| 摘要 |
PURPOSE: A formation method of plugs is provided to stabilize a CMP(Chemical Mechanical Polishing) and to prevent an isolation layer attack of a cell region by forming a plug after roundly forming edge portions of a contact hole. CONSTITUTION: After sequentially forming a multiple of word lines(32), a nitride(33), a BPSG(Boron Phosphor Silicate Glass)(34) as an interlayer dielectric, and a photoresist pattern, a contact hole is formed by selectively etching the nitride(33) sequentially using the photoresist pattern and the BPSG(34) as a mask. At this time, nitride spacers(33a) are formed on each one side of the word lines(32). The edge portions of the contact hole are roundly formed by performing a reflow on the BPSG(34) using a thermal process at SiH4, N2, O2, or H2O gas atmosphere. Then, a polycrystalline silicon plug(36) is flatly filled into the contact hole.
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