Assist feature for random, isolated, semi-dense, and other non-dense contacts
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorShinn-Sheng Yu
Life of this patent
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Abstract
An assist feature for isolated, and semi-dense random contacts, as may be present on a photomask used in photolithographic processes for semiconductor device fabrication, is disclosed. The assist feature can be used in conjunction with off-axis illumination (OAI) for such non-dense contacts, for improving the depth of focus (DOF), resolution, or both of photolithography for such contacts, such that the non-dense contact preferably substantially mimics a dense contact during OAI. A photomask of the invention includes a number of assist features situated near and around the non-dense contact. A method for creating a photomask according to the invention, as well as a method for fabricating a semiconductor device using such a mask, are also disclosed.
Claims15
An off-axis illumination (OAI) photomask for OAI semiconductor photolithography processing comprising:
- a transparent substrate;
- an opaque non-dense contact that is isolated and/or random;
- and,
- a plurality of opaque assist features situated near and around the non-dense contact, each assist feature having a size smaller than a size of the non-dense contact,
- the plurality of assist features improving at least one of depth of field (DOF) and resolution of the semiconductor photolithography processing.
A method for producing an off-axis illumination (OAI) photomask comprising:
- creating a non-dense opaque contact on a transparent substrate of the photomask, the non-dense opaque contact being isolated and/or random;
- and,
- creating a plurality of substantially identical opaque assist features situated in at least a substantially regular pattern around the non-dense contact, each assist feature having a size smaller than a size of the non-dense contact,
- such that the plurality of assist features allow the non-dense contact to at least more closely mimic a dense contact during OAI.
Dependencies are inferred from the claim text.