JPS622573A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To check destruction, and to contrive to enlarge the application extent of a semiconductor pressure sensor by a method wherein the surface of a second substrate facing a diaphragm is provided at the position to check deformation of a fixed quantity or more by coming in contact with the diaphragm when the diaphragm is deformed by a fixed quantity or more. CONSTITUTION:A second silicon substrate 5 having a projection 6 is manufactured by performing etching to a uniform silicon substrate according to acid liquid using a mask of size the same with the top part of the projection 6. A silicon substrate 1 and the silicon substrate 5 are adhered mutually at an adhering part 7 Accordingly, even when pressure of the specification or more or abnormal pressure is applied thereto, deformation of a diaphragm 2 is suppressed by the projection 6, namely deformation of a fixed quantity or more is suppressed by coming in contact of the diaphragm 2 with the projection 6, and deformation to result in destruction is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of Momito] [The present invention relates to a semiconductor pressure sensor provided with a limiter.

[Conventional technology]

Pressure sensors are used to detect gas pressure in gas maintenance of communication cables, and to detect horizontal and narrow flow rates in chemical plant pipelines.
It is used in a variety of applications, including air data collection for control purposes and aircraft flight control. And especially in recent years, small size and high precision.

Semiconductor pressure sensors, which are characterized by high-speed response, are beginning to be widely used. A conventional semiconductor pressure sensor has a structure as shown in FIG. is thermally diffused to form the piezoresistive element 8. 4 is a case that holds the silicon substrate l. This pressure sensor emits pressure by assembling piezoresistive elements 8 in a bridge shape on a diaphragm z.

[Problem that the invention seeks to solve]

By the way, the above-mentioned semiconductor pressure sensor has many points such as being easy to manufacture, being small and having good time travel, but its fundamental drawback is that it does not have a limiter. It is. For example, if the pressure exceeds a certain value, the diaphragm 2 will break and will no longer function as a cell. In other words, the pressure cannot be controlled. Due to these drawbacks, the scope of use has been narrowed, and it has been impossible to use it as a pressure sensor in important steps of a manufacturing line.

The present invention takes issue with the problem of sensor destruction at a constant pressure or higher, which is seen in conventional pressure sensors.

[Means for Solving the Problems] The present invention provides a first silicon substrate having a diaphragm formed in a part thereof and a piezoresistive element formed on the surface of the diaphragm, and a first silicon substrate formed on the first silicon substrate. a second substrate bonded with a portion facing the diaphragm, the surface of the second substrate facing the diaphragm being in contact with the diaphragm when the core diaphragm undergoes constant deformation; The diaphragm is characterized in that it is located at a position that prevents deformation of the diaphragm by a certain amount or more.

The difference from conventional semiconductor pressure sensors is that by using the second substrate as a limiter, deformation of the diaphragm is suppressed to a constant level even when abnormal pressure is applied, and destruction does not occur.

[Example l]

FIG. 1 is a diagram showing a first implementation v1 of the present invention,
is a silicon substrate (first silicon substrate), 2 is a diaphragm, 8 is a piezoresistive element, 4 is a holding case, 5 is a silicon substrate (second substrate), 6 is a projection provided on the silicon substrate 5, 7 is the bonded portion between the silicon base [1 and the silicon substrate 5].

The manufacturing method and operation of the diaphragm 2 and the piezoresistive element 8 provided on the silicon substrate 1 are the same as the operation of method 1 described in the prior art section, so the explanation thereof will be omitted.

The protrusions 6 are made by etching or grinding the silicon substrate 5. In the case of n1 etching, for example, the protrusions are etched by etching a uniform silicon substrate with an acidic solution using a mask of the same size as the top of the protrusions 6. 6
A silicon substrate 5 having the following can be manufactured. silicon substrate l
and silicon substrate 2 are in contact with each other at an adhesive portion 7. For adhesion, a high-precision adhesion method (for example, Japanese Patent Application No. 60-082609)
By using the semiconductor substrate bonding method provided in the above issue, the parallel accuracy of the bonded portion can be reduced to 1/10 μm or less.

As mentioned above, since the diaphragm 2 has a structure in which the protrusion O is provided below, the deformation of the diaphragm 2 is suppressed by the protrusion 6 even if it is subjected to pressure exceeding the standard value or normal pressure. That is, the diaphragm 2 comes into contact with the protrusion 6, and deformation beyond a certain amount is suppressed, and deformation that would lead to destruction does not occur.

FIG. 1 shows the relationship between pressure and deformation of the diaphragm 2 in the pressure sensor of the present invention. As shown in the figure, the deformation becomes constant above a certain pressure and no further deformation occurs.

As is clear from these results, the protrusion 6 acts as a limit against the deformation of the diaphragm, and the structure is safer against pressure than in the conventional technology.

[Implementation row 2] FIG. 3 is an explanatory diagram showing the second embodiment, in which 8 is a silicon substrate, ■ is a diaphragm, 10 is a recess in the upper part of the silicon substrate 8, 1 is a recess in the lower part of the silicon substrate, 12 is a piezoresistive element, and 1B is a holding case. In this embodiment, a deep recess lO and a shallow recess 11 are formed by etching the silicon substrate 8 from above and below.

When abnormal pressure is applied, the deformation of the diaphragm 0 is suppressed by the holding case 18, and the relationship between the n1 diaphragm 9 and the pressure is as shown in FIG. 2, the same as in the first embodiment. The formation of the piezoresistive element 12 is the same as that of the first embodiment or the prior art, and its explanation will be omitted. Moreover, it is easy to think that the operation and effect are the same as those of the first embodiment.

[Embodiment 8] Figure φ is an explanatory diagram showing the third embodiment, in which 14 is a silicon substrate, 15 is a silicon base [a recess provided on the lower surface of 9 of 14, and 16 is a silicon substrate that is initially integrated with the silicon substrate 14]. Silicon removed from silicon 4IE14 with nine silicon,
17 is a piezoresistive element, and 18 is a holding case. In this example, a shallow recess L5 is formed in the lower part of the silicon substrate 14 by etching, the upper surface of the silicon substrate 14 is etched or ground to remove the silicon 16, and then the piezoresistive element 17 is formed. , is held in a holding case 18, and the holding case 18 suppresses abnormal deformation of the diaphragm. The effects and false effects are the same as in the previous embodiment, and their explanation will be omitted.

The above explanation is based on one silicon chip. However, in general semiconductor products, processing is performed as a single wafer, and immediately before being held in the holding case 18, it is cut into chips and held in the holding case 18. This method is used in the present invention, and it is easier to mass-produce the present invention by using such a manufacturing method.

It goes without saying that the silicon substrate and the holding case can be bonded to each other with high precision by using the bonding method described above.

〔Effect of the invention〕

According to the present invention, since the substrate facing the diaphragm has a limiter function, the deformation of the sensor in response to pressure is suppressed, and the deformation is prevented when pressure exceeding a specified value or abnormal pressure is applied to the sensor. It has the advantage of not breaking down to a certain value of 1, and can greatly expand the range of application of semiconductor pressure sensors.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a semiconductor pressure sensor shown as a first embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between pressure and deformation of the sensor, and fsJ diagram is a diagram showing the relationship between pressure and deformation of the sensor. FIG. 9 is a schematic configuration diagram of a semiconductor pressure sensor shown as a third embodiment of the present invention, and FIG. S is a schematic configuration diagram of a conventional semiconductor pressure sensor. . 1.8.14...First silicon substrate, z, 9
...Diaphragm, 8. L2,1?・・・・・・
・Piezoresistance element, 4.18.18... Holding case, 5... Second substrate (silicon substrate), 6
······protrusion.

Claims (3)

[Claims] (1) A first silicon substrate on which a diaphragm is formed and a piezoresistive element formed on the surface of the diaphragm; a second substrate, the surface of the second substrate facing the diaphragm is at a position where the surface of the second substrate that is opposed to the diaphragm comes into contact with the diaphragm when the diaphragm is deformed by a certain amount to prevent the diaphragm from being deformed by more than a certain amount; A semiconductor pressure sensor characterized by being located at. (2) A second silicon substrate having protrusions is adhered to the first silicon substrate, and the protrusions of the second silicon substrate and the diaphragm of the first silicon substrate are opposed to each other. The semiconductor pressure sensor according to item 1. (3) A first silicon substrate and a case holding the first silicon substrate are bonded to the first silicon substrate as a second substrate, and a diaphragm of the first silicon substrate and a part of the case are bonded together. 2. The semiconductor pressure sensor according to claim 1, wherein the semiconductor pressure sensor is arranged to face each other.