REFLECTION-TYPE MASK AND METHOD OF MAKING THE REFLECTION-TYPE MASK

• US 20090220869A1
• Filed: 03/03/2009
• Published: 09/03/2009
• Est. Priority Date: 03/03/2008
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: TAKAI, Kosuke
• Granted Patent: US 7,932,002 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G03F 1/24 Reflection masks; Preparation thereof
• CPC Class Codes: G03F 1/26 Phase shift masks [PSM]; PSM blanks; Preparation thereof

Abstract

To provide a reflection-type mask having a reduced shadowing effect, capable of phase shift exposure and having a shading frame of sufficient shading performance. The mask includes a substrate 11, a multilayer reflective film 12 which is formed above the substrate 11, and which reflects exposure light, a first photoabsorber layer 15 which is formed above the multilayer reflective film 12, and which absorbs the exposure light, a circuit pattern region 16 constituted, in conformity with a predetermined circuit pattern, of an opening formed as a result of removal of the first photoabsorber layer 15 and an absorbing portion where the first photoabsorber layer remains, and a shading region 18 having a reflectance with respect to the exposure light lower than that in the absorbing portion of the circuit pattern region 16.

Claims

1. A reflection-type mask comprising:

a substrate;

a multilayer reflective film which is formed above the substrate, and which reflects exposure light;

a first photoabsorber layer which is formed above the multilayer reflective film, and which absorbs the exposure light;

a circuit pattern region constituted, in conformity with a predetermined circuit pattern, of an opening formed as a result of removal of the first photoabsorber layer, and an absorbing portion where the first photoabsorber layer remains; and

a shading region having a reflectance with respect to the exposure light lower than that in the absorbing portion of the circuit pattern region.

2. The reflection-type mask according to claim 1, wherein the absorbing portion of the circuit pattern region radiates, as first reflection light, a predetermined proportion of light in the exposure light applied to the absorbing portion while phase-shifting the first reflection light so that the first reflection light has a phase difference of a predetermined value from second reflection light reflected by the multilayer reflective film and radiated from the opening in the exposure light applied to the opening.

3. The reflection-type mask according to claim 2, wherein the predetermined proportion is 1 to 20% and the predetermined value is 175°

to 185°

.

4. The reflection-type mask according to claim 1, wherein the shading region is a shading frame provided so as to surround the circuit pattern region.

5. The reflection-type mask according to claim 1, wherein the shading region has a trench formed as an etched portion from the surface of the first photoabsorber layer at least to an intermediate position in the multilayer reflective film.

6. The reflection-type mask according to claim 5, wherein the multilayer reflective film remaining in the shading region without being etched includes an electroconductive thin film.

7. The reflection-type mask according to claim 1, further comprising an electroconductive layer between the substrate and the multilayer reflective film, wherein the shading region has a trench region formed as etched portions of the first photoabsorber layer and the multilayer reflective film, the electroconductive layer being exposed at the bottom of the trench.

8. The reflection-type mask according to claim 1, wherein the shading region has a second photoabsorber layer which is formed on the first photoabsorber layer, and which absorbs the exposure light.

9. The reflection-type mask according to claim 8, further comprising a buffer layer formed of chromium (Cr) between the multilayer reflective film and the first photoabsorber layer, wherein the second photoabsorber layer is constituted of a material containing chromium (Cr).

10. The reflection-type mask according to claim 1, wherein the shading region has a shading layer which is formed on the first photoabsorber layer, and which is formed of tantalum (Ta) or chromium (Cr).

11. The reflection-type mask according to claim 1, wherein the shading region has a denatured layer in which the multilayer reflective film is implanted with ions, and in which the crystallinity is destroyed.

12. The reflection-type mask according to claim 1, wherein the shading region has a denatured layer in which an intermediate layer is formed at the interface between thin films constituting the multilayer reflective film.

13. A method of manufacturing a reflection-type mask, comprising:

preparing a substrate;

forming a multilayer reflective film above the substrate;

forming a first photoabsorber layer above the multilayer reflective film;

forming a circuit pattern region constituted of an opening formed as a result of removal of the first photoabsorber layer, and an absorbing portion where the first photoabsorber layer remains, by etching the first photoabsorber layer in conformity with a predetermined circuit pattern; and

forming a shading region having a reflectance with respect to the exposure light lower than that in the absorbing portion of the circuit pattern region.

14. The method according to claim 13, wherein the shading portion is formed by etching the first photoabsorber layer and at least part of the multilayer reflective film.

15. The method according to claim 13, wherein an electroconductive layer is formed on the substrate after the preparation of the substrate;

the multilayer reflective film is thereafter formed on the electroconductive layer; and

the shading region is formed by etching the first photoabsorber layer and the multilayer reflective film until the electroconductive layer is exposed.

16. The method according to claim 13, further comprising forming a second photoabsorber layer on the first photoabsorber layer after forming the first photoabsorber layer, wherein the circuit pattern region is formed by etching the first photoabsorber layer and the second photoabsorber layer in conformity with the predetermined circuit pattern, and thereafter removing the second photoabsorber layer on the first photoabsorber layer in the circuit pattern region.

17. The method according to claim 16, further comprising forming a buffer layer formed of chromium (Cr) above the multilayer reflective film after forming the multilayer reflective film, wherein the first photoabsorber layer is formed on the buffer layer and the second photoabsorber layer is formed of a material containing chromium, and wherein when the circuit pattern region is formed, the second photoabsorber layer and the buffer layer exposed in the opening are simultaneously etched.

18. The method according to claim 13, further comprising:

applying a photoresist on the first photoabsorber layer and the multilayer reflective film exposed in the opening after forming the circuit pattern region;

performing patterning on the photoresist so that the first photoabsorber layer in the portion in which the shading region is to be formed is exposed;

forming a film for a shading layer on the photoresist and the first photoabsorber layer exposed; and

removing the photoresist while leaving the shading layer on the first photoabsorber layer in the portion in which the shading region is to be formed.

19. The method according to claim 13, wherein the shading region is formed by destroying the crystallinity of the multilayer reflective film by implanting ions so that the ions reach the multilayer reflective film from the surface of the first photoabsorber layer.

20. The method according to claim 13, wherein the multilayer reflective film is formed by stacking a pair of thin films constituted of a silicon thin film and a molybdenum thin film, and the shading region is formed by irradiating the multilayer reflective film with laser so that an intermediate layer formed of a compound of silicon and molybdenum is formed at the interface between the silicon thin film and the molybdenum thin film.