| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor memory element capable of stably maintaining the threshold voltage of a flash memory element. SOLUTION: This manufacturing method includes the following steps: a step for forming an element isolation film 5 in a trench after forming the trench on a semiconductor substrate 1; a step for forming wells 7 and 8 with a triple structure by an ion implantation process by using a mask after forming a screen oxide film on the semiconductor substrate; a step for forming a tunnel oxide film 10 and a first polysilicon layer on the entire upper surface to form a floating gate 11 by patterning after removing the screen oxide film; a step for forming a control gate on the semiconductor substrate in a memory cell region by patterning after forming a dielectric film 12 and a second polysilion layer 13 on the entire upper surface; a step for implanting ion for adjusting the threshold voltage into the semiconductor substrate exposed in a peripheral circuit region; and a step for forming the gate of a transistor by patterning after forming the gate oxide film and a third polysilicon layer on the semiconductor substrate in the peripheral circuit region. COPYRIGHT: (C)2004,JPO
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