Photomask producing method and apparatus and device manufacturing method

• US 20020187406A1
• Filed: 07/16/2002
• Published: 12/12/2002
• Est. Priority Date: 12/25/1997
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Shiraishi, Naomasa, Magome, Nobutaka
• Granted Patent: US 6,677,088 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• CPC Class Codes: G03F 1/78 by charged particle beam [CPB], e.g. electron beam patterning of masks
• CPC Class Codes: G03F 7/70333 Focus drilling, i.e. increase in depth of focus for exposure by modulating focus during exposure [FLEX]
• CPC Class Codes: G03F 7/70475 Stitching, i.e. connecting image fields to produce a device field, the field occupied by a device such as a memory chip, processor chip, CCD, flat panel display
• CPC Class Codes: H01J 2237/31764 Dividing into sub-patterns

Abstract

A photomask producing method according to the present invention segments a parent pattern which is an α-magnification of an original pattern which is a β-magnification of a circuit pattern into α lengthwise and breadthwise, thereby forming parent patterns on data. The parent patterns are written on a substrate at equal magnification by using an electron beam lithography system, thereby producing master reticles. Reduced images of the parent patterns of the master reticles are transferred on a substrate while performing screen linking, thereby producing working reticle. This photomask producing method can form an original pattern with a high precision and in a short period of time.

Claims

1. A method of producing a photomask having a transfer pattern formed, comprising:

segmenting an enlarged pattern of said transfer pattern into patterns of plural parent masks; and

sequentially transferring reduced images of said patterns of said plural parent masks, shifted from one to another, onto a surface of a substrate for said photomask.

8. The photomask producing method according to claim 1, wherein at a time of sequentially transferring reduced images of patterns of said plural parent masks on the surface of said substrate, a reduction projection exposure apparatus of a one-shot exposure type or a reduction projection exposure apparatus of a scanning exposure type is selectively used in accordance with the use of said photomask.

9. The photomask producing method according to claim 1, wherein at a time of sequentially transferring reduced images of patterns of said plural parent masks on the surface of said substrate, each image forming characteristic of reduced images of said patterns of said parent masks is corrected in accordance for at least one of a rotational asymmetric aberration and a distortion characteristic of a projection optical system of a projection exposure apparatus which uses said photomask.

10. The photomask producing method according to claim 1, wherein said photomask is further used in reduction projection.

25. The photomask producing method according to claim 1, wherein different pattern units corresponding to circuit blocks with different functions, which constitute said transfer pattern, are respectively formed on said plural parent masks.

27. The photomask producing method according to claim 1, wherein exposure conditions are made different on at least a part of said plural parent masks.

2. A method of producing a photomask having a transfer pattern formed, comprising:

segmenting said transfer pattern or an enlarged pattern thereof into M sets (M being an integer equal to or greater than

     2) of patterns of plural parent masks; and

sequentially transferring reduced images of said M sets of patterns of plural parent masks, overlapping one on another, onto a surface of a substrate for said photomask.

3. The photomask producing method according to claim 2, wherein said M sets of patterns of plural parent masks are a plurality of patterns segmented from said transfer pattern or an enlarged pattern thereof in a same arrangement.

4. The photomask producing method according to claim 2, wherein a segmenting method for at least one set of patterns of plural parent masks in said M sets of patterns of plural parent mask patterns differs from that for another predetermined set of patterns of plural parent masks.

5. The photomask producing method according to claim 4, wherein at least one set of patterns of plural parent masks in said M sets of patterns of plural parent masks includes a linkage area for another predetermined set of patterns of plural parent masks.

6. A method of producing a photomask having a device pattern, comprising:

transferring a reduced image of one of a plurality of segment patterns segmented from an enlarged pattern of said device pattern onto a mask substrate; and

transferring a reduced image of another segment pattern which is the same as said one segment pattern at least partially on said mask substrate in such a way that the same portions overlap each other.

7. The photomask producing method according to claim 6, wherein said plurality of segment patterns are exposed with a light beam and their reduced images are transferred, linked together, on said mask substrate.

11. A method of producing a photomask having a predetermined transfer circuit pattern formed, comprising:

forming a parent mask formed with a predetermined pattern including one or a plurality of pattern units respectively corresponding to one or a plurality of circuit blocks in said transfer circuit pattern; and

transferring a projection image of said pattern unit selected from a pattern of said parent mask on a substrate for said photomask in a predetermined positional relation.

12. The photomask producing method according to claim 11, wherein said circuit block corresponds to one of a CPU core section, RAM section and ROM section in an integrated circuit and standard circuit block for a standard cell.

13. The photomask producing method according to claim 11, wherein as said parent mask, plural parent masks are prepared on which different pattern units respectively corresponding to different circuit blocks in said transfer circuit pattern are formed, and

projection images of the pattern units selected from patterns of said plural parent masks are sequentially transferred on said substrate for said photomask in a predetermined positional relation.

14. The photomask producing method according to claim 11, wherein said parent mask is used at a time of producing plural types of photomasks.

15. The photomask producing method according to claim 11, wherein a reduced image of said pattern unit of said parent mask is transferred on said substrate for said photomask, and said photomask is further used in reduction projection.

16. The photomask producing method according to claim 11, wherein by using an exposure beam stopped down to a predetermined spot, a part of said transfer circuit pattern is written on said substrate for said photomask at at least a part of an area other than where an image of said pattern unit of said parent mask reduced image of said pattern unit of said parent mask is transferred.

18. The photomask producing apparatus according to claim 17, wherein said mask retaining unit retains plural parent masks on which segmented patterns of an enlarged pattern of a pattern of a photomask to be produced are formed respectively.

19. The photomask producing apparatus according to claim 17, comprising a view field selecting system that selects a pattern of a predetermined shape at an arbitrary position in said patterns of said masks and projects a reduced image of said selected pattern by said projection optical system on said substrate for said photomask, and

wherein said alignment system aligns said mask with said substrate on said substrate stage in order to transfer said reduced image selected by said field view selecting system on said substrate in a predetermined positional relation.

17. A photomask producing apparatus comprising:

a mask retaining unit that retains a plurality of masks;

a mask stage on which a mask selected from said mask retaining unit is placed;

a projection optical system that projects a reduced image of a pattern of said mask on said mask stage onto a substrate for a photomask;

a substrate stage that positions said substrate on a plane perpendicular to an optical axis of said projection optical system; and

an alignment system that aligns said mask on said mask stage with said substrate on said substrate stage in order to transfer reduced images of patterns of said predetermined masks on said substrate, shifted from one another.

20. A method of manufacturing a device in which a predetermined pattern is formed on a substrate, comprising:

segmenting a second pattern obtained by further enlarging an enlarged first pattern of said predetermined pattern into patterns of plural parent masks;

producing a photomask for real exposure formed with said first pattern by performing reduction projection of said patterns of plural parent masks on a predetermined substrate, sequentially shifting their positions from one to another; and

transferring a reduced image of a pattern of said photomask for real exposure on said substrate.

21. The device manufacturing method according to claim 20, wherein said second pattern of said parent mask is segmented into M sets (M being an integer equal to or greater than 2) of plural patterns;

and

said photomask for real exposure formed with said first pattern is produced by performing reduction projection of said M sets of patterns of plural parent masks on said substrate, sequentially overlapping one on another.

22. A method of manufacturing a device for forming a predetermined circuit pattern on a substrate, comprising:

forming a pattern unit corresponding to at least one circuit block in an enlarged first circuit pattern of said predetermined circuit pattern on a parent mask;

producing a photomask for real exposure formed with said first circuit pattern by transferring said pattern unit of said parent mask on a predetermined substrate in a predetermined positional relation; and

transferring a reduced image of a pattern of said photomask for real exposure on a substrate for said device.

24. The device manufacturing method according to claim 23, wherein transfer from said plural parent masks to said photomask is carried out by using an optical exposure system.

26. The photomask producing method according to claim 25, wherein another transfer pattern having a different circuit structure from said transfer pattern is formed by using said plural parent masks.

29. The photomask producing method according to claim 28, wherein said plurality of patterns respectively correspond to circuit blocks with different functions, which constitute said circuit pattern.

30. The photomask producing method according to claim 28, wherein an enlarged pattern of said circuit pattern is segmented into a plurality of segments, and reduced images of said plurality of patterns are transferred on said mask substrate.

31. The photomask producing method according to claim 30, wherein said image characteristics include an optical characteristic of a projection optical system for forming reduced images of said patterns.

23. A method of manufacturing a device for performing miniaturization work by exposure and transfer of a pattern of a photomask for real exposure, wherein at a time of forming said pattern on said photomask,

patterns segmented from an enlarged pattern of one chip of said device in accordance with its location are formed on plural parent masks, respectively;

and

reduced images of said segmented patterns on said plural parent masks are transferred on said photomask at respective positions to be combined.

28. A photomask producing method for use in an exposure system for transferring a circuit pattern on a device substrate, comprising:

segmenting said circuit pattern into a plurality of patterns, and adjusting at least one of transfer positions of said patterns on a mask substrate and image characteristics based on a transfer characteristic of said circuit pattern in said exposure system when said plurality of patterns are transferred on said mask substrate, shifted from one another.

32. A photomask for use in an exposure system for transferring a circuit pattern having a plurality of circuit blocks with different functions on a device substrate, wherein

enlarged patterns of said circuit blocks are illuminated with a light beam unit by unit and reduced images of said enlarged patterns are combined on a mask substrate to thereby form said circuit pattern.

33. The photomask according to claim 32, wherein said enlarged patterns are transferred on said mask substrate by a one-shot exposure system or a scanning exposure system.