Methods of reducing proximity effects in lithographic processes

• US 6,120,952 A
• Filed: 10/01/1998
• Issued: 09/19/2000
• Est. Priority Date: 10/01/1998
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Pierrat, Christophe, Stanton, William, Baggenstoss, William, Burdorf, James E.
• Primary Examiner(s): Young, Christopher G.
• Application Number:
  US09/164,786
• Time in Patent Office: 719 Days
• Field of Search: 430/30, 430/311
• US Class Current: 430/30
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G03F 7/70441 Optical proximity correction [OPC]

Abstract

Methods of reducing proximity effects in lithographic processes wherein an integrated circuitry pattern is transferred from a mask onto a semiconductor substrate are described. In one embodiment, a desired spacing is defined between a main feature which is to reside on a mask and which is to be transferred onto the substrate, and an adjacent proximity effects-correcting feature. After the spacing definition, the dimensions of the main feature are adjusted relative to the proximity effects-correcting feature to achieve a desired transferred main feature dimension. In another embodiment, a desired spacing is defined between a main feature having an edge and an adjacent sub-resolution feature. The edge of the main feature is moved relative to the sub-resolution feature to achieve a desired transferred main feature dimension.

Claims

1. A method of reducing proximity effects in a lithographic process wherein an integrated circuitry pattern is transferred from a mask onto a semiconductor substrate, the method comprising:

defining a desired spacing between a main feature which is to reside on the mask and which is to be transferred onto the substrate and a pair of adjacent proximity effects-correcting features disposed on opposing sides of the main feature; and

after said defining, adjusting dimensions of the main feature relative to the pair of proximity effects-correcting features to achieve a desired transferred main feature dimension.

2. The method of claim 1, wherein defining the desired spacing comprises selecting a spacing to optimize depth of focus in the lithographic process.

3. The method of claim 1, wherein adjusting comprises changing an area of the main feature.

4. The method of claim 1, wherein adjusting comprises changing a shape of the main feature.

5. The method of claim 1, wherein adjusting comprises increasing an area of the main feature.

6. The method of claim 1, wherein the main feature has a plurality of sides and wherein adjusting comprises moving at least a portion of one of the sides.

7. The method of claim 1, wherein the main feature has a plurality of sides and wherein adjusting comprises moving at least a portion of at least one of the sides.

8. The method of claim 1, wherein the main feature has first and second sides which are generally parallel with one another and laterally displaced from the pair of proximity effects-correcting features, and wherein adjusting comprises moving portions of each of the first and second sides.

9. The method of claim 1, wherein the main feature has first and second sides which are spaced apart from one another, and wherein adjusting comprises repositioning at least a portion of one of the first and second sides relative to its next adjacent proximity effects-correcting feature.

10. The method of claim 1, wherein the main feature has first and second sides which are spaced apart from one another, and wherein adjusting comprises repositioning portions of each of the first and second sides relative to its next adjacent proximity effects-correcting feature.

11. A method of reducing proximity effects in a lithographic process wherein an integrated circuitry pattern is transferred from a mask onto a semiconductor substrate, the method comprising:

defining a desired spacing between a main feature which is to reside on the mask and which is to be transferred onto the substrate and a pair of adjacent sub-resolution features disposed on opposing sides of the main feature, the main feature having parallel edges; and

moving each of the edges of the main feature relative to a respective adjacent one of the pair of sub-resolution features to achieve a desired transferred main feature dimension.

12. The method of claim 11, wherein defining comprises selecting the spacing to achieve a desired depth of focus.

13. The method of claim 11, wherein moving comprises moving each edge away from the respective adjacent one of the pair of sub-resolution features.

14. The method of claim 11, wherein moving comprises moving each edge towards the respective adjacent one of the pair of sub-resolution features and increasing dimensions of the main feature.

15. The method of claim 11, wherein moving comprises moving each edge toward the respective adjacent one of the pair of sub-resolution features.

16. The method of claim 11, wherein moving comprises moving each edge toward the respective adjacent one of the pair of sub-resolution features and increasing dimensions of the main feature.

17. The method of claim 11, wherein moving increases dimensions of the main feature.

18. The method of claim 11, wherein the main feature comprises a conductive line pattern, and the desired transferred main feature dimension is approximately equal to a minimum photolithographic feature size from which the integrated circuitry is fabricated.

19. The method of claim 11, wherein the main feature comprises a conductive line pattern and moving increases dimensions of the main feature, and wherein the desired transferred main feature dimension is approximately equal to a minimum photolithographic feature size from which the integrated circuitry is fabricated.

20. A method of reducing proximity effects in a lithographic process wherein an integrated circuitry pattern is transferred from a mask onto a semiconductor substrate, the method comprising:

defining a plurality of main features which are to appear on the mask and be transferred onto a substrate, the main features having width dimensions;

defining a desired spacing between a pair of sub-resolution features disposed on opposing sides of one of the main features and the one of the main features;

changing a width dimension of the one main feature and not changing any dimensions of the pair of sub-resolution features; and

forming a plurality of patterned main features on the substrate using the mask, said plurality of main features having substantially common patterned width dimensions.

21. The method of claim 20, wherein forming the plurality of patterned main features comprises forming the plurality of features to have width dimensions approximately equal to a minimum photolithographic feature size from which the integrated circuitry is formed.

22. The method of claim 20, wherein defining the desired spacing comprises selecting the desired spacing to achieve a desired depth of focus.

23. The method of claim 20, wherein defining the plurality of main features comprises defining at least one conductive line pattern.

24. The method of claim 20, wherein defining the plurality of main features comprises defining at least one conductive line pattern, and forming the plurality of patterned main features comprises forming the plurality of features to have at least one conductive line width approximately equal to a minimum photolithographic feature size from which the integrated circuitry is formed.

25. The method of claim 20, wherein defining the plurality of main features comprises defining a plurality of conductive line patterns.

26. The method of claim 20, wherein:

defining the plurality of main features comprises defining a plurality of conductive line patterns;

and

changing the width dimension comprises moving one of the opposing edges toward a nearest of the pair of sub-resolution features.

27. The method of claim 20, wherein:

defining the plurality of main features comprises defining a plurality of conductive line patterns; and

changing the width dimension comprises moving each of the opposing edges toward a respective one of the pair of sub-resolution features, each edge being a nearest of the spaced-apart edges relative to each of the pair of sub-resolution features.

28. A method of reducing proximity effects in a lithographic process wherein an integrated circuitry pattern is transferred from a mask onto a semiconductor substrate, the method comprising:

defining a plurality of main features which are to appear on the mask at least some of which having width dimensions effective to form main feature patterns over a substrate with width dimensions which are no greater than a minimum photolithographic feature size from which the integrated circuitry is fabricated, one of the main features being spaced from other main features a distance which is effective to form a patterned main feature over the substrate which is spaced from other patterned main features over the substrate a distance which is greater than the minimum photolithographic feature size, the one main feature having a pair of edges defining a first width dimension;

defining a desired spacing between the one main feature and each of a pair of proximity effects-correcting features, each of the pair to appear on the mask adjacent to opposing sides of the one main feature; and

after said defining of the desired spacing, moving one of the opposing edges of the one main feature to define a second width dimension which is different from the first width dimension, moving enabling a patterned main feature to be formed on the substrate corresponding to the one main feature to have a width dimension which is no greater than the minimum photolithographic feature size.

29. The method of claim 28, wherein defining a desired spacing comprises defining a desired spacing between the one main feature and each of the pair of sub-resolution proximity effects-correcting features.

30. The method of claim 28, wherein defining the desired spacing comprises defining the desired spacing to achieve a maximum depth of focus.

31. The method of claim 28, wherein moving opposing edges of the one main feature comprises moving an edge nearest each of the pair of proximity effects-correcting features.

32. The method of claim 28, wherein moving opposing edges of the one main feature comprises moving an edge nearest each of the pair of proximity effects-correcting features toward each of the pair of proximity effects-correcting features.

33. The method of claim 28, wherein moving comprises moving the opposing edges of the one main feature to define the second width to be greater than the first width.

34. The method of claim 28, wherein moving opposing edges of the one main feature comprises moving an edge nearest each of the pair of proximity effects-correcting features to define the second width to be greater than the first width.

35. The method of claim 28, wherein defining the plurality of main features comprises defining a plurality of conductive line patterns.