| 摘要 |
In the process claimed substrates (17), placed in a boat (16), are heated in a furnace (12) at reduced pressure. The source, tetra-ethyl-ortho-silicate (TEOS), is provided and its usage metered as a liquid (2). Just before entering the furnace-tube (10) it is evaporated (9). The pressure in the tube is measured (14) and maintained by a pump (19). An additional flow of O2 may also be provided via an other inlet (15) to improve the stoechiometry of the SiOx-layer. The deposition rate is controlled pref. by the partial pressure of the source-material at a constant temp. between 700 and 750 deg. C., pref. 730 deg. C, over pressure-range of 70-700 microbar by adjusting the lqiuid flowrate to 0.1-1.0 cm3/min. Prefd. conditions are a liquid flow of 0.2 cm3/min. of TEOS and 20 cm3/min. of O2. The liquid TEOS-source may also contain liquid cpds. of certain pref. elements., e.g. triethylphosphite (TEP), triethylarsenide or trimethylborate (TMB). From this mixture a layer is then deposited at 130-700 microbar pressure, using a liquid flow rate of 0.2-1.7 cm3/min. and pref. including extra O2, pref. in excess of stoechiometric quantity. Pref. conditions for a glass layer with 2% P and 4% B are a flow rate of 0.7 cm3/min. of a liquid source containing 14.7 wt.% TEP, 12.6 wt.% TMB and the rest TEOS, with an additional flow of 100 cm3/min. of O2.
|
