Search

EP-3781728-B1 - COMPOSITION FOR COBALT OR COBALT ALLOY ELECTROPLATING

EP3781728B1EP 3781728 B1EP3781728 B1EP 3781728B1EP-3781728-B1

Inventors

  • ARNOLD, MARCO
  • WEI, Chiao Chien
  • HUANG, TZU TSANG
  • LIN, SHIH MING
  • KUO, Cheng Chen
  • CHOU, SHIH WEI
  • CHU, CHIEH

Dates

Publication Date
20260506
Application Date
20190405

Claims (12)

  1. A composition comprising (a) cobalt ions, (b) an ammonium compound of formula (NR 1 R 2 R 3 H + ) n X n- (c) a suppressing agent of formula S1 wherein R 1 , R 2 , R 3 are independently selected from H and linear or branched C 1 to C 6 alkyl; X is selected from an n valent inorganic or organic counter ion; n is an integer selected from 1, 2 or 3; R S1 is selected from X S -Y S ; R S2 is selected from R S1 and R S3 ; X S C 2 is selected from linear or branched C 1 to C 10 alkanediyl, linear or branched to C 10 alkenediyl, linear or branched C 2 to C 10 alkynediyl, and (C 2 H 3 R S6 -O) m -H; Y S is selected from OR S3 , NR S3 R S4 , N+R S3 R S4 R S5 and NH-(C=O)-R S3 ; R S3 , R S4 R S5 C 20 are the same or different and are selected from (i) H, (ii) C 5 to aryl, (iii) C 1 to C 10 alkyl (iv) C 6 to C 20 arylalkyl, (v) C 6 to C 20 alkylaryl, which may be substituted by OH, SO 3 H, COOH or a combination thereof, and (vi) (C 2 H 3 R 6 -O) p -H, and wherein R S3 and R S4 may together form a ring system, which may be interrupted by O or NR S7 ; m, p are an integers independently selected from 1 to 30; R S6 is selected from H and C 1 to C 5 alkyl; R S7 is selected from R S6 and and wherein the composition has a boric acid content below 0.1 g/l.
  2. A composition according to claim 1, wherein R 1 , R 2 , and R 3 are independently selected from H and a linear or branched C 1 to C 4 alkyl.
  3. A composition according to anyone of the preceding claims, wherein at least two of R 1 , R 2 and R 3 are H, preferably all of R 1 , R 2 , and R 3 are H.
  4. A composition according to anyone of the preceding claims, wherein X is an inorganic counter-ion, particularly chloride, sulfate, hydrogen sulfate, phosphate, hydrogen phosphate, dihydrogen phosphate, and nitrate.
  5. A composition according to anyone of the preceding claims, wherein X is chloride.
  6. A composition according to anyone of claims 1 to 3, wherein X is an organic counter-ion, particularly C 1 to C 6 alkyl sulfonate, C 1 to C 6 carboxylates, phosphonates, and sulfamates.
  7. A composition according to anyone of the preceding claims, wherein the suppressing agent is (a) an aminoalkyne, wherein (i) R S1 is X S -NR S3 R S4 and R S2 is H; or (ii) R S1 is X-NR S3 R S4 and R S2 is X S - NR S3 R S4 with X S being selected from linear C 1 to C 4 alkanediyl and branched C 3 to C 6 alkanediyl; (b) a hydroxyalkyne, wherein (i) R S1 is X S -OR S3 and R S2 is H; or (ii) R S1 is X S -OR S3 and R S2 is X S - OR S3 with X S being selected from linear C 1 to C 4 alkanediyl and branched C 3 to C 6 alkanediyl; (c) an alkyne comprising an amino and a hydroxy group, wherein R S1 is X-OR 3 , particularly X S -OH, and R S2 is X S - NR S3 R S4 with X S being independently selected from linear C 1 to C 4 alkanediyl and branched C 3 to C 6 alkanediyl.
  8. A composition according to anyone of the preceding claims further comprising a leveling agent comprising the structure of formula L1 [B] n [A] p (L1) or having the structure of formula L2 or comprising the structure of formula L3a or L3b or having the structure of formula L4 Ø-R 1 (L4) and their salts, wherein R 1 is selected from X 1 -CO-O-R 11 , X 1 -SO 2 -O-R 11 , X 1 -PO(OR 11 ) 2 , X 1 -SO-O-R 11 ; R 2 are independently selected from (i) H, (ii) aryl, (iii) C 1 to C 10 alkyl (iv) arylalkyl, (v) alkylaryl, and (vi) -(O-C 2 H 3 R 12 ) m -OH, R 3 is selected from R 1 and R 2 ; R 4 is selected from R 2 and, in case R 3 is R 2 , R 4 may also be R 1 , Ø is a C 6 to C 14 carbocyclic or a C 3 to C 10 nitrogen or oxygen containing heterocyclic aryl group, which may be unsubstituted or substituted by up to three C 1 to C 12 alkyl groups or up to two OH, NH 2 or NO 2 groups, R 31 is selected from R 1 , H, OR 5 and R 5 , X 1 is a divalent group selected from (i) a chemical bond (ii) aryl, (iii) C 1 to C 12 alkandiyl, which may be interrupted by O atoms, (iv) arylalkyl group -X 11 -X 12 -, (v) alkylaryl group -X 12 -X 11 -, and (vi) -(O-C 2 H 3 R 12 ) m O-, X 2 is (i) a chemical bond or (ii) methanediyl, R 11 is selected from H and C 1 to C 4 alkyl, R 12 is selected from H and C 1 to C 4 alkyl, X 12 is a divalent aryl group, X 11 is a divalent C 4 to C 15 alkandiyl group, A is a co-monomer selected from vinyl alcohol, which may optionally be (poly)ethyoxylated, and acrylamide, B is selected from formula L1a n is an integer from 2 to 10 000, m is an integer from 2 to 50, o is an integer from 2 to 1 000, and p is 0 or an integer from 1 to 10 000.
  9. The composition according to claim 8, wherein the leveler is selected from polyacrylic acid, a maleic acid acrylic acid copolymer, polyphosphonic acid, polysulfonic acid, acrylic acid, vinylphosphonic acid, vinylsulfonic acid, and p-toluol sulfonate.
  10. The composition according to anyone of the preceding claims, wherein the composition further comprises a suppressing agent selected from a hydroxy alkyne, C 1 to C 6 alkoxy alkyne or an amino alkyne.
  11. Use of a composition according to anyone of the preceding claims for depositing cobalt into interconnect features or for providing a cobalt under bump metallization.
  12. A process for depositing cobalt on a semiconductor substrate comprising a recessed feature having an aperture size of 1 nanometer to 100 micrometers, the process comprising (a) bringing a composition according to anyone of claims 1 to 10 into contact with the semiconductor substrate, (b) applying a potential for a time sufficient to fill the recessed feature with cobalt.

Description

The present invention relates to a composition for cobalt or cobalt alloy electroplating. Background of the Invention Filling of small features, such as vias and trenches, by metal electroplating is an essential part of the semiconductor manufacture process. It is well known, that the presence of organic substances as additives in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface and in avoiding defects, such as voids and seams, within the metal lines. With further decreasing aperture size of recessed features like vias or trenches the filling of the interconnects with copper becomes especially challenging, also since the copper seed deposition by physical vapor deposition (PVD) prior to the copper electrodeposition might exhibit inhomogeneity and non-conformity and thus further decreases the aperture sizes particularly at the top of the apertures. Furthermore, it becomes more and more interesting to substitute copper by cobalt since cobalt shows less electromigration into the dielectric. WO 2017/004424 discloses a composition for cobalt electroplating into interconnect features comprising an acetylenic suppressor compound and preferably a buffer. A preferred buffer is boric acid. The only example comprises boric acid, too. DE 10 2014 019753 A1 discloses a boric acid free nickel electroplating bath comprising ammonium chloride. JP 62-103387 A discloses an electroplating bath for depositing metals like Ni, Co, Fe, etc. which comprises a buffer. The Co composition in example 10 comprises citrate as the buffer. WO 2018/015168 A1 discloses a composition and process for depositing cobalt on a semiconductor substrate comprising a recessed feature having an aperture size having nanometer or micrometer scale that uses a composition comprising cobalt ions and an alkyne-type additive. On the other hand, cobalt may also be a substitute of copper in other applications like under bump metallization. In this case much bigger structures comprising micrometer-sized aperture size are used. Besides a void free filling in this application it is of particular importance that all features are equally filled with cobalt so that all bump on which the solders are to be deposited show essentially the same height. A disadvantage of the existing cobalt electrodeposition baths is the pronounced non-uniformity of the electrodeposited cobalt layer. There is still a strong need for a cobalt electroplating bath which provides, besides void-free filling of submicrometer-sized interconnects, a substantially planar surface over the filled features. There is also a strong need for a cobalt electroplating bath which provides a cobalt under bump metallization showing a low non-uniformity over the filled features. It is therefore an object of the present invention to provide a composition useful for cobalt electrodeposition which improves the non-uniformity of the cobalt deposit across the wafer. Summary of the Invention It was found that it is possible to reduce the non-uniformity in cobalt electroplating compositions by using particular ammonium compounds as described below, particularly if applied to substrates comprising micrometer-sized solder bump features. Therefore, the present invention provides a composition as defined in claim 1. The invention further relates to the use of a metal plating composition as defined herein for depositing cobalt into interconnect features or for providing a cobalt under bump metallization. The invention further relates to a process for depositing a layer comprising cobalt on a substrate comprising features having an aperture size of 1 nanometer to 100 micrometers, by a) contacting a composition as defined herein with the substrate, andb) applying a current density to the substrate for a time sufficient to deposit a metal layer onto the substrate. By using the ammonium compound according to the invention, the non-uniformity of the cobalt deposit across the wafer is significantly improved. A further advantage of the present invention is that by using the ammonium compounds described herein avoids the use of boric acid, which is a big advantage for health, safety and environmental reasons. Therefore, a further object of the present invention to provide a composition useful for cobalt electrodeposition which is boric acid free. Detailed Description of the Invention The compositions according to the inventions comprise cobalt ions, and an ammonium compound as described below. It further comprises a suppressing agent of formula S1 (as decribed below) and has a boric acid content below 0.1 g/l. Ammonium compound The cobalt or cobalt alloy electroplating composition comprises an ammonium compound of formula (NR1R2R3H+)nXn-. Herein, R1, R2, and R3 are independently selected from H, linear or branched C1 to C6 alkyl. Preferably, R1, R2, and R3 are independently selected from H and a linear or branched C1 to C4 alkyl, particularly methyl and ethyl. More preferably at le