Etch induced sidewall damage evaluation in porous low-k methyl silsesquioxane films J. Vac. Sci. Technol. A 25, 986 (2007); 10.1116/1.2717192 In situ real-time monitoring of profile evolution during plasma etching of mesoporous low-dielectric-constant SiO 2 A highly selective and low-damage damascene process for porous methyl-silsesquioxane ͑porous MSQ, k-2.2͒ films has been realized using a neutral beam system we have developed. Use of a SF 6 or CF 4 neutral beam enables etching of porous MSQ with higher selectivity to the photoresist than what can be obtained in a conventional plasma. This is considered to be because the neutral beam eliminates exposure to ultraviolet ͑UV͒ light which enhances the resist etching. Anisotropic, low-dimension-shift damascene etching of porous MSQ is achieved through the neutral beam system. In addition, an O 2 neutral beam reduces damage to the sidewall of porous MSQ during the resist ashing process. Also, a modified layer generated on porous MSQ during ashing using a H 2 or H 2 /N 2 beam could prevent damage by UV light, which allows more effective resist ashing in a dual damascene structure of porous MSQ. Accordingly, this neutral beam system is a promising candidate for use in porous MSQ damascene processes.

Novel high-temperature (> 150 "C ) ashing using mixture of H2 and He gases (H2Me) was developed for low damage damascene fabrication of ultra low-k ILDs. Dependence of ashing characteristics on generated plasma configuration and temperature was investigated to optimize the process. Its applications to 320nm pitch Cdporous-MSQ (k =2.3) interconnects using 300mm wafers showed no degradation in leakage currents and wiring capacitance.It is feasible for precise dual damascene etch using the conventional ArF photo resist (PR) mask process towards 65 nm technology node.

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Towards the 65 nm technology node, Cu interconnect using high-modulus and low-temperature porous MSQ (k2.3) process has been developed. With an advantage of a lower k value, this process is fairly compatible with the 90 nm-node technology in terms of mechanical strength of low-k film, low thermal budget to suppress S N (Stress Induced Void) failures, and a use of conventional ArF resist mask process. Good electrical results were obtained for 300-mm-wafer Cu dual damascene interconnects using low-pressure CMP and advanced Cu-electroplating / barrier metal processes.