JP2021146485A - Manufacturing method of single crystal substrate and wrapping device - Google Patents

Abstract

To prevent an inner carrier from running on an outer carrier during double-face wrapping processing by a double carrier method, and reduce warpage of a substrate after wrapping processing.SOLUTION: In a manufacturing method of a single crystal substrate, a single crystal substrate is obtained by wrapping a single crystal substrate material by a wrapping device using a double carrier in which the single crystal substrate material held by an inner carrier is arranged in a plurality of carrier holes arranged on an outer carrier. The single crystal substrate material held by the inner carrier is arranged in at least one of the plurality of carrier holes, a support substrate where a wrap rate is lower than the single crystal substrate material is arranged in at least one of the plurality of carrier holes, and the single crystal substrate material and the support substrate are simultaneously wrapped.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for manufacturing a single crystal substrate and a wrapping device.

Lithium niobate single crystal substrates obtained from lithium tantalate (LT) single crystals and lithium niobate single crystal substrates obtained from lithium niobate (LN) single crystals remove electrical signal noise mainly used in mobile communication equipment. This is a piezoelectric single crystal substrate for a surface acoustic wave element (SAW filter).

LT and LN single crystals are mainly produced by the Czochralski method, and are usually grown in an electric furnace using a noble metal crucible having a high melting point, cooled at a predetermined cooling rate, and then taken out from the electric furnace. .. In order to remove residual strain due to thermal stress, the grown single crystal is heat-treated under soaking temperature close to the melting point, and further polled to make it single-polarized, that is, the single crystal is set to a predetermined temperature from room temperature to Curie temperature or higher. A series of treatments are performed in which the temperature is raised to a temperature, a voltage is applied to the single crystal, the temperature is lowered to a predetermined temperature equal to or lower than the Curie temperature while the voltage is applied, and then the voltage application is stopped to cool the room temperature. After the polling process, the grown single crystal is processed into a wafer-shaped single crystal substrate by slicing a single crystal ingot whose outer surface is ground to form a columnar shape in order to adjust the outer shape.

As a procedure for processing a columnar single crystal ingot into a wafer-shaped single crystal substrate, machining such as a cylindrical grinding step, a slicing step, a bevel step, a lapping step, an etching step, and a polishing step is usually performed in order (for example,). See Patent Document 1). The processing target of Patent Document 1 is a compound semiconductor substrate, but the same applies to an LT or LN single crystal substrate, which is machined by a slicing process, a bevel process, a wrapping process, an etching process, a polishing process, or the like. It becomes a crystal substrate (hereinafter, simply referred to as a single crystal substrate).

In the above wrapping step, the double-sided simultaneous wrapping process using free abrasive grains is generally performed by a wrapping device. A general wrapping device has a configuration in which an upper surface plate that can be raised and lowered, a lower surface plate, and a carrier that is arranged between the upper surface plate and the lower surface plate and has a gear portion on an outer peripheral portion. The single crystal substrate is installed in a carrier hole provided in the carrier, and is rotated and polished while being pressurized between the upper and lower surface plates.

In the double-sided lapping process, in the case of an oxide single crystal substrate of LT or LN, which is a brittle material, the substrate rotates during processing, and the substrate is damaged or worn due to contact between the end face of the carrier hole and the substrate. There was also a problem. Therefore, in order to solve the above problems, a double carrier method as described in Patent Document 2 below may be used. In this double carrier method, since the end face of the carrier hole and the substrate do not come into direct contact with each other, damage or wear of the substrate due to contact between the end face of the carrier hole and the substrate can be suppressed.

Japanese Unexamined Patent Publication No. 2009-182135 Japanese Unexamined Patent Publication No. 57-41164

By the way, in the SAW filter, a metal thin film is formed on a piezoelectric single crystal substrate by sputtering, and then a pair of comb-shaped patterns are left by a photolithography technique and unnecessary portions are etched and removed to form a comb-shaped electrode. If the warp of the substrate is large, there is a problem that the substrate cracks and the yield decreases during the manufacturing of the SAW filter, and a substrate with a small warp is required to improve the yield.

In the lapping process, if the substrate before the lapping process is warped, the substrate is pressurized by the upper and lower surface plates and is polished in an elastically deformed state. Therefore, when the substrate is taken out from the carrier after the lapping process is completed, the substrate is released from its elastic deformation and the warp becomes apparent again. In the wrapping process, in order to suppress elastic deformation due to pressurization of the upper and lower surface plates of the substrate, it is possible to reduce the above warpage by performing a method of processing by reducing the pressure during wrapping processing, so-called low pressure wrapping processing. Is. However, when the pressure during the lapping process is reduced, the double carrier method has a problem that the inner carrier rides on the outer carrier and the single crystal substrate comes off from the inner carrier hole and cracks.

An object of the present invention is to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to reduce the warp of the substrate after the lapping process.

The present inventors have conducted diligent research in order to achieve the above object, and in the double carrier method, by holding a single crystal substrate as a workpiece and a specific supporting substrate on a carrier and performing a wrapping process. The present invention has been completed by finding that it is possible to prevent the inner carrier from riding on the outer carrier and reduce the warpage of the substrate after processing.

According to the aspect of the present invention, the single crystal substrate material is wrapped by a wrapping device using a double carrier in which the single crystal substrate material held by the inner carrier is arranged in a plurality of carrier holes provided in the outer carrier. A method for manufacturing a single crystal substrate for obtaining a crystal substrate, wherein a single crystal substrate material held by an inner carrier is arranged in at least one of a plurality of carrier holes, and the single crystal substrate material is placed in at least one of a plurality of carrier holes. Also provided is a method for manufacturing a single crystal substrate, which comprises arranging a support substrate having a slow wrap rate and wrapping the single crystal substrate material and the support substrate at the same time.

Further, the wrap rate of the supporting substrate may be 0.1 times or more and 0.5 times or less with respect to the wrap rate of the single crystal substrate material. Further, the thickness of the supporting substrate may be less than or equal to the maximum height including the warp of the single crystal substrate material. Further, the thickness of the supporting substrate may be equal to or more than a value obtained by adding the thickness of the single crystal substrate material not including the warp of the single crystal substrate material to 1/2 of the warp amount of the single crystal substrate material. Further, it may include removing the polishing powder of the supporting substrate generated by the lapping process with a magnet in a tank containing the processing liquid. Further, the single crystal substrate material may be a single crystal of lithium tantalate or lithium niobate, and the supporting substrate iron may be one selected from the group consisting of stainless steel and SK material.

Further, according to the aspect of the present invention, it is a wrapping device in which a carrier holding a single crystal substrate material is mounted between an upper surface plate and a lower surface plate, and the single crystal substrate material is wrapped using free abrasive grains. The carrier has a plurality of carrier holes and an inner carrier that holds the single crystal substrate material and is arranged in at least one of the plurality of carrier holes, and at least one of the plurality of carrier holes during the wrapping process. A wrapping device is provided that is arranged in one and includes a supporting substrate having a slower wrap rate than a single crystal substrate material.

According to the present invention, it is possible to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to reduce the warpage of the substrate after the lapping process easily and at low cost.

It is a figure which shows an example of the wrapping apparatus which concerns on embodiment. (A) and (B) are diagrams showing an example of a carrier, (A) shows a state before mounting a single crystal substrate material and a supporting substrate, and (B) shows a state before mounting the single crystal substrate material and a supporting substrate, and (B) is a single crystal substrate material and supporting substrate. Indicates a state in which the substrate is mounted. It is a figure which shows the cross section along the line AA shown in FIG. 2 (B). (A) and (B) are diagrams for explaining the processing of a single crystal substrate material by the wrapping device according to the embodiment. It is a figure which shows another example of a carrier. It is a flowchart which shows an example of the manufacturing method of the single crystal substrate which concerns on embodiment.

Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not limited to this. In addition, in order to explain the embodiment, the drawings are expressed by changing the scale as appropriate, such as drawing a part in a large or emphasized manner. Further, in each of the following figures, the directions in the drawings will be described using the XYZ coordinate system. In this XYZ coordinate system, the vertical direction is the Z direction, and the horizontal direction is the X direction and the Y direction. Further, in each of the X direction, the Y direction, and the Z direction, the side at the tip of the arrow is referred to as a + side (eg, + X side), and the opposite side is referred to as a − side (eg, −X side).

[Embodiment]
First, the wrapping device according to the present embodiment will be described. FIG. 1 is a diagram showing an example of the wrapping device of the present embodiment. In addition, in FIG. 1, a part of the upper surface plate 4 is cut out and partially shown. In the wrapping device 1 of the present embodiment, as shown in FIG. 1, a carrier 2 (outer carrier 20) holding the single crystal substrate material S and the supporting substrate SP is mounted between the upper surface plate 4 and the lower surface plate 5. This is an apparatus for wrapping the substrate S by the double carrier method using the free abrasive grains L (see FIG. 4 (A)).

A general wrapping device includes a sun gear 8 provided at the center of the lower surface plate 5 as shown in FIG. 1, an internal gear 7 provided around the lower surface plate 5, and an upper surface plate 4. Further, the upper surface plate rotation drive unit 10 for rotating the upper surface plate 4, the upper surface plate elevating drive unit 11 for raising and lowering the upper surface plate 4, the lower surface plate rotation drive unit 12 for rotating the lower surface plate 5, and the sun gear 8 are rotated. A sun gear rotation drive unit 14 and an internal gear rotation drive unit 13 for rotating the internal gear 7 are provided.

The lower surface plate 5 has the shape of an annular disk, and the upper surface thereof is grooved to promote the flow of free abrasive grains L used for polishing the single crystal substrate material S (workpiece). The free abrasive grains L have a function of flowing on the surface plate to polish the lower surface of the work piece, and are rotated by the lower surface plate rotation driving unit 12. The sun gear 8 is arranged on the center side (center portion) of the lower platen 5, and is rotationally driven by the sun gear rotation drive unit 14. The pin-shaped teeth of the sun gear 8 mesh with the gear portion on the outer circumference of the carrier 2. The internal gear 7 is arranged on the outer peripheral side of the lower platen 5, and is rotationally driven by the internal gear rotation drive unit 13. The pin-shaped teeth of the internal gear 7 mesh with the gear portion on the outer circumference of the carrier 2. The carrier 2 on which the single crystal substrate material S arranged on the lower platen 5 is mounted meshes with the sun gear 8 and the internal gear 7 and rotates.

A carrier hole 21 for holding the single crystal substrate material S is installed in the carrier 2, and the single crystal substrate material S is arranged in the carrier hole 21. The upper surface plate 4 is an annular disk, and the lower surface thereof is grooved to promote the flow of free abrasive grains used for polishing the single crystal substrate material S, and the free abrasive grains flow to the single crystal substrate. It has a function of polishing the upper surface of the material S. The upper surface plate 4 and the lower surface plate 5 are arranged so as to be centered on the same central axis AX1. The sun gear 8 and the internal gear 7 are configured to rotate independently, and the degree of rotation and revolution is determined by the rotation ratio or speed of the shaft with respect to each gear. The carrier 2 on which the single crystal substrate material S is mounted also undergoes a rotational motion corresponding to its rotation and revolution. The single crystal substrate material S mounted on the carrier 2 sandwiched between the upper surface plate 4 and the lower surface plate 5 is the upper surface plate 4 and the lower surface plate 5 due to the rotation and pressurization of the upper surface plate 4 and the lower surface plate 5. Between 5 and 5, it is polished by the free abrasive grains L.

There are various types of carriers 2 used for double-sided lapping, and they are usually produced by processing iron, stainless steel, or SK material. The carrier hole 21 has a positive tolerance added, and the single crystal substrate material S is rotating in the carrier hole 21. When the single crystal substrate material S is arranged in the carrier hole 21 and polished using the free abrasive grains L, there is no problem in the case of a single crystal substrate made of a high hardness material, but as described above, the brittle material has a low hardness. In the case of the LT or LN oxide single crystal substrate, since the carrier is made of iron, stainless steel, or SK material and has high rigidity, there is a problem that damage such as chipping and scratches is likely to occur on the end face of the single crystal substrate. Further, since the substrate rotates during the lapping process, there is a problem that the substrate is worn due to contact between the end face of the carrier hole 21 and the single crystal substrate.

Therefore, in order to solve the above problem, a double carrier method is used when performing double-sided wrapping. 2A and 2B are plan views showing an example of the carrier of the wrapping device 1 of the present embodiment, and FIG. 2A shows a state before mounting the single crystal substrate material and the supporting substrate. (B) shows a state in which the single crystal substrate material and the supporting substrate are mounted. In this double carrier method, the carrier 2 has an outer carrier (conventional carrier) 20 and an inner carrier 22 (jig), and a plurality of carrier holes 21 are provided in the outer carrier 20, and the carrier holes 21 are provided. The inner carrier 22 is rotatably arranged inside. In the double carrier method, the inner carrier 22 is provided with an inner carrier hole 23 (holding portion) for holding the single crystal substrate material S, and the inner carrier hole 23 (holding portion) of the inner carrier 22 is mounted with the single crystal substrate material S. The single crystal substrate material S is polished (see FIGS. 2A and 2B). The inner carrier hole 23 has an annular shape in a plan view. The size of the inner carrier hole 23 corresponds to the size of the target single crystal substrate material S. The inner carrier hole 23 is held so as to surround the side surface (circumferential surface) of the disk-shaped single crystal substrate material S. The shape of the single crystal substrate material S is not limited to a circular shape in a plan view, and may be, for example, a polygonal shape or an indefinite shape in a plan view.

The wrapping device 1 of the present embodiment is a lithium tantalate single crystal substrate (LT single crystal substrate) obtained from a lithium tantalate (LT) single crystal, and a lithium niobate single crystal substrate obtained from a lithium niobate (LN) single crystal. A brittle single crystal substrate material S such as (LN single crystal substrate) can be suitably double-sided wrapping. In the lapping step, if the substrate before the lapping process is warped, the substrate is pressurized by the upper surface plate and the lower surface plate, and is polished in an elastically deformed state. Therefore, when the substrate is taken out from the carrier after the lapping process is completed, the substrate is released from its elastic deformation and the warp becomes apparent again. In the lapping process, in order to suppress elastic deformation due to pressurization of the upper and lower surface plates of the substrate, the above warpage is reduced by performing a method of reducing the pressure during lapping, so-called low-pressure ping processing. It is possible. However, if the pressure during the lapping process is reduced, the double carrier method has a problem that the inner carrier rides on the outer carrier and the substrate comes off from the inner carrier hole and cracks.

Therefore, in the wrapping device 1 of the present embodiment, as shown by an example in FIG. 2B, at the same time as the single crystal substrate material S, the supporting substrate SP having a slower wrap rate than the single crystal substrate material S is used as the outer carrier 20. By arranging and wrapping at the same time as the single crystal substrate material S, it is possible to prevent the inner carrier from riding on the outer carrier during double-sided wrapping by the double carrier method, and wrapping without performing the low-pressure wrapping. It is possible to reduce the warp of the single crystal substrate SA obtained later. That is, the wrapping device 1 of the present embodiment includes a supporting substrate SP that can be arranged on the outer carrier 20 and has a slower wrap rate than the single crystal substrate material S.

The supporting substrate SP that is subjected to the lapping process at the same time as the single crystal substrate material S is not particularly limited as long as the wrap rate (polishing rate) is slower (smaller) than that of the single crystal substrate material S. The supporting substrate SP is, for example, an iron material, a SUS material, an SK material (carbon tool steel), or the like. The wrap rate is a polishing speed (polishing amount per unit time) when one supporting substrate SP is polished by the above lapping device under the same processing conditions such as a polishing liquid and a load during polishing. ..

In general, the higher the hardness of the material, the lower the wrap rate tends to be. The wrap rate of the supporting substrate SP is preferably 0.1 times or more and 0.5 times or less with respect to the wrap rate of the single crystal substrate material S. When the wrap rate of the supporting substrate SP is within the above range, it is possible to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to obtain the result after the lapping process without performing the low-pressure lapping process. The effect of reducing the warp of the single crystal substrate SA to be obtained can be suitably exhibited. If the wrap rate of the supporting substrate SP exceeds 0.5 times the wrap rate of the single crystal substrate material S, the effect of wrapping the single crystal substrate material S at a low pressure is reduced. When the wrap rate of the support substrate SP is less than 0.1 times the wrap rate of the single crystal substrate material S, the lapping process of the support substrate SP is slowed down, resulting in poor production efficiency. The wrap rate of the supporting substrate SP is more preferably 0.3 times or less the wrap rate of the single crystal substrate material S. For example, when the single crystal substrate material S is an LT single crystal substrate, if the supporting substrate SP is an iron material, it is 0.3 times the wrap rate of the LT single crystal substrate, and if it is a SUS material or an SK material, it is 0. . Double.

FIG. 3 is a diagram showing a cross section taken along the line AA shown in FIG. 2 (B). 4 (A) and 4 (B) are views for explaining the processing of the single crystal substrate material S by the wrapping device 1 according to the present embodiment.

In the processing of the single crystal substrate material S by the wrapping device 1 of the present embodiment, first, as shown in FIGS. 2 (B) and 3, at least one of a plurality of carrier holes 21 provided in the carrier 2 (outer carrier 20). The single crystal substrate material S held by the inner carrier 22 is arranged therein, and the supporting substrate SP is arranged in at least one of the plurality of carrier holes 21. The arrangement of the supporting substrate SP on the outer carrier 20 does not change the shape of the conventional outer carrier 20 as shown in FIG. 2 (A), and a part of the single crystal substrate material in which the single crystal substrate material S is arranged is arranged. The support substrate SP may be arranged instead of S. A plurality of supporting substrates SP may be evenly arranged in a portion where the single crystal substrate material S is not arranged on the outer carrier 20. When the conventional carrier 2 is used, the wrapping device 1 of the present embodiment and the method of manufacturing the single crystal substrate of the present embodiment described later can be carried out easily and at low cost.

As shown in FIG. 3, the single crystal substrate material S before the lapping process has a warp. In the lapping process, it is preferable that the front and back surfaces of the single crystal substrate material S are polished to reduce the surface roughness and the warp of the single crystal substrate material S is reduced.

The wrapping device 1 of the present embodiment simultaneously wraps the single crystal substrate material S arranged on the outer carrier 20 and the supporting substrate SP. In the wrapping device 1 of the present embodiment, the single crystal substrate material S has a faster wrap rate than the supporting substrate SP, and therefore is polished faster than the supporting substrate SP under the same conditions. Therefore, as shown in FIG. 4A, the single crystal substrate material S is polished while the supporting substrate SP side supports the load during the lapping process. As a result, the wrapping device 1 of the present embodiment has the same effect as the low-pressure wrapping, and the load applied to the single crystal substrate material S during the wrapping process is minimized to gradually polish the warp of the single crystal substrate material S. be able to. Further, since the wrap rate of the supporting substrate SP is slower, the single crystal substrate material S can polish the elastically deformed portion more preferentially, and the warp is alleviated with polishing. As a result of the above, it is possible to effectively remove the warp of the single crystal substrate material S before processing as shown in FIG. 4 (B). Further, since the wrapping device 1 does not perform so-called low-pressure wrapping as described above, it is possible to prevent the inner carrier from riding on the outer carrier in the above-mentioned double carrier method. In the wrapping device 1, when the wrap rate of the supporting substrate SP is equal to the wrap rate of the single crystal substrate material S or equal to or higher than the wrap rate of the single crystal substrate material S, the appearance of the above effect is suppressed.

As shown in FIG. 2A, a plurality of carrier holes 21 for mounting the single crystal substrate material S are provided at positions eccentric from the center of the outer carrier 20 when the outer carrier 20 is viewed in a plan view (+ Z side). It is preferable from the viewpoint of processing efficiency. The positions of the plurality of carrier holes 21 in the outer carrier 20 are such that the four carrier holes 21 have the same size in a plan view and the four carrier holes 21 are arranged rotationally symmetrically with respect to the center of the outer carrier 20. It is well-balanced and preferable. Further, when the single crystal substrate material S exceeds or is close to the radius of the outer carrier 20, the outer carrier 20 may have different sizes of the plurality of carrier holes 21 as shown in another example of FIG. .. It is preferable that the single crystal substrate material S is arranged in the maximum size carrier hole 21 arranged on the −X side, and the other carrier holes 21 (21a to 21e) are arranged so as to surround the single crystal substrate material S. .. The single crystal substrate material S may not be arranged in the carrier holes 21 (21a to 21e), but the supporting substrate SP described later may be arranged. It is preferable that the positions of the plurality of carrier holes 21 in the outer carrier 20 are arranged symmetrically in a plan view as shown in the example of FIG. 5 because the balance is good. Further, it is preferable that the positions of the plurality of carrier holes 21 in the outer carrier 20 are evenly arranged in the outer carrier 20 in a plan view as in the example of FIG. 2A or FIG.

The size of the support substrate SP is not particularly limited. For example, when the outer carrier 20 shown in FIG. 2A is used, the support substrate SP is arranged in place of a part of the single crystal substrate material S in which the single crystal substrate material S is arranged, so that a conventional carrier hole is used. The size of the support substrate SP is appropriately set according to the size of 21.

When the outer carrier 20 shown in FIG. 5 is used, the size of the carrier holes 21 (21a to 21e) in which the single crystal substrate material S is not arranged in the outer carrier 20 and the carrier holes 21 (21a to 21e) are arranged in these carrier holes 21 (21a to 21e). The size of the supporting substrate SP to be supported is preferably set to about 1/4 to 1/2 of the diameter of the single crystal substrate material S.

The thickness T2 of the supporting substrate SP is preferably set to be equal to or less than the maximum thickness (height) T1 (see FIG. 3) including the warp of the single crystal substrate material S. When the thickness T2 of the supporting substrate SP is thicker than the maximum thickness T1 of the single crystal substrate material S, only the supporting substrate SP having a slow wrap rate is polished up to the maximum thickness T1 of the single crystal substrate material S. Even if only the supporting substrate SP having a slow lap rate is polished, the effect of reducing warpage is not seen, which is inefficient. Therefore, in order to efficiently reduce the warp of the single crystal substrate material S, it is preferable that the thickness T2 of the supporting substrate SP is not more than the maximum thickness T1 including the warp of the single crystal substrate material S. Further, the thickness T2 of the supporting substrate SP is preferably a thickness T3 or more of the single crystal substrate material S that does not include the warp of the single crystal substrate material S. When the thickness T2 of the supporting substrate SP is less than the thickness T3 of the single crystal substrate material S that does not include the warp of the single crystal substrate material S, the single crystal substrate is processed by the lapping process, although it depends on the processing amount during the lapping process. The warp of the material S may not be completely removed. The thickness T2 of the supporting substrate SP is the maximum thickness T1 or less including the warp of the single crystal substrate material S, and the warp of the single crystal substrate material S (= the maximum thickness T1-single crystal including the warp of the single crystal substrate material S). Single crystal substrate that does not include the warp of the single crystal substrate material S in 1/2 of the amount of the thickness T3) that does not include the warp of the substrate material S (referred to as "warp of the single crystal substrate material S (T1-T3)") It is preferable to set the thickness T3 of the material S to a value obtained by adding the sum. The thickness T2 of the supporting substrate SP is added to the thickness T3 of the single crystal substrate material S that does not include the warp of the single crystal substrate material S to 1/2 of the warp (T1-T3) of the single crystal substrate material S described above. By setting it to a value equal to or higher than the specified value, the warp of the single crystal substrate material S can be removed more reliably.

The single crystal substrate material S is lapping by the above double carrier method, but the supporting substrate SP to be lapping at the same time is iron, stainless steel, or SK material, which is the same type as the normally used outer carrier. Therefore, it is not necessary to perform the lapping process by the double carrier method, and as shown in FIG. 3, the inner carrier 22 may be installed in the carrier hole 21 without being used.

Further, it is preferable that the polishing debris of the supporting substrate SP is separated from the polishing slurry during the lapping process so that the polishing debris of the supporting substrate SP does not affect the quality of the lapping surface. Therefore, in the lapping device 1, for example, the magnet 31 may be installed in the tank 30 that houses the polishing slurry (polishing liquid) that is circulated and used (see FIG. 1). As a result, the polishing debris of the supporting substrate SP can be easily separated. The magnet 31 is, for example, a permanent magnet or an electric magnet. When the magnet 31 is installed in the tank 30, it may be covered with a member capable of covering the magnet 31, for example, resin (vinyl) or the like. As a result, the polishing debris bonded to the magnet 31 can be easily separated from the magnet 31.

Selecting a material having bondability to the magnet 31 such as iron, stainless steel (SUS 410 material, etc.), SK material, etc. as the material of the support substrate SP removes the polishing debris of the support substrate SP as described above. It is also useful from the viewpoint that it can be easily separated. By removing the polishing debris of the supporting substrate SP from the polishing slurry, the influence of the polishing debris on the quality of the single crystal substrate material S can be suppressed, and the influence on the lapping conditions can be reduced.

As described above, in the wrapping device 1 of the present embodiment, the carrier 2 holding the single crystal substrate material S is mounted between the upper surface plate 4 and the lower surface plate 5, and the single crystal substrate is used with the free abrasive grains L. A wrapping device for lapping the material S, the carrier 2 includes a plurality of carrier holes 21, an inner carrier 22 that holds the single crystal substrate material S and is arranged in at least one of the plurality of carrier holes 21. It is provided with a supporting substrate SP which is arranged in at least one of a plurality of carrier holes 21 at the time of lapping processing and has a slower wrap rate than the single crystal substrate material S. The configuration other than the above is an arbitrary configuration in the wrapping device 1. According to the wrapping device 1 of the present embodiment, it is easy to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to significantly reduce the warp of the substrate after the lapping process. Easy to implement.

That is, the lapping device 1 of the present embodiment may be, for example, a conventional lapping device including a conventional carrier 2 (outer carrier 20), an upper surface plate 4, and a lower surface plate 5 provided with a supporting substrate SP. .. That is, in the lapping device 1 of the present embodiment, as the outer carrier 2, the inner carrier 3, the upper surface plate 4, and the lower surface plate 5, those used for the known (conventional) lapping device can be used.

Next, a method for manufacturing a single crystal substrate according to this embodiment will be described. FIG. 6 is a flowchart showing a method for manufacturing a single crystal substrate according to the present embodiment. The method for manufacturing a single crystal substrate of the present embodiment uses a double carrier in which the single crystal substrate material S held by the inner carrier 22 is arranged in a plurality of carrier holes 21 provided in the outer carrier 20 (carrier 2). A method for manufacturing a single crystal substrate by wrapping a single crystal substrate material S with a wrapping device to obtain a single crystal substrate SA, wherein the single crystal substrate material S held by an inner carrier 22 in at least one of a plurality of carrier holes 21 is provided. The supporting substrate SP having a slower wrap rate than the single crystal substrate material S is arranged in at least one of the plurality of carrier holes 21 (step S1 in FIG. 5), and the single crystal substrate material S and the supporting substrate SP are arranged. Is included in step S2) of FIG. The method for manufacturing a single crystal substrate according to the present embodiment can be preferably carried out by, for example, the wrapping device 1 of the present embodiment described above. According to the method for manufacturing a single crystal substrate of the present embodiment, it is possible to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to significantly reduce the warp of the substrate after the lapping process. Can be easily and easily carried out.

In the method for manufacturing the single crystal substrate of the present embodiment, the configurations other than the above are arbitrary configurations. For example, the method for producing a single crystal substrate of the present embodiment may include steps other than the above. The items described in the wrapping device 1 of the present embodiment described above may be included. The supporting substrate SP may be one selected from the group consisting of iron, stainless steel, and SK material. Further, the thickness T2 of the supporting substrate SP is preferably not more than the maximum height T1 including the warp of the single crystal substrate material S. Further, the thickness T2 of the supporting substrate SP is equal to or more than a value obtained by adding the thickness of the single crystal substrate material S not including the warp of the single crystal substrate material S to 1/2 of the warp amount of the single crystal substrate material S. Is preferable. Further, the polishing powder of the supporting substrate SP generated by the lapping process may be removed by the magnet 31 in the tank 30 containing the processing liquid. Further, the single crystal substrate material S may be a single crystal of lithium tantalate or lithium niobate.

In the present specification, the thickness, warp, wrap rate, etc. of the single crystal substrate material S and the thickness, warp, wrap rate, etc. of the support substrate SP are the single crystal substrate material S or the support substrate, respectively. When there are a plurality of SPs, it means the maximum value in the plurality of single crystal substrate materials S or the supporting substrate SP.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples.

[Example 1]
Wrapping was performed using the double-sided wrapping device 1 shown in FIG. As the outer carrier 20, the carrier shown in FIG. 5 was used. First, as shown in FIG. 3, a resin inner carrier 22 (inner diameter 200) is formed in a carrier hole 21 (inner diameter 230.3 mm) of a stainless steel (500 μm thickness) outer carrier 20 thinner than the thickness (T3) of the single crystal substrate. .3 mm, 500 μm thickness) is set, and the 42 ° RY 8 inch φ (200 mm) single crystal substrate material S of lithium tantalate (LT) single crystal is set in the carrier hole of the inner carrier 22, and for supporting the outer carrier 20. Each of the carrier holes 21 (21a to 21e) for the substrate SP is made of 600 μm thick stainless steel and has a wrap rate of 0.2 times that of the LT single crystal substrate material S. A total of 5 pieces were set. The single crystal substrate material S before processing had a thickness T3 excluding the warp of the substrate of 550 μm, a warp of the substrate (T1-T3) of 50 μm, and a maximum thickness T1 including the substrate of 600 μm. The maximum thickness T1 of the single crystal substrate material S and the thickness T2 of the stainless steel support substrate SP were the same. Set 5 sets of the above outer carrier 20, inner carrier 22, LT substrate, and stainless steel support substrate SP, and use GC # 1000 slurry at a ^{pressure (machining pressure) of 0.9 N / cm 2 to obtain the single crystal substrate material S.} The thickness was set to be polished to 530 μm, and polishing was performed. The thickness T3 of the single crystal substrate material S, which does not include the warp of the substrate, was measured with a micrometer. The maximum thickness T1 of the single crystal substrate material S including the warp of the substrate was measured by placing the single crystal substrate material S on a surface plate and measuring the maximum height micrometer. The warp was calculated by subtracting the thickness T3 of the single crystal substrate material S not including the warp from the maximum thickness T1 including the warp of the substrate of the single crystal substrate material S.

As a result, in the wrapping process, the single crystal substrate material S is elastically deformed and polishing starts at the same time as the stainless steel supporting substrate SP, but the wrap rate is slower in the supporting substrate SP, so that the single crystal substrate material S is elastic. The deformed part was polished more preferentially. Therefore, the warp was alleviated with polishing.

The single crystal substrate SA obtained after processing was evaluated. When the single crystal substrate SA after processing was etched and the warp was measured, the warp was 5 μm, and the warp was reduced by 45 μm from that before processing. The maximum thickness of the processed single crystal substrate material S including the warp was 530 μm. The single crystal substrate material S was not cracked during the lapping process. Table 1 shows the conditions of the lapping process, the evaluation results of the single crystal substrate material S before and after the process, the thickness and warpage of the single crystal substrate SA, and the like.

[Example 2]
The lapping process and the evaluation of the single crystal substrate material S and the single crystal substrate SA before and after the lapping process were performed in the same manner as in Example 1 except that the thickness T2 of the support substrate SP was changed by 575 μm. When the single crystal substrate SA after processing was etched and the warp was measured, the warp was 10 μm, and the warp was reduced by 40 μm from that before processing. The maximum thickness of the processed single crystal substrate SA including the warp was 540 μm. The single crystal substrate material S was not cracked during the lapping process. Table 1 shows the conditions of the lapping process, the evaluation results of the single crystal substrate material S before and after the process, the thickness and warpage of the single crystal substrate SA, and the like.

[Example 3]
As the outer carrier 20, the carrier shown in FIG. 2 was used. As shown in FIG. 3, the carrier holes 21 (inner diameter 160.3 mm) made of stainless steel (500 μm thickness) thinner than the thickness (T3) of the single crystal substrate material S are made of resin in three of the four outer carriers 20. The inner carrier 22 (inner diameter 150.3 mm, 500 μm thickness) is set, and the LT 42 ° RY 6 inch φ (150 mm) single crystal substrate of lithium tantalate (LT) single crystal is set in the carrier hole of the inner carrier 22. A support substrate SP made of stainless steel having a size of 160 mm and a thickness of 600 μm and having a wrap rate of 0.2 times that of the LT single crystal substrate material S was set in one carrier hole. Other conditions and the like were the same as in Example 1.

When the LT 6-inch substrate after polishing was etched and the warp was measured, the warp was 5 μm, which was 45 μm less than that before processing. The maximum thickness of the processed single crystal substrate SA including the warp was 535 μm. The single crystal substrate material S was not cracked during the lapping process. Table 1 shows the conditions of the lapping process, the evaluation results of the single crystal substrate material S before and after the process, the thickness and warpage of the single crystal substrate SA, and the like.

[Comparative Example 1]
The lapping process was performed in the same manner as in Example 1 without using the supporting substrate SP. When the processed single crystal substrate SA was etched and the warp was measured, it was 45 μm, and the warp was reduced by only 5 μm. The maximum thickness of the processed single crystal substrate SA including the warp was 575 μm. The single crystal substrate material S was not cracked during the lapping process. Table 1 shows the conditions of the lapping process, the evaluation results of the single crystal substrate material S before and after the process, the thickness and warpage of the single crystal substrate SA, and the like.

[Comparative Example 2]
The lapping process was performed in the same manner as in Example 1 except that the support substrate SP was not used and the processing pressure was 0.15 N / cm ^2. Immediately after the start of processing (polishing), the inner carrier 22 rides on the outer carrier 20, the single crystal substrate material S comes off from the carrier hole of the inner carrier 22, and all five single crystal substrate materials S are cracked.

From the results of the above Examples and Comparative Examples, according to the method for manufacturing a single crystal substrate of the present embodiment, it is possible to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and after the lapping process. It is confirmed that the warp of the substrate in the above can be remarkably reduced.

According to the present invention, according to the method for manufacturing a single crystal substrate of the present embodiment, it is possible to prevent the inner carrier from riding on the outer carrier during the double-sided lapping process by the double carrier method, and to warp the substrate after the lapping process. Can be remarkably reduced, so that a substrate having a small warp can be provided, and the substrate cracking that occurs during the production of the SAW filter can be prevented, and as a result, the yield can be improved.

The technical scope of the present invention is not limited to the embodiments described in the above-described embodiments. One or more of the requirements described in the above embodiments and the like may be omitted. In addition, the requirements described in the above-described embodiments and the like can be combined as appropriate. In addition, to the extent permitted by law, the disclosure of all documents cited in the above-mentioned embodiments and the like shall be incorporated as part of the description in the main text.

S ... Single crystal substrate material SA ... Single crystal substrate 1 ... Lapping device 2 ... Carrier 4 ... Upper surface plate 5 ... Lower surface plate 7 ... Internal gear 8 ... Sun gear 10 ... Upper surface plate rotation drive unit 11 ... Upper surface plate elevating drive unit 12 ... Lower surface plate rotation drive unit 13 ... Internal gear rotation drive unit 14 ... Sun gear rotation drive unit 20 ... Outer carrier 21 ... Carrier hole 22 ... Inner carrier 23 ... Inner carrier hole 30 ... Tank 31 ... Magnet L ... Free abrasive grains

Claims (7)

A single crystal substrate obtained by wrapping the single crystal substrate material with a wrapping device using a double carrier in which the single crystal substrate material held by the inner carrier is arranged in a plurality of carrier holes provided in the outer carrier. It is a manufacturing method of
The single crystal substrate material held by the inner carrier is arranged in at least one of the plurality of carrier holes, and a supporting substrate having a slower wrap rate than the single crystal substrate material is placed in at least one of the plurality of carrier holes. A method for producing a single crystal substrate, which comprises arranging the single crystal substrate material and wrapping the single crystal substrate material and the supporting substrate at the same time. The method for producing a single crystal substrate according to claim 1, wherein the wrap rate of the supporting substrate is 0.1 times or more and 0.5 times or less with respect to the wrap rate of the single crystal substrate material. The method for manufacturing a single crystal substrate according to claim 1 or 2, wherein the thickness of the supporting substrate is equal to or less than the maximum height including the warp of the single crystal substrate material. 3. The method for manufacturing a single crystal substrate according to any one of the above. The single crystal substrate according to any one of claims 1 to 4, which comprises removing the polishing powder of the supporting substrate generated by the lapping process with a magnet in a tank containing a processing liquid. Production method. The single crystal substrate material is a single crystal of lithium tantalate or lithium niobate, and the supporting substrate is one selected from the group consisting of iron, stainless steel, and SK material, according to claim 1. Item 5. The method for producing a single crystal substrate according to any one of Item 5. A wrapping device in which a carrier holding a single crystal substrate material is mounted between an upper surface plate and a lower surface plate, and the single crystal substrate material is wrapped using free abrasive grains.
The carrier has a plurality of carrier holes and an inner carrier that holds the single crystal substrate material and is arranged in at least one of the plurality of carrier holes.
A supporting substrate that is arranged in at least one of the plurality of carrier holes during the lapping process and has a slower wrap rate than the single crystal substrate material is provided.
Lapping device.

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