AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP8
Effect of Film Properties on Nitride Etching

Thursday, November 1, 2012, 6:00 pm, Room Central Hall

Session: Plasma Science and Technology Poster Session
Presenter: T. Wanifuchi, Tokyo Electron Technology Development Institute, INC., Japan
Authors: T. Wanifuchi, Tokyo Electron Technology Development Institute, INC., Japan
G. Takaba, Tokyo Electron Technology Development Institute, INC., Japan
H. Ohtake, Tokyo Electron Technology Development Institute, INC., Japan
M. Sasaki, Tokyo Electron Technology Development Institute, INC., Japan
Correspondent: Click to Email
Silicon nitride has been widely used for dielectrics of CMOS logic devices, especially, for spacers or stopper layers. However, the mechanism of etching was not known well. In addition, several kinds of nitride film have been used in the devices and we have to know the effect of film properties on the etching characteristics.In this paper, the effect of film properties on nitride etching characteristics was investigated. 5 kinds of nitride wafers were prepared by changing the deposition temperature. The film density was lower at the lower deposition temperature, which contains more hydrogen in the film. As etching tools, RLSATM Etch, ICP and CCP were used. RLSATM Etch has high Ne of more than 1×1011cm-3 and low Te of less than 1 eV around the stage because RLSATM Etch tool uses the surface wave plasma and diffusion chamber. CH3F/ CF4/ O2 gas chemistry was used in all etchers. CCP showed ion-dominated etching because the etching rate was almost constant at various nitride films. On the other hand, RLSATM Etch and ICP showed the dependence of etching rate on film property. The etching rate decreases by increasing the film density. However the RLSATM Etch showed stronger dependency as compared with ICP. It is considered that radical- surface reaction dominated etching was realized at RLSATM Etch because ICP generates fluorocarbon polymers more than RLSATM Etch. Moreover, the dependency on film property was strongly related to the etching recipes. Film dependency was enhanced at the radical (chemical) etching condition as compared with ion dominated etching condition. In addition, we also observed the surface of nitride after oxygen plasma exposure because we used this plasma for surface cleaning. The results showed the dense and shallow oxidation layer was generated at the dense nitride film.Based on these result, we found that the etch characteristics was drastically changed by the film property and we have to use the appropriate plasma for precise nitride etching, corresponding to the film property.