AVS 51st International Symposium
    Dielectrics Monday Sessions
       Session DI-MoP

Paper DI-MoP1
Surface Preparation for Atomic Layer Deposition of High-K Oxides on Silicon Studied by XPS and SPM

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: J.M. Sturm, University of Twente, The Netherlands
Authors: J.M. Sturm, University of Twente, The Netherlands
A.I. Zinine, University of Twente, The Netherlands
H. Wormeester, University of Twente, The Netherlands
R.G. Bankras, University of Twente, The Netherlands
J. Holleman, University of Twente, The Netherlands
J. Schmitz, University of Twente, The Netherlands
B. Poelsema, University of Twente, The Netherlands
Correspondent: Click to Email
Atomic Layer Deposition (ALD) is regarded as a suitable deposition technique for high-K metal oxides. In order to obtain a good interface quality with the silicon substrate, preparation of the starting surface is of major importance. The initial stage of Al@sub 2@O@sub 3@ deposition from trimethylaluminium and water and growth of thin films (~ 5 nm) were studied by XPS and SPM techniques. XPS was used to determine the growth rate and chemical state of the interface and deposited film as a function of wet-chemical pre-treatment of the starting surface and the pulse time of precursor and purge pulses. Ambient AFM showed that the deposited films are microscopically rough, with a correlation length of typically 20 nm and without correlation on larger length scales. UHV STM was used to investigate the stability of a hydrogen terminated Si surface in vacuum at typical growth temperatures of 250-300 °C used in ALD growth. Starting surfaces with a high RMS roughness of about 0.6 nm resulting from a concentrated HF dip did not change significantly by annealing at pressures below 5x10@super -10@ mbar. However, annealing in a higher background pressure of 3x10@super -8@ mbar (mainly H@sub 2@O) as typically present in a deposition set-up was found to result in a decrease of the surface roughness. These results indicate the importance of in-situ preparation of the starting surface and characterization of its chemical stability.