JP7095781B2 - Semi-insulating gallium arsenide crystal substrate - Google Patents

Description

The present invention relates to a semi-insulating gallium arsenide crystal substrate.

Semi-insulating compound semiconductor substrates such as gallium arsenide crystal substrates have flatness in the micro region of the main surface (hereinafter referred to as micro-flatness) in order to contribute to the miniaturization and complexity of structures that directly improve the performance of semiconductor devices. It is required to improve (also called sex). The micro-flatness of the main surface of the substrate is affected not only by the polishing conditions but also by the physical properties of the substrate. Specifically, in order to improve the micro-flatness of the main surface of the substrate, it is important that the distribution of the specific resistance in the main surface of the substrate in the micro region (hereinafter, also referred to as micro distribution) is uniform.

From the viewpoint of obtaining a semi-insulating gallium arsenide substrate having a uniform distribution (micro distribution) of the resistivity in the micro region of the main surface and high micro flatness of the main surface, T. Kawase et al., "Properties of 6- inch Semi-insulating GaAs Substrates Manufactured by Vertical Boat Method ", GaAs ManTech 1999, April, 1999, pp19-22 (Non-Patent Document 1) describes resistivity and in a micro region 80 mm long in the outer peripheral direction at a pitch of 100 μm from the center of the substrate. A semi-insulating gallium arsenide substrate having a variation coefficient (meaning the standard deviation in the micro region divided by an average value) is 0.073 is disclosed.

T. Kawase et al., "Properties of 6-inch Semi-insulating GaAs Substrates Manufactured by Vertical Boat Method", GaAs ManTech 1999, April, 1999, pp19-22

The semi-insulating gallium arsenide crystal substrate according to one aspect of the present disclosure has a main surface having a plane orientation of (100) and a diameter of 2 Rmm, and has 0 mm, 0.5 Rmm, and 0 mm, 0.5 Rmm, and the like in the [010] direction from the center of the main surface. The average value of resistivity is 5 × 10 ⁷ Ω · cm or more for each of the three measurement regions centered on the point with a distance of (R-17) mm, and the standard deviation of resistivity is the mean value of resistivity. The coefficient of variation obtained by dividing by is 0.50 or less.

FIG. 1 is a schematic plan view showing an example of a semi-insulating gallium arsenide crystal substrate according to this embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a method for measuring the specific resistance of the semi-insulating gallium arsenide crystal substrate according to this embodiment. FIG. 3 is a schematic view showing an example of an apparatus used for manufacturing a semi-insulating gallium arsenide crystal substrate according to this embodiment. FIG. 4 is a schematic view showing another example of the apparatus used for manufacturing the semi-insulating gallium arsenide crystal substrate according to this embodiment. FIG. 5 is a schematic view showing still another example of the apparatus used for manufacturing the semi-insulating gallium arsenide crystal substrate according to this embodiment.

[Problems to be solved by this disclosure]
However, the semi-insulating gallium disclosed in T. Kawase et al., "Properties of 6-inch Semi-insulating GaAs Substrates Manufactured by Vertical Boat Method", GaAs ManTech 1999, April, 1999, pp19-22 (Non-Patent Document 1). Although the maximum value of the specific resistance of the gallium arsenide substrate is not described in Non-Patent Document 1, it is less than 5 × 10 ⁷ Ω · cm when read from the graph described in Non-Patent Document 1. In a semi-insulating gallium arsenide crystal substrate having a specific resistance of 5 × 10 ⁷ Ω · cm or more, the variation in the micro distribution of the specific resistance becomes large between the central part and the outer peripheral part of the substrate, and the micro distribution of the specific resistance becomes large. There is a problem that it is difficult to make it uniform and the micro flatness of the main surface becomes low.

It is an object of the present disclosure to solve the above-mentioned problems and to provide a semi-insulating gallium arsenide crystal substrate having high micro-flatness of the main surface even if the specific resistance is high.

[Effect of this disclosure]
According to the present disclosure, it is possible to provide a semi-insulating gallium arsenide crystal substrate having high micro-flatness of the main surface even if the specific resistance is high.

[Explanation of Embodiment of the present invention]
First, embodiments of the present invention will be listed and described.

[1] The semi-insulating gallium arsenide crystal substrate according to the embodiment of the present invention has a surface orientation of (100) and is 0 mm, 0 in the [010] direction from the center of the main surface on a main surface having a diameter of 2 Rmm. The mean value of resistivity is 5 × 10 ⁷ Ω · cm or more for each of the three measurement regions centered on points with distances of .5 R mm and (R-17) mm, and the standard deviation of resistivity is compared. The coefficient of variation obtained by dividing by the average value of resistance is 0.50 or less. In the semi-insulating gallium arsenide crystal substrate of the present embodiment, the micro distribution of the specific resistance on the main surface having the plane orientation (100) is uniform, and the micro flatness of the main surface is high.

[2] In the semi-insulating gallium arsenide crystal substrate, the diameter of the main surface of the main surface can be set to 150 mm or more. In such a semi-insulating gallium arsenide crystal substrate, even if the surface orientation is (100) and the diameter of the main surface is a large diameter of 150 mm or more, the micro distribution of the specific resistance on the main surface is uniform, and the surface of the main surface has a uniform micro-distribution. High micro flatness.

[3] In the semi-insulating gallium arsenide crystal substrate, the coefficient of variation of specific resistance can be set to 0.10 or less. In such a semi-insulating gallium arsenide crystal substrate, the micro distribution of specific resistance on the main surface having a plane orientation of (100) is extremely uniform, and the micro flatness of the main surface is extremely high.

[Details of Embodiments of the present invention]
Hereinafter, embodiments of the present invention will be described in more detail, but the present invention is not limited thereto. In the following, although the description will be made with reference to the drawings, the same or corresponding elements shall be designated by the same reference numerals in the present specification and the drawings, and the same description thereof will not be repeated. Further, (hkl) in the present specification and drawings indicates a plane direction, and [hkl] indicates an orientation. Here, h, k and l are the same or different integers and are called the Miller index. The "-" that appears before the Miller index is originally represented above the number, and is read as "bar" after the Miller index. For example, [0-10] is read as "zero, one, bar, zero."

In the present specification, the notation in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less), and when there is no description of the unit in A and the unit is described only in B, A. The unit of and the unit of B are the same. Further, in the present specification, when a compound or the like is represented by a chemical formula, it shall include all conventionally known atomic ratios when the atomic ratio is not particularly limited, and should not necessarily be limited to those in the stoichiometric range.

≪Semi-insulating gallium arsenide crystal substrate≫
With reference to FIG. 1, the semi-insulating GaAs crystal substrate 11 (semi-insulating gallium arsenide crystal substrate) according to the present embodiment is the center of the main surface having a plane orientation of (100) and a diameter of 2 Rmm. In the direction from [010], the average value of resistivity is 5 × 10 ⁷ Ω · cm or more for each of the three measurement regions centered on 0 mm, 0.5 Rmm, and (R-17) mm, and the ratio. The variation coefficient obtained by dividing the standard deviation of resistance by the average value of specific resistance is 0.50 or less. In the semi-insulating GaAs crystal substrate 11 of the present embodiment, the micro distribution of the specific resistance on the main surface having the plane orientation (100) is uniform, and the micro flatness of the main surface is high.

The semi-insulating GaAs crystal substrate 11 of the present embodiment has an average specific resistance of 5 × 10 ⁷ Ω · cm or more, preferably 7.5 × 10 ⁷ Ω · cm or more, and more preferably 1. It is 0 × 10 ⁸ Ω · cm or more.

<Main side>
As shown in FIG. 1, the semi-insulating GaAs crystal substrate 11 of the present embodiment has a main surface orientation of (100). That is, the semi-insulating GaAs crystal substrate 11 is obtained by cutting out the semi-insulating GaAs crystal body with its (100) plane as the main plane.

The diameter of the main surface of the semi-insulating GaAs crystal substrate 11 is not particularly limited, but is preferably larger, preferably 150 mm or more. In such a semi-insulating GaAs crystal substrate, even if the diameter of the main surface having a plane orientation of (100) is a large diameter of 150 mm or more, the micro distribution of specific resistance on the main surface is uniform and the main surface is micro flat. High sex.

<Mean and coefficient of variation of specific resistance>
As shown in FIG. 1, the semi-insulating GaAs crystal substrate 11 of the present embodiment has three centers centered on 0 mm, 0.5 Rmm, and (R-17) mm in the [010] direction from the center of the main surface. For each of the measurement regions, the average value of the specific resistance is 5 × 10 ⁷ Ω · cm or more, and the coefficient of variation obtained by dividing the standard deviation of the specific resistance by the average value of the specific resistance is 0.50 or less. Since the semi-insulating GaAs crystal substrate 11 of the present embodiment has the above-mentioned coefficient of variation of specific resistance of 0.50 or less, the micro distribution of specific resistance on the main surface is uniform and the micro flatness of the main surface is high. ..

As shown in FIG. 1, the center of the main surface refers to the center of the circle, assuming that the main surface of the semi-insulating GaAs crystal substrate 11 is a circle. The [010] direction from the center of the main surface corresponds to the direction in which the center of the main surface is viewed from the notch portion 11n in the substrate in which the notch portion 11n is formed in the [0-10] direction from the center of the main surface.

In a semi-insulating GaAs crystal substrate having a main surface diameter of 2 Rmm, the three measurement regions for measuring the micro distribution of specific resistance are r ₀ in the [010] direction from the center of the main surface, as shown in FIG. = 0 mm (that is, the center point of the main surface) in the center measurement area F0, r ₁ = 0.5 Rmm (that is, between the center of the main surface and the outer periphery of the main surface) in the [010] direction from the center of the main surface. Centered at the middle measurement region F1 centered on the point) and r ₂ = (R-17) mm (that is, a point 17 mm inward from the outer circumference of the main surface) in the [010] direction from the center of the main surface. It is the outer peripheral portion measurement area F2.

The specific resistance is measured over a distance of -5 mm to +5 mm in the [010] direction from the center of each region in each of the central measurement region F0, the intermediate measurement region F1 and the outer peripheral measurement region F2. At 101 points with a pitch of 100 μm (0.1 mm). The average value of the specific resistance and the standard deviation of the specific resistance are calculated from the measured values of the specific resistance at the above 101 points. The coefficient of variation of the specific resistance is calculated by dividing the standard deviation of the obtained specific resistance by the average value of the obtained specific resistance.

The specific resistance is measured by the 3-terminal guard method as shown in FIG. That is, a circle having a diameter of 70 μm is formed on the main surface (hereinafter, also referred to as the front main surface) for measuring the specific resistance of the semi-insulating GaAs crystal substrate 11 in the [010] direction from the center of each of the above three measurement regions. A pattern in which 101 pieces are arranged at a pitch of 100 μm (0.1 mm) over a distance range of 5 mm to +5 mm is produced by photolithography. Then, on the front main surface of the semi-insulating GaAs crystal substrate 11 and the main surface on the opposite side thereof (hereinafter, also referred to as the back main surface), an Au layer having a thickness of 300 nm, a Ni layer having a thickness of 40 nm, and AuGe having a thickness of 80 nm. The layers are sequentially vapor-deposited, lifted off, and then heat-treated at 475 ° C. for 6 minutes to alloy them to form measurement electrodes E1 and E2. The measurement electrodes E1 and E2 are wired as shown in FIG. 2, and a voltage is applied from the back side main surface under the conditions of a voltage application range of 0V to 10V and a voltage application step of 1V, and the inside of the patterned measurement electrodes E1. Measure the current of. Such measurement is performed for each measurement electrode E1 patterned at a pitch of 100 μm over a length of 10 mm in the [010] direction. The measured value of resistivity is obtained by dividing the resistance value calculated from the slope of the current-voltage curve by the sample thickness d of the semi-insulating GaAs crystal substrate 11 and then multiplying by the area S of the patterned measurement electrode E1. Derived by.

The average value of the specific resistance is preferably 5 × 10 ⁷ Ω · cm or more from the viewpoint of reducing the leakage current at the time of manufacturing the device. In addition, the average value of resistivity is often 1 × 10 ⁹ Ω · cm or less due to the mechanism of semi-insulating property development.

In the semi-insulating GaAs crystal substrate 11 of the present embodiment, the coefficient of variation of the specific resistance is 0.10 for each of the above three measurement regions (central measurement region F0, intermediate measurement region F1 and outer peripheral measurement region F2). The following is preferable. Since the coefficient of variation of the specific resistance of such a semi-insulating GaAs crystal substrate is 0.10 or less, the micro distribution of the specific resistance on the main surface is extremely uniform, and the micro flatness of the main surface is extremely high.

<Dislocation density>
In the semi-insulating GaAs crystal substrate 11 of the present embodiment, from the viewpoint of making the micro distribution of the specific resistance on the main surface uniform, the above three measurement regions (central measurement region F0, intermediate measurement region F1 and outer peripheral measurement region) For each of F2), the dislocation density is preferably 9.5 × 10 ³ cm ⁻² or less, and more preferably 5.5 × 10 ³ cm ⁻² or less.

The dislocation density is measured by measuring the density of the etch pits formed when the semi-insulating GaAs crystal substrate 11 is etched in molten KOH (potassium hydroxide) at 450 ° C. for 20 minutes. By magnifying the center of each of the above three measurement areas (central measurement area F0, intermediate measurement area F1 and outer peripheral measurement area F2) with a microscope and measuring the number of etch pits in the 1 mm square field of view. Calculate the etch pit density.

≪Manufacturing method of semi-insulating gallium arsenide crystal substrate≫
In order to make the micro distribution of the specific resistance of the semi-insulating GaAs crystal substrate uniform, it is important to make the distribution of the dislocation density that affects the micro distribution of the specific resistance uniform. The semi-insulating GaAs crystal substrate is usually produced by cutting out a large-diameter semi-insulating GaAs crystal body crystal-grown in the [100] direction on the (100) plane and a plane parallel to it. In a large-diameter semi-insulating GaAs crystal grown in the [100] direction, the dislocation density in the cross section having the plane orientation (100) is high at the center and the outer periphery of the cross section, and is intermediate between the center and the outer periphery. It has a non-uniform distribution that it becomes low in. Therefore, it is necessary to make such a non-uniform distribution of dislocation density uniform (Measures I). Further, due to the crystallographic properties of the GaAs crystal, the dislocation density of the semi-insulating GaAs crystal is in the <100> direction ([010] direction and the crystallographically equivalent [00-1] direction in this direction, [0-]. It tends to be higher in the four directions of [10] direction and [001] direction). Therefore, it is necessary to reduce the dislocation density in the <100> direction (Measures II). Further, it is preferable to make the non-uniform distribution of the dislocation density uniform (Measures I) and lower the dislocation density in the <100> direction (Measures II) (Measures III).

<Measures I>
FIG. 3 shows a first example of an apparatus used for producing a semi-insulating GaAs crystal. FIG. 3A is a schematic top view of the device, and FIG. 3B is a schematic side sectional view of the device. The non-uniform distribution of the transition density described above reduces the lower heat dissipation from the solid-liquid interface between the semi-insulating GaAs crystal 10 and the GaAs raw material melt 4 during crystal growth of the semi-insulating GaAs crystal 10. It is thought that it is derived from doing. That is, the downward heat radiation from the solid-liquid interface is caused by the rise of the solid-liquid interface from the GaAs raw material melt 4 to the stage (a platform located below the pit to support the pit, not shown). The direct heat dissipation from the GaAs raw material melt 4 changes to the indirect heat dissipation from the semi-insulating GaAs crystal 10 to the stage, which is reduced. However, in the conventional method for producing a semi-insulating GaAs crystal, the heat insulating material 3 as shown in FIG. 3 is not arranged, so that the heater arranged on the side surface side of the crystal growth crucible 2 (not shown). ) Does not change even if the solid-liquid interface rises. For this reason, in the conventional method for producing a semi-insulating GaAs crystal, the downward heat dissipation decreases as the solid-liquid interface rises, so if the heat input from the side surface remains constant, the liquid at the solid-liquid interface The heat balance between the heat input from the phase side and the heat dissipation from the solid phase side changes, and thermal stress is generated due to changes in the relative position and shape of the solid-liquid interface, making the distribution of the dislocation density non-uniform. The first example is, as a measure I, in order to make the dislocation density distribution uniform by suppressing the above-mentioned change in the heat balance, between the crystal growth crucible 2 and the heater, specifically for crystal growth. A tapered heat insulating material 3 is arranged around the outer periphery of the side surface of the crucible 2.

The heat insulating material 3 in the first example has a tubular shape and has a crystal growth surface side (hereinafter, also referred to as) of a semi-insulating GaAs crystal as compared with a portion corresponding to the GaAs seed crystal SC side (hereinafter, also referred to as seed side). , Also referred to as the tail side), a taper is provided so as to increase the heat insulating property of the portion corresponding to). The material of the heat insulating material 3 is not particularly limited, and is, for example, carbon, boron nitride (BN), silicon nitride (Si ₃ N ₄ ), mullite (3Al ₂ O ₃・ 2SiO ₂ to 2Al ₂ O ₃・ SiO ₂ ) and Alumina (Al ₂ O ₃ ) and the like can be mentioned. As a result, during crystal growth of the semi-insulating GaAs crystal body 10, as the solid-liquid interface rises, the heat input from the side surface side of the crystal growth pit 2 decreases, so that the change in heat balance is suppressed. , The generation of thermal stress is suppressed and the distribution of dislocation density becomes uniform.

<Measures II>
FIG. 4 shows a second example of an apparatus used for manufacturing a semi-insulating GaAs crystal. FIG. 4A is a schematic top view of the device, and FIG. 4B is a schematic side sectional view of the device. Since dislocations in the semi-insulating GaAs crystal 10 are considered to be generated by thermal stress, the semi-insulating GaAs crystal is in order to reduce the dislocation density in the <100> direction of the semi-insulating GaAs crystal 10. It is necessary to reduce the temperature difference in the <100> direction of 10. Therefore, in the second example, as a measure II, between the crystal growth crucible 2 and the heater, specifically, around the outer periphery of the side surface of the crystal growth crucible 2, the semi-insulating GaAs crystal 10 <100. > Direction (4 crystallographically equivalent directions including [010] direction, specifically, [010] direction, [00-1] direction, [0-10] direction and [001] direction. The same applies hereinafter), the heat insulating material 3 having a portion having a high heat insulating property is arranged.

The heat insulating material 3 in the second example has a first material 3a and a second material 3b made of a material having higher heat insulating properties (that is, lower thermal conductivity) than the first material 3a by 45 ° in the circumferential direction. It has a cylindrical shape formed by arranging them alternately. The heat insulating material 3 is a crystallographically equivalent four directions including the <110> direction ([01-1] direction) of the semi-insulating GaAs crystal body 10 in which the crystal grows in the [100] direction in the crystal growth pit 2. The first material 3a is located in the [01-1] direction, the [0-1-1] direction, the [0-11] direction, and the [011] direction. The same shall apply hereinafter), and <100. The second material 3b is arranged so as to be located in the> direction. The first material 3a and the second material 3b of the heat insulating material 3 are not particularly limited as long as the second material 3b is made of a material having higher heat insulating properties (lower thermal conductivity) than the first material 3a. For example, carbon is mentioned as the material of the first material 3a, and boron nitride (BN), silicon nitride (Si ₃ N ₄ ), and mulite (3Al ₂ O _{3.2SiO 2} to 2Al ₂ O ₃ ) are used as the material of the second material 3b. -SiO ₂ ) and alumina (Al ₂ O ₃ ) and the like. As a result, when the semi-insulating GaAs crystal 10 grows, the temperature distribution of the semi-insulating GaAs crystal 10 in the <110> direction is made uniform, so that the generation of thermal stress is suppressed and the dislocation density is reduced. The distribution becomes uniform.

<Measures III>
FIG. 5 shows a third example of an apparatus used for producing a semi-insulating GaAs crystal. 5 (A) is a schematic top view of the device, and FIG. 5 (B) is a schematic side sectional view of the device. A third example is a semi-insulating GaAs between the crystal growth crucible 2 and the heater, specifically around the outer periphery of the side surface of the crystal growth crucible 2, as a measure III in which the above measures I and II are combined. A tapered heat insulating material 3 having a portion having a high heat insulating property is arranged in the <100> direction of the crystal body 10.

Due to the above measure I, the heat insulating material 3 in the third example has a tubular shape and is a semi-insulating GaAs crystal as compared with the portion corresponding to the GaAs seed crystal SC side (hereinafter, also referred to as the seed side). A taper is provided so that the heat insulating property of the portion corresponding to the crystal growth surface side (hereinafter, also referred to as the tail side) is high, and due to the above-mentioned measure II, the first material 3a and the first material 3a The second material 3b, which is made of a material having high heat insulating properties (that is, having low thermal conductivity), is formed by alternately arranging the second material 3b in the circumferential direction by 45 ° each, and is formed in the [100] direction in the crystal growth pit 2. The first material 3a is located in the <110> direction of the semi-insulating GaAs crystal body 10 in which the crystal grows, and the second material 3b is located in the <100> direction. The first material 3a and the second material 3b of the heat insulating material 3 are not particularly limited as long as the second material 3b is made of a material having higher heat insulating properties (lower thermal conductivity) than the first material 3a. For example, carbon is mentioned as the material of the first material 3a, and boron nitride (BN), silicon nitride (Si ₃ N ₄ ), and mulite (3Al ₂ O _{3.2SiO 2} to 2Al ₂ O ₃ ) are used as the material of the second material 3b. -SiO ₂ ) and alumina (Al ₂ O ₃ ) and the like.

In the third example, according to the configuration corresponding to the above measure I, the heat absorption from the side surface side of the crystal growth chamber 2 decreases as the solid-liquid interface rises during crystal growth of the semi-insulating GaAs crystal body 10. As a result, changes in the heat balance are suppressed, so that the generation of thermal stress is suppressed, and with the configuration corresponding to the above-mentioned measure II, the semi-insulating GaAs crystal is formed during crystal growth of the semi-insulating GaAs crystal 10. Since the temperature distribution in the <110> direction of 10 is made uniform, the generation of thermal stress is suppressed. Therefore, the distribution of dislocation density becomes more uniform.

The semi-insulating GaAs crystal substrate 11 described above is manufactured by cutting out the semi-insulating GaAs crystal body 10 obtained by the manufacturing methods of the first to third examples with the (100) plane as the main surface. Can be done.

<< Example I >>
<Manufacturing of semi-insulating GaAs crystal substrate>
In Example I, a semi-insulating GaAs crystal 10 doped with a large diameter carbon of 150 mm in diameter was grown by a vertical boat method using the apparatus shown in FIG. The heat insulating material 3 has a tubular shape, and has a semi-insulating GaAs crystal on the crystal growth surface side (hereinafter, also referred to as the tail side) as compared with the portion corresponding to the GaAs seed crystal SC side (hereinafter, also referred to as the seed side). A taper is provided so that the heat insulating property of the portion corresponding to) is increased, specifically, the thickness of the heat insulating material 3 on the tail side is larger than that on the seed side. The material of the heat insulating material 3 was silicon nitride (Si ₃ N ₄ ). The growth condition of the semi-insulating GaAs crystal 10 was a conventional method. As a result, the semi-insulating GaAs crystal body of Example I was produced.

By cutting out the (100) plane as the main surface from the semi-insulating GaAs crystal body manufactured as described above, a plurality of semi-insulating GaAs crystal substrates having a thickness of 600 μm were manufactured. Among the plurality of manufactured semi-insulating GaAs crystal substrates, the semi-insulating GaAs obtained from the portion of the semi-insulating GaAs crystal body 10 corresponding to the most GaAs seed crystal SC side (hereinafter, also referred to as the most seed side). The crystal substrate was used as the semi-insulating GaAs crystal substrate of Example I-1, and the semi-insulating obtained from the portion corresponding to the most crystal growth surface side (hereinafter, also referred to as the tail side) of the semi-insulating GaAs crystal body 10. The sex GaAs crystal substrate was used as the semi-insulating GaAs crystal substrate of Example I-2.

<Evaluation of mean value and coefficient of variation of specific resistance and dislocation density>
The above three measurement regions (center measurement region F0) on the main surface of the semi-insulating GaAs crystal substrate of Example I-1 (most seed side) and Example I-2 (tailmost side) manufactured as described above. , The average value and the coefficient of variation and the coefficient of variation, which are indicators of the micro distribution of specific resistance in each of the intermediate measurement region F1 and the outer peripheral measurement region F2), are measured by the above method, and the ratio in each of the above three measurement regions is measured. The mean resistance, coefficient of variation and dislocation density were evaluated. The results are summarized in Table 1.

<Evaluation of surface flatness>
The above three measurement regions (central measurement regions) on the main surface of the semi-insulating GaAs crystal substrate of Example I-1 (most seed side) and Example I-2 (tailmost side) manufactured as described above. The surface flatness in each of F0, the intermediate portion measurement region F1 and the outer peripheral portion measurement region F2) was measured and evaluated. The measurement method was as follows. That is, the main surfaces of the semi-insulating GaAs crystal substrates of Examples I-1 and I-2 were mirrored. A flatness measuring instrument in each 20 mm square region (Ultrasort 6220, Corning Tropel Co., Ltd.) in a 20 mm square range centered on the center of each of the center measurement region F0, the middle measurement region F1 and the outer peripheral measurement region F2. LTV (Local Thickness Variation) measurement was performed using. The results are summarized in Table 1.

<< Example II >>
<Manufacturing of semi-insulating GaAs crystal substrate>
In Example II, a semi-insulating GaAs crystal 10 doped with a large diameter carbon of 150 mm in diameter was grown by the vertical Bridgeman method using the apparatus shown in FIG. In the heat insulating material 3, the first material 3a and the second material 3b made of a material having higher heat insulating property (that is, lower thermal conductivity) than the first material 3a are alternately arranged by 45 ° in the circumferential direction. It has a cylindrical shape formed by, and the material of the first material 3a is carbon, and the material of the second material 3b is silicon nitride (Si ₃ N ₄ ). Further, in the heat insulating material 3, the central axis of the first material 3a is located in the <110> direction of the semi-insulating GaAs crystal body 10 in which the crystal grows in the [100] direction in the crystal growth chamber 2, and the central axis of the first material 3a is located in the <100> direction. It was arranged so that the central axis of the second material 3b was located. As a result, the semi-insulating GaAs crystal body of Example II was produced.

By cutting out the semi-insulating GaAs crystal body of Example II produced as described above in the same manner as in Example I, a plurality of semi-insulating GaAs crystal substrates having a thickness of 600 μm were produced. Among the plurality of manufactured semi-insulating GaAs crystal substrates, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the most seed side of the semi-insulating GaAs crystal body 10 is the semi-insulating GaAs of Example II-1. As the crystal substrate, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the tail end side of the semi-insulating GaAs crystal body 10 was used as the semi-insulating GaAs crystal substrate of Example II-2.

<Evaluation of mean and coefficient of variation of specific resistance, dislocation density, and surface flatness>
The above three measurement regions (center measurement region F0) on the main surface of the semi-insulating GaAs crystal substrate of Example II-1 (most seed side) and Example II-2 (tailmost side) manufactured as described above. , The mean value and coefficient of variation of the specific resistance in each of the intermediate portion measurement region F1 and the outer peripheral portion measurement region F2), the shift density, and the surface flatness were evaluated in the same manner as in Example I. The results are summarized in Table 1.

<< Example III >>
<Manufacturing of semi-insulating GaAs crystal substrate>
In Example III, a large-diameter carbon-doped semi-insulating GaAs crystal 10 having a diameter of 150 mm was grown by the vertical Bridgeman method using the apparatus shown in FIG. The heat insulating material 3 has a tubular shape, and has a semi-insulating GaAs crystal on the crystal growth surface side (hereinafter, also referred to as the tail side) as compared with the portion corresponding to the GaAs seed crystal SC side (hereinafter, also referred to as the seed side). A taper is provided so that the heat insulating property of the portion corresponding to) is increased, specifically, the thickness of the heat insulating material 3 on the tail side is larger than that on the seed side. Further, in the heat insulating material 3, the first material 3a and the second material 3b made of a material having higher heat insulating property (that is, lower thermal conductivity) than the first material 3a are alternately arranged by 45 ° in the circumferential direction. It is formed by arranging them side by side, and the material of the first material 3a is carbon, and the material of the second material 3b is silicon nitride (Si ₃ N ₄ ). Further, in the heat insulating material 3, the central axis of the first material 3a is located in the <110> direction of the semi-insulating GaAs crystal body 10 in which the crystal grows in the [100] direction in the crystal growth chamber 2, and the central axis of the first material 3a is located in the <100> direction. It was arranged so that the central axis of the second material 3b was located. As a result, the semi-insulating GaAs crystal of Example III was produced.

By cutting out the semi-insulating GaAs crystal body of Example III manufactured as described above in the same manner as in Example I, a plurality of semi-insulating GaAs crystal substrates having a thickness of 600 μm were manufactured. Among the plurality of manufactured semi-insulating GaAs crystal substrates, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the most seed side of the semi-insulating GaAs crystal body 10 is the semi-insulating GaAs of Example III-1. As the crystal substrate, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the tail end side of the semi-insulating GaAs crystal body 10 was used as the semi-insulating GaAs crystal substrate of Example III-2.

<Evaluation of mean and coefficient of variation of specific resistance, dislocation density, and surface flatness>
The above three measurement regions (center measurement region F0) on the main surface of the semi-insulating GaAs crystal substrate of Example III-1 (most seed side) and Example III-2 (tailmost side) manufactured as described above. , The mean value and coefficient of variation of the specific resistance in each of the intermediate portion measurement region F1 and the outer peripheral portion measurement region F2), the shift density, and the surface flatness were evaluated in the same manner as in Example I. The results are summarized in Table 1.

<< Comparative Example I >>
A semi-insulating GaAs crystal of Comparative Example I was produced in the same manner as in Example I except that no heat insulating material was used. By cutting out the semi-insulating GaAs crystal body of Comparative Example I produced in the same manner as in Example I, a plurality of semi-insulating GaAs crystal substrates having a thickness of 600 μm were produced. Among the plurality of manufactured semi-insulating GaAs crystal substrates, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the most seed side of the semi-insulating GaAs crystal body 10 is the semi-insulating GaAs of Comparative Example I-1. As the crystal substrate, the semi-insulating GaAs crystal substrate obtained from the portion corresponding to the tail end side of the semi-insulating GaAs crystal body 10 was used as the semi-insulating GaAs crystal substrate of Comparative Example I-2. The above three measurement regions (center measurement region F0, intermediate portion measurement) of the main surface of the semi-insulating GaAs crystal substrate of Comparative Example I-1 (most seed side) and Comparative Example I-2 (tailmost side) manufactured. The mean value and coefficient of variation of the specific resistance in each of the region F1 and the outer peripheral measurement region F2), the dislocation density, and the surface flatness were evaluated in the same manner as in Example I. The results are summarized in Table 1.

With reference to Table 1, in the semi-insulating GaAs crystal substrates of Comparative Example I-1 and Comparative Example I-2, the ratio was obtained in any of the central measurement region, the intermediate measurement region, and the outer peripheral measurement region of the main surface. The average value of the resistance was 5.0 × 10 ⁷ Ω · cm or more, but the coefficient of variation of the specific resistance exceeded 0.50 in the central measurement region and the outer peripheral measurement region of the main surface, and the dislocation density. Was 1.0 × 10 ⁴ cm ⁻² or more, and the surface flatness was as large as 1.0 μm or more.

The semi-insulating GaAs crystal substrate of Example I-1 and Example I-2 manufactured by performing the above-mentioned measure I with respect to the semi-insulating GaAs crystal substrate of Comparative Example I-1 and Comparative Example I-2. In, the average value of the specific resistance is 5.0 × 10 ⁷ Ω · cm or more in any of the central measurement area, the middle measurement area, and the outer peripheral measurement area of the main surface, and the variation coefficient of the specific resistance is It is 0.50 or less, 0.39 or less, the transfer density is 9.5 × 10 ³ cm ^-2 or less, 8.6 × 10 ³ cm ^-2 or less, and the surface flatness is 0.8 μm or less. It was small. That is, in Example I-1 and Example I-2 in which the above measure I was carried out, a semi-insulating GaAs crystal substrate having a uniform microdistribution of specific resistance on the main surface and high micro flatness on the main surface was obtained. Obtained.

Here, since the semi-insulating GaAs crystal substrate of Example I-1 is cut out from the most seed side of the semi-insulating GaAs crystal of Example I, the semi-insulating GaAs crystal of Example I-1 The main surface of the substrate corresponds to the cross section of the semi-insulating GaAs crystal of Example I on the most seed side. Further, since the semi-insulating GaAs crystal substrate of Example I-2 is cut out from the tail end side of the semi-insulating GaAs crystal body of Example I, the semi-insulating GaAs crystal substrate of Example I-2 The main surface of the semi-insulating GaAs crystal of Example I corresponded to the cross section on the tail end side of the semi-insulating GaAs crystal. Therefore, the results for the main surfaces of Examples I-1 and I-2 corresponded to the results for the most seeded and tailed cross sections of the semi-insulating GaAs crystal of Example I. That is, in Example I in which the above measure I was carried out, a semi-insulating GaAs crystal body having a uniform micro-distribution of resistivity in the cross section and high micro flatness in the cross section was obtained.

The semi-insulating GaAs crystal substrates of Example II-1 and Example II-2 manufactured by performing the above-mentioned measure II with respect to the semi-insulating GaAs crystal substrates of Comparative Example I-1 and Comparative Example I-2. In, the average value of the specific resistance is 5.0 × 10 ⁷ Ω · cm or more in any of the central part measurement area, the middle part measurement area, and the outer peripheral part measurement area of the main surface, and the variation coefficient of the specific resistance is It is 0.42 or less, which is 0.50 or less, the dislocation density is 9.5 × 10 ³ cm ^-2 or less, 9.0 × 10 ³ cm ^-2 or less, and the surface flatness is 0.8 μm or less. It was small. That is, in Example II-1 and Example II-2 in which the above measure II was performed, a semi-insulating GaAs crystal substrate having a uniform microdistribution of specific resistance on the main surface and high micro flatness on the main surface was obtained. Obtained.

Here, since the semi-insulating GaAs crystal substrate of Example II-1 is cut out from the most seed side of the semi-insulating GaAs crystal of Example II, the semi-insulating GaAs crystal of Example II-1 The main surface of the substrate corresponded to the cross section on the most seed side of the semi-insulating GaAs crystal of Example II. Further, since the semi-insulating GaAs crystal substrate of Example II-2 is cut out from the tail end side of the semi-insulating GaAs crystal body of Example II, the semi-insulating GaAs crystal substrate of Example II-2 The main surface of the semi-insulating GaAs crystal of Example II corresponded to the cross section on the tail end side of the semi-insulating GaAs crystal. Therefore, the results for the main surfaces of Examples II-1 and II-2 corresponded to the results for the most seeded and tailed cross sections of the semi-insulating GaAs crystals of Example II. That is, in Example II in which the above-mentioned measure II was carried out, a semi-insulating GaAs crystal body having a uniform micro-distribution of resistivity in the cross section and high micro flatness in the cross section was obtained.

The semi-insulating GaAs crystal substrate of Example III-1 and Example III-2 manufactured by performing the above-mentioned measure III with respect to the semi-insulating GaAs crystal substrate of Comparative Example I-1 and Comparative Example I-2. In, the average value of the specific resistance is 5.0 × 10 ⁷ Ω · cm or more in any of the central measurement area, the middle measurement area, and the outer peripheral measurement area of the main surface, and the coefficient of variation of the specific resistance is It was 0.10 or less, the dislocation density was 5.5 × 10 ³ cm ^-2 or less, and the surface flatness was 0.5 μm or less, which was extremely small. That is, in Examples III-1 and III-2 in which the above-mentioned measure III was carried out, the micro-distribution of the specific resistance on the main surface was extremely uniform, and the micro-flatness of the main surface was extremely high. The substrate was obtained.

Here, since the semi-insulating GaAs crystal substrate of Example III-1 is cut out from the most seed side of the semi-insulating GaAs crystal body of Example III, the semi-insulating GaAs crystal of Example III-1 The main surface of the substrate corresponded to the most seeded cross section of the semi-insulating GaAs crystal of Example III. Further, since the semi-insulating GaAs crystal substrate of Example III-2 is cut out from the tail end side of the semi-insulating GaAs crystal body of Example III, the semi-insulating GaAs crystal substrate of Example III-2 The main surface of the semi-insulating GaAs crystal of Example III corresponded to the cross section on the tail end side of the semi-insulating GaAs crystal. Therefore, the results for the main surfaces of Examples III-1 and III-2 corresponded to the results for the most seeded and tailed cross sections of the semi-insulating GaAs crystals of Example III. That is, in Example III in which the above-mentioned measure III was carried out, a semi-insulating GaAs crystal body in which the micro-distribution of resistivity in the cross section was extremely uniform and the micro flatness in the cross section was extremely high was obtained.

The embodiments and examples disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the embodiments and examples described above, and is intended to include the meaning equivalent to the scope of claims and all modifications within the scope.

2 Crystal growth substrate, 3 Insulation material, 3a 1st material, 3b 2nd material, 4 GaAs raw material melt, 10 Semi-insulating GaAs crystal, 11 Semi-insulating GaAs crystal substrate, 11n notch, E1, E2 measurement Electrode, F0 center measurement area, F1 middle measurement area, F2 outer circumference measurement area, SC GaAs seed crystal.

Claims (3)

On a main surface with a diameter of 2 Rmm and a surface orientation of (100),
For each of the three measurement regions centered on points at distances of 0 mm, 0.5 Rmm, and (R-17) mm in the [010] direction from the center of the main surface.
The resistivity is measured at 101 points with a pitch of 100 μm over a distance of -5 mm to +5 mm in the [010] direction from the center of the measurement region, and the resistivity is calculated from the measured values of the resistivity at the 101 points. The average value of resistivity is 5 × 10 ⁷ Ω · cm or more,
The dislocation density calculated as the density within 1 mm square of the center of each measurement region of the etch pit formed when etching in molten potassium hydroxide at 450 ° C. for 20 minutes is 9.5 × 10 ³ cm ^-2 or less. A semi-insulating gallium arsenide crystal substrate. The semi-insulating gallium arsenide crystal substrate according to claim 1, wherein the main surface has a diameter of 2 Rmm of 150 mm or more. The semi-insulating gallium arsenide crystal substrate according to claim 1 or 2, wherein the dislocation density is 5.5 × 10 ³ cm ⁻² or less.

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