Manufacturing method for semiconductor device

Abstract

The invention discloses a manufacturing method for a semiconductor device. The manufacturing method for the semiconductor device comprises: a) a semiconductor substrate is provided, wherein the semiconductor substrate comprises a P-type transistor area and an N-type transistor area, and a gate dielectric layer and a covering layer are sequentially formed on the semiconductor substrate; b) a photoresist layer which exposes the P-type transistor area is formed on the covering layer; c) nitrogen treatment process is carried out, and nitrogen is mixed in the gate dielectric layer and the covering layer of the P-type transistor area; d) the photoresist layer is removed. By the fact that the nitrogen-atoms are mixed in the gate dielectric layer and the covering layer of the P-type transistor area to replace oxygen atoms at the interface, effective work function value of the covering layer in the P-type transistor area is increased, threshold voltage of a P-type transistor is reduced, so that the covering layer can be matched with work function layers of the P-type transistor area and the N-type transistor area at the same time.

Description

technical field [0001] The invention relates to a semiconductor manufacturing process, in particular to a method for manufacturing a semiconductor device. Background technique [0002] As the gate size shrinks to tens of nanometers, the thickness of the gate oxide layer drops below 3nm, causing problems such as excessive gate resistance, increased gate leakage, and depletion of the polysilicon gate. Therefore, people turn their attention to the metal gate technology again. The metal gate technology uses a metal with a lower resistance as the gate, and a material with a larger dielectric constant as the gate dielectric layer. [0003] The metal gate technology includes a gate-first process and a gate-last process. The Gate-first process refers to the formation of metal gates before performing drain / source region ion implantation and subsequent high-temperature annealing steps on the silicon wafer, while the Gate-last process is the opposite. Since the metal gate in the Gate...

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Problems solved by technology

However, since the covering layer under the N-type metal gate and the P-type metal gate is the same, if the work function of the covering layer is higher, the threshold voltage (Vt) of the P-type transistor will be reduced, and vice versa, the threshold voltage (Vt) of the N-type transistor will be reduced. threshold voltage, th

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