Method of forming a semiconductor structure
A method of forming a semiconductor structure includes following steps. First of all, a patterned hard mask layer having a plurality of mandrel patterns is provided. Next, a plurality of first mandrels is formed on a substrate through the patterned hard mask. Following these, at least one sidewall image transferring (SIT) process is performed. Finally, a plurality of fins is formed in the substrate, wherein each of the fins has a predetermined critical dimension (CD), and each of the mandrel patterns has a CD being 5-8 times greater than the predetermined CD.
1. A method of forming a semiconductor structure, comprising:
providing a photoresist layer having a plurality of mandrel patterns;
forming a plurality of first mandrels on a substrate through the photoresist layer;
performing at least one sidewall image transferring (SIT) process;
forming a plurality of third mandrels on the substrate through the SIT process;
forming a masking layer on the third mandrels and the substrate;
removing the masking layer on at least a portion of the third mandrels; and
forming a plurality of fins in the substrate through the masking layer and the third mandrels, wherein each of the fins has a predetermined critical dimension, at least one of the fins has a different critical dimension from others and each of the mandrel patterns has a critical dimension being 5-8 times greater than the predetermined critical dimension.
2. The method of forming a semiconductor structure of claim 1 , further comprising:
transferring the mandrel patterns of the photoresist layer to a mask layer under the photoresist layer, and the mask layer having a critical dimension being 5-8 times greater than the predetermined critical dimension.
3. The method of forming a semiconductor structure of claim 1 , further comprising:
forming a plurality of first spacers on the substrate, the first spacers surrounding the first mandrels respectively;
removing the first mandrels from the substrate; and
forming the third mandrels through the first spacers.
4. The method of forming a semiconductor structure of claim 3 , further comprising:
checking a critical dimension of the first spacers.
5. The method of forming a semiconductor structure of claim 4 , further comprising:
trimming a width of the first spacers to adjust the critical dimension of the first spacers.
6. The method of forming a semiconductor structure of claim 5 , wherein the trimming of the first spacers is performed after the first mandrels are removed.
7. The method of forming a semiconductor structure of claim 5 , wherein the trimming of the first spacers is performed before the first mandrels are removed.
8. The method of forming a semiconductor structure of claim 4 , further comprises:
forming another masking layer on the first spacers to adjust the critical dimension of the first spacers.
9. The method of forming a semiconductor structure of claim 1 , further comprising:
forming a plurality of first spacers on the substrate, the first spacers surrounding the first mandrels respectively;
removing the first mandrels from the substrate;
forming a plurality of second mandrels through the first spacers;
forming a plurality of second spacers on the substrate, the second spacers surrounding the second mandrels respectively;
removing the second mandrels; and
forming the third mandrels in the substrate through the second spacers.
10. The method of forming a semiconductor structure of claim 9 , further comprising:
checking a critical dimension of the first spacers.
11. The method of forming a semiconductor structure of claim 9 , further comprising:
checking a critical dimension of the second spacers.
12. The method of forming a semiconductor structure of claim 11 , further comprising:
trimming a width of the second spacers to adjust the critical dimension of the second spacers.
13. The method of forming a semiconductor structure of claim 12 , wherein the trimming of the second spacers is performed after the second mandrels are removed.
14. The method of forming a semiconductor structure of claim 12 , wherein the trimming of the second spacers is performed before the second mandrels are removed.
15. The method of forming a semiconductor structure of claim 1 , further comprising:
forming at least one of the fins having a different pitch from others.
16. The method of forming a semiconductor structure of claim 15 , wherein the photoresist layer comprises at least one mandrel pattern having a different pitch from others.
17. The method of forming a semiconductor structure of claim 15 , wherein the photoresist layer comprises at least one mandrel pattern having a different critical dimension from others.
18. The method of forming a semiconductor structure of claim 17 , wherein the at least one mandrel pattern has a critical dimension being 10-20 times greater than the predetermined critical dimension.