Abstract: A method for contact profile improvement is described. The contact window is formed over a substrate having at least one element. A first oxide layer is formed on the substrate. A borophosphosilicate glass layer is formed on the first oxide layer and the borophosphosilicate glass layer is treated by a planarization process. The contact window is formed in the first oxide layer and the borophosphosilicate glass layer. The element on the substrate is exposed therein. A second oxide layer is formed on the borophosphosilicate glass layer, the sidewall and the bottom of the contact window, with overhangs formed at an opening of the contact window. A spacer on the sidewall of the contact window is formed by etching the second oxide layer to further expose the surface of the borophosphosilicate glass layer. Finally, a native oxide on the bottom of the contact window is removed by a wet etching process and the etching selectivity between the native oxide and the spacer is smaller than 1.

Abstract: A method for contact profile improvement is described. The contact window is formed over a substrate having at least one element. A first oxide layer is formed on the substrate. A borophosphosilicate glass layer is formed on the first oxide layer and the borophosphosilicate glass layer is treated by a planarization process. The contact window is formed in the first oxide layer and the borophosphosilicate glass layer. The element on the substrate is exposed therein. A second oxide layer is formed on the borophosphosilicate glass layer, the sidewall and the bottom of the contact window, with overhangs formed at an opening of the contact window. A spacer on the sidewall of the contact window is formed by etching the second oxide layer to further expose the surface of the borophosphosilicate glass layer. Finally, a native oxide on the bottom of the contact window is removed by a wet etching process and the etching selectivity between the native oxide and the spacer is smaller than 1.