Sidewall protection for a via hole formed in a photosensitive, low dielectric constant layer
 A method for forming a via hole, in an insulator layer, without the use of photoresist procedures, has been developed. A photosensitive, low dielectric constant layer, is used as an interlevel insulator layer, between metal interconnect structures. Direct exposure, of a specific region of the photosensitive, low dielectric constant layer, converts the a specific region of the photosensitive, low dielectric constant layer, to a material that remains insoluble in a specific solution, while an unexposed region, of the same layer, can be selectively removed, creating the desired via hole. A silicon oxide deposition, and an anisotropic dry etch procedure, are employed to protect exposed surfaces of the photosensitive, low dielectric constant layer, in the form of silicon oxide spacers, formed on the sides of the via hole, and a silicon oxide layer, overlaying the top surface of the photosensitive, low dielectric constant layer. 
Industrial Technology Research Institute
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Lai-Juh Chung Liang
Chen Chang