| 摘要 |
1,197,759. Semi-conductor devices. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 13 Sept., 1967 [15 Sept.. 1966], No. 41733/67. Heading H1K. [Also in Division Cl] To remove selected parts of a silicon nitride layer on the surface of a semiconductor device, other parts of the layer are masked and the device is heated in an oxidizing atmosphere in the presence of lead oxide. This converts the exposed nitride into a mixed lead-silicon oxide which is removed by solution in hydrofluoric acid-in which the oxide is readily soluble and the nitride much less soluble. The mask may itself be an oxide, such as a mixture of silicon and aluminium oxides deposited by heating the device in the presence of specified organic compounds of silicon and aluminium in an oxidizing atmosphere. The apertures in this mask are produced by a photoetching technique in which the etchant is predominantly phosphoric acid. The heating in the presence of lead oxide is for 20 minutes at 700‹ C. with the lead oxide placed a few tenths of a millimeter from the masked nitride. The subsequent HF etch removes both the converted nitride and the masking oxide. In an alternative method, the nitride is masked by a metal, e.g. nickel, deposit provided with apertures by a photo-etching technique. In this case, however, the heating in the presence of lead oxide is for 5 minutes only; this produces total conversion of nitride to oxide at the edges of the apertures in the nickel but only partial conversion of the remainder of the exposed nitride. After the final HF etch therefore, only narrow slits in the nitrideabout 1 micron wide-are completely removed. These narrow slits may expose areas which are subsequently doped. |
