Low-noise surface level MOS capacitor for improved sensor quality factor
A low-power wireless ionizing radiation measurement system is provided that is intended to be used in a wearable dosimeter for occupational radiation monitoring.
1. A device comprising:
an epitaxial semiconductor layer grown on top of a starting semiconductor substrate to form a lower electrode of a MOSCAP,
wherein the epitaxial semiconductor layer comprises a left doped region, and a right doped region separated by a middle doped region comprising of the epitaxial semiconductor layer interposed there between,
wherein the left doped region and the right doped region have a same doping conductivity but a different doping level than the epitaxial semiconductor layer;
an insulating layer disposed over the epitaxial semiconductor layer; and
a plurality of top conductive layers disposed on top of the insulating layer,
wherein the plurality of top conductive layers comprise a left conductive layer overlying the left doped region, a middle conductive layer overlying the middle doped region and a right conductive layer overlying the right doped region, thereby forming a left upper electrode, a middle upper electrode and a right upper electrode of the MOSCAP respectively,
wherein the MOSCAP is biased across the middle upper electrode and the lower electrode and,
wherein the MOSCAP is read out across the left upper electrode and the right upper electrode.
2. The device of claim 1 , wherein the semiconductor substrate is P-type doped.
3. The device of claim 1 , wherein the doping level of the starting semiconductor substrate, the epitaxial semiconductor layer, the left doped region and the right doped region are selected based on desired response characteristics of the device.
4. The device of claim 1 , wherein the left doped region and the right doped region have a same doping level.
5. The device of claim 4 , wherein the left doped region and the right doped region have a higher doping level than the epitaxial semiconductor layer.
6. The device of claim 1 , wherein the epitaxial semiconductor layer has lower doping level than the starting semiconductor substrate.
7. The device of claim 1 , wherein the epitaxial semiconductor layer has a lower thickness than the starting semiconductor substrate.
8. The device of claim 1 , wherein the insulating layer is of a material selected from a group consisting of silicon oxide, silicon nitride and silicon oxynitride.
9. The device of claim 1 , wherein the left upper electrode, the middle upper electrode and the right upper electrode of the MOSCAP are of a material selected from a group consisting of polycrystalline silicon and metal.