Methods of forming patterns utilizing lithography and spacers

• US 8,039,399 B2
• Filed: 10/09/2008
• Issued: 10/18/2011
• Est. Priority Date: 10/09/2008
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Niroomand, Ardavan, Kiehlbauch, Mark, Sandhu, Gurtej S., Sills, Scott
• Primary Examiner(s): Deo; Duy
• Assistant Examiner(s): Dahimene; Mahmoud
• Application Number:
  US12/248,283
• Publication Number:
  US 20100093175A1
• Time in Patent Office: 1,104 Days
• Field of Search: 438/694, 430/313
• US Class Current: 438/694
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/0338 Process specially adapted to improve the resolution of the mask
• CPC Class Codes: H10B 69/00 Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices

Abstract

Some embodiments include methods of forming patterns. A first set of features is photolithographically formed over a substrate, and then a second set of features is photolithographically formed over the substrate. At least some of the features of said second set alternate with features of the first set. Spacer material is formed over and between the features of the first and second sets. The spacer material is anisotropically etched to form spacers along the features of the first and second sets. The features of the first and second sets are then removed to leave a pattern of the spacers over the substrate.

Claims

1. A method of forming a pattern, comprising:

photolithographically forming a first set of photoresist features over the substrate;

after photolithographically forming the first set of photoresist features, photolithographically forming a second set of photoresist features;

at least some of the features of said second set alternating with photoresist features of the first set along at least one cross-section extending through photoresist features of the first and second sets;

forming spacer material over and between the photoresist features of the first and second sets;

anisotropically etching the spacer material to form spacers along the photoresist features of the first and second sets; and

removing the photoresist features of the first and second sets to leave a pattern of the spacers over the substrate.

2. The method of claim 1 further comprising laterally trimming photoresist of the first set of photoresist features to narrow the photoresist features of the first set prior to forming the second set of photoresist features.

3. The method of claim 2 wherein the lateral trimming photoresist of the first set of photoresist features narrows the photoresist features of the first set by from about two-thirds to about three-quarters.

4. The method of claim 2 further comprising laterally trimming photoresist of the second set of photoresist features to narrow the photoresist features of the second set prior to forming the spacer material.

5. The method of claim 4 wherein the lateral trimming photoresist of the second set of photoresist features narrows the photoresist features of the second set by from about two-thirds to about three-quarters.

6. The method of claim 2 further comprising:

treating the narrowed photoresist features of the first set to render such narrowed photoresist features resistant to subsequent trimming;

after said treating, laterally trimming the second set of photoresist features to narrow said photoresist features prior to forming the spacer material.

7. The method of claim 6 wherein the treating comprises thermal treatment of the narrowed photoresist features of the first set to chemically alter at least exposed surfaces of the narrowed photoresist features of the first set.

8. The method of claim 6 wherein the treating comprises atomic layer deposition of a silicon-dioxide-containing material along exposed surfaces of the narrowed photoresist features of the first set.

9. The method of claim 1 further comprising laterally trimming photoresist of the first and second sets of photoresist features in a common process step prior to forming the spacer material.

10. A method of forming a pattern, comprising:

photolithographically forming a first set of photoresist features over the substrate;

the first set of photoresist features being spaced from one another by first gaps;

the photoresist features of the first set being at a first pitch, with said first pitch being a distance across a first photoresist feature and a first gap;

after photolithographically forming the first set of photoresist features, photolithographically forming a second set of photoresist features;

at least some of the features of said second set being within the first gaps so that photoresist features of the second set alternate with photoresist features of the first set along at least one cross-section extending through photoresist features of the first and second sets;

the second set of photoresist features being spaced from one another by second gaps;

the photoresist features of the second set being at a second pitch, with said second pitch being a distance across a second photoresist feature and a second gap;

the second pitch being about the same as the first pitch;

forming spacer material over and between the photoresist features of the first and second sets;

anisotropically etching the spacer material to form spacers along the photoresist features of the first and second sets; and

removing the photoresist features of the first and second sets to leave a pattern of the spacers over the substrate.

11. The method of claim 10 wherein photoresist features of the first set of photoresist features comprise about three-eighths of the first pitch.

12. The method of claim 10 further comprising laterally trimming photoresist of the first and second sets of photoresist features prior to forming the spacer material.

13. The method of claim 12 wherein the laterally trimming of the photoresist of the first and second sets of photoresist features occurs in a single process step.

14. The method of claim 12 wherein the laterally trimming of the photoresist of the first set of photoresist features occurs in a separate process step from the lateral trimming of the photoresist of the second set of photoresist features.

15. A method of forming a pattern, comprising:

photolithographically forming a first set of photoresist features over the substrate;

individual features of the first set of photoresist features having widths of from about 3x to about 4x and being spaced from one another by first gaps;

the first gaps having widths of from about 4x to about 5x;

laterally trimming the individual features of the first set of photoresist features to form trimmed first photoresist features;

the trimmed first photoresist features having widths of about x;

the trimming of the first photoresist features extending the widths of the first gaps to about 7x;

treating the trimmed first photoresist features to render the trimmed first photoresist features resistant to subsequent lateral trimming and/or solvent casting;

after treating the trimmed first photoresist features, photolithographically forming a second set of photoresist features over the substrate, at least some of the features of said second set being within the extended first gaps so that photoresist features of the second set alternate with photoresist features of the first set along at least one cross-section extending through photoresist features of the first and second sets;

individual features of the second set of photoresist features having widths of from about 3x to about 4x and being spaced from the trimmed first photoresist features by intervening gaps having widths of from about x to about 2x;

laterally trimming the individual features of the second set of photoresist features to form trimmed second photoresist features;

the trimmed second photoresist features having widths of about x;

the trimming of the second photoresist features extending the widths of the intervening gaps to from about 3x to about 4x;

forming spacer material over and between the trimmed first and second photoresist features;

anisotropically etching the spacer material to form spacers along the trimmed first and second photoresist features, the spacers having widths of about x;

removing the trimmed first and second photoresist features to leave a pattern of the spacers over the substrate, the pattern comprising spacers of width x spaced from one another by distances of width x; and

wherein x is a dimension, and is the same dimension for all recited aspects of this claim.

16. The method of claim 15 wherein the treating of the trimmed first photoresist features comprises forming a protective material along surfaces the trimmed first photoresist features.

17. The method of claim 16 wherein the forming of the protective material comprises atomic layer deposition.

18. The method of claim 16 wherein the protective material extends along the substrate within the first gaps, and wherein the photoresist features of the second set are formed over the protective material.

19. The method of claim 15 wherein the treating of the trimmed first photoresist features comprises thermal treatment of the trimmed first photoresist features to induce a chemical change throughout the trimmed first photoresist features.

20. The method of claim 15 wherein the treating of the trimmed first photoresist features comprises chemical treatment of outer surfaces of the trimmed first photoresist features to induce a chemical change along the outer surfaces of the trimmed first photoresist features.

21. The method of claim 15 wherein the substrate is a semiconductor substrate, and wherein the spacers consist of silicon dioxide.

22. A method of forming a pattern, comprising:

photolithographically forming a first set of photoresist features over the substrate;

individual features of the first set of photoresist features having widths of about 3x and being spaced from one another by first gaps;

the first gaps having widths of about 5x;

after photolithographically forming the first set of photoresist features;

photolithographically forming a second set of photoresist features over the substrate;

at least some of the features of said second set being within the first gaps so that photoresist features of the second set alternate with photoresist features of the first set along at least one cross-section extending through photoresist features of the first and second sets;

individual features of the second set of photoresist features having widths of about 3x and being spaced from the first photoresist features by intervening gaps having widths of about x;

laterally trimming the individual features of the first and second sets of photoresist features to form trimmed first and second photoresist features;

the trimmed first and second photoresist features having widths of about x;

the trimming of the first and second photoresist features extending the widths of the intervening gaps to about 3x;

forming spacer material over and between the trimmed first and second photoresist features;

anisotropically etching the spacer material to form spacers along the trimmed first and second photoresist features, the spacers having widths of about x;

removing the trimmed first and second photoresist features to leave a pattern of the spacers over the substrate, the pattern comprising spacers of width x spaced from one another by distances of width x; and

wherein x is a dimension, and is the same dimension for all recited aspects of this claim.

23. The method of claim 22 further comprising transferring the pattern of the spacers into the substrate with one or more etches.

24. The method of claim 23 wherein the substrate is a semiconductor substrate comprising one or more materials utilized for fabrication of memory architecture, and wherein the transferring the pattern into the substrate patterns said one or more materials into structures of memory architecture.

25. The method of claim 24 wherein the memory architecture is NAND.

26. The method of claim 24 wherein the memory architecture is DRAM.

27. The method of claim 24 wherein the memory architecture comprises cross-point memory cells.

28. The method of claim 23 wherein the spacers consist of silicon dioxide.