Fabrication process of MEMS print head based on silicon-silicon low temperature direct bonding

doi:10.11949/j.issn.0438-1157.20180919

Abstract

Abstract:

Aiming at the processing of complex chamber structure of MEMS piezoelectric integrated print head, a set of fabrication process based on ICP etching combined with silicon-silicon low temperature direct bonding was proposed. Firstly, the upper and lower chamber structures of the print head are separately fabricated by the ICP bulk silicon dry etching process, and then the two silicon wafers with the chamber structures are directly bonded at a low temperature to form a complete print head chamber. Through bonding experiments on the upper and lower chamber structures of the print head, the mechanism of silicon-silicon low temperature direct bonding was further explored and verified. Besides, the effects of different activation methods and annealing time on bonding quality were analyzed, and the bonding process was optimized. The low temperature direct bonding process lays the foundation for the fabrication of MEMS devices with complex three-dimensional structures. The test results show that the finished MEMS print head has a high bonding strength, and the chamber flow channel has good integrity and sealing.

Key words: MEMS, low temperature direct bonding, silicon, activation, interface, print head, fabrication

摘要：

针对一种MEMS压电式集成打印喷头复杂腔室结构的加工，提出了一套基于ICP刻蚀结合硅硅低温直接键合的制作工艺。首先通过ICP体硅干法刻蚀工艺分别制作了打印喷头的上下腔室结构，然后将带有上下腔室结构的两硅片进行低温直接键合，形成完整的打印喷头腔室。通过对打印喷头上下腔室结构的键合实验研究，进一步探索并验证了硅硅低温直接键合的机理，重点研究了不同活化方法和退火时间对复杂腔室结构键合质量的影响，优化了低温直接键合工艺，为带有复杂三维结构的MEMS器件的制作奠定了工艺基础。测试结果表明，制作完成的MEMS打印喷头具有较高的键合强度，且其腔室流道的完整性和密封性良好。

关键词: MEMS, 低温直接键合, 硅, 活化, 界面, 打印喷头, 加工制造

CLC Number:

TP 334.8

Yanzhao ZHAI, Anjiang CAI, Dongpeng ZHANG, Chao HAN, Li LI. Fabrication process of MEMS print head based on silicon-silicon low temperature direct bonding[J]. CIESC Journal, 2019, 70(3): 1220-1226.

翟彦昭, 蔡安江, 张栋鹏, 韩超, 李力. 基于硅硅低温直接键合的MEMS打印喷头制作工艺[J]. 化工学报, 2019, 70(3): 1220-1226.

Figures/Tables 9

Fig.1 Structure of MEMS piezoelectric integrated print head

Fig.2 Print head fabrication process

Fig.3 Wafers with upper and lower chamber structure

Fig.4 Wafer bonding process

Table 1 Comparative experiment of different activation methods and annealing time

Comparative experiment group		Activation method	Annealing time/h
group 1	A	O₂ plasma	4
	B		6
	C		8
	D		10
group 2	E	O₂ plasma + High concentration oxidizing ammonia solution	4
	F		6
	G		8
	H		10

Fig.5 Rolling pressure applied during pre-bonding

Fig.6 Bonding quality inspection of head samples

Fig.7 Effect of different activation methods and annealing time on bonding strength

Fig.8 Part of sample bonding interface after breaking

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