JPH02239186A - Method and device for vapor growth - Google Patents

Abstract

PURPOSE:To obtain many sheets of thin films having large area in the excellent composition ratio and surface state by holding a mercury reservoir with a shaft vertically hung in a vertical reaction tube specifying the position for supplying the organic metallic compd. of a raw material and rotating a base plate in the case of growing the thin films of mercury-contg. compd. single crystal. CONSTITUTION:In the case of growing a CdxHg1-x Te single crystal thin film, Me2Cd and Et2Te sent from the bubblers 1, 2 are diluted by H2 and introduced into the vertical reaction tube 11 through the nozzles 9, 10. Mercury vapor is generated by heating a mercury reservoir 12 which is held with the shaft vertically hung from the upper wall surface of the reaction tube 11 and arranged to the central part in the reaction tube 11. In this case, at least Me2Cd decomposable at low temp. is supplied through the nozzle 9 opened to the part lower than the mercury reservoir 12. A base plate 16 controlled at prescribed temp. is arranged to the part lower than this aperture. This base plate 16 is rotated for the center axis of the reaction tube 11 by a rotating shaft 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for vapor phase growth of a thin film of a compound containing mercury. Specifically, the present invention relates to a method and apparatus for forming a large area single crystal thin film of a compound containing mercury by metal organic vapor phase epitaxy.

(Prior art) Metal-organic pyrolysis vapor phase growth method (Metal.
anicC hemfcal V apor D e
posit1on: Hereinafter referred to as MOCVD method. )
In recent years, it has become an important technology for producing high-performance semiconductor devices because it combines mass production with controllability of the thickness and composition ratio of the crystal growth layer.

Mercury cadmium telluride (Cd-
ag. -, Te: Hereinafter referred to as CMT. ) Regarding thin film growth, for example, Journal of Crystal Research, Vol. 55 ( ]. 981), pp. 107-
1] page 5 (Journal of CrystalG
rowth. vol. 55 (1981), pl0
7-115). In this technology,
As shown in Figure 5, the thin film is grown in a horizontal reaction tube 3 made of quartz.
It is carried out at normal pressure within 0. Raw materials include dimethyl cadmium (Me2Cd), diethyl tellurium (Et2”r)
e) and metallic mercury (Hg) are used.

Me2Cd and Et2Te, which are organic metals (MO), are introduced into the reaction tube 30 from a raw material gas inlet 31 provided at one side end of the reaction tube 30 using hydrogen gas as a carrier gas.
be introduced within. Further, Hg is supplied from a mercury reservoir 32 placed on the bottom wall of the reaction tube 30. Reaction tube 30
A carbon susceptor 33 having a streamlined shape is arranged on the bottom wall surface near the other side end, and a CdTe substrate 34 is placed on this carbon susceptor 33. The MO gas introduced into the reaction tube 30 is thermally decomposed near the carbon susceptor 34 heated by the high frequency coil 35, while Hg vapor is supplied from the mercury reservoir 32, so that the MO gas is placed on the susceptor 33. CdTe substrate 34
A CMT crystal grows on the surface. Typical board temperature is 42
It is around 0°C. The composition ratio (X) of the thin film is controlled by the temperature of the mercury reservoir 32, and the temperature range is from 240°C to 320°C.
It is °C. The reaction tube 30 is heated from the outside with a resistance heater 36 so that mercury vapor does not condense on the wall of the reaction tube 30.

The mercury cadmium telluride obtained in this way has excellent sensitivity and responsiveness to infrared rays, making it a promising material for infrared sensing elements. However, as a two-dimensional array type infrared sensing element, it is difficult to It is desired to simultaneously grow multiple crystals at the same time.

However, in the apparatus configuration described above, since the horizontal reaction tube 30 is used as the reaction tube, the surface of the substrate 34 is placed in the flow direction of the raw material gas, and when the area becomes large, the in-plane composition of the grown thin film becomes The variation in the ratio and the non-uniformity of the film thickness increased. In addition, when using a human area board of 1 inch or more, 1 inch or more can be processed simultaneously.
It was 1 piece.

By the way, the vapor pressure of mercury in the composition of mercury cadmium telluride is extremely high, so if the growth temperature becomes high,
There is a problem in that a large amount of mercury vacancies are generated in the crystal, causing a deviation from the intended composition ratio (X). Surf S Science, Volume 104 (1981), No. 365
Pages ~ 383 (Surface Sc1ence)
vol. 104 (1981), p865-383
), the composition ratio is 0.2, that is, Cdo,2Hg
It has been reported that when o8Te is heated to 150° C. or higher, evaporation of mercury from the CMT crystal is observed.

Furthermore, in the MOCVD method, the crystal growth temperature mainly depends on the thermal decomposition temperature of the raw material gas. The thermal decomposition temperatures of Et2Te and Me2Cd are 400-500°C and 200°C, respectively.
~300°C. Therefore, the growth temperature of CMT crystal is
A temperature of 400° C. or higher, which is the thermal decomposition temperature of Et2Te, is required.

In this way, the CMT thin film growth temperature is 400°C or higher,
and the composition ratio X is 0. Hg as in the case of 2-0.3
When the composition is large, it is necessary to keep the mercury vapor pressure near the substrate 34 high in order to suppress Hg evaporation from the grown film.
In reality, the temperature of the mercury reservoir 31 is 300° C. or higher. Furthermore, the tube wall of the reaction tube 30 from the mercury reservoir 31 to the vicinity of the substrate 34 also needs to be heated to 300° C. or higher to prevent metal Hg from condensing. High temperature parts (mercury reservoir 31 at 300°C or higher, reaction tube 3
The following problem arises due to the existence of a tube wall of 0.

That is, since the thermal decomposition temperature of Me2Cd is 200° C. or higher, it thermally decomposes during the process and reacts with Hg vapor in the gas phase. For this reason, Hg-Cd nuclei generated by reaction in the gas phase fall and adhere to the substrate 34, resulting in a poor growth surface.

Furthermore, in the configuration shown in FIG.
A mercury reservoir 32 exists between the raw material gas inlet 31 of No. Since the mercury reservoir 32 is obstructive, the problem arises that the composition of the CMT crystal grown on the substrate 34 becomes non-uniform.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide an improved vapor phase growth method and apparatus.

Another object of the present invention is to provide a vapor phase growth method and apparatus suitable for producing a large number of large-area single-crystal thin films. A further object of the present invention is to provide a vapor phase growth method and apparatus for forming a large-area compound single crystal thin film containing mercury with high composition ratio controllability and good surface condition. The present invention further provides a large area C
The object of the present invention is to provide a vapor phase growth method and apparatus for forming a d-1{g-Te single crystal thin film with high composition ratio controllability and good surface condition.

(Means for Solving the Problems) The above objects are achieved by using a vertical reaction tube as a reaction tube in a method for growing a compound single crystal thin film containing Hg by organometallic vapor phase epitaxy. A mercury reservoir held by a shaft hanging from the wall and placed inside the reaction tube is heated to a predetermined temperature to generate mercury vapor inside the reaction tube, while the mercury vapor is entrained in the carrier gas from the raw material gas introduction system. Among the metal-organic compounds introduced into the reaction tube, at least the low-temperature decomposable metal-organic compound is supplied from a nozzle that opens below the mercury reservoir, and the mercury reservoir and A method for vapor phase growth of a single crystal thin film of a compound containing mercury, characterized by placing a substrate whose temperature is controlled to a predetermined temperature below a nozzle opening, and further rotating this substrate about the central axis of a vertical reaction tube. This is achieved by

The present invention also provides cd-Hg by organometallic vapor phase epitaxy.
- In a method for growing a Te-based single crystal thin film, a vertical reaction tube is used as the reaction tube, and a mercury reservoir, which is held by a shaft hanging from the upper wall of the reaction tube and placed in the interior space of the reaction tube, is placed in a predetermined position. Mercury vapor is generated in the reaction tube by heating to a high temperature, while a tellurium organic compound supply nozzle is inserted from the top of the reaction tube and opens into the reaction tube, and a tellurium organic compound supply nozzle is inserted from the top of the reaction tube and opens into the reaction tube. A predetermined amount of a tellurium organic compound and a cadmium organic compound are introduced into the reaction tube, each accompanied by a carrier gas, through a cadmium organic compound supply nozzle that opens at a position below the mercury reservoir, and the cadmium organic compound is introduced into the reaction tube through the mercury reservoir and the nozzle. A Cd-Hg-Te method characterized in that a substrate whose temperature is controlled to a predetermined temperature is placed below the opening, and the substrate is further rotated about the central axis of the vertical reaction tube.
This figure shows a method for vapor phase growth of single crystal thin films. The present invention further provides mercury cadmium telluride (Cd.Hg, -x
Te) This shows a vapor phase growth method for growing a single crystal thin film. The present invention further provides a method for controlling the temperature of the mercury reservoir and the source gas supply system to produce a compound semiconductor that does not contain mercury, such as a single crystal thin film of cadmium telluride (CdTe), and a compound semiconductor that contains mercury, such as mercury telluride (HgTe). )
This shows a vapor phase growth method in which single crystal thin films are grown alternately.

The above objects also provide a vapor phase growth apparatus for growing a compound single crystal thin film containing mercury, in which a mercury reservoir is held in a vertical reaction tube by a shaft hanging from the upper wall of the vertical reaction tube. one or more metal-organic compound supply nozzles are inserted through the upper wall surface of the vertical reaction tube, and at least the low-temperature decomposable metal-organic compound supply nozzle is positioned below the mercury reservoir; Each vertical reaction tube has an opening, and a vertical susceptor for mounting a substrate equipped with a rotation mechanism that rotates about the central axis of the vertical reaction tube is placed below the mercury reservoir and nozzle opening in the vertical reaction tube. A vapor phase of a single crystal thin film of a mercury-containing compound, characterized in that it is supported from the lower side of a reaction tube, and an exhaust system for exhausting the inside of the vertical reaction tube is connected to the lower side of the vertical reaction tube. It can also be achieved by a growth device.

The present invention also provides a vapor phase growth apparatus in which the nozzle for supplying a low-temperature decomposable metal organic compound also serves as a shaft for holding a mercury reservoir. The present invention further provides a vapor phase growth apparatus for growing a Cd-Hg-Te single crystal thin film, which comprises holding a mercury reservoir in a vertical reaction tube by a shaft hanging from an upper wall surface of the vertical reaction tube. A tellurium organic compound supply nozzle and a cadmium organic compound supply nozzle are inserted through the upper wall of the vertical reaction tube, and at least the cadmium organic compound supply nozzle is positioned below the mercury reservoir. The mercury reservoir and nozzle openings are respectively opened in the vertical reaction tube, and a substrate is installed below the mercury reservoir and nozzle openings in the vertical reaction tube, and is equipped with a rotating machine that rotates about the central axis of the vertical reaction tube. A susceptor for Cd-Hg-Te is disposed to be supported from the lower side of the vertical reaction tube, and an exhaust system for exhausting the inside of the vertical reaction tube is connected to the lower side of the vertical reaction tube. This figure shows a vapor phase growth apparatus for single-crystal thin films. The present invention further provides a vapor phase growth apparatus in which the nozzle for supplying a cadmium organic compound also serves as a shaft for holding a mercury reservoir.

(Function) When producing a single crystal thin film of a mercury-containing compound such as CMT, if you want to increase the area of the single crystal thin film, use a vertical reaction tube and place the substrate in the radial direction of the tube. It is conceivable to place However, in this case, the problem is how to arrange the mercury reservoir within the reaction tube.

However, in the present invention, this mercury is held by a shaft hanging from the upper wall of the vertical reaction tube, and is placed in the center of the reaction tube, so that the entire surface of the substrate located below this is held. It is possible to supply uniform mercury vapor to the

Furthermore, in the reaction apparatus of the present invention, at least one of the nozzles for supplying a low-temperature decomposable metal-organic compound (for example, Cd -Hg-Te
In the vapor phase growth apparatus for single-crystal thin films, at least the cadmium organic compound supply nozzle (among the tellurium organic compound supply nozzle and the cadmium organic compound supply nozzle) is located below the mercury reservoir. It is open at the position. Therefore, source gases such as low-temperature decomposable metal-organic compounds (such as cadmium organic compounds) are not exposed to the high-temperature region (mercury reservoir and reaction tube wall) that exists up to the substrate surface. Therefore, low-temperature decomposable metal-organic compounds such as cadmium organic compounds are thermally decomposed during the process, react with mercury vapor in the gas phase to form nuclei, and these nuclei fall to the substrate surface and form the surface of the growing thin film. Problems such as deterioration of properties or poor yield of raw material gas do not occur.

Furthermore, in the reaction apparatus of the present invention, a susceptor for installing a substrate, which is equipped with a rotation mechanism that rotates about the central axis of the vertical reaction tube, is placed below the mercury reservoir and the nozzle opening on the lower side of the vertical reaction tube. Since the substrate is supported from above, the substrate placed on the susceptor can be rotated in the plane direction during the growth reaction. For this reason, the MO gas (organic tellurium compound gas and cadmium organic compound gas) introduced into the horizontal reaction tube is located in a concentration distribution near the substrate due to the presence of a mercury reservoir or uneven opening position of each nozzle. Even if non-uniformity occurs, since each coordinate point on the substrate surface is displaced by rotation, the variation in the composition ratio within the plane is reduced, and the uniformity of the composition ratio within the plane of the growing crystal is good. . Further, by using a conical susceptor as the susceptor and placing the substrates on the side surface that serves as the substrate installation surface, it is possible to grow a large number of substrates at the same time.

Hereinafter, the present invention will be explained in more detail based on embodiments.

FIG. 1 shows an embodiment of the vapor phase growth apparatus of the present invention.
FIG. 1 is a schematic diagram showing the configuration of a -Hg-Te based single crystal thin film vapor phase growth apparatus.

That is, in the embodiment shown in FIG. 1, the raw materials Me2Cd as an organic compound of cadmium and Et2Te as an organic compound of tellurium are each placed in a stainless steel bubbler 1.2, and a constant temperature bath 3,
It is placed in 4.

In addition, as an organic compound of cadmium, M e 2C
In place of d, other alkylated cadmiums such as diethyl cadmium, dipropyl cadmium, dibutyl cadmium, diisobutyl cadmium, diisoamyl cadmium, etc. can be used, and as the organic compound of tellurium, in place of Et2Te, dimethyl tellurium, diisobutyl cadmium, diisobutyl cadmium, It is also possible to use other alkylated telluriums such as di-tert-butyl tellurium, alkenylated telluriums such as diallyl tellurium and dimethylallyl tellurium, or 2,5-dihydro-tellurophenes. The insides of bubblers 1 and 2 are saturated with appropriate vapor pressure, and the vapor pressure is
, 4. Figure 2 shows Me2Cd and Et2T.
The vapor pressure curve of e is shown.

As a result, for example, the temperature of thermostats 3 and 4 can be set to 30°C.
, if the temperature is set to 40℃, the vapor pressure is 28mm for Me2Cd.
Hg, Et2 Te becomes 18 mmHg. In addition, Me
The temperature of the constant temperature bath 3 for 2Cd is 0 to 60°C, more preferably about 25 to 35°C, and the temperature of the constant temperature bath 4 for Et2Te is 10 to 60°C, more preferably 25°C.
A temperature of about 40°C is appropriate.

The amount of raw material gas introduced into the reaction tube 11 is bubbler 1.2.
The H2 gas flow rate sent to the MO gas, that is, the mass flow controller (MFC) 5.6, and the H2 gas flow rate that dilutes these MO gases, respectively, are determined by the MFCs 7 and 8.

The tips of the Me2Cd gas supply line and the Et2Te gas supply line serve as nozzles 9 and 10, respectively, which are inserted through the upper wall surface of the vertical reaction tube 11 and extended into the vertical reaction tube 1. Of these, the Et2Te gas supply nozzle 10 opens near the upper wall surface through which it is inserted, while the Me2Cd gas supply nozzle 9
extends considerably downward in the vertical reaction tube 11, and near the upper part of the surface of the substrate 16 placed on the carbon susceptor 17 for substrate installation, which will be described later, specifically, for example, 5 to 1.
The opening is about 00 mm above, more preferably about 10 to 30 mm above. Note that if the tip opening of the Me2Cd gas supply nozzle 9 is closer to the surface of the substrate 16 than 5 mm, there is a high possibility that the supply of Me2Cd gas to the substrate 16 will be uneven; If it is further away, there is a higher possibility that Cd produced by thermal decomposition will react with Hg in the gas phase.

In this embodiment, the Me2Cd gas supply nozzle 9 also serves as a support shaft for the mercury reservoir 12. That is, the mercury reservoir 12 is shaped like a cylindrical container with an open upper end, and the Me2Cd gas supply nozzle 9 is inserted into the insertion hole 13 provided at the center of the bottom surface of the mercury reservoir 12. It is fixed to the nozzle 9 by joining the outer circumferential surface of the nozzle 9 and the inner circumferential surface of the insertion hole 13 slightly above the tip opening of the nozzle 9 . Note that since the Me2Cd gas supply nozzle 9 is arranged so that the vicinity of its tip opening passes through the mercury reservoir 12 in this way, at least the vicinity of this tip opening has a double pipe structure for heat insulation. It is said that

In this embodiment, the bottom surface of the mercury reservoir 12 is mesh-shaped, and the mercury reservoir 12 can generate mercury vapor from both the upper opening and the mesh-like bottom surface. The mesh body constituting the bottom of the mercury reservoir 12 is not particularly limited as long as it has a mesh size that does not allow liquid mercury to leak;
Mesh bodies such as stainless steel with mesh size of 0.3 m or less, nickel or nickel-coated stainless steel are used. The mesh-shaped bottom surface of this mercury reservoir 12, that is, the surface where mercury vapor is generated, is located near the top of the surface of a substrate 16 placed on a carbon susceptor 17 for substrate installation, which will be described later, and at the tip opening of the nozzle 9. Specifically, although it depends on the position of the opening of the tip of the nozzle 9, for example, it is located 10 degrees above the surface of the substrate 16.
The distance is about 120 rpm, more preferably about 30 to 50 mm, and 20 mm or more above the tip opening of the nozzle 9. That is, if the mesh-shaped bottom surface of the mercury reservoir 12 is closer than 1Qmm to the substrate 16, there is a high possibility that raw materials such as Hg vapor or Et2Te gas will be supplied unevenly; If the distance is more than 12 Qmm to 16, the substrate 1
There is a high possibility that sufficient vapor pressure will not be obtained near 6.

Furthermore, if the mesh-like bottom surface of the mercury reservoir 12 is closer than 20 mm to the tip opening of the nozzle 9, the reaction between Cd and Hg in the gas phase cannot be controlled.

However, as in this embodiment, the mercury reservoir 1
It is not always necessary to make the bottom surface of the mercury reservoir 12 mesh-like so that mercury vapor can be generated from the bottom surface, but instead the mercury reservoir 12 is configured such that mercury vapor can only be generated from the upper opening. However, it is still usable.

A coil heater 14 for heating the mercury reservoir is wound around the outer peripheral surface of the mercury reservoir 12, and a thermal lightning pair for monitoring the temperature of the mercury reservoir 12 is provided inside the mercury reservoir 12.

On the other hand, directly below this mercury reservoir 12, a vertical type reaction system is installed so that a substrate 16 can be placed at a predetermined distance from the bottom of the mercury reservoir 12 or the tip opening of the Me2Cd nozzle 9. A disk-shaped carbon susceptor 17 for mounting a substrate is disposed in the radial direction of the tube 11 and has a substrate mounting surface. This carbon zaceptor 17 for installing a substrate has a rotating shaft 1 of a rotary motor 19 extending from the outside of the vertical reaction tube 11 through the lower wall surface of the reaction tube 11 and into the reaction tube 11.
8, it is supported from the lower end surface side.

Note that an airtight means such as a mechanical seal is provided at a portion where the rotating shaft 18 penetrates the wall of the vertical reaction tube 11.

Therefore, the substrate 16 held on the carbon susceptor 17 is rotated in the plane direction by the rotation motor 19 at a rate of, for example, 60 times/minute or less, preferably 5 to 60 times/minute. If this rotation is extremely slow, e.g. 0.2 times/min, carbon may grow on the surface of the substrate 16.
If the uniformity of the composition ratio of the MT-based crystal does not improve, and on the other hand, the rotation is extremely fast, for example, 100 times/min, there is a greater possibility that various problems will occur in the device mechanism. Neither is preferable. In the vapor phase growth method of the present invention, the substrate 16 does not necessarily need to be rotated in a fixed direction, but may be reversed at predetermined intervals or at predetermined rotation angles. Furthermore, the drive system for the susceptor 17 is not limited to one using a rotary motor.

The substrate 16 is CdT with crystal orientation (1 1 1).
e substrate can be mentioned as one of the preferred ones, but other plane orientations, such as the (100) plane, as well as, for example, the G
aAs, Si. ．． Other substrate materials such as InSb, A1203 may also be used.

An RF coil 20 for substrate heating is wound around the outer peripheral surface of the vertical reaction tube 11 near the height position where the carbon susceptor 17 is arranged.
7 includes a thermocouple 2 for monitoring the temperature of the substrate 12.
1 is embedded.

Note that resistance heater heating, lamp heating, etc. can also be used as the substrate heating mechanism.

Further, the outer circumferential surface of the vertical reaction tube 11 has at least an area above the height where the carbon susceptor 17 is arranged.
It is covered with a heater 22 for heating the tube wall. Therefore, when the mercury reservoir 12 is heated to generate mercury vapor, the tube wall heating heater 22 is activated to heat the tube wall to a predetermined set value, thereby increasing the amount of Hg on the inner wall surface of the reaction tube 11. Can prevent condensation.

Further, in order to allow crystal growth to occur at a predetermined pressure inside the vertical reaction tube 11, the vertical reaction tube 11 is equipped with an exhaust control device 23 consisting of, for example, a rotary pump and an automatic conductance valve that adjusts the displacement. , are connected in the lower region of the vertical reaction tube 11 (at least in the region lower than the position where the susceptor 17 exists). Further, the vertical reaction tube 11 is provided with a high vacuum evacuation device 24 made of, for example, a turbo pump for evacuating the inside of the vertical reaction tube 11 to a high vacuum.
An exhaust gas treatment device 25 for treating the exhaust gas after the reaction is connected in the same lower region 6.

CMT (C d = H g 1-T
e) To grow a single crystal thin film, for example, the following procedure is performed.

First, M which is the raw material gas sent out from bubblers 1 and 2
e2Cd and Et2Te are diluted with H2 gas to an appropriate concentration and fed into the vertical reaction tube 11 through nozzles 9 and 10. For example, MFC7 and 8 are each 2.5. l2/min, 2.51/min, temperature of constant temperature baths 3 and 4 is 30° each
0140°C, and MFC5.6 is set to 10 ml/min and 100 mlZ min, respectively, the M in the vertical reaction tube 11
The concentrations of e2Cd and Et2Te are 4X10-6, respectively.
mo1/ρ, 7×1 0' m o 1 /Ω. Note that the flow rate of H2 gas fed into the Me2Cd bubbler 1 is 1 to 500 ml/min, more preferably 10 to 1 ml/min.
About 0 0 ml/min is the Et2Te bubbler 2.
The flow rate of H2 gas sent to is 1 to 500 mlZ,
More preferably, it is about 10 to 100 ml/min, and the dilution H2 gas flow rate for each raw material gas is 0.
A suitable rate is about 1 to 20 g/min, more preferably about 1 to 101/min.

On the other hand, the vertical reaction tube 11 into which these MO gases are fed
10' by operating the exhaust control device 23.
torr to 1000 torr, more preferably 5 torr
The tube wall of the reaction tube 11 is maintained at a predetermined pressure in the range of r to 76 Qtorr, and the tube wall of the reaction tube 11 is heated to a temperature of 50 to 600 degrees Celsius, more preferably 200 degrees Celsius, by energizing the tube wall heating heater 22.
It is maintained at a predetermined set temperature in the range of ~400°C. Further, while monitoring mercury #12 with a thermocouple 15, the mercury #12 is heated with a coil heater 14 for heating a mercury reservoir.
Mercury vapor at a predetermined vapor pressure is supplied into the reaction tube 11 so that the temperature remains constant at a predetermined set temperature in the range of 500°C, more preferably 200 to 400°C.

Then, the susceptor 1 rotates at the rotational speed as described above.
The substrate 16 placed on the substrate 7 is heated by the RF coil 20 while being monitored by the thermocouple 21 to a temperature of 50 to 600 Hz.
℃, more preferably at a predetermined temperature in the range of 250 to 450℃, and Me2Cd is heated near the heated substrate 16.
Then, Et2Te is thermally decomposed to grow a CMT crystal having a predetermined composition ratio on the 16th surface of the substrate.

FIG. 3 is a schematic diagram showing the configuration of another embodiment of the vapor phase growth apparatus of the present invention.

In this vapor phase growth apparatus, the source gas supply system includes a first
Similar to that in the embodiment shown in the figure, Me2
Cd and Et2Te are in bubblers 1 and 2, respectively, and housed in thermostats 3 and 4, respectively. In addition, the amount of raw material gas introduced into the vertical reaction tube 11 is 1.2 bubblers.
The mass flow controller (MFC) 5.6 controls the flow rate of H2 gas sent to the MO gas, and the MFC 7.8 controls the flow rate of H2 gas diluting these MO gases.

The tips of these Me2Cd gas supply lines and Et2Te gas supply lines become nozzles 9'' and ICI, respectively, which are inserted through the upper wall surface of the vertical reaction tube 11 and extended into the vertical reaction tube 11. In this embodiment, both nozzles 9-, 10- are vertical reaction tubes 11
It extends to a considerably lower part of the inner surface, and is near the upper side of the surface of the substrate 16 placed on a carbon susceptor 17 for substrate installation, which will be described later, specifically, for example, from 0 to the side edge of the substrate 16.
The opening is about 100 mm, more preferably about 0 to 50 mm outward, and about 0 to 100 mm, more preferably about 0 to 50 mm above the surface of the substrate 16. Note that if the tip openings of these nozzles 910' are closer to the substrate 16 than the above range, there is a high possibility that the supply of Me2Cd gas and Et2Te gas to the substrate 16 will be uneven; If the Me2Cd gas nozzle 9' is located farther than the substrate 16, there is a high possibility that Cd generated by thermal decomposition will react with Hg in the gas phase.

In this embodiment, the support shaft 26 is suspended from the upper wall surface of the vertical reaction tube 11, passing over the center axis of the reaction tube 11, and has an open top end and a mesh-like bottom surface as described above. The cylindrical container-shaped mercury reservoir 12 is placed at a predetermined position within the reaction tube 11 by the support shaft 26 . 5. The distance between the bottom surface of this mercury reservoir 12 and the surface of the substrate 16 placed on the carbon susceptor 17 for substrate installation placed directly below is as described in the embodiment shown in FIG. Similar conditions apply.

Further, the other configurations of the vapor phase growth apparatus according to the embodiment shown in FIG. 3 are the same as those described in the embodiment shown in FIG. 1, and therefore the description thereof will be omitted. In addition, each part or part with a symbol in FIG.
In the drawings, the same reference numerals refer to the same parts or parts.

Furthermore, FIG. 4 shows another embodiment of the vapor phase growth apparatus of the present invention. In this embodiment and the embodiment shown in FIG. 1, a thermoelectric conversion element 27 for heating and cooling the mercury reservoir is installed in place of the coil heater 14 for heating the mercury reservoir installed on the outer peripheral surface of the mercury reservoir 12. A heater 2 for heating the tube wall is arranged on the outer circumferential surface of the vertical reaction tube 12 and also installed on the outer circumferential surface of the vertical reaction tube 11.
2, a coil heater 28 for heating the tube wall and a pipe 29 for cooling the tube wall are arranged as a pair on the outer peripheral surface of the vertical reaction tube 11, and a conical one is used as the carbon susceptor 17 for installing the substrate, The device has the same configuration except that the substrate 16 is disposed on the side surface thereof.

It should be noted that each part or region labeled with a reference numeral in FIG. 4 is the same as each part or region assigned the same reference numeral in FIG. 1.

In this manner, the embodiment shown in FIG. 4 is equipped with a means for forcibly changing the temperature of the mercury reservoir 12 and the tube wall of the reaction tube 11 not only in the heating direction but also in the cooling direction. For example, Hg T e / C d
When switching the reaction system, such as when mercury-containing compound single-crystal thin films and mercury-free compound single-crystal thin films are alternately grown and laminated, as in the production of T e superlattices, the degree of Hg vapor generation can be greatly influenced. Mercury reservoir 12
It is also possible to rapidly change the temperature of the wall of the reaction tube 11, and the reaction system can be quickly switched. In this embodiment, a thermoelectric conversion element was used as a device for heating and cooling the wall of the mercury reservoir 12, and a combination of a heater and a fluid pipe was used as a device for heating and cooling the wall of the reaction tube 11. Any means can be used as long as it functions in the same way as these to heat and cool the mercury reservoir 12 and the reaction tube 11 tube wall. It is possible to use a combination of paths.

In order to alternately grow CdTe thin films and HgTe thin films on the substrate 16 using a vapor phase growth apparatus having the configuration shown in FIG. 4, for example, the following procedure is performed.

First, in the CdTe thin film growth system, Hubler 1, 2
The Me2Cd and Et2Te sent out are diluted with H2 gas to an appropriate concentration and sent into the vertical reaction tube 11 through nozzles 9 and 10. For example, if MFC7 and 8 are set to 2.5ρ/min and 2.5Ω/min, respectively, the temperature of thermostats 3 and 4 are set to 30°C and 140°C, respectively, and MFC5.6 is set to 10ml/min and 100ml/min, respectively, the vertical The concentrations of Me2Cd and Et2Te in the mold reaction tube 11 are each 4X10-'mol. /ρ, 7X10-'mo
1/,Q. The flow rate of H2 gas sent to the Me2Cd bubbler 1 is 1 to 500 ml/min, more preferably about 10 to 100 ml/min, and the flow rate of H2 gas sent to the Et2Te bubbler 2 is 1 to 500 ml/min.
ml/min, more preferably about 10 to 100 ml/min, and the dilution H2 gas flow rate for each source gas is 0.1 to 20 ρ/min, more preferably 1 to 100 ml/min.
] ODZ amount is appropriate.

On the other hand, the vertical reaction tube 11 into which these MO gases are fed
The pipe wall is maintained at a predetermined set temperature in the range of 0 to 80 °C, more preferably 20 to 40 °C, by flowing a cooling medium such as water through two pipe wall cooling pipes, and further, By passing a current through the thermoelectric conversion element 27 in the cooling direction, the mercury reservoir 12 is heated to a temperature of −100 to 50° C., preferably −20° C.
It is maintained at a predetermined set temperature in the range of ~20°C. Therefore, no mercury vapor is supplied into the reaction tube 11. The inside of the reaction tube 11 is maintained at a predetermined pressure in the range of 10.degree. 3 torr to 1000 torr, more preferably 5 torr to 760 torr by operating an exhaust control device 23.

Then, the susceptor 1 rotates at the rotational speed as described above.
The substrate 16 placed on the substrate 7 is heated by the RF coil 20 while being monitored by the thermocouple 21 to a temperature of 50 to 600
℃, more preferably at a predetermined set temperature in the range of 250 to 450°C, and Me2C is heated near the heated substrate 16.
Cd and Et2Te are thermally decomposed and Cd is deposited on the 16th surface of the substrate.
Grow Te crystal.

After the formation of a CdTe thin film of a predetermined thickness is completed, the reaction apparatus is switched to a HgTe thin film growth system.

That is, if of the MFC 5.6 is set to 0, the supply of Me2Cd, Et2Te into the reaction tube 11 is stopped, and the growth of crystals on the surface of the substrate 16 is stopped.

Then, at the same time as stopping the flow of the cooling medium to the tube wall cooling pipe 29, electricity is supplied to the tube wall heating coil heater 28 to heat the tube wall of the reaction tube 11 to 50 to 600°C, more preferably 200 to 200°C. Maintain a predetermined set temperature in the range of 400°C. Furthermore, the flow of current to the thermoelectric conversion element 27 is reversed, and while being monitored by the thermocouple 15, the mercury reservoir 1
2 to 50-500℃, more preferably 200-500℃.
Mercury vapor at a predetermined vapor pressure is supplied into the reaction tube 11 so that the temperature remains constant at a predetermined set temperature in the range of 400°C. When the Hg vapor pressure in the reaction tube 11 becomes constant at a predetermined value, Et2Te is supplied from the bubbler 2 as a raw material gas.
The liquid is sent into the vertical reaction tube 11 through the nozzle 10. For example, if MFC7 and MFC8 are each set at 2.5Ω/min, the temperature of thermostatic chamber 4 is set at 40°C, and MFC6 is set at 100ml/min, the concentration of Et2Te in vertical reaction tube 11 is
It becomes 7X10-6 mol/ρ. In addition, the H2 gas flow rate sent to the Et2Te bubbler 2 is 1 to 500ml.
The appropriate dilution H2 gas flow rate is approximately 0.1 to 20 g/min, more preferably approximately 1 to 10 g/min.

The substrate 15 is already heated and rotated, and the Et2Te
At the same time as the supply of HgTe starts, growth of HgTe crystals begins on the surface of the substrate 16.

Furthermore, after the formation of the HgTe thin film of a predetermined thickness is completed, the reaction apparatus is switched to the above-described CdTe thin film growth system, and the CdTe thin film is again formed.In other words, first, the supply of Et2Te is stopped.

Then, at the same time as stopping the power supply to the tube wall heating coil heater 28, the flow of the cooling medium to the tube wall cooling pipe 29 is restarted, so that the tube wall reaches the predetermined set temperature in the range of 20 to 40 degrees Celsius. The current flow to the thermoelectric conversion element 27 is switched again to the cooling direction, and the mercury reservoir 1
2 is rapidly cooled down to the predetermined set temperature in the range of -20 to 20° C., and the supply of mercury vapor into the reaction tube 11 is stopped. When the mercury vapor pressure inside the reaction tube 11 becomes 0, supply of the raw material gas is started.

That is, Me2Cd and Et2 from bubblers 1 and 2
Te is sent out, and H2 is heated to a predetermined set concentration as described above.
It is diluted with gas and sent into the vertical reaction tube 11 through the nozzles 9 and 10. In this way, a CdTe crystal is grown on the surface of the substrate 16, which has already been heated and is in a rotating state.

Thereafter, as described above, the reaction apparatus is alternately switched between the CdTe thin film growth system and the HgTe thin film growth system, and the operation is repeated until a predetermined number of layers is reached.

The above is CMT (C d . H g s-, Te)
and C such as C d T e / H g T e
The vapor phase growth method and vapor phase growth apparatus of the present invention have been explained by taking the vapor phase growth of a d-Hg-Te single crystal thin film as an example.
The present invention also applies to other compound semiconductors, such as Cd. Zn, Hg1
-x-yTe and CdTe/ZnT
Cd-Zn-Hg-T like e / H g T e
The method can be similarly applied to single crystal thin film growth of mercury-containing compounds such as e-based compounds, and can obtain large-area thin film crystals with high composition ratio control and good surface conditions.

(Example) EXAMPLES The present invention will be explained in more detail below with reference to Examples.

Example 1 A CMT crystal growth experiment was conducted using an apparatus as shown in FIG.

That is, using H2 gas as a carrier gas, Me2Cd and Et2Te are injected into the vertical reaction tube 11 through nozzles 9 and 10, respectively, at IX10'mo1/II! , IXI
It was fed at a flow rate of O-'mo 1/l. In addition, Me2
The opening of the Cd gas supply nozzle 9 was located 20 mm directly above the surface of the substrate 16, which will be described later. Also, this nozzle 9
The mercury reservoir 12 supported by the reaction tube 11 and placed directly above the substrate 16 in the reaction tube 11 was heated by the mercury reservoir heating heater 14 to set the temperature of the mercury reservoir 12 to 320° C. to generate mercury vapor. Note that the mesh-like bottom surface of the mercury reservoir 12 was located 40 mm above the surface of the substrate 16. Then, on the carbon susceptor 17, a CdTe substrate with a diameter of 2 inches (
The crystal orientation (1 1 1) plane) 16 is maintained, and the substrate 16
was rotated at a speed of 5 times/min. Set the susceptor temperature to 400
℃, and the pressure inside the reaction tube was 150 torr.
A CMT crystal thin film with a thickness of 5 μm was grown on the surface of a CdTe substrate. Note that the tube wall of the reaction tube was heated by a tube wall heater 22 set at 350°C.

When the composition ratio of the obtained grown thin film was evaluated using a Fourier transform infrared spectrophotometer (FTIR spectrophotometer), the variation in the composition ratio within a plane with a diameter of 2 inches was 1% or less.

Example 2 Using the apparatus shown in FIG. 3, the same total raw material gas supply flow, mercury reservoir temperature, tube wall temperature, substrate rotation speed, and the same conditions as in Example 1 were used.
Under growth temperature and growth pressure conditions, CdTe substrate (
A CMT crystal was grown on the (1 1 1) crystal orientation.

In the device used, the openings of the Me2Cd gas supply nozzle 9' and the Et2Te gas supply nozzle 10'' are located approximately 10 mm outward from the edge of the substrate 16 with a diameter of 2 inches and approximately 20 mm above the surface of the substrate 16. It was installed at.

Further, the mesh-shaped bottom surface of the mercury reservoir 12, which was supported by the support shaft 26 and placed directly above the substrate 16, was located 40 mm above the surface of the substrate 16.

The composition ratio of the grown thin film obtained was analyzed by FTIR in the same manner as in Example 1.
When evaluated using a spectrophotometer, the variation in composition ratio within a 2-inch diameter plane was 1% or less.

Comparative Example 1 For comparison, a CdTe substrate (crystal orientation (111) plane) with a diameter of 1 inch was placed on a carbon susceptor 33 using a horizontal reaction tube having the configuration shown in FIG. A CMT crystal was grown under the same raw material gas supply flow rate, mercury reservoir temperature, tube wall temperature, growth temperature, and growth pressure conditions as in Example 1.

The composition ratio of the grown thin film obtained was analyzed by FTIR in the same manner as in Example 1.
When evaluated using a spectrophotometer, the variation in composition ratio within a plane with a diameter of 1 inch reached a maximum of 30%.

Furthermore, an attempt was made to grow a CMT crystal on a CdTe substrate with a diameter of 2 inches under similar growth conditions, but the crystal growth site on the substrate was uneven, and the growth of a single crystal thin film with a diameter of 2 inches was essentially impossible. It was impossible.

Example 3 Using an apparatus as shown in FIG.
A dTe thin film, a HgTe thin film, and a CdTe thin film were successively grown in this order. In the apparatus used, the opening of the Me2Cd gas supply nozzle 9 was located 20 mm directly above the surface of the substrate 16, which will be described later. The mesh-shaped bottom surface of the mercury reservoir 12, which is supported by this nozzle 9 and placed directly above the substrate 16 in the reaction tube 11, is 40 m from the surface of the substrate 16.
m” was located in the second section. A conical carbon susceptor with an apex angle of 60'' was used as the carbon susceptor for installing the substrate, and three 2-inch CdTe substrates were attached to the side surface of the carbon susceptor.

First, in order to grow a CdTe thin film as the first layer,
A current in the cooling direction is passed through the thermoelectric conversion element 27 to cool the mercury reservoir 12.
The tube wall of the vertical reaction tube 11 was cooled to 0.degree. C. by flowing water through the tube wall cooling pipe 28. In this vertical reaction tube 11, H2 gas is used as a carrier gas, and M
e2Cd and Et2Te from nozzles 9 and 10 respectively at 1×10' mo 1 /II 11 X 1 0−
It was fed at a flow rate of 5mo 1/ρ. Three CdTe substrates (crystal orientation (111) plane) 16 having a diameter of 2 inches were held on the conical carbon susceptor 17, and the substrates 16 were rotated at a speed of 5 times/min. Set the susceptor temperature to 360
℃ and the pressure inside the reaction tube was 100 torr.
A CdTe thin film with a thickness of 1 μm was grown on the surface of a CdTe substrate.

Next, in order to grow the HgTe thin film as the second layer, the direction of the current flowing through the thermoelectric conversion element 27 is switched to heat the mercury If/12 to 370° C., and cooling by the tube wall cooling pipe 28 system is stopped. Then, the tube wall heating coil heater 29 was energized to heat the tube wall of the reaction tube 11 to 380.degree. C., and mercury vapor was supplied into the reaction tube 11. In this horizontal reaction tube 11, H2 gas was used as a carrier gas, and Et2T
e was fed into the nozzle], 0 at a flow rate of IXIO-5 mol/Ω. Then, at the reaction tube internal pressure IQQtorr,
A layer of HgTe with a thickness of 1 μm was continuously applied onto the 16 surface of the substrate, which had already been rotated at a speed of 5 times/min and heated to a substrate temperature of 360°C.
Thin film growth was performed.

Furthermore, in order to grow a CdTe thin film as the third layer, the direction of the current flowing through the thermoelectric conversion element 27 is switched again to the cooling direction to cool the mercury reservoir 12 to 0°C, and the coil heater 28 for heating the tube wall is was turned off, water was again flowed through the tube wall cooling pipe 29 to cool the tube wall of the reaction tube 11 to 0°C, and Me2Cd and Et2T were cooled using H2 gas as a carrier gas.
e from nozzles 9 and 10, respectively, in an amount of IXIO-'mol.
/Ω, IXIO-5 mol/fl.

Then, at the reaction tube internal pressure IQQtorr, 5 times /
Substrate 1 rotated at a speed of 1 minute and heated to a substrate temperature of 360°C.
A CdTe thin film with a thickness of 1 μm was continuously grown on the 6 sides.

When the film thickness of each layer of the obtained laminate was evaluated by scanning electron microscopy (SEM) observation of the cross section of each substrate, the variation in the film thickness of each layer within a plane of 2 inches in diameter was less than 1%. Ta.

Furthermore, the obtained laminate was subjected to XMA (X-ray Mi
As analyzed by cro analyzer), the first and third layers are completely CdT. e, Hg
No contamination was observed. In addition, switching the reaction system in this reactor can be done very quickly,
Switching from the HgTe reaction system in the second layer to the CdTe reaction system in the third layer, despite cooling the reaction tube,
It only took about 3 minutes.

(Effects of the Invention) As described above, according to the present invention, it is possible to increase the size and simultaneously process a large number of mercury-containing compound single crystals grown for crystal growth on a substrate using a vertical reaction tube. ,
In addition, it is possible to prevent the reaction between the low-temperature decomposable raw material gas and mercury vapor in the gas phase in the reaction tube, and furthermore, it is possible to arrange the substrate so as not to be affected by the imbalance in the flow of the raw material gas. Therefore, it becomes possible to form a mercury-containing compound single crystal thin film with high composition ratio uniformity, controllability, and good surface condition.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of an embodiment of the vapor phase growth apparatus of the present invention, Fig. 2 is a graph showing vapor pressure curves of Me2Cd and Et2Te, and Fig. 3 is a diagram showing the structure of an embodiment of the vapor phase growth apparatus of the present invention. FIG. 4 is a schematic diagram showing the configuration of yet another embodiment of the present invention, and FIG. 5 is a schematic diagram showing the configuration of an example of a conventional vapor phase growth apparatus. It is a diagram. 1, 2... Bubbler 3, 4... Constant temperature bath, 5, 6
... Mass flow controller for supply ffl adjustment {・Roaf, 7,8... Mass flow controller for dilution flow rate adjustment,
9,9-...Me2Cc! Gas supply nozzle, 10.
10'...E t2 Te gas supply nozzle, 11
...Vertical reaction tube, 12...Mercury reservoir, 13...Through hole, 14...Heater for heating the mercury reservoir, 15...Thermocouple for monitoring mercury reservoir temperature, 16...Substrate, 17... Carbon susceptor for board mounting, 18...
Rotating shaft, 19... Rotating motor, 20... RF coil for substrate heating, 21... Thermocouple for monitoring substrate temperature, 23... Exhaust device, 25... Exhaust gas treatment device, 2... Heater for heating the tube wall, 4... High vacuum evacuation device, 6... Mercury reservoir support shaft, 7... Thermoelectric conversion element for heating/cooling the mercury reservoir, 8... Coil heater for heating the tube wall, 9... Pipe for tube wall cooling, 0... Horizontal reaction tube, 31... Gas inlet ports 1, 2.
...Mercury reservoir, 33...Carbon susceptor, 4...
Substrate, 35... High frequency coil for substrate heating, 6...
Resistance heater for tube wall heating.

Claims (7)

[Claims] (1) In a method for growing a single crystal thin film of a compound containing Hg by organometallic vapor phase epitaxy, a vertical reaction tube is used as the reaction tube, and the reaction tube is held by a shaft hanging from the upper wall of the reaction tube. A mercury reservoir placed in the inner space of the tube is heated to a predetermined temperature to generate mercury vapor in the reaction tube, while one or more mercury vapors are introduced into the reaction tube from the raw material gas introduction system by being accompanied by a carrier gas. Among the metal-organic compounds, at least the low-temperature decomposable metal-organic compound is supplied from a nozzle that opens below the location of the mercury reservoir, and the temperature is controlled to a predetermined temperature below the mercury reservoir and the nozzle opening. 1. A method for vapor phase growth of a single crystalline thin film of a compound containing mercury, the method comprising: placing a mercury-containing compound substrate thereon, and rotating the substrate about the central axis of a vertical reaction tube. (2) In the method of growing a Cd-Hg-Te single crystal thin film by organometallic vapor phase epitaxy, a vertical reaction tube is used as the reaction tube, and the reaction tube is held on a shaft hanging from the upper wall surface of the reaction tube. A mercury reservoir placed inside the reaction tube is heated to a predetermined temperature to generate mercury vapor inside the reaction tube, while a tellurium organic compound supply nozzle is inserted from the top of the reaction tube and opens into the reaction tube. Then, a predetermined amount of an organic tellurium compound and an organic cadmium compound are respectively entrained in the carrier gas from a cadmium organic compound supply nozzle that is inserted from the top of the reaction tube and opens at a position below the mercury reservoir in the reaction tube. The mercury is introduced into the reaction tube, a substrate whose temperature is controlled to a predetermined temperature is placed below these mercury reservoirs and nozzle openings, and this substrate is further rotated about the central axis of the vertical reaction tube. Cd-Hg-Te
Vapor-phase growth method for single-crystalline thin films. (3) Mercury cadmium telluride (Cd_xHg_1_-
_xTe) The vapor phase growth method according to claim 1 or 2, wherein a single crystal thin film is grown. (4) Control the temperature of the mercury reservoir and the raw material gas supply system,
3. The vapor phase growth method according to claim 1, wherein cadmium telluride (CdTe) single crystal thin films and mercury telluride (HgTe) single crystal thin films are grown alternately. (5) A vapor phase growth apparatus for growing a compound single crystal thin film containing mercury, wherein a mercury reservoir is arranged in a vertical reaction tube and held by a shaft hanging from the upper wall of the vertical reaction tube; One or more metal-organic compound supply nozzles are inserted through the upper wall surface of the vertical reaction tube, and at least the low-temperature decomposable metal-organic compound supply nozzle is located below the mercury reservoir. A susceptor for mounting a substrate, which is equipped with a rotation mechanism that rotates about the central axis of the vertical reaction tube, is placed below the mercury reservoir and nozzle openings in the vertical reaction tube. 1. A vapor phase growth apparatus for a single crystal thin film of a compound containing mercury, characterized in that the vertical reaction tube is supported from the lower side and an exhaust system for evacuating the inside of the vertical reaction tube is connected to the lower side of the vertical reaction tube. (6) The vapor phase growth apparatus according to claim 5, wherein the nozzle for supplying the low-temperature decomposable metal organic compound also serves as a shaft for holding the mercury reservoir. (7) A vapor phase growth apparatus for growing a Cd-Hg-Te single crystal thin film, in which a mercury reservoir is placed in a vertical reaction tube and held by a shaft hanging from the upper wall of the vertical reaction tube. Then, a tellurium organic compound supply nozzle and a cadmium organic compound supply nozzle are inserted through the upper wall of the vertical reaction tube, so that at least the cadmium organic compound supply nozzle is located below the mercury reservoir. and a rotating mechanism that has a substrate installation surface and rotates about the central axis of the vertical reaction tube is located below the mercury reservoir and nozzle openings in the vertical reaction tube. A Cd characterized in that a susceptor for installing a substrate is disposed to be supported from the lower side of the vertical reaction tube, and an exhaust system for exhausting the inside of the vertical reaction tube is connected to the lower side of the vertical reaction tube. - Vapor phase growth apparatus for Hg-Te single crystal thin film.