JP2011082483A - Diaphragm element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm element that reduces a dimension in creepage surface direction of a cavity provided in a silicon substrate, and miniaturizes the whole element in the creepage surface direction. <P>SOLUTION: A diaphragm element 100 includes a silicon substrate 110 which includes a cavity 111, a first main surface side insulating layer 120 which blockades the cavity 111, and a heating resistor 160 which is buried in the first main surface side insulating layer 120. Then, the silicon substrate 110 is configured so that a first opening edge 111bf in the side of a first principal surface 110b of the cavity 111 and a second opening edge 111c in the side of a second principal surface 110c overlaps each other on the same position EM 1 in the creepage surface direction. Moreover, an inner periphery surface 111n which constitutes the cavity 111 is located outside in the creepage surface direction, as compared with a predetermined virtual inner periphery surface FN. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a silicon substrate having a cavity portion penetrating in the thickness direction, an insulating layer laminated on the silicon substrate so as to close the cavity portion, and embedded in a portion of the insulating layer facing the cavity portion. The present invention relates to a diaphragm element including the resistance heating element, and a method for manufacturing the diaphragm element.

  Conventionally, a diaphragm element having a diaphragm structure with a built-in heating resistor is known. Specifically, a silicon substrate having a cavity portion penetrating in the thickness direction, an insulating layer laminated on the silicon substrate so as to close the cavity portion, and a portion of the insulating layer facing the cavity portion. There is a diaphragm element including an embedded resistance heating element. For example, Patent Document 1 discloses such a diaphragm element. In the conventional diaphragm element, the cavity provided in the silicon substrate opens larger on the opposite side than the insulating layer side (heating resistor side), for example, as shown in FIG. Furthermore, the cross section was trapezoidal.

JP-A-11-194043

  However, the dimension of the cavity in the creeping direction of the cavity is larger than the dimension in the creeping direction of the diaphragm (direction along the main surface of the silicon substrate). In order to ensure the strength of the diaphragm element, it is necessary to secure the volume of the portion of the silicon substrate that forms the periphery of the cavity, so that when the dimension of the creeping direction of the cavity increases, the creeping direction of the silicon substrate The dimensions of these tend to be large. For this reason, it was difficult to reduce the size of the diaphragm element in the creeping direction.

  The present invention has been made in view of the present situation, and an object of the present invention is to provide a diaphragm element that can reduce the dimension in the creeping direction of the cavity provided in the silicon substrate and can reduce the entire element in the creeping direction. .

  The solution is made of silicon and has a plate shape having a first main surface and a second main surface forming the back surface, and penetrates between the first main surface and the second main surface in the plate thickness direction. A silicon substrate having a cavity, wherein the first principal surface and the second principal surface have a {100} plane orientation, and the silicon substrate has a cavity on the first principal surface and the cavity. A diaphragm element comprising: an insulating layer formed in a closed configuration, and a plurality of layers stacked; and a heating resistor embedded in a cavity facing portion facing the cavity of the insulating layer and generating heat when energized When the silicon substrate is viewed by overlapping the first opening edge on the first main surface side and the second opening edge on the second main surface side of the hollow portion in the plate thickness direction. The second opening edge overlaps the first opening edge or is located on the inner side of the first opening edge. And a drum-shaped virtual inner peripheral surface having a {111} plane and projecting inward from the first opening edge and the second opening edge as a starting point. This is a diaphragm element having an inner peripheral surface that actually configures the cavity when positioned virtually outside the virtual inner peripheral surface.

  In the diaphragm element of the present invention, when the silicon substrate is viewed by overlapping the first opening edge on the first main surface side and the second opening edge on the second main surface side of the cavity portion in the thickness direction, The second opening edge is configured to be located within the first opening edge, that is, overlaps with or is located inside the first opening edge. For this reason, the dimension (dimension in the radial direction of the cavity) in the creeping direction (direction along the first main surface) of the cavity can be made smaller than that of the conventional trapezoidal cavity. By reducing the dimension in the creeping direction of the cavity, even if the dimension in the creeping direction of the silicon substrate is reduced, the volume of the portion constituting the periphery of the cavity in the silicon substrate can be sufficiently secured. Thus, it is possible to reduce the size of the diaphragm element in the creeping direction while securing the strength of the silicon substrate (diaphragm element).

  Here, starting from the first opening edge and the second opening edge, the surface orientation is {111} plane, and a virtual drum-like inner peripheral surface protruding toward the inside (inside the creeping direction) is assumed. . When the inner peripheral surface that actually constitutes the hollow portion protrudes to the inner side (inner surface in the creeping direction) from the virtual inner peripheral surface, the portion of the silicon substrate that forms the inner peripheral surface (the protruding portion) ), The heat generated by the heating resistor is transmitted and heat escape increases, power consumption for energization control (heating control) by the heating resistor increases, and it is difficult to precisely control the temperature of the heating resistor.

  On the other hand, in the present invention, the silicon substrate is configured such that the inner peripheral surface that actually constitutes the cavity is positioned outside (the outer side in the creeping direction) from the virtual inner peripheral surface. By setting it as such a form, the part which makes | forms this internal peripheral surface among silicon substrates becomes difficult to exert influence on the heat escape of the heat | fever which generate | occur | produced in the heat generating resistor. Therefore, the temperature of the heating resistor can be appropriately controlled.

  The “diaphragm element” only needs to satisfy the above requirements. For example, it may be a diaphragm element having only the above heating resistor, or a physical quantity provided with a sensor unit heated by the above heating resistor. It may be a sensor element or a chemical sensor element. Specifically, examples of the diaphragm element include gas sensor elements such as an air flow sensor element and a NOx sensor element.

Further, the “cavity portion” only needs to satisfy the above requirements. For example, the drum-shaped cavity portion, that is, the inner peripheral surface constituting the cavity portion protrudes toward the inner side (the inner side in the creeping direction). Form, bead-shaped cavity of the abacus, that is, a form in which the inner peripheral surface constituting the cavity is recessed outward (outside in the creeping direction), or a cylindrical cavity, that is, a cavity It can be set as the form which the dimension of an internal peripheral surface does not change to a plate | board thickness direction.
In addition, although the “insulating layer” is stacked on the first main surface of the silicon substrate as described above, an insulating layer or the like may be stacked on the second main surface on the back surface. There may be no insulating layer or the like.
The {100} plane refers to the (100) plane or a plane orientation equivalent thereto. The {111} plane indicates the (111) plane or a plane orientation equivalent to this.

  Further, in the diaphragm element, the silicon substrate is configured such that the inner peripheral surface constituting the cavity portion protrudes inward from the first opening edge and the second opening edge. It is preferable to use a diaphragm element.

  In the present invention, the silicon substrate is configured such that the inner peripheral surface constituting the cavity portion protrudes inward (inward in the radial direction of the cavity portion) from the first opening edge and the second opening edge. For this reason, the volume of the peripheral part of a cavity part among silicon substrates rather than the case where the inner peripheral surface which comprises a cavity part is made into the form which dents toward the outer side (a cavity part is a abacus bead shape or a via-barrel form). Therefore, the strength of the silicon substrate can be increased. Therefore, the dimension in the creeping direction of the diaphragm element can be relatively reduced.

  Furthermore, in the diaphragm element, the innermost surface located on the innermost side of the inner peripheral surface constituting the cavity portion is from the first main surface to the plate thickness direction. It is preferable that the diaphragm element has a form separated by more than one third of the thickness of the silicon substrate toward the second main surface side.

  As described above, when the inner peripheral surface constituting the hollow portion protrudes toward the inner side (the inner side in the creeping direction), the heat generated by the heating resistor tends to escape from the protruding portion. . In particular, heat escape tends to occur when the innermost surface of the inner peripheral surface constituting the hollow portion is close to the first main surface. On the other hand, in the present invention, the silicon substrate has an innermost inner peripheral surface constituting the cavity portion, which is 3 minutes from the first main surface toward the second main surface side in the plate thickness direction by 3 minutes. 1 or more away from each other. For this reason, the innermost portion of the silicon substrate is less likely to affect the heat escape of heat generated by the heating resistor, and large heat dissipation generated by the heating resistor can be suppressed.

  Furthermore, in the diaphragm element according to any one of the above, the contact insulating layer in contact with the first main surface of the silicon substrate among the insulating layers is substantially in a silicon etching processing solution for etching the silicon substrate. It is preferable to use a diaphragm element made of a material that is not etched.

Since the first main surface of the silicon substrate is the {100} plane, it is easily etched by the silicon etching treatment liquid. For this reason, when the silicon substrate is etched from the second main surface side to form the cavity, the first main surface side is also etched by the silicon etching treatment liquid, and the cavity may be formed larger than necessary. is there.
On the other hand, in the present invention, of the insulating layer, the contact insulating layer in contact with the first main surface of the silicon substrate is made of a material that is not substantially etched by the silicon etching treatment liquid. For this reason, when the silicon substrate is etched from the second main surface side to form the cavity, the first main surface side is protected by the contact insulating layer, so that the first main surface side is etched more than necessary. Can be prevented. Therefore, it is possible to prevent the hollow portion from being formed larger than necessary.
The “material that is not substantially etched with the silicon etching solution” refers to a material having a selectivity (ratio to the etching rate) of 1000 or more with respect to the silicon etching solution.

  In another aspect, the first main surface and a second main surface forming the back surface are made of silicon, and a plate-shaped direction is formed between the first main surface and the second main surface. A silicon substrate having a hollow portion penetrating therethrough, wherein the first main surface and the second main surface have a {100} plane orientation, the first main surface of the silicon substrate, and the cavity And an insulating layer formed by laminating a plurality of layers, and a heating resistor embedded in a cavity facing portion facing the cavity of the insulating layer and generating heat when energized. A method for manufacturing a diaphragm element, wherein the first main surface of the silicon substrate in which the cavity is not formed is made of a material that is not substantially etched by a silicon etching treatment liquid for etching the silicon substrate. Contact insulation layer After the contact insulating layer forming step to be formed and the contact insulating layer forming step, etching is performed by the silicon etching treatment liquid above a portion of the first main surface of the silicon substrate that faces the cavity facing portion. A sacrificial layer forming step of forming a sacrificial layer made of a material; and after the sacrificial layer forming step, at least the entire sacrificial layer is substantially covered with the silicon etching treatment liquid on the first main surface side of the silicon substrate. Forming a coating insulating layer made of a material that is not etched, and forming the cavity in the silicon substrate by performing one or a plurality of etchings after the coating insulating layer forming step. The sacrificial layer is removed, and the silicon substrate is separated from the first opening edge on the first main surface side and the second opening edge on the second main surface side of the cavity. The second opening edge overlaps with the first opening edge or is located on the inner side when viewed in the thickness direction, and the first opening edge and the second opening edge Starting from the virtual orientation of the drum-shaped virtual inner peripheral surface that protrudes inward and whose surface orientation is the {111} plane, the inner peripheral surface that actually constitutes the hollow portion is the virtual surface. And a hollow portion forming step in a form positioned on the outer side of the inner peripheral surface.

The manufacturing method of the diaphragm element of the present invention includes the contact insulating layer forming step, the sacrificial layer forming step, the covering insulating layer forming step, and the cavity forming step described above. It can be easily made smaller than the hollow portion. By reducing the dimension in the creeping direction of the cavity, even if the dimension in the creeping direction of the silicon substrate is reduced, the volume of the portion constituting the periphery of the cavity in the silicon substrate can be sufficiently secured. Therefore, it is possible to easily manufacture a diaphragm element that is downsized in the creeping direction while ensuring strength.
In addition, by providing each of the above-described steps, the silicon substrate can be configured such that the inner peripheral surface that actually configures the cavity is positioned outside the virtual inner peripheral surface. Of these, the portion forming the inner peripheral surface hardly affects the heat escape of the heat generated by the heating resistor, and a diaphragm element capable of appropriately controlling the temperature of the heating resistor can be easily manufactured.

  Furthermore, in the method for manufacturing a diaphragm element, in the contact insulating layer forming step, the contact insulating layer is formed on the entire surface of the first main surface, and in the sacrificial layer forming step, the contact insulating layer is formed on the contact insulating layer. The sacrificial layer is formed, and the cavity forming step is performed by etching the silicon substrate from the second main surface side to the first main surface with the silicon etching treatment liquid, and making contact with the inside of the silicon substrate. A first etching step for forming a hole through which the insulating layer is exposed; and after the first etching step, the contact insulating layer etching treatment solution that etches the contact insulating layer without etching the silicon substrate. A second etching step of etching away the first exposed portion of the exposed contact insulating layer to expose the sacrificial layer in the hole; and after the second etching step, A third etching step of etching and removing the entire sacrificial layer with the silicon etching treatment solution to expose the contact insulating layer and the covering insulating layer in the hole; and for the contact insulating layer after the third etching step. A fourth etching step of etching away the second exposed portion of the contact insulating layer exposed in the hole with an etching treatment solution to expose the first main surface of the silicon substrate in the hole; And a fifth etching step of etching the silicon substrate from the exposed surface of the first main surface exposed in the hole with the silicon etching treatment solution to form the cavity. It would be better to do it.

  Since the manufacturing method of the diaphragm element of the present invention includes the contact insulating layer forming step, the sacrificial layer forming step, and the covering insulating layer forming step, and the cavity forming step includes the above-described first to fifth etching steps. In addition, it is possible to easily manufacture a diaphragm element that is downsized in the creeping direction while ensuring strength. In addition, a portion of the silicon substrate that forms the inner peripheral surface of the cavity is less likely to affect the heat escape of the heat generated by the heating resistor, and a diaphragm element that can appropriately control the temperature of the heating resistor can be easily obtained. Can be manufactured.

  Furthermore, in the manufacturing method of the diaphragm element, in the contact insulating layer forming step, a sacrificial portion having a ring shape in plan view disposed in a portion of the first main surface facing the cavity facing portion, and this The contact insulating layer having an annular peripheral portion in plan view disposed around the sacrificial portion via a gap is formed, and in the sacrificial layer forming step, the sacrificial portion on the sacrificial portion and the first main surface The sacrificial layer is formed on an exposed surface exposed from the contact insulating layer, and the cavity forming step includes the step of forming the silicon substrate from the second main surface side to the first main surface with the silicon etching treatment liquid. To the inside of the contact insulating layer to form a hole exposing the sacrificial layer located inside the sacrificial portion, and further to continue the etching to remove the sacrificial layer by etching, In the hole The first main surface that is located on a radially outer side of the sacrificial portion of the contact insulating layer by exposing the covering insulating layer and bypassing the sacrificial portion of the contact insulating layer through a portion where the sacrificial layer is removed. The silicon substrate is etched from the side, the sacrificial part of the contact insulating layer is liberated and removed, and a method of manufacturing a diaphragm element having a single etching process for forming the cavity part is preferable.

  Since the manufacturing method of the diaphragm element of the present invention includes the above-described contact insulating layer forming step, sacrificial layer forming step, covering insulating layer forming step, and cavity forming step including a single etching step, the strength is ensured. A diaphragm element reduced in size in the creeping direction can be easily manufactured. In addition, a portion of the silicon substrate that forms the inner peripheral surface of the cavity is less likely to affect the heat escape of the heat generated by the heating resistor, and a diaphragm element that can appropriately control the temperature of the heating resistor can be easily obtained. Can be manufactured. In particular, in the present invention, the cavity forming step (single etching step) can be performed by a single etching, and the cavity forming step can be simplified, so that the diaphragm element can be manufactured particularly easily and inexpensively.

1 is a cross-sectional view of a diaphragm element according to Embodiment 1. FIG. The manufacturing method of the diaphragm element which concerns on Embodiment 1 shows a mode that the 1-1 insulating layer and the 2-1 insulating layer were formed in the silicon substrate, and also the sacrificial layer was formed on the 1-1 insulating layer. It is explanatory drawing. It is explanatory drawing which shows a mode that the 1-2 insulating layer and the 2-2 insulating layer were formed regarding the manufacturing method of the diaphragm element concerning Embodiment 1, and also the 1-3 insulating layer was formed. It is explanatory drawing which shows a mode that the heating resistor, the electrode pad, etc. were formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the 1-4th insulating layer was formed, the 1-5th insulating layer was formed on it, and also the via hole was formed regarding the manufacturing method of the diaphragm element concerning Embodiment 1. It is explanatory drawing which shows a mode that the via conductor was formed and the electrode terminal was formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which formed the opening by patterning the 2nd main surface side insulating layer regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the silicon etching was carried out to the 1st main surface side insulating layer regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the opening part was formed by etching away the exposed part of the 1-1 insulating layer regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the sacrificial layer whole was etched away regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the exposed part of the 1-1 insulating layer was etched away regarding the manufacturing method of the diaphragm element which concerns on Embodiment 1. FIG. 6 is a cross-sectional view of a diaphragm element according to Embodiment 2. FIG. It is sectional drawing of the diaphragm element which concerns on Embodiment 3. FIG. It is sectional drawing of the diaphragm element which concerns on Embodiment 4. FIG. It is explanatory drawing which shows a mode that the recessed part was formed in the 1st main surface side of a silicon substrate regarding the 1st manufacturing method of the diaphragm element which concerns on Embodiment 4. FIG. Regarding the first method for manufacturing a diaphragm element according to the fourth embodiment, a 1-1 insulating layer and a 2-1 insulating layer are formed on a silicon substrate, and a sacrificial layer is further formed on the 1-1 insulating layer. It is explanatory drawing which shows a mode. FIG. 10 is an explanatory diagram showing a state in which a silicon oxide film is formed on a silicon substrate and a silicon nitride film is further formed and patterned with respect to the second manufacturing method of the diaphragm element according to the fourth embodiment. It is explanatory drawing which shows a mode that the exposed part of the silicon oxide film of the 1st main surface side was formed thickly regarding the 2nd manufacturing method of the diaphragm element which concerns on Embodiment 4. FIG. It is explanatory drawing which shows the diaphragm element which has a sensor part. 6 is a cross-sectional view of a diaphragm element according to Embodiment 5. FIG. It is explanatory drawing which shows a mode that the 1-1 insulating layer and the 2-1 insulating layer were formed in the silicon substrate regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. It is explanatory drawing which shows a mode that the sacrificial layer and the 2-2 insulating layer were formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. It is explanatory drawing which shows a mode that the 1-2 insulating layer and the 2-3 insulating layer were formed, and also the 1-3 insulating layer was formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. It is explanatory drawing which shows a mode that the heating resistor, the electrode pad, etc. were formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. It is explanatory drawing which shows a mode that the 1-4th insulating layer was formed, the 1-5th insulating layer was formed on it, and also the via hole was formed regarding the manufacturing method of the diaphragm element concerning Embodiment 5. It is explanatory drawing which shows a mode that the via conductor was formed and the electrode terminal was formed regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. FIG. 10 is an explanatory diagram showing an opening formed by patterning a second principal surface side insulating layer, with respect to a method for manufacturing a diaphragm element according to a fifth embodiment. It is explanatory drawing which shows a mode that the silicon etching was carried out to the 1st main surface side insulating layer regarding the manufacturing method of the diaphragm element which concerns on Embodiment 5. FIG. FIG. 10 is an explanatory view showing a state in which silicon etching is further continued, a part of the sacrifice layer is removed by etching, and the silicon substrate is etched from the first main surface side in the diaphragm element manufacturing method according to the fifth embodiment. FIG. 10 is an explanatory view showing a state in which silicon etching is further continued, the entire sacrificial layer is removed by etching, and the silicon substrate is further etched with respect to the diaphragm element manufacturing method according to the fifth embodiment.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a diaphragm element 100 according to the first embodiment. The diaphragm element 100 includes a silicon substrate 110, a first main surface side insulating layer 120 composed of a plurality of layers stacked on the first main surface 110 b of the silicon substrate 110, and a second main surface 110 c of the silicon substrate 110. The second main surface side insulating layer 140 composed of a plurality of layers laminated on the first main surface side insulating layer 120 and the heating resistor 160 embedded in the first main surface side insulating layer 120 have a diaphragm structure.

  Among these, the silicon substrate 110 is made of silicon (Si) single crystal and has a plate shape with a thickness of 0.40 mm having a first main surface 110b and a second main surface 110c forming the back surface. The plane directions of the first main surface 110b and the second main surface 110c of the silicon substrate 110 are {100} planes (specifically, (100) planes). In the center of the silicon substrate 110, a drum-shaped cavity portion 111 penetrating between the first main surface 110b and the second main surface 110c in the plate thickness direction TA is formed. In FIG. 1, the vertical direction is the thickness direction TA.

The inner peripheral surface 110n constituting the hollow portion 111 is configured to protrude toward the inside in the creeping direction with respect to the first and second opening edges 110bf and 110cf. Therefore, the hollow portion 111 formed by the inner peripheral surface 110n has a drum shape in which the inside is recessed inward of the creeping direction from both ends (the upper end and the lower end in FIG. 1).
In the hollow portion 111, the first opening edge 110bf on the first main surface 110b side and the second opening edge 110cf on the second main surface 110c side have a rectangular shape in plan view. Then, when the first opening edge 110bf and the second opening edge 110cf are viewed in the thickness direction TA, the first opening edge 110bf and the second opening edge 110cf overlap each other at the same position EM1.

  Here, starting from the first opening edge 110bf, the surface orientation is the {111} plane (specifically, the (111) plane) and the creeping direction along the first main surface 110b (in FIG. A surface extending toward the inner side (radially inner side) of the direction) is assumed as a first virtual surface F1. In addition, the second opening edge 110cf is used as a starting point and the plane orientation is the {111} plane (specifically, the (111) plane) and the plane extending inward in the creeping direction is assumed as a second. It is assumed that the virtual plane F2. Then, from these first imaginary plane F1 and second imaginary plane F2, with the first opening edge 110bf and the second opening edge 110cf as starting points, the plane orientation is the (111) plane and protrudes inward. A virtual inner peripheral surface FN is assumed (indicated by a broken line in FIG. 1). Then, the entire inner peripheral surface 110n that actually configures the cavity 111 is located on the outer side (radially outer side) in the creeping direction than the virtual inner peripheral surface FN.

  Further, in the plate thickness direction TA, the position AM1 of the innermost 110nx located on the innermost side of the inner peripheral surface 110n is positioned from the position AM2 of the first main surface 110b to the position AM3 side of the second main surface 110c. More than one third of the thickness of 110. Specifically, as described above, the thickness of the silicon substrate 110 is 0.40 mm, and the position AM1 of the innermost 110nx is 0 from the position AM2 of the first main surface 110b to the position AM3 side of the second main surface 110c. .20mm away.

  Next, the first main surface side insulating layer 120 will be described. The first main surface side insulating layer 120 is formed in a form extending from the first main surface 110 b of the silicon substrate 110 and closing the cavity 111. The first main surface side insulating layer 120 includes five stacked insulating layers 121, 122, 123, 124, and 125. Specifically, the first main surface side insulating layer 120 includes a 1-1 insulating layer (contact insulating layer) 121 in contact with the first main surface 110 b of the silicon substrate 110. The first main surface side insulating layer 120 has a 1-2 insulating layer (covering insulating layer) 122 formed on the 1-1 insulating layer 121. The first main surface side insulating layer 120 includes a first-3 insulating layer 123 formed on the first-2 insulating layer 122. The first main surface side insulating layer 120 includes a first to fourth insulating layer 124 formed on the first to third insulating layer 123. In addition, the first main surface side insulating layer 120 includes a first to fifth insulating layer 125 formed on the first to fourth insulating layer 124.

  Among these, only the 1-1 insulating layer 121 is formed on the first main surface 110 b of the silicon substrate 110 so as to avoid the cavity 111. On the other hand, the other insulating layers 122, 123, 124, and 125 are formed not only on the first main surface 110 b but also on the cavity 111. Therefore, the 1-2 insulating layer 122 of the first main surface side insulating layer 120 is exposed toward the cavity 111.

The 1-1 insulating layer 121 is made of silicon oxide (SiO ₂ ) and has a thickness of 0.1 μm. Since the 1-1 insulating layer 121 is made of silicon oxide, it is not substantially etched by the silicon etching treatment liquid for etching the silicon substrate 110 as will be described later. On the other hand, the 1-1 insulating layer 121 is etched by a contact insulating layer etching treatment liquid described later.
The 1-2 insulating layer 122 is a tensile stress film made of silicon nitride (LP-SiN) and has a thickness of 0.2 μm. Since the first-second insulating layer 123 is made of silicon nitride, it is not substantially etched by the silicon etching processing solution or the contact insulating layer etching processing solution.
The 1-3 insulating layer 123 is a compressive stress film made of silicon oxide (PE-SiO ₂ ) and has a thickness of 0.1 μm. The 1-4 insulating layer 124 is a compressive stress film made of silicon oxide (PE-SiO ₂ ) similarly to the 1-3 insulating layer 123 and has a thickness of 0.1 μm. Further, the first-5th insulating layer 125 is a tensile stress film made of silicon nitride (LP-SiN) like the first-2 insulating layer 122, and has a thickness of 0.2 μm.

  Next, the heating resistor 160 will be described. The heating resistor 160 is embedded in the cavity facing portion 120 e facing the cavity 111 (located on the cavity 111) in the first main surface insulating layer 120. Specifically, in the cavity facing portion 120e, it is disposed between the first to third insulating layers 123 and the first to fourth insulating layers. The heating resistor 160 is made of metal (specifically, platinum (Pt)), and generates heat when energized. The heating resistor 160 has a zigzag shape in plan view from the first main surface 110b side (from above in FIG. 1). Note that the cavity facing portion 120e in the first main surface side insulating layer 120 is also referred to as a diaphragm portion including the heating resistor 160 embedded in this portion.

  Both ends of the heating resistor 160 are electrically connected to the electrode terminals 170, respectively. In FIG. 1, only one of the electrode terminals 170 is shown. Each electrode terminal 170 is formed in the peripheral part 120g which comprises the periphery of the cavity facing part 120e among the 1st main surface side insulating layers 120. As shown in FIG. Each electrode terminal 170 is electrically connected to the heating resistor 160, and has a plate-like electrode pad 171 formed between the 1-3 insulating layer 123 and the 1-4 insulating layer 124, and the electrode pad. It is formed of a hook-shaped via conductor 173 that is formed on 171 and passes through the first to fourth insulating layers 124 and the first to fifth insulating layers 125 and is exposed to the outside. The electrode pad 171 is made of metal (specifically, platinum (Pt) similarly to the heating resistor 160), and the via conductor 173 is made of metal (specifically, gold (Au)).

  Next, the second main surface side insulating layer 140 will be described. The second main surface side insulating layer 140 is laminated on the entire surface of the second main surface 110 c of the silicon substrate 110. However, unlike the first main surface side insulating layer 120, the second main surface side insulating layer 140 is not configured to close the cavity 111. The second main surface side insulating layer 140 is composed of two insulating layers 141 and 143. Specifically, the second main surface side insulating layer 140 includes a 2-1 insulating layer 141 in contact with the second main surface 110c of the silicon substrate 110, and a second insulating layer 141 formed on the 2-1 insulating layer 141. -2 insulating layer 143.

The 2-1 insulating layer 141 is made of silicon oxide (SiO ₂ ) and has a thickness of 0.1 μm, like the 1-1 insulating layer 121 described above. The 2-2 insulating layer 143 is made of silicon nitride (LP-SiN) and has a thickness of 0.4 μm, like the above-described 1-2 insulating layer 122.

  As described above, in the diaphragm element 100 of the first embodiment, the silicon substrate 110 includes the first opening edge 110bf on the first main surface 110b side and the second opening on the second main surface 110c side in the cavity 111. When the opening edge 110cf is seen through in the plate thickness direction TA and overlapped, the first opening edge 110bf and the second opening edge 110cf overlap with the same position EM1. For this reason, the dimension of the creeping direction of the cavity part 111 can be made smaller than before. By reducing the dimension of the cavity 111 in the creeping direction, even if the dimension of the silicon substrate 110 in the creeping direction is reduced, the volume of the portion of the silicon substrate 110 constituting the periphery of the cavity 111 can be sufficiently secured. . Therefore, the diaphragm element 100 can be downsized in the creeping direction while ensuring the strength of the silicon substrate 110 (diaphragm element 100).

Further, the silicon substrate 110 has a virtual inner peripheral surface FN that starts from the first opening edge 110bf and the second opening edge 110cf, has a (111) plane, and protrudes inward in the creeping direction. When this is done, the inner peripheral surface 110n that actually configures the cavity 111 is positioned outside the virtual inner peripheral surface FN in the creeping direction.
If the inner peripheral surface 110n constituting the cavity 111 protrudes further inward in the creeping direction than the virtual inner peripheral surface FN, a portion of the silicon substrate 111 that forms the inner peripheral surface 110n (projects). The heat generated in the heating resistor 160 is transmitted to the portion), and the heat escape increases, and it is difficult to precisely control the temperature of the heating resistor 160.

  However, in the first embodiment, the inner peripheral surface 110n constituting the hollow portion 111 is located on the outer side in the creeping direction than the virtual inner peripheral surface FN. For this reason, the portion of the silicon substrate 110 that forms the inner peripheral surface 110n is less likely to affect the heat escape of the heat generated by the heating resistor 160, so that the temperature of the heating resistor 160 can be controlled appropriately.

  Further, in the first embodiment, the inner peripheral surface 110n of the silicon substrate 110 protrudes inward of the creeping direction from the first and second opening edges 110bf and 110cf (the hollow portion 111 has a drum shape). ). For this reason, the cavity 111 of the silicon substrate 110 is made more than the case where the inner peripheral surface 110n constituting the cavity 111 is recessed outward (the cavity 111 is an abacus bead or via barrel). Therefore, the silicon substrate 110 can be increased in strength. Therefore, the dimension of the creeping direction of the diaphragm element 100 can be relatively reduced.

  On the other hand, in the silicon substrate 110, the innermost part 110nx of the inner peripheral surface 110n constituting the cavity 111 is directed from the first main surface 110b toward the second main surface 110c side in the plate thickness direction TA. The form is separated by more than one third of the thickness. For this reason, the portion of the silicon substrate 110 that forms the innermost 110 nx hardly affects the heat escape of the heat generated by the heating resistor 160, and suppresses the large heat dissipation generated by the heating resistor 160. be able to.

  Further, in the first main surface side insulating layer 120, the 1-1 insulating layer 121 in contact with the first main surface 110b of the silicon substrate 110 is made of a material that is not substantially etched by the silicon etching treatment solution. Therefore, as will be described later, when the cavity 111 is formed by etching the silicon substrate 110 from the second main surface 110c side, the first main surface 110b side is protected by the 1-1 insulating layer 121. Further, the first main surface 110b side can be prevented from being etched more than necessary. Therefore, the cavity 111 can be prevented from being formed larger than necessary.

Next, a method for manufacturing the diaphragm element 100 will be described with reference to FIGS.
First, a cleaned silicon substrate 110 (a plate-like silicon substrate in which the cavity 111 is not formed) is prepared (see FIG. 2). Then, in the contact insulating layer forming step, a first insulating layer (contact insulating layer) made of a material that is not substantially etched by the silicon etching treatment liquid for etching the silicon substrate 110 is formed on the first main surface 110b of the silicon substrate 110. ) 121 is formed. Specifically, the silicon substrate 110 is thermally oxidized to form a solid 1-1 insulating layer 121 made of a silicon oxide film having a thickness of 0.1 μm over the first and second main surfaces 110b and 110c. A 2-1 insulating layer 141 is formed.

  Thereafter, in the sacrificial layer forming step, the first main surface 110b of the silicon substrate 110 is made of a material that is etched by a silicon etching treatment solution above a portion facing the cavity facing portion 120e (above the cavity portion 111). A sacrificial layer 126 is formed. Specifically, a solid polysilicon film having a thickness of 0.1 μm is formed on the 1-1 insulating layer 121 and the 2-1 insulating layer 141 by low-pressure CVD (LP-CVD), respectively. . After that, as shown in FIG. 2, the polysilicon film on the first main surface 110b side is patterned to form a predetermined shape (specifically, similar to the cavity facing portion 120e and the cavity portion 111) located at the center in the creeping direction. A polysilicon film having a rectangular shape in plan view). The polysilicon film on the first main surface 110b side is a sacrificial layer 126 that is removed by etching in a process described later (specifically, a third etching process in the cavity forming process). Then, all the polysilicon film formed on the second main surface 110c side was removed.

Next, in the covering insulating layer forming step, a 1-2 insulating layer made of a material that is substantially not etched by the silicon etching treatment liquid in a form that covers the entire sacrificial layer 126 on the first main surface 110b side of the silicon substrate 110. (Coating insulating layer) 122 is formed. Specifically, a tensile stress film made of a silicon nitride film having a thickness of 0.2 μm is formed on the entire first and second main surfaces 110b and 110c side of the silicon substrate 110 by low-pressure CVD (LP-CVD). To do. These silicon nitride films are the 1-2 insulating layer 122 and the 2-2 insulating layer 143 (see FIG. 3). Thereby, the second main surface side insulating layer 140 composed of two layers is formed on the second main surface side 110c.
Thereafter, as shown in FIG. 3, a compressive stress film made of a silicon oxide film having a thickness of 0.1 μm is formed on the first-second insulating layer 122 on the first main surface 110b side by plasma CVD. This silicon oxide film is the first-3 insulating layer 123.

  Next, a metal (for example, platinum) is sputtered on the first-3 insulating layer 123 on the first main surface 110b side to form the metal film (platinum film), and then the platinum film is patterned. . Thereby, as shown in FIG. 4, the heating resistor 160, the electrode pad 171 and the like are formed.

Next, a compressive stress film made of a silicon oxide film having a thickness of 0.1 μm is formed on the entire first main surface 110b side by plasma CVD. This silicon oxide film is the first-fourth insulating layer 124. Thereafter, as shown in FIG. 5, a tensile stress film made of a silicon nitride film having a thickness of 0.2 μm is formed on the first insulating layer 124 on the first main surface 110b side by low pressure CVD (LP-CVD). Form. This silicon nitride film forms the first to fifth insulating layers 125. Thereby, the first main surface side insulating layer 120 including five layers is formed on the first main surface 110b side.
After that, the first to fourth insulating layers 124 and the first to fifth insulating layers 125 are patterned to penetrate the first to fourth insulating layers 124 and the first to fifth insulating layers 125 and expose the electrode pads 171 on the bottom surface. A hole 120 h is formed on the electrode pad 171.

Next, a metal (for example, gold) is sputtered on the first main surface 110b side to form the metal film (Au film), and then the Au film is patterned into a predetermined shape as shown in FIG. And via conductors 173 are formed. Thereby, an electrode terminal 170 composed of the electrode pad 171 and the via conductor 173 is formed.
Next, as shown in FIG. 7, the second main surface side insulating layer 140 is patterned, and the second main surface side insulating layer 140 at a position facing the cavity 111 is removed to form an opening 140h.

Next, in the hollow portion forming step, etching is performed a plurality of times (specifically, five times), thereby forming the above-described hollow portion 111 in the silicon substrate 110 and removing the sacrificial layer 126.
First, in the first etching step of the cavity forming step, the silicon substrate 110 is etched from the second main surface 110c side to the first main surface 110b with the silicon etching treatment liquid, and the first inside of the first portion is formed. A hole 101h through which the -1 insulating layer (contact insulating layer) 121 is exposed is formed (see FIG. 8). The hole 101h at this stage consists only of the opening 110h formed in the silicon substrate 110.

  Specifically, silicon exposed in the opening 140h of the second principal surface side insulating layer 140 as shown in FIG. 8 by an anisotropic etching solution (specifically, KOH or TMAH) which is a silicon etching treatment solution. The substrate 110 is subjected to silicon etching until it reaches the first main surface side insulating layer 120 (1-1 insulating layer 121). As a result, the center portion (first exposed portion 121r1) of the first main surface side insulating layer 120 (1-1 insulating layer 121) is exposed on the bottom surface of the silicon substrate 110, and the first main surface 110b side is small. An opening 110h (hole 101h) having a trapezoidal cross section on the second main surface 110c side is formed. The entire inner peripheral surface 110hr constituting the opening 110h is a (111) plane.

Next, in the second etching step of the cavity forming step, the holes are formed by the contact insulating layer etching treatment liquid that etches the 1-1 insulating layer (contact insulating layer) 121 without etching the silicon substrate 110. The sacrificial layer 126 is exposed in the hole 101h by etching away the first exposed portion 121r1 of the contact insulating layer 121 exposed in 101h.
Specifically, as shown in FIG. 9, the first exposure of the 1-1 insulating layer 121 exposed in the opening 110h (hole 101h) of the silicon substrate 110 by hydrofluoric acid that is an etching treatment solution for the contact insulating layer. The portion 121r1 is removed by etching (silicon oxide etching) to form an opening 121h1 in the 1-1 insulating layer 121. As a result, the central portion (exposed portion 126r) of the sacrificial layer 126 is exposed in the hole 101h formed by the opening 110h of the silicon substrate 110 and the opening 121h1 of the first-first insulating layer 121.

Next, in the third etching step of the cavity forming step, the entire sacrificial layer 126 is etched away with a silicon etching treatment solution, and the 1-1 insulating layer (contact insulating layer) 121 and the first insulating layer 121 are formed in the hole 101h. The 1-2 insulating layer (covering insulating layer) 122 is exposed.
Specifically, the sacrificial layer 126 is etched (polysilicon etching) as shown in FIG. 10 by processing for about 4 to 5 hours with an anisotropic etching solution (silicon etching solution) such as KOH or TMAH. . Accordingly, the sacrificial layer 126 includes not only the exposed portion 126r (see FIG. 9) exposed in the opening 121h1 in the 1-1 insulating layer 121 but also the 1-1 insulating layer 121 and the 1-2 insulating layer 122. The portion disposed between the layers is also removed by etching. That is, the entire sacrificial layer 126 is removed by etching.

  As a result, the portion where the sacrificial layer 126 was present becomes the opening 126h, and the portion of the 1-1 insulating layer 121 that was in contact with the sacrificial layer 126 became the second exposed portion 121r2, and the silicon substrate 110 The opening is exposed in a hole 101h including an opening 110h, an opening 121h1 of the 1-1 insulating layer 121, and an opening 126h formed by removing the sacrificial layer 126. In addition, the portion of the first-second insulating layer 122 that is in contact with the sacrificial layer 126 also becomes the exposed portion 122r and is exposed in the hole 101h.

In the first embodiment, since the sacrificial layer 126 is formed of polysilicon, the etching time is shorter than when the sacrificial layer 126 is formed of silicon oxide (etching time is, for example, 20 hours to 40 hours). (Etching time is 4 to 5 hours). In addition, an anisotropic etching solution (KOH, TMAH, etc.) used for etching the sacrificial layer 126 has an etching rate as low as about 1/100 of the silicon nitride film as compared with hydrofluoric acid. For this reason, there is almost no influence on the 1-2 insulating layer 122 made of a silicon nitride film.
In the first embodiment, since the 1-1 insulating layer 121 made of silicon oxide is formed between the silicon substrate 110 and the sacrificial layer 126, the first main surface of the silicon substrate 110 is etched during this etching. It is possible to prevent the 110b side from being etched.

Next, in the fourth etching step of the cavity portion forming step, the second exposed portion 121r2 of the first-1 insulating layer (contact insulating layer) 121 exposed in the hole 101h is etched by the contact insulating layer etching treatment liquid. Etching is removed to expose the first main surface 110b of the silicon substrate 110h in the hole 101h.
Specifically, as shown in FIG. 11, the second exposed portion 121r2 exposed in the hole 101h (opening 126h) in the first-first insulating layer 121, as shown in FIG. Are removed by etching (silicon oxide etching). As a result, the portion where the second exposed portion 121r2 of the 1-1 insulating layer 121 was present becomes the opening 121h2, and the second exposed portion of the 1-1 insulating layer 121 of the first main surface 110b of the silicon substrate 110 is formed. A portion (exposed surface 110br1) in contact with the portion 121r2 is in the hole 101h formed by the opening 110h of the silicon substrate 110, the opening 121h2 of the first-first insulating layer 121, and the opening 126h formed by removing the sacrificial layer 126. Exposed to. Since this exposed surface 110br1 is a part of the first main surface 110b, it forms a (100) surface. On the other hand, the inner peripheral surface 110hr constituting the opening 110h of the silicon substrate 110 is the (111) surface as described above.

Next, in a fifth etching step of the cavity forming step, the silicon substrate 110 is etched from the exposed surface 110br1 of the first main surface 110b exposed in the opening 101 with a silicon etching treatment liquid, so that the cavity 111 is formed. Form.
Specifically, the silicon substrate 110 exposed in the hole 101h is etched with an anisotropic etchant (specifically, KOH or TMAH) that is a silicon etchant. At this time, since the (100) plane of the silicon substrate 110 is more easily etched than the (111) plane, the first insulating layer 121 of the first insulating layer 121 is more than the inner peripheral surface 110hr constituting the opening 110h of the silicon substrate 110. The exposed surface 110br1 exposed in the opening 121h2 is etched more quickly. As this silicon etching proceeds, the (100) plane disappears. Then, the cavity 111 shown in FIG. 1 is formed. Thus, the diaphragm element 100 is completed.

As described above, the manufacturing method of the diaphragm element 100 according to the first embodiment includes the above-described contact insulating layer forming step, sacrificial layer forming step, covering insulating layer forming step, and cavity portion forming step, and the cavity portion forming step. However, since the first to fifth etching steps are included, the creeping dimension of the cavity 111 can be easily made smaller than that of the conventional trapezoidal cavity. By reducing the dimension of the cavity 111 in the creeping direction, even if the dimension of the silicon substrate 110 in the creeping direction is reduced, the volume of the portion of the silicon substrate 110 constituting the periphery of the cavity 111 can be sufficiently secured. . Therefore, it is possible to easily manufacture the diaphragm element 100 that is reduced in size in the creeping direction while ensuring the strength.
In addition, by providing the above-described steps, the silicon substrate 110 can be configured such that the inner peripheral surface 110n that actually configures the cavity 111 is positioned outside the virtual inner peripheral surface FN. A portion of the substrate 110 forming the inner peripheral surface 110n hardly affects the heat escape of the heat generated by the heating resistor 160, and the diaphragm element 100 that can appropriately control the temperature of the heating resistor 160 can be easily obtained. Can be manufactured.

(Embodiment 2)
Next, a second embodiment will be described. In the diaphragm element 100 of the first embodiment, the inner peripheral surface 110n of the silicon substrate 110 protrudes inward in the creeping direction from the first and second opening edges 110bf and 110cf. On the other hand, in the diaphragm element 200 of the second embodiment, the inner peripheral surface 110m of the silicon substrate 110 is recessed toward the outside in the creeping direction with respect to the first and second opening edges 110bf and 110cf. Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified. FIG. 12 shows a diaphragm element 200 according to the second embodiment.

Similarly to the diaphragm element 100 of the first embodiment, the diaphragm element 200 of the second embodiment also includes a silicon substrate 110, a first main surface side insulating layer 120, a second main surface side insulating layer 140, a heating resistor 160, and the like. It is configured.
In the silicon substrate 110, a cavity portion 211 penetrating in the plate thickness direction TA is formed. When the first opening edge 110bf on the first main surface 110b side of the cavity 211 and the second opening edge 110cf on the second main surface 110c side are seen through each other in the thickness direction TA, the first opening is seen. The edge 110bf and the second opening edge 110cf overlap at the same position EM1.

  Further, with the first opening edge 110bf and the second opening edge 110cf as the starting points, the inner peripheral surface protruding inward in the creeping direction is assumed as the virtual inner peripheral surface FN with the (111) plane orientation. Then, the entire inner peripheral surface 110m that actually constitutes the cavity 111 is located outside the creeping direction with respect to the virtual inner peripheral surface FN. More specifically, unlike the inner peripheral surface 110n of the first embodiment, the inner peripheral surface 110m is recessed toward the outside in the creeping direction from the first and second opening edges 110bf and 110cf (cavity). The portion 211 forms an abacus bead shape or a beer barrel shape).

  Also in such a diaphragm element 200, the silicon substrate 110 is configured such that the first opening edge 110bf of the first main surface 110b and the second opening edge 110cf of the second main surface 110c are at the same position EM1 in the creeping direction. Yes. For this reason, the dimension of the creeping direction of the cavity part 211 can be made smaller than before. By reducing the size of the cavity 211 in the creeping direction, the volume of the peripheral portion of the cavity 211 in the silicon substrate 110 can be sufficiently secured even if the size of the silicon substrate 110 in the creeping direction is reduced. Therefore, the diaphragm element 200 can be downsized in the creeping direction while ensuring the strength of the silicon substrate 110 (diaphragm element 200).

  In the second embodiment, the inner peripheral surface 110m constituting the hollow portion 211 is recessed toward the outside in the creeping direction with respect to the first and second opening edges 110bf and 110cf. Of these, the portion forming the inner peripheral surface 110m is less likely to affect the heat escape of heat generated in the heating resistor 160, and large heat dissipation generated in the heating resistor 160 can be suppressed. In addition, the same parts as those of the first embodiment have the same effects.

  The diaphragm element 200 is manufactured as follows. First, in the same manner as in the first embodiment, the sacrifice layer 126 is removed by etching, and the steps until the second exposed portion 121r2 of the 1-1 insulating layer 121 exposed thereby is removed by etching (contact insulating layer forming step). , Sacrificial layer forming step, covering insulating layer forming step, first to fourth etching steps of the cavity portion forming step, etc.) are performed (see FIGS. 2 to 11). Thereafter, in the fifth etching step of the cavity forming step, the silicon substrate 110 exposed in the hole 101h is etched with an anisotropic etching solution (specifically, KOH or TMAH) that is a silicon etching processing solution. At this time, the etching time is set longer than that of the first embodiment, and the silicon substrate 110 is etched more. Then, the cavity 211 shown in FIG. 12 is formed, and the diaphragm element 200 according to the second embodiment is completed.

(Embodiment 3)
Next, a third embodiment will be described. In the diaphragm element 100 of the first embodiment, the first opening edge 110bf and the second opening edge 110cf of the cavity 111 exist at the same position EM1 in the creeping direction. On the other hand, in the diaphragm element 300 according to the second embodiment, the second opening edge 110cg is located on the inner side in the creeping direction than the first opening edge 110bf of the cavity 311. Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified. FIG. 13 shows a diaphragm element 300 according to the third embodiment.

Similarly to the diaphragm element 100 of the first embodiment, the diaphragm element 300 of the third embodiment also includes a silicon substrate 110, a first main surface side insulating layer 120, a second main surface side insulating layer 140, a heating resistor 160, and the like. It is configured.
In the silicon substrate 110, a cavity 311 penetrating in the plate thickness direction TA is formed. The inner peripheral surface 110p constituting the hollow portion 311 has a form protruding toward the inner side in the creeping direction from the first and second opening edges 110bf and 110cg (the hollow portion 311 has a drum shape). Further, when the first opening edge 110bf on the first main surface 110b side of the cavity 311 and the second opening edge 110cg on the second main surface 110c side are seen through in the plate thickness direction TA and overlapped, The position EM2 of the second opening edge 110cg exists inside the position EM1 of the first opening edge 110bf.

  Here, with the first opening edge 110bf as a starting point, the plane orientation is the (111) plane, and the inside (radially inward) inside the creeping direction (left-right direction in FIG. 1) along the first main surface 110b. A surface extending in the direction is assumed to be a first virtual surface G1. Further, a surface having the (111) plane and starting from the second opening edge 110cg as a starting point and extending inward in the creeping direction is assumed as a second virtual plane G2. Then, from these first imaginary plane G1 and second imaginary plane G2, with the first opening edge 110bf and the second opening edge 110cg as starting points, the surface orientation is the (111) plane and protrudes inward. A virtual inner peripheral surface GN is assumed (indicated by a broken line in FIG. 13). If it does so, the inner peripheral surface 110p which actually comprises the cavity part 311 will be located in the outer side (radial direction outer side) of the creeping direction rather than the virtual inner peripheral surface GN as a whole.

  Further, in the plate thickness direction TA, the position AM4 of the innermost 110px located on the innermost side in the creeping direction on the inner peripheral surface 110p is from the position AM2 of the first main surface 110b to the position AM3 side of the second main surface 110c. Is more than one third of the thickness of the silicon substrate 110. Specifically, the thickness of the silicon substrate 110 is 0.40 mm, and the position AM4 of the innermost 110 px is 0.18 mm away from the position AM2 of the first main surface 110b toward the position AM3 of the second main surface 110c. Yes.

  In such a diaphragm element 300, the silicon substrate 110 has the second opening edge 110cg on the second main surface 110c side of the cavity 311 closer to the inner side in the creeping direction than the first opening edge 110bf on the first main surface 110b side. It has a certain form. For this reason, the dimension of the creeping direction of the hollow part 311 can be made smaller than before. By reducing the dimension in the creeping direction of the cavity 311, the volume of the peripheral part of the cavity 311 in the silicon substrate 110 can be sufficiently secured even if the dimension in the creeping direction of the silicon substrate 110 is reduced. Therefore, the diaphragm element 300 can be downsized in the creeping direction while ensuring the strength of the silicon substrate 110 (diaphragm element 300). In addition, the same parts as those of the first embodiment have the same effects.

  The diaphragm element 300 is manufactured by performing the same steps (contact insulating layer forming step, sacrificial layer forming step, covering insulating layer forming step, cavity forming step, etc.) as the diaphragm element 100 of the first embodiment. Specifically, in the step of patterning the second main surface side insulating layer 140, the size of the portion to be removed by etching may be made smaller than that of the first embodiment.

(Embodiment 4)
Next, a fourth embodiment will be described. In the diaphragm element 100 according to the first embodiment, the portion facing the cavity 111 in the cavity facing portion 120e of the first main surface side insulating layer 120 has the cavity 111 and the cavity 111 corresponding to the formation of the sacrificial layer 126 during manufacturing. Is recessed on the opposite side (upward in FIG. 1). On the other hand, in the diaphragm element 400 of the fourth embodiment shown in FIG. 14, the cavity facing portion 120j of the first main surface side insulating layer 120 does not have such a recess and is substantially flat. Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified.

The diaphragm element 400 of the fourth embodiment also includes a silicon substrate 110, a first main surface side insulating layer 120, a second main surface side insulating layer 140, a heating resistor 160, and the like. Among these, the silicon substrate 110, the second principal surface side insulating layer 140, the heating resistor 160, and the like are the same as those in the first embodiment.
On the other hand, the first main surface side insulating layer 120 is different from the first embodiment, as shown in FIG. 14, the cavity portion 111 of the cavity facing portion 120 j (diaphragm portion) of the first main surface side insulating layer 120. The portion facing the surface has no dent as in the first embodiment and is substantially flat.

  Also in such a diaphragm element 400, the silicon substrate 110 has the first opening edge 110bf on the first main surface 110b side of the cavity 111 and the second opening edge 110cf on the second main surface 110c side at the same position in the creeping direction. Overlapping form. For this reason, the dimension of the creeping direction of the cavity part 111 can be made smaller than before. Therefore, the diaphragm element 400 can also be miniaturized in the creeping direction. In addition, the same parts as those of the first embodiment have the same effects.

Next, a first manufacturing method of the diaphragm element 400 will be described.
First, a silicon substrate 110 is prepared. Then, as shown in FIG. 15, a recess 110i is formed at a predetermined position in the center of the first main surface 110b by dry etching.

Next, in the contact insulating layer forming step, the silicon substrate 110 is thermally oxidized to form a solid first first layer made of a silicon oxide film having a thickness of 0.1 μm over the first main surface 110b and the second main surface 110c. -1 insulating layer (contact insulating layer) 121 and 2-1 insulating layer 141 are formed (see FIG. 16).
Thereafter, in the sacrificial layer forming step, a solid polysilicon film having a thickness of 0.1 μm is formed on the 1-1 insulating layer 121 and the 2-1 insulating layer 141. Thereafter, as shown in FIG. 16, the polysilicon film on the first main surface 110b side is patterned to form a predetermined shape located at the center in the creeping direction (specifically, similar to the cavity facing portion 120i and the cavity portion 111). (A rectangular shape in plan view). The polysilicon film on the first main surface 110b side is a sacrificial layer 126 that is removed by etching in a process described later (specifically, a third etching process in the cavity forming process). Then, all the polysilicon film formed on the second main surface 110c side was removed.

  In the fourth embodiment, as shown in FIG. 16, the first main surface 110b side is flat with the sacrificial layer 126 formed. Accordingly, the 1-2 insulating layer 122, the 1-3 insulating layer 123, the 1-4 insulating layer 124, and the 1-5 insulating layer 125 formed thereon are also flattened. Therefore, the 1st main surface side insulating layer 120 (cavity facing part 120j) can be formed flat. The subsequent steps (such as the coating insulating layer forming step and the cavity forming step) may be performed in the same manner as in the first embodiment to manufacture the diaphragm element 400.

Next, a second manufacturing method of the diaphragm element 400 will be described.
First, a silicon substrate 110 is prepared. Then, the silicon substrate 110 is thermally oxidized to form silicon oxide films 421 and 441 on the entire surfaces of the first main surface 110b and the second main surface 110c (see FIG. 17).
Thereafter, silicon nitride films 422 and 442 are formed on the silicon oxide films 421 and 441 by low-pressure CVD (LP-CVD). Thereafter, as shown in FIG. 17, the silicon nitride film 422 is patterned on the first main surface 110b side, and an opening 422h is formed in the center thereof. As a result, the central portion (exposed portion 421r) of the silicon oxide film 421 on the first main surface 110b side is exposed in the opening 422h.

Next, the first main surface 110b side of the silicon substrate 110 is thermally oxidized to form a thicker exposed portion 421r of the silicon oxide film 421 exposed from the silicon nitride film 422 as shown in FIG.
Thereafter, all of the silicon nitride films 422 and 442 on the first and second main surfaces 110b and 110c are removed, and further, all of the silicon oxide films 421 and 441 are also removed. As a result, a silicon substrate 110 having a recess on the first main surface side is formed (see FIG. 15). Therefore, after that, the diaphragm element 400 may be manufactured in the same manner as in the first manufacturing method.

(Embodiment 5)
Next, a fifth embodiment will be described. In the diaphragm element 600 of the fifth embodiment, the first main surface side insulating layer 620 differs from the first main surface side insulating layer 120 of the diaphragm element 100 of the first embodiment. Further, the manufacturing method of the diaphragm element 600 is different from the manufacturing method of the diaphragm element 100 of the first embodiment. Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified.

  FIG. 20 shows a diaphragm element 600 according to the fifth embodiment. The diaphragm element 600 has the same silicon substrate 110 as that of the first embodiment. A first main surface side insulating layer 620 made of a plurality of layers is laminated on the first main surface 110b of the silicon substrate 110, and a second main surface side made of a plurality of layers is formed on the second main surface 110c. An insulating layer 640 is stacked.

Among these, the 1st main surface side insulating layer 620 is comprised from the five insulating layers 621,622,623,624,625. Specifically, the first main surface side insulating layer 620 includes a 1-1 insulating layer (contact insulating layer) 621 that is in contact with the first main surface 110b of the silicon substrate 110 and is similar to the first embodiment.
The first main surface side insulating layer 620 includes a 1-2 insulating layer (covered insulating layer) 622 formed on the 1-1 insulating layer 621. The 1-2 insulating layer 122 (see FIG. 1) of the first embodiment has a flat portion facing the cavity 111, whereas the 1-2 insulating layer 622 of the fifth embodiment has a cavity. The portion facing the portion 111 is uneven. This difference is caused by a difference in manufacturing method described later.

  Further, the first main surface side insulating layer 620 includes a first to third insulating layer 623 formed on the first to second insulating layer 622 and similar to the first embodiment. The first main surface side insulating layer 620 includes the first to fourth insulating layers 624 that are formed on the first to third insulating layers 623 and are similar to those of the first embodiment. Further, the first main surface side insulating layer 620 includes the first to fifth insulating layers 625 that are formed on the first to fourth insulating layers 624 and are the same as those of the first embodiment.

The second main surface side insulating layer 640 is composed of two insulating layers 641 and 643. Specifically, the second main surface side insulating layer 640 includes the 2-1 insulating layer 641 that is in contact with the second main surface 110c of the silicon substrate 110 and is similar to the first embodiment.
The second principal surface side insulating layer 640 includes a 2-2 insulating layer 643 formed on the 2-1 insulating layer 641. The 2-2 insulating layer 643 is the same as the 2-2 insulating layer 143 (see FIG. 1) of the first embodiment.

  The heating resistor 160 is embedded in the cavity facing part 620e facing the cavity part 111 (located on the cavity part 111) in the first main surface insulating layer 620, as in the first embodiment. Yes. Moreover, the electrode terminal 170 is formed in the peripheral part 620g which makes the periphery of the cavity facing part 620e among the 1st main surface side insulating layers 620. FIG.

  In the diaphragm element 600 as well, the silicon substrate 110 has the same form as that of the first embodiment, and the dimension of the cavity 111 in the creeping direction can be made smaller than the conventional one. By reducing the dimension in the creeping direction of the cavity 111, the volume of the peripheral portion of the cavity 111 in the silicon substrate 110 can be sufficiently secured even if the dimension in the creeping direction of the silicon substrate 110 is reduced. Therefore, the diaphragm element 600 can be downsized in the creeping direction while ensuring the strength of the silicon substrate 110 (diaphragm element 600). In addition, the same parts as those of the first embodiment have the same effects.

Next, a manufacturing method of the diaphragm element 600 will be described with reference to FIGS.
First, as in the first embodiment, a plate-like silicon substrate 110 in which the cavity 111 is not formed is prepared (see FIG. 21). In the contact insulating layer forming step, a 1-1 insulating layer (contact insulating layer) 621 made of a material that is not substantially etched by the silicon etching solution is formed on the first main surface 110b of the silicon substrate 110.

Specifically, the silicon substrate 110 is thermally oxidized to form a solid 1-1 insulating layer 621 made of a silicon oxide film and a 2-1 insulating layer over the entire surfaces of the first and second main surfaces 110b and 110c. Layer 641 is formed.
Thereafter, in the fifth embodiment, as shown in FIG. 21, the 1-1 insulating layer 621 is patterned into a predetermined shape. That is, of the 1-1 insulating layer 621 formed in a solid shape on the entire surface, the portion located in the cavity facing portion 620e (see FIG. 20) of the first main surface side insulating layer 620 is patterned to form an annular shape in plan view. A 1-1 insulating layer sacrificial portion (sacrificial portion) 621j (specifically, a square shape in plan view) is formed. Since the 1-1 insulating layer sacrificial portion 621j is removed by silicon etching described later and disappears, it does not remain in the diaphragm element 600.

  On the other hand, of the 1-1 insulating layer 621 formed in a solid shape on the entire surface, the portion located at the peripheral edge 620g (see FIG. 20) of the first main surface side insulating layer 620 is left without being patterned. As a result, a first insulating layer peripheral portion (peripheral portion) 621g having a ring shape (specifically, a planar shape in plan view) is formed around the first insulating layer sacrificial portion 621j through a gap. Is done. Unlike the above-described 1-1 insulating layer sacrificial portion 621j, the 1-1 insulating layer peripheral portion 621g remains without being removed, and therefore exists even when the diaphragm element 600 is completed as the 1-1 insulating layer 621. To do.

Next, in the sacrificial layer forming step, from the material etched by the silicon etching processing solution above the portion facing the cavity facing portion 620e (above the cavity portion 111) of the first main surface 110b of the silicon substrate 110. A sacrificial layer 626 is formed.
Specifically, by the low pressure CVD method (LP-CVD method), the first main surface 110b side (specifically, on the 1-1 insulating layer 621 and among the first main surface 110b, the 1-1 insulating layer). A solid polysilicon film is formed on the exposed surface 110br2 exposed from 621) and on the second main surface 110c side (on the 2-1 insulating layer 641) (see FIG. 22).

Thereafter, as shown in FIG. 22, the polysilicon film on the first main surface 110b side is patterned to form a polysilicon film having a predetermined shape located at the center in the creeping direction. Specifically, a portion of the polysilicon film formed in a solid shape that is located at the peripheral edge portion 620g (see FIG. 20) of the first main surface side insulating layer 620 is removed, and the cavity facing portion 620e (see FIG. 20). A polysilicon film having a rectangular shape in a plan view is left, leaving a portion located at the top. The polysilicon film on the first main surface 110b side is a sacrificial layer 626 that is removed by etching in a process described later (specifically, a cavity forming process). The sacrificial layer 626 has the same shape as that of the sacrificial layer 126 in the first embodiment in plan view, but unlike the sacrificial layer 126 in the first embodiment, the first-first insulating layer sacrificial portion 621j having a predetermined pattern is provided below the sacrificial layer 126. Therefore, it has an uneven shape following it.
Note that all the polysilicon film formed on the second main surface 110c side was removed.

Next, in the covering insulating layer forming step, the 1-2 insulating layer made of a material that is substantially not etched by the silicon etching treatment liquid in a form that covers the entire sacrificial layer 626 on the first main surface 110b side of the silicon substrate 110. (Coating insulating layer) 622 is formed.
Specifically, a tensile stress film made of a silicon nitride film is formed on the entire first and second main surfaces 110b and 110c side of the silicon substrate 110 by low pressure CVD (LP-CVD). These silicon nitride films are the 1-2 insulating layer 622 and the 2-2 insulating layer 643 (see FIG. 23). Thereby, the 2nd main surface side insulating layer 640 which consists of two layers is formed in the 2nd main surface side 110c. Note that the sacrificial layer 626 located below the first-second insulating layer 622 has an uneven shape, and accordingly has an uneven shape.

Next, as shown in FIG. 23, a compressive stress film made of a silicon oxide film is formed on the first-second insulating layer 622 on the first main surface 110b side in the same manner as in the first embodiment. This silicon oxide film is the first to third insulating layer 623.
Thereafter, as shown in FIG. 24, the heating resistor 160, the electrode pad 171 and the like are formed on the first-3 insulating layer 623 in the same manner as in the first embodiment.
Thereafter, a first to fourth insulating layer 624 made of a silicon oxide film is formed on the entire first main surface 110b side in the same manner as in the first embodiment. Further, as shown in FIG. A first to fifth insulating layer 625 made of a silicon nitride film is formed on the insulating layer 124. Thereby, the first main surface side insulating layer 620 including five layers is formed on the first main surface 110b side. Thereafter, in the same manner as in the first embodiment, a via hole 620h in which the electrode pad 171 is exposed on the bottom surface is formed on the electrode pad 171.
Thereafter, as shown in FIG. 26, via conductors 173 are formed in the same manner as in the first embodiment, and electrode terminals 170 including electrode pads 171 and via conductors 173 are formed.
Further, as shown in FIG. 27, in the same manner as in the first embodiment, the second main surface side insulating layer 640 at a position facing the cavity 111 is removed to form an opening 640h.

Next, in the cavity forming process, the above-described cavity 111 is formed in the silicon substrate 110 while removing the sacrificial layer 626 by performing etching only once (single etching process).
That is, in the initial stage of this etching, the silicon substrate 110 is etched from the second main surface 110c side to the first main surface 110b with a silicon etching treatment solution, and the 1-1 insulating layer is sacrificed inside itself. A hole 601h is formed in which the sacrificial layer 626 located inside (radially inside) the portion 621j is exposed. The hole 601h at this point is composed of only the opening 110h formed in the silicon substrate 110.

  Specifically, as shown in FIG. 28, silicon exposed in the opening 640h of the second principal surface side insulating layer 640 by an anisotropic etching liquid (specifically, KOH or TMAH) that is a silicon etching treatment liquid. The substrate 110 is etched until it reaches the first principal surface side insulating layer 620. Since the 1-1 insulating layer 621 is made of a material that is not etched by the silicon etching solution, the etching of the silicon substrate 110 is temporarily stopped at the position of the inner peripheral edge 621jk of the 1-1 insulating layer sacrificing portion 621j. As a result, in the silicon substrate 110, a central portion (exposed portion 626r) in a rectangular shape in plan view located inside the first-first insulating layer sacrificial portion 621j of the sacrificial layer 626 is exposed on the bottom surface, and the first main layer is exposed. An opening 110h (hole 601h) having a trapezoidal cross section is formed on the surface 110b side and on the second main surface 110c side. The entire inner peripheral surface 110hr constituting the opening 110h is a (111) plane.

  Thereafter, this silicon etching is further continued, and as shown in FIG. 29, the sacrificial layer 626 is etched away from the central portion (exposed portion 626r) to the outside (radially outward), and the first layer is formed in the hole 601h. -2 Insulating layer (covering insulating layer) 622 is exposed, and the 1-1 insulating layer sacrificial part is bypassed by bypassing the 1-1 insulating layer sacrificing part 621j through the portion (opening 626h) from which the sacrificial layer 626 is removed. The silicon substrate 110 is etched from the side of the first main surface 110b located on the outer side in the radial direction of 621j (outside in the creeping direction).

  Thereafter, this silicon etching is further continued, and as shown in FIG. 30, the entire sacrificial layer 626 is removed by etching, and the first insulating layer sacrificial portion 621j is located on the radially outer side (the outer side in the creeping direction). The silicon substrate 100 is etched from the main surface 110b side. Since the silicon substrate 110 is more easily etched on the (100) plane than on the (111) plane, the etching proceeds so that the inner peripheral surface 110hr constituting the opening 110h becomes the (111) plane. When this silicon etching is further continued, the 1-1 insulating layer sacrificial portion 621j is removed from the silicon substrate 110 and removed, and the cavity 111 shown in FIG. 20 is formed. Thus, the diaphragm element 600 is completed.

Note that an anisotropic etching solution (KOH, TMAH, etc.) used for this etching has a small etching rate of about 1/100 of the silicon nitride film as compared with hydrofluoric acid. For this reason, there is almost no influence on the 1-2 insulating layer 622 made of a silicon nitride film.
Further, a portion of the first main surface 110b of the silicon substrate 110 that faces the peripheral portion 620g of the first main surface-side insulating layer 620 has a 1-1 insulating layer 621 (1-1 insulating layer peripheral portion 621g). ) Is formed, it is possible to prevent the first main surface 110b of the silicon substrate 110 covered therewith from being etched.

  As described above, the manufacturing method of the diaphragm element 600 according to the fifth embodiment includes the above-described contact insulating layer forming step, sacrificial layer forming step, covering insulating layer forming step, and cavity portion forming step. The dimension in the creeping direction can be made smaller than that of the conventional trapezoidal cavity. By reducing the dimension of the cavity 111 in the creeping direction, even if the dimension of the silicon substrate 110 in the creeping direction is reduced, the volume of the portion of the silicon substrate 110 constituting the periphery of the cavity 111 can be sufficiently secured. . Therefore, it is possible to easily manufacture the diaphragm element 600 that is reduced in size in the creeping direction while ensuring the strength.

  In addition, by providing the above-described steps, the silicon substrate 110 can be configured such that the inner peripheral surface 110n that actually configures the cavity 111 is positioned outside the virtual inner peripheral surface FN. A portion of the substrate 110 that forms the inner peripheral surface 110n hardly affects the heat escape of the heat generated by the heating resistor 160, and the diaphragm element 600 that can appropriately control the temperature of the heating resistor 160 is easily obtained. Can be manufactured. In particular, in the fifth embodiment, the cavity forming step can be performed by one etching, and the cavity forming step can be simplified as compared with the first to fourth embodiments. It can be manufactured more easily and cheaply than the first to fourth embodiments.

In the above, the present invention has been described with reference to the first to fifth embodiments. However, the present invention is not limited to the above-described first to fifth embodiments, and is appropriately modified and applied without departing from the gist thereof. Needless to say, it can be done.
For example, in the first to fifth embodiments, the diaphragm elements 100, 200, 300, 400, and 600 that do not include the sensor unit are illustrated. However, as illustrated in FIG. 19, for example, the heating resistor is provided on the first main surface 101b side. A sensor unit 580 that functions by being heated by the body 160 may be further provided to form a diaphragm element 500 such as a physical quantity sensor element or a chemical sensor element.

100, 200, 300, 400, 500, 600 Diaphragm element 110 Silicon substrate 110b First main surface 110c Second main surface 110bf First opening edge 110cf, 110cg Second opening edge 110n, 110m, 110p Inner peripheral surface 110nx, 110px Internal 111, 211, 311 Cavity 120, 620 First main surface side insulating layer 120e, 120j, 620e Cavity facing surface 121, 621 1-1 insulating layer (contact insulating layer)
140,640 Second main surface side insulating layer 160 Heating resistor 170 Electrode terminal EM1, EM2 Position AM1, AM2, AM3, AM4 Position FN, GN Virtual inner peripheral surface TA Plate thickness direction

Claims (7)

Silicon made of silicon, having a plate shape having a first main surface and a second main surface forming the back surface, and having a cavity that penetrates between the first main surface and the second main surface in the plate thickness direction A silicon substrate, wherein the first main surface and the second main surface have a {100} plane,
An insulating layer formed on the first main surface of the silicon substrate and in the form of closing the cavity, and formed by laminating a plurality of layers;
Of the insulating layer, a heating resistor embedded in a cavity facing part facing the cavity and generating heat by energization;
A diaphragm element comprising:
The silicon substrate is
When the first opening edge on the first main surface side and the second opening edge on the second main surface side of the hollow portion are viewed in the thickness direction, the second opening edge is It is configured to overlap with or be located inside the first opening edge, and
When the surface orientation is a {111} plane starting from the first opening edge and the second opening edge, and the drum-like virtual inner peripheral surface protruding inward is assumed, the cavity portion is A diaphragm element in which an inner peripheral surface that is actually configured is positioned outside the virtual inner peripheral surface. The diaphragm element according to claim 1,
The silicon substrate is
A diaphragm element in which the inner peripheral surface constituting the hollow portion protrudes inward from the first opening edge and the second opening edge. The diaphragm element according to claim 2, wherein
The silicon substrate is
Among the inner peripheral surfaces constituting the hollow portion, the innermost portion located on the innermost side is 3 of the thickness of the silicon substrate from the first main surface toward the second main surface in the plate thickness direction. Diaphragm element formed in a form separated by 1 / min or more. It is a diaphragm element as described in any one of Claims 1-3, Comprising:
Of the insulating layers, the contact insulating layer in contact with the first main surface of the silicon substrate is a diaphragm element made of a material that is not substantially etched by a silicon etching treatment solution for etching the silicon substrate. Silicon made of silicon, having a plate shape having a first main surface and a second main surface forming the back surface, and having a cavity that penetrates between the first main surface and the second main surface in the plate thickness direction A silicon substrate, wherein the first main surface and the second main surface have a {100} plane,
An insulating layer formed on the first main surface of the silicon substrate and in the form of closing the cavity, and formed by laminating a plurality of layers;
Of the insulating layer, a heating resistor embedded in a cavity facing part facing the cavity and generating heat by energization;
A manufacturing method of a diaphragm element comprising:
A contact insulation layer that forms a contact insulation layer made of a material that is not substantially etched by a silicon etching treatment liquid that etches the silicon substrate on the first main surface of the silicon substrate in which the cavity is not formed. Forming process;
After the contact insulating layer forming step, a sacrificial layer is formed on the first main surface of the silicon substrate above a portion facing the cavity facing portion, and a sacrificial layer made of a material etched by the silicon etching treatment solution is formed. A layer forming step;
After the sacrificial layer forming step, a coating that forms a coating insulating layer made of a material that is not substantially etched by the silicon etching treatment liquid in a form that covers at least the entire sacrificial layer on the first main surface side of the silicon substrate. An insulating layer forming step;
After the covering insulating layer forming step, the cavity is formed in the silicon substrate by performing etching once or a plurality of times, the sacrificial layer is removed, and the silicon substrate is removed from the cavity. When the first opening edge on the first main surface side and the second opening edge on the second main surface side are overlapped in the thickness direction, the second opening edge overlaps with the first opening edge, Or it is set as the form located inside this, and the surface orientation is a {111} plane from the 1st opening edge and the 2nd opening edge, and it is a drum-like virtual projecting toward the inside When the inner peripheral surface is hypothesized, a hollow portion forming step in which the inner peripheral surface that actually configures the hollow portion is located outside the virtual inner peripheral surface; and
A method for manufacturing a diaphragm element comprising: A manufacturing method of a diaphragm element according to claim 5,
In the contact insulating layer forming step,
Forming the contact insulating layer on the entire surface of the first main surface;
In the sacrificial layer forming step,
Forming the sacrificial layer on the contact insulating layer;
The cavity forming step includes
A first etching step of etching the silicon substrate from the second main surface side to the first main surface with the silicon etching treatment liquid to form a hole in which the contact insulating layer is exposed; ,
After the first etching step, the first exposed portion of the contact insulating layer exposed in the hole is removed by etching with a contact insulating layer etching treatment solution that etches the contact insulating layer without etching the silicon substrate. A second etching step of exposing the sacrificial layer in the hole;
After the second etching step, a third etching step of etching and removing the entire sacrificial layer with the silicon etching treatment liquid to expose the contact insulating layer and the covering insulating layer in the hole;
After the third etching step, the second exposed portion of the contact insulating layer exposed in the hole is etched away by the contact insulating layer etching treatment solution, and the first main surface of the silicon substrate is placed in the hole. A fourth etching step to be exposed;
And a fifth etching step of etching the silicon substrate from the exposed surface of the first main surface exposed in the hole with the silicon etching treatment liquid after the fourth etching step to form the cavity. A manufacturing method of a diaphragm element. A manufacturing method of a diaphragm element according to claim 5,
In the contact insulating layer forming step,
The sacrificial portion in plan view arranged at a portion of the first main surface facing the cavity facing portion, and the annular peripheral portion in plan view arranged around the sacrificial portion via a gap. Forming a contact insulation layer,
In the sacrificial layer forming step,
Forming the sacrificial layer on the sacrificial portion of the contact insulating layer and on an exposed surface exposed from the contact insulating layer among the first main surface;
The cavity forming step includes
With the silicon etching treatment liquid,
The silicon substrate is etched from the second main surface side until the first main surface is reached, thereby forming a hole exposing the sacrificial layer located inside the sacrificial portion of the contact insulating layer. ,
Further, the etching is continued, the sacrificial layer is removed by etching, the covering insulating layer is exposed in the hole, and the sacrificial portion of the contact insulating layer is bypassed through the portion where the sacrificial layer is removed, The silicon substrate is etched from the side of the first main surface located on the radially outer side of the sacrificial portion of the insulating layer, and the sacrificial portion of the contact insulating layer is released and removed to form the cavity portion. A manufacturing method of a diaphragm element having an etching process.

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