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Structure and Method for Forming Subtractive Features with Electrophoretic Resist

IP.com Disclosure Number: IPCOM000149800D
Original Publication Date: 2007-Apr-06
Included in the Prior Art Database: 2007-Apr-06
Document File: 3 page(s) / 145K

Publishing Venue

IBM

Abstract

Disclosed is a method for forming structures with multiple levels of topography needed for various silicon-based packages utilizing electrophoretic resist deposition.

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Structure and Method for Forming Subtractive Features with Electrophoretic Resist

    Structure and Method for Forming Subtractive Features with Electrophoretic Resist Cornelia K. Tsang, John M. Cotte, Christopher V. Jahnes
Disclosed is a method for forming structures with multiple levels of topography needed for various silicon-based packages. Increasingly, silicon-based packages and other three-dimensional integrated circuit (IC) structures require the ability to accommodate other devices (such as optoelectronic chips, SiGe chips) in large cavities or allow for optical signal pathways by means of silicon through-vias. These designs result in many levels of topography and complicate the process fabrication of these structures. In order to etch one structure (for example, a large cavity) and then further define and etch another structure (such as a via), a method of coating lithography materials as resists over large cavities/topographies must be invented. The traditional methods of spin-coating resists do not apply in this fabrication scheme because the spinning action over a previous etched feature results in streaking of the resist and destructive patterning of a silicon wafer surface. Another method of resist coating is spray-on resist coating. This method is also not feasible because of the non-uniformity of the resist coating which will result in some areas of pattern being defined while others are not. A last method of resist coating is through a laminated sheet-like resist such as RistonĀ®. In this lamination method, a previously etched cavity can be covered. However, the fine pitch and features of most required semiconductor structures cannot be achieved. The method that will successfully form such structures is an electrophoretic resist deposition which involves depositing resist over all areas of the wafer structure, including areas that have been previously etched/depressed.

    An electrophoretic resist deposition method of conformally covering all areas of a conductive silicon wafer surface will allow any variety of etched feature to be first formed in the wafer substrate, followed by the resist deposition and formation of any variety of subtractive etch feature, etched secondly. Due to the ability of electrophoretic resist deposition of covering all topographies on a wafer, this method also allows for the 2nd etched features to be defi...