A wafer grinding and polishing adjustment control system based on tension sensor

Abstract

The present invention relates to the field of wafer processing and discloses a tension sensor-based wafer grinding and polishing adjustment and control system. The system comprises a processing pressure acquisition module, which acquires the gravity of a weight and, based on the tension sensor, collects the tension of an electric cylinder in real time, calculates the processing pressure using a formula, and simultaneously collects the wafer grinding state parameters in real time. A processing pressure stability analysis module comprises a first analysis unit and a second analysis unit: the first analysis unit calculates the cumulative change in processing pressure within a preset monitoring period and compares it with a change threshold, issuing an alarm signal; the second analysis unit inputs the grinding state parameters into a grinding state model, analyzes the grinding state values, and reversely evaluates the grinding disk state; the adjustment control module adjusts the electric cylinder tension based on the first analysis unit and determines whether to replace the grinding disk based on the second analysis unit. The present invention achieves precise monitoring and stability control of processing pressure, effectively evaluates the grinding disk state, and improves the quality and efficiency of wafer grinding and polishing.

Description

Technical Field

[0001] The present invention relates to the field of wafer processing, and in particular to a wafer grinding and polishing adjustment and control system based on a tension sensor. Background Art

[0002] In the semiconductor wafer grinding and polishing process, the accuracy and stability of the processing pressure are key factors in determining the overall flattening effect of the wafer surface. Traditional control systems generally rely on direct contact pressure sensors for real-time monitoring. However, this technology has inherent drawbacks as follows:

[0003] 1. During the grinding and polishing process, the corrosive chemical mechanical polishing fluid can easily penetrate into the sensor's sensitive components, causing the measurement signal to drift or permanently fail, causing the processing pressure feedback value to deviate seriously from the actual physical quantity;

[0004] 2. When the grinding wheel causes abnormal pressure fluctuations due to local wear or thermal deformation, the contact sensing unit is affected by the hysteresis of the mechanical transmission path and is unable to capture the instantaneous pressure mutation in time, resulting in regional over-grinding or under-grinding on the wafer surface;

[0005] 3. Existing technologies lack the ability to online evaluate the working status of grinding discs and can only inspect the disc surface flatness and groove integrity by periodically shutting down and disassembling the equipment. This passive maintenance mode not only reduces equipment utilization, but may also cause batch wafer yield declines due to failure to replace failed grinding discs in a timely manner. Summary of the Invention

[0006] The object of the present invention is to provide a wafer grinding and polishing adjustment and control system based on a tension sensor to solve at least one of the above technical problems.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A wafer grinding and polishing adjustment and control system based on a tension sensor, comprising:

[0009] The processing pressure acquisition module obtains the weight of the weight and uses the tension sensor to collect the electric cylinder tension in real time. The processing pressure is calculated using the formula: processing pressure = weight of the weight - electric cylinder tension; and the polishing status parameters of the wafer are collected in real time.

[0010] Processing pressure stability analysis module, including:

[0011] The first analysis unit obtains the cumulative change K1 of the processing pressure within a preset monitoring period, compares the cumulative change K1 with the change threshold K0 determined by historical data analysis, and issues an alarm signal when K1 ≥ K0;

[0012] The second analysis unit inputs the wafer grinding state parameters into the grinding state model for analysis to obtain a grinding state value; and reversely evaluates the state of the grinding disc based on the grinding state value;

[0013] The adjustment control module adjusts the tension of the electric cylinder based on the alarm signal of the first analysis unit, and determines whether the grinding disc needs to be replaced based on the reverse evaluation result of the second analysis unit.

[0014] As a further technical solution, the process of obtaining the cumulative change K1 in the first analysis unit is:

[0015] Obtain the curve of processing pressure changing with time in each monitoring cycle ;

[0016] Based on historical data analysis, a standard curve of processing pressure over time in each monitoring period is obtained ;

[0017] Calculate the cumulative change ;

[0018] in, The start and end time of the monitoring period.

[0019] As a further technical solution, the process of obtaining the cumulative change K1 in the first analysis unit is:

[0020] In each monitoring cycle, the sampling period Continuously obtain processing pressure sequence ;

[0021] Calculate the cumulative change ;

[0022] in, represents the i-th processing pressure.

[0023] As a further technical solution, the grinding state parameters include: online measurement value of wafer thickness, grinding disc vibration spectrum and polishing liquid flow rate.

[0024] As a further technical solution, the grinding state model is expressed as:

[0025] ;

[0026] in, is the standard deviation of the online measurement value of wafer thickness during the monitoring period, is the average value of the online measurement value of the wafer thickness during the monitoring period, is the RMS value of the grinding disc vibration spectrum, is the no-load reference vibration value of the equipment, is the real-time polishing liquid flow rate, Set the optimal flow rate for the process, 、 are the upper and lower limits of the traffic security threshold respectively, 、 As a further technical solution, when the regulating control module responds to the alarm signal:

[0027] By increment Adjust the tension of the electric cylinder in stages. ,in is the compensation coefficient;

[0028] Recalculate K1 after each adjustment until K1 < K0.

[0029] As a further technical solution, the process of reversely evaluating the grinding disc state through the grinding state value includes:

[0030] Obtain the initial life reference value L0 (determined based on historical data) and life attenuation coefficient g of the grinding disc;

[0031] By formula: Calculate the remaining life index of the grinding disc ;

[0032] in, is the initial threshold of the grinding state, It is the grinding state failure threshold.

[0033] As a further technical solution, when the remaining life index of the grinding disc is > Preset first warning threshold When the wear of the grinding disc is assessed to be low, continue to use it;

[0034] When the second warning threshold is preset ≤ ≤preset first warning threshold When inspecting the grinding disc, assess whether there is local wear or performance degradation and arrange maintenance;

[0035] when <Preset second warning threshold When the grinding wheel is assessed to have reached its service life limit due to wear, deformation or groove damage, a replacement instruction is automatically generated and a shutdown protocol is triggered.

[0036] As a further technical solution, the compensation coefficient λ decays as the number of adjustments increases, and the decay function is: ,in is the number of adjustments, is the decay constant, is the initial value.

[0037] Beneficial effects of the present invention:

[0038] (1) The present invention reconstructs processing pressure monitoring through a tension sensor, fundamentally avoiding the risk of corrosion of traditional contact sensors by chemical mechanical polishing liquid; the tension sensor collects the tension of the electric cylinder away from the corrosive environment, and calculates the real processing pressure by combining it with the gravity of the weight. Processing pressure = weight - tension of the electric cylinder, which effectively eliminates the problems of measurement signal drift and sensor failure; not only ensures the physical authenticity of the pressure feedback value, but also realizes early diagnosis of pressure fluctuations through real-time cumulative change analysis; when the abnormal fluctuation exceeds the historical threshold, it immediately triggers an alarm and starts adjustment, suppressing regional over-grinding or under-grinding defects on the wafer surface, and improving the global flattening accuracy and product yield.

[0039] (2) The dual-path analysis mechanism of the present invention deeply couples the processing pressure stability control with the grinding wheel state assessment. The first analysis unit drives a progressive adjustment strategy with an adjustable compensation coefficient by dynamically calculating the pressure accumulation deviation, wherein the compensation coefficient decays exponentially with the number of adjustments to avoid overshoot and achieve rapid convergence. At the same time, the second analysis unit integrates the wafer thickness fluctuation rate, vibration spectrum and polishing liquid flow offset to construct a nonlinear grinding state model. The degradation assessment is forced to be triggered by the vibration term zeroing design, accurately capturing the hidden dangers of local wear or thermal deformation of the grinding wheel, and providing data support for proactive maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described below with reference to the accompanying drawings.

[0041] Figure 1 This is a logic principle diagram of the present invention. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] See also Figure 1 As shown, the present invention is a wafer grinding and polishing adjustment control system based on a tension sensor, comprising:

[0044] The processing pressure acquisition module obtains the weight of the weight and uses the tension sensor to collect the electric cylinder tension in real time. The processing pressure is calculated using the formula: processing pressure = weight of the weight - electric cylinder tension; and the polishing status parameters of the wafer are collected in real time.

[0045] Processing pressure stability analysis module, including:

[0046] The first analysis unit obtains the cumulative change K1 of the processing pressure within a preset monitoring period, compares the cumulative change K1 with the change threshold K0 determined by historical data analysis, and issues an alarm signal when K1 ≥ K0;

[0047] The second analysis unit inputs the wafer grinding state parameters into the grinding state model for analysis to obtain a grinding state value; and reversely evaluates the state of the grinding disc based on the grinding state value;

[0048] The adjustment control module adjusts the tension of the electric cylinder based on the alarm signal of the first analysis unit, and determines whether the grinding disc needs to be replaced based on the reverse evaluation result of the second analysis unit.

[0049] In this embodiment, a processing pressure acquisition module utilizes a tension sensor to collect the electric cylinder tension in real time and calculates the processing pressure based on the weight's gravity. This changes the traditional monitoring method that relies on direct-contact pressure sensors, effectively avoiding the problem of measurement signal drift or failure caused by corrosive polishing fluid seeping into the sensor, making processing pressure monitoring more accurate and reliable. Furthermore, the module collects wafer polishing state parameters in real time, providing a rich data foundation for subsequent analysis.

[0050] The first analysis unit in the processing pressure stability analysis module can promptly detect abnormal changes in processing pressure and issue an alarm signal. The second analysis unit reversely evaluates the grinding wheel status through the grinding state model, thus having the ability to comprehensively analyze the processing process.

[0051] Based on the analysis results, the adjustment control module adjusts the electric cylinder tension and determines whether the grinding wheel needs to be replaced, thereby realizing precise control of the processing pressure and effective management of the grinding wheel status. The above design improves the accuracy and stability of processing pressure monitoring, avoids the problem of over-grinding or under-grinding of the wafer surface due to inaccurate pressure monitoring, and can also evaluate the grinding wheel status online, changing the traditional passive maintenance mode, improving equipment utilization rate, reducing the risk of batch wafer yield decline caused by grinding wheel failure, and improving the quality and efficiency of wafer grinding and polishing from multiple dimensions.

[0052] The process of obtaining the cumulative change K1 in the first analysis unit is as follows:

[0053] Obtain the curve of processing pressure changing with time in each monitoring cycle ;

[0054] Based on historical data analysis, a standard curve of processing pressure over time in each monitoring period is obtained ;

[0055] Calculate the cumulative change ;

[0056] in, The start and end time of the monitoring period.

[0057] In this embodiment, the curve of the change of the processing pressure over time in each monitoring period and the standard curve obtained based on the historical data analysis are obtained, and then the absolute value of the difference between the two is integrated. The cumulative change is calculated to comprehensively and meticulously reflect the degree of deviation of the processing pressure from the standard state during the entire monitoring period. The above formula takes into account the entire process of the processing pressure changing over time, rather than just focusing on the value at a single time point, and can capture the trend of the processing pressure change and the overall fluctuation. When the cumulative change exceeds the change threshold, an alarm signal is issued to promptly remind the operator of abnormal processing pressure so that timely measures can be taken to adjust it and ensure the stability of the processing pressure, thereby ensuring the stability and consistency of the wafer grinding and polishing process, avoiding wafer surface quality problems caused by pressure fluctuations, and providing a strong guarantee for improving the quality of wafer grinding and polishing.

[0058] The process of obtaining the cumulative change K1 in the first analysis unit is as follows:

[0059] In each monitoring cycle, the sampling period Continuously obtain processing pressure sequence ;

[0060] Calculate the cumulative change ;

[0061] in, represents the i-th processing pressure.

[0062] In this embodiment, the processing pressure is continuously collected at a fixed sampling period in each monitoring period, which can capture the instantaneous changes of the processing pressure at a high frequency and detect the subtle fluctuations of the pressure in time; Calculating the sum of the absolute values ​​of the differences between adjacent pressure values ​​highlights the amplitude and frequency of changes in the processing pressure in a short period of time, and can keenly reflect the dynamic changes in the processing pressure. This method is simple to calculate and can quickly obtain the cumulative change, which is convenient for timely analysis and judgment. When the cumulative change exceeds the threshold, an alarm is issued, which can quickly respond to abnormal changes in the processing pressure, adjust the electric cylinder tension in time, and effectively control the stability of the processing pressure. It can also adapt to the rapid changes in pressure that may occur during the processing process, improve the response speed and control accuracy to abnormal processing pressure, ensure that the wafer grinding and polishing process is carried out under stable pressure conditions, and is conducive to improving the processing quality and production efficiency of the wafer.

[0063] The grinding state parameters include: online measurement value of wafer thickness, grinding disc vibration spectrum and polishing liquid flow rate.

[0064] The expression of the grinding state model is:

[0065] ;

[0066] in, is the standard deviation of the online measurement value of wafer thickness during the monitoring period, is the average value of the online measurement value of the wafer thickness during the monitoring period, is the RMS value of the grinding disc vibration spectrum, The reference vibration value of the equipment under no-load condition is the average value of 10 measurements under no-load condition. is the real-time polishing liquid flow rate, Set the optimal flow rate for the process, 、 are the upper and lower limits of the traffic security threshold respectively, 、 is the weight coefficient, ≥1.2, .pass Quantify the wafer thickness fluctuation rate. The larger the value, the worse the surface uniformity. This allows the statistical fluctuation to be converted into a status indicator. To achieve zero return when vibration exceeds the limit, forcibly trigger degradation assessment to build nonlinear failure boundaries; Get the absolute offset of the flow rate to capture positive or negative anomalies.

[0067] In this embodiment, the online measurement value of wafer thickness can directly reflect the actual effect of wafer grinding and polishing. By analyzing it, the uniformity of wafer thickness and processing progress can be understood; the vibration spectrum of the grinding disk contains rich information about the working state of the grinding disk. Local wear, thermal deformation and other problems of the grinding disk will directly affect its vibration characteristics. By analyzing the vibration spectrum, potential problems of the grinding disk can be discovered in time; the polishing liquid flow rate is an important process parameter in the grinding and polishing process, and its stability has an important influence on the grinding and polishing effect. Real-time monitoring of the polishing liquid flow rate can ensure that the supply of polishing liquid meets the process requirements; the grinding state value is obtained by combining and calculating multiple parameters, which can comprehensively and comprehensively reflect the actual state of the grinding process.

[0068] Among them, the ratio of the standard deviation to the mean of the wafer thickness online measurement value is used to quantify the wafer thickness fluctuation rate, which can accurately reflect the uniformity of the wafer thickness. The larger the value, the worse the surface uniformity. The statistical fluctuation is converted into an intuitive status indicator, which is convenient for evaluating the wafer processing quality. It achieves zero return when vibration exceeds the limit, forcibly triggers degradation assessment, and constructs a nonlinear failure boundary, which can promptly detect problems that may occur in the grinding wheel due to abnormal vibration. By calculating the ratio of the absolute offset between the real-time polishing liquid flow rate and the process-set optimal flow rate and the difference between the upper and lower limits of the flow safety threshold, the absolute flow offset is obtained, which can accurately detect positive or negative anomalies in the polishing liquid flow rate.

[0069] Weight coefficient 、 The settings can be adjusted according to actual process requirements, making the model more adaptable and flexible; the grinding state value obtained by the model can more accurately reflect the actual situation of the grinding process, and then more reliably reversely evaluate the state of the grinding wheel, providing a basis for the maintenance and replacement of the grinding wheel, ensuring the stability of the wafer grinding and polishing process, and improving the processing quality and production efficiency of the wafer.

[0070] When the regulation control module responds to the alarm signal:

[0071] By increment Adjust the tension of the electric cylinder in stages. ,in is the compensation coefficient;

[0072] Recalculate K1 after each adjustment until K1 < K0.

[0073] In this embodiment, when the machining pressure stability analysis module issues an alarm signal, the adjustment control module adjusts the electric cylinder tension in stages, based on increments determined by the compensation coefficient multiplied by the difference between the cumulative change and the change threshold. This staged adjustment allows for gradual adjustments based on the severity of the machining pressure anomaly, avoiding disruptions to the machining process caused by a single, large adjustment, ensuring a smoother and more controllable adjustment process. After each adjustment, the cumulative change is recalculated until it is less than the change threshold, ensuring the effectiveness of the adjustment and quickly restoring the machining pressure to a stable state.

[0074] The process of reversely evaluating the grinding disc state through the grinding state value includes:

[0075] Obtain the initial life reference value L0 of the grinding disc (determined based on historical data) and the life attenuation coefficient g, >0, based on experimental calibration;

[0076] By formula: Calculate the remaining life index of the grinding disc ;

[0077] in, is the initial threshold of the grinding state, corresponding to the normal working state, It is the grinding state failure threshold, corresponding to the grinding disc scrap state.

[0078] In this embodiment, by first obtaining the initial life reference value of the grinding wheel determined based on historical data and the life attenuation coefficient calibrated by experiments, and then using the formula to calculate the remaining life index of the grinding wheel, a quantitative relationship is established between the grinding state value and the remaining life of the grinding wheel, and the wear degree and remaining life of the grinding wheel can be accurately evaluated by the change of the grinding state; the remaining life index obtained by calculation can intuitively reflect the state of the grinding wheel, and provide a clear basis for the maintenance and replacement of the grinding wheel. The above-mentioned method of online evaluation of the grinding wheel state changes the traditional passive maintenance mode that relies on regular shutdown and disassembly inspection. It can timely discover problems with the grinding wheel and arrange maintenance or replacement at the appropriate time, thereby improving equipment utilization rate, reducing the risk of batch wafer yield decline due to grinding wheel failure, reducing production costs, and improving production efficiency and product quality.

[0079] When the remaining life index of the grinding disc > Preset first warning threshold When the wear of the grinding disc is assessed to be low, continue to use it;

[0080] When the second warning threshold is preset ≤ ≤preset first warning threshold When inspecting the grinding disc, assess whether there is local wear or performance degradation and arrange maintenance;

[0081] when <Preset second warning threshold When the grinding wheel reaches the limit of its service life due to wear, deformation or groove damage, it will automatically generate a replacement instruction and trigger the shutdown protocol. Set to 60%~80% of the initial life reference value L0; second warning threshold Set to 30%~50% of the initial life reference value L0;

[0082] First warning threshold and the second warning threshold The method of determining is:

[0083] Collect the full life cycle data of the same type of grinding disc in typical wafer processing technology, including the remaining life index corresponding to the normal use stage, local wear stage, and failure stage , determine the critical value of each stage through statistical analysis. For example: Statistical history of the turning point of the grinding disc from "normal use" to "need maintenance" value, as ; Count the turning points from "maintenance required" to "must be replaced" value, as .

[0084] In this embodiment, when the remaining life index is greater than the preset first warning threshold, it is assessed that the wear degree of the grinding disc is low and it can continue to be used, thereby avoiding the waste caused by premature replacement of the grinding disc and improving the utilization rate of the grinding disc;

[0085] When the remaining life index is between the preset second warning threshold and the first warning threshold, it is assessed that the grinding disc has local wear or performance degradation, and maintenance is arranged. The necessary maintenance can be performed on the grinding disc in time to prevent the problem from further expansion and ensure the performance and service life of the grinding disc;

[0086] When the remaining life index is less than the preset second warning threshold, it is assessed that the grinding wheel has reached its service life limit, and a replacement instruction is automatically generated and a shutdown protocol is triggered, avoiding wafer processing quality problems and equipment failures caused by excessive wear of the grinding wheel, and ensuring the safety and stability of the production process.

[0087] The compensation coefficient λ decays as the number of adjustments increases, and the decay function is: ,in is the number of adjustments, is the decay constant, It is the initial value, determined based on historical data or expert experience.

[0088] In this embodiment, the compensation coefficient attenuation function gradually decreases with the number of adjustments, taking into account the actual conditions of the machining process. During machining, when abnormal machining pressure requires adjustment of the electric cylinder tension, a larger compensation coefficient may be initially required to quickly adjust the pressure. However, as the number of adjustments increases, the machining pressure may gradually approach a stable state. At this time, a smaller compensation coefficient allows for more precise adjustment, avoiding new interference with the machining process caused by excessive adjustment, and making the adjustment process smoother and more precise. This attenuation design can adapt to the adjustment needs at different stages of the machining process, improving the adaptability and stability of the system.

[0089] It should be noted that the calculation formulas and various parameters involved in the calculations in the present invention have been dimensionally processed in advance, and the process of dimensionless processing is well known in the industry and will not be described here.

[0090] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A wafer grinding and polishing adjustment and control system based on a tension sensor, characterized in that: include: The processing pressure acquisition module obtains the weight of the heavy object and collects the tension of the electric cylinder in real time based on the tension sensor, and calculates the processing pressure through the formula: processing pressure = weight of the heavy object - tension of the electric cylinder; And real-time collection of wafer grinding status parameters; Processing pressure stability analysis module, including: The first analysis unit obtains the cumulative change K1 of the processing pressure within a preset monitoring period, compares the cumulative change K1 with the change threshold K0 determined by historical data analysis, and issues an alarm signal when K1 ≥ K0; The second analysis unit inputs the wafer grinding state parameters into the grinding state model for analysis to obtain a grinding state value; and reversely evaluates the state of the grinding disc based on the grinding state value; The grinding state parameters include: online measurement value of wafer thickness, grinding disc vibration spectrum and polishing liquid flow rate; The expression of the grinding state model is: ； in, is the standard deviation of the online measurement value of wafer thickness during the monitoring period, is the average value of the online measurement value of wafer thickness during the monitoring period, is the RMS value of the grinding disc vibration spectrum, is the no-load reference vibration value of the equipment, is the real-time polishing liquid flow rate, Set the optimal flow rate for the process, 、 are the upper and lower limits of the traffic security threshold respectively, 、 is the weight coefficient; The process of reversely evaluating the grinding disc state through the grinding state value includes: Obtaining the initial life reference value L0 and life attenuation coefficient g of the grinding disc; wherein L0 is determined based on historical data; By formula: Calculate the remaining life index of the grinding disc ; in, is the initial threshold of the grinding state, is the failure threshold of the grinding state; The adjustment control module adjusts the tension of the electric cylinder based on the alarm signal of the first analysis unit, and determines whether the grinding disc needs to be replaced based on the reverse evaluation result of the second analysis unit.

2. The wafer grinding and polishing adjustment and control system based on a tension sensor according to claim 1 is characterized in that: The process of obtaining the cumulative change K1 in the first analysis unit is as follows: Obtain the curve of processing pressure changing with time in each monitoring cycle ; Based on historical data analysis, a standard curve of processing pressure over time in each monitoring period is obtained ; Calculate the cumulative change ; in, The start and end time of the monitoring period.

3. The wafer grinding and polishing adjustment and control system based on a tension sensor according to claim 1 is characterized in that: The process of obtaining the cumulative change K1 in the first analysis unit is as follows: In each monitoring cycle, the sampling period Continuously obtain processing pressure sequence ; Calculate the cumulative change ; in, represents the i-th processing pressure.

4. The wafer grinding and polishing adjustment and control system based on a tension sensor according to claim 1, characterized in that: When the regulation control module responds to the alarm signal: By increment Adjust the tension of the electric cylinder in stages. ,in is the compensation coefficient; Recalculate K1 after each adjustment until K1 < K0.

5. The wafer grinding and polishing adjustment and control system based on a tension sensor according to claim 1, characterized in that: When the remaining life index of the grinding disc > Preset first warning threshold When the wear of the grinding disc is assessed to be low, continue to use it; When the second warning threshold is preset ≤ ≤preset first warning threshold When inspecting the grinding disc, assess whether there is local wear or performance degradation and arrange maintenance; when <Preset second warning threshold When the grinding wheel is assessed to have reached its service life limit due to wear, deformation or groove damage, a replacement instruction is automatically generated and a shutdown protocol is triggered.

6. The wafer grinding and polishing adjustment and control system based on a tension sensor according to claim 4, characterized in that: The compensation coefficient λ decays as the number of adjustments increases, and the decay function is: ,in is the number of adjustments, is the decay constant, is the initial value.

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