Silicon wafer grinding production system and method thereof

Abstract

The present application belongs to the technical field of silicon wafer manufacturing, and discloses a silicon wafer grinding production system and a method thereof. The system comprises an upper cover and a bottom table that can be buckled up and down. The upper cover is internally provided with an annular upper grinding disc and a grouting system. The bottom table is internally provided with an annular lower grinding disc and a sun turntable. The bottom table is provided with an outer tooth column along the outer circle of the lower grinding disc. The sun turntable is provided with an inner tooth column. The annular gap between the upper and lower grinding discs is internally provided with a carrier that is engaged with the inner and outer tooth columns. The carrier is provided with a limiting hole and a cutting groove with an elastic stop bar. The method comprises assembling the carrier, fixing the ground silicon wafer, and performing planetary motion grinding. The residual thickness is monitored during the final grinding. The grinding disc rotating speed and pressure are adjusted. If necessary, the direction is finely adjusted to suppress resonance. The present application reduces the shaking of the silicon wafer through the elastic stop bar, eliminates resonance by adjusting the final parameters, ensures that the ground silicon wafer reaches the target thickness and has no ripples, the grinding time can be controlled, and the risk of silicon wafer damage is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silicon wafer manufacturing, and particularly relates to a silicon wafer grinding production system and a method thereof. BACKGROUND

[0002] The working principle of the existing silicon wafer double-side grinding machine is to rely on the relative motion of the upper and lower parallel grinding discs, the silicon wafer is placed in a carrier with a planetary wheel structure, and the self-rotation and revolution of the carrier are completed synchronously, and the cutting action of the abrasive such as silicon carbide and diamond powder in the grinding liquid is used to uniformly grind the front and back surfaces of the silicon wafer to realize surface treatment and thickness control. The core use is a key equipment in the manufacturing process of silicon wafers, mainly for processing the silicon wafers after slicing of single crystal silicon or polycrystalline silicon, and can adapt to mainstream silicon wafer sizes from a few inches to twelve inches and above, laying a foundation for subsequent fine processing. From the process association, the double-side grinding is in the middle link of the silicon rod cutting-double-side grinding-fine grinding-chemical mechanical polishing-cleaning, and the silicon wafer after double-side grinding can preliminarily remove the cutting damage layer and improve the parallelism of the two surfaces, but the surface still has a certain roughness and slight damage. The fine grinding of the silicon wafer is a further fine process after the double-side grinding, and the purpose is to further reduce the surface roughness of the silicon wafer and optimize the thickness uniformity through finer abrasives and more precise process parameters, and completely remove the slight damage layer remaining after the double-side grinding, so that the surface of the silicon wafer approaches the mirror state, and finally provides a high-quality surface substrate for subsequent chemical mechanical polishing, ensures the precision requirements of core processes such as photolithography and thin film deposition in semiconductor device manufacturing, and avoids affecting the device performance due to surface defects.

[0003] In the fine grinding process of the silicon wafer, the rigidity of the silicon wafer is continuously reduced as the thickness gradually decreases. Due to the gap between the limiting hole and the silicon wafer, the silicon wafer is easy to produce slight shaking in the revolution and rotation motion of the carrier, and the reverse rotation of the upper and lower grinding discs will exert a periodic force on the silicon wafer. When the frequency of the periodic force overlaps with the natural frequency of the silicon wafer, resonance phenomenon will be induced. The resonance will cause the silicon wafer surface to produce corrugated defects, especially in the later stage of grinding, the remaining grinding allowance of the silicon wafer is small, and the corrugation produced at this time is difficult to remove through subsequent grinding, directly affecting the surface precision and product quality of the silicon wafer. SUMMARY

[0004] In order to solve the problems existing in the prior art, the application provides a silicon wafer grinding production system and a method thereof, which aims to minimize the defects of the silicon wafer grinding caused by resonance through optimization of the structure and improvement of the method steps.

[0005] The technical scheme adopted by the application is as follows:

[0006] In a first aspect, the present application discloses a silicon wafer grinding production system for double-sided fine grinding of silicon wafers, comprising an upper cover and a bottom base that are mutually buckled, wherein the upper cover is internally provided with an annular upper grinding disc and a grouting system, the bottom base is internally provided with an annular lower grinding disc and a sun turntable in the inner circle of the lower grinding disc, the bottom base is provided with an outer tooth column along the outer circle edge of the lower grinding disc, the sun turntable is provided with an inner tooth column, and a carrier for planet motion grinding of silicon wafers is arranged in the annular gap formed between the buckled upper grinding disc and lower grinding disc.

[0007] The carrier is provided with a plurality of limiting holes for placing silicon wafers and the inner diameter of the limiting holes is at least mm larger than the outer diameter of the silicon wafers, the limiting holes are provided with a cutting groove on one side edge and an elastic stop bar in the cutting groove, and the elastic stop bar gives the silicon wafers an elastic limiting force.

[0008] In combination with the first aspect, the present application provides a first embodiment of the first aspect, wherein the corresponding elastic stop bar protrudes from the cutting groove when the limiting hole is not placed with the silicon wafer, the elastic stop bar is pushed into the cutting groove for mounting the silicon wafer, and the elastic limiting force applied to the silicon wafer by the elastic stop bar is smaller than the planar displacement frictional resistance of the silicon wafer during grinding when the external pushing force is lost.

[0009] In combination with the first aspect, the present application provides a second embodiment of the first aspect, wherein the elastic stop bar is an elastic structure embedded in the cutting groove and the thickness of the elastic stop bar is not greater than the thickness of the carrier, and the elastic limiting force is provided by elastic deformation of the elastic stop bar.

[0010] In combination with the second embodiment of the first aspect, the present application provides a third embodiment of the first aspect, wherein the carrier is a metal sheet body, the cutting groove and the elastic stop bar are formed by laser cutting or etching on the edge of the limiting hole, and the elastic stop bar and the cutting groove are provided with a hollow elastic part for elastic connection formed by laser cutting or etching in front of the elastic stop bar and the cutting groove, and the elastic stop bar is displaced into the cutting groove by compression deformation of the elastic part.

[0011] In combination with the third embodiment of the first aspect, the present application provides a fourth embodiment of the first aspect, wherein the carrier is provided with a plurality of limiting holes arranged along the same central angle of the circle center, and the cutting groove of each limiting hole is arranged towards the circle center of the carrier.

[0012] In combination with the fourth embodiment of the first aspect, the present application provides a fifth embodiment of the first aspect, wherein the elastic stop bar is provided with a hollow binding fixed point, the carrier is provided with a hollow positioning point at the circle center, an external binding member is inserted into the positioning point and the binding fixed point of at least one elastic stop bar at the same time, and the elastic stop bar is squeezed to enter the cutting groove by the binding member.

[0013] In combination with the fourth implementation manner of the first aspect, the application provides a sixth implementation manner of the first aspect, wherein the elastic blocking strip is provided with hollow binding fixing points, and the external binding member is inserted into all the binding fixing points and is gathered towards the carrier circular part so that the blocking strip extrudes the elastic part into the cutting groove.

[0014] In combination with the fifth or sixth implementation manner of the first aspect, the application provides a seventh implementation manner of the first aspect, wherein the elastic blocking strip is gathered into the cutting groove by the external binding member, and a gap is formed at the edge of the limiting hole to facilitate the insertion of the fulcrum to lift the silicon wafer away from the limiting hole.

[0015] In the second aspect, the application further provides a production method using the silicon wafer grinding production system, and the specific steps are as follows:

[0016] First, the upper cover is lifted to expose the end surface of the base, and then the carrier is placed in the area of the grinding disc and is engaged and fixed with the outer tooth column and the inner tooth column;

[0017] Then, the external structure with the pin is inserted into the binding fixing points of the corresponding elastic blocking strip to gather into the cutting groove;

[0018] Then, the ground silicon wafer is placed in the limiting hole to release the elastic blocking strip to limit and fix the ground silicon wafer;

[0019] The parameters are set, the upper cover is lowered and buckled on the base to perform planetary motion grinding until the grinding is completed.

[0020] In combination with the second aspect, the application provides a first implementation manner of the second aspect, wherein during the grinding process, the real-time thickness of the ground silicon wafer, the vibration data of the upper grinding disc and the lower grinding disc and the grinding pressure data are collected in real time by the sensor; when it is monitored that the remaining thickness of the ground silicon wafer decreases to a preset threshold value, the final grinding stage is entered; if it is monitored that the vibration data or the grinding pressure data exceeds a preset resonance judgment range, the rotation speed of the upper grinding disc and the lower grinding disc is adjusted, or the single-sided grinding disc is controlled to stop rotating for a short time until the vibration data and the grinding pressure data return to the normal range; the ground silicon wafer is continuously ground by maintaining the adjusted parameters, and in the last stage when the ground silicon wafer approaches the target thickness, the grinding pressure is reduced until the ground silicon wafer reaches the target thickness, and the fine grinding is completed.

[0021] The application has the following beneficial effects:

[0022] The application provides moderate elastic limiting force by setting the elastic blocking strip on the edge of the limiting hole of the carrier, which not only ensures the stability of the silicon wafer placement, but also does not affect the planetary motion of the silicon wafer with the carrier, and the external binding member can quickly realize the pick-and-place operation of the silicon wafer, thereby reducing the operation difficulty and the risk of silicon wafer damage.

[0023] This invention introduces a resonance suppression mechanism into the grinding method. By monitoring the silicon wafer thickness in real time, the grinding wheel speed is adjusted or the grinding wheel on one side is stopped briefly during the critical final grinding stage. This effectively breaks the conditions for resonance and avoids the generation of ripple defects on the silicon wafer surface from the root, ensuring the surface accuracy and processing quality of the silicon wafer when it reaches the target thickness.

[0024] This invention does not require any modification to the main structure of existing double-sided grinding equipment. Resonance suppression can be achieved simply by optimizing the structure of the carrier and controlling the parameters of the grinding process. It is compatible with the usage scenarios of existing equipment, and the operation process is simple and easy to implement. Under the premise of ensuring processing quality, it only moderately extends the grinding time without affecting the overall processing efficiency of the equipment. It has strong practicality and promotional value. Attached Figure Description

[0025] Figure 1 This is a partial isometric view of the silicon wafer grinding production system in an embodiment of the present invention;

[0026] Figure 2 This is a partial top view of the silicon wafer grinding production system in an embodiment of the present invention;

[0027] Figure 3 This is a plan view of the carrier in an embodiment of the present invention;

[0028] Figure 4 This is an isometric view of the carrier in an embodiment of the present invention.

[0029] In the figure: 1-grinding silicon wafer, 2-base stage, 3-lower grinding disc, 4-solar disk, 5-carrier, 6-outer toothed column, 7-inner toothed column, 8-elastic stop bar, 9-elastic part, 10-binding fixing point, 11-groove, 12-limiting hole. Detailed Implementation

[0030] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] It should be noted that like reference numerals and characters refer to like elements throughout the following figures and description, and thus, once certain terminologies are defined in one figure, they do not need to be further defined and explained in the subsequent figures.

[0034] In the description of the present application, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first", "second" and the like appear in the description of the present application, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0035] In addition, if the terms "horizontal", "vertical" and the like appear in the description of the present application, they do not mean that the component must be absolutely horizontal or vertical, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0036] In the description of the present application, it should also be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. Embodiment

[0037] The embodiment discloses a grinding production system, referring to Figure 1 and Figure 2 .

[0038] The grinding production system comprises an upper cover and a bottom table 2 which are buckled to each other, the upper cover is a hollow cavity structure, an annular upper grinding disc is fixedly installed on the inner side of the upper cover, a grouting system is integrated on the top of the upper cover, the grouting system comprises a liquid storage tank, a conveying pipeline and spray nozzles which are uniformly distributed on the inner side of the upper grinding disc, and is used for continuously injecting grinding liquid between the upper grinding disc and the grinding silicon wafer 1. The grinding liquid is prepared by mixing silicon carbide or diamond powder, aqueous dispersant and deionized water, and has the functions of cutting, cooling and lubrication.

[0039] The bottom base 2 is a groove structure, and the annular lower grinding disc 3 is fixedly installed in the groove. The inner ring of the lower grinding disc 3 is provided with a sun rotating disc 4, and the sun rotating disc 4 is coaxially arranged with the bottom base 2. The outer tooth column 6 is fixedly installed along the outer ring edge of the lower grinding disc 3. The outer periphery of the sun rotating disc 4 is provided with an inner tooth column 7, and the outer tooth column 6 and the inner tooth column 7 are matched in specification and concentrically and annularly distributed.

[0040] After the upper cover is buckled with the bottom base 2, the upper grinding disc is parallel to the lower grinding disc 3, and an annular grinding gap is formed between the upper grinding disc and the lower grinding disc 3. The width of the annular grinding gap is slightly greater than the target thickness of the grinding silicon wafer 1. The carrier 5 is placed in the annular gap. The outer periphery of the carrier 5 is provided with a tooth-shaped structure which is engaged with the outer tooth column 6 and the inner tooth column 7, thereby forming a planetary transmission mechanism. The power mechanism includes a driving motor, a speed reducer and a transmission shaft. The driving motor is connected with the sun rotating disc 4 through the speed reducer, controls the sun rotating disc 4 to drive the carrier 5 to make revolution and rotation in the annular gap, and simultaneously drives the upper and lower grinding discs to relatively displace in the opposite direction in the pressure maintaining state.

[0041] The carrier 5 is a sheet structure, and a plurality of limiting holes 12 are arranged along the same central angle. The inner diameter of the limiting hole 12 is at least 2 mm greater than the outer diameter of the grinding silicon wafer 1, thereby reserving a grinding liquid flow space. A cutting groove 11 is arranged on one side edge of each limiting hole 12, and an elastic stop strip 8 is installed in the cutting groove 11. The elastic stop strip 8 is a structure with elastic deformation capacity and protrudes from the cutting groove 11 in a natural state, thereby exerting an elastic limiting force on the edge of the grinding silicon wafer 1 placed in the limiting hole 12.

[0042] The production method of the embodiment is as follows:

[0043] Firstly, the equipment control program is started, the upper cover is lifted upwards, the area of the lower grinding disc 3 of the bottom base 2 is exposed, the carrier 5 is placed in the annular gap, and it is ensured that the outer peripheral tooth-shaped structure of the carrier 5 is precisely engaged with the outer tooth column 6 and the inner tooth column 7 and is fixed;

[0044] The external structure with a plug is inserted into the binding fixing point 10 of the elastic stop strip 8, the elastic stop strip 8 is gathered into the cutting groove 11, and the limiting hole 12 forms a complete circular opening. The grinding silicon wafer 1 to be ground is placed in the corresponding limiting hole 12 one by one, the external structure is removed, the elastic stop strip 8 is reset under the action of its own elasticity, and the edge of the grinding silicon wafer 1 is flexibly limited.

[0045] The parameters such as grinding pressure, grinding disc rotating speed and total grinding time are set, the upper cover is lowered and buckled and locked with the bottom base 2. The grouting system is started to continuously inject the grinding liquid, the power mechanism drives the sun rotating disc 4 to rotate and drives the carrier 5 to make planetary motion, the upper grinding disc applies a preset pressure downwards, the grinding silicon wafer 1 is fully contacted with the upper grinding disc and the lower grinding disc 3 under the driving of the carrier 5, the double-sided uniform grinding is realized, and the fine grinding processing is completed until the preset grinding time is reached. Embodiment

[0046] The embodiment discloses a grinding production system based on a high polymer hard material carrier 5, and the core is to optimize the structural design of the carrier 5.

[0047] The carrier 5 is integrally formed by using polyether ether ketone or other high polymer hard materials, is in a circular sheet structure, and is suitable for processing an 8-inch grinding silicon wafer 1.

[0048] The carrier 5 has a diameter of 300 mm and a thickness of 0.8 mm, six limiting holes 12 are arranged along the same central angle of the center, each limiting hole 12 has a diameter of 203 mm, is matched with the outer diameter of the 8-inch grinding silicon wafer 1, and has a reserved gap of 2 mm.

[0049] An arc-shaped cutting groove 11 is cut at the circumferential position of each limiting hole 12, the corresponding central angle of the cutting groove 11 is 45 degrees, the width of the cutting groove 11 is 3 mm, the depth of the cutting groove 11 is 0.3 mm, and the inner wall of the cutting groove 11 is a smooth arc surface to avoid stress concentration.

[0050] The cutting groove 11 is injected with an elastic material and is formed by solidification to form an elastic stop bar 8, the elastic material is prepared by blending fluororubber and polyether ether ketone at a mass ratio of 7:3, and has good elasticity and wear resistance. The thickness of the elastic stop bar 8 is consistent with the thickness of the carrier 5, and the elastic stop bar 8 protrudes from the inner wall of the cutting groove 11 by 0.2 mm in a natural state, the cutting groove 11 is not completely filled, a deformation space of the elastic stop bar 8 is reserved, the elastic stop bar 8 is prevented from being bent in the thickness direction, contact with the upper and lower grinding discs 3 in the grinding process is avoided, and extrusion damage is prevented.

[0051] The production method of the embodiment is as follows: first, the carrier 5 is pretreated, the formed high polymer hard material carrier 5 is surface cleaned, and debris and impurities in the cutting groove 11 are removed; the cutting groove 11 is injected with a molten elastic material, the forming range of the elastic material is limited by a mold, the thickness of the elastic stop bar 8 is ensured to be consistent with the carrier 5, and the elastic stop bar 8 is edge trimmed after cooling and solidification to make the surface of the elastic stop bar 8 smooth and flat.

[0052] In the equipment preparation stage, the upper cover is lifted, the processed carrier 5 is placed in the annular gap of the base table 2, the carrier 5 is engaged in place with the outer tooth column 6 and the inner tooth column 7, the pins of the external restraint member are inserted into all the restraint fixing points 10 of the elastic stop bars 8, the carrier 5 is gathered towards the center, the elastic stop bars 8 are completely retracted into the cutting grooves 11, and the limiting holes 12 form complete openings; the 8-inch grinding silicon wafer 1 is stably placed in each limiting hole 12, and the center of the grinding silicon wafer 1 is ensured to be aligned with the center of the limiting hole 12; the external restraint member is slowly released, the elastic stop bars 8 are reset under the action of the elasticity of the elastic stop bars 8, and the grinding silicon wafer 1 is flexibly limited from the side.

[0053] The grinding parameters are set, the grinding pressure is 20 kPa, the upper grinding disc rotates at 95 rpm, the lower grinding disc rotates at 85 rpm, both in opposite directions, and the total grinding time is 25 minutes; the upper cover is lowered and buckled, the grouting system is started, and the grinding liquid is continuously injected; the power mechanism drives the carrier 5 to move in a planetary motion, and the grinding silicon wafer 1 stably follows the carrier 5 under the limiting action of the elastic stop bar 8, uniformly contacts the upper and lower grinding discs 3 for grinding, until the preset grinding time is completed.

[0054] The effect of this embodiment is that by arranging the elastic stop bar 8 in the cutting groove 11, the flexible limiting of the grinding silicon wafer 1 is formed, the shaking amplitude of the grinding silicon wafer 1 in the limiting hole 12 during grinding is reduced, the probability of resonance caused by the superposition of shaking and periodic force is reduced, and the elastic deformation capacity of the elastic stop bar 8 can absorb part of the vibration energy, effectively reducing the influence of resonance on the surface of the grinding silicon wafer 1, and improving the grinding uniformity. Embodiment

[0055] This embodiment discloses a grinding production system based on a metal carrier 5, which is designed for the integrated elastic structure of the carrier 5, referring to Figure 3 and Figure 4 .

[0056] The carrier 5 is made of 304 stainless steel material and is integrally formed by laser cutting or etching process, and has a circular sheet structure with a thickness of 0.7 mm and a diameter of 280 mm.

[0057] The carrier 5 is uniformly arranged with three limiting holes 12 along the center of the circle at an angle of 120 degrees, which are suitable for processing 6-inch grinding silicon wafers 1, and each limiting hole 12 has a diameter of 152 mm, which is suitable for the outer diameter of the 6-inch grinding silicon wafer 1, and has a reserved gap of 2 mm.

[0058] The edge of each limiting hole 12 is provided with a cutting groove 11 towards the center of the carrier 5, the cutting groove 11 has a width of 4 mm and a length of 15 mm, and the edges of the limiting hole 12 on both sides of the cutting groove 11 are treated with a circular arc with a radius of 1 mm to avoid stress concentration points.

[0059] The integral metal elastic stop bar 8 and elastic part 9 are formed in the cutting groove 11 by laser cutting, the elastic stop bar 8 has an arc-shaped sheet structure and is adapted to the curvature of the inner wall of the limiting hole 12, and protrudes 0.15 mm from the inner wall of the cutting groove 11 in a natural state.

[0060] The elastic part 9 is a symmetrically arranged arch-shaped structure towards the opening direction of the cutting groove 11, which connects the bottom edge of the cutting groove 11 and the two ends of the elastic stop bar 8, and the inner side of the elastic part 9 is provided with a hollow area to enhance the elastic deformation capacity.

[0061] The metal carrier 5 of the specification has a plane displacement friction resistance of 1.5-2 N during the grinding process of the silicon wafer 1 moving with the carrier 5, and the elastic limiting force of 0.8-1.2 N applied to the silicon wafer 1 by the elastic stopper 8 in a natural state is less than the plane displacement friction resistance, which ensures the stable limiting of the silicon wafer 1 and does not affect the synchronous movement of the silicon wafer 1 with the carrier 5.

[0062] The production method of the embodiment is as follows:

[0063] First, the carrier 5 is prepared. A 304 stainless steel sheet is selected, the shape of the carrier 5, three limiting holes 12 and a cutting groove 11 are processed by laser cutting, and then the structure of the elastic stopper 8 and the elastic part 9 is refined by etching process to ensure the accurate molding of the hollow area of the elastic part 9. Finally, the edges of the cutting groove 11 and the surface of the elastic stopper 8 are passivated and polished to remove burrs.

[0064] In the equipment assembly stage, the upper cover is lifted, the metal carrier 5 is placed in the annular gap of the base 2, the position of the carrier 5 is adjusted to ensure smooth transmission, the pins of the external restraint are inserted into the positioning points of the center of the carrier 5 and the restraint fixing points 10 of the three elastic stoppers 8, and the elastic part 9 is bent under pressure to drive the elastic stopper 8 to retract into the cutting groove 11, at which time a gap is formed at the edge of the limiting hole 12. The 6-inch silicon wafer 1 is placed in the limiting hole 12 one by one, and the placement state of the silicon wafer 1 is observed through the gap to ensure that there is no deviation. The external restraint is released, the elastic part 9 is elastically reset, the elastic stopper 8 is protruded from the cutting groove 11, and the edge of the silicon wafer 1 is uniformly limited.

[0065] The grinding parameters are set as follows: grinding pressure 18 kPa, upper grinding disc speed 100 rpm, lower grinding disc speed 90 rpm, reverse rotation, and total grinding time 22 minutes. The upper cover is lowered and buckled, the grouting system is started, and the grinding liquid is uniformly sprayed between the upper grinding disc and the silicon wafer 1 through the spray port. The power mechanism drives the sun disc 4 and the external tooth column 6 to rotate, and the carrier 5 rotates and revolves under the meshing action. The silicon wafer 1 moves stably under the limiting action of the elastic stopper 8. When the inner wall of the limiting hole 12 drives the silicon wafer 1 to move, the elastic stopper 8 is subjected to a lateral force from the silicon wafer 1 and is retracted into the cutting groove 11. The support force is provided by the contact between the edges of the limiting holes 12 on both sides of the cutting groove 11 to ensure that the silicon wafer 1 is uniformly stressed until the grinding is completed.

[0066] After the grinding is completed, the upper cover is lifted up, and an external binding member is inserted into the binding fixing points 10 of the three elastic blocking strips 8, which is a mechanical clamp with three sliding grooves or clamping arms, which can rotate or clamp after being inserted into the three binding fixing points 10, so that the three elastic blocking strips 8 are all gathered to the center of the carrier 5, thereby simultaneously releasing the three ground silicon wafers 1. Since the elastic blocking strips 8 after gathering are completely sunk into the cutting groove 11, a gap is formed at the opening of the cutting groove 11, which facilitates the operator to insert and pull out the silicon wafer from the gap by hand.

[0067] It should be noted that, because the surface of the ground silicon wafer still has a lot of grinding liquid, the prior art usually opens a groove on the inner wall of the limiting hole or directly forms a gap by cutting the corner of the silicon wafer, thereby facilitating the hand to pull out. Embodiment

[0068] The embodiment discloses a grinding production method with resonance suppression function, which is based on the metal carrier 5 structure of embodiment 3, and focuses on optimizing the parameter control logic of the grinding process.

[0069] The grinding production system of the embodiment is based on embodiment 3, and a sensor assembly and an intelligent control system are additionally arranged. The sensor assembly includes a laser thickness gauge, a vibration acceleration sensor and a pressure sensor. The laser thickness gauge is installed on the inner side of the upper cover, and is used to collect the thickness data of the ground silicon wafer 1 in real time. The vibration acceleration sensor is installed on the lower grinding disc 3 support of the bottom table 2, and is used to collect the vibration data of the equipment. The pressure sensor is installed on the pressing mechanism of the upper grinding disc, and is used to collect the grinding pressure data. All the sensor data are transmitted to the intelligent control system in real time.

[0070] The production method of the embodiment is as follows: the carrier 5 assembly and the ground silicon wafer 1 placement steps are the same as those of embodiment 3, and after completion, the parameter setting and grinding phase is entered:

[0071] Initial parameter setting

[0072] The target thickness of the ground silicon wafer 1 is set to 80 μm, the initial value of the grinding pressure is 20 kPa, the initial rotating speed of the upper grinding disc is 100 rpm, the initial rotating speed of the lower grinding disc 3 is 90 rpm, the upper grinding disc and the lower grinding disc 3 rotate in opposite directions, the grouting system flow is 5 L / min, the preset final grinding start threshold is 5 μm of the remaining thickness, and the resonance judgment range is vibration acceleration≥0.8 g and pressure fluctuation≥±5 kPa.

[0073] Initial grinding stage

[0074] After the upper cover is buckled, the grinding program is started, the grouting system continuously injects the grinding liquid, the power mechanism drives the carrier 5 to make planetary motion, and the intelligent control system monitors the thickness data of the ground silicon wafer 1 in real time. At this time, the ground silicon wafer 1 has a larger thickness and stronger rigidity, and the initial parameter grinding is maintained until the remaining thickness of the ground silicon wafer 1 is monitored to be reduced to 5μm, and the final stage grinding stage is entered.

[0075] Final stage resonance monitoring

[0076] After the final stage grinding stage is started, the intelligent control system increases the sensor data acquisition frequency, and the vibration acceleration data and pressure data are collected every 100ms, and are compared with the preset resonance judgment range; at the same time, according to the remaining thickness 5μm and the final stage average removal rate 0.8μm / min, the final stage grinding time is calculated to be 6.25min.

[0077] Resonance intervention adjustment

[0078] If the monitored vibration acceleration is greater than 0.8g and the pressure fluctuation is greater than 5kPa, it is determined that resonance is generated, and the intervention program is immediately started.

[0079] The rotation speed of the lower grinding disc 3 is kept unchanged at 90rpm, and the rotation speed of the upper grinding disc is gradually reduced from 100rpm to 70rpm, and the adjustment process lasts for 500ms to avoid sudden change of rotation speed causing new vibration; if the vibration acceleration is less than 0.8g and the pressure fluctuation is less than 5kPa within 500ms after adjustment, the adjusted rotation speed is maintained to continue grinding; if it is still in the resonance state, the rotation speed of the upper grinding disc is further reduced to 60rpm; in the extreme case, if the resonance still exists after rotation speed adjustment, the rotation of the upper grinding disc is stopped, and the rotation of the lower grinding disc 3 and the grinding pressure are maintained, and after 30s, the upper grinding disc is restarted and increased to 70rpm to ensure that the resonance is eliminated.

[0080] Pressure fine adjustment and finishing

[0081] After the resonance is eliminated, the current rotation speed parameter is maintained to continue grinding, and when the remaining thickness of the ground silicon wafer 1 is monitored to be reduced to 1μm, the light pressure finishing program is started, and the grinding pressure is gradually reduced from 20kPa to 8kPa to avoid vibration caused by final stage pressure fluctuation; the last 10s is kept in the light pressure state, and until the thickness of the ground silicon wafer 1 reaches the target value of 80μm, the intelligent control system successively closes the power mechanism, the grouting system, and the upper cover is lifted to complete the grinding.

[0082] The embodiment breaks the condition of resonance generation in the final stage grinding stage through accurate threshold triggering, real-time resonance monitoring and dynamic parameter adjustment, ensures that the ground silicon wafer 1 has no ripple defects when reaching the target thickness, and only moderately prolongs the final stage grinding time by 5-10%, without affecting the overall processing efficiency.

[0083] Further, the scheme is based on the above scheme, through the parameter acquisition, cycle determination, step operation, time control four steps to realize resonance suppression, can accurately match the thickness change of silicon wafer, ensure that the final grinding has no resonance, time extension is controllable.

[0084] First determine the core basis parameters of cycle calculation

[0085] First, get the key data from the device sensor as the basis for calculating the resonance suppression operation cycle, without additional hardware:

[0086] Real-time remaining thickness: read by laser thickness gauge, that is, the current grinding silicon wafer 1 thickness-target thickness, such as target thickness 80μm, current thickness 85μm, remaining thickness is 5μm;

[0087] Current removal rate: calculated according to the grinding pressure, such as current pressure 20kPa, removal rate is stable at 0.8μm / min, calibrated in advance through small batch experiment, different pressure corresponds to fixed removal rate;

[0088] Resonance risk judgment value: preset vibration acceleration threshold 0.8g, exceeding means there is a resonance risk, pressure fluctuation threshold ±5kPa.

[0089] Simple calculation of resonance suppression operation cycle

[0090] Based on the remaining thickness can be polished, add a small amount of adjustment time, the specific logic is as follows:

[0091] First calculate the basic grinding time: divide the remaining thickness by the current removal rate to get the theoretical grinding time without resonance adjustment. For example, remaining thickness 5μm, removal rate 0.8μm / min, basic time=5÷0.8=6.25min;

[0092] Add resonance adjustment reserved time: according to experience, reserve 10% of the basic time as adjustment buffer, that is, 6.25min×10%≈0.6min;

[0093] The final resonance suppression operation cycle=the basic grinding time+the adjustment reserved time, such as 6.25+0.6≈6.85min.

[0094] Divide the resonance suppression operation into three steps in the cycle

[0095] In the calculated 7min cycle, operate in the order of first speed adjustment-then stable pressure-last supplement turning, each step is aimed at resonance risk, and does not affect the grinding efficiency:

[0096] Speed adjustment (0-2min):

[0097] If the vibration sensor detects acceleration ≥ 0.8g, keep the lower grinding plate 3 speed 90 rpm unchanged, and reduce the upper grinding plate speed from 100 rpm to 70 rpm in 3 steps, each by 10 rpm, with a 10-second interval to avoid sudden changes in speed causing new vibrations;

[0098] After adjustment, monitor for 30 seconds. If the vibration acceleration is < 0.8g, it means that the resonance has been eliminated, and the grinding is continued at 70 rpm. If it is still over the limit, reduce it by another 10 rpm to 60 rpm (in extreme cases, a maximum of 2 times).

[0099] Fine-tune the pressure (2-4 min):

[0100] After the speed is reduced, the removal rate will decrease slightly. At this time, increase the grinding pressure from 20 kPa to 22 kPa, with a small amount of adjustment to avoid damaging the silicon wafer due to excessive pressure, and increase the removal rate to about 0.8 μm / min.

[0101] After fine-tuning, monitor for 1 minute to ensure that the removal rate is stable and that the remaining thickness is not ground out due to a low removal rate.

[0102] Turn to the supplementary adjustment (4-7 min):

[0103] If there is still slight resonance after the first two steps, keep the lower grinding plate 3 rotating clockwise unchanged, and change the upper grinding plate from counterclockwise to clockwise. Changing the direction of rotation changes the relative frequency of the grinding plate and the silicon wafer, breaking the resonance.

[0104] After the direction of rotation is adjusted, keep it for 2 minutes until the remaining thickness is ground out. During this period, continuously monitor the vibration data to ensure that there is no resonance.

[0105] Control the grinding time extension range

[0106] Time control for adjustment steps: the total time for speed, pressure, and direction adjustment should not exceed 1.5 minutes, and the grinding should not be interrupted during adjustment, and the silicon material should still be removed.

[0107] Removal rate compensation: if the removal rate decreases after adjustment, increase the pressure slightly to compensate for the removal rate, ensuring that the remaining thickness of 5 μm is ground out within 7 minutes, without significantly extending the time due to adjustment. The actual total time is only 0.5-1 minute longer than the basic time, with an extension range of ≤ 16%, and can be optimized to ≤ 10% through preliminary experiments.

[0108] The present application is not limited to the above-mentioned optional embodiments, and anyone can derive other various forms of products under the inspiration of the present application. The above specific embodiments should not be understood as limiting the scope of protection of the present application, and the scope of protection of the present application should be defined by the claims, and the specification can be used to interpret the claims.

Claims

1. A silicon wafer grinding production system for double-sided fine grinding of silicon wafers, comprising an upper cover and a bottom base (2) that are mutually buckled, the upper cover is internally provided with an annular upper grinding disc and a grouting system, the bottom base (2) is internally provided with an annular lower grinding disc (3) and a sun turntable (4) at the inner circle of the lower grinding disc (3), the bottom base (2) is provided with an outer toothed column (6) along the outer circle edge of the lower grinding disc (3), the sun turntable (4) is provided with an inner toothed column (7), and a carrier (5) for driving the planetary motion grinding of silicon wafers is arranged in the annular gap formed between the buckled upper grinding disc and the lower grinding disc (3). characterized in that The carrier (5) is provided with a plurality of limiting holes (12) for placing silicon wafers and the inner diameter of the limiting holes (12) is at least 2mm larger than the outer diameter of the silicon wafers, the limiting holes (12) are provided with a cutting groove (11) on one side edge and an elastic stop bar (8) is arranged in the cutting groove (11) to give the silicon wafers an elastic limiting force. When the limiting holes (12) are not placed with silicon wafers, the corresponding elastic stop bar (8) protrudes from the cutting groove (11), the elastic stop bar (8) is pushed into the cutting groove (11) for installing the silicon wafers, and the elastic limiting force applied to the silicon wafers by the elastic stop bar (8) when losing external pushing force is smaller than the plane displacement frictional resistance of the silicon wafers during grinding. The carrier (5) is a metal sheet body, the cutting groove (11) and the elastic stop bar (8) are formed by laser cutting or etching on the edge of the limiting hole (12) of the carrier (5), and the elastic stop bar (8) and the cutting groove (11) are provided with a hollow elastic part (9) formed by laser cutting or etching for elastic connection, the elastic stop bar (8) is displaced into the cutting groove (11) by the compression deformation of the elastic part (9). The carrier (5) is provided with a plurality of limiting holes (12) arranged along the same central angle of the center, and the cutting groove (11) of each limiting hole (12) is opened towards the center of the carrier (5). The elastic stop bar (8) is provided with a hollow binding fixed point (10), and a hollow positioning point is arranged at the center of the carrier (5), an external binding member is inserted into the positioning point and at least one elastic stop bar (8) binding fixed point (10) at the same time and is gathered to make the elastic stop bar (8) extrude the elastic part (9) into the cutting groove (11); or all the binding fixed points (10) are inserted by the external binding member at the same time and are gathered to the center of the carrier (5) to make the elastic stop bar (8) extrude the elastic part (9) into the cutting groove (11).

2. The silicon wafer lapping production system of claim 1, wherein: The elastic stop bar (8) is gathered into the cutting groove (11) by the external binding member, and a gap is formed at the edge of the limiting hole (12) for inserting the fulcrum to lift the silicon wafers away from the limiting hole (12).

3. A production method characterized by: The silicon wafer grinding production system of claim 2 is used, and the specific steps are as follows: First, lift the upper cover to expose the end face of the bottom base (2), then place the carrier (5) in the area of the lower grinding disc (3) and make the carrier (5) engage with the outer toothed column (6) and the inner toothed column (7) to be fixed; Then, an external structure with a pin is inserted into the binding fixed point (10) of the corresponding elastic stop bar (8) to gather it into the cutting groove (11); Then, the grinding silicon wafer (1) is placed in the limiting hole (12) to release the elastic stop bar (8) to limit and fix the grinding silicon wafer (1); Set parameters and lower the upper cover and buckle on the bottom platform (2) to carry out planetary motion grinding until the grinding is completed.

4. A method of production according to claim 3, wherein: During the grinding, the real-time thickness of the ground silicon wafer (1), the vibration data of the upper and lower grinding discs (3), and the grinding pressure data are collected in real time through sensors. When the remaining thickness of the ground silicon wafer (1) is monitored to be reduced to a preset threshold, the final grinding stage is entered; if the vibration data or the grinding pressure data is monitored to be out of the preset resonance judgment range, the rotation speed of the upper and lower grinding discs (3) is adjusted, or the rotation of the single-sided grinding disc is stopped for a short time until the vibration data and the grinding pressure data return to the normal range.

Images