JPH0685288A - Manufacture of vibration-type transducer - Google Patents

Abstract

PURPOSE:To improve reliability without causing a vibration beam from being adhered to the wall surface at a shell side of a vacuum chamber by providing an inclined side wall surface part so that the longer side surface of the vibration beam is in linear contact without causing the vibration beam to be adhered to the wall surface at the shell side of the vacuum chamber while being provided on the shell sidewall surface of the vacuum chamber. CONSTITUTION:A first epitaxial layer 204 consisting of a high-purity P-type silicon which is subjected to etching easily is subjected to selective epitaxial growth at a part corresponding to the lower half of a vacuum chamber 5. A second epitaxial layer 205 corresponding to a vibration beam 3 is subjected to selective epitaxial growth so that a required part 202 is blocked on the surface of the first epitaxial growth layer 204 by a high-purity P-type silicon which cannot be etched easily. A third epitaxial layer 206 corresponding to the upper half of the vacuum chamber 5 is subjected to selective epitaxial growth on the surface of the second epitaxial layer 205 by a high-purity P-type silicon which is subjected to etching easily. An inclined side wall surface part 11 can be constituted on the surface of the third epitaxial layer 206.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not adhere to the shell side wall surface of the vacuum chamber even if the vibrating beam comes into contact with the shell wall surface of the vacuum chamber due to disturbance such as impact or buckling. The present invention relates to a method for manufacturing a highly reliable vibrating transducer which is completely restored.

[0002]

2. Description of the Related Art FIG. 10 is an explanatory view of a main part of a conventional example which has been generally used. For example, Japanese Patent Application No. 62-166176 filed by the applicant of the present application, entitled "Vibration Type Transducer" Manufacturing Method ", filed on July 2, 1987. 11 is a sectional view taken along line AA of FIG.

In the figure, 1 is a semiconductor single crystal substrate, 2
Is a measuring diaphragm which is provided on the semiconductor substrate 1 and receives the measuring pressure Pm. Reference numeral 3 is a strain detection sensor embedded in the measurement diaphragm 2, and a vibrating beam 3 is used. Reference numeral 4 denotes a shell made of a semiconductor epitaxial growth layer for sealing, which seals the vibrating beam 3 in the measurement diaphragm 2.
A vacuum chamber 5 is provided around the vibrating beam 3 and between the vibrating beam 3 and the measurement diaphragm 2 and the shell 4. The vibrating beam 3 is oscillated by the natural vibration of the vibrating beam 3 by the magnetic field of the permanent magnet (not shown) and the closed loop self-excited oscillation circuit (not shown) connected to the vibrating beam 3. It is configured.

In the above configuration, the measuring diaphragm 2
When the measurement pressure Pm is applied to the, the axial force of the vibrating beam 3 changes,
Since the natural frequency changes, the measurement pressure Pm can be measured by changing the oscillation frequency.

12 to 17 are examples of manufacturing explanatory diagrams of the conventional example of FIG. 10, which are Japanese Patent Application No. 63-
No. 86946, titled "Method for manufacturing vibrating transducer", which is an improved version filed on April 8, 1988.

12 to 17 will be described below. (1) As shown in FIG. 12, a silicon oxide or silicon nitride film 101 is formed on a substrate 1 cut into an n-type silicon (100) plane. The required portion 102 of the film 101 is removed by photolithography. (2) As shown in FIG. 13, hydrogen (H ₂ ) at 1050 ° C.
Etching is carried out with hydrogen chloride in the atmosphere to etch a required portion 102 of the substrate 1 and undercut the film 101 to form a recess 103. It should be noted that, instead of hydrogen chloride, high temperature steam, oxygen is used, or 40 ° C to
Anisotropic etching with an alkaline solution at 130 ° C. may be used.

(3) As shown in FIG. 14, in a hydrogen (H ₂ ) atmosphere at 1050 ° C., hydrogen chloride gas is mixed with a source gas to perform a selective epitaxial growth method. That is, the first epitaxial layer 104 corresponding to the lower half of the vacuum chamber 5 is made of P-type silicon having a boron concentration of 10 ¹⁸ cm ^−3.
Is selectively epitaxially grown. A second epitaxial layer 105 corresponding to the vibrating beam 3 is selectively epitaxially grown on the surface of the first epitaxial layer 104 by using P-type silicon having a boron concentration of 3 × 10 ¹⁹ cm ⁻³ so as to block the required portion 102. A third epitaxial layer 106 corresponding to the upper half of the vacuum chamber 5 is selectively epitaxially grown on the surface of the second epitaxial layer 105 with P-type silicon having a boron concentration of 10 ¹⁸ cm ^-3 . A fourth epitaxial layer 107 corresponding to the shell 4 is selectively epitaxially grown on the surface of the third epitaxial layer 106 using P-type silicon having a boron concentration of 3 × 10 ¹⁹ cm ⁻³ .

(4) As shown in FIG. 15, the silicon oxide or silicon nitride film 101 is removed by etching with hydrofluoric acid (HF), and an etching injection port 108 is provided. (5) As shown in FIG. 16, a positive pulse or a positive voltage is applied to the substrate 1 with respect to the fourth layer, and an alkali solution is injected from the etching injection port 108 to form the first epitaxial layer 104 and the third epitaxial layer 104. The epitaxial layer 106 is removed by selective etching. The difference in the etching action between the second epitaxial layer 105 and the first epitaxial layer 104 or the third epitaxial layer 106 is that when the boron concentration is 3 × 10 ¹⁹ cm ⁻³ or more, the etching action is suppressed. It depends on what happens.

(6) As shown in FIG. 17, n-type silicon is epitaxially grown in hydrogen (H ₂ ) at 1050 ° C. to form an epitaxial growth layer 111 on the outer surfaces of the substrate 1 and the fourth epitaxial layer 107. The etching inlet 108 is closed. In this process, the etching injection port 108 is closed by thermal oxidation. Polysilicon is deposited on the portion of the etching inlet 108 by the CVD method or the sputtering method, and the etching inlet 108 is closed. The etching injection port 108 is filled by the silicon epitaxial method by the vacuum evaporation method. The etching inlet 108 may be filled with an insulating material such as glass (SiO ₂ ), nitride, or alumina by the CVD method, the sputtering method, or the vapor deposition method.

[0010]

However, in such a device, since the surface of the vibrating beam 3 is a mirror surface and has a small surface roughness and is active, it is likely to be disturbed by external disturbance such as impact or buckling due to a large compressive force. When the vibrating beam 3 comes into contact with the wall surface of the vacuum chamber 5, it may adhere to the wall surface of the vacuum chamber 5 as it is. To prevent this, the vacuum chamber 5
It is conceivable that the side wall surface on the side of the substrate 1 is an inclined surface, and moreover, the side surface in the longitudinal direction of the vibrating beam 3 is brought into contact with the inclined surface to make line contact. However, even with such a configuration, it is not possible to solve the problem that the vibrating beam 3 adheres to the shell side wall surface of the vacuum chamber 5. This is because the planar portion of the side wall surface of the shell of the vacuum chamber 5 is formed by stacking the axially grown layers, and thus is wider than the vibrating beam 3.

The present invention solves this problem. The object of the present invention is that even if the vibrating beam comes into contact with the shell wall surface of the vacuum chamber due to disturbance such as impact or buckling, it does not adhere to the shell side wall surface of the vacuum chamber and is completely removed if the disturbance is removed. It is to provide a highly reliable method of manufacturing a vibrating transducer.

[0012]

To achieve this object, the present invention provides a vibrating beam provided on a silicon single crystal substrate, and the vibrating beam so that a gap is maintained around the vibrating beam. A method of manufacturing a vibrating transducer comprising: a shell made of a silicon material that surrounds the substrate and a vacuum chamber; an exciting unit that excites the vibrating beam; and an exciting detecting unit that detects vibration of the vibrating beam. A method of manufacturing a vibration type transducer comprising the following steps. (A) A step of forming a silicon oxide or silicon nitride film on a substrate cut on the n-type silicon (100) surface. (B) A step of removing a required portion of the film by photolithography. (C) A step of etching the desired portion of the substrate to undercut the film to form a recess. (D) A step of selectively epitaxially growing a first epitaxial layer made of high-concentration P-type silicon that is easily etched in a portion corresponding to the lower half of the vacuum chamber. (E) A step of selectively epitaxially growing a second epitaxial layer corresponding to the vibrating beam on the surface of the first epitaxial layer with a high concentration of P-type silicon that is difficult to be etched so as to block the required portion. (F) A step of selectively epitaxially growing a third epitaxial layer corresponding to the upper half of the vacuum chamber on the surface of the second epitaxial layer with high-concentration P-type silicon that is easily etched. (G) A step of vapor-phase etching the surface of the third epitaxial layer so that an inclined side wall surface portion can be formed. (H) A step of selectively epitaxially growing a fourth epitaxial layer corresponding to the shell on the surface of the third epitaxial layer with high-concentration P-type silicon that is difficult to be etched. (I) A step of etching and removing the silicon oxide or silicon nitride film to provide an etching injection port. (J) A positive pulse or a positive voltage is applied to the substrate with respect to the fourth layer, and an etching solution is injected from the etching injection port to select the first epitaxial layer and the third epitaxial layer. Step of etching and removing. (K) A step of performing epitaxial growth of n-type silicon to form an epitaxial growth layer on the outer surfaces of the substrate and the fourth epitaxial layer, and closing the etching injection port.

[0013]

In the above manufacturing method, n-type silicon (10
A film of silicon oxide or silicon nitride is formed on the substrate cut in the 0) plane. The required parts of the film are removed by photolithography. The required portion of the substrate is etched to undercut the film to form a recess. In the part corresponding to the lower half of the vacuum chamber,
A first epitaxial layer made of high-concentration P-type silicon that is easily etched is selectively epitaxially grown. Due to the high concentration of P-type silicon that is difficult to etch,
A second epitaxial layer corresponding to the vibrating beam is selectively epitaxially grown on the surface of the first epitaxial layer so as to block the required portion. A third epitaxial layer corresponding to the upper half of the vacuum chamber is selectively epitaxially grown on the surface of the second epitaxial layer by high-concentration P-type silicon which is easily etched. The surface of the third epitaxial layer is vapor-phase etched so that an inclined side wall surface portion can be formed. A fourth epitaxial layer corresponding to the shell is selectively epitaxially grown on the surface of the third epitaxial layer with high-concentration P-type silicon that is difficult to be etched. The silicon oxide or silicon nitride film is etched and removed to provide an etching injection port. A positive pulse or a positive voltage is applied to the substrate with respect to the fourth layer, an etchant is injected from the etching inlet, and the first epitaxial layer and the third epitaxial layer are selectively etched. Remove. Epitaxial growth of n-type silicon is performed, an epitaxial growth layer is formed on the outer surfaces of the substrate and the fourth epitaxial layer, and the etching inlet is closed. Hereinafter, detailed description will be given based on examples.

[0014]

【Example】

1 to 8 are explanatory views of a manufacturing method according to an embodiment of the present invention. In the figure, the same symbols as those in FIG. 10 represent the same functions. (1) As shown in FIG. 1, a silicon oxide or silicon nitride film 201 is formed on a substrate 1 cut into an n-type silicon (100) plane. The required portion 202 of the film 201 is removed by photolithography. (2) As shown in FIG. 2, etching is performed with hydrogen chloride in a hydrogen (H ₂ ) atmosphere at 1050 ° C., a required portion 202 is etched in the substrate 1 to undercut the film 201, and the recess 203 is formed. Form. It should be noted that, instead of hydrogen chloride, high temperature steam, oxygen is used, or 40 ° C to
Anisotropic etching with an alkaline solution at 130 ° C. may be used.

(3) As shown in FIG. 3, hydrogen chloride gas is mixed with a source gas in a hydrogen (H ₂ ) atmosphere to perform a selective epitaxial growth method. That is, at a temperature of 1050 ° C., P-type silicon having a boron concentration of 10 ¹⁸ cm ⁻³ corresponds to the first half of the lower half of the vacuum chamber 5.
The epitaxial layer 204 is selectively epitaxially grown. Boron concentration 3 × 10 ¹⁹ cm at a temperature of 1050 ° C.
^-3 P-type silicon, the first epitaxial layer 204
A second epitaxial layer 205 corresponding to the vibrating beam 3 is selectively epitaxially grown on the surface of the so as to cover the required portion 202. A third epitaxial layer 206 corresponding to the upper half of the vacuum chamber 5 is selectively epitaxially grown on the surface of the second epitaxial layer 205 with P-type silicon having a boron concentration of 10 ¹⁸ cm ^-3 .

(4) As shown in FIG. 4, the surface of the third epitaxial layer 206 is vapor-phase etched with hydrogen chloride gas so that the inclined side wall surface portion 11 can be formed. (5) As shown in FIG. 5, the boron concentration is 3 × 10 ¹⁹ cm.
^-3 P-type silicon, the third epitaxial layer 206
The fourth epitaxial layer 2 corresponding to the shell 4 on the surface of the
07 is selectively epitaxially grown. (6) As shown in FIG. 6, the silicon oxide or silicon nitride film 201 is removed by etching with hydrofluoric acid (HF) to provide an etching injection port 208.

(7) As shown in FIG. 7, a positive pulse or a positive voltage is applied to the substrate 1 with respect to the fourth layer, and an alkaline solution is injected from the etching injection port 208 to form the first epitaxial layer 204. Then, the third epitaxial layer 206 is removed by selective etching. Second epitaxial layer 20
The reason why there is a difference in the etching action between 5 and the first epitaxial layer 204 or the third epitaxial layer 206 is that when the boron concentration is 3 × 10 ¹⁹ cm ⁻³ or more, the etching action is suppressed. (8) As shown in FIG. 8, n-type silicon is epitaxially grown in hydrogen (H ₂ ) at 1050 ° C.
An epitaxial growth layer 209 is formed on the outer surface of the fourth epitaxial layer 207, and the etching injection port 208 is closed.

In the above manufacturing method, the silicon oxide or silicon nitride film 201 is formed on the substrate 1 cut into the n-type silicon (100) surface. Membrane 20
The required portion 202 of No. 1 is removed by photolithography. The required portion 202 of the substrate 1 is etched to form the film 20.
Undercut 1 to form a recess. In the portion corresponding to the lower half of the vacuum chamber 5, the first epitaxial layer 204 made of highly-concentrated P-type silicon that is easily etched
Are selectively epitaxially grown. A second epitaxial layer 205 corresponding to the vibrating beam 3 is selectively epitaxially grown on the surface of the first epitaxial layer 204 with high-concentration P-type silicon that is difficult to be etched so as to cover a required portion 202. A third epitaxial layer 206 corresponding to the upper half of the vacuum chamber 5 is selectively epitaxially grown on the surface of the second epitaxial layer 205 by high-concentration P-type silicon that is easily etched. The surface of the third epitaxial layer 206 is vapor-phase etched so that the inclined side wall surface portion 11 can be formed. The third epitaxial layer 2 is made of high-concentration P-type silicon that is difficult to etch.
A fourth epitaxial layer 207 corresponding to the shell 4 is selectively epitaxially grown on the surface of 06. The silicon oxide or silicon nitride film 201 is removed by etching, and an etching injection port 208 is provided. 4th layer 2
07, a positive pulse or a positive voltage is applied to the substrate 1, an etching solution is injected from the etching injection port 208, and the first epitaxial layer 204 and the third epitaxial layer 206 are selectively etched and removed. . By epitaxially growing n-type silicon, an epitaxial growth layer 209 is formed on the outer surfaces of the substrate 1 and the fourth epitaxial layer 207, and the etching injection port 208 is closed.

As a result, when the wall surface of the vacuum chamber 5 is a mirror surface, since the surface roughness is small and active, the vibrating beam 3 is moved toward the shell side of the vacuum chamber 5 due to disturbance such as impact or buckling due to a large compressive force. When it comes into contact with the wall surface, it may adhere to the wall surface of the vacuum chamber 5 as it is, but it is provided on the side wall surface of the shell 4 of the vacuum chamber 5, and the vibrating beam 3 does not adhere to the side wall surface of the shell 4 of the vacuum chamber 5. Since the method for manufacturing the vibrating transducer in which the slanted side wall surface portion 11 configured so that the longitudinal side surfaces of the vibrating beam 3 are in line contact is provided, the vibrating beam 3 is attached to the wall surface of the vacuum chamber 5 on the shell 4 side. The reliability can be improved without causing it.

FIG. 9 is an explanatory view of the essential structure of an example of use of the vibrating beam of the present invention. In the figure, 3 is a vibrating beam. The vibrating beam 3 has two first oscillators 31, both ends of which are fixed to the diaphragm 3 and arranged in parallel with each other, and a second oscillator that mechanically couples antinode portions of the vibration of the first oscillator 31 with each other. And 32. 40 is a magnet 3 for applying a DC magnetic field orthogonal to the vibrating beam 3.
In addition to 0, an AC current is applied to both ends of one of the first oscillators 31 by an input transformer 41 to excite the vibrating beam 3 in a direction orthogonal to the magnetic field and the current by a magnetic induction action. The secondary side of the input transformer 41 is connected to both ends of the one first oscillator 31.

Reference numeral 50 is a vibration detecting means for detecting an electromotive force generated at both ends of the other first vibrator 31. In this case, the output transformer 51 and the amplifier 52 are used.
The primary side of the output transformer 51 is connected to both ends of the other first oscillator 31, the secondary side is connected to the output terminal 53 via the amplifier 52, and the output transformer 51 is branched and input.
Is connected to the primary side of the positive feedback self-oscillation circuit. The vibration of the vibrating beam 3 is detected by the vibration detecting means 50 and taken out as an output signal.

[0023]

As described above, according to the present invention, the vibrating beam provided on the silicon single crystal substrate is surrounded by the vibrating beam so that a gap is maintained around the vibrating beam. A method of manufacturing a vibrating transducer comprising a shell made of a silicon material forming a chamber, an exciting means for exciting the vibrating beam, and an exciting detecting means for detecting vibration of the vibrating beam, including the following steps. The manufacturing method of the vibrating transducer is characterized by. (A) A step of forming a silicon oxide or silicon nitride film on a substrate cut on the n-type silicon (100) surface. (B) A step of removing a required portion of the film by photolithography. (C) A step of etching the desired portion of the substrate to undercut the film to form a recess. (D) A step of selectively epitaxially growing a first epitaxial layer made of high-concentration P-type silicon that is easily etched in a portion corresponding to the lower half of the vacuum chamber. (E) A step of selectively epitaxially growing a second epitaxial layer corresponding to the vibrating beam on the surface of the first epitaxial layer with a high concentration of P-type silicon that is difficult to be etched so as to block the required portion. (F) A step of selectively epitaxially growing a third epitaxial layer corresponding to the upper half of the vacuum chamber on the surface of the second epitaxial layer with high-concentration P-type silicon that is easily etched. (G) A step of vapor-phase etching the surface of the third epitaxial layer so that an inclined side wall surface portion can be formed. (H) A step of selectively epitaxially growing a fourth epitaxial layer corresponding to the shell on the surface of the third epitaxial layer with high-concentration P-type silicon that is difficult to be etched. (I) A step of etching and removing the silicon oxide or silicon nitride film to provide an etching injection port. (J) A positive pulse or a positive voltage is applied to the substrate with respect to the fourth layer, and an etching solution is injected from the etching injection port to select the first epitaxial layer and the third epitaxial layer. Step of etching and removing. (K) A step of performing epitaxial growth of n-type silicon to form an epitaxial growth layer on the outer surfaces of the substrate and the fourth epitaxial layer, and closing the etching injection port.

As a result, when the wall surface of the vacuum chamber is a mirror surface,
Since the surface roughness is small and active, if the vibrating beam comes into contact with the side wall surface of the shell of the vacuum chamber due to external disturbance such as impact or buckling due to a large compressive force, it may adhere to the wall surface of the vacuum chamber as it is. Provided on the shell side wall surface of the vacuum chamber,
Since the vibrating beam was not attached to the shell side wall surface of the vacuum chamber, the method of manufacturing the vibrating transducer was adopted in which the slanted side wall surface portion configured so that the long side surface of the vibrating beam is in line contact was adopted. Reliability can be improved without sticking to the shell side wall of the vacuum chamber.

Therefore, according to the present invention, even if the vibrating beam may come into contact with the wall surface of the vacuum chamber due to disturbance such as impact or buckling, if the disturbance is removed without adhering to the shell side wall surface of the vacuum chamber. It is possible to realize a highly reliable method of manufacturing a vibration type transducer.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a patterning process according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an etching process according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an epitaxial growth process of one example of the present invention.

FIG. 4 is an explanatory diagram of an etching process according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an epitaxial growth process of one example of the present invention.

FIG. 6 is a diagram illustrating a film removing process according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of an etching process according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of an epitaxial growth process according to an example of the present invention.

FIG. 9 is an explanatory diagram of a main part configuration of a usage example of the device of the present invention.

FIG. 10 is an explanatory diagram of a configuration of a conventional example that is generally used in the past.

11 is a sectional view taken along line AA of FIG.

FIG. 12 is an explanatory diagram of a patterning process of the conventional example.

FIG. 13 is an explanatory diagram of the etching process of the conventional example.

FIG. 14 is an explanatory diagram of an epitaxial growth process of the conventional example.

FIG. 15 is a drawing for explaining the film removal process of the conventional example.

FIG. 16 is an explanatory diagram of an etching process of the conventional example.

FIG. 17 is an explanatory diagram of an epitaxial growth process of the conventional example of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Measuring diaphragm 3 ... Oscillating beam 4 ... Shell 5 ... Vacuum chamber 11 ... Inclined side wall surface part 30 ... Magnet 31 ... First oscillator 32 ... Second oscillator 40 ... Excitation means 41 ... Input transformer 42 ... Input terminal 50 ... Vibration detecting means 51 ... Output transformer 52 ... Amplifier 53 ... Output terminal 201 ... Film 202 ... Required location 203 ... Recessed portion 204 ... First epitaxial layer 205 ... Second epitaxial layer 206 ... Third epitaxial layer 207 ... Fourth epitaxial layer 208 ... Etching injection port 209 ... Epitaxial growth layer

Claims (1)

[Claims] 1. A vibrating beam provided on a silicon single crystal substrate, and a shell made of a silicon material surrounding the vibrating beam so as to maintain a gap around the vibrating beam and forming a vacuum chamber with the substrate. A method of manufacturing a vibrating transducer, comprising: an exciting unit that excites the vibrating beam; and an exciting detecting unit that detects vibration of the vibrating beam, including the following steps. . (A) A step of forming a silicon oxide or silicon nitride film on a substrate cut on the n-type silicon (100) surface. (B) A step of removing a required portion of the film by photolithography. (C) A step of etching the desired portion of the substrate to undercut the film to form a recess. (D) A step of selectively epitaxially growing a first epitaxial layer made of high-concentration P-type silicon that is easily etched in a portion corresponding to the lower half of the vacuum chamber. (E) A step of selectively epitaxially growing a second epitaxial layer corresponding to the vibrating beam on the surface of the first epitaxial layer with a high concentration of P-type silicon that is difficult to be etched so as to block the required portion. (F) A step of selectively epitaxially growing a third epitaxial layer corresponding to the upper half of the vacuum chamber on the surface of the second epitaxial layer with high-concentration P-type silicon that is easily etched. (G) A step of vapor-phase etching the surface of the third epitaxial layer so that an inclined side wall surface portion can be formed. (H) A step of selectively epitaxially growing a fourth epitaxial layer corresponding to the shell on the surface of the third epitaxial layer with high-concentration P-type silicon that is difficult to be etched. (I) A step of etching and removing the silicon oxide or silicon nitride film to provide an etching injection port. (J) A positive pulse or a positive voltage is applied to the substrate with respect to the fourth layer, and an etching solution is injected from the etching injection port to select the first epitaxial layer and the third epitaxial layer. Step of etching and removing. (K) A step of performing epitaxial growth of n-type silicon to form an epitaxial growth layer on the outer surfaces of the substrate and the fourth epitaxial layer, and closing the etching injection port.