IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Dielectrics Wednesday Sessions
       Session DI-WeA

Paper DI-WeA6
Formation of Self-Assembled Molecular Layers on the Low Dielectric Porous Methyl Silsesquioxane

Wednesday, October 31, 2001, 3:40 pm, Room 130

Session: Low K Dielectrics
Presenter: J.C. Hu, National Tsing Hua University, Taiwan, R.O.C.
Authors: J.C. Hu, National Tsing Hua University, Taiwan, R.O.C.
C.W. Wu, National Tsing Hua University, Taiwan, R.O.C.
L.J. Chen, National Tsing Hua University, Taiwan, R.O.C.
C.H. Li, National Chiao Tung University, Taiwan, R.O.C.
T.C. Chang, National Sun Yat-Sen University, Taiwan, R.O.C.
C.J. Chu, Nanmat Technology Co., Taiwan, R.O.C.
Correspondent: Click to Email
Porous methyl silsesquioxane (PMSQ) with a low dielectric constant (~1.8) is of great interest for ULSI applications. However, many hydrophilic methyl groups (-CH@sub 3@) on the PMSQ were destroyed under O@sub 2@ plasma ashing. Hydroxyl groups (-OH) were bonded with Si dangling bonds on the PMSQ films. H@sub 2@ plasma post-treatment is usually used to decrease -OH bond formation. In the present work, bottom-up growth behavior of self-assembled molecular layers (SAMs) on the PMSQ was investigated. Diclorodimethylsilane was used to form SAMs on the PMSQ at the room temperature. Structural properties of the PMSQ films were investigated using FTIR. The absorption peaks of Si-C (781 cm@super -1@), Si-C (1273 cm@super -1@), and C-H (2975 cm@super -1@) in PMSQ samples disappeared after O@sub 2@ plasma treatment for 5 min. It indicated that the majority of methyl groups in the films were removed and Si dangling bonds were exposed. The Si-O cage-like structures in the PMSQ films also decreased due to its loose structure arrangement. As a result, the low dielectric characteristic of PMSQ would be damaged. On the other hand, the absorption peaks of Si-C and C-H were present for the PMSQ films dipped in diclorodimethylsilane solution with and without ultrasonic system. The purpose of using ultrasonic system was to accelerate formation rate of SAMs on the PMSQ. The results revealed that the hydrophobic dimethylsilane groups have been formed on the surface of PMSQ. The Si-OH bonds on the PMSQ changed to Si-O-Si(CH@sub 3@)@sub 2@. The thickness of SAMs was less than 1.0 nm. The -CH@sub 3@ groups of SAMs on the Si-O network surface of the PMSQ films were apparently of ordered array structure owing to minimal steric hindrance arrangement.