Method for improving tensile stress of silicon nitride film in semiconductor devices

Abstract

The invention discloses a method for improving tensile stress of a silicon nitride film in semiconductor devices. The method comprises the following steps of adding a certain quantity of organic pore-forming agent into the silicon nitride film while depositing the silicon nitride film; irradiating the silicon nitride film with UV-light, wherein part of Si-H / N-H bonds in the silicon nitride film crack and shrink after obtaining energy, and because of volatilization of the organic pore-forming agent, the shrink of the film is enhanced; the organic pore-forming agent is Alpha-terpinene or NBDNorbornadiene. The film preparation method is applied in a CESL (contact etch stop layer) layer of CMOS (Complementary Metal-Oxide-Semiconductor Transistor)production and can improve the performance of NMOS (PMOS (N-channel Metal Oxide Semiconductor) devices.

Description

technical field [0001] The present invention generally relates to the technical field of integrated circuit manufacturing, and more particularly, the present invention relates to a method for increasing the tensile stress of silicon nitride films in semiconductor devices. Background technique [0002] As the feature line width of integrated circuits is reduced to less than 90nm, improving device performance through gate thickness, gate dielectric constant and junction depth can no longer meet the requirements of the process. Even if the gate thickness is controlled at 5 atomic layers, the junction depth is also Only 10nm. To meet the requirement of switching speed, high-stress silicon nitride technology has been widely studied. With the high stress applied by silicon nitride on the gate mechanism, the carrier mobility of MOS devices can be greatly improved. Specifically, the compressive stress on the PMOS structure can improve the mobility of holes, while the tensile stress...

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Problems solved by technology

In order to obtain a silicon nitride film with higher tensile stress, as shown in Figure 1, plasma treatment under a nitrogen atmosphere or ultraviolet light irradiation is usually used to remove a certain amount of hydrogen 2 in the film 1 (shown in Figure 1 The method of ultraviolet irradiation) shrinks the film 1 to increase the stress of the film 1. However, the highest stress that can be achieved by silicon nitride is about 1.7GPa

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