19 September 1995 Deposition of thick zinc oxide films with a high resistivity
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Proceedings Volume 2639, Micromachining and Microfabrication Process Technology; (1995) https://doi.org/10.1117/12.221290
Event: Micromachining and Microfabrication, 1995, Austin, TX, United States
ZnO is a well known piezoelectric material. Unfortunately, it is not easy to deposit thin films onto silicon with a high resistivity by using common deposition technologies. The use of such films is therefore strictly limited to high frequency applications. The goal of our work was to find out a new deposition technology that allows the deposition of ZnO films with a high resistivity. Furthermore we were looking for the deposition of film thicknesses in a range up to 20 micrometers for SAW-sensor and microactuator applications. The deposition of the ZnO films was carried out in a programmable RF-magnetron-sputtering-system. We sputtered from a pure zinc target with a variable gas composition that consists of argon and oxygen. We worked in an alternating mode to achieve a high resistivity of the films. After a deposition cycle at a sample temperature of about 30 degrees C with a ramp shaped power the silicon- samples were cooled during the following cycle in the gas atmosphere. The deposition rate we measured was dependent from the gas composition and the applied power in a range between 1,5 micrometers /h and 2,2 micrometers /h. We deposited films of a thickness of 20 micrometers . Between two sputtered aluminium electrodes the films had a resistivity in a range between 2*1010(Omega) cm and 2*1011(Omega) cm. The stress of the films could be influenced by the composition of the gases. The measured minimum stresses of the films were in a range of about 180 MPa. The films were also characterized by means of XRD- measurments. We found a weak < 101 > orientation of the layers perpendicular to the surface.
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Norbert Schwesinger, Norbert Schwesinger, Heike Bartsch, Heike Bartsch, Frank Moeller, Frank Moeller, "Deposition of thick zinc oxide films with a high resistivity", Proc. SPIE 2639, Micromachining and Microfabrication Process Technology, (19 September 1995); doi: 10.1117/12.221290; https://doi.org/10.1117/12.221290

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