Multi-wire saw process parameter on-line control method

Abstract

The application provides a kind of multi-wire cutting process parameter on-line control method, comprising: adding working fluid to cutting chamber and starting wire cutting machine to make wire cutting machine drive wire cutting material;Multiple repeated monitoring of cutting chamber liquid inlet temperature and liquid outlet temperature, and obtain the original instantaneous temperature difference of working fluid;Smooth instantaneous temperature difference is averaged in each mean sampling period to obtain multiple average temperature differences corresponding to multiple mean sampling periods;If it is higher than the preset instantaneous temperature difference upper limit threshold value in a short time fluctuation time interval and lasts at least 7 seconds, the cutting parameters of wire cutting machine are adjusted to reduce according to the over-limit degree grading;If it is out of the preset temperature difference allowable fluctuation interval in a long-term drift time interval and lasts at least 5 minutes, comprehensive correction adjustment is carried out on process parameters to make the temperature difference allowable fluctuation interval fall back.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an online control method for multi-wire dicing process parameters. Background Technology

[0002] When using a multi-wire cutting system to cut materials, working fluids (including cutting fluid and slurry) are required to cool the cutting wires and materials to ensure stable heat load on the multi-wire cutting system and materials. This prevents abnormal fluctuations in heat load from affecting cutting efficiency and product quality. Therefore, it is necessary to monitor the inlet and outlet temperatures of the cutting chamber and judge the changes in heat load based on the temperature difference between the two.

[0003] Existing multi-wire cutting systems lack the ability to distinguish between short-term abrupt changes and long-term gradual changes in heat load, and can only achieve simple temperature feedback control through limited temperature adjustment methods, such as reducing the inlet temperature or increasing the working fluid flow rate when the heat load increases. These temperature adjustment methods have limited effectiveness and cannot fundamentally eliminate the causes of abnormal heat load fluctuations. Summary of the Invention

[0004] In view of this, the present invention provides an online control method for multi-wire cutting process parameters, which aims to adopt adaptive parameter control strategies for short-term sudden changes and long-term gradual changes in heat load, thereby mitigating abnormal fluctuations in heat load and ensuring cutting efficiency and product quality.

[0005] The online control method for multi-wire cutting process parameters of the present invention is used to control the process parameters of multi-wire cutting operations. These process parameters include the cutting parameters of the wire cutting machine and the inlet temperature of the working fluid. The cutting parameters include the linear velocity of the wire and the feed rate of the material, and the method includes:

[0006] Add working fluid to the cutting chamber and start the wire cutter to drive the wire to cut the material;

[0007] Repeatedly monitor the inlet temperature of the cutting chamber. and liquid outlet temperature And obtain the original instantaneous temperature difference of the working fluid. , ;

[0008] For the original instantaneous temperature difference Perform filtering operations to obtain a smooth instantaneous temperature difference. ;

[0009] Smoothed instantaneous temperature difference within each mean sampling period Calculate the mean to obtain multiple average temperature differences corresponding to multiple mean sampling periods. ;

[0010] If a smooth, instantaneous temperature difference occurs within a short-term fluctuation range... Exceeding the preset upper limit threshold for instantaneous temperature difference And continue for at least 7 seconds, then based on the smooth instantaneous temperature difference Adjust the cutting parameters of the wire cutter according to the degree of over-limit to reduce ;

[0011] If an average temperature difference occurs within a long drift period... If the temperature difference exceeds the preset allowable fluctuation range and persists for at least 5 minutes, then comprehensive corrective adjustments will be made to the process parameters to ensure that... The temperature difference will fall back to the allowable fluctuation range.

[0012] Among them, the upper limit of the short-term fluctuation duration range is no greater than the lower limit of the long-term drift duration range.

[0013] This invention alleviates short-term abrupt changes in heat load by implementing graded adjustment of the cutting parameters of the wire cutter, and alleviates long-term drift anomalies in heat load by implementing comprehensive correction process parameters. Therefore, compared with the prior art, this invention can adopt adaptive parameter control strategies for both short-term abrupt changes and long-term gradual changes in heat load, and fundamentally eliminate the causes of abnormal heat load fluctuations, thereby alleviating abnormal heat load fluctuations to ensure cutting efficiency and product quality.

[0014] In some embodiments, the comprehensive correction adjustment of the process parameters includes:

[0015] First, adjust the process parameters in multiple steps to achieve... It is falling back into the permissible range of temperature fluctuations;

[0016] Then If the temperature difference still exceeds the allowable fluctuation range, the cutting parameters need to be deeply intervened to make It is falling back into the permissible range of temperature fluctuations;

[0017] Then in If the temperature difference still exceeds the permissible fluctuation range, an off-site emergency alert will be triggered.

[0018] In some embodiments, the multiple step-by-step adjustment of process parameters includes:

[0019] Ensure the inlet temperature of the working fluid during process parameter adjustment. Between 20.5°C and 22.5°C;

[0020] The above When the temperature difference still exceeds the allowable fluctuation range, the deep intervention cutting parameters include: ensuring the inlet temperature during the deep intervention cutting process. Between 20.5°C and 22.5°C.

[0021] In some embodiments, the multiple step-by-step adjustment of process parameters includes:

[0022] Ensure the inlet temperature set value is met. Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. The set value of liquid inlet temperature each time The adjustment range shall not be less than 0.04℃ and not greater than 0.08℃;

[0023] exist > In this case, control the heat exchange unit to operate in heating mode and / or increase the heating power of the heat exchange unit to make near ;

[0024] exist < In this case, control the heat exchange unit to operate in cooling mode and / or increase the cooling capacity of the heat exchange unit to make near .

[0025] In some embodiments, the step of ensuring the inlet temperature setpoint is... Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. include:

[0026] After adjusting the inlet temperature setting value Afterwards, wait 4-8 minutes and observe. Is it within the allowable temperature fluctuation range?

[0027] like Maintain the inlet temperature setpoint within the allowable temperature difference fluctuation range. ;

[0028] like If the temperature fluctuation is outside the allowable range, continue to adjust the inlet temperature setpoint. until Until the temperature difference falls within the permissible fluctuation range;

[0029] After repeatedly adjusting the inlet temperature setting value During the process, the inlet temperature setpoint The required adjustment range increases sequentially.

[0030] In some implementations, the depth intervention cutting parameters include:

[0031] Reduce the wire speed and / or the material feed rate by 15% to 30%.

[0032] In some embodiments, the multiple step-by-step adjustment of process parameters includes:

[0033] according to The material feed rate was adjusted multiple times, every 3-8 minutes, and the trend of change was examined. Does it fall within the allowable temperature fluctuation range?

[0034] like If the temperature falls within the allowable fluctuation range, the material feed rate will be maintained.

[0035] like If the temperature difference exceeds the upper limit of the allowable fluctuation range, the feed rate of the material should be reduced by 0.5% to 2%.

[0036] like If the temperature difference is below the lower limit of the allowable fluctuation range, the feed rate of the material should be increased by 0.5% to 2%.

[0037] In some embodiments, the cutting parameters of the graded adjustable wire cutter include:

[0038] If 0℃ < ( - If the temperature is ≤0.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate, but the reduction should not exceed 5%.

[0039] If 0.5℃ < ( - If the temperature is ≤1.0℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 5%~10%.

[0040] If 1.0℃ < ( - If the temperature is ≤1.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 10%~20%.

[0041] If ( - If the temperature exceeds 1.5°C and remains above 7 seconds, reduce the wire speed and / or the material feed rate by more than 20%.

[0042] In some embodiments, the repeated monitoring of the liquid inlet temperature of the cutting chamber... and liquid outlet temperature And obtain the original instantaneous temperature difference of the working fluid. , include:

[0043] The inlet temperature was monitored repeatedly at the same sampling interval. and liquid outlet temperature The sampling interval is the original instantaneous temperature difference. The sampling interval;

[0044] The original instantaneous temperature difference Perform filtering operations to obtain a smooth instantaneous temperature difference. include:

[0045] Multiple raw instantaneous temperature differences are filtered using an integer multiple of the sampling interval as the first filtering window. Filtering is performed to obtain multiple smooth instantaneous temperature differences. ;

[0046] The sampling interval is not less than 0.2 seconds and not more than 5 seconds, the first filtering window is 5 to 20 seconds, and the mean sampling period is 10 to 15 minutes.

[0047] In some implementations, the initial instantaneous temperature difference of the working fluid is obtained. , include:

[0048] Substitute into the calculation formula In and There is a preset dwell time interval. , The measured time is compared to The measured time was late .

[0049] In some embodiments, the method further includes:

[0050] If the instantaneous temperature difference is smoothed Within the preset allowable temperature difference fluctuation range, and the average temperature difference If the temperature difference is within the allowable fluctuation range, the current multi-wire cutting process parameters will be maintained.

[0051] and / or,

[0052] The duration of the short-term fluctuation is 2 to 3 minutes, and the duration of the long-term drift is 10 to 30 minutes.

[0053] and / or,

[0054] The upper limit threshold of instantaneous temperature difference The temperature shall not be lower than 3°C, and the allowable temperature difference fluctuation range is 1.7°C to 2.3°C. Detailed Implementation

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] This invention provides an online control method for multi-wire cutting process parameters. The multi-wire cutting operation includes cutting crystal materials to obtain wafers using a wire cutter and diamond wire, and cutting other materials using a wire cutter and other types of wire. The wire cutter, wire, cutting chamber, and process parameter control unit together constitute a multi-wire cutting system. The multi-wire cutting process parameters include, but are not limited to, the cutting parameters of the wire cutter and the inlet temperature of the working fluid. The cutting parameters of a wire cutting machine include, but are not limited to, the linear speed of the wire, the feed rate of crystalline materials or other materials (feed rate is also known as table speed). The working fluid includes cutting fluid and slurry, and the specific selection depends on the type of multi-wire cutting operation and the material being cut.

[0058] When cutting crystals using a multi-wire dicing system, a working fluid is needed not only to improve cutting efficiency and accelerate chip removal, but also to cool the wire and the material being cut. Taking multi-wire dicing of crystal materials as an example, when the thermal load of the multi-wire dicing system and the crystal is abnormal or fluctuates significantly, the cutting efficiency will be affected, and the geometric accuracy of the final wafer product will decrease, resulting in a lower wafer product yield. Geometric accuracy includes total thickness variation (TTV), warp, bow, surface quality, and internal cracks. Therefore, it is necessary to monitor and control the temperature of the working fluid during the cutting process. However, existing multi-wire dicing systems do not have the ability to distinguish between short-term abrupt changes and long-term gradual changes in thermal load, and the control effect of the working fluid temperature is generally poor and it is difficult to eliminate the causes of abnormal fluctuations in thermal load.

[0059] Therefore, the online control method for multi-wire EDM process parameters of the present invention includes:

[0060] Step A: Add working fluid to the cutting chamber and start the wire cutter to drive the wire to cut the material;

[0061] Step B: Repeatedly monitor the inlet temperature of the cutting chamber. and the outlet temperature And obtain the original instantaneous temperature difference of the working fluid. , ;

[0062] Step C: Assess the original instantaneous temperature difference. Perform filtering operations to obtain a smooth instantaneous temperature difference. ;

[0063] Step D: Smooth the instantaneous temperature difference within each mean sampling period. Calculate the mean to obtain multiple average temperature differences corresponding to multiple mean sampling periods. ;

[0064] Step E: If a smooth instantaneous temperature difference occurs within a short-term fluctuation range... Exceeding the preset upper limit threshold for instantaneous temperature difference And continue for at least 7 seconds, then based on the smooth instantaneous temperature difference Adjust the cutting parameters of the wire cutter according to the degree of over-limit to reduce ;

[0065] Step F: If an average temperature difference occurs within a long drift time interval... If the temperature difference exceeds the preset allowable fluctuation range and persists for at least 5 minutes, then comprehensive corrective adjustments will be made to the process parameters to ensure that... The temperature difference will fall back to the allowable fluctuation range.

[0066] Among them, the upper limit of the short-term fluctuation duration range is no greater than the lower limit of the long-term drift duration range.

[0067] The material in step A above can be a semiconductor material such as monocrystalline silicon or polycrystalline silicon, or a photovoltaic material such as silicon ingot or silicon rod. The online control method for multi-wire cutting process parameters of this invention is particularly suitable for diamond wire cutting and slurry wire cutting operations. Steps B through F are all performed during step A; therefore, the technical solution of this invention is an online process parameter control method, that is, the technical solution of this invention is implemented during the production process of cutting materials to obtain products.

[0068] In step B above, the liquid inlet temperature of the cutting chamber is... and liquid outlet temperature Repeated monitoring can be performed at different or the same sampling intervals. If any two adjacent inlet temperatures... If the time span of each sampling time is n, then the temperatures of any two adjacent outlets are... The time span for each sampling point is n, where n is the original instantaneous temperature difference. The sampling interval.

[0069] In step C, smoothing the instantaneous temperature difference The reaction process generates heat in real time during multi-wire cutting operations, addressing a series of initial instantaneous temperature differences. The filtering algorithm can be smoothing filtering, low-pass filtering, exponentially weighted moving average filtering, or Kalman filtering. Taking smoothing filtering as an example, the filtering window can be selected first, and then a portion of the original instantaneous temperature difference can be filtered. The data is evenly distributed across multiple filter windows, with each filter window containing the original instantaneous temperature difference. There are 3 to 8 values. The filtering process aims to reduce noisy data, ultimately yielding a series of smooth instantaneous temperature differences. The data contains no noise and clearly shows the trend of heat load variation in the multi-wire cutting system during multi-wire cutting operations.

[0070] After performing step C, proceed to step D to analyze the smoothing of instantaneous temperature differences. The changing trend is used to calculate the average temperature difference. This serves as an indicator of the average heat load of the multi-wire cutting system. Step D essentially involves calculating and smoothing the instantaneous temperature difference. The average value over a relatively long time window, which is the mean sampling period, is significantly larger than the original instantaneous temperature difference. The sampling interval. The sampling periods for each mean can be equal or unequal. When the sampling periods for each mean are equal, step D essentially involves calculating the smoothed instantaneous temperature difference. The moving average over a relatively long time window is called the second filter window.

[0071] Before implementing the online control method for multi-wire cutting process parameters of the present invention, the instantaneous temperature difference target value of the multi-wire cutting process has been preset. Upper limit of instantaneous temperature difference The allowable temperature difference fluctuation range. Taking a multi-wire dicing process for crystal ingots aimed at obtaining wafers as an example, in some implementations, the target instantaneous temperature difference value is... 2.0℃, upper limit of instantaneous temperature difference The temperature should not be lower than 3.0℃, and the allowable temperature fluctuation range is 1.7℃~2.3℃.

[0072] Step E aims to determine whether the heat load of the multi-wire cutting system experiences a short-term abrupt change, and to take emergency adjustment measures when such a change occurs. This involves smoothing the instantaneous temperature difference. A sharp increase occurs within a short-term fluctuation range, and the temperature remains above the instantaneous temperature difference threshold for at least 7 seconds. If this occurs, the heat load of the multi-wire cutting system will experience a short-term abrupt change.

[0073] Taking the multi-wire dicing process for crystal rods as an example, in some implementations, the short-term fluctuation duration is 2-3 minutes, when smoothing the instantaneous temperature difference. If the temperature rises to above 3.0°C within 2-3 minutes and remains above 3.0°C for at least 10 seconds, the multi-wire cutting system will experience a short-term abnormal change in heat load.

[0074] Step E, adjusting the cutting parameters of the wire cutter in stages, refers to adjusting the cutting parameters of the wire cutter to different degrees according to the severity of short-term sudden changes in the heat load of the multi-wire cutting system. The purpose of staged adjustment is to minimize the wear and impact on the wire cutter and wire while meeting the adjustment requirements of the wire cutter and alleviating the short-term sudden changes in the heat load of the multi-wire cutting system, so as to make the wire cutter smoothly change its own operating state and make the changes in wire load stable.

[0075] Step F aims to determine whether the heat load of the multi-wire cutting system exhibits a long-term, slow, and imperceptible drift anomaly, and to implement long-term gradual adjustment measures when such anomalies occur. When the average temperature difference... If the temperature changes slowly within a long-term drift range and remains below the lower limit of the allowable temperature difference fluctuation range or above the upper limit of the allowable temperature difference fluctuation range for at least 5 minutes, then the heat load of the multi-wire cutting system exhibits a long-term gradual change anomaly.

[0076] Taking the multi-wire dicing process for crystal rods as an example, in some implementations, the long-term drift time ranges from 10 to 30 minutes, when the average temperature difference... If the temperature is slowly raised to above 2.3°C or dropped to below 1.7°C and maintained for at least 15 minutes, a long-term gradual change anomaly will occur in the multi-wire cutting system.

[0077] Step F involves comprehensive correction adjustment, which includes multiple levels of adjustment based on the severity of long-term gradual changes in the heat load of the multi-wire cutting system. The purpose of setting multiple levels of correction adjustment is to: meet the parameter adjustment requirements of the multi-wire cutting process, alleviate the long-term gradual changes in the heat load of the multi-wire cutting system, prevent significant changes in the operating parameters of the multi-wire cutting system, and delay wear and tear on the wire cutter and wire, as well as load variations.

[0078] By implementing graded adjustment of the cutting parameters of the wire cutting machine to alleviate short-term abrupt changes in heat load, and by implementing comprehensive correction process parameters to alleviate long-term drift anomalies in heat load, the online control method of multi-wire cutting process parameters of this invention, compared with the prior art, can automatically identify short-term abrupt changes and long-term gradual changes in heat load, and can take adaptive parameter control strategies for short-term abrupt changes and long-term gradual changes in heat load respectively. It also fundamentally eliminates the causes of abnormal heat load fluctuations to alleviate abnormal heat load fluctuations and ensure cutting efficiency and product quality. Therefore, this invention provides a solution for multi-dimensional and hierarchical adjustment of multiple process parameters to deal with abnormal heat load, rather than simply adjusting the working fluid flow rate and working fluid inlet temperature as in the prior art to deal with various possible abnormal heat loads. The adjustment method of only adjusting the working fluid flow rate and inlet temperature is passive and requires repeated execution, the adjustment effect is lagging, the working fluid flow is abnormal, and it will also cause oscillations in various operating parameters of the multi-wire cutting system. In some cases, even after the inlet temperature is adjusted to the critical value, the abnormal heat load still does not improve.

[0079] To address the issue of long-term gradual changes in thermal load, this invention, through comprehensive correction process parameters, can resolve the mismatch between the operating parameters of the multi-wire dicing system and process requirements earlier in the formal production stage. This eliminates surface defects in wafers or other types of products as early as possible, avoiding the low product yield caused by taking countermeasures only after a large number of surface defects have accumulated. In contrast, existing multi-wire dicing processes focus only on short-term abrupt changes in thermal load while ignoring long-term gradual changes, which can easily lead to a large accumulation of surface defects over a long period, resulting in significant production losses.

[0080] In some implementations, the online control method for multi-wire EDM process parameters further includes:

[0081] Step G: If the instantaneous temperature difference is smoothed within a short-term fluctuation range... Within the preset allowable temperature difference fluctuation range, and the average temperature difference over the long-term drift period. If the temperature difference is within the allowable fluctuation range, the current multi-wire cutting process parameters will be maintained.

[0082] Step G provides the criteria and countermeasures for determining normal fluctuations in the heat load of a multi-wire cutting system, including smoothing out instantaneous temperature differences. Within at least one short-term fluctuation range, the temperature difference falls within the permissible fluctuation range, and the average temperature difference... If the temperature difference fluctuation range is within at least one long-term drift time interval, the heat load change of the multi-wire cutting system is considered normal and therefore acceptable.

[0083] In some implementations, the cutting parameters of the wire cutter adjusted in step E include:

[0084] Step E1, if 0℃ < ( - If the temperature is ≤0.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate, but the reduction should not exceed 5%.

[0085] If 0.5℃ < ( - If the temperature is ≤1.0℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 5%~10%.

[0086] If 1.0℃ < ( - If the temperature is ≤1.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 10%~20%.

[0087] If ( - If the temperature exceeds 1.5°C and remains above 7 seconds, reduce the wire speed and / or the material feed rate by more than 20%.

[0088] The wire is conveyed by the wire rollers of the wire cutter. The linear velocity of the wire is equal to the linear velocity of the outer circumference of the wire roller, and also equal to the frictional velocity of the wire relative to the surface of the material being cut. The feed rate of the material, also known as the table speed, refers to the speed at which the material moves relative to the cutting wire mesh formed by the wire. Taking multi-wire cutting of crystalline materials as an example, in some embodiments, the wire rollers used to drive the wire are arranged in a horizontally extending posture along the roller axis, the material feed rate is in the vertical direction, and the wire bowing factor is not considered. The wire forms a horizontal cutting wire mesh between two of the wire rollers.

[0089] Step E1 specifies two adjustable parameter types for the wire cutting machine's cutting parameters: adjusting the wire speed and the material feed rate. With this configuration, the present invention can adjust the wire cutting machine's cutting parameters appropriately based on the severity of short-term heat load fluctuations in the multi-wire cutting system. This minimizes wear and impact on the wire cutting machine and wire while meeting the wire cutting machine's parameter adjustment requirements and mitigating short-term heat load fluctuations in the multi-wire cutting system. This allows the wire cutting machine to smoothly change its operating state and ensures stable changes in wire load. The severity of short-term heat load fluctuations is defined as (…). - ) characterization, ( - The larger the number, the more serious the condition.

[0090] In some implementations, step F, which involves comprehensive corrective adjustments to the process parameters, includes:

[0091] Step F1: First, adjust the process parameters in multiple steps to achieve the desired result. It is falling back into the permissible range of temperature fluctuations;

[0092] Step F2, then If the temperature difference still exceeds the allowable fluctuation range, the cutting parameters need to be deeply intervened to make It is falling back into the permissible range of temperature fluctuations;

[0093] Step F3, then in If the temperature difference still exceeds the allowable fluctuation range, an off-site emergency alert will be triggered, and manual investigation and intervention will be carried out on the multi-line cutting system.

[0094] With this configuration, the online control method for multi-wire cutting process parameters of the present invention can cope with five levels of abnormal thermal load response. Step G provides countermeasures for Level 1 abnormal response, Step E provides countermeasures for Level 2 abnormal response, Step F1 provides countermeasures for Level 3 abnormal response, Step F2 provides countermeasures for Level 4 abnormal response, and Step F3 provides countermeasures for Level 5 abnormal response. Level 2 abnormal response is a short-term abrupt change in thermal load, while Levels 3, 4, and 5 are long-term gradual changes in thermal load. The multi-wire cutting system can autonomously handle all levels from Level 1 to Level 4 abnormal response. Level 5 abnormal response requires manual investigation and intervention. The countermeasures for Level 5 abnormal response serve as the basis for subsequent upgrades to the multi-wire cutting process.

[0095] Furthermore, the multiple step-by-step adjustments of process parameters in step F1 include:

[0096] Step F11: During the adjustment of process parameters, ensure the inlet temperature of the working fluid. The temperature remains consistently between 20.5°C and 22.5°C.

[0097] Step F12: Ensure the inlet temperature setting is met. Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. The set value of liquid inlet temperature each time The adjustment range shall not be less than 0.04℃ and not greater than 0.08℃;

[0098] exist > In this case, control the heat exchange unit to operate in heating mode and / or increase the heating power of the heat exchange unit to make near ;

[0099] exist < In this case, control the heat exchange unit to operate in cooling mode and / or increase the cooling capacity of the heat exchange unit to make near ;

[0100] In step F2, When the temperature difference still exceeds the allowable fluctuation range, the parameters for deep intervention cutting include:

[0101] During step F21, when intervening in the cutting parameters, ensure the inlet temperature is within acceptable limits. The temperature remains between 20.5°C and 22.5°C.

[0102] Specifically, the multi-wire cutting system includes an inner-loop PID control module, which comprises a heat exchange unit and an inlet fluid temperature sensor. The working fluid entering the cutting chamber first passes through the heat exchange unit, and the inlet fluid temperature sensor is located in the cutting chamber to monitor the inlet fluid temperature. Based on the monitoring results of the inlet temperature sensor and the preset liquid inlet temperature setting value The deviation between the two is addressed by the inner-loop PID control module generating temperature control commands through the inner-loop PID algorithm. The heat exchange unit responds to these commands by adjusting its cooling and heating capacities to maintain the inlet liquid temperature. Approaching the inlet temperature setpoint .

[0103] Taking multi-wire cutting of crystalline materials as an example, the inlet temperature of the working fluid... The working fluid inlet temperature has a decisive impact on the geometric accuracy, cutting efficiency, and finished product yield of wafer products. In the cutting processes of other materials, it is also crucial. This also determines the quality of the final product. Setting the inlet liquid temperature setpoint... The purpose of setting up the inner-loop PID control module is to ensure the actual inlet temperature of the working fluid. Stable at Within a minimal fluctuation range of ±0.2℃, to ensure that the surface quality of the product remains consistent regardless of the type of abnormal heat load response. And the impact.

[0104] Step F12 is designed to adjust the inlet temperature setpoint in multiple steps. Step F12 specifies the adjustment of the inlet temperature setpoint at each step. The temperature change range is limited to 0.04℃~0.08℃ to prevent issues arising from the set inlet liquid temperature. Rapid changes in working fluid inlet temperature Significant changes in a short period of time, inlet liquid temperature Significant changes in a short period of time can cause obvious geometric variations in the surface shape of chips or other products.

[0105] The inner loop PID control module controls the heat exchange unit to operate in heating mode and / or increases the heating power of the heat exchange unit by temperature control commands; the inner loop PID control module also controls the heat exchange unit to operate in cooling mode and / or increases the cooling power of the heat exchange unit by temperature control commands.

[0106] Furthermore, in step F12, ensuring the inlet liquid temperature setpoint... Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. include:

[0107] Step F121: After adjusting the initial liquid inlet temperature setting... Then, wait 4-8 minutes and observe the average temperature difference. Is it within the allowable temperature fluctuation range?

[0108] like Maintain the inlet temperature setpoint within the allowable temperature difference fluctuation range. ;

[0109] like If the temperature fluctuation is outside the allowable range, continue to adjust the inlet temperature setpoint. until Until the temperature difference falls within the permissible fluctuation range;

[0110] Among them, the inlet temperature set value was adjusted multiple times. During the process, the inlet temperature setpoint The adjustment range requirements are progressively increased. The effect of this progressively increasing adjustment range is to prevent the initial liquid inlet temperature setting from being affected. Significant changes lead to changes in inlet liquid temperature Make significant changes at the beginning to avoid inlet liquid temperature Rapid changes in the temperature of the inlet fluid impact the multi-wire cutting system. This is understandable, especially when the inlet fluid temperature... When changes are rapid, the properties and performance of the material being cut and the wire will change drastically.

[0111] In other embodiments, the multiple step-by-step adjustment of process parameters in step F1 includes:

[0112] F13, according to The material feed rate was adjusted multiple times, every 3-8 minutes, and the trend of change was examined. Does it fall within the allowable temperature fluctuation range?

[0113] like If the temperature falls within the allowable fluctuation range, the material feed rate will be maintained.

[0114] like If the temperature difference exceeds the upper limit of the allowable fluctuation range, the feed rate of the material should be reduced by 0.5% to 2%.

[0115] like If the temperature difference is below the lower limit of the allowable fluctuation range, the feed rate of the material should be increased by 0.5% to 2%.

[0116] Step F13 aims to adjust the material feed rate in multiple steps, specifying the rate variation for each adjustment. The feed rate adjustment is limited to 0.5% to 2% to prevent drastic changes in the material's relative speed to the cutting wire mesh within a short period. This avoids sudden shifts in the interaction force between the material and the wire, which could impact the multi-wire cutting system and reduce the likelihood of wire breakage or jamming within the material cut.

[0117] In some implementations, the depth intervention cutting parameters in step F2 include:

[0118] F22. Reduce the wire speed and / or material feed rate by 15% to 30%.

[0119] Step F22 specifies two specific means to achieve deep intervention in cutting parameters: intervening in wire speed and material feed rate. The reduction ratio of cutting parameters in step F22 is 15%~30%, which exceeds the maximum reduction ratio of cutting parameters in step E1 of 20%. This setting effectively overcomes the adverse sources of long-term gradual changes in heat load for the response to level 4 heat load anomalies, breaks through the current limitation of cutting parameter adjustment that focuses on short-term sudden changes in heat load, and can also upgrade the multi-wire cutting process.

[0120] In some embodiments, the multi-wire cutting system also includes an outlet temperature sensor located in the cutting chamber for monitoring the outlet temperature. In step B, the inlet temperature of the cutting chamber is monitored repeatedly. and liquid outlet temperature include:

[0121] Step B1: Repeat the monitoring of the inlet liquid temperature multiple times at the same sampling interval n. and liquid outlet temperature The sampling interval n is the original instantaneous temperature difference. The sampling interval.

[0122] With this configuration, the inlet and outlet temperature sensors can achieve inlet temperature measurement at sampling intervals n. and liquid outlet temperature Periodic sampling is used to obtain the raw instantaneous temperature difference over a period of time. In the middle, each original instantaneous temperature difference The formation time is evenly distributed within this time period, from which a smooth instantaneous temperature difference is obtained. This can more clearly demonstrate the heat load variation trend of the multi-wire cutting system during multi-wire cutting operations. Based on this, the smoothed instantaneous temperature difference obtained by performing steps C and D is then analyzed. and average temperature difference The reduced distortion helps to fully overcome the causes of short-term abrupt changes and long-term gradual changes in heat load.

[0123] Furthermore, in step C, the original instantaneous temperature difference is... Perform filtering operations to obtain a smooth instantaneous temperature difference. include:

[0124] Step C1: Using an integer multiple of the sampling interval n as the first filtering window, filter multiple raw instantaneous temperature differences. Filtering is performed to obtain multiple smooth instantaneous temperature differences. .

[0125] The sampling interval is no less than 0.2 seconds and no more than 5 seconds, the first filtering window is 5 to 20 seconds, and the mean sampling period is 10 to 15 minutes.

[0126] With this setting, the original instantaneous temperature difference Data noise filtering and smoothing of instantaneous temperature differences The data is filtered for noise more effectively.

[0127] Further, in step B, the initial instantaneous temperature difference of the working fluid is obtained. , include:

[0128] Step B2, Substitute into the calculation formula In and There is a preset dwell time interval. , The measured time is compared to The measured time was late .

[0129] With this setup, the original instantaneous temperature difference over a period of time is obtained in this way. The values ​​are more accurate and better reflect the true heat load of the multi-wire cutting system.

[0130] In other embodiments, where the working fluid has a short dwell time in the cutting chamber and the geometric accuracy requirements for the sliced ​​products are low, the inlet temperature can be ignored. and outlet temperature The time interval between stays and at the same inlet temperature and outlet temperature The difference is taken as the original instantaneous temperature difference at that moment. value.

[0131] It is worth noting that in step E, the instantaneous temperature difference is smoothed. Exceeding the preset upper limit threshold for instantaneous temperature difference The duration should not be less than the first filtering window; in step F, the average temperature difference The duration exceeding the preset allowable temperature difference fluctuation range should be less than or equal to the average sampling period, and should be significantly greater than the short-term fluctuation duration range. The reason for being greater than the short-term fluctuation duration range is to confirm whether a long-term gradual change in heat load has truly occurred, thereby improving the reliability of the judgment.

[0132] The technical features of the above-described embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any appropriate changes and variations made to the above embodiments within the essential spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for online control of multi-wire EDM process parameters, wherein the process parameters include the cutting parameters of the wire EDM machine and the inlet temperature of the working fluid. The cutting parameters include the linear velocity of the wire and the feed rate of the material, characterized in that... The method includes: Add working fluid to the cutting chamber and start the wire cutter to drive the wire to cut the material; Repeatedly monitor the inlet temperature of the cutting chamber. and outlet temperature And obtain the original instantaneous temperature difference of the working fluid. , ; For the original instantaneous temperature difference Perform filtering operations to obtain a smooth instantaneous temperature difference. ; Smoothed instantaneous temperature difference within each mean sampling period Calculate the mean to obtain multiple average temperature differences corresponding to multiple mean sampling periods. ; If a smooth, instantaneous temperature difference occurs within a short-term fluctuation range... Exceeding the preset upper limit threshold for instantaneous temperature difference And continue for at least 7 seconds, then based on the smooth instantaneous temperature difference Adjust the cutting parameters of the wire cutter according to the degree of over-limit to reduce ; If an average temperature difference occurs within a long drift period... If the temperature difference exceeds the preset allowable fluctuation range and persists for at least 5 minutes, then comprehensive corrective adjustments will be made to the process parameters to ensure that... The temperature difference will fall back to the allowable fluctuation range. Among them, the upper limit of the short-term fluctuation duration range is no greater than the lower limit of the long-term drift duration range; The comprehensive correction adjustment of the process parameters includes: First, adjust the process parameters in multiple steps to achieve... It is falling back into the permissible range of temperature fluctuations; Then If the temperature difference still exceeds the allowable fluctuation range, the cutting parameters need to be deeply intervened to make It is falling back into the permissible range of temperature fluctuations; Then in If the temperature difference still exceeds the permissible fluctuation range, an off-site emergency alert will be triggered. The cutting parameters of the graded adjustable wire cutter include: If 0℃ < ( - If the temperature is ≤0.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate, but the reduction should not exceed 5%. If 0.5℃ < ( - If the temperature is ≤1.0℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 5%~10%. If 1.0℃ < ( - If the temperature is ≤1.5℃ and lasts for at least 7 seconds, then reduce the wire speed and / or the material feed rate by 10%~20%. If ( - If the temperature exceeds 1.5°C and remains above 7 seconds, reduce the wire speed and / or the material feed rate by more than 20%.

2. The online control method for multi-wire EDM process parameters as described in claim 1, characterized in that, The process parameters are adjusted in multiple steps, including: Ensure the inlet temperature of the working fluid during process parameter adjustment. Between 20.5°C and 22.5°C; The above When the temperature difference still exceeds the allowable fluctuation range, the deep intervention cutting parameters include: ensuring the inlet temperature during the deep intervention cutting process. Between 20.5°C and 22.5°C.

3. The online control method for multi-wire cutting process parameters as described in claim 2, characterized in that, The process parameters are adjusted in multiple steps, including: Ensure the inlet temperature set value is met. Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. The set value of liquid inlet temperature each time The adjustment range shall not be less than 0.04℃ and not greater than 0.08℃; exist > In this case, control the heat exchange unit to operate in heating mode and / or increase the heating power of the heat exchange unit to make near ; exist < In this case, control the heat exchange unit to operate in cooling mode and / or increase the cooling capacity of the heat exchange unit to make near ; and / or, according to The material feed rate was adjusted multiple times, every 3-8 minutes, and the trend of change was examined. Whether it falls within the allowable temperature fluctuation range; like If the temperature falls within the allowable fluctuation range, maintain the material feed rate; like If the temperature difference exceeds the upper limit of the allowable fluctuation range, the material feed rate should be reduced by 0.5% to 2%. like If the temperature difference is below the lower limit of the allowable fluctuation range, the feed rate of the material should be increased by 0.5% to 2%.

4. The online control method for multi-wire cutting process parameters as described in claim 3, characterized in that, The above ensures the set value of the inlet temperature. Under the premise of a temperature range of 20.5°C to 22.5°C, the inlet temperature setpoint should be adjusted at least once. include: After adjusting the inlet temperature setting value Afterwards, wait 4-8 minutes and observe. Is it within the allowable temperature fluctuation range? like Maintain the inlet temperature setpoint within the allowable temperature difference fluctuation range. ; like If the temperature fluctuation is outside the allowable range, continue to adjust the inlet temperature setpoint. until Until the temperature difference falls within the permissible fluctuation range; After repeatedly adjusting the inlet temperature setting value During the process, the inlet temperature setpoint The required adjustment range increases sequentially.

5. The online control method for multi-wire EDM process parameters as described in claim 2, characterized in that, The depth intervention cutting parameters include: Reduce the wire speed and / or the material feed rate by 15% to 30%.

6. The online control method for multi-wire EDM process parameters as described in claim 1, characterized in that, The inlet temperature of the cutting chamber was repeatedly monitored. and outlet temperature And obtain the original instantaneous temperature difference of the working fluid. , include: The inlet temperature was monitored repeatedly at the same sampling interval. and outlet temperature The sampling interval is the original instantaneous temperature difference. The sampling interval; The original instantaneous temperature difference Perform filtering operations to obtain a smooth instantaneous temperature difference. include: Multiple raw instantaneous temperature differences are filtered using an integer multiple of the sampling interval as the first filtering window. Filtering is performed to obtain multiple smooth instantaneous temperature differences. ; The sampling interval is not less than 0.2 seconds and not more than 5 seconds, the first filtering window is 5 to 20 seconds, and the mean sampling period is 10 to 15 minutes.

7. The online control method for multi-wire cutting process parameters as described in claim 6, characterized in that, Obtain the original instantaneous temperature difference of the working fluid , include: Substitute into the calculation formula In and There is a preset dwell time interval. , The measured time is compared to The measured time was late .

8. The online control method for multi-wire EDM process parameters as described in any one of claims 1 to 7, characterized in that, The method further includes: If the instantaneous temperature difference is smoothed Within the preset allowable temperature difference fluctuation range, and the average temperature difference If the temperature difference is within the allowable fluctuation range, the current multi-wire cutting process parameters will be maintained. and / or, The duration of the short-term fluctuation is 2 to 3 minutes, and the duration of the long-term drift is 10 to 30 minutes. and / or, The upper limit threshold of instantaneous temperature difference The temperature shall not be lower than 3°C, and the allowable temperature difference fluctuation range is 1.7°C to 2.3°C.

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