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Publication Date: 2008-Mar-18
Document File: 9 page(s) / 60K

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The Prior Art Database

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Various non-limiting embodiments according to the current invention are hereafter described.

Disclosed are embodiments of a method for the deposition tantalum nitride from organic tantalum sources for semiconductor manufacturing

-           using a deposition apparatus (LPCVD, MOCVD, pulsed-CVD, ALD) in a reaction furnace

-           by the early transition metal (Ti, Ta…) precursor, either pure or in association with an inert gas or chemical

-           by supplying or not ammonia in association with another inert gas

-           by supplying or not a carbon source

-           by supplying or not a silicon source

depending on the target tantalum-based material targeted (Ta, TaN, TaSi2, TaC, TaCN…).

Also included is the use of a solution to deliver this novel organic tantalum precursor so as to accommodate it for ALD/MOCVD applications (i.e. having the desired physical properties:  liquid at the vaporized temperature, volatile, of low viscosity…).

With dramatic device dimensions shrinkage, one of the most concerning issues of scaling of metal-oxide-semiconductor field effect transistor (MOSFETs) is the need for alternative gate-electrode materials, because of the adverse gate-deplation effects for dual poly-Si gate technology and because of integration issues between poly-Si and high-k dielectrics.  Since metals are very conductive and do not suffer from depletion effects, one/some of them will be chosen for future generations.  The criteria of choice are as follows:

-           relevant work function

-           easy to deposit

-           easy to etch and clean

Taking into account of their respective work function and the possibility to tune it using appropriate dopants, tantalum nitride might be an attractive candidate for both PMOS and NMOS, even though the work function of thin films might be significantly different from bulk depending on the deposition and the annealing conditions.  To some extent, it will also depend on the high-k material deposited underneath.

Many precursors for deposition have been considered so far either for electronics or other applications, such as:

-           Tantalum halides, including TaF5. which has been extensively studied to form Ta, TaNx with different reductants (H2, silanes, diborane. . .). There are concerns regarding surface roughness when using this highly aggressive precursor.

-           TaC15: it is a volatile solid; it is not very convenient to use and deliver.  On top of that, the deposition temperature required exceeds 600 ºC.

-           amino tantalum precursors such as TBTDET or TAlMATA, which are liquid near RT, and therefore would are easy to deliver even in the pure form.  ...