JPH0518252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ashing method, and particularly to an ashing method suitable for ashing photoresist of a processed sample.

[Background of the invention]

When a sample such as a semiconductor substrate is subjected to a plasma etching process, for example, a photoresist is baked onto the surface of the sample to be processed. This photoresist is unnecessary after processing the sample and must be removed from the surface of the sample to be processed.

removing the photoresist from such samples,
In other words, as a method of ashing, for example, as shown in Japanese Patent Publication No. 54-24697, oxygen gas is turned into plasma, and the active oxygen atoms present in the oxygen gas plasma react with the photoresist to decompose the photoresist. A method is known in which photoresist is ashed by vaporization.

However, this method does not recognize the problem of increasing the speed of ashing photoresist (hereinafter abbreviated as ashing speed).

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ashing method that increases the reaction rate between active gas atoms in gas plasma and photoresist, improves the ashing speed, and uniformly ashes photoresist.

[Summary of the invention]

The present invention heats a gas, introduces the heated gas into a reaction chamber to turn it into plasma, and uses the gas plasma to ashe the photoresist in the reaction chamber, thereby combining active gas atoms in the gas plasma and photoresist. This makes it possible to increase the ashes speed by increasing the reaction rate with the plasma, and also to equalize the temperature of the introduced gas and plasma, thereby making it possible to ashe the photoresist uniformly.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings.

In the drawing, on the outside of the reaction chamber 10, in this case:
An electrode 20 and another electrode 21 are provided. A power source, for example, a high frequency power source 30 is connected to the electrode 20, and the other electrode 21 is grounded. In this case, at the bottom of the reaction chamber 10, a gas exhaust system 43 composed of, for example, a variable conductance valve 40, a gas cooling device 41, and a vacuum exhaust device 42 is connected in communication with the inside of the reaction chamber 10. . In this case, at the top of the reaction chamber 10, for example, a gas heating device 50, a gas flow rate control device 51, and a gas source 52 are installed.
A gas supply system 53 configured with the following is connected in communication with the inside of the reaction chamber 10. Note that as the gas heating device 50, a device having a heating element such as a heater or an indirect heat exchanger type device is used.

In the drawing, a jig 70 to which a plurality of processed samples 60 having photoresist on the surface to be processed are attached with the surface to be processed as a vertical plane is carried into the reaction chamber 10 in this state and installed. After that, reaction chamber 1
0 is hermetically sealed and variable conductance valve 4
By opening 0 and operating the vacuum evacuation device 42, the pressure is reduced to a predetermined pressure. Thereafter, the flow rate from the gas source 52 is controlled to a predetermined flow rate by the flow rate control device 51, and the gas heating device 50 is heated to a temperature of at most 200.
A gas, for example, oxygen gas, heated to about
By discharging air at a predetermined amount, the inside of the reaction chamber 10 is regulated and maintained at a predetermined reaction pressure, for example, 0.5 to 10 Torr. In this state, by applying high frequency power from the high frequency power supply 30 to the electrode 20, the oxygen gas in the reaction chamber 10 is turned into plasma. A reaction occurs between the active oxygen atoms in this oxygen gas plasma and the photoresist on the surface to be processed of the sample 60, and the photoresist is decomposed, vaporized, and ashed. In this case, since the oxygen gas is heated, active oxygen atoms in the oxygen gas plasma react actively with the photoresist, thereby improving the ashing rate. Note that in order to prevent deterioration of the exhaust performance of the vacuum exhaust device 42, the gas exhausted from the reaction chamber 10 is cooled by a gas cooling device 41.

The following effects can be obtained by the assuring method as in this embodiment.

(1) The active oxygen atoms in the oxygen gas plasma actively react with the photoresist, which improves the ashing speed. By heating the oxygen gas at
When heated to 200°C, the ashes speed was approximately doubled compared to conventional methods.

(2) By supplying heated oxygen gas to the reaction chamber, it is possible to equalize the temperature of the oxygen gas supplied to the reaction chamber and the oxygen gas turned into plasma, and the photoresist can be ashed uniformly. I can do it.

(3) By increasing the ashing speed, throughput in semiconductor device manufacturing can be improved.

Note that although oxygen gas is used as the gas in this embodiment, the same effect can be obtained by using a mixed gas of oxygen gas and CF ₄ . In addition, the temperature of the gas discharged from the reaction chamber is 250℃.
Because of the relatively high temperature, this gas may be used to heat the gas supplied to the reaction chamber without immediately cooling it as in this embodiment. In this case, the thermal energy contained in the gas discharged from the reaction chamber can be effectively used, and the burden on the gas cooling device can be reduced.

〔Effect of the invention〕

According to the present invention, a heated gas is introduced into a reaction chamber and turned into plasma, and the photoresist is ashed in the reaction chamber by the gas plasma, thereby causing a reaction between active gas atoms in the gas plasma and the photoresist. This has the effect that the ashes can be activated and the ashes speed can be improved, and the temperatures of the introduced gas and plasma can be made uniform, so that the photoresist can be ashed uniformly.

[Brief explanation of the drawing]

The drawing is a configuration diagram of an asshearing device embodying the present invention. DESCRIPTION OF SYMBOLS 10... Reaction chamber, 20... Electrode, 21... Other electrodes, 43... Gas exhaust system, 50... Gas heating device, 53... Gas supply system.

Claims (1)

[Claims] 1. An ashing method characterized by heating a gas, introducing the heated gas into a reaction chamber to turn it into plasma, and using the gas plasma to ash photoresist in the reaction chamber.