| 摘要 |
1,201,246. Semi-conductor device. TEXAS INSTRUMENTS Inc. 19 Sept., 1967 [30 Dec., 1966], No. 42538/67. Heading H1K. In order to achieve a high degree of isolation between individual components in an integrated circuit formed in a single body of semi-conductor material, the individual components are separated by pairs of junctions between semiconductor material of high resistivity and opposite conductivity types. The components are situated within isolated regions of highresistivity N-type material distributed within a substrate of high-resistivity P-type material. The resulting junctions between the highresistivity materials exhibit high breakdown voltage and low capacitance and so provide effective isolation between the components. A high-resistivity (10-15 ohm. cm.) P-type silicon substrate 12 has epitaxially deposited thereon an N-type silicon layer 14 of similar resistivity. The surface of the layer 14 is covered with a resist 16 having apertures therein through which pockets 22, 24 are etched from the layer 14 by means of a suitable etchant. A thin layer of low-resistivity (0À018-0À02 ohm. cm.) N-type material 26, 28 is deposited epitaxially within each pocket and the remaining volume within each pocket is then filled epitaxially with less heavily doped N-type material 30, 32 (resistivity 0À18-0À22 ohm. cm.). The individual components of the integrated circuit are then formed by conventional diffusion processes within the regions 30, 32; a transistor is formed within the region 30 and the low resistance layer 26 serves as a connecting lead for its collector. A resistor is formed in region 32. In addition apertures (42) are formed in the mask (40) used during this diffusion process so as to separate each of the regions 30, 32 and acceptor impurity is diffused therethrough into the N-type layer 14 to create high-resistivity P-regions extending through the layer 14 to the substrate 12. Thus isolating junctions are formed between each of the regions 30, 32. In a modification, Figs. 7-9 (not shown), pockets are etched directly into the highresistivity P-type substrate and the first layer epitaxially deposited within each pocket is of high resistivity N-type material. Thereafter a further thin layer of low resistivity (N+) material is deposited and the pockets then filled with N-type material in which the components are formed. Shallow P+ annular regions may be made surrounding each component to prevent possible coupling between the components by surface N-type channels produced beneath the masking layer. The etching and epitaxial deposition processes may be carried out in the same apparatus, Fig. 10 (not shown). Etching is effected by means of gaseous HCl in a H 2 carrier and deposition by decomposition of SiH 4 , PH 3 and B 2 H 6 may be added for N- and P-type doping respectively. |
