Method for making metal oxide semiconductor transistor

Abstract

The invention discloses a method for manufacturing a metal oxide semiconductor (MOS) transistor. In this method, a masking layer is deposited on the surface of the silicon substrate before the source / drain regions are formed. The shielding layer covers the gate electrode and the field oxide layer or the shallow isolation trench on the substrate with a uniform thickness. Next, high-concentration ion implantation is carried out on the silicon substrate, and its energy is controlled so that the ions cannot penetrate the shielding layer on the side wall of the gate electrode. After removing the shielding layer, the silicon substrate is doped with low-concentration ions. In this way, MOS transistors with LDD can be formed with fewer process steps.

Description

technical field [0001] The invention relates to a method for manufacturing a MOS transistor, in particular to a method for reducing the steps of forming an LDD. Background technique [0002] In a MOS transistor, the channel length is the distance between the source and drain. To make the component size smaller, the length of the channel must be shortened. However, it is well known that too short a MOS channel will generate hot electron effects (Hot Electron Effects) and affect the performance of the MOS transistor. In order to solve this problem, a lightly doped drain (LDD) can be formed at the place where the source and the drain are close to the channel. [0003] FIG. 1( a ) to FIG. 1( g ) show a method for forming an LDD of a conventional MOS transistor. [0004] First, according to the existing semiconductor process, a gate oxide layer 101 , a gate electrode 102 and a field oxide layer 103 are formed on a P-type silicon substrate 100 , as shown in FIG. 1( a ). Second...

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Problems solved by technology

Therefore, in order to form a MOS transistor with this LDD, its process steps will become quite complicated

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