Alternating hardmasks for tight-pitch line formation
View Patent ↗A method for forming fins includes forming a three-color hardmask fin pattern on a fin base layer. The three-color hardmask fin pattern has hardmask fins of three mutually selectively etchable compositions. A region on the three-color hardmask fin pattern is masked, leaving one or more fins of a first color exposed. All exposed fins of the first color are etched away with a selective etch that does not remove fins of a second color or a third color. The mask and all fins of a second color are etched away. Fins are etched into the fin base layer by anisotropically etching around remaining fins of the first color and fins of the third color.
1. A wafer, comprising:
a plurality of fins of three distinct materials, comprising fins of a first material (A), fins of a second material (B), and fins of a third material (C), wherein the fins are arranged in contact with one another in a pattern of ABCBABCBA and are disposed directly on a layer of a fourth distinct material; and
fin caps disposed on the fins of the first material, with a top surface that has a height higher than a top surface of the fins of the second material and a bottom surface that has a height lower than the top surface of the fins of the second material.
2. The wafer of claim 1 , wherein the first material comprises amorphous silicon, the second material comprises carbon, and the third material comprises silicon dioxide.
3. The wafer of claim 1 , wherein the fins of the second material have a height that is below the height of the fins of the third material.
4. The wafer of claim 1 , wherein the fourth material comprises silicon nitride.
5. The wafer of claim 1 , wherein the fin caps have a thickness of about 5 nm.
6. The wafer of claim 1 , wherein the fin caps comprise the fourth material.
7. The wafer of claim 1 , wherein the fin caps comprise a fifth distinct material.
8. The wafer of claim 1 , further comprising a semiconductor layer under the layer of the fourth material.
9. A wafer, comprising:
a plurality of fins of three distinct materials, comprising fins of a first material (A), fins of a second material (B), and fins of a third material (C), wherein the fins are arranged in contact with one another in a pattern of ABCBABCBA and are disposed directly on a layer of a fourth distinct material;
fin caps disposed on the fins of the first material, formed from a material selected from the group consisting of the fourth material and a fifth distinct material.
10. The wafer of claim 9 , wherein the first material comprises amorphous silicon, the second material comprises carbon, and the third material comprises silicon dioxide.
11. The wafer of claim 9 , wherein the fins of the second material have a height that is below the height of the fins of the first material and the fins of the third material.
12. The wafer of claim 9 , wherein the fourth material comprises silicon nitride.
13. The wafer of claim 9 , wherein the fin caps have a thickness of about 5 nm.
14. The wafer of claim 9 , further comprising a semiconductor layer under the layer of the fourth material.
15. The wafer of claim 9 , wherein a top surface of the fin caps has a height higher than a top surface of the fins of the second material and wherein a bottom surface of the fin caps has a height lower than the top surface of the fins of the second material.