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TiN Diffusion Barrier Formation by Pulsed Source Chemical Vapor Deposition method

Published online by Cambridge University Press:  10 February 2011

Hyeongtag Jeon
Affiliation:
Dept. of Metallurgical Engineering, CRPC, Hanyang Univ., Seoul, Korea 133–791
Sangsoo Lee
Affiliation:
Dept. of Metallurgical Engineering, CRPC, Hanyang Univ., Seoul, Korea 133–791
Taehang Ahn
Affiliation:
Dept. of Metallurgical Engineering, CRPC, Hanyang Univ., Seoul, Korea 133–791
Jangwoong Uhm
Affiliation:
Dept. of Metallurgical Engineering, CRPC, Hanyang Univ., Seoul, Korea 133–791
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Abstract

TiN film is applied as a diffusion barrier and an adhesion promotion layer in the ultralarge scale integrated circuit (ULSI) devices. These TiN thin films are usually deposited by sputtering and chemical vapor deposition (CVD) methods. The CVD method is now studied intensively due to its satisfiable step coverage and compatibility with current device fabrication process. There are several different CVD methods already proposed such as LPCVD, MOCVD and PECVD. These proposed CVD methods have many disadvantages such as impurity incorporation and particle generation due to gas phase reactions between source and reactant gases. To solve these problems, we propose a new CVD method to reduce impurities and particles which is the pulsed source chemical vapor deposition (PS-CVD) method. In this method, the source, reactant and purge gases are introduced into reaction chamber, separately. TiN films are deposited using TiCl4, NH3 and Ar by alternately introducing into reaction chamber. In detail, TiCl4 source is introduced and adsorbed on Si substrate and then Ar gas purges this source gas. Continuously, NH3 gas in supplied into reaction chamber and adsorbed on the Ti-adsorbed Si substrate and then Ar gas is again introduced to purge NH3 gas. These four steps are one cycle. The main variables in this experiment are source pulse time, source purge time, reactant pulse time, reactant purge time, and so on. The deposition characteristics are also different depending on substrate temperatures. Above the thermal decomposition temperatures, the film thickness is a function of the source pulse time like conventional CVD. Below the thermal decomposition temperatures, the film thickness is saturated and exhibits a constant value in this temperature range. The TiN film thickness depends only on the number of deposition cycle. The process window were determined by experimentally in this temperature range. Process variables were established, and then TiN films were deposited. The characteristics of this TiN diffusion barrier were analyzed. The surface microroughness, the chemical composition and contaminant contents were measured by AFM, SEM and AES. A crystal structure and the phase identification were performed with using XRD and the sheet resistance was measured by a four point probe. These results will be discussed and compared with the results of TiN formed by sputtered and conventional CVD methods.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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