Back-to-back metal/semiconductor/metal (MSM) Schottky diode
View Patent ↗A method is provided for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor. The method deposits a Si semiconductor layer between a bottom electrode and a top electrode, and forms a MSM diode having a threshold voltage, breakdown voltage, and on/off current ratio. The method is able to modify the threshold voltage, breakdown voltage, and on/off current ratio of the MSM diode in response to controlling the Si semiconductor layer thickness. Generally, both the threshold and breakdown voltage are increased in response to increasing the Si thickness. With respect to the on/off current ratio, there is an optimal thickness. The method is able to form an amorphous Si (a-Si) and polycrystalline Si (polySi) semiconductor layer using either chemical vapor deposition (CVD) or DC sputtering. The Si semiconductor can be doped with a Group V donor material, which decreases the threshold voltage and increases the breakdown voltage.
1. A method for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, comprising:
providing a Si substrate;
forming a bottom electrode with a Pt layer overlying the Si substrate, and a TiN layer overlying the Pt layer;
forming an amorphous Si (a-Si) semiconductor layer overlying the bottom electrode, having a thickness in the range of 10 to 80 nanometers (nm);
forming a TiN top electrode overlying the a-Si semiconductor layer; and,
forming a MSM diode having a threshold voltage in the range of about 0.8 to 2 volts, and a breakdown voltage in the range of about 2.5 to 6 volts.
2. The method for forming a MSM back-to-back Schottky diode from a Si semiconductor according to claim 1 wherein forming the a-Si semiconductor layer includes forming an a-Si layer with a thickness of about 30 nm; and,
wherein forming the MSM diode includes forming an MSM diode with a threshold voltage of about 1.5 volts and a breakdown voltage of about 3.5 volts.
3. The method for forming a MSM back-to-back Schottky diode from a Si semiconductor according to claim 2 wherein forming the MSM diode includes forming an MSM diode with an on/off current ratio of about 1.5 ×10 2 amperes per square centimeters (A/cm 2 ) at 3 volts, to 6 ×10 −2 A/cm 2 at 1 volt.
4. The method for forming a MSM back-to-back Schottky diode from a Si semiconductor according to claim 1 further comprising:
doping the a-Si semiconductor layer with a Group V donor material; and,
wherein forming the MSM diode includes forming an MSM diode with a threshold voltage in the range of about 2 to 3.5 volts and a breakdown voltage in the range of about 6 to 12 volts.
5. The method for forming a MSM back-to-back Schottky diode from a Si semiconductor according to claim 4 wherein forming the a-Si semiconductor layer includes forming an a-Si layer with a thickness of about 30 nm; and,
wherein forming the MSM diode includes forming an MSM diode with a threshold voltage of about 2.5 volts and a breakdown voltage of about 6 volts.
6. A metal/semiconductor/metal (MSM) back-to-back Schottky diode fabricated from a silicon (Si) semiconductor, comprising:
a Si substrate;
a bottom electrode with a Pt layer overlying the Si substrate, and a TiN layer overlying the Pt layer;
an amorphous Si (a-Si) semiconductor layer overlying the bottom electrode, having a thickness in the range of 10 to 80 nanometers (nm); and,
a TiN top electrode overlying the a-Si semiconductor layer.
7. The MSM back-to-back Schottky diode from a Si semiconductor according to claim 6 wherein the MSM diode has a threshold voltage in the range of about 0.8 ; to 2 volts and a breakdown voltage in the range of about 2.5 to 6 volts.
8. The MSM back-to-back Schottky diode from a Si semiconductor according to claim 6 wherein the a-Si semiconductor layer has a thickness of about 30 nm; and,
wherein the MSM diode has a threshold voltage of about 1.5volts, a breakdown voltage of about 3.5 volts, and an on/off current ratio of about 1.5 ×10 2 amperes per square centimeters (A/cm 2 ) at 3 volts, to 6 ×10 −2 A/cm 2 at 1 volt.
9. The MSM back-to-back Schottky diode from a Si semiconductor according to claim 6 wherein the a-Si semiconductor layer includes a Group V donor dopant material; and,
wherein the MSM diode has a threshold voltage in the range of about 2 to 3.5 volts and a breakdown voltage in the range of about 6 to 12 volts.
10. The MSM back-to-back Schottky diode from a Si semiconductor according to claim 9 wherein the a-Si semiconductor layer has a thickness of about 30 nm; and,
wherein the MSM diode has a threshold voltage of about 2.5 volts and a breakdown voltage of about 6 volts.