Electrodeposition of nanotwinned copper structures

Patent metadata

Field	Value
Publication number	US-2022010446-A1
Application number	US-201917309128-A
Country	US
Kind code	A1
Filing date	Oct 28, 2019
Priority date	Oct 31, 2018
Publication date	Jan 13, 2022
Grant date	—

Abstract

A copper structure having a high density of nanotwins is deposited on a substrate. Electroplating conditions for depositing a nanotwinned copper structure may include applying a pulsed current waveform that alternates between a constant current and no current, where a duration of no current being applied is substantially greater than a duration of a constant current being applied. In some implementations, the nanotwinned copper structure is deposited by applying a pulsed current waveform followed by a constant current waveform. In some implementations, the nanotwinned copper structure is deposited on a highly-oriented base layer, where an electroplating solution contains an accelerator additive. In some implementations, the nanotwinned copper structure is deposited on a non-copper seed layer. In some implementations, the nanotwinned copper structure is deposited at a relatively low flow rate.

First claim

1 . A method of depositing a nanotwinned copper structure, the method comprising:
contacting a surface of a substrate with an electroplating solution; and applying a first current to the substrate when the substrate is contacted with the electroplating solution to deposit a nanotwinned copper structure on the substrate, wherein the first current comprises a pulsed current waveform that alternates between a constant current and no current.

2 . The method of claim 1 , wherein the nanotwinned copper structure comprises a plurality of (111)-oriented nanotwinned crystal copper grains.

3 . The method of claim 1 , wherein a duration of no current being applied in the pulsed current waveform is at least three times longer than a duration of constant current being applied in the pulsed current waveform.

4 . The method of claim 1 , wherein the pulsed current waveform alternates between the constant current being applied for a duration between about 0.1 seconds and about 2 seconds, and no current being applied for a duration between about 0.4 seconds and about 6 seconds.

5 . The method of claim 1 , wherein the constant current of the pulsed current waveform has a current density between about 2 A/dm 2 and about 8 A/dm 2 .

6 . The method of claim 1 , wherein the electroplating solution is free of or substantially free of an accelerator additive.

7 . The method of claim 1 , wherein the pulsed current waveform includes a plurality of cycles alternating between the constant current and no current to deposit the nanotwinned copper structure having a thickness of at least 5 μm.

8 . The method of claim 1 , further comprising:
applying a second current to the substrate when the substrate is contacted with the electroplating solution, wherein the second current comprises a constant current waveform.

9 . The method of claim 8 , wherein the first current is applied to the substrate to deposit a first thickness of at least about 1 μm of the nanotwinned copper structure, and wherein the second current is applied to the substrate to deposit a second thickness of the nanotwinned copper structure after the first thickness is deposited.

10 . The method of claim 1 , wherein the substrate comprises a diffusion barrier layer on which the nanotwinned copper structure is deposited, the diffusion barrier layer having a plurality of columnar grain structures.

11 . The method of claim 10 , wherein the electroplating solution includes an accelerator additive.

12 . The method of claim 1 , wherein the substrate comprises a copper seed layer on which the nanotwinned copper structure is deposited, the copper seed layer having a plurality of <111> crystal grain structures.

13 . The method of claim 12 , wherein the electroplating solution includes an accelerator additive.

14 . The method of claim 1 , wherein the substrate comprises a cobalt seed layer on which the nanotwinned copper structure is deposited.

15 . The method of claim 1 , wherein contacting the substrate with the electroplating solution occurs at a flow rate of between about 30 cm/s and about 70 cm/s.

16 . The method of claim 1 , wherein the nanotwinned copper structure is a copper pillar, redistribution layer, or under bump metallization.

17 . An apparatus comprising:
an electroplating cell for holding an electroplating solution; a substrate holder for supporting a substrate during electroplating; a power supply for applying current to the substrate during electroplating; and a controller configured with instructions for performing the following operations:
contact a surface of a substrate with the electroplating solution; and
apply a first current to the substrate when the substrate is contacted with the electroplating solution to deposit a nanotwinned copper structure on the substrate, wherein the first current comprises a pulsed current waveform that alternates between a constant current and no current.

18 . The apparatus of claim 17 , a duration of no current being applied in the pulsed current waveform is at least three times longer than a duration of constant current being applied in the pulsed current waveform.

19 . The apparatus of claim 17 , wherein the electroplating solution is free of or substantially free of an accelerator additive.

20 . The apparatus of claim 17 , wherein the controller is further configured with instructions for performing the following operation:
apply a second current to the substrate when the substrate is contacted with the electroplating solution, wherein the second current comprises a constant current waveform.

21 . The apparatus of claim 17 , wherein the substrate comprises a base layer on which the nanotwinned copper structure is deposited, the base layer being a diffusion barrier layer having a plurality of columnar grain structures or a copper seed layer having a plurality of <111> crystal grains.

Assignees

• Lam Res Corp

Inventors

• Banik Ii Stephen J
• Buckalew Bryan L
• Oberst Justin
• Dua Bhuvan
• Neumann Anica Nicole
• Ponnuswamy Thomas Anand

Classifications

• H10W20/0261

  characterised by the filling method or the material of the conductive fill · CPC title

• H10W20/425

  Barrier, adhesion or liner layers · CPC title

• H10W20/023

  the interconnections being through-semiconductor vias · CPC title

• H10P14/47

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

• C25D7/123

  Semiconductors first coated with a seed layer or a conductive layer · CPC title