JP3399044B2 - Hall element and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Hall element, and in particular, GaInAs having a low unbalance rate and excellent uniformity of characteristics.
Regarding Hall element.

[0002]

2. Description of the Related Art A Hall element is known as one of so-called magnetoelectric conversion elements which detects a magnetic field and generates an electric signal according to the strength thereof, that is, the magnetic field strength. This Hall element is a kind of magnetic sensor that detects the Hall voltage generated by the movement of electrons in the semiconductor known as the Hall effect when a magnetic field is applied, as a detection amount. In addition to being used as a position detection sensor or a current sensor, it is widely used as a probe (probe) for measuring magnetic field strength.

Semiconductor materials for Hall elements include elemental semiconductors such as silicon (Si) and germanium (Ge), as well as elements such as indium antimonide (InSb), indium arsenide (InAs) and gallium arsenide (GaAs). A III-V binary compound semiconductor formed by combining two elements belonging to Group V with an element belonging to Group III of the periodic table is also used. However, looking at a conventional Hall element made of a compound semiconductor, there are advantages and disadvantages in the characteristics of the Hall element depending on the physical properties of the semiconductor used. For example,
The Hall element made of GaAs has little change in temperature due to the relatively large band gap of the GaAs semiconductor, but on the contrary, its electron mobility is somewhat low, so that its product sensitivity is lower than that of the InSb Hall element. is there. On the other hand, the InSb Hall element has a large bandgap of the InSb semiconductor, so that the temperature change of the characteristics is large.
It has an advantage that high product sensitivity can be obtained.

Recently, the need for precision sensing technology in high temperature environments, such as precise rotation control of automobile engines, has increased, it has the ability to output a high Hall voltage, and the change in element characteristics due to temperature is low. There has been a demand for suppressed high-performance Hall elements. Here, the Hall voltage depends on the Hall coefficient of the semiconductor material, and the higher the Hall coefficient, the higher the Hall voltage output capability. Moreover, this Hall coefficient increases in proportion to the electron mobility of the semiconductor material. Therefore, in order to obtain a high Hall output voltage, that is, to obtain a highly sensitive Hall element, it is necessary to use a semiconductor material exhibiting a high electron mobility.

Therefore, along with the demand for high-performance Hall elements from the industrial world, investigations from the viewpoint of the physical properties of semiconductor materials have progressed, and recently, III-V group compound semiconductors similar to binary compound semiconductors such as GaAs and InP have been recently developed. However, III- such as gallium arsenide and indium made by mixing three types of elements
New high-sensitivity Hall devices using heterojunctions of group V compound ternary mixed crystals and InP have been realized (for example, Shinobu Okuyama et al., 1993 Autumn Proceedings of 53rd Annual Meeting of the Applied Physics Society of Japan). No. 3 (published by Japan Society of Applied Physics 1992), Lecture No. 16a-SZC-16, 1078
page). It has been reported that this new GaInAs Hall element brings about an unprecedented excellent product sensitivity because the characteristic temperature change is relatively small and the room temperature mobility is extremely high.

[0006]

In addition to the above temperature characteristics and product sensitivity, an unbalanced voltage is one of the important characteristics of Hall elements. This unbalanced voltage is an output voltage generated when no magnetic field is applied. Here, the unbalanced voltage is V ₀ . Further, assuming that the Hall voltage generated by the Hall element under a certain magnetic field strength is V, the unbalance rate is generally defined by the following equation. Unbalance rate (%) = {V ₀ / (V−V ₀ )} × 100 This unbalance rate is equivalent to the S / N ratio of the output voltage, and the lower the better. It must also be uniform at each output level. The reason is that if the unbalance ratio is large, the ratio of V ₀ to V becomes large when the Hall output voltage is small,
There is an adverse effect that the S / N ratio deteriorates. Further, if the unbalance ratio is not uniform, practical problems such as complicated adjustment of the offset circuit provided for removing the unbalance voltage component occur.

It has already been confirmed that a high room temperature mobility can be obtained in the heterojunction between the GaInAs magnetosensitive layer and the InP buffer layer (Kenjiro Konuma et al., 1).
1992 Autumn Proceedings No. 53 1 (published by Japan Society of Applied Physics, 1992), Lecture No. 18a-ZE-3, p. 283). However, regarding the unbalance ratio, the quality that the constituent material of the heterojunction should have in order to reduce the unbalance ratio is not yet clear. Therefore, the S / N ratio of the Hall output voltage cannot be improved as described above,
In addition, the compensation of the unbalanced voltage component becomes complicated, and GaIn
There was a problem in using the As heterojunction Hall element. In the present invention, in order to obtain a high-performance Hall element using GaInAs as a magnetic sensitive layer with a low unbalance ratio, the requirements for the epitaxial growth layers such as the InP buffer layer and the magnetic sensitive layer have been studied carefully. It was found that the density of particles such as growth hills existing on the surface of the p-type has a significant influence, and from this viewpoint, the requirements that the epitaxial growth layer should have are clarified. Here, the growth hill refers to a protrusion or a dent generated along with the epitaxial growth of the crystal layer. These growth hills are generally composed of crystal planes of a certain orientation. If such protrusions or depressions are present in the crystal layer portion that exerts the function of the element, it hinders the uniform distribution of the operating current. Growth hills are generated depending on the crystal growth conditions. GaInAs deposited on the InP crystal layer
In the crystal layer, a growth hill may appear on the GaInAs crystal surface with the portion of the surface of the InP layer where P is removed as the nucleus. Further, not the growth hill composed of a specific crystal plane, but irregular-shaped particle-shaped projections or depressions also hinder the homogenization of characteristics such as unbalance voltage like the growth hill. Therefore, from the viewpoint of eliminating the factors that adversely affect the characteristics of the Hall element, it is convenient to define the growth hill, the total density of particles, and the like.

[0008]

That is, according to the present invention, when a GaInAs crystal layer is used as a magnetic sensing layer and InP is used as a buffer layer, the diameter existing on the surface of the InP buffer layer is first converted to 50 μm. Set the density of the following growth hills to 5
The number is 0 / cm ² or less. Furthermore, the density of particles such as growth hills having a diameter of 50 μm or less is 170 particles / converted to the diameter existing on the surface of the GaInAs magnetic sensitive layer grown on the InP buffer layer.
cm ² or less. As a result, Ga having an excellent unbalance rate
An InAs Hall element is provided. As a means for suppressing the growth hill, GaInA after the growth of the InP buffer layer is performed.
When moving to the growth of the s-sensitive layer, the GaIn layer was exposed to an environment having a P concentration higher than that required for the growth of the buffer layer, and
By performing the growth of the As magnetosensitive layer, GaInA
s It is possible to store the density of particles such as growth hills on the surface of the magneto-sensitive layer within a certain level.

Usually, in forming a GaInAs Hall element, the plane orientation is {100} or {100}.
A semi-insulating iron (Fe) -doped InP single crystal substrate having a plane orientation inclined at an angle of several degrees [110] from the plane is used. Practically, the specific resistance is 10 ⁴ Ω · cm or more, 10
InP single crystal substrates of less than ⁸ Ω · cm are generally used, and these crystals are liquid-sealed Czochralski (L
The EC) method and the vertical Bridgman method called VB method these days can be easily manufactured.

On this InP single crystal substrate, an n-type Ga _x In _1-x As layer serving as a magnetic sensing layer is formed.
InP is generally deposited as a buffer layer on an nP single crystal substrate. This is Ga _x In _1-x A
In order to maintain high electron mobility in s, the purpose is to suppress diffusion of Fe impurities from the InP single crystal substrate into the Ga _x In _1-x As epitaxial growth layer. In addition, by providing a buffer layer, Ga _x
Since it also has an effect of suppressing the propagation to the In _1-x As epitaxial growth layer, the high sensitivity characteristics of the GaInAs Hall element can be maintained without unnecessarily decreasing the electron mobility of Ga _x In _1-x As. Invite the benefits of. From the viewpoint of lattice matching with InP and GaInAs, aluminum / indium arsenide (AlInAs) can also be used as the buffer layer.

For the growth of the InP buffer layer, VPE method and MOC are used.
A vapor phase growth method such as the VD method is generally used. Regardless of the vapor phase growth method, a cylindrical growth hill appears on the surface of the InP layer as it grows. All of the growth hills have a circular or oval top plate, and the top plate was used as a substrate.
The feature is that the orientation is almost the same as the plane orientation of the nP crystal. For example, a growth hill existing in an InP growth layer deposited on an InP crystal substrate having a plane orientation of (100) has a top plate substantially parallel to (100). (100)
2 ° inclined from the surface in the <110> direction by 2 °
In the case of an off-substrate, the growth hill also has an upper surface with a plane orientation inclined by about 2 ° in the same direction from (100). The surface density of these growth hills can be easily measured, for example, along with the distribution of diameters in a particle counter that utilizes the scattering of laser scanning light that is commercially available. Looking at the diameter values measured with this type of instrument, the distribution is not always uniform. For example, the diameters of growth hills on the surface of a certain InP buffer layer are almost evenly distributed within a region of 2 to 30 μm, but in other cases, the diameters are mainly distributed within a width of 5 to 70 μm. is there. However, the characteristic of the growth hill on the InP layer is that the larger the diameter, the less the height difference from the InP surface, regardless of the distribution. Since the height difference from the InP surface is large, that is, the diameter of the growth hill is small, if the stepped portion of the protrusion is large, it becomes a magnetic sensing layer that is deposited on the InP layer to become Ga _x.
In _1-x As protrudes into. This is schematically shown in FIG. In the figure, (111) is a growth hill having a diameter of more than 50 μm, and the growth is planar rather than in the height direction. (11
2) is a growth hill having a diameter of 50 μm or less and grows like a protrusion. If many protrusions due to such growth of the InP layer exist in the magnetic sensing part layer, the improvement of the electron mobility of the magnetic sensitive part layer is hindered. Further, the presence of the growth hill in the magnetic sensing layer partially changes the film thickness of the magnetic sensing layer, resulting in an increase in the unbalance ratio of the Hall element. As a result of diligent study by the present inventors, it was found that a minute growth hill having a diameter of 50 μm or less in terms of the diameter on the surface of the InP layer has high and low steps that affect the unbalance rate. Therefore, in the present invention, the diameter conversion value of the growth hill is specified to be 50 μm or less.

In practice, the unbalance rate of the Hall element is usually ± 1.
The density of the growth hills on the InP layer was examined on the basis that 0% or less was allowed. As will be described later, in the case of the present invention, the density of the growth hills on the surface of Ga _x In _1-x As needs to be 170 pieces / cm ² or less in order to obtain the imbalance rate of ± 10%. I
The growth hills generated during the growth of the nP layer act as nuclei for Ga _x
The growth continues even during the deposition of In _1-x As. Further, new growth hills are generated along with the deposition of Ga _x In _1-x As, and the density of the growth hills on the surface of the same layer is higher than that of the InP underlayer. The density is determined in consideration of the rate of increase of the growth hills. Further, the size and density of the growth hills are determined by maintaining the flatness of the heterojunction interface between the InP layer and Ga _x In _1-x As, and by increasing the electron mobility required for high sensitivity of the Hall element. There is also a meaning to prevent the decrease of.

The density of growth hills on the InP crystal layer is I
It has been found that there is a range of layer thicknesses that strongly depends on the layer thickness of the nP layer and is suitable for reducing the density of the growth hills.
This is shown in FIG. That is, the density of the growth hills was 50 / cm ² or less in both cases where the InP layer thickness was less than 20 nm and over 60 nm. Therefore, InP
In the case of selecting as the buffer layer, the layer thickness of the same layer may be accommodated within either range.
When the layer thickness of the nP layer is less than 20 nm, InP is sometimes used.
This results in being affected by the quality difference of the single crystal substrate, resulting in a situation where the quality of the InP crystal layer as the buffer layer cannot be sufficiently exhibited. On the contrary, when the layer thickness is set to a range exceeding 60 nm, the influence of the quality of the InP single crystal substrate on the InP growth layer is reduced, and an InP buffer layer having stable characteristics is easily obtained. However, if the layer thickness is set to be extremely thick, a problem occurs in mesa etching required in the manufacturing process of the Hall element, resulting in an increase in unbalance voltage. In consideration of this point, the film thickness of InP as the buffer layer is 60 nm to 200 n.
Good results are obtained when set around m.

Next, the environment during the growth of the InP buffer layer, particularly the P concentration used for the growth will be described. V as a P source
In the PE vapor phase growth method, phosphorus trichloride (PCl ₃ )
Phosphine (PH ₃ ) is generally used in the OCVD method. In the MOCVD method, the amount of PH ₃ supplied to the growth reaction system at a general InP growth temperature of 600 to 700 ° C. is generally in the range of 0.01% to several tens%. PH
_The large range of the supply amount of ₃ is mainly due to the difference in the growth method between the reduced pressure and the normal pressure (atmospheric pressure) and the difference in the heating method for the growth substrate. In addition, Ga _x is formed on the InP layer.
When stacking In _1-x As, it is a conventional practice to hold the InP underlayer in an atmosphere having a phosphorus concentration substantially the same as that required for growing the InP layer just before starting stacking. This is due to the fact that InP is grown before the growth of Ga _x In _1-x As.
The purpose is to prevent evaporation and desorption of phosphorus from the underlayer.

Furthermore, although depositing a Ga _x In _1-x As sensing section layer thereon an InP buffer layer as a base, the Ga _x I
Limit the density of growth hills existing on the surface even in n _1-x As. That is, the density of particles having a diameter of 50 μm or less on the surface of the same layer is 170 / cm ² or less. Figure 3
This is because the unbalance rate of the GaInAs Hall element exceeds ± 10% when the density value of the present invention is exceeded, as shown in FIG. Ga
In order to reduce the density of growth hills on the surface of _x In _1-x As,
First, as described above, the density of the growth hills on the surface of the underlying InP layer is set to an appropriate specified value.

On the surface of Ga _x In _1-x As, the underlying I
In addition to the growth hills that continue to grow from the nP buffer layer, Ga _x
There is a growth hill peculiar to In _1-x As. This peculiar growth hill is in the form of particles that do not include a specific crystal plane on the surface of the InP layer. In addition to the growth hills existing from the InP layer, the presence of the particulate growth hills also promotes the nonuniformity of the unbalanced voltage. The present inventor has found that Ga _x In
It was found that the particulate growth hills on the _1-x As crystal layer are generated due to the desorption of P from the surface of the InP buffer layer. G
In the growth of a _x In _1-x As, the growth reaction system of PH ₃ is supplied during the transition period between the growth of the InP buffer layer and the start of the growth of the Ga _x In _1-x As magnetic sensitive layer. The operation of switching to arsine (AsH ₃ ) gas containing arsenic (As) is performed. In the present invention, not only is the source gas containing the group V element of the periodic table changed as in the prior art, but the concentration of P in the growth reaction system is increased as compared with that during the growth of the InP layer. No special operation is required to increase the P concentration in the growth reaction system during this transition period, and it is easily achieved by simply increasing the supply flow rate of PH ₃ gas as the P source to the growth reaction system. . By this operation, thermal desorption of P from the surface of the InP buffer layer located under the growth environment can be efficiently prevented, and Ga _x In _1-x
It is possible to prevent the generation of particulate growth hills on the surface of the As magnetic sensing part layer.

There is no particular limitation on the rate of increasing the P-containing raw material in the transition period, but it is 550 ° C. which is a general growth temperature of the InP layer in the MOCVD method using PH ₃ as the P source. InP in the temperature range of ~ 650 ° C
Supplying PH ₃ at a flow rate that is 2 to 3 times the PH ₃ flow rate required for growing the layer is effective in reducing the density of the growth hills on the surface of the Ga _x In _1-x As crystal layer. Furthermore,
If the PH ₃ flow rate is about 6 to 7 times, the growth hill can be suppressed. This new method of manufacturing a Ga _x In _1-x As / InP heterojunction makes it possible to unify the types of growth hills existing on the surface of the Ga _x In _1-x As. Further, this unification brings an advantage that the density of the growth hills that continue to grow from the surface of the InP layer to Ga _x In _1-x As may be controlled. The growth method of the above InP buffer layer and Ga _x In _1-x As is not particularly limited, and may be molecular beam epitaxial growth method (MBE method), MOVPE method, or MOVPE method.
The MO / MBE method that combines both MBE and MBE can be applied.

Further, Ga which is responsible for the magnetic sensing section_x In_1-x Of As
Regarding the mixed crystal ratio x, 0.37 ≦ x ≦ 0.57
Is desirable. Because Ga that lattice-matches InP_x 
In _1-x As the mixed crystal ratio of As deviates from x = 0.47,
Ga_x In_1-x Difference in lattice constant between As and InP, that is, case
The degree of inconsistency also becomes remarkable and induces a large amount of crystal defects, etc.
Not only the crystallinity decreases, but also the electric mobility such as the decrease in electron mobility.
It also deteriorates the characteristics and greatly improves the product sensitivity of the Hall element.
Because it causes trouble. In addition, Ga that becomes the magnetically sensitive portion_x In
_1-x There is no particular limitation on the carrier concentration of As.
However, the high sensitivity which is the basis for obtaining the high sensitivity GaInAs Hall element
In order to exert mobility characteristics, it is approximately 1 × 10.¹⁵cm
^-35 × 10 or more¹⁷cm^-3The following is convenient. what
Therefore, the carrier concentration is 1 × 10¹⁵cm^-3Is less than
And the input and output electrodes of a Hall element
Does it cause instability of ohmic characteristics due to increased resistance?
It is. Carrier concentration is 5 × 10¹⁷cm^-3Crossing
The electron mobility of the same layer is remarkably reduced and it has high sensitivity.
It is not a good idea to obtain a GaInAs Hall element
Is. Although there is no limitation on the film thickness of the magnetic sensing part layer, it will be described later.
Considering the processing accuracy during the mesa etching process, it is usually several μ
m or less.

InP grown on an InP single crystal substrate
A GaInAs Hall element is manufactured by using an epitaxial wafer composed of a buffer layer and a Ga _x In _1-x As magnetic sensing part layer as a base material. First, using well-known photolithography technology, etching technology, and other processing technologies, Ga _x In _1-x As and I that exhibit the function as a Hall element are displayed.
So-called mesa etching is applied to the nP layer to process the element functional region into a mesa. In this mesa processing, two semiconductor mesa layers crossing each other in a cross shape are orthogonal to each other <0.
The bar 11> and the <0 bar 1 bar-1> direction are provided in parallel.

A method for obtaining the mesa structure will be described here. First, the outermost surface of the base material, Ga _x In
_1-x As A general photoresist material is applied to the surface of the magnetic sensitive layer, and then the resist material is left only in the areas where the magnetic sensitive portion and the input and output electrodes are formed by the ordinary photolithography technique. The resist material existing in the other areas is peeled off and removed. Then, using an inorganic acid, Ga
Etching is performed on _x In _1-x As. The G in the region where the photoresist material has been removed by this etching
The a _x In _1-x As is selectively removed, and only the magnetic sensing part and the electrode formation region remain in a mesa shape. Further, etching in the depth direction is advanced, and this Ga _x In _1-x A
A portion of the InP layer existing immediately below s is selectively removed by etching. Due to this etching, the vertical cross section of the electrode forming portion and the magnetic sensitive portion can be formed by <0 bar 11>
Seen from the directions of crystal axes that are orthogonal to each other in the <0 bar 1 bar-1> direction, the cross section in the <0 bar 11 >> direction has a trapezoidal shape, a so-called forward mesa shape, and conversely <0 In the direction of the bar 1 bar-1> crystal axis, an inverted trapezoidal so-called inverted mesa cross section is provided. From an electrical point of view, this mesa etching can ensure the insulation of the element functional portion including the electrode forming portion and the magnetic sensing portion. However, regarding the mesa etching, when the total thickness of the epitaxial growth layer exceeds 5 μm, the difference in the etching shape based on the crystal axis (crystal orientation) becomes remarkable as described above, which causes one of the characteristics of the Hall element, the unbalanced voltage. Will increase. Therefore, it is convenient to set the total thickness of the epitaxial growth layer to about 5 μm or less by adjusting the thickness of the InP buffer layer, because the imbalance ratio is not increased.

After performing such mesa etching, input and output electrodes are formed. In this formation, a photoresist material is applied to the entire surface of the mesa-etched wafer. After that, the region where the electrode is to be formed is patterned by a known photolithography method, and only the photoresist material in the region where the input and output electrodes are formed is peeled and removed. Ga _x In _1-x
The surface layer of As is exposed. Next, gold (A
u) Vacuum deposition of germanium (Ge) alloy. Although the Au.Ge alloy is exemplified here as the electrode material, the electrode material is not particularly limited to this, and a material that can obtain an ohmic electrode for the n-type GaInAs crystal may be used. Next, a silicon dioxide (SiO ₂ ) film having an insulating property to be a passivation film is coated on the wafer surface by the plasma CVD method. Although a silicon dioxide film is proposed here as the coating film, a film having another insulating property, such as silicon nitride (SiN), may be used.
Further, there is no problem even if the passivation film is obtained by the usual thermal CVD method.

The silicon dioxide insulating film manufactured as described above is covered with a general resist material. After that, the resist material in the portion corresponding to the position for forming the dicing line necessary for separating the electrode portion and each element is removed by photolithography technique to expose the SiO ₂ insulating film immediately below. . Further, the exposed SiO ₂ insulating film is immersed in hydrofluoric acid (HF) to dissolve and remove the SiO ₂ insulating film in the relevant portion. This exposes the surface of the input / output electrodes and the surface of Ga _x In _1-x As at the portion where the dicing line is formed. In order to actually separate the individual elements, the Ga _x In exposed in the portion corresponding to the dicing line is exposed.
_1-x As may be removed by etching using a suitable inorganic acid. InP directly under Ga _x In _1-x As
The layer is removed with an inorganic acid. Usually, etching is further advanced to remove a part of the surface layer of the InP single crystal substrate.
This is done so as to reduce the mechanical damage to the epitaxial growth layer and the hetero interface during element isolation by the scriber or blade used for dicing.

[0023]

[Function] InP forming the buffer layer and Ga _x I forming the magnetic sensitive layer
With respect to n _1-x As, by limiting the surface state of the n _{1 -x} As, in particular, the density of the growth hills, it has an effect of making the characteristics of the GaInAs Hall element uniform.

[0024]

EXAMPLES The present invention will be described in detail based on examples. Figure 4
FIG. 3 is a schematic plan view of a Hall element having Ga _x In _1-x As as a magnetic sensing layer according to the present invention. In addition, FIG.
FIG. 9 is a schematic view of a vertical cross section along the direction of the broken line AA ′ of the schematic plan view shown in FIG. In forming an epitaxial wafer as a base material, a semi-insulating high-resistance InP single crystal substrate (101) having a specific resistance of about 10 ⁶ Ω · cm and a plane orientation (100) formed by adding iron (Fe) is used. I was there. First, by a normal pressure MOCVD method using C ₅ H ₅ In as an In source and PH ₃ as a P source, a pressure of about 200 n was obtained at a temperature of 610 ° C.
An undoped InP layer (102) was grown to a thickness of m. The PH ₃ used was diluted with high-purity hydrogen gas so that the concentration became 10%, and the InP layer (102)
The flow rate of PH ₃ was set to 60 cc / min for the growth of P. The total flow rate of hydrogen gas etc. supplied to the growth reaction system is 7
Since it was 000 cc / min, the concentration of PH ₃ in the growth system was about 0.86%. As a result of measuring the carrier concentration of the InP layer (102) by the Hall effect method, about 2 × 1
It was 0 ¹⁵ cm ^-3 . Also, the density of growth hills of 50 μm or less in terms of the diameter on the surface of the InP layer (102) was measured by a particle counter using a commercially available laser beam, and it was 4 pieces / cm ² .

After that, in the transition to the growth of the Ga _x In _1-x As crystal layer by the MOVPE growth reaction system, the flow rate of PH ₃ was increased to 360 cc / min. This flow rate corresponds to 6 times PH ₃ supplied to the growth reaction system during the growth of the InP layer (102). The total flow rate of gas supplied to the growth system is 7,000 cc even during the transition.
Therefore, the concentration of PH _{3 in} the system was 5.1%. In addition, As for growth of Ga _x In _1-x As
The supply of PH _{3 to} the growth reaction system was stopped prior to the start of H ₃ distribution. Then, on the InP buffer layer (102), the carrier concentration was 2 × 10 ¹⁶ cm ⁻³ and the Ga mixed crystal ratio was 0.47.
Undoped n-type Ga _0.47 In _0.53 As (10
3) was deposited at a temperature of 610 ° C. to a thickness of 250 nm.
The total flow rate of gas supplied to the growth reaction system was 7000 cc / min, and the flow rate of AsH ₃ gas with a concentration of 10% was 120 cc / min.
Minutes PH ₃ gas was not added to the system during the growth of Ga _0.47 In _0.53 As (103). The density of the growth hills of 50 μm or less in terms of the diameter of the surface was 8 / cm ² when measured with a particle counter.

Next, the Ga _x In _1-x As magnetic sensitive layer (10
3) The entire surface of 3) is covered with a normal organic photoresist material, and then the well-known photolithography technology and etching technology are used, and the area (104) to be formed with the input / output electrodes and the magnetic sensitive section is formed. Processed into shape. In this example, an inorganic acid was used for the mesa etching process. After that, the entire surface of the Ga _x In _1-x As magnetic sensing part layer (103) was covered again with the organic resist material. Next, using a known photolithography technique, only the resist material existing in the regions where the pair of input electrodes (105) and output electrodes (106) are to be formed is removed, and Ga _x In is removed.
_{The surface of the 1-x} As magnetic sensitive layer (103) was exposed. After that, an Au.Ge alloy containing about 13% by weight of Ge was vacuum-deposited. After that, the wafer is immersed in an organic solvent mixed solution, the resist material is peeled off, and at the same time, the wafer is deposited on the resist material by vapor deposition.
The alloy film was removed by the lift-off method. Next, the wafer on which the alloy film to be the electrode was adhered was heat-treated at a temperature of 420 ° C. for several minutes to obtain an ohmic electrode. Further, a pad electrode (107) was provided by electrically connecting each electrode with the input / output electrodes (105 and 106). The pad electrode (107)
Was exposed by mesa etching and placed on the surface layer of the InP single crystal substrate (101). This is to prevent the strain from being directly introduced into the Ga _x In _1-x As magnetic sensitive layer during alloying.

Next, a region other than the input / output electrode portions on the surface of the Hall element which has undergone the above steps was covered with a silicon dioxide film (108) by a plasma CVD method to a film thickness of about 400 nm. Further, the entire surface of the element is covered with a photoresist material again, and the Hall element formed on the entire surface of the wafer is separated into individual elements, and patterning is performed so as to form a dicing line (109) to form a Hall element chip. . After that, the oxide film (108), the Ga _x In _1-x As magnetic sensitive layer (103) and the InP layer (102) existing directly below the portion corresponding to the dicing line (109) were removed by etching. Further, the etching was advanced to remove the constituent materials to reach the surface layer of the InP single crystal substrate (101), and the dicing line (109) was formed.

The electrical characteristics of the Hall element manufactured as described above, particularly the unbalance rate, were evaluated. In addition, a comparison was made with the unbalance rate of the conventional example. GaIn for comparison
The As Hall element has a growth hill density of 64 / cm ² In
It indicates a Hall element including a P buffer layer. FIG. 6 shows the distributions of the absolute values of the imbalance ratios of the present invention and the conventional example for comparison. In the GaInAs Hall element according to the present invention, the average unbalance rate was ± 3.2%. On the other hand, the conventional example is ± 14.
Clearly, it was 0%, and the superiority of the present invention was revealed.

[0029]

EFFECTS OF THE INVENTION By newly defining the surface conditions of the buffer layer and the magnetic sensitive layer, a high-performance Ga having an excellent imbalance ratio can be obtained.
An InAs Hall device is provided.

[Brief description of drawings]

FIG. 1 is a structural sectional view schematically showing a growth hill.

FIG. 2 is a diagram showing the relationship between the density of growth hills and the InP layer thickness.

FIG. 3 is a diagram showing a relationship between an unbalance rate and a density of growth hills.

FIG. 4 is a diagram schematically showing a plane of a Hall element according to the present invention.

5 is a schematic view of a vertical cross section taken along line AA ′ of the Hall element shown in FIG.

FIG. 6 is a diagram comparing the distributions of unbalance rates.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-198877 (JP, A) JP-A-57-177583 (JP, A) JP-A-6-77556 (JP, A) JP-A-5- 275767 (JP, A) JP-A-52-65691 (JP, A) JP-A-63-226027 (JP, A) Proceedings of the 53rd Autumn Meeting of the Applied Physics Society of Japan, Autumn 1992, September 16, 1992 , Lecture No. 16a-SZC-16, page 1078 (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 43/06 H01L 43/14

Claims (2)

(57) [Claims] 1. An InP buffer layer and Ga _x on an InP crystal substrate.
A heterojunction composed of an In _1-x As magneto _- sensitive layer;
In the Hall element in which the nP buffer layer has a surface density of growth hills of 50 μm or less in terms of diameter of 50 / cm ² or less, G
The Hall element characterized in that the a _x In _1-x As magneto _- sensitive layer has a surface density of 170 hills / cm ² or less in terms of diameter of growth hills of 50 μm or less. 2. When the Ga _x In _1-x As magnetosensitive layer is vapor _- deposited on the InP buffer layer, the InP buffer layer is exposed to an atmosphere having a phosphorus concentration higher than that required for the growth of the buffer layer. The method for manufacturing a Hall element according to claim ₁ , wherein a Ga _x In _1-x As magnetosensitive layer is grown.