Photomask blank, photomask, and methods of manufacturing the same

• US 8,021,806 B2
• Filed: 06/29/2009
• Issued: 09/20/2011
• Est. Priority Date: 06/30/2008
• Status: Expired due to Fees

• Current Assignee: Hoya Corporation
• Original Assignee: Hoya Corporation
• Inventors: Mitsui, Hideaki, Hashimoto, Masahiro
• Primary Examiner(s): ROSASCO, STEPHEN D
• Application Number:
  US12/493,641
• Publication Number:
  US 20090325084A1
• Time in Patent Office: 813 Days
• Field of Search: 430/5, 428/428, 428/430
• US Class Current: 430/5
• CPC Class Codes: G03F 1/32 Attenuating PSM [att-PSM], e.g. halftone PSM or PSM having semi-transparent phase shift portion,; Preparation thereof
• CPC Class Codes: G03F 1/34 Phase-edge PSM, e.g. chromeless PSM; Preparation thereof
• CPC Class Codes: G03F 1/38 Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
• CPC Class Codes: G03F 1/80 Etching

Abstract

A photomask blank for manufacturing a phase shift mask having a light-transmitting substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light. An etching mask film serving as an etching mask when forming a phase shift part is provided on the front surface side, where the phase shift part is to be formed, of the substrate. A light-shielding film serving to shield exposure light is provided on the back surface side (opposite-side surface) of the substrate.

Claims

1. A photomask blank for manufacturing a phase shift mask having a light-transmitting substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light,

wherein the phase shift part is a dug-down part that is dug down from a surface of the light-transmitting substrate to a digging depth adapted to produce the predetermined phase difference with respect to exposure light transmitted through the light-transmitting substrate at a portion where the phase shift part is not provided,

the photomask blank comprising:

an etching mask film, on the digging-side surface of the light-transmitting substrate, that is made of a material being dry-etchable with a chlorine-based gas, but not dry-etchable with a fluorine-based gas, and serves as an etching mask at least until the digging depth is reached when forming the dug-down part; and

a light-shielding film, on an opposite-side surface of the light-transmitting substrate, that forms, by etching, a light-shielding part adapted to shield exposure light transmitted through the light-transmitting substrate in a region other than a transfer pattern region,

wherein the light-shielding film comprises a portion that contacts with the opposite-side surface of the light-transmitting substrate and that is formed by a material having an etch resistance with respect to the light-transmitting substrate.

3. The photomask blank according to claim 1 or 2, wherein the light-shielding film is made of a material being wet-etchable with an etchant to which the light-transmitting substrate has etching resistance.

4. The photomask blank according to claim 1 or 2, wherein the light-shielding film is made of a material mainly containing one of chromium, chromium nitride, chromium oxide, chromium oxynitride, and chromium oxycarbonitride.

5. The photomask blank according to claim 1 or 2, wherein the light-shielding film has a thickness of 60 nm to 100 nm.

6. The photomask blank according to claim 1 or 2, wherein the etching mask film is made of a material mainly containing one of chromium, chromium nitride, chromium oxide, chromium oxynitride, and chromium oxycarbonitride.

7. The photomask blank according to claim 1 or 2, wherein the etching mask film has a thickness of 5 nm to 40 nm.

10. A photomask manufactured using the photomask blank according to claim 1 or 2.

11. A photomask manufacturing method using the photomask blank according to claim 1, the method comprising the steps of:

etching the light-shielding film using a resist film pattern as a mask, thereby forming the light-shielding part in the region other than the transfer pattern region;

dry-etching the etching mask film using a resist film pattern as a mask, thereby forming an etching mask film pattern; and

dry-etching the light-transmitting substrate using the etching mask film pattern as a mask, thereby forming the dug-down part that is dug down from the surface of the light-transmitting substrate to the digging depth adapted to produce the predetermined phase difference.

13. The photomask blank according to claim 1 or 2, wherein each of the etching mask film and the light-shielding film is formed of a material containing the same metal.

14. The photomask blank according to claim 1 or 2, wherein the light-shielding film is formed of a material mainly containing tantalum.

2. A photomask blank for manufacturing a phase shift mask having a light-transmitting substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light,

wherein the phase shift part is a phase shift film adapted to give a predetermined phase change amount to the transmitted exposure light,

the photomask blank comprising:

an etching mask film, on a surface of the phase shift film, that is made of a material being dry-etchable with a chlorine-based gas, but not dry-etchable with a fluorine-based gas, and serves as an etching mask at least until a transfer pattern is formed in the phase shift film by dry etching with a fluorine-based gas; and

a light-shielding film, on an opposite-side surface of the light-transmitting substrate, that forms, by etching, a light-shielding part adapted to shield exposure light transmitted through said light-transmitting substrate in a region other than a transfer pattern region,

wherein the light-shielding film comprises a portion that contacts with the opposite-side surface of the light-transmitting substrate and that is formed by a material having an etch resistance with respect to the light-transmitting substrate.

8. The photomask blank according to claim 2, wherein the phase shift film is made of a material mainly containing one of molybdenum silicide, molybdenum silicide nitride, molybdenum silicide oxide, and molybdenum silicide oxynitride.

9. The photomask blank according to claim 2, wherein the phase shift film comprises:

a phase adjusting layer made of a material mainly containing silicon oxide or silicon oxynitride; and

a transmittance adjusting layer made of a material mainly containing tantalum or a tantalum-hafnium alloy.

12. A photomask manufacturing method using the photomask blank according to claim 2, the method comprising the steps of:

etching the light-shielding film using a resist film pattern as a mask, thereby forming the light-shielding part in the region other than the transfer pattern region;

dry-etching the etching mask film using a resist film pattern as a mask, thereby forming an etching mask film pattern; and

dry-etching the phase shift film using the etching mask film pattern as a mask, thereby forming a phase shift film pattern.

15. A phase shift mask, comprising:

a light-transmitting substrate;

a phase shift part formed in a transfer pattern region of a surface of the light-transmitting substrate and adapted to give a predetermined phase difference to transmitted exposure light; and

a light-shielding part formed on an opposite-side surface of the light-transmitting substrate and adapted to shield exposure light transmitted through the light-transmitting substrate in a region other than the transfer pattern region;

wherein

the light-shielding part is made of the light-shielding film, and the light-shielding film comprises a portion that contacts with the opposite-side surface of the light-transmitting substrate and that is formed by a material having an etch resistance with respect to the light-transmitting substrate.

16. The phase shift mask according to claim 15, wherein the phase shift part comprises a dug-down part that is dug down from a surface of the light-transmitting substrate to a digging depth adapted to produce the predetermined phase difference with respect to exposure light transmitted through the light-transmitting substrate at a portion where the phase shift part is not provided.

17. The phase shift mask according to claim 15, wherein the phase shift part comprises a phase shift film adapted to give a predetermined phase change amount to the transmitted exposure light.

18. The phase shift mask according to claim 15, wherein the light-shielding film is made of a material mainly containing one of chromium, chromium nitride, chromium oxide, chromium oxynitride, and chromium oxycarbonitride or a material mainly containing tantalum.