Dual exposure track only pitch split process
View Patent ↗An integrated circuit is formed with structures spaced more closely together than a transverse dimension of such structures, such as for making contacts to electronic elements formed at minimum lithographically resolvable dimensions by dark field split pitch techniques. Acceptable overlay accuracy and process efficiency and throughput for the split pitch process that requires etching of a hard mark for each of a plurality of sequentially applied and patterned resist layers is supported by performing the etching of the hard mask entirely within a lithography track through using an acid sensitive hard mark material and an acidic overcoat which contacts areas of the hard mask through patterned apertures in the resist. The contacted areas of the hard mask are activated for development by baking of the acidic overcoat.
1. A method for etching a pattern in a layer of acid sensitive material, said process comprising steps of
forming said layer of acid sensitive material,
forming and patterning a layer of resist on said layer of acid sensitive material,
applying an acidic overcoat on said patterned layer of photoresist and areas of said acid sensitive material exposed by said photoresist,
activating said areas of said acid sensitive material, and
developing said activated areas of said acid sensitive material to transfer a pattern in the resist to said acid sensitive material.
2. The method as recited in claim 1 comprising the further steps of
forming and patterning a further layer of resist on said layer of acid sensitive material,
applying an acidic overcoat on said patterned layer of photoresist and areas of said acid sensitive material exposed by said photoresist,
activating said areas of said acid sensitive material, and
developing said activated areas of said acid sensitive material to transfer a pattern in the resist to said acid sensitive material.
3. The method as recited in claim 2 , comprising the further step of
transferring a pattern developed in said acid sensitive material to an underlying layer of material.
4. The method as recited in claim 2 , wherein said acid sensitive material is formed on an organic planarizing layer.
5. The method as recited in claim 2 , further including a step of
adjusting size of a feature patterned in said resist.
6. The method as recited in claim 2 , further including a step of
adjusting size of a feature patterned in said acid sensitive material.
7. The method as recited in claim 1 , comprising the further step of
transferring a pattern developed in said acid sensitive material to an underlying layer of material.
8. The method as recited in claim 1 , wherein said acid sensitive material is formed on an organic planarizing layer.
9. The method as recited in claim 1 , further including a step of
adjusting size of a feature patterned in said resist.
10. The method as recited in claim 1 , further including a step of
adjusting size of a feature patterned in said acid sensitive material.
11. A pitch split process for semiconductor manufacturing, said process comprising steps of
forming a layer of acid sensitive material,
forming and patterning a layer of photoresist on said layer of acid sensitive material using a lithographic pitch split exposure mask,
applying an acidic overcoat on said patterned layer of photoresist and areas of said acid sensitive material exposed by said photoresist,
activating said areas of said acid sensitive material, and
developing activated areas of said acid sensitive material,
forming and patterning another layer of photoresist on said layer of acid sensitive material using another lithographic pitch split exposure mask,
applying an acidic overcoat on said another patterned layer of photoresist and areas of said acid sensitive material exposed by said photoresist,
activating said areas of said acid sensitive material, and
developing activated areas of said acid sensitive material.
12. The method as recited in claim 11 , comprising the further step of
transferring a pattern developed in said acid sensitive material to an underlying layer of material.
13. The method as recited in claim 11 , wherein said acid sensitive material is formed on an organic planarizing layer.
14. The method as recited in claim 11 , further including a step of
adjusting size of a feature patterned in said resist.
15. The method as recited in claim 11 , further including a step of
adjusting size of a feature patterned in said acid sensitive material.