AVS 62nd International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS1-TuA

Paper PS1-TuA8
Enhancing Selectivity for Self-Aligned Contact Etching by Employing Dual Fluorocarbon Etch Gas Processes

Tuesday, October 20, 2015, 4:40 pm, Room 210A

Session: Novel Materials and Etch Chemistry
Presenter: Jeffrey Shearer, IBM Research Division
Authors: J.C. Shearer, IBM Research Division
S.U. Engelmann, IBM Research Division, T.J. Watson Research Center
R.L. Bruce, IBM Research Division, T.J. Watson Research Center
E.M. Sikorski, IBM Research Division, T.J. Watson Research Center
T. Suzuki, ZEON Chemicals L.P.
M. Nakamura, ZEON Chemicals L.P.
A. Ito, ZEON Chemicals L.P.
G. Matsuura, Zeon Corporation, Japan
H. Matsumoto, Zeon Corporation, Japan
B. Messer, TEL Technology Center, America, LLC
K. Horvath, TEL Technology Center, America, LLC
A. Metz, TEL Technology Center, America, LLC
J.C. Arnold, IBM Research Division
E.A. Joseph, IBM Research Division, T.J. Watson Research Center
Correspondent: Click to Email
As the industry moves from 10nm node to 7nm node and beyond, self-aligned contact (SAC) etch is becoming one of the most critical and challenging process elements in logic chip manufacturing. Extremely high selectivites are required to adequately stop on spacer and hard mask materials in addition to the ever continuing trend of scaling critical dimensions (CDs). For the self-aligned contact etch this translates into a classic trade-off relationship between increased selectivity by fluorocarbon deposition and random etch stop due to ion/neutral flux imbalances at reduced dimensions.

Our team has recently introduced a new etch gas (C5HF7) which is able to etch by selective deposition of a fluorocarbon (FC) layer, where the elemental fluorine content was reduced due to feedgas optimization. Even though the C5HF7 gas yielded better protection of the spacer material than the comparable C4F6 process, adequate etch depth was not achieved in aggressive 10nm test structures (etch stop was observed).

We enhanced this process further by decomposing the etchant supply of the fluorocarbon gas by the use of dual FC etch chemistries. While one FC gas is targeted to deliver radicals for FC deposition and selectivity enhancement, another FC gas is added to supply FC radicals that promote the oxide etch. We are reporting our results from this approach by two trusts: On a more fundamental level, we evaluated the dual FC etch gas approach in detail, with gas optimization and a survey of multiple spacer materials. We found that for SiN spacer materials our C4F6 process showed selectivities of approx. 9, the C5HF7 process showed selectivities of up to 23 and the dual FC process showed selectivities of up to 38.

Furthermore, C5HF7 has been deployed for SAC applications in 10nm and 7nm product demonstrations. This paper will show that this new gas is able to match the performance of the C4F6 while at the same time significantly improving raw process time.

This work was performed by the Research Alliance Teams at various IBM Research and Development Facilities.

1M. Schaepkens, T.E.F.M. Standaert et al., J. Vac. Sci. Technol. A 17, 26 (1999)

2M. Schaepkens, G.S. Oehrlein and J.M. Cook, J. Vac. Sci. Technol. B18, 848 (2000)

3R.L. Bruce, T. Suzuki et al., AVS 61st Int. Symp. & Exhibit. (2014)