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1.3 Overview and History of Process Simulators for Oxidation

Simulation of oxidation has a long tradition and a lot of people and institutions were active in oxidation modeling, also the Institute for Microelectronics [2]. Because over the decades a large number of oxidation simulators has been developed, this section is only focused on commercial process simulation tools. The history of the commercial tools is close with the history of the respective TCAD company. In principle all the following listed tools use the Deal-Grove concept (see Section 2.6) with its two rate constants and moving boundaries. The main reason to use the Deal-Grove model is the existence of the calibrated rate constants for a multitude of different oxidation conditions, because since Deal and Grove 1965 a lot of other oxidation experiments has been done. The price for this convenience are the difficulties in handling moving boundaries, especially in three dimensional geometries.

SUPREM-IV is a two-dimensional process simulator [3], which was developed at the Stanford University (Department of Electrical Engineering) in the TCAD group of Prof. Robert Dutton [4], with SUPREM a pioneer in TCAD. For oxidation SUPREM-IV has a compress and a viscous mechanical model [5]. The compress model treats the oxide as compressible liquid, while the viscous model treats the oxide as an incompressible viscous liquid. SUPREM-IV, the successor of the one-dimensional version SUPREM-III , is the basis for the two commercial tools TSUPREM-IV and ATHENA.

TSUPREM-IV [6] was the commercial version of SUPREM-IV from the company Technology Modeling Associates Inc. (TMA). TMA was founded out of Stanford University 1979 with Prof. Dutton as director and started the commercial TCAD business [7]. Approximately 20 years later, in 1998 TMA was acquired by the 1986 founded company Avant! Corp. In the last Avant! release 2002 TSUPREM-IV offers for oxidation a compress, viscous, and also a visco-elastic model [6]. Last release, because in 2002 Avant! itself was acquired by the company Synopsys Inc.

ATHENA [8] is the commercial version of SUPREM-IV from the private company Silvaco International [9], which still distributes ATHENA. Silvaco was founded 1984 by Dr. Ivan Pesic [10] and is since this time successful on the TCAD market. ATHENA was never extended to three dimensions and thus it is still only a two-dimensional tool [11]. ATHENA also has the same compress and viscous mechanical models like the university version SUPREM-IV.

In 1992 TMA started a project for a new three-dimensional process simulator which is mainly based on the level-set algorithm. After TMA was acquired, Avant! released this product 1998 with the name TAURUS [12]. The mechanics during oxidation is described with a visco-elastic model. Because of the problems with moving boundaries in three dimensions, TAURUS has never become a complete stable three-dimensional process simulator [13].

The Integrated Systems Laboratories at the ETH Zurich also developed a two-dimensional process simulator named DIOS [14], which came out 1992. Later, in December 1993 the company Integrated Systems Engineering AG (ISE) was founded as a spin-off of the university laboratories. Since this time ISE distributed DIOS as a commercial tool. In the last 2004 ISE TCAD release, a viscous, elastic, or visco-elastic model for the mechanical problem can be applied. This was the last release, because in 2004 ISE was also acquired by Synopsys.

In 1993 a first version of the Florida Object-Oriented Process Simulator (FLOOPS) was completed. FLOOPS was developed at the University of Florida in the Electrical Engineering Department of Prof. Mark Law [15]. Already 1996 the PhD student Stephen Cea presented that FLOOPS has been extended from two to three dimensions and three-dimensional oxidation simulation can be performed [16]. Since 1996 the work has been continued to reach a stable three-dimensional tool, because even the actual FLOOPS version is still a little buggy for three-dimensional oxidation [17]. The 2002 release of FLOOPS was commercialized by ISE in the same year and henceforth promoted as the next generation three-dimensional process tool [18]. With the additional developments of ISE the so-called FLOOPS-ISE became a stable three-dimensional oxidation simulator. FLOOPS-ISE has the same mechanical models as DIOS (viscous, elastic, and viscoelastic), but extended for three-dimensional structures [19].

The company Synopsys Inc. [20] was founded in 1986. After Synopsys acquired Avant! and ISE, it holds now the licenses for all former Avant! and ISE tools and has with 80% market share nearly a monopoly in the TCAD market [13]. Silvaco is the only remaining competitor. For two-dimensional process simulation Synopsys sells now the packages DIOS and TAURUS-TSUPREM-IV [21]. After merging with ISE, Synopsys started to transfer the best features of DIOS, TAURUS and TSUPREM-IV to the FLOOPS-ISE platform for generating a new three-dimensional process simulator [22]. The first release of the new simulator with the name SENTAURUS [23] was carried out in 2005 [24].

next up previous contents
Next: 1.4 Outline of the Up: 1. Introduction Previous: 1.2 Isolation Techniques

Ch. Hollauer: Modeling of Thermal Oxidation and Stress Effects