Approach to lowering extreme ultraviolet exposure dose for inorganic hardmasks for extreme ultraviolet patterning

1. An extreme ultraviolet lithography pattern stack, comprising:

an inorganic hardmask layer;

a polymeric or a self-assembled monolayer under layer on the inorganic hardmask layer; and

a resist layer directly on the a polymeric or self-assembled monolayer under layer, wherein the resist layer is sensitive to extreme ultraviolet light with a wavelength of about 13.5 nm, and includes photoacid generators (PAGs), and wherein the inorganic hardmask layer, polymeric or self-assembled monolayer under layer, and resist layer have a combined thickness in the range of about 8.5 nm to about 70 nm.

2. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the under layer is a polymeric under layer having a thickness in the range of about 0.5 nm to about 10 nm.

3. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the inorganic hardmask layer has a thickness in the range of about 3 nm to about 10 nm.

4. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the resist layer has a thickness in the range of about 5 nm to about 50 nm.

5. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the inorganic hardmask layer is a silicon-containing material, a metal oxide (MO x ), a metal nitride (MN x ), a metal carbide (MC x ), or combinations thereof.

6. The extreme ultraviolet lithography pattern stack of claim 1 , further comprising an organic planarization layer having a thickness in the range of about 20 nm to about 150 nm, where the inorganic hardmask layer is on the organic planarization layer.

7. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the under layer is a fast etching polymeric under layer that increases the adhesion of the resist layer to the inorganic hardmask layer.

8. The extreme ultraviolet lithography pattern stack of claim 1 , wherein the under layer is a self-assembled monolayer.

9. The extreme ultraviolet lithography pattern stack of claim 8 , wherein the self-assembled monolayer is formed by surface active agents with a hydroxyl (—OH) head and an alky tail with a C 6 to C 18 carbon chain length, a sulfonic acid (—SO 3 H) head and an alky tail with a C 6 to C 18 carbon chain length, or phosphonic acid (—PO(—OR 1 )(—OR 2 )) head, where R 1 and R 2 are alky tails with a C 6 to C 18 carbon chain length, where R 1 has the same chain length as R 2 or R 1 has a different chain length than R 2 .

10. An extreme ultraviolet lithography pattern stack, comprising:

an inorganic hardmask layer, wherein the inorganic hardmask layer is made of a material selected from the group consisting of silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbonitride (SiCN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon boro carbonitride (SiBCN), titanium oxide (TiO x ), molybdenum oxide (MoO x ), hafnium oxide (HfO x ), titanium nitride (TiN x ), molybdenum nitride (MoN x ), tantalum nitride (TaN x ), titanium carbide (TiC x ), and tantalum carbide (TaC x );

an under layer directly on the inorganic hardmask layer, where the under layer is a polymeric layer or a self-assembled monolayer; and

a resist layer on the under layer.

11. The extreme ultraviolet lithography pattern stack of claim 10 , further comprising an organic planarization layer, where the inorganic hardmask layer is on the organic planarization layer.

12. The extreme ultraviolet lithography pattern stack of claim 11 , wherein the inorganic hardmask layer is directly on the organic planarization layer, and the resist layer is directly on the under layer.

13. The extreme ultraviolet lithography pattern stack of claim 10 , wherein the under layer is a self-assembled monolayer.

14. The extreme ultraviolet lithography pattern stack of claim 13 , wherein the self-assembled monolayer is formed by surface active agents with a hydroxyl (—OH) head and an alky tail with a C 6 to C 18 carbon chain length, a sulfonic acid (—SO 3 H) head and an alky tail with a C 6 to C 18 carbon chain length, or phosphonic acid (—PO(—OR 1 )(—OR 2 )) head, where R 1 and R 2 are alky tails with a C 6 to C 18 carbon chain length, where R 1 has the same chain length as R 2 or R 1 has a different chain length than R 2 .

15. A method of forming an extreme ultraviolet lithography pattern stack, comprising:

forming an organic planarization layer on a substrate;

forming an inorganic hardmask layer directly on the organic planarization layer;

forming an under layer directly on the inorganic hardmask layer, wherein the under layer is a polymeric layer or a self-assembled monolayer, and the underlayer does not include photoacid generators (PAGs); and

forming a resist layer directly on the under layer.

16. The method of claim 15 , wherein the self-assembled monolayer is formed by surface active agents with a hydroxyl (—OH) head and an alky tail with a C 6 to C 18 carbon chain length, a sulfonic acid (—SO 3 H) head and an alky tail with a C 6 to C 18 carbon chain length, or phosphonic acid (—PO(—OR 1 )(—OR 2 )) head, where R 1 and R 2 are alky tails with a C 6 to C 18 carbon chain length, where R 1 has the same chain length as R 2 or R 1 has a different chain length than R 2 .

17. The method of claim 15 , wherein the inorganic hardmask layer is a silicon-containing material, a metal oxide (MO x ), a metal nitride (MN x ), a metal carbide (MC x ), or a combination thereof.

18. The method of claim 15 , wherein the inorganic hardmask layer has a thickness in the range of about 3 nm to about 10 nm.

19. The method of claim 15 , wherein the resist layer has a thickness in the range of about 5 nm to about 50 nm.

20. The method of claim 15 , the inorganic hardmask layer, under layer, and resist layer have a combined thickness in the range of about 9 nm to about 35 nm.