A study on the structures and properties of low temperature wafer bonding

• Main Authors: Ying-Hung Cheng, 鄭穎鴻
• Other Authors: 蘇程裕
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/vj9235

碩士 === 國立臺北科技大學 === 製造科技研究所 === 100 === Currently, the increase in development of electronic industry, minimization, multi-functions and low cost of an electronic product is the significant challenge to the semiconductor industry in two-dimensional integrated circuits (2DICs). As a result, three-dimensional integrated circuits (3DICs) have been proposed as promising solution to all of the issues. In this study, we focus on the silicon-silicon bonding with high tensile strength. Meanwhile, the demands of low cost and simplified manufacturing process are also investigated. The silicon-silicon bonding was achieved completely by using the diffusion bonding technique. The experimental steps show as follows: firstly, Cr thin films were deposited on silicon substrate as barrier layer to prevent the Cu diffusion. Then, the bonding layers were prepared by sputtering of Cu target. Prior to thermal-compression bonding, the silicon substrates were dipped in acidic solution to remove any native oxide existing on the Cu surface. The surface-activated bonding process for Cu-Cu was performed in the vacuum system under low temperature. The microstructure of the bonding interface was observed by OM and SEM; in addition, the diffusion process was confirmed by EPMA. Finally, the strength and quality of the bonding structure were identified by durability test and adhesion test. The result show that wet pretreatment could effectively remove the native Cu oxide, which led to easy diffusion of Cu atoms into the other Cu layer. Higher bonding temperature helps to improve the mechanical strength, the maximum tensile strength of the layer can reach 10 Mpa at 350℃1hr.