Antimonide crystal multi-wire cutting method

Abstract

An antimonide crystal multi-line cutting method relates to the technical field of semiconductor material preparation, and comprises the following steps: providing an antimonide crystal of which one end is subjected to set crystal orientation, and placing the antimonide crystal in a preset graphite support; transferring to a preset positioning table for positioning; filling the gap and curing; integrally fixing the cured antimonide crystal and the graphite support on a reference table board of a cutting machine; based on a laser displacement sensor preset on a vertical datum plane of the cutting equipment, a sensor cursor is aligned with the end face where crystal orientation is completed; adjusting a reference table surface to enable a sensor cursor to respectively move along the X and Y directions on the end surface which finishes crystal orientation, and respectively adjusting the angles of the rotary table in the X and Y directions to enable the numerical value change of the laser displacement sensor not to be greater than a set threshold value; graphite baffles are adhered to two ends of the graphite support to form a groove body structure with two closed ends; and carrying out multi-wire cutting to obtain the antimonide wafer. According to the invention, the fragment rate of multi-wire cutting and the crystal orientation deviation of the wafer are reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material preparation technology, and in particular to a method for multi-wire cutting of antimony compound crystals. Background Technology

[0002] Antimonide crystals (such as indium antimonide and gallium antimonide) are widely used materials in the field of infrared detectors. In the process of preparing infrared detection components, the first step is to prepare antimonide wafer materials to obtain antimonide wafers with specific crystal orientations. One important process is multi-wire dicing of antimonide crystals (single-wire dicing is difficult to achieve while maintaining dicing efficiency).

[0003] The multi-wire cutting process is as follows: Before multi-wire slicing, the crystal is first bonded to a tray with a high-strength adhesive. After it has fully cured, the required reference surface is cut out by internal circle cutting / single-wire cutting. Then, the carrier is fixed on the "wire mesh" for multi-wire cutting.

[0004] Because antimony compound crystals have irregular shapes, the bonding surface between the crystal and the support plate is not stable and consistent. In addition, the crystal rod is subjected to huge frictional thrust generated by the high-speed cutting wire. The soft and brittle antimony compound wafer, which is only 1 / 5 the hardness of silicon, is prone to breakage, displacement, or even detachment. Traditional fixing methods often use adhesives such as paraffin wax and rosin to bond the crystal to the support plate. However, this method cannot guarantee the final crystal orientation accuracy when bonding crystals with different shapes. Due to the influence of the initial bonding accuracy and the change in the relative position of the carrier and the wire mesh, poor crystal orientation accuracy will occur. Furthermore, the irregular shape of the crystal and the weak bonding or the curing characteristics of the adhesive will also cause crystal orientation deviation. In multi-wire cutting equipment, secondary alignment cannot be achieved, resulting in large crystal orientation deviation of the cut wafer. Moreover, fragmentation and flying wafers are very likely to occur in multi-wire cutting.

[0005] To reduce the sharding rate while maintaining low wafer orientation deviation, existing technologies include: Patent application CN103522432A proposes a silicon block cutting method and cutting device, which discloses a rigid plate bonding device to reduce the proportion of microcracks, cracks and notches at the silicon wafer entry point during silicon block cutting, improve the cutting yield, and reduce the silicon wafer TTV. Although this patent reduces the shaking of the steel wire and improves the flow of slurry by using two rigid plates, when cutting antimony compound soft materials with diamond wire, the large difference in hardness between the rigid plate and the crystal will cause a large difference in the amount of material removed, which will aggravate the local wire shaking.

[0006] Patent application CN115383921A proposes a method for cutting, orienting, and segmenting large-size antimonybide crystal materials. It discloses a specially designed graphite holder suitable for large-size irregular antimonybide crystals and achieves segmentation of large-size antimonybide crystals by moving an X-ray orienting instrument and a cutting platform. However, this method is only suitable for single-piece cutting or segmentation of antimonybide crystals. The adjustment method is highly subjective, has poor repeatability, and cannot guarantee the yield rate of multi-wire cutting and the accuracy of secondary orientation. Summary of the Invention

[0007] This invention provides a multi-wire cutting method for antimony compound crystals, which solves the problems of reducing the fragmentation rate and crystal orientation deviation of wafers in multi-wire cutting.

[0008] To achieve the above objectives, this application adopts the following technical solution: A method for multi-wire cutting of antimony compound crystals is provided, comprising: Provide an antimony crystal with one end already oriented and place it in a pre-set graphite holder; The graphite support is configured as a long, narrow groove structure with open ends along its length. Place the graphite holder containing the antimony crystal on the pre-set positioning stage; The positioning platform includes two mutually perpendicular surfaces; The graphite support is placed on one of the mesa surfaces, such that the end face of the antimony crystal with its crystal orientation completed abuts against the other mesa surface; The gaps between the antimony compound crystals and the graphite substrate were filled with a two-component epoxy resin adhesive, which was then cured. The solidified antimony crystal and graphite support are fixed together on the reference table of the cutting machine; based on the laser displacement sensor pre-placed on the vertical reference surface of the cutting equipment, the sensor cursor is aligned with the end face that has completed crystal orientation. Among them, an X and Y direction turntable is pre-positioned below the reference platform; Perform the first calibration operation: adjust the reference stage so that the sensor cursor moves along the Y direction on the end face that has completed crystal orientation, and adjust the angle of the Y-direction turntable so that the value change of the laser displacement sensor does not exceed the set threshold. Perform the second calibration operation: adjust the reference stage so that the sensor cursor moves along the X direction on the end face that has completed crystal orientation, and adjust the angle of the X-direction turntable so that the value change of the laser displacement sensor does not exceed the set threshold. Graphite baffles are bonded to both ends of the graphite holder to form a groove structure with both ends closed. Set the cutting machine parameters to perform multi-wire cutting to obtain antimony bromide wafers.

[0009] Furthermore, the height of the inner side of the graphite support groove must be greater than the maximum height of the cross-section of the antimony crystal to be placed.

[0010] Furthermore, the filler height is not less than the maximum height of the antimony crystal cross-section.

[0011] Furthermore, the set threshold is 3μm.

[0012] Furthermore, the countertop is a stainless steel countertop, and the levelness of the countertop is less than 0.05°. Attached Figure Description

[0013] Figure 1 A schematic flowchart illustrating a method for multi-wire cutting of antimony compound crystals provided in this application embodiment; Figure 2 A schematic cross-sectional view of an antimony crystal after solidification in a graphite substrate, provided in an embodiment of this application; Figure 3 A schematic diagram of an antimony crystal on a positioning stage provided in an embodiment of this application; Figure 4 This is a schematic diagram of a multi-wire cutting process for an antimony crystal provided in an embodiment of this application. Detailed Implementation

[0014] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions in the embodiments of this application are clearly described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application.

[0015] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0016] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily strictly executed according to the step numbers; the execution order of the method steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0017] This specification provides a method for multi-wire cutting of antimony compound crystals, which will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0018] Please see Figure 1-4 This application provides a method for multi-wire cutting of antimony compound crystals, such as... Figure 1-4 As shown, it includes: Step S1: Provide an antimony crystal with one end (denoted as end A) already oriented and place it in a pre-set graphite holder; The graphite support is configured as a long, narrow groove structure with open ends along its length.

[0019] The graphite support is a long, narrow groove structure without sidewalls at both ends; that is, its top and both ends are open. Furthermore, the height of the inner side of the groove must be greater than the maximum height of the cross-section of the antimony crystal to be placed.

[0020] Step S2: Place the graphite holder containing the antimony crystals onto the pre-set positioning stage; The positioning platform includes two mutually perpendicular surfaces; The graphite support is placed on one of the mesa surfaces, such that the end face (A end) of the antimony crystal with its crystal orientation completed abuts against the other mesa surface.

[0021] Step S3: Fill the gaps between the antimony compound crystal and the graphite substrate with a two-component epoxy resin adhesive and then cure it.

[0022] Wherein, the filler height is not less than the maximum height of the antimony crystal cross-section, such as Figure 3 As shown.

[0023] Step S4: Fix the cured antimony crystal and graphite support as a whole onto the reference table of the cutting machine; based on the laser displacement sensor pre-placed on the vertical reference surface of the cutting equipment, align the sensor cursor with the end face (end A) that has completed crystal orientation. The reference platform is pre-positioned with X and Y direction turntables below it.

[0024] Step S5: Perform the first calibration operation: Adjust the reference stage to move the sensor cursor along the Y direction on the end face (end A) that has completed crystal orientation, and adjust the angle of the Y-direction turntable to ensure that the value change of the laser displacement sensor does not exceed the set threshold.

[0025] Step S6: Perform the second calibration operation: Adjust the reference stage to move the sensor cursor along the X direction on the end face (end A) that has completed crystal orientation, and adjust the angle of the X-direction turntable to ensure that the value change of the laser displacement sensor does not exceed the set threshold.

[0026] Step S7: Graphite baffles are bonded to both ends of the graphite holder to form a groove structure with both ends closed.

[0027] Step S8: Set the cutting machine parameters to perform multi-wire cutting to obtain antimony bromide wafers.

[0028] In this embodiment, an antimony crystal, oriented at one end (denoted as end A) according to a specific crystal orientation, is fixed onto a specially designed graphite support. The graphite support is placed on a level platform, with end A resting against a plane completely perpendicular to the level platform. This method ensures the perpendicularity of end A to the bottom surface during cutting. A two-component epoxy resin is used to fill the gap between the crystal and the graphite support, and then cured. The cured crystal and graphite support are then fixed to the reference platform of the cutting machine. Orientation of the multi-wire cutting reference platform is achieved using a non-contact displacement measuring tool (laser displacement sensor). A precision protection device is located below the reference platform. The X and Y direction turntables, with a certain adjustable range, have lifting and left-right swing functions. They are used to adjust the angle of the graphite support relative to the cutting wire mesh and to obtain the parallelism of the X and Y directions of end A with the vertical plane of the equipment. The X and Y direction turntables achieve high-precision alignment of the crystal, thereby ensuring the accuracy of the crystal orientation of the wafer after multi-wire cutting. The front and rear ends of the crystal are bonded with graphite baffles to reduce the vibration and breakage of the wafer during the cutting process. In particular, the middle and later stages of the cutting process are prone to shearing and breakage of the wafer due to excessive friction of the cutting wires. After flying out, the wafer may jump or break, ultimately leading to wafer fragments and flying wafers.

[0029] The above method can effectively improve the bonding stability of irregularly shaped antimonide crystals, reduce the fragmentation rate during multi-wire cutting, and effectively ensure the orientation accuracy of the crystals. The crystal orientation deviation of the cut wafers is less than or equal to 0.2°, which provides a strong guarantee for improving material utilization, reducing production costs, and ensuring the quality of subsequent applications of the materials.

[0030] For example, in the specific implementation process: An antimony crystal, oriented at its A-end using an internal circular cut / single-wire cutter and an orientation instrument, is fixed onto a specially designed graphite support. The side height of the graphite support is at least 1 cm greater than the maximum height of the crystal. Figure 2 As shown; The positioning platform is configured with a stainless steel tabletop. The graphite holder is placed on the stainless steel tabletop with a horizontality of less than 0.05°, and end A is placed against a stainless steel plane that is completely perpendicular to the horizontal stainless steel tabletop. Two-component epoxy resin is used to fill the gap between the crystal and the graphite support. The filling height is greater than or equal to the maximum height of the crystal, and then cured, as shown in Appendix 3. With the help of a precise reference plane and vertical plane, the orientation reference of the crystal can be locked in the correct position, avoiding the reference offset problem caused by stress or flow of traditional adhesives, and realizing reference stability throughout the entire process from fixing to cutting. The solidified crystal and graphite support are fixed onto the reference table of the cutting machine. Below the reference table is an X and Y direction turntable with an adjustment accuracy of 0.1° and an adjustment angle of ±5°, which is used to adjust the angle of the graphite support relative to the cutting wire mesh. A laser displacement sensor is used, which is fixed to the vertical surface of the cutting equipment using a magnetic clamp, as shown in the attached figure. Figure 4 As shown, when the sensor cursor is aligned with end A, the sensor displays the value d. Perform operation 1: Move the reference platform up and down, and move the cursor in the Y direction at end A. Adjust the turntable angle in the Y direction of the reference platform so that the sensor value changes by |∆dy|≤3μm. Perform operation 2: Move the cursor in the X direction at end A by swinging the reference platform left and right. Adjust the turntable angle in the X direction of the reference platform to make the sensor value change |∆dx|≤3μm. Repeat steps one and two to ensure the parallelism of the X and Y directions of end A with the vertical plane of the equipment, thereby achieving high-precision crystal orientation; ensure that the crystal orientation on the cutting machine is consistent with the initial orientation reference height; After the orientation of the multi-wire cutting reference platform is completed, graphite baffles are used to bond the front and rear ends of the crystal; thus, the crystal-colloid-graphite support form a stable composite that can effectively resist mechanical vibration and slurry erosion during the multi-wire cutting process, and prevent crystal micro-movement, edge chipping or breakage. After the bonding has cured, the cutting machine parameters are set to complete the multi-wire cutting process and obtain antimony bromide wafers; this greatly reduces the scrap caused by cutting fragments and crystal orientation deviations, and significantly improves the yield.

[0031] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0032] It is understood that the embodiments of this application have been described above in conjunction with the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. As those skilled in the art will know, various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, those skilled in the art, under the guidance or instruction of this application, can modify these features and embodiments to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this invention.

Claims

1. A multi-wire saw method for cutting antimony chalcogenide crystals, characterized in that, The method comprises the following steps: providing an antimony compound crystal with one end of which is oriented and placing the crystal in a preset graphite holder; wherein the graphite holder is configured as a long slot structure with both ends open; placing the graphite holder with the antimony compound crystal in a preset positioning table; wherein the positioning table comprises two mutually perpendicular table surfaces; the graphite holder is placed on one of the table surfaces, and the end of the antimony compound crystal with the completed orientation is made to abut against the other table surface; filling the gap between the antimony compound crystal and the graphite holder with a two-component epoxy resin adhesive and curing the adhesive; fixing the cured antimony compound crystal and graphite holder as a whole on a reference table surface of a cutting machine; based on a laser displacement sensor preset on a vertical reference surface of the cutting device, the sensor cursor is aligned with the end of the antimony compound crystal with the completed orientation; wherein an X and Y direction rotary table is preset below the reference table surface; performing a first calibration operation: adjusting the reference table surface to make the sensor cursor move along the Y direction on the end of the antimony compound crystal with the completed orientation, and adjusting the angle of the Y direction rotary table to make the value of the laser displacement sensor change by no more than a preset threshold value; performing a second calibration operation: adjusting the reference table surface to make the sensor cursor move along the X direction on the end of the antimony compound crystal with the completed orientation, and adjusting the angle of the X direction rotary table to make the value of the laser displacement sensor change by no more than a preset threshold value; bonding graphite baffles to both ends of the graphite holder to form a slot structure with both ends closed; setting the parameters of the cutting machine to perform multi-wire cutting to obtain an antimony compound wafer.

2. The method according to claim 1, wherein the height of the inner side of the graphite holder slot is greater than the maximum height of the cross section of the antimony compound crystal to be placed.

3. The method according to claim 1, wherein the height of the filled adhesive is not less than the maximum height of the cross section of the antimony compound crystal.

4. The method according to claim 1, wherein the preset threshold value is 3 μm.

5. The method according to claim 1, wherein the table surface is a stainless steel table surface, and the levelness of the table surface is less than 0.05°. ​ ​ ​ ​

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