How the transistor is formed

Abstract

A method for forming a transistor, comprising: providing a semiconductor substrate, the semiconductor substrate including a PMOS region, a PMOS gate structure is formed on the surface of the semiconductor substrate in the PMOS region; semiconductor substrates on both sides of the PMOS gate structure A groove is formed in the bottom; a first stress layer is formed in the groove by a first epitaxial process, and the upper surface of the first stress layer is lower than the upper surface of the semiconductor substrate; a second stress layer covering the first stress layer is formed by a second epitaxial process The second stress layer, the material of the second stress layer contains carbon atoms, and the upper surface of the second stress layer is higher than the upper surface of the semiconductor substrate or is flush with the upper surface of the semiconductor substrate. The invention improves the density and stability of the stress layer near the upper surface of the semiconductor substrate, reduces the rate at which the stress layer is eroded by chemical substances in the transistor forming process, thereby increasing the carrier mobility of the transistor and increasing the driving current of the transistor.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a transistor. Background technique [0002] With the continuous development of semiconductor technology, carrier mobility enhancement technology has been widely studied and applied. Improving the carrier mobility in the channel region can increase the driving current of MOS devices and improve the performance of the devices. [0003] In the existing manufacturing process of semiconductor devices, since stress can change the energy gap and carrier mobility of silicon materials, it has become an increasingly common means to improve the performance of MOS transistors through stress. Specifically, by properly controlling the stress, the mobility of carriers (electrons in NMOS transistors and holes in PMOS transistors) can be increased, thereby increasing the driving current, thereby greatly improving the performance of MOS transistors. [0004] At pres...

AI Technical Summary

Problems solved by technology

[0005] The introduction of embedded silicon germanium technology can improve the carrier mobility of transistors to a certain extent, but in practical applications, it is found that in the process of forming transistors, the quality of embedded silicon germanium in transistors needs to be improved

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