Three-dimensional high voltage transistor and method for manufacturing the same
View Patent ↗A method for manufacturing a three-dimensional high voltage transistor is disclosed. According to the method, lengths and widths of channels are increased while the reducing transistor forming area on plane, and semiconductor devices are completely separated from each other while restraining parasitic capacitance, latch-up phenomena, and formation of field transistors. The three-dimensional high voltage transistor includes an active area of the three-dimensional high voltage transistor formed in the form of a column on predetermined areas of a Silicon-On-Insulator substrate, source and drain formed in the active areas of the three-dimensional high voltage transistor in the depth direction, a channel area formed between the source and the drain in the depth direction, and a column-shaped gate formed at the side of the channel area on the Silicon-On-Insulator substrate.
1. A method for manufacturing a three-dimensional high voltage transistor comprising the steps of:
defining an active area of the three-dimensional high voltage transistor by forming a trench in a single crystal silicon layer on a Silicon-On-Insulator substrate;
forming an isolation layer enclosing the active area by filing an oxide in the trench;
forming a source and a drain in the active area, wherein the source and the drain are spaced apart from each other to a predetermined space;
removing the isolation layer at a side of the active area between the source and the drain;
forming a gate oxide layer on an exposed surface of the active where the isolation layer is removed; and
filling a gate material where the isolation layer is removed.
2. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the trench is formed by dry etching using the Silicon-On-Insulator substrate as an etch-stop layer.
3. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the active area comprises a column structure of a single crystal layer remained after forming the trench.
4. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the source and the drain are formed by ion injection process while varying ion injection energy such that the source and the drain have uniform doses in the depth direction.
5. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the gate is formed at both sides of the active area of the three-dimensional high voltage transistor.
6. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the step of removing the isolation layer comprises a dry etching.
7. The method for manufacturing a three-dimensional high voltage transistor as set forth in claim 1 , wherein the gate material comprises poly-silicon or metal such as tungsten.