Browse Prior Art Database

Four Layer Switch With Schottky Barrier Diode

IP.com Disclosure Number: IPCOM000074753D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 107K

Publishing Venue

IBM

Related People

Anantha, NG: AUTHOR [+3]

Abstract

This method results in a monolithic four-layer switch with a built-in Schottky diode clamp across one of the junctions. This device has high switching speed, because the low forward-drop Schottky diode conducts away the charge stored in one base region during the switching off period of the device.

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Four Layer Switch With Schottky Barrier Diode

This method results in a monolithic four-layer switch with a built-in Schottky diode clamp across one of the junctions. This device has high switching speed, because the low forward-drop Schottky diode conducts away the charge stored in one base region during the switching off period of the device.

In the method of fabrication shown in Fig. A, 10 is P/-/ substrate with n/+/ type buried layer 11. An 'n' type epi layer 12 is grown on top of the substrate 10. Three subsequent diffusions result in lightly doped P type region 13, a lightly doped n type region 14 and a heavily doped p+ type region 15. Two isolation pockets 16 serve to isolate one device from another. A reach through diffusion 17 is provided for the collector. A window 18 is opened in the oxide 19 exposing the junction between the regions 13 and 14 during the contact etching step. Any contact metal such as aluminum, PtSi, molybdenum, etc. is deposited in the contact windows. The metal contact 30 gives a good ohmic contact to P type region 13 while it forms a Schottky barrier with lightly doped n region 14. The resulting PNPN structure, shown in Fig. B, has a Schottky diode 30 across one of its junctions.

Similarly a NPNP switch is fabricated with a Schottky diode as shown in Fig.
C. 20 is N type substrate, 21 is P+ buried layer and 22 is P type epi layer. 23 is lightly doped N region, 24 is lightly doped P region, and 25 is heavily doped N+ region. 26 are is...