AVS 51st International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session DI+PS-TuM

Paper DI+PS-TuM5
Development of Post Etching Process for Hf Based High-K Gate Dielectric

Tuesday, November 16, 2004, 9:40 am, Room 304C

Session: High-k Dielectrics: Growth and Processing
Presenter: W.S. Hwang, National University of Singapore, Singapore
Authors: W.S. Hwang, National University of Singapore, Singapore
J.H. Chen, National University of Singapore, Singapore
W.J. Yoo, National University of Singapore, Singapore
D.S.H. Chan, National University of Singapore, Singapore
D.-L. Kwong, University of Texas at Austin
Correspondent: Click to Email
For successful integration of high-K dielectrics into CMOS process, a technique to selectively remove high-K films and interfacial layers with minimum consumption of both Si substrate and shallow trench isolation SiO@sub 2@ needs to be developed. In this work, we studied the wet etching properties of Hf based high-K dielectrics using 1% HF (DHF) for HfO@sub 2@, HfSiO, and HfAlO deposited by atomic layer deposition or sputtering. Effects of anneal, plasma oxidation and nitridation are discussed. Results show that before anneal, all these films can be removed completely by DHF with etch rates higher than 12nm/min. After 700@super o@C anneal, etch rate of HfAlO does not change, whereas etch rate of HfSiO decreases ~ 50%, leaving ~ 1nm thick densified HfSiO interfacial layer unremoved. Furthermore, HfO@sub 2@ cannot be etched by DHF after anneal: after etching for 24 hours, no thickness change was observed. By applying the room temperature plasma oxidation treatment, HfSiO interfacial layer can be removed in 10s in DHF, but 3-6nm thick SiO@sub 2@ grows underneath HfSiO interfacial layer, resulting in significant recess into Si substrate. However, 2 nm thick HfO@sub 2@ can be removed in 10s in DHF without noticeable recess into Si substrate, by applying the room temperature plasma nitridation treatment. Surface analysis using X-ray photoelectron spectroscopy shows that Hf-N bonds are formed on the surface of HfO@sub 2@ after plasma nitridation. High etch rate of HfN of 1000Å/min in DHF can explain the increase of the etch rate by the incorporation of N. HfSiO interfacial layer was also removed in 10s after plasma nitridation. By the plasma nitridation aided DHF cleaning process, very little recess of both Si substrate and STI SiO@sub 2@ was achieved, and furthermore low contact NiSi sheet resistance of 4-5@ohm@/sq was achieved.