Effect Plasma Transport on Etched Profiles with Surface Topography in Diverging Field Electron Cyclotron Resonance Plasma

Abstract

Recent studies of electron cyclotron resonance (ECR) plasma etching for fabricating fine patterns of less than a half-micron indicate a serious problem in the etched profiles caused by a charge build-up of the patterns. The relationships between the local pattern distortion and the plasma properties measured by the electrostatic probe are investigated. Lowering the electron temperature perpendicular to the surface normal is one of the most effective techniques for eliminating the local side etch. It is enhanced by setting the wafer at the lower magnetic field. As the large space charge bends the ion trajectories, the higher ion current density also enhances the local side etch. The distribution of plasma potential which accelerates the ions can reduce the local side etch in spite of the higher current density.

Kinetic-energy measurement of a neutral stream extracted from Ar electron cyclotron resonance plasma

“…1,2 They are caused by a local charge buildup on the surface of a pattern, which occurs as a result of ions and electrons having different motions. 3 Therefore, one solution to these problems is to use neutral particles for etching instead of charged particles. 4 Anisotropic etching by neutral particles requires the production of energetic and directed neutral species.…”

Electron temperatures of inductively coupled Cl2–Ar plasmas

“…[1][2][3][4][5][6][7] We have previously reported measurements of the absolute densities of Cl 2 , Cl, Cl 2 ϩ , Cl ϩ , and Ar ϩ in inductively coupled plasmas ͑ICPs͒ containing such mixtures; such measurements should be useful to investigations of the etch mechanism, rate, selectivity, and etched profile shapes. [8][9][10] Eddy et al have used a Langmuir probe to measure T e as a function of rf power and Ar fraction in Cl 2 -Ar electron cyclotron resonance discharges. The electron energy distribution function ͑EEDF͒ ͑and therefore T e ͒ can affect the undesirable etched profile anomalies, such as bowing and microtrenching, and electrical damage due to charge build-up and current flow, as have been observed in the etching of silicon device materials ͑e.g., Si and Al͒.…”

High electronegativity multi-dipolar electron cyclotron resonance plasma source for etching by negative ions

“…[1][2][3][4][5][6][7] So far, only positive ions at low pressure and high plasma densities are used to ensure good anisotropy and high etching rates. [8][9][10][11][12][13][14][15][16][17][18][19] The continuous decreasing of the node size (now below 100 nm) at an increased devices density bring new challenges that need to be solved, including: charging-induced gate breakdown; 20,21 dependence of the etching rate on the pattern size (low RIE-lag effect 22 or aspect-ratio-dependence etching effect) and on the laid-out pattern density (microloading effect); 23 and handling of new materials such as low-k and high-k. 1 In particular, the notch phenomenon 24 induced by side etching with positive ions deflected by the positive space charge accumulated at the bottom of patterns has pointed to the possibility to reduce the charge build-up effect by etching with negative ions that induce lower charging potentials for similar ion fluxes and ion energy. 23 Moreover, negative ion etching can also bring the advantage of replacing the sulfur-based positive-ion-species (SF þ 2 and SF þ 3 ) that need to dissociate before releasing F þ , with a process dominated by volatile F À .…”