Vacuum pressure control system

Abstract

The present invention relates to a vacuum pressure control system. In a vacuum pressure control system capable of easily calculating the optimal valve opening of a vacuum control valve required to make the pressure value of a vacuum chamber a target value, a control device (70) includes a mapping program (702a). Before performing pressure value control, the mapping program (702a) approximates the relationship between the pressure value in the vacuum chamber (11) and the flow rate of a process gas to a linear function (LF11) to (LF20), and stores the linear function (LF11) to (LF20) in the control device (70). The control device (70) includes a valve opening calculation program. The valve opening calculation program (702b) calculates the optimal valve opening (VO) of the vacuum control valve (30) required to make the pressure value in the vacuum chamber (11) the target value (Pt) when supplying the process gas at a prescribed flow rate based on the linear functions (LF11) to (LF20) before performing pressure value control. The control device (70) adjusts the valve opening of the vacuum control valve (30) based on the optimal valve opening (VO), thereby enabling control to be performed so that the pressure value in the vacuum chamber (11) is the target value (Pt).

Description

Technical Field

[0001] The present disclosure relates to a vacuum pressure control system, which includes, in a serially connected manner: a gas supply source; a vacuum chamber that receives gas from the gas supply source; a vacuum control valve that is used to adjust the pressure value of the vacuum chamber; and a vacuum pump that is used to decompress the vacuum chamber, and the vacuum pressure control system includes: a pressure sensor that detects the pressure value of the vacuum chamber; and a control device that controls the vacuum control valve, wherein, when gas is supplied from the gas supply source to the vacuum chamber at a prescribed flow rate, the control device adjusts the valve opening of the vacuum control valve based on the pressure value detected by the pressure sensor, thereby performing pressure value control so that the pressure value of the vacuum chamber is a target value. Background Art

[0002] Conventionally, vacuum pressure control systems, such as those disclosed in Japanese Patent Application Laid-Open No. 10-252942, have been used to adjust and maintain the pressure within a vacuum chamber at a target pressure. Such vacuum pressure control systems are used, for example, when forming films on wafers made of semiconductor materials. By adjusting the valve opening of a vacuum control valve, the pressure in the vacuum chamber, where gas (process gas) is supplied at the required flow rate for film formation, is maintained at the target pressure, thereby allowing film formation to be performed on wafers placed within the vacuum chamber. Summary of the Invention

[0003] However, the above-mentioned prior art has the following problems. As mentioned above, in order to keep the pressure value of the vacuum chamber at the target value, the valve opening of the vacuum control valve needs to be adjusted to the optimal state. However, if the pressure value control is not actually attempted, it is impossible to determine what the optimal valve opening of the vacuum control valve is. Therefore, as a preliminary preparation before the actual film forming process, it is necessary to adjust the valve opening of the vacuum control valve while experimentally supplying the process gas at the flow rate required for film forming to the vacuum chamber, and to find the optimal valve opening of the vacuum control valve that can make the pressure value of the vacuum chamber reach the target value. For example, Figure 10 As shown in FIG. 1 , the valve opening is gradually reduced to find the optimum valve opening VO that becomes the target value Pt.

[0004] Then, based on the found optimal valve opening VO, the actual pressure value of the vacuum chamber is confirmed to be the target value Pt. Figure 11 As shown, the valve opening of the vacuum control valve is set to the optimal valve opening VO, and the pressure waveform of the vacuum chamber is checked to see whether the pressure value is actually the target value Pt. After this check is completed, the film forming process is carried out.

[0005] Furthermore, film formation is typically performed under multiple conditions within a single step. These multiple conditions may involve using multiple process gases, or using the same process gas multiple times with different flow rates or target pressures. Therefore, it is necessary to search for the optimal valve opening and verify that the vacuum chamber pressure is actually at the target value under each of these multiple conditions. Consequently, increasing the number of process gases used increases the time required for preparatory preparations prior to film formation, potentially negatively impacting semiconductor manufacturing efficiency.

[0006] Problems to be solved by the invention

[0007] The present disclosure aims to solve the above-mentioned problems and has an object to provide a vacuum pressure control system that can easily calculate the optimal valve opening of a vacuum control valve required to achieve a target pressure value in a vacuum chamber.

[0008] Solutions to Problems

[0009] In order to solve the above-mentioned problems, the vacuum pressure control system of the present disclosure has the following configuration.

[0010] A vacuum pressure control system, which includes, in a series connection, a gas supply source; a vacuum chamber that receives gas from the gas supply source; a vacuum control valve for adjusting the pressure value of the vacuum chamber; and a vacuum pump for decompressing the vacuum chamber, and the vacuum pressure control system includes: a pressure sensor for detecting the pressure value of the vacuum chamber; and a control device for controlling the vacuum control valve. The vacuum pressure control system is characterized in that, when gas is supplied from the gas supply source to the vacuum chamber at a prescribed flow rate, the control device adjusts the valve opening of the vacuum control valve based on the pressure value detected by the pressure sensor, thereby performing pressure control so that the vacuum chamber The pressure value of the empty chamber is a target value. In this vacuum pressure control system, the control device includes a mapping program. Before performing pressure value control, the mapping program approximates the relationship between the pressure value in the vacuum chamber and the flow rate of the gas to a linear function, and stores the linear function in the control device. The control device includes a valve opening calculation program. Before performing pressure value control, when a prescribed flow rate of gas is supplied based on the linear function, the valve opening calculation program calculates the optimal valve opening of the vacuum control valve required to make the pressure value in the vacuum chamber reach the target value. The control device adjusts the valve opening of the vacuum control valve based on the optimal valve opening, thereby enabling control to be performed so that the pressure value in the vacuum chamber reaches the target value.

[0011] According to the vacuum pressure control system described above, the optimal valve opening of the vacuum control valve required to set the pressure value of the vacuum chamber to the target value can be easily calculated.

[0012] The control device includes a mapping program and a valve opening calculation program. The mapping program approximates the relationship between the pressure value within the vacuum chamber and the gas flow rate to a linear function, and the linear function is stored in the control device. Furthermore, when a predetermined flow rate of gas is supplied based on the stored linear function, the valve opening calculation program calculates the optimal valve opening of the vacuum control valve required to achieve a target pressure value within the vacuum chamber. The valve opening of the vacuum control valve can be adjusted based on the calculated optimal valve opening.

[0013] By approximating the relationship between the pressure value within the vacuum chamber and the gas flow rate to a linear function, the optimal valve opening can be calculated using this linear function. Therefore, even when film formation is performed under multiple conditions, such as using multiple gases, there is no need to experimentally supply the vacuum chamber with the gas flow rate required for film formation while adjusting the valve opening of the vacuum control valve according to each of these conditions to find the optimal valve opening that will achieve the target pressure value in the vacuum chamber. This reduces the risk of wasting time on preparatory preparations before the film formation process, which could negatively impact semiconductor manufacturing efficiency.

[0014] Note that the predetermined flow rate refers to a flow rate when the pressure of the vacuum chamber is actually controlled, for example, a flow rate of a gas required for film formation on a wafer.

[0015] According to the vacuum pressure control system of the present disclosure, the optimal valve opening of the vacuum control valve required to set the pressure value of the vacuum chamber to the target value can be easily calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an explanatory diagram showing the configuration of a vacuum pressure control system according to this embodiment.

[0017] Figure 2 This is a cross-sectional view of a vacuum control valve used in the vacuum pressure control system according to the present embodiment.

[0018] Figure 3 1 is a block diagram showing the configuration of a control device used in the vacuum pressure control system according to the present embodiment.

[0019] Figure 4 This is a table illustrating conditions for performing a film formation process on a wafer.

[0020] Figure 5 This is a diagram showing the flow of the mapping program according to this embodiment.

[0021] Figure 6 1 is a diagram showing the flow of the valve opening degree calculation program according to the present embodiment.

[0022] Figure 7This is a graph showing the relationship between the pressure value in the vacuum chamber and the flow rate of the process gas when the valve opening of the vacuum control valve is kept constant.

[0023] Figure 8 This is a diagram showing a map created by a mapping program.

[0024] Figure 9 1 is a diagram illustrating a method for calculating the optimum valve opening by the valve opening calculation program.

[0025] Figure 10 It is a graph explaining the operation of finding the optimal valve opening in the prior art.

[0026] Figure 11 This is a highlighted diagram when checking the pressure waveform with the vacuum control valve at the optimal valve opening. DETAILED DESCRIPTION

[0027] Refer to the attached Figure 1 Next, embodiments of the vacuum pressure control system according to the present disclosure will be described in detail.

[0028] Figure 1 1 is a diagram illustrating the configuration of a vacuum pressure control system 1. The vacuum pressure control system 1 is a semiconductor manufacturing apparatus that uses, for example, atomic layer deposition (ALD) and is used to perform surface treatment on a wafer 150.

[0029] like Figure 1 As shown, the vacuum pressure control system 1 is connected in series, starting from the upstream side, to: a gas supply source 16, which is a supply source of process gas (an example of gas) used for surface treatment of wafers 150; a mass flow controller 20; a vacuum chamber 11, which is a vacuum container; a vacuum control valve 30; and a vacuum pump 15. Furthermore, an N2 supply source 17, which is a supply source of nitrogen gas (N2) used for purging process gases, is connected in series with the gas supply source 16 on the upstream side of the mass flow controller 20.

[0030] Furthermore, the vacuum pressure control system 1 includes a pressure sensor 12 for detecting the pressure value of the vacuum chamber 11 via a shutoff valve 13 between the vacuum chamber 11 and the vacuum control valve 30 , and a control device 70 electrically connecting the pressure sensor 12 and the vacuum control valve 30 .

[0031] A process gas supplied from a gas supply source 16 or a purge gas supplied from an N2 supply source 17 is supplied at a predetermined flow rate from a gas supply port 11a to the vacuum chamber 11. The predetermined flow rate of the process gas refers to the flow rate during actual pressure control of the vacuum chamber 11 and is the flow rate of the process gas required for film formation on the wafer 150.

[0032] Furthermore, the first port 41a of the vacuum control valve 30 is connected to the gas exhaust port 11b of the vacuum chamber 11, and the vacuum pump 15 is connected to the second port 41b of the vacuum control valve 30. Therefore, the process gas or the purge gas supplied to the vacuum chamber 11 can be sucked by the vacuum pump 15. At this time, the control device 70 obtains the pressure value in the vacuum chamber 11 from the pressure sensor 12 while adjusting the valve opening of the vacuum control valve 30, thereby performing pressure control so that the pressure value in the vacuum chamber 11 becomes the target value Pt. In order to make the pressure value of the vacuum chamber 11 become the target value Pt, the required valve opening of the vacuum control valve 30 is set to the optimal valve opening VO (refer to Figure 10 、 11 ).

[0033] Such a vacuum pressure control system 1 performs film formation under multiple conditions in one process. Multiple conditions refer to, for example, Figure 4 Conditions 1 to 5 of the table shown. Figure 4 The "gas type" shown here refers to the type of process gas used for film formation. Figure 4 The specific types of gases are not shown in the figure, and are simply expressed as A gas, B gas, C gas, etc. "Gas flow rate" refers to the flow rate (specified flow rate) of the process gas required for film formation. The gas flow rate is adjusted by the mass flow controller 20, Figure 4 The flow rate shown is supplied to the vacuum chamber 11. "Target value" refers to the target pressure value Pt within the vacuum chamber 11. The valve opening of the vacuum control valve 30 is adjusted by the control device 70 to achieve the target value Pt. "Chamber temperature" refers to the temperature within the vacuum chamber 11. Purge with N2 gas is performed between each condition.

[0034] Figure 2 1 is a cross-sectional view of the vacuum control valve 30, showing a state in which the vacuum control valve 30 is fully opened. The vacuum control valve 30 includes a pneumatic cylinder 31 and a bellows-type poppet valve 32, which are assembled one above the other in the figure.

[0035] The pneumatic cylinder 31 includes a cylinder body 33 having a hollow cylinder chamber, and a piston 34 slidably mounted in a direction parallel to the direction in which the pneumatic cylinder 31 and the bellows-type poppet valve 32 are stacked (vertical direction in the figure). The piston 34 is biased downward by a return spring 35. A sliding rod 36 extending upward is provided at the upper end of the piston 34.

[0036] A potentiometer 37, serving as an opening sensor, is mounted on the outside of the cylinder body 33. The potentiometer 37 incorporates a variable resistor (not shown) connected to the slide rod 36. As the slide rod 36 and the piston 34 move vertically together, the value of the variable resistor changes. The potentiometer 37 outputs this resistance value to the control device 70 as a value correlated with the vertical position of the piston 34.

[0037] A bellows diaphragm 38 is provided on the lower surface of the piston 34. The inner peripheral end of the bellows diaphragm 38 is fixed to the piston 34, and the outer peripheral end of the bellows diaphragm 38 is fixed to the inner wall of the cylinder chamber. The bellows diaphragm 38 is extremely thin and is structurally formed by coating a strong polyester or polyester cloth with rubber. The bellows diaphragm 38 has a long deformation stroke and a deep return portion. The bellows diaphragm 38 is a diaphragm formed in a cylindrical shape, and its effective pressure-bearing area remains constant during deformation. The cylinder chamber includes an atmospheric chamber 33a and a pressurized chamber 33b, which are divided into an upper and lower part by the piston 34 and the bellows diaphragm 38. The upper atmospheric chamber 33a accommodates the return spring 35 and is introduced into the atmosphere from an atmospheric port (not shown). The lower pressurized chamber 33b is introduced into compressed air from an air supply source (not shown) through a pressurized port (not shown).

[0038] A piston rod 39, which is inserted into the interior of the bellows-type poppet valve 32, is fixed to the center of the piston 34. The bellows-type poppet valve 32 includes a piston rod 39, a valve body 40, and a housing 41 that houses the piston rod 39 and the valve body 40. The valve body 40 is fixed to the end of the piston rod 39 on the side inserted into the interior of the bellows-type poppet valve 32. The housing 41 is cylindrical and has the first port 41a and the second port 41b described above. A bellows 42 is provided on the upper surface of the valve body 40. The bellows 42 is arranged so as to enclose the piston rod 39.

[0039] An O-ring 43 is attached to the lower surface of the valve body 40, and a valve seat 45 is provided on the upper end side of the first port 41a of the housing 41, with which the valve body 40 contacts and separates. When the valve body 40 moves toward the valve seat 45 and contacts the valve seat 45, and the O-ring 43 is pressed against the valve body 40 and the valve seat 45, that is, when the vacuum control valve 30 is fully closed, the flow of the process gas is shut off.

[0040] Furthermore, the piston 34 moves up and down, thereby causing the valve body 40 to move up and down via the piston rod 39. This changes the opening of the vacuum control valve 30. The potentiometer 37 then measures the vertical position of the piston 34, and consequently the vertical position of the valve body 40, i.e., the valve opening of the vacuum control valve 30, and outputs this measured value to the control device 70.

[0041] like Figure 3As shown, the control device 70 includes a CPU 701, a ROM 702, a RAM 703, and a storage unit 704. The ROM 702 stores a mapping program 702a for creating a map used to calculate the optimal valve opening VO, and a valve opening calculation program 702b for calculating the optimal valve opening VO of the vacuum control valve 30 based on the created map. The valve opening calculation program 702b then controls the vacuum control valve 30 to the optimal valve opening VO. The CPU 701 controls the operation of the vacuum control valve 30 according to the mapping program 702a or the valve opening calculation program 702b, temporarily storing data in the RAM 703. Furthermore, the storage unit 704 stores the map created by the mapping program 702a.

[0042] <Function of Vacuum Pressure Control System>

[0043] The operation of the vacuum pressure control system 1 having the above configuration is described using the vacuum pressure control system 1. For example, assuming that Figure 4 Conditions 1 to 5 in the table shown are used to perform film formation processing on the wafer 150 .

[0044] When performing actual pressure control for film formation processing, the vacuum pressure control system 1 calculates in advance the optimal valve opening VO of the vacuum control valve 30 under each of conditions 1 to 5 using the mapping program 702 a and the valve opening calculation program 702 b .

[0045] First, the control device 70 creates a map using the mapping program 702 a . The map is used to calculate the optimal valve opening VO.

[0046] When creating a map, the operator first sets the flow rate Ft (refer to the flow rate Ft) used for mapping to be used. Figure 8 ) The process gas is supplied to the vacuum chamber 11. The measurement flow rate Ft is a flow rate predetermined by the mapping program 702a and is set to a value close to the actual supply amount of the process gas, such as 10 L / min.

[0047] In the state where the measurement flow rate Ft is supplied, the mapping program 702a is started. The control device 70 adjusts the valve opening of the vacuum control valve 30 to a predetermined valve opening ( Figure 5 The valve opening is adjusted based on the resistance value output from the potentiometer 37.

[0048] Here, the prescribed valve opening is a valve opening that is pre-set for mapping, and a plurality of valve openings are set. For example, if the maximum valve opening is 100%, then 7%, 11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, 114% are set (see Figure 8 Here, the valve opening is first adjusted to 7%.

[0049] When the valve opening is adjusted to a predetermined value, the control device 70 then acquires the pressure measurement value Pm11 of the vacuum chamber 11 in a state where the process gas is supplied at the measurement flow rate Ft from the pressure sensor 12 and stores it ( S12 ).

[0050] Then, the process is repeated at all remaining specified valve openings (11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, 114%) until the pressure measurement values Pm12 to Pm20 of the vacuum chamber 11 are obtained (S13: No).

[0051] When the pressure measurement values of the vacuum chamber 11 are obtained at all valve openings (S13: YES), the control device 70 creates a map (S14). Specifically, the pressure measurement values Pm11 to Pm20 are plotted at each of a plurality of predetermined valve openings (7%, 11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, and 114%), and linear functions LF11 to LF20 are calculated so that the intercepts of the plotted pressure measurement values Pm11 to Pm20 are zero.

[0052] The linear functions LF11 to LF20 are functions that approximate the relationship between the pressure value in the vacuum chamber 11 and the flow rate of the process gas. To explain why this approximation is possible, for example, when the valve opening of the vacuum control valve 30 is fixed at 7%, the flow rate of the process gas is increased. Figure 7 As shown in FIG. 1 , the pressure value in the vacuum chamber 11 increases with the increase in the flow rate of the process gas. This shows that the vacuum control valve 30 is opened at the same valve opening (e.g., Figure 7 As shown in the figure, the same applies to valve openings of 11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, and 114%. As long as the valve opening of vacuum control valve 30 is fixed, the pressure in vacuum chamber 11 increases with increasing process gas flow, and decreases with decreasing process gas flow. In other words, the pressure in vacuum chamber 11 is proportional to the process gas flow. Therefore, the relationship between the pressure in vacuum chamber 11 and the process gas flow can be approximated by a linear function LF11-LF20 with a zero intercept.

[0053] When the mapping is completed, the control device 70 stores the generated mapping in the storage unit 704 (S15), and the mapping program 702a ends.

[0054] Next, the valve opening calculation program 702b is described. Figure 4 The operation of calculating the optimum valve opening VO of the vacuum control valve 30 is performed for each of the conditions 1 to 5 shown.

[0055] First, the optimal valve opening VO with respect to condition 1 is calculated.

[0056] When calculating the optimal valve opening VO, the operator first sets the state as follows: the process gas is supplied to the vacuum chamber 11 at a specified flow rate. The specified flow rate refers to the gas flow rate determined under conditions 1 to 5. If condition 1 is used, then Figure 4 As shown, 0.5 L / min becomes the predetermined flow rate.

[0057] After the process gas is supplied at a predetermined flow rate, the operator activates the valve opening calculation program 702 b .

[0058] The control device 70 adjusts the valve opening of the vacuum control valve 30 to any one of a plurality of predetermined valve openings (7%, 11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, 114%). Figure 6 , S21). This is: before the valve opening calculation program 702b is executed, the operator can select any valve opening from a plurality of predetermined valve openings. Here, for example, assuming that a valve opening of 11% is selected, the control device 70 adjusts the valve opening of the vacuum control valve 30 to 11%.

[0059] Then, the control device 70 obtains the second pressure measurement value Pm21 through the pressure sensor 12 ( S22 ).

[0060] When the second pressure measurement value Pm21 is obtained, the control device 70 calculates the estimated flow rate Fe based on the map (S23). For example, if the vacuum control valve 30 is set to an opening of 11%, the estimated flow rate Fe can be calculated by substituting Pm21 into LF12.

[0061] The estimated flow rate Fe refers to the flow rate of the process gas supplied to the vacuum chamber 11 and is synonymous with the specified flow rate (0.5 L / min if Condition 1 is met). The reason for calculating the estimated flow rate Fe, which is synonymous with the specified flow rate, is that the vacuum control valve 30 cannot obtain flow rate information from the mass flow controller 20. Furthermore, enabling the vacuum control valve 30 to obtain flow rate information from the mass flow controller 20 requires a new circuit configuration, which is costly. However, by having the control device 70 calculate the estimated flow rate Fe as described above, it is possible to obtain flow rate information using the existing circuit configuration, thereby reducing costs.

[0062] Next, the control device 70 determines the target value Pt of the pressure value of the vacuum chamber 11 (S24). If condition 1 is satisfied, the target value Pt is 133 Pa.

[0063] Then, based on the target value Pt and the estimated flow rate Fe, the optimal valve opening VO is calculated (S25). Since the relationship between the pressure value and the flow rate can be approximated by a linear function, as shown in FIG. Figure 9 As shown, the target value Pt can be expressed as a linear function LF21 of the estimated flow rate Fe with an intercept of zero. By calculating the slope of this linear function LF21, the optimal valve opening VO of the vacuum control valve 30 suitable for achieving the target value Pt at the estimated flow rate Fe, i.e., a predetermined flow rate, can be calculated based on this slope.

[0064] Then, the control device 70 confirms that the actual pressure value of the vacuum chamber 11 is the target value Pt based on the calculated optimal valve opening VO (S26). Figure 11 As shown, the valve opening of the vacuum control valve 30 is set to the optimal valve opening VO, and the pressure value of the vacuum chamber 11 is confirmed to be the target value Pt. Figure 10 However, since the optimal valve opening VO can be calculated as described above, the operation of finding the optimal valve opening VO is not necessary.

[0065] If the pressure waveform confirms that the target value Pt is obtained (S26: YES), the control device 70 stores the obtained optimal valve opening VO in the storage unit 704 (S27). If the pressure waveform confirmation result does not confirm that the target value Pt is obtained, the control device 70 issues an error notification (S29), and the valve opening calculation program 702b ends.

[0066] As described above, the control device 70 repeats steps S21 to S25 (S28: No) under all conditions 1 to 5 to determine the optimal valve opening VO for each condition. When steps S21 to S27 are completed (S28: Yes) under all conditions 1 to 5, the valve opening calculation program 702b ends.

[0067] Then, during the actual film formation process, the control device 70 reads the optimal valve opening VO from the storage unit 704 for each condition, such that when film formation is performed under condition 1, the optimal valve opening VO is referred to as condition 1, and when film formation is performed under condition 2, the optimal valve opening VO is referred to as condition 2. The control device 70 adjusts the valve opening of the vacuum control valve 30 to the optimal valve opening VO. This allows control to be performed so that the pressure value within the vacuum chamber 11 reaches the target value Pt.

[0068] Furthermore, if a plurality of semiconductor manufacturing apparatuses of the same type are installed in a factory, by using any of the plurality of semiconductor manufacturing apparatuses to create a map using the mapping program 702a, the optimal valve opening V0 of the vacuum control valve 30 required to achieve the target pressure value Pt in the vacuum chamber 11 can be calculated using the same map in the semiconductor manufacturing apparatuses of the same type. This reduces the possibility that time spent on preliminary preparations before the film formation process may adversely affect semiconductor manufacturing efficiency.

[0069] As described above, according to the vacuum pressure control system 1 of the present embodiment, (1) is a vacuum pressure control system 1, which includes, in a serially connected manner: a gas supply source 16; a vacuum chamber 11, which receives a supply of process gas from the gas supply source 16; a vacuum control valve 30, which is used to adjust the pressure value of the vacuum chamber 11; and a vacuum pump 15, which is used to decompress the vacuum chamber 11, and the vacuum pressure control system 1 includes: a pressure sensor 12, which detects the pressure value of the vacuum chamber 11; and a control device 70, which controls the vacuum control valve 30. The vacuum pressure control system 1 is characterized in that when the process gas is supplied from the gas supply source 16 to the vacuum chamber 11 at a prescribed flow rate, the control device 70 adjusts the valve opening of the vacuum control valve 30 based on the pressure value detected by the pressure sensor 12, thereby performing pressure value control so that the vacuum chamber 11 The pressure value is a target value Pt. In this vacuum pressure control system, the control device 70 includes a mapping program 702a. Before performing pressure value control, the mapping program 702a makes the relationship between the pressure value in the vacuum chamber 11 and the flow rate of the process gas approximate to a linear function LF11~LF20, and stores the linear function LF11~LF20 in the control device 70. The control device 70 includes a valve opening calculation program 702b. Before performing pressure value control, when a specified flow rate of process gas is supplied based on the linear function LF11~LF20, the valve opening calculation program 702b calculates the optimal valve opening VO of the vacuum control valve 30 required to make the pressure value in the vacuum chamber 11 the target value Pt. The control device 70 adjusts the valve opening of the vacuum control valve 30 based on the optimal valve opening VO, thereby being able to control so that the pressure value in the vacuum chamber 11 is the target value Pt.

[0070] According to the vacuum pressure control system 1 described in (1), the optimum valve opening VO of the vacuum control valve 30 required to make the pressure value of the vacuum chamber 11 the target value Pt can be easily calculated.

[0071] The control device 70 includes a mapping program 702a and a valve opening calculation program 702b. The mapping program 702a approximates the relationship between the pressure value within the vacuum chamber 11 and the flow rate of the process gas to linear functions LF11 to LF20, and stores the linear functions LF11 to LF20 in the control device 70. Furthermore, when a predetermined flow rate of process gas is supplied based on the stored linear functions LF11 to LF20, the valve opening calculation program 702b calculates the optimal valve opening VO of the vacuum control valve 30 required to bring the pressure value within the vacuum chamber 11 to the target value Pt. The valve opening of the vacuum control valve 30 can be adjusted based on the calculated optimal valve opening VO.

[0072] The relationship between the pressure value within the vacuum chamber 11 and the flow rate of the process gas is approximated by linear functions LF11 to LF20. The optimal valve opening VO can be calculated using these linear functions LF11 to LF20. Therefore, even when film formation is performed under multiple conditions, such as using multiple process gases, there is no need to experimentally supply process gas at the flow rate required for film formation to the vacuum chamber 11 while adjusting the valve opening of the vacuum control valve 30 according to each of the multiple conditions (conditions 1 to 5). This eliminates the need to find the optimal valve opening VO that will bring the pressure value in the vacuum chamber 11 to the target value Pt. This reduces the possibility that time spent on preliminary preparations before the film formation process, which could adversely affect semiconductor manufacturing efficiency, will be reduced.

[0073] Note that the predetermined flow rate refers to a flow rate when the pressure of the vacuum chamber 11 is actually controlled, for example, a flow rate of a process gas required for film formation on the wafer 150 .

[0074] (2) The vacuum pressure control system 1 according to (1) is characterized in that before pressure value control is performed, in a state where process gas is supplied from the gas supply source 16 to the vacuum chamber 11 at a measuring flow rate determined by the mapping program 702a at a specified valve opening of the vacuum control valve 30, the mapping program 702a obtains the pressure measurement values Pm11~Pm20 of the vacuum chamber 11 at the specified valve opening from the pressure sensor 12, and based on the measuring flow rate and the pressure measurement values Pm11~Pm20, obtains the linear functions LF11~LF20 that make the intercept zero and pass through the pressure measurement values Pm11~Pm20 at the specified valve opening.

[0075] According to the vacuum pressure control system 1 described in (2), the optimum valve opening VO of the vacuum control valve 30 required to make the pressure value of the vacuum chamber 11 the target value Pt can be easily calculated.

[0076] As long as the valve opening of the vacuum control valve 30 is fixed, the pressure in the vacuum chamber 11 increases as the process gas flow rate increases, and the pressure in the vacuum chamber 11 decreases as the process gas flow rate decreases. In other words, the pressure in the vacuum chamber 11 is proportional to the process gas flow rate. Therefore, the relationship between the pressure in the vacuum chamber 11 and the process gas flow rate can be approximated by a linear function LF11 to LF20 (the slope depends on the specified valve opening) with a zero intercept. Using this linear function LF11 to LF20, the optimal valve opening VO of the vacuum control valve 30 required to achieve the target pressure value Pt in the vacuum chamber 11 can be easily calculated.

[0077] Furthermore, if multiple semiconductor manufacturing apparatuses of the same type are installed within a factory, the linear functions LF11 to LF20 described above can be calculated using any of the multiple semiconductor manufacturing apparatuses. Using the same linear functions LF11 to LF20 in the same type of semiconductor manufacturing apparatuses, the optimal valve opening VO of the vacuum control valve 30 required to achieve the target pressure value Pt in the vacuum chamber 11 can be calculated. This reduces the possibility of adversely affecting semiconductor manufacturing efficiency due to the time wasted in the preliminary preparations before the film formation process.

[0078] (3) The vacuum pressure control system 1 shown in (1) or (2) is characterized in that, before pressure value control is performed and a process gas of a specified flow rate is supplied to the vacuum chamber 11 at a specified valve opening, the valve opening calculation program 702b uses the pressure sensor 12 to obtain a second pressure measurement value Pm21 in the vacuum chamber 11, substitutes the second pressure measurement value Pm21 into the linear functions LF11~LF20, thereby calculating the estimated flow rate Fe of the process gas, takes the target value Pt as the linear function LF21 of the estimated flow rate Fe so that the intercept is zero, obtains the slope of the linear function LF21, and obtains the optimal valve opening VO at the specified flow rate based on the slope.

[0079] According to the vacuum pressure control system 1 described in (3), the optimal valve opening VO of the vacuum control valve 30 required to make the pressure value of the vacuum chamber 11 the target value Pt can be easily calculated.

[0080] The slope of the linear function LF11~LF20 is determined by the specified valve opening. The second pressure measurement value Pm21 in the state where the process gas at a specified flow rate is supplied to the vacuum chamber 11 is substituted into the linear function LF11~LF20. Therefore, the estimated flow rate Fe obtained is synonymous with the specified flow rate.

[0081] It is known that the relationship between the pressure value in the vacuum chamber 11 and the flow rate of the process gas can be approximated by a linear function with a zero intercept. Therefore, the target value Pt can be said to be a function of the estimated flow rate Fe (linear function LF21) which is synonymous with the specified flow rate. The slope of this linear function LF21 can be calculated. This slope represents the optimal valve opening VO for obtaining the target value Pt at the specified flow rate.

[0082] By calculating the estimated flow rate Fe, which is equivalent to the specified flow rate, the control device 70 itself can calculate the optimal valve opening VO without external input of the specified flow rate information. Therefore, there is no need to configure new equipment to input the specified flow rate information into the vacuum control valve 30 or the control device 70, and the optimal valve opening VO of the vacuum control valve 30 can be calculated using existing equipment.

[0083] The above-described embodiments are merely examples and do not limit the present disclosure in any way. Therefore, the present disclosure can be variously improved and modified without departing from the spirit and scope of the present disclosure.

[0084] For example, ten valve openings are listed as the prescribed valve openings when mapping is created using the mapping program 702a: 7%, 11%, 14%, 18%, 21%, 25%, 29%, 54%, 100%, and 114%. However, the valve openings are not limited to these and any valve openings may be used. Furthermore, the valve openings are not limited to ten.

[0085] Description of Reference Signs

[0086] 1 Vacuum pressure control system

[0087] 11 Vacuum Chamber

[0088] 12 Pressure Sensor

[0089] 15 Vacuum pump

[0090] 16 Gas supply source

[0091] 30 Vacuum control valve

[0092] 70 Control device.

Claims

1. A vacuum pressure control system comprising: Gas supply source; a vacuum chamber receiving a supply of gas from the gas supply source; A vacuum control valve, used to adjust the pressure value of the vacuum chamber; and a vacuum pump for decompressing the vacuum chamber, and the vacuum pressure control system includes: a pressure sensor for detecting a pressure value in the vacuum chamber; and a control device for controlling the vacuum control valve. The vacuum pressure control system is characterized in that, when gas is supplied from the gas supply source to the vacuum chamber at a prescribed flow rate, the control device adjusts the valve opening of the vacuum control valve based on the pressure value detected by the pressure sensor, thereby performing pressure control so that the pressure value in the vacuum chamber is a target value. In this vacuum pressure control system, The control device includes a mapping program. Before performing the pressure value control, the mapping program approximates the relationship between the pressure value in the vacuum chamber and the flow rate of the gas to a linear function, and stores the linear function in the control device. The control device includes a valve opening calculation program that calculates an optimal valve opening of the vacuum control valve required to bring the pressure value within the vacuum chamber to the target value when the gas is supplied at the predetermined flow rate based on the linear function before performing the pressure control. The control device adjusts the valve opening of the vacuum control valve based on the optimal valve opening, thereby enabling control so that the pressure value in the vacuum chamber reaches the target value. Before the pressure value control is performed, the valve opening calculation program obtains a second pressure measurement value in the vacuum chamber using the pressure sensor in a state where the gas at the specified flow rate is supplied to the vacuum chamber at the specified valve opening. The valve opening calculation program substitutes the second pressure measurement value into the linear function to thereby calculate the estimated flow rate of the gas. The valve opening calculation program defines the target value as a linear function of the estimated flow rate with an intercept of zero, obtains a slope of the linear function, and obtains the optimal valve opening at the predetermined flow rate based on the slope.

2. The vacuum pressure control system according to claim 1, characterized in that: Before performing the pressure value control, the mapping program acquires, from the pressure sensor, a pressure measurement value of the vacuum chamber at a predetermined valve opening of the vacuum control valve, while the gas is supplied from the gas supply source to the vacuum chamber at a measurement flow rate determined by the mapping program. The mapping program obtains the linear function that makes the intercept zero at the predetermined valve opening and passes through the pressure measurement value based on the measurement flow rate and the pressure measurement value.

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