JPH06266446A - Pressure controller for vacuum chamber - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the responsiveness of pressure control and shorten the stabilization time by controlling the pressure in the vacuum chamber. A vacuum chamber 1, a gas supply unit 2 connected to the vacuum chamber, an exhaust line 3 connected to the vacuum chamber and having a variable capacity valve 4, and a pressure detector 7 for detecting the pressure in the vacuum chamber. And a pressure controller 5 for controlling the opening of the variable capacity valve by comparing the detected pressure from the pressure detector with a target pressure value 6, and a means for fully closing the variable capacity valve. When the pressure is increased from the vacuum state to the target pressure 6, first, the variable capacity valve is closed regardless of the pressure in the vacuum chamber, the pressure in the vacuum chamber is increased, and then, when the pressure in the vacuum chamber reaches the predetermined pressure 11, Feedback control is performed by the pressure controller to bring the vacuum chamber to a target pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control device for a vacuum chamber, particularly a plasma etching device, a low pressure CVD device, etc.
The present invention relates to a pressure control device for a vacuum chamber of a semiconductor manufacturing apparatus that produces semiconductor devices, when the pressure in the vacuum chamber is reduced or increased.

[0002]

2. Description of the Related Art Pressure control in a vacuum chamber is one of the techniques widely used in semiconductor manufacturing equipment, and particularly in plasma etching equipment, low pressure CVD equipment, etc., which has a vacuum processing compartment and mass-produces semiconductor devices. This is an indispensable technology for equipment that performs In recent years, as the demand for automation further increases, there is a demand for a pressure control device for a vacuum chamber that can control at high speed and can be applied to a wide pressure range.

A conventional pressure control device for a vacuum chamber will be described with reference to FIG.

The vacuum chamber 1 has a gas supply section 2 and an exhaust line 3
Is connected, and a variable capacity valve 4 is provided midway in the pipeline of the exhaust line 3. The opening of the variable capacity valve 4 is adjusted by a pressure controller 5, and a target pressure value 6 is set and input to the pressure controller 5 and a pressure detection valve provided in the vacuum chamber 1 is detected. The pressure detection value from the device 7 is input.

The conventional vacuum chamber pressure control device has the above-described structure and performs proportional control (PID).

First, the vacuum chamber 1 is evacuated by the exhaust line 3, and then the reaction gas is introduced from the vacuum chamber 1. The variable capacity valve 4 starts from the fully opened state, and when the pressure in the vacuum chamber 1 increases due to the introduction of the reaction gas, this pressure is detected by the pressure detector 7 and input to the pressure controller 5. The pressure controller 5 obtains the deviation between the signal from the pressure detector 7 and the pressure target value 6, calculates the target valve opening with the deviation and a preset PID constant, and opens the target valve opening. The valve drive signal corresponding to the degree is output to the variable capacity valve 4, and the opening degree of the variable capacity valve 4 is decreased. Furthermore, the variable capacity valve 4
The degree of opening is fed back to the pressure controller 5 and closed loop control is performed.

FIG. 4 shows the relationship between the pressure value in the vacuum chamber 1 and the opening of the variable capacity valve 4 by this pressure control.

As can be seen from FIG. 4, in the PID control, the variable displacement valve 4 is controlled in the fully closing direction until the detected pressure exceeds the target pressure value 6 and completely closed, after which the variable displacement valve 4 is opened in the opening direction. The opening is adjusted in response to the control and the detected pressure value repeatedly increasing and decreasing with respect to the target pressure value 6.
Eventually, the pressure value will converge.

[0009]

The above-mentioned conventional pressure control device for the vacuum chamber performs feedback loop control based on the PID constant. However, when the opening speed and the response speed differ depending on the set PID constant, the PID constant is not appropriate. ,
When the operating conditions are changed, a hunting phenomenon, an inconsistent state such as undershoot occurs, and it takes a long time to achieve stable control. In semiconductor manufacturing equipment, especially in single-wafer processing type semiconductor manufacturing equipment, pressure responsiveness and the time until stable control greatly affect productivity, so pressure control responsiveness and shortening of stabilization time are major problems. There is.

In view of the above situation, the present invention is intended to improve the responsiveness of pressure control and shorten the stabilization time.

[0011]

According to the present invention, there is provided a vacuum chamber, a gas supply unit connected to the vacuum chamber, an exhaust line connected to the vacuum chamber and having a variable capacity valve, and a pressure in the vacuum chamber. A pressure detector for detecting, a pressure controller for controlling the opening of the variable capacity valve by comparing the detected pressure from the pressure detector with a target pressure value, and means for fully closing the variable capacity valve. The pressure controller controls the opening / closing of the variable capacity valve when the pressure detected by the pressure detector reaches a predetermined pressure.

[0012]

When the pressure in the vacuum chamber is raised from the vacuum state to the target pressure, the variable capacity valve is first closed regardless of the pressure in the vacuum chamber to raise the pressure in the vacuum chamber, and then the pressure in the vacuum chamber becomes a predetermined pressure. By the way, feedback control is performed by the pressure controller to bring the vacuum chamber to a target pressure.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment shown in FIG. 1, the same parts as those shown in FIG. 2 are designated by the same reference numerals.

A pressure detector 7 for detecting the pressure in the vacuum chamber 1 is connected to a comparator 8 and is also connected to the pressure controller 5 via the comparator 8. Control changeover switch 9 for the comparator 8
A variable capacity valve 4 is connected to the comparator 8, and a high-level computer 10 is connected to the comparator 8. The host computer 10 inputs the comparison reference value 11 for setting the switching timing of the control changeover switch 9 to the comparator 8.

The operation will be described below.

The pressure control is started when the vacuum chamber 1 is in a vacuum state, and when the pressure control is started, the state of the control changeover switch 9 is such that the valve drive signal from the comparator 8 is input to the variable capacity valve 4. ing.

The valve drive signal from the comparator 8 fully closes the variable capacity valve 4 at the same time when the pressure control is started. This full closing speed is controlled by the variable capacity valve 4 regardless of the response of the control system.
Closes at its maximum rate. When the variable capacity valve 4 is fully closed, the pressure in the vacuum chamber 1 rapidly rises, and the pressure detector 7 inputs the pressure in the vacuum chamber 1 to the comparator 8. The comparator 8 compares the detected pressure from the pressure detector 7 with the comparison reference value 11, and when the detected pressure reaches the comparison reference value 11, issues a changeover signal 12 to the control changeover switch 9 to change the pressure. The control changeover switch 9 is switched so that the signal from the target value 6 is input to the variable capacity valve 4. By this switching, the PID by the pressure controller 5
Control is started.

That is, the pressure detected from the pressure detector 7 is input to the pressure controller 5 via the comparator 8, and the pressure controller 5 detects the pressure by comparing the detected pressure value with the target pressure value 6. The opening of the variable capacity valve 4 is adjusted so that the pressure becomes the target pressure value 6.

FIG. 2 shows the state of pressure control of this embodiment.
The curve shown by the solid line in FIG. 2 shows the pressure control state of this embodiment, and the curve shown by the broken line shows the conventional pressure control state shown in FIG.

As is clear from the comparison with the prior art, the time until pressure stabilization is greatly shortened.

The comparison reference value 11 at which the control changeover switch 9 performs the switching operation can be appropriately selected by the host computer 10. Further, the control changeover switch 9 may be composed of an electronic circuit, may be made to perform switching operation by a semiconductor element such as a transistor, or the function of the control changeover switch 9 may be incorporated in the pressure controller 5. Needless to say, various changes can be made without departing from the scope of the present invention.

[0023]

As described above, according to the present invention, it is possible to greatly reduce the time until the pressure stabilizes, and to exert an excellent effect of contributing to the improvement of productivity.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing the operation of the embodiment.

FIG. 3 is a block diagram showing a conventional example.

FIG. 4 is a diagram showing an operation of the conventional example.

[Explanation of symbols]

 1 vacuum chamber 2 gas supply part 3 exhaust line 4 variable capacity valve 5 pressure controller 6 target pressure value 7 pressure detector 8 comparator 9 control changeover switch 10 host computer 11 comparison reference value 12 changeover signal

Claims (1)

[Claims] 1. A vacuum chamber, a gas supply unit connected to the vacuum chamber, an exhaust line having a variable capacity valve connected to the vacuum chamber, a pressure detector for detecting the pressure in the vacuum chamber, A pressure controller for controlling the opening of the variable capacity valve by comparing the detected pressure from the pressure detector with a target pressure value; and a means for fully closing the variable capacity valve. A pressure control device for a vacuum chamber, wherein the pressure controller controls opening and closing of the variable capacity valve when the pressure reaches a predetermined pressure.