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Simulation of three‐dimensional refractory metal step coverage over contact cuts and vias

 

作者: M. K. Sheergar,   T. Smy,   S. K. Dew,   M. J. Brett,  

 

期刊: Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena  (AIP Available online 1996)
卷期: Volume 14, issue 4  

页码: 2595-2602

 

ISSN:1071-1023

 

年代: 1996

 

DOI:10.1116/1.588992

 

出版商: American Vacuum Society

 

关键词: INTEGRATED CIRCUITS;TUNGSTEN;DIFFUSION BARRIERS;THIN FILMS;MORPHOLOGY;MICROSTRUCTURE;THREE−DIMENSIONAL CALCULATIONS;COMPUTERIZED SIMULATION;COMPUTER CODES;COMPARATIVE EVALUATIONS;W

 

数据来源: AIP

 

摘要:

In very large scale integration metalization processes, thin diffusion barrier metal films deposited over vias and contacts are used to inhibit the diffusion of the top metal layer into the underlying junctions. These thin films are normally sputter deposited and their reliability is crucial to die yield and device lifetime. As wafer sizes increase, die at the wafer edge receive a directionally asymmetrical sputter flux, leading to nonuniform and asymmetrical film coverage over vias and contacts. Two three‐dimensional (3D) extensions of the two‐dimensional (2D) film growth programSIMBADare presented. The first extension (quasi‐3D) assumes a radially symmetrical adatom flux distribution and would be appropriate for the simulation of film deposition on regions near the central axis of a radially symmetrical target. Due to the assumption of a symmetrical flux distribution, the resulting film growth is symmetrical. The second extension (interpolated‐3D) does not assume that the flux is symmetrical and is intended for the simulation of asymmetrical film growth off‐axis. Both extensions provide a 3D surface of the deposited film and the microstructure and profile of 2D slices through the via or contact. In order to determine the accuracy of the two models, simulations were compared to W films sputter deposited over contacts having an aspect ratio of 3:1. The models were tested for a substrate placed directly under the center of the target. The interpolated‐3D model was also tested for asymmetrical fluxes by placing the substrate off‐axis by 2.2, 5.0, and 8.1 cm. The comparisons with the experimental results indicate that both the surface profiles and the microstructure of the deposited films were predicted well by the two models. The interpolated 3D model was very successful at predicting deposition profiles for off‐axis deposition flux.

 

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