Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Patent
1996-01-16
1998-11-10
Baxter, Janet C.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
430311, 430319, 355 55, G03C 500, G03B 2752
Patent
active
058341609
ABSTRACT:
The present inventors have discovered that fine patterns of metal or insulator can be formed on printed circuit board using conventional lithographic steppers with inverted projection lenses. The inverted projection lenses act as enlargement lenses rather than reducing lenses and exhibit a large depth of focus sufficient to accommodate the deviations of PC board from planarity. The inverted lens reduces the size of the image needed at the mask, permitting multiple mask levels to be combined on a single glass. This reduces the cost of the mask set and permits the use of smaller glass masks having greater accuracy and dimensional stability than the convention mylar masks used for PC board.
By inverting the projection lenses on near-obsolete steppers, applicants were able to form metal patterns on PC board of finer dimension than heretofore reported. Inverting a 5.times. ZEISS lens on a GCA 6300A stepper, applicants were able to form vias of less than 25 .mu.m diameter, pattern metal lines and spaces of less than 25 .mu.m, and obtain overlay registration accuracy of less than 25 .mu.m. The field size was larger than 1 in.sup.2, and the depth of focus was greater than 50 .mu.m.
REFERENCES:
patent: 4702994 (1987-10-01), Rendulic et al.
patent: 4801977 (1989-01-01), Ishizaka et al.
Ferry Alan E.
Han Byung Joon
Lau Maureen Yee
Scruton, Sr. Robert T.
Tai King Lien
Ashton Rosemary
Baxter Janet C.
Lucent Technologies - Inc.
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