JPS6126828A - Infrared detecting element - Google Patents

Abstract

PURPOSE:To maintain the mechanical strength of a thin film and prevent heat radiation by leaving part of a substrate in a linear or lattice shape. CONSTITUTION:A platinum thin-film electrode 2 is formed on a magnesium oxide substrate 1, a lead titanate thin film 2 is grown, and an NiCr electrode 4 is vapor-deposite thereupon. A groove is formed on the reverse side of the substrate 1 and epoxy resin 5 is pressed in the groove. An opening part 6 is formed of phosphoric acid after the epoxy resin cakes to expose the part 7 formed of only a thin film, manufacturing the infrared detecting element withoug breaking the thin film part. At this time, the width and thickness of a stripe part 8 consisting of part of the substrate 1 are specified to obtain a large output while maintaining the mechanical strength of the thin film 3.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an infrared detection element.

(Conventional configuration and its problems) At room temperature, objects radiate infrared rays that have a peak around a wavelength of 10 μm.The wavelength characteristics of this radiant energy vary depending on the temperature of the object, so it is difficult to radiate from objects. By measuring the infrared energy emitted, the temperature of an object can be measured without contact.

Infrared detectors used for this temperature measurement are broadly classified into quantum type and thermal type. Quantum type has the advantage of fast response speed and high sensitivity, but has the drawback that it requires rhythm using liquid nitrogen or the like and has a strong wavelength dependence of sensitivity. In comparison, thermal detectors have lower sensitivity, but have the advantage of operating at room temperature and having no wavelength dependence on sensitivity. There are two types of thermal type: thermistor type and pyroelectric type. Pyroelectric type has relatively good sensitivity, does not require a bias power source, and is easy to handle. For this reason, a pyroelectric detector with good characteristics is desired as an infrared detector.

Possible forms of the pyroelectric element include single crystal, porcelain, and thin film. A thin film is advantageous in configuring a high-density array sensor, and is also advantageous in that the specific detectability D* can be increased. A pyroelectric thin film is usually formed using an oxide, Si, or the like as a substrate by high-frequency sputtering, vapor deposition, or the like.

Since a pyroelectric infrared detector utilizes temperature rise due to absorption of infrared rays, it is necessary to sufficiently absorb infrared rays and to prevent heat from radiating to the substrate.

To prevent heat dissipation, the substrate can be removed by etching. However, since the thin film is usually formed with a thickness of several micrometers, it is very fragile, and due to the internal strain of the film, it is damaged when the substrate is removed. Furthermore, even if the device is thin, the fact that the substrate remains throughout the device is a major drawback.

(Objective of the Invention) An object of the present invention is to provide a highly sensitive infrared detection element that is easy to manufacture.

(Structure of the Invention) The infrared detection element according to the present invention maintains the mechanical strength of the thin film and prevents heat dissipation as much as possible by leaving a part of the substrate in a striped or grid pattern.

The actual flow side will be explained in detail below with reference to the drawings.

(Description of an embodiment) Fig. 1 shows an embodiment of the present invention, in which a platinum thin film electrode with a thickness of about 0.2 μm is formed on a magnesium oxide substrate 1 with a thickness of 300 μm by sputtering. 2 was formed, then a lead titanate thin film 3 having a thickness of about 2 μm was grown, and a Ni Cr electrode 4 was deposited thereon. Next, grooves were formed at a pitch of one blade by ion beam etching from the back side of the substrate, and then epoxy resin 5 was press-fitted into the grooves. After solidifying the epoxy resin, an opening 6 was formed with phosphoric acid to expose a portion 7 consisting only of a thin film, thereby producing an infrared detecting element without damaging the thin film portion.

The width and thickness of the striped portion 8, which is a part of the substrate, was varied, and changes in the output of the device in response to infrared light irradiated from a blackbody furnace at a temperature of 500 °C were investigated. Figure 2 shows the change in output when the width of the striped portion 8 is constant at 10 μm and the width is changed, and Figure 3 shows the change in output when the width is constant at 100 μm and the thickness is changed. Each is shown in the figure. As is clear from these figures, by holding the thin film with the striped portions, a large output can be obtained while maintaining the mechanical strength of the thin film.

Note that the remaining shape of the substrate may be a lattice shape.

(Effects of the Invention) As described above, according to the present invention 8A, it is possible to provide an infrared detection element that is industrially easy to produce and has excellent characteristics of high sensitivity.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of one embodiment of the present invention, FIG.
b) is a bottom view of the same, and FIG. 2 is a diagram showing changes in the output of the infrared detection element with respect to the width of the striped portion 8 in FIG.
Fig. 3 is a diagram showing the change in the output of the infrared detection element with respect to the thickness of the striped portion 8 in Fig. 1 (the output is relative when the thickness is 100 μm). (relative output with the value of 1 being 1). DESCRIPTION OF SYMBOLS 1... Magnesium oxide substrate, 2... Platinum thin film electrode, 3... Lead titanate thin film, 4... Ni Cr electrode, 5
... Epoxy resin, 6. Opening, 7. Part consisting only of thin film, 8. -- Striped part. Patent applicant: Matsushita Electric Industrial Co., Ltd.
Koshi 6 Go Tsukaji Figure 1 (b)

Claims (1)

[Claims] A thin film infrared detection element is characterized in that a part of the substrate below the light-receiving part is left in a striped or grid pattern and the other part is removed, and the thin film of the element is supported by the remaining part of the substrate. Thin film infrared detection element.