| 摘要 |
PURPOSE: A formation method of contact hole is provided to improve a yield and a reliability and to prevent a short by covering a contact hole with a following bit line instead of an interlayer dielectric having a contact top CD(Critical Dimension) widening. CONSTITUTION: After forming a multiple of word lines(32), a nitride(33), a BPSG(Boro Phospho Silicate Glass)(34), and a first photoresist pattern, a first contact hole is formed by selectively etching the nitride(33) sequentially using the first photoresist pattern and the BPSG(34) as masks. Then, a polycrystalline silicon plug(36) is filled into the first contact hole and a planarization is performed on the resultant structure using the word lines(32) as an etch ending point. After forming a second BPSG(37), a third BPSG(38) as an interlayer dielectric, an anti-reflective layer and a second photoresist pattern, a second contact hole(41) is formed by selectively etching the third and second BPSGs(38,37) using the anti-reflective layer and the second photoresist pattern as a mask. At this time, a contact top CD widening is formed on the third BPSG(38), so that the third BPSG(38) is removed, thereby improving a reliability.
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