Feature profile evolution during shallow trench isolation etch in chlorine-based plasmas. II. Coupling reactor and feature scale models

A two-dimensional numerical fluid model was developed to investigate the effects of reactor design on the radial profiles of plasma species, namely, etch products and positive ions, during shallow trench isolation etching in Cl2∕O2∕Ar inductively coupled plasmas. Specifically, the dual-coil and dual gas-feed designs of the reactor were examined. The former parameter was determined to be effective in tailoring the radial ion flux profile at pressures higher than 20mT, while the latter parameter was shown to alter the etch product transport in the convection-dominant flow regime. Coupling of the reactor scale model to a feature scale model allowed investigation of minor center to edge variations in the etched feature profile. This hybrid model suggests that the general radial decrease in the etch depth seen from a set of design of experiments is caused by an inherent decrease in the spatial distribution of chlorine radicals. In addition, the increase in the silicon sidewall angle from center to edge can be qualitatively explained by the radial profile of the etch products.A two-dimensional numerical fluid model was developed to investigate the effects of reactor design on the radial profiles of plasma species, namely, etch products and positive ions, during shallow trench isolation etching in Cl2∕O2∕Ar inductively coupled plasmas. Specifically, the dual-coil and dual gas-feed designs of the reactor were examined. The former parameter was determined to be effective in tailoring the radial ion flux profile at pressures higher than 20mT, while the latter parameter was shown to alter the etch product transport in the convection-dominant flow regime. Coupling of the reactor scale model to a feature scale model allowed investigation of minor center to edge variations in the etched feature profile. This hybrid model suggests that the general radial decrease in the etch depth seen from a set of design of experiments is caused by an inherent decrease in the spatial distribution of chlorine radicals. In addition, the increase in the silicon sidewall angle from center to edge can be ...

[1]  Jane P. Chang,et al.  Kinetic study of low energy argon ion-enhanced plasma etching of polysilicon with atomic/molecular chlorine , 1997 .

[2]  David B. Graves,et al.  Comparison of model and experiment for Ar, Ar/O2 and Ar/O2/Cl2 inductively coupled plasmas , 2006 .

[3]  Jane P. Chang,et al.  Feature profile evolution during shallow trench isolation etch in chlorine-based plasmas. I. Feature scale modeling , 2008 .

[4]  M. Lieberman,et al.  Global model of Ar, O2, Cl2, and Ar/O2 high‐density plasma discharges , 1995 .

[5]  S Deleonibus.  Is there LOCOS after LOCOS , 1997 .

[6]  M. Kushner,et al.  Conceptual design of advanced inductively coupled plasma etching tools using computer modeling , 1996 .

[7]  C. Steinbrüchel.  Universal energy dependence of physical and ion-enhanced chemical etch yields at low ion energy , 1989 .

[8]  Jane P. Chang,et al.  Molecular-beam study of the plasma-surface kinetics of silicon dioxide and photoresist etching with chlorine , 2001 .

[9]  M. Lieberman,et al.  Role of etch products in polysilicon etching in a high-density chlorine discharge , 1996 .

[10]  H. Sawin,et al.  Etching of polysilicon in inductively coupled Cl2 and HBr discharges. II. Simulation of profile evolution using cellular representation of feature composition and Monte Carlo computation of flux and surface kinetics , 2002 .

[11]  J. Coburn.  Ion‐assisted etching of Si with Cl2: The effect of flux ratio , 1994 .

[12]  T. Ohzone,et al.  A practical trench isolation technology with a novel planarization process , 1987, 1987 International Electron Devices Meeting.

[13]  D. Graves,et al.  Effect of neutral transport on the etch product lifecycle during plasma etching of silicon in chlorine gas , 2003 .

[14]  D. Graves,et al.  Plasma uniformity in high-density inductively coupled plasma tools , 1995 .

[15]  N. Hershkowitz,et al.  Symmetric rate model for fluorocarbon plasma etching of SiO2 , 1996 .

[16]  A. Lichtenberg,et al.  Principles of Plasma Discharges and Materials Processing: Lieberman/Plasma 2e , 2005 .

[17]  S. Hamaguchi,et al.  Microprofile simulations for plasma etching with surface passivation , 1994 .