| 摘要 |
PURPOSE: To obtain optimized, intrinsic, long-channel and short-channel NMOS devices as in a PMOS device by manufacturing a VLSI structure on a semiconductor well, without additional steps and masks. CONSTITUTION: An N-well 10 is formed in a P-type silicon substrate 2, and an isolation field oxide 3 is formed in the middle of an MOS device that is constituted in and on the silicon substrate 2, before being selectively masked by a photoresist mask material. First, injection is performed through the field oxide 30 that is adjacent to active regions 50a-50c, a strong boron concentration is given to an NMOS device, field inversion in a substrate 2 under the oxide 30 adjacent to the NMOS device is prevented. Secondly, deep boron is injected into the region 50c, a short-channel NMOS device is optimized regarding the protection of a punch-through. Thirdly, an inversely doped injection is given to the region 50e, and a lower N-type background concentration is given to a long-channel PMOS device.
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