TECHNICAL FIELD

The present disclosure relates to compositions and processes to selectively etch titanium silicon nitride in the presence of other materials, such as metal conductors, barrier materials, insulator materials, and exposed or underlying layers of copper, tungsten, and low-k dielectric materials.

BACKGROUND

The semiconductor industry is rapidly decreasing the dimensions and increasing the density of electronic circuitry and electronic components in microelectronic devices, silicon chips, liquid crystal displays, MEMS (Micro Electro Mechanical Systems), printed wiring boards, and the like. The integrated circuits within them are being layered or stacked with constantly decreasing thicknesses of the insulating layer between each circuitry layer and smaller and smaller feature sizes. As the feature sizes have shrunk, patterns have become smaller, and device performance parameters tighter and more robust. As a result, various issues which heretofore could be tolerated, can no longer be tolerated or have become more of an issue due to the smaller feature size.

In the production of advanced integrated circuits, to minimize problems associated with the higher density and to optimize performance, both high k and low k insulators, and assorted barrier layer materials have been employed.

Titanium silicon nitride (TiSiN) can be utilized for semiconductor devices and as ground layers and cap layers for precious metal, aluminum (Al) and copper (Cu) wiring. In semiconductor devices, it may be used as a barrier metal, a hard mask, or a gate metal.

In the construction of devices for these applications, TiSiN frequently needs to be etched. In the various types of uses and device environments of TiSiN, other layers are in contact with or otherwise exposed at the same time as the TiSiN is etched. Highly selective etching of the TiSiN in the presence of these other materials (e.g. metal conductors, dielectrics, and hard marks) is mandatory for device yield and long life. The etching process for the TiSiN may be a plasma etching process. However, using a plasma etching process on the TiSiN layer may cause damage to either or both the gate insulating layer and the semiconductor substrate. In addition, the etching process may remove a portion of the semiconductor substrate by etching the gate insulating layer exposed by the gate electrode. The electrical characteristics of the transistor may be negatively impacted. To avoid such etching damage, additional protective device manufacturing steps may be employed, but at significant cost.

Wet etching methods for TiSiN are known. Such methods may include use of etchants containing hydrofluoric acid in combination with other reagents. However, the selectivity with silicon based dielectrics and metals (e.g., Al) is not sufficient and other exposed metals in the device may also undergo corrosion or etching.

Thus, there is a need for TiSiN etching solutions that have relatively high etch rates, but have relatively low etch and corrosion rates for other semiconductor materials which are exposed or in contact with the TiSiN during the etching process.

SUMMARY

The present disclosure relates to compositions and processes for selectively etching TiSiN relative to metal conductor layers, hard mask layers and low-k dielectric layers that are present in the semiconductor device. More specifically, the present disclosure relates to a composition and process for selectively etching titanium silicon nitride relative to copper, tungsten, bottom anti-reflectant coating (BARC), high-k dielectric (e.g., HfOx), and interlayer dielectrics (ILD) (e.g., SiOx or low-k dielectrics).

In one aspect, the disclosure features an etching composition (e.g., an etching composition for selectively removing TiSiN) that includes: 1) at least one oxidizing agent; 2) at least one chelating agent; 3) at least one organic solvent; 4) at least one amine compound; and 5) water; in which the composition has a pH from about 6.5 to about 9.5.

In some embodiments, the etching compositions can include:

1) at least one oxidizing agent in an amount of from about 0.1% to about 30% by weight of the composition;

2) at least one chelating agent in an amount of from about 0.01% to about 1% by weight of the composition;

3) at least one organic solvent in an amount of from about 1% to about 30% by weight of the composition;

4) at least one amine compound comprising a diamine, an alkanolamine, or a quaternary ammonium compound, the at least one amine compound containing 1 to 6 carbon atoms and being in an amount of from about 0.1% to about 5% by weight of the composition; and

5) water;

in which the composition has a pH from about 6.5 to about 9.5.

In another aspect, the disclosure features a method that includes contacting a semiconductor substrate containing TiSiN features with an etching composition disclosed herein to remove the TiSiN features.

In still another aspect, the disclosure features an article formed by the method described above, in which the article is a semiconductor device (e.g., an integrated circuit).

