HK1210542B - Single ultra-planar wafer table structure for both wafers and film frames - Google Patents

Abstract

A wafer table structure providing a single wafer table surface suitable for handling both wafers and film frames includes a base tray having a set of compartments formed therein by way of a set of ridges formed in or on an interior base tray surface,a hardenable fluid permeable compartment material disposed within the set of base tray compartments,and a set of openings formed in the base tray interior surface by which the hardened compartment material is exposable to negative or positive pressures. The base tray includes a first ceramic material (e.g., porcelain), and the hardenable compartment material includes a second ceramic material. The base tray and the compartment material are simultaneously machinable by way of a standard machining process to thereby planarize exposed outer surfaces of the base tray and the hardened compartment material at an essentially identical rate for forming a highly or ultra-planar wafer table surface.

Description

Single hyperplane wafer table structure for wafer and film frame

Technical Field

The present disclosure relates generally to systems and methods for handling and aligning semiconductor wafers and film frames carrying all or a portion of the semiconductor wafers. More particularly, aspects of the present disclosure relate to single or unified high planarity or hyperplane porous wafer table structures configured to handle wafers and film frames in a manner that facilitates accurate, high throughput wafer and/or film frame handling or processing operations, such as optical inspection processing.

Background

Semiconductor wafer processing operations include performing various types of processing steps or processing sequences on a semiconductor wafer on which a plurality of dies (e.g., a large or very large number of dies) are present. The geometry, line width, or characteristic dimensions of devices, circuits, or structures on each die are typically very small (e.g., on the micron, submicron, or nanometer scale). Any given die includes a large number of integrated circuits or circuit structures that are fabricated, processed, and/or patterned layer-by-layer, e.g., by means of processing steps performed on a wafer placed on a flat wafer surface, such that the die carried by the wafer are collectively subjected to the processing steps.

Various semiconductor device processing operations involve multiple handling systems that perform wafer or film frame handling operations involving securely and selectively transporting a wafer or wafer mounted on a film frame (hereinafter referred to simply as a "film frame") from one location, place, or destination to another location, place, or destination and/or holding a wafer or film frame in a particular location during a wafer or film frame processing operation. For example, before starting the optical inspection process, the handling system must take a wafer or film frame from a wafer or film frame source, such as a wafer cassette, and transfer the wafer or film frame to the wafer table. The wafer table must hold the wafer or film frame firmly to its surface before the inspection process is started and must release the wafer or film frame from its surface after the inspection process is completed. Once the inspection process is complete, the handling system must retrieve the wafer or film frame from the wafer table and transfer the wafer or film frame to the next destination, such as a wafer or film frame cassette or another processing system.

Various types of wafer handling systems and film frame handling systems are known in the art. Such handling systems can include one or more mechanical or robotic arms configured to perform wafer handling operations (which involve transferring wafers to and retrieving wafers from a wafer table); or to perform film frame handling operations (which involve transferring the film frame to the wafer table and retrieving the film frame from the wafer table). Each robotic arm includes an associated end effector configured to acquire, pick, hold, transfer and release a wafer or film frame by means of application and discontinuation of vacuum forces to portions of the wafer or film frame in a manner understood by those skilled in the art.

The wafer table itself can be considered or defined as a handling system that must reliably, securely, and selectively position and hold a wafer or film frame on the wafer table surface while moving the wafer or film frame relative to elements of the processing system (e.g., corresponding to one or more image capture devices and one or more light sources of an optical inspection system). The structure of the wafer table can significantly impact whether the inspection system can achieve a high average inspection throughput as described in more detail below. In addition, the structure of the wafer table greatly affects whether the optical inspection process can reliably produce accurate inspection results, in relation to the physical properties of the wafer and the physical properties of the film frame.

With respect to the generation of accurate inspection results, the wafer or film frame must be securely held on the wafer table during the optical inspection process. Furthermore, the wafer table must arrange and maintain the upper or top surface of the wafer or film frame in the same inspection plane so that all or as much of the surface area of the wafer die as possible are located together on the same plane with minimal or negligible deviation. More specifically, proper or accurate optical inspection of the die at very high magnification requires that the wafer table be very flat, preferably with an error margin in planarity of the wafer table that is less than 1/3 of the depth of field of the image capture device. If the depth of field of the image capture device is, for example, 20 μm, the corresponding wafer table planarity error cannot exceed 6 μm.

This planarity requirement becomes critical in order to handle very small (e.g., 0.5 x 0.5mm or less) and/or thick (50 μm or less-e.g., carried by very thin and/or flexible wafers or substrates) die. For very thin wafers, it is important that the wafer table be ultra-flat, otherwise one or more dies on the wafer or film frame are easily positioned out of depth of field. Those skilled in the art will appreciate that the smaller the die, the higher the magnification required, and thus the narrower the band of depth of field in which the inspection plane is located.

With planarity as outlined above, a wafer placed on the wafer table will lie flat on the wafer table surface, the wafer squeezing out almost all the air underneath it. The difference in atmospheric pressure between the top and bottom surfaces of the wafer when the wafer is disposed on the wafer table results in a large force being exerted on the top surface of the wafer due to the atmospheric pressure, while holding the wafer strongly or rather strongly on the wafer table. Since the pressure is a function of the surface area, the larger the size of the wafer, the greater the force exerted downward on the wafer. This is commonly referred to as "intrinsic suction" or "natural suction" on the wafer. The flatter the wafer table surface, the stronger the natural suction force, up to the limit defined by the finite surface of the wafer. However, the strength of such suction depends on the flatness of the wafer stage. Some wafer tables are not as flat and may have other grooves or holes on their surface, resulting in reduced suction. Despite such natural suction, it is ensured that the wafer remains as flat as possible and does not move during inspection because the wafer table will repeatedly accelerate over short distances during inspection of each die, and a large vacuum force is typically applied by the wafer table to the wafer table surface to reach the underside of the wafer.

Different types of wafer table structures have been developed in an attempt to securely hold a wafer or film frame during a wafer or film frame inspection operation and to reliably hold a maximum number of dies on the same plane during the inspection operation. However, none of the designs would allow a wafer handling system to handle wafers and cut wafers mounted on film frames without one or more of the problems described below. Each type of existing design and its associated problems will be briefly described.

Several types of wafer chucks have been or are currently being used. In the past, wafers were small (e.g., 4, 6, or 8 inches) and significantly thicker (particularly compared to their overall surface area, e.g., based on wafer thickness normalized by wafer surface area), resulting in larger per die sizes. Current wafer sizes are typically 12 or 16 inches and the thickness of these processed wafers decreases with increasing size and die size (e.g., 0.5-1.0 square millimeters), respectively (e.g., typically, for a 12 inch wafer, the thickness is 0.70-1.0 mm before thinning/backgrinding/backpolishing and 50-150 μm after thinning/backpolishing). It can be expected that the standard wafer size increases further over time. Furthermore, it can be expected that wafers to be processed are becoming thinner each year in response to the increasing demand and demand by electronic device and mobile phone manufacturers to embed thinner die/thinner components into thin electronic devices (e.g., flat panel televisions, mobile phones, notebook computers, tablet computers, etc.). These factors, which lead to increasing deficiencies in current designs of wafer tables for handling wafers and film frames, are described below.

Historically, even today, many wafer clamps are made of metal, such as steel. Such metal wafer clamps embed a network of trenches (typically circular trenches) that intersect with trenches that radiate linearly from a central location. By such grooves, vacuum forces can be applied to the underside of the wafer intersecting the wafer table surface, thereby facilitating secure retention of the wafer relative to the wafer table surface. In many wafer table designs, such grooves are arranged in concentric circles of increasing size. Depending on the size of the wafer, when the wafer is placed on the wafer table surface, the wafer will cover the one or more grooves. The vacuum can be activated through the trenches covered by the wafer to hold the wafer down during processing operations (e.g., wafer inspection operations). After inspection, the vacuum is deactivated and the ejector pins are employed to lift the wafer off the wafer table surface so that the wafer can be accessed or removed by the end effector. Because there are linear grooves radiating from the center of the metal wafer table surface, once the vacuum is deactivated, the residual suction force associated with the application of the vacuum force to the underside of the wafer quickly disappears. Thicker wafers are more suitable for application of a significant force applied through the pop-pins to lift the wafer (and resist any residual suction if present) without breaking.

As noted above, wafers are increasingly being manufactured today that are thinner or thinner than before (e.g., current wafer thicknesses can be as thin as 50 μm), and the size of each die thereon is also increasingly shrinking from the past (e.g., 0.5mm square). Advances in technology have resulted in smaller die sizes and thinner dies, which have resulted in problems handling wafers with existing wafer table designs. Typically, a back-ground/thinned or diced wafer (hereinafter "diced wafer") having very small-sized and/or very thin dies is mounted on a film frame for processing. Conventional metal wafer tables are not suitable for use with a film frame to which the diced wafers are mounted for a number of reasons.

It is noted that inspection of a die involves very high magnifications, the higher the magnification, the narrower the acceptable depth of field, range, variation, or tolerance that will be used for accurate inspection. Die that are not on the same plane may not be within the depth of field of the image capture device. As described above, the depth of field of modern image capture devices for wafer inspection typically ranges from 20-70 μm or less depending on the magnification. The presence of grooves on the wafer table surface can be problematic, particularly during inspection of diced wafers (small die size) mounted on a film frame on such systems.

The presence of the grooves results in the diced wafer with smaller die size not being properly or uniformly placed on the wafer table surface. In particular, in areas where there are trenches (and can be many trenches), the diaphragms of the diaphragm holders can hang slightly into the trenches, resulting in a lack of global or uniform planarity across the wafer surface across all dies, which is important for optical inspection operations. The lack of planarity is more pronounced for small or very small die of the diced wafer. Furthermore, the presence of the grooves enables the dies to be placed at an angle with respect to the same die inspection plane, or to fall into and lie on one or more different and lower planes. In addition, light falling onto the tilted die in the trench will reflect from the image capture device such that the image capture corresponding to the tilted die will not include or convey the precise details and/or features of one or more regions of interest on the die. This will adversely affect the quality of the images captured during the examination, which can lead to inaccurate examination results.

A number of previous approaches have attempted to address the foregoing problems. For example, in one approach, the metal wafer table support comprises a network of grooves. A flat metal mesa is placed on top of the trench network. The metal plate includes many small or very small vacuum holes that allow a vacuum to be applied to the wafer or diced wafer through the holes. Depending on the size of the wafer under consideration, an appropriate pattern or number of corresponding trenches will be activated. While multiple small or very small vacuum holes can increase the likelihood of holding the die together on the same inspection plane, the overall die planarity issue is still not effectively or completely eliminated due to continued technological developments that result in smaller and smaller die sizes and smaller die thicknesses. Such designs also include sets of triplets of pop-pins corresponding to different wafer sizes, i.e., sets of triplets of pop-pins corresponding to different sets of standard wafer sizes that the wafer table is capable of carrying. Multiple holes for the pop-pins can also be present and, for reasons similar to those described above, the overall die planarity issue can be more severe when inspecting die carried on the film frame.

Some manufacturers use a wafer table conversion kit in which a grooved metal wafer table is used to handle the entire wafer and a metal wafer table cover with many very small openings is used to handle the film frame. Unfortunately, the conversion kit requires inspection system down time because the conversion from one type of wafer table to another and the wafer table calibration after conversion is time consuming and needs to be done manually. Such downtime can have a detrimental effect on average system throughput (e.g., overall or average throughput associated with sequential or co-considering wafer and film frame inspection operations), and thus it is undesirable to require an inspection system for a wafer table conversion kit.

Other wafer table designs, such as that described in U.S. patent 6513796, involve a wafer pedestal that allows a different central wafer table insert depending on whether the wafer is currently being processed or the film frame. For wafer inspection, the insert is typically a metal plate with an annular ring having vacuum holes for initiating a vacuum. For membrane frame inspection, the interposer is a metal plate with many micro holes for vacuum activation, which still leads to the overall die non-planarity problem as described above.

Another wafer table design, such as U.S. patent application publication 2007/0063453, uses a wafer table having a plate-type insert constructed of a porous material in which annular rings made of a thin film material are used to define the various zones. In general, such wafer table designs are complex in construction and involve specialized and complex processes, so their manufacture is difficult, time consuming, or costly. In addition, such a design enables the use of a metallic annular ring to achieve control of the area vacuum force on the wafer table surface as a function of wafer size. The metal annular ring can require undesirably long planarization times or damage the polishing apparatus used to polish the wafer table surface while planarizing the wafer table surface. In addition, the metal ring can cause non-planarity problems due to different material polishing characteristics of the wafer table surface, and therefore the metal ring is not suitable for modern optical inspection processes (e.g., optical inspection processes particularly involving post-dicing wafers mounted on a film frame).

Unfortunately, past wafer table designs (a) make the structure unnecessarily complex due to insufficient wafer table surface flatness uniformity that arises in view of the technological developments that continue to result in smaller and smaller wafer die sizes and/or tapering of wafer thicknesses; (b) it is difficult, expensive or time consuming to manufacture; and/or (c) not suitable for various types of wafer processing operations (e.g., die inspection operations, particularly when the die are carried by a film frame). There is clearly a need for a wafer table structure and associated wafer table fabrication techniques that will enable a wafer table to handle both wafers and cut wafers that overcomes one or more of the aforementioned problems or deficiencies.

Disclosure of Invention

According to an aspect of the present disclosure, a single wafer table structure provides a wafer table surface suitable for handling wafers and film frames on which the wafers or portions thereof are mounted. The wafer table structure includes a substrate tray including a first set of exposed upper surfaces, an inner surface, and a set of compartments integral with or attached to the inner surface, the substrate tray being formed of at least one type of material that is permeable to a gas or fluid in response to an applied negative pressure; at least one type of compartment material disposed within a set of substrate tray compartments, the at least one type of compartment material conforming to the set of compartments and being hardenable to provide a hardened compartment material in the set of compartments that is permeable to gases or fluids in response to applied vacuum forces, and the hardened compartment material providing a second set of exposed upper surfaces; and a set of openings formed in an inner surface of the substrate tray through which the hardened compartment material can be exposed to a negative or positive pressure, wherein (a) a first set of exposed upper surfaces of the substrate tray and (b) a second set of exposed upper surfaces of the hardened compartment material can be simultaneously processed by means of a common processing treatment to provide a planar wafer table surface (e.g., a hyperplane surface having a planarity uniformity of ± 100 μm or less across the wafer table surface) for carrying wafers and film frames. At least one of the base tray and the hardened cell material comprises a ceramic-based material.

The rate at which the first set of exposed upper surfaces of the substrate tray can be planarized by the common process and the rate at which the second set of exposed upper surfaces of the hardened compartment material can be planarized by the common process are substantially the same (e.g., within 5-20% or within 10%).

The set of compartments can include a plurality of compartments, and the wafer table structure further includes a set of ridges separating each compartment within the plurality of compartments from one another. The first set of exposed upper surfaces of the base tray includes exposed upper surfaces of the set of ridges. The base tray and each ridge within the set of ridges can be formed of the same or different materials. The base tray interior surface includes a plurality of interior bottom surfaces. Each ridge within the set of ridges borders an inner bottom surface of the base tray, and each ridge within the set of ridges divides portions of different base tray inner bottom surfaces from each other to define the set of compartments. The dimensions of each ridge within the set of ridges and each compartment within the set of compartments are determined in a manner correlated to a standard wafer size and/or a standard film frame size.

In an embodiment, the set of compartments includes a first compartment containing a first volume of hardened compartment material exposed to a first set of openings corresponding thereto; and a second compartment comprising a second volume of compartment material exposed to a second set of openings corresponding thereto, the second set of openings being different from the first set of openings. A first ridge within the set of ridges surrounds the first compartment, thereby separating the first compartment from the second compartment. A negative pressure can be applied to the first set of openings to securely hold a first wafer or a first film frame having a first standard diameter to the planar wafer table surface, and wherein the negative pressure can be applied to the first set of openings and the second openings to securely hold a second wafer or a second film frame having a second standard diameter greater than the first standard diameter to the planar wafer table surface.

The set of compartments can also include a third compartment containing a third volume of hardened compartment material exposed to a third set of openings corresponding thereto, the third set of openings being different from each of the first and second sets of openings. A second ridge within the set of ridges surrounds the second compartment, thereby separating the second compartment from the third compartment. Negative pressure can be applied to the first, second, and third sets of openings to securely hold a third wafer or a third film frame having a third gauge diameter that is larger than each of the first and second gauge diameters to the planar wafer table surface.

The wafer table structure can also include a single set of pop-pin guide members through which a single set of pop-pins can travel to handle multiple standard size wafers.

According to another aspect of the present disclosure, a process of fabricating a single wafer table structure providing a wafer table surface suitable for handling a wafer and a film frame on which the wafer or a portion thereof is mounted, comprises: providing a substrate tray having a first set of exposed upper surfaces, an interior surface and a set of compartments formed integrally with or attached to the interior surface, and at least one set of openings formed in the interior surface, the substrate tray being formed of at least one material that is permeable to a gas or fluid in response to an applied negative or positive pressure; disposing at least one type of compartment material within the set of base tray compartments, the at least one type of compartment material conforming to the set of compartments; hardening the at least one type of compartment material to provide a hardened compartment material in the set of compartments that is permeable to gas or fluid in response to the applied vacuum force, and the hardened compartment material provides a second set of exposed upper surfaces; and simultaneously machining the first set of exposed upper surfaces and the second set of exposed upper surfaces by means of a common machining process to provide a planar wafer table surface for carrying a wafer and a film frame on which the wafer or a portion thereof is mounted. During such processing, the rate of planarizing the first set of exposed upper surfaces of the substrate tray and the rate of planarizing the second set of exposed upper surfaces of the hardened compartment material are substantially the same using the common processing treatment.

Drawings

Fig. 1A is a schematic diagram illustrating a portion of a wafer and/or film frame handling system that provides a single multi-aperture wafer table structure for handling wafers and film frames, according to an embodiment of the present disclosure.

Fig. 1B is a schematic diagram illustrating a portion of a wafer and/or film frame handling system that provides a single multi-aperture wafer table structure for handling wafers and film frames, according to an embodiment of the present disclosure.

Fig. 2A is a perspective view of a wafer table chassis comprising a non-porous material, such as a ceramic-based non-porous material, according to an embodiment of the present disclosure.

Fig. 2B is a perspective cross-sectional view of the chassis of fig. 2A taken along line a-a'.

Fig. 3A is a perspective view of the chassis of fig. 2A with a moldable, conformable, or flowable porous material, such as a ceramic-based porous material, disposed therein.

Fig. 3B is a perspective cross-sectional view of a chassis carrying moldable, conformable, or flowable ceramic-based porous material corresponding to fig. 3A taken along line B-B'.

Figure 3C is a cross-sectional view of a vacuum chuck structure after planarization corresponding to the chassis carrying hardened porous ceramic material of figures 3A and 3B.

Fig. 3D is a cross-sectional view of a vacuum chuck structure corresponding to fig. 3C and carrying a wafer or film frame on a planar vacuum chuck surface, produced or manufactured in accordance with an embodiment of the present disclosure.

Fig. 3E is a perspective view of a representative first wafer having a first standard diameter (e.g., 8 inches) disposed on a vacuum chuck structure, in accordance with an embodiment of the present disclosure.

Fig. 3F is a perspective view of a representative second wafer having a second standard diameter (e.g., 12 inches) disposed on a vacuum chuck structure, in accordance with an embodiment of the present disclosure.

Fig. 3G is a perspective view of a representative third wafer having a third standard diameter (e.g., 16 inches) disposed on a vacuum chuck structure, in accordance with an embodiment of the present disclosure.

Fig. 4A is a perspective view of a ceramic-based vacuum chuck chassis including a set of pop-pin guide members according to another embodiment of the present disclosure.

Fig. 4B is a cross-sectional view of the ceramic-based vacuum chuck base plate of fig. 4A taken along line C-C'.

Fig. 5A is a perspective view of the chassis of fig. 2A and 2B with a moldable, conformable, or flowable ceramic-based porous material disposed therein.

Fig. 5B is a perspective cross-sectional view of a tray carrying moldable, formable, or flowable ceramic-based porous material corresponding to fig. 5A taken along line D-D'.

Fig. 6 is a flow chart of a representative process of manufacturing a vacuum chuck structure according to an embodiment of the present disclosure.

Figure 7 is a cross-sectional view of a vacuum chuck structure showing an initial volume of moldable ceramic-based porous material slightly beyond the capacity of the chassis before planarization is complete, in accordance with an embodiment of the present disclosure.

Detailed Description

In the present disclosure, consideration or use of a particular element number in a particular figure or reference in a description of a given element or corresponding descriptive material can encompass the same, equivalent, or similar element or element number identified in another figure or descriptive material associated therewith. The use of "/" in the figures or associated text is understood to mean "and/or" unless stated otherwise. Recitation of specific values or ranges of values herein is understood to not include, or be interpreted as, recitation of approximate values or ranges of values (e.g., within 20%, 10%, or 5%). Similarly, references to being equal, substantially equal, or substantially equal are understood to encompass actual equality as well as substantially or substantially equal (e.g., equal within 20%, ± 10%, or ± 5%)

As used herein, the term "group" corresponds to or is defined as a non-empty Finite organization of elements mathematically representing a cardinality of at least 1 (i.e., a group as defined herein can correspond to a unit, a single state or a single element group or a plurality of element groups) according to known Mathematical definitions (e.g., in a manner corresponding to that described in the following documents, the anti-introduction to physical reading of the Cambridge university Press, of Peter J. Eccles, 1998, "Chapter11: Properties of Fine Sets" (e.g., as described on page 140)). In general, elements of a group can include, or be a system, device, apparatus, structure, object, process, physical parameter or value depending on the type of group under consideration.

For purposes of brevity and to facilitate understanding, the term "wafer" as used herein can encompass an entire wafer, a portion of a wafer, or other type of whole or partial object or component (e.g., a solar cell) having one or more planar surface areas on which a set of optical inspection and/or other processing operations are desired or required. The term "film frame" in the following description generally denotes a support member or frame configured to carry or support a wafer, thinned or backlapped wafer or diced wafer, for example by means of a thin layer or film of material disposed or stretched across a surface region of the film frame, and to which the wafer is mounted or adhered in a manner understood by those skilled in the art.

Further, the term "wafer table" as used herein includes apparatus for holding a wafer or film frame during a wafer inspection process or film frame inspection process, respectively, wherein the term "wafer table" will be understood by those skilled in the art to correspond, be equivalent, be substantially equivalent, or be similar to a wafer chuck, vacuum table, or vacuum chuck. The term "non-porous material" as used herein is intended to mean a material that is at least substantially or essentially impermeable to the flow or transmission of a fluid, such as air or a liquid, therethrough, and thus is at least substantially or essentially impermeable to the communication or transmission of negative pressure or vacuum forces therethrough (e.g., for a non-porous material of a given depth or thickness, such as a depth greater than about 0.50-1.0 mm). Similarly, the term "porous material" is intended to mean a material that is at least substantially or essentially permeable to the flow or transmission of a fluid, such as air or a liquid, therethrough, and thus at least suitably/substantially or essentially permeable to the communication or transmission of negative pressure or vacuum forces therethrough (e.g., for a porous material of a given depth or thickness, such as a depth greater than about 0.50-1.0 mm). Finally, the terms "ceramic-based" and "ceramic-based material" in the context of the present disclosure are intended to denote a material that is monolithic or substantially ceramic in terms of its material structure and properties.

Embodiments according to the present disclosure relate to systems and processes for handling wafers and film frames that provide a single or unified porous wafer table configured to handle wafers and film frames in a manner that facilitates or enables accurate, high throughput wafer and/or film frame handling or processing operations (e.g., inspection (e.g., optical inspection) processing).

A high planarity or hyperplane wafer table according to the present disclosure can be used in association with or form part of a system that handles wafers and film frames (e.g., an inspection system as described in detail below). While various embodiments according to the present disclosure relate to wafer and film frame inspection systems (e.g., optical inspection systems), several embodiments according to the present disclosure can additionally or alternatively be configured to support or perform other types of wafer and/or film frame front-end or back-end processing operations (e.g., testing operations). For the sake of brevity and to facilitate understanding, aspects of representative embodiments according to the present disclosure are described in detail below in a manner that will primarily emphasize inspection systems.

By virtue of the single or unified wafer table being configured to handle both wafers and film frames, embodiments according to the present disclosure eliminate the need for or the elimination of a wafer table conversion kit, thus eliminating production downtime due to wafer-to-film frame and film frame-to-wafer conversion kit exchanges and calibration operations, thereby enhancing average inspection process throughput. A single or unified wafer table according to embodiments of the present disclosure facilitates or enables high accuracy inspection operations by: a wafer table surface with a high or very high degree of planarity is provided that maintains the wafer die surface on a common inspection plane with minimal or negligible deviation from the wafer table surface along a direction parallel to a normal axis of the highly planar wafer table surface.

Aspects of representative System configurations and System elements

Fig. 1A is a block diagram of a system 200 for handling wafers 10 and film frames 30, the system 200 including a wafer table assembly 610 that may be coupled to, carrying, or have a single or unified wafer table 620, the wafer table 620 providing a wafer table surface 622 exhibiting high, very high, or ultra-high planarity (e.g., planarity within ± 200 μ ι η, or ± 100 μ ι η, or ± 50 μ ι η), the surface 622 configured to handle wafers and film frames by an inspection system 600 (e.g., during an inspection process, e.g., during a wafer inspection process and a film frame inspection process, respectively), according to a representative embodiment of the present disclosure. In the exemplary, non-limiting embodiment, system 200 further includes a first handling subsystem 250 and a second handling subsystem 300 configured to (a) transfer wafers 10 and film frames 30 to inspection system 600 and transfer wafers 10 and film frames 30 from inspection system 600. The system 200 can also include additional elements, for example, elements configured to perform the following operations: (b) wafer rotational misalignment correction and wafer non-planarity repair with respect to the film frame as part of a pre-inspection handling operation and/or lateral displacement prevention as part of a post-inspection handling operation are provided as described in U.S. provisional patent application 61/696051 filed on month 8 and 31 2012 as a priority of the present application.

Depending on whether the wafer 10 or the film frame 30 is being inspected at a given time, the system 200 includes a wafer source 210, such as a wafer cassette, or a film frame source 230, such as a film frame cassette, respectively. Similarly, if the wafer 10 is inspected, the system 200 includes a wafer destination 220, such as a wafer cassette (or a portion of a processing station); and if the film frame 30 is inspected, the system 200 includes a film frame destination 240 that can be a film frame cassette (or part of a processing system). The wafer source 210 and the wafer destination 220 can correspond to or be the same location or structure (e.g., the same cassette). Similarly, the film frame source 220 and film frame destination 240 can correspond to or be the same location or structure (e.g., the same film frame cassette).

In the exemplary embodiment under consideration, the system 200 further includes a wafer pre-alignment or alignment station 400 configured to establish an initial or pre-inspection alignment of the wafer 10 such that the wafer 10 is properly aligned relative to the inspection system 600; a rotational misalignment inspection system 500 configured to receive, acquire, determine, or measure a rotational misalignment direction and a rotational misalignment magnitude (e.g., capable of being indicated by a rotational misalignment angle) corresponding to a wafer 10 mounted on a film frame 30; and a control unit 1000 configured to manage or control aspects of system operation (e.g., via execution of stored program instructions), as will be described in detail below. The control unit 1000 can include or be a computer system or computing device that includes a processing unit (e.g., a microprocessor or microcontroller), memory (e.g., including fixed and/or removable Random Access Memory (RAM)) and Read Only Memory (ROM)), a communication source (e.g., standard signaling and/or network interfaces), a data storage source (e.g., hard disk, optical disk, etc.), and a display device (e.g., flat panel display).

In various embodiments, system 200 additionally includes a support structure, base, chassis, or chassis coupled to or configured to support or carry at least second handling subsystem 300, such that second handling subsystem 300 is capable of forming an operational interface with first handling subsystem 250 and processing system 600 to facilitate wafer or film frame handling operations. In some embodiments, support structure 202 supports or carries each of first handling subsystem 250, second handling subsystem 300, wafer alignment station 400, misalignment inspection system 500, and inspection system 600.

Fig. 1B is a block diagram of a system 200 for handling wafers 10 and film frames 30 according to another embodiment of the present disclosure, the system 200 providing a single or unified wafer table 620 configured to handle wafers and film frames during inspection by an inspection system 600, and further providing a first handling subsystem 250 and a second handling subsystem 300. In this embodiment, the wafer source 210 and the wafer destination 230 are the same (e.g., the same cassette); and the film frame source 220 and film frame destination 240 are the same (e.g., the same film frame cassette). Such an embodiment can provide a smaller or significantly reduced space contact area, resulting in a compact, space efficient system 200.

In yet another exemplary embodiment, the inspection system 600 is configured to perform 2D and/or 3D optical inspection operations with respect to the wafer 10 and the film frame 30. The optical inspection system 600 can include a plurality of illumination sources, an image capture device (e.g., a camera) configured to capture images and generate image data sets corresponding thereto, and optical elements configured to perform some or each of the following processes in a manner understood by those skilled in the art: directing illumination toward the wafer 10, directing illumination reflected from the wafer surface toward a particular image capture device, reflecting or applying an optical effect (e.g., filtering, focusing, or collimating) on illumination incident on and/or reflected from the wafer surface. The optical inspection system 600 further includes or is configured to communicate with a processing unit and memory by executing stored program instructions to analyze the image data set and generate an inspection result. As previously described, the system 600 can include or alternatively be another type of processing system.

With further reference to fig. 1C, a wafer table 620 carried by wafer table assembly 610 provides an outer or exposed wafer table surface 622 of high planarity or hyperplane on which wafer 10 and film frame 30 can be disposed or placed and securely held or retained such that wafer die 12 are along a normal axis Z orthogonal to a midpoint, center of drawing or approximate midpoint, center or drawing center of wafer table surface 622 defined as the wafer table surface 622 of high planarity_wtThe parallel directions are maintained entirely on the common examination plane with minimal or negligible plane deviation. Wafer table assembly 610 is configured to selectively or controllably displace wafer table 620, and thus, relative to axis Z, along each of the axes corresponding to or defining a plane_vtTwo transverse spatial axes of traverse (e.g., wafer table X and y axes X, respectively)_vtAnd Y_vt) Carrying or securely holding any wafer 10 or film frame 30.

The wafer table 620 is configured to selectively and securely hold or retain the wafer 10 or film frame 30 on the wafer table surface 622 by a combination of: (a) an inherent or natural suction force that exists due to a pressure differential between atmospheric pressure acting on the top, upper or exposed surface of the wafer and the bottom or underside of the wafer; and (b) selectively controlling the application of vacuum force or negative pressure to the underside of the wafer 10. The wafer table 620 can be further configured to apply positive air pressure to the wafer 10 or film frame 30, for example, by applying or delivering a short/transient (e.g., approximately 0.50 seconds or 0.25-0.75 seconds) positive air pressure jet (e.g., a blow) to the interface between the wafer table surface 622 and the underside of the wafer 10 or film frame 30, after the applied vacuum force is discontinued or stopped, in order to relieve the vacuum suction force acting on the wafer 10 or film frame 30 from the wafer table surface 622.

In various embodiments, the wafer table assembly 610 includes a set of pop-pins 612 that can be selectively or controllably oriented in a perpendicular direction (parallel to or along the wafer table Z-axis Z) relative to the wafer table surface 622_wt) Up-shift to vertically shift the wafer 10 or film frame 30 relative to the wafer table surface 622. In various embodiments, the wafer table 620 includes a single set of pop-pins 612 (e.g., three pop-pins) configured to handle a plurality of standard size wafers 10 (e.g., 8 inch, 12 inch, and 16 inch wafers 10). The wafer table 620 need not include and additional sets of pop-pins 612 (e.g., additional sets of three pop-pins) can be omitted or not included due to the positioning of a single set of pop-pins 612 on the wafer table 620 (e.g., positioned to carry an 8-inch wafer somewhat near, substantially near, or near its perimeter). As described in detail below, in several embodiments, although the pop-pins 612 can be used in connection with the transfer of the wafer 10 to the wafer table 620 and from the wafer table 620, there is no need to involve the transfer of the film frame 30 to the wafer table 620 and/or from the wafer table 620, and the use of the pop-pins 612 can be omitted or eliminated entirely.

In various embodiments, the wafer table 620 includes or has the same, essentially the same, substantially the same, or similar structure as the wafer table structure described below with reference to fig. 2A-7.

Aspects of a representative unified wafer table structure for wafer and film frame handling

In embodiments according to the present disclosure, the wafer table structure can include a base tray (or base, frame, form, library, or storage structure) having a plurality of ridges (e.g., can include or be protrusions, ridges, raised bars, dividers, corrugations, creases, or folds) integrally formed from or attached to an interior or base surface of the wafer table structure (e.g., the bottom of the base tray). In various embodiments, the substrate tray can include at least one type of non-porous material (e.g., a ceramic-based material). The substrate tray is intended to be impermeable to a gas or fluid (e.g., air), or substantially impermeable to a gas or fluid, in response to application of a vacuum force. That is, a non-porous material is intended to be impermissible or substantially impermissible to the passage of gas, fluid, or vacuum forces in response to an applied vacuum force. The non-porous material is further intended to be easily machinable, easily sandable or easily ground by common techniques and equipment (e.g., conventional sanding wheels). In various embodiments, the non-porous material can comprise or be porcelain.

The ridges define, delineate, divide, or segregate the substrate tray into a plurality of compartments, chambers, cell structures, open areas, or recesses into which at least one type of moldable, formable, conformable, or flowable porous material can be introduced, provided, deposited, or poured and cured or hardened. The porous material can be further securely bonded (e.g., chemically bonded (e.g., associated with a hardening, curing process)) or adhered to the substrate tray compartment such that the hardened porous material is securely retained within or bonded to the compartment. Additionally or alternatively, the ridges can be shaped such that the porous material when hardened or cured within the compartment is securely held therein by the structure of the ridges. The ridges can be structured to include curved and/or overhanging portions, or have other suitable shapes, as desired or required.

The porous material within the compartment is intended to allow the passage of a gas or fluid (e.g., air) in response to the application of a vacuum force thereto, such that the gas, fluid, or vacuum force can be communicated or transmitted therethrough (e.g., after having been cured or hardened and applied with a vacuum force). Furthermore, the porous material is intended to be easily machined, ground or ground by common techniques and equipment (e.g., conventional grinding wheels).

The choice of non-porous substrate tray material for the wafer table structure and/or the porous material introduced into the substrate tray compartment depends on the desired or required characteristics of the wafer table structure in relation to the application or process to be performed on the wafer 10 or film frame 30 to be placed thereon. For example, optical inspection of small or ultra-small dies 12 of a large diameter diced wafer 10 carried by a film frame 30 requires that the wafer table structure provide a wafer table surface with very high or ultra-high planarity. Furthermore, the selection of the non-porous base tray material and/or the porous compartment material can depend on the chemical, electrical/magnetic, thermal or acoustic requirements that the wafer table structure should meet in view of the anticipated or desired type of wafer or film frame processing conditions to which the wafer table structure will be exposed.

In various embodiments, the non-porous substrate tray material and the porous compartment material are selected to be implemented based on material properties or qualities that will facilitate or enable the implementation of abrading or grinding on multiple exposed surfaces of at least two distinguishable or different materials utilizing a single abrading or grinding device (e.g., substantially simultaneously). More particularly, the exposed surfaces of two (or more) distinguishable or different non-porous and porous materials can be processed, ground or sanded simultaneously in the same manner (e.g., by means of standard processing, grinding or sanding equipment involving operations in accordance with standard processing, grinding or sanding techniques). Such machining, grinding or abrading of each of the non-porous and porous materials results in less, minimal or negligible damage to the machining, grinding or abrading element, device or tool, such as the abrading head. Further, in various embodiments, the non-porous substrate tray material and the porous compartment material are selected such that the rate at which the non-porous substrate tray material is affected (e.g., planarized) by such processing, grinding or abrading is substantially the same as the rate at which the porous compartment material is affected (e.g., planarized) by such processing, grinding or abrading.

For purposes of brevity and ease of understanding, in the representative embodiments of the wafer table structures described below, the non-porous substrate tray material comprises a non-porous material that is either ceramic-based, and the porous cell material comprises a porous material that is either ceramic-based. Those skilled in the art will appreciate that wafer table structures according to embodiments of the present disclosure are not limited to the types of materials provided in connection with the representative embodiments described below.

When it is desired or required to produce a very flat, highly planar or hyperplane wafer table surface, the porous material can comprise a moldable ceramic-based porous material and/or other compounds suitable for forming, fabricating or producing a porous wafer table, wafer chuck, vacuum table or vacuum chuck in a manner understood by those skilled in the art in accordance with standard/conventional processing techniques, processing sequences or processing parameters (e.g., hardening temperature or temperature range and corresponding hardening time or time interval). In various embodiments, the porous material can comprise or be a commercially available material provided by CoorsTek (CoorsTek inc., Hillsboro, ORUSA, 503-. Such porous materials can include one or more types of ceramic-based materials, for example, alumina (Al)₂O₃) And silicon carbide (SiC), and can exhibit a post-hardening/post-curing pore size in the range of about 5-100 μm (e.g., about 5, 10, 30, or 70 μm) and a porosity in the range of about 20-80% (e.g., about 30-60%). The pore size of the porous compartment material can be selected based on application requirements, such as a desired or required level of vacuum force, suitable for the application in question (e.g., inspection of thin or very thin wafers 10 on the membrane frame 30), as will be understood by those skilled in the art. It can be a process (e.g., by means of a unified or individual machining or grinding process) corresponding to working (e.g., by means of a uniform or individual machining or grinding process) a portion of the ceramic substrate tray (e.g., the set of ridges and possibly also the outer substrate tray edge) and the exposed upper or outer surface of the hardened moldable porous ceramic material carried by the substrate tray compartment to provide a common wafer table surface exhibiting very high or ultrahigh planarity or planar uniformity, which is suitable for securely holding a wafer or film frame, for example, during inspection, in a manner that efficiently arranges or holds the wafer die surface along or within the common plane (normal axis perpendicular to the wafer table surface) with minimal or negligible deviation.

Fig. 2A is a perspective view of a ceramic-based substrate tray 100, and fig. 2B is a perspective cross-sectional view of the substrate tray of fig. 2A taken along line a-a', according to an embodiment of the present disclosure. As described above, in various embodiments, the ceramic-based substrate tray 100 is non-porous or substantially non-porous, and thus is not permitted or substantially not permitted to gas, fluid, or vacuum force transmission therethrough in response to an applied vacuum force. That is, the ceramic-based substrate tray 100 is generally intended to serve as an impermeable barrier that is strong, very strong, or effective to the communication or transmission of gas, fluid, or vacuum forces therethrough.

In an embodiment, the substrate tray 100 has a shape defining a center or centroid 104, with respect to which the vacuum openings 20 can be arranged or around which center or centroid 104; plane or transverse spatial extent or region A_T(ii) a An outer edge or boundary 106; a plurality of inner bottom surfaces 110a-c that can include a plurality of vacuum openings 20 disposed therein; and one or more ridges 120a-b (e.g., arranged in a ring or concentric circle) disposed between the center of the substrate tray and its outer edge 106. As described in detail below, in various embodiments, the ridges 120a-b and the outer edge 106 of the substrate tray are sized, shaped, and/or sized in a manner related to or corresponding to standard wafer and/or film frame sizes (e.g., 8 inch, 12 inch, and 16 inch wafers and one or more film frame sizes corresponding to such wafer sizes). The substrate tray 100 further includes at least one underside surface 150, most or all of which, in various embodiments, is disposed or substantially disposed on a single substrate tray underside plane.

In several embodiments, the vertical base tray axis Z_TCan be defined as perpendicular or substantially perpendicular to the underside surface 150 of the base tray and the inner bottom surface 110a-c of the base tray, and extends through the center or centroid 104 of the base tray. As understood by those skilled in the art, the vertical base tray axis Z_TIs defined as being perpendicular to the desired planar surface of the wafer table upon which the wafer or film frame can be securely held. In FIG. 2AAnd in FIG. 2B, Z_TCan be perpendicular to a line a-a' bisecting each vacuum opening 20.

Each ridge 102a-b borders an inner bottom surface 110a-c of the base tray 100, and each ridge 120a-b depicts, separates or partitions portions of different base tray inner bottom surfaces relative to one another to define a set of base tray compartments or bases 130a-b capable of receiving or carrying the aforementioned moldable, conformable or flowable porous materials. More specifically, in the embodiment shown in fig. 2A, the first ridge 120a extends over and surrounds (e.g., concentrically surrounds) the first inner bottom surface 110a of the base tray 100. The continuous or substantially continuous structural depression defined by the first ridge 120a surrounding or encircling the first interior bottom surface 110a thereby defines a first base tray compartment or base 130a having the first interior bottom surface 110a as its bottom surface. In a similar manner, the first and second ridges 120a, 120b extend above the second inner bottom surface 110b of the base tray 100. The second ridge 120b closes the first ridge 120a (e.g., the first and second ridges 120a-b are concentric with respect to each other) such that the first and second ridges 120a-b define a second continuous or substantially continuous base tray compartment or base 130b having the second inner bottom surface 110b as a bottom surface thereof. Also similarly, the outer edge 106 of the base tray closes the second ridge 120b (e.g., the second ridge 120b and the outer edge 106 are concentric with respect to each other) such that they define a third continuous or substantially continuous base tray compartment or base 130c having a third inner base tray surface 110c as a bottom surface thereof. Any given ridge 120 has a width across the base, such as approximately 1-4mm (e.g., approximately 3 mm); and a corresponding ridge depth, such as approximately 3-6mm (e.g., approximately 4mm), that defines the depth of the compartment or base 130. As described in detail below, in various embodiments, any given substrate tray compartment or base 130a-c has a spatial extent, planar surface area, or diameter that correlates or corresponds to a spatial extent, planar surface area, or diameter of a standard wafer and/or film frame size, shape, and/or dimension.

In alternative embodiments, similar considerations as previously described apply to the definition of additional or other types of substrate tray compartments or bases 130, such embodiments including embodiments having a single ridge 120; embodiments having more than two ridges 120 a-b; and/or embodiments in which one or more ridges 120 are not completely enclosed by each other or are not circular/concentric with respect to one or more other ridges 120 (e.g., when portions of a particular ridge 120 are arranged laterally, radially, or otherwise with respect to another ridge 120). One skilled in the art will readily appreciate the manner in which ridges 120 exhibiting various shapes, sizes, dimensions, and/or portions (e.g., the ridges 120 can include a plurality of different or separate portions arranged relative to an elliptical, circular, or other type of geometric profile or pattern) can define different types of substrate tray compartments or mounts 130.

In addition to the foregoing, the outer edge 106 of the substrate tray and each ridge 120a-b includes an exposed outer edge upper surface 108 and an exposed ridge upper surface 122a-b, respectively, which corresponds to an upper surface or side of the substrate tray 100 that is opposite the lower side surface 150 of the substrate tray and is intended to be closest to the wafer 10 or film frame 30 carried by the wafer table planar surface. In various embodiments, the vertical distance (e.g., parallel to the central transverse axis Z of the base tray) between the outer edge upper surface 108 of the base tray and the inner bottom surface 110a-c of the base tray, and between each ridge upper surface 122a-b and the inner floor surface 110a-c of the base tray_T) Defining a base tray compartment depth D_TC. The vertical distance between the outer edge upper surface 108 of the substrate tray and the underside surface 150 of the substrate tray defines the overall substrate tray thickness T_OT. Finally, the vertical distance along which the vacuum opening 20 extends can be defined to be equal to T_OTAnd D_TCVacuum channel depth D of difference therebetween_V。

Fig. 3A is a perspective view of the substrate tray 100 of fig. 2A into which a moldable, conformable, or flowable porous material has been introduced, arranged, or provided into the substrate tray 100 effective to provide for facilitating or effectuating the formation of the wafer table structure 5 or forming the wafer table structure 5 in accordance with an embodiment of the present disclosure. Fig. 3B is a perspective cross-sectional view of the substrate tray 100 carrying porous material corresponding to fig. 3A taken along line B-B'. Fig. 3C is a cross-sectional view of the substrate tray 100 carrying a porous material corresponding to fig. 3A and 3B.

In fig. 3A and 3B, the porous material can be considered to be located in substrate tray compartments 13/0a-c in either a pre-cure/pre-set or post-cure/post-set state, depending on the stage of fabrication of the wafer table structure under consideration. Furthermore, if considered in a post-cured/post-placement state, the porous material and the non-porous or vacuum non-porous ceramic-based substrate tray 100 can likewise be considered in a pre-planarization/pre-processing or post-planarization/post-processing state, depending on the stage of fabrication of the wafer table structure under consideration. The stages of a representative wafer table structure fabrication process according to embodiments of the present disclosure are described in detail below.

Considering fig. 3A-3C and in relation to the substrate tray embodiment shown in fig. 2A and 2B, after introducing, placing, depositing or providing the porous material into the substrate tray compartments 130a-C and integrating the porous material into the internal geometry of the substrate tray compartments 130a-C, the first substrate tray compartment 130a is filled with a first volume 140a of porous material; filling the second substrate tray compartment 130b with a second volume 140b of porous material; and a third base tray compartment 130c is filled with a third volume 140c of porous material. Similar considerations apply to other substrate tray embodiments having a different number and/or different configuration of compartments 130. That is, after the porous material has been introduced into the substrate tray compartments 130, each of such compartments 130 is filled with a given amount 140 of porous material corresponding to the size or volume of any given compartment 130 under consideration. The initial volume 140 of porous material introduced into any given substrate tray compartment 130 should equal or exceed the volume of the compartment so that excess porous material can be machined or ground away using a planarization process, as will be described in more detail below.

After introducing the porous material into the compartment 130, a portion of any given volume 140 of porous material is exposed to the plurality of vacuum openings 20 within the compartment 130. More specifically, within a given volume 140 of porous material, the porous material that forms an interface with the base tray inner bottom surface 110 is selectively exposed to one or more vacuum openings 20 disposed or formed within the corresponding base tray inner bottom surface 110. For example, as particularly shown in the embodiments shown in fig. 3B and 3C, the porous material of the first volume 140a is exposed to the vacuum opening 20 disposed at the center of the base tray 100 within the first inner bottom surface 110a of the first base tray compartment 130 a. Similarly, the porous material of the second volume 140b is exposed to the vacuum openings 20 disposed within the second inner bottom surface 110b of the second base tray compartment 130 b; also, a third volume 140c of porous material is exposed to the vacuum openings 20 disposed within the third inner bottom surface 110c of the third base tray compartment 130 c. Since the porous material of each volume 140a-c is exposed to a corresponding set of vacuum openings 20, the vacuum force can be selectively communicated, distributed or transmitted through the porous material of each volume 140a-c to the upper surface of the porous material corresponding to the wafer table structure 5. Thus, when the wafer table structure 5 carries a particular size or shape of the wafer 10 or film frame 30 on a planar wafer table surface, vacuum forces can be selectively communicated or transmitted to the underside of the wafer 10 or film frame 30 through the corresponding substrate tray compartment covered by the wafer 10 or film frame 30 disposed on the wafer table planar surface, as will be described in detail below.

As described above and in further detail below, after the porous material volumes 140 have been introduced into the base tray compartment 130, each such volume 140 can be hardened, cured, or bonded (e.g., integrally associated with or simultaneously with the hardening/bonding process) to the inner bottom surface 110 and the associated side surfaces or sidewalls of the one or more ridges 120 defining the compartment 130. In addition, after the hardening/bonding treatment, a single machining, grinding or abrading device can be used on two distinguishable or different material surfacesThe exposed upper surface of the wafer table structure 5, including the exposed upper surface of the porous material of the volume 140, the exposed ridge upper surface 122 and the exposed outer edge upper surface 108, is processed, lapped or planarized at the same time in one or more conventional technically simple, inexpensive and robust processing or lapping techniques or treatments. In addition, the use of a single processing, grinding or abrading apparatus enables, provides or defines a wafer table planar surface that exhibits very high or ultra-high planar uniformity. As a result, even for very small die and/or very thin wafers, the die 12 carried by the wafer 10 or film frame 30 arranged and securely held on the wafer table planar surface is held on a common plane so as to effectively hold the upper or exposed die surface on the common plane with minimal or negligible deviation. Thus, the upper surface of such a die 12 follows a normal axis (e.g., corresponding to the vertical axis Z of the substrate tray) parallel to the wafer table surface with high planarity_TWafer table vertical axis Z (overlapping or including)_WT) Exhibit a minimal or negligible positional deviation out of the common plane. The ultra-high planarity of the wafer table surface provided by embodiments according to the present disclosure enables the wafers 10 or die 12 on the film frame 12 located on the wafer table surface to lie substantially in a single plane (e.g., an inspection plane) to facilitate accurate inspection and/or other processing.

Fig. 3D is a cross-sectional view of a wafer table structure 5, produced or manufactured according to an embodiment of the present disclosure, which corresponds to fig. 3C, and which carries a wafer or film frame on a planar wafer table surface. The wafer table structure 5 provides a wafer table planar surface 190 with very high or ultra-high planar uniformity such that die 12 (e.g., very small and/or very thin die 12), devices or material layers carried by the wafer 10 or film frame 30 that are securely held on the wafer table planar surface by vacuum forces are integrally or collectively held, substantially held, or very substantially held on a wafer or film frame processing plane 192 (e.g., optical inspection plane) and along a wafer table vertical axis Z_WTIn the direction of (or equivalently, in the direction of) aOr away from the wafer table planar surface 190) with minimal or negligible positional deviation or displacement from the wafer or film frame processing plane 192. In representative embodiments, the exposed or upper surfaces of the die 12, having a planar surface area in the range of about 0.25-0.50 square millimeters or more and a thickness of about 25-50 microns or more, can collectively exhibit a vertical deviation relative to the wafer or film frame processing plane of less than about ± 100 μm or less than about 10-90 μm (e.g., less than about ± 20-80 μm or less than about 50 μm on average). Very small or ultra-small die 12 (e.g., about 0.25-0.55 square millimeters) and/or very thin or ultra-thin die 12 (e.g., about 25-75 μm or about 50 μm thick) can be held within the inspection plane 192 such that their deviation from the inspection plane 192 is less than about 20-50 μm.

As described above, the maximum transverse diameter or dimension of the porous material of a given volume 140 within a particular substrate tray compartment 130 and the planar spatial extent or surface area spanned by the ridges 120 defining or limiting the maximum planar spatial extent or surface area of the compartment 130 in which the porous material of the volume 140 is placed are related or correspond to a particular standard or expected wafer and/or film frame size, planar spatial extent or surface area, dimension or diameter. More specifically, to securely hold a given size wafer 10 or film frame 30 to the wafer table planar surface 190, vacuum force is provided or transmitted to the wafer 10 or film frame 30 by selectively providing or transmitting vacuum force to or from vacuum openings 20 exposed to or disposed within the compartments 130 or compartments 130, the compartments 130 having a maximum transverse dimension or diameter that most closely matches the transverse dimension or diameter of the wafer or film frame size currently under consideration, and each compartment 130 corresponding to a wafer or film frame size that is smaller than the wafer 10 or film frame 30 currently under consideration. Thus, a particular size wafer 10 or membrane holder 30 should entirely cover (a) the upper surface of the porous material of the volume 140 having a transverse dimension or diameter that most closely matches the size of the wafer 10 or membrane holder 30 currently under consideration and (b) the upper surface of the porous ceramic material of each volume 140 having a smaller transverse dimension or diameter. The wafer 10 or film frame 30 should also cover a portion of the ridges 120 that most closely matches the size of the wafer 10 or film frame 30 and each ridge 120 having a diameter that is smaller than the wafer 10 or film frame 30 under consideration.

Fig. 3E is a perspective view of a representative first wafer 10a having a first standard diameter (e.g., 8 inches) disposed on the wafer table structure 5, such that the first wafer 10a can be securely held on the wafer table planar surface 190 by: (a) the first wafer 10a covers the porous material of the first volume 140a and covers at least a portion of the transverse width of the first ridges 120a but does not extend to or overlap with the porous material of the second volume 140 b; and (b) applying or transferring a vacuum force to the first wafer 10a by selectively or preferentially providing a vacuum force to or through the vacuum opening 20 of the first compartment, to and through the porous material of the first volume 140a, to the underside of the first wafer 10 a.

Fig. 3F is a perspective view of a representative second wafer 10b having a second standard diameter (e.g., 12 inches) disposed on the wafer table structure 5, in accordance with an embodiment of the present disclosure. The second wafer 10b can be held securely on the wafer table planar surface 190 by: (a) the second wafer 10b covers the porous material of the first and second volumes 140a-b and covers at least a portion of the transverse width of the second ridges 120b but does not extend to or overlap with the porous material of the third volume 140 c; and (b) applying or transferring a vacuum force to the second wafer 10b by selectively or preferentially providing a vacuum force to or through the vacuum openings 20 of the first compartment and the vacuum openings 20 of the second compartment, to and through the porous material of the first and second volumes 140a-b, to the underside of the second wafer 10 b.

Fig. 3G is a perspective view of a representative third wafer 10c having a third standard diameter (e.g., 16 inches) disposed on the wafer table structure 5, in accordance with an embodiment of the present disclosure. The third wafer 10c can be held securely on the wafer table planar surface 190 by: (a) the third circle 10c covers the porous material of the first, second and third volumes 140a-c and covers a portion of the transverse width of the outer edge 106 of the substrate tray; and (b) applying or transferring a vacuum force to the third wafer 10c by selectively or preferentially providing a vacuum force to or through the vacuum openings 20 of the first compartment, the vacuum openings 20 of the second compartment, and the vacuum openings 20 of the third compartment, to and through the porous material of the first, second, and third volumes 140a-c, to the underside of the third wafer 10 c.

In addition to the above, in various embodiments, the ceramic-based base tray 100 can include or be formed to receive or provide one or more additional types of structural features or elements. Certain representative, non-limiting embodiments of such ceramic-based trays 102 will be described in detail below.

Fig. 4A is a perspective view of a ceramic based wafer table substrate tray 100, the substrate tray 100 including a set of pop-pin guide features 160, according to another embodiment of the present disclosure. FIG. 4B is a cross-sectional view of the ceramic based wafer table substrate tray of FIG. 4A taken along line C-C'. In such embodiments, the substrate tray 100 can have a general or unitary structure similar to or substantially the same as described above. However, the first ridge 110a includes a plurality of pop-pin guide structures, elements or features 160a-c (e.g., three in various embodiments, sufficient to enable three pop-pins to handle each of 8 inch, 12 inch and 16 inch wafers corresponding to such wafer sizes). Each pop-pin guide member 106a-c is shaped and configured to provide an opening 162 that corresponds to or defines a passageway or path through which the pop-pin can travel. In various embodiments, any given pop-pin guide member 160a-c can be formed as an integral part or extension of the first spine 110a such that the pop-pin guide member 160a-c protrudes into a portion of the first compartment 120 a. In addition, the pop-pin guide components 1760a-c are sized and/or configured such that substantially no, negligible or minimal vacuum loss occurs during use of the wafer table structure (e.g., during pop-pin raising and lowering). In several embodiments, the pop-pin guide members 160a-c can be strategically positioned such that a single set of pop-pins 164 can handle each wafer size that the wafer table structure 5 is designated to handle. Those skilled in the art will appreciate that the pop-pin guide members 160a-c can alternatively or additionally be formed separate from the first ridge 110a, or as part of another ridge 110 (e.g., the second ridge 110 b).

Fig. 5A is a perspective view of the substrate tray 100 of fig. 4A and 4B into which a moldable, conformable, or flowable porous material has been introduced, provided, or disposed. Fig. 5B is a perspective cross-sectional view of a substrate tray 100 carrying moldable porous material corresponding to fig. 5A taken along line D-D'. It should be noted that when moldable porous material is introduced into base tray 100, opening 162 within each pop-pin guide member 160a-c and through pop-pin guide member 160a-c should be sealed or blocked so that porous material does not enter opening 162 and the path through which its corresponding pop-pin guide member 160a-c passes in order to ensure that hardened moldable porous material does not interfere with the travel of pop-pins 163a-c through this path and opening 162 during pop-pin actuation involving the lowering or raising of a wafer or film frame relative to wafer table planar surface 190.

In some embodiments, the substrate tray 100 can carry, include, or incorporate a plurality of heating and/or cooling elements. For example, the heating element can comprise a resistive heating element. The cooling element can include a pipe, tube, or passage configured to carry a cooling substance or fluid (e.g., a cooling gas or liquid); or a thermoelectric cooling device. The heating and/or cooling elements can be enclosed or encapsulated within a ceramic-based non-porous substrate tray material (e.g., integrally formed within one or more portions of the substrate tray 100). Alternatively, the heating and/or cooling element can be located outside of the ceramic-based non-porous substrate tray material, enclosed or encapsulated within a portion of the porous material occupying the substrate tray base 130. In addition to or as an alternative to the foregoing, the ceramic-based non-porous substrate tray 100 and/or the porous material occupying the substrate tray base 130 can carry, include, or incorporate additional other types of elements, such as electrodes, temperature sensing elements (e.g., thermocouples), other types of sensing elements (e.g., accelerometers, vibration sensors, or optical sensors), and/or other types of sensing elements configured to sense ambient/environmental conditions within or outside a portion of the wafer table structure 5.

Fig. 6 is a representative process 170 for fabricating the wafer table structure 5 in accordance with an embodiment of the present disclosure. In an embodiment, the wafer table fabrication process 170 includes a first process portion 172 that involves providing a ceramic-based non-porous wafer table substrate tray 100 having a plurality of compartments 130 therein; a second processing portion 174 that involves providing a moldable porous material; and a third processing section 176 comprising introducing a moldable porous material into the plurality of compartments 130 and filling the volumetric geometry of each compartment 130 within the plurality of compartments 130 with the moldable porous material such that the moldable porous material integrates into or occupies the internal spatial dimensions of each compartment 130. Within each compartment 130, a depth D beyond the substrate tray compartment 130 is exhibited in a manner shown in FIG. 7 or generally shown by means of a moldable porous ceramic material_TCThe initial volume 142 of moldable porous ceramic material can exceed or slightly exceed the volumetric capacity of the compartment 130.

The fourth process portion 178 involves hardening or curing the moldable porous ceramic material and bonding the porous material to the interior surfaces defining each compartment 130 (i.e., the interior bottom surface 110 within the base tray and the compartment side walls corresponding to the ridges 120). Once the porous material is securely held within or bonded to the compartment interior surfaces, the fifth processing portion 180 involves machining or grinding the porous material (i.e., each porous material volume 140) and portions of the substrate tray 110 such as the exposed upper surface 108 of the substrate tray outer edge 106 and the exposed upper surface 122 of the substrate tray ridge 120 so as to simultaneously provide the exposed, upper or outer surface of the porous material volume 140, the exposed upper surface 122 of the substrate tray ridge 120, and the exposed upper surface 108 of the substrate tray outer edge 106 with a very high planarity, thereby defining a wafer table planar surface 190 upon which a high uniformity of the wafer and film frame can be securely held. Once planarized, each porous material volume 140 corresponding to any given compartment 130 is the same or substantially the same volume as the compartment 130.

The sixth processing portion 182 involves coupling or mounting the planarized wafer table structure 5 to a displaceable wafer table assembly (e.g., an x-y wafer table) and coupling the vacuum opening of the planarized wafer table structure 5 to a set of table assembly vacuum lines, links and/or valves so that a vacuum force can be selectively actuated and applied to the wafer 10 or film frame 30 disposed on the wafer table planar surface 190.

In contrast to certain prior art wafer table designs in which regions of porous material are separated by spacers made or substantially made of one or more metals and/or utilize an outer pedestal structure made or substantially supported by one or more metals, various embodiments of a wafer table structure according to the present disclosure avoid or eliminate ridges 120 made or substantially made of one or more metals, and generally further avoid or eliminate base trays 100 made or substantially made of one or more metals. More specifically, in prior art wafer table designs that include an upper or exposed non-porous wafer table surface that is at least partially or substantially made of metal and an upper or exposed porous wafer table surface that is at least substantially made of ceramic material, such metal surface has very different machining, grinding or polishing characteristics, properties or behavior than the porous ceramic material surface. During the machining, grinding or polishing process, the metal surface will not planarize at the same rate or ease as the surface of the porous ceramic material. In addition, metal surfaces can easily damage standard machining, grinding or abrading elements, devices or tools (e.g., sanding heads). The inclusion of a metal surface makes machining, grinding or polishing a wafer table structure with a processing arm made according to embodiments of the present disclosure more difficult, more expensive and more time consuming.

Furthermore, the difference between the machining, grinding or abrading characteristics of the exposed metal surface and the exposed porous ceramic surface significantly increases the likelihood that the finally-manufactured wafer table surface will exhibit an undesirable or unacceptable non-planarity or insufficient planarity at one or more portions or areas of the wafer table surface. Such prior art wafer table designs are therefore not well suited for inspection of large diameter and thin wafers 10 having fragile dies 12 thereon (e.g., 12 inch or larger diced wafers 10 carried by a film frame 30 carrying small or ultra-small dies 12). In contrast, wafer table structure embodiments according to the present disclosure do not suffer from this drawback and provide a highly uniform or ultra-uniform planar wafer table surface 622 that is well suited for inspection of such types of wafers 10 or film frames 30.

The end result of a wafer table structure fabricated in accordance with embodiments of the present disclosure is a wafer table 620 that (a) eliminates or omits grooves or vacuum holes (e.g., drilled vacuum holes) on the wafer table surface 622 that can adversely affect the planarity of the wafer table surface 622 and cause one or more of the aforementioned related problems; (b) a wafer table surface 622 having a very high or ultra-high planarity that is suitable for handling (i) the wafer 10 and film frame 30, thereby eliminating the need for a wafer table conversion kit; and (ii) very small or ultra-small die 12 (e.g., 0.5 x 0.5 square millimeters or less) on a very thin or flexible wafer (e.g., 75 μm, 50 μm or less) because the planar wafer table surface 622 facilitates positioning and retaining such die 12 on a single plane, which is difficult to achieve using conventional wafer table designs; and (c) are structurally simple, low cost, and easy to manufacture (particularly as compared to conventional wafer table designs that include grooves or machined/drilled vacuum holes on their wafer table surface and exposed metallic material (e.g., a plurality of metallic partitions or plates on the wafer table surface).

Aspects in accordance with various embodiments of the present disclosure address at least one aspect, problem, limitation and/or disadvantage associated with existing systems and methods for handling wafers and/or film frames including one or more problems, limitations and/or disadvantages associated with existing wafer table structures. While features, aspects, and/or advantages associated with certain embodiments have been described in the present disclosure, other embodiments may also exhibit such features, aspects, and/or advantages, and not all embodiments need necessarily exhibit such features, aspects, and/or advantages to fall within the scope of the present disclosure. Those skilled in the art will appreciate that some of the above disclosed systems, components, processes, or alternatives thereof can be combined with other different systems, components, processes, and/or applications as desired. In addition, various modifications, alterations, and/or improvements to the various embodiments disclosed may occur to those skilled in the art within the scope of the disclosure.

Claims (20)

1. A wafer table structure, the wafer table structure providing a wafer table surface, the wafer table structure comprising:

a substrate tray comprising a plurality of first exposed upper surfaces, an interior surface, and a plurality of compartments formed integrally with or attached to the interior surface, the substrate tray being formed of at least one type of material that is permeable to a gas or fluid in response to an applied negative pressure;

a plurality of ridges separating individual ones of the plurality of compartments from one another, wherein the first exposed upper surfaces of the base tray comprise exposed upper surfaces of the plurality of ridges, wherein each compartment forms a depression between the exposed upper surfaces of at least one ridge within the plurality of ridges, and wherein each ridge within the plurality of ridges is sized to correspond to a standard wafer size and/or a standard film frame size;

a single set of multiple pop-pin guides through which a single set of multiple pop-pins can travel to hold multiple standard size wafers, wherein each of the single set of multiple pop-pin guides is formed in a portion of an innermost ridge within the multiple ridges;

at least one type of compartment material disposed within the plurality of compartments, the at least one type of compartment material being flowably or moldably conformable to a shape of each of the plurality of compartments and hardenable to provide a hardened compartment material in the plurality of compartments that is permeable to gas or fluid in response to applied vacuum force, and the hardened compartment material providing a plurality of second exposed upper surfaces; and

a plurality of openings formed in the inner surface of the base tray through which the hardened compartment material may be exposed to negative or positive pressure, wherein the plurality of openings includes at least one opening corresponding to each compartment within a plurality of compartments,

wherein (a) the plurality of first exposed upper surfaces of the substrate tray and (b) the plurality of second exposed upper surfaces of the hardened compartment material are simultaneously machinable by means of a common machining process to provide a planar wafer table surface, and

wherein the wafer table surface is adapted for handling wafers, portions of wafers, and/or film frames on which wafers or portions thereof are mounted.

2. The wafer table structure of claim 1, wherein the planar wafer table surface has no grooves and vacuum holes formed therein.

3. The wafer table structure of claim 2, wherein the planar wafer table surface facilitates positioning and retention of wafer dies in or on a single plane, and wherein the planar wafer table surface has a planarity uniformity across the planar wafer table surface of less than ± 100 μ ι η.

4. The wafer table structure of claim 1, wherein the rate of planarization of the plurality of first exposed upper surfaces of the substrate tray by the common process and the rate of planarization of the plurality of second exposed upper surfaces of the hardened compartment material by the common process are the same.

5. The wafer table structure of claim 1, wherein:

the base tray interior surface includes a plurality of interior bottom surfaces, each ridge within the plurality of ridges bordering the interior bottom surface of the base tray, and each ridge within the plurality of ridges dividing portions of different base tray interior bottom surfaces from one another to define the plurality of compartments.

6. The wafer table structure of claim 5, wherein the base tray and each ridge within the plurality of ridges are formed of the same material.

7. The wafer table structure of claim 5, wherein each ridge within the plurality of ridges is located a predetermined distance from a center of the base tray, and wherein at least a first compartment within the plurality of compartments is surrounded by a ridge.

8. The wafer table structure of claim 1, particular openings of the plurality of openings being selectively exposed to a negative or positive pressure such that the hardenable compartment material is selectively exposed to the negative or positive pressure applied through the plurality of openings, and wherein the hardened compartment material in any given compartment is fluidically isolated from the hardened compartment material in any other compartment when exposed to the negative or positive pressure.

9. The wafer table structure of claim 7, wherein:

(a) the plurality of compartments include:

a first compartment comprising a first volume of hardened compartment material exposed to a corresponding plurality of first openings within a plurality of openings; and

a second compartment comprising a second volume of compartment material exposed to a corresponding plurality of second openings within a plurality of openings, the plurality of second openings being different from the plurality of first openings; and is

(b) A first ridge within the plurality of ridges surrounds the first compartment, thereby separating the first compartment from the second compartment.

10. The wafer table structure of claim 9, wherein a negative pressure can be applied to the first plurality of openings to securely hold a first wafer table or a first film frame having a first standard diameter to the planar wafer table surface, and wherein a negative pressure can be applied to the first plurality of openings and the second plurality of openings to securely hold a second wafer or a second film frame having a second standard diameter greater than the first standard diameter to the planar wafer table surface.

11. The wafer table structure of claim 10, wherein:

(c) the plurality of compartments includes a third compartment containing a third volume of hardened compartment material exposed to a plurality of third openings corresponding thereto, the plurality of third openings being different from each of the plurality of first openings and the plurality of second openings; and is

(d) A second ridge within the plurality of ridges surrounds the second compartment, thereby separating the second compartment from the third compartment.

12. The wafer table structure of claim 11, wherein a negative pressure can be applied to the first, second, and third plurality of openings to securely hold a third wafer or a third film frame having a third standard diameter that is greater than each of the first and second standard diameters to the planar wafer table surface.

13. The wafer table structure of claim 1, wherein at least one of the base tray and the hardened cell material comprises a ceramic-based material.

14. The wafer table structure of claim 13, wherein the substrate tray comprises porcelain.

15. The wafer table structure of claim 1, further comprising a single set of pop-pin guide members through which a single set of pop-pins can travel to handle a plurality of standard size wafers, wherein each of the single set of multiple pop-pin guide members protrudes into a portion of an innermost compartment within the plurality of compartments.

16. A method of manufacturing a wafer table structure, the wafer table structure providing a wafer table surface, the method comprising:

providing a substrate tray having a plurality of first exposed upper surfaces, an interior surface, a plurality of compartments formed integrally with or attached to the interior surface, and a plurality of openings formed in the interior surface, the substrate tray being formed of at least one type of material that is permeable to a gas or fluid in response to an applied negative pressure;

providing a plurality of ridges separating individual ones of the plurality of compartments from one another, wherein the first exposed upper surfaces of the base tray comprise exposed upper surfaces of the plurality of ridges, wherein each compartment forms a depression between the exposed upper surfaces of at least one ridge within the plurality of ridges, and wherein each ridge within the plurality of ridges is sized to correspond to a standard wafer size and/or a standard film frame size;

providing a single set of a plurality of pop-pin guides through which a single set of a plurality of pop-pin guides can travel to hold a plurality of standard size wafers, wherein each of the single set of the plurality of pop-pin guides is formed in a portion of an innermost ridge within the plurality of ridges;

disposing at least one type of compartment material within compartments of a plurality of substrate trays, the at least one type of compartment material being flowably or moldably conformable to a shape of each compartment within the plurality of compartments;

hardening the at least one type of compartment material to provide a hardened compartment material in the plurality of compartments that is permeable to gas or fluid in response to the applied negative or positive pressure, and the hardened compartment material provides a plurality of second exposed upper surfaces; and is

Simultaneously machining the plurality of first exposed upper surfaces and the plurality of second exposed upper surfaces by means of a common machining process to provide a planar wafer table surface for carrying wafers and film frames on which the wafers or parts thereof are mounted,

wherein the wafer table surface is adapted for handling wafers, portions of wafers, and/or film frames on which wafers or portions thereof are mounted.

17. The method of claim 16, wherein during simultaneous processing of the plurality of first exposed upper surfaces and the second exposed upper surfaces, a rate of planarizing the plurality of first exposed upper surfaces of the substrate tray with the common processing treatment is the same as a rate of planarizing the plurality of second exposed upper surfaces of the hardened compartment material with the common processing treatment.

18. The method of claim 16, wherein each of the single set of the plurality of pop-pin guide members protrudes into a portion of an innermost compartment within the plurality of compartments.

19. The method of claim 16, wherein at least one of the base tray and the hardened compartment material comprises a ceramic-based material, and wherein the hardened compartment material is exposable to a negative pressure and a positive pressure selectively applied by a plurality of openings.

20. The method of claim 16, the method further comprising:

mounting the wafer table structure to a displaceable wafer table assembly; and

each of the plurality of openings is coupled to a set of table assembly vacuum lines, links, and/or valves by which a negative or positive pressure can be selectively actuated and applied to a wafer or film frame disposed on the planar wafer table surface.