Control of Plasma Etch Profiles with Plasma Sheath Electric Field and RF Power Density

Abstract

In this paper it is shown that the plasma sheath electric field in which the etch sample is immersed controls the anisotropy of the etching of polysilicon films. These films are on wafers supported by the grounded electrode of a diode plasma etch reactor. The sheath electric field at the wafer supporting electrode is modified either by changing the rf power delivered to the plasma, or, at constant rf power, by application of d-c voltage to the rf driven electrode, With similar consequences to the etch profiles. The absence of mask undercut and vertical etch walls characteristic of an anisotropic etch process are observed above a certain threshold power density-sheath electric field, while below this threshold, the profiles become progressively more undercut until they are equal to the etch depth, as expected ofisotropic etch processes. The experimental results presented in this paper, demonstrate these effects for a CC14 containing gas mixture at a total pressure of 65 Pa (0.5 Torr). A similar power density and pressure dependence of the etch anisotropy has been reported previously in different plasma etch gas under comparable conditions. These results will be shown to be explicable in terms of the increase in the anisotropy of the transport of ions for increasing sheath field. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-03-16 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-03-16 to IP Publication costs o] this article were assisted by the Perkin-Elmer Corporation.

Semi-analytical model for a static sheath including a weakly collisional presheath

“…(12) is the space charge density in the presheath region, Poisson's equation Eq. (1) becomes the Helmholtz equation as follows:…”

“…In reactive ion etching processes, ions are accelerated in a sheath adjacent to a wafer surface and play an important role in controlling etching characteristics such as etching rate, 1) anisotropy, 2,3) directionality, [4][5][6] selectivity, 7,8) and damage. [9][10][11][12] Among them, the directionality of ions is closely related to the shapes of microstructures formed on the wafer surface.…”

Tunable metamaterials with carrier-induced effective permittivity for active control of electromagnetic fields in semiconductor manufacturing device

“…The ability to control local electromagnetic fields precisely is an essential and potentially quality-determining factor in many advanced manufacturing processes ranging from plasma etching to direct laser writing [1][2][3][4][5][6][7][8][9]. Those processes aiming to realize leading-edge devices often require extreme precision and uniformity.…”