Method for preparing a plasma nitrided gate dielectric layer

Abstract

The invention provides a method for preparing a plasma nitrided gate dielectric layer. The method is characterized in that the method includes the steps of providing a substrate, forming a silicon dioxide layer on the substrate and doping nitrogen into a silicon oxide layer under the temperature condition of minus 100 degrees to 0 degree. With the nitrogen doped under the low temperature of minus 100 degrees to 0 degree; diffusion effect of nitrogen ions is reduced; more nitrogen ions gather on the upper surface of the silicon dioxide layer; more bonding between Si-O bond and nitrogen ions is interrupted; nitrogen content on the upper surface of the plasma nitrided gate dielectric layer is increased. Thus, not only is leakage current density reduced but also a high gate capacitance is provided. Furthermore, reliability of the device is improved, and B+ is inhibited from diffusing from gate polysilicon to gate oxide.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for preparing a plasma nitride gate dielectric layer. Background technique [0002] Integrated circuits are made up of millions of basic building blocks such as transistors, capacitors and resistors. A transistor usually includes a source (Source), a drain (Drain) and a gate stack, and the composition of the gate stack is to form a dielectric layer (usually silicon dioxide) above the substrate (silicon), and then The dielectric layer is covered with a thin film (such as polysilicon) as an electrode. [0003] With the rapid development of Very Large Scale Integration (VLSI) and Ultra Large Scale Integration (ULSI), the size of MOS devices has been continuously reduced. In order to increase the response speed of the device, increase the driving current and the capacity of the storage capacitor, the thickness of the silicon dioxide gate dielectric layer in the d...

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Problems solved by technology

In this method, the nitrogen content is still not high enough to reduce the equivalent thickness of the oxide, effectively reduce the gate leakage and increase the driving current, which affects the reliability of the device.

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