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USE OF COMPOSITE SILICON-RICH SiO/2/ AND SiO/2/ LAYERS OR OFF-STOICHIO- METRIC CVD SiO/2/ LAYERS FOR IMPROVEMENT OF POLY l TO POLY 2 DIELECTRIC

IP.com Disclosure Number: IPCOM000045953D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

DiMaria, DJ: AUTHOR [+2]

Abstract

Use of Si-rich SiO/2/ (13% excess atomic Si) buffer layers or off-- stoichiometric CVD SiO/2/ (1-13% atomic Si) provides improvement in breakdown properties of dielectric material. A problem in the double polysilicon gate technology is the breakdown in the SiO/2/ layer between the two polysilicon layers. The problem is enhanced as thinner oxide layers are used when devices are scaled to smaller dimensions.

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USE OF COMPOSITE SILICON-RICH SiO/2/ AND SiO/2/ LAYERS OR OFF- STOICHIO- METRIC CVD SiO/2/ LAYERS FOR IMPROVEMENT OF POLY l TO POLY 2 DIELECTRIC

Use of Si-rich SiO/2/ (13% excess atomic Si) buffer layers or off-- stoichiometric CVD SiO/2/ (1-13% atomic Si) provides improvement in breakdown properties of dielectric material. A problem in the double polysilicon gate technology is the breakdown in the SiO/2/ layer between the two polysilicon layers. The problem is enhanced as thinner oxide layers are used when devices are scaled to smaller dimensions.

If the SiO/2/ is grown thermally from poly l layers, then a Si-rich SiO/2/ layer can be deposited on top and patterned with the SiO/2/. With negative bias on poly 2, breakdown characteristics improve because of the screening effect of the Si-rich oxide on injected charge from any inhomogeneous high field spots. Recent experimental evidence shows that there is also improvement with positive bias on poly 2. There is no delay due to charge storage in the Si-rich layer which has been demonstrated experimentally. Electron injection into the oxide is non- existent under normal field conditions. Even if there are electrons injected and trapped in the oxide, such charge trapping would not affect the operation since the insulator is sandwiched between two conducting polysilicon layers.

If a CVD oxide is used between poly l and poly 2, then composite layers similar to the DEIS (dual electron injector structure) or off-- stoichio...