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EP0655773A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Lithographic image size reduction

Assignee: STMicroelectronics SRL
•
Filing: 1993-10-27
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Granted: —
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Expires: 2013-10-27
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Abstract

Abstract A mask having features of a smaller size than a lithographically defined image width is formed by depositing a first layer of a different material from the underlying material to be treated through the openings of the mask. This first layer is lithographically patterned and thereafter a conformally deposited second layer is anisotropically etched, thus leaving residues on vertical definition walls of the first layer. The mask openings are restricted to a controllably reduced width as compared with the width of the lithographically defined window. Empirical relationships between the thicknesses of the deposited layers and the reduction of the lithographic image size that is achieved provide a good dimensional control of the mask openings that are finally produced, adequate for sub-micron line-width processes.

Inventors

  • 👤 Claudio Brambilla
  • 👤 Manlio Sergio Cereda
  • 👤 Andrea Ravaglia

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-06 08:46
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; H10P76/4088

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 136 words
A method for forming a mask having a window of a smaller width than a lithographically defined width, on the surface of a first material, characterized by: a) depositing a first layer of a second material different from said first material; b) lithographically defining by the use of a photosensitive resist layer a window of a certain width; c) anisotropically etching through said lithographically defined window said first layer and removing the resist mask; d) conformally depositing a second layer of a material different from said first material; e) anisotropically etching said second, conformally deposited layer, leaving residues on vertical definition walls of said first layer; f) the opening defined between said residues formed on vertical definition walls of said first layer, having a reduced width as compared with the width of the litographically defined window.
Claim 2
Dependent Claim 25 words
A method as defined in claim 1, wherein said first material belongs to the group composed of monocrystalline semiconducting material, dielectric material and conducting material.
Claim 3
Dependent Claim 23 words
The method as defined in claim 1, wherein said first material belongs to the group composed of silicon, glass, metal and silicon nitride.
Claim 4
Dependent Claim 27 words
The method as defined in claim 1, wherein said first material is a conducting material and said first and said second layers are both of an oxide.
Claim 5
Dependent Claim 15 words
The method according to claim 4, wherein said oxide is obtained by chemical vapor deposition.
Claim 6
Dependent Claim 75 words
The method as defined in claim 1, wherein the thickness S C of said first deposited layer, the thickness S D of said second conformally deposited layer and a distance by which the width of said lithographically defined window is reduced (W-w), satisfy the following relationships: W - w ≈ 2S D , when S C ≧ S D ; or W - w ≈ 2S C , when S C << S D .
Claim 7
Dependent Claim 34 words
The method as defined in claim 1, wherein said first material is a dielectric and said first layer and said second conformally deposited layer are both of a polysilicon, deposited by chemical vapor deposition.

References Cited (Backward Citations)

US4792534A Cited
EP0265638A2 Cited
US4801350A Cited
EP0491408A2 Cited

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