JPH0734333U - Thermal infrared sensor - Google Patents

Abstract

(57) [Summary] [Object] To provide a thermal infrared sensor that can be manufactured by a method that does not use a black body mask and therefore does not require alignment work. A thin film support 3 is disposed on the surface of a heat sink substrate 4, a heat sensitive portion 1 is disposed on a part of the surface of the thin film support 3, and the heat sink substrate material immediately below the heat sensitive portion 1 is removed. A thermal infrared sensor having a structure forming a cavity 5, wherein a black body layer 2 deposited on the side wall surface of the cavity 5 and the back surface of the thin film support 3 exposed by the formation of the cavity 5 is formed. To have.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal infrared sensor. The thermal infrared sensor may be abbreviated as a sensor in this specification.

[0002]

[Prior art]

 FIG. 3 shows a thermopile as an example of a conventional thermal infrared sensor. Reference numeral 1 is a heat sensitive portion, and in this example, the hot junction portions of the thermocouple are gathered together. Reference numeral 2 denotes a black body layer, which is adhered to the upper portion of the heat sensitive portion 1 via an insulating layer 8. The thermocouple is composed of two kinds of metals, thermocouple materials 6a and 6b, and a connecting metal 7 connects the thermocouple materials 6a and 6b in series. The thermocouple materials 6a and 6b and the connecting metal 7 are formed by sequentially performing vapor deposition and patterning by a normal photolithography method. A thin film support 3 is a multi-layered film including a silicon oxide (SiO2) film deposited by the CVD method and a silicon nitride film also deposited thereon by the CVD method. Reference numeral 4 denotes a heat sink base plate made of silicon, and a cavity 5 is formed in a portion immediately below the heat sensitive portion 1 so that heat given to the heat sensitive portion 1 does not escape to the heat sink substrate 4. The cavity 5 has an opening at the lower end in the figure, and the thin film support 4 is exposed at the upper end. Reference numeral 10 is a Cr layer formed by vapor deposition on the lower surface of the heat sink substrate 4 excluding the opening of the cavity 5, and 11 is an Au layer also formed on the surface of the Cr layer 10 by vapor deposition.

In the conventional thermal infrared sensor, a black body layer 2 mainly made of a metal is formed on the heat sensitive portion 1 for the purpose of absorbing the infrared rays and converting it into heat after forming the heat sensitive portion 1 as shown in FIG. Is formed. In this case, it is necessary that the black body layer 2 is applied evenly to the heat-sensitive part 1 and is not applied to the connection part with the external extraction electrode. Therefore, as shown in FIG. It is necessary to align the body mask 15 with the heat sensitive portion 1. 4, the same reference numerals as those in FIG. 3 indicate the same or corresponding ones, 15 is a black body mask used as a shadow mask during black body vapor deposition, and 16 is an opening pattern of the black body mask 15. Since the black body layer 2 is formed on the heat sensitive portion 1, the alignment work is performed in a manner that the black body mask 15 is placed in the direction of the arrow in the figure so that the opening pattern 16 overlaps the heat sensitive portion 1. .

[0004]

[Problems to be solved by the device]

 It is difficult to make a large number of small sensors by the conventional manufacturing method because high accuracy is required for the alignment between the black body mask and the workpiece. Also, the blackbody layer was easily damaged, and handling was difficult until the assembly and sealing were completed. It is possible to form a black body layer by photolithography without using a black body mask, but this is not a good measure because it is costly and the number of steps increases, which increases the chances of the black body layer breaking. An object of the present invention is to provide a thermal type infrared sensor which can be manufactured by a method which does not use a black body mask and thus does not require an alignment work.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a thin film support on the surface of a heat sink substrate, a heat sensitive part is provided on a part of the surface of the thin film support, and a heat sink substrate material directly under the heat sensitive part. A thermal infrared sensor having a structure in which a cavity is removed to form a cavity, wherein a black body deposited on the side wall surface of the heat sink substrate of the cavity and the back surface of the thin film support exposed by the cavity formation. It is configured to include.

[0006]

[Action]

 With the above configuration, the black body is located in the recess of the sensor and is less likely to be affected by external force.

In addition, the fine structure of the black body layer is such that thin filaments of the black body material are deposited in a frost column shape almost perpendicularly to the surface to be adhered, and the heat conduction in the direction parallel to the surface to be adhered is extremely vertical. It was confirmed experimentally that it was small, and the effect of releasing the heat of the heat-sensitive part to the heat sink was extremely small.

[0008]

Embodiment FIG. 1 is a view showing an embodiment of the present invention. FIG. 1A shows a plan view, and FIG. 1B shows a cross section taken along the line AA of FIG. In this figure, the same reference numerals as those in FIGS. 3 and 4 indicate the same or corresponding ones, and 9 indicates a contact hole. As shown in the figure, the black body layer 2 is deposited on the sidewall surface of the heat sink substrate in the cavity 5 and the back surface of the thin film support 3 exposed by the cavity 5. Next, an example of the manufacturing method of the present embodiment will be described with reference to FIGS.

First, a (100) plane of Si was cut out, and a silicon nitride film was first deposited by a CVD method on a wafer 14 whose both surfaces were mirror-finished, and then SiO 2 was deposited on one surface thereof by a CVD method. After that, a silicon nitride film is again deposited in the same manner as above to form the thin film support 3.

Next, by sequentially depositing and patterning Bi2Te3 and Sb2Te3, a large number of sets of thermocouple materials 6a and 6b are arranged substantially radially (FIG. 1 (a)) and the connecting metal 7 is used to form each thermocouple material. Ohmic connection is made so that is connected in series. A vapor deposition film of gold is used as the connecting metal 7 and is patterned by the so-called lift-off method.

For the purpose of protecting the above-mentioned processed portion, a SiO 2 film is deposited by a CVD method to form an insulating layer 8 and is connected to the outside. The contact hole 9 in the pad portion is patterned.

Since the cavity 5 is formed by selectively etching Si from the rear surface of the surface provided with the sensor part in which a large number of the above thermocouple materials are connected in series, a photoresist is applied to the rear surface and alignment is performed with a double-sided aligner. Then, after leaving the photoresist in a portion corresponding to the opening (etching hole) of the cavity 5, Cr and Au are vapor-deposited on the entire back surface, and Cr and Au are vapor-deposited together with the photoresist by the lift-off method. The layer is removed to expose the Si surface of the portion to be etched, and the other portion forms a surface covered with the vapor deposition layer of the Au layer 11 on which the Cr layer 10 is a base.

The surface of the Si wafer 14 on which the sensor portion is provided is coated with acid-resistant wax and attached to a stainless steel plate (not shown), and Si is etched with a mixed solution of nitric acid and hydrofluoric acid to support a thin film. Obtain the cavity 5 by reaching the body 3.

Subsequently, a black body (Bi black) layer 2 made of bismuth was formed to a thickness of 10 to 20 μm by a vapor deposition method as shown in FIG. The Bi black is removed by rubbing the surface with Bi black on the back of the screen.

After removing the excess Bi black as described above, the individual sensors 13 aligned on the wafer 14 are cut using a dicing saw (FIG. 2B), and then adhered to the stainless plate. The acid-resistant wax serving as an agent is dissolved and removed by a solvent, and the individual sensors 13 are separated and taken out to obtain the sensor of this embodiment.

The sensor of this embodiment is usually used as a sensor module by die-bonding a hermetic sealing header such as TO-5 with silver paste and electrically sealing a cap with a Si filter in an N 2 atmosphere to hermetically seal.

Although the thermopile has been described as an example in the embodiments, it is obvious that other sensors such as a bolometer and a pyroelectric element may be used.

[0018]

[Effect of device]

 Since the present invention has a black body deposited on the surface of the cavity side wall and the surface of the thin film support exposed by the cavity, the thermal infrared sensor of the present invention is used as described in the embodiments. A method of depositing a black body on the entire surface without using a black body mask and removing unnecessary portions can be used for manufacturing, and since a patterning process such as photolithography is not used, a conventional black body layer is formed in a predetermined manner. The mask alignment for depositing at the position is unnecessary, and the cost can be reduced.

Further, in the thermal infrared sensor of the present invention, since the black body layer is in the cavity, that is, in the recess, it may be damaged by an external force such as mechanical force contact during handling of the sensor such as transportation. Almost never. The same can be said in the process of manufacturing the present invention (after black body deposition). Therefore, it is possible to provide a thermal infrared sensor having a high yield and a low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of an embodiment of the present invention.

FIG. 3 is a diagram showing a conventional thermal infrared sensor.

FIG. 4 is a diagram showing a mode of alignment of a black body mask which is conventionally required.

[Explanation of symbols] 1. Heat sensitive part 2. Black body layer 3. Thin film support 4. Heat sink substrate 5. Cavities 6a, 6b. Thermocouple material 7. Connection metal 8. Insulating layer 9. Contact hole 10. Cr layer 11. Au layer 12. Sensor element 13. Sensor 14. Wafer 15. Black body mask 16. Opening pattern

Claims (1)

[Scope of utility model registration request] 1. A thin film support is provided on the surface of a heat sink substrate, a heat sensitive portion is provided on a part of the surface of the thin film support, and the heat sink substrate material immediately below the heat sensitive portion is removed, A thermal infrared sensor having a structure forming a barrel, comprising a black body deposited on a sidewall surface of a heat sink substrate of the cavity and on a back surface of the thin film support exposed by the cavity formation. Thermal infrared sensor.