AVS 45th International Symposium
    Manufacturing Science and Technology Group Thursday Sessions
       Session MS-ThM

Invited Paper MS-ThM7
Process Environment Monitoring of Plasma Etching for Advanced Process Control

Thursday, November 5, 1998, 10:20 am, Room 317

Session: Sensors and Support Technology
Presenter: H. Enami, Hitachi, Ltd., Japan
Authors: H. Enami, Hitachi, Ltd., Japan
A. Kagoshima, Hitachi, Ltd., Japan
Correspondent: Click to Email
The development of 0.18um process is our current target. Some equipment, at present, cannot meet the requirements from the process (e.g. Selectivity, uniformity, aspect ratio, etc., in dry etching). Considering the facts: (1) Physical limitation against the countermeasures in equipment (2) Decrease of Overall Equipment Effectiveness due to increasing QC time, we suggest quick installation of advanced process control (APC) system such as In-Situ control. To make the best use of In-Situ Control, following 3 steps are necessary. (1) To find useful methods and instruments for process condition analysis. (2) To make digital network among instruments for analysis and to reduce sampling period (less than 1 sec./time) and the prices of those instruments. (3) To find a correlation between monitoring data and process condition or results. Firstly, In-Situ data comparison between Plasma Probe Data and RF Impedance (RFIM) Data shows that RFIM is more useful monitoring method than Plasma Probe for unstable plasma discharge and fluctuating process condition. Secondly, Plasma diagnostics by Plasma Optical Emission Spectroscopy (OES) per sub-micro-sec shows that Pulsed-Plasma-Discharge contributes to improve etching uniformity and control the quantity of etchant. Quadrupole Mass Spectrometry (QMS) is also useful for the same purpose. Comparing OES and QMS, OES is useful for short life species in plasma, on the other hand OMS is for reacted species or products. Both are necessary as In-Situ-Monitoring. In dry etching (SiO@sub 2@ film) process, for example, the combination of OES and RFIM for Gas flow rate and RF Power control contributes to reduce the dispersion of Selectivity among wafer to wafer in a batch to 25% of it without control. This data shows the advantage of In-Situ Control by simple, convenient and high-speed sensor. Then we have began the development of process control system using RFIM, OMS, OES allowing more than one time feedback per second.