JP2003121403A - Sensor device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost of a humidity sensor. SOLUTION: This device has pads 133, 153 formed respectively as follows: an oxide film 102 is formed on the surface on one side of a silicon substrate 101; a ground electrode 103 is formed on the oxide film 102; an organic insulating layer 104 is formed on the ground electrode 103; an upper electrode 105 is formed on the organic insulating layer 104; and the ground electrode 103 and the upper electrode 105 are formed in the noncontact state mutually. Solderable metal layers 134, 154 are formed on the upper surfaces of the pads 133, 153.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor device such as a humidity sensor and a manufacturing method thereof.

[0002]

2. Description of the Related Art Various types of humidity sensors have been proposed. One of them has a capacitor formed by sandwiching an organic insulating layer between two electrodes. There is one that utilizes the fact that the capacitance changes due to the attachment of water to the. An example of this type of humidity sensor is shown in FIGS. 4 (a) and 4 (b).

This humidity sensor has a sensor die 10 and a ceramic substrate 11. In the sensor die 10, the oxide film 2 is formed on one surface of the silicon substrate 1. A base electrode 3 made of, for example, aluminum is formed on the upper surface of the oxide film 2. The base electrode 3 includes a wire bond pad portion 33. The organic insulating layer 4 functioning as a dielectric is fixed to the upper surface of the base electrode 3. An upper electrode 5 made of, for example, aluminum is fixed to the upper surface of the organic insulating layer 4. This upper electrode 5
Also has a wire bond pad portion 53.

On the upper surface of the ceramic substrate 11, two solder pads 14, 14 and two gold pads 12, 12 connected to these solder pads 14 are formed as print pattern electrodes, respectively. Ceramic substrate 11
The sensor die 10 is adhered to the upper surface of the above, and is bonded to the gold pad 12 from each wire bond pad portion 33, 53 by the bonding wire 13. The terminal leads 8 and 8 are soldered to the solder pads 14 and 14.

[0005]

In the above sensor device, a defect is likely to occur in the bonding between the wire bond pad portions 33 and 53 and each gold pad 12, and the defect occurrence rate is about 10%, for example. There was a hindrance to cost reduction. Further, the cost of the ceramic substrate 11 is almost equal to the cost of the sensor die 10 when the printing process and the wire bonding are included,
This also largely hindered the cost reduction of the sensor device.

It is an object of the present invention to provide a sensor device and a manufacturing method thereof, which eliminates the occurrence of defects, improves the yield, and rationalizes the components other than the sensor die to reduce the cost. To do.

[0007]

A sensor device according to the present invention, such as a humidity sensor, comprises a silicon substrate, an oxide film formed on one surface of the silicon substrate, and a base electrode formed on the oxide film. An organic insulating layer formed on the base electrode and an upper electrode formed in the organic insulating layer shape are provided. The base electrode and the upper electrode have pad portions formed in a non-contact state with each other. The base electrode, the upper electrode, and both pad portions are formed of a metal that cannot be soldered. These pad parts are, for example,
The base electrode and the upper electrode may be projected substantially in parallel from the same direction. A solderable metal layer is formed on the upper surfaces of these pads.

Terminal metals may be soldered on the both metal layers.

In the method of manufacturing a sensor device such as a humidity sensor according to the present invention, a base electrode having a protrusion as a pad portion is formed on the oxide film formed on the surface of a silicon substrate by vapor deposition or sputtering. . An organic insulating layer is fixed to the upper surface of the base electrode other than the protrusion. On the upper surface of this organic insulating layer, an upper electrode having a protrusion as a pad is formed by vapor deposition or sputtering. The base electrode and the upper electrode are made of metal that cannot be soldered. A solderable metal layer is formed on the upper surface of each of the protrusions by a vapor deposition method.

Further, terminal leads can be soldered to the solderable metal layer.

If the terminal lead can be directly soldered to the wire bond pad portion by eliminating the wire bonding step, the yield can be improved and the ceramic substrate is not necessary. However, the base electrode and the upper electrode, including the wire bond pad portion, are made of a metal that cannot be soldered, and the terminal lead cannot be soldered. Therefore, a solderable metal layer is formed on the base electrode and the upper electrode to form a soldering pad portion. by this,
It has become possible to significantly reduce the process and delete parts.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A sensor device according to an embodiment of the present invention, for example, a humidity sensor has a silicon substrate 101 as shown in FIGS. 1 (a) to 1 (c). The silicon substrate 101 has a thickness of, for example, about 290 mm,
It is a flat plate having a size of about 5 mm square. On one surface,
An oxide film 102 is formed on the entire area.

The base electrode 10 is formed on the upper surface of the oxide film 102.
3 is formed. The base electrode 103 is formed of a metal that cannot be soldered, such as aluminum. The size of the base electrode 103 is, for example, 3 mm square. A protrusion 133 is formed as a pad on one side of the base electrode 103. The protrusion 133 is formed on one corner side of the one side, substantially perpendicular to the side, and integrally with the base electrode 103. The protrusion 133 has a width of about 1 mm and a length of about 1 mm, for example.

An organic insulating layer 104 is fixed to the entire upper surface of the base electrode 103. This organic insulating layer 104
As the material, a polymer resin such as a polyimide resin can be used. The thickness of the organic insulating layer 104 is several microns,
For example, it can be 3 microns.

An upper electrode 105 is fixed to the upper surface of the organic insulating layer 104. The upper electrode 105 is also made of a metal that cannot be soldered, such as aluminum. The upper electrode 105 is formed so as not to protrude from the periphery of the organic insulating layer 104, for example, about 2.
It is a 6 mm square. The upper electrode 105 is formed, for example, as a mesh electrode or a flat plate that penetrates a myriad of holes, and the outside air contacts the organic insulating layer 104 through these meshes or holes. One side of the upper electrode 103, for example, the protrusion 13
The protrusion 133 is provided on the same side as the side on which 3 is provided.
The protrusion 153 is formed so as not to come into contact with. For example, the protrusion 153 is provided at a corner opposite to the corner where the protrusion 133 is provided, substantially parallel to the protrusion 133, and the upper electrode 1.
It is formed integrally with 05. The width of the protrusion 153 is about 1
mm, and the length is about 1.2 mm.

On the upper surfaces of the protrusions 133 and 153, a metal layer 1 made of a solderable metal, for example, nickel.
34 and 154 are formed. Protrusion 133 and metal layer 1
And the soldering pad portion 132 and the protrusion 153.
And the metal layer 154 form the soldering pad portion 152,
Each is formed.

In this humidity sensor, for example, as shown in FIG. 2A, after forming an oxide film 102 on the upper surface of a silicon substrate 101, an aluminum vapor deposition method or a sputtering method is used.
The base electrode 103 and the protrusion 133 are formed. Next, as shown in FIG. 3B, the organic insulating layer 104 is formed on the upper surface of the base electrode 103. As shown in FIG. 3C, the upper electrode 105 and the protrusion 153 are formed on the upper surface of the organic insulating layer 104 by aluminum vapor deposition or sputtering. As shown by hatching in FIG. 3D, metal layers 134 and 154 are formed on the upper surfaces of the protrusions 133 and 153 by vapor deposition of nickel, whereby the humidity sensor of the terminal leadless is completed. .

In the sensor device constructed as described above, since the solderable metal layers 134 and 154 are formed on the upper surfaces of the protrusions 133 and 153, there is no need to form terminal pads by wire bonding. . Therefore,
Yield does not decrease due to defective wire bonding. Moreover, it is not necessary to use a ceramic substrate provided with gold pads and wire bonding pads. The combination of these can reduce the cost.

FIG. 3 shows a sensor device of the second embodiment, for example, a humidity sensor. In this humidity sensor, the organic insulating layer 104 is formed only at a position slightly inside the peripheral portion of the base electrode 103, and the metal layer 1
The sensor device has the same configuration as that of the sensor device shown in FIGS. 1 and 2, except that the terminal leads 108 and 108 are soldered to the upper surfaces of 34 and 154. The same parts are designated by the same reference numerals and the description thereof will be omitted. Terminal leads 108, 1
08 is soldered on the metal layers 134 and 154 after the metal layers 134 and 154 are formed. This completes the sensor device with terminal leads.

Although nickel is used as the solderable metal in the above embodiment, other metals can be used.

[0021]

As described above, according to the present invention, the cost of the sensor device is as follows: the step of printing the conventional pattern electrode to process the ceramic substrate, the step of adhering the sensor die to the ceramic substrate, the wire. No bonding process is required, and the material cost is reduced by about half. Moreover, the occurrence of defects due to wire bonding is eliminated, and the yield is improved. Further, the bonding wire, which is likely to occur during use of the sensor device, is not cut.

[Brief description of drawings]

1A is a plan view of a sensor device according to a first embodiment of the present invention, FIG. 1B is a sectional view taken along line bb of FIG.
(C) is sectional drawing which follows the cc line of (a).

FIG. 2 is a diagram showing a manufacturing process of the sensor device of FIG.

FIG. 3 is a plan view of a sensor device according to a second embodiment.

FIG. 4A is a plan view of a conventional sensor device,
(B) is sectional drawing which follows the bb line | wire of (a).

[Explanation of symbols]

101 Silicon substrate 102 oxide film 103 Base electrode 104 organic insulating layer 105 upper electrode 135 Projection 134 Metal layer 153 Projection 154 metal layer

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Claims (4)

[Claims] 1. A silicon substrate, an oxide film formed on one surface of the silicon substrate, a base electrode formed on the oxide film, an organic insulating layer formed on the base electrode, An upper electrode formed on the insulating layer,
The sensor device in which the base electrode and the upper electrode have pad portions formed in a non-contact state with each other, and a solderable metal layer is formed on the upper surfaces of the pad portions. 2. The sensor device according to claim 1, wherein terminal metals are soldered on the both metal layers. 3. A step of forming a base electrode having a protrusion as a pad by an evaporation method or a sputtering method on an oxide film formed on the surface of a silicon substrate, and an upper surface of the base electrode other than the protrusion. A step of fixing the organic insulating layer, a step of forming an upper electrode having a protrusion as a pad portion on the upper surface of the organic insulating layer by an evaporation method or a sputtering method, and an upper surface of both the protrusions. And a step of forming a solderable metal layer by vapor deposition. 4. The method of manufacturing a sensor device according to claim 3, further comprising the step of soldering a terminal lead to the solderable metal layer.