JP6510265B2 - Method for manufacturing quantum infrared device and etchant for manufacturing quantum infrared device - Google Patents

Description

The present invention relates to a method of manufacturing a quantum infrared device and an etchant for manufacturing a quantum infrared device.

  In general, infrared rays in a long wavelength band having a wavelength of 5 μm or more are used for a human sensor for detecting a human body, a noncontact temperature sensor, a gas sensor, etc. from the thermal effect and the effect of infrared absorption by gas. Among these usage examples, as infrared sensors used as human body detection and non-contact temperature sensors, thermal infrared sensors such as pyroelectric sensors and thermopiles, and quantum infrared sensors using semiconductor light receiving elements is there. These infrared sensors are characterized in that the infrared sensors of the quantum type have high sensitivity, high-speed response, and can detect a static body as compared with the thermal infrared sensors.

As such a quantum type infrared sensor, one provided with a compound semiconductor multilayer portion including indium (In) and antimony (Sb) is widely used.
In general, a quantum type infrared device provided with a compound semiconductor multilayer including In and Sb forms a mesa-shaped operating part, and its manufacturing process requires an etching step. Note that a quantum infrared device (also referred to as a quantum infrared device) as used herein refers to a device that detects or emits infrared light, such as a quantum infrared sensor, an infrared light receiving element, an infrared light emitting element, or the like.
Typical etching techniques include dry etching and wet etching. Wet etching is advantageous in that the unit cost is lower than dry etching and that many wafers can be processed simultaneously. Wet etching is etching that utilizes a chemical reaction between a semiconductor and an etching solution (see, for example, Patent Document 1 and Patent Document 2).

JP, 2014-72217, A JP 2013-211454 A

By the way, in a quantum type infrared device provided with a compound semiconductor multilayer portion including In and Sb, it is extremely important also to improve the reliability that a good wiring layer with little variation in wiring resistance or the like is obtained.
However, under the conditions of the conventional wet etching, etch pits (dents) derived from defects during crystal growth occur in the film formation process of each layer of the compound semiconductor laminated portion, and metal interconnections are formed in the etch pit portions. There may be variations in resistance.
The present invention was made in view of the above problems, and a method of manufacturing a quantum infrared device capable of suppressing generation of etch pits and obtaining a good wiring layer, and an etchant for manufacturing a quantum infrared device The purpose is to provide.

  A method of manufacturing a quantum infrared device according to an aspect of the present invention is a method of manufacturing a quantum infrared device having a mesa structure, comprising: a first compound semiconductor layer of a first conductivity type including In and Sb on a substrate And a compound semiconductor multilayer portion in which a second compound semiconductor layer of a second conductivity type different in conductivity type from the first conductivity type is stacked in this order from the substrate side, the mass concentration is 3.5 wt% or more Providing a mesa forming step of wet etching using an etchant containing 5.5 wt% or less of hydrochloric acid and hydrogen peroxide to form the mesa structure in which a part of the first compound semiconductor layer is exposed; It features.

In the etchant for manufacturing a quantum infrared device according to another aspect of the present invention, the first compound semiconductor layer of the first conductivity type containing In and Sb and the first conductivity type are conductivity types on the substrate. A mesa structure in which a part of the first compound semiconductor layer is exposed by wet etching a compound semiconductor laminated portion in which second compound semiconductor layers of different second conductivity types are stacked in this order from the substrate side The etchant is used in the step of forming H.sub.2 O.sub.2, wherein the etchant contains hydrochloric acid having a mass concentration of 3.5 wt.% Or more and 5.5 wt.% Or less and hydrogen peroxide.

  According to one aspect of the present invention, the occurrence of etch pits can be reduced, and variations in interconnect resistance can be suppressed.

It is sectional drawing which shows an example of the manufacturing process of the quantum type infrared device in one Embodiment of this invention. It is explanatory drawing for demonstrating the ratio of the etch pit of the quantum type infrared device in one Embodiment of this invention. 5 is an example of an image showing the surface shape of the first conductive compound semiconductor layer of the quantum infrared device in Example 1. FIG. It is an example of the image which shows the surface shape of the 1st conductivity type compound semiconductor layer of the quantum type infrared device in the comparative example 1. FIG. 15 is an example of an image showing a cross-sectional shape of a quantum infrared sensor as a quantum infrared device in Comparative Example 1. FIG. 16 is an example of an image showing the surface shape of the first conductive compound semiconductor layer of the quantum infrared device in Example 2. FIG. FIG. 16 is an example of an image showing the surface shape of the first conductive compound semiconductor layer of the quantum infrared device in Example 3. FIG. FIG. 18 is an example of an image showing the surface shape of the first conductive compound semiconductor layer of the quantum infrared device in Example 4. FIG.

In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent that other embodiments can be practiced without being limited to such specific specific configurations. In addition, the following embodiments do not limit the invention according to the claims, and include all combinations of characteristic configurations described in the embodiments.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In a method of manufacturing a quantum infrared device according to an embodiment of the present invention, a first compound semiconductor layer of a first conductivity type containing In and Sb and a second compound semiconductor layer of a second conductivity type are formed on a substrate. A wet etching process is carried out using an etchant containing hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less and hydrogen peroxide; And a mesa forming step of forming a mesa-shaped compound semiconductor laminated portion in which a part of the compound semiconductor layer is exposed. The second conductivity type is different from the first conductivity type in conductivity type.
Incidentally, conventionally, wet etching is performed with an etchant having a higher hydrochloric acid concentration, and in the example of Patent Document 2, for example, an etchant having a hydrochloric acid concentration of 14.4 wt% to 23.0 wt% is used.

In one embodiment of the present invention, as described above, the compound semiconductor multilayer portion having the first conductivity type compound semiconductor layer containing In and Sb is hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less By performing the wet etching process using an etchant containing hydrogen peroxide and hydrogen peroxide, it becomes possible to reduce the etch pit more than in the past.
Further, in the method of manufacturing a quantum infrared device according to an embodiment of the present invention, a viewpoint from which a signal from a compound semiconductor lamination is efficiently taken out, and a plurality of mesa-shaped compound semiconductor laminations are connected in series or in parallel. In order to improve the output, a step of forming a wiring layer may be further included after the step of forming the mesa.
In addition, the method for manufacturing a quantum infrared device according to one embodiment of the present invention further includes, after the mesa formation step, a singulation step of singulating the quantum infrared device and a packaging step using a sealing resin. It is also good.

  The quantum infrared device according to the present embodiment includes a substrate and a mesa-shaped compound semiconductor laminated portion formed on the substrate, and the compound semiconductor laminated portion is a mesa of the mesa-shaped compound semiconductor laminated portion from the substrate side. A first compound semiconductor layer of a first conductivity type including In and Sb forming a bottom portion, and a second conductivity type of a second conductivity type different from the first conductivity type forming an upper portion of the mesa of the mesa-shaped compound semiconductor multilayer portion And an etch pit existing on the surface of the first compound semiconductor relative to the area of the surface of the first compound semiconductor layer when the mesa-shaped compound semiconductor multilayer portion is viewed in plan The area ratio of is less than 0.09.

By setting the ratio of the area of the etch pits present on the first compound semiconductor surface to not more than 0.09, it is possible to suppress the variation in wiring resistance and the like more than in the past, and obtain a quantum infrared device with high reliability. .
The quantum infrared device according to the embodiment of the present invention may have a wiring layer on the first compound semiconductor layer and the second compound semiconductor layer.
The method for producing the quantum infrared device according to the embodiment of the present invention is not particularly limited, and can be produced, for example, by the method for producing the quantum infrared device according to the embodiment of the present invention described later.

<Description of Components of Quantum Infrared Device>
Hereinafter, each component in the manufacturing method of the quantum type infrared device and the quantum type infrared device in one embodiment of the present invention will be described. The features of each component described below can be applied singly or in combination without departing from the technical concept of the present invention.
As a quantum type infrared device in one embodiment of the present invention, a quantum type infrared sensor, an infrared light emitting element, an infrared light receiving element, etc. are applicable, for example.

[substrate]
As shown in FIG. 1A, in the quantum infrared device according to one embodiment of the present invention, the substrate 10 is a first compound semiconductor layer 21 of the first conductivity type including In and Sb on the substrate 10. The first compound semiconductor layer 21 is not particularly limited as long as it can form the compound semiconductor multilayer portion 20 having the second compound semiconductor layer 23 of the second conductivity type different in conductivity type.
From the viewpoint of forming the first compound semiconductor layer 21 of the first conductivity type containing high-quality In and Sb, it is preferable to use a substrate having a lattice constant close to that of the first compound semiconductor layer 21. As the substrate 10, as an example, a silicon (Si) substrate or a gallium arsenide (GaAs) substrate can be applied. Moreover, what formed what is called a buffer layer on the board | substrate 10 which consists of a specific material can be regarded as the board | substrate 10 as one. For example, when a GaAs buffer layer is formed on a Si substrate and the first compound semiconductor layer 21 is formed thereon, the Si substrate and the GaAs buffer layer can be regarded as the substrate 10 in combination.

From the viewpoint of efficiently extracting the signal from the compound semiconductor laminate portion 20 to the outside, or from the viewpoint of enabling the output to be improved by connecting a plurality of mesa-shaped compound semiconductor laminate portions 20 in series or in parallel, Is preferably an insulating or semi-insulating material. As the substrate 10 made of an insulating or semi-insulating material, a silicon (Si) substrate or a gallium arsenide (GaAs) substrate can be applied. Although not particularly limited, the substrate 10 is preferably a material having an electrical resistivity of 1 × 10 ⁵ [Ω · cm] or less.

[Compound semiconductor laminated portion]
In the quantum infrared device according to one embodiment of the present invention, the compound semiconductor lamination portion 20 includes the first compound semiconductor layer 21 of the first conductivity type including In and Sb, and In and Sb as described above. And a second compound semiconductor layer 23 of a second conductivity type.
The second compound semiconductor layer 23 does not necessarily have to be a compound semiconductor layer containing In and Sb, and may be a compound semiconductor layer that can be etched by an etchant used when forming a mesa shape, and a quantum type A semiconductor layer according to the purpose of the infrared device can be applied.
In the quantum infrared device according to one embodiment of the present invention, the ratio of the area of the etch pits present on the surface of the first compound semiconductor layer 21 to the area of the surface of the first compound semiconductor layer 21 is 0.09. It is below.

  Here, even in the quantum infrared device obtained by the conventional manufacturing method of the quantum infrared device, a certain amount of etch pits are present, but the influence of the etch pit on the characteristics of the infrared sensor is particularly remarkable. It was not done. However, it is important to further reduce this etch pit in order to reduce variations in the wiring resistance of the wiring layer included in the quantum infrared sensor and to improve the reliability of the lifetime of the quantum infrared sensor. The present inventors have found that, in particular, the ratio of the area of the etch pit present on the surface of the first compound semiconductor layer 21 to the area of the surface of the first compound semiconductor layer 21 is 0.09 or less. It has been found that the dispersion of the wiring resistance of the wiring layer in the infrared device is reduced and a highly reliable quantum infrared device can be realized.

The first conductivity type and the second conductivity type mean that semiconductor characteristics of different polarities are exhibited. For example, when the first conductivity type is n-type, the second conductivity type is p-type, and the first conductivity type is the first conductivity type. When the conductivity type is p-type, the second conductivity type is n-type. In order to obtain n-type conductivity, a method of doping antimony (Sn) as a doping material in the formation region of the first compound semiconductor layer 21 or the second compound semiconductor layer 23 having n-type conductivity is known. It can be mentioned. Further, in order to obtain a p-type conductivity type, zinc (Zn) is doped as a doping material in the formation region of the first compound semiconductor layer 21 or the second compound semiconductor layer 23 which is a p-type conductivity type. The method is mentioned.
The amount of doping is not particularly limited, but from the viewpoint of obtaining a quantum infrared device with good sensor characteristics, the amount of doping is 1 × 10 ¹⁶ [cm ⁻² ] or more 1 × 10 ²⁰ [cm] in one aspect of the present invention ^[2 ] or less, and in one embodiment, in the range of 1 × 10 ¹⁷ cm ^{−2 to} 5 × 10 ¹⁹ cm ⁻² , and in one embodiment, 1 × 10 ¹⁸ [2 − 2 It is the range of cm ^<-2 >] or more and 1 * 10 ^{< 19} > [cm ^<-2 >] or less.

In the quantum infrared device according to one embodiment of the present invention, the compound semiconductor lamination portion 20 includes a mesa structure 20a as shown in FIG. 1 (b), and the first compound semiconductor layer 21 is a mesa structure 20a. At the bottom, the second compound semiconductor layer 23 becomes the top of the mesa structure 20a.
The quantum infrared device according to an embodiment of the present invention is preferably in the form of a wafer from the viewpoint of mass productivity in the step of wet-etching the compound semiconductor lamination portion 20 in the manufacturing process thereof. By forming the plurality of compound semiconductor laminations 20 having the mesa structure 20 a as the wafer-like compound semiconductor laminations, many quantum infrared devices can be obtained at one time.

  In the quantum infrared device according to one embodiment of the present invention, the compound semiconductor lamination portion 20 may further include another layer depending on the purpose for which the quantum infrared device is used and the characteristics desired for the quantum infrared device. Good. For example, from the viewpoint of increasing sensitivity, as shown in FIG. 1A, a non-doped compound semiconductor layer or a first compound is interposed between the first compound semiconductor layer 21 and the second compound semiconductor layer 23. A third compound semiconductor layer 22 formed of a compound semiconductor layer whose doping amount is lower than that of the semiconductor layer 21 or the second compound semiconductor layer 23 may be provided. In this case, the third compound semiconductor layer 22 and the first compound semiconductor layer 21 and the second compound semiconductor layer 23 formed in the lower layer and the upper layer form a pin junction.

In addition, a compound semiconductor layer having a band gap larger than that of the first compound semiconductor layer 21 or the second compound semiconductor layer 23 may be further provided. In one aspect of the present invention, a compound semiconductor layer having a larger band gap is formed between the first compound semiconductor layer 21 and the second compound semiconductor layer 23. The compound semiconductor layer having a larger band gap can function as a barrier layer against electrons and holes.
Even if a compound semiconductor layer having a doping amount larger than that of the first compound semiconductor layer 21 or the second compound semiconductor layer 23 is provided between the first compound semiconductor layer 21 and the second compound semiconductor layer 23. Good. The compound semiconductor layer having a large amount of doping can function as a contact layer.

[Etchant]
In the method of manufacturing a quantum infrared device according to an embodiment of the present invention, the etchant used in the step of wet-etching the compound semiconductor lamination portion 20 includes hydrochloric acid and hydrogen peroxide. The mass concentration of hydrochloric acid is adjusted to 3.5 wt% or more and 5.5 wt% or less. Although the method of adjusting the mass concentration of hydrochloric acid is not particularly limited, for example, it can be realized by using a method of adjusting the amount of hydrochloric acid to be used or a method of adding water.
The mass concentration of hydrogen peroxide is not particularly limited, but from the viewpoint of mass productivity, in one aspect of the present invention, it is 0.5 wt% or more and 3.0 wt% or less. From the viewpoint of etch pit reduction, in one aspect of the present invention, the mass concentration of hydrogen peroxide is 2.0 wt% or more and 3.0 wt% or less, and in one aspect, 2.5 wt% or more and 3.0 wt% or less It is.
Temperature of etchant containing hydrochloric acid and hydrogen peroxide adjusted in mass concentration to 3.5 wt% or more and 5.5 wt% or less, which is used in the step of wet-etching the compound semiconductor lamination portion 20 in one embodiment of the present invention The temperature of the etchant is not particularly limited because the temperature of the etchant is not particularly limited because the temperature of the etchant is small, but the temperature of the etchant is 20 ° C. or less in one aspect of the present invention from the viewpoint of facilitating control of the reaction time. In one embodiment, the temperature is 10 ° C. or less.

[Mesa formation process]
In the method of manufacturing a quantum infrared device according to one embodiment of the present invention, in the mesa forming step of forming the mesa structure 20 a, the compound semiconductor lamination portion 20 is wet-etched with a predetermined etchant to form the first compound semiconductor layer 21. This is a step of forming a mesa-shaped compound semiconductor lamination portion 20 in which a part is exposed. The method for forming the mesa-shaped compound semiconductor laminated portion 20 in which a part of the first compound semiconductor layer 21 is exposed is not particularly limited, but in one aspect of the present invention, as shown in FIG. After forming the protective film 30 resistant to the etchant on the compound semiconductor layer 23, the wet etching process is performed.
As the protective film 30, a patterned resin film, a photoresist that can be patterned by photolithography, or the like can be applied.
The etching process is not particularly limited as long as the etching process can be performed until a part of the first compound semiconductor layer 21 is exposed, and the etching process is performed according to the etchant and the type of the compound semiconductor layer included in the compound semiconductor lamination portion 20. Time, temperature, pressure, etc. may be controlled.

[Wiring layer]
In the quantum infrared device according to one embodiment of the present invention, the wiring layer is not particularly limited as long as it exhibits conductivity capable of extracting a signal from the compound semiconductor lamination unit 20. For example, a single layer or a stack of metals such as gold, silver, copper, platinum, nickel, platinum, titanium can be used.
For example, in the case of connecting a plurality of compound semiconductor laminations 20 having a mesa structure 20 a in series, a wiring layer may be formed from the first compound semiconductor layer 21 to the second compound semiconductor layer 23. At this time, in one aspect of the present invention, the compound semiconductor lamination is performed via the insulating layer except the contact portion with the first compound semiconductor layer 21 of the wiring layer and the contact portion with the second compound semiconductor layer 23 of the wiring layer. A wiring layer is formed on the portion 20. As the insulating layer, silicon oxide, silicon nitride, or the like can be used. The method of forming the wiring layer is not particularly limited, but can be formed by a known method such as an etching method or a lift-off method.

[Dividing process]
There is no particular limitation on the method of cutting a wafer on which a plurality of compound semiconductor laminations are formed and dividing it into individual quantum type infrared devices, but a known cutting method such as blade dicing method or laser dicing method can be adopted.
[Package process]
Although the method in particular of packaging a quantum type infrared device by sealing resin is not restrict | limited, Well-known packaging methods, such as a method of using thermosetting resin compositions, such as an epoxy resin, are employable.

<Description of quantum infrared device>
Next, a method of manufacturing a quantum infrared device and a quantum infrared device according to an embodiment of the present invention will be described using the drawings.
FIG. 1 is a schematic sectional view for explaining a method of manufacturing a quantum infrared device according to a first embodiment of the present invention.
First, as shown in FIG. 1A, the substrate 10, and the first compound semiconductor layer 21 of the first conductivity type including In and Sb stacked sequentially on the substrate 10 from the substrate 10 side, and non-doped A semiconductor wafer having a compound semiconductor lamination portion 20 comprising the third compound semiconductor layer 22 and the second compound semiconductor layer 23 of the second conductivity type is prepared, and the semiconductor wafer is formed on a part of the second compound semiconductor layer 23. A protective film 30 is formed.

Next, wet etching is performed using an etchant containing hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less and hydrogen peroxide, using the protective film 30 as a mask, as shown in FIG. Then, a mesa structure 20a formed of a compound semiconductor lamination portion is formed in which a part of the first compound semiconductor layer 21 is exposed.
Next, as shown in FIG. 1C, the insulating groove 40a is formed between the mesa structures 20a, and the insulating layer 40 is formed on the entire surface of the compound semiconductor stack 20 including the mesa structure 20a and the insulating groove 40a. Then, an opening 40 b to be a contact portion is formed in each of a part on the first compound semiconductor layer 21 and a part on the second compound semiconductor 23.
Further, as shown in FIG. 1D, the wiring layer 50 is formed so as to cover the opening 40b. Thereby, a quantum infrared device can be obtained. Further, a quantum infrared device can be obtained in which a plurality of patterns shown in FIG. 1D are connected in series.

FIG. 2 illustrates the ratio Ap of the area of the etch pit present in the surface of the first compound semiconductor layer 21 to the area of the surface of the first compound semiconductor layer 21 in the quantum infrared device according to one embodiment of the present invention It is a plane schematic diagram for doing.
When the quantum infrared device is observed, a plane as shown in FIG. 2 (a) is observed. In FIG. 2A, 21a is a portion of the mesa structure 20a, and 21b is an etch pit. At this time, the area of the surface of the first compound semiconductor layer 21 is the area indicated by S1 in FIG. 2B, and the area of the etch pits 21b existing in the surface of the first compound semiconductor layer 21 is FIG. And the sum of the areas of the etch pits shown by S2. Therefore, the ratio Ap can be determined by determining S2 / S1.
As a method of obtaining the ratio, a laser microscope is used from the viewpoint that data analysis in the depth direction can be performed and image processing can be performed by recognizing the etch pit 21 b portion and the flat portion.

<Effect of the embodiment>
Thus, in the present embodiment, the first compound semiconductor layer of the first conductivity type including In and Sb and the second compound semiconductor layer of the second conductivity type are formed on the semiconductor substrate from the semiconductor substrate side. The compound semiconductor stacked portion stacked in this order is wet-etched using an etchant containing 3.5 wt% or more and 5.5 wt% or less hydrochloric acid and hydrogen peroxide to form a mesa shape. Therefore, the etch pits 21b present on the surface of the first compound semiconductor layer 21 can be reduced, and the etch present on the surface of the first compound semiconductor layer 21 with respect to the area of the surface of the first compound semiconductor layer 21. The ratio Ap, which is the ratio of the area of the pits 21b, can be reduced, and Ap can be made 0.090 or less.

Then, the fact that the ratio Ap can be reduced is equivalent to the reduction of the etch pits 21b, so that it is derived from defects during crystal growth when forming the first compound semiconductor layer 21. By the generated etch pits, it is possible to suppress the occurrence of variations in wiring resistance or the like in the wiring layer formed on the etch pits, and as a result, the reliability of the quantum infrared device can be improved.
As mentioned above, although embodiment of this invention was described, the technical scope of this invention is not limited to the technical scope as described in embodiment mentioned above. It is also apparent from the scope of the claims that it is possible to add various changes or improvements to the embodiment described above, and a form in which such changes or improvements are added can be included in the technical scope of the present invention. is there.

Hereinafter, based on an example, the manufacturing method of the quantum type infrared device of this embodiment and the effect by a quantum type infrared device are explained.
Example 1
N-type compound semiconductor layer (first compound semiconductor layer) composed of an InSb layer in which Sn is doped 1 × 10 ¹⁹ [cm ⁻³ ] on a semi-insulating GaAs substrate (substrate 10) by a molecular beam epitaxial (MBE) device 21) An active layer (third compound semiconductor layer 22) comprising an InSb layer doped with 2 × 10 ¹⁶ [cm ⁻³ ] of Zn, and an InSb layer doped with 1 × 10 ¹⁸ cm ^{−3 of} Zn A p-type compound semiconductor layer (second compound semiconductor layer 23) was formed in this order from the substrate 10 side to form a compound semiconductor laminated portion 20.

Next, a resist pattern is formed on the compound semiconductor lamination portion 20 by photolithography, and etching is performed with an etchant (10 ° C.) having a mass concentration of hydrochloric acid of 5.40 wt% and a mass concentration of hydrogen peroxide of 1.41 wt%. Thus, a mesa-shaped compound semiconductor lamination portion 20 in which a part of the n-type compound semiconductor layer (the first compound semiconductor layer 21) is exposed is formed.
In order to evaluate the surface shape of the n-type compound semiconductor layer (first compound semiconductor layer 21) as a compound semiconductor layer of the first conductivity type by etch pits, the area (S1) of the compound semiconductor layer 21 of the first conductivity type The ratio (S2 / S1) of the sum (S2) of the area of the etch pit 21b of the compound semiconductor layer 21 of the first conductivity type to the above is defined as Ap.

The observation of the surface shape of the n-type compound semiconductor layer (first compound semiconductor layer 21) as a compound semiconductor layer of the first conductivity type is performed using a laser microscope “VK-9500” manufactured by Keyence Corporation in the height direction 0 This was done by measuring in .02um steps. An image obtained by a laser microscope is shown in FIG.
The obtained image data was analyzed using data analysis software "VK Analyzer" manufactured by Keyence Corporation, and the result was Ap = 0.090.

  Next, as shown in FIG. 1D, an insulating layer 40 made of silicon oxide is formed, and an opening 40b is formed, and then a lamination of gold (Au) formed on nickel (Ni) and Ni is formed. The wiring layer 50 was formed, and a quantum infrared device was manufactured in which compound semiconductor multilayer portions having 400 mesa structures 20a were connected in series. Observation of the cross section of the quantum infrared sensor as a quantum infrared device produced makes it possible to obtain a wiring layer having a desired film thickness, and to obtain a wiring layer having a desired film thickness in any of the sensors. I was able to. That is, although the etch pit of ratio Ap = about 0.090 was confirmed, the wiring layer which has a desired film thickness was able to be obtained.

Comparative Example 1
A compound semiconductor laminate having a mesa structure 20a in the same manner as in Example 1 except that etching is performed by an etchant (10 ° C.) having a mass concentration of hydrochloric acid of 7.50 wt% and a mass concentration of hydrogen peroxide of 1.31 wt%. The part 20 was formed. The image acquired by the laser microscope of the surface shape of the formed compound semiconductor lamination part 20 is shown in FIG.
Measurement and evaluation of the surface shape of the formed compound semiconductor laminate portion 20 were performed in the same manner as in Example 1, and the surface shape of the compound semiconductor laminate portion 20 was observed, to be Ap = 0.226.
In addition, when a quantum infrared device was prepared according to the same procedure as in Example 1 and a cross section of the sensor was observed, as shown in FIG. 5, the film thickness was thinner in the wiring layer formed on the etch pits. It was confirmed that the place M exists.

Example 2
A compound semiconductor lamination 20 of a mesa shape is formed in the same manner as in Example 1 except that etching is performed by an etchant (10 ° C.) having a mass concentration of hydrochloric acid of 3.86 wt% and a mass concentration of hydrogen peroxide of 1.51 wt%. Formed. The image acquired by the laser microscope of the surface shape of the formed compound semiconductor lamination part 20 is shown in FIG.
Measurement and evaluation of the surface shape of the formed compound semiconductor laminate portion 20 were performed in the same manner as in Example 1, and the surface shape of the compound semiconductor laminate portion 20 was observed, to be Ap = 0.032.

[Example 3]
A compound semiconductor lamination 20 of a mesa shape is formed in the same manner as in Example 1 except that etching is performed by an etchant (10 ° C.) having a mass concentration of hydrochloric acid of 4.04 wt% and a mass concentration of hydrogen peroxide of 0.53 wt%. Formed. The image obtained by the laser microscope of the surface shape of the formed compound semiconductor lamination part 20 is shown in FIG.
Measurement and evaluation of the surface shape of the formed compound semiconductor laminate portion 20 were performed in the same manner as in Example 1, and the surface shape of the compound semiconductor laminate portion 20 was observed, to be Ap = 0.002.

Example 4
A mesa-shaped compound semiconductor multilayer portion 20 is formed in the same manner as in Example 1 except that etching is performed using an etchant (10 ° C.) having a mass concentration of hydrochloric acid of 3.63 wt% and a mass concentration of hydrogen peroxide of 2.84 wt%. It formed. The image acquired by the laser microscope of the surface shape of the formed compound semiconductor lamination part 20 is shown in FIG.
Measurement and evaluation of the surface shape of the formed compound semiconductor laminate portion 20 were performed in the same manner as in Example 1, and the surface shape of the compound semiconductor laminate portion 20 was observed. Ap = 0.001.
The above results are shown in Table 1.

  From Table 1, the compound semiconductor laminate portion 20 is wet-etched using an etchant containing hydrochloric acid having a mass concentration of 3.63 wt% or more and 5.4 wt% or less and hydrogen peroxide to obtain a ratio Ap of 0. It could be confirmed that it can be made 090 or less. Also, from the evaluations thus far, in the etchant containing hydrochloric acid and hydrogen peroxide, when the concentration of hydrochloric acid is less than 3.5 wt% (for example, 2.7 wt%), the shape stability of the compound semiconductor laminate is poor, When it is larger than 5.5 wt%, it is known that the ratio of the area of the etch pit is increased as in Comparative Example 1. From such findings, it can be seen that the ratio Ap can be made 0.090 or less if the etchant contains hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less and hydrogen peroxide. It was issued.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a quantum infrared device such as a quantum infrared sensor, an infrared light receiving element, an infrared light emitting element, and the like, which has high reliability and small variations in wiring resistance and the like.

DESCRIPTION OF SYMBOLS 10 substrate 20 compound semiconductor lamination part 21 1st compound semiconductor layer 22 3rd compound semiconductor layer 23 2nd compound semiconductor layer 30 protective film 40 insulating layer 40a insulating groove 40b opening 50 wiring layer

Claims (3)

A method of manufacturing a quantum infrared device having a mesa structure, comprising:
A first compound semiconductor layer of a first conductivity type containing In and Sb and a second compound semiconductor layer of a second conductivity type different in conductivity type from the first conductivity type are formed on the substrate from the substrate side The compound semiconductor lamination portion formed in this order is wet-etched using an etchant containing hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less and hydrogen peroxide, and the first compound semiconductor A method of manufacturing a quantum infrared device, comprising the step of forming a mesa for forming the mesa structure in which a part of a layer is exposed.   The method for manufacturing a quantum infrared device according to claim 1, further comprising the step of forming a wiring layer in the compound semiconductor multilayer portion in which the mesa structure is formed after the mesa forming step. A first compound semiconductor layer of a first conductivity type containing In and Sb and a second compound semiconductor layer of a second conductivity type different in conductivity type from the first conductivity type are formed on the substrate from the substrate side It is an etchant used in the step of forming a mesa structure in which a portion of the first compound semiconductor layer is exposed by wet etching processing of a compound semiconductor lamination portion formed by laminating in this order,
The etchant is a quantum infrared device manufacturing etchant containing hydrochloric acid having a mass concentration of 3.5 wt% or more and 5.5 wt% or less and hydrogen peroxide.