In Situ Rapid Thermal Oxidation and Reduction of Copper Thin Films and Their Applications in Ultralarge Scale Integration

Abstract

Copper is widely accepted as a next-generation metallization material for ultralarge-scale integration ͑ULSI͒ because of its low resistivity and high electromigration resistance. It is well known that Cu oxidizes easily at low temperatures. This characteristic has impeded the application of Cu in integrated circuits. However, the high oxidation rate of Cu and high reduction rate of its oxides at low temperature can be exploited for some potential applications. This paper presents the kinetic studies of Cu film oxidation and in situ reduction of its oxide films. The Cu oxidation experiments were performed in dry and wet oxygen at temperatures from 100 to 600°C for oxidation times from 10 to 718 s. Scanning electron microscopy, Rutherford backscattering spectrometry, spectroscopic ellipsometry and reflectometry, and X-ray photoelectron spectroscopy were used for analyzing the chemical composition of the processed material and determining the oxidation/reduction kinetics of the films. The results showed that the oxide phase is CuO at higher temperature and Cu 2 O at lower temperature ͑Ͻ400°C͒. In situ reduction of copper oxide was studied using secondary ion mass spectroscopy, indicating that the reduction of Cu oxides proceeds from the interface to the surface with a high reduction rate. The infrared reflectivity of Cu surface is over 99%. This is a problem when the Cu process is performed in a rapid thermal processing ͑RTP͒ system, since most of the radiation from the lamps is consequently reflected by the Cu surface. An improved process, called shield-enhanced RTP, results in higher lamp power efficiency and better within wafer temperature uniformity.

UV‐Assisted Low Temperature Oxide Dielectric Films for TFT Applications

“…In the case of the ZrO 2 dielectric film, with or without the Al 2 O 3 bottom layer prepared from Al(OH) 3 precursor solution, the ZrO 2 dielectric is fitted well by both models. The refractive indices of our ZrO 2 film are smaller than those of ZrO 2 produced by DC magnetron sputtering [30] . Figure 5), the surface roughness of the interface was not included in our model.…”

PREPARATION AND CHARACTERIZATION OF In2O3 THIN FILMS FOR OPTOELECTRONIC APPLICATIONS

“…Cu 2 O and Ag 2 O films for ultra large-scale integration applications have been prepared by RTO using halogen lamps at low temperatures. 12,13 Here we report the use of RTO to grow highly oriented In 2 O 3 films and present our investigations on their structural, optical, and electrical properties.…”

Thermal Oxidation of Cu Interconnects Capped with CoWP

“…The CoWP is formed selectively on Cu using electroless plating [5,6]. During the deposition of oxide-based dielectrics by plasma enhanced chemical vapor deposition (PECVD), the CoWP will be briefly exposed to an oxidizing ambient at temperatures of 350 to 400 o C. Both Cu [7,8] and Co [9,10] are known to oxidize at low temperatures (< 400 o C). During the deposition of oxide-based dielectrics by plasma enhanced chemical vapor deposition (PECVD), the CoWP will be briefly exposed to an oxidizing ambient at temperatures of 350 to 400 o C. Both Cu [7,8] and Co [9,10] are known to oxidize at low temperatures (< 400 o C).…”