EP0433467A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Fabrication of complementary patterns for exposing semiconductor chips with self-supporting masks
Assignee: International Business Machines Corp
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Filing: 1989-12-18
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Granted: —
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Expires: 2009-12-18
Abstract
Abstract For the fabrication of semiconductor chips with an increasing number of electrical elements it is necessary that the geometry of the elements becomes smaller and smaller. For that purpose, lithographic techniques have been developed using x-rays, electron or ion beams. Especially for particle beams, self-supporting masks are stringent with the consequence that it is not possible to fabricate e.g. a ring-shaped structure with one mask. This so-called mask stencil problem is solved by exposing the chip with two complementary masks. The present application relates to a method for automatically splitting one layout into two complementary patterns for said two masks. The method determines all corners of said layout which extend into a hole representing area of said masks. A stability criterion is carried out for said corners, with the consequence that only instable corners are used for cutting said hole representing area into sections. Subsequently said sections are distributed onto said two patterns alternatively.
Inventors
- 👤 Helmut Dr. Dipl.-Phys. Engelke
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 06:44
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/20; H; H10; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2045; H10P76/2047
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
178 words
Method of splitting a layout of an electrical circuit into two complementary patterns, said patterns being used in connection with self-supporting masks for exposing semiconductor chips, said layout comprising edges and corners encircling a number of areas which represent either a hole or no hole in said masks, said method comprising the following steps: determining all corners of said layout which extend into said hole representing areas as inside corners, all other corners of said layout which extend into said no hole representing areas being outside corners, assigning a stability value to each of said inside corners which is a function of the lengths of the adjacent edges of said inside corners, comparing each of said stability values with a stability limit function which is dependant on the physical characteristics of said masks, partitioning each of said hole representing areas into sections by providing cutting lines running from any of those inside corners with said assigned stability value below said stability limit function to one of said edges, and establishing said two patterns by distributing said sections alternatively.
Claim 2
Dependent Claim
178 words
Method of splitting a layout of an electrical circuit into two complementary patterns, said patterns being used in connection with self-supporting masks for exposing semiconductor chips, said layout comprising edges and corners encircling a number of areas which represent either a hole or no hole in said masks, said method comprising the following steps: determining all corners of said layout which extend into said hole representing areas as inside corners, all other corners of said layout which extend into said no hole representing areas being outside corners, assigning a stability value to each of said inside corners which is a function of the lengths of the adjacent edges of said inside corners, comparing each of said stability values with a stability limit function which is dependant on the physical characteristics of said masks, partitioning each of said hole representing areas into sections by providing cutting lines running from any of those inside corners with said assigned stability value below said stability limit function to one of said edges, and establishing said two patterns by distributing said sections alternatively.
Claim 3
Dependent Claim
148 words
Method according to claim 1, wherein said step of assigning a stability value to each of said inside corners comprises, in the case of a number of inside and outside corners being arranged in a row in any order whatever: determining those two outside corners of said row which are arranged in both directions of said row adjacent to the last inside corner of said row, establishing a new row of corners from one of said two outside corners to the other and including all outside corners of said former row, said corners of said new row being connected by hull edges, repeating said steps of determining said two outside corners and establishing said new row of corners until said new row is free of inside corners, and said hull edges and said corners of said new rows being the subject matter of assigning a stability value, respectively.
Claim 4
Dependent Claim
122 words
Method according to claim 1 or 2, wherein said step of assigning a stability value to each of said inside corners comprises, in the case of one or more inside corners being arranged in a row one after the other in between two outside corners: adding the lengths of the two adjacent edges of said inside corner to a sum, if only one inside corner is arranged between said two outside corners, or adding all lengths of all adjacent edges of said inside corners to a sum, if a number of inside corners are arranged in a row one after the other between said two outside corners, ascertaining the distance of said two outside corners, and dividing said distance by said sum.
Claim 5
Dependent Claim
20 words
Method according to claim 3, wherein said stability limit function increases, when said distance of said two outside corners increases.
Claim 6
Dependent Claim
93 words
Method according to any one of claims 1 to 4, wherein said step of partitioning each of said hole representing areas into sections comprises: planning pairs of rectangular cutting lines running from any one of said inside corners to one of said edges, respectively, assembling one or more sets of cutting lines which incorporate one cutting line of each of said pairs of cutting lines, respectively, and in which said cutting lines do not intersect, and selecting that set of cutting lines which has the shortest length of all cutting lines summed up.
Claim 7
Dependent Claim
67 words
Method according to any one of claims 1 to 5, wherein said step of partitioning each of said hole representing areas into sections comprises: determining all sections with a surface exceeding a given value, and partitioning each of said sections into sub-sections by providing additional cutting lines which run between two of said cutting lines of said sections and which do not intersect any other cutting line.
Claim 8
Dependent Claim
53 words
Method according to any one of claims 1 to 6, wherein said step of partitioning each of said hole representing areas into sections comprises: providing an overlap for each of said cutting lines, said overlap expanding from one of said sections, which is adjacent to said cutting line, into said other adjacent section.
Claim 9
Dependent Claim
30 words
Method according to claim 7, wherein said step of providing an overlap comprises: determining the width of said overlap as a function of the length of the accompanying cutting line.
Claim 10
Dependent Claim
58 words
Method according to any one of claims 1 to 8, wherein said step of establishing said two patterns comprises: determining the number of all sections or the number of sections surrounding a hole, examining if said number is divisible by two and providing an odd number of additional cutting lines if said number is not divisible by two.
References Cited (Backward Citations)
No citation records indexed.
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