# US 5,352,550 A · Mask for manufacturing semiconductor devices and method of manufacture thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,352,550 A - Document ID: US5352550A - Status: Granted - Kind: A - Application number: 08/051,238 - Filed: 1993-04-23 - Granted: 1994-10-04 - Earliest claimed: 1988-11-22 - Assignees: Hitachi, Ltd. - Inventors: Yoshihiko Okamoto - Web page: https://patentgrep.com/patent/US5352550A ## CPC - G03F 1/29: Rim PSM or outrigger PSM; Preparation thereof - G03F 1/30: Alternating PSM, e.g. Levenson-Shibuya PSM; Preparation thereof - G03F 1/26: Phase shift masks [PSM]; PSM blanks; Preparation thereof - Y10S 438/948: Radiation resist - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract The present invention relates to a microminiaturization technique to achieve the miniaturization and higher integration of IC chip and to the improvement of a mask used in its manufacturing process. In other words, the phases of lights transmitted through the mask is controlled within one mask pattern. Specifically, a transparent film is formed in such a manner that it covers a mask pattern along a pattern formed by magnifying or demagnifying the mask pattern or otherwise a groove is formed in a mask substrate. A phase difference of 180.degree. is generated between the lights transmitted through the mask substrate and the transparent film or the groove, causing interference with each light to offset each other. Therefore, the pattern transferred onto a wafer has an improved resolution, being used in the invention. ## Claims ### Claim 1 An integrated circuit device projection exposure method for transferring a circuit pattern, on a first major surface of a transparent mask substrate, onto a photoresist film on an integrated circuit wafer through an optical projection system, the method comprising: (a) mounting the mask substrate on a first position in the projection system, the circuit pattern having a first light transmission region and a second light transmission region for substantially reversing the phase of a transmitted light without substantially attenuating the amplitude of the transmitted light relative to the first light transmission region, which second light transmission region substantially borders on and is adjacent to the first light transmission region to the extent that destructive interference between light beams from both vicinity sides of a boundary between the second light transmission region and the first light transmission region sufficiently takes place such that resolution is improved; (b) mounting the wafer having the resist film onto a second position in the projection system; (c) exposing the mask substrate mounted on the first position to an exposure light beam having a predetermined wavelength, and having the light beam transmit through the mask substrate in such manner that the phase of a transmitted light beam through the first light transmission region is reversed, as compared to that of a transmitted light beam through the second light transmission region, by a first phase-shifting structure disposed at one of the first and second light transmission regions; (d) focusing the transmitted light beams through the projection system so as to form a real image of the circuit pattern, on the mask substrate, onto the resist film on the wafer in such manner that an edge portion of the real image is made clear on the second light transmission region side of the first light transmission region due to destructive interference between light beams from both vicinity sides of a boundary between the first and second light transmission regions, and exposing the wafer mounted on the second position in the projection system to the focused light beams; and (e) transferring the circuit pattern, on the mask substrate, onto the resist film on the wafer through the projection system. ### Claim 2 (depends on 1) An integrated circuit device projection exposure method according to claim 1, wherein the projection system is an optical reduction projection system. ### Claim 3 (depends on 2) An integrated circuit device projection exposure method according to claim 2, wherein the first phase-shifting structure is a first transparent film having a predetermined thickness disposed on a substantially entire surface of one of the first and second light transmission regions. ### Claim 4 (depends on 1) An integrated circuit device projection exposure method according to claim 1, wherein said first phase-shifting structure is disposed on one of the first and second light transmission regions. ### Claim 5 (depends on 1) An integrated circuit device projection exposure method according to claim 1, wherein said first phase-shifting structure is disposed in one of the first and second light transmission regions. ### Claim 6 (depends on 1) An integrated circuit device projection exposure method according to claim 1, wherein the second light transmission region borders on the first light transmission region, and a width of the second light transmission region is sufficiently narrow so as not to form an independent bright real image corresponding thereto onto the photoresist film. ### Claim 7 (depends on 6) An integrated circuit device projection exposure method according to claim 6, wherein the first phase-shifting structure is a first transparent film having a predetermined thickness disposed on a substantially entire surface of one of the first and second light transmission regions. ### Claim 8 (depends on 7) An integrated circuit device projection exposure method according to claim 7, wherein the first transparent film is formed directly on the first major surface of the transparent mask substrate. ### Claim 9 (depends on 8) An integrated circuit device projection exposure method according to claim 8, wherein the first major surface of the transparent mask substrate is exposed over the entire surface of the other of the first and second light transmission regions. ### Claim 10 (depends on 7) An integrated circuit device projection exposure method according to claim 7, wherein the first transparent film is disposed on the first light transmission region. ### Claim 11 (depends on 7) An integrated circuit device projection exposure method according to claim 7, wherein the first transparent film is disposed on the second light transmission region. ### Claim 12 (depends on 11) An integrated circuit device projection exposure method according to claim 11, wherein the projection system is an optical reduction projection system. ### Claim 13 (depends on 11) An integrated circuit device projection exposure method according to claim 11, wherein the projection system is an optical reduction projection system. ### Claim 14 (depends on 6) An integrated circuit device projection exposure method according to claim 6, the circuit pattern further having: a first light shield region for shielding the exposure light beam, disposed at a side of the second light transmission region opposite a side thereof at which the first light transmission region is disposed, and bordering on the second light transmission region. ### Claim 15 (depends on 14) An integrated circuit device projection exposure method according to claim 14, wherein the first phase-shifting structure is a first transparent film having a predetermined thickness disposed on a substantially entire surface of one of the first and second light transmission regions. ### Claim 16 (depends on 15) An integrated circuit device projection exposure method according to claim 15, wherein the first transparent film is disposed on the first light transmission region. ### Claim 17 (depends on 16) An integrated circuit device projection exposure method according to claim 16, the circuit pattern further having: a second light shield region for shielding the exposure light beam, disposed at a side of the first light transmission region opposite a side thereof at which the first light shield region is disposed, and adjacent to the first light transmission region; and a third light transmission region disposed between and bordering on both the second light shield region and the first light transmission region, wherein a phase of the transmitted exposure light beam transmitted through the third light transmission region is substantially reversed as compared with the phase of the transmitted exposure light beam transmitted through the first light transmission region, by the first phase-shifting structure, so as to make an edge portion of the real image clear on the third light transmission region side of the first light transmission region, and wherein a width of the third light transmission region is sufficiently narrow so as not to form an independent bright real image thereof on the photoresist film. ### Claim 18 (depends on 16) An integrated circuit device projection exposure method according to claim 16, the circuit pattern further having: a fourth light transmission region, disposed at a side of the first light shield region opposite a side thereof at which the first light transmission region is disposed; and a fifth light transmission region narrower than the fourth light transmission region and disposed between and bordering on both the first light shield region and the fourth light transmission region, wherein the mask has a second phase-shifting structure for substantially reversing a phase of the transmitted exposure light beam transmitted through the fifth light transmission region as compared with a phase of the transmitted exposure light beam transmitted through the fourth light transmission region, so as to make an edge portion of the real image clear on the fifth light transmission region side of the fourth light transmission region, wherein the second phase-shifting structure includes a transparent film on substantially an entire surface of the fourth light transmission region, and wherein a width of the fifth light transmission region is sufficiently narrow so as not to form an independent bright real image thereof on the photoresist film. ### Claim 19 (depends on 15) An integrated circuit device projection exposure method according to claim 15, wherein the first transparent film is disposed on the second light transmission region. ### Claim 20 (depends on 19) An integrated circuit device projection exposure method according to claim 19, the circuit pattern further having: a fourth light transmission region, disposed at a side of the first light shield region opposite a side thereof at which the first light transmission region is disposed; and a fifth light transmission region narrower than the fourth light transmission region and disposed between and bordering on both the first light shield region and the fourth light transmission region, wherein the mask has a second phase-shifting structure for substantially reversing a phase of the transmitted exposure light beam transmitted through the fifth light transmission region as compared with a phase of the transmitted exposure light beam transmitted through the fourth light-transmission region, so as to make an edge portion of the real image clear on the fifth light transmission region side of the fourth light transmission region, wherein the second phase-shifting structure includes a second transparent film on substantially an entire surface of the fourth light transmission region, and wherein a width of the fifth light transmission region is sufficiently narrow so as not to form an independent bright real image thereof on the photoresist film. ### Claim 21 (depends on 20) An integrated circuit device projection exposure method according to claim 20, wherein the first and second transparent films constitute a single transparent film connected with each other within the first light shield region. ### Claim 22 (depends on 21) An integrated circuit device projection exposure method according to claim 21, wherein the first and second transparent films respectively contact the first major surface of the mask substrate within substantially an entire surface of the second and fifth light transmission regions. ### Claim 23 (depends on 19) An integrated circuit device projection exposure method according to claim 19, the circuit pattern further having: a second light shield region for shielding the exposure light beam, disposed at a side of the first light transmission region opposite a side thereof at which the first light shield region is disposed, and adjacent to the first light transmission region; and a third light transmission region disposed between and bordering on both the second light shield region and the first light transmission region, wherein the mask has a third phase-shifting structure for substantially reversing the phase of the transmitted exposure light beam transmitted through the third light transmission region as compared with the phase of the transmitted exposure light beam transmitted through the first light transmission region, so as to make an edge portion of the real image clear on the third light transmission region side of the first light transmission region, wherein the third phase-shifting structure includes a third transparent film on substantially an entire surface of the third light transmission region, and wherein a width of the third light transmission region is sufficiently narrow so as not to form an independent bright real image thereof on the photoresist film. ### Claim 24 (depends on 19) An integrated circuit device projection exposure method according to claim 19, wherein the projection system is an optical reduction projection system.