JP2020008383A - Dicing chip inspection device - Google Patents

Abstract

To provide a method for inspecting a diced wafer for defects such as crack or chipping hidden in a dicing line.SOLUTION: There is provided a device for inspecting device chips c arranged on a dicing wafer, comprising: a wafer holding unit, an imaging unit 3, a relative movement unit, an inspection recipe registration unit, and a control unit. The control unit includes a peripheral area inspection mode in which, while imaging with a prescribed imaging magnification along a dicing line DL of a diced wafer so that the dicing line DL is included, the peripheral area Re of device chips is inspected, and a device area inspection mode in which imaging is performed so as to skip the dicing line with a lower imaging magnification than in the peripheral area inspection mode and a device area is inspected. An inspection recipe for executing the device area inspection mode and/or the peripheral area inspection mode is registered in the inspection recipe registration unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a dicing chip inspection apparatus for inspecting a device region and a peripheral region of a device chip arranged on a wafer having scribe lines formed or diced.

  2. Description of the Related Art A dicing apparatus is known as an apparatus for cutting or scribing a workpiece such as a wafer on which a semiconductor device or an electronic component is formed (for example, Patent Documents 1 and 2).

  In addition, a technique has been proposed in which an abnormality in a processing size, a processing state, or the like is detected by imaging a workpiece during dicing processing, and a countermeasure is taken according to the abnormal state (for example, Patent Document 2).

  In addition, a technique of imaging one device chip at a time on a wafer on which a scribe line is formed or diced, and inspecting an effective area (that is, a device area) and an edge (that is, a peripheral area) of the device chip ( That is, an inspection using an inspection apparatus has been proposed (for example, Patent Document 3).

JP-A-62-53804 JP 2009-253017 A JP-A-2017-161236

  In the technique disclosed in Patent Document 2, when trying to detect minute cracks (cracks) or the like, the moving speed of the wafer (that is, the cutting speed) is set to an extent that does not affect the inspection quality while increasing the imaging magnification. ).

  On the other hand, there is a need to increase the number of processed wafers per unit time (so-called WPH) as much as possible. Inspection during dicing involves checking the position of the processing groove (kerf), the width of the kerf, and the presence or absence of large chipping (chipping). In addition to measurement, detection of minute cracks and the like has been left to a dedicated machine (that is, an inspection device).

  However, in the inspection by the inspection apparatus, both the device region of the device chip and the chip end (that is, the peripheral region) on which the dicing line (including the scribe line; the same applies hereinafter) are formed with a predetermined accuracy within a predetermined time. Although there is a need for inspection, if all the divided areas are inspected at the same high magnification, the inspection time for one wafer becomes long. On the other hand, there is a rule that if all the divided areas are inspected at the same low magnification in order to shorten the inspection time, defects such as minute cracks hidden in the dicing line cannot be reliably detected. Therefore, there has been a demand for an inspection apparatus that can inspect both the device region and the peripheral region with a predetermined accuracy within a predetermined time.

  Therefore, the present invention has been made in view of the above-described problems, and reliably detects defects such as cracks, chipping, and film peeling lurking in a dicing line of a wafer on which a scribe line is formed or diced, and detects a defect of a device chip. It is an object of the present invention to provide a dicing chip inspection apparatus capable of reducing a time for inspecting a device area.

In order to solve the above problems, one embodiment of the present invention provides:
In a dicing chip inspection device for inspecting a device region and a peripheral region of a device chip arranged on a diced wafer,
A wafer holding unit for holding a wafer,
An imaging unit that images a predetermined area set on the wafer at a predetermined imaging magnification;
A relative moving unit that relatively moves the wafer and the imaging unit;
An inspection recipe registration unit that registers the direction and speed of the relative movement in the relative movement unit, and the imaging magnification and the imaging position in the imaging unit as an inspection recipe,
A control unit that controls the imaging unit and the relative movement unit based on the inspection recipe,
The control unit is
A peripheral area inspection mode for performing imaging along the dicing line so as to include a dicing line of a wafer diced at a predetermined imaging magnification and inspecting a peripheral area of a device chip;
At a lower imaging magnification than the peripheral area inspection mode, imaging is performed so as to skip a dicing line, and a device area inspection mode for inspecting a device area is provided.
The inspection recipe registration unit registers an inspection recipe for executing at least one of the device area inspection mode and the peripheral area inspection mode.

  According to the above dicing chip inspection apparatus, an area (peripheral area) along the dicing line is imaged with a high magnification field size in the peripheral area inspection mode, and defects such as cracks and chipping can be reliably detected. . On the other hand, in the device area inspection mode, the inspection time can be reduced by imaging the device area of the device chip with a relatively small magnification field of view.

FIG. 1 is a schematic diagram illustrating an entire configuration of an example of an embodiment embodying the present invention. It is a perspective view showing an important section of an example of an embodiment which embodies the present invention. It is a conceptual diagram in an example of the form which embodies the present invention. It is a conceptual diagram in an example of the form which embodies the present invention. It is a flow figure in an example of the form which embodies the present invention.

  An embodiment for carrying out the present invention will be described below with reference to the drawings.

  In the following description, three axes of the rectangular coordinate system are represented by X, Y, and Z, the horizontal direction is represented by the X direction and the Y direction, and the direction perpendicular to the XY plane (that is, the direction of gravity) is represented by the Z direction. I do. In the Z direction, the direction against gravity is expressed as “up”, and the direction in which gravity acts is expressed as “down”. The direction in which the Z direction rotates about the center axis is defined as the θ direction.

  FIG. 1 is a schematic diagram showing an entire configuration of an example of an embodiment embodying the present invention. FIG. 1 shows a schematic diagram of a dicing chip inspection apparatus 1 according to the present invention.

  The dicing chip inspection apparatus 1 inspects a device region Rc and a peripheral region Re of a device chip C arranged on a diced wafer W. The device region Rc is a region where the main circuit of the device chip C is patterned. On the other hand, the peripheral region Re is a region arranged around (outside) the device region Rc of the device chip C, and is a region set to allow a positional shift of the dicing line DL (a blank region). , And cut off).

  The peripheral area Re of the device chip C is adjacent to the dicing line DL. The dicing line DL is a groove formed when the wafer W is scribed or cut, and is actually a space between ridge lines of the processed wafer W. In the present application, for convenience of description, the dicing line DL including the ridge line of the processed wafer W is called.

  Specifically, the dicing chip inspection device 1 includes a wafer holding unit 2, an imaging unit 3, a relative movement unit 4, an inspection recipe registration unit 5, a control unit 9, a computer CN, and the like.

  The wafer holding unit 2 holds the wafer W. For example, the lower surface side of the diced wafer W is held using a wafer ring R (also called a flat ring or a dicing ring) and an expanded sheet (not shown). More specifically, the wafer holding unit 2 maintains the horizontal state while supporting the wafer W from below by way of a wafer ring R or the like. More specifically, the wafer holding unit 2 includes a wafer mounting table 20 having a horizontal upper surface.

  The wafer mounting table 20 is provided with a groove or a hole at a portion that comes into contact with a wafer ring or the like holding the wafer W. These grooves and holes are connected to a negative pressure of a vacuum pump or the like via a switching valve or the like. It is connected to the generating means. The wafer holding unit 2 can hold or release the wafer ring or the like by switching these grooves and holes to a negative pressure state or an atmosphere release state.

  The imaging unit 3 captures an image of a predetermined area set on the wafer W at a predetermined imaging magnification. Specifically, the imaging unit 3 captures an image of the device region Rc and the peripheral region Re to be inspected, and switches the imaging magnification so as to capture an image at an appropriate imaging magnification for these regions. are doing. More specifically, the imaging unit 3 includes a lens barrel 30, an illumination unit 31, a half mirror 32, a plurality of objective lenses 33a and 33b, a revolver mechanism 34, an imaging camera 35, and the like.

  The lens barrel 30 fixes the illumination unit 31, the half mirror 32, the objective lenses 33a and 33b, the revolver mechanism 34, the imaging camera 35, and the like in a predetermined posture, and guides illumination light and observation light. The lens barrel 30 is attached to the apparatus frame 1f via a connection fitting or the like (not shown).

  The illumination unit 31 emits illumination light L1 necessary for imaging. Specifically, the illumination unit 31 can be exemplified by a laser diode, a metal halide lamp, a xenon lamp, and an LED illumination.

  The half mirror 32 reflects the illumination light L1 emitted from the illumination unit 31 and irradiates it to the wafer W side, and passes light (reflected light, scattered light) L2 incident from the wafer W side to the imaging camera 35 side. It is.

The objective lenses 33a and 33b form images of the imaging area on the workpiece W on the imaging camera 35 at different predetermined observation magnifications.
The revolver mechanism 34 switches which of the objective lenses 33a and 33b is used. Specifically, the revolver mechanism 34 rotates and stops at predetermined angles at a time based on manual or external signal control.

  The imaging camera 35 captures an image of the imaging area F on the workpiece W and acquires an image. The acquired image is output to the outside (in the present invention, a chip position calculation unit described in detail later) as a video signal or video data.

The relative moving unit 4 relatively moves the wafer holding unit 2 and the imaging unit 3.
Specifically, the relative moving unit 4 includes an X-axis slider 41, a Y-axis slider 42, and a rotation mechanism 43.

  The X-axis slider 41 is mounted on the apparatus frame 1f, and moves the Y-axis slider 42 at an arbitrary speed in the X direction and stops at an arbitrary position. More specifically, the X-axis slider includes a pair of rails extending in the X direction, a slider unit that moves on the rail, and a slider drive unit that moves and stops the slider unit. The slider driving unit can be configured by a combination of a servo motor or a pulse motor that rotates and stops by signal control from the control unit CN and a ball screw mechanism, a linear motor mechanism, or the like. Further, the X-axis slider 41 is provided with an encoder for detecting the current position and the moving amount of the slider section. The encoder may be, for example, a linear member called a linear scale in which fine irregularities are carved at a predetermined pitch, a rotary encoder that detects the rotation angle of a motor that rotates a ball screw, and the like.

  The Y-axis slider 42 moves the rotation mechanism 43 in the Y direction at an arbitrary speed and stops at an arbitrary position based on a control signal output from the control unit CN. Specifically, the Y-axis slider includes a pair of rails extending in the Y direction, a slider unit that moves on the rail, and a slider drive unit that moves and stops the slider unit. The slider driving unit may be configured by a combination of a servo motor or a pulse motor that rotates and stops by signal control from the control unit CN and a ball screw mechanism, a linear motor mechanism, or the like. The Y-axis slider 42 is provided with an encoder for detecting the current position and the amount of movement of the slider section. The encoder may be, for example, a linear member called a linear scale in which fine irregularities are engraved at a predetermined pitch, a rotary encoder that detects a rotation angle of a motor that rotates a ball screw, and the like.

  The rotation mechanism 43 rotates the wafer mounting table 20 at an arbitrary speed in the θ direction and stops at an arbitrary angle. Specifically, as the rotation mechanism 43, a mechanism that rotates / stops at an arbitrary angle by signal control from an external device such as a direct drive motor can be exemplified. The wafer mounting table 20 of the wafer holding unit 2 is mounted on a member on the rotating side of the rotation mechanism 43.

  Since the relative moving unit 4 has such a configuration, the wafer W is independently or combined in the XYθ direction with respect to the imaging unit 3 in a predetermined manner while holding the wafer W to be inspected. It can be relatively moved at a speed or angle, or can be stopped at any position or angle.

  FIG. 2 is a perspective view showing a main part of an example of an embodiment embodying the present invention. FIG. 2 shows a state in which the peripheral area Re of the device chip C is sequentially imaged while the wafer W and the imaging unit 3 are relatively moved along the dicing line DL, and the imaging area F is moved in the direction indicated by the arrow Vs. ing.

  The inspection recipe registration unit 5 registers the direction and speed of the relative movement in the relative moving unit 4, the imaging magnification and the imaging position in the imaging unit 3, and the like as an inspection recipe. The inspection recipe registration unit 5 can register an inspection recipe relating to a device area inspection mode and a peripheral area inspection mode, which will be described in detail later. An inspection recipe for executing both or at least one of these modes is registered. ing. Specifically, the inspection recipe registration unit 5 captures an image of a place on the wafer W at what imaging magnification and in what order (that is, the imaging route T) in each of the device area inspection mode and the peripheral area inspection mode. Alternatively, information (also referred to as recipe information) such as what to do with the moving speed and the imaging interval and the moving pitch and the feed speed at that time can be registered as an inspection recipe for each inspection type.

The control unit 9 has, for example, the following functions and roles.
-Outputs a signal for holding / releasing the wafer W to the wafer holding unit 2-Switching the objective lens (imaging magnification) to be used by controlling the revolver mechanism 34-Outputting an imaging trigger to the imaging camera 35 Driving control of the relative moving unit 4: a function of outputting a driving signal while monitoring the current positions of the X-axis slider 41, the Y-axis slider 42, and the rotating mechanism 43. An imaging position, an imaging route T, an imaging interval (pitch) , Interval) registration, registration of inspection recipe, switching of inspection recipe to be used, inspection based on captured image

  More specifically, the control unit 9 includes a computer CN, a programmable logic controller and the like (that is, hardware), and an execution program and the like (that is, software). Further, the inspection recipe registration unit 5 is configured by a part of a storage unit (register, memory, HDD, SSD, etc.) of the computer CN.

  Further, the control unit 9 controls the imaging unit 3 and the relative moving unit 4 based on the inspection recipe, and sets a peripheral area inspection mode and an operation mode called a device area inspection mode (for example, a setting screen or the like). ) And execution means (computer CN and control equipment, etc.).

  FIG. 3 is a conceptual diagram illustrating an example of an embodiment embodying the present invention. FIG. 3 illustrates an imaging route T and an imaging region F in the peripheral region inspection mode.

  In the peripheral area inspection mode, an image is taken along the dicing line DL so as to include the dicing line DL of the wafer W diced at a predetermined imaging magnification (relatively high magnification), and the peripheral area of the device chip C is taken. This is an operation mode for checking Re.

  Specifically, in the peripheral area inspection mode, as shown in FIG. 3A, imaging is performed along an imaging route T that relatively moves the imaging area F along a dicing line DL extending in the X direction. As shown in FIG. 3 (b), while performing imaging along an imaging route T that relatively moves the imaging region F along a dicing line DL extending in the Y direction, cracks lurking in the dicing line DL over the entire surface of the wafer W The inspection of the peripheral region Re is performed at a predetermined imaging magnification (relatively high magnification) at which a defect such as chipping can be reliably detected.

  More specifically, in the peripheral area inspection mode, an edge extraction process is performed to detect a chip end portion (that is, a ridge line) of the device chip C, and a part of the ridge line does not enter a preset intrusion prohibited area. Whether or not cracks or chippings extending from the ridge line have entered the intrusion prohibited area is inspected.

  In the embodiment shown in FIG. 3, the imaging magnification and the imaging region F, the peripheral region Re of a plurality of device chips arranged adjacent to each other are simultaneously imaged in a positional relationship straddling the dicing line DL. The imaging route T and the like are set in the inspection recipe registration unit 5.

  FIG. 4 is a conceptual diagram illustrating an example of an embodiment of the present invention. FIG. 4 illustrates an imaging route T and an imaging region F in the device area inspection mode.

  In the device area inspection mode, imaging is performed at an imaging magnification T lower than the imaging magnification in the peripheral area inspection mode, along an imaging route T that relatively moves the imaging area F so as to skip the dicing line DL of the diced wafer W, This is an operation mode for inspecting the device region Rc of the device chip C over the entire surface of the wafer W.

  Specifically, in the device region inspection mode, a predetermined magnification (eg, a predetermined magnification (eg, a predetermined magnification factor) is used to determine whether a foreign substance or a scratch is present on the device region Rc, whether a clear pattern collapse, a film formation failure, or the like has occurred. Imaging and inspection of the device region Rc are performed at a relatively low magnification.

  More specifically, in the device region inspection mode, an image (a so-called teaching image) in which no foreign matter, scratch, pattern collapse, film formation failure, or the like has occurred in the device region Rc is registered in advance. The image is compared with an image of the device region Rc taken for inspection from now on, and it is inspected whether a foreign substance, a scratch, a pattern collapse, a film formation defect, or the like has occurred in the device region Rc.

  In the embodiment shown in FIG. 4, the imaging magnification, the imaging region F, the imaging route T, and the like are set such that the predetermined region imaged in the device region inspection mode skips the predetermined region imaged in the peripheral region inspection mode. This is set in the inspection recipe registration unit 5.

  FIG. 5 is a flowchart illustrating an example of an embodiment of the present invention. FIG. 5 shows a configuration in which the device region Rc and the peripheral region Re of the device chip C arranged on the wafer W are imaged and inspected using the dicing chip inspection apparatus 1 as a series of steps for each step. .

  First, an inspection recipe is set (step s11), and an inspection mode and an order of the wafer W are determined. Next, the wafer W is mounted on the wafer mounting table 20 of the dicing chip inspection apparatus 1 (step s12), and is moved to a reading position of a reference mark (not shown) formed on the wafer W to perform alignment ( Step s13).

  Subsequently, the mode is switched to the peripheral area inspection mode based on the inspection recipe (step s21), and the revolver mechanism 34 is rotated so that a high-magnification lens is selected (step s22). Then, the imaging / inspection is performed while the imaging unit 3 and the relative moving unit 4 are relatively moved (step s23). It is determined whether or not all imaging in this mode has been completed (step 24), and if not completed, imaging and inspection are continued. If the imaging has been completed, it is determined whether to execute another inspection mode (step s25).

  If another inspection mode (that is, a device area inspection mode) is to be executed, the mode is switched to the device area inspection mode (step s31), and the revolver mechanism 34 is rotated so that a low-magnification lens is selected (step s31). s32). Then, imaging and inspection are performed while the imaging unit 3 and the relative moving unit 4 are relatively moved (step s33). It is determined whether or not all imaging in this mode has been completed (step 34). If not, imaging / inspection is continued. If the imaging has been completed, the wafer W is paid out of the apparatus (step s41). It should be noted that the wafer W is paid out of the apparatus even when another inspection mode is not executed in step 25 (step s41).

  Then, it is determined whether or not imaging / inspection of the next wafer W is to be performed (step s42). When imaging / inspection is to be performed, steps s12 to s41 described above are repeated. On the other hand, when imaging / inspection is not performed, the inspection ends.

  In the above description, the procedure for executing the peripheral area inspection mode first and then executing the device area inspection mode has been exemplified. However, in implementing the present invention, the order of these inspection modes may be reversed. In addition, these inspection modes indicate a series of operation flows and states, and are not limited to cases where registration is performed in a state specified in the inspection recipe, and different imaging magnifications and imaging routes T are registered without being specified. Includes cases where

The output of the imaging trigger from the control unit 9 to the imaging unit 3 can be exemplified by the following method.
A method in which the illumination light L1 is emitted for a very short time (so-called strobe light) each time it moves a predetermined distance while being relatively moved in the X and Y directions for scanning.
-Alternatively, a relative position and a stationary state are set at a predetermined position, and the illumination light L1 is irradiated in a stationary state to capture an image (so-called step & repeat).

  Further, the imaging trigger means an image capturing instruction to the imaging camera 35 or an image processing device (not shown), an emission instruction of the illumination light L1, and the like. Specifically, as the imaging trigger, (case 1) the illumination light L1 is strobed during the time during which an image can be captured by the imaging camera 35 (so-called exposure time), or (case 2) the illumination light L1 is irradiated. Within a certain period of time. Alternatively, the imaging trigger is not limited to the instruction to the imaging camera 35, and (case 3) may be an image capturing instruction to an image processing apparatus that acquires an image. By doing so, it is possible to cope with a mode in which video signals and video data are sequentially output from the imaging camera 35.

  Since the dicing chip inspection apparatus 1 according to the present invention has such a configuration, in the peripheral area inspection mode, an area along the dicing line (that is, the peripheral area Re) is imaged with a high magnification field size, Defects such as cracks and chipping can be reliably detected (ie, inspected). On the other hand, in the device area inspection mode, the inspection time can be reduced by imaging the device area Rc of the device chip C with a relatively small magnification field of view. That is, the dicing chip inspection apparatus 1 can inspect both the device region Rc and the peripheral region Re with a predetermined accuracy within a predetermined time.

[Another form]
In the above description, the imaging magnification, the imaging region F, the imaging route T, and the like are set such that the peripheral regions Rc of the plurality of device chips C arranged adjacently are simultaneously imaged in a positional relationship across the dicing line DL. The configuration set in the inspection recipe registration unit 5 has been exemplified.

  Such a configuration is preferable because the number of times of imaging can be reduced, and the inspection time per wafer W can be reduced.

  However, when the width of the dicing line DL is large with respect to the imaging region F, the ridge line of the peripheral region Re is likely to be out of the field of view, or cracks and chips to be detected are small, and if the imaging magnification is increased, the dicing line DL may cross If the images cannot be taken simultaneously due to the positional relationship, the peripheral region Rc of one device chip C may be taken.

Reference Signs List 1 dicing chip inspection device 2 wafer holding unit 3 imaging unit 4 relative movement unit 5 inspection recipe registration unit 9 control unit 1f device frame 20 wafer mounting table 30 lens barrel 31 illumination unit 32 half mirror 33a, 33b objective lens 34 revolver mechanism 35 imaging Camera 41 X-axis slider 42 Y-axis slider 43 Rotation mechanism W Wafer C Device chip DL Dicing line (groove / gap)
F Imaging area (field of view)
Rc device area Re peripheral area (near ridge line)
L1 Illumination light L2 Light incident from the wafer side (reflected light, scattered light)
T imaging route

Claims (2)

In a dicing chip inspection device for inspecting a device region and a peripheral region of a device chip arranged on a diced wafer,
A wafer holding unit for holding the wafer,
An imaging unit that images a predetermined region set on the wafer at a predetermined imaging magnification,
A relative moving unit that relatively moves the wafer and the imaging unit;
An inspection recipe registration unit for registering the direction and speed of the relative movement in the relative movement unit, and the imaging magnification and the imaging position in the imaging unit as an inspection recipe,
A control unit that controls the imaging unit and the relative movement unit based on the inspection recipe,
The control unit includes:
A peripheral area inspection mode for performing imaging along the dicing line so as to include a dicing line of the diced wafer at a predetermined imaging magnification, and inspecting the peripheral area of the device chip;
At an imaging magnification lower than the imaging magnification in the peripheral area inspection mode, imaging is performed so as to skip the dicing line, and a device area inspection mode for inspecting the device area,
A dicing chip inspection apparatus, wherein the inspection recipe for executing at least one of the device area inspection mode and the peripheral area inspection mode is registered in the inspection recipe registration unit. In the inspection recipe registration unit,
2. The dicing device according to claim 1, wherein the peripheral regions of the plurality of device chips arranged adjacent to each other are set so as to be simultaneously imaged in a positional relationship across the dicing line. 3. Chip inspection device.

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