Method for forming fin field effect transistor

Abstract

A forming method of a fin type field effect transistor comprises the following steps: providing a semiconductor substrate having a fin portion and a dummy grid electrode crossing a top portion and a side wall of the fin portion; forming an interlayer medium layer on the fin portion on two sides of the dummy grid electrode and the semiconductor substrate, and a top surface of the interlayer medium layer is flush with a top surface of the dummy grid electrode; etching the dummy grid electrode until the dummy grid electrode with partial thickness is left on the top of the fin portion, thereby forming a first groove; forming a first side wall on a side wall of the first groove; using the first side wall as a mask to continuously etch the dummy grid electrode through anistropic etching technology until the semiconductor substrate is exposed, thereby forming a second groove; processing the remained dummy grid electrode so as to form a second side wall; forming a metal grid electrode in the second groove comprising the second side wall. The threshold-voltage of the fin type field effect transistor formed by the method can be controlled, and the formed fin type field effect transistor has better performance.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming a fin field effect transistor. Background technique [0002] In order to keep up with the pace of Moore's Law, people have to gradually shrink the feature size of a metal oxide semiconductor field effect transistor (MOSFET for short). Doing so can bring benefits such as increasing chip density and improving the switching speed of MOSFETs. However, as the channel length of the transistor is shortened, the distance between the drain and the source is also shortened, so that the control ability of the gate to the channel becomes worse, and the difficulty of pinching off the channel by the gate voltage is also reduced. It becomes larger and larger, so that the phenomenon of subthreshold leakage (Subthreshold leakage), that is, the so-called short-channel effects (short-channel effects, referred to as SCE) is more likely to occur. [0003] Fo...

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Problems solved by technology

[0005] However, with the continuous reduction in the size of FinFETs, it becomes more and more difficult to control the threshold voltage of FinFETs, especially the disturbance of dopant substances makes the above problems more prominent

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