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Process for Simulating the Design and Fabrication of Device Structures

IP.com Disclosure Number: IPCOM000047282D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Appel, A: AUTHOR [+4]

Abstract

This computer-aided designing and manufacturing process enables a device modeler to visualize in three dimensions the results of selectively adding and subtracting materials according to a proposed design for fabricating a device structure. The process graphically generates 3D models of the substrate, mask and fabricated structure, showing the various volumes in which materials are deposited or removed in response to specified masking patterns, deposition thickness or depths of removal as the chosen fabrication techniques (evaporation, sputtering, etching and dissolving) are performed in simulation.

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Process for Simulating the Design and Fabrication of Device Structures

This computer-aided designing and manufacturing process enables a device modeler to visualize in three dimensions the results of selectively adding and subtracting materials according to a proposed design for fabricating a device structure. The process graphically generates 3D models of the substrate, mask and fabricated structure, showing the various volumes in which materials are deposited or removed in response to specified masking patterns, deposition thickness or depths of removal as the chosen fabrication techniques (evaporation, sputtering, etching and dissolving) are performed in simulation. Basically, the process involves a method of graphic analysis which makes use of various volumes defined as geometric entities, some of these volumes lying outside the device boundaries and others being constituent volumes within the device boundaries. A "condensation volume" is the polyhedron generated in space when a polygon or set of polygons representing the target area is translated toward a source of particles or evaporated material. If a mask is used, the "projection volume" is the polyhedron bounded by lines passing from the source through the edges of the mask opening. A "shadow volume" is the polyhedron generated as a polygon or set of polygons representing the non- impinged area of the target translated away from the source. The material added to a target by an evaporation or sputtering technique is the material contained in a condensation volume that is not inside a shadow volume, not inside the original target volume, and not outside the projection volume if a mask is used. In an ion beam etching process, material removed from a polyhedral model of the target is in a condensation volume that translates away from the ion source and that is also not inside the shadow volume, and, when a mask is used, is not outside the projection volume of the mask. Volumes lying within the target boundaries will be referred to hereinafter, particularly in connection with removal processes such as chemical dissolving. The figures show representations of various stages in the simulated fabrication of various device structures as viewed on the display screen of an interactive graphics terminal while operating under the control of the present design process. Typically, in designing a device structure which is fabricated at least in part by the use of a mask, two-dimensional (2D) plan representations of the substrate and mask configurations are generated on convenient parts of the display screen and are then moved into the desired alignment, as indicated in Fig. 1. These 2D images are then rotated and spaced in three dimensions to form perspective images, as shown in Fig. 2. A deposition thickness is specified by the designer, and the portion of the projection volume defined by that thickness is generated to simulate the deposited material, as shown in Fig. 3. After inspection...