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Publication Date: 2005-Apr-15
Document File: 9 page(s) / 63K

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The Prior Art Database

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This invention is directed to a chemical delivery manifold for delivering an ultrapure chemical or a mixture of ultrapure chemicals from a chemical container to a point of use.  In particular, the invention is directed to chemical delivery manifold for delivering ultrapure chemicals to manufacturing process tools, such as semiconductor tools and optical fiber manufacturing process tools.

Chemical precursors are used to grow films in the manufacturing process of integrated circuits and optical fiber products.  These chemical precursors normally have ultrahigh purity levels and are fed from chemical containers to a point of use with chemical delivery systems.  The chemicals could be easily contaminated if the delivery lines and those connection points are not properly purged and cleaned.  Contaminants include ambient air, particulate matters, and moisture.  Contaminants may also include reaction products of chemical precursors and ambient air or moisture.  The contaminants may diffuse into the delivery lines from the ambient atmosphere when the lines are not properly protected.  Any contaminant will seriously deteriorate the production yields.  For example, particulate impurities could change the dielectric property of deposited films and short the conductive connections.

Most of the chemical precursors are delivered in liquid phase to the tools before chemical vapor deposition.  Some of the chemicals are in liquid phase themselves at room condition, such as TEOS (tetraethylorthosilicate), or TiCl4.  Some of the chemicals are in solid phase at low temperature and in liquid phase at an elevated temperature, such as PET (Tantalum Pentaethoxide), and TDMAT (tetrakis‑dimethylamino titanium).  Often, chemicals in the solid phase, such as BST (barium/strontium/titanate), are dissolved in a suitable solvent before delivery.  For a stable and continuous delivery of chemicals, a dual container either in series or in parallel is usually used for delivery.  An empty container could be replaced with a full container while another container is still in use.  In the process of replacing an empty container, chemicals remaining inside the line and the joints must be cleaned to prevent the residue chemical from contaminating the system, or spilling into the system.  Exposure to these chemicals should also be limited, as they are often extremely toxic, or pose a fire hazard or explosion risk.  Another reason to clean the residual chemical is that the residuals of most precursor chemicals mentioned above will react with air and moisture.  The reaction products will contaminate the delivery system and further the chemicals to be delivered.  Some of the chemical may also react with air and moisture to produce solid that is very difficult to be removed.  In this case, the delivery line could be blocked, resulting in discontinuation of delivery.

The method to protect the lines f...