JPH04291719A - Wafer processing end determining method - Google Patents

Abstract

PURPOSE:To determine a processing end with good reproducibility by deciding the wafer processing end depending on the value of gas component which changes with time after the gas is exhausted from the processing chamber. CONSTITUTION:A wafer is set within a processing chamber 1 and the processing gas is supplied through a pipe 4. The processing gas supplied is held at the predetermined pressure with a vacuum evacuation pump 2. The wafer is processed by the processing gas which has been changed to the gas plsma by a high frequency power and the reaction gas and non-reaction gas are exhausted through a pipe 5. The reaction gas exhausted from the vacuum evacuation pump 2 is exhausted through a pipe 6. In this case, the interior of pipe 6 is set almost to the atmospheric pressure. Therefore, the reaction gas is fetched from the pipe 6 through the pipe 7 and aging values of gas component are recorded with a gas chromatograph 3. From this aging values, the wafer processing end time can be decided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the end point of wafer processing.

0002

[Prior Art] Conventionally, in plasma etching processing or resist etching processing, which is one of the processes for manufacturing semiconductor integrated circuit devices, the end point of these processings has been detected by measuring the emission intensity at a specific wavelength. There is a method of calculating and determining changes over time. This is Tokukai Showa 6
As described in Japanese Patent Application Laid-open No. 3-255382 and Japanese Patent Application Laid-Open No. 63-244847, a processing gas is flowed into a wafer processing chamber and is turned into plasma by high frequency waves applied between electrodes. A specific emission wavelength from this plasma is collected from the measurement port of the processing chamber, and a computer calculates the change value over time to determine the end point.

0003

[Problems to be Solved by the Invention] The above-mentioned conventional technology has the advantage that there is less delay in determination because it observes the plasma state near the wafer. This method has the drawback that when the system becomes unstable for some reason, the end point may be incorrectly determined.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer processing end point determination method that can perform end point determination with good reproducibility even under unstable plasma generation conditions.

[0005]

[Means for Solving the Problems] In order to achieve the above object, processing gas is supplied to a wafer processing chamber where wafer processing is performed, and during wafer processing in which a predetermined wafer processing is performed, the processing gas is discharged from the processing chamber. The completion of wafer processing is determined based on the change value of gas components over time.

[0006]

[Operation] The components of the wafer processing gas discharged from the wafer processing chamber differ during and after wafer processing. For example, when photoresist material is removed with O2 gas plasma, the O2 or CO2 concentration during processing is different from the concentration after processing. The end point of wafer processing can be determined by data processing this time-dependent change value. At this time, it is technically difficult to collect the processing gas from the plasma generating section that is kept under vacuum. Therefore, the gas is collected from the outlet of the pump for exhausting the process gas because the pressure is usually close to atmospheric pressure and it is easy to collect the gas. Changes in the sampled gas components over time are measured using a gas analyzer. By doing this, although a slight delay in determination occurs, since it is located at a distance from the plasma generation part, it is less affected by the plasma generation part, and therefore it is possible to perform stable end point determination with good reproducibility.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention. A wafer is set in a processing chamber 1, and processing gas is supplied through a pipe 4. The supplied processing gas is evacuated by a vacuum pump 2 and is maintained at a predetermined pressure. The wafer is processed with a processing gas that has been turned into plasma by high frequency power, and the reaction gas and unreacted gas are exhausted through the pipe 5. The reaction gas exhausted by the vacuum pump 2 is exhausted through the pipe 6, but at this time the inside of the pipe 6 is near atmospheric pressure, and the reaction gas is sampled from the pipe 6 through the pipe 7 and analyzed. Record the changes in gas components over time in a total of 3 steps. The end point of wafer processing can be determined based on this change value. In this embodiment, since the gas sampling position is far from the actual plasma generation part, a slight delay in determination occurs. However, since the pressure up to the suction side of the vacuum evacuation pump 2 is high vacuum, the linear velocity is large, and the delay is so small that it hardly poses a problem in practice.

FIG. 2 shows the concentration change over time of reactant gas and unreacted gas when the present invention is applied to a photoresist removal system. The components of photoresist are mainly carbon and hydrogen, but when this is treated with O2 gas plasma, mainly CO2 is produced. During photoresist removal, the concentration of O2 gas decreases due to reaction, while the concentration of CO2 increases. After completing the removal of the photoresist, those relationships are reversed. The time at which the photoresist is reversed is the end point of photoresist removal.

[0009]

[Effects of the Invention] According to the present invention, even when the plasma itself becomes unstable due to some cause unrelated to plasma changes accompanying the progress of wafer processing, there is no misjudgment of the end point, and stable reproducibility is achieved. A certain end point can be determined.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a diagram showing changes in concentration over time of reactant gas and unreacted gas when the present invention is applied to a photoresist removal system.

[Explanation of symbols] 1...processing chamber, 2...vacuum pump, 3...gas analyzer, 8
...Data processing equipment.

Claims (2)

[Claims] [Claim 1] In wafer processing in which a processing gas is supplied to a wafer processing chamber in which wafer processing is performed and predetermined wafer processing is performed, wafer processing is terminated based on a time-varying value of a gas component after processing discharged from the processing chamber. A method for determining a wafer processing end point, the method comprising determining the end point of a wafer. 2. The wafer processing end point determination method according to claim 1, wherein the determination of the end of the wafer processing is performed by detecting gas components at an exhaust port of a vacuum pump that evacuates the processing chamber.