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Submicron Gap-Fill Process for Electronic Structures

IP.com Disclosure Number: IPCOM000039828D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Finch, WF: AUTHOR [+3]

Abstract

This process enables filling submicron gaps in semiconductor integrated structures with high molecular weight polyimides. Fabrication of the metallization and insulation layers of single and multilevel metallization on semiconductor integrated circuits is done with the following generalized process sequence: 1) the insulating film is deposited; 2) appropriate channels are etched in the film by the usual methods; 3) metal is deposited in the channels through a liftoff (or other) mask; and 4) steps 1 through 3 are repeated for multilevel structures. Fabrication of such microstructures using polyimide as the insulating film material has the problem that a gap is formed between the etched walls of the insulator channel and the metal deposited in the channel.

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Submicron Gap-Fill Process for Electronic Structures

This process enables filling submicron gaps in semiconductor integrated structures with high molecular weight polyimides. Fabrication of the metallization and insulation layers of single and multilevel metallization on semiconductor integrated circuits is done with the following generalized process sequence: 1) the insulating film is deposited; 2) appropriate channels are etched in the film by the usual methods; 3) metal is deposited in the channels through a liftoff (or

other) mask; and 4) steps 1 through 3 are repeated for multilevel structures. Fabrication of such microstructures using polyimide as the insulating film material has the problem that a gap is formed between the etched walls of the insulator channel and the metal deposited in the channel. Subsequently deposited metallization will not reliably bridge this gap. The submicron gap can be filled with low molecular weight polyimide, but this material is not dimensionally and chemically stable. On the other hand, high molecular weight polyimide is stable but it will not fill the gap.

The reason appears to be that the surface tension holding the wet film together is greater than the energy of attraction between the wet film and the surface of the gap walls. The following method solves the problem of filling submicron gaps with high molecular weight polyimide (and other polymers). The process is as follows: 1) The semiconductor wafers are conventionally processed until

the gap is formed. 2) The wafers are then placed on the inside surface of a cylin der of radius r. 3) The cylinder is the...