Low-K Precursors Adapted for Incorporation of Porosity
Publication Date: 2009-Jul-15
The IP.com Prior Art Database
LOW-K PRECURSORS ADAPTED FOR
INCORPORATION OF POROSITY
Disclosed herein are non-limiting embodiments of precursor compositions and their methods of use in the manufacture of semiconductor devices.
Unless special measures are taken to improve the electrical properties of interconnect materials, the benefits in speed and device density that can be obtained by reducing dimensions in integrated circuits, tend to be negated by increases in interconnect delay. This is the driving force behind the adoption of copper, which reduces resistivity, and lower-dielectric constant insulators, which reduce capacitance.
The formerly-used dielectric, SiO2, has been replaced first by SiOF (i.e. fluorine-doped silicon dioxide), SiCOH (“carbon-doped oxide” – which adds organic groups such as –CH3 to the SiO2 network) and most recently porous SiCOH, also or pSiCOH. pSiCOH films may be deposited by liquid-phase or gas-phase methods. Gas-phase methods include plasma-enhanced chemical vapor deposition (PECVD). To date, PECVD is the most commercially successful approach, in large part because it uses equipment designs and know-how accumulated through years of experience on SiO2 and SiOF. Nonetheless, liquid-phase deposition methods have certain advantages. Among those advantages is the wider available selection of precursor molecules that incorporate desired properties into their molecular structure. As the liquid phase deposition process is relatively “gentle” the structural characteristics of the molecule tend to be incorporated into the film. In PECVD, the deposition environment is much more energetic and the relationship between the structure of the deposited film and that of the precursor molecules is much more tenuous. This disadvantage of PECVD can be somewhat reduced by using a plasma of lower energy, which allows the structure of the precursor to be better preserved in the deposited film. In the some embodiments of the present invention, precursors are described that are adapted to deposit films are lower energies, which in turn allows the structure of the precursor to be reflected in that of the deposited film.
The PECVD of pSiCOH films has been extensively studied and discussed by many authors and inventors, as summarized in, for example, US 7384471 (Vrtis et al.). The usual procedure is deposition of a hybrid film from an organosilicon precursor and an organic compound referred to as a “porogen”. The hybrid film is subsequently thermally treated, usually with accompanying exposure to ultraviolet light, to cause a major fraction of organic component to escape the film as gaseous species, forming pores. The thermal/uv treatment also increases cross-linking of the organosilane backbone, which improves mechanical properties. Vrtis et al. mention that the porogen may be inc...