AVS 47th International Symposium
    Incorporating Principles of Industrial Ecology Tuesday Sessions
       Session IE-TuA

Paper IE-TuA10
High Throughput Process for Photoresist Stripping and Residual Polymer Removal in a Via Post-Etch Process

Tuesday, October 3, 2000, 5:00 pm, Room 304

Session: Green Manufacturing
Presenter: M. Boumerzoug, Ulvac Technologies Inc.
Authors: M. Boumerzoug, Ulvac Technologies Inc.
Q. Geng, Ulvac Technologies Inc.
H. Xu, Ulvac Technologies Inc.
S. Gu, LSI Logic Corporation
S. Goh, Silterra (M) Sdn. Bhd.
T. Meyer, LSI Logic Corporation
J. Seaton, LSI Logic Corporation
Correspondent: Click to Email
In fabricating advanced IC, a multi-level interconnect scheme is commonly used and plasma etch is applied to form metal lines and via holes. During the plasma etch, a sidewall polymer is formed to control the etch profile. After the etch, the sidewall polymer needs to be removed completely to insure a good via contact resistance. Typically, a very aggressive amine based chemical solvent is needed to clean up the sidewall polymer. As the design rule shrinks and aggressive zero overplot of the metal line and via plug is used to minimize the die size, some degree of misalignment between via plug and metal lines is inevitable. Wet chemical based post etch cleaning starts to show problems for the misaligned via and metal because they may attack exposed Ti, W and Al. An advanced dry clean process has been developed for removing post etch polymer. In addition, the dry clean process offers a lower cost of ownership (COO) than the wet clean process and is much safer and environmentally friendly. This technology utilizes the combination of microwave downstream and non-damage ion assisted processes to strip chemically altered and damaged photoresist and clean residue according to the chemical composition of each layer. The ion-assisted process is also found useful in stripping the photoresist at high rate. After this dry process, no wet strippers are needed; thus, the high cost and environment and safety concern associated with chemicals can be eliminated. In some cases, this dry clean process becomes an enabling technology for avoiding Ti and W-plug attack occurring in the wet cleaning processes. Split lots of wafers, which have two layer metal, were processed by the all-dry processes and tested electrically. The via chain resistance, metal bridging yield, metal continuity and electrical CD are all equal or better than the control wafers which were processed by wet chemicals.