A method of controlling a semiconductor vacuum chamber step pressure transition valve

Abstract

The application relates to the technical field of semiconductor manufacturing equipment control, and provides a semiconductor vacuum chamber step pressure transition valve control method. The wafer position, the current pressure and the target pressure are acquired; the pressure difference is divided into a first stage and a second stage; the opening degree control parameter is determined according to the pressure difference, the pressure difference is negatively correlated with the opening degree control parameter; the opening degree control parameter is corrected according to the wafer spacing; the exhaust valve is opened according to the corrected parameter in the first stage, so that the pressure enters the second stage; the exhaust valve is closed and then reopened when the stages are connected; when the pressure matches the target pressure, the exhaust valve is closed and the isolation valve is opened. The wafer cleanliness is protected, and the transition efficiency is maintained.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing equipment control technology, and more specifically, to a method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber. Background Technology

[0002] In semiconductor manufacturing, the loading lock chamber serves as a transition channel connecting the atmospheric environment and the vacuum process chamber, handling the pressure transition during wafer loading and unloading. Existing technologies typically employ a single, fixed valve control strategy, using a constant opening or simple linear adjustment for evacuation across the entire pressure range. This strategy is prone to excessive gas velocity during high pressure differential stages, increasing shear force on the wafer surface and causing particle agitation. Furthermore, as the gas flow transitions from viscous to molecular flow, the valve opening and conductance exhibit a non-linear relationship, making it difficult for the fixed control strategy to maintain a stable pressure change rate. In addition, existing strategies do not consider the impact of wafer position and size on local airflow distribution, resulting in insufficient protection when the wafer is close to the valve or when dealing with large wafers. Simultaneously, temperature changes in the chamber and valves affect the gas viscosity coefficient and valve conduction capacity; existing technologies lack temperature compensation mechanisms, leading to control inaccuracies under different thermal conditions.

[0003] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0004] The purpose of this application is to provide a step-by-step pressure transition valve control method for semiconductor vacuum chambers, which has the advantages of being able to dynamically control the valve according to the gas flow characteristics corresponding to the pressure range, the wafer spatial position and size information, and the real-time temperature status of the chamber, maintaining pressure transition efficiency while protecting the cleanliness of the wafer surface, and adapting to different wafer specifications and different thermal conditions.

[0005] This application provides a method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber, the technical solution of which is as follows: Obtain wafer position information, current pressure value, and target pressure value of adjacent process chambers within the loading lock chamber; Based on the pressure difference between the current pressure value and the target pressure value, the pressure transition process is divided into at least a first stage and a second stage; For each stage, the opening control parameter is determined based on the pressure difference between its starting and ending pressures. The pressure difference is negatively correlated with the opening control parameter to limit the gas flow rate and prevent particles from being lifted off the wafer surface. The opening control parameter is then compensated and corrected based on the nonlinear relationship between the opening and the gas conductivity under the corresponding gas flow state in the current pressure range. The opening control parameters are adjusted based on the distance between the wafer and the suction valve and isolation valve, wherein the distance is positively correlated with the opening control parameters; The air extraction valve is opened according to the opening control parameters after the first stage correction, so that the pressure enters the second stage; when the first stage and the second stage are connected, the air extraction valve is closed; when the pressure change rate is less than the stability determination threshold, the pressure is determined to be stable, and then the air extraction valve is reopened according to the opening control parameters after the second stage correction. When the pressure in the loading lock chamber matches the target pressure value, the evacuation valve is closed and the isolation valve is opened to establish communication between the loading lock chamber and the adjacent process chamber.

[0006] Furthermore, before closing the air extraction valve and opening the isolation valve, the method further includes: introducing clean gas into the loading lock chamber, wherein the flow rate of the clean gas is positively correlated with the pressure value of the loading lock chamber at the current stage; and simultaneously opening the air extraction valve so that the clean gas flows through the loading lock chamber and is discharged through the air extraction valve.

[0007] Furthermore, the method also includes: obtaining the temperature value of the loading lock chamber; and correcting the opening control parameter based on the temperature value, wherein the temperature value is negatively correlated with the opening control parameter.

[0008] Furthermore, after opening the extraction valve according to the opening control parameters corrected in the first stage, the method further includes: Monitor the pressure change rate of the loading lock chamber; when the deviation between the pressure change rate and the expected pressure change rate corresponding to the current stage exceeds the deviation threshold, close the vent valve, record the current pressure change rate, the actual valve opening, the wafer position and temperature value, and generate an abnormality prompt message; when the same abnormality occurs consecutively a set number of times, subsequent pressure transition operations are prohibited.

[0009] Furthermore, the division of the pressure transition process into at least a first stage and a second stage includes: Based on historical pressure transition data under the same wafer size and target pressure, the number of stages and the corresponding pressure range for each stage are determined; wherein, the historical pressure transition data includes historical pressure change rate and historical stabilization time.

[0010] Furthermore, after opening the extraction valve according to the opening control parameters revised in the first stage, the method further includes: Monitor the rate of pressure change in the loading lock chamber; The opening of the suction valve is adjusted based on the deviation between the pressure change rate and the expected pressure change rate corresponding to the first stage; wherein, when the pressure change rate is greater than the expected pressure change rate, the opening of the suction valve is decreased; and when the pressure change rate is less than the expected pressure change rate, the opening of the suction valve is increased.

[0011] Furthermore, adjusting the opening degree of the suction valve includes: The adjustment amount of the air extraction valve opening is determined based on the proportion of the execution time in the first stage to the total expected time of the stage: when the execution time in the first stage does not exceed half of the total expected time, the opening adjustment amount is the first adjustment amount; when the execution time in the first stage exceeds half of the total expected time, the opening adjustment amount is the second adjustment amount; the first adjustment amount is greater than the second adjustment amount.

[0012] Furthermore, when the air extraction valve is reopened according to the opening control parameters corrected in the second stage, the method further includes: obtaining the mechanical response delay time of the air extraction valve; correcting the mechanical response delay time according to the temperature deviation of the air extraction valve at the current temperature relative to the standard temperature and the opening deviation of the current opening relative to the reference opening; and sending an opening control signal in advance before the pressure in the loading lock chamber reaches the pressure range corresponding to the second stage, based on the corrected delay time.

[0013] Furthermore, dividing the pressure transition process into at least a first stage and a second stage further includes: adjusting the number of stages and the pressure range width corresponding to each stage according to the wafer position information; wherein, when the distance between the wafer and the suction valve or the isolation valve is less than a first distance threshold, the number of stages is increased and the pressure range width of each stage is narrowed; when the distance between the wafer and the suction valve or the isolation valve is greater than a second distance threshold, the number of stages is reduced and the pressure range width of each stage is widened.

[0014] Furthermore, the step of correcting the opening control parameters based on the distance between the wafer and the suction valve and isolation valve further includes: Obtain the size information of the wafer; The opening control parameters are jointly corrected based on the wafer's size and position information; wherein, for wafers at the same position, the wafer size is negatively correlated with the corresponding opening correction coefficient; and for wafers of the same size, the distance between the wafer edge and the valve is positively correlated with the opening correction coefficient. As can be seen from the above, the step-type pressure transition valve control method for semiconductor vacuum chambers provided in this application divides the pressure transition process into at least a first stage and a second stage, establishes a negative correlation between the stage pressure difference and the opening control parameter to limit the gas flow rate, and performs compensation and correction based on the nonlinear relationship between the opening and the gas conductivity under the corresponding gas flow state in the current pressure range. It also dynamically corrects the opening control parameter by combining wafer position and size information and chamber temperature state, and performs valve closure stability judgment and mechanical response delay compensation at the stage transition. This solves the problems of insufficient particle protection, control inaccuracy during flow state transition, and failure to consider wafer position and thermal condition differences in a single valve control strategy. It has the advantages of maintaining pressure transition efficiency while protecting wafer surface cleanliness and adapting to different wafer specifications and different thermal conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating the steps of the semiconductor vacuum chamber stepped pressure transition valve control method disclosed in the embodiments of the present invention. Figure 2 This is a schematic diagram of the loading lock chamber disclosed in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the delay correction steps disclosed in an embodiment of the present invention. Detailed Implementation

[0017] 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 these embodiments belong; the terminology used herein and in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit these embodiments; the terms "comprising" and "having," and any variations thereof, in the specification of these embodiments and the foregoing drawings, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification of these embodiments and the foregoing drawings are used to distinguish different objects, not to describe a particular order.

[0018] The implementation details of the technical solution in this embodiment are described in detail below: In semiconductor manufacturing, the loading lock chamber serves as a transition channel between the atmospheric environment and the vacuum process chamber. When wafers enter or exit the process chamber, the loading lock chamber must complete a pressure transition from atmospheric pressure to process vacuum. If a single valve control strategy is used, excessively high gas velocity during the high pressure differential stage increases shear force on the wafer surface, causing particles to be lifted. Simultaneously, when the gas flow transitions from viscous to molecular flow, the valve opening and gas conductivity exhibit a non-linear relationship, making it difficult for a fixed control strategy to maintain a stable pressure change rate. Furthermore, when the wafer is near the extraction or isolation valve, localized airflow becomes concentrated, and the distance between the edge of the wafer and the valve varies depending on the wafer size; a single strategy cannot simultaneously achieve both cleanliness and efficiency.

[0019] This application proposes a method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber, such as... Figure 1 As shown, the method includes: S101, obtain the wafer position information, current pressure value and target pressure value of adjacent process chambers in the loading lock chamber.

[0020] In this embodiment, as Figure 2 The diagram shows the structure of the loading lock chamber. In semiconductor vacuum processing equipment, the loading lock chamber serves as a transition chamber connecting the atmospheric environment and the vacuum process chamber. Its internal pressure state and the wafer's spatial position together determine the baseline parameters for subsequent valve control strategies. This step aims to establish an initial dataset for pressure transition control, including the wafer's spatial position within the chamber, the current actual pressure value of the loading lock chamber, and the target pressure values ​​required by adjacent process chambers.

[0021] Specifically, the wafer position information is determined jointly by the encoder feedback coordinates of the vacuum manipulator and the through-beam photoelectric sensor array on the sidewall of the chamber. After the vacuum manipulator places the wafer in the wafer holder within the loading lock chamber, the manipulator control system outputs the three-dimensional coordinates of the wafer center in the manipulator coordinate system. Multiple sets of through-beam sensors arranged axially along the sidewall of the chamber verify whether the wafer is centered on the holder. The data from both are fused to obtain the axial distance between the wafer center and the flange face of the extraction valve, as well as the axial distance between the wafer center and the flange face of the isolation valve. This distance data is used to subsequently adjust the valve opening control parameters based on the spatial relationship between the wafer and the valve, to prevent particles from being lifted off the wafer surface due to excessively high local airflow velocity.

[0022] The current pressure value is acquired using a composite vacuum measuring device mounted on the side wall of the loading lock chamber. In the rough vacuum range, a Pirani vacuum gauge outputs the chamber pressure signal in real time; once the high vacuum range is reached, the measurement is switched to an ionization vacuum gauge. The current pressure value reflects the initial vacuum state of the loading lock chamber after wafer loading, serving as the starting point for subsequently dividing the pressure transition process into the first and second stages.

[0023] The target pressure value is obtained by reading pressure sensor data from adjacent process chambers via the device control bus, or by directly retrieving it from the currently executed process recipe file. Adjacent process chambers are maintained at their required vacuum levels by independent vacuum pump units. This pressure value represents the endpoint pressure state that the loading lock chamber needs to reach, and together with the current pressure value, forms the basis for differential pressure calculation.

[0024] Because the specific position of the wafer within the loading chamber alters the gas flow path and the shear force distribution of the gas flow on the wafer surface, and because the pressure difference between the current and target pressure values ​​directly determines the number of pressure transition stages and the width of each stage's pressure range, it is necessary to acquire all three types of parameters simultaneously at the start of pressure transition control. This multi-parameter synchronous acquisition mechanism ensures that subsequent stage division and valve opening control can simultaneously consider pressure transition efficiency and wafer surface cleanliness protection, thus providing precise input conditions for stepped pressure transition.

[0025] In one implementation, the control system triggers a parameter acquisition command after detecting that the wafer has fully entered the loading lock chamber and the chamber door is closed. The robotic arm encoder outputs the axial distance L1 of the wafer center relative to the evacuation valve and the axial distance L2 relative to the isolation valve, the composite vacuum gauge outputs the current pressure value P0, and the process chamber controller outputs the target pressure value Pt via the bus. These parameters are then converted from analog to digital and written to the control register for use by the subsequent stage partitioning module and opening calculation module.

[0026] S102, based on the pressure difference between the current pressure value and the target pressure value, divide the pressure transition process into at least a first stage and a second stage.

[0027] In this embodiment, after the wafer loading is completed and the chamber door is closed in the loading lock chamber, the control system reads the current pressure value P0 and the target pressure value Pt collected in step S101, and calculates the pressure difference ΔP between them. This pressure difference represents the pressure span required for the loading lock chamber to reach the target vacuum state of the adjacent process chamber from the current vacuum state. Based on the magnitude of the absolute value of this pressure difference, the control system divides the complete pressure transition process into at least two stages, namely, the first stage and the second stage. The first stage corresponds to the interval from the current pressure value P0 to the intermediate pressure value Pm, and the second stage corresponds to the interval from the intermediate pressure value Pm to the target pressure value Pt. The essence of stage division is to decompose a single continuous pressure change process into multiple discrete intervals with different control strategies, so that the pressure change rate and valve opening control parameters in each stage can be matched with the gas flow characteristics of that stage.

[0028] Specifically, the pressure difference ΔP is the absolute value of the difference between the current pressure value P0 and the target pressure value Pt, i.e., ΔP = |P0 - Pt|. When ΔP is greater than the reference pressure difference threshold, the control system divides the pressure transition process into a first stage and a second stage; as ΔP further increases, the number of stages can be increased accordingly. The intermediate pressure value Pm is determined based on the pressure difference ΔP and the number of stages N. For the case of dividing into two stages, Pm = P0 - ΔP / 2. The pressure range of the first stage is from P0 to Pm, and the pressure range of the second stage is from Pm to Pt. The width of the pressure range for each stage is the absolute value of the difference between the starting pressure and the ending pressure of that stage. The width of the first stage is ΔP / 2, and the width of the second stage is also ΔP / 2. Since the initial pressure difference of the first stage is relatively large, the corresponding gas flow state may be in the viscous flow range, while the second stage is close to the target pressure, and the corresponding gas flow state may be in the transition flow or molecular flow range. Therefore, different valve opening control strategies are required for the two stages.

[0029] The proposed solution divides the pressure transition process into multiple stages based on the pressure difference, enabling the pressure change within each stage to be completed under control parameters that match the flow characteristics of that stage. This avoids the decrease in control accuracy caused by flow changes across the entire pressure difference range by a single continuous control strategy, thus providing a structural basis for subsequently determining the opening control parameters based on the pressure difference of each stage.

[0030] In one implementation, the current pressure value P0 is atmospheric pressure (1.01 × 10⁵ Pa), the target pressure value Pt is the process vacuum of the adjacent process chamber (1.33 × 10⁻¹ Pa), and the pressure difference ΔP between the two is approximately 1.01 × 10⁵ Pa. The control system divides this pressure difference into a first stage and a second stage, with an intermediate pressure value Pm set at 5.05 × 10⁴ Pa. The pressure range of the first stage is from 1.01 × 10⁵ Pa to 5.05 × 10⁴ Pa, and the pressure range of the second stage is from 5.05 × 10⁴ Pa to 1.33 × 10⁻¹ Pa. The first stage corresponds to the viscous flow-dominated region, and the second stage corresponds to the region where the flow transitions from transitional flow to molecular flow.

[0031] Furthermore, in S102, dividing the pressure transition process into at least a first stage and a second stage includes: determining the number of stages and the pressure range corresponding to each stage based on historical pressure transition data under the same wafer size and the same target pressure; wherein, the historical pressure transition data includes historical pressure change rate and historical stabilization time.

[0032] In this embodiment, during mass production, combinations of the same wafer size and the same target pressure will occur repeatedly. The control system records the historical pressure change rate at each stage of each pressure transition and the historical stabilization time required from closing the extraction valve to determining pressure stability. When a new pressure transition task is initiated, the control system retrieves a set of historical data with the same wafer size and the same target pressure as that task, and statistically analyzes the distribution of historical pressure change rates and historical stabilization times at each stage in this set.

[0033] Specifically, the historical pressure change rate, or the average pressure drop per unit time within a certain stage, characterizes the pumping efficiency of that stage under specific opening control parameters. The historical stabilization time, or the time required for the pressure change rate to drop below the stabilization threshold after the pumping valve is closed when two adjacent stages are connected, characterizes the speed at which the internal pressure equalizes. The control system statistically processes the above parameters in the historical data set. If the historical pressure change rate fluctuates significantly in a certain stage, it indicates that the pressure range width of that stage is too large and the flow regime changes drastically. In this case, the control system will increase the number of stages and narrow the pressure range width of that stage. If the historical stabilization time is generally long, it indicates that the pressure equalization at the stage transition is insufficient. In this case, the control system will adjust the stage boundary points to optimize the pressure range distribution.

[0034] This application's solution introduces historical pressure transition data, so that the stage division no longer relies on fixed empirical formulas, but is based on statistical feedback during actual equipment operation. Historical pressure change rate and historical stabilization time, as directly measurable physical quantities, can objectively reflect the pumping characteristics of the loading lock chamber under specific wafer sizes and target pressures, thus ensuring that the determination of the number of stages and pressure ranges matches the actual operating conditions of the equipment.

[0035] In one implementation, for a process formulation with a target pressure of 1.33 × 10⁻¹ Pa on a 12-inch wafer, the control system retrieves the most recent 100 historical pressure transition data. Statistical analysis shows that the standard deviation of the historical pressure change rate in the first stage exceeds 30% of the mean. Based on this, the control system increases the number of stages from 2 to 3, correspondingly narrowing the pressure range width of each stage.

[0036] Furthermore, in S102, dividing the pressure transition process into at least a first stage and a second stage further includes: adjusting the number of stages and the pressure range width corresponding to each stage according to the wafer position information; wherein, when the distance between the wafer and the suction valve or the isolation valve is less than a first distance threshold, the number of stages is increased and the pressure range width of each stage is narrowed; when the distance between the wafer and the suction valve or the isolation valve is greater than a second distance threshold, the number of stages is decreased and the pressure range width of each stage is widened.

[0037] In this embodiment, the position of the wafer within the loading lock chamber directly affects the gas flow path inside the chamber and the distribution of airflow shear force on the wafer surface. When the wafer approaches the extraction valve or isolation valve, the space between the wafer and the valve decreases, the gas flow channel narrows, the local airflow velocity increases, and the shear force on the wafer surface correspondingly intensifies. At this point, if a smaller number of stages and a wider pressure range are used, the pressure difference within each stage is large. Even with modified extraction valve opening control parameters, airflow velocities sufficient to lift particles may still be generated in localized areas. Therefore, the stage division strategy needs to be dynamically adjusted based on the actual distance between the wafer and the valve.

[0038] Specifically, the distances L1 between the wafer and the extraction valve and L2 between the wafer and the isolation valve are obtained in step S101. The first and second distance thresholds are preset based on the geometry of the loading lock chamber and the standard wafer dimensions. When either L1 or L2 is less than the first distance threshold, it indicates that the wafer is close to at least one valve. The control system will increase the number of stages and narrow the pressure range of each stage, reducing the pressure difference within each stage and thus limiting the maximum airflow velocity of each stage. When both L1 and L2 are greater than the second distance threshold, it indicates that the wafer is away from both valves and located in the central region of the chamber. In this case, the control system reduces the number of stages and widens the pressure range of each stage, improving pressure transition efficiency while ensuring that the wafer surface shear force remains below the safety limit.

[0039] The solution proposed in this application incorporates wafer location information into the stage division strategy, enabling proactive protection of wafer surface cleanliness in the spatial dimension through pressure transition control. This adaptive stage division based on wafer location avoids the potential for insufficient protection or transition efficiency loss that may occur with fixed stage division strategies when facing different wafer locations, allowing the number of stages and the width of the pressure range to match the actual spatial distribution of the wafer within the chamber.

[0040] In one embodiment, the axial length of the loading lock chamber is 400 mm, the first distance threshold is set to 100 mm, and the second distance threshold is set to 300 mm. When the axial distance between the center of the 12-inch wafer and the suction valve is 80 mm, which is less than the first distance threshold, the control system increases the number of stages from 2 to 4, and the width of the pressure range in each stage is correspondingly narrowed to half of its original width. When the axial distance between the center of the wafer and the suction valve is 350 mm and the axial distance between the center of the wafer and the isolation valve is 320 mm, both of which are greater than the second distance threshold, the control system maintains the number of stages at 2, and the width of the pressure range in each stage remains at the baseline value.

[0041] S103, for each stage, determine the opening control parameter based on the pressure difference between its starting and ending pressures. The pressure difference is negatively correlated with the opening control parameter to limit the gas flow rate and prevent particles from being lifted off the wafer surface. The opening control parameter is then compensated and corrected based on the nonlinear relationship between the opening and the gas conductivity under the corresponding gas flow state in the current pressure range.

[0042] In this embodiment, after the stage division is completed, the control system assigns valve control parameters to each stage. The opening control parameter determines the degree of opening of the evacuation valve, which in turn determines the rate at which gas flows from the loading lock chamber to the vacuum pump unit. If the stage pressure difference is large and the opening control parameter remains at a large value, the gas velocity will be too high in the early stage of the stage, forming a strong shear gas flow near the wafer surface, causing particles on the wafer surface or the carrier to detach and contaminate the wafer. Therefore, the opening control parameter is determined with the stage pressure difference as input, establishing a negative correlation constraint between the two.

[0043] Specifically, the stage pressure difference is the absolute value of the difference between the starting and ending pressures of that stage, denoted as ΔPi, where i is the stage number. The opening control parameter is denoted as Ki. The negative correlation is reflected in the fact that Ki decreases as ΔPi increases, and the basic relationship is expressed as Ki = Kbase / (1 + c·ΔPi). Where, Kbase is the baseline opening parameter, determined by the valve's rated gas delivery capacity and chamber volume; c is the pressure difference sensitivity coefficient, calibrated by the wafer surface particle lifting test; and ΔPi is the stage pressure difference of the i-th stage. The denominator increases with ΔPi, causing Ki to decrease monotonically with increasing ΔPi. In stages with larger pressure differences, the exhaust valve opens less, and the gas flow rate is actively limited.

[0044] Specifically, the valve opening control parameters are compensated and corrected based on the nonlinear relationship between the valve opening and the gas conductivity under the current pressure range. Specifically, the gas flow state within the vacuum chamber undergoes three flow states as the pressure decreases: viscous flow, transitional flow, and molecular flow. In the viscous flow range, intermolecular collisions dominate, and the valve opening and gas conductivity are approximately linearly related. In the transitional flow range, intermolecular collisions and collisions between molecules and the wall coexist, and the relationship between the valve opening and gas conductivity is nonlinear. In the molecular flow range, collisions between molecules and the wall dominate, and the gas conductivity tends to saturate; further increasing the valve opening has limited effect on improving the gas conductivity. If these nonlinear characteristics are not compensated for, the actual gas conductivity will deviate from the expected value, leading to uncontrolled pressure change rates.

[0045] In practical applications, the compensated and corrected opening control parameter is denoted as Ki', and the calculation relationship is Ki' = Ki·λ. Here, Ki is the basic opening control parameter determined by the negative correlation of the pressure difference; λ is the nonlinear compensation coefficient under the current flow state, determined by looking up the intermediate pressure value of the stage from a table. When the intermediate pressure value of the stage is in the viscous flow range, λ approaches 1, indicating that no significant compensation is needed; when it is in the transition flow range, λ is greater than 1, indicating that the opening control parameter needs to be appropriately increased to compensate for the decrease in gas conductance; when it is in the molecular flow range, λ is less than 1, indicating that the opening control parameter needs to be reduced to avoid overshoot caused by gas conductance saturation. The nonlinear compensation coefficient is determined by looking up a table, which is pre-established by gas dynamics simulation or chamber flow calibration experiment: in the viscous flow range, λ≈1.0; in the transition flow range, λ∈(1.0,1.3] is determined by interpolation based on the measured gas conductance deviation; and in the molecular flow range, λ∈[0.7,1.0] is determined based on the gas conductance saturation characteristics. The control system compares the intermediate pressure value of the stage with the above flow state boundary pressure and directly reads the corresponding λ value. S104, the opening control parameter is corrected according to the distance between the wafer and the suction valve and the isolation valve, wherein the distance is positively correlated with the opening control parameter.

[0046] In this embodiment, after determining the opening control parameter Ki' after nonlinear flow compensation in step S103, the control system further incorporates the spatial position information of the wafer within the loading lock chamber to correct the position of Ki'. The distance between the wafer and the suction valve and isolation valve reflects the spatial distribution of the wafer within the chamber, and this distance directly affects the magnitude of the airflow shear force on the wafer surface. When the wafer is close to the valve, the shear force generated by the high-speed airflow formed after the valve opens significantly increases near the wafer surface, and the risk of particle scattering increases accordingly; when the wafer is far from the valve, the airflow has diffused within the chamber space before reaching the wafer surface, and the shear force decreases accordingly. Therefore, the opening control parameter needs to be corrected according to the actual distance between the wafer and the valve, so that the opening control parameter decreases when the wafer is close to the valve and increases when the wafer is far from the valve.

[0047] Specifically, the distance between the wafer and the extraction valve is denoted as L1, and the distance between the wafer and the isolation valve is denoted as L2. The smaller of the two values ​​is taken as the effective distance Le, i.e., Le equals the smaller of L1 and L2. This value selection strategy ensures that the control system is corrected based on the valve closest to the wafer, guaranteeing that the particle protection requirements at the most stringent locations are met. The corrected opening control parameter is denoted as Ks, and the calculation relationship is Ks equal to Ki' multiplied by 1 plus the product of α and Le. Wherein, Ki' is the opening control parameter after flow compensation in step S103; α is the position correction coefficient, calibrated by the wafer surface particle protection test, in millimeters; Le is the effective distance, in millimeters. In this relationship, Le and Ks are positively correlated; when Le increases, Ks increases linearly, and when Le decreases, Ks decreases linearly.

[0048] In practical applications, the calibration process of the position correction coefficient α is carried out under standard test conditions. A standard test wafer is placed at different axial positions within the loading chamber, the evacuation valve is gradually opened, and the number of particles falling off the wafer surface is measured. The opening control parameter corresponding to the critical airflow velocity for particle lifting is determined. From this, the opening reduction relative to the reference position at each position is calculated, and α is then fitted to obtain the result. This coefficient reflects the quantitative relationship between the wafer position and the airflow shear force under a specific loading chamber geometry.

[0049] The proposed solution introduces wafer position correction after flow compensation, enabling the opening control parameters to be dynamically adjusted based on the real-time spatial distribution of the wafer within the chamber. Since the distance between the wafer and the valve directly determines the local airflow distribution and the magnitude of the wafer surface shear force, and the positive correlation between the distance and the opening control parameters ensures that the valve opening degree is additionally restricted when the wafer is close to the valve, the stepped pressure transition can achieve both efficient transition and precise spatial protection of the wafer surface cleanliness.

[0050] In one implementation, Ki' output in step S103 is 40%. The distance L1 between the wafer and the evacuation valve is 80 mm, and the distance L2 between the wafer and the isolation valve is 320 mm, with an effective distance Le of 80 mm. The position correction factor α is calibrated to 0.005 per millimeter, so Ks equals 40% multiplied by 1 plus the product of 0.005 and 80, which is 40% multiplied by 1.4, resulting in 56%. If the wafer is in the middle of the chamber, and both L1 and L2 are 200 mm, then Le is 200 mm, and Ks equals 40% multiplied by 1 plus the product of 0.005 and 200, which is 40% multiplied by 2.0, resulting in 80%.

[0051] Furthermore, the step of correcting the opening control parameters based on the distance between the wafer and the suction valve and isolation valve further includes: obtaining the size information of the wafer; and correcting the opening control parameters together based on the size information and position information of the wafer; wherein, for wafers at the same position, the wafer size is negatively correlated with the corresponding opening correction coefficient; and for wafers of the same size, the distance between the wafer edge and the valve is positively correlated with the opening correction coefficient.

[0052] In this embodiment, different process nodes in semiconductor manufacturing use wafers of different sizes, with mainstream specifications including 8-inch and 12-inch wafers. Wafer size not only determines the space occupied by the wafer within the loading chamber but also alters the relative distance between the wafer edge and the valve. At the same center position, the edge of a 12-inch wafer is closer to the chamber sidewall and valve than that of an 8-inch wafer, and its surface area affected by airflow is also larger. Therefore, correcting solely based on the distance between the wafer center and the valve may result in insufficient edge protection for large-size wafers. This further feature incorporates wafer size information into the correction system, working together with position information to determine the final opening control parameters.

[0053] Specifically, wafer size information is directly read from the process recipe of the equipment control system or obtained through size recognition sensors during wafer loading. The opening correction factor is denoted as β, and the jointly corrected opening control parameter is denoted as Kc. For wafers in the same position (i.e., when the distance between the wafer center and the valve is fixed), the larger the wafer size, the closer the wafer edge is to the valve, and the larger the area of ​​the wafer surface subjected to airflow shear force, resulting in a smaller opening correction factor β; the two are negatively correlated. For wafers of the same size, the smaller the distance between the wafer edge and the valve, the closer the wafer as a whole is to the valve, and the more significant the concentration effect of airflow at the wafer edge; the smaller the opening correction factor β; the two are positively correlated.

[0054] In practical applications, the jointly corrected opening control parameter Kc is equal to Ki' multiplied by β. Here, Ki' is the opening control parameter after flow compensation in step S103; β is the opening correction coefficient considering both wafer size and edge position. β is calculated as β equal to 1 plus the product of δ and Leedge, then divided by 1 plus the product of γ and D. Here, Leedge is the distance between the wafer edge and the nearest valve, in millimeters; D is the wafer diameter, in millimeters; δ is the edge position sensitivity coefficient, in millimeters; and γ is the size sensitivity coefficient, in millimeters. In this formula, Leedge is positively correlated with the numerator, causing β to increase as Leedge increases; D is positively correlated with the denominator, causing β to decrease as D increases. When Leedge decreases or D increases, β shows a decreasing trend, thus jointly reducing the opening control parameter and strengthening particle protection when the wafer is close to the valve or in the case of large-size wafers.

[0055] This application's solution incorporates both wafer size and location information into the correction system, enabling the opening control parameters to simultaneously reflect the wafer's spatial distribution and physical scale. Since wafer size directly determines the critical distance between the edge and the valve, as well as the total surface area affected by airflow, and the negative correlation between size and opening correction coefficients ensures stricter opening limits for larger wafers, this allows the stepped pressure transition control to adapt to the cleanliness protection requirements of different wafer sizes, avoiding edge protection blind spots that might result from single-location corrections.

[0056] Furthermore, the method also includes: obtaining the temperature value of the loading lock chamber; and correcting the opening control parameter based on the temperature value, wherein the temperature value is negatively correlated with the opening control parameter.

[0057] In this embodiment, during the pressure transition process in the loading lock chamber, the internal gas temperature and valve body temperature change with environmental conditions and the evacuation process. Temperature changes directly affect the gas viscosity coefficient and the physical state of the valve sealing material, thereby altering the gas flow characteristics and the valve's actual gas-carrying capacity. When the temperature rises, the gas viscosity coefficient increases, resulting in a decrease in the actual gas flow rate at the same valve opening. Furthermore, thermal expansion of the valve seals may reduce the effective valve orifice diameter. If the opening control parameters are not temperature-corrected, the actual pressure change rate will deviate from the expected value. Under high-temperature conditions, the pressure transition time may be prolonged, while under low-temperature conditions, excessive actual flow may lead to excessive gas flow velocity on the wafer surface. Therefore, the control system, based on the determined position-corrected opening control parameters, further introduces a temperature correction step.

[0058] Specifically, the temperature of the loading lock chamber is collected in real time by a temperature sensor installed on the side wall of the chamber or the valve body, and is denoted as T. The reference temperature is denoted as T0, which is calibrated by the equipment manufacturer or set according to the process formula, and is usually 20 degrees Celsius. The temperature-corrected opening control parameter is denoted as Kt, and the calculation relationship is Kt equal to the product of Kc multiplied by 1 minus η and T minus T0. Wherein, Kc is the opening control parameter after correction by both position and size in step S104; η is the temperature sensitivity coefficient, calibrated by temperature cycling test, in degrees Celsius; T is the current temperature value; and T0 is the reference temperature value. In this relationship, when T is greater than T0, T minus T0 is positive, and Kt decreases relative to Kc; when T is less than T0, T minus T0 is negative, and Kt increases relative to Kc. The temperature value and the opening control parameter are negatively correlated, ensuring that the valve opening degree is suppressed when the temperature rises and compensated when the temperature falls. After the above-mentioned flow compensation, position correction, combined size correction and temperature correction, the final output opening control parameter is denoted as Kt. Kt is used as the valve control input for opening the extraction valve during subsequent stages of execution.

[0059] The calibration of the temperature sensitivity coefficient η was conducted under a test environment where the temperature of the loading lock chamber was controllable. The chamber temperature was adjusted to multiple test points above and below the reference temperature. At each temperature point, a standard pressure transition process was performed, and the deviation between the actual pressure change rate and the expected value was measured. The correction slope of the opening control parameter for each 1 degree Celsius temperature change was obtained by least squares fitting, which is η.

[0060] In practical applications, the temperature correction stage follows the position correction stage, forming a three-tiered progressive parameter determination chain of flow compensation, position correction, and temperature correction. This chain ensures that the final output opening control parameters simultaneously match the gas flow characteristics of the current pressure range, the spatial distribution of the wafer within the chamber, and the real-time thermal state of the chamber. While the magnitude of temperature correction is typically smaller than that of position correction, neglecting temperature correction in high-temperature environments or under conditions of frequent chamber door opening and closing will lead to a significant increase in pressure transition time or inaccurate control of the gas flow velocity on the wafer surface.

[0061] S105, the suction valve is opened according to the opening control parameters corrected in the first stage, so that the pressure enters the second stage; when the first stage and the second stage are connected, the suction valve is closed; when the pressure change rate is less than the stability determination threshold, the pressure is determined to be stable, and then the suction valve is reopened according to the opening control parameters corrected in the second stage.

[0062] In this embodiment, after all corrections are completed and the final opening control parameter Kt is output in step S104, the control system enters the execution phase. During the first phase of execution, the control system outputs Kt as the opening control parameter for the first phase to the drive unit of the pump valve, causing the pump valve to open to the corresponding opening degree. The gas inside the loading lock chamber is discharged through the pump valve under the action of the vacuum pump group, and the chamber pressure decreases from the initial pressure value of the first phase to the final pressure value.

[0063] Specifically, the corrected opening control parameter in the first stage is denoted as K1, which is the Kt value output in step S104. The control system sends an opening command to the extraction valve, and the valve plate of the extraction valve opens to the mechanical position corresponding to K1, with the gas conduction area proportional to K1. As the extraction process proceeds, the pressure in the loading lock chamber continues to decrease. When the pressure drops to the first stage termination pressure value, the control system issues a valve closing command, the extraction valve closes, and the first stage ends.

[0064] During the transition between the first and second stages, the control system closes the extraction valve and enters the pressure stabilization assessment stage. Because the gas distribution inside the chamber may be locally uneven after the extraction valve is closed, and the valve closure action causes temporary fluid disturbances, it is necessary to wait for the chamber pressure field to homogenize before entering the second stage. Pressure stabilization is assessed by monitoring the rate of pressure change. When the rate of pressure change is less than the stabilization threshold, it indicates that the internal pressure of the chamber has reached dynamic equilibrium, and it is safe to proceed to the next stage.

[0065] The pressure change rate is denoted as dP / dt, which is the pressure change per unit time. The stability threshold Ps is estimated based on the chamber volume V and the viscosity coefficient μ corresponding to the gas type, Ps = k·μ / V, where k is a proportionality factor related to the minimum measurable pressure change of the sensor, determined by on-site debugging. For a typical loading lock with nitrogen and a chamber volume of 50 liters, Ps is usually taken as 0.3~0.5 Pa / s. When the absolute value of dP / dt is less than Ps, the control system determines that the pressure is stable and outputs the second-stage opening command. The corrected opening control parameter for the second stage is denoted as K2, which is calculated by step S104 for the second-stage pressure range. The control system reopens the evacuation valve according to K2, allowing the pressure to continue transitioning from the initial pressure value of the second stage to the target pressure value.

[0066] The proposed solution avoids pressure overshoot or control instability caused by flow state switching between different stages during continuous pumping by inserting a valve closure stability determination step at the stage transition. It is precisely because the pumping valve is actively closed between stages and the pressure field is allowed to homogenize that the initial pressure value at the start of the second stage accurately corresponds to the stage boundary point, providing boundary conditions for the accurate execution of independent control strategies in subsequent stages.

[0067] In one implementation, the first-stage corrected opening control parameter K1 is 30.8%. The control system outputs an opening command, and the suction valve opens to 30.8%, causing the pressure in the loading lock chamber to drop from 1.01 × 10⁵ Pa to 5.05 × 10⁴ Pa. When the pressure reaches 5.05 × 10⁴ Pa, the control system closes the suction valve and monitors the pressure change rate. A stability threshold Ps is set at 0.5 Pa / s; when the pressure change rate is less than 0.5 Pa / s for three consecutive sampling periods, the pressure is considered stable. The second-stage corrected opening control parameter K2 is 35%. Based on K2, the control system reopens the suction valve, and the pressure continues to transition towards 1.33 × 10⁻¹ Pa.

[0068] Furthermore, in some embodiments, the method further includes: opening the vent valve according to the opening control parameters corrected in the first stage; then, the method further includes: monitoring the pressure change rate of the loading lock chamber; when the deviation between the pressure change rate and the expected pressure change rate corresponding to the current stage exceeds the deviation threshold, closing the vent valve, recording the current pressure change rate, the actual valve opening, the wafer position, and the temperature value, and generating an abnormality prompt message; when the same abnormality occurs consecutively a set number of times, prohibiting subsequent pressure transition operations.

[0069] In this embodiment, during the pressure transition process after the vacuum valve opens, the control system needs to continuously monitor whether the actual pressure change follows the expected trajectory. Because the vacuum system may experience abnormal operating conditions such as valve mechanical jamming, sensor drift, chamber leakage, or performance degradation of the vacuum pump unit, the actual pressure change rate may deviate from the design value. If these issues are not identified and addressed in a timely manner, it may lead to uncontrolled pressure transition time or abnormal airflow conditions on the wafer surface.

[0070] Specifically, the expected pressure change rate is denoted as Vp, calculated from the stage pressure difference and the expected stage duration; that is, Vp equals the stage pressure difference divided by the expected stage duration. The actual pressure change rate is denoted as Va, obtained by real-time acquisition and differential calculation from the pressure sensor. The deviation is denoted as ΔV, which equals the absolute value of the difference between Va and Vp. The deviation threshold is denoted as Vth, determined by a statistical calibration method: under standard operating conditions, N pressure transitions are performed, and the deviation distribution between the actual pressure change rate and the expected value at each stage is recorded. The mean deviation plus three times the standard deviation is taken as Vth, i.e., Vth = μΔV + 3σΔV, where μΔV is the mean deviation and σΔV is the standard deviation. When ΔV is greater than Vth, the control system determines that there is an anomaly in the current stage and immediately performs a protective valve closing operation, closing the suction valve and cutting off the connection between the loading lock chamber and the vacuum pump group to prevent the abnormal operating condition from escalating.

[0071] The system records the current pressure change rate, actual valve opening, wafer position, and temperature value. This means the control system writes multi-dimensional state parameters at the moment of the anomaly into non-volatile memory, forming a traceable anomaly log. These parameters reflect the states of the pressure control loop, valve actuator, wafer spatial position, and thermal environment at the instant of the anomaly, providing a data foundation for subsequent fault diagnosis. Generating anomaly alerts involves the control system outputting an anomaly code and an anomaly occurrence stage identifier to the equipment's human-machine interface.

[0072] When the same anomaly occurs a set number of times consecutively, the control system determines that the anomaly has systematic characteristics rather than a random disturbance, and prohibits subsequent pressure transition operations. This prohibition mechanism is implemented by setting a pressure transition enable flag. After the flag is cleared, the equipment refuses to execute new wafer loading and pressure transition commands until maintenance personnel complete the fault diagnosis and manually reset it.

[0073] The proposed solution introduces pressure change rate deviation monitoring and graded abnormal response during phased execution, enabling the control system to identify abnormal behavior in the pressure control loop within a millisecond timescale. Since the deviation between the actual pressure change rate and the expected value directly reflects the integrity of the transmission link from control commands to physical responses, and the deviation threshold and continuous counting mechanism prevent erroneous shutdowns caused by single disturbances, this anomaly detection strategy ensures both equipment safety and production continuity.

[0074] In one implementation, the expected pressure change rate Vp in the first stage is 1.01 × 10⁵ Pa / s, the actual monitored pressure change rate Va is 1.5 × 10⁵ Pa / s, the deviation ΔV is 0.49 × 10⁵ Pa / s, and the deviation threshold Vth is set to 0.3 × 10⁵ Pa / s. Since ΔV is greater than Vth, the control system determines an anomaly, closes the extraction valve, records the current pressure change rate (1.5 × 10⁵ Pa / s), the actual valve opening (30.8%), the wafer position, and the temperature value, and generates an anomaly warning message. If this anomaly occurs repeatedly in three consecutive pressure transitions, the control system prohibits subsequent pressure transition operations.

[0075] Furthermore, in some embodiments, after opening the suction valve according to the opening control parameters corrected in the first stage, the method further includes: monitoring the pressure change rate of the loading lock chamber; adjusting the opening of the suction valve according to the deviation between the pressure change rate and the expected pressure change rate corresponding to the first stage; wherein, when the pressure change rate is greater than the expected pressure change rate, the opening of the suction valve is reduced; and when the pressure change rate is less than the expected pressure change rate, the opening of the suction valve is increased.

[0076] In this embodiment, during normal pressure transition, even if the abnormal threshold is not triggered, the actual pressure change rate may still deviate slightly from the expected value. This deviation originates from the transient characteristics of gas flow state transition, valve mechanical hysteresis, and the slow change of the internal temperature field of the chamber. To maintain the pressure change trajectory within each stage close to the design curve, the control system introduces real-time closed-loop regulation during stage execution, dynamically fine-tuning the opening of the extraction valve based on the deviation between the actual pressure change rate and the expected value.

[0077] Specifically, the expected pressure change rate Vp is determined by the stage pressure difference and the expected duration of the stage. The actual pressure change rate Va is acquired in real time by a pressure sensor. When Va is greater than Vp, it indicates that the actual pumping rate is higher than expected, and the chamber pressure drops too quickly, which may cause the gas flow velocity on the wafer surface to momentarily exceed the limit or the pressure to overshoot at the end of the stage. In this case, the control system reduces the opening of the pumping valve to reduce the gas conduction area, causing Va to fall back. When Va is less than Vp, it indicates that the actual pumping rate is lower than expected, and the pressure transition time will be prolonged. In this case, the control system increases the opening of the pumping valve to increase the gas conduction area, causing Va to rise again.

[0078] Specifically, decreasing or increasing the opening of the extraction valve involves the control system outputting incremental or decremental adjustment commands based on the current opening control parameters. The adjustment range is determined by the proportional adjustment coefficient to avoid oscillations caused by excessively large single adjustments. This closed-loop control is executed cyclically with the sampling period as the time base until the stage ends or an abnormal threshold is triggered.

[0079] The adjustment of the opening of the extraction valve includes: determining the adjustment amount of the opening of the extraction valve based on the proportion of the execution time in the first stage to the total expected time of the stage: when the execution time in the first stage does not exceed half of the total expected time, the opening adjustment amount is a first adjustment amount; when the execution time in the first stage exceeds half of the total expected time, the opening adjustment amount is a second adjustment amount; the first adjustment amount is greater than the second adjustment amount.

[0080] In this embodiment, during the phased execution process, the closed-loop adjustment of the pressure change rate deviation needs to consider the differences in control requirements at different times within the phase. In the early stage of the phase, the chamber pressure is high, the gas molecule density is large, and the effect of valve opening changes on the gas conductance is approximately linear. At this time, a larger opening adjustment is allowed to quickly eliminate the deviation. In the later stage of the phase, the chamber pressure approaches the phase termination value, the gas molecule density decreases, and the flow state may be in the transition flow or molecular flow range. The valve opening and gas conductance exhibit a non-linear relationship, and the risk of wafer surface particle agitation is more sensitive to changes in airflow velocity. At this time, a smaller opening adjustment is required to avoid pressure overshoot or instantaneous peak airflow velocity caused by excessive adjustment.

[0081] Specifically, the executed time is denoted as t, the total expected time is denoted as Ttotal, and the proportion is denoted as R, where R equals t divided by Ttotal. The first adjustment is denoted as ΔK1, and the second adjustment is denoted as ΔK2. When R is less than or equal to 0.5, the control system uses ΔK1 as the single opening adjustment step size; when R is greater than 0.5, the control system uses ΔK2 as the single opening adjustment step size. ΔK1 and ΔK2 are calibrated during the equipment commissioning phase, and ΔK1 is greater than ΔK2.

[0082] The total expected time Ttotal is calculated by dividing the stage pressure difference by the expected pressure change rate Vp, representing the duration of the stage under ideal operating conditions. The executed time t is accumulated by the internal timer of the control system from the start of the stage. By using half of the total expected time as the dividing point, the stage execution process is divided into a first half and a second half, and different opening adjustment amounts are configured for each half, achieving fine-grained switching of the control strategy within the stage.

[0083] Based on this, by introducing a time-proportion-based segmented adjustment strategy within each stage, the opening adjustment step size can be matched with the stage execution progress. Since there are significant differences in gas flow characteristics, control sensitivity requirements, and particle protection needs between the early and late stages of the stage, the configuration of the first adjustment amount being greater than the second adjustment amount ensures rapid convergence in the early stage and fine stability in the later stage. This allows the closed-loop regulation to improve pressure control accuracy while avoiding pressure overshoot and abnormal airflow velocity at the end of the stage.

[0084] Furthermore, when the extraction valve is reopened according to the opening control parameters corrected in the second stage, such as Figure 3 As shown, the following delay correction steps are also included: S3001, Obtain the mechanical response delay time of the air extraction valve; In this embodiment, during the transition between the first and second stages, after the control system determines that the pressure has stabilized, it needs to reopen the extraction valve to initiate the second stage of extraction. There is an inherent mechanical response delay between the extraction valve receiving the electrical signal from the control system and the valve plate actually moving to the target opening position. This delay is composed of the excitation time of the electromagnetic drive coil, the static friction breakthrough time of the valve plate seal, and the inertial response time of the mechanical transmission mechanism. If the control system sends the valve opening signal only at the instant the pressure reaches the initial pressure value of the second stage, the actual valve opening time will lag behind the pressure arrival time, resulting in a no-extraction window period at the beginning of the second stage. During this window period, the chamber pressure may slightly rise due to minor external leakage or internal degassing, affecting the pressure transition accuracy. Therefore, it is necessary to obtain the mechanical response delay time of the extraction valve in advance before sending the valve opening signal as a time reference for sending the control signal ahead of time.

[0085] Specifically, the mechanical response delay time is obtained through the command response timing module inside the valve controller. Under standard operating conditions, the control system sends an opening command to the extraction valve and simultaneously starts a timer. The timer stops when the valve position feedback sensor detects that the valve plate has reached 90% of the commanded opening, and this duration is recorded as the reference delay time T0. The reference delay time T0 is calibrated during equipment commissioning or periodic maintenance and stored in the non-volatile memory of the control system. For extraction valves with pneumatic actuators, the reference delay time is typically 50 to 200 milliseconds; for extraction valves with electric actuators, the reference delay time is typically 100 to 500 milliseconds. This reference value reflects the inherent mechanical response characteristics of the valve under standard temperature and standard opening changes.

[0086] S3002, based on the temperature deviation of the air extraction valve at the current temperature relative to the standard temperature, and the opening deviation of the current opening degree relative to the reference opening degree, the mechanical response delay time is corrected; In this embodiment, the mechanical response delay of the extraction valve is not a constant value, but drifts with changes in ambient temperature and target opening degree. Temperature changes affect the resistance of the electromagnetic coil, the elastic modulus of the sealing material, and the viscosity of the lubricating medium, thereby altering the valve's opening and closing dynamics. The amount of opening degree change affects the stroke length and inertial load of the mechanical transmission mechanism; the mechanical response delay corresponding to a large stroke adjustment is usually greater than that for a small stroke adjustment. Therefore, based on the reference delay time T0, temperature deviation and opening degree deviation need to be introduced for real-time correction.

[0087] Specifically, the current temperature is denoted as T, and is collected in real time by a temperature sensor installed on the valve body or drive unit of the extraction valve. The standard temperature is denoted as Tstd, and is determined by the equipment factory calibration, typically 20 degrees Celsius. The temperature deviation is denoted as ΔT, which equals T minus Tstd. The current opening degree is denoted as K, which is the opening control parameter after the second stage correction. The reference opening degree is denoted as Kstd, and is determined by the test opening degree during reference delay time calibration, typically 50% opening degree. The opening degree deviation is denoted as ΔK, which equals K minus Kstd.

[0088] The corrected mechanical response delay time, denoted as Tcorr, is calculated using the following formula: Tcorr = T0 × (1 + θ·ΔT) × (1 + φ·ΔK) In the formula, T0 is the reference delay time, obtained by calibration of the valve controller under standard operating conditions; θ is the temperature correction coefficient, calibrated by temperature cycling tests, in units of per degree Celsius, reflecting the relative rate of change of delay time for every 1 degree Celsius change in temperature; ΔT is the temperature deviation of the current temperature relative to the standard temperature, ΔT = T - Tstd; φ is the opening correction coefficient, calibrated by opening step tests, in units of per percentage opening, reflecting the relative rate of change of delay time for every 1 percentage point change in opening; ΔK is the opening deviation of the current opening relative to the reference opening, ΔK = K - Kstd. When the temperature is higher than the standard temperature, ΔT is positive. If θ is positive, the increase in temperature leads to an increase in delay time; if θ is negative, the increase in temperature leads to a decrease in delay time. When the target opening is greater than the reference opening, ΔK is positive. If φ is positive, large stroke adjustment leads to an increase in delay time.

[0089] In practical applications, the signs and values ​​of the temperature correction factor θ and the opening correction factor φ are determined by the mechanical characteristic curves provided by the valve manufacturer or by on-site calibration tests. For pneumatic valves using fluororubber seals, increased temperature typically softens the seals and reduces friction, so θ may be negative. For electric valves using metal bellows seals, increased temperature may thin the grease and reduce damping, so θ may be positive. The opening correction factor φ is usually positive because when the valve is opened from the fully closed position to a greater degree of opening, the mechanical transmission mechanism needs to overcome a greater inertial load and gas pressure differential resistance.

[0090] S3003, based on the corrected delay time, before the pressure in the loading lock chamber reaches the pressure range corresponding to the second stage, a valve opening control signal is sent in advance.

[0091] In this embodiment, after obtaining the corrected mechanical response delay time Tcorr, the control system needs to calculate the timing for sending the valve opening control signal in advance. This advance ensures that when the valve's mechanical action is completed and the valve plate actually reaches the target opening degree, the pressure in the loading lock chamber just enters the pressure range corresponding to the second stage, achieving timing synchronization between mechanical action and pressure change.

[0092] Specifically, the control system monitors the pressure value P and the current pressure change rate dP / dt of the loading lock chamber in real time. The starting value of the pressure range corresponding to the second stage is denoted as P2start. The remaining pressure difference is denoted as ΔPrem, which is equal to the current pressure value P minus P2start. The estimated arrival time is denoted as test, which is equal to ΔPrem divided by the absolute value of dP / dt. When test is less than or equal to Tcorr, the control system immediately sends a valve opening control signal. This signal is transmitted to the extraction valve through the valve drive circuit. After a mechanical response delay of Tcorr, the valve actually opens. At this time, the chamber pressure drops to around P2start, and the second stage of extraction is seamlessly connected.

[0093] This embodiment eliminates control timing deviations caused by valve mechanical inertia by introducing the acquisition, correction, and advance compensation of mechanical response delay time during stage transitions. Since the mechanical response delay of the extraction valve dynamically changes due to temperature and opening degree, the reference delay time combined with the correction mechanism for temperature and opening degree deviations can track this dynamic change in real time. This allows the timing of the advance control signal transmission to precisely match the actual physical moment of valve opening, avoiding pressure gaps and airflow disturbances at the beginning of the second stage.

[0094] S106, in response to the pressure in the loading lock chamber matching the target pressure value, the evacuation valve is closed and the isolation valve is opened to establish communication between the loading lock chamber and the adjacent process chamber.

[0095] In this embodiment, during the second stage of execution, the control system continuously compares the real-time pressure value of the loading lock chamber with the target pressure value of the adjacent process chamber. When the absolute value of the difference between the two is less than the pressure matching threshold, it is determined that the pressure matches the target pressure value. At this time, the pressure difference between the loading lock chamber and the adjacent process chamber has been eliminated, and the physical conditions for establishing a direct connection are met.

[0096] Specifically, the pressure matching threshold, denoted as Pmth, is determined jointly by the pressure control accuracy of adjacent process chambers and the minimum measurable pressure change of the pressure sensor in the loading lock chamber. Alternatively, Pmth can be the larger of one-third of the pressure control accuracy of adjacent process chambers and the minimum measurable pressure change of the pressure sensor in the loading lock chamber, i.e., Pmth = max(σprocess / 3, Presolution), where σprocess is the standard deviation of the process chamber pressure, and Presolution is the minimum measurable pressure change of the sensor.

[0097] When the absolute value of the difference between the real-time pressure value and the target pressure value is less than Pmth, the control system sequentially performs valve closing and valve opening operations. First, the evacuation valve is closed to cut off the passage between the loading lock chamber and the vacuum pump unit, preventing the vacuum pump unit from directly acting on the process chamber and causing pressure disturbances after the adjacent process chambers are connected. Then, the isolation valve is opened to eliminate the physical barrier between the loading lock chamber and the adjacent process chamber, forming a common vacuum space, allowing the wafer to be transferred between the chambers.

[0098] Establishing connectivity between the loading lock chamber and the adjacent process chamber means that after the isolation valve is opened, the gas between the two chambers can freely exchange, the pressure tends to be consistent, and the wafer transfer mechanism can move the wafer from the wafer carrier in the loading lock chamber to the wafer receiving position in the adjacent process chamber. The establishment of this connectivity marks the completion of the pressure transition process in the loading lock chamber, and the equipment enters the wafer handover stage.

[0099] Furthermore, before closing the air extraction valve and opening the isolation valve, the method further includes: introducing clean gas into the loading lock chamber, wherein the flow rate of the clean gas is positively correlated with the pressure value of the loading lock chamber at the current stage; and simultaneously opening the air extraction valve so that the clean gas flows through the loading lock chamber and is discharged through the air extraction valve.

[0100] In this embodiment, before the pressure transition is nearly complete and the connection between the two chambers is established, trace amounts of atmospheric moisture, oxygen, or particulate contaminants may remain inside the loading lock chamber. If the isolation valve is opened directly, these residues may enter the adjacent process chamber with the airflow, contaminating the process environment or affecting the wafer surface quality. Therefore, a cleaning gas purging step is introduced before final connection, using inert gas or high-purity nitrogen to replace the residual gas inside the chamber, and continuously evacuating to remove contaminants.

[0101] Specifically, the cleaning gas is introduced through a purge inlet on the side wall or top of the loading lock chamber. The inlet is typically equipped with a diffuser to reduce the inlet gas velocity and prevent the formation of localized high-speed airflow. The flow rate of the cleaning gas is denoted as Q and is regulated by a mass flow controller. The flow rate is positively correlated with the pressure value of the loading lock chamber at the current stage; that is, the higher the current pressure, the larger the setpoint for the cleaning gas flow rate; the lower the current pressure, the smaller the setpoint for the cleaning gas flow rate. This positive correlation is determined by the balance requirements between purging efficiency and vacuum compatibility: at higher pressures, the residual gas molecules in the chamber are denser, requiring a larger flow rate of cleaning gas for effective dilution and replacement; at lower pressures, an excessively large cleaning gas flow rate will prolong the evacuation time, increase the load on the vacuum pump unit, and may introduce unnecessary turbulence.

[0102] Simultaneously opening the extraction valve allows clean gas to flow through the loading lock chamber and then exit through the extraction valve. This means that after the clean gas enters the loading lock chamber through the inlet, it forms a directional flow path from the inlet to the extraction valve inside the chamber. This carries trace amounts of moisture and suspended particles detached from the chamber walls and exits through the extraction valve into the vacuum pump assembly system. This flow path covers the area around the wafer carrier and the dead corners of the chamber, achieving active cleaning of the environment surrounding the wafer. The purging duration is determined by the remaining time of the pressure transition phase and the purging flow rate, and is typically set to 5 to 15 seconds.

[0103] In practical applications, the positive correlation between flow rate and pressure is achieved using a lookup table. The control system queries a preset flow rate setting table based on the current pressure value. This table is calibrated during the process development phase through particle counting experiments to ensure that the purging flow rate at each pressure level maintains the gas replacement efficiency inside the chamber without causing particles to be stirred up from the wafer surface due to excessive flow velocity. For example, when the current pressure value is in the range of 10³ Pa, the flow rate setting is set to a higher value; when the current pressure value drops to the range of 10¹ Pa, the flow rate setting is reduced to a lower value. The flow rate setting table is established through particle counting experiments: after purging at different pressure levels with different flow rates, the residual particle amount in the chamber is measured, and the minimum flow rate at which the residual particle amount is lower than the cleanliness index is selected as the setting value for that pressure level, forming a pressure-flow rate correspondence table.

[0104] This embodiment divides the pressure transition process of the loading lock chamber into multiple stages, and combines the gas flow characteristics, wafer spatial position and size information, and real-time temperature status of the chamber for dynamic valve control in each stage, thereby achieving synergistic optimization of wafer surface cleanliness protection and pressure transition efficiency.

[0105] By establishing a negative correlation between stage pressure difference and valve opening control parameters, this embodiment actively limits the valve opening degree during stages with large pressure differences, thereby controlling the gas flow rate below the particle uplift threshold and avoiding particle contamination caused by excessive shear force generated by high-speed airflow on the wafer surface. Simultaneously, a nonlinear compensation correction based on gas flow regime is introduced to ensure that the actual mapping relationship between valve opening degree and gas conductivity remains accurate across different pressure ranges, eliminating control deviations caused by flow regime transitions and ensuring the stability of the pressure change rate in each stage.

[0106] By introducing wafer position correction and size joint correction, this embodiment enables the valve opening to be dynamically adjusted according to the actual spatial distribution of the wafer within the chamber and the physical dimensions of the wafer. When the wafer is close to the extraction valve or isolation valve, the opening control parameter is reduced accordingly, reducing the local airflow concentration effect; the edge region of large-size wafers receives stricter opening restrictions, eliminating edge protection blind spots that may result from single position correction. The temperature correction compensates for the impact of changes in the chamber's thermal state on the valve's mechanical response and gas flow characteristics, ensuring that the control strategy maintains the expected design performance under different thermal conditions.

[0107] During the transition between stages, this embodiment closes the extraction valve and monitors the rate of pressure change to determine stability before starting the next stage. This avoids pressure overshoot and airflow disturbance caused by flow state switching during continuous extraction. By acquiring and correcting the mechanical response delay time of the extraction valve, the control system can send the valve opening signal in advance before the pressure reaches the next stage interval, eliminating timing deviations caused by valve mechanical inertia and achieving seamless pressure transition between stages.

[0108] Before establishing communication between the loading lock chamber and the adjacent process chamber, this embodiment introduces a cleaning gas purging step, which makes the cleaning gas flow rate positively correlated with the current pressure value. This achieves effective replacement during the high-pressure stage and avoids excessive disturbance during the low-pressure stage, significantly reducing the risk of cross-contamination when communicating between chambers and providing a clean transition environment for the wafer to enter the process chamber.

[0109] Furthermore, through real-time closed-loop regulation of the pressure change rate within a stage and an anomaly detection mechanism, this embodiment can maintain the pressure change trajectory close to the design curve under normal operating conditions, and promptly identify and execute protective valve shut-off operations under abnormal operating conditions, avoiding potential damage to wafers and equipment caused by pressure runaway, and improving the reliability and safety of the vacuum control system.

[0110] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber, characterized in that, include: Obtain wafer position information, current pressure value, and target pressure value of adjacent process chambers within the loading lock chamber; Based on the pressure difference between the current pressure value and the target pressure value, the pressure transition process is divided into at least a first stage and a second stage; wherein the first stage corresponds to the interval from the current pressure value to the intermediate pressure value, and the second stage corresponds to the interval from the intermediate pressure value to the target pressure value. The pressure transition process is divided into at least a first stage and a second stage, including: determining the number of stages and the pressure range corresponding to each stage based on historical pressure transition data under the same wafer size and the same target pressure; wherein, the historical pressure transition data includes historical pressure change rate and historical stabilization time; For each stage, the opening control parameter is determined based on the pressure difference between its starting and ending pressures. The pressure difference is negatively correlated with the opening control parameter to limit the gas flow rate and prevent particles from being lifted off the wafer surface. The opening control parameter is then compensated and corrected based on the nonlinear relationship between the opening and the gas conductivity under the corresponding gas flow state in the current pressure range. The opening control parameter is corrected based on the distance between the wafer and the suction valve and isolation valve, wherein the distance is positively correlated with the opening control parameter; the correction of the opening control parameter based on the distance between the wafer and the suction valve and isolation valve further includes: obtaining the wafer size information; and correcting the opening control parameter based on the wafer size information and position information; wherein, for wafers at the same position, the wafer size is negatively correlated with the corresponding opening correction coefficient; and for wafers of the same size, the distance between the wafer edge and the valve is positively correlated with the opening correction coefficient. The air extraction valve is opened according to the opening control parameters after the first stage correction, so that the pressure enters the second stage; when the first stage and the second stage are connected, the air extraction valve is closed; when the pressure change rate is less than the stability determination threshold, the pressure is determined to be stable, and then the air extraction valve is reopened according to the opening control parameters after the second stage correction. When the pressure in the loading lock chamber matches the target pressure value, the evacuation valve is closed and the isolation valve is opened to establish communication between the loading lock chamber and the adjacent process chamber.

2. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 1, characterized in that, Before closing the air extraction valve and opening the isolation valve, the method further includes: introducing clean gas into the loading lock chamber, wherein the flow rate of the clean gas is positively correlated with the pressure value of the loading lock chamber at the current stage; and simultaneously opening the air extraction valve so that the clean gas flows through the loading lock chamber and is discharged through the air extraction valve.

3. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 1, characterized in that, The method further includes: Obtain the temperature value of the loading lock chamber; The opening control parameter is adjusted based on the temperature value, and the temperature value is negatively correlated with the opening control parameter.

4. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 1, characterized in that, After opening the extraction valve according to the opening control parameters revised in the first stage, the method further includes: Monitor the pressure change rate of the loading lock chamber; when the deviation between the pressure change rate and the expected pressure change rate corresponding to the current stage exceeds the deviation threshold, close the vent valve, record the current pressure change rate, the actual valve opening, the wafer position and temperature value, and generate an abnormality prompt message; when the same abnormality occurs consecutively a set number of times, subsequent pressure transition operations are prohibited.

5. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 1, characterized in that, After opening the extraction valve according to the opening control parameters revised in the first stage, the process further includes: Monitor the rate of pressure change in the loading lock chamber; The opening of the suction valve is adjusted based on the deviation between the pressure change rate and the expected pressure change rate corresponding to the first stage; wherein, when the pressure change rate is greater than the expected pressure change rate, the opening of the suction valve is decreased; and when the pressure change rate is less than the expected pressure change rate, the opening of the suction valve is increased.

6. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 5, characterized in that, Adjusting the opening of the suction valve includes: The adjustment amount of the air extraction valve opening is determined based on the proportion of the execution time in the first stage to the total expected time of the stage: when the execution time in the first stage does not exceed half of the total expected time, the opening adjustment amount is the first adjustment amount; when the execution time in the first stage exceeds half of the total expected time, the opening adjustment amount is the second adjustment amount; the first adjustment amount is greater than the second adjustment amount.

7. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 6, characterized in that, When the extraction valve is reopened according to the opening control parameters corrected in the second stage, the following steps are also included: Obtain the mechanical response delay time of the air extraction valve; The mechanical response delay time is corrected based on the temperature deviation of the extraction valve at the current temperature relative to the standard temperature, and the opening deviation of the current opening degree relative to the reference opening degree. Based on the corrected delay time, the valve opening control signal is sent in advance before the pressure in the loading lock chamber reaches the pressure range corresponding to the second stage.

8. The method for controlling a stepped pressure transition valve in a semiconductor vacuum chamber according to claim 1, characterized in that, The method of dividing the pressure transition process into at least a first stage and a second stage further includes: adjusting the number of stages and the pressure range width corresponding to each stage according to the wafer position information; wherein, when the distance between the wafer and the suction valve or the isolation valve is less than a first distance threshold, the number of stages is increased and the pressure range width of each stage is narrowed; when the distance between the wafer and the suction valve or the isolation valve is greater than a second distance threshold, the number of stages is reduced and the pressure range width of each stage is widened.

Images