High-chi block copolymers for interconnect structures by directed self-assembly

Patent metadata

Field	Value
Publication number	US-9768059-B1
Application number	US-201615092693-A
Country	US
Kind code	B1
Filing date	Apr 7, 2016
Priority date	Apr 7, 2016
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

High-chi diblock copolymers are disclosed whose self-assembly properties are suitable for forming hole and bar openings for conductive interconnects in a multi-layered structure. The hole and bar openings have reduced critical dimension, improved uniformity, and improved placement error compared to the industry standard poly(styrene)-b-poly(methyl methacrylate) block copolymer (PS-b-PMMA). The BCPs comprise a poly(styrene) block, which can optionally include repeat units derived from trimethylsilyl styrene, and a second block that can be a polycarbonate block or a polyester block. Block copolymers comprising a fluorinated linking group L′ comprising 1-25 fluorines between the blocks can provide further improvement in uniformity of the openings.

First claim

What is claimed is:

1. A method, comprising:
providing a substrate having a top surface comprising a topographic pre-pattern of discrete initial openings, the initial openings comprising respective sidewalls and bottom surfaces, the initial openings having a critical dimension CD Init ;
forming a film layer disposed within each of the initial openings, the film layer having a top surface in contact with an atmosphere, the film layer comprising a linear diblock copolymer (BCP) comprising a block A and a block B, wherein
i) block A comprises a styrene repeat unit (A-2a):

ii) block B is an aliphatic polycarbonate or an aliphatic polyester,
iii) block A and block B are covalently linked by respective end repeat units to a divalent linking group L′, wherein L′ is a single bond or a group comprising at least one carbon,
iv) the BCP is capable of self-assembling to form a phase-segregated domain pattern comprising alternating domains of respective chemically distinct blocks of the block copolymer, and
v) the sidewalls of the initial openings are preferentially wetted by block B;

allowing or inducing the BCP disposed in the initial openings to self-assemble, thereby forming the domain pattern within each of the initial openings, the domain pattern comprising: a) a central block B domain comprising block B which is centrally located within the initial openings and b) a peripheral block B domain comprising block B which is in contact with the sidewalls, wherein the central block B domain and the peripheral block B domain are separated by, and in contact with, a block A domain comprising block A, and wherein the domain pattern within the initial openings has a top surface in contact with the atmosphere; and
selectively removing the central block B domain without substantially removing the block A domain and without substantially removing the peripheral block B domain, thereby forming an etched domain pattern comprising second openings, the second openings centrally located within the initial openings and having sidewalls comprising the block A domain, the second openings having a critical dimension CD 2nd corresponding to CD Init and smaller than CD Init ;

wherein
the method is suitable for forming openings for conductive interconnects that contact two or more layers of a multi-layered structure.

2. The method of claim 1 , comprising transferring the etched domain pattern to the substrate, thereby forming the openings for the conductive interconnects.

3. The method of claim 1 , wherein the domain pattern has a bulk periodicity Lo, and CD Init is about 2Lo.

4. The method of claim 1 , wherein the bulk periodicity Lo has a value in the range of 4 nm to 100 nm.

5. The method of claim 1 , wherein the initial openings include circular openings having a diameter of length d′, and CD Init is d′.

6. The method of claim 1 , wherein the initial openings include bar-shaped openings having a long axis of length 1′, a short axis of length w′, and an aspect ratio of l′:w′ between 1:1 and 100:1, and wherein CD Init is w′.

7. The method of claim 1 , wherein the block copolymer is capable of forming a lamellar domain pattern.

8. The method of claim 1 , wherein block A is a homopolymer of styrene.

9. The method of claim 1 , wherein block B is a polycarbonate comprising the carbonate repeat unit (A-4):

10. The method of claim 9 , wherein block B is a homopolymer of the carbonate repeat unit (A-4).

11. The method of claim 1 , wherein block B is a polyester comprising the ester repeat unit (A-8):

12. The method of claim 11 , wherein block B is a homopolymer of the ester repeat unit (A-8).

13. The method of claim 1 , wherein block A comprises a 4-(trimethylsilyl)styrene (TMSS) repeat unit (A-3):

14. The method of claim 1 , wherein L′ comprises 1-25 fluorine atoms.

15. The method of claim 1 , wherein the block copolymer has a block A:block B volume ratio in the range of 45:55 to 55:45.

16. A method, comprising:
providing a substrate having a top surface comprising a topographic pre-pattern of discrete initial openings, the initial openings comprising respective sidewalls and bottom surfaces, the initial openings having a critical dimension CD Init ;
forming a film layer disposed within each of the initial openings, the film layer having a top surface in contact with an atmosphere, the film layer comprising a linear diblock copolymer (BCP) comprising a block A, a block B, and a divalent linking group L′, wherein
i) block A comprises a styrene repeat unit (A-2a):

ii) block B comprises a repeat unit selected from the group consisting of carbonate repeat unit (A-4):

and
ester repeat unit (A-8):

iii) L′ comprises at least one carbon and 1-25 fluorine atoms,
iv) block A and block B are covalently linked by respective end repeat units to L′,
v) the BCP is capable of self-assembling to form a phase-segregated domain pattern comprising alternating domains of respective chemically distinct blocks of the block copolymer, and
vi) the sidewalls of the initial openings are preferentially wetted by block B;
allowing or inducing the BCP disposed in the initial openings to self-assemble, thereby forming the domain pattern within each of the initial openings, the domain pattern comprising: a) a central block B domain comprising block B which is centrally located within the initial openings and b) a peripheral block B domain comprising block B which is in contact with the sidewalls, wherein the central block B domain and the peripheral block B domain are separated by, and in contact with, a block A domain comprising block A, and wherein the domain pattern within the initial openings has a top surface in contact with the atmosphere; and
selectively removing the central block B domain without substantially removing the block A domain and without substantially removing the peripheral block B domain, thereby forming an etched domain pattern comprising second openings, the second openings centrally located within the initial openings and having sidewalls comprising the block A domain, the second openings having a critical dimension CD 2nd corresponding to CD Init and smaller than CD Init ;

wherein
the method is suitable for forming openings for conductive interconnects that contact two or more layers of a multi-layered structure.

17. The method of claim 16 , comprising transferring the etched domain pattern to the substrate, thereby forming the openings for the conductive interconnects.

18. The method of claim 16 , wherein L′ comprises a fluorinated alkyl group of formula (A-9):

wherein
n′ is an integer having

Assignees

• IBM

Inventors

• Liu Chi-Chun
• Magbitang Teddie P
• Sanders Daniel P
• Schmidt Kristin
• Vora Ankit

Classifications

• H10P14/68

  Organic materials, e.g. photoresists · CPC title

• H10P76/20

  of masks comprising organic materials · CPC title

• H10P50/242

  of Group IV materials · CPC title

• H10P50/73

  using masks for insulating materials · CPC title

• H10W20/089 Primary

  using processes for implementing desired shapes or dispositions of the openings, e.g. double patterning · CPC title