Surface modification on hydrophilicity enhancement using NH<sub>4</sub>OH, NaOH, and KOH on fine-pitch low-temperature Cu/SiO<sub>2</sub> Hybrid Bonding
Jia-Juen Ong, Dinh-Phuc Tran, Wei-Lan Chiu, Yuan Chen, Ou-Hsiang Lee, Hsiang-Hung Chang, Chih Chen
Abstract
A novel plasma-free hydrophilicity surface modification treatment on PECVD SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> dielectric layer is proposed in this paper. Different alkaline chemicals such as ammonia (NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> OH), sodium hydroxide (NaOH), and potassium hydroxide (KOH) are used as pretreatment solutions. By using this pretreatment prior to the bonding process, we found the contact angle of water decreased significantly. Cu etching issue is further discussed while no serious variation in surface roughness of Cu after KOH and NaOH pretreatment. Cross-sectional HR TEM shows excellent bonding quality and no contamination signal of residual pretreatment solution detected by TEM-EDS. Low specific contact resistivity of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> Ω/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was detected at kelvin structure.