JP2018121179A - Method for manufacturing piezoelectric oxide wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a piezoelectric oxide wafer, by which the occurrence of an irretrievable case, attributed to wrong discrimination about the surface from the backside of a piezoelectric oxide wafer, can be prevented with further reliability.SOLUTION: A method for manufacturing a piezoelectric oxide wafer according to an embodiment of the present invention comprises: a surface-backside determination step of determining, by a controller, the surface or backside of the piezoelectric oxide wafer depending on the polarization direction of the piezoelectric oxide wafer; and a beveling step of grinding and beveling an outer periphery of the piezoelectric oxide wafer. The surface-backside determination step is executed right before the beveling step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a piezoelectric oxide wafer.

  Since the piezoelectric oxide crystal, lithium tantalate crystal (hereinafter referred to as “LT”) and lithium niobate crystal (hereinafter referred to as “LN”) have piezoelectricity, surface acoustic waves (hereinafter referred to as “LTN”) are used. , “SAW”.) Used as filter material. The demand for SAW filters is great and the market is experiencing explosive growth. In particular, the market size of mobile communication applications represented by mobile phones is large.

  LT and LN are often grown by a pull-up type growth method called CZ method. The grown crystal is delivered to the processing step through an annealing process for removing strain and a poling process (polarization process) for causing polarization. In the processing process, the cylinder is processed into a slightly thicker cylinder than the final product in the cylindrical grinding process, and is often cut into a disk-shaped wafer using a multi-wire saw in the wafer ring process.

  The wafer cut into a disk shape is finished to a product diameter in a beveling process, and the end face is chamfered. Thereafter, the front and back damages are removed by surface polishing in the lapping step to obtain a desired thickness. And it finishes so that the surface may become a mirror surface and a back surface may become a rough surface. The roughening of the back surface is to suppress bulk spurious and can be realized by various methods such as lapping with loose abrasive grains and sand blasting. In many cases, the surface is mirror-finished by mechanochemical polishing using colloidal silica.

  Thereafter, the SAW filter is completed through electrode formation, chip cutting, and packaging by the device manufacturer. Wafers made of LT and LN have a diameter of 3 to 6 inches, and the thickness is about 0.2 to 0.5 mm.

  In the SAW filter, the crystal orientation as well as the crystal quality is one of the important items. In general, in the SAW filter, the main surface of the wafer is parallel to the X axis, and the angle between the axis perpendicular to the main surface of the wafer and the Y axis is in the range of 36 to 50 ° in the case of LT. It is desirable. This angle is generally called a Y-cut, and is expressed as 42 ° RY (Rotation from Y-axis), for example. In the case of LN, 126 to 128 ° RY is desirable. Here, the a axis of the crystal is the X axis, the c axis is the Z axis, and the axis orthogonal to the X axis and the Z axis is the Y axis.

  By the way, these wafers have front and back sides. LT and LN are ferroelectrics, and the grown crystal is composed of a plurality of adjacent regions called domains. These domains form a multipolar state of mutually opposite polarization. This state is not preferable for a SAW filter. Therefore, the crystal is unipolarized by the poling process. Specifically, electrodes are formed above and below a plane perpendicular to the polarization direction (Z-axis direction), heated above the Curie temperature, and gradually cooled with a DC electric field applied. The + Z direction and the -Z direction are determined by the polling process.

  The LT wafer in the range of 36 to 50 ° RY and the LN wafer in the range of 126 to 128 ° RY are wafers that are positioned so as to cross the Z axis. Therefore, there are front and back surfaces based on the polarization direction. The front and back sides based on the polarization direction affect the characteristics of the SAW filter, and should not be mistaken. That is, the desired side of the wafer disk surface must be reliably mirror finished. This is because thousands of SAW filters are produced on the mirror side of one wafer, and mistakes in the front and back lead to enormous loss.

  The problem here is that the wafer cut into a disk shape cannot be discriminated from the front and back, and the operator cannot recognize that the reverse of the front and back has occurred. In the cleaning process of the wafer cut into a disk shape, the wafer is aligned with the wafer carrier. When handling the wafer or returning the wafer to the wafer carrier during the sampling inspection after cleaning, Inversion may occur.

  Therefore, there is a case where a method of preparing a sub-orientation flat in a cylindrical grinding process before cutting into a disk shape is sometimes used. This is because the front and back of the wafer can be determined from the position of the sub-orientation flat with respect to the main orientation flat.

  Orientation flat is an abbreviation for orientation flat and means a linear notch formed on the outer periphery of a wafer. The main orientation flat indicates the propagation direction of SAW (surface acoustic wave), for example. In an LT wafer with a 36 to 50 ° RY orientation and an LN wafer with a 126 to 128 ° RY orientation, a main orientation flat is often produced on a plane perpendicular to the + X axis.

  When the sub-orientation flat is produced in the cylindrical grinding process, the sub-orientation flat is produced so that the dimension (width) of the sub-orientation flat before the beveling process is about 10 mm at the maximum. This is because the machining allowance by beveling is often set to a minimum in consideration of the machining load.

  In the beveling process, a sub-orientation flat may be produced for another purpose. This sub-orientation flat is intended for use by a device manufacturer that actually processes a SAW filter. At the stage where the device manufacturer receives the wafer, the wafer has a mirror surface on the front and a rough surface on the back, so that the front and back can be discriminated visually. Therefore, this sub-orientation flat is used not for judging the front and back but for identifying the variety. For example, if the position of the sub-orientation flat is defined in association with the Y-cut angle, management for each Y-cut angle is facilitated, and it is possible to prevent mistakes in the type of product when making a SAW filter. The width of the sub-orientation flat is often 5 to 10 mm.

  When the sub-orientation flat is made in the beveling process, the position of the sub-orientation flat relative to the main orientation flat is fixed. Therefore, when making the sub-orientation flat in the beveling process, the front and back must be in the desired state. I must. This is because even if a mistake is found after the sub-orientation flat is manufactured, the sub-orientation flat can no longer be re-created, and the wafer becomes a defective product.

  In the beveling process, the outer periphery (end surface) of the wafer is chamfered. Then, a difference is provided in the chamfering amount between the front surface side and the back surface side of the wafer. This is because the SAW filter wafer has a single-sided mechanochemical polishing finish, and the center position in the wafer thickness direction must be shifted toward the back side by the amount of the surface mechanochemical polishing. Specifically, this is because after the surface is mechanochemically polished, that is, in the final state as a wafer for a SAW filter, it is necessary to finish so that the cross section of the wafer end has an even R shape. This R shape plays an important role of suppressing chipping, cracking and the like during machine conveyance in the SAW filter manufacturing process by the device manufacturer. For this reason, the mistake of the front and back of the wafer is irreversible.

JP 2014-224663 A

  As described above, the front and back sides based on the polarization direction are largely related to the characteristics of the SAW filter, and should not be mistaken. This is because thousands of SAW filters are produced from one wafer, and mistakes in the front and back lead to enormous loss. As a countermeasure, there is a method in which a sub-orientation flat is prepared in a cylindrical grinding process before the crystal is cut into a disk shape, and the front and back of the wafer can be discriminated in a subsequent process. However, in reality, even if the sub-orientation flat is manufactured, carelessness of the operator in the cleaning work of the wafer cut into a disk shape, and the human work when returning the wafer to the wafer carrier at the subsequent sampling inspection A mistake has occurred due to a mistake.

  Further, the invention described in Patent Document 1 can be cited as an invention that can directly determine the polarization direction. However, even if the polarization direction is determined, the wafer can be reversed when the wafer is subsequently handled by an operator. There is sex. Then, if the sub-orientation flat is produced and the beveling process is performed with the front and back reversed, the wafer is no longer defective. That is, even if the front and back of the wafer can be determined after the sub-orientation flat has been manufactured or after the beveling process has been performed, the wafer cannot be reproduced as a good product.

  Therefore, an object of the present invention is to provide a method for manufacturing a piezoelectric oxide wafer that can more reliably prevent the occurrence of an irreversible situation caused by a mistake in the front and back of the piezoelectric oxide wafer.

  A method for manufacturing a piezoelectric oxide wafer according to an embodiment of the present invention includes a front / back determination step in which a control device determines the front / back of the piezoelectric oxide wafer determined according to the polarization direction of the piezoelectric oxide wafer; A beveling step of chamfering the outer periphery of the piezoelectric oxide wafer, and the front / back determination step is performed immediately before the beveling step.

  By the above-described means, it is possible to provide a method for manufacturing a piezoelectric oxide wafer that can more reliably prevent the occurrence of an irreversible situation caused by a mistake in the front and back of the piezoelectric oxide wafer.

It is a flowchart of the manufacturing method of a piezoelectric oxide wafer. It is the partial schematic diagram of a wafer manufacturing apparatus. It is a flowchart of the process performed at a front / back determination process. It is a figure which shows the example of a waveform pattern.

  FIG. 1 is a flowchart of a method for manufacturing a piezoelectric oxide wafer (hereinafter referred to as “wafer”) according to an embodiment of the present invention. The wafer includes, for example, an LT wafer in the range of 36 to 50 ° RY, an LN wafer in the range of 126 to 128 ° RY, and the like.

  The manufacturing method of this embodiment mainly includes a crystal growth step S1, an annealing step S2, a poling step S3, a cylindrical grinding step S4, a wafer ring step S5, a front / back determination step S6, a beveling step S7, a lapping step S8, and a back surface roughening. It has a surface forming step S9 and a surface mirror surface forming step S10. In the manufacturing method of the present embodiment, the front / back determination step S6 is performed immediately before the beveling step S7 as the irreversible step. That is, a beveling step S7 as an irreversible step is performed immediately after the front / back determination step S6.

  The irreversible process is a process in which when the wafer is turned upside down, the wafer cannot be a good product even if the wafer is turned upside down. In the beveling step S7 of this embodiment, a sub-orientation flat is formed, and the position of the sub-orientation flat with respect to the main orientation flat is determined. Further, in the beveling step S7 of the present embodiment, the end face of the wafer is chamfered, and a difference in the chamfering amount is provided between the front surface side and the back surface side of the wafer. Therefore, if the beveling step S7 is performed in a state where the front and back sides of the wafer are reversed, even if the subsequent step is performed after the front and back sides are reversed, the wafer can no longer be a good product.

  In the manufacturing method of the present embodiment, the front / back determination step S6 may be performed immediately before at least one of other irreversible steps such as the lapping step S8, the back surface roughening step S9, and the front surface mirroring step S10.

  “The front / back determination step S6 is performed immediately before the irreversible step” means that another step is not performed between the irreversible step and the front / back determination step S6, and that no artificial work is involved. means. The same applies to “an irreversible process is performed immediately after the front / back determination process S6”.

  Further, the front / back determination step S6 may include the front / back determination of the wafer and the automatic transfer to the irreversible step immediately after as an integrated inseparable process. This is to prevent a manual error from occurring after the front / back determination of the wafer is performed.

  “Indivisible processing” is processing that does not allow resumption from the interruption point. For example, if the wafer front / back determination and the automatic transfer to the irreversible process are inseparable, once the inseparable process is interrupted during the automatic transfer, in order to continue the inseparable process, The decision needs to be redone. In other words, the interrupted automatic transfer is not resumed without performing the wafer front / back determination again.

  Next, the details of the front / back determination step S6 and the beveling step S7 will be described with reference to FIG. FIG. 2 is a partial schematic view of a wafer manufacturing apparatus 100 that realizes the above-described manufacturing method. Specifically, FIG. 2A is a top view of the wafer manufacturing apparatus 100, and FIG. 2B is a side view of the wafer manufacturing apparatus 100.

  The wafer manufacturing apparatus 100 mainly includes a transfer unit 5, a force applying mechanism 20, a chamfering grinding apparatus 50, a computer 60, an oscilloscope 70, and the like.

  The transfer unit 5 includes a stage 5a that supports the wafer W, an adsorption mechanism 5b that vacuum-adsorbs the wafer W, a linear motor 5c, a linear motor guide 5d, and the like.

  The suction mechanism 5b of the transport unit 5 is moved in the horizontal direction by the linear motor 5c along the linear motor guide 5d as indicated by an arrow AR1 in FIG. Specifically, the suction mechanism 5b includes a vacuum suction arm 5b1, an air cylinder 5b2, and a vacuum suction arm shaft 5b3.

  The conveyance unit 5 moves the suction mechanism 5b to the wafer cassette by the linear motor 5c. The suction mechanism 5b sucks only one wafer W in the wafer cassette. Specifically, the transport unit 5 drives the air cylinder 5b2 to extend the vacuum suction arm shaft 5b3 downward, and the vacuum suction arm 5b1 attached to the tip of the vacuum suction arm shaft 5b3 causes the wafer W in the wafer cassette. Adsorb only one sheet. Then, after the air cylinder 5b2 is driven to retract the vacuum suction arm shaft 5b3 upward, the suction mechanism 5b is moved to the stage 5a by the linear motor 5c. Thereafter, the suction mechanism 5b places the wafer W that has been sucked on the stage 5a. Specifically, the transfer unit 5 extends the vacuum suction arm shaft 5b3 downward as shown by the dotted line in FIG. 2B, and places the wafer W that has been sucked by the vacuum suction arm 5b1 on the stage 5a. Then, the vacuum suction by the vacuum suction arm 5b1 is released. The wafer W may be centered by a centering mechanism such as a mechanical clamp or a laser micrometer.

  Thereafter, the front / back determination step S6 is performed. In the front / back determination step S6, the front / back of the wafer W is determined by evaluating the waveform pattern of the voltage due to the piezoelectric effect of the wafer W. An oscilloscope 70 as a waveform measuring instrument is used for recording the waveform pattern, and a computer 60 as a control device is used for evaluating the waveform pattern. The computer 60 is connected to a display 60a that can display the evaluation result. The probe of the oscilloscope 70 is caused to collide with the upper surface of the wafer W by the force applying mechanism 20 in order to generate a voltage due to the piezoelectric effect. The force imparting mechanism 20 may be configured with an air cylinder as a main component, for example, similarly to the suction mechanism 5b. Specifically, the probe of the oscilloscope 70 is attached to a probe shaft that an air cylinder expands and contracts, and is configured to contact the upper surface of the wafer W when the probe shaft extends. Further, the probe of the oscilloscope 70 may be struck to the upper surface of the wafer W by natural fall after being pulled up to a predetermined height from the upper surface of the wafer W by an air cylinder or the like. The probe of the oscilloscope 70 may be attached to the probe shaft via a spring or the like. This is to prevent an excessive shock from being applied to the wafer W.

  When the probe of the oscilloscope 70 is applied to the wafer W, a voltage due to the piezoelectric effect is generated. The voltage due to the piezoelectric effect is detected through the probe of the oscilloscope 70 in contact with the wafer W. The voltage variation due to the piezoelectric effect only lasts for a short time on the order of microseconds. Further, if the contact time between the probe and the wafer W is long, there is a risk that extra noise will be picked up. Therefore, the contact time between the probe and the wafer W is preferably configured to be several tens of microseconds to several hundred milliseconds. However, the probe of the oscilloscope 70 may be brought into contact with the wafer W before the voltage due to the piezoelectric effect is generated. In this case, another insulator is configured to be applied to the wafer W.

  Alternatively, in order to generate a voltage due to the piezoelectric effect, a mechanism for applying vibration to the periphery of the wafer W using a piezo element, such as the crystal polarity determination device of Patent Document 1, may be used. Any other mechanism for providing may be utilized. Note that the force applying mechanism 20 may be configured to move together with the suction mechanism 5b. This is because the front / back determination step S6 can be executed at a place other than the place where the stage 5a is installed.

  In the present embodiment, the wafer W is hit by the probe of the oscilloscope 70 on the stage 5a. The probe is driven so as to lightly hit the wafer W by the force applying mechanism 20. The waveform of the voltage due to the piezoelectric effect of the wafer W at the time of impact is recorded by the oscilloscope 70. The oscilloscope 70 is connected to the computer 60 via a coaxial analog cable. For example, the coaxial analog cable may be in a floating state. The computer 60 automatically evaluates the waveform of the voltage due to the piezoelectric effect of the wafer W to determine the front and back of the disk surface of the wafer W, and displays the determination result on the display 60a. For example, the computer 60 determines whether the front and back arrangement of the wafer W is a desired front and back arrangement. The desired front and back arrangement refers to the case where the upper surface of the wafer W placed on the stage 5a is the front surface, for example. The case where the upper surface of the wafer W placed on the stage 5a is the back surface may be a desired front and back arrangement.

  In the present embodiment, if the computer 60 determines that the front / back arrangement of the wafer W is not the desired front / back arrangement, that is, if it is determined that the front / back is wrong, it outputs an alarm to that effect. Specifically, this is displayed on the display 60a and the display 70a. An alarm sound may be sounded. Further, a program for urging the wafer reversing operation may be executed. For example, the operator may be notified to invert the wafer W on the stage 5a. For the inverted wafer W, the front / back determination step S6 is performed again. Further, the wafer W may be automatically reversed.

  Here, an example of a specific process executed in the front / back determination step S6 will be described with reference to FIG. FIG. 3 is a flowchart showing an example of specific processing executed in the front / back determination step S6. The computer 60 repeatedly executes this process every time the wafer W is positioned on the stage 5a.

  First, the computer 60 determines whether or not the front and back arrangement of the wafer W is a desired front and back arrangement (step S11).

  The front and back of the wafer W is determined by comparing, for example, a waveform pattern to be evaluated with a reference pattern. The reference pattern is a desired waveform pattern of a voltage due to the piezoelectric effect of the wafer W, and is registered in advance in the computer 60.

  The reference pattern is, for example, a waveform pattern of a voltage sampled when a raw ingot crystal immediately after the polling process is hit with a probe of the oscilloscope 70.

  Here, the waveform pattern will be described with reference to FIG. FIG. 4 shows an example of the temporal transition (waveform pattern) of the voltage due to the piezoelectric effect of the wafer W, which is displayed on the display 70 a of the oscilloscope 70. Specifically, FIG. 4A shows a waveform pattern when the upper surface of the wafer W placed on the stage 5a is the front surface, and FIG. 4B shows a waveform pattern when the upper surface is the back surface. Time t1 indicates the time at which the top surface of the wafer W was hit by the probe of the oscilloscope 70.

  As shown in FIG. 4, the waveform pattern when the upper surface of the wafer W is the front surface is inverted upside down with respect to the waveform pattern when the upper surface is the back surface. The computer 60 can determine the front and back of the wafer W using this characteristic.

  In general, the front and back surfaces of the wafer W are generally in the + Z direction. Therefore, as shown in FIG. 4A, the surface where a negative voltage is generated at the moment of impact by the probe is often used as the surface. However, as shown in FIG. 4B, a surface where a positive voltage is generated at the moment of impact by the probe may be used as the surface.

  The front and back surfaces of the wafer W are compared with the reference phase difference registered in advance and the phase difference between the waveform of the vibration caused by the piezo element and the waveform of the voltage generated according to the vibration, as in the crystal polarity determination device of Patent Document 1. It may be determined based on.

  If it is determined that the front / back arrangement of the wafer W is the desired front / back arrangement (YES in step S11), the computer 60 automatically transfers the wafer W to the chamfering grinding apparatus 50 (step ST12). For example, when the computer 60 determines that the upper surface of the wafer W placed on the stage 5a is the front surface, the computer 60 determines that the front and back arrangement of the wafer W is a desired front and back arrangement. The computer 60 outputs a control signal to the transfer unit 5 to operate the suction mechanism 5b and the linear motor 5c, and the wafer W is installed in the chamfering grinding chamber 55 through the insertion port 51 of the chamfering grinding device 50. It is positioned on the grinding chuck stage 30a.

  On the other hand, if it is determined that the front / back arrangement of the wafer W is not the desired front / back arrangement (NO in step S11), the computer 60 warns the front / back mistake (step S13). For example, when the computer 60 determines that the upper surface of the wafer W placed on the stage 5a is the back surface, or cannot determine whether the upper surface is the front surface or the back surface, the front and back arrangement of the wafer W is determined. It is determined that the desired front / back arrangement is not achieved. Then, the computer 60 displays a text message on the display 60a informing that a front / back error of the wafer W has occurred. Further, the computer 60 may output an alarm sound from a speaker.

  Thereafter, the computer 60 inverts the wafer W (step S14). For example, the computer 60 operates a reversing mechanism (not shown) mounted on the transfer unit 5 to automatically reverse the wafer W up and down. This is to correct the mistakes. The reversing mechanism may be a mechanism using vacuum suction or a mechanism using a clamp. The computer 60 may prompt the operator to manually reverse the wafer W.

  Thereafter, the computer 60 redoes the processing after step S11. For example, when the wafer W is automatically reversed by the reversing mechanism, the computer 60 automatically restarts the processes after Step S11. Alternatively, when the worker manually flips the wafer W up and down, the computer 60 may resume the processing from step S11 onward according to the operator's input operation such as pressing the resume button.

  In this way, the computer 60 can reliably prevent the beveling step S7 from being performed while the front and back of the wafer W are reversed. In addition, it is possible to more surely prevent the occurrence of an irreparable situation caused by a mistake in the front and back of the wafer W.

  The evaluation of the voltage waveform pattern and the front / back determination of the wafer W by the computer 60 may be omitted. This is because the evaluation of the voltage waveform pattern and the front / back determination of the wafer W may be performed by an oscilloscope 70 as a control device. In this case, the determination result may be automatically displayed on the display 70a of the oscilloscope 70. The display 70a may be manually operated so as to display the determination result.

  Thereafter, the beveling step S7 is performed. For example, the computer 60 determines whether or not the front and back arrangement of the wafer W is a desired front and back arrangement. If the computer 60 determines that the front and back arrangement is a desired front and back arrangement, for example, the front and back arrangement of the wafer W is also desired in the beveling step S7. The wafer W is automatically transferred to the chamfering grinding apparatus 50 as indicated by a solid arrow AR2 in FIG.

  Specifically, the transport unit 5 drives the air cylinder 5b2 to extend the vacuum suction arm shaft 5b3 downward, and sucks the wafer W on the stage 5a with the vacuum suction arm 5b1. Then, after the air cylinder 5b2 is driven to retract the vacuum suction arm shaft 5b3 upward, the suction mechanism 5b is moved to the chamfering grinding device 50 by the linear motor 5c. Thereafter, the suction mechanism 5 b puts the sucked wafer W into the chamfering grinding chamber 55 through the insertion port 51 of the chamfering grinding device 50. Specifically, the transfer unit 5 extends the vacuum suction arm shaft 5b3 downward, and positions the wafer W that has been sucked by the vacuum suction arm 5b1 on the grinding chuck stage 30a. Then, the vacuum suction by the vacuum suction arm 5b1 is released.

  The chamfering grinding apparatus 50 includes a chuck unit 30 that holds the wafer W when the wafer W is beveled, and a grindstone unit 40 that grinds the wafer W. The chuck part 30 and the grindstone part 40 are installed in a chamfering grinding chamber 55.

  The chuck unit 30 includes a grinding chuck stage 30a, a grinding chuck stage spindle 30b, a spindle motor 30c, a linear motor 30d, and a linear motor guide 30e.

  The grinding chuck stage 30a holds the wafer W by vacuum suction. The grinding chuck stage 30a is connected to a spindle motor 30c via a grinding chuck stage spindle 30b. The spindle motor 30c rotates around the vertical axis. The number of rotations is, for example, about 1 to 10 RPM.

  The grinding chuck stage 30a is moved in the horizontal direction as indicated by an arrow AR3 along the linear motor guide 30e by the linear motor 30d.

  The wafer W held by vacuum chucking on the grinding chuck stage 30a is moved in the horizontal direction together with the grinding chuck stage 30a and comes into contact with the grindstone unit 40.

  The grindstone unit 40 includes a diamond grindstone 40a, a grindstone spindle 40b, and a spindle motor 40c.

  The diamond grindstone 40a is connected to a spindle motor 40c via a grindstone spindle 40b, and is rotated at a high speed to obtain a grinding force. The spindle motor 40c rotates around the vertical axis. The peripheral speed of the diamond grindstone 40a is, for example, about 400 to 1200 meters per minute in the case of a wafer made of 4 to 6 inches of lithium tantalate crystal.

  The diamond grindstone 40a has a desired round-shaped grindstone cross section, and the wafer W can be chamfered simultaneously with the beveling process. The chamfering grinding device 50 performs beveling while spraying the coolant 57 from the coolant nozzle 56. In order to fabricate the sub-orientation flat in the beveling step S7 or to perform the beveling process of the main / orientation flat, the horizontal position of the wafer W and the horizontal movement distance via the linear motor guide 30e are determined. What is necessary is just to adjust finely for every rotation angle of W. The wafer W is finished to a desired diameter by the beveling process.

  When the beveling process is completed, the transfer unit 5 automatically transfers the wafer W from the chamfering grinding process chamber 55 to the post-grinding stage 58 through the insertion port 51 as indicated by a solid arrow AR4 in FIG.

  With the above-described configuration, the method for manufacturing a piezoelectric oxide wafer according to the embodiment of the present invention can more reliably prevent the occurrence of an irreversible situation due to a front / back error of the piezoelectric oxide wafer.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to the above specific embodiment, In the range of the summary of this invention described in the claim Various modifications and changes are possible.

  For example, the wafer manufacturing apparatus 100 may be automatically operated by a cassette-to-cassette using a plurality of wafer cassettes that can store 25 wafers. In this case, the wafer manufacturing apparatus 100 includes a robot that takes out the wafer W from the wafer cassette and moves it onto the stage 5a, a robot that moves the wafer W from the stage 5a to the grinding chuck stage 30a, and a wafer chuck after the beveling process. A robot that moves from 30a to the stage 58 after grinding, a robot that returns the wafer W after the beveling process from the stage 58 to the wafer cassette after grinding, and a robot that replaces the wafer cassette may be provided.

In the above-described embodiment, the front / back determination step S6 includes the front / back determination of the wafer and the automatic conveyance to the beveling step S7 immediately after that as an integrated inseparable process. This is to prevent a manual error from occurring after the front / back determination of the wafer is performed. For example, when the automatic transfer to the beveling step S7 is interrupted by the operation of a pause button or the like, even if it is already determined that the front / back arrangement of the wafer is the desired front / back arrangement, the subsequent automatic transfer Resumption may be prohibited. In this case, the front / back determination of the wafer is performed again. The same applies to the case where the wafer that has been sucked by the vacuum suction arm 5b1 is removed during the automatic transfer by the operation of the suction release button or the like.

Using the wafer manufacturing apparatus 100 according to the above-described embodiment, 10,000 42 ° RY 4-inch LT wafers were manufactured. As a result, five wafers were determined to be front / back wrong in the front / back judgment step S6 immediately before the beveling step S7, and the incidence of front / back mistakes was 0.05%. Note that the five wafers determined to be front / back mistakes were turned over and then entered again in the front / back determination step S6, and finally shipped as non-defective products.

Comparative example

When the wafer manufacturing apparatus 100 according to the above-described embodiment is not used, that is, when the front / back determination step S6 is not performed immediately before the beveling step S7, the occurrence rate of the front / back mistake immediately after the beveling step S7, that is, a disc It is known that the occurrence rate of front and back mistakes due to a handling error of a wafer after being cut into a shape is about 0.05%. However, for example, when a newcomer or an inexperienced operator is in charge of the cleaning process, the occurrence rate may increase. Further, for example, an incorrect installation direction of the wafer carrier may cause a large number of defective products. The method for manufacturing a piezoelectric oxide wafer according to the present embodiment is not affected by these factors, and ensures that a wafer having no front and back is manufactured.

  DESCRIPTION OF SYMBOLS 5 ... Transfer part 5a ... Stage 5b ... Adsorption mechanism 5b1 ... Vacuum adsorption arm 5b2 ... Air cylinder 5b3 ... Vacuum adsorption arm shaft 5c ... Linear motor 5d ... Linear motor Guide 20 ... Force applying mechanism 30 ... Chuck 30a ... Grinding chuck stage 30b ... Grinding chuck stage spindle 30c ... Spindle motor 30d ... Linear motor 30e ... Linear motor guide 40 ..Wheel part 40a ..Diamond wheel 40b... Grinding wheel spindle 40c... Spindle motor 50... Chamfering grinding device 51 .. Chamfering port 55 .. Chamfering grinding chamber 56. ..Coolant 58 ... Stage after grinding 60 ... Computer 60a ··· display 70 ... oscilloscope 70a ··· display 100 ... wafer manufacturing equipment W ··· wafer

Claims (9)

A method for manufacturing a piezoelectric oxide wafer, comprising:
A front / back determination step in which a controller determines the front / back of the piezoelectric oxide wafer determined according to the polarization direction of the piezoelectric oxide wafer;
A beveling step of chamfering and grinding the outer periphery of the piezoelectric oxide wafer,
The front and back determination step is executed immediately before the beveling step.
Production method. The piezoelectric oxide wafer is made of piezoelectric oxide crystals;
The manufacturing method according to claim 1. The oxide crystal is a lithium tantalate crystal having a 36 to 50 ° RY orientation or a lithium niobate crystal having a 126 to 128 ° RY orientation.
The manufacturing method according to claim 2. In the front / back determination step, the control device determines the front / back of the piezoelectric oxide wafer by evaluating a waveform pattern of a voltage generated by the piezoelectric effect of the piezoelectric oxide wafer.
The manufacturing method according to claim 1. In the front / back determination step, the control device causes the force from the piezoelectric element to act on the piezoelectric oxide wafer, or brings the probe of the waveform measuring instrument into contact with the surface of the piezoelectric oxide wafer, Generate voltage due to the piezoelectric effect of the piezoelectric oxide wafer,
The manufacturing method according to claim 4. A method for manufacturing a piezoelectric oxide wafer, comprising:
A front / back determination step in which a controller determines the front / back of the piezoelectric oxide wafer determined according to the polarization direction of the piezoelectric oxide wafer;
When performed in a state where the front and back of the piezoelectric oxide wafer is reversed, an irreversible process that brings about a situation where the piezoelectric oxide wafer cannot be a good product even if the front and back are reversed thereafter,
The front / back determination step is executed immediately before the irreversible step,
Production method. In the front / back determination step, the control device determines whether the front / back arrangement of the piezoelectric oxide wafer is a desired front / back arrangement, and determines that the desired front / back arrangement is a desired front / back arrangement, The piezoelectric oxide wafer is automatically transferred to the irreversible process immediately after the piezoelectric oxide wafer so that the front and back arrangement of the piezoelectric oxide wafer is a desired front and back arrangement.
The manufacturing method according to claim 6. In the front / back determination step, the control device determines whether the front / back arrangement of the piezoelectric oxide wafer is a desired front / back arrangement, and when determining that the piezoelectric oxide wafer is not a desired front / back arrangement, the piezoelectric oxide wafer Automatically reversing the front and back of the piezoelectric oxide wafer, re-determine the front and back of the piezoelectric oxide wafer,
The manufacturing method according to claim 6. The front and back determination step is executed immediately before each of the plurality of irreversible steps.
The manufacturing method in any one of Claims 6 thru | or 8.

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