Fluorinated interlayer dielectric films in ULSI multilevel interconnections

Abstract

Fluorinated interlayer dielectric films for ultra large scale integrated circuit (ULSI) multilevel interconnections are investigated. The interlayer dielectric film properties and their formation techniques have to meet three requirements such as: (1) a high planarization capability, (2) a low dielectric constant and (3) a low deposition temperature. To satisfy the three requirements, the technologies such as (i) a fluorinated spin-on-glass (SOG) film by fluorotrialkoxysilane vapor treatment (FAST-SOG), (ii) a fluorinated SiO 2 (SiOF) film by room temperature chemical vapor deposition (RTCVD-SiOF) using fluorotrialkoxysilane (FTAS) and pure water as gas sources, (iii) a room temperature liquid phase deposition (LPD) SiO 2 film, and (iv) fluorinated polyimide siloxane (F-PSI) films are desirable. The RTCVD, FAST and LPD techniques have shown the possibility to reduce the film formation temperature to room temperature by catalytic reactions. The dielectric constant for SiO 2 films can be reduced to 3.7 at 1 MHz by using the RTCVD and LPD techniques. The dielectric constant of 2.7 at 1 MHz can be achieved for the F-PSI films, and is lower than those for conventional polyimide films (3.2–3.5) and SiO 2 films (3.9–4.2). Although the FAST-SOG, RTCVD-SiOF and F-PSI films cannot achieve full planarization, the LPD technique can achieve both global and local planarization because this technique has high capability for selective SiO 2 film deposition. The fluorinated films have other good properties such as low residual stress, low residual OH contents and low moisture absorption, which can enlarge the fabrication margins of multilevel interconnections. These other properties are also very effective for improving the ULSI devices performance.