| 摘要 |
Disclosed is a process for removing doped silicon dioxide from a structure selectively to undoped silicon dioxide. A structure having both doped and undoped silicon dioxide regions is exposed to a high density plasma etch having a fluorinated etch chemistry. Doped silicon dioxide is preferably removed thereby at a rate 10 times or more greater than that of undoped silicon dioxide. The etch is conducted in a chamber having an upper electrode to which a source power is applied and a lower electrode to which a bias power is applied sufficient to generate a power density on a surface of the structure such that the source power density is in a range less than or equal to about 1000 W per 200-mm diameter wafer surface. The high density plasma etch has an ion density not less that about 109 ions/cm3. A variety of structures are formed with the etch process, including self-aligned contacts to a semiconductor substrate.
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