SPRINTCAD QUARTERLY SUMMARY

April 1 - June 30, 1995


ORGANIZATION:

Stanford University

SUB-CONTRACTORS:

none

PRINCIPAL INVESTIGATORS:

Robert W. Dutton, dutton@gloworm.Stanford.EDU, (650) 723-4138
Kincho H. Law, law@cive.Stanford.EDU, (650) 725-3154
Krishna Sa raswat, saraswat@ee.Stanford.EDU, (650) 725-3610
Peter Pinsky, pinsky@ce.Stanford.EDU

PROJECT LEADER

Edwin C. Kan, kan@gloworm.Stanford.EDU, (415) 723-9796


TITLE OF EFFORT:

"SPRINT-CAD"---Industry-Networked TCAD using Shared Parallel Computers

RELATED INFORMATION:

The URL for Stanford TCAD projects is: http://www-tcad.stanford.edu

OBJECTIVE:

First-time capabilities to bridge solid modeling, FEM-based parallel computation of fabrication processes and electrical analysis of the resulting IC structures will be developed. Models needed to represent diffusion, etching, deposition, oxidation and stress analysis resulting from a sequence of process steps necessary in the creation of electrical devices will be developed. This effort will provide a radically new HPC framework for technology-based 3D process/device modeling as well as realistic benchmarks to test HPC architectures and software.

APPROACH:

We will build, integrate and test TCAD modules based on an object-oriented approach that both develops and uses information models in support of CFI-based standards. The modules and software engineering methodology will be designed specifically to exploit parallel computers and library components. The 3D process simulation modules will utilize HPC platforms and provide new functional capabilities for "computational prototyping" of the following key technology fabrication steps:
  1. deposition/etching module---of special interest are CVD and plasma assisted processes that result in high aspect ratio structures such as trenches and filling/planarization of structures for metal interconnects. Algorithmic work focuses on geometric manipulations and surface evolution.
  2. thermal/stress analysis module---that can solve nonlinear constitutive models for key process steps involving growth of dielectric layers and impurity redistribution as well as the resulting stress fields. Advanced formulations for finite elements are being developed that support: parallel computation, adaptive gridding and domain decomposition.

PROGRESS:

Most of Sprint-CAD research directions have made good progress within the last quarter, and there are major breakthroughs on the diffusion and etching/deposition modules. These are summarized below.

The dial-an-operator finite-element program ALAMODE has been successfully implemented for 1-2-3D test problems such as boron segregation (benchmarked with SUPREM IV) and five-species kinetic phosphorus diffusion (benchmarked with PEPPER). Demonstration examples include 1D and 2D SUPREM mesh and 3D FLOOPS mesh. Diffusion in poly-silicon by considering the average grain boundary growth/recombination is under intensive study. This will demonstrate first-time capabilities in consistent modeling of both front-end and back-end processes. The layered access to model definition and program control have been implemented using the tcl scripting language.

The 2D and 3D SPEEDIE for physical etching/deposition simulation has been implemented with a collision-free boundary movement method based on the level-set function approach. The boundary merge and cutoff can be simulated in a physical manner. Examples of 2D overhang structure with PECVD and 3D stringer problems on nonplanar surfaces have been successfully simulated. This approach is a first-time demonstration of the 3D geometry/field server that can be used for accurate physical etching/deposition simulation.

The FOREST 2D geometry/field server now fully supports the minimal SWR specification and has been under testing to be used by the newly developed modules (ALAMODE and SPEEDIE) in the procedural level. The CAMINO 3D geometry/field server can now provide most of the functions in the minimal SWR specification, but in lack of the geometry fixing capabilities. An active study of using the collision free method for 3D geometry fixing is under way. All of the tools developed have been aiming at the open architecture of SUPREM OO7, which will contain true plug-and-play capabilities for all physical simulation modules, geometry/field servers, graphical visualizers and user control.

The new finite-deformation oxidation model has been demonstrated for asymptotic elastic and viscous cases. Consideration on thermal constitution relations and deformation kinematics has been added to the formulation. The boundary movement will be treated by the collision-free method summarized above. A quasi-3D modeling of the LOCOS isolation structure has been developed based on 2D simulation and physical manipulation of geometry in the third dimension. This approach has been calibrated with the experimental results.

RECENT ACCOMPLISHMENTS:

FY-`96 PLANS:

TECHNOLOGY TRANSITION:

The proposed minimal SWR specification, which is fully supported by the FOREST geometry and field server, is released for beta test at IBM, ATT and Intel. This is not only a release of ONE OF the proposed standards, but also a fully functional server supporting the standard, so that the specification is ready for practical testing purposes. The SUPREM-ALAMODE code has been used in other Stanford groups as well as in Intel, where one of the key developers of the dial-an-operator module has been working as a summer intern. Various defect-related dopant transport effects, such as the transient enhanced diffusion, have been vigorously studied using the flexible physical definition and multi-dimension capability in ALAMODE. At Intel, it will also be tested on heat conduction during device operation as an entirely different type of application owing to ALAMODE's tremendous flexibility. The advance in etching/deposition boundary movement will be included in the future SPEEDIE release.

Edwin C. Kan
kan@gloworm.stanford.edu
201 AEL, Stanford University, Stanford, CA 94305
Office: (415)723-9796
Fax: (415)725-7731

Date prepared: 7/27/95