Alignment method and apparatus

Claim 2

An alignment method for aligning a substrate having at least one alignment mark, said substrate having at least one film covering the at least one alignment mark, comprising the steps of: (a) locally removing the at least one film covering the at least one alignment mark so as to expose the at least one alignment mark; (b) detecting position coordinates of said at least one alignment mark on the substrate, the detecting being performed with the at least one alignment mark exposed, the locally removing being performed prior to the detecting; and (c) carrying out alignment of said substrate on the basis of said position coordinates.

Claim 3

An alignment method according to claim 1, wherein the locally removing is performed by a gas assisted etching method using an energy beam.

Claim 4

An alignment method according to claim 2, wherein said energy beam is a laser beam, an electron beam or an ion beam.

Claim 5

An alignment method according to claim 3, wherein said substrate is a semiconductor wafer.

Claim 6

An alignment method according to claim 1, wherein, in said step of detecting, an alignment light beam is applied directly to the at least one alignment mark.

Claim 7

An alignment method according to claim 5, wherein the alignment light beam is a laser beam.

Claim 8

An alignment method according to claim 1, wherein the at least one alignment mark is a projection formed on the substrate.

Claim 9

An alignment method according to claim 1, wherein the at least one alignment mark is a recess.

Claim 10

An alignment method according to claim 1, wherein said at least one film includes two films, an overlying film covering the at least one alignment mark and a photoresist film on the overlying film.

Claim 11

An alignment method according to claim 9, wherein said overlying film is a metal film.

Claim 12

An alignment method according to claim 1, wherein an alignment light beam is used for said detecting, and wherein the at least one film is opaque to the alignment light beam.

Claim 13

An alignment method according to claim 1, wherein the substrate has a plurality of alignment marks, with at least one film covering the plurality of alignment marks, and wherein, in the step of locally removing, the at least one film covering the plurality of alignment marks is simultaneously removed from the plurality of alignment marks so as to simultaneously expose the plurality of alignment marks.

Claim 14

An alignment method according to claim 1, wherein the step of locally removing is performed by etching, and the etching is monitored so as to detect an etching terminal point.

Claim 15

An alignment method according to claim 1, wherein the step of carrying out alignment is performed with an alignment light beam, inside a reduction exposure apparatus where a circuit pattern on a mask is to be transferred onto a photoresist film on the substrate by exposing the substrate to an exposure light beam.

Claim 16

An alignment method according to claim 14, wherein the wavelength of the exposure light beam is shorter than that of the alignment light beam.

Claim 17

An alignment method according to claim 15, wherein the alignment light beam is within a range of visible light.

Claim 18

An alignment method according to claim 16, wherein the at least one film covering the at least one alignment mark includes an overlying film covering the at least one alignment mark and a photoresist film covering the overlying film.

Claim 19

An alignment method according to claim 17, wherein the overlying film is an inorganic film made of a material selected from a group consisting of silicon oxide, polysilicon and aluminum.

Claim 20

An alignment method according to claim 17, wherein the overlying film is opaque to the alignment light beam.

Claim 21

An alignment method according to claim 17, wherein the overlying film is a metal film.

Claim 22

An alignment method according to claim 20, wherein the metal film is made of aluminum or an alloy of aluminum.

Claim 23

An alignment method according to claim 1, wherein the at least one film covering the at least one alignment mark includes an overlying film covering the alignment mark and a photoresist film covering the overlying film, and wherein the overlying film is removed by a gas assisted etching method using an energy beam.

Claim 24

An alignment method according to claim 22, wherein the energy beam is selected from a group consisting of a laser beam, an electron beam, and an ion beam.

Claim 25

A reduction exposure method for transferring a pattern on a mask onto a photoresist film on a major surface of a semiconductor wafer having at least one alignment mark on the semiconductor wafer, the at least one alignment mark being covered by at least two films including an overlying film, to be patterned, and the photoresist film, comprising the steps of: (a) locally removing the photoresist film at a location over and around an alignment mark; (b) locally removing the overlying film, to be patterned, at a location over and around the alignment mark; (c) after steps (a) and (b), detecting a position of the alignment mark in an exposure apparatus by irradiating the alignment mark with an alignment light beam, while the alignment mark is exposed directly to the alignment light beam; (d) in accordance with the result of detecting the position of the alignment mark, carrying out the alignment of the semiconductor wafer; and then (e) exposing the semiconductor wafer in an exposure apparatus to an exposure light beam shorter in wavelength than the alignment light beam, the semiconductor wafer being exposed through the mask so as to transfer the pattern on the mask onto the photoresist film on the major surface of the semiconductor wafer.

Claim 26

A reduction exposure method for transferring a pattern on a mask onto a photoresist film on a major surface of a semiconductor wafer having at least one alignment mark on the semiconductor wafer, the at least one alignment mark being covered by at least two films including an overlying film, to be patterned, and the photoresist film, comprising the steps of: (a) locally removing the photoresist film at a location over and around an alignment mark; (b) locally removing the overlying film, to be patterned, at a location over and around the alignment mark; (c) after steps (a) and (b), detecting a position of the alignment mark in an exposure apparatus by irradiating the alignment mark with an alignment light beam, while the alignment mark is exposed directly to the alignment light beam; (d) in accordance with the result of detecting the position of the alignment mark, carrying out the alignment of the semiconductor wafer; and then (e) exposing the semiconductor wafer in an exposure apparatus to an exposure light beam shorter in wavelength than the alignment light beam, the semiconductor wafer being exposed through the mask so as to transfer the pattern on the mask onto the photoresist film on the major surface of the semiconductor wafer.

Claim 27

A reduction exposure method according to claim 24, wherein the alignment light beam is within the range of visible light.

Claim 28

A reduction exposure method according to claim 25, wherein the overlying film is an inorganic film of a material selected from a group consisting of silicon oxide, polysilicon and aluminum.

Claim 29

A reduction exposure method according to claim 24, wherein the overlying film is substantially opaque to the alignment light beam.

Claim 30

A reduction exposure method according to claim 27, wherein the overlying film is a metal film.

Claim 31

A reduction exposure method according to claim 28, wherein the metal film is made of aluminum or an alloy of aluminum.

Claim 32

A reduction exposure method according to claim 24, wherein the overlying film is removed by a gas assisted etching method using an energy beam.

Claim 33

A reduction exposure method according to claim 30, wherein the energy beam is selected from a group consisting of a laser beam, an electron beam and an ion beam.