The present disclosure is directed to cyclic alkene derivatives stabilized with one or more stabilizer compounds to reduce or eliminate residue formation upon evaporation of such compositions, and methods for use of such compositions to form dielectric films.
The semiconductor industry requires numerous types of thin and thick films to prepare semiconductor devices, many of which are based on silicon. The elemental composition of these films is typically some combination of silicon and carbon with various combinations of oxygen, hydrogen, and fluorine. Relevant patents are: U.S. Pat. No. 6,914,335, Andideh et al. and U.S. Pat. No. 6,846,515, Vrtis et al. A frequently used process is chemical vapor deposition (CVD), and there are numerous variations of this process.
In a typical chemical vapor deposition process, a silicon containing compound is introduced into a deposition chamber containing a substrate to be coated. The silicon containing compound is then chemically or physically altered (i.e., reacted with another component, or subjected to application of an energy source such as radiation, heat (thermal CVD), or plasma (PECVD), etc.) to deposit a film on the substrate. Deposited films containing only silicon and oxygen (i.e., silicon oxide) have a dielectric constant of approximately 4 in the absence of pores, while films that also contain carbon (i.e., carbon doped silicon oxide) and/or pores often have dielectric constants lower than 4. Films with a dielectric constant below about 2.7 are preferred for newer semiconductor devices. A relevant patent is: U.S. Pat. No. 6,583,048, Vincent et al.
The properties of a layer deposited on a substrate, such as dielectric constant, film hardness and refractive index, are influenced by changing the composition of the chemistry that is fed into the film deposition tool and the process employed. The film properties can be tuned by changing the identity of the silicon containing compound by using a different flow gas, by using one or more different reactive gases, or by using post-deposition anneal techniques. Another means to affect the layer properties is to use a combination of silicon containing compounds or to combine a silicon containing compound(s) with one or more additive compounds. These techniques can be employed to alter the chemical composition of the film to adjust the film to the desired properties. Relevant patents are: U.S. Pat Nos. 6,633,076, 6,2176,58, 6,159,871, 6,479,110 and 6,756,323.
An alternative method of use for the additive compound is to employ compounds whose fragments or atoms are only temporarily resident in the film. The film can be post-treated to drive the fragments or atoms out of the film using radiation or a combination of radiation and reactive gases, such as oxygen, to create voids in the resulting film. This approach affects the properties (e.g. dielectric constant) of the deposited film. The compounds employed in this manner are described as porogens.
Typical porogens used in this type of approach are predominately composed of carbon and hydrogen. Relevant patents are: U.S. Pat. Nos. 6,846,515 and 6,756,323.
High volume semiconductor manufacturing places stringent demands on the equipment and on the purity and stability of the chemistries that flow through the equipment. Even trace amounts of some contaminants can degrade the properties of a deposited film. A chemical that is sent through chemical lines and a vaporizer means is expected to transport and vaporize cleanly and leave behind little or no residue during extended use. The longer a piece of equipment can operate between scheduled or unscheduled maintenance periods (such as, to clean out chemical lines or a vaporizer means that is fouled or clogged with polymeric residue), the more productive the tool is, making it more cost-effective. A deposition tool that must be shut down often for cleaning and maintenance is not as appealing to semiconductor manufacturing customers. Thus, continuous, long term operation of equipment is desirable. Vaporizer means can include several types of vaporization apparatuses, including, but not limited to, heated vaporizers (see U.S. Pat. Nos. 6,604,492, 5,882,416, 5,835,678, and references therein), bubbler ampoules (see U.S. Pat. Nos. 4,979,545, 5,279,338, 5,551,309, 5,607,002, 5,992,830 and references therein), flash evaporators (see U.S. Pat. No. 5,536,323 and references therein) and misting apparatuses (see U.S. Pat. Nos. 5,451,260, 5,372,754, 6,383,555, and references therein).
These purity and stability requirements are often difficult to achieve. Many materials may oxidize, polymerize or rearrange to some degree. Even small amounts of such byproducts may be undesirable for many semiconductor applications.
1,3,5,7-Tetramethylcyclotetrasiloxane (TMCTS) is a representative silicon containing compound which can be employed to produce low k dielectric films and is an example of the difficulty in maintaining stability. Initial work to establish reliable manufacturing processes was hampered by the product gelling at different points in the deposition process, including the chemical lines, vapor delivery lines, and within the deposition chamber. This indicated that the stability of pure TMCTS was not sufficient, and a variety of additives were studied. It was found that stabilizers were highly effective to stabilize TMCTS against exposure to air, specifically oxygen, for extended periods of time at ambient or elevated temperatures. When stabilizer-stabilized TMCTS is used now in semiconductor manufacturing, processes are more stable, and gel formation in a deposition tool is reduced significantly. A relevant patent is Teff et al. U.S. Patent Application Publication No. 2004/0127070.