Patent US2024615A successfully refreshed from Google Patents.
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EP0588371A2
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Semiconductor dynamic sensor having a thin thickness structure and its production method
Assignee: Denso Corp
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Filing: 1993-09-20
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Granted: —
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Expires: 2013-09-20
Abstract
Abstract It is intended to provide an etching method for semiconductor devices in which the etching depth or the thickness of a thin thickness portion (5-8) can be precisely controlled. According to experiment results, when a P-type substrate in which an N-type epitaxial layer is formed is immersed in an etching solution such as KOH or the like, and a voltage for reverse bias of PN junction is applied between an electrode plate opposing the substrate and the epitaxial layer to perform electrochemical etching, it has been found that the distance from the PN junction plane to the etching stop position is approximately equal to a depletion layer width at the substrate side of the PN junction portion. Namely, the etching stops at the forward end of the depletion layer. Therefore, the junction depletion layer width at the substrate side is controlled to be a size obtained by subtracting a necessary depth for etching from a thickness of the semiconductor substrate except for the semiconductor layer, so that the etching depth or the thickness of the thin thickness portion remaining after etching can be precisely controlled.
Inventors
- 👤 Tsuyoshi Fukada
- 👤 Yoshimi Yoshino
- 👤 Hiroshige Sugito
- 👤 Minekazu Sakai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 04:43
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/0802; G01P15/12; G01P15/123; G01P15/124; H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/613; Y; Y10; Y10S; Y10S438/00; Y10S438/914; Y10S438/924
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
123 words
A production method for semiconductor dynamic sensors comprising following steps: a step in which a semiconductor member in which a first conductive type semiconductor portion and a second conductive type semiconductor portion form a PN junction is immersed in an etching solution, and said second conductive type semiconductor portion is subjected to electrochemical etching so as to form a thin thickness shaped distortion-causing portion, and a step in which the thickness of said distortion-causing portion is set to be a thickness in which in addition to a thickness of said first conductive type semiconductor portion, a width of a depletion layer, which extends from said PN junction to the side of said second conductive type semiconductor portion during said electrochemical etching, is estimated.
Claim 2
Dependent Claim
43 words
The production method for semiconductor dynamic sensors according to claim 1 further comprising a step in which said depletion layer width is controlled by the magnitude of the voltage to be applied to said first conductive type semiconductor portion during said electrochemical etching.
Claim 3
Dependent Claim
52 words
The production method for semiconductor dynamic sensors according to claim 2 wherein said step of controlling the depletion layer width is a step in which a voltage larger than a maximum rated voltage in the actual use of the semiconductor dynamic sensor is used as said application voltage during said electrochemical etching.
Claim 4
Dependent Claim
216 words
A production method for semiconductor dynamic sensors comprising following steps: a step of preparing a wafer in which a monocrystal semiconductor layer of the first conductive type of a predetermined thickness is formed on a monocrystal semiconductor substrate of the second conductive type; a step of forming a semiconductor distortion detecting means in the monocrystal semiconductor layer; a step of forming a thin thickness portion having a thickness T by immersing the wafer in an etching solution to oppose said monocrystal semiconductor substrate of the second conductive type to an electrode, and applying a voltage between said monocrystal semiconductor layer of the first conductive type and said electrode to perform electrochemical etching of said monocrystal semiconductor substrate of the second conductive type; and a first setting step of setting said predetermined thickness W of said monocrystal semiconductor layer of the first conductive type using W = T - (2Kε(Vc +V₀) / (qNb(1 + Nb/Ne))) 1/2 provided that the dielectric constant of the monocrystal semiconductor is K, the vacuum dielectric constant is ε, the application voltage during the electrochemical etching is Vc, the barrier voltage at 0 bias is V₀, the electric charge amount of electron is q, the impurity concentration of said semiconductor substrate is Nb, and the impurity concentration in said semiconductor layer is Ne.
Claim 5
Dependent Claim
39 words
The production method for semiconductor dynamic sensors according to claim 4 wherein said step of forming the semiconductor distortion detecting means is a step in which a second conductive type diffusion layer is formed in said monocrystal semiconductor layer.
Claim 6
Dependent Claim
73 words
The production method for semiconductor dynamic sensors according to claim 5 wherein said step of setting the thickness of the monocrystal semiconductor layer includes a second setting step in which the depletion layer which extends from the PN junction between said diffusion layer and said monocrystal semiconductor layer to the side of said monocrystal semiconductor layer is suppressed to arrive at said semiconductor substrate during the actual use of the semiconductor dynamic sensor.
Claim 7
Dependent Claim
31 words
The production method for semiconductor dynamic sensors according to claim 6 wherein said second setting step is a step in which the impurity concentration in said monocrystal semiconductor layer is controlled.
Claim 8
Dependent Claim
77 words
The production method for semiconductor dynamic sensors according to claim 7 wherein the impurity concentration Ne in said monocrystal semiconductor layer is set to be a concentration which is higher than 2Kε(Vcc + V₀) / (q(w - d)²) provided that Vcc is the maximum rated voltage which is applied between said diffusion layer and said monocrystal semiconductor layer during the actual use of the semiconductor dynamic sensor, and d is the diffusion depth of said diffusion layer.
Claim 9
Dependent Claim
38 words
The production method for semiconductor dynamic sensors according to claim 4 wherein the voltage Vc applied during said electrochemical etching is made larger than the maximum rated voltage Vcc during the actual use of the semiconductor dynamic sensor.
Claim 10
Dependent Claim
147 words
An etching method for semiconductor devices in which a semiconductor member in which a first conductive type monocrystal semiconductor portion and a second conductive type monocrystal semiconductor portion form a PN junction is immersed in an etching solution to allow said second conductive type monocrystal semiconductor portion to oppose an electrode, a voltage is applied between said first conductive type monocrystal semiconductor portion and said electrode to perform electrochemical etching of said second conductive type semiconductor portion, and said etching is stopped at said PN junction portion, wherein the etching method for semiconductor devices is characterized in that a depletion layer width of said PN junction portion which extends to the side of said second conductive type monocrystal semiconductor portion is controlled to be a size in which a necessary depth for said etching is subtracted from a thickness of said second conductive type monocrystal semiconductor portion.
Claim 11
Dependent Claim
187 words
A production method for semiconductor distortion sensors characterized in that a fist conductive type epitaxial layer is formed to have a predetermined thickness on the surface at the first main face side of a second conductive type semiconductor substrate, a second conductive type piezoresistance region is formed at a predetermined region in said epitaxial layer, an etching planned region at the second main face of said semiconductor substrate is exposed, said semiconductor substrate is immersed in an etching solution, and said epitaxial layer is protected from said etching solution, a predetermined etching voltage is applied between an electrode opposing the second main face of said semiconductor substrate and said epitaxial layer so as to perform etching of said etching planned region, thereby a thin thickness distortion-causing portion, which comprises a coating region comprising a predetermined thickness of said semiconductor substrate and the epitaxial layer having its bottom face coated with said coating region, is formed, and said etching voltage is used to make a PN junction depletion layer width extending to the side of said semiconductor substrate to be equal to the thickness of said coating region.
Claim 12
Dependent Claim
61 words
The production method for semiconductor distortion sensors according to claim 11 wherein said etching voltage is used to make the PN junction depletion layer width extending to the side of said semiconductor substrate to be larger than a PN junction depletion layer width extending to the side of said semiconductor substrate in the case of application of the maximum rated voltage.
Claim 13
Dependent Claim
51 words
The production method for semiconductor distortion sensors according to claim 11 wherein said etching voltage is changed with respect to each of wafers formed in the same semiconductor production steps, thereby plural types of semiconductor distortion sensors which are different in the thickness of said thin thickness distortion-causing portion are produced.
Claim 14
Dependent Claim
243 words
A thin type semiconductor dynamic sensor which is provided with a thin thickness distortion-causing portion composed of a first conductive type monocrystal semiconductor in which at least one end is supported by a semiconductor substrate and its thickness is not more than 15 µm, and a piezoresistance region portion which is formed at the surface portion of said thin thickness distortion-causing portion and is composed of a second conductive type semiconductor having an impurity concentration of a concentration which is higher by not less than one digit than that of said thin thickness distortion-causing portion, in which a predetermined rated voltage is applied between one input end of said piezoresistance region portion and said thin thickness distortion-causing portion and the other input end of said piezoresistance region portion so as to detect a change in the resistance value of said piezoresistance region portion, wherein the semiconductor dynamic sensor is characterized in that said thin thickness distortion-causing portion has the impurity concentration of a concentration which is higher than 2Kε(Vcc+V₀)/q(W-d)² provided that K is the dielectric constant of said thin thickness distortion-causing portion and said piezoresistance region portion, ε is the vacuum dielectric constant, Vcc is said rated voltage, V₀ is the barrier voltage between said thin thickness distortion-causing portion and said piezoresistance region at 0 bias, q is the electric charge amount of electron, W is the thickness of the thin thickness distortion-causing portion, and d is the depth of said piezoresistance region.
Claim 15
Dependent Claim
142 words
A semiconductor dynamic sensor which is provided with a thin thickness distortion-causing portion composed of a first conductive type monocrystal semiconductor in which at least one end is supported by a semiconductor substrate, and a piezoresistance region portion which is formed at the surface portion of said thin thickness distortion-causing portion and is composed of a second conductive type semiconductor, in which a predetermined rated voltage is applied between one input end of said piezoresistance region portion and said thin thickness distortion-causing portion and the other input end of said piezoresistance region portion so as to detect a change in the resistance value of said piezoresistance region portion, wherein the semiconductor dynamic sensor is characterized in that a first conductive type depletion layer stopper region of a high concentration is arranged at the back face portion of said thin thickness distortion-causing portion.
Claim 16
Dependent Claim
132 words
A semiconductor distortion sensor which is provided with a second conductive type semiconductor substrate, a first conductive type surface layer region which is formed at the surface portion of the first main face side of said semiconductor substrate to have a predetermined thickness and has a second conductive type piezoresistance region at the surface portion, and a thin thickness distortion-causing portion which is formed by electrochemical etching from the second main face side of said semiconductor substrate and contains said surface layer region, wherein the semiconductor distortion sensor is characterized in that said thin thickness distortion-causing portion is composed of said surface layer region of a predetermined thickness, and has a coating region which coats the bottom face of said surface layer region and is exposed to said second main face side.
Claim 17
Dependent Claim
54 words
The semiconductor distortion sensor according to claim 16 wherein the thickness of the coating region is larger than a width of a junction depletion layer which is formed between said surface layer region and said semiconductor substrate during the application of the maximum rated voltage, and extends to the side of said semiconductor substrate.
References Cited (Backward Citations)
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