Precision alignment of photographic masks

Claim 2

A method as defined by claim 1 wherein said photoresist is a positive photoresist.

Claim 3

A negative photographic mask divided into a plurality of individual areas employed in the formation of images in an equal plurality of individual areas on a member, the improvement comprising: certain of saId areas having transparent patterns on an opaque background; and certain others of said areas having opaque key images on transparent background whereby, those individual areas on the member aligned with said transparent backgrounds having opaque key images are used for alignment purposes.

Claim 4

A negative photographic mask being divided into a plurality of individual areas, and employed in the formation of images required in a multiplicity of device units being fabricated in a plurality of individual areas on a semiconductor material, the improvement comprising: certain of said areas having transparent patterns on an opaque background; and certain others of said areas comprising opaque key images on transparent background whereby, those individual areas on the body of semiconductor material aligned with said areas of said mask having transparent backgrounds and opaque key images are used for alignment purposes.

Claim 5

The negative photographic masks as recited in claim 5, wherein; said opaque key images being of the same size ans shape as the transparent patterns.

Claim 7

The method of aligning a subsequent photographic mask with an array of patterns formed on a member by a first mask, as recited in claim 7, and further including, prior to the step of providing a second layer of negative photoresist, the step of: etching at least said surface of said member exposed by the removal of said photoresist aligned with said opaque keys whereby, said pattern on said member is an etched out area.

Claim 8

In the manufacture of semiconductor devices in a major surface of a body of semiconductor material requiring a plurality of process steps, each of which performs at least a single step in the process, and each of which is closely related to at least one other step of the process, requiring the predetermined alignment of each step, the method of aligning a subsequent photographic mask used for controlling one step in the process with a pattern formed by a first mask on the major surface, comprising the steps of: providing a body of semiconductor material having at least a major surface and coating said major surface with a negative photoresist composition; providing a first negative photographic mask divided into a plurality of individual areas and certain of said areas having transparent patterns on an opaque background, and certain of said remaining areas having opaque key images on transparent backgrounds; exposing to light, transmitted by said transparent patterns and backgrounds of said first mask, said photoresist which is covering said member and developing said photoresist aligned under said transparent patterns and backgrounds; removing said unexposed portions, including such photoresist aligned with said opaque keys, of said photoresist leaving said transparent pattern and transparent backgrounds; providing a second layer of photoresist over said major surface; providing a second negative photographic mask divided into a plurality of individual areas which correspond to said areas of said first mask, and certain of said areas having transparent patterns on an opaque background corresponding to similar areas in said first mask, and certain of said remaining areas having opaque key images on transparent backgrounds corresponding to similar areas in said first mask; aligning said opaque key images on said second mask with said patterns on said major surface through said transparent background associated with each such key image on said second mask; exposing to light, transmitted by said second mask, said second layer of photoresist which is covering said major surface and developing said second layer of photoresist aligned under said transparent pattern and backgrounds; and removing said unexposed portions, including such photoresist aligned with said opaque keys, of said photoresist leaving said transparent patterns and transparent backgrounds on said major surface.

Claim 9

The method of aligning a subsequent photographic mask with an array of patterns formed on a major surface of semiconductor material by a first mask, as recited in claim 7, and further including, prior to the step of providing the second layer of photoresist, the step of: etching at least said surface of said member exposed by the removal of said photoresist aligned with said opaque keys whereby, said pattern on said major surface is an etched out area.

Claim 11

The method of aligning a subsequent photographic mask with an array of patterns formed on a member by a first mask, as recited in claim 11, and further including, prior to the step of providing a second layer of positive photoresist, the step of: etching at least said surface of said member exposed by the removal of said positive photoresist aligned with said transparent background whereby, said pattern on said member is a raised area protected by said positive photoresist and surrounded by an etched out area.

Claim 12

In the manufacture of semiconductor devices in a major surface of a body of semiconductor material requiring a plurality of process steps, each of which performs at least a single step in the process, and each of which is closely related to at least one other step of the process, requiring the predetermined alignment of each step, the method of aligning a subsequent photographic mask used for controlling one step in the process with a pattern formed by a first mask on the major surface, comprising the steps of: providing a body of semiconductor material having at least a major surface and coating said major surface with a positive photoresist composition; providing a first negative photographic mask divided into a plurality of individual areas and certain of said areas having transparent patterns on an opaque background, and certain of said remaining areas having opaque key images on transparent backgrounds; exposing to light, transmitted by said transparent patterns and backgrounds of said first mask, said positive photoresist which is covering said member and developing said photoresist aligned under said transparent patterns and backgrounds; removing said exposed portions, including such photoresist aligned with said transparent patterns and transparent backgrounds of said photoresist, leaving said photoresist aligned under said opaque key images and opaque backgrounds on said major surface; providing a second layer of positive photoresist over said major surface; providing a second negative photographic mask divided into a plurality of individual areas which correspond to said areas of said first mask, and certain of said areas having transparent patterns on an opaque background corresponding to similar areas in said first mask, and certain of said remaining areas having opaque key images on transparent backgrounds corresponding to similar areas in said first mask; aligning said opaque key images on said second mask with said patterns on said major surface through said transparent background associated with each such key image on said second mask; exposing to light, transmitted by said second mask, said second layer of positive photoresist which is covering said major surface and developing said second layer of positive photoresist aligned under said transparent pattern and backgrounds; and removing said exposed portions including such photoresist aligned with said opaque keys, of said photoresist leaving said transparent patterns and transparent backgrounds on said major surface transparent patterns and transparent backgrounds, of said positive photoresist leaving opaque key images and opaque backgrounds,.

Claim 13

The method of aligning a subsequent photographic mask with an array of patterns formed on a major surface of a semiconductor material by a first mask, as recited in claim 13, and further including, prior to the step of providing the second layer of positive photoresist, the step of: etching at least said surface of said member exposed by the removal of said positive photoresist alignEd with said transparent background whereby, said pattern on said major surface is a raised area protected by said positive photoresist and surrounded by an etched out area.

Claim 14

A method as recited in claim 1, wherein said key images occupy positions of the same array and being the same size and shape as said transparent pattern.