Methods for producing photomask blanks, cluster tool apparatus for producing photomask blanks and the resulting photomask blanks from such methods and apparatus

Abstract

Described herein are photomask blanks and photomasks prepared therefrom, methods for producing the photomask blanks and apparatus used in such methods. In one aspect, there is described methods for preparing photomask blanks having layers with a compositional gradient, i.e., a varying composition through the thickness of the layer. In other aspects, either in conjunction with the above aspects or independently, methods and apparatus are provided which allow more efficient use of a cluster tool for preparing the photomask blanks and performing quality control on them. The inventions find applicability, for example, in preparing binary photomask blanks and phase shift photomask blanks.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is Example of embodiment according to the invention having unique gradient feature of the film.

FIG. 2 is Example of Chamber Configuration according to an embodiment of the invention.

FIG. 3 is Cross-section view of an example of optical measurement device integral to transferring area of vacuum transfer chamber

FIG. 4 is Isometric view of multi-substrate cassette

Tables:

Table 1—Process values range of deposited films

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The specific embodiments described herein are, therefore, to be construed as merely illustrative, and not limitative of the disclosure in any way whatsoever. From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

Claims

1. A method for preparing a photomask blank which comprises depositing a layer with a compositional gradient on a substrate by sputtering in a single vacuum sputtering zone in the presence of plasma generated from at least one target, wherein: the composition of the plasma generated from at least one target is gradually varied during the deposition of the layer, and/orat least one reactive gas is provided in the same sputtering zone and the composition of the reactive gas is gradually varied during the deposition of the layer,

2. The method of claim 1 wherein the composition of the plasma generated from at least one target is gradually varied during the deposition of the layer.

3. The method of claim 2, wherein the composition of the plasma generated from the target is varied by varying the power applied to the target.

4. The method of claim 2, wherein at least one further target of differing composition is provided in the same sputtering zone and sputtering is also conducted on such further target.

5. The method of claim 4, wherein the at least one further target is also subject to variation in applied energy so that an additional gradient effect in the deposited layer from such additional target is achieved.

6. The method of claim 2, wherein there is at least one reactive gas in the same sputtering zone.

7. The method of claim 1, wherein the composition of the reactive gas is varied during the deposition of the layer to provide a compositional gradient in one or more deposited reactive gas elements.

8. The method of claim 2, wherein the composition of the reactive gas is varied during the deposition of the layer to provide a further compositional gradient in one or more deposited reactive gas elements.

9. The method of claim 1, wherein the resulting photomask blank is a binary and nanoimprint photomask blank having a thickness ranging from 5 Å to 3000 Å.

10. The method of claim 1, wherein the photomask blank is a transmissive embedded phase shift photomask blank wherein the phase shift is 180 degrees.

11. The method of claim 10, wherein the transmissive embedded phase shift photomask blank has a transmission varying from 0.1 to 0.9 at lithographic wavelength.

12. The method of claim 10, wherein the transmissive embedded phase shift photomask blank has a reflectance within the range of from 0 to 0.5 at lithographic wavelength.

13. The method of claim 2, wherein the plasma is continuously generated while the composition of the plasma generated from at least one target is gradually varied during the sputtering and deposition of the layer.

14. A photomask or photomask blank having at least one single layer which has both a compositional gradient in an element provided from a reactive gas and a compositional gradient in an element provided from plasma generated from a target.

15. A photomask or photomask blank having an anti-reflection layer and a masking layer and a gradient layer therebetween which has a compositional gradient in an element gradually varying from its composition in the anti-reflection layer to its composition in the masking layer, wherein the element is provided from a reactive gas and/or from plasma generated from a target.

16. A method for producing photomask blanks in a cluster tool having a vacuum sputtering chamber, a first vacuum chamber for active substrates and a mechanism for transferring active substrates from the first vacuum chamber for active substrates to the vacuum sputtering chamber, wherein at least one dummy plate is provided into the sputtering chamber from a vacuum chamber separate from the vacuum chamber for active substrates and using a mechanism for transferring the dummy plate that is separate from the mechanism used to transfer the active substrates into the sputtering chamber.

17. A cluster tool apparatus comprising a vacuum sputtering chamber, a first transferring vacuum chamber for providing active substrates into the vacuum sputtering chamber, a robotic transferring mechanism for transferring active substrates from the first transferring vacuum chamber into the vacuum sputtering chamber, a second transferring vacuum chamber for providing dummy plates into the vacuum sputtering chamber and a second robotic transferring mechanism for transferring dummy plates from the second transferring vacuum chamber into the vacuum sputtering chamber.

18. A method for producing photomask blanks in a cluster tool having a vacuum sputtering chamber, a load-lock chamber for unloading sputtered substrates from the vacuum sputtering chamber and a transferring area between the vacuum sputtering chamber and load-lock chamber, comprising conducting an optical measurement of a property of a sputtered substrate within the transferring area by an optical measurement tool integrated in the transferring area.

19. A cluster tool apparatus for producing photomask blanks which comprises a vacuum sputtering chamber and an unload chamber for unloading sputtered substrates from the vacuum sputtering chamber wherein the unload chamber comprises, integrally therein, at least one optical measurement tool for measuring a property of a sputtered substrate within the unload chamber.

20. A cassette which can hold multiple photomask blank substrates or coated substrate blanks usable in connection with a vacuum sputtering zone to prepare photomask blanks from such substrates, wherein the cassette: comprises means for holding multiple substrates or resulting blanks and positioning them for supplying to the sputtering zone and/or collecting them from the sputtering zone;has a design for reduced contamination, reduced damage and/or increased throughput in producing photomask blanks, which design avoids use of screws to assemble the cassette or similar small inaccessible areas susceptible to contamination; andis constructed of materials and designed such that the part where the substrate contacts the cassette results in a minimum contact area with minimum wear and/or reduces substrate scratching of the substrate or substrate blank.

21. The cassette of claim 20, wherein: the cassette comprises a top and bottom plate and four rods therebetween to define a rectilinear volume wherein the rods are press fit into slots and holes in the top and bottom plates without screws or similar fasteners;the cassette further comprises slots defined by corresponding donut-shaped protrusions on each of the four rods along the side corners of the cassette such that an inserted substrate or blank rests only on minimal contact points of each of four horizontally-corresponding donut-shaped protrusions andwherein the part of the cassette where the substrate or blank contacts the cassette has a rounded shape and is constructed of a wear-resistant polymer material which is resistant to scratching or otherwise wearing on the substrate or blank.

22. A method for producing photomask blanks in a cluster tool having a vacuum sputtering chamber wherein the substrates are provided to the load-lock from a cassette according to claim 20.