Low-k Precursor (18-Jan-2010)

Disclosed herein are non-limiting embodiments of materials and methods which may be used in the manufacture of semiconductor, photovoltaic, flat panel or LCD-TFT devices.

Background

Insulating films that simultaneously providing  low dielectric constant (“low-k”) are critically required for semiconductor manufacturing (see International Technology Roadmap for Semiconductors, 2007 edition, Interconnect chapter:  http://www.itrs.net/Links/2007ITRS/2007_Chapters/2007_Interconnect.pdf). 

In recent years, the most successfully used low-k materials have been carbon-doped silicon oxides containing Si, C, O and H (i.e. “SiCOH”), deposited by Plasma-Enhanced Chemical Vapor Deposition (PECVD) as described for example in US7,030,468 and US7,282,458 (both to Gates et al.).  A major advantage of these materials is that they can be deposited using PECVD equipment which provides high throughput and is well-understood in semiconductor manufacturing, owing to its use for depositing SiO₂ dielectrics.  Silane or tetraethoxysilane (TEOS) are widely used precursors for SiO₂ deposition, whereas other precursors, incorporating Si-C bonds, are used for SiCOH deposition.

The dielectric constant of a dielectric film may be further reduced by using a porogen to introduce porosity, as in, for example US 7,288,292 (also Gates et al.).  In general, the porogen may be an organic compound that is co-deposited with a silicon-containing precursor which forms the low-k matrix.  The porogen may subsequently removed by “curing” the film, most commonly by exposing it to UV light in combination with heating.  Other curing methods, e.g. heating alone or electron-beam curing, have also been studied.  One drawback of this approach is that that the porogen incorporation into the desired film is often very low.  Thus very large amounts of porogen must be used in order to incorporate adequate quantities into the desired film.  Another drawback is that the curing process is time-consuming.  Pure thermal curing may take over one hour.  UV-assisted curing is faster, typically taking 10 – 15 minutes.  However, even this time is long compared to typical wafer-processing times of 1 – 5 minutes (e.g. for deposition of a low-k film by PECVD).

There is a need in the art for porogens with improved incorporation in SiCOH films, adequate volatility, and available at manageable cost.  The resultant films must have a dielectric constant (k) of 2.4 or lower.  In addition, materials which lead to porous SiCOH films without the need for a separate curing step would be highly advantageous.

Description of Preferred Embodiments

Cyclohexylmethyldimethoxysilane (shown below) is widely used as an electron-donor in manufacture of polypropylene by Ziegler-Natta catalysis. We now propose it for use as a precursor in deposition of l...