Acceleration sensor element and method of its manufacture
First Claim
1. A flexure transducer element which is used in an acceleration sensor for sensing an acceleration applied thereto comprises(1) a frame having an upper surface and a lower surface, (2) a sheet member which has a plurality of flexible parts and a center part, each flexible part extending between at least a portion of an inner edge of the frame and the center part and being integrally connected to them, (3) a weight which has a neck part integrally connected to the center part of the sheet member and which is hung from the sheet member through the neck part, and (4) a support member which supports the lower surface of the frame and of which inward side surface of said support member faces to a side surface of the weight through a first space therebetween, the sheet member further includes a weight upper part which is located on the upper surface of the weight, and the upper weight part is integral with the weight, a second space which is continuous with the first space is defined between each flexible part of the sheet member and the weight, a third space is defined between the frame and the sheet member and/or through the sheet member, the frame and the sheet member are connected to each other and the sheet member and the weight are connected to each other in such a manner that, when the acceleration is applied to the element, at least two flexible parts are elastically deformed so that the weight is displaced relatively to the frame, the weight and the support member are formed of a semiconductor substrate, the second space is formed by removing a sacrificial layer which is provided in the semiconductor substrate, and the frame and the sheet member comprises an epitaxial layer provided on the semiconductor substrate.
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Accused Products
Abstract
A flexure transducer element used in an acceleration sensor for sensing an acceleration applied thereto and the method of making the same. The flexure transducer element comprises a frame, a sheet member, a weight, and a support member.
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Citations
37 Claims
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1. A flexure transducer element which is used in an acceleration sensor for sensing an acceleration applied thereto comprises
(1) a frame having an upper surface and a lower surface, (2) a sheet member which has a plurality of flexible parts and a center part, each flexible part extending between at least a portion of an inner edge of the frame and the center part and being integrally connected to them, (3) a weight which has a neck part integrally connected to the center part of the sheet member and which is hung from the sheet member through the neck part, and (4) a support member which supports the lower surface of the frame and of which inward side surface of said support member faces to a side surface of the weight through a first space therebetween, the sheet member further includes a weight upper part which is located on the upper surface of the weight, and the upper weight part is integral with the weight, a second space which is continuous with the first space is defined between each flexible part of the sheet member and the weight, a third space is defined between the frame and the sheet member and/or through the sheet member, the frame and the sheet member are connected to each other and the sheet member and the weight are connected to each other in such a manner that, when the acceleration is applied to the element, at least two flexible parts are elastically deformed so that the weight is displaced relatively to the frame, the weight and the support member are formed of a semiconductor substrate, the second space is formed by removing a sacrificial layer which is provided in the semiconductor substrate, and the frame and the sheet member comprises an epitaxial layer provided on the semiconductor substrate.
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4. A method for producing a flexure transducer element used in an acceleration sensor which senses an acceleration applied thereto, in which method, the element comprises
a flexure transducer element which is used as an acceleration sensor for sensing an acceleration applied thereto comprises (A) a frame having an upper surface and a lower surface, (B) a sheet member which has a plurality of flexible parts and a center part, each flexible part extending between at least a portion of an inner edge of the frame and the center part and being integrally connected to them, (C) a weight which has a neck part integrally connected to the center part of the sheet member and which is hung from the sheet member through the neck part, and (D) a support member which supports the lower surface of the frame and of which inward side surface of said support member faces to a side surface of the weight through a first space therebetween, a second space which is continuous with the first space is defined between each flexible part of the sheet member and the weight, a third space is defined between the frame and the sheet member and the weight, the frame and the sheet member are connected to each other and the sheet member and the weight are connected to each other in such a manner that, when the acceleration is applied to the element, at least two flexible parts are elastically deformed so that the weight is displaced relatively to the frame, the weight and the support member are formed of a semiconductor substrate having a first main surface and a second main surface which are opposing to each other, the second space is formed by removing a sacrificial layer which is provided in the semiconductor substrate, and the frame and the sheet member comprises an epitaxial layer provided on the semiconductor substrate, the method comprising: -
(1) forming in the first main surface of the semiconductor substrate for the formation of the weight having the neck part and the support member, the sacrificial layer which extends outward from a portion of an outer periphery of the center part of the first main surface which center part is to constitute the neck part, (2) the epitaxial layer is formed on the first main surface after (1), and (3) after (2), carrying out the following (3-a) to (3-c);
(3-a) removing a portion of the substrate from the second main surface of the substrate using etching so that the side surface of the weight and the support member are formed, the support member including the side surface opposing to the side surface of the weight through the first space, (3-b) forming the third space through the epitaxial layer by removing a portion thereof using etching so that at least a portion of the rest of the epitaxial layer is formed into the frame and the sheet member including the center part and a plurality of the flexible parts which finally becomes able to elastically deform, and (3-c) removing the sacrificial layer through wet etching so that the second space and the neck part of the weight are formed, whereby the weight is formed, in any one of the following orders (i) to (iv);
(i) (3-a)→
(3-b)→
(3-c),(ii) (3-a)→
(3-c)→
(3-b),(iii) (3-b)→
(3-a)→
(3-c), and(iv) (3-b)→
(3-c)→
(3-a).- View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification