EP0496159A2
Expired / Lapsed
EP
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Partitioning method for E-beam lithography
Assignee: International Business Machines Corp
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Filing: 1991-12-11
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Granted: —
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Expires: 2011-12-11
Abstract
Abstract A method of partitioning design shapes, in an E-beam lithography system, into subshapes such that a constant dose may be applied to an E-team sensitive resist within each subshape. Within each subshape the constant dose corresponds to an approximation to an indicator function, indicative of the degree of the proximity effect, such as the effective exposure of the resist from backscattered electrons or the required dose. The error of the approximation is equal to a predetermined value for each subshape, and can depend upon the position of the subshape within the shape and the influence of errors in the applied dose at that position on the position, on development, of the edge of the shape.
Inventors
- 👤 Abraham Zvi Meiri
- 👤 Dov Ramm
- 👤 Uzi Shvadron
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 12:19
CPC Classifications
B; B82; B82Y; B82Y10/00; H; H01; H01J; H01J37/00; H01J37/30; H01J37/317; H01J37/3174; B82Y40/00; H01J37/302; H01J37/3023; H01J37/3026; H01J2237/00; H01J2237/30; H01J2237/317; H01J2237/3175; H01J2237/31761; H01J2237/31764; H01J2237/31769
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
134 words
Method of partitioning, in an E-beam lithography system, a design pattern, comprising at least one design shape, into a plurality of subshapes to each of which a respective constant E-beam dose is applied, the method comprising the steps of: (a) determining, at a plurality of points on the design, an indicator field indicative of the magnitude of the proximity effect; (b) determining the boundaries of the subshapes; (c) assigning a constant indicator value to each subshape; and (d) assigning the respective constant E-beam dose to each subshape based on the value of the constant indicator value, the boundary determination and the constant indicator value assignment being such that, within each subshape, the constant indicator value represents an approximation to the indicator field, the error of the approximation being substantially equal to a predetermined value.
Claim 2
Dependent Claim
41 words
Method as claimed in claim 1 wherein the predetermined value for each subshape is chosen in dependence on the indicator field so as to provide, on development, a substantially constant error in the location of the edge of each design shape.
Claim 3
Dependent Claim
17 words
Method as claimed in claim 1 or claim 2 wherein the indicator field is the electron backscatter.
Claim 4
Dependent Claim
26 words
Method as claimed in claim 1 or claim 2 wherein the indicator field is the E-beam dose required to produce, on development, the required design pattern.
Claim 5
Dependent Claim
127 words
Method as claimed in any preceding claim wherein the determination of the boundaries of the subshapes comprises the steps of: (b1) dividing the design shapes into rectangular sleeves and inner rectangular areas, each inner rectangular area being surrounded by rectangular sleeves; (b2) determining a one-dimensional representative indicator function along the length of each of the sleeves, the one-dimensional indicator function being an approximation to the indicator field within the sleeve; (b3) dividing the sleeves into subshapes, along their length, so that the maximum deviation of the one-dimensional representative indicator function, within each subshape, is equal to twice the predetermined value, and wherein the constant indicator value for each subshape is assigned to be the mid-point of the range of the one-dimensional representative indicator function within the subshape.
Claim 6
Dependent Claim
39 words
Method as claimed in claim 5 comprising the step between the steps (b2) and (b3) of determining the predetermined value from the one-dimensional indicator function so that, on development, the location of the shape edge lies within predetermined limits.
Claim 7
Dependent Claim
38 words
Method as claimed in claim 5 or claim 6 comprising the additional step of dividing each internal rectangular area into rectangular intermediate sleeves and an inner rectangular area and repeating steps (b2) and (b3) for the intermediate sleeves.
Claim 8
Dependent Claim
79 words
Method as claimed in any of claims 5 to 7 wherein the one-dimensional representative indicator function is chosen as a weighted sum of the indicator value at the edge of the sleeve and the average of the indicator field across the sleeve, the weights in the weighted sum being such that, on development, the error in the position of the edge of the shape introduced by the substitution of the indicator field by the one-dimensional indicator function is minimised.
Claim 9
Dependent Claim
16 words
Proximity correction method for E-beam lithography comprising a partitioning method as claimed in any preceding claim.
Claim 10
Dependent Claim
131 words
Partitioning apparatus for partitioning, in a E-beam lithography system, a design pattern comprising at least one design shape into a plurality of subshapes to each of which a respective constant E-beam dose is applied, the partitioning apparatus comprising: logic for determining, at a plurality of points on the design, values of an indicator field indicative of the magnitude of the proximity effect; logic for determining the boundaries of the subshapes; logic for assigning a constant indicator value to each subshape; and logic for assigning the respective constant E-beam dose to each subshape based on the value of the constant indicator value, wherein, within each subshape, the constant indicator value represents an approximation to the indicator field, the error of the approximation being substantially equal to a predetermined value for the subshape.
References Cited (Backward Citations)
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