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Method of Contacting Semiconductor Zones

IP.com Disclosure Number: IPCOM000081165D
Original Publication Date: 1974-Apr-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gansauge, P: AUTHOR [+2]

Abstract

During the application of metallic contacts on lowly doped semiconductor zones, a highly doped and thus a low-resistance contacting zone of the same conductivity type is initially diffused into the semiconductor in the area of the contact surface. Then the contact metal is applied. In this manner a high-surface concentration and thus a low-contact resistance is obtained in the area of the contact.

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Method of Contacting Semiconductor Zones

During the application of metallic contacts on lowly doped semiconductor zones, a highly doped and thus a low-resistance contacting zone of the same conductivity type is initially diffused into the semiconductor in the area of the contact surface. Then the contact metal is applied. In this manner a high- surface concentration and thus a low-contact resistance is obtained in the area of the contact.

If the semiconductor zones to be contacted are extremely shallow and only lightly doped, it is not possible to increase the surface concentration in the contact area by diffusion, because this would affect the doping profile of the shallow structure.

Reliable, low-resistance contacts to extremely shallow and lowly doped semiconductor zones are obtained by ion implanting donor or acceptor atoms into the contact area, in such a manner that the penetration depth of the implanted ions is low in comparison to the depth of the zone to be contacted, and the doping on the surface is increased to a level necessary for applying metal contacts.

Thus, the ion implantation process has to meet the following requirements;
1) Low energy of the implanted ions to ensure a low depth of

penetration (approx. 500 Angstroms).
2) High dose to increase the surface concentration to

10/20/-10/21/ atoms/cm/3/.
3) Annealing process (approx. 700 degrees C) that

electrically activates the implanted

ions, without changing the doping profile of the zone

to be c...