Chemical Repair of Plasma Damaged Porous Ultra Low-k SiOCH Film using a Vapor Phase Process

Abstract

A vapor phase based silylation process was used to restore plasma damaged porous ultra low-κ SiOCH dielectric films. The process was carried out with eleven different silylation agents. After processing of blanked wafers, the restoration performance was characterized by different analytic techniques like Fourier Infrared and Auger electron spectroscopy as well as contact angle and mercury probe measurements. Quantum mechanics calculations and practical results suggest three repair chemicals having two reactive groups to be most promising. However, a comparable electrical improvement, i.e. κ-value improvement was achieved with chemicals having one reactive group. A thin dielectric layer formation was found to be one explanation for this effect. This is supported by a high surface free energy recovery after the repair process, without carbon incorporation near the surface. Hence, depending on the requirement to the restoration (κ-value, carbon restoration, etc.) chemicals having one reactive group can be sufficient as well.

Use of a Thermally Degradable Chemical Vapor Deposited Polymer Film for Low Damage Plasma Processing of Highly Porous Dielectrics

“…Nowadays, for CMOS interconnect manufacturing, the CO 2 ash , is an industry standard, due to its limited damage in comparison with other reference processes, such as O 2 or N 2 –H 2 . This has been attributed to a combination of multiple reasons, which depend on the particular used plasma conditions: lower density of atomic oxygen, , high rate of surface nondissociative neutralization of CO 2 + ions, weaker VUV emission, and surface pore sealing . Although bulk ULK damage is lower than for other processes, the CO 2 ash causes carbon depletion, confined within a few nanometers of the surface. , This is of key importance for advanced nanointerconnects, which target 32 nm pitch at imec’s iN5 technology node.…”