JPS6369227A - Pressure controlling method and device in etching equipment - Google Patents

Abstract

PURPOSE:To maintain a process pressure inside a vacuum chamber in a plasma discharging operation so as to be a definite one, by starting discharge when the pressure inside the vacuum container attains within the range of an etching process pressure and measuring the pressure inside the vacuum container after the discharge and performing a PID control of a variable valve. CONSTITUTION:A variable valve 7 and a valve 10 are opened and a vacuum pump 11 is operated to perform vacuum exhaustion inside a vacuum container 1. When the pressure inside the container 1 attains to a definite pressure, valves 2 and 5 are opened and a flow rate controller 3 is controlled to supply a proper quantity of process gas into the container 1 from a process gas supplying source. Discharge is generated inside the container 1 by the use of a high-frequency power source 13. The pressure inside the container 1 is made feedback and PID control is performed inside a controller 15 to adjust an opening degree of a valve 7. If the pressure inside the container 1 is in the allowable range, the opening degree of the valve 7 is memorized. Hence, the process pressure inside the container 1 is maintained to be a definite one.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a pressure control method and apparatus for an etching apparatus, and more particularly to a pressure control method and apparatus for an etching apparatus suitable for processing using plasma. It is.

[Conventional technology]

In the conventional pressure control method, as described in Japanese Patent Application Laid-Open No. 61-54627, a processing gas is introduced into a vacuum chamber that is evacuated to a predetermined pressure, and when the introduced processing gas is caused to discharge into plasma, the plasma discharge Taking into account the pressure increase at the start, plasma discharge is started at a lower pressure than the predetermined processing pressure, and the processing pressure in the vacuum vessel is adjusted so that the increased pressure is approximately the processing pressure. The time required from the start of introduction of a processing gas into a vacuum vessel evacuated to a predetermined pressure until the start of discharge is shortened, thereby improving throughput.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the point of controlling the pressure to quickly converge to a predetermined processing pressure, and the pressure that rises when the processing gas is plasma discharged is almost equal to the predetermined processing pressure. Therefore, there is a problem that the difference from the predetermined processing pressure is small, and it is difficult to converge the pressure for feedback control.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure control method and apparatus for an etching apparatus that can quickly maintain the processing pressure in a vacuum chamber at a predetermined pressure during plasma discharge.

[Means for solving problems]

The above purpose is to control the pressure control device of an etching apparatus that uses plasma to etch a sample in a vacuum chamber, and to control the exhaust system valve and vacuum pump connected to the vacuum chamber, and the processing gas supply connected to the vacuum chamber. A digital output means sends an operating signal to the valves in the system, a pulse output means sends an M signal to adjust the opening of the variable valve in the exhaust system, and a pressure value measured by a vacuum gauge installed in the vacuum vessel is input. an analog input means, an analog output means for sending a signal for adjusting the flow rate of a flow rate controller of the processing gas supply system and a signal for activating a high frequency power source connected to the vacuum container;
It has a storage means for storing the opening degree of the variable valve before the end of the previous etching process, a pressure control procedure storage means for storing the pressure adjustment procedure, and a central processing unit for controlling these input/output means and the storage means. When the pressure inside the vacuum container is reduced to a predetermined pressure, the processing gas is supplied into the vacuum container, and when the predetermined etching processing pressure is reached, the variable valve is adjusted to the opening position before the end of the previous etching processing. This is achieved by setting and matching the initial opening degree based on , starting discharge within the vacuum chamber, and adjusting the pressure within the vacuum chamber after discharge to a predetermined etching pressure by controlling PID using a variable valve.

[Function] In accordance with the pressure control means recorded in the pressure control procedure storage means, the central processing bag r'''C is centrally controlled,
The pressure value inside the vacuum container is input to the analog input means, and a signal is sent from the digital output means to the vacuum pump and the valve of the exhaust system, so that the pressure inside the vacuum container reaches a predetermined pressure 6.
When the pressure has been evacuated, signals are sent from the digital output means and the analog output means to the valves and flow control valves of the processing gas supply system to supply the processing gas into the vacuum vessel,
When the predetermined etching process pressure is reached, a signal to adjust the variable valve in the exhaust system is sent from the pulse output stage, the variable valve is adjusted to the opening degree before the end of the 111th etching process, and a high frequency power source is applied from the analog output means. Send a signal to operate, start discharge in the vacuum container, send an adjustment signal for the variable valve from the pulse output means, and adjust the variable valve 1)
By controlling the pressure in the vacuum chamber after discharge to a predetermined etching pressure through ID control, the processing pressure in the vacuum chamber during plasma discharge can be easily maintained at a predetermined pressure.

〔Example〕

Hereinafter, a practical example of the present invention will be explained from FIG. 1 to the third factor.

FIG. 1 shows a block diagram of the pressure control device. Vacuum container 1
On one side is valve 2. A processing gas supply source 6 is connected to the flow rate controller through a 3° valve 5 in this order, and a vacuum pump 11 is connected to the other side through a variable valve 7 and a valve 10. Further, a vacuum gauge 12 is attached to the vacuum vessel 1, and a high frequency power source is connected thereto.

The control device 15 also sends an analog output means 18 to the central processing bag Wt16. Analog input means 19. An input/output device 17 consisting of a pulse output means (S) and a digital output means (M) is connected to a storage device (N) consisting of a pressure control procedure storage means (T) and a storage means (S).

The analog output means 18 is connected to the flow M controller 3 through four LT quantity sub-controllers, and the high frequency power supply controller 14.
is connected to the high-frequency power supply controller 13 through the converter, which converts the command signal of the central processing unit 16 into an analog signal and sends it to the flow rate controller 4 or the high-frequency power controller 1.
4 to operate and control the flow rate controller 3 or the high frequency power source 13.

The analog input means 19 is connected to the vacuum gauge 12 and converts the analog quantity detected by the vacuum gauge 12 into a digital quantity, and is, for example, an analog input board.

The pulse output means is connected to a pulse motor 8 via a pressure control valve controller 9, and the pulse motor 8 is connected to a variable valve 7. The command signal of the central fi4'u processor 1R16 is converted into a pulse signal and sent to the pressure control valve controller 9I, which drives and controls the pulse motor 8 to adjust the variable valve 7.

The digital output means 4 is a valve 2 of the processing gas supply system.
．． It is connected to the valve 5, the exhaust system valve 10, and the vacuum pump 11, respectively, and converts it into a digital signal such as a command signal for the central processing unit 16, and sends the valve 2, valve 5, . A signal is sent to the valve 10 or the vacuum pump 11 to operate the valve 10 or the vacuum pump 11, respectively.

The pressure control procedure storage means stores a procedure for controlling the pressure inside the vacuum container 1 to a predetermined pressure, for example, RO.
M (Read 0nly Memory) Te3)
Le.

The storage means sae stores the opening degree of the variable valve when the inside of the vacuum container i is maintained at a predetermined processing pressure during the previous pressure control.
Access Memory).

With the above configuration, the operation will be explained according to the procedure stored in the pressure control procedure storage means. The procedure is shown in Fig. 2, and the pressure state is shown in Fig. 3.

First, the variable valve 7 and the valve IO are opened, and the vacuum pump 11 is operated to evacuate the inside of the vacuum container 1 (this is shown in step 31).

Next, the pressure inside the vacuum container l is set to a predetermined pressure Po (Fig. 3<
When reaching point A) shown in a>, valve 2 and valve 5 are
is opened, and the flow rate controller 3 is controlled to supply an appropriate amount of processing gas from the processing gas supply source into the vacuum vessel 1 (this is shown in step 32).

Next, it is determined whether the pressure within the vacuum vessel l to which the processing gas is supplied has reached the allowable pressure range ΔP of the predetermined etching processing pressure Pl (this is shown in step 33).
.

Next, when the pressure inside the vacuum container i reaches a predetermined etching pressure (point B shown in FIG. 3(a)), the initial opening of the variable valve 7 is adjusted to the opening degree v1 that was memorized during the previous etching process. The variable valve 7 is set to the opening degree v2, which is a value obtained by multiplying the degree coefficient K (1≦≦1.1) (this is shown in step 34).

Next, the high-frequency power source 13 generates a discharge in the vacuum vessel l (this is shown in step 35i).

When the discharge starts, the pressure inside the vacuum vessel l suddenly increases to P2(
The temperature rises to point C shown in FIG. 3(a). At this time,
As shown in FIG. 3(b), by keeping the opening degree of the variable valve 7 open to v2, the pressure increase in the vacuum container 1 is suppressed to P2, and the pressure is prevented from increasing unnecessarily.

Next, the pressure inside the vacuum container 1 is fed back to perform PID control in the controller 5i15 to adjust the opening degree of the variable valve 70 (this is shown in step 36).

Next, it is determined whether the pressure within the vacuum container 1 approaches a predetermined etching process pressure Pl and is within the allowable range ΔP by PID control (this is shown in step 37).

Next, if the pressure inside the vacuum container l is within the permissible range, the current opening degree of the variable valve 7 is memorized (this is shown in step 38). New data is stored one after another as time passes, and data obtained by averaging four neighboring points is stored.

Next, the end point of etching is detected by an end point determining device not described in this embodiment, and it is determined whether or not the discharge continues (this is shown in step 39). variable valve 7
The opening degree at the end of etching is stored as the final value.

It is then determined whether there is a next step or not (this is shown in step 40).

FIG. 3 shows the relationship between the internal pressure of the vacuum vessel, the variable valve opening degree, and time when pressure control is performed according to the above procedure. Processing gas is supplied from point A, where the pressure inside the vacuum container 1 becomes Po, and when it reaches point B, the variable valve opening is opened by v2I to start discharging, and the pressure rises to point C, P2. Then, the predetermined pressure P! is controlled by PID control. can be approached.

In this case, since the initial opening degree of the variable valve 7 is set to ■2, the pressure increase can be suppressed to P2, and the predetermined pressure range Pl±
The time T2 to enter ΔP becomes faster.

As described above, according to this embodiment, pressure control is performed by a control device that stores pressure control procedures, and when a predetermined processing pressure is reached, an initial opening is given to the variable valve to start discharging. , because the pressure rise is suppressed and a clear pressure difference appears.

Pressure control using PID control is easy, and the pressure can be quickly maintained within a predetermined processing pressure range.

〔Effect of the invention〕

As described above, according to the present invention, the processing pressure in the vacuum chamber during plasma discharge can be quickly maintained at a predetermined pressure.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the pressure control device of the etching apparatus of the present invention, Fig. 2 is a flowchart showing a pressure control method, and Fig. 3 is a diagram showing the relationship between the pressure state in the vacuum container and time and the variable FIG. 3 is a diagram showing the relationship between valve opening degree and time. 1...Vacuum container, 2,5.10...Valve, 3...Flow rate controller, 7...Variable valve, 11...Vacuum pump , 12... Vacuum gauge, 13... High frequency power supply, 16... Central processing unit, 18... Analog output means,
19...Analog input means, addition...Pulse output means, 4...Digital output means, Z...
Pressure control procedure storage means, memory means 'Kl' Figure 11-1 F pump. Figure 3 14f

Claims (1)

[Claims] 1. In a pressure control method for an etching apparatus that etches a sample using plasma in a vacuum container, after starting to introduce a processing gas into the vacuum container which has been evacuated to a predetermined pressure, When the pressure inside the vacuum container reaches the predetermined etching process pressure range, the variable valve in the exhaust system is set to the initial opening based on the opening before the end of the previous etching process, and discharge is started. A pressure control method for an etching apparatus, characterized in that the pressure inside the vacuum container is subsequently measured, and the variable valve is controlled by PID to adjust the pressure to a predetermined etching process pressure. 2. In a pressure control device for an etching apparatus that etches a sample using plasma in a vacuum container, an exhaust system valve and a vacuum pump connected to the vacuum container, and a processing gas supply connected to the vacuum container. digital output means for sending an operating signal to a valve in the exhaust system; pulse output means for sending a signal to adjust the opening degree of the variable valve in the exhaust system; and inputting a pressure value measured by a vacuum gauge provided in the vacuum vessel. an analog input means; an analog output means for sending a signal for adjusting the flow rate of a flow rate controller of the processing gas supply system and a signal for activating a high frequency power source connected to the vacuum container; and a previous etching of the variable valve. a storage means for storing the opening degree before the end of the process; and when the pressure inside the vacuum vessel is reduced to a predetermined pressure, a processing gas is supplied into the vacuum vessel, and when the predetermined etching process pressure is reached; Then, the initial opening degree of the variable valve is set and adjusted based on the opening degree before the end of the previous etching process, discharge is started in the vacuum container, and the variable valve is controlled by PID to maintain the vacuum after the discharge. Pressure control procedure storage means storing a procedure for adjusting the pressure inside the container to a predetermined etching pressure; and the digital output means, the pulse output means, the analog input means, the analog output means, and the pressure control procedure storage means. A pressure control device for an etching apparatus, comprising: a central processing unit for controlling the pressure; and a central processing unit for controlling the pressure.