Epitaxial wafer edge morphology compensation type wafer double-sided polishing device and method

Abstract

The invention provides an epitaxial wafer edge morphology compensation type wafer double-sided polishing device and method, and belongs to the technical field of semiconductor wafer ultra-precision machining. The polishing main machine comprises an upper fixed disc, a lower fixed disc and a wafer driving mechanism; the pressure loading system is used for applying adjustable pressure to the fixed disc; the polishing solution supply system is used for conveying a flow-adjustable polishing solution to the processing interface; the central control unit is in communication connection with the two systems and executes edge morphology compensation control logic, specifically, the machining pressure is adjusted in a segmented mode, and the flow of the polishing solution and the pressure are subjected to coupling change. According to the method, the atomic level flatness of the wafer surface is ensured, the edge morphology is accurately controlled, the edge thickening of the epitaxial layer is perfectly counteracted, and the photoetching yield of high-end chip manufacturing is remarkably improved.

Description

Technical Field

[0001] This disclosure relates to the field of ultra-precision machining technology in semiconductor manufacturing processes, and in particular to an epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus and method. Background Technology

[0002] In today's integrated circuit manufacturing field, process nodes are constantly approaching the limits of 7nm, 5nm, and even 3nm, which places extremely high demands on the geometric morphology of wafers, the basic substrate material. For large-size wafers of 300mm (12 inches), photolithography is the core bottleneck determining chip manufacturing yield. With the increase in the numerical aperture of photolithography machines, the depth-of-focus window is drastically compressed, which means that any tiny nanometer-level undulations on the wafer surface can lead to exposure defocusing. In particular, the wafer edge region has always been a challenge for flatness control due to the special physical boundary conditions. The industry typically uses indicators such as Edge Site Front least sQuares Range (ESFQD) to quantify edge morphology. In the manufacturing chain of high-end logic devices and memory devices, in order to obtain a perfect single-crystal lattice structure and accurately control doping distribution, epitaxial growth is usually required on the wafer surface after double-side polishing (DSP).

[0003] In current mainstream wafer manufacturing processes, double-sided polishing is a crucial step determining the final geometric accuracy of the wafer. Traditional double-sided polishing technology has consistently pursued "ultimate planarization," aiming to achieve zero undulation across the entire wafer surface (including edges). To achieve this, existing technologies typically employ high-hardness polishing pads (such as polyurethane foam pads), combined with multi-stage slow-increase processes, and the addition of special edge protectants (such as surfactants or polymers) to the polishing slurry to suppress overcutting and prevent roll-off. Under this process, the manufactured polished wafers typically have ESFQD values ​​close to zero, exhibiting near-perfect planar characteristics. This process performs exceptionally well in non-epitaxy applications and is considered the industry standard.

[0004] However, problems arise when this "ultra-flat" wafer enters the subsequent epitaxial growth stage. Due to the discontinuous gas dynamics and thermal field distribution within the epitaxial reaction chamber, the boundary layer thickness thins and the mass transfer rate increases as the precursor gas flows through the wafer edge. This results in a higher deposition rate at the edge than at the center, forming the so-called "edge thickening effect." Typically, the epitaxial layer is about 20nm to 30nm thicker at the edge than at the center. If the substrate itself is flat, this thickening layer will result in a significant edge rise on the final epitaxial wafer. This rise can cause severe defocusing at the edge during photolithography, rendering the entire chip within a few millimeters of the wafer edge unusable, significantly reducing the utilization rate of the expensive 300mm wafer. Although some have attempted to compensate by adjusting polishing parameters to create edge collapse, existing technologies struggle to balance the contradiction between "creating edge collapse" and "maintaining surface quality." Excessive pressure or uneven chemical corrosion often leads to deterioration of surface roughness, increased haze, or orange peel defects. Furthermore, batch stability is poor, making it difficult to meet the demands of industrial mass production. Summary of the Invention

[0005] This disclosure provides an epitaxial wafer edge morphology compensation wafer double-sided polishing apparatus and method. This solution utilizes the deformation characteristics of a non-woven polishing pad to actively create edge collapse through the reverse application of physical mechanisms, precisely compensating for edge thickening in subsequent epitaxial processes. Simultaneously, innovative rheological coupling control ensures surface quality.

[0006] To achieve the above objectives, this disclosure provides the following technical solution: In a first aspect, embodiments of this disclosure provide an epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus, comprising: The polishing host assembly includes an upper fixed plate and a lower fixed plate disposed opposite each other, and a drive mechanism for driving the wafer to move between the upper fixed plate and the lower fixed plate; A pressure loading system for applying adjustable processing pressure to the upper and / or lower platens; A polishing slurry supply system for supplying polishing slurry to the machining interface between the upper and lower fixed plates, the polishing slurry supply system having an adjustable flow rate output function; and The central control unit is communicatively connected to both the pressure loading system and the polishing fluid supply system. The central control unit is configured to execute edge topography compensation control logic, which includes controlling the pressure loading system to output different set pressure values ​​at different processing stages, and controlling the polishing fluid flow rate value output by the polishing fluid supply system to maintain a coupled change relationship with the set pressure value output by the pressure loading system.

[0007] In a second aspect, embodiments of this disclosure provide a method for double-sided polishing of epitaxial wafers with edge morphology compensation, the method being performed using the apparatus described in the first aspect, the method comprising: Set the target edge morphology parameter range, and determine the first pressure value of the high-pressure shaping stage and the second pressure value of the low-pressure modification stage based on this range; Establish a coupling function relationship between polishing fluid flow rate and processing pressure; When polishing is started, the central control unit controls the pressure loading system to output the first pressure value, and at the same time controls the polishing fluid supply system to output the first flow rate value according to the coupling function relationship. After maintaining the predetermined time or reaching the predetermined removal amount, the central control unit controls the pressure loading system to switch the output of the second pressure value, and at the same time automatically adjusts the output of the polishing fluid supply system to the second flow rate value according to the coupling function relationship.

[0008] This disclosure provides an epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus and method, which can stably create a collapsed edge at the edge of the polished wafer, perfectly offsetting the thickening of the epitaxial layer, resulting in excellent edge flatness of the final epitaxial wafer and significantly improving the depth-of-focus margin of the photolithography process; through flow-pressure coupling control, excessive chemical etching in the low-pressure stage is avoided, so that while obtaining the collapsed edge morphology, the surface roughness and haze level of the wafer are on par with the traditional planarization process. Attached Figure Description

[0009] Figure 1 This is a front view schematic diagram of the overall structure of the epitaxial wafer edge morphology compensation type wafer double-sided polishing device disclosed herein.

[0010] Figure 2 This is a top view schematic diagram of the moving parts of the epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus disclosed herein.

[0011] Figure 3 This is a schematic diagram of the dynamic supply system for polishing fluid in this disclosure.

[0012] Figure 4 This is a schematic diagram of the components of the central control unit in this disclosure.

[0013] Figure 5 This is a schematic flowchart of the epitaxial wafer edge morphology compensation type wafer double-sided polishing method in the embodiments of this disclosure. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present disclosure, a detailed description of the present disclosure will be provided below in conjunction with specific embodiments. This specific embodiment section aims to demonstrate, through a comprehensive explanation of the device structure, working principle, process flow, and experimental data, how the present disclosure achieves precise compensation for the edge morphology of epitaxial wafers and synergistic control of surface quality. The content described in this embodiment should be considered as an interpretation and supplement to the claims, not a limitation.

[0015] First, the mechanical hardware architecture of the epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus provided in this disclosure will be described in detail. See [link to relevant documentation]. Figure 1 and Figure 2 This device is a deeply customized and innovative design based on the basic architecture of a vertical planetary gear double-sided polishing machine. The core support structure of the device consists of an upper fixed plate 1 and a lower fixed plate 2, which are the physical carriers of the entire polishing process. Both the upper fixed plate 1 and the lower fixed plate 2 are precision cast from high-strength, low-thermal-expansion-coefficient ductile iron and undergo long-term natural aging and artificial thermal aging treatments before finishing to completely eliminate casting internal stress and prevent warping deformation under subsequent long-term thermal cycling and mechanical loads. This high-rigidity matrix design is the foundation for ensuring micron-level and even nanometer-level machining accuracy. The upper fixed plate 1 and the lower fixed plate 2 are coaxially opposite each other along the vertical axis, and their diameter is usually around 1500 mm to accommodate the batch processing of 300 mm large-size wafers (e.g., processing 15 to 20 wafers simultaneously in a single batch). Polishing pads 3 are bonded to the opposing working surfaces of the upper and lower fixed plates using high-strength pressure-sensitive adhesive.

[0016] The selection of the polishing pad 3 in this disclosure adheres to extremely stringent standards, which is the first hurdle to overcome in achieving the physical mechanism of "edge morphology compensation." Unlike traditional rigid polyurethane foam pads used to manufacture absolutely flat surfaces (whose compression ratio is typically less than 1%), this disclosure specifically selects a nonwoven type polishing pad 3 with specific compression modulus and viscoelastic characteristics. This polishing pad 3 is composed of polyester fiber felt impregnated with polyurethane resin, and its surface has a rich microporous structure, which can effectively store and transport polishing fluid. More importantly, the compression ratio of the polishing pad 3 is strictly selected between 2% and 4%, and the Shore C hardness is controlled between 70 and 80. This selection of material parameters makes the polishing pad 3 exhibit a significant viscoelastic hysteresis effect when subjected to normal pressure. Specifically, when the wafer 7 is pressed into the polishing pad 3 under high pressure, the polishing pad 3 not only undergoes compressive deformation in the vertical direction, but also produces a "rebound wrapping" phenomenon around the edge of the wafer 7, that is, the pad material bulges towards the side of the edge of the wafer 7, thereby significantly increasing the contact area and contact stress in the edge region. This stress concentration effect is the physical basis for the high removal rate achieved by this disclosure in the edge region, thereby "excavating" the collapsed edge morphology. If the pad is too hard, it cannot produce coverage, and the edge will remain flat; if the pad is too soft, the coverage will be excessive and uncontrollable, leading to severe edge roll-off and a very short lifespan. The selection of this disclosure is precisely at the "optimal balance point" between the two.

[0017] Regarding the drive system, this device employs a classic planetary transmission mechanism, but its precision and stability have been enhanced. (See also...) Figure 1 and Figure 2The mechanism comprises a sun gear 4 at the geometric center, an internal gear ring 5 on the periphery, and several planetary gears 6 distributed between the upper and lower fixed disks. The planetary gears 6 are typically made of wear-resistant, high-strength engineering plastics (such as glass fiber reinforced epoxy resin or polyetheretherketone), and their thickness is precisely double-polished to be controlled within a range slightly thinner than the final target thickness of the wafer 7 to be processed (e.g., 10-20 micrometers thinner), ensuring that the load is primarily borne by the wafer 7 rather than the planetary gears 6 during processing. Each planetary gear 6 has one or more (usually three) mounting holes for loading the wafer 7. During processing, the upper fixed disk 1 and the lower fixed disk 2 rotate in opposite directions (e.g., the upper fixed disk clockwise, the lower fixed disk counterclockwise), while the sun gear 4 and the internal gear ring 5 drive the planetary gears 6 to rotate and revolve. This complex planetary trajectory motion design ensures that every point on the surface of wafer 7 can statistically traverse different areas of the polishing pad 3 surface, thereby minimizing local thickness differences caused by uneven wear on the pad surface and guaranteeing excellent Global Back-side Referenced Ideal Range (GBIR). The drive motors disclosed herein all employ high-precision AC servo motors, coupled with low-backlash precision planetary reducers, ensuring that the speed fluctuation rate is controlled within 0.1%, eliminating high-frequency vibration patterns caused by speed fluctuations.

[0018] As one of the core innovations of this device, the precision pressure loading system 8 is endowed with unprecedented control capabilities. Traditional double-sided polishing machines often use simple airbag pressurization, which has a slow response speed and is difficult to achieve precise force control under high pressure. The precision pressure loading system 8 of this disclosure is mechanically connected to the non-working surface (back side) of the upper plate 1 and is equipped with a set of servo hydraulic actuators (or airbags controlled by high-response electro-proportional valves) evenly distributed along the circumference. The system has two key characteristics: first, an ultra-wide pressure adjustment range, capable of stably outputting normal loads from 1000 daN (ten Newtons) to 1800 daN, which covers the low-pressure finishing zone and high-pressure shaping zone required by the process of this disclosure; second, millisecond-level dynamic response capability, when the central control unit 10 issues a pressure step command, the system can complete the pressure establishment and stabilization within 500 milliseconds, and the steady-state error is controlled within ±5 daN. To accommodate the minute thickness wedge errors that may exist in the wafer assembly, the upper platen 1 is connected to the pressure loading system 8 via a specially designed spherical bearing or universal joint structure. This "floating" design allows the upper platen to make minute adaptive tilt adjustments during pressurization, ensuring that the pressure is applied evenly to each wafer 7.

[0019] Closely integrated with the precision pressure loading system 8 is the dynamic polishing slurry supply system 9. In existing polishing equipment, the polishing slurry supply is typically open-loop and constant. However, this disclosure reveals that in processes with significant pressure variations, a constant polishing slurry flow rate is the primary cause of unstable surface quality. Therefore, this disclosure constructs a closed-loop, variable flow rate supply system 9. See also... Figure 3 The system consists of a corrosion-resistant polishing slurry storage tank 901, a pulsation-free magnetic levitation centrifugal pump 902, a high-frequency response proportional control valve 903, and a high-precision flow meter 904. The delivery pipeline is made of soluble polytetrafluoroethylene (PFA) to prevent metal ion precipitation and contamination of the wafer 7. The nozzles 905 at the end of the pipeline are located at the center opening of the upper platen, or designed as multi-point distributed spray bars to ensure that the polishing slurry can be rapidly and evenly spread across the entire polishing interface. The core of this system lies in its real-time linkage capability between flow control and pressure control. The response time of its flow regulation is designed to be highly synchronized with the response time of the pressure loading system 8, which is the hardware foundation for realizing the "rheological coupling" process.

[0020] The central control unit 10 coordinates the operation of the entire device; it is essentially the brain of the device. This unit is built on a high-performance industrial computer or PLC and runs the control algorithms unique to this disclosure. See also Figure 1 The central control unit 10 communicates with the aforementioned subsystems in real time via a high-speed fieldbus. It is responsible not only for executing preset process recipes but, more importantly, for performing real-time logic operations and feedback control. The device is also equipped with a non-contact online measurement module 11, which typically employs infrared interferometry or eddy current sensor technology and is embedded in the upper platen 1. This module can penetrate the polishing slurry layer to monitor the thickness changes of the wafer 7 in real time. This data is the direct basis for determining process stage switching. Furthermore, considering the enormous frictional heat generated by high-pressure polishing, the device incorporates complex labyrinthine cooling medium channels within the upper platen 1 and lower platen 2, connected to an external high-power constant-temperature cooling circulation system. The central control unit 10 dynamically adjusts the flow rate and temperature of the cooling medium by monitoring temperature sensors at various points on the platen to maintain thermal balance on the platen surface and prevent platen deformation due to thermal expansion.

[0021] After detailing the hardware configuration of the device, the following section elaborates on the specific process flow and underlying mechanism of the epitaxial wafer edge morphology compensation double-sided polishing method proposed in this disclosure. This method, through the precise scheduling of the central control unit 10, reconstructs the traditional continuous polishing process into two distinct stages: a high-pressure shaping stage and a low-pressure finishing stage, which are maintained throughout by a unique flow-pressure coupling mechanism.

[0022] Before the process begins, an initialization step is performed. The central control unit 10 automatically reads the quality data of the previous batch of processed wafers 7 from the factory's host system or metrology equipment, focusing primarily on the edge morphology indicator ESFQD. See also Figure 4 If the ESFQD value of the previous batch deviates from the target window (-25nm to -15nm), the inter-batch feedback calculation module 1003 inside the central control unit 10 will be activated. For example, if the ESFQD of the previous batch was -10nm (indicating insufficient edge collapse and overly flat edges), the feedback calculation module 1003 will calculate a correction factor and automatically reduce the target removal ratio R of the current batch. target (i.e., increase the proportion of the high-pressure phase), or appropriately increase the high-pressure setpoint P. high Conversely, if ESFQD is -30nm (indicating excessive collapse), the adjustment direction is reversed. This intelligent feedback mechanism ensures long-term process stability and offsets drift caused by consumable wear. Assume the calculated parameters for the current batch are: High Pressure P... high =1600 daN, low pressure P low =1100 daN, target removal ratio R target =0.70 (i.e., low pressure removal amount / high pressure removal amount = 0.7).

[0023] Subsequently, wafer 7 is loaded into planetary gear 6, upper platen 1 closes, and the process officially begins. The first stage is high-pressure shaping (first stage). The pressure control module 1001 of the central control unit 10 instructs the pressure loading system 8 to rapidly increase the pressure to 1600 daN. This is a first pressure value far exceeding that of conventional polishing, which can range from 1500 daN to 1700 daN. Under this high pressure, the edge of wafer 7 is deeply embedded in the viscoelastic nonwoven polishing pad 3. According to the principles of contact mechanics, the normal stress on the edge area comes not only from the vertical load but also from the shear stress generated by lateral compression, resulting in a significantly higher local removal rate at the edge than in the center area. This is precisely the "shaping" or "digging" process we expect. However, the side effect of high pressure is intense frictional heat generation. If the polishing fluid flow is insufficient at this time, it will cause a local temperature spike, evaporation of water in the polishing fluid, and "dry polishing," which will not only damage the polishing pad 3 but also leave severe mechanical scratches on the surface of wafer 7. Therefore, the central control unit 10 of this disclosure synchronously activates the flow coupling module 1002, and automatically sets the polishing fluid flow rate to Q according to the formula Q = k × P (assuming k = 0.004), where Q is the polishing fluid flow rate, P is the processing pressure, k is the flow-pressure coupling coefficient, and the value of k ranges from 0.003 to 0.005 L / min·daN. high= 1600 × 0.004 = 6.4 L / min. This high-flow-rate polishing fluid serves a dual purpose: firstly, it acts as a coolant to remove high heat, and secondly, it provides sufficient chemical reactants (alkaline components and active silica abrasive) to ensure chemical-mechanical balance at high removal rates.

[0024] The non-contact online measurement module 11 monitors the thickness removal amount of wafer 7 in real time. When the detected removal amount reaches a specific percentage of the total target removal amount (e.g., 10 micrometers), a stage switch is triggered. This is based on a set ratio R. target =0.70, the removal amount in the first stage should be approximately 5.9 micrometers (10 / 1.7 ≈ 5.88). Once this value is reached, the system immediately enters a transition switch.

[0025] The stage switching process is the most delicate part of this process. The first pressure value needs to be stepped down from 1600 daN to a second pressure value of 1100 daN, which can range from 1000 daN to 1200 daN. If only the pressure is reduced while the flow rate remains unchanged (as in conventional processes, maintaining 6.4 L / min), then under low pressure, excess polishing fluid will cause chemical corrosion to dominate over mechanical grinding. In an alkaline environment, excess hydroxide ions (OH-) will anisotropically corrode the silicon lattice, resulting in microscopic etch pits on the surface, macroscopically manifested as increased haze and surface roughening. To avoid this, the central control unit 10 of this disclosure issues a flow reduction command simultaneously with the pressure reduction command within milliseconds. The proportional control valve 903 actuates rapidly, reducing the flow rate from 6.4 L / min to Q. low = 1100 × 0.004 = 4.4 L / min.

[0026] This naturally leads to the low-pressure finishing stage (stage two). In this stage, the pressure is reduced to 1100 daN, the elastic deformation of polishing pad 3 decreases, the edge encapsulation effect disappears, and the contact stress distribution returns to uniformity. The main task of this stage is to smooth the potentially steep collapsed edge profile formed in the first stage, repair any micro-scratches that may remain from high-pressure machining, and optimize the final surface roughness. Since the flow rate is also reduced simultaneously, the ratio of chemical to mechanical action is maintained constant. Thus, surface quality is finely improved without drastic changes to the morphology. This stage continues until the total removal reaches the target value (10 micrometers), at which point the process ends.

[0027] Subsequently, the upper tray 1 is raised, and wafer 7 is removed and sent to the subsequent cleaning unit. Cleaning typically includes megasonic cleaning, brushing, and spin drying to thoroughly remove residual polishing slurry particles.

[0028] To verify the actual effectiveness of the disclosed technical solution, we conducted a series of rigorous comparative experiments.

[0029] The experimental setup is as follows: a 300mm P-type polished wafer 7 was selected, with the goal of offsetting the approximately +20nm edge thickening caused by subsequent epitaxial processes.

[0030] Comparative Example 1 uses the industry-standard constant pressure and constant flow process: the pressure is kept constant at 1300 daN throughout the process, and the polishing fluid flow rate is kept constant at 5.0 L / min.

[0031] Comparative Example 2 uses a segmented pressure process without flow coupling: the pressure is reduced from 1600 daN to 1100 daN, but the flow rate is maintained at 5.0 L / min throughout.

[0032] The embodiment adopts the complete scheme of this disclosure: the pressure is reduced from 1600 daN to 1100 daN, and the flow rate is coupled from 6.4 L / min to 4.4 L / min.

[0033] The experimental results are as follows.

[0034] For Comparative Example 1, the edge ESFQD of the processed wafer 7 was approximately -2nm, exhibiting extreme flatness. However, after epitaxial growth, due to the edge thickening effect, the edge height of the final product reached +18nm. In subsequent photolithography tests, severe defocusing occurred in the edge region, resulting in an edge chip yield of only 85%. This demonstrates that the traditional "extreme flatness" strategy is ineffective in epitaxial wafer applications.

[0035] For Comparative Example 2, the edge ESFQD of the processed wafer 7 reached -23nm, successfully creating a collapsed edge. After epitaxial growth, the edge height deviation was neutralized to -3nm, and the morphology control basically met the standards. However, detailed surface inspection revealed that the average haze on the surface of wafer 7 was as high as 0.25 ppm (the conventional requirement is <0.1 ppm), and obvious orange peel texture was visible under strong light. This was due to the relatively excessive flow rate of 5.0 L / min during the low-pressure stage (1100 daN), leading to excessive chemical etching. Although this surface defect solved the morphology problem, it introduced new quality risks and was equally unacceptable.

[0036] In this embodiment, the ESFQD at the edge of wafer 7 after processing stabilized at -21.8 nm, centered within the target window. After epitaxial growth, the edge height deviation was only -1.8 nm, achieving near-perfect zero deviation. More importantly, the average haze on the surface of wafer 7 was only 0.09 ppm, with a mirror-like surface free of any orange peel or scratch defects. Photolithography testing showed that the yield of the edge chip improved to 99.5%. This result strongly demonstrates the necessity and effectiveness of the "fluid flow-pressure linear coupling" mechanism. It successfully resolved the seemingly irreconcilable contradiction between "morphology control" and "surface quality."

[0037] Furthermore, analysis of data from 1000 continuously produced wafers showed that, in the embodiment with batch-to-batch feedback control enabled, the standard deviation of the ESFQD distribution was only 1.5 nm. In contrast, without feedback control, the ESFQD exhibited a significant drift trend due to wear of the polishing pad 3, with a standard deviation as high as 5.8 nm. This demonstrates that the control logic of this disclosure possesses extremely high industrial mass production stability.

[0038] Finally, regarding the specific formulation of the polishing slurry, this embodiment uses an alkaline silica sol with a pH of 10.5, containing high-purity colloidal silica abrasive with an average particle size of 50 nm. This slurry formulation has optimal chemical compatibility with the non-woven polishing pad 3 and rheological coupling process disclosed herein. Of course, those skilled in the art can fine-tune the solid content, pH value, or additives of the polishing slurry according to specific removal rate requirements, but this does not deviate from the core technical concept of this disclosure.

[0039] Accordingly, see Figure 5 This disclosure also provides a method for double-sided polishing of epitaxial wafers with edge morphology compensation, which utilizes the aforementioned apparatus and includes: S501: Set the target edge morphology parameter range, and determine the first pressure value of the high-pressure shaping stage and the second pressure value of the low-pressure modification stage based on the range; S502: Establish the coupling function relationship between polishing fluid flow rate and processing pressure; S503: Polishing starts. The central control unit controls the pressure loading system to output the first pressure value, and at the same time controls the polishing fluid supply system to output the first flow rate value according to the coupling function relationship. S504: After maintaining the predetermined time or reaching the predetermined removal amount, the central control unit controls the pressure loading system to switch the output of the second pressure value, and at the same time automatically adjusts the output of the polishing fluid supply system to the second flow rate value according to the coupling function relationship.

[0040] In summary, this disclosure provides a comprehensive solution to the problem of edge thickening in epitaxial wafers through innovative hardware design and sophisticated intelligent process control. It not only fills the gap in the field of "topography customization" in existing double-sided polishing technology, but also provides a high-yield, high-stability processing method for advanced semiconductor manufacturing processes.

[0041] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0042] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A wafer double-sided polishing apparatus for compensating the edge morphology of epitaxial wafers, characterized in that, include: The polishing host assembly includes an upper fixed plate and a lower fixed plate disposed opposite each other, and a drive mechanism for driving the wafer to move between the upper fixed plate and the lower fixed plate; A pressure loading system for applying adjustable processing pressure to the upper and / or lower platens; A polishing slurry supply system for supplying polishing slurry to the machining interface between the upper and lower fixed plates, the polishing slurry supply system having an adjustable flow rate output function; and The central control unit is communicatively connected to both the pressure loading system and the polishing fluid supply system. The central control unit is configured to execute edge topography compensation control logic, which includes controlling the pressure loading system to output different set pressure values ​​at different processing stages, and controlling the polishing fluid flow rate value output by the polishing fluid supply system to maintain a coupled change relationship with the set pressure value output by the pressure loading system.

2. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 1, characterized in that, The associated coupling relationship is that the polishing fluid flow rate increases with the increase of the set pressure value and decreases with the decrease of the set pressure value.

3. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 2, characterized in that, The polishing fluid flow rate and the set pressure value satisfy a linear proportional relationship.

4. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 1, characterized in that, The central control unit controls the pressure loading system to perform at least two stages of pressure loading, the at least two stages including: a high-pressure shaping stage, in which a first pressure value is applied to generate a predetermined collapsed edge morphology at the wafer edge by utilizing the deformation of the polishing pad; and a low-pressure modification stage, in which a second pressure value is applied, the second pressure value being less than the first pressure value, to repair the surface micromorphology of the wafer, wherein the polishing fluid flow rate corresponding to the high-pressure shaping stage is greater than the polishing fluid flow rate corresponding to the low-pressure modification stage.

5. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 4, characterized in that, The working surfaces of the upper and lower fixed plates are covered with non-woven polishing pads, and the set pressure value of the high-pressure shaping stage is configured to cause the non-woven polishing pads to produce viscoelastic hysteresis deformation adapted to the edge of the wafer.

6. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 1, characterized in that, The central control unit also includes a feedback calculation module, which is configured to correct the set pressure value or the parameters of the coupling change relationship during the current batch processing based on the deviation between the edge morphology parameters of the wafers processed in the previous batch and the target range.

7. The epitaxial wafer edge morphology compensation type wafer double-sided polishing apparatus according to claim 1, characterized in that, The pressure loading system includes an airbag loading mechanism or a hydraulic cylinder loading mechanism, and has a millisecond-level pressure response speed.

8. A method for double-sided polishing of epitaxial wafers with edge morphology compensation, characterized in that, The method is performed using the apparatus according to any one of claims 1 to 7, the method comprising: Set the target edge morphology parameter range, and determine the first pressure value of the high-pressure shaping stage and the second pressure value of the low-pressure modification stage based on this range; Establish a coupling function relationship between polishing fluid flow rate and processing pressure; When polishing is started, the central control unit controls the pressure loading system to first output the first pressure value, and at the same time controls the polishing fluid supply system to output the first flow rate value according to the coupling function relationship. After maintaining the predetermined time or reaching the predetermined removal amount, the central control unit controls the pressure loading system to switch the output of the second pressure value, and at the same time automatically adjusts the output of the polishing fluid supply system to the second flow rate value according to the coupling function relationship.

9. The epitaxial wafer edge morphology compensation type double-sided polishing method according to claim 8, characterized in that, The first pressure value ranges from 1500 daN to 1700 daN, and the second pressure value ranges from 1000 daN to 1200 daN.

10. The epitaxial wafer edge morphology compensation type wafer double-sided polishing method according to claim 8, characterized in that, The coupling function relationship satisfies: Q = k × P, where Q is the polishing fluid flow rate, P is the processing pressure, k is the flow-pressure coupling coefficient, and the value of k ranges from 0.003 to 0.005 L / min · daN.

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