JPS6377533A - Pressure change-over method for decompression treatment device - Google Patents

Abstract

PURPOSE:To shorten the time required to be converged to a set pressure by obtaining in advance the correlation between the pressure of a treatment chamber and the opening of a valve, and setting the opening of the valve to the opening shown in the correlation when the pressure of the treatment chamber is changed over. CONSTITUTION:The treatment chamber 1 is supplied with a gas to be treated while decompressed through a valve 3 by a gas discharge means 4, and the opening of the valve 3 is kept in a constant opening when the pressure of the chamber is kept in a constant pressure. And the equation showing the correlation between the pressure of the treatment chamber 1 and the opening of the valve 3 is stored in a pressure-valve opening conversion circuit 9. When the pressure of the treatment chamber 1 is to be changed over to a specified pressure, the pressure-valve opening conversion circuit 9 converts the signal from a pressure setting circuit 7 to an opening signal by the correlation equation. This signal is sent to a valve driving circuit 5a to set at a specified opening. As a result, the pressure of the treatment chamber 1 is changed to approach the set pressure and is converged to the set pressure without hunting.

Description

[Detailed Description of the Invention] [Summary] In switching the pressure of the processing chamber in a reduced pressure processing apparatus equipped with a processing chamber that is supplied with processing gas and whose pressure is reduced by exhaust means via a valve, the pressure of the processing chamber and the pressure of the valve are adjusted in advance. By determining the correlation with the opening degree and setting the opening degree of the valve to the opening degree indicated by the correlation with respect to the desired pressure, the required time can be shortened.

[Industrial application field]

The present invention relates to a method for switching the pressure of a processing chamber in a reduced-pressure processing apparatus that includes a processing chamber that is supplied with processing gas and whose pressure is reduced by exhaust means via a valve.

In the manufacture of semiconductor devices, microfabrication of wafers includes processes such as dry etching and ashing (dry resist removal), and reduced pressure processing equipment similar to the above is used for these processes.

In this reduced-pressure processing apparatus, the pressure in the processing chamber in which processing is performed usually differs between the time of processing and the time of wafer exchange, etc., and the pressure must be switched.

In order to improve throughput, it is desired to shorten the time required for this switching.

[Conventional technology]

The conventional method of switching the pressure of the decompression processing equipment described above is the third method.
As shown in the configuration diagram in the figure.

In the same figure, a processing chamber 1 in which processing is performed is supplied with a processing gas 2 at a constant flow rate and an exhaust means 4 via a valve 3.
The pressure is reduced by (for example, a vacuum pump). Valve 3 is
For example, it is a butterfly type throttle valve, which is driven by the valve drive circuit 5, and when the opening degree is large, the exhaust force is increased and the pressure in the processing chamber 1 is lowered, and when the opening degree is small, it works in the opposite way. do.

When switching the pressure in the processing chamber 1 from a certain pressure to a desired pressure, the signal from the pressure sensor 6 that detects the pressure in the processing chamber 1 is compared with the signal from the pressure setting circuit 7 that has set the desired pressure. When the pressure in the processing chamber 1 is higher than the set pressure, the valve is driven so that the opening of the valve 3 is increased, and in the opposite case, the opening of the valve 3 is decreased. Send a signal to circuit 5.

Then, the pressure in the processing chamber 1 approaches the set pressure, and finally converges to the set pressure.

Note that W in the figure is a wafer to be processed, and 1a is an entrance/exit for the wafer W.

[Problem that the invention seeks to solve]

However, in the conventional method of pressure switching, the time required to reach the convergence is as shown by the broken line in the pressure characteristic diagram of FIG. 2, although the pressure in the processing chamber 1 reaches the set pressure relatively quickly, there is an Since it takes time to reach convergence due to so-called hunting, which involves repeated up and down movements, there is a problem that the required time becomes long.

[Means for solving problems]

The above problem can be solved by determining the correlation between the pressure in the processing chamber and the opening degree of the valve in a steady state in advance, and when switching the pressure in the processing chamber from a certain pressure to the desired pressure, the opening degree of the valve must be adjusted to the desired pressure. This problem can be solved by the pressure switching method of the present invention, which sets the opening degree to the degree indicated by the correlation.

[Effect]

In the aforementioned reduced pressure processing apparatus, when the pressure in the processing chamber is maintained at a certain constant pressure, the valve is also maintained at a certain constant opening degree. Furthermore, hunting during convergence due to pressure switching occurs when the valve opening is too large or too small.

The present invention focuses on this phenomenon.

In other words, according to this method, the opening degree of the valve is set from the beginning to the opening degree commensurate with the desired pressure, regardless of the process of pressure change in the processing chamber, so hunting, which prolongs the time required for pressure switching, is eliminated. , the time required is shorter than that of conventional methods.

〔Example〕

Hereinafter, an embodiment of the pressure switching method according to the present invention will be described using the configuration diagram in FIG. 1 and the pressure characteristic diagram in FIG. 2. The same reference numerals indicate the same objects throughout the figures.

In FIG. 1, the processing chamber 1, processing gas 2, valve 3, exhaust means 4, and their mutual relationships are the same as described in FIG. 3. When the pressure in the processing chamber 1 is maintained at a certain constant pressure, the valve 3 is also maintained at a certain constant opening degree.

The valve drive circuit 5a corresponds to the valve drive circuit 5, and is capable of setting the valve 3 to a desired opening degree using a pulse motor or the like.

Further, the pressure/valve opening degree conversion circuit 9 stores an equation showing the correlation between the pressure in the processing chamber 1 and the opening degree of the valve 3 in a steady state, and converts the pressure signal to the valve opening degree based on the correlation equation. It can be converted into a signal. This correlation formula was obtained in advance from data measured separately.

When switching the pressure in the processing chamber 1 from a certain pressure to a desired pressure, the pressure/valve opening conversion circuit 9 converts the signal from the pressure setting circuit 7, which has set the desired pressure, into a valve opening signal using the above correlation formula. It is converted and sent to the valve drive circuit 5a, and the valve drive circuit 5a sets the valve 3 to a specified opening degree. By setting the opening degree of the valve 3, the pressure in the processing chamber 1 changes to approach the above set pressure and converges to the set pressure.

The convergence situation at this time is as shown by the solid line in FIG.

That is, since the valve 3 is set to the opening corresponding to the set pressure, the initial change in the pressure in the processing chamber l is slower than in the conventional method (dotted line in the figure), but the opening of the valve 3 is Since it is fixed, it converges without hunting. Therefore, the time required for convergence, that is, the time required for pressure switching, is shorter than in the conventional method.

For example, in a reactive ion etching (RIE) apparatus, the time required to switch the pressure from 1 Torr when loading a wafer W to Q, 3 Torr during processing was about 30 seconds with the conventional method, but with this method. This means that the time is reduced to about 10 seconds. and reverse switching (0,3
-I Torr), it is similarly shortened.

Since the time required for processing is about 1 minute, it can be seen that the above time reduction greatly improves throughput.

In addition, if the pressure converged using the above method does not match the set pressure, it is better to switch to the conventional method using the pressure sensor 6 and comparison circuit 8 and make fine adjustments once the pressure becomes constant. . Since the pressure changes are small, this fine adjustment can be completed in a short time without hunting, and has little effect on the time required for pressure switching.

〔Effect of the invention〕

As explained above, according to the configuration of the present invention, the time required for switching the pressure in a pressure reduction processing apparatus equipped with a processing chamber that is supplied with processing gas and reduced in pressure by an exhaust means via a valve is reduced compared to the conventional method. This has the effect of making it possible to improve the sloop and throat of the processing device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating an embodiment of the method of the present invention, FIG. 2 is a pressure characteristic diagram showing pressure changes during switching, and FIG. 3 is a block diagram explaining a conventional method. In the figure, 1 is a processing chamber, 2 is a processing gas, 3 is a valve, 4 is an exhaust means, 5.5a is a valve drive circuit, 6 is a pressure sensor, 7 is a pressure setting circuit, 8 is a comparison circuit, 9 is a pressure This is a valve opening conversion circuit. AA figure

Claims (1)

[Claims] In a depressurization processing apparatus equipped with a processing chamber which is supplied with processing gas and whose pressure is reduced by exhaust means via a valve, the correlation between the pressure of the processing chamber in a steady state and the opening degree of the valve is determined in advance, and the A pressure switching method for a reduced pressure processing apparatus, characterized in that when switching the pressure in a processing chamber from a certain pressure to a desired pressure, the opening degree of the valve is set to the opening degree indicated by the correlation with respect to the desired pressure.