Method for forming recessed dielectric isolation with a minimize

Details Method for forming recessed dielectric isolation with a minimize Method for forming recessed dielectric isolation with a minimize

1975-06-30

1976-06-08

Rutledge, L. Dewayne

Metal treatment

Process of modifying or maintaining internal physical...

Chemical-heat removing or burning of metal

29578, 29580, 29590, 148174, 156612, 357 49, 357 50, 357 59, 427 86, H01L 2176, H01L 2120

Patent

active

039619990

ABSTRACT:
In the fabrication of integrated circuits, a method is provided for forming recessed silicon dioxide isolation in integrated circuits in which the "bird's beak" problems associated with conventional silicon dioxide-silicon nitride composite masking structures is minimized. A conventional composite mask comprising a bottom layer of silicon dioxide and an upper layer of silicon nitride having a plurality of openings defining the regions in the silicon substrate which are to be thermally oxidized is formed on a silicon substrate. Recesses are then etched in the silicon substrate in registration with the openings in the composite mask. Then, the silicon dioxide layer is, in effect, over-etched to extend the openings in the silicon dioxide to greater lateral dimensions than the openings in the silicon nitride layer whereby the silicon nitride at the periphery of the openings is undercut.
A layer of silicon is then deposited in the recesses covering the undercut portions of said silicon nitride layer. Then, the structure subjected to thermal oxidation whereby the silicon in and abutting the recesses is oxidized to form regions of recessed silicon dioxide substantially coplanar with the unrecessed portions of the silicon substrate. Because of the undercutting and the deposition of silicon in the recesses, the "bird's beak" effect is minimized.

REFERENCES:
patent: 3783047 (1974-01-01), Paffen et al.
patent: 3858231 (1974-12-01), Magdo et al.
patent: 3886000 (1975-05-01), Bratter et al.
patent: 3900350 (1975-08-01), Appels et al.
"Selective Oxidation of Silicon and Its Device Applications", Semiconductor Silicon, 1973, edited by Huff et al., Electrochem. Soc., Publ., pp. 860-879.
Appels et al., "Local Oxidation of Silicon; New Technological Aspects", Philips Res. Repts, June, 1971, pp. 157-165.
Kooi et al., "Locos Devices", Ibid., June 1971, pp. 166-180.
Antipov, I., "Isolation of N and P Regions . . . . Structure", I.B.M. Tech. Discl. Bull., vol. 17, No. 5, Oct. 1974, pp. 1545-1546.

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