JP6716403B2 - Laminated wafer processing method - Google Patents

Description

The present invention relates to a method for processing a laminated wafer in which the laminated wafer is divided along a dividing line.

Conventionally, as a laminated wafer, one in which a glass substrate is adhered to the surface of a silicon substrate with a resin is known, and a method of cutting with an ultrasonic blade has been proposed as a method of processing a laminated wafer of this type (for example, patents Reference 1). In the processing method described in Patent Document 1, a protective tape is attached to the back surface of the silicon substrate, and the protective tape side is held on the chuck table with the glass substrate facing upward. Then, the image division means transmits the glass substrate, detects a predetermined dividing line on the surface of the silicon substrate, aligns it, and cuts the glass substrate and the silicon substrate with an ultrasonic blade along the dividing line.

JP, 2007-081264, A

By the way, there is a laminated wafer in which a metal film, a matte surface or the like is formed on the back surface side of a silicon substrate. Since the metal film or the matte surface is an impermeable layer that does not easily transmit infrared rays, alignment using an infrared camera cannot be performed with the silicon substrate facing upward, and the laminated wafer is used as a glass substrate as in the processing method of Patent Document 1. Need to cut from the side. However, when a metal film is formed on the back surface of the silicon substrate, metal burrs are generated, and when a satin is formed on the back surface of the silicon substrate, back surface chipping is aggravated. There is a problem that it tends to occur.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for processing a laminated wafer capable of favorably dividing the laminated wafer having an opaque layer formed thereon.

A method for processing a laminated wafer according to one aspect of the present invention is a laminated wafer in which a glass substrate is bonded with a resin on the surface side of a silicon substrate on which a plurality of devices divided by a plurality of dividing lines are formed on the surface of the silicon substrate. In the processing method according to the above, an impermeable layer that does not easily transmit infrared rays is formed on the back surface of the silicon substrate, and the glass substrate side is provided with a protective tape on the glass substrate side through the protective tape. Is placed on the chuck table upper surface of the cutting device, and after carrying out the placing step, the impermeable layer in the peripheral excess area where the plurality of devices are not formed by the cutting blade of the cutting device. After performing the outer peripheral excess area silicon substrate exposing step of cutting and removing to expose the silicon substrate and the outer peripheral excess area silicon substrate exposing step, the infrared camera is positioned on the exposed silicon substrate of the outer peripheral redundant area to perform the silicon exposure. An alignment step of detecting a planned dividing line on the front surface side through the substrate to perform alignment, and after performing the alignment step, a first cutting blade from the silicon substrate side of the laminated wafer to the middle of the resin A first cutting step of cutting and dividing the silicon substrate along the dividing line; and a second cutting blade along the groove cut in the first cutting step after performing the first cutting step. A second cutting step of cutting the protective tape halfway and dividing the glass substrate along the dividing line.

According to this structure, in the impermeable layer that covers the back surface of the silicon substrate of the laminated wafer, the peripheral excess region where the device is not formed is removed, and the silicon substrate is partially exposed. By positioning the infrared camera on the exposed silicon substrate, the planned division line on the front surface side of the silicon substrate is detected by the infrared light transmitted through the silicon substrate, and alignment is performed. In addition, since the silicon substrate is cut from the back surface of the non-transmissive layer side, burrs are less likely to occur and back surface chipping is less likely to occur. Therefore, the laminated wafer on which the impermeable layer is formed can be favorably divided along the dividing line.

According to the present invention, by removing the outer peripheral surplus region of the impermeable layer on the back surface of the silicon substrate to enable alignment, and by cutting from the impermeable layer side of the back surface of the silicon substrate, the problem caused by the impermeable layer is eliminated. The laminated wafer can be satisfactorily divided while being solved.

It is an exploded perspective view of the laminated wafer of this embodiment. It is explanatory drawing of the processing method of the laminated wafer of a comparative example. It is a figure which shows an example of the mounting step of this Embodiment. It is a figure which shows an example of the outer periphery excess area|region silicon substrate exposure step of this Embodiment. It is a figure which shows an example of the alignment step of this Embodiment. It is a figure which shows an example of the 1st cutting step of this Embodiment. It is a figure which shows an example of the 2nd cutting step of this Embodiment.

Hereinafter, a method for processing a laminated wafer according to the present embodiment will be described with reference to the accompanying drawings. First, the laminated wafer to be processed will be described. FIG. 1 is an exploded perspective view of the laminated wafer of this embodiment. FIG. 2 is an explanatory diagram of a method for 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 a silicon substrate W1 with a transparent resin 13 (see 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 devices D partitioned by the planned dividing lines L are formed. The surface 11 of the silicon substrate W1 is divided into a device region A1 in which the device D is formed and an outer peripheral excess region A2 in which the device D is not formed around the device region A1. Further, on the back surface 12 of the silicon substrate W1, there is formed an opaque layer 14 such as a metal layer or a satin-finished surface, which makes it difficult for infrared rays to pass therethrough.

As shown in the comparative example of FIG. 2A, since the back surface 12 of the silicon substrate W1 is usually covered with the impermeable layer 14 in the laminated wafer W thus configured, the planned dividing line L from the glass substrate W2 side. (See FIG. 1). In this method, the silicon substrate W1 side of the laminated wafer W is attached to the protective tape T attached to the ring frame F with the glass substrate W2 side of the laminated wafer W facing upward. Further, the cutting blade 39 for the glass substrate W2 is ultrasonically vibrated, so that the glass substrate W2 and the silicon substrate W1 are ultrasonically cut together by the cutting blade 39 along the planned dividing line L.

By the way, since the laminated wafer W is down-cut by the cutting blade 39, the impermeable layer 14 on the back surface 12 of the silicon substrate W1 is easily deteriorated. For this reason, the cutting resistance of the silicon substrate W1 with respect to the cutting blade 39 is reduced by ultrasonic cutting, but burrs and chipping of the impermeable layer 14 of the silicon substrate W1 cannot be suppressed. It is possible to process the glass substrate W2 and the silicon substrate W1 individually instead of processing the glass substrate W2 and the silicon substrate W1 at a time by ultrasonic cutting, but this is a step cut divided into two stages. However, the deterioration of the impermeable layer 14 cannot be prevented.

For example, as shown on the left side of 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 is cut so that the divided chips are metalized. The burr 16 is generated. The chip becomes defective due to the metal burr 16 and the metal burr 16 bites into the protective tape T so that the chip cannot be peeled off. Further, as shown on the right side of FIG. 2B, when the matte surface 17 is formed as the impermeable layer 14 on the back surface 12 of the silicon substrate W1, the adhesion area of the matte surface 17 of the silicon substrate W1 and the protective tape T becomes. The adhesive force is reduced to weaken the adhesion, and the back surface chipping of the silicon substrate W1 is deteriorated.

Further, especially when the silicon substrate W1 is formed thin (several tens of μm), backside chipping occurs in the silicon substrate W1 and cracks extend and the chip after division is damaged. As described above, when the impermeable layer 14 is formed on the back surface 12 of the silicon substrate W1, cutting the laminated wafer W from the glass substrate W2 side tends to cause defective chips after division. On the other hand, when the laminated wafer W is turned upside down and it is attempted to cut from the silicon substrate W1 side, the imaging by the infrared camera is blocked by the opaque layer 14, so the planned dividing line L cannot be detected and alignment is performed. Can not do it.

Therefore, in the method for processing the laminated wafer W according to the present embodiment, the portion corresponding to the outer peripheral excess area A2 in the impermeable layer 14 on the back surface 12 of the silicon substrate W1 is removed to enable alignment (see FIG. 5). The silicon substrate W1 is cut along the planned dividing line L from the back surface 12 side (see FIGS. 6 and 7). As a result, it is possible to suppress the occurrence of burrs and backside chipping and to divide the laminated wafer W well along the dividing line L. In this embodiment, the laminated wafer W on which the metal film 15 and the matte surface 17 are formed as the impermeable layer 14 is processed, but the present invention is not limited to this structure. In the method for processing the laminated wafer W according to the present embodiment, the non-transmissive layer 14 other than the metal film 15 and the satin-finished surface 17, that is, the non-transmissive layer 14 that reduces the amount of infrared rays transmitted through the back surface 12 of the silicon substrate W1 is formed. It is also effective for the laminated wafer W.

Hereinafter, a method for processing a laminated wafer will be described in detail with reference to FIGS. 3 to 7. 3 is a placing step of the present embodiment, FIG. 4 is a step of exposing a peripheral surplus region silicon substrate of the present embodiment, FIG. 5 is an alignment step of the present embodiment, and FIG. 6 is a first cutting of the present embodiment. FIG. 7 is a diagram showing an example of each of the second cutting steps of the present embodiment.

As shown in FIG. 3, the mounting step is performed before the cutting device is operated. In the mounting step, the laminated wafer W supported by the ring frame F is carried into a cutting device (not shown) for trimming. In the laminated wafer W, the protective tape T adhered to the ring frame F is adhered to the glass substrate W2 of the laminated wafer W, and the glass substrate W2 side is placed on the chuck table 31 of the cutting device through the protective tape T. To be done. At this time, the laminated wafer W is suction-held on the chuck table 31 via the protective tape T such that the center of the laminated wafer W coincides with the rotation axis of the chuck table 31.

As shown in FIG. 4, after the placing step is performed, the outer peripheral excess region silicon substrate exposing step is performed. In the outer peripheral excess region silicon substrate exposing step, the cutting blade 32 for trimming is positioned in the outer peripheral excess region A2 where the plurality of devices D (see FIG. 1) are not formed, and the impermeable layer 14 is cut by the cutting blade 32. .. Then, by rotating the chuck table 31 with respect to the cutting blade 32, the impermeable layer 14 is removed from the outer peripheral excess area A2, and the step portion 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, as the cutting blade 32 for trimming, it is preferable that the cutting blade 32 does not become clogged with the impermeable layer 14 such as a metal layer and the surface roughness of the step portion 21 can be made as smooth as possible. Further, since the cutting blade 32 for trimming has a flat tip shape, the stepped portion bottom surface 22 from which the impermeable layer 14 is removed is formed flat. In this manner, the opaque layer 14 in the device area A1 is left from the back surface 12 side of the silicon substrate W1 and the opaque layer 14 in the outer peripheral excess area A2 is removed over the entire circumference, so that the infrared camera 36 (in the alignment step) ( An infrared transmitting region is formed by (see FIG. 5).

As shown in FIG. 5A, the alignment step is performed after the peripheral excess area silicon substrate exposing step is performed. In the alignment step, the laminated wafer W is loaded from the cutting device for trimming to the cutting device for division (not shown), and the glass substrate W2 side is chucked via the protective tape T with the silicon substrate W1 side facing upward. It is held on the upper surface of the table 35. The infrared camera 36 is positioned above the exposed silicon substrate W1 in the peripheral excess area A2, and the stepped portion 21 of the silicon substrate W1 is imaged. At this time, infrared rays are emitted from the infrared camera 36 toward the stepped portion 21 of the silicon substrate W1, and the reflected light that has passed through the silicon substrate W1 and reflected by the surface 11 is captured by the infrared camera 36 to generate a captured image. It

As shown in FIG. 5B, since the planned division line L extends across the entire surface of the silicon substrate W1, the planned division line L directly below the step portion 21 from which the opaque layer 14 is removed is imaged. It At this time, since the bottom surface 22 of the step portion is formed flat and smooth, the silicon substrate W1 is transmitted while the infrared ray scattering on the bottom surface 22 of the step portion is suppressed, and the surface 11 (see FIG. 5A) side is divided. The scheduled line L is detected. Based on the captured image of the planned division line L, the alignment is performed so that the center position of the first cutting blade 37 for the silicon substrate W1 in the width direction is located at the center position of the planned division line L in the width direction.

As shown in FIG. 6, the first cutting step is performed after the alignment step is performed. In the first cutting step, the upper silicon substrate W1 of the laminated wafer W is divided by the first cutting blade 37 for the silicon substrate W1. A blade suitable for silicon cutting is selected as the first cutting blade 37, and for example, an electroformed blade having fine abrasive grains is used. When the first cutting blade 37 is positioned on the planned dividing line L (see FIG. 1) on the outer side of the laminated wafer W in the radial direction, the first cutting blade 37 has a depth at which the resin 13 below the silicon substrate W1 can be cut into the middle thereof. 37 is lowered and the chuck table 35 is cut and fed to the first cutting blade 37.

As a result, the first cutting blade 37 cuts the laminated wafer W from the silicon substrate W1 side to the middle of the resin 13, and divides the silicon substrate W1 along the division line L (see FIG. 5B). By repeating this cutting feed, the silicon substrate W1 is cut along all the planned dividing lines L, and the lattice-shaped grooves 23 are formed in the upper silicon substrate W1 of the laminated wafer W. Further, since the first cutting blade 37 divides only the silicon substrate W1 without cutting the glass substrate W2, the first cutting blade 37 is less likely to be crushed and the deterioration of the cutting performance for the silicon substrate W1 is suppressed. ing.

Further, since the laminated wafer W is cut by the first cutting blade 37 from the opaque layer 14 side by down-cutting, it is possible to suppress a defect caused by cutting the opaque layer 14. That is, even if the opaque layer 14 is a metal film, the deformation of the metal film is suppressed by the silicon substrate W1 directly below the opaque layer 14, and a metal burr is less likely to occur. Even if the impermeable layer 14 is a matte surface, since the matte surface is located on the upper surface of the laminated wafer W, chipping may be worse as in the case where the matte surface is located on the lower surface of the laminated wafer W. Absent. Thus, even if the impermeable layer 14 is formed on the silicon substrate W1, the cause of defects such as metal burr and chipping can be suppressed.

As shown in FIG. 7, the second cutting step is performed after the first cutting step is performed. In the second cutting step, the lower glass substrate W2 of the laminated wafer W is divided by the second cutting blade 38 for the glass substrate W2. A blade suitable for glass cutting is selected as the second cutting blade 38, and, for example, a resin blade having a smaller abrasive grain size and a narrower width than the first cutting blade 37 (see FIG. 6) is used. .. When the second cutting blade 38 is positioned in the groove 23 on the silicon substrate W1 on the outer side in the radial direction of the laminated wafer W, the second cutting blade 38 is cut to a depth at which the protective tape T below the glass substrate W2 can be cut halfway. The chuck table 35 is lowered and the chuck table 35 is cut and fed to the second cutting blade 38.

As a result, the laminated wafer W is cut in the middle of the protective tape T by the second cutting blade 38, and the glass substrate W2 is divided along the groove 23 (planned division line L) of the silicon substrate W1. By repeating this cutting feed, the glass substrate W2 is cut along all the division lines L, and the laminated wafer W is divided into individual chips. Further, since the second cutting blade 38 is formed narrower than the first cutting blade 37, only the glass substrate W2 is satisfactorily cut without damaging the silicon substrate W1 with the second cutting blade 38 having a coarse grain size. It is possible.

As described above, according to the method for processing the laminated wafer W of the present embodiment, the outer peripheral area A2 in which the device D is not formed in the impermeable layer 14 that covers the back surface 12 of the silicon substrate W1 of the laminated wafer W. Are removed to partially expose the silicon substrate W1. By positioning the infrared camera 36 on the exposed silicon substrate W1, the planned dividing line L on the front surface 11 side of the silicon substrate W1 is detected by the infrared rays transmitted through the silicon substrate W1 and alignment is performed. Further, since the back surface 12 of the silicon substrate W1 is cut from the impermeable layer 14 side, burrs are less likely to occur and back surface chipping is less likely to occur. Therefore, the laminated wafer W on which the impermeable layer 14 is formed can be favorably divided along the division line L.

In this embodiment, the placing step and the outer peripheral surplus region silicon substrate exposing step are performed by the cutting device for trimming, and the alignment step, the first cutting step, and the second cutting step are performed by the cutting device for dividing. However, the configuration is not limited to this. The placing step, the outer peripheral surplus region silicon substrate exposing step, the alignment step, the first cutting step, and the second cutting step may all be performed by the same cutting device.

Further, although the present embodiment and the modified examples have been described, as another embodiment of the present invention, the above-described embodiments and modified examples may be combined wholly or partially.

The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, replaced, or modified without departing from the spirit of the technical idea of the present invention. Further, if the technical idea of the present invention can be realized in another way by the advancement of the technology or another derivative technology, the method may be implemented. Therefore, the claims cover all embodiments that can be included in the scope of the technical idea of the present invention.

Further, in the present embodiment, the configuration for processing the laminated wafer in which the glass substrate is laminated on the silicon substrate has been described, but the laminated wafer can be satisfactorily divided while eliminating the problem caused by the opaque layer. It can also be applied to a method of processing a laminated wafer.

As described above, the present invention has an effect that a laminated wafer on which an impermeable layer is formed can be favorably divided, and in particular, a laminated wafer in which a glass substrate is attached to a thin silicon substrate is used. It is useful as a method for processing a laminated wafer to be cut.

11 Surface of Silicon Substrate 12 Back of Silicon Substrate 13 Resin 14 Impermeable Layer 15 Metal Film (Impermeable Layer)
17 Pear ground (impermeable layer)
23 Groove of Silicon Substrate 32 Cutting Blade for Trimming 36 Infrared Camera 37 First Cutting Blade for Silicon Substrate 38 Second Cutting Blade for Glass Substrate A1 Device Area A2 Peripheral Excess Area D Device L Planned Line T Protective Tape W Laminate Wafer W1 Silicon substrate W2 Glass substrate

Claims (1)

A method of processing a laminated wafer in which a glass substrate is adhered to a surface of a silicon substrate on which a plurality of devices divided by a plurality of planned dividing lines are formed on the surface of the silicon substrate,
An impermeable layer that is hard to transmit infrared rays is formed on the back surface of the silicon substrate,
A placing step of placing the glass substrate side on the chuck table upper surface of the cutting device through the protective tape of the laminated wafer having the protective tape adhered to the glass substrate side;
After performing the mounting step, the cutting blade of the cutting device cuts and removes the impermeable layer in the peripheral excess region where the plurality of devices are not formed to expose the silicon substrate to expose the silicon substrate. Steps,
After performing the outer peripheral excess area silicon substrate exposing step, an infrared camera is positioned on the exposed silicon substrate of the outer peripheral excess area, the infrared rays are transmitted through the silicon substrate, and the planned dividing line on the front surface side is detected to perform alignment. An alignment step,
After performing the alignment step, a first cutting step in which a first cutting blade is cut from the silicon substrate side of the laminated wafer to the middle of the resin, and the silicon substrate is divided along the dividing line,
After performing the first cutting step, cut a second cutting blade halfway along the protective tape along the groove cut in the first cutting step, and divide the glass substrate along the dividing line. 2 cutting steps,
And a method for processing a laminated wafer.

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