JP7103269B2 - Terrace processing method for bonded wafers - Google Patents

Description

The present invention relates to a method for terrace processing of laminated wafers.

As semiconductor wafers, silicon wafers made of single crystal silicon and bulk wafers made of compound semiconductors such as GaAs (hereinafter, may be referred to as "bulk wafers") are known. Further, there is known a bonded wafer in which a bulk wafer is used as a support substrate wafer, an insulating film is provided on the surface thereof, and the support substrate wafer is bonded to the active layer wafer via the insulating film. It is common to form an active layer by further thinning the active layer wafer of the bonded wafer and use the active layer as a semiconductor device forming region. As the active layer wafer, a wafer of the same type as the bulk wafer may be used, or a different type of wafer may be used.

Particularly in recent years, in the field of highly integrated CMOS elements, high withstand voltage elements, and image sensors, SOI wafers having an SOI (Silicon on Insulator) structure have been attracting attention. This SOI wafer has a structure in which an insulating film such as silicon oxide (SiO ₂ ) and a semiconductor layer such as a single crystal silicon layer used as a device active layer are sequentially formed on a wafer for a support substrate. Although the parasitic capacitance that can be generated between the element and the substrate is relatively large in the bulk silicon substrate, the parasitic capacitance can be significantly reduced in the SOI wafer, so that the device speed, withstand voltage, and power consumption can be reduced. It is advantageous in that.

By the way, in a laminated wafer such as an SOI wafer, a region called a "terrace" is generally formed on the outer peripheral side of the active layer for various purposes such as prevention of chipping. In addition, the portion provided with the terrace may be used for wafer handling in a device forming process for manufacturing a semiconductor device on a bonded wafer.

As an example, the terrace _TA of the bonded wafer 100 is shown in FIG. The bonded wafer 100 has an insulating film 30 such as silicon oxide (SiO ₂ ) and an active layer 21 on the support substrate wafer 10. The active layer 21 is obtained by bonding the support substrate wafer 10 and the active layer wafer to each other via an insulating film 30, and then grinding and polishing the active layer wafer to make it thinner. _A terrace TA is formed on the outer peripheral side of the active layer 21.

_A general method for forming a terrace TA on a laminated wafer such as an SOI wafer will be described with reference to the schematic diagram of FIG. As shown in FIG. 2, the active layer wafer 20 and the chamfer wheel 200 provided with the grinding wheel 210 are rotated in opposite directions to each other, and the bonded wafer 100 is pushed up against the chamfer wheel 200 while the active layer wafer 20 is pushed up. The peripheral edge of the active layer wafer 20 is scraped off by rotating contact with the peripheral edge of the wafer 20. While the chamfer wheel 200 is rotated at high speed, the active layer wafer 20 in the bonded state is usually rotated at low speed. Then, the peripheral portion of the active layer wafer 20 is ground to a desired thickness, and the processing is completed with the unremoved portion left on the insulating film 30 to obtain the terrace processed portion _TB . Then, the terrace _TA shown in FIG. 1 can be formed by finally removing the terrace processed portion _TB which is an unremoved portion on the insulating film 30 by etching which is a post-process. Hereinafter, in the present specification, the processing of the peripheral portion of the wafer until the terrace processing portion _TB is obtained, which corresponds to the processing before obtaining the final terrace by etching, is referred to as “terrace processing”.

For example, Patent Document 1 discloses a terrace chamfering device for use in terrace processing of bonded wafers. The terrace chamfering device described in Patent Document 1 includes a vibrating flange fitted and fixed to the spindle of a grinding unit, a piezoelectric element built in the vibrating flange and ultrasonically vibrates in the Z direction, and a grinding grindstone on the lower surface of the outer periphery. Is provided, and a chamfering wheel fitted to the vibrating flange is provided, and a terraced portion is formed on the member to be processed by cutting in the Z direction while applying ultrasonic vibration by the piezoelectric element to the grinding grindstone. .. The wafer feed unit of this terrace chamfering device can move horizontally in each of the X-axis and Y-axis directions and vertically in the Z-axis direction, and further, a member to be machined around the spindle of the wafer feed unit. To rotate. Further, the grinding unit of this terrace chamfering device can also move vertically in the Z-axis direction, and the chamfering wheel is rotated around the spindle. A terrace chamfering device that only rotates the chamfering wheel without moving the grinding unit vertically in the Z-axis direction is also known.

By the way, the semiconductor wafer is provided with a notch or an orientation flat (hereinafter, may be abbreviated as "orifra") for indicating a crystal orientation. As disclosed in Patent Document 2, in the wafer for the active layer in the laminated wafer, the circumferential partial terrace processing and the orientation flat partial terrace processing are performed separately and independently. In addition, since the circumferential partial terrace processing and the olifra partial terrace processing are performed separately, in order to increase the productivity of the olifra partial terrace processing, the conventional technique finishes the olifra partial terrace processing with one scanning (1 pass processing). ..

JP-A-2017-170541 Japanese Unexamined Patent Publication No. 2004-235251

As disclosed in Patent Document 2, in the prior art, after the circumferential partial terrace processing is performed, the orientation flat portion is terraced (hereinafter, may be abbreviated as "orifra partial terrace processing"). It was common. Therefore, a large load is applied between the active layer wafer and the chamfering wheel grinding wheel at the time of cutting the blade at the start of the orifra partial terrace processing (that is, the moment when the contact between the grinding wheel and the active layer wafer starts). Stress (machining damage) will occur. When such load stress is generated, the wafer portion that should not be processed and removed may be forcibly peeled off. In such a case, in the etching process of the terrace processing portion performed after the terrace processing, it may cause pits and spider defects due to surface irregularities.

Therefore, in view of the above problems, it is an object of the present invention to provide a method for terrace processing of laminated wafers capable of reducing the load stress generated during terrace processing of an orientation flat portion.

The present inventors have diligently studied to solve the above problems. The maximum load stress is generated at the moment when the grinding wheel and the wafer for the active layer start to come into contact with each other during the orifra partial terrace processing. Therefore, the present inventors have found that the above problems can be solved by continuously performing the circumferential partial terrace processing and the orientation flat partial terrace processing without stopping the rotational operation of the bonded wafer, and complete the present invention. It came to. That is, the gist structure of the present invention is as follows.

(1) The peripheral portion of the active layer wafer in the bonded wafer in which the support substrate wafer and the active layer wafer are bonded via an insulating film is terraced by using a chamfering wheel provided with a grinding wheel. It is a terrace processing method for laminated wafers.
The first step of starting the rotation of each of the bonded wafer and the chamfered wheel, and
The second step of pressing the grinding wheel and the bonding wafer in the thickness direction of the bonded wafer while rotating the active layer wafer against the grinding wheel of the chamfer wheel is included.
In the second step, while maintaining the rotational contact between the active layer wafer and the grinding wheel, the circumferential portion terrace processing of the active layer wafer and the terrace processing of the orientation flat portion of the active layer wafer are continuously performed. A method for terrace processing of laminated wafers, which is characterized by the fact that it is performed in a specific manner.

(2) In the second step, the distance between the chamfered wheel and the bonded wafer is controlled according to the shape of the orientation flat portion of the active layer wafer while maintaining the rotational contact state. The terrace processing method for bonded wafers according to (1).

(3) (i) The rotation from the start point at which the contact of the orientation flat portion starts to the center point of the orientation flat portion imparts a velocity component in which the bonded wafer is relatively close to the chamfer wheel. Approach process and
(Ii) In the rotation from the center point of the orientation flat portion to the end point at which the contact with the bonded wafer ends, a separation step of imparting a velocity component in the direction opposite to the velocity component to the bonded wafer is provided. ,
The method for terrace processing of a bonded wafer according to (2) above, wherein the follow-up control of the second step is performed.

(4) The method for terrace processing of a bonded wafer according to any one of (1) to (3) above, wherein the bonded wafer is rotated for two or more turns.

(5) The method for terrace processing of a bonded wafer according to any one of (1) to (4) above, wherein both the support substrate wafer and the active layer wafer are silicon wafers.

According to the present invention, it is possible to provide a method for terrace processing of a laminated wafer, which can reduce the load stress generated during terrace processing of an orientation flat portion.

It is a schematic cross-sectional view which shows an example of the laminated wafer by the prior art. It is a schematic cross-sectional view which shows the terrace processing to the bonded wafer by the prior art. It is a front view of the terrace chamfering apparatus applicable to one Embodiment of this invention. It is a top view of the terrace chamfering apparatus applicable to one Embodiment of this invention. It is a schematic diagram explaining the continuous operation of the circumferential partial terrace processing and the orientation flat partial terrace processing in one embodiment of the present invention. It is a graph which shows an example of the change of the velocity component in the Y direction of the bonded wafer in one Embodiment of this invention. It is a photograph of the vicinity of the orientation flat part after the terrace processing in the example. It is a photograph of the vicinity of the orientation flat part after performing alkaline etching in the example. It is a photograph of the vicinity of the orientation flat part after terrace processing in the conventional example. It is a photograph of the vicinity of the orientation flat part after performing alkaline etching in the conventional example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The configuration in the schematic diagram is exaggerated unlike the actual aspect ratio. First, the terrace chamfering device 500, which is an example of the terrace chamfering device applicable to one embodiment of the present invention, will be described with reference to FIGS. 3A and 3B.

The terrace chamfering device 500 includes a wafer feed unit 500A and a grinding unit 500B. The wafer feed unit 500A can slidably support the bonded wafer 100 mounted on the table 310 in the X, Y, and Z directions by the drive unit 320, and rotates the θ _A axis parallel to the Z axis. It is rotatable as an axis. As the table 310, a vacuum suction table or the like can be used. Further, the grinding unit 500B can be rotated by the drive unit 220 about the θ _B axis parallel to the Z axis as a rotation axis, and the chamfer wheel 200 includes a grinding wheel 210. After aligning the positions of the bonded wafer 100 in the X, Y, and Z directions, the bonded wafer 100 and the chamfering wheel 200 are rotated in opposite directions around each rotation axis to transfer the bonded wafer 100 to the grinding wheel 210. Make contact. An embodiment in which the circumferential partial terrace processing and the orientation flat partial terrace processing are continuously performed on the bonded wafer 100 by the terrace chamfering device 500 will be described. The grinding unit 500B may rotate the chamfer wheel 200 while slidably supporting the chamfer wheel 200 in the Z-axis direction by the drive unit 220 and pushing down the grinding wheel 210 in the Z-axis direction. Further, the bonded wafer 100 and the chamfered wheel 200 may have the same rotation direction. For the reference numerals of the bonded wafer 100, also refer to FIG. 2 described above.

(Terrace processing method for bonded wafers)
In the method of terrace processing of the bonded wafer 100 according to the embodiment of the present invention, the peripheral portion of the active layer wafer 20 in the bonded wafer 100 is terraced using a chamfering wheel 200 provided with a grinding wheel 210. This is a terrace processing method. Here, the bonded wafer 100 is formed by bonding the support substrate wafer 10 and the active layer wafer 20 via the insulating film 30 (see FIG. 2). Then, in the terrace processing method of the bonded wafer 100 according to the present invention, the first step of starting the rotation of the bonded wafer 100 and the chamfering wheel 200, and the rotation of the active layer wafer 20 on the grinding wheel 210 of the chamfering wheel 200. It includes a second step of pressing the grinding wheel 210 and the bonded wafer 100 in the thickness direction of the bonded wafer 100 while making contact with each other. Then, in the second step, while maintaining the rotational contact between the active layer wafer 20 and the grinding wheel 210, the circumferential portion terrace processing of the active layer wafer 20 and the terrace processing of the orientation flat portion on the active layer wafer 20 are performed. (Hereinafter, "orifura partial terrace processing") is continuously performed. Hereinafter, details of each step will be described in sequence.

<First step>
First, in the first step, the rotation of each of the bonded wafer 100 and the chamfered wheel 200 is started. This step can be performed using a general terrace chamfering device 500. Generally, the rotation speed of the bonded wafer 100 is a low speed rotation of about 0.1 to 1.0 rpm, and the rotation speed of the chamfer wheel 200 is a high speed rotation of about 3000 to 6000 rpm.

<Second step>
Subsequently, the active layer wafer 20 is rotationally contacted with the grinding wheel 210 of the chamfering wheel 200, and the grinding wheel 210 and the bonding wafer 100 press against each other in the thickness direction of the bonded wafer 100. For example, the grinding unit 500B only rotates the chamfer wheel 200 while fixing the position of the chamfer wheel 200 in the Z-axis direction. On the other hand, the wafer feed unit 500A pushes up the bonded wafer 100 in the Z-axis direction. In the example of FIG. 2 described above, the laminated wafer 100 is pushed up upward in the Z-axis direction. Here, while maintaining the rotational contact between the active layer wafer 20 and the grinding wheel 210, the circumferential portion terrace processing of the active layer wafer 20 and the orientation flat portion terrace processing of the active layer wafer 20 are continuously performed.

With reference to FIG. 4, an example of the operation when the circumferential partial terrace processing and the orientation flat partial terrace processing in this step are continuously performed will be described. FIG. 4 schematically shows a top view of the active layer wafer 20 (bonded wafer 100) rotating counterclockwise. The active layer wafer 20 shown by the alternate long and short dash line in the figure shows the rotational position of the active layer wafer 20 when the circumferential portion terrace processing is performed. Further, the active layer wafer 20 shown by the solid line in the drawing shows the rotation position of the active layer wafer 20 when the orifra partial terrace processing is performed.

The position where the orientation flat portion OF formed on the active layer wafer 20 starts contact with the grinding wheel 210 is referred to as position A, the position where the contact ends is referred to as position B, and the center point between position A and position B is referred to as position C. .. FIG. 5 shows a conceptual graph of the velocity component in the Y direction applied to the active layer wafer 20.

See FIGS. 4 and 5. First, when the active layer wafer 20 is subjected to circumferential terrace processing (that is, when the active layer wafer 20 and the grinding wheel 210 come into contact with each other at a circumferential portion other than the orientation flat portion OF), the active layer wafer 20 is activated. Only the layer wafer 20 needs to be rotated. At this time, the velocity component in the Y direction is 0 (see FIG. 5). When the rotation of the active layer wafer 20 is continued for the circumferential portion terrace processing, the active layer wafer 20 and the grinding wheel 210 start to come into contact with each other at the position A of the orientation flat portion OF. At this time, a velocity component in the + Y direction is imparted to the active layer wafer 20 (that is, the entire bonded wafer), and the active layer wafer 20 is started to be brought closer to the chamfer wheel 200 to change from the circumferential partial terrace processing to the orifura partial terrace processing. Switch continuously. Then, when the active layer wafer 20 comes into contact with the grinding wheel 210 at the position C of the orientation flat portion OF, the active layer wafer 20 is brought closest to the chamfer wheel 200. After that, a velocity component in the −Y direction is imparted to the active layer wafer 20 (that is, the entire bonded wafer) until the active layer wafer 20 comes into contact with the grinding wheel 210 at the position B of the orientation flat portion OF, and the active layer wafer 20 is used. The wafer 20 is moved away from the chamfer wheel 200, and when the position B is reached, the wafer 20 is continuously switched from the orifra partial terrace processing to the circumferential partial terrace processing.

Focusing on the velocity in the Y direction, as shown in FIG. 5, the approach starts at the velocity V ₀ in the Y direction (position A), and while decelerating the velocity in the Y direction, the position C of the orientation flat portion OF is in the Y direction. The direction of movement speed begins to reverse. Subsequently, the velocity component is gradually added in the -Y direction, the velocity in the -Y direction is increased to the position B, and when the position B is reached, the velocity component in the Y direction is given and the circumferential partial terrace processing is restarted. .. Such approaching from position A to position C and separation from position C to position B are performed while maintaining rotational contact between the active layer wafer 20 and the grinding wheel 210.

After that, the active layer wafer 20 is continuously rotated, and the circumferential portion terrace processing of the active layer wafer 20 is performed. When the active layer wafer 20 begins to come into contact with the grinding wheel 210 at the position A of the orientation flat portion OF while continuing to rotate due to the circumferential portion terrace processing, the active layer wafer 20 is again imparted with a velocity component in the Y direction and chamfered. The wheel 200 is approached and separated from the wheel 200.

As in this example, in the second step, the distance between the chamfered wheel 200 and the bonded wafer 100 is tracked and controlled along the shape of the orientation flat portion OF of the active layer wafer 20. By doing so, it is possible to continuously perform the circumferential partial terrace processing on the peripheral portion of the active layer wafer 20 and the orientation flat partial terrace processing on the active layer wafer 20. The follow-up control by rotational scanning of the active layer wafer 20 and movement control in the Y direction can be performed by NC control of the wafer feed unit 500A or the like.

As described above, in the prior art, after the circumferential partial terrace processing is performed, the orientation flat partial terrace processing is separately performed. Therefore, the load stress was concentrated at the end point of the olifra portion OF during the terrace processing of the olifra portion. On the other hand, in the method of the present invention, since the olifra portion terrace processing is performed following the circumferential portion terrace processing, the load stress at the moment when the olifra portion OF first contacts the grinding wheel 210 at the position A can be significantly reduced. It will be possible.

As described above, in the rotation from (i) the start point (position A) at which the contact of the orientation flat portion OF starts to the center point (position C) of the orientation flat portion OF, the bonded wafer 100 is attached to the chamfering wheel 200. In the approaching step of imparting a relatively approaching velocity component and (ii) rotation from the center point (position C) of the orientation flat portion OF to the end point (position B ) where the contact with the bonded wafer 100 ends. It is preferable to perform the follow-up control of the second step by the separation step of imparting the velocity component in the direction opposite to the velocity component to the bonded wafer 100. In this way, in the terrace processing method according to the method of the present invention, it is possible to reliably perform the circumferential partial terrace processing and the orientation flat partial terrace processing. The following operation described with reference to FIGS. 4 and 5 is only a specific embodiment. Even if a velocity component is applied in the X direction in addition to the Y direction, it is possible to continuously perform the circumferential partial terrace processing and the orientation flat partial terrace processing. It is also preferable to finely adjust the velocity components in the X direction and the Y direction according to the contact state between the active layer wafer 20 and the grinding wheel 210 in the orientation flat portion OF while performing these approaching step and separating step.

In the prior art, it was common to finish the olifra partial terrace processing in one scan, but in the method of the present invention, the olifra partial terrace processing is continuously performed with the circumferential partial terrace processing, so that the laminated wafer is used. It is preferable to rotate the above two or more turns. By rotating the ground portion by two or more turns, the load stress in the vicinity of the ground portion can be reduced, and as a result, the machining strain can be reduced.

As described above, according to the method of the present invention, it is possible to provide a terrace processing method for laminated wafers capable of reducing the load stress generated during the terrace processing of the orientation flat portion. Further, in the method of the present invention, since it is not necessary to separately perform the circumferential partial terrace processing and the orientation flat partial terrace processing, it is also advantageous in that the productivity of the bonded wafer can be increased.

Although the mode of pushing up the bonded wafer with respect to the grinding wheel 210 has been described with reference to FIGS. 3A and 3B, the pressing direction may be arbitrary or opposite.

Further, although the mode in which the bonded wafer 100 is operated in the X direction and the Y direction by the wafer feed unit 500A shown in FIGS. 3A and 3B has been described so far, the grinding wheel by the grinding unit 500B is moved in the X direction and the Y direction. The relative position between the active layer wafer 20 and the chamfer wheel 200 may be tracked and controlled. Further, the relative position may be track-controlled by moving both the active layer wafer 20 and the chamfer wheel 200 in the X direction and the Y direction.

Hereinafter, specific embodiments of the bonded wafer 100 suitable for application to the method of the present invention will be described. However, it is naturally understood that the method of the present invention is not limited to the following specific examples.

As the support substrate wafer 10 and the active layer wafer 20, a single crystal silicon wafer made of a silicon single crystal can be used. As the single crystal silicon wafer, one obtained by slicing a single crystal silicon ingot grown by the Czochralski method (CZ method) or the floating zone melting method (FZ method) with a wire saw or the like can be used. Further, carbon and / or nitrogen may be added to the single crystal silicon wafer. Further, any impurities may be added to obtain n-type or p-type. Further, the support substrate wafer 10 and the active layer wafer 20 may be bulk compound semiconductors such as GaAs and SiC other than silicon single crystals. The support substrate wafer 10 and the active layer wafer 20 may be the same type of substrates as each other, or different types of substrates may be used. Further, in the case of the same type of substrate, the conductive type (p type and n type) and the conductivity may be the same or different. Further, the terrace processing method of the present invention can be applied to both wafers before terrace processing regardless of whether a notch indicating a crystal orientation or an orientation flat is formed on both wafers. The shape and size of the orifra formed on the active layer wafer 20 may be appropriately determined with reference to the notch or the orifla before processing of the active layer wafer 20.

As the insulating film 30, silicon oxide formed on the surface of the silicon wafer by heat-treating the silicon wafer in an oxidizing atmosphere can be used. Further, the insulating film 30 is not limited to silicon oxide, and an electric insulator can be used. For example, silicon nitride may be used, or diamond or diamond-like carbon (DLC) may be used. can.

The active layer wafer 20 can be formed into an active layer 21 by undergoing circumferential partial terrace processing and orifra partial terrace processing, as well as etching and thinning by subsequent steps (see FIG. 1).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In the following examples and conventional examples, the terrace processing is performed under the condition of emphasizing the load stress.

<Example>
A silicon wafer having a diameter of 150 mm was prepared as a wafer for a support substrate and a wafer for an active layer. Two silicon wafers were bonded together via an oxide film, and a strengthening heat treatment was performed to strengthen the bonding of the bonded surfaces to prepare a bonded wafer before terrace processing. Next, using a wafer terrace chamfering device (manufactured by Daitron Co., Ltd., model number: WBM-2200A), the circumferential portion terrace processing and the orientation flat portion terrace processing are continuously performed on the bonded wafer according to the terrace processing method according to the present invention. gone. The terrace processing was performed until the residual thickness of the silicon portion in the terrace processing portion of the active layer wafer was 10 μm. Further, # 800 diamond abrasive grains were used as the grinding wheel. In addition, the processing of the bonded wafer was performed in two passes (that is, the wafer was rotated twice). Finally, the terraced portion was removed by etching to form a terrace.

<Conventional example>
After the circumferential partial terrace processing was performed, the terrace processing was performed in the same manner as in the examples except that the Orifra partial terrace processing was performed separately and independently. In addition, the circumferential partial terrace processing was performed in 2 passes, and the orifura partial terrace processing was performed in 1 pass.

(Evaluation 1: Observation immediately after terrace processing)
In each of the examples and the conventional examples, the state of the vicinity of the orifra portion immediately after the terrace processing was observed. Photographs of the vicinity of the orifra portion are shown in FIG. 6A (Example) and FIG. 7A (conventional example), respectively. In FIG. 7A according to the conventional example, peeling of silicon is observed near the edge of the terraced portion, while in FIG. 6A according to the embodiment, the silicon peeling portion in FIG. 7A is hardly observed. Therefore, FIG. 6A according to the embodiment is determined to be good, while FIG. 7A according to the conventional example is determined to be defective.

(Evaluation 2: Observation after etching treatment)
Alkali etching with TMAH (tetramethylammonium hydroxide) was further performed on each of the examples and the conventional examples, and the state change in the vicinity of the orifra portion was observed. Photographs of the vicinity of the orifra portion are shown in FIG. 6B (Example) and FIG. 7B (conventional example), respectively. In FIG. 7B according to the conventional example, the trace of the silicon peeled portion observed in FIG. 7A is confirmed on the chamfered portion side of the terrace. On the other hand, in FIG. 6B according to the example, no trace of such a peeled portion was confirmed, and the finish after etching was good. In the conventional example, it is considered that the silicon peeled portion forms a pit by etching, and such a bonded wafer does not satisfy the product specifications and is therefore a target for disposal.

As described above, it has been confirmed that the terrace processing method of the present invention can reduce the load stress during the terrace processing of the orifura portion and reduce the distortion (processing damage) of the processed portion as compared with the conventional technique.

According to the present invention, it is possible to provide a method for manufacturing a bonded wafer capable of stably producing a bonded wafer having a terrace surface provided on the wafer for a support substrate.

10 Wafer for support substrate 20 Active layer wafer 21 Active layer 30 Insulating film 100 Laminated wafer 200 Chamfering wheel 210 Grinding wheel 310 Table 220, 320 Drive unit 500 Terrace chamfering device 500A Wafer feeding unit 500B Grinding unit _TA Terrace _TB Terrace processing Department

Claims (3)

A bonded wafer in which a support substrate wafer and an active layer wafer are bonded together via an insulating film, and the peripheral edge of the active layer wafer is terraced using a chamfering wheel provided with a grinding wheel. It ’s a terrace processing method.
The first step of starting the rotation of each of the bonded wafer and the chamfered wheel, and
The second step of pressing the grinding wheel and the bonding wafer in the thickness direction of the bonded wafer while rotating the active layer wafer against the grinding wheel of the chamfer wheel is included.
In the second step, while maintaining the rotational contact between the active layer wafer and the grinding wheel, the circumferential portion terrace processing of the active layer wafer and the terrace processing of the orientation flat portion of the active layer wafer are continuously performed. Do it
In the terrace processing of the orientation flat portion of the active layer wafer in the second step, the chamfer wheel and the chamfering wheel are bonded together while maintaining the rotational contact state along the shape of the orientation flat portion of the active layer wafer. Follow-up control of the distance to the wafer,
(I) In the rotation from the start point at which the contact of the orientation flat portion starts to the center point of the orientation flat portion, the speed component of the bonded wafer relatively approaching the chamfer wheel is decelerated. However, the approaching process to be given and
(Ii) In the rotation from the center point of the orientation flat portion to the end point at which the contact with the bonded wafer ends, the velocity component in the direction opposite to the velocity component is applied to the bonded wafer to increase the velocity. However, the separation process to be applied and
A method for terrace processing of bonded wafers, which comprises performing the follow-up control in the second step . The terrace processing method for a bonded wafer according to claim 1 , wherein the bonded wafer is rotated for two or more turns. The method for terrace processing of a bonded wafer according to claim 1 or 2 , wherein both the support substrate wafer and the active layer wafer are silicon wafers.

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