JP2014093497A - Vacuum device, pressure control method therefor, and etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for suppressing rapid pressure fluctuation in a vacuum device which adjusts pressure in a processing container mainly by an APC valve.SOLUTION: In a step S1, EC81 acquires an opening of an APC valve 55. A step S2 determines whether the opening of the APC valve 55 acquired in the step S1 exceeds a first threshold value. When the step S2 determines that the opening exceeds the first threshold value (Yes), a step S3 integrates an excess count value by one account. A step S4 determines whether an integrated value of the excess count value counted by an excess counter 124 exceeds a second threshold value. When the step S4 determines that the excess count value exceeds the second threshold value (Yes), a flow rate control unit instructs a mass flow controller (MFC) to reduce a process gas flow rate by a prescribed amount by transmitting a control signal to the MFC.

Description

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

  In an FPD (flat panel display) manufacturing process, various plasma processes such as plasma etching, plasma ashing, and plasma film formation are performed on an FPD substrate. As an apparatus for performing such plasma processing, for example, a parallel plate type plasma processing apparatus, an inductively coupled plasma (ICP) processing apparatus, and the like are known. These plasma processing apparatuses are configured as vacuum apparatuses that perform processing by reducing the pressure inside the processing container to a vacuum state.

  As a conventional technique related to pressure control of a vacuum apparatus, Patent Document 1 proposes a method of changing the flow rate of a gas supplied into a processing container by a mass flow controller (MFC) while keeping the conductance of an exhaust path constant. . Further, Patent Document 2 proposes a method of adjusting the pressure inside the processing container by flowing a ballast gas having a constant flow rate upstream of the throttle valve in the exhaust path.

JP 2002-57089 A (FIG. 3 etc.) Japanese Patent Laid-Open No. 10-111152 (FIG. 1 etc.)

  In recent years, processing containers have also become larger in order to process large FPD substrates. Therefore, a single vacuum pump for evacuating the inside of the processing vessel is not sufficient, and a plurality of vacuum pumps are required. On the upstream side of these vacuum pumps in the exhaust direction, an automatic pressure control valve (hereinafter referred to as “APC valve”) is provided, and by automatically adjusting the conductance of the exhaust path, The pressure is adjusted. For example, a plasma etching apparatus employs a method in which a conductance of an exhaust path is adjusted by an APC valve and controlled to a desired process pressure while supplying a constant flow of processing gas into a processing vessel by a mass flow controller during a process. Yes.

  By the way, in the process in which the processing gas is consumed during the plasma etching and the gas volume is reduced, the gas volume is rapidly increased immediately after the etching is completed. This phenomenon occurs because the processing gas consumed for the reaction with the target film while the target film is present is not consumed when the etching progresses and the target film disappears. When such a sudden volume change occurs, the opening degree of the APC valve remains fully open, and the pressure control by the APC valve cannot be caught up. As a result, there has been a problem that the pressure in the processing container rapidly increases with the completion of etching. An abrupt increase in pressure after completion of etching may cause adverse effects such as collapse of the pattern shape formed on the substrate surface due to generation of excessive radicals. In order to cope with the pressure fluctuation as described above, it is necessary to increase the number of vacuum pumps and APC valves installed to ensure a sufficient exhaust capacity, which contributes to an increase in the number of parts and an increase in cost. .

  Accordingly, an object of the present invention is to suppress rapid pressure fluctuations in a vacuum apparatus that mainly adjusts the pressure in the processing vessel using an APC valve.

  The vacuum apparatus of the present invention accommodates an object to be processed and is capable of holding the inside in a vacuum, a gas supply source for supplying a processing gas into the processing container via a gas supply path, and the gas supply path A flow rate adjusting device for adjusting a supply flow rate of the processing gas, a pressure detecting device for detecting a pressure in the processing vessel, an exhaust device connected to the processing vessel via an exhaust path, and the exhaust gas An APC valve that is provided on the road and automatically adjusts the opening based on the pressure value detected by the pressure detection device, an opening monitoring unit that monitors the opening of the APC valve, and the opening monitoring unit And a flow rate control unit for adjusting the flow rate of the gas supplied by the flow rate adjusting device based on the monitoring result.

  In the vacuum device of the present invention, the flow rate control unit controls the flow rate control device to reduce the supply flow rate of the processing gas by comparing the opening degree of the APC valve with a predetermined threshold value. Also good.

  The vacuum device of the present invention further includes a counter unit that counts the number of times that the opening degree of the APC valve exceeds a first threshold value, and the flow rate control unit is configured such that the count value is a second value. When the threshold value is exceeded, the flow rate adjusting device may be controlled so as to reduce the supply flow rate of the processing gas.

  The vacuum device of the present invention further includes an opening degree calculation unit that calculates an increase rate of the opening degree of the APC valve within a predetermined elapsed time range, and the flow rate control unit has an increase rate of the opening degree. When the third threshold value is exceeded, the flow rate adjusting device may be controlled so as to reduce the supply flow rate of the processing gas.

  The vacuum apparatus of the present invention may be an etching apparatus that performs etching on an object to be processed.

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

  The pressure control method of the present invention includes a processing container configured to accommodate an object to be processed and capable of maintaining the inside in a vacuum state, and a gas supply source for supplying a processing gas into the processing container via a gas supply path A flow rate adjusting device that is provided in the gas supply path and adjusts a supply flow rate of the processing gas, a pressure detection device that detects a pressure in the processing container, and is connected to the processing container via an exhaust path. The pressure in the processing vessel is controlled in a vacuum apparatus provided with an exhaust device and an APC valve that is provided in the exhaust passage and automatically adjusts the opening based on a pressure value detected by the pressure detection device. It is a method to do. This pressure control method monitors the opening degree of the APC valve, and adjusts the gas flow rate supplied by the flow rate control device based on the result.

  The pressure control method of the present invention may be controlled so as to reduce the supply flow rate of the processing gas by comparing the opening of the APC valve with a predetermined threshold value.

  The pressure control method of the present invention counts the number of times the opening degree of the APC valve exceeds the first threshold value, and when the count value exceeds the second threshold value, The supply flow rate may be controlled to decrease.

  In the pressure control method of the present invention, the supply flow rate of the processing gas is decreased when the increase rate of the opening degree of the APC valve exceeds a third threshold value within a predetermined elapsed time. You may control to.

  The pressure control method of the present invention may be an etching apparatus in which the vacuum apparatus performs etching on the object to be processed.

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

  The etching method of the present invention includes a processing container configured to accommodate an object to be processed and capable of maintaining the inside in a vacuum state, and a gas supply source for supplying a processing gas into the processing container via a gas supply path. A flow rate adjusting device for adjusting a supply flow rate of the processing gas, a pressure detecting device for detecting a pressure in the processing vessel, and an exhaust gas connected to the processing vessel via an exhaust passage. An object to be processed is etched using an etching apparatus provided with an apparatus and an APC valve that is provided in the exhaust passage and automatically adjusts the opening degree based on a pressure value detected by the pressure detection device . In this etching method, the opening degree of the APC valve may be monitored, and the flow rate of gas supplied by the flow rate adjusting device may be adjusted based on the result.

  The etching method of the present invention may reduce the supply flow rate of the processing gas by comparing the opening degree of the APC valve with a predetermined threshold value.

  The etching method of the present invention counts the number of times the opening degree of the APC valve exceeds the first threshold value, and supplies the processing gas when the count value exceeds the second threshold value. The flow rate may be decreased.

  The etching method of the present invention is controlled to decrease the supply flow rate of the processing gas when the increase rate of the opening degree of the APC valve exceeds a third threshold value within a predetermined elapsed time range. You may do.

  According to the present invention, in a vacuum apparatus that mainly adjusts the pressure in a processing vessel by an APC valve, the opening degree of the APC valve is monitored, and the flow rate of the processing gas introduced into the processing vessel is adjusted based on the result. To do. For example, when the opening degree increases, the gas flow rate is decreased, and the pressure increase in the processing container can be mitigated by offsetting the pressure increase in the processing container by suppressing the processing gas flow rate. Further, since the increase in the opening degree of the APC valve precedes the pressure increase in the processing container, the response is superior to changing the processing gas flow rate based on the pressure measurement result in the processing container. Therefore, according to the present invention, even in a large vacuum apparatus, pressure control in the processing container can be reliably performed without increasing the number of vacuum pumps and APC valves.

It is sectional drawing which shows typically the structure of the plasma etching apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the hardware constitutions of the control part of the plasma etching apparatus which concerns on one embodiment of this invention. It is a block diagram which shows the hardware constitutions of the apparatus controller in FIG. It is a functional block diagram which shows the function structure of the apparatus controller in FIG. It is a flowchart which shows an example of the procedure of the pressure control method which concerns on the 1st Embodiment of this invention. It is drawing which shows the time change of the pressure in a processing container at the time of carrying out plasma etching processing of the etching object film | membrane by the conventional method, and the opening degree of an APC valve | bulb. FIG. 7 is a view showing a time change of light emission of plasma generated in the processing container in the same plasma etching process as FIG. 6. It is drawing explaining the time change of the opening degree of the APC valve by the pressure control method of the 1st Embodiment of this invention, and the time change of a process gas flow rate. It is drawing which shows the experimental result which applied the pressure control method of the 1st Embodiment of this invention to actual plasma etching process. It is a functional block diagram which shows the function structure of the apparatus controller in the 2nd Embodiment of this invention. It is a flowchart which shows an example of the procedure of the pressure control method which concerns on the 2nd Embodiment of this invention.

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

[First Embodiment]
FIG. 1 is a 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. As shown in FIG. 1, a plasma etching apparatus 100 is a capacitively coupled parallel plate plasma etching that etches, for example, an FPD glass substrate (hereinafter simply referred to as “substrate”) S as an object to be processed. It is configured as a device. Examples of the FPD include a liquid crystal display (LCD), an electro luminescence (EL) display, a plasma display panel (PDP), and the like.

  The plasma etching apparatus 100 has a processing container 1 formed into a rectangular tube shape made of aluminum, the inside of which is anodized (anodized). The main body (container main body) of the processing container 1 is composed of a bottom wall 1a and four side walls 1b (only two are shown). A lid 1 c is joined to the upper part of the main body of the processing container 1. Although illustration is omitted, the side wall 1b is provided with a substrate transfer opening and a gate valve for sealing the opening.

  The lid 1c is configured to be openable and closable with respect to the side wall 1b by an opening / closing mechanism (not shown). With the lid 1c closed, the joint between the lid 1c and each side wall 1b is sealed by the O-ring 3 so that the airtightness in the processing container 1 is maintained.

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

  Above the susceptor 11, a shower head 31 that functions as an upper electrode is provided in parallel to and opposite to the susceptor 11. The shower head 31 is supported by a lid 1 c at the top of the processing container 1. The shower head 31 has a hollow shape, and a gas diffusion space 33 is provided therein. A plurality of gas discharge holes 35 for discharging a processing gas are formed on the lower surface of the shower head 31 (the surface facing the susceptor 11). The shower head 31 is grounded and forms a pair of parallel plate electrodes together with the susceptor 11.

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

  Exhaust openings 51 penetrating through a plurality of locations (for example, 8 locations) are formed in the bottom wall 1a in the processing container 1. An exhaust pipe 53 is connected to each exhaust opening 51. The exhaust pipe 53 has a flange portion 53a at its end, and is fixed with an O-ring (not shown) interposed between the flange portion 53a and the bottom wall 1a. The exhaust pipe 53 is provided with an APC valve 55, and the exhaust pipe 53 is connected to an exhaust device 57. The exhaust device 57 includes a vacuum pump such as a turbo molecular pump, for example, and is configured so that the inside of the processing container 1 can be evacuated to a predetermined reduced pressure atmosphere. A total of eight APC valves 55 provided in each exhaust pipe 53 are constituted by 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 / closing operations in synchronization with each other.

  Further, the plasma etching apparatus 100 is provided with a pressure gauge 61 for measuring the pressure in the processing container 1. The pressure gauge 61 is connected to a master valve among the eight APC valves 55, and provides a measurement result of the pressure in the processing container 1 to the APC valve 55 in real time. The APC valve 55 automatically adjusts the conductance of the exhaust pipe 53 by changing the opening degree based on the measurement result of the pressure gauge 61.

  A power supply line 71 is connected to the base material 12 of the susceptor 11. A high frequency power source 75 is connected to the feeder line 71 via a matching box (MB) 73. Thereby, high frequency power of 13.56 MHz, for example, is supplied from the high frequency power supply 75 to the susceptor 11 as the lower electrode. The power supply line 71 is introduced into the processing container 1 through a 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 and controlled by the control unit 80. With reference to FIG. 2, the control part 80 of the substrate processing system which includes the plasma etching apparatus 100 of this Embodiment in the part is demonstrated. FIG. 2 is a block diagram illustrating a hardware configuration of the control unit 80. As shown in FIG. 2, the control unit 80 includes an apparatus controller (Equipment Controller; hereinafter referred to as “EC”) 81 and a plurality (only two are shown in FIG. 2). A module controller (hereinafter also referred to as “MC”) 83 and a switching hub (HUB) 85 that connects the EC 81 and the MC 83.

  The EC 81 is a main control unit (master control unit) that controls the overall operation of the substrate processing system by supervising the plurality of MCs 83. Each of the plurality of MCs 83 is a sub control unit (slave control unit) that controls the operation of each module including the plasma etching apparatus 100 under the control of the EC 81. The switching hub 85 switches the MC 83 connected to the EC 81 in accordance with a control signal from the EC 81.

  The EC 81 sends a control signal to each MC 83 based on a control program for realizing various processes for the substrate S executed in the substrate processing system and a recipe in which processing condition data and the like are recorded. Control the overall operation of the system.

  The control unit 80 further includes a sub-network 87, a DIST (Distribution) board 88, and an input / output (hereinafter referred to as I / O) module 89. Each MC 83 is connected to the I / O module 89 via the sub-network 87 and the 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 end 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 / output of digital signals, analog signals, and serial signals. Control signals for the end devices are output from the I / O unit 90, respectively. Output signals from the end devices are input to the I / O unit 90, respectively. In the plasma etching apparatus 100, examples of the end device 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 a MES (Manufacturing Execution System) that manages the manufacturing process of the entire factory where 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 in the factory to the basic business system and make a determination related to the process in consideration of the load of the entire factory. The computer 93 may be connected to an information processing device such as another computer 95, for example.

  Next, an example of the hardware configuration of the EC 81 will be described with reference to FIG. The EC 81 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, and a bus 107 that connects them to each other. It has. The main control unit 101 includes a CPU (Central Processing Unit) 111, a RAM (Random Access Memory) 112, and a ROM (Read Only Memory) 113. The storage device 105 is not particularly limited as long as it can store information, but is, for example, a hard disk device or an optical disk device. The storage device 105 records information on a computer-readable recording medium 115 and reads information from the recording medium 115. The recording medium 115 may be of any form as long as it can store information. For example, the recording medium 115 is a hard disk, an optical disk, a flash memory, or the like. The recording medium 115 may be a recording medium that records a recipe for the plasma etching method according to the present embodiment.

  In EC81, the CPU 111 uses the RAM 112 as a work area to execute a program stored in the ROM 113 or the storage device 105, so that the plasma etching process for the substrate S can be performed in the plasma etching apparatus 100 of the present embodiment. It has become. The hardware configuration of the computers 93 and 95 in FIG. 2 is also the configuration shown in FIG. 3, for example. The hardware configuration of the MC 83 shown in FIG. 2 is, for example, the configuration shown in FIG. 3 or a configuration in which unnecessary components are removed from the configuration shown in FIG.

  Next, the functional configuration of the EC 81 will be described with reference to FIG. FIG. 4 is a functional block diagram showing a functional configuration of the EC 81. As shown in FIG. In the following description, it is assumed that the hardware configuration of the EC 81 is the configuration shown in FIG. As shown in FIG. 4, the EC 81 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. These are realized by the CPU 111 executing a program stored in the ROM 113 or the storage device 105 using the RAM 112 as a work area.

  The process control unit 121 controls the plasma etching apparatus 100 to perform a desired plasma etching process by transmitting a control signal to each MC 83 based on recipes, parameters, and the like stored in the storage device 105 in advance. To do. Moreover, the process control part 121 has the flow volume control part 121a.

  The opening degree monitoring unit 122 monitors the opening degree 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 from 0 to 1000, and the digital opening (DI) information is sent from the APC valve 55 to the opening degree monitoring unit 122 via the MC 83 in real time. Sent out. Note that the opening degree monitoring unit 122 may have a function attached to the APC valve 55 instead of the EC 81. In that case, it is possible to adopt a configuration in which the MC 83 of the plasma etching apparatus 100 acquires the opening degree as digital input (DI) information from the APC valve 55 and transmits it to the EC 81.

  The opening degree determination unit 123 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 function of the APC valve 55), and the opening degree is a predetermined threshold (for example, the first threshold value) 1 threshold) is exceeded. Here, the opening degree determination unit 123 refers to the first threshold value stored in the storage device 105 in advance as a parameter.

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

  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 inputs / outputs data such as external data via the external interface 106. Control.

  The flow rate control unit 121 a controls the valves 41 and 41 and the mass flow controller (MFC) 43 to control the flow rate of the processing gas supplied from the gas supply source 45 into the processing container 1. The flow controller 121a determines whether or not the excess count value counted by the excess counter 124 exceeds a predetermined threshold (second threshold), and the excess count value is the second. When the threshold value is exceeded, a control signal is sent to the mass flow controller (MFC) 43 via the MC 83 so as to reduce the flow rate of the processing gas by a predetermined amount. Thereby, the mass flow controller (MFC) 43 decreases the flow rate of the processing gas by a predetermined amount. Here, the flow rate controller 121a refers to the second threshold value stored in the storage device 105 in advance as a parameter or a part of the recipe. In addition, the flow rate control unit 121a also refers to the process gas decrease amount (V0-V1) that is stored in advance in the storage device 105 as a parameter or part of the recipe.

  Next, the processing operation in the plasma etching apparatus 100 configured as described above will be described. First, a substrate S, which is an object to be processed, is loaded into the processing container 1 by a fork of a transfer device (not shown) through a substrate transfer opening with a gate valve (not shown) opened, and delivered to the susceptor 11. The Thereafter, the gate valve is closed, and the inside of the processing container 1 is evacuated to a predetermined degree of vacuum 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 mass flow controller 43 controls the flow rate of the processing gas. The processing gas introduced into the gas diffusion space 33 is further uniformly discharged to the substrate S placed on the susceptor 11 through the plurality of discharge holes 35, and the pressure in the processing container 1 becomes a predetermined value. Maintained.

  In this state, high frequency power is applied from the high frequency power supply 75 to the susceptor 11 via the matching box 73. As a result, 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 processing gas is dissociated into plasma. The substrate S is etched by this plasma.

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

  During the plasma etching process, in the plasma etching apparatus 100 of the present embodiment, the control unit 80 monitors the opening of the APC valve 55 and detects the increase in the opening as a signal for increasing the pressure. Based on this detection result, feedback control to the mass flow controller (MFC) 43 is performed, thereby suppressing the supply amount of the processing gas and mitigating the pressure increase in the processing container 1.

  Hereinafter, the pressure control method of the present embodiment will be specifically described with reference to FIGS. FIG. 5 is a flowchart showing an example of the procedure of the pressure control method of the present embodiment executed by the control unit 80. FIG. 5 shows a procedure until the process of suppressing the flow rate of the mass flow controller (MFC) 43 is performed 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 described above, the opening degree acquisition of the APC valve 55 may be performed by the opening degree monitoring unit 122 of the EC 81 via the MC 83, or using an opening degree monitoring unit (not shown) attached to the APC valve 55, You may transmit to EC81 via MC83.

  Next, in step S2, the opening degree determination unit 123 of EC81 determines whether or not the opening degree of the APC valve 55 acquired in step S1 has exceeded a first threshold value. The opening degree determination unit 123 compares the acquired opening degree with a first threshold value that is a preset parameter.

  If it is determined in step S2 that the opening degree has exceeded the first threshold (Yes), then the excess counter 124 counts in excess based on the determination result from the opening degree determination unit 123 in step S3. The value is integrated by 1 count.

  Next, in step S4, the flow control unit 121a determines whether or not the integrated value of the excess count value counted by the excess counter 124 has exceeded the second threshold value. If it is determined that the excess count value exceeds the second threshold value (Yes), in step S5, the flow rate control unit 121a supplies the processing gas to the mass flow controller (MFC) 43 via the MC 83. A control signal is sent out so as to reduce the flow rate of. In the present embodiment, the reason why the excess counter 124 is used to count the number of times the first threshold value is exceeded is as follows. During the plasma etching process, the pressure in the processing chamber 1 fluctuates with a constant amplitude. For this reason, just exceeding the first threshold value does not necessarily cause a large pressure fluctuation, and proper pressure control may not be performed. Therefore, in the present embodiment, the excess counter 124 counts the number of times the first threshold value is exceeded, and compares it with the second threshold value. Control is realized.

  On the other hand, if it is determined in step S2 that the opening does not exceed the first threshold value (No), the process returns to step S1 again, and the procedures of steps S1 and S2 are repeated. The procedure of step S1 and step S2 is repeated until it is determined in step S2 that the opening degree has exceeded the first threshold (Yes) or the plasma etching process is completed.

  If 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 procedure from step S1 to step S4 is repeated. The procedure from step S1 to step S4 is repeated until it is determined in step S4 that the rate of increase in the opening degree exceeds the second threshold (Yes) or the plasma etching process is completed.

  According to the procedure from step S1 to step S5, the pressure fluctuation in the processing container 1 can be suppressed. As described above, in performing reliable pressure control, it is advantageous to count the number of times the first threshold value is exceeded using the excess counter 124. For example, the first threshold is used. By making the value larger than the normal pressure fluctuation range in the processing container 1 during plasma etching, it is possible to adjust the flow rate of the processing gas by determining whether or not the first threshold value has been exceeded.

<Action>
In the plasma etching apparatus 100, unless special control is performed, the pressure in the processing container 1 may increase 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. 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 a time change of light emission of plasma generated in the processing container 1 in the same plasma etching process as that of FIG. As the etching target film, a film in which a titanium layer, an aluminum layer, and a titanium layer are laminated in this order on the substrate S was used, and chlorine gas was used as an etching gas. FIG. 7 shows the intensity of Ti emission at a wavelength of 335 nm and the intensity of Al emission at a wavelength of 396 nm.

  Referring to FIG. 6, plasma etching is started around 10 seconds on the horizontal axis and is finished around 125 seconds. It can be seen that during the plasma etching, the pressure in the processing vessel 1 has remained substantially constant, but has turned to increase in the range of 100 to 110 seconds, which is about to end, and continues to increase until the end of etching. On the other hand, the opening degree of the APC valve 55 increases rapidly between 100 and 110 seconds just before the end of etching, and is constant after 110 seconds (the opening degree is fully open).

  On the other hand, referring to FIG. 7, light emission of Ti is observed as etching of the upper Ti film proceeds up to about 25 seconds on the horizontal axis. Next, Al light emission becomes dominant with the etching of the intermediate Al film, and Ti light emission due to the etching of the underlying Ti film peaks before and after the light emission of Al disappears around 100 seconds. Note that the light emission of the components of each film overlaps as shown in FIG. 7, instead of the etching progressing uniformly on the surface of the large-area substrate S, for example, the etching progresses from the outer periphery to the center of the substrate S. This is because, in the surface of the substrate S, etching of the two films stacked one above the other proceeds simultaneously. From FIG. 7, during the period from 100 seconds to 110 seconds after the peak of the emission of Ti, the lowermost Ti film of the etching target film having a three-layer structure is etched and disappears, so that the substrate S It is considered that the formed base film is in a stage where it gradually begins to be exposed. Then, during the period from 100 seconds to 110 seconds, as shown in FIG. 6, when the opening degree of the APC valve 55 suddenly rises and the opening degree is fully opened, the pressure control becomes impossible thereafter, and the processing container It turns out that the pressure in 1 has started to rise.

  From FIG. 6 and FIG. 7, the pressure increase in the processing container 1 indicates that the processing gas consumed for the reaction with the target film while the target film is present is etched and disappears. It can be seen that this is because it is not consumed. When such a rapid pressure fluctuation occurs, as shown in FIG. 6, the opening degree of the APC valve 55 remains fully open, and the pressure control in the processing container 1 by the APC valve 55 becomes impossible. 6 and 7, it can be seen that the increase in the opening degree of the APC valve 55 occurs prior to the pressure increase in the processing container 1.

  Therefore, in the pressure control method of the present embodiment and the plasma etching method using the pressure control method, the opening degree is increased prior to the pressure increase in the processing container 1 according to the procedure of Step S1 to Step S5 illustrated in FIG. The opening degree of the APC valve 55 that starts is monitored, and the flow rate of the processing gas introduced into the processing container 1 is changed based on the result. Here, FIG. 8 is an explanatory view schematically showing the time variation of the opening degree of the APC valve and the processing gas flow rate when the pressure control method of the present embodiment is implemented. 8, C1, C2, C3... Indicate sections in which the excess counter 124 counts and integrates the number of times that the opening degree of the APC valve 55 exceeds the first threshold value Th. Further, t1, t2, and t3 on the horizontal axis in FIG. 8 are controlled by the EC 81 to the mass flow controller (MFC) 43 via the MC 83 when the count value by the excess counter 124 exceeds the second threshold value. The timing of sending a signal and reducing the flow rate of the processing gas by a predetermined amount is shown.

In accordance with the procedure from step S1 to step S5 illustrated in FIG. 5, first, the increase in the opening degree of the APC valve 55 preceding the pressure increase in the processing container 1 is monitored, and based on the result, the APC valve 55 in the section C1. The excess counter 124 counts and accumulates the number of times that the opening of the first exceeds the first threshold value Th. At a time point t1 when the count value by the excess counter 124 exceeds the second threshold value, the mass flow controller (MFC) 43 decreases the flow rate of the processing gas from V ₀ to V ₁ .

Next, the increase in the opening degree of the APC valve 55 is monitored again in accordance with the procedure of steps S1 to S5 in FIG. 5, and based on the result, the opening degree of the APC valve 55 is set to the first threshold value in the section C2. The number of times exceeding Th is accumulated. Then, at the time t2 when the count value by the excess counter 124 exceeds the second threshold value, the mass flow controller (MFC) 43 decreases the flow rate of the processing gas from V ₁ to V ₂ . Thereafter, if 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 method, the pressure increase in the processing container 1 is reduced by offsetting the pressure increase in the processing container 1 by suppressing the flow rate of the processing gas. Can be relaxed.

FIG. 9 shows a result of an experiment in which the pressure control method of the present embodiment is applied to an actual plasma etching process in the plasma etching apparatus 100. In this experiment, a Ti / Al / Ti laminated film was used as an etching target film, and Cl ₂ (chlorine) was used as a processing gas (etching gas). In accordance with the procedure from Step S1 to Step S5, the increase in the opening degree of the APC valve 55 was monitored, and the flow rate of the processing gas introduced into the processing container 1 was decreased according to the increase in the opening degree. Specifically, by repeating the procedure of step S1 to step S5, the flow rate of the processing gas is gradually reduced from 3500 ml / min (sccm) to 1700 ml / min (sccm) as shown in FIG. . As a result, the pressure in the processing container 1 is stably changed at about 10 mTorr (1.3 Pa). Therefore, the effectiveness of the pressure control method of the present embodiment was confirmed from FIG.

  As described above, according to the present embodiment, in the plasma etching apparatus 100 that mainly adjusts the pressure in the processing chamber 1 by the APC valve 55, the opening degree of the APC valve 55 is monitored, and based on the result, The flow rate of the processing gas introduced into the processing container 1 is adjusted. For example, when the opening degree is increased, the gas flow rate is decreased, and the pressure increase in the processing container 1 is offset by the suppression of the processing gas flow rate, thereby reducing the pressure increase in the processing container 1. Further, since the increase in the opening degree of the APC valve 55 precedes the pressure increase in the processing container 1, it is more responsive than changing the processing gas flow rate based on the pressure measurement result in the processing container 1. Therefore, according to the present invention, even in a large vacuum apparatus, the pressure control in the processing container 1 can be reliably performed without increasing the number of exhaust devices 57 and APC valves 55 including a vacuum pump. Moreover, since generation | occurrence | production of the excessive radical by the pressure rise in the processing container 1 can be suppressed, generation | occurrence | production of the collapse of the pattern formation formed in the board | substrate S surface 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. In the present embodiment, an increase rate of the opening degree of the APC valve 55 within a predetermined time is obtained, and it is determined whether or not to adjust the gas flow rate based on the increase rate. In the following description, differences from the first embodiment will be mainly described, and a duplicate description of the same configuration as that of 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 of the present embodiment. In the following description, the reference numeral in FIG. 3 is also referred to assuming that the hardware configuration of the EC 81A is the configuration shown in FIG. As shown in FIG. 10, the EC 81A 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. These are realized by the CPU 111 executing a program stored in the ROM 113 or the storage device 105 using the RAM 112 as a work area.

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

  The opening calculation unit 126 refers to the opening of the APC valve 55 acquired in real time by the opening monitoring unit 122 (or the opening monitoring unit of the APC valve 55), and within a predetermined elapsed time range, the APC valve 55 The rate of increase of the opening is calculated. That is, the opening degree calculation unit 126 determines the opening degree of the opening degree monitoring unit 122 (or the opening degree monitoring unit of the APC valve 55) according to an arbitrary time interval stored in the storage device 105 in advance as a parameter or a part of the recipe. Reference is made and the rate of increase of the opening within the time interval is obtained from the difference.

  The flow control unit 121a determines whether or not the increase rate of the opening calculated by the opening calculation unit 126 exceeds a predetermined threshold (third threshold), and increases the opening. When the rate exceeds the third threshold value, a control signal is sent to the mass flow controller (MFC) 43 through the MC 83 so as to reduce the flow rate of the processing gas by a predetermined amount. Thereby, the mass flow controller (MFC) 43 decreases the flow rate of the processing gas by a predetermined amount. Here, the flow rate control unit 121a refers to the third threshold value that is stored in the storage device 105 in advance as a parameter or a part of the recipe. In addition, the flow control unit 121a refers to the amount of decrease in the processing gas that is stored in the storage device 105 in advance as a parameter or a part of the recipe.

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

  First, in step S11, the EC 81A acquires the opening degree of the APC valve 55. The opening degree of the APC valve 55 may be acquired via the MC 83 by the opening degree monitoring unit 122 of the EC 81A, or sent to the EC 81A via the MC 83 using the opening degree monitoring function attached to the APC valve 55. Also good.

  Next, in step S12, the opening rate calculation unit 126 of the EC 81A calculates an increase rate of the opening degree of the APC valve 55 acquired in step S11 within a predetermined elapsed time range.

  Next, in step S13, the flow control unit 121a determines whether or not the increase rate of the opening calculated by the opening calculation unit 126 exceeds the third threshold value. And when it determines with the increase rate of an opening exceeded the 3rd threshold value (Yes), the flow control part 121a is mass flow controller (MFC) via MC83 by following step S14. A control signal is sent to 43 so as to reduce the flow rate of the processing gas by a predetermined amount.

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

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

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

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment. Those skilled in the art can make many modifications without departing from the spirit and scope of the present invention, and these are also included within the scope of the present invention. For example, in the above embodiment, a parallel plate type plasma etching apparatus has been described as an example. However, the present invention can be applied to, for example, an inductively coupled plasma apparatus, a surface wave plasma apparatus, an ECR (Electron Cyclotron Resonance) plasma apparatus, and a helicon wave plasma. The present invention can also be applied to other types of plasma etching apparatuses such as an apparatus. Further, any vacuum apparatus that includes an APC valve and requires pressure adjustment in the chamber can be equally applied not only to a dry etching apparatus but also to a film forming apparatus or an ashing apparatus.

  In addition, the present invention is not limited to the FPD substrate used as an object to be processed, and can be applied to, for example, a semiconductor wafer or a solar cell substrate used as an object to be processed.

  Moreover, in the said embodiment, although the case where the opening degree of the APC valve 55 and the pressure in the processing container 1 rose and the flow rate of the processing gas was decreased was given as an example, the opening degree of the APC valve 55 and the processing container 1 were described. The present invention can also be applied to a case where the internal pressure decreases and the flow rate of the processing gas is increased.

  DESCRIPTION OF SYMBOLS 1 ... Processing container, 1a ... Bottom wall, 1b ... Side wall, 1c ... Cover body, 11 ... Susceptor, 12 ... Base material, 13, 14 ... Seal member, 15 ... Insulating member, 31 ... Shower head, 33 ... Gas diffusion space 35 ... Gas discharge hole, 37 ... Gas inlet, 39 ... Process gas supply pipe, 41 ... Valve, 43 ... Mass flow controller, 45 ... Gas supply source, 51 ... Exhaust opening, 53 ... Exhaust pipe, 53a ... Flange 55 ... APC valve, 57 ... exhaust device, 61 ... pressure gauge, 71 ... feed line, 73 ... matching box (MB), 75 ... high frequency power supply, 100 ... plasma etching device

Claims (16)

A processing container that accommodates an object to be processed and can hold the inside in a vacuum, and
A gas supply source for supplying a processing gas into the processing container via a gas supply path;
A flow rate adjusting device provided in the gas supply path for adjusting a supply flow rate of the processing gas;
A pressure detection device for detecting the pressure in the processing container;
An exhaust device connected to the processing vessel via an exhaust path;
An automatic pressure control valve that is provided in the exhaust passage and automatically adjusts the opening based on the pressure value detected by the pressure detection device;
An opening degree monitoring unit for monitoring the opening degree of the automatic pressure control valve;
Based on the monitoring result of the opening degree monitoring unit, a flow rate control unit for adjusting the gas flow rate supplied by the flow rate adjustment device,
A vacuum device equipped with.   2. The flow rate control unit according to claim 1, wherein the flow rate control unit controls the flow rate control device to reduce a supply flow rate of the processing gas by comparing an opening degree of the automatic pressure control valve with a predetermined threshold value. Vacuum device. Furthermore, the counter unit for counting the number of times the opening of the automatic pressure control valve exceeds the first threshold,
2. The vacuum apparatus according to claim 1, wherein the flow rate control unit controls the flow rate adjusting device so as to decrease a supply flow rate of the processing gas when the count value exceeds a second threshold value. Furthermore, an opening degree calculation unit that calculates an increase rate of the opening degree of the automatic pressure control valve within a predetermined elapsed time range,
2. The flow rate control unit according to claim 1, wherein the flow rate control unit controls the flow rate control device to decrease a supply flow rate of the processing gas when an increase rate of the opening degree exceeds a third threshold value. 3. Vacuum device.   The vacuum apparatus according to claim 1, wherein the vacuum apparatus is an etching apparatus that performs etching on an object to be processed.   The vacuum apparatus according to claim 5, wherein the object to be processed is an FPD substrate. A processing container configured to accommodate the object to be processed and to be able to hold the inside in a vacuum state;
A gas supply source for supplying a processing gas into the processing container via a gas supply path;
A flow rate adjusting device provided in the gas supply path for adjusting a supply flow rate of the processing gas;
A pressure detection device for detecting the pressure in the processing container;
An exhaust device connected to the processing vessel via an exhaust path;
An automatic pressure control valve that is provided in the exhaust passage and automatically adjusts the opening based on the pressure value detected by the pressure detection device;
A pressure control method for controlling the pressure in the processing container in a vacuum apparatus comprising:
A pressure control method for a vacuum apparatus, wherein the opening degree of the automatic pressure control valve is monitored, and based on the result, the flow rate of gas supplied by the flow rate adjusting device is adjusted.   8. The pressure control method for a vacuum apparatus according to claim 7, wherein control is performed so as to reduce the supply flow rate of the processing gas by comparing the opening of the automatic pressure control valve with a predetermined threshold value.   Counting the number of times the opening of the automatic pressure control valve exceeds the first threshold value, and reducing the supply flow rate of the processing gas when the count value exceeds the second threshold value. The pressure control method for a vacuum apparatus according to claim 7, wherein   The control is performed so as to decrease the supply flow rate of the processing gas when an increase rate of the opening degree of the automatic pressure control valve exceeds a third threshold value within a predetermined elapsed time range. The pressure control method of the vacuum apparatus as described in 2.   The pressure control method for a vacuum apparatus according to claim 7, wherein the vacuum apparatus is an etching apparatus that performs etching on an object to be processed.   The pressure control method for a vacuum apparatus according to claim 11, wherein the object to be processed is an FPD substrate. A processing container configured to accommodate the object to be processed and to be able to hold the inside in a vacuum state;
A gas supply source for supplying a processing gas into the processing container via a gas supply path;
A flow rate adjusting device provided in the gas supply path for adjusting a supply flow rate of the processing gas;
A pressure detection device for detecting the pressure in the processing container;
An exhaust device connected to the processing vessel via an exhaust path;
An automatic pressure control valve that is provided in the exhaust passage and automatically adjusts the opening based on the pressure value detected by the pressure detection device;
An etching method for etching an object to be processed using an etching apparatus comprising: an opening of the automatic pressure control valve is monitored, and a gas flow rate supplied by the flow rate adjustment device is adjusted based on the result Etching method characterized by performing.   The etching method according to claim 13, wherein the supply flow rate of the processing gas is decreased by comparing the opening of the automatic pressure control valve with a predetermined threshold value.   The number of times that the opening of the automatic pressure control valve exceeds a first threshold value is counted, and when the count value exceeds a second threshold value, the supply flow rate of the processing gas is decreased. Item 14. The etching method according to Item 13.   The control is performed so as to decrease the supply flow rate of the processing gas when an increase rate of the opening degree of the automatic pressure control valve exceeds a third threshold value within a predetermined elapsed time range. The etching method as described in 4. above.

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