Preparation method of germanium-base schottky transistor

Abstract

The invention discloses a preparation method of a germanium-base schottky transistor, which belongs to the technical field of a manufacturing process of ultra large scale integrated circuits (ULSI). The method comprises the following steps: manufacturing an MOS transistor structure on a germanium-base substrate; depositing a metal thin film; carrying out heat treatment for the first time for quick heat annealing so as to ensure that the metal thin film layer and the germanium layer below the metal thin film layer react to form metal germanide; removing the unreacted metal thin film layer; doping impurities in the germanide layer generated by the reaction; carrying out heat treatment for the second time for annealing so as to ensure that the doped impurities are activated to drive in; and finally forming contact holes and metal connection wires. The method carries out the impurity doping and the activated drive-in annealing after forming the germanide through the first annealing and can effectively regulate and control a barrier height of the contact of a metal semiconductor and also improve the surface appearance of the germanide.

Description

technical field [0001] The invention belongs to the technical field of ultra-large-scale integrated circuit (ULSI) manufacturing technology, and in particular relates to a method for preparing a Ge-based Schottky. Background technique [0002] As the device size shrinks, mobility degradation becomes a difficult problem. Compared with silicon materials, germanium materials have higher and more symmetrical low-field carrier mobility, narrow energy band width, and are compatible with silicon processes, so germanium-based devices are a promising development direction for high-speed MOSFET devices. [0003] The germanium-based Schottky transistor is a new structure with great potential for development. The main difference between it and the traditional transistor is that it replaces the traditional highly doped source and drain with a metal germanide source and drain. The contact between the source and drain and the channel is made of The PN junction becomes the Schottky junctio...

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Problems solved by technology

(6) Germanium-based Schottky transistor structure Realizing germanium source and drain on germanium materials will greatly overcome the low solid solubility of impurities in Ge in bulk Ge devices, large source-drain resistance, and impurity in the activation process. Diffusion is fast, it is very difficult to achieve shallow junctions and other shortcomings

[0006] 1. Since the source and drain of the Schottky transistor and the channel are in metal-semiconductor contact, affected by the height of the Schottky barrier, the leakage current of the Schottky transistor is relatively large, so that its switching ratio is restricted to a certain extent, and the on-state drive The current is small, and the off-state leakage current is large;

[0007]2. The germanium compound formed by metal deposition on germanium and annealed will cause condensation on the surface of the germanium compound to form many cavities due to the nucleation and condensation reaction, which is very important for the preparation of Xiao Tetky transistors are unfavorable, because the morphology of the germanium compound connected to the channel directly affects the performance of the germanium-based Schottky transistor, and the poor surface morphology of the germanium compound will lead to uneven source-drain properties and relatively large fluctuations , if too many voids are formed in the germanide film, the performance of the transistor will be greatly affected, and it may even fail to conduct at all.

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