AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeM

Paper PS-WeM11
Dry Etching Characteristics Related to TiN Material Properties

Wednesday, October 31, 2012, 11:20 am, Room 25

Session: Advanced BEOL/Interconnect Etching
Presenter: A.P. Labonte, GLOBALFOUNDRIES
Authors: A.P. Labonte, GLOBALFOUNDRIES
F. Wu, GLOBALFOUNDRIES
V. Arunachalam, GLOBALFOUNDRIES
S. Patil, GLOBALFOUNDRIES
C. Niu, ST Microelectronics, France
T.Q. Chen, GLOBALFOUNDRIES
E. Wornyo, IBM Microelectronics
B.G. Morris, IBM Microelectronics
Y. Yin, IBM Microelectronics
Y. Mignot, ST Microelectronics, France
Correspondent: Click to Email
TiN is ubiquitous as a hard mask layer in semiconductor patterning applications. Deposition parameters such as DC power, N2 flow, Ar flow, temperature, pressure, and target to wafer spacing influence the film properties: density, film stress, resistivity, roughness, grain size and uniformity. These changes in the TiN film properties can affect etch characteristics. For TiN hard mask etches, shifts in etch rate, sidewall angle, undercut/gouge, CD control and LER have been observed. For dielectric etches using the TiN layer as a hard mask, changes in selectivity, erosion rate, etch byproducts, CD control, profile angle and pattern loading have been observed. This presentation will show data on the etch behavior of TiN etch as well as the etch when TiN is used as a mask.In a TiN hard mask open application, a uniformly dense film is required. As part of an evaluation of different TiN films, both uniform and non-uniform density TiN films were generated. Changes in deposition conditions were used to adjust film density uniformity while maintaining average film density. The etch process used to pattern these films was a two step process consisting of an end-pointed main etch and a timed over-etch. The impact to the dry etch process of the film change, was to alter the behavior of the two etch steps in radically different ways. For the main etch, the sidewall angle and etch rate were impacted. For the over-etch chemistry, lateral etch-rate, CD control and profile were most impacted. In addition, the impact of pattern density on via CD definition has been studied for a via double patterning scheme employing TiN as a hard mask for part of the etch. The etch was found to behave differently as a function of pattern density in a fluorine-based plasma, which was theorized to be a consequence of redeposition of TiFx etch byproducts. This theory was supported by data showing a series of TiN films with different material properties resulted in different pattern density responses. The selectivity between the TiN and the underlying film being etched was changed by these TiN film changes, resulting in the different behavior.This work was performed by the Research Alliance Teams at various IBM Research and Development Facilities.