US 4,394,437 AGranted

Process for increasing resolution of photolithographic images

AssigneeInternational Business Machines Corporation

InventorsAlbert S. Bergendahl, Mark C. Hakey, John P. Wilson

Life of this patent

Estimating the term…

Loading patent…

Abstract

The present invention describes conformable masking techniques which can be successfully made and used in a practical manufacturing environment while providing increased resolution of photolithographic images while eliminating all manner of defects that might presently be encountered in the masks currently used in the semiconductor industry. In the present invention a body is first coated with a positive photoresist overcoated with a conformable mask which is exposed through a fixed mask and developed to define a replica of the fixed mask, together with all its defects. The underlying photoresist is then exposed to light through developed openings in the conformable mask. The conformable mask is then stripped and a new conformable mask laid down. This new conformable mask is now exposed through a second fixed mask having the same image as the first fixed mask, but presumably with different defects and developed to define a replica of the second mask. The underlying photoresist is again exposed through the second conformable mask and developed. As a result of using two independently defined conformable masks clear image defects in the fixed masks are prevented from being reproduced in the underlying photoresist and are not doubly exposed. Only desired regions in the underlying photoresist are doubly exposed.

Claims9

Dependent claims

A method of developing relief images in a first layer of photoresist comprising the steps of:

applying a first layer of photoresist, sensitive to a selected wavelength of light, a selected solvent and a selected developer, to the surface of a substrate;
applying a second layer of photoresist over said first layer;
said second layer of photoresist being sensitive to a wavelength of light, a solvent and a developer different from said selected wavelength, solvent and developer to which said first layer of photoresist is sensitive,
forming a first relief image in said second layer of photoresist by exposure through a fixed mask having an image thereon,
partially exposing said first layer of photoresist using said second layer as a mask,
removing said second layer of photoresist,
applying a third layer of photoresist over said first layer, said third layer of photoresist being sensitive to a wavelength of light, a solvent and a developer different from said selected wavelength, solvent and developer to which said first layer of photoresist is sensitive,
forming a second relief image in said third layer substantially identical to the first relief image formed in said second layer by exposure through a second mask having the same image as the said first mask but having different defects thereon,
re-exposing said first layer of photoresist using said third layer as a mask to fully expose only those partially exposed portions of said first layer thereof corresponding to areas being exposed by said third layer;
and
developing a relief image in said first layer of photoresist, said relief image having openings extending to the surface of said substrate only in said fully exposed areas.

8 more elements

A method of developing relief images in a first layer of photoresist comprising the steps of:

applying a first layer of photoresist sensitive to a selected wavelength of light, a selected solvent and a selected developer to a substrate,
applying a second layer of photoresist over said first layer;
said second layer of photoresist being sensitive to a wavelength of light, solvent and developer different from that to which said first layer of photoresist is sensitive,
forming a relief image in said second layer having openings extending through said second layer of photoresist by exposure through a first fixed mask having a predetermined pattern thereon,
partially exposing said first layer of photoresist through said second layer;
removing said second layer of photoresist,
applying a third layer of photoresist over said first layer said second layer of photoresist being sensitive to a wavelength of light, solvent and developer different from that to which said first layer of photoresist is sensitive;
forming a relief image in said third layer substantially identical to the first relief image formed in said second layer and having openings extending through said third layer of photoresist substantially overlying said partially exposed regions of said first layer of photoresist by exposure through a second fixed mask having the same pattern as said first fixed mask but having different defects thereon,
re-exposing said first layer of photoresist to further expose only those partially exposed portions thereof corresponding to the openings in the second relief image;
removing said third layer of photoresist;
applying a fourth layer of photoresist over said first layer said fourth layer of photoresist being sensitive to a wavelength of light, solvent and developer different from that to which said first layer of photoresist is sensitive;
forming a third relief image in said fourth layer having openings extending through said fourth layer of photoresist through exposure to a third mask having the same pattern as said first and second fixed masks, but having different defects thereon,
re-exposing said first layer of photoresist to further expose those exposed portions thereof corresponding to the openings in the third relief image;
removing the fourth layer of photoresist,
developing a relief image having openings extending through said first layer of photoresist, said openings being defined by said multiply exposed areas.

12 more elements

Dependencies are inferred from the claim text.