JP2010023166A - Manufacturing method for single crystal substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a single crystal wafer, capable of adjusting a cutting angle relative to the crystal axis of a crystal to a desired angle. <P>SOLUTION: Initial cutting angle measurement is performed for a crystal wafer having initial polishing by cutting a crystal, aiming at a desired cutting angle thereof relative to a crystal axis thereof from a crystal lumber (step S4). When the initial cutting angle measurement indicates that the cutting angle of the crystal wafer is out of an allowable range of a standard value (No in step S5), a step shape capable of correcting a difference from the standard value of the cutting angle of the crystal wafer measured by the initial cutting angle measurement is determined based on data indicating a relationship between the previously confirmed step shape and a shift amount of cutting angles before and after cutting angle correction polishing, as indicated in step S8. Next, as indicated in step S9, the step of the shape determined in step S8 is formed on the crystal wafer. Cutting angle correction polishing is performed to polish the crystal wafer formed with the step by a predetermined amount (step S10). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a single crystal substrate, and more particularly to a method for manufacturing a single crystal substrate capable of adjusting a cutting angle with respect to a crystal axis of the single crystal substrate to a desired angle.

As a piezoelectric material for piezoelectric vibrating pieces used in piezoelectric devices such as piezoelectric vibrators and piezoelectric oscillators used in electronic equipment such as communication equipment, information equipment, and consumer equipment, it is possible to obtain stable frequency characteristics. Crystal is adopted. This quartz crystal vibrating piece consists of a quartz crystal wafer as a single crystal substrate cut out at a predetermined cutting angle from a quartz lambard in which a portion of an artificial quartz crystal is formed into a block shape with a clear crystal axis (optical axis). Formed using. Here, the predetermined cutting angle refers to a cutting angle inclined by a target angle with respect to the crystal axis of the crystal, for example, using a crystal wafer cut at a cutting angle of 35 degrees 15 minutes from the crystal axis. The formed AT-cut quartz-crystal vibrating piece has long been used as a piezoelectric vibrating piece having excellent temperature characteristics that can obtain a stable frequency in a wide temperature range.
As described above, a cutting method using a wire saw is widely used as a method of cutting a quartz wafer from a quartz lambard at a desired cutting angle (see, for example, Patent Document 1).

  FIG. 12 is a perspective view schematically illustrating the wire saw (multi-wire saw) described in Patent Document 1. In FIG. 12, the wire saw 150 includes a pair of guide rollers 152 having a spiral groove formed on the outer peripheral surface and arranged apart from each other, and one end of one of the pair of guide rollers 152. An endless wire 153 wound around the groove to the other end of the other guide roller 152 and reversed by a roller (not shown) disposed above the same is connected to the same pair of guide rollers 152. And a motor (not shown) that rotates forward or backward in the direction. Also, below the pair of guide rollers 152, a work attachment jig (multi-wire saw jig) 151 used when cutting a work as an object to be cut by the wire saw 150 is disposed. The workpiece attachment jig 151 is configured such that a pasting plate 156 is mounted on a mounting base 155 that can be lifted and lowered by a lifting device (not shown), and a crystal lambard 1A as a workpiece is stuck on the pasting plate 156 with an adhesive. .

  When cutting the crystal lumbard 1A, an X-ray diffractometer is used to draw a target line of a cutting angle (cut angle) that forms a predetermined angle with respect to the crystal axis of the crystal lumbard 1A, and paste the target line. In a state where the reference line on the plate 156 coincides with the reference line, the crystal lambad 1A is attached to the attaching plate 156 with an adhesive. Then, affixing plate 156 with quartz lumbard 1A attached thereto is attached and fixed on mounting base 155, and the pair of guide rollers 152 are rotated in the same direction while raising mounting base 155 by an elevating device. Then, each wire 153 travels in the same direction between the pair of guide rollers 152 and comes into contact with the crystal lambard 1A, and a polishing liquid (not shown) is supplied to the wire 153 and the crystal lambard 1A. A plurality of quartz wafers (quartz pieces) having a cut surface targeted at a predetermined cutting angle are cut out.

  The quartz wafer cut out as described above is polished to such a thickness that a desired frequency can be obtained. As a polishing apparatus for polishing a quartz wafer, a so-called planetary gear carrier having a wafer holding hole for holding one or more quartz wafers, a sun gear (sun gear), and an internal gear (internal gear) is usually used. A planetary gear type double-side polishing apparatus (double-side lapping apparatus) is used (see, for example, Patent Document 2). When a crystal wafer is polished using this planetary gear type double-side polishing apparatus, a carrier holding the crystal wafer in the wafer holding hole is placed between the sun gear at the center of the double-side polishing apparatus and the internal gear at the outer periphery. The carrier is sandwiched between the lower surface plate and the upper surface plate which are arranged in the vertical direction of the carrier on which the crystal wafer is held, so as to press both main surfaces of the crystal wafer. Then, while rotating the lower surface plate and the upper surface plate in a relative direction while supplying polishing slurry (abrasive grains) from above the quartz wafer, the carrier is rotated and revolved by the sun gear and the internal gear, thereby producing the quartz wafer. Polish both main surfaces at the same time.

Japanese Patent Laid-Open No. 9-1544 JP 2006-123020 A

By the way, the oscillation frequency of the crystal vibrating piece is determined by the size of the crystal vibrating piece. When the planar shape is the same, the oscillation frequency depends on the thickness of the crystal vibrating piece. Further, since the cutting angle of the crystal vibrating piece with respect to the crystal axis particularly affects the temperature characteristics of the crystal vibrating piece, it is necessary to strictly control the cutting angle in the manufacturing process of the crystal wafer. The crystal wafer cutting angle is generally determined in the process of cutting out the crystal wafer from the crystal lambard, and in the subsequent polishing process, both sides are polished while maintaining the cutting angle, so the process control for the cutting angle in the crystal wafer cutting process is performed. It is especially important to do.
However, in the process of cutting out the crystal wafer with the wire saw 150 described in Patent Document 1, the attachment displacement of the work attachment jig 151 and the attachment plate 156 and the attachment position of the crystal lambird 1A to the attachment plate 156 are as follows. The cutting angle of the cut crystal wafer is not deviated from the target value due to factors such as deviation in the process such as deviation, wear and deviation of the guide roller 152, or deterioration of the wire saw 150 over time such as elongation of the wire 153. There has been a problem that it may become a non-defective product and the yield may be reduced.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A method of manufacturing a single crystal substrate according to this application example includes a step of polishing the single crystal substrate using at least a planetary gear type double-side polishing apparatus, and cutting at a predetermined cutting angle with respect to the crystal axis. A method of manufacturing a single crystal substrate having a surface, a wafer cutting step of cutting out the single crystal substrate from the single crystal material to aim at the predetermined cutting angle, and an initial polishing step of polishing the single crystal substrate by a predetermined amount; After the initial polishing step, an initial cutting angle measurement step for measuring a cutting angle of the single crystal substrate, and a measurement value of the single crystal substrate measured in the initial cutting angle measurement step is outside an allowable range of a standard value. If there is, a shape capable of correcting the cutting angle within the allowable range of the standard value in the vicinity of any one side of the sides orthogonal to the crystal axis of at least one surface of the single crystal substrate A step forming step of forming a step, after said step forming step, characterized in that it comprises a and a cutting angle correction polishing step of polishing until at least the step a single crystal substrate is removed.

The inventor provides a step having a controlled shape such as thickness and width on at least one surface of a single crystal substrate that is cut from the single crystal material with a predetermined cutting angle with respect to the crystal axis. It has been found that the cutting angle can be shifted by a predetermined amount.
According to the method for manufacturing a single crystal substrate having the above-described structure, data indicating the relationship between the shape of the step provided on the single crystal substrate and the shift amount of the cutting angle before and after polishing the single crystal substrate provided with the step is acquired in advance. In addition, based on this data, the shape of the step that can be corrected to a desired cutting angle is determined, the step is formed on the single crystal substrate, and then the cutting angle correction polishing is performed. As a result, a single crystal substrate whose cutting angle is adjusted with high accuracy can be obtained, and when the cutting angle is outside the allowable range of the standard value in the wafer cutting step, the cutting angle is corrected and the desired cutting is performed. Since a single crystal substrate having an angle cut surface can be obtained, the single crystal substrate can be manufactured with a high yield.

  Application Example 2 In the method for manufacturing a single crystal substrate according to the application example described above, the step is on a virtual center line in the same direction as the crystal axis on the surface of the single crystal substrate where the step is provided. It is provided with line symmetry.

  According to this configuration, when the cutting angle correction polishing is performed on the single crystal substrate provided with the level difference, the balance of the distribution of the polishing pressure generated in the single crystal substrate due to the level difference is maintained until the level difference disappears as the polishing progresses. Be drunk. Thereby, the cutting angle of the single crystal substrate can be adjusted without polishing the polishing angle in the direction orthogonal to the crystal axis of the single crystal substrate at an undesired angle.

  Application Example 3 In the method for manufacturing a single crystal substrate according to the application example, the step is made of a metal film.

  According to this configuration, a step having a shape capable of correcting the difference between the cutting angle measured in the initial cutting angle measuring step and the standard value of the cutting angle can be formed relatively easily and accurately, so that the cost can be reduced. Thus, the cutting angle of the single crystal substrate can be adjusted accurately.

  Application Example 4 In the method for manufacturing a single crystal substrate according to the application example, the step is formed by removing a part of the single crystal substrate.

  According to this configuration, when a step is formed on the single crystal substrate, a material for forming a step other than the single crystal substrate material is not required, and the load applied to the grindstone (table plate) of the polishing apparatus is reduced to the single crystal substrate material. There is no increase with respect to the load for polishing.

  Application Example 5 A method for manufacturing a single crystal substrate according to the application example, wherein the single crystal substrate is made of quartz.

  According to this configuration, a crystal wafer having a finely adjusted cutting angle can be obtained, so that a crystal resonator element having a good frequency temperature characteristic can be manufactured.

  Hereinafter, an embodiment of a method for producing a single crystal substrate will be described with reference to the drawings.

(Crystal wafer)
First, in the process of manufacturing a crystal wafer as a single crystal substrate obtained by the manufacturing method of the present embodiment, a crystal wafer on which a step provided to correct the cutting angle of the crystal wafer to a desired angle will be described. .
FIG. 1 schematically illustrates an aspect of a quartz wafer when performing polishing for cutting angle correction (cutting angle correction polishing) to be described later. The top view seen from the lower surface side which contacts a board | substrate side, (b) is sectional drawing which shows the cut surface of the virtual centerline P1 of (a).

In FIG. 1, a crystal wafer 1 ′ before cutting angle correction polishing is a rectangular flat plate crystal wafer 1 ′ having a cut surface 2a cut at a cutting angle inclined by a predetermined angle with respect to the crystal axis 7 of the quartz crystal. It has the metal film 5 as a level | step difference provided in one surface.
The metal film 5 has a center line P1 in the same direction as the crystal axis in the vicinity of one side determined by the direction of correcting the cutting angle among the sides orthogonal to the crystal axis 7 on one side of the crystal wafer 1 ′. On the other hand, it is formed in the shape of width W1 and thickness T so as to be line symmetrical. The width W1 and the thickness T of the metal film 5 will be described in detail later. The shape of the step (metal film) acquired in advance and the cutting angle before and after polishing a predetermined amount of the crystal wafer 1 ′ provided with the step are described. It is determined based on data indicating the relationship with the shift amount.

(Double-side polishing machine)
Next, a double-side polishing apparatus used for polishing the quartz wafer 1 ′ in the quartz wafer manufacturing method will be described with reference to the drawings.
FIG. 2 is a plan view schematically showing a carrier as a planetary gear in the double-side polishing apparatus. FIG. 3 schematically illustrates a double-side polishing apparatus, (a) is a plan view illustrating a lower surface plate of the polishing apparatus, and (b) is a cross-sectional view taken along line AA in (a) ( It is a fragmentary sectional view explaining including the upper surface plate arrange | positioned at the upper part of a).

  In FIG. 3, a double-side polishing apparatus 50 is a general-purpose double-sided lapping apparatus having a planetary gear mechanism including a sun gear (sun gear) 21, an internal gear (internal gear) 22, and a carrier 10 as a planetary gear. Yes. Further, the double-side polishing apparatus 50 includes an upper surface plate 30 and a lower surface plate 20 that sandwich the carrier 10 holding the crystal wafer 1 ′ from above and below. The upper surface plate 30 is provided with a cylinder (not shown) for applying rotation and polishing load (polishing pressure), and the lower surface plate 20 includes a cylinder for transmitting rotation from the motor and the speed reducer to the lower surface plate and a lower surface plate. Thrust bearings (both not shown) that support the load are installed. Although not shown, the double-side polishing apparatus 50 includes a slurry supply means for supplying polishing slurry (abrasive grains) to the crystal wafer 1 ′ held by the carrier 10, and the thickness of the crystal wafer 1 ′ being polished. And a thickness measuring means for measuring.

  As shown in FIG. 2, the carrier 10 is a plate on a disk having a plurality of wafer holding holes 15 for holding the crystal wafer 1 ′. Although not shown, the carrier 10 has a thickness target by polishing the crystal wafer 1 ′. It is formed with a plate thickness thinner than a quartz wafer obtained by polishing to a value. The carrier 10 of this embodiment is provided with five wafer holding holes 15.

  Returning to FIG. 3, when the quartz wafer 1 ′ is polished by the double-side polishing apparatus 50, the carrier 10 in which the quartz wafer 1 ′ is inserted and held in the wafer holding hole 15 is attached to the sun gear 21 at the center of the double-side polishing apparatus 50 and It is held between the internal gears 22 on the outer periphery. Further, the carrier 10 is sandwiched between the lower surface plate 20 and the upper surface plate 30 arranged in the vertical direction of the carrier 10 so as to press both main surfaces of the crystal wafer 1 ′. The lower surface plate 20 and the upper surface plate 30 are rotated relative to the crystal wafer 1 ′ while supplying polishing slurry from above the crystal wafer 1 ′, and at the same time, the carrier 10 is driven by the sun gear 21 and the internal gear 22. Both main surfaces of the quartz wafer are polished simultaneously by rotating and revolving. The rotation directions of the sun gear 21, the internal gear 22, the lower surface plate 20, and the carrier 10 are indicated by arrows 25 to 28. However, the arrow 28 that is the rotation direction of the carrier 10 may vary depending on the revolution ratio. is there.

(Quartz wafer manufacturing method)
Next, a method for manufacturing a quartz wafer will be described with reference to the drawings, particularly a cutting angle correction polishing method for correcting the cutting angle of the quartz wafer 1 ′.
FIG. 4 is a flowchart for explaining a method of manufacturing a quartz wafer. FIG. 5 is a partial cross-sectional view schematically illustrating a process in which the crystal wafer 1 ′ is polished in the cutting angle correction polishing process in the crystal wafer manufacturing method. In the following description of the method for manufacturing a crystal wafer, refer to FIGS. 1 to 3 for the double-side polishing apparatus 50 including the carrier 10 holding the crystal wafer 1 ′.

  In the method of manufacturing a quartz wafer, first, from a quartz lambard obtained by lambard processing, in which a portion of an artificial quartz crystal is formed into a block shape with a clear crystal axis, a wire saw or a band saw is used to crystal the crystal axis. The crystal wafer 1 ′ is cut out aiming at a desired cutting angle (step S1).

Next, as shown in step S <b> 2, a predetermined number of crystal wafers 1 ′ are set by being inserted and held in the wafer holding holes 15 of the carrier 10.
Next, as shown in step S <b> 3, initial polishing is performed to polish the crystal wafer 1 ′ to a state before the initial cutting angle measurement described later. Here, the state before measuring the initial cutting angle is that the surface of the crystal wafer 1 ′ is uniformly polished by the number of abrasive grains used in the initial polishing and the crystal wafer 1 when the initial cutting angle is measured. When the cutting angle of 'is outside the allowable range of the standard value, it means a state in which a thickness sufficient for cutting angle correction polishing is left.

Next, as shown in step S4, an initial cutting angle measurement is performed to measure the cutting angle of the crystal wafer 1 ′ using an X-ray diffractometer or the like.
When the cutting angle of the crystal wafer 1 ′ is within the allowable range of the standard value by the initial cutting angle measurement (Yes in step S5), it is not necessary to perform cutting angle correction polishing described later, and the process proceeds to step S6.

  When the cutting angle of the crystal wafer 1 ′ is outside the allowable range of the standard value by the initial cutting angle measurement (No in step S5), the cutting angle correction polishing is performed to correct the cutting angle of the crystal wafer 1 ′ to the standard value. Apply. In the cutting angle correction polishing, as shown in FIG. 1, a step made of a metal film 5 is provided on one surface of the crystal wafer 1 ′, and both surfaces are tilted so that the cut surface 2a of the crystal wafer 1 ′ is inclined from the horizontal. The cutting angle with respect to the crystal axis is corrected by polishing.

  In the cutting angle correction polishing, first, the arrangement and shape of the metal film 5 as a step formed on the crystal wafer 1 'are determined (step S8). Depending on whether the cutting angle is increased or decreased with respect to the crystal axis of the crystal wafer 1 ′, the arrangement of the steps formed on the crystal wafer 1 ′ is determined on which side of the two sides in the direction orthogonal to the crystal axis. decide. The shape of the metal film 5 is based on data indicating the relationship between the shape of the step and the shift amount of the cutting angle before and after the cutting angle correction polishing, which is confirmed in advance using a test piece having the same size as the crystal wafer 1 ′. Thus, a step shape that can correct the difference from the standard value of the cutting angle of the quartz crystal wafer 1 ′ measured by the initial cutting angle measurement is determined. In this embodiment, the shape of the step is determined using the width W1 of the metal film 5 shown in FIG. 1A and the thickness T of the metal film 5 shown in FIG. 1B as control factors (step S8).

  Next, as shown in step S9, a metal film 5 is formed on the crystal wafer 1 'as a step having the position and shape determined in step S8 by vapor deposition or sputtering.

  Next, as shown in step S <b> 10, cutting angle correction polishing is performed for polishing a predetermined amount of the crystal wafer 1 ′ on which the step due to the metal film 5 is formed. The predetermined amount to be polished here is determined based on the data indicating the relationship between the shape of the step confirmed in advance and the amount of shift of the cutting angle before and after cutting angle correction polishing, and at least the step formed of the metal film 5 This refers to a polishing amount in which both main surfaces of the crystal wafer 1 ′ are parallel to each other, and a thickness sufficient for final polishing is left from the target thickness of the crystal wafer.

In the cutting angle correction polishing, the crystal wafer 1 ′ on which the metal film 5 is formed is polished in the manner shown in FIG. That is, as shown in FIG. 5A, the crystal wafer 1 ′ at the start of the cutting angle correction polishing is sandwiched between the lower surface plate 20 and the upper surface plate 30 of the double-side polishing apparatus, and the lower surface plate 20 The cut surface 2a is sandwiched between the lower surface plate 20 and the upper surface plate 30 in a state where the cut surface 2a is inclined from the horizontal by the metal film 5 formed on the side surface. 5 (a) to 5 (c) schematically show the state of the crystal wafer 1 'sandwiched between the lower surface plate 20 and the upper surface plate 30, and in actuality, a thin crystal plate is used. A certain crystal wafer 1 ′ is deformed by the polishing pressure of the lower surface plate 20 and the upper surface plate 30 and is sandwiched between the lower surface plate 20 and the upper surface plate 30 with almost no gap.
In this state, the polishing pressure applied to the surfaces of the lower surface plate 20 and the upper surface plate 30 that are in contact with the lower surface plate 20 and the upper surface plate 30 in the process of being polished on both sides by the lower surface plate 20 and the upper surface plate 30 is as follows. The pressure in the vicinity of the portion facing the metal film 5 on the contact surface on the 30 side is particularly high, and the pressure on the side opposite to the side on which the metal film 5 on the contact surface on the lower surface plate 20 is provided is increased. Distribution occurs. As a result, the quartz wafer 1 ′ in the region where the polishing pressure of the quartz wafer 1 ′ is strongly applied is rapidly polished. Further, since the metal film 5 is harder to be polished than quartz, the progress of the polishing of the metal film 5 is slower than that of the quartz wafer 1 ′, as shown in FIG. 5B. The crystal wafer 1 'in the formed region is not polished as long as the metal film 5 remains. As described above, due to the pressure distribution of the polishing pressure generated on the quartz wafer 1 ′ between the lower surface plate 20 and the upper surface plate 30 due to the level difference caused by the metal film 5, and the effect of suppressing the polishing by the metal film 5, the cutting angle correction polishing at the start of polishing is performed. The cut surface 2a of the crystal wafer 1 ′ (see FIG. 5A) is tilted in a predetermined direction as the cutting angle correction polishing proceeds, and is desired with respect to the crystal axis 7 at the end of the cutting angle correction polishing. As a result, the cut surface 2c is inclined at an angle of 1 and a crystal wafer 1 'with the corrected cut angle is obtained (see FIG. 5C).

Returning to FIG. 4, next, as shown in step S <b> 11, the cutting angle of the crystal wafer 1 ′ after the cutting angle correction polishing is measured by an X-ray diffractometer or the like.
When the cutting angle of the crystal wafer 1 ′ is within the allowable range of the standard value (Yes in step S12), the process proceeds to step S6.
If the cutting angle of the crystal wafer 1 ′ is outside the allowable range of the standard value (No in step S12), as shown in step S13, perform a defect process such as applying a defect marking as a defective product, or A treatment such as sorting as a crystal wafer that can be used at the cutting angle is performed.

Next, as shown in step S6, the quartz wafer 1 ′ whose cutting angle is within the allowable range of the standard value is polished to a predetermined surface state and polished to a target thickness value.
Then, the crystal wafer 1 ′ is taken out from the carrier 10 (step S7), and a series of crystal wafer manufacturing processes is completed.

The effects of the above embodiment will be described below.
The inventor performs polishing after providing a step whose thickness and width are controlled in the vicinity of one of the sides orthogonal to the crystal axis of at least one surface of a single crystal substrate such as a quartz wafer. Thus, it has been found that the cutting angle can be shifted by a predetermined amount. Based on this, in the crystal wafer manufacturing method of the above embodiment, the initial cutting is performed on the crystal wafer 1 ′ based on the data indicating the relationship between the step shape and the cutting angle shift amount that are confirmed in advance in the wafer size of the crystal wafer. A metal film 5 was formed as a step that was controlled to have a shape capable of correcting the difference between the angle measurement value and the cut angle standard value. And after performing the cutting angle correction | amendment grinding | polishing for correct | amending the cutting angle of crystal wafer 1 'in which the metal film 5 was formed, it was set as the structure which finish-polishes until it becomes thickness target value.
Thereby, it is possible to manufacture a crystal wafer that is accurately adjusted to a desired cutting angle with a high yield.

Moreover, in the said embodiment, the level | step difference formed on quartz wafer 1 'was set as the structure formed with the metal film 5 which can form metals, such as aluminum, by vapor deposition or sputtering, for example.
As a result, a step having a shape capable of correcting the difference between the measurement value of the initial cutting angle measurement and the standard value of the cutting angle can be formed relatively easily and accurately, so that the accurate cutting angle of the crystal wafer can be adjusted. It becomes possible.

Moreover, in the said embodiment, the level | step difference which consists of the rectangular-shaped metal film 5 by planar view is arrange | positioned so that it may become line symmetrical with respect to the virtual centerline P1 of the same direction as the crystal-axis direction of crystal wafer 1 '. It was set as the structure provided.
Thereby, when the cutting angle correction polishing is performed on the crystal wafer 1 ′ provided with the metal film 5, the balance of the distribution of the polishing pressure generated on the crystal wafer 1 ′ due to the level difference is increased as the polishing progresses. It is kept until it disappears. Therefore, it is possible to correct the cutting angle with respect to the crystal axis of the crystal wafer without polishing the polishing angle in a direction orthogonal to the crystal axis of the crystal wafer at an undesired angle.

  The method for manufacturing a quartz wafer described in the above embodiment can also be implemented as the following modification.

(Modification 1)
In the crystal wafer manufacturing method of the above embodiment, the shape in plan view of the metal film 5 as a step formed on the crystal wafer 1 ′ based on the initial cutting angle measurement result is orthogonal to the crystal axis of the crystal wafer 1 ′. One rectangular shape formed with a width W1 in the vicinity of one side was formed. The shape of the step in plan view is not limited to this, and the distribution of the polishing pressure generated in the crystal wafer by the step when the quartz wafer is subjected to the cutting angle correction polishing can be balanced until the step is eliminated by polishing. The shape may not be rectangular, and a plurality of steps may be formed.
8 and 9 are schematic plan views schematically showing modifications of the shape of the step provided on the quartz wafer in plan view. In addition, about the structure same as the said embodiment among the structures shown in FIG. 8 and FIG. 9, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIG. 8 shows the crystal wafer 1b before cutting angle correction polishing provided with two rectangular steps in plan view. That is, on one surface of the crystal wafer 1b, on one side of the sides orthogonal to the crystal axis direction of the crystal wafer 1b, the metal film 65 is made of, for example, aluminum and has two rectangular steps in plan view. Are arranged so as to be line-symmetric with respect to a virtual center line P2 in the same direction as the crystal axis direction. Each metal film 65 is formed with a width W2 and a thickness (not shown) determined based on the amount of deviation from the standard value of the cutting angle of the crystal wafer 1b, as in the above embodiment.

  FIG. 9 shows a crystal wafer 1c provided with three circular steps in plan view. In the crystal wafer 1c, three metal films 75 made of aluminum or the like and having a circular shape in plan view are provided on one side of the sides orthogonal to the crystal axis direction of the crystal wafer 1c in the same direction as the crystal axis direction. Are arranged so as to be line-symmetric with respect to the center line P3. Each metal film 75 has a diameter R and a thickness (not shown) determined based on the deviation from the standard value of the cutting angle of the crystal wafer 1c, similarly to the crystal wafer 1b of FIG. Is formed.

  According to the above modification, the metal films 65 and 75 as steps provided on the crystal wafers 1b and 1c are in relation to virtual center lines P2 and P3 in the same direction as the crystal axis direction of the crystal wafers 1b and 1c. Since they are arranged so as to be line-symmetric, when the cutting angle correction polishing is performed, the balance of the distribution of the polishing pressure generated on the quartz wafer due to the level difference is reduced until the metal films 65 and 75 disappear as the polishing progresses. Kept. Thus, the metal film 65 capable of correcting the cutting angle while preventing the polishing angle in the direction orthogonal to the crystal axis direction of the crystal wafers 1b and 1c from being inclined to an undesired angle as in the above embodiment. , 75 can be reduced in area, so that the cost can be reduced.

(Modification 2)
In the embodiment and the first modification, the metal films 5, 65, and 75 formed on the quartz wafers 1 ′, 1b, and 1c by vapor deposition or the like are provided as steps. However, the present invention is not limited to this, and a step may be formed by removing a part of the wafer material of the crystal wafer.
FIG. 10 is a cross-sectional view schematically illustrating the crystal wafer 101 provided with a step for correcting the cutting angle by removing a part of the wafer material.

The crystal wafer 101 before cutting angle correction polishing shown in FIG. 10 has a step 105 having a thickness t2 on one side of the sides orthogonal to the crystal axis direction of one main surface. The shape of the step 105 is formed with a thickness t2 and a width W3 determined based on the amount of deviation from the standard value of the cutting angle of the crystal wafer 101, as in the above embodiment and the first modification. The step 105 can be precisely formed by wet etching a region different from the step 105 of the crystal wafer 101 with a hydrofluoric acid solution or by dry etching.
In the present modification in which the step 105 is formed by removing a part of the crystal wafer 101, the crystal wafer 101 is cut out from the crystal lambard in consideration of the removal amount of the crystal wafer 101 that is removed when the step 105 is formed. At this time, the thickness of the crystal wafer 101 is increased during the manufacturing process, such as increasing the thickness of the crystal wafer 101 or reducing the amount of initial polishing to be performed before the initial cutting angle is measured.

  According to the second modification, since the step 105 is formed by etching the crystal wafer 101 itself, no other step forming material other than the crystal wafer 101 is required, and the grindstone (fixed surface) of the double-side polishing apparatus is fixed. The load on the panel is reduced.

(Modification 3)
In the above embodiment and Modifications 1 and 2, the metal film 5, 65, 75 or the step 105 as a step is provided on one main surface of the quartz wafers 1 ′, 1b, 1c, and 101. However, the present invention is not limited to this, and a step may be provided in a region where both main surfaces of the quartz wafer face each other.
FIG. 11 is a cross-sectional view schematically illustrating a crystal wafer 1e in which a metal film as a step is provided in a region where both main surfaces of the crystal wafer are opposed to each other. In addition, about the structure of the workpiece | work shown in FIG. 11, about the same structure as the said embodiment and the modifications 1-3, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The crystal wafer 1e before cutting angle correction polishing shown in FIG. 11 has a metal film 115 as a step in a region where both main surfaces in the vicinity of either one of the sides orthogonal to the crystal axis direction of the crystal wafer 1e face each other. 125 is provided. The metal films 115 and 125 correct the amount of deviation from the standard value of the initial cutting angle of the crystal wafer 1e based on data indicating the relationship between the step shape confirmed in advance and the cutting angle shift after the cutting angle correction polishing. It is formed with a width W4 and thicknesses t3 and t4.

  Even when the metal films 115 and 125 as steps are formed on both surfaces as in the quartz wafer 1e of the above-described modification 3, each step shape and the shift amount of the cutting angle before and after cutting angle correction polishing are confirmed in advance. Thereby, the cutting angle of the crystal wafer 1e can be adjusted to a desired cutting angle.

  Hereinafter, the steps formed on the quartz wafer when performing the cutting angle correction polishing in the quartz wafer manufacturing method of the above embodiment will be described in detail based on examples. In addition, this invention is not limited to these Examples, A various change can be added in the range which does not deviate from the summary.

1. Preparation of crystal wafers As crystal wafers to be subjected to cutting angle correction polishing, they are cut from quartz lambard with a wire saw aiming at a so-called AT cut with a cutting angle of 35 degrees 15 minutes from the crystal axis, and then polished by lapping with lap count # 3000 An AT-cut quartz wafer was prepared. Two types of 8 mm square and 12 mm square plane sizes were prepared for the AT cut crystal wafer.

2. Initial cutting angle measurement The initial cutting angle of the AT-cut quartz wafer prepared in 1 above was measured using an X-ray diffractometer ("High-precision X-ray angle measuring device" manufactured by Rigaku Corporation).

3. Step formation The step formed on the AT-cut quartz wafer whose cutting angle was measured was formed by an aluminum film formed by pure vacuum having a purity of 99.99% (4N) by vacuum deposition.
The steps were formed in the same manner as in FIG. 1 with the following width (W) and thickness (t) on 8 mm square and 12 mm square AT-cut quartz wafers.
In the 8 mm square AT-cut quartz wafer, the step width (W) is 2 levels of 2 mm and 4 mm, and the thickness (t) of 5 levels of 400 nm, 600 nm, 800 nm, 1000 nm, and 1200 nm for each step width. Steps were formed (total of 10 levels).
In a 12 mm square AT-cut quartz wafer, the width (W) of the step is set to two levels of 3 mm and 7 mm, and the thickness (t) of five levels of 400 nm, 600 nm, 800 nm, 1000 nm, and 1200 nm for each step width. Steps were formed (total of 10 levels).
Three samples were prepared for each level of the step shape.

4). Cutting angle correction polishing Each of the AT-cut quartz wafers formed with the steps of the aluminum film having the above-described 10 levels was subjected to double-side polishing using a GC # 3000 abrasive grain by a double-side polishing apparatus. The polishing amount was controlled to 20 μm for both sides.

5). Measurement of cutting angle after cutting angle correction polishing and confirmation of cutting angle shift amount After the above cutting angle correction polishing, the cutting angle of an AT-cut quartz wafer having a 10-level step shape is measured by an X-ray diffractometer (“high-precision X-ray measurement”). Measurement was performed using a corner device (manufactured by Rigaku Corporation), and the shift amount of each cutting angle was calculated in comparison with the initial cutting angle of each AT-cut quartz wafer. FIG. 6 shows the result of confirming the shift amount of the cutting angle of 3 samples for each level of the 8 mm square AT-cut quartz wafer. FIG. 6 shows the result of confirming the shift amount of the cutting angle of 3 samples for each level of the 12 mm square AT-cut quartz wafer. Each is shown in FIG. In the graphs of FIG. 6 and FIG. 7, the amount of shift of the cutting angle for each film thickness (thickness t) of the aluminum film as a step is plotted for all samples, and the cutting angle for each width W of the two-level aluminum film. An approximate curve of the shift amount is shown.

(Evaluation results)
From the results shown in FIGS. 6 and 7, the larger the step width and thickness, the larger the shift amount of the cutting angle after polishing (cutting angle correction polishing), and the error can be kept within an angle of several seconds. I understand that. Therefore, the wafer is cut by providing a step formed by controlling the shape such as thickness (t) and width (W) on the wafer (AT cut quartz wafer) and then polishing (cutting angle correction polishing). It is possible to shift the angle by a desired angle.

  The embodiment of the present invention, its modification, or the example made by the inventor has been specifically described above, but the present invention is limited to the above-described embodiment, its modification, or example. Instead, various changes can be made without departing from the scope of the invention.

  For example, in the above embodiment and the modification, the quartz wafer as the single crystal substrate has been described. However, the present invention is not limited to this, and other single crystal substrates such as silicon wafers used for semiconductor circuit elements (IC chips) can be applied as a method for manufacturing a single crystal substrate capable of correcting the cutting angle with respect to the crystal axis. it can.

(A) is a top view which illustrates typically a quartz wafer, (b) is sectional drawing which shows the cut surface of the centerline P1 of (a). The top view which shows typically the carrier as a planetary gear in a double-side polish apparatus. (A) is a top view which illustrates typically the lower surface plate of a double-side polish apparatus, (b) is the sectional view on the AA line of (a). The flowchart explaining the manufacturing method of a crystal wafer. The fragmentary sectional view which explains typically the process in which a crystal wafer is ground in the cutting angle correction polish process in the manufacturing method of a crystal wafer. The graph which shows the shift amount confirmation result of the cutting angle of an Example. The graph which shows the shift amount confirmation result of the cutting angle of an Example. The top view which illustrates the modification 1 of a crystal wafer typically. The top view which illustrates typically another aspect of the crystal wafer of the modification 1. FIG. Sectional drawing which illustrates the modification 2 of a crystal wafer typically. Sectional drawing which illustrates the modification 3 of a crystal wafer typically. The perspective view explaining a wire saw typically.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ', 1b, 1c, 1c, 101 ... Crystal wafer as a single crystal substrate, 1A ... Crystal lambard, 2a, 2c ... Cut surface, 5, 65, 75, 115, 125 ... Metal film as a level | step difference, 7 ... Crystal Shaft, 10 ... carrier, 15 ... wafer holding hole, 20 ... lower surface plate, 21 ... sun gear, 22 ... internal gear, 30 ... upper surface plate, 50 ... double-side polishing machine, 105 ... step, 150 ... wire saw, 151 ... work Mounting jig, 152 ... guide roller, 153 ... wire, 155 ... mounting base, 156 ... affixing plate.

Claims (5)

A method for producing a single crystal substrate comprising a step of polishing a single crystal substrate using at least a planetary gear type double-side polishing apparatus, and having a cut surface having a predetermined cutting angle with respect to a crystal axis,
A wafer cutting step of cutting out the single crystal substrate from the single crystal material aiming at the predetermined cutting angle;
An initial polishing step for polishing a predetermined amount of the single crystal substrate;
After the initial polishing step, an initial cutting angle measuring step for measuring a cutting angle of the single crystal substrate;
When the measurement value of the single crystal substrate measured in the initial cutting angle measurement step is outside the allowable range of the standard value, any of the sides orthogonal to the crystal axis of at least one surface of the single crystal substrate A step forming step for forming a step having a shape capable of correcting the cutting angle within an allowable range of the standard value in the vicinity of the one side;
After the step forming step, a cutting angle correction polishing step for polishing the single crystal substrate until at least the step is removed;
A method for producing a single crystal substrate, comprising: In the manufacturing method of the single-crystal substrate of Claim 1,
The method for producing a single crystal substrate, wherein the step is provided symmetrically with respect to a virtual center line in the same direction as the crystal axis on the surface of the single crystal substrate where the step is provided. . In the manufacturing method of the single-crystal substrate of Claim 1 or 2,
The method of manufacturing a single crystal substrate, wherein the step is made of a metal film. In the manufacturing method of the single-crystal substrate as described in any one of Claims 1-3,
The method of manufacturing a single crystal substrate, wherein the step is formed by removing a part of the single crystal substrate. In the manufacturing method of the single-crystal substrate as described in any one of Claims 1-4,
The method for manufacturing a single crystal substrate, wherein the single crystal substrate is made of quartz.

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