Chemistry additives and process for cobalt film electrodeposition

Patent metadata

Field	Value
Publication number	US-2016273117-A1
Application number	US-201514663279-A
Country	US
Kind code	A1
Filing date	Mar 19, 2015
Priority date	Mar 19, 2015
Publication date	Sep 22, 2016
Grant date	—

Abstract

Various embodiments herein relate to methods and apparatus for electroplating cobalt on a substrate. In many cases, the cobalt is electroplated into recessed features. The recessed features may include a seed layer such as a cobalt seed layer. Electroplating may occur through a bottom-up mechanism. The bottom-up mechanism may be achieved by using particular additives (e.g., accelerator and suppressor), which may be present in the electrolyte at particular concentrations. Further, leveler, wetting agent, and/or brightening agents may be used to promote high quality plating results. In various embodiments, the substrate is pre-treated to remove oxide (and in some cases carbon impurities) from the seed layer before electroplating takes place. Further, the electrolyte may have a particular conductivity to promote uniform plating results across the face of the substrate.

First claim

What is claimed is:

1 . A method of electroplating cobalt into recessed features on a substrate, the method comprising:
receiving the substrate in an electroplating chamber, the substrate comprising recessed features having a cobalt seed layer thereon, the cobalt seed layer having a thickness of about 50 Å or less, and the recessed features having a width between about 10-150 nm; immersing the substrate in electrolyte, the electrolyte comprising boric acid, halide ions, cobalt ions, and organic additives for achieving seam-free bottom-up fill in the recessed features; and electroplating cobalt into the features under conditions that provide bottom-up fill, wherein a plating potential at the substrate during electroplating has a magnitude between about 1.0-3.5 V vs. a HgSO 4 mercury sulfate reference electrode.

2 . The method of claim 1 , wherein the electrolyte has a conductivity of about 10 mS/cm or less.

3 . The method of claim 1 , wherein the electrolyte has a cobalt ion concentration of about 5 g/L or less.

4 . The method of claim 1 , wherein the organic additives comprise a suppressor that comprises a nitrogen-containing group.

5 . The method of claim 4 , wherein the suppressor comprises an amine group.

6 . The method of claim 5 , wherein the suppressor comprises polyethyleneimine (PEI).

7 . The method of claim 1 , wherein the organic additives comprise an accelerator, the accelerator being selected from the group consisting of 3-mercapto-1-propane sulfonic acid sodium salt (MPS), thiourea, and combinations thereof.

8 . The method of claim 7 , wherein the organic additives further comprise a suppressor comprising polyethyleneimine (PEI).

9 . The method of claim 8 , wherein the suppressor is present in the electrolyte at a concentration between about 10-60 ppm, wherein the accelerator is present in the electrolyte at a concentration between about 150-400 ppm, and wherein electroplating occurs at a constant current density during bottom-up fill, the current density being between about 0.5-7 mA/cm 2 .

10 . The method of claim 1 , wherein the organic additives comprise an accelerator and a suppressor, and wherein a ratio of the concentration of accelerator to the concentration of suppressor in the electrolyte is at least about 3:1, as measured in ppm.

11 . The method of claim 10 , wherein the concentration of accelerator in the electrolyte is between about 150-500 ppm and wherein the concentration of suppressor in the electrolyte is between about 10-60 ppm.

12 . The method of claim 1 further comprising:
before receiving the substrate in the electroplating chamber, pre-treating the substrate by exposing the substrate to a remotely generated hydrogen-containing plasma to thereby reduce oxides present on the cobalt seed layer.

13 . The method of claim 12 , wherein the remote plasma pre-treatment reduces the seed layer's sheet resistance by at least about 15% to a value that is between about 50-1000 Ω/cm 2 .

14 . The method of claim 1 , further comprising:
before receiving the substrate in the electroplating chamber, annealing the substrate at a temperature of at least about 75° C. while the substrate is exposed to reducing gas to thereby reduce oxides present on the cobalt seed layer.

15 . The method of claim 14 , wherein the anneal pre-treatment reduces the seed layer's sheet resistance by at least about 15% to a value that is between about 50-1000 Ω/cm 2 .

16 . The method of claim 1 , wherein the substrate is immersed at open circuit conditions, and wherein an induction period occurs after immersion, during which no voltage or current is applied to the substrate, the induction period having a duration between about 0.5-5 seconds.

17 . The method of claim 1 , wherein the electrolyte further includes a leveler and/or wetting agent.

18 . The method of claim 17 , wherein the leveler and/or wetting agent comprises polyethylene glycol (PEG), the PEG being present in electrolyte at a concentration between about 10-500 ppm.

19 . The method of claim 18 , wherein the electroplated cobalt has an RMS roughness of about 3 nm or lower.

20 . The method of claim 1 , wherein the electrolyte comprises:
(i) between about 0.5-5 g/L cobalt(II) ions, (ii) between about 2-35 g/L boric acid, (iii) between about 0.1-0.3 g/L polyethylene glycol, and (iv) a pH between about 4-6.

21 . The method of claim 1 , wherein the electrolyte comprises:
(i) an accelerator selected from the group consisting of: N,N-dimethyl-dithiocarbamic acid (-3-sulfopropyl)ester, 3-mercapto-propylsulfonic acid-(3-sulfurpropyl) ester, 3-sulfanyl-1-propane sulfonate, carbonic acid-dithio-o-ethylester-s-ester with 3-mercapto-1-propane sulfonic acid potassium salt, bis-sulfopropyl disulfide, 3-(benzothiazolyl-s-thio)propyl sulfonic acid sodium salt, pyridinium propyl sulfobetaine, 1-sodium-3-mercaptopropane-1-sulfonate, N,N-dimethyl-dithiocarbamic acid-(3-sulfoethyl)ester, 3-mercapto-ethyl propylsulfonic acid (3-sulfoethyl)ester, 3-mercapto-ethylsulfonic acid sodium salt, carbonic acid-dithio-o-ethyl ester-s-ester, pyridinium ethyl sulfobetaine, thiourea, and combinations thereof; and (ii) a suppressor selected from the group consisting of: carboxymethylcellulose, nonylphenolpolyglycol ether, polyethylene glycoldimethyl ether, octandiolbis(polyalkylene glycol ether), octanol polyalkylene glycol ether, oleic acid polyglycol ester, polyethylene propylene glycol, polyethylene glycol, polyethyleneimine, polyethylene glycoldimethyl ether, polyoxypropylene glycol, polypropylene glycol, polyvinyl alcohol, stearic acid polyglycol ester, stearyl alcohol polyglycol ether, polyethylene oxide, ethylene oxide-propylene oxide copolymers, butyl alcohol-ethylene oxide-propylene oxide copolymers, 2-Mercapto-5-benzimidazolesulfonic acid, 2-mercaptobenzimidazole (MBI), benzotriazole, and combinations thereof.

22 . The method of claim 21 , wherein the electrolyte further comprises:
(iii) a leveler selected from the group consisting of: alkylated polyalkyleneimines, polyethylene glycol, organic sulfonates, 4-mercaptopyridine, 2-mercaptothiazoline, ethylene thiourea, thiourea, 1-(2-hydroxyethyl)2-imidazolidinethion, sodium naphthalene 2-sulphonate, acrylamide, substituted amines, imidazole, triazole, tetrazole, piperidine, morpholine, piperazine, pyridine, oxazole, benzoxazole, quinolin, isoquinoline, coumarin, butyne 1:4 diol and derivatives thereof, and combinations thereof; (iv) a wetting agent selected from the group consisting of: alkyl phenoxy polyethoxyethanols, compounds of polyoxyethylene and polyethyleneglycol polymers, block and random copolymers of polyoxyethylene and polyoxypropylene, and combinations thereof; and (v) a brightening agent selected from the group consisting of: 3-sulfanyl-1-propane sulfonate, 2-mercapto-ethane sulfonic acid sodium salt, bisulfopropyl disulfide, N,N-dimethyldithiocarbamic acid ester sodium salt, (o-ethyldithiocarbonato)-S-(3-sulfurpropyl)-ester potassium salt, 3-[(amino-iminomethyl)-thio]-1-propane sulfonic acid sodium salt, phenolphthalein, lactone, lactams, cyclic sulfate esters, cyclic imides, cyclic oxazolinones, assymetrical alkyne sulfonic acids, (N-substituted pyridyl)-alkyl sulfonic acid betaines, amino polyarylmethanes, pyridine derivatives, quinoline derivatives, sulfonated aryl aldehydes, and combinations thereof.

23 . The method of claim 1 , wherein the magnitude of the plating potential at the substrate during electroplatin

Assignees

• Lam Res Corp

Inventors

• Doubina Natalia V
• Rigsby Matthew A
• Reid Jonathan David

Classifications

• H10P14/47

  Electrolytic deposition, i.e. electroplating; Electroless plating · CPC title

• H10W20/4441

  the principal metal being a refractory metal · CPC title

• H10W20/0526

  by thermal treatment thereof · CPC title

• H10W20/0523

  by irradiating with ultraviolet or particle radiation · CPC title

• H10W20/056

  by filling conductive material into holes, grooves or trenches · CPC title