Patent ID: 6492215
Filing Date: 2002-12-10
Classification: H01L

Abstract:
A method of fabricating a semiconductor device comprising the steps of:forming an oxide film on the entire surface of a semiconductor substrate through oxidation thereof in an oxidizing atmosphere; etching the oxide film on the semiconductor substrate, in an N channel region where an N channel MOS device is to be formed; forming a first buffer oxide film for implanting a p-type dopant into the N channel region; implanting the p-type dopant into the N channel region of the semiconductor substrate; forming a second buffer oxide film on the entire surface of the semiconductor substrate after etching the oxide film formed on the entire surface of the semiconductor substrate; implanting an n-type dopant into a P channel region of the semiconductor substrate, where a P channel MOS device is to be formed, using photoresist as a mask; forming a pad oxide film on the entire surface of the semiconductor substrate after etching the second buffer oxide film, and activating the respective dopants implanted in an oxidizing atmosphere; forming a nitride film composed of a silicon nitride film, on the pad oxide film; etching the nitride film in regions of the semiconductor substrate where field oxide films are to be formed; removing the nitride film and pad oxide film after forming the field oxide films on the semiconductor substrate by means of a selective oxidation method for effecting device isolation between the N channel region and the P channel region; forming a gate oxide film on the entire surface of the semiconductor substrate, in the N channel region and the P channel region, in an oxidizing atmosphere, and forming a gate silicon nitride film on the entire surface of the gate oxide film; forming a first gate electrode material on the entire surface of the gate silicon nitride film, and forming gate electrodes by a photo-etching method; forming a memory oxide film by oxidizing the entire surface of the semiconductor substrate in an oxidizing atmosphere, and turning the memory oxide film into an nitride oxide film by annealing in an ammonia atmosphere; forming a memory nitride film on the memory oxide film, forming a top oxide film by oxidizing the memory nitride film in an oxidizing atmosphere, and forming a second gate electrode material on the entire surface of the top oxide film; forming a memory, gate electrode by photo-etching the second gate electrode material, the top oxide film, the memory nitride film, and the memory oxide film; forming a highly doped n-type layer in regions for forming a source and drain, in the N channel region of the semiconductor substrate, using photoresist as a mask against ion implantation; forming a highly doped p-type layer in regions for forming, a source and drain, in the P channel region of the semiconductor substrate, using photoresist as a mask against ion implantation; forming an interlevel insulator composed primarily of a silicon dioxide film on the entire surface of the semiconductor substrate; activating the highly doped n-type and p-type layers by annealing; forming a plurality of contact holes in the interlevel insulator by means of the hot-etching method; and forming interconnections connected, via the contact holes, to the gate electrode, the source, and the drain of the N channel MOS device, the P channel MOS device, and a MONOS device, respectively.