Method for determining the end point for a cleaning etching process
View Patent ↗A method is provided for determining the end point during cleaning etching of processing chambers by means of plasma etching, which is used for carrying out coating or etching processes during the manufacture of semiconductor components. The invention provides a method for effectively and reliably determining the end point during cleaning etching of processing chambers. The end point is determined by monitoring the DC bias voltage on the plasma generator which is used for the plasma cleaning etching in the processing chamber in an evaluation unit. The plasma cleaning etching process is terminated by stopping the supply of the process gases in the gas supply unit and by switching off the plasma generator upon reaching a predetermined DC bias voltage value which corresponds to completion of the cleaning etching process.
1. A method for determining an end point of a plasma etching process using ionized process gases for cleaning etching of a processing chamber that is used for coating or etching processes during the manufacture of semiconductor components, comprising the steps of:
monitoring a DC bias voltage profile of a plasma generator during a cleaning etching process run, wherein the DC bias voltage is the voltage measured between ground and a decoupling electrode of the plasma generator disposed within the processing chamber, and wherein the voltage measurement points are selected so that the measured voltage profile has a maximum in the voltage profile at the endpoint of the cleaning etching process indicating that the processing chamber is clean;
comparing the DC bias voltage to a stored value representing a clean processing chamber, wherein the stored value is predetermined from a prior plasma cleaning etching process run; and
terminating the plasma cleaning etching process by disconnecting a supply of process gases and deactivating the plasma generator when said DC bias voltage reaches said predetermined value.
2. The method according to claim 1 , wherein the measured DC voltage profile is compared with a previously stored DC voltage profile.
3. The method according to claim 2 , wherein the comparison of the DC voltage profiles is performed for process runs with the same process gases and process parameters.
4. The method according to claim 1 , wherein a plurality of DC voltage profiles of plasma cleaning etching process are stored.
5. The method according to claim 4 , wherein the measured-DC voltage profile is compared with a previously stored DC voltage profile.
6. The method according to claim 5 , wherein the comparison of the DC voltage profiles is performed for process runs with the same process gases and process parameters.