Insulated gate field-effect transistor
The invention aims at precisely making an effective junction depth sufficiently small with respect to a substrate surface having a steep PN junction stable in its configuration and having a channel formed therein in relation to an extension portion. Gate electrodes are formed on a P-type well and an N-type well through respective gate insulating films. Two extension portions are formed from two first epitaxial growth layers which contact regions, of the P-type well and the N-type well, where channels are to be formed, respectively, and which are at a distance from each other. Two second epitaxial growth layers are formed on the first epitaxial growth layers in positions which are further at a distance from facing ends of the two extension portions in a direction of being separate from each other. Thus, two source/drain regions are formed on a PMOS side and on an NMOS side each. In the case of this structure, there is adopted no ion implantation for introducing impurities into a deep portion. Hence, the impurities in the extension portions do not thermally diffuse into the substrate side through the activation anneal.
1. An insulated gate field-effect transistor having:
a semiconductor substrate;
a channel region in the semiconductor substrate;
a gate insulating film on the substrate above the channel region;
a gate electrode above the channel region and above the gate insulating film;
two first epitaxial growth layers on the substrate;
a sidewall spacer comprising a first layer and a second layer (1) a bottom surface of the first layer on a portion of the upper surface of the first epitaxial growth layers, (2) an upper surface of the first layer opposite of the bottom surface of the first layer, (3) a first side surface of the first layer next to the gate electrode and (4) a second side surface of the first layer located opposite of the first side surface (5) a first side surface of the second layer adjacent the second side surface of the first layer, (6) a second side surface of the second layer located opposite of the first side surface of the second layer, and (7) a bottom surface of the second layer on the upper surface of the first layer; and
two source/drain regions in the form of two second epitaxial growth layers respectively on the first epitaxial growth layers and adjacent to the second side surface of the second layer,
wherein,
the sidewall spacer establishes a horizontal distance between the gate electrode and said second epitaxial growth layer, and
a portion of each first epitaxial growth layer is located underneath the gate electrode.
2. The insulated gate field-effect transistor according to claim 1 , wherein an alloy layer made of an alloy of a semiconductor and metal is on said second epitaxial growth layer, and
said second epitaxial growth layer has a thickness such that a bottom surface of said alloy layer is above said first epitaxial growth layer.
3. The insulated gate field-effect transistor according to claim 1 , wherein an end of the first epitaxial growth layer located next to the side face of the gate electrode is inclined and has a distance, from said gate electrode, which increases as the height of the side face of the gate electrode increases, and
the gate electrode is partially stacked on said inclined end of the first epitaxial growth layer and the gate insulating film.