JPH05157625A - Filter for infrared sensor array and its manufacture - Google Patents

Abstract

PURPOSE:To provide a filter for infrared sensor arrays which can manufactured at a low cost, improved in S/N and packing density, and reduced in size and its manufacturing method. CONSTITUTION:Recessed sections 6 are formed on the surface of a filter material 20 covering the light receiving section 4 of an infrared sensor formed on a substrate 3. The sections 6 are formed on the surface opposed to the section 4 and filter windows 21 are formed by reducing the thickness of the bottom walls 7 of the sections 6. The thick section between each section 6 are constituted as partition walls 22 which do not transmit infrared rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor array filter used for opening and closing an automatic door and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Infrared detection sensors used for opening and closing automatic doors are made of silicon or the like that transmits only infrared rays to be detected in order to prevent malfunction due to incidence of visible light or near infrared light. The created filter is used. The conventional infrared sensor has one chip and one light receiving section, but recently, an infrared sensor having one chip and a plurality of light receiving sections to increase the detection sensitivity (hereinafter referred to as an infrared sensor). Sensor array) is being adopted. FIG. 6 shows a structure explanatory view of an infrared sensor array of this type. FIG. 7 shows a detailed view of the infrared sensor filter. In these figures, a plurality of infrared ray receiving parts 4 (in the figures, 4
(× 4 pieces) are arranged in a regular array with intervals E. The base 2 has a cap 2 including an infrared partition member 10.
The cap 2 is covered with a plurality of infrared ray transmitting holes 5 corresponding to the plurality of infrared ray receiving portions 4 facing each other, and the infrared ray transmitting holes 5 are made of silicon or the like. Filter 1 is attached. Further, the cap 2 has a concave infrared absorbing wall 11
Are formed by a press or the like and are arranged between the respective infrared sensor filters 1. This infrared absorption wall 11
Is configured as an infrared-impermeable partition wall that prevents crosstalk of infrared rays incident from each infrared filter 1.

This infrared detecting sensor has a sensor light receiving section 4
When infrared rays are incident on the sensor, the infrared rays are converted into heat energy by the sensor light-receiving unit 4, and the heat energy is converted into, for example, a pyroelectric body using a change in spontaneous polarization, or a thermocouple using a change in electromotive force or resistance value. Communicate to. This heat is converted into an output voltage using a pyroelectric body or a thermocouple, and an object is detected from this output voltage.

[0004]

However, in the conventional infrared sensor array, the infrared filter 1 and the cap 2 including the infrared partition member 10 are separately formed, and the filter 1 and the cap 2 are provided to the infrared light receiving portion 4. When the filter 1 is attached to a predetermined position, it must be attached to the infrared ray transmitting hole 5 of the cap 2 while aligning the filter 1 with the opposing position of the infrared ray receiving portion 4, which is time-consuming and costly. Further, since the infrared absorbing wall 11 has a complicated shape, it is difficult to form a large recess depth, and the forming density cannot be increased, which is an obstacle to downsizing and increasing the density of the entire infrared sensor array. In addition, because the plate thickness of the infrared partition member 10 cannot be sufficiently taken due to its processing difficulty, and the recess depth of the infrared absorbing wall 11 cannot be taken sufficiently, the transmitted light from the filter 1 may be slightly crossed. This caused talk, which was also an obstacle to improving the S / N ratio of noise.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to assemble easily and inexpensively, to improve the S / N ratio, and to make the device compact and highly densified. The present invention provides a filter for an infrared sensor array and a method for producing the same.

[0006]

In order to achieve the above object, the present invention is configured as follows. That is, in the infrared sensor array filter of the present invention, the sensor light receiving portions of the plurality of infrared sensors installed on the base are covered with the filter material, and the opposing surface of the filter material facing each sensor light receiving portion is provided. Recesses are formed, the bottom wall of each recess is thinned and is configured as a filter window that transmits infrared rays, and the thick part between each recess is an infrared ray that prevents crosstalk of infrared rays incident from each filter window. It is characterized by being configured as a non-permeable partition wall.

Further, in the method for manufacturing a filter for an infrared sensor array of the present invention, a filter material that covers the sensor light receiving portions of a plurality of infrared sensors installed on a base is made of a silicon material, and the silicon material is used to The concave portion is formed by anisotropically etching the orientation surface of the portion facing the sensor light receiving portion, and the anisotropic etching is performed until the bottom wall of the concave portion has a thickness that allows infrared rays to pass therethrough to form a filter window. It is characterized by that.

[0008]

[Function] Infrared rays emitted from the human body pass through the filter window,
The light enters the sensor light receiving portion of the infrared sensor disposed on the opposite surface of the filter window. At this time, partition walls formed between the filter windows block the incident light to prevent infrared crosstalk.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of an infrared sensor array filter according to a first embodiment of the present invention. FIG. 2 shows a detailed view of the infrared sensor array filter. A characteristic of this embodiment is that a plurality of filter windows and a plurality of partition walls are integrally formed by using a filter material such as silicon. In FIG. 1, sensor light receiving portions 4 of a plurality of infrared sensors are arranged and formed on a base 3 similarly to the conventional example. A cap 2 covers the peripheral edge of the base 3, and the cap 2 is covered with a filter material 20 for infrared sensor array, such as silicon, for each sensor light receiving portion 4.
It is arranged and fixed in a state of covering. As shown in FIG. 2, recesses 6 are formed in the filter material 20 for the infrared sensor array on the facing surface of the filter material 20 facing the respective sensor light receiving portions 4, and the bottom wall 7 of each recess 6 is thinned. A filter window 21 that transmits infrared rays is configured. Each of these recesses 6
The thick portion in between is configured as an infrared-impermeable partition wall 22 that prevents crosstalk of infrared rays incident from each filter window 21.

According to this embodiment, a plurality of recesses 6 are provided in a filter material 20 such as silicon, the recesses 6 are thinned to form a filter window 21, and a thick portion between the recesses 6 is defined as a partition 22.
Therefore, unlike the conventional example, the troublesome work of mounting separate filters 1 to the infrared transmitting holes 5 of the infrared partitioning member 10 one by one is eliminated, and the assembling work is greatly simplified and the working cost can be reduced. it can. In addition, since the partition wall 22 that is impermeable to infrared rays is thick and a sufficient projecting length that partitions both sides can be secured, it is possible to prevent crosstalk of infrared rays entering from the filter window 21.
The N ratio can be improved.

FIG. 3 shows an explanatory view of the infrared sensor array filter according to the second embodiment of the present invention, which is manufactured by the anisotropic etching technique of silicon. FIG. 4 shows a detailed view of the infrared sensor array filter. In these figures, a plurality of infrared ray receiving portions 4 are provided on a base 3, and a filter material 20 such as silicon covers each infrared ray receiving portion 4 via a cap 2. In this embodiment, a (100) plane silicon wafer (silicon thin film piece) is used as the filter material 20. When manufacturing the filter material 20, the filter window 20 and the partition wall 22 are anisotropically etched by anisotropically etching the silicon filter material 20 with an etching material for anisotropic etching such as an aqueous solution of potassium hydroxide.
To form. At this time, the silicon single crystal (111)
Utilizing the property that the etching speed of the surface is slower than other crystal surfaces, the silicon single crystal (111) surface is not etched after the etching regardless of the shape of the etching window when the silicon single crystal is anisotropically etched. And the filter window 21 is formed. Due to such self-aligning processing properties, silicon can be processed with micron-order accuracy and good reproducibility can be obtained.

Since the filter window 21 and the partition wall 22 are produced by anisotropically etching silicon as described above, the dimensional accuracy of the filter window 21 and the partition wall 22 can be processed with a dimensional accuracy of the order of microns. The manufacturing yield of the filter is improved, and the assembly work with the base 3 becomes easy,
The cost can be reduced. Further, since it becomes easy to control the thickness of the partition wall 22 which is impermeable to infrared rays, the sensor array as a whole can be made compact and high-density without lowering the S / N ratio.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, the shape of the filter window 21 that transmits infrared rays may be polygonal other than circular or quadrangular, and the number of arrays is four in the embodiment.
Although x4 = 16 is set, any number may be used.

Although the cap 2 is used on the base 3 in the above embodiment, the filter material 20 may be directly bonded to the base 3 or the sensor light receiving portion 4.

Further, as shown in FIG. 5, an optical multilayer film filter 30 for preventing reflection of infrared rays or for bandpass may be formed on the front, back or both sides of the filter window 21. Furthermore,
It is possible to further improve the sensitivity, the S / N ratio and the like by using an infrared ray condensing lens.

Further, although the (100) plane silicon wafer is used as the silicon filter material 20 in the second embodiment, the plane orientation of the silicon wafer used may be arbitrary, and in that case, the plane orientation of the silicon wafer may be changed. The filter for an infrared sensor array has a corresponding etching surface shape.

[0017]

Since the recess is formed in the filter material and the recess is thinned to form the filter window, it is not necessary to separately prepare the infrared partition member and the filter as in the conventional case. Assembling work with is easy,
It is possible to reduce working time and cost.

Further, since the filter window and the partition wall which is impermeable to infrared rays are integrally formed by using the filter material, the partition wall can be formed at a high density and can be made sufficiently thick, so that the light enters from the filter window. Infrared crosstalk can be prevented, and the sensor array as a whole can be made smaller and higher in density without lowering the S / N ratio.

Further, since silicon as a filter material is anisotropically etched to form the filter window and the partition wall, the dimensional accuracy can be increased to the micron order, so that the production yield of the filter is improved and infrared rays are infrared rays. The crosstalk can be prevented, the S / N ratio can be further improved, and the overall size and density of the sensor array can be further improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a configuration of an infrared sensor array filter according to a first embodiment.

FIG. 2 is a detailed view of an infrared sensor array filter according to the same embodiment.

FIG. 3 is an explanatory view of a second embodiment in which the infrared sensor array filter according to the present invention is manufactured by an anisotropic silicon etching technique.

FIG. 4 is a detailed view of the infrared sensor array filter.

FIG. 5 is an explanatory diagram showing another configuration of the infrared sensor array filter according to the present invention.

FIG. 6 is an explanatory diagram of a conventional infrared sensor array filter.

FIG. 7 is a detailed view of the infrared sensor array filter.

[Explanation of symbols]

 3 Base 4 Sensor light receiving part 6 Recess 7 Bottom wall 20 Filter material 21 Filter window 22 Partition wall

Claims (2)

[Claims] 1. A sensor light receiving portion of a plurality of infrared sensors installed on a base is covered with a filter material, and a concave portion is formed on a facing surface of the filter material facing each sensor light receiving portion. The bottom wall of the is configured as a filter window that is thin and transmits infrared rays, and the thick portion between the recesses is an infrared-impermeable partition wall that prevents crosstalk of infrared rays incident from each filter window. Infrared sensor array filter configured. 2. A filter material for covering the sensor light receiving portions of a plurality of infrared sensors installed on a base is formed of a silicon material, and the silicon material has an anisotropic orientation surface at a portion facing the sensor light receiving portions. Etching to form recesses,
A method for producing a filter for an infrared sensor array, wherein the anisotropic etching is performed until the bottom wall of the recess has a thickness that allows infrared rays to pass therethrough to form a filter window.