JPH0590552A - Infrared ray detector - Google Patents

Abstract

PURPOSE:To obtain an image having no blurred pixel in an infrared picture image produced by the title infrared ray detector while increasing the bond strength of a photo-reflection preventive film comprising a metallic black body formed on an electrode part adjacent to the photodetector of a photodetective infrared ray element. CONSTITUTION:An image having no blurred pixel can be obtained since a photo-reflection preventive film 15 comprising a metal evaporated in a low vacuum state is formed above an electrode 13 of the title infrared ray detector so that the infrared rays multi-reflected on the space between the electrode 13 and an incident window 16 may not enter into a photodetector 12. In such a constitution, an underneath metallic film is formed above the electrode 13 of the infrared ray detector and then a metallic black body is formed on the metallic film. Furthermore, another metallic film is formed on the metallic black body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detecting element.

[0002]

2. Description of the Related Art The structure of an infrared detector in a conventional infrared detector will be described with reference to FIG. 4 for a liquid nitrogen cooling type infrared detector. The infrared detector 41 should be attached to a vacuum portion 43 of an element container 42. Accordingly, the infrared rays 47 entering the light receiving portion from the light incident window 44 of the element container 42 are photoelectrically converted while being cooled by the liquid nitrogen 46 of the liquid nitrogen reservoir 45 to extract an electric signal.

FIG. 5 shows an example of the infrared light path at this time. When the image is taken by an infrared camera using the detector in the infrared detecting element in which the light receiving portion 52 using the infrared detecting material and the electrode 53 using Au or the like are formed on the base 51,
As in the case of the optical path 57, the light may be incident on the light receiving unit 52 after multiple reflection between the electrode 53 and the incident window 56. Therefore, when strong light is incident on the pixel of the image, bleeding occurs and the detection resolution decreases. There was something to do.

As a measure for preventing multiple reflection, there is one in which a light absorption layer made of a black organic material is provided in the multiple reflection region (Japanese Patent Laid-Open No. 1-287961). In this method, the multiple reflection of light having a wavelength in the visible light region is prevented. Only valid, 1-10
It has no effect on so-called infrared rays of μm.

Since an object that causes multiple reflections is not only an entrance window but also a camera lens, a filter, and the like, even in a structure other than the above, image pixel bleeding may occur and detection resolution may be lowered.

As a measure for preventing multiple reflection, 0.01 to 10 [t
There has been proposed a structure of a thermal sensor in which a metal black body film formed by metal deposition in a low vacuum of [orr] is formed in an electrode region in the vicinity of a light receiving portion of an infrared sensor and used as an antireflection film.
Metal black body, for example, "" metal black body formation by vapor deposition "vacuum Vol. 16, No. 5 (1937)" As introduced in the metal 10 ^{- 5} [torr] or more when the deposited at a high vacuum state so while the metal film having a high reflectivity called metallic luster, 10 ^{- 2} to several 10 [torr] low density porous membrane and becomes light absorber when depositing in vacuum called metal black body It will be.

FIG. 6 is a schematic view of a metal black body film which is an antireflection film of a thermal sensor formed near the light receiving portion. A method of forming the antireflection film will be described. First, the light receiving portion of the infrared detecting element is covered by a photoresist pattern forming method. After that, the metal black body is formed as an antireflection film 68 by vapor deposition in a low vacuum state of 0.01 to 10 [torr], and the resist on the light receiving portion is removed by washing to remove the antireflection film on the electrode region 63 other than the light receiving portion. Can be formed.

[0008]

When an infrared image is captured by a conventional infrared detection element device using infrared detection, after performing multiple reflection between the electrode of the infrared detection element and the incident window of the infrared detection element. Since it sometimes enters the light-receiving part and is added to the light which is the positive signal directly entering the light-receiving part, the pixel of the image bleeds when the strong infrared light enters, and the detection resolution is lowered.

An object of the present invention is to solve the above problems, and to prevent deterioration of the detection resolution without causing bleeding of image pixels even when strong infrared rays are incident.
Furthermore, since this antireflection film must be formed with high precision in the electrode region near the light receiving portion of the infrared sensor, a patterning process using a photoresist is required. Then, a step of cleaning the photoresist after forming the antireflection film is necessary. The cleaning method is soaked in an organic solvent,
Perform ultrasonic cleaning. At this time, in the structure in which only the conventional metal black body film is formed in the vicinity of the light receiving portion of the infrared detection element, the adhesive force is very weak, so that there is a problem that the film is peeled off by cleaning and the reflection component is increased.

Another object of the present invention is to solve the above-mentioned problems and to provide an infrared detecting element which hardly peels off even after cleaning after the formation of the antireflection film and which suppresses an increase in the reflection component.

[0011]

According to the present invention, there is provided an infrared detecting element, characterized in that an antireflection film made of metal deposited in a low vacuum state is provided in a region other than a light receiving portion, and the infrared detecting element. In the infrared detecting element, a base metal film, a metal black body film, and an upper metal film are laminated in this order in an electrode region around the portion.

[0012]

With such a laminated structure of the base metal film, the metal blackbody film, and the upper metal film, the metal blackbody is formed on the base metal, so that the metal blackbody is formed more directly than on the insulating film. The wearing power is great. Next, a thin film is formed on the upper surface of the metal film so as to cover the metal black body film, and by combining the large grains forming the irregularities of the metal black body film with each other, the peeling is greatly suppressed. As a result, the antireflection film is less likely to be peeled off by cleaning, and an increase in the reflection component can be suppressed. Also, by setting the thickness of the metal film on the upper surface to about 3000 A or less, there is no influence on the shape of the lower porous metal black body film, and there is no increase in the reflection component.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of the photoconductive infrared detecting element of the present invention will be described with reference to FIG. A light receiving portion 12 using an infrared detecting material and an electrode 1 using Au or the like on a substrate 11.
In the infrared detection element in which 3 is formed, the antireflection film 15 made of metal vapor-deposited in a low vacuum state is formed in a region other than the light receiving portion 12. With such a structure, the infrared incident light 18 that has entered the area other than the light receiving portion 12 through the entrance window 16 is prevented from being reflected by the antireflection film 15 and does not return in the incident direction. The incident infrared ray is only the infrared incident light 17 which is a positive signal.

The method of forming the antireflection film of the infrared detecting element will be described below. First, the light receiving portion of the infrared detecting element is covered by a photoresist pattern forming method. After that, an antireflection film made of metal deposited in a low vacuum state is deposited, and the resist on the light receiving portion is removed by washing, whereby the antireflection film can be formed in a region other than the light receiving portion.

FIG. 2 shows an example of a vapor deposition apparatus used for vapor deposition in a low vacuum state, and the vapor deposition method will be described. Vacuum chamber 2
In FIG. 1, an infrared detection element 22 and an Au 23 that serves as a vapor deposition source are installed and connected to a vacuum pump 24 via a valve 25. A vacuum gauge 26 capable of monitoring the degree of vacuum is connected to the vacuum chamber 21. General metal vapor deposition vacuum of 1 × 10 ^{- 4} will be deposited in a good vacuum level than [torr], the vacuum pump is deposited in a low vacuum state of formation of the antireflection film of the infrared detection element used in the present invention By adjusting the opening of 24 and valve 25,
The vacuum degree is set to 10 [torr], and vapor deposition is performed as it is. FIG. 6 shows that the present inventor has performed the above-described low-vacuum deposition to set the vacuum degree of the vacuum chamber of the deposition apparatus to 1.5 [tor].
r] is used to form an antireflection film using Au as a vapor deposition source. The reflection of light of 1 to 10 μm is suppressed to 5% or less. The reflectance of the antireflection film that does not cause bleeding in the pixels of the actual infrared image may be 30% or less.

At this time, another metal substance such as Cu or Al may be used instead of Au as the vapor deposition source.

Another embodiment of the infrared detecting element of the present invention will be described with reference to FIG. As an example of forming the antireflection film, a case where three metal films are formed by a vapor deposition method will be described.

The thin film forming method is as described above. First, an Au film 19 having a thickness of 2000 A vapor-deposited with Au is formed in a high vacuum on the electrode region other than the light receiving portion of the infrared detection element as a base. When a total of 3.0 g of Au is vapor-deposited on it with a vacuum degree of 1.5 [torr], a metal black body film 18 is formed,
Finally, Au was vapor-deposited again with high vacuum to a thickness of 2000A.
The film 15 is formed.

The thickness of the metal black body film is 1 to 2 μm and is irregular and porous. The presence of the 2000 A thick Au film 13 formed the third time cannot be confirmed in the photograph because the thickness of the metal black body film at 1.5 [torr] is large and the unevenness is severe, but it is a porous metal black body. Au according to the unevenness of the film
The particles form a thin film. At this time, Au is used as a vapor deposition source.
Other metal substances such as Cu and Al may be used instead of.

FIG. 7 shows a conventional method (A) in which only a metal black body film is formed in the vicinity of the light receiving portion of an infrared sensor, and a photoresist is then washed by the same method (C). 2) shows the spectral sensitivity of vertical reflectance and the spectral sensitivity of vertical reflectance before (A) and after (B) cleaning of the antireflection film of the present invention prepared in the manner of Examples. From this data, the structure of the antireflection film of the present invention is hardly peeled off and exhibits the performance as the antireflection film.

[0021]

As described above, according to the present invention, in the infrared detecting element, by providing the light antireflection film made of metal evaporated in a low vacuum state in the region excluding the light receiving portion, when strong infrared rays are incident. Also prevents the pixels of the infrared image from bleeding and prevents deterioration of the detection resolution. Further, according to the present invention, the adhesion strength of the antireflection film can be improved,
It is possible to obtain an infrared detection element which is hardly peeled off even after cleaning after formation and which can sufficiently exhibit the performance as an antireflection film.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the structure of an infrared detection element of the present invention.

FIG. 2 is a diagram showing an example of a vapor deposition apparatus used for metal vapor deposition in a low vacuum state.

FIG. 3 is a cross-sectional view of an example of an antireflection film having a laminated structure of a base metal film, a metal black body film, and an upper metal film of the present invention.

FIG. 4 is a cross-sectional view of a detector using a liquid nitrogen cooling type infrared detection element, which is an example of a conventional infrared detection element.

FIG. 5 is a diagram showing an example of an infrared light path in a detector using a liquid nitrogen cooling type infrared detection element which is an example of a conventional infrared detection element.

FIG. 6 is a diagram showing the relationship between the reflectance of an antireflection film and the wavelength of incident light.

FIG. 7 is a diagram showing the spectral sensitivity of vertical reflectance.

[Explanation of symbols]

 11 substrate 12 light receiving part 13 electrode 14 insulating film 15 antireflection film 16 entrance window 17 infrared incident light 18 infrared incident light 33, 43, 63 electrode 35 metal film 38, 68 metal black body film 39 metal film 21 vacuum chamber 22 , 31 infrared detection element 23 Au 24 vacuum pump 25 valve 26 vacuum gauge 42 element container 43 vacuum section 44, 56 entrance window 45 liquid nitrogen reservoir 46 liquid nitrogen 47 infrared 51 substrate 52 light receiving section 53 electrode 54 insulating film 57 optical path

Claims (2)

[Claims] 1. An infrared detecting element, characterized in that a light antireflection film made of metal evaporated in a low vacuum state is provided in a region other than a light receiving portion in the infrared detecting element. 2. The infrared detecting element, wherein a base metal film, a metal black body film, and an upper metal film are laminated in this order in an electrode region around a light receiving portion.