JP2019063985A - Groove depth detection device and groove depth detection method - Google Patents

Abstract

To provide a groove depth detection device and a groove depth detection method for measuring the depth of a calf with a small error.SOLUTION: A calf depth measurement device 50 according to an aspect of the present invention is a calf depth measurement device 50 for measuring a depth of a calf k provided on a surface of a wafer W. The calf depth measurement device 50 comprises a width measurement unit for measuring a width of the calf k, a measurement head 64 positioned at a spacing from the calf k of the wafer and having a nozzle 66 for injecting compressed air toward the calf k, a first computation unit 70 for calculating the cross-sectional area of the calf k based on a flow rate of air flowing out of a clearance between the nozzle 66 and the calf k or a pressure change caused by a change in the flow rate, and a second computation unit 72 for calculating the depth of the calf based on a width of the calf k measured by the width measurement unit and the cross-sectional area of the calf k calculated by the first computation unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a kerf depth measuring apparatus, and more particularly to a kerf depth measuring apparatus for measuring the depth of a kerf (groove) cut by a blade when a semiconductor wafer is cut into semiconductor elements by a dicing apparatus. .

  In the semiconductor manufacturing process, various processes are performed on the surface of a thin plate-like semiconductor wafer to manufacture a plurality of semiconductor devices having electronic devices. Each chip of the semiconductor device is inspected for electrical characteristics by an inspection device, and then cut and separated into chips by a high-speed rotating blade of the dicing device.

  In a dicing machine, the depth of several tens of microns of kerf machined by a blade changes with blade wear, so the kerf depth is periodically measured to adjust the cutting depth of the blade to the semiconductor wafer. ing.

  The kerf depth measuring device of the dicing apparatus disclosed in Patent Document 1 measures the shape of the kerf with a laser displacement meter, and measures the depth of the kerf based on this shape. Specifically, a kerf is scanned by laser light of a laser displacement meter, and the shape and chipping situation are measured. The measurement of the depth of the kerf can not be performed by the measurement by the camera image, and by having the laser displacement meter, the depth measurement of the kerf can be realized.

JP 2003-168655 A

  The laser displacement meter of Patent Document 1 irradiates a kerf with a laser beam collected through a light projection lens, and receives a part of a light beam diffusely reflected from the kerf by a light receiving element through a light receiving lens, The shape of the kerf is measured by detecting the position of the spot light received by the light receiving element.

  Therefore, in the laser displacement meter, when minute unevenness is present on the side wall or bottom of the kerf, the value corresponding to the amount of unevenness is directly obtained as the shape of the kerf, so the minute unevenness is the depth of the kerf. There is a problem that it greatly affects the accuracy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a kerf depth measuring apparatus capable of measuring a kerf depth with a small error.

  In order to achieve the object of the present invention, one aspect of the kerf depth measuring apparatus of the present invention measures the width of the kerf in the kerf depth measuring apparatus that measures the depth of the kerf provided on the surface of the wafer. Changes in the flow rate or flow rate of the air flowing out from the gap between the width measurement unit, the measurement head having a nozzle spaced from the wafer kerf and injecting compressed air toward the kerf, and the gap between the nozzle and the kerf And the width of the kerf measured by the width measuring unit, and the kerf depth based on the cross-sectional area of the kerf calculated by the first calculating unit. And a second operation unit for calculating

  According to one aspect of the present invention, the depth of the kerf is calculated based on the width of the kerf and the cross-sectional area of the kerf. According to one aspect of the present invention, even when minute unevenness is present on the side wall or bottom of the kerf, the depth of the kerf is calculated based on the cross-sectional area of the kerf having little influence on the unevenness. Calf depth measurements can be made.

  One aspect of the present invention preferably includes a moving unit that moves the measuring head relatively along the surface of the wafer.

  According to one aspect of the present invention, in the case where a plurality of kerfs are provided on the surface of the wafer, the moving unit measures the depth of each kerf by moving the measuring head along the surface of the wafer. can do.

  In one aspect of the present invention, the wafer is held by a wafer chuck of a dicing apparatus that dices the wafer, and the width measurement unit performs image processing on the image obtained by the imaging unit for imaging a kerf and the imaging unit. The image processing unit calculates the width of the kerf, the measurement head is supported by the spindle or spindle support on which the blade of the dicing apparatus is supported, and the measurement head and the first calculation unit are configured as an air micrometer. The moving unit is preferably a moving mechanism that moves the wafer chuck and the spindle of the dicing apparatus in the horizontal direction.

  According to one aspect of the present invention, in the case of measuring the depth of a kerf of a wafer cut by a blade of a dicing apparatus, an existing member provided in the dicing apparatus as a member constituting the kerf depth measuring apparatus Functional members can be used.

  That is, a moving mechanism unit that holds the wafer by the wafer chuck of the dicing apparatus, supports the measurement head on the spindle or spindle support on which the blade is supported, and moves the wafer chuck and spindle of the dicing apparatus relatively in the horizontal direction , Used as a moving part of the calf depth measuring device. Then, in the dicing apparatus, an air micrometer for measuring the thickness of the wafer and setting the cut depth to the wafer is used as the measurement head and the first calculation unit. That is, an air micrometer for wafer thickness measurement provided in the dicing apparatus can be used as a kerf depth measurement apparatus.

  According to the kerf depth measurement device of the present invention, it is possible to perform kerf depth measurement with less error.

An outline view of a dicing apparatus on which the calf depth measuring apparatus of the embodiment is mounted Plan view of the table of the dicing apparatus shown in FIG. 1 An illustration using an air micrometer as a kerf depth measurement device Diagram explaining the principle of the method of measuring the depth of kerf with air micrometer Explanatory drawing showing the moving direction of the measuring head relative to the surface of the semiconductor wafer Explanatory drawing showing that the depth of a kerf was measured by moving a measurement head to one measurement area of a semiconductor wafer Graph showing change in air flow rate in one measurement area shown in FIG. 6

  Hereinafter, a preferred embodiment of a kerf depth measuring apparatus according to the present invention will be described in detail with reference to the attached drawings.

[Configuration of dicing apparatus 10]
FIG. 1 is an external view of a dicing apparatus 10 on which a kerf depth measuring apparatus according to an embodiment is mounted.

  The dicing apparatus 10 has a load port 12 for transferring a cassette in which a plurality of disk-shaped semiconductor wafers (wafers) W are stored to and from an external apparatus, and a suction pad 14. A transport unit 16 for transporting the wafer, a table 18 for sucking and holding the semiconductor wafer W, a processing unit 20 for dicing the semiconductor wafer W, and a spinner 22 for cleaning and drying the semiconductor wafer W after dicing processing There is. The operation of each part of the dicing apparatus 10 is controlled by a controller 24 as control means.

<Processing unit 20>
The processing unit 20 is provided with a camera (a width measurement unit, an imaging unit) 26. The camera 26 is used as a member for imaging the surface of the semiconductor wafer W to align the semiconductor wafer W by a known pattern matching method, and as a member for measuring the groove dimension of the kerf.

  Inside the processing unit 20, a pair of disc-like blades 28 disposed opposite to each other and a spindle 32 with a built-in high frequency motor for rotating the blades 28 are provided.

  The blade 28 is rotated at a high speed of 6000 rpm to 80 000 rpm by the spindle 32, and the index feed in the Y direction and the cut feed in the Z direction of FIG. Furthermore, a table 18 for holding the semiconductor wafer W by suction is configured to be ground and fed in the X direction in FIG. 1 by a moving shaft (not shown). The processing point (lowest point) of the blade 28 rotating at high speed is brought into contact with the semiconductor wafer W by these operations, and the semiconductor wafer W is diced in the X and Y directions. Thus, the semiconductor element is cut from the semiconductor wafer W into chips.

  As the blade 28, in addition to an electrodeposition blade in which diamond abrasive grains and CBN abrasive grains are electrodeposited with nickel, a blade of metal resin bond bonded with resin in which metal powder is mixed, or the like is used.

  Further, the feed amounts in the X, Y, and Z directions described above are adjusted by controlling the X, Y, and Z moving mechanism units (not shown) with the controller 24. The controller 24 cuts the semiconductor element from the semiconductor wafer W chip by chip while controlling the cutting feed amount in the Z direction in the X direction based on kerf depth information obtained by a kerf depth measurement device described later.

  FIG. 2 is a plan view of the table 18.

  The table 18 adsorbs and holds the semiconductor wafer W, and has a circular adsorption portion (wafer chuck) 34 in a plan view, and a ring-shaped main body 36 disposed on the outside of the adsorption portion 34 and supporting the adsorption portion 34 Equipped with

  The suction unit 34 is configured in a circular shape centered on the central axis 18A of the table 18. Moreover, the adsorption | suction part 34 is comprised by the porous member, and is connected to the vacuum source not shown via a vacuum path. By driving the vacuum source, air in the vacuum path is sucked, whereby the semiconductor wafer W is held by vacuum suction on the surface of the suction unit 34.

[Operation of dicing apparatus 10]
In the dicing apparatus 10, first, a cassette in which a plurality of semiconductor wafers W are stored is placed on the load port 12 by a transport apparatus (not shown) or manually. The semiconductor wafer W is taken out of the placed cassette and placed on the surface of the table 18 by the transfer device 16. After that, the back surface of the semiconductor wafer W is vacuum-held on the surface of the suction portion 34 of the table 18. Thus, the semiconductor wafer W is held on the table 18.

  The surface of the semiconductor wafer W held on the table 18 is imaged by the camera 26 of FIG. 1, and the position of the dicing cut line formed on the surface of the semiconductor wafer W and the position of the blade 28 are not shown. The table 18 is adjusted and adjusted by the moving mechanism units in the X, Y, and θ directions.

  When alignment is completed and dicing is started, the spindle 32 discloses rotation, and the blade 28 rotates at high speed, and cutting fluid is supplied to the processing point from a nozzle (not shown). In this state, the semiconductor wafer W is processed and fed in the X direction shown in FIG. 1 by a movement axis (not shown) together with the table 18, and the spindle 32 is lowered to a predetermined height and dicing is performed. By this operation, a kerf is cut on the surface of the semiconductor wafer W.

[Karf depth measuring device 50]
FIG. 3 is an explanatory view using a flow type air micrometer 52 as the kerf depth measurement device 50. As shown in FIG.

  The air micrometer 52 is not limited to the flow type, and air micrometers having other measurement principles such as a back pressure type, a vacuum type, and a flow speed type can be applied as the inspection apparatus.

  The air micrometer 52 adjusts the pressure of the compressed air supplied from the pump 58 to a constant pressure by the regulator 60, and the pressure of the measuring head 64 is set via the throttle (not shown) installed inside the A / E converter 62. Compressed air is injected from the nozzle 66 onto the surface of the semiconductor wafer W.

  The A / E converter 62 converts minute changes in the flow rate (pressure) between the nozzle 66 and the throttle into an electrical signal by means of a built-in bellows and a differential transformer, and outputs the electrical signal to the amplifier 68. The amplifier 68 amplifies this electrical signal.

  The amplified electric signal is output to the first calculation unit 70, and the first calculation unit 70 calculates the flow rate based on the electric signal, and calculates the cross-sectional area of the kerf k based on the calculated flow rate. That is, the first calculation unit 70 calculates the cross-sectional area of the kerf k based on the flow rate of air flowing out from the gap between the nozzle 66 and the kerf k or the pressure change caused by the change in the flow rate. The calculated cross-sectional area of the kerf k is output to the second calculation unit 72.

  On the other hand, the width of the kerf k from the image processing unit 74 is output to the second calculation unit 72. That is, the kerf k is imaged by the camera 26, and the image processing unit 74 performs image processing on the image information from the camera 26 to calculate the width of the kerf k. The width of the kerf k is output to the second calculation unit 72.

  The second operation unit 72 calculates the depth of the kerf k based on the width of the kerf k measured by the camera 26 and the image processing unit 74 and the cross-sectional area of the kerf k calculated by the first operation unit 70. . The calculation method will be described later. Also, the depth of the calculated calf k is displayed on the monitor 76.

  The measuring head 64 is attached to the moving mechanism (spindle support) 54 of the spindle 32 or Z, and is disposed apart from the surface of the semiconductor wafer W, and a nozzle 66 for injecting compressed air toward the surface. Have. In FIG. 3, the measuring head 64 is attached to the moving mechanism unit 54.

  The measuring head 64 is relatively moved along the surface of the semiconductor wafer W by the existing X and Y moving mechanism units (moving units) 78 and 80 of the dicing apparatus 10.

  The moving mechanism unit 78 includes a pair of rails 82 extending in the X direction, and a table support member 84 is slidably mounted on the rails 82. Further, the moving mechanism unit 78 includes a driving unit (not shown) for moving the table support member 84 in the X direction along the rail 82.

  The moving mechanism unit 80 includes a pair of rails 86 extending in the Y direction, and the slider 88 is slidably supported by the rails 86. The moving mechanism unit 80 also includes a driving unit (not shown) that moves the slider 88 along the rail 86 in the Y direction.

  The slider 88 includes a pair of rails 90 extending in the Z direction, and the slider 92 of the moving mechanism 54 is slidably supported by the rails 90. Further, the moving mechanism unit 54 includes a driving unit (not shown) for moving the slider 92 along the rail 90 in the Z direction.

[Principle of measurement method of depth of calf k]
FIG. 4 is a view for explaining the principle of the method of measuring the depth of the kerf k by the air micrometer 52. As shown in FIG.

  [Case 1] of FIG. 4 is an explanatory view for measuring the kerf k1 of the known depth L1 by the air micrometer 52, and [case 2] is an explanatory view for measuring the kerf k2 of the known depth L2.

  At this time, assuming that a flow passage cross-sectional area formed between the air micrometer 52 and the semiconductor wafer W is A1, and a flow passage cross-sectional area of the kerf k2 is A2, It can be calculated. The channel cross section is the sum of the term consisting of the gap H between the nozzle 66 and the semiconductor wafer W and the term consisting of the kerf k, and the area to which the kerf k contributes as a cross section is two places intersecting the nozzle inner diameter d .

A1 = d × Pi × H + 2 × W1 × L1 formula 1
A2 = d × Pi × H + 2 × W2 × L2 equation 2
Here, d is the inner diameter of the nozzle 66 and is a known value. Pi is the pi. H is a known value set in the gap measurement of a normal air micrometer 52. W1 and W2 are width dimensions of the kerfs k1 and k2, which are known values obtained by image processing for image processing of an image obtained by the camera 26 of the dicing apparatus 10.

According to Bernoulli's theorem, the pressure and height are constant in the amplifier 68, so
^{V1 2/2 = V2 2/} 2
V is the flow velocity.

Therefore, V1 = V2 ... Formula 3
From the law of continuity, the flow rate Q1 in [case1] and the flow rate Q2 in [case2] can be calculated by the following equations 4 and 5.

Flow rate Q1 = A1 x V1 ... Formula 4
Flow rate Q2 = A2 x V2 ... Formula 5
Here, the values obtained by dividing the flow rate by the cross-sectional area in [case1] and [case2] become equal, as in the following Equation 6, according to Equations 3, 4, and 5.

Q1 / A1 = Q2 / A2 equation 6
The air micrometer 52 can convert the flow rate into a kerf cross-sectional area by displacement, and has a function of observing the difference from the kerf serving as a gauge.

  In fact, by calibrating [case 1] and [case 2] as a material for which the kerf depths L1 and L2 have already been obtained, it is possible to experimentally obtain the relationship between the change in cross-sectional area and the change in flow rate. The minute components of the loss component and the kerf, and the R shape of the bottom are absorbed by the calibration of [case 1] and [case 2].

  By using the calibration value, it is possible to obtain the flow path cross-sectional area A3 ... of [Case 3] ... after the measurement target.

  That is, assuming [Case 3], the flow path cross-sectional area A3 of [Case 3] can be calculated based on the change of the flow rate.

At that time, d, H, and W3 are known values, respectively.
In the case of obtaining the kerf depth L3 of [Case 3],
The kerf depth L3 can be obtained by substituting the known values (A3, d, H, W3) into the equation A3 = d × Pi × H + 2 × W3 × L3.

  In other words, the second calculation unit 72 shown in FIG. 3 has the width W of the kerf k measured by the camera 26 and the image processing unit 74 and the cross-sectional area A of the kerf k calculated by the first calculation unit 70. Based on this, by dividing the cross-sectional area A by the width W, it is possible to calculate the depth of the kerf k which is not affected by the minute unevenness.

[Measurement method of depth of kerf k by air micrometer 52]
The measuring head 64 is attached to the moving mechanism 54, and while the compressed air is jetted from the nozzle 66 toward the surface of the semiconductor wafer W, the measuring heads 64 are relatively moved along the surface of the semiconductor wafer W by the moving mechanisms 78 and 80. Translate to parallel.

  In the plan view of the semiconductor wafer W shown in FIG. 5, a plurality of arrows A in the drawing indicate the relative movement direction of the measurement head 64 with respect to the surface of the semiconductor wafer W. That is, the measurement area on the surface of the semiconductor wafer W is divided in the X direction, and the measurement head 64 is moved in the Y direction (the same direction as the A direction) plural times for each divided measurement area. Measure the depth of

  The positioning of the measuring head 64 on the surface of the semiconductor wafer W can be performed by controlling the existing moving mechanism 54 of the dicing apparatus 10, and the depth measurement of the kerf k can be performed on the existing of the dicing apparatus 10. This can be implemented by moving the measuring head 64 by controlling the X, Y moving mechanism units 78, 80.

  The air micrometer 52 adjusts the pressure of the compressed air supplied from the pump 58 to a constant pressure by the regulator 60, and the pressure of the measuring head 64 is set via the throttle (not shown) installed inside the A / E converter 62. Compressed air is injected from the nozzle 66 onto the surface of the semiconductor wafer W.

  The A / E converter 62 converts minute changes in the flow rate (pressure) between the nozzle 66 and the throttle into an electrical signal by means of a built-in bellows and a differential transformer, and outputs the electrical signal to the amplifier 68. The amplifier 68 calculates a flow rate value based on the electrical signal, and the calculated flow rate is output to the first calculation unit 70. Then, the first calculation unit 70 calculates the cross-sectional area of the kerf k based on the flow rate. The calculated cross-sectional area of the kerf k is output to the second calculation unit 72.

  The width of the kerf k from the image processing unit 74 is output to the second operation unit 72. Then, the second operation unit 72 calculates the depth of the kerf k based on the width of the kerf k and the cross-sectional area of the kerf k.

  As described above, the kerf depth measuring apparatus 50 according to the embodiment can measure the depth of the kerf k based on the cross-sectional area of the kerf k which has little influence on the unevenness even when the minute unevenness is present on the side wall or the bottom of the kerf k. Because of this, it is possible to measure the depth of the kerf k with less error.

  FIG. 6 is an explanatory view showing that the air micrometer 52 is relatively moved in the arrow A direction in one measurement area of the semiconductor wafer W. As shown in FIG.

  FIG. 7 is a graph showing the air flow rate detected by the air micrometer 52 by a line B in the one measurement area shown in FIG. The horizontal axis in FIG. 7 indicates the position of the semiconductor wafer W in the arrow A direction, and the vertical axis indicates the air flow rate.

  According to FIG. 7, the air flow rate increases at positions a to j when passing through the kerfs A to J in FIG. 6 in the orthogonal direction, and the first calculation unit 70 in FIG. , The cross-sectional area of kerfs A to J at positions a to j is calculated. Then, the second arithmetic unit 72 calculates the depths of the kerfs A to J at the positions a to j as described above.

[Advantage of Providing the Calf Depth Measurement Device 50 to the Dicing Device 10]
The camera 26 and the image processing unit 74 of the dicing apparatus 10 are used as a width measuring unit that measures the width of the kerf k.

  Further, moving mechanisms 78, 80 for moving the table 18 and spindle 32 of the dicing apparatus 10 in the horizontal direction by supporting the measuring head 64 on the spindle 32 or the moving mechanism 54 on which the blade 28 of the dicing apparatus 10 is supported. It is used as a moving unit of the measuring head 64.

  Furthermore, in the dicing apparatus 10, the measurement head 64 of the air micrometer 52, the detection unit 56, and the first calculation unit 70 for measuring the thickness of the wafer W and setting the cut depth to the wafer W, The measurement head of the kerf depth measurement apparatus 50 is used as a first calculation unit.

  That is, since the air micrometer 52 for measuring the wafer thickness provided in the dicing apparatus 10 can be used as an apparatus for measuring the depth of the kerf k, the kerf depth measuring apparatus dedicated to the dicing apparatus 10 can be used. The depth of the kerf k of the semiconductor wafer W can be measured without setting 50.

  In the embodiment, the kerf depth measuring apparatus 50 for measuring the kerf depth of the semiconductor wafer W held on the table 18 of the dicing apparatus 10 has been described, but the present invention is not limited thereto. The present invention can be applied to any device that measures the depth of the kerf provided in the device.

  W: Semiconductor wafer, 10: Dicing device, 12: Load port, 14: Suction pad, 16: Transport device, 18: Table, 20: Processing unit, 22: Spinner, 24: Controller, 26: Camera, 28: Blade, 32: spindle, 34: adsorption unit, 50: calf depth measuring device, 52: air micrometer, 54: moving mechanism unit, 56: detection unit, 58: pump, 60: regulator, 62: A / E converter, 64: measuring head, 66: nozzle, 68: amplifier, 70: first arithmetic unit, 72: second arithmetic unit, 74: image processing unit, 76: monitor, 78, 80: moving mechanism unit, 82: rail, 84 ... Table support member, 86 ... rail, 88 ... slider, 90 ... rail, 92 ... slider

Claims (4)

A groove depth detection device for detecting the depth of a processed groove formed in a workpiece, comprising:
An injection nozzle for injecting a fluid from the position facing the groove forming surface of the workpiece toward the processing groove;
Detection means for detecting a change in flow rate or a change in pressure of the fluid;
Groove depth detection device comprising: In the groove depth detection device according to claim 1,
The computing device includes a computing unit that calculates the depth of the processing groove based on the detection result of the detection unit.
Groove depth detection device. A groove depth detection method for detecting the depth of a processed groove formed in a workpiece, comprising:
Injecting a fluid from the position facing the groove forming surface of the workpiece toward the processing groove;
Detecting the flow rate change or pressure change of the fluid;
A groove depth detection method comprising: In the groove depth detection method according to claim 3,
And a calculation step of calculating the depth of the processed groove based on the detection result of the detection step.
Groove depth detection method.

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