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US 5,844,286 AGranted
Semiconductor acceleration sensor
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorYuji Hase
Life of this patent
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Abstract
A semiconductor acceleration sensor of a single integral type has a semiconductor substrate, a first nitride layer, a first poly-silicon layer, a second nitride layer, a second poly-silicon layer, a third nitride layer and a third poly-silicon layer which are fabricated in order. A movable section is formed in a part of the second poly-silicon layer placed in a cavity enclosed and sealed by the first nitride layer, the first poly-silicon layer, the second nitride layer, the second poly-silicon layer, the third nitride layer and the third poly-silicon layer. A fabrication method of the semiconductor acceleration sensor of a single integral type is also disclosed.
Claims19
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer, is disposed in a cavity, said cavity being enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section spaced movably apart from said first poly-silicon layer which is static.
6 more elements
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer in a cavity enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section;
- and
- wherein a movable electrode is formed at a part of the movable section in the second poly-silicon layer and a fixed electrode is formed at a part of the first poly-silicon layer, a magnitude of acceleration is detected based on a magnitude of change of an electro-static capacitance between the movable electrode and the fixed electrode.
8 more elements
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer in a cavity enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section;
- and
- wherein a movable electrode is formed at a part of the movable section in the second poly-silicon layer, a lower side fixed electrode is formed at a part of the first poly-silicon layer at a position corresponding to the movable electrode, an upper side fixed electrode is formed at a part of the third poly-silicon layer at a position corresponding to the movable electrode, and a magnitude of acceleration applied to the semiconductor acceleration sensor is detected based on a magnitude of change of an electro-static capacitance between the movable electrode and the upper side fixed electrode and between the movable electrode and the lower side fixed electrode.
8 more elements
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer in a cavity enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section,
- wherein a movable electrode is formed at a part of the movable section in the second poly-silicon layer, a lower side fixed electrode is formed at a part of the first poly-silicon layer at a position corresponding to the movable electrode, an upper side fixed electrode is formed at a part of the third poly-silicon layer at a position corresponding to the movable electrode, and wirings are formed in the first poly-silicon layer, the second poly-silicon layer and the third poly-silicon layer by diffusing impurity and connected to the upper side fixed electrode and the lower side fixed electrode, and
- wherein a magnitude of acceleration applied to the semiconductor acceleration device is detected based on a magnitude of change of an electro-static capacitance between the movable electrode and the upper side fixed electrode and between the movable electrode and the lower side fixed electrode.
8 more elements
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer in a cavity enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section,
- wherein a movable electrode is formed at a part of the movable section in the second poly-silicon layer, a fixed electrode is formed in the first poly-silicon layer, a driving electrode separated from the fixed electrode in the first poly-silicon layer in distance is formed in the first poly-silicon layer, and
- wherein the semiconductor acceleration sensor has a self-checking function and a damage of the movable electrode is detected based on a magnitude of change of an electro-static capacitance between the movable electrode and the fixed electrode generated when a voltage is applied to the driving electrode.
8 more elements
A semiconductor acceleration sensor comprising:
- a semiconductor substrate;
- a first insulating layer formed on a surface of the semiconductor substrate;
- a first poly-silicon layer formed on a surface of the first insulating layer;
- a second insulating layer formed on a surface of the first poly-silicon layer;
- a second poly-silicon layer formed on a surface of the second insulating layer;
- a third insulating layer formed on a surface of the second poly-silicon layer;
- and
- a third poly-silicon layer formed on a surface of the third insulating layer,
- wherein a part of the second poly-silicon layer in a cavity enclosed and sealed by the first insulating layer, the first poly-silicon layer, the second insulating layer, the second poly-silicon layer, the third insulating layer, and the third poly-silicon layer, and said part of the second poly-silicon layer is formed as a movable section,
- wherein a movable electrode is formed at a part of the movable section in the second poly-silicon layer, an impurity diffusion resistance section is formed by diffusing impurity in a part of the movable section, a fixed electrode is formed in the first poly-silicon layer, and
- wherein the semiconductor acceleration sensor has a self-checking function and a damage of the movable electrode is detected by measuring a magnitude of change of a resistance value of the impurity diffusion resistance section when a voltage is applied to the fixed electrode.
8 more elements
Dependencies are inferred from the claim text.