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Browse Prior Art Database

Low Voltage Electrostatic Discharge Clamp

IP.com Disclosure Number: IPCOM000041222D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Geissler, S: AUTHOR

Abstract

A storage node implant is used to lower snapback voltage in dynamic random access memories (DRAMs) for the purpose of providing low voltage protection of storage insulators.

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This is the abbreviated version, containing approximately 93% of the total text.

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Low Voltage Electrostatic Discharge Clamp

A storage node implant is used to lower snapback voltage in dynamic random access memories (DRAMs) for the purpose of providing low voltage protection of storage insulators.

Semiconductor devices can be damaged by voltages that exceed the dielectric breakdown voltage of a storage cell's gate oxide. To avoid this hazard, a protective clamp device is utilized which is normally non-conductive; however, the device turns on when the drain voltage exceeds the snapback voltage of approximately 16 volts. Test structures and product designs with pads connected to storage node oxides and other devices are left unprotected using conventional protection techniques.

By reducing the snapback voltage, which is achieved by increasing the impact ionization current, a solution to the gate dielectric breakdown problem can be realized. A reduction in impact ionization is achieved by increasing the drain junction electric field. This can be done by decreasing the junction depth and/or increasing the channel tailor implant by using a high capacity (HC) boron implant in the channel region of an enhanced FET. A further reduction in snapback voltage to about 10 volts can be realized by using HC arsenic and boron implants to form a shallow drain junction and to increase the boron concentration in the channel region. The shallow junction clamp shown in the figure has the ability to protect storage node structures from electrostatic discharge events...