JP2000356545A - Infrared detection element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared detection element having a large resistance value and a large infrared absorption reception area as a temperature-measuring part by forming the element of a high-concentration impurities-doped area on an SOI substrate in a spiral pattern turning back at the center. SOLUTION: A silicon oxide film 3 is formed on a surface of a silicon substrate 2 constituting an SOI substrate 1, on which a silicon activation layer 4 is formed. A temperature-measuring part and infrared-absorbing part 5 is formed to the silicon activation layer 4. Boron as a high-concentration impurity is doped to the part, which is formed in a spiral shape turning back at the center. The infrared detection element can be obtained in which a resistance value can be increased as the temperature-detecting part and moreover an infrared absorption reception area can be increased. Aluminum electrode parts 6 and 7 are set to both ends of the temperature-measuring and infrared- absorbing part 5, and the silicon substrate 2 and silicon oxide film 3 are selectively removed to form a hollow part 8. A general semiconductor production process can be used to manufacture the element, and the element stable in quality can be manufactured with a high yield.

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 and a method of manufacturing the same, and more particularly, to an infrared detecting element which is easy to manufacture and suitable for mass production, can avoid stress concentration, has a strong structure, and has a strong structure. The present invention relates to an infrared detecting element using a silicon single crystal, in which a resistance value as a warm part can be increased, a light receiving area as infrared absorption can be increased.

[0002]

2. Description of the Related Art A thin film bolometer is one type of infrared detecting element conventionally used. Thin-film bolometers mainly use ceramics such as a metal oxide film as a resistance temperature detector. A resistance pattern is formed on a substrate using a hard mask or the like, electrodes are formed, and an absorbing material or the like is formed. It is manufactured by applying.

An important factor in such a thin film bolometer is the physical properties of the resistance temperature detector. An important technical factor is how to form a film having a high resistance temperature coefficient and low noise. . The properties of the resistance thermometer greatly change if the composition ratio of the substance or the like changes.

[0004] Noise is measured at the time of shipment to select non-defective products. On the other hand, such a resistor generally has a very high resistivity and can be applied with a high voltage in order to improve the sensitivity, but has a large variation in resistance value and requires a booster circuit.

A thin-film bolometer, which is a thermal detector, receives an irradiated radiant flux of an infrared ray to be measured by an absorber, converts the radiant flux into heat, and converts the temperature change into an electric signal at each of the resistance temperature detectors. Convert and measure irradiance.

At this time, it is important to efficiently convert the heat converted by the absorber into a temperature change.
The thermal conductance between the temperature measuring unit and the substrate must be as small as possible. Further, in order to increase the response speed, the heat capacity must be small.

[0007]

However, in the above-mentioned conventional manufacturing method, it is difficult to perform complicated patterning in order to improve the thermal conductance, and the thermal conductance, The heat capacity deteriorates.

That is, since the performance of the thin film bolometer greatly depends on the physical property value of the resistance temperature detector, it greatly changes depending on the film forming conditions, and a dedicated film forming apparatus is required.
Further, since the absorption depends on the absorbing material, it is difficult to improve the thermal conductance and the heat capacity.

Furthermore, it is difficult to automate the use of a hard mask and the application of an absorbing material, and variations in these manufacturing processes affect variations in performance between elements.

Next, in order to obtain an element having a large resistance value, for example, the element may be configured in a meandering (meandering) shape. However, stress concentrates on the folded portion, and the limit on the length of the resistor that can be manufactured to obtain an appropriate resistance value increases.

Further, during self-heating, a temperature difference occurs between the adjacent resistors, and there is a possibility that the resistors will be deformed unevenly when a high bias is applied.

The present invention focuses on such a problem. SUMMARY OF THE INVENTION An object of the present invention is to provide an infrared detecting element having an easy manufacturing process, suitable for mass production, a strong structure, a large resistance value as a temperature measuring section, and a large light receiving area as infrared absorption, and a method of manufacturing the same. Is to provide.

[0013]

In order to achieve the above object, according to the present invention, in the infrared detecting element of the first aspect, the center folded back formed on the SOI substrate by the doped region of the high concentration impurity is provided. Characterized by being formed as a spiral pattern.

As a result, the infrared detecting element having such a structure can be manufactured by using a general semiconductor manufacturing process, and an infrared element capable of producing a stable element at a high yield can be obtained.

Further, since the temperature measuring portion and the infrared absorbing portion are formed in a spiral pattern with the center folded back, an infrared element capable of increasing the resistance value as the temperature measuring portion and increasing the light receiving area for absorbing infrared rays can be provided. can get.

By forming the temperature measuring portion and the infrared absorbing portion in a spiral shape (spiral shape) folded back at the center, it is possible to avoid concentration of stress, which is likely to occur when the meandering shape is formed. An element is obtained.

Further, by gradually increasing the width of the root portion of the beam (temperature measuring portion and infrared absorbing portion), an infrared device capable of further improving the strength can be obtained. In addition, when the temperature measuring part and the infrared absorbing part are used, the central part where the temperature becomes higher due to self-heating is strong, and an infrared element is obtained in which the deformation occurs uniformly in the radial direction.

According to a second aspect of the present invention, in the infrared detecting element according to the first aspect, a hollow portion is formed below the temperature measuring portion and the infrared absorbing portion.

As a result, since a hollow portion is formed,
The temperature measuring part and the infrared absorbing part can be thermally and almost insulated from the SOI substrate, the thermal conductance becomes extremely small, and an infrared element that can greatly improve the heat capacity characteristic can be obtained.

According to a third aspect of the present invention, in the method for manufacturing an infrared detecting element, a step of forming a silicon oxide film on the back surface of the SOI substrate; and a step of doping a high concentration impurity in an active layer of the SOI substrate. Forming a metal layer on the active layer of the SOI substrate, forming the metal layer in an electrode pattern, performing anisotropic etching using the silicon oxide film on the back surface of the SOI substrate as a mask, and performing a temperature measurement unit and an infrared absorption unit And a step of forming the high-concentration impurity-doped region in a temperature-measuring section and an infrared-absorbing section having a spiral pattern with a central turn.

As a result, since such a method for manufacturing an infrared detecting element is employed, the infrared detecting element can be manufactured by using a general semiconductor manufacturing process, and an element having stable quality can be manufactured at a high yield. A method for manufacturing a device is obtained.

According to a fourth aspect of the present invention, in the method for manufacturing an infrared detecting element, a step of epitaxially growing a silicon single crystal layer doped with a high concentration impurity on an n-type silicon substrate is provided. Forming a folded spiral-shaped pattern in the temperature measuring portion and the infrared absorbing portion and forming a hollow portion in a lower portion thereof.

As a result, such a method for manufacturing an infrared device can be simplified and a low-cost method for manufacturing an infrared device can be obtained because all the manufacturing steps can be performed only by processing from the surface of the n-type silicon substrate.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of a characteristic example of the dependency of noise and the temperature coefficient of resistance on the resistivity of a silicon single crystal resistor obtained by doping boron as an impurity on an SOI (Silicon on insulator) substrate. The detectability of a bolometer is proportional to the temperature coefficient and inversely proportional to noise.

Therefore, from the graph of FIG. 1, the resistivity is 5 ×
It is understood that 10-3 Ωcm or less is suitable. When the resistivity is 5 × 10 −3 Ωcm or less, it is approximately 5 × 10 19 / cm 3 or more when converted to boron concentration.

FIG. 2 is an explanatory diagram of a characteristic example of the resistivity dependence of the absorption coefficient in the infrared region. As is clear from FIG. 2, the smaller the resistivity, the larger the absorption coefficient in the infrared region. However, the resistivity at this concentration is as low as 5 × 10 −3 Ωcm or less.

If the resistance temperature detector does not have a certain resistance value, it is difficult to measure the temperature, and even with a small bias voltage, an excessive current flows, causing self-heating and current noise. Therefore, in the present invention, the resistance thermometer is formed in a spiral shape with the center turned back to increase the resistance value.

Further, by separating the resistance temperature detector from the substrate except for the portion from which the electrode is taken out, and by making it the minimum thickness necessary for it to be independent, the thermal conductance is minimized and the heat capacity is minimized. Can be improved.

FIG. 3 shows an embodiment of the present invention.
FIG. 3 is a configuration explanatory view showing a part cut away. In the figure, S
A silicon oxide film 3 is formed on the surface of a silicon substrate 2 constituting the OI substrate 1, and a silicon active layer 4 is formed on the silicon oxide film 3.

In this embodiment, the silicon active layer 4
A high-concentration (approximately 5.times.10@19 / cm @ 3) impurity is doped with boron to form a spiral-shaped temperature measuring portion / infrared absorbing portion 5 which is folded at the center.

Aluminum electrodes 6 and 7 are provided at both ends of the temperature measuring / infrared absorbing section 5, respectively. Silicon substrate 2 and silicon oxide film 3 under temperature measuring and infrared absorbing part 5
Is selectively removed to form a hollow portion 8.

In the present embodiment, the resistor width of the temperature measuring section and the infrared absorbing section 5 is 10 μm, line: space 1: 1 and the resistor thickness is 1.7.
μm, resistor length (narrow part): 1 cm or more, resistance value 20 kΩ or more.

The infrared detecting element having such a structure can be manufactured by using a general semiconductor manufacturing process, and an infrared element capable of producing a stable element at a high yield can be obtained.

Further, since the temperature measuring portion and the infrared absorbing portion 5 are formed in a spiral pattern with the center folded, the resistance value of the temperature measuring portion can be increased and the light receiving area for absorbing infrared light can be increased. An element is obtained.

By forming the temperature measuring portion and the infrared absorbing portion 5 in a spiral shape (spiral shape) having a center turn, it is possible to avoid concentration of stress, which is likely to occur when the meandering shape is formed. An infrared device is obtained. Further, by gradually widening the width of the root portion of the beam (temperature measuring part and infrared absorbing part 5), an infrared element capable of further improving the strength can be obtained.

In addition, when the temperature measuring part and the infrared absorbing part 5 are used, the central part where the temperature becomes higher due to self-heating is strong, and an infrared element in which deformation occurs uniformly in the radial direction can be obtained. .

Since the hollow portion 8 is formed below the temperature measuring section and infrared absorbing section 5, the temperature measuring section and infrared absorbing section 5 can be thermally and almost insulated and separated from the SOI substrate 1. As a result, the thermal conductance becomes extremely small, and an infrared device capable of greatly improving the heat capacity characteristic can be obtained.

The infrared detecting element having the structure shown in FIG. 3 is manufactured by, for example, the following steps. A silicon oxide film (not shown) for a mask in an etching process is formed on the back surface of the SOI substrate 1.

The silicon active layer 4 of the SOI substrate 1 is doped with an impurity (for example, boron), a metal for an electrode (for example, aluminum) is deposited, and patterned as electrodes 6 and 7.

The silicon oxide film on the back side of the SOI substrate 1 is patterned, and the silicon substrate 2 is anisotropically etched with an alkali solution such as hydrazine using the intermediate silicon oxide film 3 as an etching stop layer. (Diaphragm).

In order to avoid stress deformation due to the multilayer structure of the diaphragm 8, the silicon oxide film 3 on the back surface of the diaphragm 8 is removed with a hydrofluoric acid-based etchant.

Using a photoresist film (not shown) as a mask and the intermediate silicon oxide film layer 3 as an etch stop layer, the silicon active layer 4 is processed into a center-turned spiral shape (spiral shape) by a dry etching apparatus to remove the resist. And bonding.

As a result of measuring this device in a vacuum, the noise was reduced to almost Johnson noise, the temperature coefficient of resistance was 0, 19% / K, the bridge voltage was 3.0 V, and the specific detection capability D
* = 1 × 10 8 cm√Hz / W (at 500 K black body furnace, chopping 10 Hz, amplification bandwidth 1 Hz) was obtained.

As a result, since such a method of manufacturing an infrared detecting element is employed, the infrared detecting element can be manufactured using a general semiconductor manufacturing process, and an element having stable quality can be manufactured at a high yield. A method for manufacturing a device is obtained.

FIG. 4 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 5 is a sectional view taken along line AA of FIG. In the figure,
On an n-type silicon substrate 11, a temperature measuring part and an infrared absorbing part 12 formed in a spiral pattern with a center turn after epitaxially growing a silicon single crystal layer doped with a high concentration impurity is formed.

Electrode take-out sections 13 and 14 are formed at both ends of the temperature measurement section / infrared absorption section 12, respectively. A hollow portion 15 is formed below the temperature measuring section and infrared absorbing section 12, and the temperature measuring section and infrared absorbing section 12 has a beam shape.

A silicon oxide film 16 is formed on the surface of the silicon substrate 11 other than the temperature measurement / infrared absorption section 12 and the electrode extraction sections 13 and 14. The infrared detecting element having such a structure can be manufactured by using a general semiconductor manufacturing process similarly to the element of FIG. 3, and an infrared element capable of producing a stable element at a high yield can be obtained.

Further, since the temperature measuring portion and the infrared absorbing portion 12 are also formed in a spiral pattern with the center folded in the same manner as in FIG. 3, the resistance value of the temperature measuring portion can be increased, and the light receiving area for absorbing infrared light can be reduced. An infrared device that can be enlarged can be obtained.

Since the hollow portion 15 is formed below the temperature measuring section and infrared absorbing section 12 as in FIG. 3, the temperature measuring section and infrared absorbing section 12 are substantially thermally insulated from the silicon substrate 11. The infrared element can be separated, the thermal conductance becomes extremely small, and the heat capacity characteristic can be greatly improved.

The infrared detecting element having the structure shown in FIG. 4 is manufactured, for example, by the following steps. On the n-type silicon substrate 11, a silicon single crystal layer doped with impurities at a high concentration is epitaxially grown.

Using a photoresist film (not shown) as a mask, an unnecessary portion of the high-concentration silicon single crystal layer which is not involved in the formation of the temperature measuring portion and the infrared absorbing portion 12 is removed by a dry etching device.

A silicon oxide film 14 is formed on the n-type silicon substrate 9 and holes for anisotropic etching and contact are formed. A metal, such as gold-chromium, which resists the alkaline solution used is deposited and patterned as an electrode.

Using the silicon oxide film 16 and the high-concentration silicon single crystal layer as an etching stop layer, anisotropic etching is performed on the n-type silicon substrate 13 with an alkali solution such as hydrazine to form a center-folded beam having a spiral pattern. A temperature measuring part and an infrared absorbing part 12 are formed and bonded.

In the device having the structure shown in FIG. 4, the entire manufacturing process can be performed only by processing from the surface of the n-type silicon substrate 11.
As compared with the manufacturing process of the structure shown in FIG. 3, a method for manufacturing an infrared device that can be simplified and inexpensive can be obtained.

Further, as an effect common to these embodiments, since a semiconductor manufacturing process is used, an amplifier circuit can be formed on the same substrate as an element, or can be arrayed and used as an imaging element. It can be developed.

As described above, according to the first aspect of the present invention, the following effects can be obtained. An infrared detecting element was formed on an SOI substrate, wherein the infrared detecting element was formed as a spiral pattern having a center turn formed by a doped region of a high concentration impurity.

As a result, the infrared detecting element having such a structure can be manufactured by using a general semiconductor manufacturing process, and an infrared element capable of producing a stable element at a high yield can be obtained.

Further, since the temperature measuring portion and the infrared absorbing portion are formed in a spiral pattern with the center folded back, an infrared element capable of increasing the resistance value as the temperature measuring portion and increasing the light receiving area for absorbing infrared light can be provided. can get.

By forming the temperature measuring portion and the infrared absorbing portion in a spiral shape (spiral shape) folded back at the center, it is possible to avoid concentration of stress, which is likely to occur when a meandering (meandering) shape is formed. An element is obtained.

Further, by gradually increasing the width of the root portion of the beam (temperature measuring portion and infrared absorbing portion), an infrared device capable of further improving the strength can be obtained. In addition, when the temperature measuring part and the infrared absorbing part are used, the central part where the temperature becomes higher due to self-heating is strong, and an infrared element is obtained in which the deformation occurs uniformly in the radial direction.

According to the second aspect of the present invention, the following effects can be obtained. The infrared detecting element according to claim 1, wherein a hollow portion is formed below the temperature measuring portion and the infrared absorbing portion.

As a result, since a hollow portion is formed,
The temperature measuring part and the infrared absorbing part can be thermally and almost insulated from the SOI substrate, the thermal conductance becomes extremely small, and an infrared element that can greatly improve the heat capacity characteristic can be obtained.

According to the third aspect of the present invention, the following effects can be obtained. Forming a silicon oxide film on the back surface of the SOI substrate, doping the active layer of the SOI substrate with high-concentration impurities, forming a metal layer on the active layer of the SOI substrate, and using the metal layer as an electrode pattern. Forming and S
Anisotropic etching using a silicon oxide film on the back surface of the OI substrate as a mask to form a hollow portion below the temperature measuring portion and the infrared absorbing portion, and measuring a spiral pattern in which the high-concentration impurity-doped region is folded back at the center. A method of manufacturing an infrared detecting element including a step of forming a warm part and an infrared absorbing part.

As a result, since such a method of manufacturing an infrared detecting element is employed, the infrared detecting element can be manufactured using a general semiconductor manufacturing process, and an element having stable quality can be manufactured at a high yield. A method for manufacturing a device is obtained.

According to the fourth aspect of the present invention, the following effects can be obtained. a step of epitaxially growing a silicon single crystal layer doped with a high concentration of impurity on an n-type silicon substrate; and forming the silicon single crystal layer in a temperature-measuring part and an infrared absorption part in a spiral pattern with a center folded back and a hollow underneath. And a step of forming a portion.

As a result, such a method for manufacturing an infrared device can be simplified and a low-cost method for manufacturing an infrared device can be obtained because all the manufacturing steps can be performed only by processing from the surface of the n-type silicon substrate.

Therefore, an infrared detecting element which has a simple manufacturing process, is suitable for mass production, has a strong structure, can have a large resistance value as a temperature measuring section, and can have a large light receiving area as infrared absorption, and a manufacturing method thereof. Can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a characteristic example of the dependence of the noise and the temperature coefficient of resistance on the resistivity of a silicon single crystal resistor.

FIG. 2 is an explanatory diagram of a characteristic example of a resistivity dependency of an absorption coefficient in an infrared region.

FIG. 3 is a configuration explanatory view showing one embodiment of the present invention with a part cut away.

FIG. 4 is a structural explanatory view showing another embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 SOI substrate 2 Silicon substrate 3 Silicon oxide film 4 Silicon active layer 5 Temperature measurement part and infrared absorption part 6 Aluminum electrode part 7 Aluminum electrode part 8 Hollow part 11 n-type silicon substrate 12 Temperature measurement part and infrared absorption part 13 Electrode extraction part 14 Electrode take-out part 15 Hollow part 16 Silicon oxide film

Claims (4)

[Claims] 1. An infrared detecting element formed on a SOI substrate as a spiral pattern with a center turn formed by a doped region of a high concentration impurity. 2. The infrared detecting element according to claim 1, wherein a hollow portion is formed below the temperature measuring portion and the infrared absorbing portion. A step of forming a silicon oxide film on a back surface of the SOI substrate; a step of doping an active layer of the SOI substrate with high-concentration impurities; a step of forming a metal layer on the active layer of the SOI substrate; Forming a layer in an electrode pattern; performing anisotropic etching using a silicon oxide film on the back surface of the SOI substrate as a mask to form a hollow portion below the temperature measuring portion and the infrared absorbing portion; Forming a region on a temperature measuring portion and an infrared absorbing portion in a spiral pattern with a center folded back. 4. A step of epitaxially growing a silicon single crystal layer doped with high-concentration impurities on an n-type silicon substrate, and forming the silicon single crystal layer on a temperature measuring portion and an infrared absorbing portion in a center-turned spiral pattern. And a step of forming a hollow portion in the lower part thereof.