Patent GB-1191002-A (GB)
Title: Semiconductor Devices and Fabrication thereof
Inventor: HABERECHT ROLF REINHOLD
IPC: H01L21/00
Filed: 1967-05-19
Abstract: 1,191,002. Semi-conductor devices; capacitors; inductors. TEXAS INSTRUMENTS Inc. 19 May, 1967 [23 May, 1966], No. 23432/67. Headings H1K, H1M and HIT. in a manufacturing process for semi-conductor devices the crystallographic structure of a semi-conductor substrate 2, Fig. 1, is altered at selected areas by directing a localized beam of energy 16 on to the selected areas. The substrate 2 is exposed to a vaporous reactant material which results in epitaxial deposition of material only on to those portions of the substrate 2 unaffected by the energy beam 16. The beam 16 may be from a laser, but as shown, it comprises electrons. The substrate 2 may, for example, comprise a II-VI or III-V compound and in one embodiment it consists of GaAs which is selectively irradiated to evaporate off As from the irradiated areas, leaving Ga-rich regions which are incompatible with subsequent epitaxial deposition of GaAs, so that deposition occurs only on the non-irradiated areas. The epitaxial deposition may take place into cavities in the substrate surface. The invention may be used in conjunction with the method of U.K. Specification 1,165,016, in which a beam of energy is used to produce local protuberances on a monocrystalline semiconductor substrate. An integrated circuit includes transistors T 1 , T 2 , Fig. 7, and resistors R 1 , R 2  formed in N-type epitaxial bodies 30-33, Figs. 2 and 4, deposited in the above manner on a P-type Si substrate 2. P-type regions 41a, 41b, 41c and N-type regions such as 42 may be diffused into the bodies 30-33 by passing the vapours of suitable impurity sources such as BCl 3 , BBr 3 , B 2 H 6 , B 2 O 3 , PCl 3  or P 2 O 5  over the bodies 30-33 while areas thereof are selectively heated to a diffusing temperature using the electron beam. The supply of the impurity source may be controlled automatically by monitoring secondary emission from the bodies 30-33, since this will vary according to the dopant concentration. Ion bombardment may alternatively be used to form the regions 41a, 41b, 41c, 42, a beam of, e.g. B ions being traced across the semi-conductor surface simultaneously and coincidentally with the electron beam. An insulating layer 40 of silicon oxide is formed on the substrate 2 between the epitaxial bodies by selectively heating the exposed surface of the substrate 2 by means of the electron beam and passing a current of steam or oxygen across it. A subsequent insulating layer 60, e.g. of CeO 2  or TiO 2  may be formed conventionally. The integrated circuit also includes a capacitor C, Fig. 7, formed by selectively heating an area BBBB, Fig. 2, of the Si substrate 2 by means of the electron beam and selectively depositing thereon a body 34 of SiO 2 , TiO 2  or CeO 2 .SiO 2  may be formed either by passing steam or oxygen over the substrate 2 to thermally oxidize only the selectively heated area or by flowing a mixture of oxygen and tetraethoxysilane over the substrate, in which case the reaction leading to deposition of SiO 2  occurs only over the selectively heated area. TiO 2  may similarly be deposited using a flow of water vapour and titanium tetrachloride. The lower electrode of the capacitor C comprises either the substrate 2 or a predeposited metal layer. The upper electrode 81 is formed by converting a layer of the body 34 to a conductive condition by reduction by means of the electron beam in the manner disclosed in Specification 1,107,305. An inductor L is formed by selectively depositing a body 35 of a ferrite such as yttrium iron garnet on to a selectively heated area of the substrate 2 and selectively converting a spiral area 80 on the upper surface thereof to a conductive condition using the electron beam. Interconnections 70- 73 between the various components are formed by selectively rendering strips of the insulating layer 60 conductive by means of the electron beam. Where the interconnections are required to extend below the surface of the layer 60 the necessary energy is localized at the desired level by suitable focusing of the electron beam. In any of the above-described processes in which a vaporous reaction reacts with the semiconductor surface under the direct action of the energy beam the substrate may be tilted slightly so that the energy beam meets the flow of reactants only at the area where reaction is desired.