AVS 47th International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS-FrM

Paper PS-FrM10
Surface Studies of the Etching of Low-k Hydrogen SilsesQuioxanes (HSQ) Dielectrics under Medium and High Density Plasma Conditions

Friday, October 6, 2000, 11:20 am, Room 310

Session: Dielectrics II
Presenter: C.H. Low, Chartered Semiconductor Manufacturing Limited, Singapore
Authors: C.N. Ho, Nanyang Technological University, Singapore
C.H. Low, Chartered Semiconductor Manufacturing Limited, Singapore
P. Yelehanka, Chartered Semiconductor Manufacturing Limited, Singapore
A. Cuthbertson, Chartered Semiconductor Manufacturing Limited, Singapore
A. See, Chartered Semiconductor Manufacturing Limited, Singapore
L.H. Chan, Chartered Semiconductor Manufacturing Limited, Singapore
G. Higelin, Nanyang Technological University, Singapore
Correspondent: Click to Email
The need for RC delay reduction, arising from device scaling and increased interconnect complexity, leads to the evolution of vast varieties of low-k inter-metal dielectrics. Doped oxide is the more established group being studied due to its similar composition as SiO@sub 2@. However, issues associated with the film stability, have to be resolved before successful integration of these materials into the multi-level interconnect scheme is achieved. In this work, the chemical aspect of the etching of FOx, one type of SiO@sub 2@-like HSQ materials, is evaluated as part of the feasibility studies towards successful low-k IMD integration. In our previous studies, it was demonstrated that FOx IMD vias can be successfully etched under both medium (MDP) and high density plasma (HDP) conditions. Comparative studies on physical performance were performed. Typically, less FOx sidewall bowing was observed in the case of HDP. In addition, higher FOx etch rate and less FOx removal during in-situ photoresist strip (PRS) can be observed. However, higher Si-H loss is induced as shown by FTIR studies. In this work, we perform surface studies using XPS techniques on patterned wafers etched with MDP and HDP source. The surface chemical composition of partially etched TEOS and FOx as well as the post-resist-stripped etched surfaces is investigated through detailed peak de-convolution analysis. In general, higher C1s with negligible Si2p & O1s signal can be observed on both TEOS and FOx surfaces etched under HDP condition. This suggests the presence of a large amount of CF@sub x@ polymer. De-convolution of the C1s signal further indicates difference in the composition, particularly C/F ratio, of polymeric species formed under MDP and HDP condition. After O@sub 2@ treatment, significantly high Si2p and O1s signal can be observed, indicating oxidation of the etched surface. However, in-situ PRS exhibits additional capability in removing the polymer residues.