Method for forming a salicide in semiconductor device
View Patent ↗Disclosed is a method for forming salicide in a semiconductor device. The method comprises the steps of: forming a first and a second gate oxide film and in a non-salicide region and a salicide region, the first gate oxide film being thicker than the second gate oxide film; forming a conductive layer and a nitride based hard mask layer, and then selectively removing the conductive layer, the hard mask layer, the first gate oxide film, and the second gate oxide film, thereby forming gate electrodes and simultaneously exposing an active region of the salicide region; forming a spacer oxide film on an upper surface, except for the hard mask layer, of a second resultant structure; selectively removing the spacer oxide film, thereby forming a spacer and simultaneously exposing the active region of the salicide region; removing the hard mask layer; and forming a salicide film on the upper surfaces of the gate electrodes and on the surface of the active region in the salicide region. Therefore, a non-salicide region and a salicide region can be formed selectively and simultaneously in a one-chip semiconductor device, so that the number of steps for a salicide forming process can be reduced.
1. A method for forming salicide in a semiconductor device, the method comprising the steps of:
(1) forming a first gate oxide film and a second gate oxide film in a non-salicide region and a salicide region of a silicon substrate, respectively, the first gate oxide film being thicker than the second gate oxide film;
(2) forming a conductive layer on an upper surface of a first resultant structure obtained through step (1), and then selectively removing the conductive layer, the first gate oxide film, and the second gate oxide film, thereby forming gate electrodes respectively in the non-salicide region and the salicide region and simultaneously exposing an active region of the salicide region;
(3) forming an ONO thin film and a nitride film on an upper surface of a second resultant structure which has been obtained through steps (1) to (2) and includes the gate electrodes;
(4) selectively removing the ONO thin film and the nitride film located in the salicide region;
(5) removing the nitride film remaining in the salicide region and forming a spacer on one side of each of the gate electrodes; and (6) forming a salicide film on the upper surfaces of the gate electrodes in the non-salicide region and the salicide region and on the surface of the active region in the salicide region.
2. The method as claimed in claim 1 , wherein a thickness of the first gate oxide film is 100˜300 Å and a thickness of the second gate oxide film is 1˜150 Å.
3. The method as claimed in claim 1 , wherein the ONO thin film comprises a first oxide film having a thickness of 0˜200 Å, a nitride film having a thickness of 0˜500 Å, and a second oxide film having a thickness of 0˜200 Å.
4. The method as claimed in claim 1 , wherein the step of selectively removing the ONO thin film and the nitride film located in the salicide region comprises the etching of the nitride film and the ONO thin film in the salicide region is performed using activated plasma of CHF 3 /CF 4 /O 2 /Ar.
5. The method as claimed in claim 4 , wherein etching gases used for the etching and flow rates thereof are CHF 3 : 1˜200 sccm, CF 4 : 1˜200 sccm, O 2 : 0˜20 sccm, Ar: 1˜1000 sccm, C 4 F 8 : 1˜50 sccm and N 2 : 0˜500 sccm.
6. The method as claimed in claim 1 , wherein the removing of the nitride film is performed by a down flow method and using O 2 /CF 4 as etching gas.