JP2002334924A - Sealed wafer carrier, reading device and method for reading mark on wafer in carrier - Google Patents

Abstract

(57) Abstract: A wafer carrier capable of accurately reading dot marks from the outside using a small optical device while a semiconductor wafer is housed in a sealed wafer carrier, and the dot marks. A reading device and a reading method. A sealed wafer carrier has a transparent window (15) at a part facing a peripheral surface of a semiconductor wafer (W) to be accommodated.
And a plurality of reflectors near the inner surface of the window (15).
(16) are arranged with a wafer accommodation interval. Furthermore, at the installation site of the transparent window (15), the semiconductor wafer (W)
Spacers (1) for keeping a constant distance between the peripheral edge of each wafer (W) and the inner surface of the transparent window (15) corresponding to the storage position of (1).
8), and a relay lens (19) is arranged between the reflecting mirror (16) and the peripheral mark forming surface of the semiconductor wafer (W) housed in the carrier. The imaging device (17) has its light receiving axis arranged substantially orthogonal to the transparent window (15),
(17) is controlled and moved at intervals of each wafer in parallel with the central axis of the wafers (W) arranged in multiple stages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed wafer suitable for optically sequentially reading various marks formed in respective mark forming areas of a plurality of semiconductor wafers while being housed in a sealed wafer carrier. The present invention relates to a carrier, a reading device and a reading method of the mark.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, it is necessary to set various and strict manufacturing conditions for each process.
In order to manage these, a mark composed of a two-dimensional code or a bar code using numerals, characters, and dots is displayed on a partial surface of the semiconductor wafer. Thus, the number of semiconductor manufacturing steps is over 100, and many element forming processes and planarizing processes are performed in each process. These processes include, for example, resist coating, reduction projection of a pattern on the resist, resist development, or planarization by various kinds of film formation such as an insulating film or a metal film for filling a gap generated by copper wiring or the like. is there.

[0005] The dot marking is usually performed by irradiating a continuous pulse laser beam to a partial surface of a semiconductor wafer via an optical system. In addition, this marking is not limited to one time, and in order to know the history characteristics of each manufacturing process, the minimum necessary history data is often marked in each manufacturing process. However, since marking on a semiconductor wafer is limited to an extremely narrow area, the size and number of dots to be marked are also limited, and the size of the marking area, the size of the dots, the number of dots, etc. are determined by the SEMI standard. Stipulated.

[0004] A semiconductor wafer on which dot marking has been performed, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-299216, changes in reflectivity due to irradiation of a laser beam of a He-Ne laser, or heat waves of a normal laser beam. Is read as a change in the vibration, and various manufacturing conditions in subsequent manufacturing steps are set based on the read information. Therefore, if the above-mentioned reading is not performed correctly and the information is read as erroneous information, all become defective unless accidental. Most of the causes of the reading failure are based on the unclearness of the mark due to the dot marking.

[0005] One cause of this blur is that the depth of the dots forming the mark is small. When the depth of the dot is small, the dot is buried by the above-described film formation and reading becomes impossible. Therefore, it is necessary to increase the depth of the dot to some extent. Alternatively, it is desirable that the dot mark itself be in a form having high optical visibility.

Further, in order to write a large amount of data by dot marks in such a small area as described above, it is desirable to make the size of the dot marks as small as possible within an optically readable range. It is necessary to have a form in which the visibility is not lost even after a film process or various grinding processes.

[0007] In view of these problems, the present inventors,
For example, JP-A-11-156563, JP-A-2001
A dot mark form, a dot marking technique, or a dot mark reading technique as described in JP-A-60606 has already been proposed and implemented, or a number of related techniques have been proposed. According to these proposals, the shape of a dot mark is changed to a wisteria jar-like shape composed of a deep concave hole as compared with a hole diameter having a length of 1 to 15 μm and a depth of 0.5 to 10 μm along the mark forming surface. 1.0 to 15 μm in parallel with the height of the protrusion is 0.01 to 5 μm
The formation of m minute dot marks has been successful.

In particular, regarding the size of these dot marks, the opening diameter of the holes is less than 15 times smaller than the size of 100 to 200 μmφ like a conventional concave dot mark, and the semiconductor wafer Greatly increases the amount of information that can be written in the same area. In addition, in the case of a dot mark having a peculiar form protruding from the mark forming surface, not only the visibility is increased, but also the reading of the mark is performed not by the specular reflection light but by the scattered light of the irradiation surface. Since not only coherent light but also incoherent light can be used as light, the reading device for the mark can be structurally simplified.

As a result of the formation of such dot marks, it is possible to efficiently read the subsequent marks without affecting the semiconductor wafer from external influences such as movement or conveyance during the reading of the marks, and furthermore, the surface marks can be formed on the surface. The most preferable area as the marking area where the change in the state is small is an upper and lower chamfered portion of the peripheral portion of the semiconductor wafer.

A scribe line, which is a cutting line for cutting the wafer into chips, is also an ideal part for the dot marking area as described above. However, for reading the dot mark, the semiconductor wafer is taken out of the cassette and read. Must be set on the table. Usually, these operations are performed by a robot, so that the occurrence of contamination and the like is small, but if possible, the number of times of taking in and out of the cassette should be as small as possible. In consideration of this point, the influence of various processing on the wafer surface is the least, the state close to the exposed silicon is always maintained, and the peripheral edge of the semiconductor wafer that can be read in the state of being stored in the wafer cassette during the subsequent reading is also possible. The surface of the part is preferred.

An ordinary wafer cassette or carrier is composed of a plastic case body in which a plurality of wafers are stored in parallel and in a multi-stage manner at a predetermined interval at which a hand portion of a robot can be inserted and removed. Has an opening for inserting and removing the wafer, and a part of the peripheral surface of the semiconductor wafer accommodated in the cassette is exposed to the outside through the opening. Therefore, if a dot mark can be formed on the exposed portion, the mark can be read while the semiconductor wafer is stored in the cassette.

The periphery of the semiconductor wafer is chamfered along the ridge line on the front and back sides, and dot marks can be marked on the chamfered portion and the flat surface of the peripheral surface sandwiched between the front and back surfaces of the chamfered portion. , These parts are preferable as marking areas from all sides. In particular, if the inner surface of the notch is cut out in a substantially V-shape on the peripheral surface of the wafer for indicating the crystal orientation, the marking area may be more suitable than the chamfered portion or the peripheral surface.

As described above, at present, when dot marks having excellent visibility and minute dimensions are realized, the number of dot marks that can be imprinted on the marking area is so large as to be incomparable with the conventional number of engraved marks. The code can be used freely, and the number of information bytes can be significantly increased regardless of the 1D or 2D code. Further, the same information can be written not only once but twice and three times.

On the other hand, recent advances in microfabrication in the manufacturing process of semiconductor devices have also affected the degree of cleanliness during processing, and, as in the conventional case, wafers are individually moved and moved one by one. If processing and management are to be performed, it will be difficult to cope with the huge capital investment required, and inevitably manage the cleanliness of each processing step independently and secure the cleanliness when moving. However, a plurality of wafers must be moved and processed simultaneously as a unit. As a result, it is required that each processing and management be performed for a plurality of wafers as one unit.

For this purpose, it is desirable that the dot marks provided on each wafer can be optically read while being accommodated in a wafer carrier. In the manufacture of semiconductor devices, fine processing by lithography in the wafer process, which is the most important processing technology, for example, the processing in the exposure process is currently 0.25 μm, so the cleanliness of the clean room is a numerical value corresponding to it. It is, for example, smaller 0.13 μm
Now that the following processes are being put to practical use, it is necessary to further increase the cleanliness of the clean room.

In order to meet this demand, the current clean room must be significantly remodeled or rebuilt, which requires a huge capital investment. In order to avoid such enormous capital investment, each processing step is composed of a closed processing room that satisfies the required cleanliness without changing the structure of the clean room. There are also studies that rely entirely on robots.

In this case, if the movement of the wafer by the robot is performed in units of wafers with the wafers exposed, the influence of the cleanliness in the room causes the simultaneous movement of a plurality of wafers by the sealed wafer carrier. Let it. The wafer carrier at this time is configured so that, for example, the main body and the front surface can be opened and closed via a sealing material. With a wafer carrier having such a configuration, it is possible to process not only a wafer but also a plurality of wafers per carrier in each closed processing chamber. It is preferable that reading be performed in a state where a wafer is stored in the wafer carrier in the processing chamber.

[0018]

As described above, when writing or reading dot marks for each wafer in a state in which a semiconductor wafer is stored in a wafer carrier, the open / close lid on the front surface of the wafer carrier must be closed. The dot mark is written or read in a state where the dot mark forming area of the semiconductor wafer accommodated in the multistage, for example, the V notch portion is exposed outside the carrier.

However, exposing the semiconductor wafer to the outside of the carrier does not cause any particular problem if the cleanliness in the sealed processing chamber is ensured. Is reduced, processing in the processing chamber becomes impossible. Therefore, it is desirable to avoid removing the opening / closing lid of the wafer carrier whenever possible, as much as possible.
As long as the process can be performed with the wafer carrier sealed, it is desirable to perform the process with the wafer carrier sealed.

Regardless of the writing of the dot mark, the reading is performed by making the portion of the wafer carrier facing the dot mark forming region of the semiconductor wafer housed in the wafer carrier a transparent window.
The dot mark can be read through the window. However, even if the window is made of a transparent material, optically reading dot marks inside the carrier through the window not only makes it extremely difficult to read due to refraction of light passing through the window, but also makes it difficult to read the wafer carrier. The distance between the dot mark formation area and the image pickup device becomes longer because it is read from the outside of the device, making it impossible to use an optical device with a small depth of focus, resulting in an increase in size. Even if it is a large dot mark, if it is a minute dot mark as described above, it will be difficult to read because it is more difficult to read.

According to the present invention, there is provided a wafer carrier capable of accurately reading a dot mark from the outside using a small optical device while a semiconductor wafer is housed in a sealed wafer carrier, and reading the dot mark. It is intended to provide an apparatus and a reading method.

[0022]

Means for Solving the Problems and Effects of the Invention The present inventors have repeatedly studied and experimented from various angles on specific methods for overcoming the above problems. First, in order to reliably and accurately read a dot mark formed on a peripheral portion of a semiconductor wafer contained in a carrier through the transparent window in a sealed wafer carrier, a dot formed on a wafer surface is required. It was considered that transmitting the optical path of the light image of the mark substantially perpendicularly to the transparent window portion was most desirable because the image could be captured without being affected by refraction or the like.

As a result of further study, as long as the positioning of all the semiconductor wafers contained in the wafer carrier in the carrier is not performed correctly, the dot mark forming area is detected each time reading is performed, and the dot mark forming area is detected and formed. Complicated operations such as the need to focus on the set dot mark are inevitable. Therefore, they thought that such an operation would need to be simplified. Further, it has been found that even a dot mark having a minute form as described above cannot be put to practical use unless accurate optical visibility is secured.

Based on the results of these studies, it was considered that the modification of the wafer carrier was the most effective in implementing the system, as well as the improvement of the optical system. Then, further investigation of the specific method was started, and as a result of repeating many tests, the invention according to claim 1 of the present application was finally reached.

According to a first aspect of the present invention, there is provided a sealed wafer carrier for accommodating a plurality of semiconductor wafers in multiple stages, wherein a transparent window portion is provided in a part facing the peripheral surface of the accommodated semiconductor wafer. A plurality of reflecting mirrors are arranged in the vicinity of the inner surface of the window at a wafer accommodation interval.

The plurality of semiconductor wafers accommodated in the wafer carrier are accommodated in the carrier in a multistage manner, with a gap between the insertion and removal of the robot hand and the surfaces of the wafers being parallel to each other. Further, ID marks such as an identification mark and a processing history mark of the semiconductor wafer are formed on the peripheral edge chamfered portion of the semiconductor wafer using the dot mark as a two-dimensional code. Therefore, the mark forming surface has a predetermined inclination angle with respect to the wafer surface. Usually, the wafer carrier is placed and fixed on a table with the surface of the semiconductor wafer housed therein being horizontal or vertical.

Therefore, when the semiconductor wafer is accommodated in the wafer carrier in multiple stages, the mark forming region of the semiconductor wafer and the window of the wafer carrier face each other at a predetermined angle. Therefore, when the mark formed in the mark formation area is to be imaged by the image pickup device from outside the wafer carrier, the optical axis of the image pickup device must be accurately directed to the mark formation region in consideration of the refractive index. ,
Further, an operation for adjusting the focus of the image pickup device to the surface of the mark forming area is required. These operations must be performed sequentially and accurately for each of the semiconductor wafers arranged in multiple stages, which is an extremely complicated operation and practically difficult to put to practical use.

Therefore, in the present invention, as shown in FIG. 4, the optical axis of the image pickup device 17 is arranged so as to be substantially orthogonal to the transparent window 15 of the wafer carrier 10 so that the refractive index of the window 15 can be reduced. Without having to consider it. for that reason,
The mark in the mark forming area inclined with respect to the window 15 is to be imaged by the image pickup device 17 via the reflecting mirror 16. In order to form an image on the optical axis of the imaging device 17 in the imaging, the inclination angle of the reflection mirror 16 with respect to the horizontal line is set so that the reflection optical path of light from the surface of the mark forming area is substantially orthogonal to the window. .

According to a second aspect of the present invention, the distance between the peripheral edge of each wafer and the inner surface of the transparent window is made constant in accordance with the storage position of the semiconductor wafer. It is characterized by providing a holding spacer.

In the hermetically sealed wafer carrier 10 having the window portion 15 as described above, in order to take an image of a mark from outside the carrier, the window portion 15 of the semiconductor wafer W accommodated in multiple stages in the carrier is required. In addition, there must be no other interference between the window and the mark forming region on the peripheral portion facing the window portion 15, and a gap is inevitably formed. However, this gap allows free movement of the semiconductor wafers W arranged in multiple stages. On the other hand, in reading the mark by the imaging device 17, the positioning and fixing of the semiconductor wafer W is an essential requirement.

According to the present invention, as shown in FIG. 4, the position of the window 15 corresponding to the individual semiconductor wafer W accommodated in the wafer carrier is not interfered with for the positioning and fixing of the semiconductor wafer W, as shown in FIG. A spacer 18 having a fixed size is attached. When the semiconductor wafer W is accommodated in the wafer carrier 10 and sealed, the spacer 18 is positioned between the inner surface of the window 15 and the mark forming area of the semiconductor wafer W. The semiconductor wafer W accommodated in the device is immobilized. As a result, the gaps between the mark forming areas of all the semiconductor wafers W stored in multiple stages and the windows 15 are uniform, and the imaging device 17 is moved linearly along the arrangement direction of the semiconductor wafers W during imaging. Then, only by fine adjustment, the marks can be sequentially imaged accurately.

The invention according to claim 3 is characterized in that a relay lens is further arranged between the reflecting mirror and the periphery of the semiconductor wafer housed in the carrier. Although the marks formed on conventional semiconductor wafers are large,
For example, a dot mark is extremely small, such as 100 to 200 μm. In particular, in the case of an extremely small dot mark of 1 to 15 μm as described above, various improvements are required for reading. The present inventors have developed a technique for forming dot marks in a minute form, and for example, disclosed in Japanese Patent Application No.
Various proposals have been made for an effective reading method for minute dot marks, as proposed in US Pat.

Therefore, in the present invention, as described above, the peripheral portion of the semiconductor wafer W, which is the mark forming area, and the reflecting mirror 1
6 and a relay lens 19 is interposed. The relay lens 19 is preferably a magnifying lens, and the mark is magnified through the lens 19 and reflected by the reflecting mirror 16, and the magnified image is captured by the imaging device 17 to realize accurate reading.

According to a fourth aspect of the present invention, there is provided a sealed wafer carrier according to any one of the first to third aspects, wherein a mark formed in a mark forming area of a semiconductor wafer housed in the carrier is placed outside the carrier. The present invention relates to a mark reading device suitable for capturing an image from a mark. The configuration includes a table for positioning and fixing the wafer carrier, an imaging device moving guide rod disposed around the table, an imaging device supporting member guided and controlled by the guiding rod, and a light receiving port. Are directed to the transparent window of the wafer carrier and are supported by the imaging device support member.

According to a fifth aspect of the present invention, there are provided various types of semiconductor wafers formed in a peripheral portion of a semiconductor wafer accommodated therein by using the sealed wafer carrier according to any one of the first to third aspects. What is claimed is: 1. A mark reading method for reading a mark from outside a carrier, comprising: positioning and fixing a transparent window portion of a wafer carrier containing a semiconductor wafer on a table toward an imaging side; Adjusting the optical axis of the reflected light image by the reflecting mirror so as to coincide with the optical axis of the lighting port of the imaging device; and capturing the reflected light image of the mark formed in the mark forming area by the reflecting mirror. A mark reading method, which includes taking an image with a device.

If a mark reading device having a simple structure as described above is used to read marks on a plurality of semiconductor wafers contained in a sealed wafer carrier in accordance with the above-described mark reading method, for example, the cleanliness can be further improved. It is no longer necessary to read marks inside a processing chamber having a high temperature, and the marks can be read efficiently and accurately sequentially in a semiconductor wafer always in a clean environment without having to take in and out of the carrier.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows an example of a typical structure of the sealed wafer carrier of the present invention. The wafer carrier 10 is a container for accommodating a 300 mmφ semiconductor wafer, and its reference structure is defined by the SEMI standard.

The top plate and the bottom plate have a shape in which a substantially arc-shaped plate is connected to one side of a square plate, and two sides of the top plate and the bottom plate and the periphery of the arc-shaped plate are connected by side walls. The case main body 11 includes a door body 12 and the door main body 12 hermetically fitted to the semiconductor wafer insertion opening of the case main body 11. Retainers 13 that support the peripheral edges of a plurality of semiconductor wafers W are formed on both inner wall surfaces of the arc-shaped side wall and the flat side wall of the case body 11 so as to face each other. Other configurations conform to the SEMI standard,
For example, a crossbar 10a for positioning and mounting on a table or the like is provided at the center of the lower surface of the bottom plate. The retainer portion 13 is formed with a plurality of V-shaped cross-section wafer support grooves extending in a circumferential direction from a part of the arc-shaped inner wall surface and continuing to a part of the flat plate-shaped inner wall surface. A part of the periphery of the plurality of semiconductor wafers W is fitted into the opposed wafer support grooves, and the semiconductor wafers are accommodated in the wafer carrier 10 in multiple stages.

The wafer carrier 10 of the present invention also has the above-described basic structure, but as shown in FIG. 4, a flat transparent window portion is formed on the side wall of the case body 11 opposite to the opening. 15 are formed. In the present embodiment, the mark formed on the semiconductor wafer W has a maximum length parallel to the mark formation surface of 1 to 15 μm and a depth of 0.5 to 10 μm.
m has a wisteria shape consisting of a deep concave hole compared to the hole diameter, or the length parallel to the mark forming surface is 1 to 15 μm.
m, a small dot mark having a protruding form in which the height of the protruding portion is 0.01 to 5 μm is imaged from outside the carrier by the imaging device 17 through the transparent window 15.

The dot mark in this mode is developed by the present inventors and others, for example, as described in
If a part of the semiconductor manufacturing apparatus disclosed in Japanese Patent Application Laid-Open No. 1-60612 is improved, it can be easily formed. FIG. 3 shows a schematic configuration of a dot mark forming unit using a laser beam in the semiconductor manufacturing apparatus. Since the method of forming minute dot marks by the dot mark forming section is disclosed in detail in the above-mentioned publication, only a brief description of the method is given here.

In the figure, reference numeral 2 denotes a laser oscillator, 3
Denotes a beam homogenizer, 4 denotes a liquid crystal mask, 5 denotes a beam profile converter, 6 denotes a reduction lens unit, and W denotes a semiconductor wafer. Here, the semiconductor wafer W is not only a silicon wafer but also a wafer in which an oxide film or a nitride film is formed on the surface of the wafer, or a semiconductor wafer grown by epitaxial growth, gallium arsenide, an indium phosphide compound or the like. Semiconductor wafers in general.

Laser marking device 1 in this embodiment
In the dot marking on the surface of the semiconductor wafer, a laser beam having a Gaussian-shaped energy density distribution emitted from a laser oscillator 2 is first passed through a beam homogenizer 3 to form a top-hat type energy density distribution having a substantially uniform peak value. Mold into The laser beam having a uniform energy density distribution is then applied to the surface of the liquid crystal mask 4. At this time, the liquid crystal mask 4 can drive and display a required marking pattern on the mask, as is widely known, and the laser beam is applied to a pixel portion within the pattern display area in a light transmissible state. Through. The energy density distribution of each transmitted light after being divided for each pixel and transmitted is the same as the shape formed by the beam homogenizer 3 and is evenly distributed.

The beam homogenizer 3 is a general term for optical components for shaping a laser beam having, for example, a Gaussian energy density distribution into a smoothed energy density distribution shape. As the optical component, for example, a fly-eye lens, binary optics, or a cylindrical lens is used to irradiate the mask surface at a time or scan the mask surface by driving a mirror such as a polygon mirror or a mirror scanner. There is.

Here, the pulse width of the laser beam is 1
0 to 500 ns and the energy density is 0.15 to
Control within the range of 3.5 J / cm ² . The laser beam
When controlled within such a numerical range, the above-described dot mark having a unique form of the present invention can be efficiently formed.

The laser beam in dot units that has passed through the liquid crystal mask 4 is subsequently applied to the beam profile converter 5. The beam profile converters 5 are similarly arranged in a matrix corresponding to the individual liquid crystals arranged in a matrix of the liquid crystal mask 4. Therefore, the laser beam transmitted through the liquid crystal mask 4 passes through the beam profile converter 5 for each pixel in a one-to-one correspondence, and the laser beam having the energy density distribution smoothed by the beam homogenizer 3 respectively. Is converted into an energy density distribution shape necessary for forming a minute dot mark shape unique to the present invention. In this embodiment, as described above, the laser beam after passing through the liquid crystal mask 4 is passed through the beam profile converter 5 to convert the energy density distribution shape. May be directly introduced into the next reduction lens unit 6 without converting the profile.

The laser beam that has passed through the beam profile converter 5 is converged by the reduction lens unit 6 and is applied to a predetermined position on the surface of the semiconductor wafer W, and required dot marking is performed on the surface. In the present embodiment, the maximum length of the liquid crystal in pixel units is 50 to 2000 μm.
m is reduced to 1 to 15 μm on the surface of the semiconductor wafer W by the reduction lens unit 6. The dot mark formed at this time has a maximum length in a size range of 1 to 15 μm, and the size of the unevenness is 0.01 to 5 μm in consideration of a case where the periphery of the raised portion is slightly depressed. To form a dot mark of such dimensions,
Semiconductor wafer W depending on resolution of reduction lens unit
It is necessary that the length of one side per dot of the liquid crystal mask 4 is 50 to 2000 μm in order to prevent the image formation at the irradiation point on the surface from being distorted.

Further, the beam profile converter 5
If the distance between the liquid crystal mask 4 and the liquid crystal mask 4 is too large or too small, the image formed on the surface of the semiconductor wafer is disturbed due to the influence of peripheral light rays or the instability of the optical axis. Easy to occur. Therefore, in the present embodiment, the arrangement interval X between the beam profile converter 5 and the liquid crystal mask 4 needs to be set to 0 to 10 times the maximum length of the liquid crystal mask 4 in one pixel unit. . By setting the arrangement interval in such a range, the image formed on the wafer surface becomes clear.

The beam profile converter 5 is an optical component for converting the energy density distribution smoothed by the beam homogenizer 3 into an optimal energy density distribution shape for obtaining a dot shape unique to the present invention. In this method, the profile of the energy density distribution of the incident laser light is converted into an arbitrary shape by arbitrarily changing a light transmittance at a laser irradiation point, a diffraction phenomenon, a refraction phenomenon, or the like. The optical components include, for example, a diffractive optical element, a holographic optical element, a convex microlens array, and a liquid crystal itself. These are arranged in a matrix and used as a beam profile converter 5.

The laser beam that has passed through the beam profile converter 5 is converged by the reduction lens unit 6 and radiated on the semiconductor wafer W to perform necessary dot marking.

In turn, the wafer carrier 10 of the present invention
In general, this type of wafer cassette or carrier is molded from a synthetic resin material, and thus usually has optical anisotropy. In order to image a dot mark in a minute form as described above, it is necessary that the window has no optical anisotropy and is made of a material having excellent light transmittance. Therefore, it is desirable to use hard glass, acrylic resin, or the like as the material of the window portion 15. Further, as shown in FIG. 2, the dot mark has a flat surface of a chamfer formed at the upper and lower edges of a V-shaped notch N indicating the orientation of the crystal axis of the semiconductor wafer W as a dot mark forming surface N1. It is formed on any of them. When the semiconductor wafer W is stored in the wafer carrier 10, the notch N is generally stored so as to be located on the side of the wafer carrier 10 opposite to the wafer insertion opening. Therefore, in the present embodiment, the disposition position of the window portion 15 is the side wall portion opposite to the opening of the case main body 11 as described above.

In the present embodiment, the dot mark forming surface N1 is a flat surface of a chamfered portion formed at the upper and lower edges of the notch N. However, the present invention is not limited to this flat surface, and may be formed at the peripheral edge of the semiconductor wafer W, for example. The flat surface of the chamfered portion to be formed may be used.

Further, in the present embodiment, as shown in FIG. 4, near the inner surface side of the window portion 15, the wafer 15 is arranged at equal intervals in the wafer carrier 10 and stored vertically in multiple stages. Dot mark forming surface N1 of each of a plurality of semiconductor wafers W
The reflecting mirror 16 is installed so as to face the required angle of inclination θ. In addition, a magnifying lens 19 is provided between each reflecting mirror 16 and the mark forming surface N1 of the semiconductor wafer W, and the dot mark on the mark forming surface N1 is formed through the magnifying lens 19, the reflecting mirror 16, and the window 15. Image by the image pickup device 17. The optical axis of the imaging device 17 is substantially perpendicular to the transparent window 15. Therefore, it is necessary to adjust the inclination angle θ of the reflecting mirror 16 in advance so that the reflected image of the dot mark by the reflecting mirror is formed on the optical axis of the imaging device 17. Further, in the present embodiment, spacers 18 are respectively arranged between the inner surface of the transparent window portion 15 and the peripheral edge of each semiconductor wafer W to regulate the free movement of the semiconductor wafer.

FIG. 4 shows a mechanism for reading dot marks formed in a dot mark forming area of a semiconductor wafer accommodated in multiple stages aligned with the closed wafer carrier 10 according to the present invention. In this figure, the peripheral edge chamfered portion of the semiconductor wafer W is used as a mark forming region for easy understanding. Now, when the mark forming area is illuminated by an illumination source (not shown), the dot marks formed in the mark forming area are magnified by the magnifying lens 19, reflected horizontally by the reflecting mirror 16, and transmitted through the transparent window 15. I do. The transmitted mark image is formed on the image forming plane of the image pickup device. Normally, a CCD camera is used as the imaging device 17, and its image is electrically recorded and displayed on a CRT screen.

As described above, according to the mark reading apparatus of the present invention, even a very small dot mark is formed into an enlarged image through the magnifying lens 19 and its optical path is reflected by the reflecting mirror 16.
Through the transparent window portion 15 at substantially right angles through the
7, the image can be reliably captured even if the mark is a minute mark.
Since the optical axis of the mark image reflected at 6 is transmitted substantially perpendicularly to the transparent window 15, the image can be taken without any image collapse at the window 15 due to refraction or the like. As a result, accurate imaging is possible.

FIG. 5 shows a typical embodiment of the dot mark reading device of the present invention.
A rotary table 101 is mounted on the rotary table 101. A crossbar 10a for positioning a wafer carrier or a wafer carrier positioning section 21 formed on the lower surface of the bottom of the wafer carrier 10 is fitted on the upper surface of the rotary table 101. A mounting recess 101a is formed. Therefore, the cross bar 10 a of the wafer carrier 10 or the wafer carrier positioning portion 21 is connected to the fitting portion 1 of the turntable 101.
01a, and the wafer carrier 10 is placed on the upper surface of the turntable 101.
Is positioned and fixed on the rotary table 101, and rotates with the rotation of the rotary table 101.
The rotary drive mechanism of the rotary table 101 is described in, for example,
A conventional mechanism described in JP-A-212436 and known in the art can be employed. For example, a stepping motor or various servomotors are used as the driving source, and the rotation angle θ is controlled by the controller 105. Control with high precision.

On the other hand, in the present embodiment, in addition to the rotary table 101, the wafer carrier 1
Image pickup device (CCD) for picking up an image of a dot mark formed in, for example, a V notch of the semiconductor wafer W accommodated in the semiconductor wafer W
A column 103 for supporting the camera 17 is provided upright. The imaging device 17 is attached to the tip of an arm 104 that is controllably movable in the vertical direction (z-axis direction) along the column 103, and the column 103 is controllably movable in the y-axis direction. The driving control of the column 103 and the arm 104 is performed by the controller 105.

The dot mark is illuminated by the illumination source 113 from the outside through the window 15 toward the chamfered portion on the upper surface side, which is the mark formation area of the V notch N, and the dot image is illuminated. The light is magnified through the magnifying lens 19 disposed above, and is further reflected by the reflecting mirror 16 also installed on the same reflection optical axis, thereby obtaining the window 1.
5 is transmitted through a reflection optical axis set so as to be substantially orthogonal to the transmission surface, and forms an image on an imaging plane in an image pickup device 17 which is similarly arranged with the optical axis of the light receiving port aligned with the optical axis. .

FIG. 6 is a block diagram of a signal processing system of the mark reading apparatus. In the present embodiment, a plurality of semiconductor wafers W stored in the wafer carrier 10 are positioned while being stored in the same carrier 10, and the positioning data is stored in the controller 105 for each wafer W, and each wafer W is stored. The positioning adjustment of the semiconductor wafer W is performed based on the positioning data stored for each.

First, the wafer carrier positioning crossbar 10a or the wafer carrier positioning portion 21 formed on the back side of the wafer carrier 10 accommodating a plurality of wafers W is fitted to the surface of the rotary table 101. The wafer carrier 10 is set on the turntable 101 by being fitted and positioned in the mounting recess 101a. Next, the wafer carrier 1 stored in the controller 105
A signal is issued based on the storage position data of each wafer W in 0, and a table rotation drive motor (not shown) starts operating based on a command from the controller 105 to rotate the rotary table 101 by a required angle. . Then, a drive motor (not shown) in the z-axis direction is operated, and up to a height position corresponding to the storage position of the wafer W to be positioned.
The arm 104 attached to the column 103 is moved in the z direction.

When this movement is completed, a drive motor (not shown) in the y-axis direction is operated to move the column 103 itself toward the semiconductor wafer W to be positioned. When the column 103 moves on the y-axis and a position sensor (not shown) detects a predetermined detection position, a drive motor for rotating the table (not shown) starts operating based on a command from the controller 105 to rotate the table. By rotating the table 101 by a further minute angle, the position of the reading surface is finely adjusted.

FIG. 7 is a block diagram showing a schematic configuration of the mark reading apparatus. In the mark reading device according to the present embodiment, the rotation table 101 enables the control rotation about the z-axis. In addition, the column 103 is controlled to move in the y-axis direction, and the arm 104 guided and supported by the column 103 is controlled to move on the column in the z-axis direction. These control operations are performed by driving the motor driver unit 112 via the stage control unit (controller) 105 by a signal from the main control unit 110 connected to the image processing unit 111.

The light receiving port is formed in the flat portion N1 of the chamfered portion on the upper surface side of the V notch formed in the peripheral portion of any one of the plurality of semiconductor wafers W accommodated in the wafer carrier 10. Toward, CCD camera (imaging device) 17
Are supported by the column 103 via the arm 104.
An illumination light source (irradiation optical system) 113 is also directed to the flat portion N1 at a predetermined angle with respect to the camera 17, and is fixed on the arm 104, similarly to the CCD camera 17. The illumination light amount of the illumination light source 113 and the like are determined by the image processing unit 1.
This is performed by controlling the illumination power supply 115 based on a signal from the eleventh illumination control unit 111a. The CC
Adjustment of the focus and the like of the D camera 17 is also performed by the image processing unit 1
The camera control unit 114a receives the signal from the image input unit 111b.

In this embodiment, the optical axis of the CCD camera 17 is consequently the light irradiation surface through the window 15, the reflecting mirror 16 and the magnifying lens 19 provided on the sealed wafer carrier 10. The illumination light is directed obliquely upward from the illumination light source 113 at a desired opposing angle with respect to the intersection of the optical axis of the camera 17 and the V notch reading surface with respect to the mark reading surface of the V notch N1. Irradiated. Thus, in the present invention, the light emitted from the illumination light source 113 is preferably irradiation with incoherent light closer to natural light than coherent light as described above, but may be coherent light. According to the present embodiment, the light received by the camera 17 with respect to the light image of the dot mark is not a parallel reflected light having a uniform directivity due to the parallel light, but a diffusely reflected light flux in a predetermined area which is diffusely reflected from an illumination area.

The relationship between the illumination and the imaging is as follows.
In the case where the dot mark formed in the V notch N of the semiconductor wafer W has a raised form, it is advantageous that the positioning of the camera 3 and the camera 17 does not require very strict positioning accuracy and various arrangements can be set. When the amount of irregularly reflected light between the dot mark and the irradiation surface around the dot mark is compared, most of the irregularly reflected light received by the camera 17 is made on the surface of the dot mark. , A high-luminance point-shaped light image having a large luminance difference from the surroundings can be obtained, and the dot mark can be reliably recognized.

FIG. 8 shows a dot mark reading procedure according to the present embodiment. Now, when the illumination power supply 115 is turned on and the illumination light source 113 is turned on, the area (dot notch inner surface) on which the dot mark is written is first detected, and the wafer carrier 10 mounted and fixed on the rotary table 101 is detected.
Is determined. This positioning is performed by controlling and driving the motor driver unit 112 to control the rotation of the rotary table 101 about the z-axis and the control movement of the arm 104 guided and supported on the column 103 on the y-axis. When the positioning adjustment is completed, the image of the dot mark is read by operating the camera 17, and the image information is digitally processed to recognize the information content. At this time, if the information content is not recognized or is unclear, the reading area on the inner surface of the V notch is detected again, and the above operation is performed again.

When the reading of the dot mark written on one semiconductor wafer W is completed, the arm 104 on the column 103 is moved up and down, the rotary table 101 is rotated by a required angle, and then read. By positioning the camera 17 with respect to the semiconductor wafer W,
The dot mark is read by irradiating the dot mark formation region with illumination light from the illumination light source 113. Hereinafter, the above operation is repeated to read the dot marks written in the V notches N of all the semiconductor wafers W stored in the sealed wafer carrier 10.

In the above embodiment, the rotary table 10
1 is rotated about the z-axis, but the rotary table 101 may be moved up and down or tilted. By doing so, it is possible to more precisely control the direction of the reflection optical axis of the reflection mirror 16 and the like. Also CCD
Even if the camera 17 and the illumination light source 113 are tilted,
Similar effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a typical basic structure of a sealed wafer carrier according to the present invention as viewed from the bottom side.

FIG. 2 is a partial perspective view showing an example of a formation area of a minute dot-mark which is a mark reading reference of the present invention.

FIG. 3 is an explanatory view schematically showing a configuration example of a typical laser marking device for forming the minute dot mark.

FIG. 4 is a schematic diagram of a sealed wafer carrier according to the present invention and an explanatory diagram of a mark reading mechanism formed on a peripheral edge of a semiconductor wafer in the carrier.

FIG. 5 is a three-dimensional view showing a typical example of a dot mark reading device for a semiconductor wafer housed in a wafer carrier according to the present invention.

FIG. 6 is a block diagram of a signal processing system of the dot mark reading device.

FIG. 7 is a block diagram showing a schematic configuration of the dot mark reading device.

FIG. 8 is an explanatory diagram showing a dot mark reading procedure by the dot mark reading device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser marking device 2 laser oscillator 3 beam homogenizer 4 liquid crystal mask 5 beam profile converter 6 reduction lens unit 10 sealed wafer carrier 10 a crossbar 15 window 16 reflecting mirror 17 imaging device (CCD camera) 18 spacer 19 relay lens (enlargement) Lens) unit 21 wafer carrier positioning unit 100 base 101 turntable 103 support 104 arm 105 controller (stage control unit) 110 main control unit 111 image processing unit 111a illumination control unit 111b image input unit 112 motor driver 113 illumination light source 114a camera control Unit 115 Illumination power supply W Semiconductor wafer O Center of V notch inner surface NV notch N1 Dot mark formation region (flat surface)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E096 AA06 BA16 BB04 CA08 DA13 DA18 DC02 FA11 FA30 5F031 CA02 DA08 EA12 EA14 EA19 EA20 FA01 FA11 GA35 GA36

Claims (5)

[Claims] 1. A sealed wafer carrier (10) for accommodating a plurality of semiconductor wafers (W) in multiple stages, wherein a transparent window portion is provided at a part of the semiconductor wafer (W) facing the peripheral surface of the accommodated semiconductor wafer (W). A sealed wafer carrier having (15), wherein a plurality of reflecting mirrors (16) are arranged in the vicinity of the inner surface of the window portion (15) at a wafer accommodation interval. 2. In the installation site of the transparent window (15),
A spacer (18) for keeping a constant distance between the periphery of each wafer (W) and the inner surface of the transparent window (15) corresponding to the storage position of the semiconductor wafer (W) is provided. The wafer carrier according to claim 1, wherein 3. A relay lens (19) is further provided between the reflecting mirror (16) and a peripheral mark forming surface of a semiconductor wafer (W) accommodated in a carrier. Item 3. The wafer carrier according to item 1 or 2. 4. A semiconductor wafer contained in a sealed wafer carrier (10) according to claim 1.
A mark reading device for reading various marks formed on the periphery of (W) from outside the carrier, comprising: a table (101) for positioning and fixing the wafer carrier (10); and a periphery of the table (101). An imaging device moving guide rod (103) disposed in the unit, an imaging device support member (104) that is guided and controlled by the guiding rod (103), and a light receiving port is a transparent window of the wafer carrier (10). (15), the imaging device (1) supported by the imaging device support member (104).
7) A mark reading device comprising: 5. A semiconductor wafer housed in a sealed wafer carrier (10) according to claim 1.
A mark reading method for reading various marks formed on the periphery of (W) from outside the carrier, wherein a transparent window (15) of the wafer carrier (10) containing a semiconductor wafer (W) is placed on an imaging side. Towards the wafer carrier (10)
Is positioned and fixed on a rotary table (101), and the optical axis of a light image of a mark formed on the mark forming area (N1) reflected by the reflecting mirror (16) is a lighting port of the imaging device (17). Adjusting the optical axis to coincide with the optical axis of, including imaging the reflected light image of the mark formed in the mark forming area (N1) by the reflecting mirror (16) by the imaging device (17). A mark reading method.