Manufacturing method of semiconductor device

Abstract

A manufacturing method of a semiconductor device including a step of forming a via hole in an insulation layer including an organic low dielectric film, such as MSQ, SiC, and SiCN, and then embedding a wiring material in the via hole through a barrier metal. According to this method, a plasma treatment is performed after the via hole is formed and before the barrier metal is deposited, using a He / H2 gas capable of replacing groups (methyl groups) made of organic constituents and covering the surface of the exposed organic low dielectric film (MSQ) with hydrogen, or a He gas capable decomposing the groups (methyl groups) without removing organic low dielectric molecules. As a result, the surface of the low dielectric film (MSQ) is reformed to be hydrophilic and adhesion to the barrier metal is hence improved, thereby making it possible to prevent the occurrence of separation of the barrier metal and scratches.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a structure of a semiconductor device and a manufacturing method thereof, and more particularly to, in a damascene process using a low dielectric film having a bond of Si and a group made of organic constituents, such as MSQ, an interface: structure of a barrier metal and the low dielectric film and a surface treatment method thereof.[0003] 2. Description of the Related Art[0004] To meet the high integration of a semiconductor device and a reduction in chip size in recent years, not only the miniaturization of the wiring, but also the multi-level interconnection is being promoted. As a method of forming a multi-level interconnect structure, a so-called damascene process is generally performed, by which an interconnect is formed by embedding Cu in both a via hole and a wiring trench pattern concurrently followed by planarization through the CMP (Chemical Mechanical Polishing) method. The damascene process can inc...

AI Technical Summary

Problems solved by technology

The damascene process can increase density of wiring patterns; however, when the wiring patterns are formed too close, a parasitic capacitance between the wiring patterns causes problematic interconnect delay.

Hence, a reduction in interconnect capacitance becomes an issue of great importance to improve the interconnect delay.

However, when a low dielectric film having a bond of Si and a group made of organic constituents, such as MSQ, is used as the second interlayer insulation film 18, it does not adhere well to an inorganic material, particularly, a barrier metal, and as shown in FIG. 3B, the barrier metal is separated from an MSQ-based low dielectric film during CMP, which gives rise to a problematic scratch 21 on the surface of the MSQ-based low dielectric film, or stress caused by the multi-level interconnection gives rise to problematic film separation 20 at the barrier metal / MSQ interface having poor adhesion.

This method, however, cannot avoid an increase in dielectric constant when a thick film is formed, and deterioration in adhesion associated with a pin-hole when a thin film is formed.

However, because merely a sputtered material is etched away through Ar sputtering, it proves to be ineffective in reforming the MSQ surface.

This method, however, has a problem that water comes into the film and a dielectric constant of the insulation film is increased; moreover, the surface of the film is made rough and a residue is left thereon.

However, the reliability reduced by poor adhesion of the low dielectric film to an inorganic material, particularly, a barrier metal, poses a serious problem, and there has been a need to develop a structure capable of increasing adhesion of the low dielectric film to the barrier metal, and a process capable of reforming the surface of the low dielectric film.

Impurities and foreign matters adhering on the surface of a sputtered material can be removed through Ar sputtering; however, applying Ar sputtering to a low dielectric film having a bond of Si and a group made of organic constituents, such as MSQ, cannot improve adhesion of the low dielectric film to a barrier metal.

However, adhesion was not improved by applying RF bias in the case of Ar, from which it is understood that the effect cannot be achieved unless an adequate gas is selected.

However, it remains uncertain whether the improvement effect is attributed to removal of methyl groups on the MSQ surface.

In this case, however, hydrogen atoms penetrate into the interior of a substance exposed to plasma, and in particular, in a case where Cu used as a wiring material is exposed, there occurs a problem that Cu becomes brittle.

In regard to a component ratio of a H.sub.2 gas and a noble gas, when a ratio of a H.sub.2 gas is increased, the reactivity becomes too high to remain controllable, and there is the possibility that a replacement-reaction of methyl groups takes place not only on the surface layer, but also in the interior, which undesirably increases a dielectric constant of MSQ.

In this case, however, Cu used as a wiring material undergoes nitridation with ammonia, and an adverse effect on the reliability of interconnections is concerned.

Images