JP2010223600A - Semiconductor pressure sensor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor pressure sensor having a simple structure and manufacturable at low cost, and to provide a method of manufacturing the semiconductor pressure sensor. <P>SOLUTION: The semiconductor pressure sensor for detecting a pressure by a change in a capacitance includes: a first semiconductor substrate 1 to be one electrode of the capacitance; a second semiconductor substrate 2 which forms a diaphragm 7 of a pressure sensing part by being thinned and is to be the other electrode of the capacitance element; and a glass substrate 3 laminated between the first semiconductor substrate 1 and the second semiconductor substrate 2, and forming a space to be a capacitive gap of the capacitance between the first semiconductor substrate 1 and the second semiconductor substrate 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor pressure sensor that detects pressure by electrically detecting deflection of a diaphragm due to pressure applied from the outside, and a method for manufacturing the same.

  Conventionally, as this type of technology, for example, those described in the following documents are known (see Patent Document 1). In this document, two silicon substrates are stacked with a glass substrate serving as an insulating substrate interposed therebetween, and a recess is formed on the back side of the silicon substrate before one silicon substrate is bonded to the glass substrate. An invention of a semiconductor pressure sensor in which a diaphragm serving as a pressure receiving portion of the sensor is formed on one silicon substrate is described.

JP 2001-41837 A

  In the conventional semiconductor pressure sensor, a thin diaphragm serving as a pressure receiving portion of the sensor is formed in advance on the silicon substrate by forming a recess in the silicon substrate before bonding the silicon substrate to the glass substrate by anodic bonding or the like. There was a need. For this reason, it is necessary to form a recess in the silicon substrate to reduce the thickness, resulting in an increase in cost.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a semiconductor pressure sensor that has a simple structure and can be manufactured at low cost, and a manufacturing method thereof.

  In order to achieve the above object, a semiconductor pressure sensor according to the present invention is a semiconductor pressure sensor for detecting pressure by a change in capacitance, and a first semiconductor substrate serving as one electrode of the capacitance, and a thinner wall. The second semiconductor substrate constituting the pressure sensing portion and serving as the other electrode of the capacitance, and laminated between the first semiconductor substrate and the second semiconductor substrate. A first feature is that an insulating substrate is provided which forms a space serving as a capacitance gap of capacitance between the substrate and the second semiconductor substrate.

  The semiconductor pressure sensor according to the present invention is the semiconductor pressure sensor according to the first feature, wherein the electrode wiring connected to the first semiconductor substrate is connected to the first semiconductor via the lead-out port formed in the second semiconductor substrate. The electrode wiring that is drawn out to the second semiconductor substrate or connected to the second semiconductor substrate is drawn out to the first semiconductor substrate side through the lead-out port formed in the first semiconductor substrate. It is characterized by.

  According to a third feature of the semiconductor pressure sensor of the present invention, in the semiconductor pressure sensor of the first or second feature, the capacitance gap of the capacitance is defined by the thickness of the insulating substrate. To do.

  The semiconductor pressure sensor according to the present invention is the semiconductor pressure sensor according to any one of the first to third features, wherein the thickness of the insulating substrate is an anodic bonding between the insulating substrate and the second semiconductor substrate. The fourth feature is that the interval is set such that no discharge occurs in the space of the capacity gap when a high voltage is applied.

  On the other hand, a method for manufacturing a semiconductor pressure sensor according to the present invention includes a first step of forming a recess in an insulating substrate in a method for manufacturing a semiconductor pressure sensor that detects pressure by a change in capacitance, A second step of bonding an insulating substrate having a recess formed in the first step to the first semiconductor substrate serving as one electrode with the opening side of the recess facing the first semiconductor substrate; A third step of polishing one main surface of the substrate to penetrate the recess to form a capacitance gap space of the capacitance, and a second semiconductor substrate serving as the other electrode of the capacitance on the insulating substrate And a fifth step of forming a pressure-sensitive portion that receives pressure by polishing one of the main surfaces of the second semiconductor substrate to reduce the thickness. .

  The method for manufacturing a semiconductor pressure sensor according to the present invention is the method for manufacturing a semiconductor pressure sensor according to the first feature, wherein in the second step, the first semiconductor substrate and the insulating substrate are bonded by anodic bonding. The second feature is that the thickness of the insulating substrate is set to an interval that does not cause discharge in the space of the capacity gap when a high voltage is applied during anodic bonding.

  In the semiconductor pressure sensor having the first feature according to the present invention, the pressure sensor can be easily manufactured, and the manufacturing cost can be reduced.

  In the semiconductor pressure sensor according to the second feature of the present invention, the electrode wiring can be easily drawn out in the same direction.

  In the semiconductor pressure sensor of the third feature according to the present invention, it is possible to easily set the capacitance gap of the capacitance.

  In the semiconductor pressure sensor of the fourth feature according to the present invention, it is possible to prevent discharge at the time of anodic bonding, and to avoid adverse effects due to discharge.

  In the semiconductor pressure sensor manufacturing method according to the fifth aspect of the present invention, the pressure sensor can be easily manufactured, and the manufacturing cost can be reduced.

  In the method for manufacturing a semiconductor pressure sensor according to the sixth aspect of the present invention, it becomes possible to prevent discharge during anodic bonding, and damage due to discharge can be avoided.

It is a figure which shows the structure of the semiconductor pressure sensor which concerns on Example 1 of this invention. It is a figure which shows the other structure of the semiconductor pressure sensor which concerns on Example 1 of this invention. It is process drawing which shows the manufacturing method of the semiconductor pressure sensor which concerns on Example 1 of this invention. It is process drawing which shows the manufacturing method of the semiconductor pressure sensor which concerns on Example 1 of this invention. It is process drawing which shows the manufacturing method of the semiconductor pressure sensor which concerns on Example 1 of this invention.

  Embodiments for carrying out the present invention will be described below with reference to the drawings.

  1A and 1B are diagrams showing a configuration of a semiconductor pressure sensor according to a first embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a cross-sectional view. The semiconductor pressure sensor of Example 1 shown in FIG. 1 functions as a semiconductor pressure sensor that detects a deflection of a diaphragm that receives a pressure applied from the outside as a change in capacitance, and is configured by a semiconductor such as silicon. The semiconductor substrate 1 and the second semiconductor substrate 2, and an insulating glass substrate 3 are provided.

  The first semiconductor substrate 1 constitutes a fixed electrode that functions as one electrode of capacitance, and is connected via an electrode wiring 5a electrically connected to an electrode pad 4a formed on the first semiconductor substrate 1. Are connected to a detection circuit (not shown) for detecting capacitance.

  On the first semiconductor substrate 1, a glass substrate 3 on which through regions 6a and 6b from which glass has been selectively removed is formed is bonded and laminated. One through region 6a formed in the glass substrate 3 forms a space between electrodes facing the capacitance, that is, a capacitance gap, between the first semiconductor substrate 1 and the second semiconductor substrate 2, The other penetrating region 6b constitutes a lead-out port when the electrode wiring 5a connected to the electrode pad 4a of the first semiconductor substrate 1 is drawn out to the second semiconductor substrate 2 side.

  On the glass substrate 3, the second semiconductor substrate 2 is bonded and laminated. In the second semiconductor substrate 2, the substrate is thinned, and a diaphragm 7 is formed as a pressure-sensitive part that detects the pressure by bending with the received pressure, and this diaphragm 7 functions as the other electrode of the capacitance. Configure the electrode. The second semiconductor substrate 2 is connected to the detection circuit touched earlier for detecting the capacitance via the electrode wiring 5b electrically connected to the electrode pad 4b formed on the substrate.

  In such a configuration, when pressure is received by the diaphragm 7, the thin-walled diaphragm 7 is deflected according to the received pressure, and the capacitance between the fixed electrode and the movable electrode changes due to this deflection, and the electrostatic capacitance is changed. A change in capacity is detected electrically to detect pressure.

  In such a structure, since the diaphragm 7 is formed as the second semiconductor substrate 2 whose entire surface is thinned, it is not necessary to form a diaphragm in the semiconductor substrate to form a diaphragm as in the prior art. As a result, the structure is simple and the manufacturing cost can be reduced.

  When joining the 1st semiconductor substrate 1 and the 2nd semiconductor substrate 2 to the glass substrate 3, the anodic bonding which can be simply performed without interposing another joining member is used abundantly. In this anodic bonding, a high voltage of about 500 V to 800 V, for example, is applied between the semiconductor substrate and the glass substrate. At this time, if the distance between the electrodes of the capacity gap is short, discharge easily occurs in this space, and this discharge may cause adverse effects such as poor bonding.

  Therefore, by setting the distance of the capacitance gap to a distance that does not cause discharge according to the applied voltage during anodic bonding, for example, about 20 μ to 50 μ, the semiconductor substrate and the glass substrate are short-circuited when high voltage is applied. It is possible to avoid discharge without providing a short-circuit wiring (discharge prevention wiring) that prevents the discharge. This eliminates the need for short-circuit wiring and avoids the complexity of the structure. In addition, a manufacturing process such as forming a short-circuit wiring or cutting the short-circuit wiring after the semiconductor substrate and the glass substrate are joined becomes unnecessary, and the manufacturing process can be simplified and the manufacturing cost can be reduced.

  The distance of the capacity gap is set in advance based on the result of an experiment or the like. For example, based on the conventionally known Paschen's law indicating the relationship between the distance between the electrodes and the discharge voltage, It is set accordingly.

  Further, in the structure shown in FIG. 1, the diaphragm 7 is provided on the upper side with respect to the surface on which the semiconductor pressure sensor is installed, and the electrode wirings 5a and 5b are drawn on the upper side, but the structure shown in FIG. 1 is a plan view, and FIG. 1B is a cross-sectional view. As in FIG. 1, the electrode wires 5a and 5b are drawn upward with respect to the installation surface, while a diaphragm 7 is provided on the lower side. It may be a type that receives pressure from the side.

  Next, a method of manufacturing the semiconductor pressure sensor shown in FIG. 1 will be described with reference to FIG. 3 (FIGS. 3-A, 3-B, and 3-C) showing the manufacturing process.

  First, an insulating glass substrate 3 such as borosilicate glass is prepared (FIG. 3A (a (cross-sectional view))), a through region 6a serving as a capacitance gap of capacitance, and a lead-out port of the electrode wiring 5a; The portion of the glass to be the through region 6b is deeply removed and selectively removed to form the recesses 31a and 31b (FIG. 3-A (b1 (plan view), (b2 (cross-sectional view))).

  On the other hand, a first semiconductor substrate 1 made of a semiconductor such as silicon is prepared (FIG. 3-A (c (cross-sectional view))), and an electrode pad 4a is formed of a metal such as aluminum (FIG. 3-A (d1 ( Plan view)), (d2 (sectional view))).

  Thereafter, the first semiconductor substrate 1 and the glass substrate 3 are overlapped, and a high voltage of about 500 V to 800 V is applied between the first semiconductor substrate 1 and the glass substrate 3 to anodic bond them (see FIG. 3-A (e (sectional view))). At the time of this anodic bonding, the depth of the recesses 31a and 31b is set to, for example, about 20 to 50 μm as described above, whereby discharge in the recesses 31a and 31b can be avoided when a high voltage is applied.

  Next, the surface of the glass substrate 3 bonded to the first semiconductor substrate 1 is polished and removed, and the recesses 31a and 31b are penetrated to the surface side to form the through regions 6a and 6b (FIG. 3-B (f1 (Plan view)), (f2 (sectional view))). In this polishing step, the thickness of the glass substrate 3 is adjusted by adjusting the amount of polishing of the glass substrate 3, and the capacitance value is set to a predetermined value by setting a predetermined interval between the electrodes of the electrostatic capacitance. Set.

  On the other hand, a second semiconductor substrate 2 made of a semiconductor such as silicon is prepared (FIG. 3-B (g (cross-sectional view))), and the glass substrate 3 is bonded to one main surface of the second semiconductor substrate 2. The joining member 32 according to the joining method used for is formed. The joining member 32 is made of, for example, low-melting glass, polymer, gold (Au), or the like (FIG. 3-B (h (sectional view))).

  Thereafter, an atmosphere of temperature and pressure suitable for each bonding is set by sputtering in the case of low melting point glass, adhesion in the case of polymer, or eutectic bonding in the case of Au, and the second semiconductor substrate. 2 and the glass substrate 3 are joined (FIG. 3-B (i (cross-sectional view)). Note that anodic bonding may be used for this bonding.

  Next, the entire surface on the other main surface side of the second semiconductor substrate 2 is polished to reduce the thickness and reduce the thickness (FIG. 3B (j (cross-sectional view)). Subsequently, after the electrode pad 4b is formed on the surface of the second semiconductor substrate 2 (FIG. 3-C (k1 (plan view), (k2 (cross-sectional view))), the diaphragm 7 and the diaphragm 7 and the electrode pad 4b are formed. The second semiconductor substrate 2 is selectively removed by etching so as to leave a region for electrically connecting the two to form a diaphragm 7 (FIG. 3-C (l1 (plan view), (l2 (cross-sectional view))) Finally, although not shown, a large number of chips formed on the wafer are divided into individual chips by dicing to complete a semiconductor pressure sensor, and when this chip is mounted, electrode wiring is applied to each electrode pad 4a, 4b. 5a and 5b are connected.

  As described above, in the above manufacturing method, the glass substrate 3 laminated between the first semiconductor substrate 1 serving as the fixed electrode and the second semiconductor substrate 2 serving as the movable electrode is polished to obtain the capacitance. By forming the space of the capacitance gap, the capacitance of the pressure sensor can be easily formed. Further, by polishing and thinning the second semiconductor substrate 2, it is possible to easily form the diaphragm of the pressure sensitive part. Thereby, the manufacturing method of the semiconductor pressure sensor can be simplified, and the manufacturing cost can be reduced. Furthermore, it becomes possible to set the space | interval between the electrodes of an electrostatic capacitance according to the grinding | polishing amount of the glass substrate 3, and can control the value of an electrostatic capacitance easily.

  On the other hand, in the step of anodic bonding of the glass substrate 3 to the first semiconductor substrate 1, by using the glass substrate 3 having a recess dug to a depth that does not cause discharge, a recess space when a high voltage is applied. It is possible to prevent the discharge at the point of time, and the adverse effects such as poor bonding due to the discharge can be avoided.

DESCRIPTION OF SYMBOLS 1 ... 1st semiconductor substrate 2 ... 2nd semiconductor substrate 3 ... Glass substrate 4a, 4b ... Electrode pad 5a, 5b ... Electrode wiring 6a, 6b ... Through region 6b ... Through region 7 ... Diaphragm 31a, 31b ... Recess 32 Joining member

Claims (6)

In a semiconductor pressure sensor that detects pressure by a change in capacitance,
A first semiconductor substrate serving as one electrode of the capacitance;
A second semiconductor substrate that is thinned to form a pressure-sensitive portion and serves as the other electrode of the capacitance;
A space is formed between the first semiconductor substrate and the second semiconductor substrate to form a capacitance gap of the capacitance between the first semiconductor substrate and the second semiconductor substrate. And a semiconductor pressure sensor. The electrode wiring connected to the first semiconductor substrate is drawn out to the second semiconductor substrate side through a lead-out port formed in the second semiconductor substrate, or connected to the second semiconductor substrate. 2. The semiconductor pressure sensor according to claim 1, wherein the electrode wiring is drawn out to the first semiconductor substrate side through a lead-out port formed in the first semiconductor substrate. The semiconductor pressure sensor according to claim 1, wherein a capacitance gap of the capacitance is defined by a thickness of the insulating substrate. The thickness of the insulating substrate is set to an interval that does not cause a discharge in the space of the capacitance gap when a high voltage is applied when the insulating substrate and the first semiconductor substrate are anodic bonded. The semiconductor pressure sensor according to claim 1, wherein the pressure sensor is a semiconductor pressure sensor. In the manufacturing method of the semiconductor pressure sensor for detecting the pressure by the change in capacitance,
A first step of forming a recess in the insulating substrate;
A first semiconductor substrate serving as one electrode of capacitance is bonded to an insulating substrate having a recess formed in the first step with an opening side of the recess facing the first semiconductor substrate. Two steps;
A third step of polishing one main surface of the insulating substrate to penetrate the concave portion to form a capacitance gap space of capacitance;
A fourth step of bonding a second semiconductor substrate serving as the other electrode of the capacitance to the insulating substrate;
And a fifth step of forming a pressure-sensitive portion that receives pressure by polishing one main surface of the second semiconductor substrate to make it thinner. In the second step, the first semiconductor substrate and the insulating substrate are bonded by anodic bonding, and the thickness of the insulating substrate is determined in the space of the capacitance gap when a high voltage is applied during anodic bonding. 6. The method of manufacturing a semiconductor pressure sensor according to claim 5, wherein the interval is set such that no discharge occurs.

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