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Method of Multiple Gate Oxide Device formation in Mg/MeOx Application

IP.com Disclosure Number: IPCOM000042882D
Publication Date: 2005-Feb-04
Document File: 4 page(s) / 420K

Publishing Venue

The IP.com Prior Art Database

Related People

Byoung W. Min: AUTHOR [+2]

Abstract

This disclosure relates generally to forming semiconductor devices, and more specifically, to forming multiple gate oxide devices in Metal Gate / Metal Oxide stacks. As device dimensions shrink, high dielectric constant (high-k or hi-k) materials associated with metal gate materials are being used as the gate stack for devices operating at the lowest voltages in the circuit, henceforth referred to as core devices. But at least four problems exist if a high-k on top of the thicker oxide is conventionally used for high voltage devices, a thicker gate oxide devices (henceforth known as DGO devices), or resistor. First, using a metal gate material changes the work function of the device. When the work function changes, the technology associated with the device must be altered. Instead, by not changing to a metal gate material, the earlier technology can continue to be used and time is saved having to develop any new technology. Second, silicon is thinned down during thicker oxidation, preventing a use of thin silicon substrate, which is preferable in the most recent technology. Third, surface roughness increases during additional thick oxide etch in fabrication, degrading transistor mobility. Fourth, metal gate is so conductive that it cannot be used for resistor.

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Name of Invention : Method of Multiple Gate Oxide Device formation in Mg/MeOx Application

Disclosure No. SC13782TP

Conception Date : 5/31/2004

Inventor : Byoung W. Min and Bill Taylor

Abstract :

                    This disclosure relates generally to forming semiconductor devices, and more specifically, to forming multiple gate oxide devices in Metal Gate / Metal Oxide stacks.

                    As device dimensions shrink, high dielectric constant (high-k or hi-k) materials associated with metal gate materials are being used as the gate stack for devices operating at the lowest voltages in the circuit, henceforth referred to as core devices.  But at least four problems exist if a high-k on top of the thicker oxide is conventionally used for high voltage devices, a thicker gate oxide devices (henceforth known as DGO devices), or resistor.  First, using a metal gate material changes the work function of the device.  When the work function changes, the technology associated with the device must be altered.  Instead, by not changing to a metal gate material, the earlier technology can continue to be used and time is saved having to develop any new technology.  Second, silicon is thinned down during thicker oxidation, preventing a use of thin silicon substrate, which is preferable in the most recent technology. Third, surface roughness increases during additional thick oxide etch in fabrication, degrading transistor mobility. Fourth, metal gate is so conductive that it cannot be used for resistor.

It is often desirable that both core devices and DGO devices are formed on the same semiconductor substrate.  When forming the metal gate/high-k stack for the core devices, it is desirable to prevent the metal gate from being formed as part of a gate stack for the DGO device and/or resistors.  Thus, there is a need for an integration process that enables the different dielectrics to be formed in different areas of the substrate.

The present invention is illustrated by way of example and is not limited by the accompanying figures,...