Pressure control method, device and semiconductor process equipment

Abstract

The present invention discloses a pressure control method, device and semiconductor process equipment, the method includes: obtaining the actual pressure value in the process chamber in real time; calculating the maximum difference between the initial actual pressure value and the target pressure value in the process chamber, and determining the initial frequency of the actuator of the corresponding pressure regulating valve based on the maximum difference; calculating the pressure change of the actual pressure value, comparing the pressure change with a preset value, when the pressure change is less than or equal to the preset value, controlling the actuator to maintain the current frequency, when the pressure change is greater than the preset value, the frequency of the actuator decreases according to a preset function relationship until the actual pressure value reaches the target pressure value. The problem of pressure overshoot in the process of rapid chamber pressure control is solved, and the influence of pressure fluctuation on the process is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and more specifically, to a pressure control method, device and semiconductor process equipment. Background Art

[0002] In the fields of semiconductor manufacturing, photovoltaics, etc., process chambers such as oxidation furnaces are one of the most important equipment in the semiconductor process. H2, HCL, excess O2, a small amount of C2H2Cl2 and N2 entering the oxidation furnace process chamber need to react chemically under constant pressure to ensure the thickness of the coating. The pressure in the process chamber greater than or less than the set pressure will affect the thickness of the coating, so the pressure in the process chamber must be stable. How to accurately and quickly control the pressure in the chamber has become a core technical problem that needs to be solved urgently.

[0003] The prior art CN111831022A proposes a chamber pressure control method, which realizes rapid pressure control based on the PTL (Pressure To Location) strategy. The technology adopts the PTL strategy according to the fast opening characteristics of the pressure regulating valve, that is, the closed-loop PID control coefficient is dynamically and autonomously adjusted, and the PID fine adjustment is realized based on the PTL conversion coefficient Kn (the conversion coefficient between pressure change and butterfly valve opening) and the PID coefficient, thereby achieving the purpose of rapid and stable pressure control.

[0004] Although this technology can perform pressure control relatively quickly, that is, it can respond quickly when relevant parameters (such as flow rate, pressure, etc.) change during the process, due to the certain hysteresis characteristics of the pressure system, overly rapid adjustment is prone to overshoot, and the chamber pressure fluctuation caused by overshoot will affect the process results. Summary of the invention

[0005] The purpose of the present invention is to provide a pressure control method, device and semiconductor process equipment to solve the problem of pressure overshoot in the process of rapid chamber pressure control and reduce the influence of pressure fluctuations on the process.

[0006] In a first aspect, the present invention proposes a pressure control method, which is applied to a process chamber of a semiconductor process equipment, wherein a pressure regulating valve is provided on a gas pipeline of the process chamber for regulating the pressure in the process chamber, and the method comprises:

[0007] Acquiring the actual pressure value in the process chamber in real time;

[0008] Calculating a maximum difference between an initial actual pressure value and a target pressure value in the process chamber, and determining an initial frequency of an actuator of the corresponding pressure regulating valve based on the maximum difference;

[0009] Calculate the pressure change of the actual pressure value, compare the pressure change with a preset value, and when the pressure change is less than or equal to the preset value, control the actuator to maintain the current frequency; when the pressure change is greater than the preset value, the frequency of the actuator decreases according to a preset functional relationship until the actual pressure value reaches the target pressure value.

[0010] Optionally, calculating the pressure change of the actual pressure value includes:

[0011] A first difference between a first actual pressure value at a first moment in the process chamber and the target pressure value is calculated, and a second difference between a second actual pressure value at a second moment and the target pressure value is calculated, wherein the pressure change is a ratio of a difference between the first difference and the second difference to the maximum difference.

[0012] Optionally, calculating the pressure change of the actual pressure value includes:

[0013] A first difference between a first actual pressure value at a first moment in the process chamber and the target pressure value is calculated, and a second difference between a second actual pressure value at a second moment and the target pressure value is calculated, wherein the pressure change is a ratio of a difference between the first difference and the second difference to the first difference.

[0014] Optionally, the first actual pressure value and the second actual pressure value are adjacent to each other, and when the pressure change is greater than zero, as the difference between the actual pressure value and the target pressure value decreases, the frequency of the actuator decreases according to the preset functional relationship.

[0015] Optionally, the preset functional relationship is: i+1 =K*F i , where F i is the current frequency of the actuator, F i+1 is the next frequency of the actuator, K is between 0 and 1, i=1, 2, 3, ..., n, wherein F1 is the initial frequency, and the initial frequency is the maximum frequency of the actuator that does not produce resonance.

[0016] Optionally, the pressure control method adopts PID closed-loop control.

[0017] Optionally, the actual pressure value is an absolute pressure value inside the chamber;

[0018] Alternatively, the actual pressure value is a relative value between the internal pressure of the chamber and the atmospheric pressure.

[0019] In a second aspect, the present invention provides a chamber pressure control device, comprising: a pressure collector, a pressure controller and an actuator;

[0020] The pressure collector is used to collect the actual pressure value in the chamber in real time;

[0021] The pressure controller is used to execute the chamber pressure control method described in the first aspect;

[0022] The actuator is used to control the opening change of the pressure regulating valve based on the frequency output by the pressure controller.

[0023] Optionally, the actuator is a motor that controls the opening of the pressure regulating valve, and the frequency of the actuator is the rotation frequency of the motor.

[0024] Optionally, the pressure regulating valve comprises an elastic telescopic member, so that the opening of the pressure regulating valve can be adjusted by the elastic telescopic member.

[0025] In a third aspect, the present invention proposes a semiconductor process equipment, including a process chamber, and a pressure regulating valve arranged on a gas pipeline of the process chamber, and also includes the chamber pressure control device described in the second aspect.

[0026] The beneficial effects of the present invention are:

[0027] The present invention obtains the actual chamber pressure value in real time during the pressure control process, first calculates the maximum difference between the initial actual pressure value and the target pressure value in the process chamber, and determines the initial frequency of the actuator of the corresponding pressure regulating valve based on the maximum difference, then calculates the pressure change of the actual pressure value, and compares the pressure change with a preset preset value. When the pressure change is less than or equal to the preset value, the actuator is controlled to maintain the current frequency. When the pressure change is greater than the preset value, the frequency of the actuator decreases according to a preset function relationship until the actual pressure value reaches the target pressure value. During the pressure control process, as the difference between the chamber pressure and the target pressure gradually decreases, the actuator frequency also gradually decreases, that is, as the pressure difference gradually decreases, the opening change rate of the pressure regulating valve gradually slows down. Therefore, the pressure overshoot phenomenon caused by pressure change or flow change during the pressure control process can be effectively reduced, so that the pressure control response time is faster and the pressure control is more stable. When the gas flow in the process chamber pressure control system is a staged decrease or increase change within a specified period of time, the method can significantly prevent pressure overshoot, thereby improving the process quality.

[0028] The device of the present invention has other characteristics and advantages, which will be obvious from the drawings incorporated herein and the following detailed description, or will be described in detail in the drawings incorporated herein and the following detailed description, which together are used to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0030] Figure 1 A step diagram of a pressure control method according to embodiment 1 of the present invention is shown.

[0031] Figure 2 A curve diagram of actuator frequency and pressure variation in a pressure control method according to Example 1 of the present invention is shown.

[0032] Figure 3 A schematic diagram of a chamber pressure control device according to embodiment 2 of the present invention is shown.

[0033] Figure 4 A schematic structural diagram of a semiconductor process equipment according to Embodiment 3 of the present invention is shown. DETAILED DESCRIPTION

[0034] In order to solve the problems existing in the prior art, the present invention proposes a pressure control method, device and semiconductor process equipment. The pressure control method is based on the input and output negative feedback characteristics of the pressure system. The entire pressure closed-loop control process adopts the method of step-by-step frequency conversion of the actuator to solve the problem of pressure overshoot in the process of rapid chamber pressure control, minimize the impact of pressure fluctuations on the process, and this method can be applied to different pressure control systems.

[0035] The present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0036] Example 1

[0037] like Figure 1 As shown, a pressure control method specifically includes the following steps:

[0038] S1: Obtain the actual pressure value in the process chamber in real time;

[0039] Optionally, the actual pressure value is an absolute pressure value inside the chamber, such as the pressure of the chamber at the exhaust port can be detected as the actual pressure value; or the actual pressure value is a relative value between the pressure inside the chamber and the atmospheric pressure. Therefore, the chamber pressure control method provided in this embodiment can be applied to an absolute pressure control method or a relative pressure control method.

[0040] S2: calculating the maximum difference between the initial actual pressure value and the target pressure value in the process chamber, and determining the initial frequency of the actuator of the corresponding pressure regulating valve based on the maximum difference;

[0041] Specifically, the initial actual pressure value in the process chamber can be obtained by a pressure sensor, the target pressure value is the pressure value required by the process, is the set value, and the initial frequency can be set according to an empirical value, which can be the maximum frequency of the actuator that does not produce resonance.

[0042] S3: Calculate the pressure change of the actual pressure value, and compare the pressure change with the preset value. When the pressure change is less than or equal to the preset value, control the actuator to maintain the current frequency. When the pressure change is greater than the preset value, the frequency of the actuator decreases according to the preset function until the actual pressure value reaches the target pressure value.

[0043] In this embodiment, the pressure control method adopts PID closed-loop control. In step S3, the pressure change of the actual pressure value is calculated, including:

[0044] A first difference between a first actual pressure value at a first moment in the process chamber and a target pressure value is calculated, and a second difference between a second actual pressure value at a second moment and the target pressure value is calculated, and the pressure change is the ratio of the difference between the first difference and the second difference to the maximum difference, or the pressure change is the ratio of the difference between the first difference and the second difference to the first difference.

[0045] The default function relationship is: F i+1 =K*F i , where F i is the current frequency of the actuator, F i+1 is the next frequency of the actuator, K is between 0 and 1, i = 1, 2, 3, ..., n, where F1 is the initial frequency, and the initial frequency is the maximum frequency of the actuator that does not produce resonance.

[0046] For example: the pressure change amount for each frequency conversion (the change value of the real-time difference relative to the maximum pressure difference) can be a certain ratio of the difference between the actual pressure in the measured chamber and the set target pressure, where the smaller the preset value of the pressure change used for comparison with the pressure change, the higher the frequency of the actuator frequency adjustment, which is equivalent to smooth frequency conversion. In certain occasions, there will be no overshoot when the frequency conversion step occurs. If the preset value of the pressure change is set to 5%, that is, the pressure change amount for the next frequency conversion needs to change by more than 5%, the frequency conversion degree can be set according to the actual situation, for example, the frequency of the actuator is adjusted to 10% of the previous frequency each time, specifically:

[0047] Method 1: The actuator frequency is determined by the change in the real-time difference relative to the maximum pressure difference (i.e., the absolute change in pressure). For example, Pn is the target pressure value, P1 is the initial pressure value, P2 and P3 are the actual pressure values ​​at the intermediate moments, and the pressure differences at different moments are ΔP1=Pn-P1, ΔP2=Pn-P2, ΔP3=Pn-P3.

[0048] If the absolute change in pressure is (ΔP1-ΔP2) / ΔP1>5%,

[0049] Then the initial frequency F1 is executed within the pressure change range from P1 to P2, and after P2, the execution frequency is adjusted to F2 = 10% * F1;

[0050] If the absolute change in pressure is (ΔP1-ΔP2) / ΔP1≤5%, the execution frequency after P2 is maintained at the current frequency F1.

[0051] Method 2: The frequency of the actuator can also be determined based on the change in the real-time difference in the measured pressure relative to the previous difference (i.e., the relative change in pressure).

[0052] The case where (ΔP1-ΔP2) / ΔP1>5%, or (ΔP1-ΔP2) / ΔP1≤5% is not described in detail here.

[0053] The above is just an example. 5% is just a self-set threshold. When it is less than 5%, just keep running at the current frequency. In addition, the value of the actuator frequency conversion can be customized according to actual needs. 10% is only used as an example. It will be adjusted according to the response time. The longer the maximum difference takes to reach the set pressure value, the greater the degree of frequency conversion.

[0054] It should be noted that the actuator is the motor of the pressure regulating valve, and the frequency of the actuator is the motor rotation frequency. The smaller the difference between the actual chamber pressure and the target pressure, the lower the corresponding motor speed, that is, the smaller the valve operating rate, and the slower the valve opening changes. Therefore, the smaller the difference, the more stable the valve operation.

[0055] The method of this embodiment combines the input and output negative feedback characteristics of the pressure control system to change the frequency of the pressure regulating valve actuator in advance, thereby achieving control optimization. The input and output negative feedback characteristics of the pressure control system refer to the process characteristics that the system pressure follows the pressure setting change under a fixed flow rate over a period of time and finally stabilizes at the pressure setting value. The final state of system stability is that the pressure detection is equal to the pressure setting.

[0056] According to the relationship between the actual pressure in the measured chamber and the set target pressure, the real-time state is determined, and the motor frequency is changed according to the negative feedback characteristics, thereby changing the pressure control parameters. Further, according to different pressure differences, the actuator frequency is calculated, and the opening of the pressure regulating valve is finely adjusted, thereby achieving the purpose of fast and stable pressure control.

[0057] As a preferred embodiment, the first actual pressure value and the second actual pressure value are adjacent to each other. When the pressure change is greater than zero, as the difference between the actual pressure value and the target pressure value decreases, the frequency of the actuator decreases according to a preset functional relationship. Specifically, the actual pressure value in the chamber measured in real time is compared with the preset target pressure value, and the change of the actuator frequency is adjusted according to the difference between the real-time difference between the two. Specifically, as the difference between the real-time pressure detection value and the pressure setting continues to decrease, the actuator frequency will continue to decrease. In the process from the measured actual pressure P1 to the preset target pressure Pn, ΔP1=Pn-P1, ΔP1 corresponds to an actuator frequency, and for the actual pressure P2, ΔP2=Pn-P2, corresponding to another actuator frequency, where P1 and P2 are two adjacent real-time measured pressure values, until the difference ΔP=0, each pressure difference corresponds to a frequency, which changes linearly, and the change of the actuator frequency will change the movement rate of the pressure regulating valve, specifically the movement rate of the valve driven by the motor.

[0058] This pressure control method follows the pressure set point (target pressure value) and automatically realizes step-by-step frequency conversion. That is, in the closed-loop control process, the motor frequency conversion control is performed according to the set pressure change threshold value based on the difference between the actual pressure and the set pressure. The closer to the set point, the slower the motor movement speed, thereby achieving pressure stability. The pressure control process can effectively avoid pressure overshoot and improve the process effect.

[0059] It should be noted that the control method of this embodiment is also applicable to other pressure control methods that perform closed-loop control based on differences.

[0060] In this embodiment, the pressure regulating valve may be a piston valve, a butterfly valve, a needle valve or a ball valve.

[0061] The chamber pressure control method of this embodiment is further explained below by taking a piston valve as an example.

[0062] In the process of controlling the piston valve, the piston valve position is basically adjusted by aerodynamic bearings and force balance. When a certain threshold is reached, the motor drive does not work, and the piston valve will automatically retract and adjust mechanically through the spring, which can control the pressure faster and more stably.

[0063] Taking the piston valve as an example, in the pressure control system, especially in the larger volume chamber pressure response, there is often a certain hysteresis. In order to better highlight the control effect, on the basis of frequency conversion control, buffer hysteresis compensation control (purely adjusted by mechanical elasticity) is superimposed again to achieve better control effect.

[0064] like Figure 2 As shown in the figure, the horizontal axis is time, the vertical axis is pressure, and P1 is a certain set target pressure value. In the process of the actual pressure in the detection chamber approaching the pressure setting, the actuator (motor) frequency will decrease as the difference between the actual pressure in the detection chamber and the set target pressure decreases. As shown in the figure, t1 to tn gradually increase, indicating that the frequency of the actuator is getting smaller and smaller.

[0065] The initial actuator frequency F1 is a fixed maximum value (the maximum value at which the actuator system does not resonate). This value is restricted by the pressure system. i+1 =K*F i , where F i is the current frequency of the actuator, F i+1 is the next frequency of the actuator, K is between 0 and 1, i = 1, 2, 3, ..., n, where F1 is the initial frequency. K value can be set according to actual needs, such as K = 0.1. When the frequency conversion condition is triggered, for example, according to a certain ratio of the difference between the measured actual pressure and the set target pressure, such as 5%, the pressure difference for the next frequency conversion needs to change by more than 5%. The frequency conversion degree can be adjusted according to actual conditions, for example, each time it is changed to 10% of the previous frequency, and it decreases step by step.

[0066] When the gas flow in the reaction chamber pressure control system decreases or increases in stages within a specified period of time, it will cause fluctuations in chamber pressure. As long as there is a deviation between the actual chamber pressure and the set pressure, the actuator will perform frequency conversion operation. As the difference between the actual chamber pressure and the set target pressure decreases, the frequency conversion will be gradually reduced, thereby gradually slowing down the valve movement rate of the pressure regulating valve, thereby avoiding the problem of pressure overshoot and minimizing the impact of pressure fluctuations on the process.

[0067] In summary, the chamber pressure control method of the present invention can reduce the pressure overshoot phenomenon caused by pressure change or flow change, so that the pressure control response time is faster and the pressure control is more stable. Moreover, the chamber pressure control method provided by the present invention is not limited to the semiconductor field, but can also be applied to other pressure control fields, such as the photovoltaic field.

[0068] Example 2

[0069] like Figure 3 As shown, a chamber pressure control device comprises: a pressure collector 1, a pressure controller 2 and an actuator 3;

[0070] The pressure collector 1 is used to collect the actual pressure value in the chamber in real time;

[0071] The pressure controller 2 is used to execute the chamber pressure control method of embodiment 1;

[0072] The actuator 3 is used to control the opening change of the pressure regulating valve 4 based on the frequency output by the pressure controller 2 .

[0073] In this embodiment, a parameter setting module 5 is also included, and the parameter setting module 5 is used to set the target pressure value of the chamber and the calculation function of the actuator frequency.

[0074] In this embodiment, the actuator 3 is a motor for controlling the opening of the pressure regulating valve 4, and the frequency of the actuator 3 is the rotation frequency of the motor.

[0075] In this embodiment, the pressure regulating valve 4 is a piston valve, a butterfly valve, a needle valve or a ball valve.

[0076] Preferably, the pressure regulating valve includes an elastic expansion member, which is used to enable the pressure regulating valve to adjust its opening through the elastic expansion member. For example, a piston valve with a spring. In the process of controlling the piston valve, the position of the piston valve is basically adjusted by aerodynamic bearings and force balance. When a certain threshold is reached, the motor drive does not work, and the piston valve will automatically expand and contract mechanically through the spring, which can control the pressure faster and more stably.

[0077] The chamber pressure control device of this embodiment can use the chamber pressure control method of Example 1 to perform closed-loop control when there is a deviation between the actual chamber pressure and the set pressure, and control the actuator 3 to perform frequency conversion operation. As the difference between the actual pressure in the chamber and the set target pressure decreases, the frequency conversion is gradually reduced, so that the valve movement rate of the pressure regulating valve is gradually slowed down, thereby avoiding the problem of pressure overshoot and minimizing the impact of pressure fluctuations on the process.

[0078] Example 3

[0079] like Figure 4As shown, a semiconductor process equipment includes a process chamber 6 and a chamber pressure control device of embodiment 2.

[0080] In this embodiment, one end of the process chamber 6 is connected to the air inlet pipe 8, and the other end is connected to the exhaust pipe 9. The exhaust pipe 9 is provided with a pressure collector 1, a pressure regulating valve 4 and a vacuum pumping device 7. The pressure regulating valve 4 is connected to the actuator 3. The pressure collector 1, the actuator 3 and the parameter setting module 5 are respectively connected to the pressure controller 2.

[0081] The semiconductor device of this embodiment can achieve rapid and stable control of the chamber pressure by adopting the chamber pressure control device of Example 2, avoiding the problem of pressure overshoot, thereby improving the process quality and yield rate.

[0082] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A pressure control method, applied to a process chamber of a semiconductor process equipment, wherein a pressure regulating valve is provided on a gas pipeline of the process chamber to regulate the pressure in the process chamber, characterized in that: The method comprises: Acquiring the actual pressure value in the process chamber in real time; Calculating a maximum difference between an initial actual pressure value and a target pressure value in the process chamber, and determining an initial frequency of an actuator of the corresponding pressure regulating valve based on the maximum difference; Calculate the pressure change of the actual pressure value, compare the pressure change with a preset value, and when the pressure change is less than or equal to the preset value, control the actuator to maintain the current frequency; when the pressure change is greater than the preset value, the frequency of the actuator decreases according to a preset functional relationship until the actual pressure value reaches the target pressure value.

2. The pressure control method according to claim 1, characterized in that: The calculating the pressure change of the actual pressure value comprises: A first difference between a first actual pressure value at a first moment in the process chamber and the target pressure value is calculated, and a second difference between a second actual pressure value at a second moment and the target pressure value is calculated, wherein the pressure change is a ratio of a difference between the first difference and the second difference to the maximum difference.

3. The pressure control method according to claim 1, characterized in that: The calculating the pressure change of the actual pressure value comprises: A first difference between a first actual pressure value at a first moment in the process chamber and the target pressure value is calculated, and a second difference between a second actual pressure value at a second moment and the target pressure value is calculated, wherein the pressure change is a ratio of a difference between the first difference and the second difference to the first difference.

4. The pressure control method according to claim 2, characterized in that: The first actual pressure value is adjacent to the second actual pressure value in front and back, and when the pressure change is greater than zero, as the difference between the actual pressure value and the target pressure value decreases, the frequency of the actuator decreases according to the preset functional relationship.

5. The pressure control method according to any one of claims 1 to 4, characterized in that: The preset functional relationship is: i+1 =K*F i , where F i is the current frequency of the actuator, F i+1 is the next frequency of the actuator, K is between 0 and 1, i=1, 2, 3, ..., n, wherein F1 is the initial frequency, and the initial frequency is the maximum frequency of the actuator that does not produce resonance.

6. The pressure control method according to claim 5, characterized in that: The pressure control method adopts PID closed-loop control.

7. The pressure control method according to claim 1, characterized in that: The actual pressure value is the absolute pressure value inside the chamber; Alternatively, the actual pressure value is a relative value between the internal pressure of the chamber and the atmospheric pressure.

8. A chamber pressure control device, characterized in that: include: Pressure collector, pressure controller and actuator; The pressure collector is used to collect the actual pressure value in the chamber in real time; The pressure controller is used to execute the pressure control method according to any one of claims 1 to 7; The actuator is used to control the opening change of the pressure regulating valve based on the frequency output by the pressure controller.

9. The chamber pressure control device according to claim 8, characterized in that: The actuator is a motor that controls the opening of the pressure regulating valve, and the frequency of the actuator is the rotation frequency of the motor.

10. The chamber pressure control device according to claim 8, characterized in that: The pressure regulating valve comprises an elastic telescopic member, which is used to enable the pressure regulating valve to adjust its opening degree through the elastic telescopic member.

11. A semiconductor process equipment, comprising a process chamber, and a pressure regulating valve arranged on a gas pipeline of the process chamber, characterized in that: It also includes the chamber pressure control device as described in any one of claims 8-10.

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