Method of electron beam exposure

Claim 1

A method of electron beam exposure, which automatically effects the focusing of an electron beam by utilizing registration marks on the surface of a specimen, characterized in that plural sets of reference values for setting the conditions for electron beam exposure are obtained in relation to a plurality of sizing marks which are successively arrayed at positions in the vicinity of the pattern area of the specimen, the distance between said plurality of sizing marks in the direction in which the electron beam flows is so selected as to be greater than the magnitude of variation in position on the surface of said specimen, said plural sets of reference values for setting the exposure conditions are stored in a central processing unit, exposing said specimen to an electron beam, detecting bounced signals from the registration marks on the specimen during the actual beam exposure, and setting the exposure conditions corresponding to the registration marks on the surface of the specimen being fed from said central processing unit responsive to variation in focusing which deviates from said reference values for setting exposure conditions when said specimen is being exposed to the electron beam.

Claim 2

A method of electron beam exposure, which automatically effects the focusing of an electron beam by utilizing registration marks on the surface of a specimen, characterized in that plural sets of reference values for setting the conditions for electron beam exposure are obtained in relation to a plurality of sizing marks which are successively arrayed at positions in the vicinity of the pattern area of the specimen, the distance between said plurality of sizing marks in the direction in which the electron beam flows is so selected as to be greater than the magnitude of variation in position on the surface of said specimen, said plural sets of reference values for setting the exposure conditions are stored in a central processing unit, exposing said specimen to an electron beam, detecting bounced signals from the registration marks on the specimen during the actual beam exposure, and setting the exposure conditions corresponding to the registration marks on the surface of the specimen being fed from said central processing unit responsive to variation in focusing which deviates from said reference values for setting exposure conditions when said specimen is being exposed to the electron beam.

Claim 5

A method of automatically focusing an electron beam while exposing by said electron beam a semiconductor device which is not strictly flat comprising: (a) providing registration marks in a pattern area on the surface of a semiconductor specimen; (b) further providing a plurality of sizing marks adjacent to the pattern area, wherein the distance between said plurality of sizing marks and the direction in which the electron beam flows is so selected as to be greater than the magnitude of variation in vertical position of the upper surface of said specimen; (c) obtaining exposure reference values by using said plurality of sizing marks; (d) storing said reference values in a central processing unit; (e) exposing said specimen to an electron beam; (f) detecting bounced signals from the registration marks on the specimen during the actual beam exposure; (g) determining the depth of the registration mark in accordance with said detected bounced signals; (h) calculating exposure condition values corresponding to the depth of the registration mark using said determined depth; and (i) carrying out an electron beam exposure on said specimen in accordance with said calculated exposure condition values.

Claim 6

A method of automatically focusing an electron beam while exposing by said electron beam a semiconductor device which is not strictly flat comprising: (a) providing registration marks in a pattern area on the surface of a semiconductor specimen; (b) further providing a plurality of sizing marks adjacent to the pattern area, wherein the distance between said plurality of sizing marks and the direction in which the electron beam flows is so selected as to be greater than the magnitude of variation in vertical position of the upper surface of said specimen; (c) obtaining exposure reference values by using said plurality of sizing marks; (d) storing said reference values in a central processing unit; (e) exposing said specimen to an electron beam; (f) detecting bounced signals from the registration marks on the specimen during the actual beam exposure; (g) determining the depth of the registration mark in accordance with said detected bounced signals; (h) calculating exposure condition values corresponding to the depth of the registration mark using said determined depth; and (i) carrying out an electron beam exposure on said specimen in accordance with said calculated exposure condition values.