Manufacturing method of semiconductor device
In a semiconductor device having a MOS transistor and a diffused resistor layer, a leakage current of a diffused resistor layer is suppressed. A film of gate electrode material is formed over the entire surface of an N-type well, a photoresist layer is formed to mask a region to form a gate electrode and portions of the diffused resistor layer and the gate electrode and a damage prevention films are formed by anisotropically etching the film of gate electrode material. After forming a CVD insulation film over the entire surface of the N-type well, sidewall spacers are formed on sidewalls of the gate electrode and the damage prevention films by anisotropically etching the CVD insulation film. A source layer and a drain layer of the MOS transistor and contact regions to the diff-used resistor layer are formed by doping portions of the N-type well and the diffused resistor layer with high concentration P-type impurities using the gate electrode, the damage prevention film and the sidewall spacers as a mask.
1. A method of manufacturing a semiconductor device comprising a MOS transistor and a diffused resistor layer that are formed on a semiconductor substrate, the method comprising:
forming an isolation layer on the semiconductor substrate;
forming a gate insulation film on the semiconductor substrate;
forming the diffused resistor layer by doping with a low concentration of impurities a portion of the semiconductor substrate defined by the device isolation layer;
forming a film of a gate electrode material on the device isolation layer and the gate insulation film;
forming a mask on the film of the gate electrode material to cover portions of the film of the gate electrode material that correspond to a gate electrode of the MOS transistor and an area of the diffused resistor layer;
etching the film of the gate electrode material using the mask so that the gate electrode and a damage prevention film are formed;
forming a spacer insulation film over a surface of the semiconductor substrate on which the gate electrode and the damage prevention film are formed; and
etching the spacer insulation film so that a sidewall spacer is formed on a sidewall of the gate electrode and another sidewall spacer is formed on a sidewall of the damage prevention film.
2. The method of claim 1 , further comprising doping portions of the semiconductor substrate with a high concentration of impurities using the gate electrode, the damage prevention film and the sidewall spacers as a mask so that a source layer and a drain layer of the MOS transistor are formed.
3. The method of claim 1 , wherein the forming of the spacer insulation film comprises a chemical vapor deposition.
4. The method of claim 1 , further comprising forming a bipolar transistor on the semiconductor substrate.
5. A method of manufacturing a semiconductor device comprising a MOS transistor and a diffused resistor layer of a first conductivity type that are formed on a semiconductor substrate of the first conductivity type, the method comprising:
forming a well of a second conductivity type on the semiconductor substrate;
forming a device isolation layer on the well;
forming a gate insulation film on the well;
forming a photoresist layer having an opening above a first region of the well defined by the device isolation layer;
doping the first region of the well with a low concentration of impurities of the first conductivity type through the opening of the photoresist layer so that the diffused resistor layer of the first conductivity type is formed;
forming a film of a gate electrode material on the device isolation layer and the gate insulation film;
forming a mask on the film of the gate electrode material to cover portions of the film of the gate electrode material that correspond to a gate electrode of the MOS transistor and an area of the diffused resistor layer;
etching the film of gate the electrode material using the mask so that the gate electrode and a damage prevention film are formed;
forming a spacer insulation film over a surface of the semiconductor substrate on which the gate electrode and the damage prevention film are formed;
etching the spacer insulation film so that a sidewall spacer is formed on a sidewall of the gate electrode and another sidewall spacer is formed on a sidewall of the damage prevention film; and
doping second regions of the well and portions of the diffused resistor layer with a high concentration of impurities of the first conductivity type using the gate electrode, the damage prevention film and the sidewall spacers as a mask so that a source layer and a drain layer of the MOS transistor and contact regions to the diffused resistor layer are formed.
6. The method of claim 5 , wherein the forming of the spacer insulation film comprises a chemical vapor deposition.
7. The method of claim 5 , further comprising forming a bipolar transistor on the semiconductor substrate.