JPS6063387A - Plasma treating device - Google Patents

Abstract

PURPOSE:To improve the plasma treating rate for articles and to increase productivity by forming preliminary chambers for housing temporarily the articles before and after treatment to the inside volume smaller by a specific ratio than the inside volume of an etching chamber in which the articles are plasma-treated. CONSTITUTION:A wafer-shaped sample in a cassette 1 is housed in a preliminary chamber 3 and the inside of the chamber is thoroughly evacuated. The sample is conveyed into an etching treatment chamber 9 which is thoroughly and preliminarily evacuated. Glow discharge plasma is generated in said chamber and the sample is etching-treated. The sample is then conveyed into a thoroughly evacuated preliminary chamber 21 and thereafter the atm. pressure is restored in the chamber 21 and the sample is taken out of said chamber. The inside volume of the chambers 3, 21 with the device which performs continuously the above-mentioned operation is made <=1/20 the inside volume of the chamber 9. The pressure in the chamber 9 is thus maintained satisfactorily constant by supplying continuously the reactive gas to be used for the plasma treatment even during the exchange of the sample, by which the time for evacuation, the time for regulating the pressure, etc. required in the stage of exchanging the sample are omitted and the reproducibility of the treatment is maintained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a plasma processing apparatus and processing method for processing such as plasma etching and plasma chemical deposition. The present invention relates to a plasma processing apparatus and method suitable for.

[Background of the invention]

In recent years, surface treatment techniques such as dry etching using glow discharge plasma have been widely used in the semiconductor device manufacturing industry. This method utilizes the chemical reactivity and physical energy of chemically active radicals and ions generated in low-pressure gas plasma to etch the surface of a solid sample and deposit substances on the surface. . A conventional plasma processing apparatus and method will be explained using dry etching as an example.

FIG. 1 is a conceptual diagram of an etching apparatus equipped with an etching processing chamber and a preliminary chamber for temporarily storing a sample i to be processed. The wafer-shaped sample stored in the cassette 1 is
is opened and placed in the preliminary chamber 3 by the conveying device 4, the pulp 2 is closed, the pulp 6 is opened, and the inside of the preliminary chamber 3 is sufficiently evacuated by the vacuum pump 7. The pulp 8 is opened and the sample 5 is transported by the transport device 4 onto the etching tape /1/10 which also serves as a high frequency electrode in the etching processing chamber 9 which is sufficiently evacuated by the damp vacuum pump 18 . Close pulp 8,
CF4. A nohalogenide gas such as SFa, BCts, etc. is supplied from a gas source 13 to an etching chamber 9 by a mass flow controller 14 at a constant flow rate and evacuated by a vacuum pump 18. At this time, the exhaust conductance is adjusted by the variable orifice 16 to keep the pressure inside the etching chamber 9 constant at a predetermined pressure of about 10 Pa. After that, high-frequency power is supplied to the high-frequency electrode 10 by the high-frequency power source 12 to generate glow discharge plasma, and the sample 1
The etching process of step 1 is started. By continuously monitoring the plasma emission spectrum with a spectrometer,
When the end of etching is observed, the supply of the extra frequency force is stopped to stop the generation of plasma, the pulp 15 is closed and the supply of the reaction gas is stopped, and the inside of the etching chamber 9 is fully vacuumed by the vacuum bonder 18. Exhaust. Pulp 22f: The pulp 19 is opened and the sample 11 is transported by the transport device 20 into the preliminary chamber 21 which has been opened and sufficiently evacuated by the vacuum pump 7.

After closing the pulp 19, nitrogen or atmospheric pressure is pumped into the preliminary chamber 21, and when the pressure in the preliminary chamber 21 reaches atmospheric pressure, the pulp 23 is opened and the sample is transferred to the transfer device 20 to store the processed sample. It is stored in the cassette 24. The second sample is carried into the etching chamber 9 immediately after the sample that has been etched in the above process is carried out from the etching chamber to the preliminary chamber.

In order to perform etching treatment on a large number of samples, the above-described process is repeated, but the conventional treatment methods described above have a major obstacle in increasing the processing speed and productivity. That is, in the above method, for each etching process, the etching reaction gas is supplied to the etching chamber,
- Exhaust and high frequency power supply ff: Must be intermittent.

In this case, in addition to the time required for intermittent operation, it often takes several tens of seconds to control the pressure to a constant level after the gas supply starts, and furthermore, when high-frequency discharge is used, it takes a long time until the discharge reaches a steady state. simulates υ tens of seconds. If the time required for the etching process is 1 to 2 minutes, the ratio of these times to the time required for the entire process can be ignored.
This becomes a factor that impairs the productivity of the equipment. Furthermore, when the discharge is completely intermittent as described above, it takes several tens of seconds for the plasma to reach a stable state after the start of the discharge, so the progress of etching during this period varies from time to time, and the etching process ends before the etching ends. If the time required to reach this point is as short as 1 to 2 minutes, the reproducibility of the etching time will be impaired.

[Purpose of the invention]

The purpose of the present invention is to provide a plasma processing apparatus and method that can eliminate the A'AF exhaust time, pressure adjustment time, etc. that are necessary for sample exchange, and to
It is an object of the present invention to provide a plasma processing apparatus and method that can overcome the lack of reproducibility of plasma processing due to instability in the initial stage of plasma generation.

[Summary of the invention]

In order to solve the above-mentioned problems with current plasma processing equipment, the present invention can continuously supply the reactive gas used for plasma processing even while the sample to be processed is being replaced, and can maintain the pressure inside the processing chamber at a sufficiently constant level. The interior volume of the preparatory chamber is sufficiently small compared to the internal volume of the pretreatment chamber. For example, the y-product of the preliminary chamber is 1t for the volume of the processing chamber 201 (that is, the internal volume of the preliminary chamber is 1/1 of the internal volume of the processing chamber.
20 or less), the pressure of the reaction gas in the processing chamber is 20P
In the case of a, the preliminary chamber must be fully opened before replacing the sample.
．． If the gas is evacuated to below IPa, even if the valve separating the processing chamber and preliminary chamber is opened for sample exchange, the gas pressure in the processing chamber will only drop from 20 Pa to about 19 pa.

Normally, in processes such as plasma etching and plasma CVD, pressure changes of this magnitude do not cause large changes in the etching characteristics such as etching rate or the quality of the film deposited by plasma CVD. Therefore, no time is required for pressure adjustment during sample exchange, and discharge can be started immediately after sample exchange to generate plasma and plasma processing can be started.

Juku et al. explained that if the pressure change during sample exchange is small enough, it is possible to convert the sample while maintaining the discharge plasma. It is possible to avoid the point where a transient state continues until a stable plasma is reached for several seconds, and it is possible to ensure the stability of plasma processing. One of the reasons why the plasma state is unstable for several tens of seconds after the start of discharge, as described above, is that the residual gas adsorbed on the inner wall surface of the processing chamber when no discharge is in progress is caused by active particles in the plasma after the start of discharge. This is because it is emitted into the plasma as it is incident on the inner wall surface. Therefore, the composition of the gas in the plasma will gradually change as the adsorbed gas is released from the wall surface after the discharge starts, and to prevent this, it is necessary to continue the discharge even when replacing the sample as described above. is desirable.

[Embodiments of the invention]

The sixth aspect will be explained in detail below with reference to examples.

Embodiment FIG. 1V In the plasma etching surface shown in the configuration shown in FIG.
A 9T device was constructed and used to plasma etch 35 Q nm thick polycrystalline silicon deposited on a silicon substrate. Sulfur hexafluoride SF6 is supplied as a reaction gas for etching to the processing chamber 9 at a flow rate of 50 m1/H, and is evacuated using a mechanical booster bong and an oil rotary Makabe pump to maintain the SFa pressure in the processing chamber at 15 PH. A high frequency power of 13.56 M1 (z) was supplied to the electrode 10 to generate plasma and etching the polycrystalline silicon. Etching was completed in about 60 seconds, but continued for 20 seconds. Etching was performed and the discharge was stopped, valve 19 was opened and the sample was transferred to the preparatory chamber 21, and at the same time, valve 8 was opened to transfer the next sample from the preparatory chamber 3 to the processing chamber 9, and valve 8.19 was closed. @The discharge was immediately restarted to perform the etching process on the next sample.The time allowed for sample exchange was only 15 seconds, and the change in gas pressure in the processing chamber during sample exchange was 4% at maximum. For this, as in the conventional method, when the discharge is stopped after etching, the supply of SFg is stopped and the gas is temporarily evacuated to 8 Fs' remaining in the processing chamber, and then the sample is replaced and the supply of SFg is restarted. When the pressure was adjusted and the discharge was restarted, the time required to replace the sample was 95 seconds.

In the above example, a plasma etching apparatus is described in which a preliminary chamber for storing a processed sample and a preliminary chamber for storing a sample to be processed next are arranged on each side of the processing chamber. As mentioned above, it is of course possible to adopt a device configuration in which one preparatory room serves both roles.

〔Effect of the invention〕

As explained above, according to the uninvented plasma processing apparatus and method, plasma etching, plasma CVD
In plasma processing such as this, it is possible to achieve highly physiological plasma processing by saving time such as adjusting the pressure of the reaction gas, and because plasma discharge can be continued even during sample exchange.
This has the advantage that the sample can be prevented from being exposed to an unstable plasma state at the start of discharge, and the reproducibility of plasma processing can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a plasma etching apparatus. 1.24...Wafer cassette, 2, 8, 19°23
...Pulp, 3.21...Preliminary room, 4.20...
Wafer transfer device, 5.11... wafer, 6,15
゜17.22...Pulp, 7.18...Exhaust pump, 9...Etching processing chamber, 10...^Frequency electrode,
12... High frequency power supply, 13... Gas source (gas cylinder), 14... Mass 70-controller, 16... Variable orifice. Figure/Figure

Claims (1)

[Claims] 1. Surface treatment of an article in a plasma processing apparatus that etches the surface of the article in gaseous glow discharge plasma or deposits a film on the surface of the article. It is equipped with a processing chamber that generates plasma to be processed, and a preliminary chamber that can be evacuated to temporarily accommodate articles to be processed next and articles that have been processed, and the internal volume of the preliminary chamber is one of the internal volume of the processing chamber. A plasma processing apparatus characterized in that: /20 or less. Z % In the plasma processing apparatus according to claim 1, an article whose surface has been surface-treated is carried out from the processing chamber to the preliminary chamber, and an article to be subsequently processed is carried from the preliminary chamber into the treatment chamber. 1. A plasma processing apparatus characterized in that the same gas as during processing can be supplied to the processing chamber at the same flow rate even during exchange. 3. Scope of permissible requirements In the plasma processing apparatus according to item 1 or 2, both while the surface treatment of the article is progressing in the treatment chamber and when replacing the article after the treatment, A plasma processing apparatus characterized in that it is configured to continuously supply gas to a processing chamber at a constant flow rate and to sustain discharge at a constant high frequency power. 4.% Permissible In the plasma processing apparatus according to any one of claims 1 to 3, before exchanging an article for which processing has been completed and an article to be subsequently processed in the processing chamber, The gas pressure during plasma processing in the processing chamber is 5P.
A plasma processing apparatus characterized in that it is configured to be able to perform more than a.