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Sensitive Surface Damage Avoidance During Polishing

IP.com Disclosure Number: IPCOM000122323D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Burke, PA: AUTHOR

Abstract

By chemically etching to remove sharp protrusions on a surface prior to polishing, damage to nearby sensitive areas, e.g., thin gate insulation, by break-away projection fragments during a polishing operation is avoided.

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Sensitive Surface Damage Avoidance During Polishing

      By chemically etching to remove sharp protrusions on a surface
prior to polishing, damage to nearby sensitive areas, e.g., thin gate
insulation, by break-away projection fragments during a polishing
operation is avoided.

      Referring to the figure, conventional processing is used to
form thin gate insulator 10 on silicon substrate 12 and to
anisotropically etch a shallow trench through film 10 and into
substrate 12.  Thick oxide 14 is conformally applied and a pattern is
formed in photoresist (PR) 16. Then, an anisotropic etch nearly
planarizes the surface of oxide 14.  In conventional processing, PR
16 is stripped and the surface of oxide 14 is polished to finalize
planarization to the level of the surface of gate insulation 10.
Fragments of "fence" 18 may be broken away during polishing and
damage nearby gate insulation 10.

      By isotropic etching, e.g., immersion in hydrofluoric acid (HF)
either before or after resist 16 is stripped, thickness of oxide 14
is reduced a small amount and sharp protrusions, e.g., fence 18, are
removed before polishing. Elimination of this source of abrasive
particles during polishing to completely planarize the surface and
expose gate insulator 10 results in improved yield of acceptably
insulated gates.

      Disclosed anonymously.