TWI729180B - Laminated wafer processing method - Google Patents

Abstract

[Problem] Divide the laminated wafer with the non-penetrating layer formed well. [Solution] A method for processing a laminated wafer in which a glass substrate is adhered to the front side of a silicon substrate, and the structure is formed as follows: from the back side of the silicon substrate formed with an impenetrable layer that is impermeable to infrared rays. The remaining area of the outer periphery of the formed element is cut to expose the silicon substrate, and the infrared camera is positioned above the silicon substrate exposed in the remaining area of the outer periphery, to detect the planned dividing line on the front side of the silicon substrate, and perform calibration. The first cutting blade for the silicon substrate cuts along the planned dividing line to divide the silicon substrate, and the second cutting blade for the glass substrate cuts along the groove dividing the silicon substrate to divide the glass substrate.

Description

Laminated wafer processing method Field of invention

The present invention relates to a method for processing a laminated wafer that divides the laminated wafer along a predetermined dividing line.

Background of the invention

In the past, as a laminated wafer, a laminated wafer in which a glass substrate is bonded to the front surface of a silicon substrate with a resin is well known, and the following proposal has been proposed: a method of cutting with an ultrasonic knife As a processing method of such a laminated wafer (see, for example, Patent Document 1). In the processing method described in Patent Document 1, a protective tape is attached to the back surface of a silicon substrate, and the protective tape side is held on the work clamp table with the glass substrate facing upward. Then, the imaging device penetrates the glass substrate to detect and align the predetermined dividing line on the front surface of the silicon substrate, and the ultrasonic knife cuts the glass substrate and the silicon substrate along the predetermined dividing line.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2007-081264

Summary of the invention

However, on the back side of the silicon substrate of the laminated wafer, there is also a substance on which a metal film or a pear skin surface is formed. Since the surface of the metal film or pear skin is an impenetrable layer that is difficult for infrared rays to pass through, it cannot be calibrated with an infrared camera with the silicon substrate facing upwards. It is necessary to cut the laminated wafer from the glass substrate side as in the processing method of Patent Document 1. . However, if a metal film is formed on the back surface of the silicon substrate, metal burrs will be generated. If the back surface of the silicon substrate is formed with a pear skin surface, chipping of the back surface will be worsened, so that the wafers formed after division become easy to produce defects. Bad condition.

The present invention is an invention made in view of the above points, and one of its objects is to provide a method for processing a laminated wafer that can divide a laminated wafer with an impermeable layer formed in a good manner.

In one aspect of the method for processing a laminated wafer of the present invention, the laminated wafer is a laminated wafer in which a glass substrate is adhered to the front side of a silicon substrate with resin, and the silicon substrate is formed on the front side of the silicon substrate with a plurality of An element divided by a plurality of predetermined dividing lines has an impermeable layer that is impermeable to infrared rays is formed on the back surface of the silicon substrate. The processing method of the laminated wafer includes the following steps: a placing step, the glass substrate The protective tape of the laminated wafer with the protective tape attached to the glass substrate side is placed on the upper surface of the work chuck table of the cutting device through the protective tape on the side of the glass substrate; the silicon substrate in the remaining area of the outer periphery is exposed, after the placing step is performed , The cutting tool of the cutting device will not be formed with the plural elements The non-penetrating layer in the remaining area of the periphery is cut and removed to expose the silicon substrate; the calibration step, after performing the step of exposing the silicon substrate in the remaining area of the periphery, position the infrared camera on the exposed silicon substrate in the remaining area of the periphery , And penetrate the silicon substrate to detect the planned dividing line on the front side for calibration; the first cutting step, after the calibration step is performed, the first cutting knife is cut from the silicon substrate side of the laminated wafer to In the resin, the silicon substrate is divided along the planned dividing line; and in the second cutting step, after the first cutting step is performed, the second cutting tool is moved along the groove cut in the first cutting step Cut into the protective tape, and divide the glass substrate along the planned dividing line.

According to this configuration, in the impermeable layer covering the back surface of the silicon substrate of the build-up wafer, the remaining area on the outer periphery where no element is formed is removed to partially expose the silicon substrate. By positioning the infrared camera on the exposed silicon substrate, the infrared rays penetrating the silicon substrate can detect the predetermined dividing line on the front side of the silicon substrate and perform calibration. In addition, since it is cut from the non-penetrating layer side of the back surface of the silicon substrate, it becomes difficult to form burrs, and it is difficult to generate cracks on the back surface. According to this, it is possible to well divide the laminated wafer in which the impermeable layer is formed along the planned dividing line.

According to the present invention, in the non-penetrating layer on the back of the silicon substrate, the remaining area on the outer periphery can be removed for alignment, and cut from the side of the non-penetrating layer on the back of the silicon substrate, thereby solving the problem caused by the non-penetrating layer. The poor condition of the layer and the good separation of the build-up wafer.

11: The front side of the silicon substrate

12: The back of the silicon substrate

13: Resin

14: No penetration layer

15: Metal film (non-penetrating layer)

16: Metal flash

17: Pear skin surface (not penetrating layer)

21: Stage

22: Bottom of the step

23: The groove of the silicon substrate

31: work clamp

32: Cutter

35: work clamp

36: Infrared camera

37: The first cutting tool for silicon substrates

38: The second cutter for glass substrates

39: Cutter

F: ring frame

T: Protective tape

D: Components

L: Pre-divided line

A1: component area

A2: The remaining area of the outer periphery

W: Laminated wafer

W1: Silicon substrate

W2: Glass substrate

FIG. 1 is an exploded perspective view of the laminated wafer of this embodiment.

2A and B are explanatory diagrams of a method of processing a laminated wafer of a comparative example.

Fig. 3 is a diagram showing an example of the placing procedure of the present embodiment.

Fig. 4 is a diagram showing an example of the step of exposing the silicon substrate in the outer peripheral surplus area of the present embodiment.

5A and B are diagrams showing an example of the calibration procedure of this embodiment.

Fig. 6 is a diagram showing an example of the first cutting step of the present embodiment.

Fig. 7 is a diagram showing an example of the second cutting step of the present embodiment.

The form used to implement the invention

Hereinafter, with reference to the attached drawings, the processing method of the laminated wafer of this embodiment will be described. First, a description will be given of a build-up wafer to be processed. FIG. 1 is an exploded perspective view of the laminated wafer of this embodiment. Fig. 2 is an explanatory diagram of a method of processing a laminated wafer of a comparative example.

As shown in FIG. 1, the laminated wafer W is formed by bonding a glass substrate W2 to the front surface 11 side of the silicon substrate W1 with a transparent resin 13 (refer to FIG. 3). On the front surface 11 of the silicon substrate W1, a plurality of planned dividing lines L are arranged in a grid pattern, and a plurality of elements D divided by the planned dividing line L are formed. The front surface 11 of the silicon substrate W1 is divided into an element area A1 where the element D is formed, and a peripheral remaining area A2 surrounding the element area A1 and where the element D is not formed. In addition, on the back surface 12 of the silicon substrate W1, an impermeable layer 14 such as a metal layer or a pear skin surface that is difficult to pass infrared rays is formed.

As shown in the comparative example of FIG. 2A, generally, the laminated wafer W constructed in this way is covered with the back surface 12 of the silicon substrate W1 with the impermeable layer 14, so it is along the planned dividing line L from the glass substrate W2 side. (Refer to Figure 1) for processing. In this method, with the glass substrate W2 side of the build-up wafer W facing upward, the silicon substrate W1 side of the build-up wafer W is attached to the protective tape T attached to the ring frame F . In addition, the cutting blade 39 for the glass substrate W2 performs ultrasonic vibration, so that the glass substrate W2 and the silicon substrate W1 can be ultrasonically cut along the planned dividing line L by the cutting blade 39.

However, since the laminated wafer W is down cut by the cutter 39, the impermeable layer 14 of the back surface 12 of the silicon substrate W1 is easily deteriorated. Therefore, although the cutting resistance of the silicon substrate W1 with respect to the cutting blade 39 can be reduced by ultrasonic cutting, the burrs or cracks of the impermeable layer 14 of the silicon substrate W1 cannot be suppressed. Instead of using ultrasonic cutting to process the glass substrate W2 and the silicon substrate W1 at one time, and the method of processing the glass substrate W2 and the silicon substrate W1 separately is also considered, but even if it is divided into two stages like this (step cut) still cannot prevent the deterioration of the non-penetrating layer 14.

For example, as shown on the left side of the diagram in FIG. 2B, when the metal film 15 is formed as the impermeable layer 14 on the back surface 12 of the silicon substrate W1, the metal film 15 of the silicon substrate W1 will be cut on the divided wafer. Produce metal burrs16. The metal burr 16 makes the wafer defective, and the metal burr 16 bites into the protective tape T so that the wafer cannot be peeled off. In addition, as shown on the right side of the diagram in FIG. 2B, pears are formed on the back surface 12 of the silicon substrate W1. When the skin surface 17 is used as the non-penetrating layer 14, the adhesion force of the pear skin surface 17 of the silicon substrate W1 and the protective tape T is reduced and the adhesion force becomes weak, and the back surface of the silicon substrate W1 is broken and deteriorated.

In addition, especially when the silicon substrate W1 is formed thinner (tens of μm), the back surface of the silicon substrate W1 is cracked and the cracks are elongated, resulting in breakage of the divided wafer. In this way, when the impermeable layer 14 is formed on the back surface 12 of the silicon substrate W1, when the laminated wafer W is cut from the glass substrate W2 side, the divided wafer is likely to become defective. On the other hand, when the laminated wafer W is turned upside down to cut from the side of the silicon substrate W1, the infrared camera's imaging is blocked by the opaque layer 14, so that the planned dividing line L cannot be detected and calibration cannot be performed. .

Therefore, in the method of processing the laminated wafer W of the present embodiment, in the impermeable layer 14 of the back surface 12 of the silicon substrate W1, the portion corresponding to the outer peripheral remaining area A2 is removed to form a calibrated (refer to the figure). 5), and cut along the planned dividing line L from the back surface 12 side of the silicon substrate W1 (refer to FIGS. 6 and 7). With this, it is possible to suppress the occurrence of burrs or cracks on the back surface, and it becomes possible to divide the build-up wafer W along the planned dividing line L satisfactorily. In addition, in the present embodiment, although the laminated wafer W on which the metal film 15 or the pear skin surface 17 has been formed as the impermeable layer 14 is processed, it is not limited to this structure. In the method of processing the laminated wafer W of the present embodiment, the non-penetrating layer 14 other than the metal film 15 or the surface 17 of the pear skin, that is, the back surface 12 of the silicon substrate W1 is formed with a non-penetrating layer that reduces the penetration of infrared rays. The laminated wafer W of the transparent layer 14 is also effective.

Hereinafter, with reference to FIGS. 3 to 7, the laminated wafer will be described in detail. The processing method. Respectively: FIG. 3 is a diagram showing an example of the placement step of this embodiment, FIG. 4 is a diagram showing an example of the step of exposing the silicon substrate in the outer peripheral area of this embodiment, and FIG. 5 is a diagram showing the calibration step of this embodiment. Fig. 6 is a diagram showing an example of the first cutting step in this embodiment, and Fig. 7 is a diagram showing an example of the second cutting step in this embodiment.

As shown in Fig. 3, the placing step can be implemented before the cutting device is operated. In the placing step, the laminated wafer W supported by the ring frame F is carried into a trimming device (not shown). For the laminated wafer W, the protective tape T attached to the ring frame F is attached to the glass substrate W2 of the laminated wafer W, and the glass substrate W2 is placed on the cutting device via the protective tape T. The upper surface of the work clamp table 31. At this time, the center of the layered wafer W is formed to coincide with the rotation axis of the work chuck table 31, and the layered wafer W is sucked and held on the work chuck table 31 via the protective tape T.

As shown in FIG. 4, after the placement step has been implemented, the step of exposing the silicon substrate in the remaining peripheral area can be implemented. In the step of exposing the silicon substrate in the outer peripheral residual area, the trimming cutter 32 is positioned to the outer peripheral residual area A2 where a plurality of elements D (refer to FIG. 1) are not formed, and the impermeable layer 14 is cut with the cutter 32. Next, by rotating the work chuck table 31 with respect to the cutting blade 32, the impenetrable layer 14 is removed from the outer peripheral remaining area A2 and the step 21 is formed along the outer periphery of the laminated wafer W. By partially removing the impermeable layer 14, the silicon substrate W1 is partially exposed.

In this case, it is desirable that the cutting blade 32 used for dressing is not blocked by the impermeable layer 14 such as a metal layer. A cutting blade that can make the surface roughness of the step portion 21 as smooth as possible. In addition, since the tip shape of the cutting blade 32 for dressing is flat, the step bottom surface 22 from which the impermeable layer 14 has been removed can be formed flat. In this way, the opaque layer 14 of the element area A1 is left from the back 12 side of the silicon substrate W1, and the opaque layer 14 of the peripheral remaining area A2 is removed by covering the entire circumference, and the infrared rays in the calibration step can be formed. The infrared transmission area of the camera 36 (refer to FIG. 5).

As shown in FIG. 5A, the calibration step can be performed after the step of exposing the silicon substrate in the remaining area of the outer periphery has been performed. In the calibration step, the laminated wafer W is transferred from the cutting device for trimming to the cutting device for dividing (not shown), and the glass substrate W2 is placed with the silicon substrate W1 side facing upward through the protective tape T. The side is held on the upper surface of the work clamp platform 35. The infrared camera 36 is positioned above the exposed silicon substrate W1 in the outer peripheral remaining area A2, and photographs the step portion 21 of the silicon substrate W1. At this time, infrared rays are irradiated from the infrared camera 36 toward the step portion 21 of the silicon substrate W1 to penetrate the silicon substrate W1 and the reflected light reflected on the front surface 11 is collected into the infrared camera 36 to generate a captured image.

As shown in FIG. 5B, since the planned dividing line L extends across the entire front surface of the silicon substrate W1, it is possible to photograph the planned dividing line L immediately below the step portion 21 where the impermeable layer 14 has been removed. At this time, since the bottom surface of the step portion 22 is formed flat and smooth, it is possible to penetrate the silicon substrate W1 to detect the side of the front surface 11 (see FIG. 5A) while the scattering of infrared rays on the bottom surface 22 of the step portion is suppressed. Split the planned line L. The calibration can be implemented as: based on the captured image of the planned dividing line L, the first cutting for the silicon substrate W1 The center position of the blade 37 in the width direction is positioned at the center position of the planned dividing line L in the width direction.

As shown in Figure 6, the first cutting step can be performed after the calibration step has been performed. In the first cutting step, the silicon substrate W1 on the upper stage of the laminated wafer W is divided by the first cutting blade 37 for the silicon substrate W1. As the first cutting blade 37, a blade suitable for silicon cutting can be selected. For example, an electroformed blade with a finer abrasive grain size can be used. When the first cutting blade 37 is positioned on the planned dividing line L (refer to FIG. 1) outside the radial direction of the laminated wafer W, the first cutting blade 37 can be lowered into the resin 13 that can be cut under the silicon substrate W1 The working chuck table 35 is cut and fed with respect to the first cutting blade 37.

Thereby, the first cutting blade 37 cuts into the resin 13 from the silicon substrate W1 side of the laminated wafer W, and the silicon substrate W1 can be divided along the planned dividing line L (see FIG. 5B). By repeatedly performing this cutting feed to cut the silicon substrate W1 along all the planned dividing lines L, lattice-shaped grooves 23 can be formed in the silicon substrate W1 on the upper stage of the laminated wafer W. In addition, since the first cutting blade 37 does not cut into the glass substrate W2 but only divides the silicon substrate W1, it becomes difficult to generate a grinding level on the first cutting blade 37, and it is possible to suppress the reduction in the cutting performance of the silicon substrate W1.

In addition, since the first cutting blade 37 cuts into the build-up wafer W from the side of the impermeable layer 14 undercutting, it is possible to suppress defects caused by cutting the impermeable layer 14. That is, even if the non-penetrating layer 14 is a metal film, the silicon substrate W1 directly below the non-penetrating layer 14 can still suppress the deformation of the metal film, making it difficult to produce metal burrs. Moreover, even if the non-penetrating layer 14 is the surface of the pear skin, since the surface of the pear skin is located on the upper surface of the laminated wafer W, Therefore, the crack will not be worsened like the surface of the pear skin is located on the lower surface of the laminated wafer W. In this way, even if the impermeable layer 14 is formed on the silicon substrate W1, it is possible to suppress the undesirable factors such as metal burrs and cracks.

As shown in Fig. 7, after the first cutting step has been performed, the second cutting step can be performed. In the second cutting step, the glass substrate W2 of the lower stage of the laminated wafer W is divided by the second cutting blade 38 for the glass substrate W2. As the second cutting blade 38, a blade suitable for glass cutting can be selected. For example, a resin blade with a coarser abrasive grain size and a narrower width than that of the first cutting blade 37 (refer to FIG. 6) can be used. ). When the second cutting blade 38 is positioned on the groove 23 on the silicon substrate W1 on the radially outer side of the laminated wafer W, the second cutting blade 38 can be lowered until it can be cut into the protective tape T under the glass substrate W2 The depth of the work chuck 35 relative to the second cutting knife 38 cutting feed.

Thereby, the laminated wafer W is cut into the protective tape T by the second cutter 38, and the glass substrate W2 can be divided along the groove 23 (the planned dividing line L) of the silicon substrate W1. By repeatedly performing this cutting feed to cut the glass substrate W2 along all the planned dividing lines L, the laminated wafer W can be divided into individual wafers. In addition, since the second cutting blade 38 is formed to have a narrower width than the first cutting blade 37, the second cutting blade 38 with a relatively coarse particle size does not damage the silicon substrate W1, and it becomes possible to achieve only The glass substrate W2 is cut well.

As described above, according to the method for processing the laminated wafer W of this embodiment, the opaque layer 14 on the back surface 12 of the silicon substrate W1 covering the laminated wafer W can be used to remove the peripheral remaining area A2 where the device D is not formed. Remove The silicon substrate W1 is partially exposed. The infrared camera 36 can be positioned on the exposed silicon substrate W1, and the infrared rays penetrating the silicon substrate W1 can detect the planned dividing line L on the front side 11 of the silicon substrate W1 and perform calibration. In addition, since it is cut from the side of the impermeable layer 14 of the back surface 12 of the silicon substrate W1, it becomes difficult to generate burrs and it is difficult to generate back surface cracks. According to this, the build-up wafer W on which the impermeable layer 14 is formed can be well divided along the planned dividing line L.

In addition, in the present embodiment, the configuration is as follows: a cutting device for trimming is used to perform the mounting step and a silicon substrate exposing step in the outer peripheral surplus area, and a cutting device for dividing is used to perform the calibration step and the second step. The first cutting step and the second cutting step are not limited to this configuration. It is also possible to perform all of the placing step, the silicon substrate exposing step of the outer peripheral surplus area, the calibration step, the first cutting step, and the second cutting step with the same cutting device.

In addition, although the present embodiment and modification examples have been described, as other embodiments of the present invention, the above-mentioned embodiment and modification examples may be combined in whole or in part.

In addition, the embodiments of the present invention are not limited to the above-mentioned embodiments and modifications, and various changes, substitutions, and modifications may be made within the scope not departing from the technical idea of the present invention. In addition, if the technical idea of the present invention can be realized in other ways through technological progress or other derived technologies, this method can also be used to implement it. Therefore, the scope of the patent request covers all embodiments that can be included in the scope of the technical idea of the present invention.

In addition, in this embodiment, although the structure of processing a laminated wafer formed by laminating a glass substrate on a silicon substrate is described, it can also be applied to solve the problem caused by the impermeable layer and A method for processing other build-up wafers that divide the build-up wafers well.

Industrial availability

As explained above, the present invention has the effect of being able to divide a laminated wafer with a non-penetrating layer formed well, especially for cutting a laminated wafer formed by attaching a glass substrate to a thin silicon substrate. The processing method of the laminated wafer is useful.

12‧‧‧The back of the silicon substrate

13‧‧‧Resin

14‧‧‧No penetration layer

23‧‧‧Silicon substrate groove

35‧‧‧Working Clamping Table

38‧‧‧Second cutter for glass substrate

W‧‧‧Laminated Wafer

W1‧‧‧Silicon substrate

W2‧‧‧Glass substrate

F‧‧‧Ring frame

T‧‧‧Protective tape

Claims (1)

A method for processing a laminated wafer. The laminated wafer is a laminated wafer in which a glass substrate is adhered to the front side of a silicon substrate with a resin. The silicon substrate is formed on the front side of the silicon substrate with a plurality of sections divided by a plurality of strips. The element divided by a predetermined line is formed on the back surface of the silicon substrate with a non-transmissive layer that is impenetrable to infrared rays. The processing method of this laminated wafer includes the following steps: a placing step, with the glass substrate side interposed therebetween The protective tape of the laminated wafer with the protective tape attached to the side of the glass substrate is placed on the upper surface of the work clamp table of the cutting device; The cutting blade cuts and removes the non-penetrating layer that is not formed with the remaining areas of the outer periphery of the plurality of components, so as to expose the silicon substrate; in the calibration step, after the step of exposing the remaining areas of the outer periphery of the silicon substrate, the infrared camera is positioned at The remaining area of the outer periphery is exposed on the silicon substrate, and the silicon substrate is penetrated to detect the dividing line on the front side for calibration; the first cutting step, after the calibration step is performed, remove the first cutting tool from The silicon substrate side of the layered wafer is cut into the resin, and the silicon substrate is divided along the planned dividing line; and a second cutting step, after the first cutting step is performed, along the first cutting The groove cut in the step cuts the second cutting blade into the protective tape, and divides the glass substrate along the planned dividing line.

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