JP2016057299A - Pyroelectric sensor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pyroelectric sensor capable of improving absorption efficiency of infrared and reducing warp of a pyroelectric material and a method for manufacturing the same.SOLUTION: A pyroelectric sensor includes: a pyroelectric material 11; an upper surface electrode 13 that is formed on the upper surface of the pyroelectric material 11 and takes out a signal; a first infrared absorption film 14 that is formed on the upper surface of the upper surface electrode 13 and absorbs infrared; a lower surface electrode 15 that is formed on the lower surface of the pyroelectric material 11 and takes out a signal; a second infrared absorption film 16 that is formed on the lower surface of the lower surface electrode 15 and absorbs infrared; and a holding base 12 for holding the pyroelectric material 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pyroelectric sensor that converts infrared light into an electrical signal by using the pyroelectric effect and a method for manufacturing the same, and more particularly, a pyroelectric sensor that can improve infrared absorption efficiency and reduce warping of the pyroelectric body. And a manufacturing method thereof.

  A pyroelectric infrared sensor (hereinafter referred to as a pyroelectric sensor) is known as an infrared sensor for Fourier transform infrared spectroscopy. This pyroelectric sensor is formed with an infrared absorption film for absorbing infrared rays.

  Examples of the material of the infrared absorption film include a metal black film, particularly a gold black film, which is very excellent in infrared absorption efficiency (Patent Document 1). In the case of this gold black film, the film thickness is 3 μm, and an infrared absorption rate of about 90% can be obtained. However, about 10% of infrared rays pass through the gold black film. Since the thickness of the pyroelectric material is several μm, the transmitted infrared light cannot be absorbed by the pyroelectric material itself.

  Further, the pyroelectric material is warped by the influence of the internal stress of the infrared absorption film formed on the pyroelectric material. For this reason, cracks and peeling easily occur.

  In the technique described in Patent Document 2, warpage is reduced by dividing the infrared absorption film. However, since there is no infrared absorption film in the slit portion for dividing the infrared absorption film, the slit portion cannot absorb infrared rays.

JP-A-8-148663 Japanese Patent No. 2737597

  Further, when the thickness of the gold black film is further increased in order to increase the infrared absorption efficiency, the pyroelectric body is further warped, and cracks and peeling are likely to occur.

  An object of the present invention is to provide a pyroelectric sensor that can improve infrared absorption efficiency and reduce warping of the pyroelectric body, and a method for manufacturing the same.

  In order to solve the above problems, a pyroelectric sensor according to the present invention is formed on a pyroelectric sensor element, an upper electrode formed on the upper surface of the pyroelectric sensor element and for taking out a signal, and an upper surface of the upper electrode. And a first infrared absorption film for absorbing infrared rays, a lower electrode formed on the lower surface of the pyroelectric sensor element for extracting the signal, and formed on the lower surface of the lower electrode and absorbing the infrared rays. And a holding base for holding the pyroelectric sensor element.

  A method for manufacturing a pyroelectric sensor according to the present invention includes a step of forming a bottom electrode for extracting a signal on the bottom surface of a pyroelectric sensor element, and a second infrared absorbing film for absorbing infrared rays on the bottom surface of the bottom electrode. Forming a top electrode for extracting the signal on the top surface of the pyroelectric sensor element, forming a first infrared absorbing film for absorbing the infrared light on the top electrode, and The method includes the step of holding the pyroelectric sensor element on a holding table.

  According to the present invention, the infrared light incident on the pyroelectric sensor element is absorbed by the first infrared absorbing film, and the infrared light transmitted through the first infrared absorbing film is transmitted through the pyroelectric sensor element and is transmitted to the second infrared light. Absorbed by the absorption film. That is, since the infrared rays that could not be absorbed by the first infrared absorbing film can be absorbed by the second infrared absorbing film, the infrared absorption efficiency is improved.

  In addition, since the pyroelectric sensor element is sandwiched between the first infrared absorbing film and the second infrared absorbing film, warping of the pyroelectric sensor element can be reduced.

It is sectional drawing of the pyroelectric sensor of Example 1. FIG. It is a top view of the pyroelectric sensor of Example 1. 6 is a cross-sectional view showing a manufacturing process of the pyroelectric sensor of Example 1. FIG. It is sectional drawing of the pyroelectric sensor of Example 2. FIG.

  Hereinafter, embodiments of the pyroelectric sensor of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of the pyroelectric sensor of the first embodiment. FIG. 2 is a top view of the pyroelectric sensor according to the first embodiment. The cross-sectional view of the pyroelectric sensor shown in FIG. 1 is a cross-sectional view taken along the line BB ′ in the top view of the pyroelectric sensor shown in FIG.

  The pyroelectric sensor shown in FIG. 1 includes a pyroelectric body 11, a holding base 12, a top electrode 13, a primary infrared absorption film 14 (first infrared absorption film), a bottom electrode 15, and a secondary infrared absorption film 16 (second infrared radiation). Absorption film), upper surface electrode signal extraction line 17, lower surface electrode pad 18, and lower surface electrode signal extraction line 19.

  The pyroelectric sensor converts incident infrared light into an electrical signal. In an FTIR (Fourier transform infrared spectrometer), incident infrared light is modulated at about several tens to several kiloHz.

The pyroelectric material 11 (pyroelectric sensor element) is DLATGS (Deuterated L-Alanine Triglycine Sulphate), LiTaO ₃ (lithium tantalate), LiNbO ₃ (lithium niobate) , Either. Alternatively, as the pyroelectric body 11, PZT, PbTiO ₃ , PGO, TGS including the above-described DLATGS, or the like can be used. Although the external shape of the pyroelectric body 11 is a quadrangular shape, the corners of the four corners of the pyroelectric body 11 can be cut out or circularly shaped to avoid warping due to thermal expansion. Any shape is acceptable.

  The holding table 12 holds the pyroelectric body 11 and is made of any one of a Si single crystal substrate, a glass substrate, and a ceramic substrate. The holding table 12 has an opening 12a, and the opening 12a is formed so as to be larger than the light receiving area of the secondary infrared absorption film 16, thereby avoiding the escape of heat from the pyroelectric body 11 to the holding table 12. Therefore, the pyroelectric body 11 is held at four points (four corners) of the holding table 12.

  A top electrode 13 is formed on the top surface of the pyroelectric body 11. Further, a primary infrared absorption film 14 is formed on the upper surface of the upper electrode 13.

  A lower surface electrode 15 is formed on the lower surface of the pyroelectric body 11. Further, a secondary infrared absorption film 16 is formed on the lower surface of the lower electrode 15.

  Each of the upper surface electrode 13 and the lower surface electrode 15 is made of a conductive metal such as gold, copper, or aluminum. Each of the primary infrared absorption film 14 and the secondary infrared absorption film 16 is made of a metal black film such as a gold black film. Alternatively, each of the primary infrared absorption film 14 and the secondary infrared absorption film 16 may be a metal black film such as a platinum black film.

  An upper surface electrode signal extraction line 17 for signal extraction is bonded to the upper surface electrode 12. The upper surface electrode signal extraction line 17 reads out an electric signal generated in the pyroelectric body 11 through the upper surface electrode 13. The lower surface electrode pad 18 is formed on the holding table 12 and is joined to the lower surface electrode 15 by a conductive paste or solder to be electrically conductive.

  The lower electrode signal extraction line 19 is bonded to the lower electrode pad 18. For this reason, the lower electrode signal extraction line 19 reads out an electric signal generated in the pyroelectric body 11 via the lower electrode 15 and the lower electrode pad 18.

  Next, the operation of the pyroelectric sensor of Example 1 configured as described above will be described. A primary infrared absorption film 14 is formed on the upper surface of the pyroelectric body 11, and a secondary infrared absorption film 16 is formed on the lower surface of the pyroelectric body 11. Therefore, the infrared rays incident on the pyroelectric body 11 are absorbed by the primary infrared absorption film 14 formed on the upper surface of the pyroelectric body 11.

  Next, the infrared rays that have passed through the primary infrared absorbing film 14 pass through the pyroelectric body 11 and are absorbed by the secondary infrared absorbing film 16 formed on the lower surface of the pyroelectric body 11. That is, since the infrared rays that could not be absorbed by the primary infrared absorption film 14 can be absorbed by the secondary infrared absorption film 16, the infrared absorption efficiency is improved.

  Further, since the pyroelectric body 11 is sandwiched between the primary infrared absorption film 14 and the secondary infrared absorption film 16, the warpage of the pyroelectric body 11 can be reduced.

  Further, the pyroelectric body 11 is held at the four points of the holding base 12 so that the area of the opening 12a is larger than the area of the secondary infrared absorption film 16, so Heat escape to 12 can be avoided.

  Next, the manufacturing method of the pyroelectric sensor according to the first embodiment will be described in detail with reference to the manufacturing process of the pyroelectric sensor shown in FIG.

First, as shown in FIG. 3A, a pyroelectric body 11 made of, for example, LiTaO ₃ is processed into a desired shape. Next, as shown in FIG. 3B, a lower electrode 15 made of gold is formed on the lower surface of the pyroelectric body 11 by vapor deposition.

  Next, as shown in FIG. 3C, a mask 21 for forming a gold black film pattern is attached to the pyroelectric body 11 on the lower surface of the pyroelectric body 11. Next, as shown in FIG. 3D, porous gold is deposited on the lower surface of the pyroelectric body 11 by vapor-depositing gold under a low vacuum of about 1000 Pa, and a gold black film (2 A next infrared absorption film 16) is formed.

  Next, as shown in FIG. 3E, the mask 21 is removed. Further, as shown in FIG. 3 (f), a glass substrate 22 is bonded to the lower surface of the pyroelectric body 11.

  Next, as shown in FIG. 3G, after the pyroelectric body 11 is polished to a desired thickness, as shown in FIG. 3H, the upper surface electrode 13 made of gold is formed on the upper surface of the pyroelectric body 11. Evaporate.

  Next, as shown in FIG. 3I, a mask 23 for forming a gold black film pattern is attached to the pyroelectric body 11 on the upper surface of the pyroelectric body 11. Next, as shown in FIG. 3 (j), by depositing gold under a low vacuum of about 1000 Pa, porous gold is formed on the upper surface of the pyroelectric body 11, and the gold black film (1 A next infrared absorbing film 14) is formed.

  Next, as shown in FIG. 3 (k), the mask 23 is removed. Further, as shown in FIG. 3L, the glass substrate 22 is peeled from the pyroelectric body 11.

  Finally, as shown in FIG. 3 (m), the lower surface electrode of the pyroelectric body 11 and the lower surface electrode pad 18 on the holding base 12 are bonded or bonded with a conductive paste (conductive member). .

  By performing the steps of FIG. 3A to FIG. 3M, the pyroelectric sensor according to the first embodiment can be easily manufactured.

  FIG. 4 is a cross-sectional view of the pyroelectric sensor of the second embodiment. In the pyroelectric sensor of Example 2, the primary infrared absorption film 14 and the secondary infrared absorption film 16a are made of a gold black film.

  The primary infrared absorption film 14 is made of a gold black film having an infrared reflectance smaller than a predetermined value. For example, the degree of vacuum at the time of forming the gold black film can be obtained by setting the degree of vacuum higher than the film forming condition (1000 Pa or less) in FIG.

  The secondary infrared absorption film 16 a is made of a gold black film having an infrared reflectance higher than that of the primary infrared absorption film 14. For example, the degree of vacuum when forming the gold black film can be obtained by setting the degree of vacuum lower than the degree of vacuum when forming the primary infrared absorption film 14.

  According to the pyroelectric sensor of Example 2 as described above, the primary infrared absorption film 14 is made of a gold black film having an infrared reflectance smaller than a predetermined value, and therefore can sufficiently absorb infrared rays. For example, about 90% of incident infrared rays can be absorbed by the primary infrared absorption film 14.

  In addition, since the secondary infrared absorption film 16a is made of a gold black film having an infrared reflectance greater than the predetermined value, the infrared light incident on the secondary infrared absorption film 16a is absorbed by the secondary infrared absorption film 16a. Reflected with almost no transmission, returns to the pyroelectric body 11.

  For this reason, for example, most of the remaining 10% infrared light is absorbed by the secondary infrared absorption film 16a. Therefore, since the infrared absorption rate is further improved by the secondary infrared absorption film 16a, the pyroelectric sensor of the second embodiment is larger than the effect of the pyroelectric sensor of the first embodiment.

  The pyroelectric sensor according to the present invention can be applied to a Fourier transform infrared spectrometer.

DESCRIPTION OF SYMBOLS 11 Pyroelectric body 12 Holding stand 12a Opening part 13 Upper surface electrode 14 Primary infrared absorption film 15 Lower surface electrode 16, 16a Secondary infrared absorption film 17 Upper surface electrode signal extraction line 18 Lower surface electrode pad 19 Lower surface electrode signal extraction line 21, 23 Mask 22 Glass substrate

Claims (6)

A pyroelectric sensor element;
An upper surface electrode formed on the upper surface of the pyroelectric sensor element and for taking out a signal;
A first infrared absorbing film formed on the upper surface of the upper electrode and absorbing infrared rays;
A lower electrode formed on the lower surface of the pyroelectric sensor element and for taking out the signal;
A second infrared absorbing film formed on the lower surface of the lower electrode and for absorbing the infrared rays;
A holding base for holding the pyroelectric sensor element;
A pyroelectric sensor comprising:   2. The pyroelectric sensor according to claim 1, wherein the holding table has an opening that is larger than a light receiving area of each of the first infrared absorbing film and the second infrared absorbing film.   3. The pyroelectric sensor according to claim 1, wherein each of the first infrared absorption film and the second infrared absorption film is made of a gold black film or a platinum black film. The pyroelectric sensor according to claim 1, wherein the pyroelectric sensor element is made of any one of DLATGS, LiTaO ₃ , and LiNbO ₃ .   5. The pyroelectric sensor according to claim 1, wherein an infrared reflectance of the second infrared absorbing film is larger than an infrared reflectance of the first infrared absorbing film. 6. Forming a bottom electrode for extracting a signal on the bottom surface of the pyroelectric sensor element;
Forming a second infrared absorbing film for absorbing infrared rays on the lower surface of the lower electrode;
Forming an upper surface electrode for extracting the signal on the upper surface of the pyroelectric sensor element;
Forming a first infrared absorption film for absorbing the infrared ray on the upper surface electrode;
Holding the pyroelectric sensor element on a holding table;
A method of manufacturing a pyroelectric sensor, comprising:

Images