Illumination-source shape definition in optical lithography
AssigneesImec, Sony Corporation, ASML Netherlands B.V.
InventorsKazuya Iwase, Peter De Bisschop
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Abstract
A method and system are described for determining lithographic processing conditions for a lithographic process. After obtaining input, a first optimization is made for illumination source and mask design under conditions of allowing non-rectangular sub-resolution assist features. Thereafter, mask design is optimized in one or more further optimizations for which only rectangular sub-resolution assist features are allowed. The latter results in good lithographic processing while limiting the complexity of the mask design.
Claims12
A method for determining lithographic processing conditions for a lithographic process, the method comprising:
- performing using a processing system:
- obtaining characteristics of an illumination source and a mask design, the mask design comprising a lithography pattern;
- performing a first optimization for combined optimizing of at least the illumination source characteristics and the mask design characteristics for the lithographic process, whereby for the first optimization non-rectangular sub-resolution assist features for the mask are allowed;
- determining from the first optimization a set of optimized illumination source characteristics;
- performing at least one additional optimization for optimizing the mask design characteristics of the lithographic process, whereby for the at least one additional optimization the presence of non-rectangular sub-resolution assist features for the mask design is substantially excluded and whereby the at least one additional optimization takes into account the set of optimized illumination source characteristics;
- and
- determining from the at least one additional optimization a set of optimized mask design characteristics substantially excluding non-rectangular sub-resolution assist features.
A system for determining lithographic processing conditions for a lithographic process, the system comprising:
- an input means for obtaining characteristics of an illumination source and a mask design, the mask design comprising a lithography pattern;
- a processing means programmed for performing a first optimization for combined optimizing of the illumination source characteristics and the mask design characteristics for the lithographic process, whereby for the first optimization non-rectangular sub-resolution assist features for the mask are allowed;
- determining from the first optimization a set of optimized illumination source characteristics;
- performing at least one additional optimization for optimizing the mask design characteristics of the lithographic process, whereby for the at least one additional optimization the presence of non-rectangular sub-resolution assist features for the mask is substantially excluded and whereby the at least one additional optimization takes into account the set of optimized illumination source characteristics;
- and
- determining from the at least one additional optimization a set of optimized mask design characteristics substantially excluding non-rectangular sub-resolution assist features.
A method of manufacturing an electronic device, the method comprising:
- determining a set of lithographic processing conditions comprising illumination source characteristics and mask characteristics by:
- obtaining characteristics of an illumination source and a mask design, the mask design comprising a lithography pattern;
- performing a first optimization for combined optimizing of at least the illumination source characteristics and the mask design characteristics for the lithographic process, whereby for the first optimization non-rectangular sub-resolution assist features for the mask are allowed;
- determining from the first optimization a set of optimized illumination source characteristics;
- performing at least one additional optimization for optimizing the mask design characteristics of the lithographic process, whereby for the at least one additional optimization the presence of non-rectangular sub-resolution assist features for the mask design is substantially excluded and whereby the at least one additional optimization takes into account the set of optimized illumination source characteristics;
- determining from the at least one additional optimization a set of optimized mask design characteristics substantially excluding non-rectangular sub-resolution assist features;
- and
- exposing a photoresist layer on a semiconductor substrate using the lithographic processing conditions for forming the electronic device.
Dependencies are inferred from the claim text.