高均匀性的铜柱凸块电镀

doi:10.13208/j.electrochem.2213004

摘要/Abstract

摘要：

随着电子产品的小型化、多功能化和高性能化的发展,促使着2D集成封装向2.5D或3D集成封装发展。铜柱凸块电镀是晶圆级三维封装的关键基础技术之一。本文研究了铜柱凸块的电镀均匀性与添加剂浓度、镀液对流、电流密度和电镀设备之间的影响规律。研究结果表明, 添加剂浓度、镀液对流以及电流密度对单个铜柱凸块的平整度影响较大,而对铜柱凸块高度的均一性影响较小。相反,电镀设备对铜柱凸块的高度均一性的影响较大, 而对铜柱凸块的平整度影响较小。在三种有机添加剂中, 整平剂对铜柱凸块的平整度影响最大, 随着镀液中整平剂浓度的增加,铜柱凸块顶部形状由凸起、变为平整、再转变为凹陷。电镀液的单向对流会导致所沉积铜柱凸块形貌发生倾斜。高的电流密度会导致凸顶的铜柱凸块形貌。精密设计的电镀设备可以提高晶圆上电流密度分布的均匀性, 继而大幅提高电镀铜柱凸块的共面性。本文的研究结果可为铜柱凸块的电镀优化提供指导。

关键词: 铜柱凸块, 电化学沉积, 均匀性, 添加剂, 整平剂

Abstract:

Electrochemical deposition of copper pillar bumps (CPBs) is one of the key technologies for the advanced packaging. In this study, the effects of the additive concentration, the electrolyte convection, the current density, and the electroplating system on the uniformity of the CPBs have been systematically investigated. The results showed that the profiles of the CPBs were mainly determined by the additive concentration, the bath convection and the current density, while the heights of the CPBs were mainly affected by the electroplating system. For the CPBs profiles, it was found that the low leveler concentration and high current density would generally result in domed shape, while the uneven agitation would lead to inclined surface. For the heights of CPBs, the macroscopic uniformity could be dramatically improved by a sophisticatedly designed electroplating system. These results can provide basic guidance for the optimization of the CPBs electroplating.

Key words: copper pillar bump, electrochemical deposition, uniformity, additive, leveler

谭柏照, 梁剑伦, 赖子亮, 罗继业. 高均匀性的铜柱凸块电镀[J]. 电化学（中英文）, 2022, 28(7): 2213004.

Bai-Zhao Tan, Jian-Lun Liang, Zi-Liang Lai, Ji-Ye Luo. Electrochemical Deposition of Copper Pillar Bumps with High Uniformity[J]. Journal of Electrochemistry, 2022, 28(7): 2213004.

图/表 11

参考文献 22

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Test	B (mL·L^-1)	C (mL·L^-1)	L (mL·L^-1)	TIR_avg	WID
1	1	5	1	17.2%	15.8%
2	1	10	3	-0.8%	14.6%
3	1	20	5	-5.3%	16.7%
4	2	5	3	0.3%	18.2%
5	2	10	5	-4.2%	19.4%
6	2	20	1	21.9%	14.5%
7	4	5	5	-7.3%	19.8%
8	4	10	1	21.6%	13.7%
9	4	20	3	-0.5%	18.1%
TIR_avg
k1	3.7%	3.4%	20.3%
k2	6.0%	5.5%	-0.3%
k3	4.6%	5.4%	-5.6%
R	2.3%	2.1%	25.9%
WID
k1	15.7%	17.9%	14.7%
k2	17.4%	15.9%	17.0%
k3	17.2%	16.4%	18.6%
R	1.6%	2.0%	4.0%

Flow condition	TIR_avg	WID
X- axis unidirectional flow	-10.2%	14.1%
Y- axis unidirectional flow	10.3%	12.1%
Reversible flow	2.6%	12.9%

Electroplating equipment	Area	Average height of CPBs (μm)	TIR_avg	WID
Vertical Plating Equipment	Ⅰ	36.4	6.2%	19.3%
	Ⅱ	26.6	2.6%	5.7%
	Ⅲ	24.3	3.9%	4.2%
Horizontal Plating Equipment	Ⅰ	38.5	3.8%	6.0%
	Ⅱ	38.1	3.6%	2.7%
	Ⅲ	37.7	3.5%	2.3%