Chemical Vapor Deposition of Ti-Si-N Films with Alternating Source Supply
- PDF / 882,615 Bytes
- 4 Pages / 417.6 x 639 pts Page_size
- 74 Downloads / 165 Views
to the one described previously [4]. The reactor was purged by Ar gas for 20 s between the supply of reactants. TDMAT was kept in a bubbler at 30 'C and delivered by Ar carrier gas. SiH, diluted in Ar was used. Total gas flow rate into the reactor was fixed at 270 sccm and reactor pressure was maintained at 1.0 torr. All Ti-Si-N films were grown on SiO, (100 nm)/Si wafers at the substrate temperature of 180 'C. The thickness of deposited film was measured by the surface profilometer. The composition of the film was analyzed with Auger electron spectroscopy (AES). Rutherford backscattering spectroscopy (RBS) using 2.43 MeV He> ion beam. and elastic recoil detectiontime of flight (ERD-TOF) method using 9.0 MeV CI' ion beam. The chemical nature of Si in the film was investigated with X-ray photoelectron spectroscopy (XPS). RESULTS Figure 1 shows the cross-section of a Ti-Si-N film deposited after 227 gas supply cycles. The superior step and side-wvall coverage of ALD even in holes with 0.3-pm diameter and 10:1 aspect ratio, is clearly demonstrated. The gas supply cycle of TDMAT and SiH4 did not deposit any film on the substrate at 180 'C. nor the cycle of SiH, and NH-. TiN films were deposited by ALD using TDMAT and NH. at 180 'C. TDMAT supply for 5 s and NH, supply for 5 s were sufficient to achieve the saturation of film growth per cycle. 0.44 nm'cvcle. Ti-Si-N films were deposited by sequential supply of TDMAT for 5 s. SiH 4 for 10 s. and NH3 for 10 s in the written order. The partial pressure of SiH, was varied from 0.002 torr to 0.1 torr by dilution in Ar. Figure 2 shows the dependence of the Si content of the Figure 1. SEM image of a film deposited on a hole-patternied SiO,/Si substrate at films and the Ti-Si-N film growth per cycle on the 180 'C after 227 cycles of gas supply of Sil, partial pressure. Despite the wide variation in TDMAT. Ar. SiH,. Ar. NH•. and Ar for 5. SiH, partial pressure the Si content of the films remains constant at 18 at.% and the film growth rate 20. 10.20. 10. and 20 s. respecti'el. decreases little from 0.24 nm/cycle. The silicon content dependence is strikingly different from the conventional CVD result where the Si content in the film increases logarithmically as the partial pressure of SiH, increases [51. In a different set of experiments. SiH, and NH. were simultaneously supplied in the sequence of TDMAT for 5 s and SiHftNH; for 10 s. Figure 3 shows the dependence of the Si content and the film grox\th per cycle on SiH4/NH; ratio. The Si content increases at lo\\ SiHf NIl ratio as SifH NH, ratio increases, and saturates to 23 at.% at about 1:1 ratio. It is concluded that SiH, does not react with either TDMAT or NH. and is involved only \%ith certain intermediates generated by the reaction between TDMAT and NH., (or between either one and the surface derivative of the other). Apparently SiH, and NH. compete for these intermediates. In conventional CVD more Si is incorporated in the film as there are more SiH, molecules than NH4, in the gas phase. In ALD where Sifti and NIl; are sim
Data Loading...
