Synthesis of photoresist polymers
The present invention is directed to the preparation of photoresist polymers via living free radical polymerization techniques. Sterically bulky ester monomers are utilized as the polymerization components. Use of chain transfer agents is included in polymerization processing conditions. Cleavage of polymer terminal end groups that include a heteroatom are described.
1. A method of free radical polymerization to form a polymer having the formula:
[A] x [B] y [C] z
wherein A, B and C are each individually one of
wherein x is between 0 and 200 inclusive, y is between 0 and 200 inclusive and z is between 1 and 200 inclusive, comprising:
forming a mixture of one or more of monomers A, B and C and a chain transfer agent and subjecting the mixture to polymerization conditions wherein the chain transfer agent (CTA) is characterized by the general formula:
wherein R 1 is any group that can be expelled as its free radical form in an addition-fragmentation reaction;
R 2 and R 3 are each independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and combinations thereof, and optionally R 2 and R 3 together to form a double bond optionally substituted alkenyl moiety;
R 4 is selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and combinations thereof; and optionally, R 4 combines with R 2 and/or R 3 to form a ring structure, with said ring having from 3 to 50 non-hydrogen atoms; and
D is either sulfur, selenium or tellurium.
2. The method of claim 1 , wherein the polymerization conditions comprise a source of free radicals that is an initiator.
3. The method of claim 1 , wherein R 1 is selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted alkoxy, optionally substituted heterocyclyl, optionally substituted alkylthio, optionally substituted amino and optionally substituted polymer chains.
4. The method of claim 1 , wherein R 1 is selected from the group consisting of —CH 2 Ph, —CH(CH 3 )CO 2 CH 2 CH 3 , —CH(CO 2 CH 2 CH 3 ) 2 , —C(CH 3 ) 2 CN, —CH(Ph)CN and —C(CH 3 ) 2 Ph.
5. The method of claim 1 , wherein R 3 and R 4 together form a substituted or unsubstituted pyrazole.
6. The method of claim 1 , wherein the polymerization conditions comprise a temperature in the range of from about 20° C. to about 110° C.
7. The method of claim 1 , wherein two or more monomers are added to said polymerization mixture and said two or more monomers are added sequentially or simultaneously.
8. The method of claim 1 , wherein said polymerization conditions comprise living kinetics.
9. The method of claim 1 , wherein the polymer has a polydispersity index that is less than 1.7.
10. The method of claim 1 , wherein the polymer has a polydispersity index that is between about 1.2 to about 1.4.
11. The method of claim 1 , wherein the M w of the polymer is between about 3,000 and about 20,000.
12. The method of claim 1 , wherein the M w of the polymer is between about 3,000 and about 10,000.
13. The method of any one of claims 1 – 12 , wherein A, B and C are each individually one of
x is at least 1.
14. The method of any one of claims 1 – 12 , wherein A, B and C are each individually one of
and x is at least one.
15. The method of claim 14 , wherein the formula is
16. The method of claim 15 , wherein the M w of the polymer is between about 3,000 and 10,000.
17. The method of claim 15 , wherein the polydispersity index of the polymer is about 1.3.
18. The method of any one of claims 1 – 12 , wherein A, B and C are each individually one of
and x is at least one.
19. The method of claim 18 , wherein the formula is
20. The method of claim 19 , wherein the M w of the polymer is between about 3,000 to about 12,000.
21. The method of claim 19 , wherein the polydispersity index of the polymer is between about 1.1 and about 1.2.
22. The method of any of claims 1 – 12 , wherein A, B and C are each individually one of
and x is at least 1.
23. The method of claim 22 , wherein the formula is
24. The method of claim 23 , wherein the M w is between about 3,000 to about 12,000.
25. The method of claim 23 , wherein the polydispersity index is between about 1.1 and about 1.2.
26. The method of any one of claims 1 – 12 , wherein a terminal end position of the polymer includes a thiocarbonylthio moiety derived from the CTA.
27. The method of any one of claims 1 – 12 , wherein a terminal end position of the polymer includes a termination group having the formula
wherein R′ is CN or COOMe.
28. The method of any of claims 1 – 12 , further comprising a step of treating the resultant polymer with an excess of radical initiator to cleave a CTA fragmentation moiety from a terminal end position of the polymer.
29. The method of claim 28 , further comprising a step of re-precipitating the polymer from a precipitation solvent.