| 摘要 |
A novel graded composite silicon nitride/silicon oxide (SNO) hard mask, and manufacturing method is achieved. This novel SNO film improves the profile (optical fidelity) of the photoresist etch mask image used to pattern the SNO film, and thereby improves the critical dimensions (CD) for deep submicrometer semiconductor circuits. After forming a stress release layer, such as a pad oxide layer, on a semiconductor substrate, the graded composite Si3N4-SiO2 layer (SNO) is deposited by LPCVD and starting with SiH4 and NH3 as reactant gases. A nitrogen (N) rich film (Si3N4) is formed on the pad oxide layer. During deposition the NH3 flow rate is reduced and N2O is introduced to form a graded silicon oxynitride (SiON) film which has an oxygen-rich film (SiO2) at the top surface of the SNO layer. This SiON film modifies (reduces) the adsorption constant at the surface of the SNO layer. When the photoresist etch mask is formed on the SNO layer by exposing a photoresist layer with DUV radiation (through a reticle or photomask) and developed, the decomposition of the photoresist at the photoresist-hard-mask interface is minimized. This eliminates the need for an additional plasma treatment in oxygen of a Si3N4 hard mask used in the prior art.
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