| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeA |
| Session: | High-K Dielectrics for 2D Semiconductor |
| Presenter: | Tyler Kent, University of California at San Diego |
| Authors: | T. Kent, University of California at San Diego K. Tang, Stanford University S. Lee, University of California at Santa Barbara C.Y. Huang, University of California at Santa Barbara V. Chobpattana, University of California at Santa Barbara K. Sardashti, University of California at San Diego M. Edmonds, University of California at San Diego R. Droopad, Texas State University P.C. McIntyre, Stanford University A.C. Kummel, University of California at San Diego |
| Correspondent: | Click to Email |
One of the major obstacles impeding the advancement of III-V MOSFETs is the large density of interfacial trap states (Dit) at the high-k/III-V interface. Poor nucleation of the gate oxide can lead to dangling bonds, strained bonds, and metallic bonds which contribute to Dit; additionally, low nucleation density requires a thicker oxide to avoid pinholes which increase gate leakage. The nucleation of HfO2 was studied using tetrakis(ethylmethylamino)hafnium (TEMAH) and H2O on the InGaAs (001) and InGaAs (110) surfaces at low temperature, 120 ˚C, using atomic layer deposition (ALD). Low temperature ALD reduces subcutaneous oxidation of the channel when this is an activated process. The pulse and purge times of the oxidant and reductant were varied and their impact on the nucleation of HfO2 were studied by fabricating MOSCAPs and extracting the Dit using the full interface surface state model. All samples had 10 cycles of an in-situ pre-ALD surface clean developed by Choptabanna and Carter which utilizes atomic H and TMA. The effectiveness of the ex-situ buffered oxide etch (BOE) was examined by fabricating samples with and without this clean. The BOE was more effective on the (001) samples since the non-BOE samples had a larger Dit and a higher Cmax indicating poor nucleation of the HfO2. The dispersion in accumulation remained constant indicating the BOE had an immediate effect on the interface, rather than deep traps in the oxide. The BOE and non-BOE (110) samples had a nearly identical Cmax, Dit, and dispersion in accumulation indicating the nucleation of HfO2 is not as dependent on the BOE as the (001) surface. This result obviates the need for the BOE allowing an all dry process on InGaAs(110) and is likely a result of the inherent stability of the (110) surface compared to the (001) surface.