ELSEVIER Thin SolidFilms 304 (1997) 222-224 Chemical vapor deposition of A1203 films using highly volatile single sources Wonyong Koh, Su-Jin Ku, Yunsoo Kim Thin Film Materials Laborator); Korea Research Institute of Chemical Technology, Yusong P.O. Box 107, Taejon 305-600, South Korea Received2 January 1997; accepted26 February 1997 Abstract Amorphous AI203 films were grown on Si(100) and Si(11 l) substrates by low-pressure chemical vapor deposition in the temperature range of 250-600°C using dimethylaluminum isopropoxide, dimethylaluminum tert-butoxide, and diethylaluminum isopropoxide as single sources. All these sources vaporize readily at room temperature under reduced pressure. The films were characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. Auger depth profiling analysis of the samples indicates no appreciable carbon incorporation in the films. © 1997 Elsevier Science S.A. Keywords: Aluminumoxide; Chemical vapor deposition; Depth profiling; Organometallicvapor deposition Films and coatings of aluminum oxide (A120 3) have numerous electrical, optical and wear-resistant applica- tions. A120 3 films are commonly produced by chemical vapor deposition (CVD) using various kinds of aluminum sources such as aluminum chloride, aluminum isopropox- ide (A1(O-iC3I-I7)3), aluminum tert-butoxide (AI(O- tC4H9)3), aluminum acetylacetonate, aluminum hexafluo- roacetylacetonate, trimethylaluminum (AI(CH3)3), and aluminum 2-ethylhexanoate, and these are well reviewed recently [1]. Aluminum borohydride (AI(BH4)3) [21 and aluminum 2,2,6,6-tetramethyt-3,5-heptanedionate [3] are also proposed as aluminum CVD sources. Among these sources, only AI(CH3) 3 and AI(BH4) 3 are highly volatile liquids whereas all the other sources are solids and must be heated to temperatures higher than 100°C for vapor trans- port. AI(CH3) 3 is commercially available and frequently adapted for CVD of AI~O 3 [4-11]. However, it is py- rophoric and must be handled carefully. Using a single CVD source provides a novel alternative to conventional CVD that employs separate sources for each element of compound materials [12,13]. Gas-phase mixing is not necessary and undesirable gas-phase reac- tions that can generate particles or impurity sources are * Corresponding author. E-mail: yunsukim@pado.krict.re.kr. 0040-6090/97/$17.00 © 1997 ElsevierScience S.A. All rights reserved. PI1 S0040-6090(97)00132-6 much less likely to occur. Deposition usually proceeds at lower temperatures compared to conventional CVD. In this paper, we report on the CVD of Al20 3 films using dimethylaluminum isopropoxide, (CH3)2AI(O- iC3H7) , dimethylaluminum tert-butoxide, (CH3)2AI(O- tC 4H 9 ), and diethylaluminum isopropoxide, (C2I-Is)2AI(O-iC3Hv), as single sources. These com- pounds can be synthesized at room temperature simply by mixing AI(CH3) 3 or AI(CzHs) 3 with AI(O-iC3HT) 3 or AI(O-tC4Hg) 3 in a 2:1 ratio under inert atmosphere. (CH3)2AI(O-iC3H 7) is a liquid whereas (CH3)2AI(O- tC4H 9) and (C2Hs)zAI(O-iC3H 7) are gel-like solids. Si(100) and Si(lt 1) substrates were degreased and cleaned just prior to CVD. A simple CVD apparatus was used in which borosilicate glass tubing, quartz tubing, and stain- less steel bodies are connected through O-ring joints. It was evacuated by a rotary vane pump only. No carrier gas was used and the sources vaporized at room temperature. The substrates were placed on a graphite heating block. Substrate temperature was monitored by a thermocouple inserted in the graphite block. The deposition temperature was maintained in the range of 250-600°C. The pressure, measured by a Convectron gauge, was initially about 1 Pa and increased to 4-10 Pa after introducing a source into the apparatus. Interference colors of transparent oxide films on the substrates were observed within several min- utes after starting the CVD, which continued for several hours.