JPS61195318A - Pyroelectric type infrared detector - Google Patents

Abstract

PURPOSE:To prevent the influence of a signal read-out part by visible light by forming adjacently the signal charge read-out function part and an IR detecting part provided with a through-region penetrating through a semiconductor substrate on the substrate to connect each other and making incident IR rays thereon from the rear side. CONSTITUTION:An oxide film is formed over the entire surface of an Si wafer by a thermal oxidation method and the oxide film is removed from the part where an IR detecting element is constituted on one side. A recess is formed in said part by anisotropic chemical etching. The oxide film on the surface opposite from the side facing the recess is removed away and the wafer is anisotropically etched from both sides to form a through-part 25. A shift register and conductive part 28 are formed as the signal charge read-out part near the through-part 25. Electrodes 23, 24 of the pyroelectric type IR detecting element 22 consisting of a thin sheet of PbTiO3 ceramics or LiTaO3 crystal are separately formed and are fixed by a conductive adhesive agent 27 and adhesive agent 29 to the step part of the through-part 25. The register 21 and the electrode 23 are connected by the vapor deposition of Al. The IR rays are made incident on the detector from the rear side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pyroelectric infrared detector in which a large number of pyroelectric infrared detection elements utilizing the pyroelectric effect are formed on a semiconductor substrate.

Conventional technology Objects are detected using infrared rays emitted from objects according to their temperature.Infrared detectors that measure the temperature of objects use quantum effects and those that detect infrared rays as heat. There is also a thermal type. Some thermal type devices utilize the pyroelectric effect, and in particular, a structure in which a large number of pyroelectric infrared detection elements are arranged in an array and has the function of sequentially reading out the signal charges generated therein has been proposed in Japanese Patent Application Publication No. Publication No. 57-120830 or JP-A-59-3
The one described in Publication No. 5119 and the like is known. The configuration of a conventional pyroelectric infrared detection element array and its output charge readout function section will be described below with reference to FIGS.

Figures 5a and 5b are schematic diagrams showing the pyroelectric infrared detection element array section, where 1 is a pyroelectric element, 2 is a support plate, 3 is an electrode, and 4
6 is a ground electrode, 6 is a conductive adhesive, and 6 is a hollow portion.

The pyroelectric element 1 is heated by irradiation with infrared rays, and a hollow portion 6 is provided in the support plate 2 for the purpose of preventing heat from escaping due to downward heat conduction and improving sensitivity. FIG. 6 shows a pyroelectric infrared detection element configured to electrically connect a pyroelectric infrared detection element array section 1o and a shift register part 11 for reading signal charges at a coupling section 12, and read out signal charges sequentially. 1 shows a wiring diagram of a conventional example of a device. Here, 13 is a pyroelectric element array, 14 is an electrode of the pyroelectric element array 13, 16 is a lead wire for the switch FICT 116, 17 is a shift register, and 18 is a signal output terminal, and the signal output is from each pyroelectric element 13. The shift register 17 sequentially reads out the signal charges generated by the shift register 17 through a lead wire 16 formed by ultrasonic bonding or the like, and outputs them from the signal output terminal 18.

Problems to be Solved by the Invention However, in the above configuration, as the number of pyroelectric element arrays increases and the pyroelectric elements themselves become smaller, the pyroelectric infrared detection element array section and the signal charge readout section There is a problem in that not only is it complicated and difficult to connect the two using lead wires using a method such as ultrasonic bonding, but also the size of the infrared detector becomes large. Furthermore, when visible light is incident on an infrared detector along with infrared rays, the signal charge reading section senses the visible light, causing the infrared detector to malfunction.

The present invention solves the above-mentioned problems all at once, and facilitates the electrical connection between the pyroelectric infrared detection element array section and the signal charge readout section, making the size of the infrared detector compact, and the signal charge readout section. This eliminates the influence of visible light in the area.

Means for Solving the Problems In order to solve the above problems, the present invention forms a signal charge readout function section and an infrared detection section having a penetration region that penetrates the substrate adjacently on the same semiconductor substrate, The above objective is achieved by forming the electrical connection between the two at once using a vapor deposited film or conductive adhesive, and by configuring the structure so that the incident infrared rays enter from the side opposite to the semiconductor surface where the signal charge readout function section is formed. It is something to do.

Effect of the Invention With the above-mentioned configuration, the present invention can form an electrical connection between the signal charge readout function section and the infrared detection section at once. Compared to forming individual lead wires using ultrasonic bonding or the like to establish electrical connections, electrical connections can be made much more easily. Furthermore, compared to the conventional method in which the signal charge readout function section and the infrared detection section are formed separately and electrically connected after mounting them in the same package, the present invention allows both to be formed within the same semiconductor substrate. can be formed all at once, so the overall configuration can be made compact. Furthermore, since the configuration is such that infrared rays are incident from the side opposite to the semiconductor surface where the signal charge readout function section is formed, it is possible to prevent the influence of visible light on the signal charge readout section.

EXAMPLE The present invention will be explained in detail using FIG. FIG. 1 is a cross-sectional view showing one embodiment of the pyroelectric infrared detector of the present invention.
b is an example in which the pyroelectric infrared detecting element is formed on the same side as the front surface of the semiconductor substrate on which the signal charge readout function section is formed, and b is an example in which it is formed on the opposite side.

Identical parts are indicated by the same numbers. 2Q is a semiconductor substrate, 21 is a signal charge readout section, 22 is a pyroelectric infrared detection element, 2
3.24 is an electrode, 26 is a penetration portion, 28.27 is an electrical connection portion, 28 is a conductive portion, and 29, 30.31 is an adhesive. An n-type or p-type 100-plane or 11Q-plane Si substrate was used as the semiconductor substrate 2o. When Si is subjected to anisotropic chemical etching, the etching takes place in the shapes shown in FIG. 2, a and b, depending on the crystal orientation plane. That is, the crystal orientation plane is 1o.

When the Si substrate 40 is subjected to anisotropic chemical etching using the oxide layer 41 as a mask, θ is 64 to 65 degrees as shown in Figure 2a.
Can be etched. In addition, Si with a crystal orientation of 110
When the substrate 42 is subjected to anisotropic chemical etching using the oxide layer 43 as a filler, etching can be achieved as shown in FIG.

(Example 1) An oxide film was formed on the entire surface of a Si wafer with a thickness of 300 μm using a thermal oxidation method, and then an oxide film was formed on one side of the portion of the Si wafer where an infrared detection element was constructed using microfabrication technology. Anisotropic chemical etchant K Yotte 1.2 jFll X
A recess with a thickness of 6.6 nr and a depth of 240 μm was formed. Next, the oxide film on the opposite side of the Si wafer, facing the part where the recesses were formed, was removed using microfabrication technology, and then the anisotropic etching solution was used again to remove the oxide film from both sides for 30 minutes.
μm etching was performed. As a result, the opening on one side is 1.2ml x 6,6 II+, depth 270μ
The recess of m and the opening of the other side are 1,1j11×6.51
11. A penetrating portion 26 as shown in FIG. 1 was formed by connecting concave portions each having a depth of 30 μm. "Also, a shift register and a conductive part 28 were formed as a signal charge readout part 21 in the vicinity of the through part using a generally well-known microfabrication technique. On the other hand, a 30 μm thick PbT
Engineering 03 ceramics or LiTa0, crystal 1ff
Nichrome was vapor-deposited as electrodes 23 and 24 of each pyroelectric infrared detection element 22 on both sides of the x6.4In at intervals of 50 μm. As shown in FIG.
7 and adhesive 29. Furthermore, aluminum is vapor-deposited using a metal mask, and as shown in FIG. 3 (the same parts as in FIG. Electrical connections (corresponding to 26) were made to produce a pyroelectric infrared detector consisting of an array of 128 pyroelectric infrared detection elements.

(Example 2) As shown in FIG. 1, the shift register 21 was formed on the opposite side of the semiconductor substrate 20 to that in Example 1, and nichrome electrodes were formed at 50 μm intervals on the 30 μm step side of the through portion 26. 1fl×e, 4xxr PbTi0. Ceramics or LiTa0.

The single crystal is fixed with adhesive 30, 31, and then aluminum evaporation is performed using a metal mask to form the electrical connection part 2.
A pyroelectric infrared detector consisting of an array of 128 pyroelectric infrared detection elements was fabricated by forming 8.27.

(Example 3) Another example will be shown using FIG. After forming the penetration part 66 in the silicon substrate 50 by performing anisotropic etching using the method shown in Example 1, a shift register is formed in the vicinity of the penetration part 66 using a generally well-known microfabrication technique. 61 and conductive portion 58 were formed. Next, 30 μm thick pbTio 3 ceramics or LiTa0. Single crystal 1jFIX: (As shown in Figure 4 on both sides of 5.4g, nichrome is vapor-deposited on the entire surface except for a part of the edge, and electrode 53 is formed.
．． 64 was formed. Next, apply adhesive 69.60 to the semiconductor substrate 6 on the side of the step with a depth of 30 μm in the through part 65.
The shift register 61 and the electrode 53 are fixed by adhesive and fixed to
An electrical connection 66 between the electrode 64 and the conductive portion 68 was made.

Thereafter, PbTiO3 ceramics or LIT is adhesively fixed to the semiconductor substrate 60 using a dicing saw.
a O5 single crystal 62 with semiconductor substrate 60 to a depth of 36μ
A pyroelectric infrared detector consisting of an array of 64 pyroelectric infrared detection elements was fabricated by cutting and separating at a pitch of 100 μm.

Effects of the Invention As described above, the present invention is to form a pyroelectric infrared detecting element array section and a signal charge readout section provided on the through portion on the same semiconductor substrate, and to form an electrical connection between the two at once. This has the effect of facilitating the electrical coupling between the two and making the size compact.In addition, since the infrared rays are incident from the side opposite to the semiconductor surface where the signal charge readout section is formed, the signal charge This produces the effect of preventing the influence of visible light on reading.

In the above description, a shift register has been described as a signal charge readout section, but even if a CCI is used, the effects of the present invention will not be lost and the effects will be sufficiently exhibited. Further, although the present invention has shown an example in which the signal charge readout section and the pyroelectric infrared detection section are arranged in one dimension, the effects of the present invention will not be lost even if a large number of these are arranged in two dimensions. This is a passionate argument.

[Brief explanation of the drawing]

Figure 3 is a plan view of an infrared detector according to an embodiment of the present invention, and Figures 4a and 4b are schematic diagrams showing the element array portion of the present invention. 6 are configuration diagrams of a conventional pyroelectric infrared detector. 1...Pyroelectric element, 2...Support plate, 6.
...Hollow, 10...Pyroelectric infrared detection element array part, 11゜61...Part of shift register, 12...Coupling part, 20.60・・・・・・
Semiconductor substrate, 21...Signal charge reading section, 2
2.52...Pyroelectric infrared detection element, 26.2
7.56.57... Electrical connection, 26°66
・・・・・・Penetration part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure M, vVf Tato HB Figure 2 Figure 3 Figure 4 Figure 5 Otsu J,? Figure 6/θ

Claims (3)

[Claims] (1) A semiconductor substrate is equipped with a signal charge readout section and a penetration region that penetrates the front and back sides of the semiconductor substrate, and a plurality of pyroelectric infrared detection elements suspended in the air covering the penetration region are connected to the semiconductor substrate at both ends. 1. A pyroelectric infrared detector, characterized in that the pyroelectric infrared detector is fixed to a pyroelectric infrared detector, thin film electrodes are formed on both sides of the pyroelectric infrared detector, and one side is electrically connected to the signal charge readout section. (2) A pyroelectric infrared detector according to claim 1, characterized in that a penetrating region penetrating the front and back surfaces of the semiconductor substrate is etched away by anisotropic etching. (3) A signal charge readout section is formed on one side of the semiconductor substrate, and a plurality of infrared detection elements are formed on the other side, covering the penetration area and suspended in the air, separated from each other. A pyroelectric infrared detector according to claim 1.