AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS-MoM

Paper PS-MoM3
Resist Transformation under High Density Plasma Exposure

Monday, November 4, 2002, 9:00 am, Room C-105

Session: Conductor Etch I
Presenter: E. Pargon, CNRS/LTM, France
Authors: E. Pargon, CNRS/LTM, France
J. Foucher, CNRS/LTM, France
J. Detter, CNRS/LTM, France
L. Vallier, CNRS/LTM, France
G. Cunge, CNRS/LTM, France
O. Joubert, CNRS/LTM, France
Th. Lill, Applied Materials
Correspondent: Click to Email
We are now entering in the development of sub 0.1 µm Integrated Circuits device fabrication where a very accurate control and understanding of plasma processes is essential to address the road map requirements. In particular, plasma processes involved in gate stack processes need special attention since several steps such as resist trimming, hard mask opening and silicon etching impact the final gate dimension. In any of these processes, the etching behaviour of photoresist exposed to the plasma plays a key role. In this study, we have performed chemical topography analyses using XPS to explore the chemical nature and thickness of the reactive layers formed on the resist patterns. XPS analyses show that the resist transformation during the resist trimming process is well correlated with the trim rate measured in HBr/O@sub2@ and HBr/Cl@sub2@/O@sub2@ /CF@sub4@ chemistry. In particular, a decrease in trim rate obtained when increasing the bias power is well correlated with a thicker perturbed layer formed on the resist sidewalls. A good correlation between reactive layer thickness on the sidewalls and decrease in trim rate is also observed with CF@sub4@ addition. CF@sub4@ based plasmas used for hard mask opening generate reactive layers as thick as 10 nm on the resist sidewalls (through the formation of a CFx-based layer). This layer is suspected to generate a loss of CD control during hard mask patterning. Deep transformations of the resist during silicon gate etching are also observed. XPS studies show that the resist mask strongly loads chlorine species as compared to an oxide hard mask and that thick passivation layers are formed on the resist sidewalls using HBr/Cl@sub2@/O@sub2@ and HBr/Cl@sub2@/O@sub2@/CF@sub4@ chemistries. Correlations between resist behaviour and process control (mainly CD control) can be established