ECR Plasma Etching Technology for ULSIs
- PDF / 1,152,265 Bytes
- 11 Pages / 420.48 x 639 pts Page_size
- 58 Downloads / 249 Views
ECR Plasma Etching Technology for ULSIs
Seiji Samukawa VLSI Development Div., NEC Corporation 1120 Shimokuzawa Sagamihara, Kanagawa, 229, Japan Abstract A new electron cyclotron resonance (ECR) plasma etching technology has been developed to realize simultaneously high selectivity, high rate and anisotropic etching for phosphorus doped poly-Si and WSix/poly-Si at a low ion energy. In this technology, a substrate is located around the ECR position (875 gauss position) in an ECR plasma. As a result of ECR position etching, under the low pressure of 5 x 10-4 Torr, a high etching rate and an infinite selectivity to SiO 2 etching are realized by using C12/0 2 and C12/0 2 /SF 6 etching gas. 1I.Introduction Electron cyclotron resonance (ECR) plasma etching technology for submicron pattern fabrication has many advantages, such as low ion energy and high density plasma in low pressure. However, the ECR plasma etching system has not been widely accepted in production lines because of poor uniformity, low etching rate and poor anisotropy. The disadvantages of ECR plasma etching technology are caused by plasma transport from a discharge region to an etching region as a result of the divergent magnetic field gradient. The traveling plasma stream diameter is enlarged by the divergent magnetic field. The amount of ions and radicals decreases through the relaxation and the recombination process that take place during the plasma transport. Therefore, ion current density becomes lower and nonuniform, and the ions have various flight directions due to scattering. This paper reviews on ECR plasma characteristics and the results of ECR position etching accomplished by a newly developed ECR plasma etching system [1,2,3,4]. It solves the above problems, and provides n+ poly-Si and practical and accurate ECR plasma etching for WSix/poly-Si. These etching characteristics are obtained in 6 in.-diam. substrates.
Mat. Res. Soc. Symp. Proc. Vol. 223. @1991 Materials Research Society
Downloaded from https://www.cambridge.org/core. UNSW Library, on 18 Apr 2020 at 16:07:08, subject to the Cambridge Core terms of use , available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-223-97
98
2.Experimental A schematic illustration of the ECR plasma etching system used in this study is shown in Fig.1. Plasma chamber diameter is 260 mm. Silicon substrates of 6 or 8-inch diameters are automatically transported to substrate holder. Main magnetic coils and sub-magnetic coils are located around the periphery of the plasma chamber. In this experiment, a substrate is located around the ECR position (875 gauss position) in an ECR plasma. The etching characteristics near the ECR position are investigated using n+ poly-Si and WSix/poly-Si as etching materials. The etching is carried out without radiofrequency (RF) bias. A n+ poly-Si (4000A thick) film or a WSix (1100 A thick)/poly-Si (1600 A) are deposited on the thermal oxide. The etching gases used for the n+ poly-Si and WSIx/poly-Si are C12, C12/0 2 and C12/02/SF 6 . 3.Results and Di
Data Loading...
