JP2003337066A - Bolometric infrared detector and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolometric infrared detector and a manufacturing method for the bolometric infrared detector that keep a high-speed response and high sensitivity, and at the same time can increase the bandwidth of a detection wavelength. <P>SOLUTION: The bolometric infrared detector 10 comprises: a substrate 1; an infrared ray absorption layer 13 that is supported at a specific height position while being separated by a void from the substrate 1; a reflection layer 3 provided on the substrate 1; or the like. The infrared ray absorption layer 13 has an irregular sectional shape, flat sections 13a and 13b in parallel with the reflection layer 3, and a slanting section 13c that is not in parallel with the reflection layer 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uncooled thermal infrared detector capable of detecting infrared rays from an object such as a human body, animals and plants, a vehicle, a natural environment, etc., and a method for manufacturing the same.

[0002]

2. Description of the Related Art A thermal infrared detector such as a bolometer has an infrared absorption layer that absorbs infrared rays and converts them into heat. The infrared intensity is measured by electrically measuring the temperature change due to infrared absorption. To detect. By arranging such infrared detecting portions in a one-dimensional line shape or a two-dimensional array shape, it is possible to detect an infrared intensity distribution and an infrared image.

A conventional thermal infrared detector comprises an infrared absorbing layer that absorbs infrared rays and converts it into heat, and a reflecting layer provided in a stage subsequent to the infrared absorbing layer. The reflecting layer is absorbed by the infrared absorbing layer. It has a function of reflecting the infrared rays that cannot be completely reflected in the direction of the infrared absorption layer, whereby the infrared rays are efficiently absorbed and the detection sensitivity is improved.

For example, Japanese Patent Laid-Open No. 2-196929 discloses that
An infrared detector in which a plurality of bolometer elements are arranged in an array with a certain gap from a substrate is described. With particular reference to FIG. 4A and the like, an insulating layer made of silicon oxide and a ground plane made of aluminum are formed on the substrate, and the ground plane functions as an infrared reflection layer. The ground plane and the bolometer element are installed in parallel so that the distance between them is constant, and the distance is 2.5 μm corresponding to λ / 4 with respect to the central wavelength λ = 10 μm of the detection region 8 to 12 μm. Held, center wavelength 10μ
It is set so that the absorption efficiency is maximized near m.

US Reissue Pat. No. 36706 describes an infrared detector having a two-stage structure similar to the above, in which a protective layer and a metal reflection layer are formed on a substrate, and a certain gap is provided from the substrate. A trapezoidal bridge is provided, and a resistance layer made of vanadium oxide having a large temperature dependence of electric resistance is formed on the horizontal plane of the bridge.

[0006]

In the conventional thermal infrared detector, the infrared absorption layer and the reflection layer are arranged parallel to each other and are held so that the optical distance between them is constant. Therefore, high absorption efficiency is exhibited at a wavelength λ whose optical distance corresponds to λ / 4.
The sensitivity is relatively low for wavelength bands other than. As a result, the detection wavelength characteristic shows a steep peak, which is useful as a narrow band detector, but is not suitable for wide band detectors such as infrared spectroscopy.

A method of broadening the detection wavelength band by forming the infrared absorption layer with an optical multilayer film is also conceivable. However, as the thickness of the infrared absorption layer increases, the heat capacity of the detection unit increases and the thermal time constant increases.
As a result, the thermal responsiveness deteriorates and the response speed to the incident infrared ray becomes slow, which makes it unsuitable for heat sensing of a moving object, for example.

An object of the present invention is to provide a thermal infrared detector capable of widening a detection wavelength band while maintaining high-speed response and high sensitivity, and a manufacturing method thereof.

[0009]

According to the present invention, an infrared ray absorbing layer for absorbing an infrared ray incident from the outside and converting it into heat, and an infrared ray passing through the infrared ray absorbing layer are reflected and returned to the infrared ray absorbing layer. And a reflection layer for the infrared absorption layer,
A thermal infrared detector having a flat portion parallel to the reflection layer and an inclined portion not parallel to the reflection layer.

With this structure, the sharpness of resonance caused by the interference between the infrared rays incident on the infrared absorbing layer and the infrared rays traveling the optical distance between the infrared absorbing layer and the reflecting layer is suppressed, so that a specific wavelength is suppressed. The sensitivity peak height for λ can be relaxed. As a result, it is possible to prevent a relative decrease in sensitivity in wavelength bands other than λ, and to broaden the detection wavelength band.

Further, since the infrared absorbing layer has the uneven cross-sectional shape consisting of the flat portion and the inclined portion, the mechanical vibration is suppressed, the shape is stabilized, and the impact resistance is improved as compared with the flat film.

Further, according to the present invention, an infrared absorbing layer for absorbing infrared rays incident from the outside and converting the infrared rays into heat, and a reflecting layer for reflecting the infrared rays passing through the infrared absorbing layer and returning the infrared rays to the infrared absorbing layer. And a reflection layer having a flat portion parallel to the infrared absorption layer and a sloped portion not parallel to the infrared absorption layer.

With this configuration, the sharpness of resonance caused by the interference between the infrared rays incident on the infrared absorption layer and the infrared rays traveling the optical distance between the infrared absorption layer and the reflection layer is suppressed, so that the specific wavelength is suppressed. The sensitivity peak height for λ can be relaxed. As a result, it is possible to prevent a relative decrease in sensitivity in wavelength bands other than λ, and to broaden the detection wavelength band.

Further, since the reflecting layer has the uneven cross-sectional shape consisting of the flat portion and the inclined portion, mechanical vibration is suppressed, the shape is stable, and the impact resistance is improved as compared with the flat film.

In the present invention, it is preferable that the optical distance between the infrared absorption layer and the reflection layer is different in the detection plane.

With such a configuration, the resonance wavelength that satisfies the optical interference condition between the infrared absorption layer and the reflection layer changes according to the optical distance between them. As a result, sensitivity peaks can be generated for each of a plurality of wavelengths, so that the detection wavelength can be broadened as a whole.

Further, in the present invention, there may be a plurality of resonance wavelengths in which the phase of the infrared rays incident on the infrared absorption layer and the phase of the infrared rays that have reciprocated the optical distance between the infrared absorption layer and the reflection layer are substantially the same. preferable.

With such a configuration, sensitivity peaks can be generated for each of a plurality of resonance wavelengths, so that the detection wavelength can be broadened as a whole.

In the present invention, the infrared absorption layer is preferably made of a material whose electric resistance changes with temperature.

With this structure, the infrared absorption layer can also serve as the electric resistance changing member, so that the size of the entire detection unit can be reduced. As a result, the response speed and detection sensitivity to incident infrared rays can be improved.

Further, according to the present invention, a step of forming a reflection layer for reflecting infrared rays on a substrate, a step of providing a sacrifice layer on the reflection layer, and processing the surface of the sacrifice layer into a predetermined uneven shape. A method of manufacturing a thermal infrared detector, comprising: a step, a step of forming an infrared absorption layer on the sacrificial layer, and a step of removing the sacrificial layer.

By such a manufacturing method, the surface-processed shape of the sacrificial layer can be transferred to the three-dimensional shape of the infrared absorbing layer with high accuracy. As a result, the infrared absorption layer can be easily formed into a desired shape, and the optical distance between the infrared absorption layer and the reflection layer can be set with high accuracy over the detection surface.

Further, according to the present invention, a step of forming an infrared absorbing layer on a substrate, a step of providing a sacrificial layer on the infrared absorbing layer, and a step of processing the surface of the sacrificial layer into a predetermined uneven shape. A method of manufacturing a thermal infrared detector, comprising: a step of forming a reflective layer for infrared reflection on the sacrificial layer; and a step of removing the sacrificial layer.

By such a manufacturing method, the surface processed shape of the sacrificial layer can be transferred to the three-dimensional shape of the reflective layer with high accuracy. As a result, the reflection layer can be easily formed into a desired shape, and the optical distance between the infrared absorption layer and the reflection layer can be set with high accuracy over the detection surface.

Further, in the present invention, it is preferable that the sacrificial layer is formed of a photosensitive organic material. With such a manufacturing method, a photolithography method using a photomask or the like can be applied, and the three-dimensional shape of the sacrificial layer can be arbitrarily formed by controlling the exposure dose distribution. Therefore, for example, the through holes and the surface irregularities can be processed at the same time, and the number of steps and the manufacturing cost can be reduced.

Further, the viscosity of the organic material makes it difficult for minute irregularities such as a wiring pattern formed on the surface of the substrate to appear on the surface of the sacrificial layer, so that a transfer surface having excellent surface accuracy can be realized.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1A is a partial cross-sectional view showing an embodiment of the present invention, FIG. 1B is a partial plan view thereof, and FIG. 1A is A in FIG. 1B.
-Corresponds to the sectional view along the line A.

The thermal infrared detector 10 comprises a substrate 1, an infrared absorption layer 13 supported at a predetermined height position with a gap from the substrate 1, a reflection layer 3 provided on the substrate 1, and the like. In addition, it is a surface detection type that detects infrared rays incident from above in FIG.

The substrate 1 is formed of a semiconductor material such as silicon, and a semiconductor integrated circuit is formed in the substrate by a multilayer wiring technique. In FIG. 1A, a transistor or a connection for switching the infrared absorption layer 13 is connected. The scanning circuit 2 formed of a conductor or the like is illustrated. The upper surface of the substrate 1 is SiO ₂
An electric insulating layer 1a made of a semiconductor oxide film such as is formed.

The infrared absorption layer 13 is made of, for example, a bolometer material such as vanadium oxide, a copper oxide-based material, and amorphous silicon, and has a function of absorbing infrared rays incident from the outside and converting them into heat, and has an electric property as the temperature rises. It also has the function of changing resistance. By arranging the plurality of infrared absorption layers 13 one-dimensionally or two-dimensionally, it can be configured as an infrared line sensor or an infrared image sensor.

On the electrically insulating layer 1a of the substrate 1, a reflection layer 3 for reflecting infrared rays, a scanning circuit 2 and leg electrodes 12 are provided.
And a contact point 4 for electrically connecting and are formed.

The reflection layer 3 is formed of a metal material such as aluminum or gold, reflects infrared rays which are incident from the upper side of FIG.
It has the function of returning to the infrared rays and improves the infrared absorption efficiency.

The contact 4 is formed of a metal material such as aluminum, gold or copper, and can be formed in the same process as the reflective layer 3 by applying a photolithography method using the same material as the reflective layer 3.

The leg electrode 12 is made of a high-strength metal material capable of hollowly supporting the infrared absorption layer 13, and is preferably made of a material which can be easily processed into a desired shape. For example, titanium, titanium alloy, or nitride. Metals such as titanium, tungsten and cobalt and alloys thereof can be used.

The infrared absorption layer 13 is hollowly supported by a pair of leg electrodes 12 at both ends thereof and has a bridge structure, which prevents infrared absorption heat from being conducted to other members and dissipated. The heat capacity is reduced as much as possible to speed up the thermal response.

In this embodiment, the infrared absorption layer 13 is not a uniformly flat film, but has an uneven cross-sectional shape, and is parallel to the reflection layer 3 as shown in FIG. It has flat parts 13a and 13b and a slant part 13c that is not parallel to the reflective layer 3. By adopting such a concavo-convex shape, mechanical vibration is suppressed as compared with a flat film, the shape of the infrared absorption layer 13 is stabilized, and impact resistance is improved.

Further, the infrared rays incident on the infrared absorption layer 13 pass through without being absorbed by the infrared absorption layer 13,
The infrared rays that have traveled back and forth the optical distance between the infrared absorption layer 13 and the reflection layer 3 optically interfere with each other. Due to such interference, the infrared intensities in the infrared absorption layer 13 may mutually enhance or cancel each other.

As a countermeasure against this, in order to enhance the infrared intensity, the detection wavelength λ, the optical distance L between the infrared absorption layer 13 and the reflection layer 3, and the refractive index n between the infrared absorption layer 13 and the reflection layer 3 are set. , It is desirable that the following formula is established. n · L = λ / 4 (1)

Therefore, the optical distance La between the flat portion 13a and the reflective layer 3 and the optical distance Lb between the flat portion 13b and the reflective layer 3 are set so that the following expressions are established. n · La = λa / 4 (2) n · Lb = λb / 4 (3) Δλ = λb−λa = 4 · n (Lb−La) (4)

Here, the wavelength λa is the resonance wavelength due to the interference between the flat portion 13a and the reflection layer 3, the wavelength λb is the resonance wavelength due to the interference between the flat portion 13b and the reflection layer 3, and Δλ is It is the difference between the wavelength λb and the wavelength λa.

Optical distance La at flat portion 13a and flat portion 1
When the optical distance Lb at 3b is made different, the wavelength λa at which the sensitivity peak appears and the wavelength λb can be shifted by Δλ. As a result, a wide detection wavelength region including the peak at the wavelength λa and the peak at the wavelength λb can be obtained, and the detection wavelength can be broadened.

Further, by providing three or more flat portions having different optical distances from the reflection layer 3, it is possible to secure three or more different peak wavelengths, and to broaden the detection wavelength band as a whole. It will be possible.

Next, a method of manufacturing the thermal infrared detector 10 will be described. First, as shown in FIG. 2, by applying a semiconductor manufacturing process, a substrate 1 in which a scanning circuit 2 is arranged and an electric insulating layer 1a is provided on the surface is prepared, and the surface of the substrate 1 is formed using a photolithography method. Then, the reflective layer 3 and the contact 4 are formed.

Next, as shown in FIG.
A sacrificial layer 5 serving as a mold material for the hollow portion is arranged. As a material for the sacrificial layer 5, a material that is easily subjected to surface unevenness processing and mold removal processing is preferable. Here, a photosensitive organic material such as an organic resist material, for example, photosensitive polyimide is used. A photolithography method using a photomask or the like can be applied to such a photosensitive organic material, and the three-dimensional shape of the sacrificial layer can be arbitrarily formed by controlling the exposure dose distribution. In addition, since the fineness of the wiring pattern and the like formed on the surface of the substrate is less likely to appear on the surface of the sacrificial layer due to the viscosity of the organic material, a transfer surface with excellent surface accuracy can be realized.

Next, in order to expose the sacrificial layer 5 in a desired pattern, a photomask 6 is arranged above the sacrificial layer 5.
The photomask 6 includes a through-hole pattern 6a for forming the leg electrode 12, an unevenness-forming pattern 6b for forming an uneven shape on the surface of the sacrificial layer 5, a through-hole pattern 6a, and an unevenness-forming pattern. 6b has a flat auxiliary pattern 6c and the like. The concavo-convex forming pattern 6b changes the number of pinholes per unit area and the pinhole area to spatially control the exposure amount to the sacrificial layer 5.

Next, with the photomask 6 in place, the sacrificial layer 5 is exposed by using a light source that emits a photosensitive wavelength of the sacrificial layer 5, for example, ultraviolet rays or electron beams. After exposing the sacrificial layer 5, the photomask 6 is removed and the sacrificial layer 5 is developed.
A portion having a large exposure amount is removed, and as shown in FIG. 4, the through hole 5a is formed corresponding to the through hole pattern 6a.
Is formed, and the surface unevenness 5b is formed corresponding to the unevenness forming pattern 6b.

Next, as shown in FIG. 5, a thin film electrode for forming the leg electrode 12 is formed by a sputtering method, and the leg electrode 12 is formed along the through hole 5a by a photolithography method.

Next, as shown in FIG. 6, the infrared absorption layer 1
The bolometer thin film for forming 3 is formed by the sputtering method, and the infrared absorption layer 13 is formed along the surface unevenness 5b by the photolithography method.

Next, when the sacrificial layer 5 is ashed and removed by the oxygen plasma ashing method, the space in which the sacrificial layer 5 was present becomes hollow as shown in FIG. A bridge structure in which both ends are supported by the leg electrodes 12 is obtained.

FIG. 7 is a graph showing an example of the wavelength dependence of the thermal infrared detector 10. The vertical axis represents infrared absorption (%, linear arbitrary unit), and the horizontal axis represents wavelength (μm). Each graph shows the sensitivity spectrum when the optical distance L between the infrared absorption layer 13 and the reflection layer 3 is changed,
The broken line corresponds to L = 1 μm, the one-dot chain line corresponds to L = 2 μm, and the two-dot chain line corresponds to L = 3 μm. The refractive index n = 1 between the infrared absorption layer 13 and the reflection layer 3 is set.
Since the actual absorption occurs in the infrared absorption layer having a certain n value, a slight shift of the peak position occurs from the theoretical formula (1).

First, referring to the broken line graph, if the optical distance L between the infrared absorbing layer 13 and the reflecting layer 3 is set to 1 μm, the resonance wavelength λ can be calculated from equation (1) above to be 4 μm, which is approximately λ. = 4 μm, the sensitivity peak appears.

Next, referring to the one-dot chain line graph, if the optical distance L between the infrared absorption layer 13 and the reflection layer 3 is set to 2 μm, the resonance wavelength λ can be calculated to be 8 μm from the above formula (1), A sensitivity peak appears at about λ = 8 μm.

Next, referring to the chain double-dashed line graph, if the optical distance L between the infrared absorption layer 13 and the reflection layer 3 is set to 3 μm, the resonance wavelength λ can be calculated as 12 μm from the above equation (1). , A sensitivity peak appears at about λ = 12 μm.

Therefore, the infrared absorption layer 13 is shaped into a concave-convex shape in cross section, and the distance between the flat portions is optimized so that the optical distances L between the infrared absorption layer 13 and the reflection layer 3 are 1 μm, 2 μm, and 3 μm, respectively. Then, the respective graphs are averaged to obtain a sensitivity spectrum like a solid line graph. As a result, the height of the sensitivity peak of the specific wavelength is suppressed, and the detection wavelength is broadened as a whole.

Embodiment 2. FIG. 8 is a partial cross-sectional view showing another embodiment of the present invention. Thermal infrared detector 20
Is the substrate 1 and the infrared absorption layer 1 provided on the substrate 1.
3 and a reflective layer 3 supported at a predetermined height position with a gap from the substrate 1, and is a back surface detection type that detects infrared rays incident from below in FIG.

The substrate 1 is formed of a semiconductor material such as silicon that allows infrared rays to pass therethrough, and a semiconductor integrated circuit is formed in the substrate by a multilayer wiring technique. In FIG. 8, a transistor for switching the infrared absorption layer 13 is used. 1 illustrates a scanning circuit 2 including a connection conductor and the like. The upper surface of the substrate 1 is an electrically insulating layer 1 made of a semiconductor oxide film such as SiO _2.
a is formed, and a concave portion 1b is formed around the infrared absorption layer 13.

The infrared absorbing layer 13 is formed of, for example, a bolometer material such as vanadium oxide, a copper oxide-based material, and amorphous silicon, and has a function of absorbing infrared rays incident from the outside and converting them into heat, and an electrical function as the temperature rises. It also has the function of changing resistance. By arranging the plurality of infrared absorption layers 13 one-dimensionally or two-dimensionally, it can be configured as an infrared line sensor or an infrared image sensor.

On the electrically insulating layer 1a of the substrate 1, an infrared absorption layer 13 and a contact 4 for electrically connecting the infrared absorption layer 13 and the scanning circuit 2 are formed.

The infrared absorption layer 13 is hollowly supported by the pair of contacts 4 at both ends together with the electric insulation layer 1a in a hollow structure to form a bridge structure, which prevents infrared absorption heat from being conducted to other members and dissipated. At the same time, the heat capacity is made as small as possible to speed up the thermal response.

The contact 4 is made of a metal material such as aluminum, gold or copper and is formed into a desired pattern by photolithography.

The reflection layer 3 is made of a metal material such as aluminum or gold, reflects infrared rays which are incident from the lower side of FIG. 8 and have passed through the infrared absorption layer 13 via the substrate 1 to the infrared absorption layer 13. It has a returning function and improves infrared absorption efficiency.

The reflective layer 3 has a pair of leg members 3b at both ends thereof.
It is supported in the air by means of a bridge structure.

In this embodiment, the reflective layer 3 is not a flat film, but has an uneven cross-sectional shape. For example, as shown in FIG.
As shown in FIG. 3, the flat portions 3 a and 3 b are parallel to the infrared absorption layer 13, and the inclined portions 3 c are not parallel to the infrared absorption layer 13. By adopting such a concavo-convex shape, mechanical vibration is suppressed as compared with a flat film, the shape of the reflective layer 3 is stabilized, and impact resistance is improved.

Further, the infrared rays incident on the infrared absorption layer 13 pass through without being absorbed by the infrared absorption layer 13,
The infrared rays that have traveled back and forth the optical distance between the infrared absorption layer 13 and the reflection layer 3 optically interfere with each other. Due to such interference, the infrared intensities in the infrared absorption layer 13 may mutually enhance or cancel each other.

As a countermeasure against this, in order to enhance the infrared intensity, the detection wavelength λ, the optical distance L between the infrared absorption layer 13 and the reflection layer 3, and the refractive index n between the infrared absorption layer 13 and the reflection layer 3 are set. , It is desirable that the following formula is established. n · L = λ / 4 (1)

Therefore, the optical distance La between the flat portion 3a and the infrared absorbing layer 13 and the flat portion 3b and the infrared absorbing layer 13 are set.
The optical distance Lb between and is set so that the following equation holds. n · La = λa / 4 (2) n · Lb = λb / 4 (3) Δλ = λb−λa = 4 · n (Lb−La) (4)

Here, the wavelength λa is the resonance wavelength due to the interference between the flat portion 3a and the infrared absorption layer 13, and the wavelength λb.
Is the resonance wavelength due to the interference between the flat portion 3b and the infrared absorption layer 13, and Δλ is the difference between the wavelength λb and the wavelength λa.

Optical distance La at flat portion 3a and flat portion 3b
If the optical distance Lb in (1) is made different, the wavelength λa at which the sensitivity peak appears and the wavelength λb can be shifted by Δλ. As a result, a wide detection wavelength region including the peak at the wavelength λa and the peak at the wavelength λb can be obtained, and the detection wavelength can be broadened.

By providing three or more flat portions having different optical distances from the infrared absorption layer 13, three or more different peak wavelengths can be secured, and the detection wavelength can be broadened as a whole. It becomes possible to do.

Next, a method of manufacturing the thermal infrared detector 20 will be described. First, by applying the semiconductor manufacturing process, the scanning circuit 2 is arranged inside and the concave portion 1b is formed on the surface.
Then, the substrate 1 provided with the electric insulating layer 1a is prepared, and the infrared absorption layer 13 and the contact 4 are formed on the surface of the substrate 1 by using the photolithography method.

Next, as in FIG. 3, a sacrificial layer serving as a mold material for the hollow portion is arranged on the substrate 1. As the material of the sacrificial layer,
It is preferable to use a material that can be easily subjected to surface unevenness processing and mold removal processing, and here, a photosensitive organic material such as an organic resist material, for example, photosensitive polyimide is used. A photolithography method using a photomask or the like can be applied to such a photosensitive organic material, and the three-dimensional shape of the sacrificial layer can be arbitrarily formed by controlling the exposure dose distribution. In addition, since the fineness of the wiring pattern and the like formed on the surface of the substrate is less likely to appear on the surface of the sacrificial layer due to the viscosity of the organic material, a transfer surface with excellent surface accuracy can be realized.

Next, in order to expose the sacrificial layer in a desired pattern, a photomask is arranged above the sacrificial layer. The photomask connects the through-hole pattern for forming the leg member 3h, the concavo-convex forming pattern for forming the concavo-convex shape on the surface of the sacrificial layer, and the through-hole pattern and the concavo-convex forming pattern. It has a flat auxiliary pattern and the like. The concavo-convex forming pattern changes the number of pinholes per unit area and the pinhole area to spatially control the exposure amount to the sacrificial layer.

Next, the sacrifice layer is exposed while the photomask is arranged. After the exposure of the sacrificial layer, the photomask is removed and the sacrificial layer is developed to remove a portion having a large amount of exposure, so that a through hole is formed corresponding to the through hole pattern to form unevenness as in the case of FIG. Surface irregularities are formed corresponding to the use pattern.

Next, as in FIG. 5, thin film electrodes for forming the reflection layer 3 and the leg members 3h are formed by the sputtering method.

Next, when the sacrificial layer is ashed and removed by the oxygen plasma ashing method, as shown in FIG. 8, the space where the sacrificial layer was present becomes hollow, and both ends of the reflective layer 3 are formed by the leg members 3h. A supporting bridge structure is obtained.

In this embodiment, the infrared absorbing layer 13 has a simple shape, and the heat capacity can be further reduced. In particular, when it is desired to form the infrared absorption layer 13 prior to the step of forming the sacrifice layer, for example, it is necessary to form the infrared absorption layer 13 at a high temperature by using crystalline silicon, a pyroelectric material, or the like. It is suitable when it cannot be done.

In the above description, the structure in which the infrared absorbing layer 13 or the reflecting layer 3 is provided with the uneven shape is shown. However, the infrared absorbing layer 13 and the reflecting layer 3 may be provided with the uneven shape. It is possible.

Further, in the above description, an example in which the infrared absorption layer 13 is configured as a bolometer is shown, but a pyroelectric material or a PN is used.
It can also be configured as a diode or the like.

[0079]

As described in detail above, the infrared absorbing layer is
By having a flat portion parallel to the reflection layer and a sloped portion that is not parallel to the reflection layer, the infrared rays incident on the infrared absorption layer and the optical distance between the infrared absorption layer and the reflection layer are reciprocated. Since the sharpness of resonance caused by the interference with the infrared rays is suppressed, the height of the sensitivity peak for a specific wavelength λ can be relaxed. As a result, it is possible to prevent a relative decrease in sensitivity in wavelength bands other than λ, and to broaden the detection wavelength band. Further, since the infrared absorbing layer has the uneven cross-sectional shape composed of the flat portion and the inclined portion, mechanical vibration is suppressed, the shape is stabilized, and the impact resistance is improved as compared with the flat film.

Further, the reflecting layer has a flat portion parallel to the infrared absorbing layer and an inclined portion non-parallel to the infrared absorbing layer, so that the infrared ray incident on the infrared absorbing layer and the infrared absorbing layer Since the sharpness of resonance due to the interference with infrared rays that have traveled back and forth between the optical layer and the reflective layer is suppressed, the height of the sensitivity peak for a specific wavelength λ can be relaxed. As a result, it is possible to prevent a relative decrease in sensitivity in wavelength bands other than λ, and to broaden the detection wavelength band. Further, since the reflective layer has the uneven cross-sectional shape including the flat portion and the inclined portion, mechanical vibration is suppressed, the shape is stable, and the impact resistance is improved as compared with the flat film.

Further, since the optical distance between the infrared absorption layer and the reflection layer is different on the detection surface, the resonance wavelength satisfying the optical interference condition between the infrared absorption layer and the reflection layer is between them. It will change according to the optical distance. As a result, sensitivity peaks can be generated for each of a plurality of wavelengths, so that the detection wavelength can be broadened as a whole.

Further, since there are a plurality of resonance wavelengths in which the phase of the infrared rays incident on the infrared absorption layer and the phase of the infrared rays that have reciprocated the optical distance between the infrared absorption layer and the reflection layer are substantially the same, there are a plurality of resonance wavelengths. Since the sensitivity peaks can be generated for each resonance wavelength, the detection wavelength can be broadened as a whole.

Further, since the infrared absorption layer is made of a material whose electric resistance changes according to temperature, the infrared absorption layer can also serve as an electric resistance changing member, so that the size of the entire detection unit can be reduced. As a result, the response speed and detection sensitivity to incident infrared rays can be improved.

When forming a hollow support structure for the infrared absorption layer or the reflection layer, the sacrificial layer is used to transfer the surface-processed shape of the sacrifice layer to the three-dimensional shape of the infrared absorption layer or the reflection layer with high accuracy. be able to. As a result, the infrared absorption layer or the reflection layer can be easily formed into a desired shape, and the optical distance between the infrared absorption layer and the reflection layer can be set with high accuracy over the detection surface.

By forming the sacrificial layer from a photosensitive organic material, a photolithography method using a photomask or the like can be applied, and the three-dimensional shape of the sacrificial layer can be arbitrarily formed by controlling the exposure dose distribution. Therefore, for example, the through holes and the surface irregularities can be processed at the same time, and the number of steps and the manufacturing cost can be reduced. Also,
Due to the viscosity of the organic material, minute irregularities such as a wiring pattern formed on the surface of the substrate are less likely to appear on the surface of the sacrificial layer, so that a transfer surface with excellent surface accuracy can be realized.

[Brief description of drawings]

FIG. 1A is a partial cross-sectional view showing an embodiment of the present invention, and FIG. 1B is a partial plan view thereof.

FIG. 2 is an explanatory diagram showing an example of a method for manufacturing the thermal infrared detector 10.

FIG. 3 is an explanatory diagram showing an example of a method for manufacturing the thermal infrared detector 10.

FIG. 4 is an explanatory diagram showing an example of a method for manufacturing the thermal infrared detector 10.

FIG. 5 is an explanatory diagram showing an example of a method of manufacturing the thermal infrared detector 10.

FIG. 6 is an explanatory diagram showing an example of a method for manufacturing the thermal infrared detector 10.

7 is a graph showing an example of wavelength dependence of the thermal infrared detector 10. FIG.

FIG. 8 is a partial cross-sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1 substrate, 1a electrical insulating layer, 1b recess, 2
Scanning circuit, 3 reflective layer, 3a, 3b flat part, 3
c inclined part, 3h leg member, 4 contact points, 5 sacrificial layer, 5b surface unevenness, 6 photomask, 6a
Through-hole pattern, 6b Concavo-convex forming pattern, 6c Auxiliary pattern, 10 Thermal infrared detector, 12 Leg electrode, 13 Infrared absorbing layer, 13
a, 13b Flat part, 13c Inclined part, 20 Thermal infrared detector

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G065 AA04 AB02 BA12 BB24 BB25                       BE08 DA20                 2G066 AC13 AC16 BA01 BA03 BA04                       BA09 BA11 BA12 BA13 BA55                 4M118 AA01 AA10 AB04 BA19 CA09                       CA15 CA20 CA27 CA35 CA40                       CB06 CB14 EA04 GA08 GA10                       GD15 GD16

Claims (8)

[Claims] 1. An infrared absorption layer for absorbing infrared rays incident from the outside and converting the infrared rays into heat, and a reflection layer for reflecting the infrared rays passing through the infrared absorption layer and returning the infrared rays to the infrared absorption layer. The infrared absorption layer has a flat portion parallel to the reflection layer and an inclined portion non-parallel to the reflection layer. 2. An infrared absorption layer for absorbing infrared rays incident from the outside and converting them into heat, and a reflection layer for reflecting the infrared rays that have passed through the infrared absorption layer and returning the infrared rays to the infrared absorption layer, The thermal infrared detector, wherein the reflective layer has a flat portion parallel to the infrared absorbing layer and a sloped portion not parallel to the infrared absorbing layer. 3. The thermal infrared detector according to claim 1, wherein the optical distance between the infrared absorption layer and the reflection layer is different in the detection plane. 4. A plurality of resonance wavelengths in which the phase of the infrared rays incident on the infrared absorption layer and the phase of the infrared rays reciprocating the optical distance between the infrared absorption layer and the reflection layer are substantially coincident with each other. The thermal infrared detector according to claim 3. 5. The infrared absorption layer is formed of a material whose electric resistance changes with temperature.
The thermal infrared detector according to any one of 1 to 4. 6. A step of forming a reflective layer for infrared reflection on a substrate, a step of providing a sacrificial layer on the reflective layer, and a step of processing the surface of the sacrificial layer into a predetermined uneven shape. A method of manufacturing a thermal infrared detector, comprising: a step of forming an infrared absorption layer on the sacrificial layer; and a step of removing the sacrificial layer. 7. A step of forming an infrared absorbing layer on a substrate, a step of providing a sacrificial layer on the infrared absorbing layer, a step of processing the surface of the sacrificial layer into a predetermined uneven shape, and a sacrificial layer. A method for manufacturing a thermal infrared detector, comprising: a step of forming a reflective layer for infrared ray reflection on the top surface; and a step of removing the sacrificial layer. 8. The method for manufacturing a thermal infrared detector according to claim 6, wherein the sacrificial layer is formed of a photosensitive organic material.