US 5,514,614 A · Method for producing quantization functional device utilizing a resonance tunneling effect · patentgrep

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Abstract

By etching, a first groove and a second groove are formed in a silicon substrate. Surfaces of the side walls of these grooves have a surface orientation of (111). The first and second grooves sandwich a silicon thin plate therebetween, which is formed as a part of the silicon substrate. The silicon thin plate is sufficiently thin so as to act as a quantum well. Further, a pair of silicon oxide films acting as tunneling barriers are formed on the surfaces of the side walls of the silicon thin plate, thus forming a double barrier structure. In addition, a pair of polysilicon electrodes are formed and sandwich the double barrier structure. As a result, the structure of a resonance tunneling diode, which utilizes the resonance tunneling effect, is provided. Adding a third electrode to the above structure provides a hot electron transistor. In the quantization functional devices having the above-described configuration, the satisfactory resonance effect is obtained due to a high crystallinity of the quantum well, a high potential barrier brought by the high quality silicon oxide films used as the tunneling barriers and a smooth interface between the quantum well and the tunneling barriers.

Claims50

Dependent claims

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon substrate having a surface orientation of (001);
(b) forming a first opening and a second opening in the etching protection film in one of a parallel direction and a perpendicular direction to a <110>
crystal orientation of the silicon substrate, the first opening and the second opening being parallel to each other;
(c) covering the second opening with an etchant resistive material;
(d) forming a first groove in the silicon substrate at a position corresponding to the first opening by etching;
(e) removing the etchant resistive material;
(f) performing crystalline anisotropic etching to form the first groove into a shape having a substantially diamond-shaped cross section and a surface having a surface orientation of (111), and to form a second groove having a V-shaped cross section and a surface having a surface orientation of (111) in the silicon substrate at a position corresponding to the second opening, thereby forming a silicon thin plate sandwiched between the first groove and the second groove, surfaces of the silicon thin plate having a surface orientation of (111), and a distance between the surfaces of the silicon thin plate being sufficiently thin to allow the silicon thin plate to act as a quantum well;
(g) forming a pair of tunneling barriers on the surfaces of the silicon thin plate;
(h) forming a polysilicon layer on a surface of the silicon substrate so as to fill the first groove and the second groove, and doping an impurity having an identical conductivity with the conductivity of the silicon substrate into the polysilicon layer at a high density;
and
(i) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

8 more elements

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon substrate having a surface orientation of (001);
(b) forming a first opening and a second opening in the etching protection film in one of a parallel direction and a perpendicular direction to a <110>
crystal orientation of the silicon substrate, the first opening and the second opening being parallel to each other;
(c) covering the second opening with an etchant resistive material;
(d) forming a first groove in the silicon substrate at a position corresponding to the first opening by etching;
(e) removing the etchant resistive material;
(f) covering the first opening with a second etchant resistive material;
(g) forming a second groove in the silicon substrate at a position corresponding to the second opening by etching;
(h) removing the second etchant resistive material;
(i) performing crystalline anisotropic etching to form each of the first groove and the second groove into a shape having a substantially diamond-shaped cross section and a surface having a surface orientation of (111), thereby forming a silicon thin plate sandwiched between the first groove and the second groove, surfaces of the silicon thin plate having a surface orientation of (111), and a distance between the surfaces of the silicon thin plate being sufficiently thin to allow the silicon thin plate to act as a quantum well;
(j) forming a pair of tunneling barriers on the surfaces of the silicon thin plate;
(k) forming a polysilicon layer on a surface of the silicon substrate so as to fill the first groove and the second groove, and doping an impurity having an identical conductivity with the conductivity of the silicon substrate into the polysilicon layer at a high density;
and
(1) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

11 more elements

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon substrate having a surface orientation of (001);
(b) forming a first opening in the etching protection film in one of a parallel direction and a perpendicular direction to a <110>
crystal orientation of the silicon substrate;
(c) forming a first groove in the silicon substrate at a position corresponding to the first opening by etching;
(d) performing crystalline anisotropic etching to form the first groove into a shape having a substantially diamond-shaped cross section and a surface having a surface orientation of (111);
(e) forming a tunneling barrier on the surface of the first groove;
(f) forming a second opening in the etching protection film parallel to the first opening;
(g) performing crystalline anisotropic etching to form a second groove having a cross section of a predetermined shape and a surface having a surface orientation of (111) in the silicon substrate at a position corresponding to the second opening, thereby forming a silicon thin plate sandwiched between the first groove and the second groove, surfaces of the silicon thin plate having a surface orientation of (111), and a distance between the surfaces of the silicon thin plate being sufficiently thin to allow the silicon thin plate to act as a quantum well;
(h) forming a tunneling barrier on the surface of the second groove while increasing the thickness of the tunneling barrier formed on the surface of the first groove;
(i) forming a polysilicon layer on a surface of the silicon substrate so as to fill the first groove and the second groove, and doping an impurity having an identical conductivity with the conductivity of the silicon substrate into the polysilicon layer at a high density;
and
(j) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

9 more elements

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon-on-insulator substrate having a surface orientation of (110);
(b) patterning the etching protection film into a rectangular shape in one of a parallel direction and a perpendicular direction to a <112>
crystal orientation of the silicon-on-insulator substrate;
(c) performing crystalline anisotropic etching to etch an exposed surface of the silicon-on-insulator substrate up to an insulating layer of the silicon-on-insulator substrate by using the patterned etching protection layer as a mask, thereby forming a silicon microscopic structure, surfaces of the silicon microscopic structure having a surface orientation of (111), and a distance between the surfaces of the silicon microscopic structure being sufficiently thin to allow the silicon microscopic structure to act as a quantum well;
(d) forming a pair of tunneling barriers on the surfaces of the silicon microscopic structure;
(e) forming a polysilicon layer on a surface of the silicon-on-insulator substrate including the silicon microscopic structure, and doping an impurity having an identical conductivity with the conductivity of the silicon-on-insulator substrate into the polysilicon layer at a high density;
and
(f) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

5 more elements

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon-on-insulator substrate having a surface orientation of (001);
(b) patterning the etching protection film into a rectangular shape in one of a parallel direction and a perpendicular direction to a <110>
crystal orientation of the silicon-on-insulator substrate;
(c) forming a resist mask to cover an exposed surface of the silicon-on-insulator substrate in one side of the patterned etching protection layer;
(d) etching, by using the patterned etching protection layer and the resist mask as a mask, the exposed surface of the silicon-on-insulator substrate which is not covered with the mask up to an insulating layer of the silicon-on-insulator substrate;
(e) removing the resist mask;
(f) performing crystalline anisotropic etching to etch the rest of the exposed surface of the silicon-on-insulator substrate up to the insulating layer of the silicon-on-insulator substrate by using the patterned etching protection layer as a mask, thereby forming a silicon microscopic structure, surfaces of the silicon microscopic structure having a surface orientation of (111), and a distance between the surfaces of the silicon microscopic structure being sufficiently thin to allow the silicon microscopic structure to act as a quantum well;
(g) forming a pair of tunneling barriers on the surfaces of the silicon microscopic structure;
(h) forming a polysilicon layer on a surface of the silicon-on-insulator substrate including the silicon microscopic structure, and doping an impurity having an identical conductivity with the conductivity of the silicon-on-insulator substrate into the polysilicon layer at a high density;
and
(i) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

8 more elements

A method for producing a quantization functional device, comprising the steps of:

(a) forming an etching protection film on a silicon-on-insulator substrate having a surface orientation of (001);
(b) patterning the etching protection film into a rectangular shape in one of a parallel direction and a perpendicular direction to a <110>
crystal orientation of the silicon-on-insulator substrate;
(c) etching an exposed surface of the silicon-on-insulator substrate, on one side of the patterned etching protection layer the silicon-on-insulator substrate being etched up to an insulating layer of the silicon-on-insulator substrate, and on the other side up to a predetermined depth between the insulator layer and the surface of the silicon-on-insulator substrate;
(d) performing crystalline anisotropic etching to etch the rest of the exposed surface of the silicon-on-insulator substrate up to the insulating layer of the silicon-on-insulator substrate by using the patterned etching protection layer as a mask, thereby forming a silicon microscopic structure, surfaces of the silicon microscopic structure having a surface orientation of (111), and a distance between the surfaces of the silicon microscopic structure being sufficiently thin to allow the silicon microscopic structure to act as a quantum well;
(e) forming a pair of tunneling barriers on the surfaces of the silicon microscopic structure;
(f) forming a polysilicon layer on a surface of the silicon-on-insulator substrate including the silicon microscopic structure, and doping an impurity having an identical conductivity with the conductivity of the silicon-on-insulator substrate into the polysilicon layer at a high density;
and
(g) patterning the polysilicon layer into a first electrode and a second electrode sandwiching the pair of tunneling barriers.

6 more elements

Dependencies are inferred from the claim text.