JP3399046B2 - Hall element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a Hall element composed of a heterojunction with GaInAs, and more particularly to high sensitivity of the 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. Besides being used as a position detection sensor, a current sensor, etc., it is used as a probe (probe) for measuring magnetic field strength, and is used in industry.

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 obtained 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, Ga
The Hall element made of As has a small change in temperature due to the relatively large band gap of the GaAs semiconductor, but on the contrary, its mobility is somewhat low, so that the product sensitivity is InSb.
It has the drawback of being lower than the Hall element consisting of. On the other hand, the InSb Hall element has an advantage that a high product sensitivity can be obtained although the characteristic temperature change is large because the band gap of the InSb semiconductor is low.

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 new high-performance Hall elements that are suppressed. 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. The Hall coefficient also increases in proportion to the 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.

For this reason, in consideration of physical properties of semiconductor materials, the so-called two-dimensional confinement, which is called two-dimensional confinement, has been advanced in recent years in response to the demand for high-performance Hall elements from the industrial world.
A Hall element utilizing a high mobility characteristic manifested by a two-dimensional electron gas has also been proposed (for example, Japanese Patent Publication No. 3-25035).
However, the history of research and development of Hall elements using such two-dimensional electrons is old, and Si semiconductor and silicon dioxide (Si
Heterojunction structure with O _2), so-called Simos (meta
Hall devices using two-dimensional electrons expressed by the l-oxide-semiconductor structure have already been reported in the mid-1960s (eg RC GALLAGHER and WS CORA).
K, Solid-State Electronics, Volume 9 (1966),
571-580). Furthermore, theoretical understanding of Hall elements having a SiMOS structure has been made (for example, RICHARD S. HEMMERT, Solid-State Electronics,
Volume 17 (1974), 1039-1043).

Recently, gallium arsenide aluminum (Al _x Ga _{1-x) is formed} by mixing three kinds of elements in a binary compound semiconductor such as GaAs or InP and a conventional III-V group compound semiconductor. As: x represents a mixed crystal ratio.)
And gallium indium arsenide (Ga _x In _1-x As: x
Represents a mixed crystal ratio. There is also a method of forming a two-dimensional electron gas by a heterojunction with a compound ternary mixed crystal such as (1) (for example, Japanese Patent Publication No. 59-46425 and USP 4,163,3).
27). The heterojunction for obtaining such a two-dimensional electron gas is composed of an intrinsic semiconductor and an N-type semiconductor having a bandgap higher than that of the intrinsic semiconductor. For example, a combination of heterojunctions for obtaining two-dimensional electrons in which AlGaAs is an N-type semiconductor and GaAs is an intrinsic semiconductor is already known (for example, Japanese Patent Publication No. 59-46425).
And JP-B-59-53714). A semiconductor device using a two-dimensional electron gas formed by a heterojunction based on such a known combination has been realized as a high mobility field effect transistor having a gate electrode having Schottky junction characteristics. .

As such a known combination, a heterojunction of Ga _x In _1-x As and InP is mentioned in the above references. In addition to the known heterojunction combinations of various III-V group compound semiconductor materials for obtaining a two-dimensional electron gas, a heterojunction with a single semiconductor material such as germanium (Ge) is also known. An example of two-dimensional electron formation has already been given (Japanese Patent Publication No. 59).
-53714). In any case, what is essential for forming a two-dimensional electron gas is to combine semiconductors having different electron affinities.

Here, from the viewpoint of increasing the sensitivity of a Hall element using two-dimensional electrons, in order to explore the trend of the conventional technology, it has already been known to develop two-dimensional electron gases having different electron affinities. GaInAs / In
A proposal has also been made on a Hall element with high sensitivity, which uses a two-dimensional electron gas produced by a heterojunction in which Ga _x In _1-x As is an N-type semiconductor and InP is an intrinsic semiconductor based on a P heterojunction system as a magnetically sensitive portion. It is (special fair 3-
25035).

Further, although the combination forming a heterojunction is the same most recently, conversely, when Ga _x In _{1 -x} As plays a role as an intrinsic semiconductor and InP is an N-type semiconductor. Even in this case, a high-sensitivity Hall element has been realized (for example, Shinobu Okuyama et al., Autumn 1993 53rd).
Proceedings No. 3 (published by Japan Society of Applied Physics), Lecture No. 16a-SZC-16,
1078). 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.

[0010]

[Problems to be Solved by the Invention] However, such Ga
Even in a high-sensitivity Hall element that utilizes the high mobility characteristics exhibited by the InAs / InP heterojunction system, the desired high-sensitivity characteristics are not always stably obtained. Although it has already been reported that a high room temperature mobility can be obtained by a heterojunction between GaInAs and InP (for example, Kenjiro Onuma et al., Proceedings of the 53rd JSAP Autumn Meeting, 1992). ．
1 (published by Japan Society of Applied Physics), Lecture No. 18a-ZE-3,
282), the mechanism of high mobility in the same heterozygous system has not been clarified yet. Therefore, Ga _x
In _1-x As that plays a role as an intrinsic semiconductor
The heterojunction Hall element with P has a drawback that high sensitivity characteristics cannot be stably obtained.

The present invention has been made to overcome such a situation, and in order to stably obtain the high electron mobility characteristic originally possessed by the base material for the high sensitivity Hall element including the GaInAs / InP heterojunction, The requirements that the constituent elements of the heterojunction material should have are clarified, and a new means for stably obtaining a GaInAs / InP heterojunction Hall element having excellent sensitivity characteristics is provided.

[0012]

The present invention is based on Ga _x In _1-x.
Clarify the requirements that a host material including a heterojunction of As and a III-V group compound semiconductor such as InP should have in order to stably and stably exhibit its high sensitivity characteristics. That is, in a Hall element that utilizes the high mobility characteristics brought about by the heterojunction between Ga _x In _1-x As and another III-V group compound semiconductor, the Ga _x In that forms the magnetically sensitive portion is used.
Carrier concentration of _1-x As is 1 × 10 ¹⁵ cm ⁻³ or more, 5 ×
It should be 10 ¹⁷ cm ^-3 or less. The layer thickness is made smaller than the thickness of the depletion layer corresponding to the carrier concentration of the same layer. Ga _x In _1-x
In forming a heterojunction with As and InP, a strained layer is provided inside the InP layer within 50 nm from the interface of the heterojunction. In addition, Ga _x In
_1-x As and In the form a heterojunction by the Al _x In _1-x As, in the distance from the interface of the heterojunction providing the Al _x an In strain _1-x As layer within 50nm.
As a result, a Hall element having stable electron emission and high sensitivity can be obtained.

Usually, in forming a GaInAs heterojunction Hall element, a high-resistance InP single crystal substrate having a semi-insulating property is used. For practical use of the Hall element, In having a specific resistance of 10 ⁴ Ω · cm or more and 10 ⁸ Ω · cm or less
It is common to use a substrate of P single crystal. These crystals are manufactured by the liquid-encapsulated Czochralski (LEC) method, or recently the vertical Bridgman method called VB method.

An n-type Ga _x In _1-x As layer serving as a magnetic sensing layer is formed on this InP single crystal substrate, and normally, a high electron transfer is caused in the Ga _x In _1-x As layer serving as a magnetic sensing part. In order to maintain the temperature, the Fe impurity Ga from the InP single crystal substrate is used.
For the sake of such _x In _1-x As epitaxial layer of diffusion to suppress, first, to deposit the InP on InP single crystal substrate as a buffer layer (buffer layer) is generally used. By providing this buffer layer, Ga _x I
Since the effect of suppressing the propagation to the n _1-x As epitaxial growth layer is produced, the electron mobility of the Ga _x In _1-x As layer is not unnecessarily lowered and the high sensitivity characteristics of the GaInAs Hall element are maintained. It brings advantages such as being able to. Also,
The buffer layer is not limited to InP and other materials such as Al _x
The same effect can be obtained by using In _1-x As.

The above InP buffer layer and Ga _x In
The growth method of the _1-x As layer is not particularly limited, and liquid phase epitaxial growth method (LPE method), molecular beam epitaxial growth method (MBE method), metalorganic pyrolysis vapor phase growth method, so-called MOVPE, or MOVPE is used. The MO / MBE method in which both MBEs are combined can be applied.

The mixed crystal ratio x of the Ga _x In _1-x As
With respect to, it is desirable that 0.37 ≦ x ≦ 0.57. Because Ga _x In _1-x lattice-matched to InP
As x shifts from the mixed crystal ratio of As of 0.47, Ga _x In
The difference in the lattice constant between _1-x As and InP, that is, the degree of lattice mismatching becomes remarkable, which induces a large amount of crystal defects and the like, resulting in deterioration of crystallinity. Further, it is also because the electrical characteristics such as a decrease in electron mobility are deteriorated, and the product sensitivity of the Hall element is greatly hindered.

The carrier concentration of the Ga _x In _1-x As layer is 1 × 10 ¹⁵ cm ^-3 or more, which is optimum for stably exhibiting high mobility characteristics in this heterojunction system, and 5 It is limited to x 10 ¹⁷ cm ^-3 or less. This is because when the carrier concentration is less than 1 × 10 ¹⁵ cm ⁻³ , the resistance of the magneto-sensitive layer becomes high and the ohmic characteristics of the input and output electrodes of the Hall element become unstable.
On the other hand, when the carrier concentration exceeds 5 × 10 ¹⁷ cm ⁻³ , the electron mobility is significantly reduced, and it is not a good idea to obtain a Hall element having high sensitivity.

The thickness of the Ga _x In _1-x As magnetosensitive layer is made smaller than the thickness of the depletion layer region corresponding to the carrier concentration of the Ga _x In _1-x As layer described in the previous section. The depletion layer means a depletion region under zero bias. Now, if the unit charge of electrons is q, the permittivity of GaInAs is Ks, and the vacuum permittivity is ε0, the region of the depletion layer (W) can be expressed by the following equation (1) (Kawatoda Takashi, "Semiconductor Evaluation Technology"). ], 1991, published by Sangyo Tosho Co., Ltd., p. 234).

[Chemical 1] Vbi represents a diffusion potential and V represents an applied voltage. N _d is the donor concentration. When the acceptor concentration is N _a , the carrier concentration (n) of the n-type layer and N _d and N _a have _a relationship of n = N _d −N _a . Here, if N _d >> N _a , then n = N _d .
W according to the present invention is a value at V = 0. Therefore, W is given by equation (2) which is a simplified version of equation (1).

[Chemical 2] ε ₀ is 8.85 × 10 ⁻¹⁴ F / cm, and q is 1.6 × 1.
It is 0 ^-19 C. The value of Ks is 13.5 for GaAs and In
As is 11.5 (Mr. Hisao Miyazawa, "Semiconductor for Beginners", 1992, published by Tamagawa University Press). When Ks value of Ga0.47In0.53As that lattice-matches with InP is 12.4 when calculated by the interpolation method from both values. Therefore, when N _d = 5 × 10 ¹⁷ cm ^-3 and Vbi = 1,
W = 480Å. With N _d = 1 × 10 ¹⁵ cm ⁻³ ,
It becomes 1.1 μm.

As in the present invention, the thickness of the GaInA layer is set to be equal to or less than the width (W) of the depletion layer according to its carrier concentration.
This is because carriers (electrons) are accumulated at the heterojunction interface. The reason for accumulating electrons at the hetero interface is to realize high electron mobility. When the tip of the depletion layer does not penetrate the inside of the GaInAs layer at zero bias, GaIn
There are remaining electrons in the As layer. This state is schematically shown in FIG. In this case, the electrons in the GaInAs layer cannot be efficiently accumulated at the hetero interface, which does not contribute to the improvement of electron mobility. In order to accumulate the electrons in the GaInAs layer at the hetero interface, it is necessary to form a Schottky junction and apply a reverse bias to expand the depletion layer. However, this involves a manufacturing process and becomes complicated for forming a Hall element. If the thickness of the GaInAs layer is set to be equal to or less than the width of the depletion layer, the tip of the depletion layer passes through the GaInAs layer and reaches the hetero interface at zero bias. Therefore, the electrons in the GaInAs layer are swept out from the inside of the GaInAs layer, accumulate at the hetero interface, and the electron mobility can be improved. This state is schematically shown in FIG.

Further, the present inventor has further proposed that Ga _x , which forms a magnetically sensitive portion.
In forming a heterojunction between the In _1-x As layer and InP, strain is further provided within a range of 50 nm within the distance from the hetero interface inside the InP layer. We have found that mobility can be achieved. There are several methods for providing strain in the InP layer as described above. For example, after the InP layer is epitaxially grown and then the Ga _x In _1-x As layer serving as the magnetically sensitive portion is deposited, In the cooling step of the thin film growth step, the strain can be relatively easily introduced into the InP layer by appropriately controlling the cooling rate of the wafer after the thin film growth. As a result of earnest study by the present inventor, it was found that Ga _x In _{1-x in the} MOVPE method was used.
600 ° C which is a general growth temperature of As and InP thin films
Strain can be made to exist relatively easily by cooling from about 200 to 200 ° C. for about 20 minutes, that is, cooling at a rate of about 20 ° C. per minute. In addition, after the growth of InP, when the Ga _x In _1-x As serving as the magnetic sensitive portion is grown, the composition ratio x is changed to the Ga _x In ₁ -x serving as the magnetic sensitive portion.
Ga _x In _1-x As, which is slightly different from that of As, is grown with a certain layer thickness, and then Ga of a predetermined composition ratio is obtained.
_{Even if x} In _1-x As is grown as a magnetically sensitive portion, InP
Strains can form in the layers. However, in this case, Ga _x an In that having a composition ratio different from the composition ratio of Ga _x In _1-x As to the magnetically sensitive unit, an extremely thick Ga _x In _1-x As and InP and the magnetically sensitive portion _{1- If} it is interposed in the middle of _x As, the region where strain introduced in InP exists exceeds the proper range, and on the contrary, high electron mobility characteristics can be imparted to Ga _x In _1-x As that is the magnetically sensitive part. Disappear. Therefore, in selecting the method of introducing strain by changing the composition ratio as described above, InP and Ga _x are introduced in order to introduce strain.
In _1-x As Ga _x In inserted in the middle of the magnetic sensitive section
The film thickness of _1-x As should be kept at a maximum of about 10 nm.

Heterojunction with Ga _x In _1-x As is not limited to InP described in the preceding paragraph, but Al _x In
_1-x As is acceptable. Even when Al _x In _1-x As is used, the method of providing strain in the same layer is basically InP.
It is similar to the case of. That is, the region where the strained layer is provided in Al _x In _1-x As is also set to be within 50 nm from the heterojunction interface with Ga _x In _1-x As. As a result, even when Al _x In _1-x As is used, Ga _x In _{1- x} As is simply used without intervening strain.
The electron mobility is remarkably improved as compared with the case of heterojunction between Al _x In _1-x As and Al _x In _1-x As.

The region where strain exists can be confirmed by analysis using, for example, a transmission electron microscope. As one method, C
AT (Composite Analysis by)
There is a "Thickness-Fringe" method (Hiroji Kakibayashi, Fumio Nagata, "Applied Physics" Vol. 56, No. 8 (1987), p. 1047). According to this method, interference fringes (fringes) having different intervals are imaged depending on the substance or even on the same substance depending on the difference in composition. The presence or absence of strain is observed because of the steepness of the hetero interface due to the discontinuity and linearity of the interference fringes. As an example, a CAT image of a GaInAs / InP heterojunction is schematically shown in FIG. When strain exists in the InP layer, the interference fringes on the InP layer side are bent. The distance from the hetero interface (indicated by symbol d in FIG. 7) required for the bent interference fringes to return to a straight line can be measured from the CAT image. In the present invention, this distance (d) is 50 nm or less.

As an example, we will demonstrate the improvement of electron mobility in a Ga _x In _1-x As / InP heterojunction which is achieved by having strain. FIG. 3 is a graph showing the relationship between room temperature electron mobility and sheet resistance of the strained InP / Ga _0.47 In _0.53 As heterojunction material according to the present invention. The strain was added to the InP layer by adjusting the cooling rate after the growth of the heterojunction material. The region where strain exists is about 25 nm in distance from the heterojunction interface according to the CAT method. The figure also shows the room temperature electron mobility of a similar heterojunction wafer having no conventional strain. Comparing in the range of about 100 to about 2000 Ω / □, which is a sheet resistance of a normal practical heterojunction material for Hall elements, the electron mobility of the wafer according to the present invention is higher than the conventional electron mobility. There is. For example, about 10
With a sheet resistance of 00Ω / □, the room temperature electron mobility of the heterojunction material according to the present invention is 8,000 to 12,000c.
It is about m ² / V · s. On the other hand, in the conventional example, at most 6,0
It is about 00 cm ² / V · s.

An epitaxial wafer having a heterojunction composed of InP or Al _x In _1-x As and a Ga _x In _1-x As magnetically sensitive portion grown on an InP single crystal substrate is used as a base material, and a GaInAs hole is used. Fabricate the element. It is I to form a heterojunction with Ga _x In _1-x As.
Since the manufacturing method of the GaInAs Hall element is not largely different depending on whether it is nP or Al _x In _1-x As, here, a GaInAs Hall element composed of a heterojunction of Ga _x In _1-x As and InP is manufactured. Add an explanation by giving an example. First, a well-known processing technique such as photolithography technique and etching technique is used, and a Ga _x In _1-x As magnetically sensitive layer and InP exhibiting a function as a Hall element.
So-called mesa etching is performed on the buffer layer to process the element functional region into a mesa shape. At the time of this mesa processing, two semiconductor mesa layers intersecting each other in a cross shape are provided parallel to the <0 bar 11> and <0 bar 1 bar 1> directions orthogonal to each other. Here, the method of obtaining the mesa structure will be described here. First, Ga, which is the outermost surface of the base material, is added.
_A general photoresist material is applied to the surface of the _x In _1-x As magnetically sensitive portion layer, and then the photoresist material is formed only on the areas where the magnetically sensitive portion and the input and output electrodes are formed by a normal photolithography technique. Let it remain. The resist material existing in the other regions is peeled and removed. Thereafter, the Ga _x In _{1- x} As magnetically sensitive portion layer is etched with an inorganic acid. The Ga _x In _1-x As layer in the region where the photoresist material is removed by this etching is Ga
It is exposed to an inorganic acid that has an etching action on InAs. Ga _x In _1-x As in the region is selectively removed, and only the magnetically sensitive portion and the electrode formation region remain in a mesa shape.

Further, etching is advanced to make this Ga _x I
A portion of the InP buffer layer immediately below the n _1-x As magnetically sensitive portion layer is selectively removed by etching. By this etching, the vertical cross section of the electrode formation portion and the magnetically sensitive portion region is <0 bar 11> when viewed from the directions of crystal axes of <0 bar 11> and <0 bar 1 bar 1> which are orthogonal to each other. The cross section in the direction is trapezoidal, that is, a so-called forward mesa cross section, and conversely, in the <0 bar 1 bar 1> crystal axis direction, a reverse trapezoidal so-called reverse 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 magnetically sensitive portion region. However, regarding the mesa etching, when the total thickness of the growth layer exceeds 5 μm, the difference in etching shape based on the crystal axis (crystal orientation) becomes remarkable as described above. As a result, the unbalance voltage, which is one of the characteristics of the Hall element, is increased, and the unbalance rate is deteriorated. Therefore, as described above, the total film thickness of the epitaxial growth layer used for manufacturing the Hall element is set to approximately 5 μm or less by mainly adjusting the layer thickness of InP or Al _x I _1-x nAs. It is more convenient. After performing such mesa etching, input and output electrodes are formed. In this formation, a general 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 / output electrodes are formed is peeled and removed. _x In _1-x A
The surface layer of the s layer is exposed.

Next, a gold (Au) / germanium (Ge) alloy used as an electrode material is vacuum-deposited on the processed resist material. Although the Au.Ge alloy is used as the electrode material here, the electrode material is not particularly limited thereto, and a material that can obtain an ohmic electrode with respect to 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 formed into a known plasma C.
The surface of the wafer is coated by the VD method. Although a silicon dioxide film is used here as the coating film, another insulating film, for example, silicon nitride (SiN) may be used.

The silicon dioxide insulating film produced as described above was covered with a general resist material. After that, the resist material in a portion corresponding to a position for forming a dicing line necessary for so-called dicing, which is separated into an electrode portion and individual elements, is removed by a known photolithography technique, and SiO ₂ directly below is formed. The insulating film was exposed. Further, the exposed SiO ₂ insulating film is immersed in hydrofluoric acid (HF),
The portion of the SiO ₂ insulating film was dissolved and removed. As a result, the surfaces of the input / output electrodes and the surface of the Ga _x In _1-x As layer are exposed at the dicing line forming portion. In actual separation into individual elements, the Ga _x In _1-x As layer exposed at the portion corresponding to the dicing line may be removed by etching using a suitable inorganic acid. After that, the InP layer immediately below the Ga _x In _1-x As 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. The reason for this is to reduce in advance the mechanical damage to the epitaxial growth layer and the hetero interface when the element is separated by the scriber or blade used for dicing.

After performing such processing, the electrical characteristics of the GaInAs Hall element are evaluated. The characteristics of a GaInAs Hall element having a conventional heterojunction structure are also evaluated in parallel. Here, the conventional Hall element is an element composed of a heterojunction system in which a strained layer exists in a thick region because the cooling rate after epitaxial growth is set to be extremely high although strain exists in InP. Say The result of the comparison is shown in FIG. 4 as the difference in the distribution of electron mobility in the device state. As is clear from the figure, the GaI according to the present invention is
In the nAs Hall element, the average electron mobility is higher than that in the conventional example.

[0030]

By regulating the carrier concentration and layer thickness of the magnetosensitive layer as in the present invention, it has a function of imparting high electron mobility to the GaInAs heterojunction Hall element material.

[0031]

EXAMPLES The present invention will be described in detail based on examples. Figure 1
FIG. 3 is a schematic plan view of a Hall element using Ga _x In _1-x As as a magnetically sensitive portion according to the present invention. 2 is a schematic view of a vertical cross section along the direction of the broken line AA ′ in the schematic plan view shown in FIG. In forming the epitaxial wafer including the heterojunction described in the present text, iron (F
The semi-insulating high-resistance InP single crystal substrate (10) having a plane orientation (100) and a specific resistance of about 10 ⁶ Ω · cm added with e).
1) Undoped InP used as a buffer layer as the first layer
Layer (102) was grown to a thickness of about 100 nm. The carrier concentration of the InP layer (102) is changed to the hole (Hal
l) The result of measurement by the effect method was about 2 × 10 ¹⁵ cm ⁻³ .

After that, undoped n-type Ga _0.47 In _0.53 As (103) having a carrier concentration of 2 × 10 ¹⁶ cm ^-3 and a composition ratio of 0.47 is formed on the InP buffer layer (102) with a thickness of 250 nm. Deposited to thickness. Next, Ga _x In _1-x A
s The magnetic sensitive layer (103) is entirely covered with a normal organic photoresist material, and then the well-known photolithography technology and etching technology are used to form the area where the input / output electrodes are to be formed and the magnetic sensitive section. The region (104) was processed into a mesa shape. In this example, an inorganic acid was used for the mesa etching process.

After that, a Ga _x In _1-x As layer (103) is formed.
The entire surface of the above was coated again with the organic resist material. Next, a pair of input electrode (105) and output electrode (1
06) is removed by using a known photolithography technique to remove only the resist material existing in the region where
The surface of the a _x In _1-x As 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, it is not necessary to manufacture an element deposited on the resist material by vapor deposition.
The alloy film was removed by the so-called lift-off method. Next, the wafer on which the alloy film serving as the electrode was adhered was heat-treated (alloyed) at a temperature of 420 ° C. for several minutes to obtain an ohmic electrode.

Further, a pad electrode (107) is provided on each electrode in electrical connection with the input / output electrodes (105 and 106). The pad electrode (107) was placed on the surface layer portion of the InP single crystal substrate (101) exposed by mesa etching as described above. This is to prevent the strain from being directly introduced into the Ga _x In _1-x As magnetically sensitive layer during alloying. Next, the surface of the heterojunction material that has undergone the above steps was covered by a plasma CVD method with a silicon dioxide film (108) in the regions other than the above-mentioned input / output electrode portions. The deposited film thickness of the oxide film is about 400 n.
m. Further, the entire surface of the element was covered again with a general photoresist material, and patterning was performed so as to form a dicing line (109) for separating the Hall element formed on the entire surface of the wafer into individual Hall element chips. . After that, in the portion corresponding to the dicing line (109), the oxide film (108) and Ga _x immediately below are present.
In _1-x As magnetic sensitive section crystal layer (103), and In
The P buffer layer (102) was sequentially removed by etching. Further, the etching is advanced, and the InP single crystal substrate (1
The constituent material was removed to reach the surface layer portion of 01) to form a dicing line (109).

After that, the electrical characteristics, especially the product sensitivity, of the new Hall element thus manufactured were compared with those of the conventional GaInAs Hall element. The conventional Hall element referred to here is the same Ga _0.47 In _0.53 A as described in the above embodiment.
s A Hall element made of a heterojunction material in which the heterojunction is composed of the magnetically sensitive portion and the InP buffer layer, but the strain region existing in the InP layer is beyond the scope of the present invention. Incidentally, the existing region of strain in the conventional Hall element exceeds about 60 nm in distance from the hetero interface. Comparing the case of the present invention and the conventional example with the average room temperature mobility after the Hall element is formed, the average mobility of the conventional example is about 6,100 cm ² / V · s. On the other hand, in the Hall element according to the present invention, a significant difference of about 9,400 cm ² / V · s was recognized. This significant difference has almost the same numerical value as the above-described conventional Hall element having no distortion.

[0036]

EFFECT OF THE INVENTION With a simple and new method of providing strain within a specific region within a compound semiconductor layer forming a heterojunction with Ga _x In _1-x As forming a magnetically sensitive portion, a high sensitivity can be obtained. It has an effect of providing a stable supply of the GaInAs Hall element.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a plane of a GaInAs heterojunction Hall element according to the present invention.

FIG. 2 is a schematic diagram of a vertical cross section taken along line AA ′ of the Hall element shown in FIG.

FIG. 3 is a diagram showing a relationship between room temperature electron mobility and sheet resistance.

FIG. 4 is a diagram showing a distribution of electron mobility.

FIG. 5 is a schematic diagram showing the relationship between the GaInAs film thickness and the depletion layer (when the film thickness exceeds the depletion layer region at zero bias).

FIG. 6 is a diagram showing the relationship between the GaInAs film thickness and the depletion layer (when the film thickness is equal to or less than the depletion layer region at zero bias).

FIG. 7 is a schematic diagram showing an example of imaging a strained layer by a CAT method.

[Explanation of symbols]

(101) Fe-added high-resistance InP single crystal substrate (102) Strained InP crystal layer (103) Ga _0.47 In _0.53 As magnetically sensitive layer (104) Mesa region (105) Input electrode (106) Output electrode (107) Pad Electrode (108) Oxide film (109) Dicing line (201) Depletion layer (201-1) Depletion layer tip (202) Heterojunction interface (203) Electron (301) Fringe

Continuation of the front page (56) Reference JP-A-5-218528 (JP, A) JP-A-4-106988 (JP, A) JP-A 64-2384 (JP, A) JP-A-7-79032 (JP , A) JP-A-5-275767 (JP, A) JP-A-60-198877 (JP, A) JP-A-54-114089 (JP, A) International Publication 93/2479 (WO, A1) IEICE News, No. No. 511, pp. 6-10 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 43/06 H01L 43/14 JISST file (JOIS)

Claims (7)

(57) [Claims] 1. A buffer layer made of indium phosphide (InP) and having a carrier concentration of 1 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁷ or more.
cm ⁻³ or less and a gallium arsenide / indium mixed crystal (Ga _X In _1-X As: 0.37 ≦ X ≦ 0.57) having a layer thickness equal to or less than the thickness of the depletion layer corresponding to the above carrier concentration. In a Hall element comprising a heterojunction with a magnetosensitive layer consisting of, the buffer layer has a magnetic layer in the region within 50 nm from the heterojunction interface with the magnetic layer. A Hall element in which a strained layer is introduced by adjusting a cooling rate in a cooling step after being provided by joining. 2. An aluminum arsenide / indium mixed crystal (Al
InAs) buffer layer and carrier concentration 1 × 10
^A gallium arsenide / indium mixed crystal (Ga _X In _1-X As: 0) having a thickness of ¹⁵ cm ^-3 or more and 5 × 10 ¹⁷ cm ^-3 or less and a thickness of the depletion layer corresponding to the above carrier concentration or less. ．
In a Hall element comprising a heterojunction with a magnetosensitive layer consisting of 37 ≦ X ≦ 0.57), the buffer layer is in a region within 50 nm from the heterojunction interface with the magnetosensitive layer. A Hall element, wherein a strained layer is introduced by adjusting a cooling rate in a cooling step after the magnetically sensitive layer is bonded to the buffer layer and provided. 3. A buffer layer made of indium phosphide (InP) and having a carrier concentration of 1 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁷ or more.
cm ⁻³ or less and a gallium arsenide / indium mixed crystal (Ga _X In _1-X As: 0.37 ≦ X ≦ 0.57) having a layer thickness equal to or less than the thickness of the depletion layer corresponding to the above carrier concentration. In a Hall element including a magnetic sensitive layer made of Ga _x I having a composition different from that of the magnetic sensitive layer between the buffer layer and the magnetic sensitive layer.
By disposing the n _{1 -X} As mixed crystal layer so as to be interposed, the buffer layer forms the strained layer in a region within 50 nm from the bonding interface with the intervening Ga _X In _{1 -X} As mixed crystal layer. Hall element that has been introduced. 4. An aluminum arsenide / indium mixed crystal (Al
InAs) buffer layer and carrier concentration 1 × 10
^A gallium arsenide / indium mixed crystal (Ga _X In _1-X As: 0) having a thickness of ¹⁵ cm ^-3 or more and 5 × 10 ¹⁷ cm ^-3 or less and a thickness of the depletion layer corresponding to the above carrier concentration or less. ．
37 <X <0.57) in a Hall element, wherein a Ga _X In _{1 -X} As mixed crystal having a composition different from that of the magnetic sensitive layer is provided between the buffer layer and the magnetic sensitive layer. Since the buffer layer is provided with the layer interposed, the strained layer is introduced in a region within 50 nm in distance from the bonding interface with the intervening Ga _x In _1-x As mixed crystal layer. Hall element. 5. A Ga _x In _{1 -X} As mixed crystal layer having a composition different from that of the magnetic sensing layer, which is provided between the buffer layer and the magnetic sensing layer, has a layer thickness of 10 n.
The hall element according to claim 3 or 4, wherein the hall element has a thickness of m or less. 6. A buffer layer made of indium phosphide (InP) or aluminum arsenide / indium mixed crystal (AlInAs) and having a carrier concentration of 1 × 10 ¹⁵ cm ⁻³ or more and 5 × 1.
0 ¹⁷ cm ^-3 or less, and the layer thickness of the gallium arsenide indium mixed crystal with less thickness of the depletion layer corresponding to the above-mentioned carrier concentration _{(Ga X In 1-X As} : 0.37 ≦ X ≦ 0. 5
In a method of manufacturing a Hall element having a heterojunction with a magnetosensitive layer consisting of 7), a Ga _X In _{1 -X} As magnetosensitive layer is heterojunctioned with a buffer layer, and then a cooling step is performed. A method of manufacturing a Hall element, comprising forming a strained layer in a region of 50 nm or less in distance from the heterojunction interface inside the buffer layer at a cooling rate of 20 ° C./min. 7. The method of manufacturing a hall element according to claim 6, wherein the cooling rate when cooling from 600 ° C. to 200 ° C. is 20 ° C./min.