Browse Prior Art Database

MIXED Ce/Si OXIDE FOR INSULATOR IN VLSI DEVICES

IP.com Disclosure Number: IPCOM000039813D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Hillebrecht, FU: AUTHOR [+3]

Abstract

The drawing shows schematically the cross section of a dynamic random- access memory (D-RAM), with the gate insulator and storage capacitor insulator marked by cross-hatching. For megabit memories in very large-scale integration (VLSI) all device dimensions have to be scaled down. The capacity of the storage capacitor insulator has to go up, so that the charge can be sensed. For both reasons the insulators in the figure have to be thinner than in previous devices, in the order of & 100 Ao . So far as the storage capacitor insulator is concerned, the stringent requirement on thickness can be moderated by an increase in the dielectric constant of the insulator. The material choice for the transfer gate insulator is SiO2, while for the storage capacitor the insulator choice is open.

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MIXED Ce/Si OXIDE FOR INSULATOR IN VLSI DEVICES

The drawing shows schematically the cross section of a dynamic random- access memory (D-RAM), with the gate insulator and storage capacitor insulator marked by cross-hatching. For megabit memories in very large-scale integration (VLSI) all device dimensions have to be scaled down. The capacity of the storage capacitor insulator has to go up, so that the charge can be sensed. For both reasons the insulators in the figure have to be thinner than in previous devices, in the order of & 100 Ao . So far as the storage capacitor insulator is concerned, the stringent requirement on thickness can be moderated by an increase in the dielectric constant of the insulator. The material choice for the transfer gate insulator is SiO2, while for the storage capacitor the insulator choice is open. Below 100 Aothickness SiO2 is not good for the storage capacitor, since it has problems with yield, does not block Na+ and B, has many pinholes, and does not have a high dielectric constant at high frequencies. A mixed cerium silicon oxide, cerium silicate can be used instead of SiO2 for the transfer gate and storage capacitor insulator. The insulator is formed by depositing the required thickness of Ce metal on a silicon substrate. The amount of insulator can be controlled by the amount of deposited cerium. Either at room temperature or at a temperature between room temperature and 700oC, CeSi2 forms epitaxially on silicon where CeSi2 (001...