CN103811300A - Vaccum apparatus, pressure controlling method thereof and etching method - Google Patents

Abstract

The technical problem to be solved by the present invention is to suppress sudden pressure changes in a vacuum device that mainly uses an APC valve to regulate the pressure in a processing container. According to the steps of step S1 to step S5, it is possible to suppress pressure change in the processing container (1). In step S1, the EC (81) obtains the opening degree of the APC valve (55), and in step S2, the opening degree determination part (123) of the EC (81) determines the opening degree of the APC valve (55) obtained in step S1. Whether the degree has exceeded the first threshold. When it is determined in step S2 that the opening degree exceeds the first threshold (Yes), in step S3 the excess counter ( 124 ) counts up the excess count value once. Next, in step S4, it is determined whether the cumulative value of the excess count value counted by the excess counter (124) has exceeded the second threshold value, and if it is determined that the excess count value exceeds the second threshold value (Yes), the flow control The unit (121a) sends a control signal to a mass flow controller (MFC) (43) via the MC (83) so as to decrease the flow rate of the processing gas by a predetermined amount.

Description

Vacuum device, its pressure control method and etching method

technical field

The present invention relates to a vacuum device for performing plasma treatment or the like on an object to be processed, its pressure control method, and an etching method.

Background technique

In the FPD (Flat Panel Display) manufacturing process, various plasma treatments such as plasma etching, plasma ashing, and plasma film formation are performed on the FPD substrate. As an apparatus for performing such plasma processing, for example, a parallel plate type plasma processing apparatus, an inductively coupled plasma (ICP: Inductively Coupled Plasma) processing apparatus, etc. are known. These plasma processing apparatuses are configured as vacuum apparatuses that depressurize the inside of a processing container to a vacuum state and perform processing.

As a prior art related to the pressure control of a vacuum device, Patent Document 1 proposes to use a mass flow controller (MFC) to supply pressure into a processing container while keeping the conductance (conduction) of the exhaust path constant. The method of changing the flow rate of the gas. In addition, Patent Document 2 proposes a method of adjusting the pressure inside the processing container by flowing a constant flow rate of ballast gas upstream of a throttle valve in the exhaust path.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2002-57089 (FIG. 3 etc.)

Patent Document 2: Japanese Patent Application Laid-Open No. 10-11152 (FIG. 1 etc.)

Contents of the invention

The technical problem to be solved by the invention

In recent years, in order to process large substrates for FPDs, processing containers have also increased in size. Therefore, one vacuum pump for depressurizing and evacuating the inside of the processing container is not enough, and a plurality of them is required. On the upstream side of the exhaust direction of these vacuum pumps, an Adaptive Pressure Control (Adaptive Pressure Control) valve (hereinafter referred to as "APC valve") is installed to automatically adjust the flow conductance of the exhaust path, thereby adjusting the pressure in the processing container. For example, in a plasma etching apparatus, the following method is adopted: during processing, while using a mass flow controller to supply a certain flow rate of processing gas in the processing container, the APC valve is used to adjust the flow conductance of the exhaust path, and the control is as follows: Expect to handle stress.

However, in a process in which the processing gas is consumed during plasma etching to reduce the gas volume, the gas volume rapidly increases immediately after the etching is completed. This phenomenon is caused by the fact that the processing gas consumed by the reaction with the etching target film while the etching target film is present is not consumed when the etching progresses and the etching target film disappears. When such a sudden volume change occurs, the opening degree of the APC valve becomes fully open and remains constant, and the pressure control by the APC valve cannot keep up. As a result, there arises a problem that the pressure in the processing chamber rises rapidly at the same time as the etching is completed. The rapid pressure rise after the etching may cause excess radicals to cause damage such as distortion (collapse) of the shape of the pattern formed on the surface of the substrate. In order to cope with the pressure change as described above, it is necessary to increase the number of installed vacuum pumps and APC valves to secure a sufficient exhaust capacity, which causes an increase in the number of parts and an increase in cost.

Therefore, an object of the present invention is to suppress sudden pressure changes in a vacuum apparatus that mainly uses an APC valve to regulate the pressure in a processing container.

Technical solutions for technical problems

The vacuum apparatus of the present invention includes: a processing container that accommodates an object to be processed and can keep the inside vacuum; a gas supply source that supplies a processing gas to the processing container through a gas supply path; A flow regulating device for adjusting the supply flow rate of gas; a pressure detection device for detecting the pressure in the processing container; an exhaust device connected to the processing container via an exhaust path; The pressure value detected by the device automatically adjusts the APC valve opening; the opening monitoring part monitors the opening degree of the above-mentioned APC valve; A flow control section for regulation.

In the vacuum apparatus according to the present invention, the flow control unit may control the flow adjustment device by comparing the opening degree of the APC valve with a predetermined threshold so as to decrease the supply flow rate of the processing gas.

The vacuum device of the present invention may further include a counting unit that counts the number of times the opening of the APC valve exceeds a first threshold value, and when the counted value exceeds a second threshold value, the flow rate control unit controls the flow rate adjustment device, The supply flow rate of the above-mentioned processing gas is reduced.

The vacuum apparatus of the present invention may further include an opening calculation unit that calculates an increase rate of the opening of the APC valve within a predetermined elapsed time range, and when the increase rate of the opening exceeds a third threshold value, the above-mentioned The flow rate control unit controls the flow rate regulator so that the supply flow rate of the processing gas decreases.

The vacuum device of the present invention may be an etching device for etching an object to be processed.

In the vacuum apparatus of the present invention, the object to be processed may be a substrate for FPD.

In the pressure control method of the present invention, the pressure in the processing container is controlled in a vacuum apparatus comprising: the processing container containing an object to be processed and capable of maintaining the inside in a vacuum state; A gas supply source for supplying processing gas in the processing container; a flow regulating device installed on the gas supply path to adjust the supply flow rate of the processing gas; a pressure detection device for detecting the pressure in the processing container; via the exhaust path and an exhaust device connected to the above-mentioned processing container; and an APC valve disposed on the above-mentioned exhaust path and automatically adjusting the opening according to the pressure value detected by the above-mentioned pressure detection device. In this pressure control method, the opening degree of the APC valve is monitored, and based on the result, the flow rate of the gas to be supplied is adjusted by the flow rate regulator.

In the pressure control method of the present invention, the supply flow rate of the processing gas may be reduced by controlling the opening degree of the APC valve to a predetermined threshold value.

In the pressure control method of the present invention, the number of times the opening of the APC valve exceeds a first threshold may be counted, and when the counted value exceeds a second threshold, the flow rate of the process gas supplied may be controlled to decrease.

In the pressure control method of the present invention, when the increase rate of the opening of the APC valve exceeds a third threshold value within a predetermined elapsed time range, the supply flow rate of the process gas may be controlled to decrease.

In the pressure control method of the present invention, the vacuum device may be an etching device for etching an object to be processed.

In the pressure control method of the present invention, the object to be processed may be a substrate for FPD.

In the etching method of the present invention, an etching device is used to etch an object to be processed. The etching device includes: a processing container that accommodates the object to be processed and is configured to keep the inside in a vacuum state; A gas supply source for processing gas; a flow regulating device installed on the gas supply path to adjust the supply flow rate of the processing gas; a pressure detection device for detecting the pressure in the processing container; connected to the processing container through an exhaust path an exhaust device; and an APC valve that is arranged on the above-mentioned exhaust path and automatically adjusts the opening according to the pressure value detected by the above-mentioned pressure detection device. In this etching method, the opening degree of the APC valve may be monitored, and the flow rate of the supplied gas may be adjusted by the flow rate regulator according to the result.

In the etching method of the present invention, the supply flow rate of the process gas can be decreased by comparing the opening degree of the APC valve with a predetermined threshold value.

In the etching method of the present invention, the number of times the opening of the APC valve exceeds a first threshold is counted, and when the count value exceeds a second threshold, the supply flow rate of the processing gas may be reduced.

In the etching method of the present invention, when the increase rate of the opening of the APC valve exceeds a third threshold within a predetermined elapsed time range, the supply flow rate of the process gas may be controlled to decrease.

Invention effect

According to the present invention, in the vacuum apparatus mainly using the APC valve to regulate the pressure in the processing container, the opening degree of the APC valve is monitored, and the flow rate of the processing gas introduced into the processing container is adjusted based on the result. For example, when the opening degree increases, the gas flow rate is decreased, and the pressure increase in the processing container is offset by suppressing the processing gas flow rate, thereby reducing the pressure increase in the processing container. In addition, the opening degree of the APC valve is increased before the pressure in the processing chamber is increased, and therefore, responsiveness is superior to changing the flow rate of the processing gas based on the pressure measurement result in the processing chamber. Therefore, according to the present invention, it is possible to reliably control the pressure in the processing container even in a large vacuum apparatus without increasing the number of vacuum pumps and APC valves installed.

Description of drawings

FIG. 1 is a cross-sectional view schematically showing the structure of a plasma etching apparatus according to a first embodiment of the present invention.

2 is a block diagram showing a hardware configuration of a control unit of a plasma etching apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a hardware configuration of a device controller in FIG. 2 .

FIG. 4 is a functional block diagram showing a functional configuration of a device controller in FIG. 2 .

FIG. 5 is a flowchart showing an example of steps of the pressure control method according to the first embodiment of the present invention.

6 is a graph showing temporal changes in the pressure in the processing chamber and the opening degree of the APC valve when the plasma etching process is performed on the etching target film by the conventional method.

FIG. 7 is a graph showing temporal changes in light emission from plasma generated in the processing chamber during the same plasma etching process as in FIG. 6 .

FIG. 8 is a diagram illustrating temporal changes in the opening degree of the APC valve and temporal changes in the process gas flow rate obtained by the pressure control method according to the first embodiment of the present invention.

FIG. 9 is a graph showing experimental results of applying the pressure control method according to the first embodiment of the present invention to an actual plasma etching process.

FIG. 10 is a functional block diagram showing a functional configuration of a device controller according to a second embodiment of the present invention.

FIG. 11 is a flowchart showing an example of the procedure of the pressure control method according to the second embodiment of the present invention.

Explanation of reference signs

1…handling container

1a...bottom wall

1b... side wall

1c…Cover body

11…base

12...Substrate

13, 14...Sealing parts

15...Insulation parts

31...nozzle

33…Gas diffusion space

35...gas ejection hole

37...Gas inlet

39...Processing gas supply pipe

41...valve

43…mass flow controller

45…gas supply source

51...Opening for exhaust

53…exhaust pipe

53a...Flange part

55...APC valve

57...exhaust device

61...Pressure gauge

71…Power supply line

73…Matching Box (M.B.)

75…High frequency power supply

100...Plasma etching apparatus.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[first embodiment]

1 is a cross-sectional view showing a schematic configuration of a plasma etching apparatus as a first embodiment of the processing apparatus of the present invention. FIG. 2 is an enlarged cross-sectional view showing a main part of FIG. 1 . As shown in FIG. 1 , the plasma etching apparatus 100 is configured as a capacitively coupled parallel plate plasma etching apparatus that etches a glass substrate (hereinafter, simply referred to as “substrate”) S for an FPD as an object to be processed, for example. In addition, examples of the FPD include a liquid crystal display (LCD), an electroluminescence (Electro Luminescence; EL) display, a plasma display panel (PDP), and the like.

This plasma etching apparatus 100 has a processing container 1 formed of aluminum on which anodic oxidation treatment (aluminum oxide film treatment) has been performed on the inner side and formed in a cylindrical shape. The main body (container body) of the processing container 1 is composed of a bottom wall 1 a and four side walls 1 b (only two are shown). In addition, a cover body 1c is joined to the upper portion of the main body of the processing container 1 . Although not shown in the drawing, an opening for substrate transfer and a gate valve for sealing the opening for substrate transfer are provided on the side wall 1b.

The lid body 1c is configured to be able to be opened and closed with respect to the side wall 1b by an unshown opening and closing mechanism. In the state where the lid 1c is closed, the joint portion between the lid 1c and each side wall 1b is sealed by the O-ring 3 to maintain the airtightness in the processing container 1 .

A frame-shaped insulating member 10 is arranged at the bottom of the processing container 1 . A base 11 serving as a mounting table on which the substrate S can be mounted is provided on the insulating member 10 . The base 11 also serving as a lower electrode includes a base material 12 . The base material 12 is formed of a conductive material such as aluminum or stainless steel (SUS), for example. The base material 12 is disposed on the insulating member 10, and a sealing member 13 such as an O-ring is provided at the junction of both members to maintain airtightness. Between the insulating member 10 and the bottom wall 1a of the processing container 1, airtightness is also maintained by a sealing member 14 such as an O-ring. The side periphery of the base material 12 is surrounded by an insulating member 15 . Thereby, the insulation of the side surface of susceptor 11 is ensured, and abnormal discharge during plasma processing is prevented.

Above the susceptor 11 , a shower head 31 functioning as an upper electrode is provided parallel to and facing the susceptor 11 . The shower head 31 is supported by the upper lid body 1 c of the processing container 1 . The shower head 31 is hollow, and a gas diffusion space 33 is provided therein. In addition, a plurality of gas ejection holes 35 for ejecting processing gas are formed on the lower surface (the surface facing the susceptor 11 ) of the shower head 31 . The shower head 31 is grounded, and constitutes a pair of parallel plate electrodes together with the susceptor 11 .

A gas introduction port 37 is provided near the upper center of the shower head 31 . The gas introduction port 37 is connected to a processing gas supply pipe 39 . The processing gas supply pipe 39 is connected to a gas supply source 45 for supplying a processing gas for etching via two valves 41 , 41 and a mass flow controller (MFC) 43 . As the processing gas, for example, a rare gas such as Ar gas, etc. other than halogen gas and O ₂ gas can be used.

Exhaust openings 51 penetrating at a plurality of locations (for example, eight locations) are formed in the bottom wall 1 a inside the processing container 1 . Each exhaust opening 51 is connected to an exhaust pipe 53 . The exhaust pipe 53 has a flange portion 53 a at its end, and is fixed with an O-ring (not shown) provided between the flange portion 53 a and the bottom wall 1 a. An APC valve 55 is provided on the exhaust pipe 53 , and the exhaust pipe 53 is connected to an exhaust device 57 . The exhaust device 57 includes, for example, a vacuum pump such as a turbomolecular pump, thereby being configured to be able to evacuate the inside of the processing container 1 to a predetermined reduced pressure atmosphere. A total of eight APC valves 55 provided in each exhaust pipe 53 are composed of one master valve and seven slave valves, and each slave valve operates in conjunction with the master valve. That is, the eight APC valves 55 perform opening and closing operations in synchronization with each other.

In addition, the plasma etching apparatus 100 is provided with a pressure gauge 61 for measuring the pressure inside the processing container 1 . The pressure gauge 61 is connected to the main control valve among the eight APC valves 55 , and provides the measurement result of the pressure in the processing container 1 to the APC valve 55 in real time. The APC valve 55 changes the opening degree based on the measurement result of the pressure gauge 61 to automatically adjust the conductance of the exhaust pipe 53 .

The base material 12 of the base 11 is connected to the power supply line 71 . This power supply line 71 is connected to a high-frequency power supply 75 via a matching box (M.B.) 73 . Thus, high-frequency power of, for example, 13.56 MHz is supplied from the high-frequency power supply 75 to the susceptor 11 serving as the lower electrode. Further, the power supply line 71 is introduced into the processing container 1 through the power supply opening 77 as a through opening formed in the bottom wall 1a.

Each component of the plasma etching apparatus 100 is connected to the control unit 80 to be controlled. Referring to FIG. 2 , the control unit 80 of the substrate processing system included in a part of the plasma etching apparatus 100 of the present embodiment will be described. FIG. 2 is a block diagram showing a hardware configuration of the control unit 80 . As shown in FIG. 2 , the control unit 80 includes: an equipment controller (Equipment Controller; hereinafter, sometimes referred to as “EC”) 81; (Module Controller; hereinafter, sometimes referred to as "MC") 83; and a switching hub (HUB) 85 connecting EC81 and MC83.

The EC81 is a main control unit that integrates a plurality of MC83 and controls the overall operation of the substrate processing system. Each of the plurality of MC83 is a sub-control unit that controls the operation of each module including the plasma etching apparatus 100 under the control of the EC81. Switching hub 85 switches MC83 connected to EC81 based on the control signal from EC81.

The EC81 sends control signals to each MC83 based on the control program for implementing various processes on the substrate S performed by the substrate processing system and the plan in which processing condition data and the like are recorded, thereby controlling the overall operation of the substrate processing system .

The control unit 80 further includes a subnet 87 , a DIST (Distribution) disk 88 , and an input/output (hereinafter referred to as I/O) module 89 . Each MC83 is connected to an I/O module 89 through a subnet 87 and a DIST board 88 .

The I/O module 89 has a plurality of I/O units 90 . The I/O unit 90 is connected to each terminal device of each module including the plasma etching apparatus 100 . Although not shown, the I/O unit 90 is provided with an I/O board for controlling input and output of digital signals, analog signals, and serial signals. Control signals for each terminal device are output from the I/O section 90 . In addition, output signals from the respective terminal devices are respectively input to the I/O section 90 . In the plasma etching apparatus 100 , examples of terminal devices connected to the I/O unit 90 include a mass flow controller (MFC) 43 , an APC valve 55 , a pressure gauge 61 , and an exhaust device 57 .

The EC 81 is connected via a LAN (Local Area Network) 91 to a computer 93 as an MES (Manufacturing Execution System) that manages the manufacturing process of the entire factory in which the substrate processing system 100 is installed. The computer 93 cooperates with the control unit 80 of the substrate processing system 100 to feed back real-time information related to the process of the factory to the core business system, and makes a judgment related to the process in consideration of the load of the entire factory. The computer 93 can be connected to an information processing device such as another computer 95 .

Next, an example of the hardware configuration of EC81 will be described with reference to FIG. 3 . The EC81 includes: a main control unit 101; an input device 102 such as a keyboard and a mouse; an output device 103 such as a printer; a display device 104; a storage device 105; an external interface 106; The main control unit 101 has a CPU (Central Processing Unit) 111 , a RAM (Random Access Memory) 112 , and a ROM (Read Only Memory) 113 . The form of the storage device 105 is not limited as long as it can store information, and is, for example, a hard disk device or an optical disk device. In addition, the storage device 105 records information on a computer-readable recording medium 115 and reads information from the recording medium 115 . The form of the recording medium 115 is not limited as long as it can store information, for example, a hard disk, an optical disk, a flash memory, and the like. The recording medium 115 may be a recording medium in which the protocol of the plasma etching method of this embodiment is recorded.

In EC81, CPU111 uses RAM112 as a work area, and executes the program stored in ROM113 or memory|storage device 105, By this, plasma etching process to the board|substrate S can be performed in the plasma etching apparatus 100 of this embodiment. In addition, the hardware structure of the computers 93 and 95 in FIG. 2 is also the structure shown in FIG. 3, for example. In addition, the hardware configuration of the MC83 shown in FIG. 2 is, for example, the configuration shown in FIG. 3 or a configuration obtained by removing unnecessary components from the configuration shown in FIG. 3 .

Next, the functional configuration of EC81 will be described with reference to FIG. 4 . FIG. 4 is a functional block diagram showing the functional configuration of EC81. In addition, in the following description, the code|symbol in FIG. 3 is also referred as the part which becomes the structure shown in FIG. 3 as the hardware structure of EC81. As shown in FIG. 4 , EC81 includes a processing control unit 121 , an opening degree monitoring unit 122 , an opening degree determination unit 123 , an excess counter 124 , and an input/output control unit 125 . They are realized by CPU 111 executing programs stored in ROM 113 or storage device 105 using RAM 112 as a work area.

The processing control unit 121 transmits a control signal to each MC 83 based on the recipe, parameters, and the like stored in the storage device 105 in advance, thereby performing control so that a desired plasma etching process is performed in the plasma etching apparatus 100 . In addition, the processing control unit 121 has a flow rate control unit 121a.

The opening monitoring unit 122 monitors the opening of the APC valve 55 and acquires the information in real time. Specifically, the opening degree of the APC valve 55 is divided into, for example, 1000 levels of 0 to 1000, and is sent from the APC valve 55 to the opening degree monitoring unit 122 through the MC83 in real time as digital input (DI) information. In addition, the opening monitoring unit 122 may exist as a function not attached to the EC 81 but attached to the APC valve 55 . In this case, the MC83 of the plasma etching apparatus 100 can acquire the opening degree which is digital input (DI) information from the APC valve 55, and can transmit it to EC81.

The opening degree determination unit 123 refers to the opening degree of the APC valve 55 obtained in real time by the opening degree monitoring unit 122 (or the opening degree monitoring function of the APC valve 55), and determines whether the opening degree has exceeded a predetermined threshold value (for example, the first threshold value). determination. Here, for the first threshold value, the opening degree determination unit 123 refers to a value previously stored in the storage device 105 as a parameter.

The excess counter 124 refers to the determination result of the opening degree determination unit 123, and when the opening degree exceeds the first threshold, counts up the number of times by one.

The input/output control unit 125 controls input from the input device 102 , controls output to the output device 103 , controls display on the display device 104 , and controls input/output of external data through the external interface 106 .

The flow control unit 121 a controls the valves 41 , 41 and a mass flow controller (MFC) 43 to control the flow rate of the processing gas supplied from the gas supply source 45 into the processing chamber 1 . In addition, the flow control unit 121a judges whether the excess count value counted by the excess counter 124 has exceeded a predetermined threshold value (second threshold value), and when the excess count value exceeds the second threshold value, the MC83 controls the mass flow controller. The (MFC) 43 sends a control signal to reduce the flow rate of the processing gas by a predetermined amount. Accordingly, the mass flow controller (MFC) 43 reduces the flow rate of the processing gas by a predetermined amount. Here, for the second threshold, the flow control unit 121a refers to a value previously stored in the storage device 105 as a parameter or a part of the recipe. Also, regarding the reduction amount (V0-V1) of the processing gas, the flow rate control unit 121a refers to a value previously stored in the storage device 105 as a parameter or a part of the recipe.

Next, the processing operation of the plasma etching apparatus 100 configured as above will be described. First, with the gate valve (not shown) opened, the substrate S as the object to be processed is carried into the processing container 1 through the opening for substrate transfer by using the fork of the transfer device (not shown), and delivered to the susceptor 11. . Then, the gate valve is closed, and the inside of the processing container 1 is evacuated to a predetermined vacuum degree by the exhaust device 57 .

Next, the valve 41 is opened, and the processing gas is introduced from the gas supply source 45 into the gas diffusion space 33 of the shower head 31 through the processing gas supply pipe 39 and the gas introduction port 37 . At this time, the flow rate of the process gas is controlled by the mass flow controller 43 . The processing gas introduced into the gas diffusion space 33 is further uniformly ejected toward the substrate S placed on the susceptor 11 through the plurality of ejection holes 35, and the pressure in the processing chamber 1 is maintained at a predetermined value.

In this state, high-frequency power is applied to the susceptor 11 from the high-frequency power supply 75 via the matching box 73 . Accordingly, a high-frequency electric field is generated between the susceptor 11 as the lower electrode and the shower head 31 as the upper electrode, and the process gas is dissociated and turned into plasma. The substrate S is etched using this plasma.

After performing the etching process, the application of the high-frequency power from the high-frequency power source 75 is stopped, and the gas introduction is stopped, and then the inside of the processing container 1 is depressurized to a predetermined pressure. Next, the gate valve is opened, the substrate S is transferred from the susceptor 11 to the fork of a transfer device (not shown), and the substrate S is carried out from the substrate transfer opening of the processing container 1 . Through the above operations, the plasma etching process on the substrate S is completed.

During the plasma etching process described above, in the plasma etching apparatus 100 of the present embodiment, the control unit 80 monitors the opening degree of the APC valve 55 and detects an increase in the opening degree as a signal of a pressure increase. Based on the detection result, feedback control is performed on the mass flow controller (MFC) 43 , whereby the supply amount of the processing gas is suppressed, and the pressure increase in the processing container 1 is moderated.

Hereinafter, the pressure control method of this embodiment will be specifically described with reference to FIGS. 5 to 9 . FIG. 5 is a flowchart showing an example of the steps of the pressure control method of the present embodiment executed by the control unit 80 . FIG. 5 shows a procedure for performing a process of suppressing the flow rate of the mass flow controller (MFC) 43 once by monitoring the opening degree of the APC valve 55 .

First, in step S1 , the EC 81 acquires the opening degree of the APC valve 55 . As mentioned above, the opening degree of the APC valve 55 may be obtained by the opening degree monitoring unit 122 of the EC81 through the MC83, or may be sent to the EC81 through the MC83 by using the opening degree monitoring unit (not shown) attached to the APC valve 55 .

Next, in step S2, the opening degree determination part 123 of EC81 judges whether the opening degree of the APC valve 55 acquired in step S1 has exceeded the 1st threshold value. The opening degree determination unit 123 compares the obtained opening degree with a first threshold value which is a parameter set in advance.

When it is determined in step S2 that the opening exceeds the first threshold (Yes), then in step S3 , the excess counter 124 counts up the excess count value once based on the determination result from the opening determination unit 123 .

Next, in step S4, the flow rate control unit 121a determines whether or not the cumulative value of the excess count value counted by the excess counter 124 has exceeded the second threshold value. When it is determined that the count value exceeds the second threshold (Yes), in step S5, the flow control unit 121a sends a control signal to the mass flow controller (MFC) 43 through the MC83 so as to decrease the flow rate of the processing gas by a predetermined amount. . In the present embodiment, the reason for counting the number of times of exceeding the first threshold using the exceeding counter 124 is as follows. During the plasma etching process, the pressure in the processing container 1 fluctuates with a certain amplitude. Therefore, when the first threshold value is exceeded only once, it is not necessarily a large pressure change, and appropriate pressure control may not be performed. Therefore, in the present embodiment, the number of times the first threshold value is exceeded is counted by the excess counter 124 and compared with the second threshold value, whereby highly reliable pressure control is realized in the plasma etching apparatus 100 .

On the other hand, when it is determined in step S2 that the opening degree does not exceed the first threshold (No), the process returns to step S1 again, and the steps of step S1 and step S2 are repeated. The steps of step S1 and step S2 are repeated until it is determined in step S2 that the opening exceeds the first threshold (Yes), or the plasma etching process ends.

In addition, when it is determined in step S4 that the excess count value does not exceed the second threshold value (No), the process returns to step S1 again, and the steps from step S1 to step S4 are repeated. The steps from step S1 to step S4 are repeated until it is determined in step S4 that the increase rate of the opening exceeds the second threshold value (Yes), or the plasma etching process ends.

According to the steps of step S1 to step S5 described above, it is possible to suppress the pressure change in the processing container 1 . In addition, as described above, in terms of highly reliable pressure control, it is advantageous to use the exceeding counter 124 to count the number of times the first threshold value is exceeded. The normal pressure fluctuation range in the processing container 1 is large, and the flow rate of the processing gas is adjusted by judging whether it has exceeded the first threshold value.

＜Function＞

In the plasma etching apparatus 100, without special control, the pressure in the processing chamber 1 may rise rapidly immediately after the etching progresses and the etching target film on the substrate S disappears. First, this phenomenon will be described with reference to FIGS. 6 and 7 . FIG. 6 is a characteristic diagram showing temporal changes in the pressure in the processing chamber 1 and the opening degree of the APC valve 55 when the etching target film is etched using the plasma etching apparatus 100 . FIG. 7 is a characteristic diagram showing temporal changes in light emission from plasma generated in the processing chamber 1 during the same plasma etching process as in FIG. 6 . In addition, as a film to be etched, a film in which a titanium layer, an aluminum layer, and a titanium layer were sequentially laminated on the substrate S was used, and chlorine gas was used as an etching gas. In FIG. 7 , the intensity of Ti emission at a wavelength of 335 nm and the intensity of Al emission at a wavelength of 396 nm are shown.

Referring to FIG. 6 , it can be seen that plasma etching starts around 10 seconds on the horizontal axis and ends around 125 seconds. During the plasma etching, the pressure in the processing chamber 1 changes substantially constantly, but it turns to increase 100 to 110 seconds before the end of the plasma etching, and continues to increase until the end of the etching. On the other hand, the opening degree of the APC valve 55 increases rapidly 100 to 110 seconds before the end of etching, and becomes constant after 110 seconds (the opening degree is fully open).

On the other hand, referring to FIG. 7 , the etching of the Ti film of the upper layer proceeded to around 25 seconds on the horizontal axis, whereby Ti emission was observed. Next, with the etching of the intermediate Al film, the Al luminescence becomes dominant, and the Ti luminescence due to the etching of the underlying Ti film peaks around 100 seconds after the Al luminescence disappears. In addition, as shown in FIG. 7, the light emission of the components of each film overlaps because the etching does not proceed uniformly on the surface of the large-area substrate S, but for example, the etching proceeds from the outer periphery of the substrate S to the center, thereby, the surface of the substrate S is etched. In-plane, the etching of the two layers stacked on top of each other is performed simultaneously. From FIG. 7 , it can be considered that the Ti film in the lowermost layer of the three-layered film to be etched is etched and disappeared during the period from 100 seconds to 110 seconds after the Ti emission peaked, thereby forming a base on the substrate S. The stage in which the membrane gradually begins to emerge. During the period from 100 seconds to 110 seconds, as shown in FIG. 6 , the opening degree of the APC valve 55 rises sharply, and when the opening degree becomes fully open, pressure control cannot be performed thereafter, and the pressure in the processing container 1 decreases rapidly. for rising.

As can be seen from FIGS. 6 and 7 , the reason for the pressure increase in the processing container 1 is that the processing gas consumed by the reaction with the target film during the existence of the etching target film is not consumed when the etching progresses and the etching target film disappears. . When such a sudden pressure change occurs, as shown in FIG. 6 , the opening degree of the APC valve 55 becomes fully open and remains constant, and the pressure control in the processing container 1 cannot be performed by the APC valve 55 . In addition, as can be seen from FIGS. 6 and 7 , the opening degree of the APC valve 55 increases before the pressure in the processing container 1 increases.

Therefore, in the pressure control method of the present embodiment and the plasma etching method using the pressure control method, following the steps from step S1 to step S5 illustrated in FIG. The opening degree of the APC valve 55 changes the flow rate of the processing gas introduced into the processing chamber 1 according to the result. Here, FIG. 8 is an explanatory diagram schematically showing temporal changes in the opening degree of the APC valve and the flow rate of the process gas when the pressure control method of the present embodiment is implemented. C1 , C2 , C3 . . . in FIG. 8 indicate intervals in which the excess counter 124 counts and counts the number of times the opening degree of the APC valve 55 exceeds the first threshold Th. In addition, t1, t2, and t3 on the horizontal axis of FIG. 8 indicate that when the count value of the counter 124 exceeds the second threshold value, the EC81 sends a control signal to the mass flow controller (MFC) 43 through the MC83 to make the flow rate of the processing gas The moment to reduce the prescribed amount.

According to the steps of step S1 to step S5 illustrated in FIG. 5 , at first, the opening degree increase of the APC valve 55 occurring before the pressure increase in the processing container 1 is monitored. The number of times the opening degree of 55 exceeds the first threshold Th is counted and accumulated. At time t1 when the count value of the counter 124 exceeds the second threshold, the mass flow controller (MFC) 43 reduces the flow rate of the process gas from V ₀ to V ₁ .

Next, according to steps S1 to S5 in FIG. 5 , the opening of the APC valve 55 is monitored to increase, and based on the result, the number of times the opening of the APC valve 55 exceeds the first threshold Th is counted up in section C2. At time t2 when the count value of the exceeding counter 124 exceeds the second threshold value, the mass flow controller (MFC) 43 reduces the flow rate of the processing gas from V ₁ to V ₂ . Thereafter, when the pressure continues to rise, the same process is repeated until the plasma etching process is completed.

As described above, in the pressure control method of the present embodiment and the plasma etching method using the pressure control method, the pressure increase in the processing container 1 is canceled out by suppressing the flow rate of the processing gas, thereby reducing the stress of the processing container 1. internal pressure rises.

FIG. 9 shows experimental results of applying the pressure control method of this embodiment to an actual plasma etching process in the plasma etching apparatus 100 . In this experiment, a laminated film of Ti/Al/Ti was used as the etching target film, and Cl ₂ (chlorine) was used as the processing gas (etching gas). According to the above steps S1 to S5, the opening degree increase of the APC valve 55 is monitored, and the flow rate of the processing gas introduced into the processing chamber 1 is reduced according to the opening degree increase. Specifically, by repeating steps S1 to S5 , as shown in FIG. 9 , the flow rate of the processing gas was decreased stepwise from 3500 ml/min (sccm) to 1700 ml/min (sccm). As a result, the pressure in the processing container 1 changes stably at about 10 mTorr (1.3 Pa). Therefore, the effectiveness of the pressure control method of this embodiment can be confirmed from FIG. 9 .

As described above, according to the present embodiment, in the plasma etching apparatus 100 that mainly uses the APC valve 55 to regulate the pressure in the processing chamber 1, the opening degree of the APC valve 55 is monitored, and based on the result, the pressure in the processing chamber 1 is controlled. The flow rate of the introduced process gas is adjusted. For example, when the opening degree increases, the gas flow rate is decreased, and the pressure increase in the processing container 1 is offset by suppressing the processing gas flow rate, thereby relieving the pressure increase in the processing container 1 . In addition, the opening degree of the APC valve 55 is increased before the pressure in the processing chamber 1 is increased, and therefore, responsiveness is excellent compared to changing the flow rate of the processing gas based on the pressure measurement result in the processing chamber 1 . Therefore, according to the present invention, it is possible to reliably control the pressure in the processing chamber 1 even with a large vacuum apparatus without increasing the number of exhaust apparatuses 57 including vacuum pumps and APC valves 55 installed. In addition, generation of excess radicals due to pressure increase in the processing chamber 1 can be suppressed, and therefore, distortion of the shape of the pattern formed on the surface of the substrate S can also be prevented.

[Second Embodiment]

Next, a plasma etching apparatus, a pressure control method, and a plasma etching method according to a second embodiment of the present invention will be described with reference to FIGS. 10 and 11 . In the present embodiment, the increase rate of the opening degree of the APC valve 55 is obtained within a predetermined time period, and whether or not to adjust the gas flow rate is determined based on the increase rate. In the following description, differences from the first embodiment will be mainly described, and overlapping descriptions of the same configurations as in the first embodiment will be omitted.

FIG. 10 is a functional block diagram showing a functional configuration of an apparatus controller (EC) 81A in the plasma etching apparatus according to this embodiment. In the following description, reference numerals in FIG. 3 are also referred to as parts of the hardware configuration of EC81A as shown in FIG. 3 . As shown in FIG. 10 , EC81A includes a processing control unit 121 , an opening degree monitoring unit 122 , an opening degree calculation unit 126 , and an input/output control unit 125 . They are realized by CPU 111 executing programs stored in ROM 113 or storage device 105 using RAM 112 as a work area.

The processing control unit 121 , the opening monitoring unit 122 , and the input/output control unit 125 have the same functions as those of the first embodiment.

The opening degree computing unit 126 refers to the opening degree of the APC valve 55 acquired in real time by the opening degree monitoring unit 122 (or the opening degree monitoring unit of the APC valve 55 ), and calculates the value of the opening degree of the APC valve 55 within a predetermined elapsed time range. The increase rate is calculated. That is, the opening degree calculation unit 126 refers to the opening degree of the opening degree monitoring unit 122 (or the opening degree monitoring unit of the APC valve 55 ) at an arbitrary time interval previously stored in the storage device 105 as a parameter or a part of the plan, and calculates the opening degree according to the opening degree of the opening degree monitoring unit 122 (or the opening degree monitoring unit of the APC valve 55 ). The difference value finds the increase rate of the opening degree in the time interval.

The flow control unit 121a judges whether the increase rate of the opening calculated by the opening calculation unit 126 has exceeded a predetermined threshold (third threshold), and if the increase rate of the opening exceeds the third threshold, the MC83 A control signal is sent to a mass flow controller (MFC) 43 so as to decrease the flow rate of the processing gas by a predetermined amount. Accordingly, the mass flow controller (MFC) 43 reduces the flow rate of the processing gas by a predetermined amount. Here, regarding the third threshold value, the flow rate control unit 121a refers to a value previously stored in the storage device 105 as a parameter or a part of the recipe. In addition, the flow control unit 121a also refers to a value previously stored in the storage device 105 as a parameter or a part of the recipe for the reduction amount of the processing gas.

The pressure control method of this embodiment can include the steps of step S11 to step S14 shown in FIG. 11 . FIG. 11 shows a procedure for performing a process of suppressing the flow rate of the mass flow controller (MFC) 43 once by monitoring the opening degree of the APC valve 55 .

First, in step S11 , EC81A acquires the opening degree of APC valve 55 . The opening degree of the APC valve 55 may be acquired by the opening degree monitoring unit 122 of the EC81A through the MC83, or may be transmitted to the EC81A through the MC83 using the opening degree monitoring function attached to the APC valve 55.

Next, in step S12 , the opening degree computing unit 126 of EC81A calculates the rate of increase within the predetermined elapsed time range of the opening degree of the APC valve 55 acquired in step S11 .

Next, in step S13, the flow rate control unit 121a determines whether or not the increase rate of the degree of opening calculated by the degree of opening calculation unit 126 has exceeded the third threshold value. When it is determined that the increase rate of the opening exceeds the third threshold (Yes), in the next step S14, the flow rate control unit 121a sends a control signal to the mass flow controller (MFC) 43 through the MC83 so that the process gas The flow rate is reduced by the specified amount.

On the other hand, when it is determined in step S13 that the excess count value does not exceed the third threshold (No), the process returns to step S11 again, and steps from step S11 to step S13 are repeated. The steps from step S11 to step S13 are repeated until it is determined in step S13 that the increase rate of the opening exceeds the third threshold value (Yes), or the plasma etching process ends.

According to the steps from step S11 to step S14 described above, the pressure fluctuation in the processing container 1 can be suppressed. In the present embodiment, the increase rate of the opening degree within a predetermined time is used as an index, but similar control may be performed based on a difference in the opening degree within a predetermined time.

Other configurations and effects of this embodiment are the same as those of the first embodiment.

As mentioned above, although the embodiment of this invention was demonstrated in detail for the purpose of illustration, this invention is not limited to the said embodiment. Those skilled in the art can make many changes without departing from the spirit and scope of the present invention, and these are also included in the scope of the present invention. For example, in the above-mentioned embodiments, a parallel plate type plasma etching device was cited as an example, but the present invention can also be applied to, for example, an inductively coupled plasma device, a surface wave plasma device, an ECR (Electron Cyclotron Resonance: electron cyclotron Resonance) plasma device, helicon wave plasma device and other plasma etching devices. In addition, as long as it is a vacuum device equipped with an APC valve and necessary to adjust the pressure in the chamber, it is not limited to a dry etching device, and can be equally applied to a film forming device, an ashing device, and the like.

In addition, the present invention is not limited to the case where the substrate for FPD is used as the object to be processed, but can also be applied to the case where the object to be processed is used as a semiconductor wafer or a substrate for solar cells, for example.

In addition, in the above-mentioned embodiment, the case where the opening degree of the APC valve 55 and the pressure in the processing container 1 are increased and the flow rate of the processing gas is decreased is cited as an example, but the present invention can also be applied to the opening of the APC valve 55. The temperature and the pressure in the processing container 1 are reduced, and the flow rate of the processing gas is increased.

Claims (16)

1. A vacuum device, characterized in that, possesses: A processing container that accommodates the object to be processed and can maintain a vacuum inside; a gas supply source for supplying processing gas into the processing container via a gas supply path; a flow regulating device arranged on the gas supply path to regulate the supply flow of the processing gas; a pressure detection device for detecting the pressure in the processing container; an exhaust device connected to the processing container via an exhaust path; An automatic pressure control valve that is installed on the exhaust path and automatically adjusts its opening according to the pressure value detected by the pressure detection device; an opening degree monitoring section that monitors the opening degree of the automatic pressure control valve; and A flow rate control unit that adjusts the flow rate of gas supplied by the flow rate adjustment device based on the monitoring result of the opening monitoring unit. 2. The vacuum device according to claim 1, characterized in that: The flow rate control unit controls the flow rate adjustment device by comparing the opening degree of the automatic pressure control valve with a predetermined threshold so that the supply flow rate of the processing gas decreases. 3. The vacuum device according to claim 1, characterized in that: further comprising a counting unit that counts the number of times the opening of the automatic pressure control valve exceeds a first threshold value, When the counted value exceeds a second threshold value, the flow rate control unit controls the flow rate regulator so that the supply flow rate of the process gas is reduced. 4. The vacuum device according to claim 1, characterized in that: further comprising an opening calculation unit that calculates an increase rate of the opening of the automatic pressure control valve within a predetermined elapsed time range, When the rate of increase of the opening exceeds a third threshold, the flow rate control unit controls the flow rate adjustment device so that the supply flow rate of the processing gas decreases. 5. The vacuum device according to any one of claims 1 to 4, characterized in that: The vacuum device is an etching device for etching an object to be processed. 6. The vacuum device according to claim 5, characterized in that: The object to be processed is a substrate for FPD. 7. A pressure control method for a vacuum device, characterized in that: The vacuum device has: A processing container that accommodates an object to be processed and is configured to keep the inside in a vacuum state; a gas supply source for supplying processing gas into the processing container via a gas supply path; a flow regulating device arranged on the gas supply path to regulate the supply flow of the processing gas; a pressure detection device for detecting the pressure in the processing container; an exhaust connected to the processing vessel via an exhaust path; and An automatic pressure control valve that is installed on the exhaust path and automatically adjusts the opening according to the pressure value detected by the pressure detection device, The pressure control method controls the pressure in the processing container, wherein, The opening degree of the automatic pressure control valve is monitored, and the flow rate of the supplied gas is adjusted by the flow rate regulator according to the result. 8. The pressure control method of the vacuum device as claimed in claim 7, characterized in that: The flow rate of the process gas supplied is controlled by comparing the opening degree of the automatic pressure control valve with a predetermined threshold value. 9. The pressure control method of a vacuum device as claimed in claim 7, characterized in that: The number of times the opening degree of the automatic pressure control valve exceeds a first threshold is counted, and when the count value exceeds a second threshold, control is performed such that the supply flow rate of the process gas is reduced. 10. The pressure control method of a vacuum device as claimed in claim 7, characterized in that: When the increase rate of the opening degree of the automatic pressure control valve exceeds a third threshold within a predetermined elapsed time range, control is performed such that the supply flow rate of the processing gas is reduced. 11. The pressure control method of a vacuum device according to any one of claims 7 to 10, characterized in that: The vacuum device is an etching device for etching an object to be processed. 12. The pressure control method of a vacuum device as claimed in claim 11, characterized in that: The object to be processed is a substrate for FPD. 13. An etching method, which uses an etching device to etch an object to be processed, said etching method is characterized in that: The etching device has: A processing container that accommodates an object to be processed and is configured to keep the inside in a vacuum state; a gas supply source for supplying processing gas into the processing container via a gas supply path; a flow regulating device arranged on the gas supply path to regulate the supply flow of the processing gas; a pressure detection device for detecting the pressure in the processing container; an exhaust connected to the processing vessel via an exhaust path; and An automatic pressure control valve that is installed on the exhaust path and automatically adjusts the opening according to the pressure value detected by the pressure detection device, In the etching method, The opening degree of the automatic pressure control valve is monitored, and the flow rate of the supplied gas is adjusted by the flow rate regulator according to the result. 14. The etching method according to claim 13, characterized in that: The supply flow rate of the processing gas is decreased by comparing the opening degree of the automatic pressure control valve with a predetermined threshold value. 15. The etching method according to claim 13, characterized in that: The number of times the opening degree of the automatic pressure control valve exceeds a first threshold is counted, and when the count value exceeds a second threshold, the supply flow rate of the process gas is decreased. 16. The etching method according to claim 13, characterized in that: When the increase rate of the opening degree of the automatic pressure control valve exceeds a third threshold within a predetermined elapsed time range, control is performed such that the supply flow rate of the processing gas is reduced.

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