| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThA |
| Session: | Plasma Sources |
| Presenter: | K. Maeda, Hitachi, Ltd., Japan |
| Authors: | K. Maeda, Hitachi, Ltd., Japan H. Tamura, Hitachi High-Technologies Corp., Japan S. Obama, Hitachi High-Technologies Corp., Japan M. Izawa, Hitachi High-Technologies Corp., Japan G. Miya, Hitachi, Ltd., Japan |
| Correspondent: | Click to Email |
In semiconductor industries, a high level of productivity to reduce the cost of ULSI fabrication has always been required for plasma etching tools, as well as the other tools. According to the International Technology Roadmap for Semiconductors (ITRS) 2010, increasing the size of the wafer improves the productivity, and the diameter of the Si wafer will be 450 mm in 2014. One of the most significant problems for achieving an extremely uniform process for the 450-mm wafer area is precise control of the plasma distribution over a large area. We have developed a newly designed microwave electron cyclotron resonance (M-ECR) plasma reactor for next-generation 450-mm wafer processing. The reactor configuration is based on the previous M-ECR etching reactor for 300-mm wafers. A microwave power of 2.45-GHz in a circular TE11 mode (principal mode) is supplied to the chamber via the circular waveguide, microwave circuit (cavity), and quartz window. The chamber is surrounded by solenoid coils and a yoke, and the position of the ECR plane (87.5 mT magnetic field strength) is controlled by the currents supplied to the coils.
We present the measurement of two-dimensional (radial and vertical) distribution of ion saturation currents in the reactor, which was measured by a movable single probe system in halogen gas mixture at 0.4 Pa for poly-Si etching. The ring-shaped high density region was observed at the ECR plane in the optimized microwave circuit type, in which we could obtain uniform plasma distribution just above the wafer. This plasma distribution could be controlled by changing the position of the ECR plane. On the other hand, strongly convex-shaped plasma distribution was observed in an inappropriately designed microwave circuit. A plasma generating distribution is also estimated by comparing the result of plasma-diffusion analysis in magnetized plasma to that of a probe experiment. We confirmed that the plasma seemed to be generated in a very thin (1-2 cm) region at the ECR position. In addition to the result of plasma characteristics, the etching results, i.e., radial distribution of poly-Si etching rate, with a uniformity of 1.5%, and critical dimension control of the line and space pattern by controlling the temperature of the wafer are also presented.