1. A semiconductor device, comprising:
a semiconductor substrate;
a well of a first conductivity type which is formed on the semiconductor substrate, the well having a concave portion formed therein with varying depth in a gate width direction;
a gate electrode formed on an upper surface and inside of the concave portion via an insulating film;
a source region of a second conductivity type formed on one side of the gate electrode up to near a bottom portion of the gate electrode; and
a drain region of the second conductivity type formed on another side of the gate electrode up to near the bottom portion of the gate electrode.
2. A semiconductor device according to claim 1, wherein bottom portions of the source region and the drain region are formed at one of a position as deep as the bottom portion of the gate electrode and a position deeper than the bottom portion.
3. A semiconductor device according to claim 1 or 2, wherein a bottom portion side of the source region and the drain region is formed by a well of the second conductivity type.
4. A semiconductor device according to any one of claims 1 to 3, wherein an impurity concentration of a portion of the drain region which is adjacent to the gate electrode is set to be low.
5. A method of manufacturing a semiconductor device, comprising:
a concave portion forming step of forming a concave portion in the well, with varying depth in a gate width direction;
a gate electrode forming step of forming, after forming an insulating film on the concave portion, a gate electrode on an upper surface and inside of the concave portion via the insulating film, wherein the gate electrode is formed with a length of a portion of the gate electrode on the upper surface of the concave portion that is shorter than a length of the gate electrode inside of the concave portion; and
a source and drain forming step of implanting ions of a second conductivity type into both sides of the gate electrode to form a source region and a drain region up to near a bottom portion of the gate electrode.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A dust-proof plug for mobile phone, comprising an ornament and a plastic sheath, characterized in that: the plug further comprises a alloy contact pin, which is fixed on the ornament, and provided with a groove on the sidewall thereof, accordingly the plastic sheath is provided with a socket adapted to the alloy contact pin therein, wherein the alloy contact pin is bonded and fixed in the socket by gluing after being inserted into the socket.
2. The dust-proof plug for mobile phone according to claim 1, characterized in that: the socket is a tapered socket, the diameter of the upper port of the socket is equal to the diameter of cross section of the alloy contact pin in the portion corresponding to the upper port of the socket, the diameter of the lower port is approximately 0.1 to 0.3 mm smaller than the diameter of the upper port.
3. The dust-proof plug for mobile phone according to claim 1, characterized in that: the alloy contact pin is divided into an upper portion and a lower portion by the groove, and the diameter of cross section of the lower portion is approximately 0.1 to 0.3 mm larger than the diameter of cross section of the upper portion.
4. The dust-proof plug for mobile phone according to claim 3, characterized in that: the bottom end of the alloy contact pin is a needle tip.
5. The dust-proof plug for mobile phone according to claim 3, characterized in that: the groove is approximately 2.0 to 2.4 mm distant from the bottom end of the alloy contact pin.
6. The dust-proof plug for mobile phone according to claim 3, characterized in that: the width of the groove is 1 mm.