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Method for Forming Planar Self Aligned Via Studs

IP.com Disclosure Number: IPCOM000045231D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Feng, BC: AUTHOR [+2]

Abstract

In the conventional method of forming via studs through a lift-off process, the surface of the via studs is not planar due to misalignment, as shown in Fig. 1. In contrast, described here is a novel method of producing self-aligned via studs using the following procedure.

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Method for Forming Planar Self Aligned Via Studs

In the conventional method of forming via studs through a lift-off process, the surface of the via studs is not planar due to misalignment, as shown in Fig. 1. In contrast, described here is a novel method of producing self-aligned via studs using the following procedure.

A) Use the conventional lift-off process to form the structure shown in Fig. 2. After metal deposition, run the following steps and omit lift-off at this moment.

B) Apply a thin layer of polysulfone as a release agent. Though the casting solvents of polysulfone consisting of diglyme and n methyl 2 pyrrolidone are used for lift-off (at 135 degrees C), the above structure will not be damaged by the application of polysulfone. Experiments show that no damage of the structure is observed; even straight NMP or diglyme at room temperature can be applied on wafers without damage.

C) Here, the underlay resist can be immediately coated without baking polysulfone.

D) Underlay resist application.

E) Bake at 210-230 degrees C for 30 minutes.

F) Glass resin application. Bake at 230 degrees C for 30 minutes, or plasma deposit SiO(x) or Si(x)N(y).

G) Top resist application and soft-bake.

H) Expose with via hole pattern (optical or E-beam).

I) Development.

J) Reactive ion etch.

K) Via stud metal deposition (see Figs. 8A and 8B).

L) Lift-off in hot UP (n-methyl-2-pyrrolidone), 135 degrees C.

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