Template mask lithography utilizing structured beam

• US 6,372,391 B1
• Filed: 09/25/2000
• Issued: 04/16/2002
• Est. Priority Date: 09/25/2000
• Status: Expired due to Term

• Current Assignee: University of Houston Law Center (University of Houston System)
• Original Assignee: University of Houston (University of Houston System)
• Inventors: Ruchhoeft, Paul, Wolfe, John Charles
• Primary Examiner(s): Young, Christopher G.
• Application Number:
  US09/669,288
• Time in Patent Office: 568 Days
• Field of Search: 430/5, 430/296, 430/396, 430/942
• 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 1/20 Masks or mask blanks for imaging by charged particle beam [CPB] radiation, e.g. by electron beam; Preparation thereof
• CPC Class Codes: G03F 9/00 Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically G03F7/22 takes precedence; preparation of photographic masks G03F1/00; within photographic printing apparatus for making copies G03B27/00
• CPC Class Codes: H01J 2237/31788 through mask
• CPC Class Codes: H01J 37/3174 Particle-beam lithography, e.g. electron beam lithography
• CPC Class Codes: Y10S 430/143 Electron beam

Abstract

For lithographic patterning a plurality of identical structures (24) onto a target substrate (14), a template mask (13) is produced which bears a template structure pattern comprising a plurality of identical template structures each consisting of a set of at least one structure element (C) of circular shape. Starting from a primary mask (11) bearing a primary structure pattern consisting of at least one structure element having a circular shape, the production of the template mask is done in at least one lithographic mask structuring step (b, c) wherein in each mask structuring step by means of a broad beam (31) of energetic radiation the mask is illuminated and a structure pattern on the mask (11,12) is imaged onto an intermediate substrate (12a,13a); in these mask structuring steps the pattern image imaged from the structure pattern is moved over the intermediate substrate to a number of different locations. From the intermediate substrate (12a,13a) thus patterned another mask (12,13) having a structure pattern corresponding to the pattern image is produced, respectively. The mask produced from the last of said mask structuring steps is the template mask (13). By means of the template mask (13) a target substrate (14) is patterned in a final lithographic patterning step, the pattern image thus produced comprising a plurality of identical target structures (24).

Claims

1. A method for lithographic patterning of a plurality of identical structures onto a target substrate, wherein

a template mask bearing a template structure pattern, comprising a plurality of identical template structures each consisting of a set of at least one structure element of circular shape, is used for lithographic patterning of the target substrate,

wherein by means of a broad beam of energetic radiation the template mask is illuminated to form a structured beam and the template structure pattern is imaged onto the target substrate by means of the structured beam, the target substrate being positioned after the mask as seen in the optical path of the beam and comprising material sensitive to exposure to said energetic radiation, producing a pattern image on the target substrate, the pattern image thus produced comprising a plurality of identical target structures.

2. The method of claim 1, wherein

the pattern image is moved over the substrate through a sequence of image positions, the exposure with respect to the sequence of image positions superposing into a spatial distribution of exposure dose on the substrate, said distribution defining the structures thus patterned on the target substrate according to the exposure-dependent characteristic of said sensitive material.

3. The method of claim 2, wherein

the spatial distribution of exposure dose on the substrate exceeds the specific minimum exposure dose of said sensitive material only within regions of the substrate field, said regions forming an exposure pattern comprising a plurality of identical structures.

4. The method of claim 2, wherein

the intensity of exposure is varied for each image position in a manner according to a prescribed set of intensities calculated from a representation of a pattern image to be produced on the target substrate.

5. The method of claim 4, wherein

the intensity of exposure is controlled by varying the time of exposure for the respective image position.

6. The method of claim 4, wherein

the pattern image is defined in terms of a spatial distribution of height of said exposure sensitive material, and said set of intensities is calculated from said distribution of height using a predetermined functional dependence of the height on the exposure dose.

7. The method of claim 2, wherein

the primary structure pattern as well as each of the template structures of the template mask consist of a single structure element of circular shape.

8. The method of claim 2, wherein

the pattern image is moved through a discrete set of image positions.

9. The method of claim 8, wherein

the time during which the pattern is held at an image position is varied according to the exposure dose to be imparted to the respective image position.

10. The method of claim 2,

the energetic radiation comprises electrically charged particles and the lithographic patterning is done using a particle optical lithography system, and the pattern image is moved over the substrate by inclining the direction of the beam with respect to the optical axis of said lithography system by means of an electrostatic deflection means of said lithography system.

11. The method of claim 1, wherein

the energetic radiation comprises electrically charged particles and the lithographic patterning is done using a particle optical lithography system.

12. The method of claim 11, wherein

the energetic radiation comprises ions, such as hydrogen or helium ions.

13. The method of claim 1, wherein

the target substrate comprises a layer of resist material sensitive to exposure to an energetic radiation.

14. A lithography system provided with a template mask according to claim 1, the template mask bearing a template structure pattern comprising a plurality of identical template structures each consisting of a set of at least one structure element of circular shape.

15. A method for producing a template mask according to claim 1, the template mask bearing a template structure pattern comprising a plurality of identical template structures each consisting of a set of at least one structure element of circular shape, wherein starting from a primary mask bearing a primary structure pattern consisting of at least one structure element having a circular shape, a template mask bearing a template structure pattern, comprising a plurality of identical template structures each corresponding to the primary structure pattern, is produced using the primary mask to define the template structures, wherein

the production of the template mask is done in at least one lithographic mask structuring step wherein in each mask structuring step by means of a broad beam of energetic radiation a mask bearing a structure pattern is illuminated to form a structured beam and the structure pattern is imaged at least once onto an intermediate substrate by means of the structured beam, said intermediate substrate being positioned after the mask as seen in the optical path of the beam and comprising material sensitive to exposure to said energetic radiation, producing a pattern image on the intermediate substrate, and from the intermediate substrate thus patterned another mask having a structure pattern corresponding to the pattern image is produced,

the mask used in the first of said mask structuring steps is the primary mask, the mask used in each subsequent step, if present, is the mask produced from the previous step, and the mask produced from the last of said mask structuring steps is the template mask, and

in at least one of said mask structuring steps the pattern image imaged from the structure pattern is moved over the intermediate substrate to a number of different locations.

16. The method of claim 15, wherein

in each mask structuring step, the pattern image is moved over the intermediate substrate to a number of locations arranged in a regular array.

17. The method of claim 15, wherein

the energetic radiation comprises electrically charged particles and the lithographic patterning is done using a particle optical lithography system.

18. The method of claim 17, wherein

the energetic radiation comprises ions, such as hydrogen or helium ions.