JP4994432B2 - ZnO semiconductor single crystal layer manufacturing method - Google Patents

Description

  An object of this invention is to provide the manufacturing method and manufacturing apparatus suitable for epitaxially growing the crystalline film of a compound semiconductor.

  Crystal growth methods for III-V compound semiconductors such as GaAs, GaAlAs, GaAsP, GaAlP, and GaAlAsP used for optical elements include liquid phase growth (LPE), molecular beam epitaxy (MBE), and organic metal vapor. A phase growth (MOCVD) method or the like is used. In particular, the MOCVD method is widely used because of its high crystal growth rate and excellent controllability and reproducibility of film growth. For example, Patent Document 1 discloses that a substrate is treated with a predetermined gas in a pretreatment chamber, then moved to an MOCVD growth chamber, an organic group III compound gas and an organic group V compound gas are introduced, a pressure of 76 torr, and a substrate temperature. It is disclosed that an AlGaAs layer and a GaAs layer are crystal-grown under a condition of 750 ° C.

  On the other hand, among III-V group compound semiconductors, the characteristics of optical elements using nitride III-V group compound semiconductors such as GaN, GaAlN, and InGaN are attracting attention. In addition, II-VI group compound semiconductors such as ZnSe, ZnCdSe, ZnO, and ZnMgO have been studied as next-generation semiconductors.

Japanese Patent No. 3353876

However, II-VI group compound semiconductors such as ZnSe, ZnCdSe, ZnO, ZnMgO and the like are formed by MOCVD, which is used for the growth of conventional III-V group compound semiconductors. Often becomes a polycrystalline layer. Even if a single crystal layer is formed, the n-type residual carrier concentration is high, or the rocking curve has a wide half-value width in the X-ray ω-θ measurement reflecting the geometrical alignment of the crystal. It is very difficult to grow crystals epitaxially. Specifically, in the case of a ZnO crystal, in order to obtain a good p-conduction type layer, the residual carrier density is 5 × 10 ¹⁶ (pieces / cm ³ ) or less, and the crystal domain tilting and twisting amount is small. Although it is necessary to grow a crystal, it has not been obtained by the conventional MOCVD method. In particular, in order to reduce the n-type residual carrier concentration caused by oxygen vacancies, it is necessary to use a highly reactive oxygen supply material. However, a highly reactive VICVD method using a conventional viscous fluid region is necessary. When a group gas is used, the source gas (group II gas and group VI gas) reacts before the source gas reaches the substrate, and the source gas can be supplied to the substrate while maintaining high reactivity. There wasn't. On the other hand, when the MBE method is used, a single crystal can be grown, but there is a problem that the growth rate is slow.

The objective of this invention is providing the manufacturing method suitable for manufacture of the II-VI group compound semiconductor excellent in crystallinity.

  The inventors have investigated the reason why high-quality crystals of II-VI compound semiconductors cannot be epitaxially grown by the usual MOCVD method used for the growth of III-V compound semiconductors. As a result, group II compound gas and group VI compound gas, which are source gases for II-VI group compound semiconductors, are often more reactive than group III compound gas and group V compound gas, and the source gas is applied to the substrate. It was found that the raw material gases reacted with each other in the space just before reaching to form reaction products, and some of them were deposited on the substrate to inhibit epitaxial growth. In order to solve this problem, it is necessary to control the source gases of highly reactive II-VI compound semiconductors so that they do not react with each other until they reach the substrate, and that a reaction occurs on the substrate.

The inventors have carried out MOCVD of II-VI group compound semiconductors at a pressure in a region where the source gas exhibits molecular flow and molecular flow behavior, so that the source gases react with each other before reaching the substrate. We have found that the phenomenon of product formation can be avoided. In the present invention, the pressure in the region where the source gas exhibits molecular flow and molecular flow behavior is the value obtained by dividing the distance L from the gas supply nozzle to the substrate by W in the mean free path of the source gas (L / W) means a pressure region of several tens or less, specifically, for example, about 10 ⁻² torr or less. In addition, a pressure region greater than 10 ⁻² torr and less than or equal to 10 torr which is an intermediate pressure region between the molecular flow region and the completely viscous fluid region is referred to as a submolecular flow region, and is included in the pressure region of the present invention. The gas pressure of the MOCVD method used for the growth of conventional III-V group compound semiconductors is usually several tens of torr and is a complete viscous fluid region. Similarly, it is determined by fluid dynamics, for example, convection occurs when there is a temperature distribution, and stagnation occurs when the shape of the vacuum vessel or an obstacle exists. For this reason, it is extremely difficult to control the traveling directions so that the two kinds of source gases do not contact each other until they reach the substrate.

On the other hand, at the pressure in the molecular flow region (10 ⁻² torr or less), the molecules of the source gas behave as particles, and thus travel straight through the mean free path. Go straight. Therefore, it is possible to control the traveling direction of the source gas. In addition, the pressure in the submolecular flow region (greater than 10 ⁻² torr and less than 10 torr) is a boundary region in which not only the behavior of the molecular flow but also the behavior of the viscous flow begins to be exhibited, but the gas supplied from the nozzle diffuses straight. Is maintained, and the direction of travel can be controlled. In the present invention, two types of source gases are blown out from the gas supply port toward the substrate, so that the source gases are made to travel almost straight to the substrate and collide with the substrate, thereby bringing them into contact and reacting on the substrate. Thereby, epitaxial growth can be caused on the substrate.

  Of the source gas that has collided with the substrate, the source gas that has not reacted is reflected on the substrate. If there is a vacuum vessel wall or obstacle in the traveling direction, it will be further reflected and return to the substrate direction again, reacting with the source gas supplied from the gas supply port in the space in front of the substrate and reacting the reaction product. And may interfere with epitaxial growth. Therefore, in the present invention, the traveling direction of the source gas supplied toward the substrate is controlled even after the collision with the substrate, and exhausted quickly.

  As described above, in the present invention, the source gas of the II-VI group compound semiconductor is supplied toward the substrate at the gas pressure in the region showing the behavior as a molecular flow, and the traveling direction of the source gas after the collision with the substrate is controlled. A method of manufacturing a semiconductor by the MOCVD method that exhausts without returning to the substrate is provided.

That is, a method of manufacturing a ZnO semiconductor single crystal layer using a semiconductor manufacturing apparatus having the following configuration is provided. A semiconductor manufacturing apparatus exhausts a gas in a vacuum vessel, a substrate mounting portion for arranging a substrate in the vacuum vessel, a gas supply portion for ejecting two or more source gases to the substrate, and a vacuum vessel And an exhaust port provided in the vacuum vessel. The gas supply unit is disposed at a position for ejecting the source gas from an oblique direction with respect to the substrate surface, and has a plurality of first ejection ports arranged in a row for ejecting the first source gas, A plurality of second jet nozzles arranged in a row for jetting two source gases, and the row of first jet nozzles and the row of second jet nozzles are arranged alternately. . The exhaust port is disposed at a position where the raw material gas is reflected on the substrate while remaining unreacted and is reflected by the side wall of the vacuum vessel. The ZnO semiconductor single crystal layer manufacturing method of the present invention uses this semiconductor manufacturing apparatus, the step of setting the pressure in the submolecular flow region in the vacuum vessel, and the first source gas and the second source gas are ejected to the substrate. And a step of growing a ZnO single crystal.

The angle formed between the gas supply unit and the substrate is set to, for example, 30 ° to 70 °. The distance between the source gas ejection surface of the gas supply unit and the substrate is set to, for example, 30 mm or more and 200 mm or less.

The gas supply unit ejects an inert gas layer that separates the first source gas layer ejected from the first ejection port and the second source gas layer ejected from the second ejection port. It is also possible to have a configuration further including an inert gas jet port arranged between the first jet port and the second jet port.

It is also possible to attach a separation plate for reducing collisions between the source gases between the row-shaped first jet ports and the row-shaped second jet ports. The substrate mounting portion can be configured to mount a plurality of the substrates, and a projection for controlling the direction of the gas reflected on the substrate surface can be provided at the center thereof.

Sectional drawing which shows the structure of the single piece type MOCVD apparatus of the 1st Embodiment of this invention. (A) And (b) is a perspective view of the gas supply nozzle 12 of the MOCVD apparatus of FIG. (A) is a perspective view showing a configuration in which the gas supply nozzle 12 of the MOCVD apparatus of FIG. 1 is provided with an inert gas ejection slit for reducing the number of collisions of source gases, and (b) is a gas supply nozzle 12 of FIG. Explanatory drawing which shows the layer structure of the source gas discharge | released from. Sectional drawing which shows the structure of the multi-sheet type MOCVD apparatus of 2nd Embodiment. The top view of the susceptor 11 of the MOCVD apparatus of FIG. FIG. 6 is a cross-sectional view showing a configuration in which a guide plate 61 is disposed on the upper part of the gas supply nozzle 12 of the MOCVD apparatus of FIG. The perspective view which shows the structure provided with the separation plate for reducing the frequency | count of collision of source gas as the gas supply nozzle 12 of the MOCVD apparatus of FIG. Sectional drawing which shows the structure which has arrange | positioned the adhesion board 81 to the multi-sheet type MOCVD apparatus of 2nd Embodiment. Sectional drawing which shows the structure which has arrange | positioned the adsorption | suction jacket 91 in the multi-sheet type MOCVD apparatus of 2nd Embodiment. Sectional drawing which shows the apparatus made into the structure which has arrange | positioned the gas supply nozzle 12 by incident angle (theta) 1 = 45 degree or more, and was directly exhausted in the MOCVD apparatus of 2nd Embodiment.

Hereinafter, an embodiment of the present invention will be described.
(First embodiment)
The semiconductor manufacturing apparatus according to the first embodiment will be described with reference to FIG. The semiconductor manufacturing apparatus of FIG. 1 is an apparatus for performing metal organic chemical vapor deposition (MOCVD) at a pressure in a region that exhibits a behavior as a molecular flow. As shown in FIG. 1, the MOCVD apparatus includes a susceptor 11 for placing a substrate 10 and a gas for irradiating the first and second source gases toward the substrate 10 mounted on the susceptor 11. And a supply nozzle 12. These are arranged in the vacuum vessel 13. On the back side of the susceptor 11, a heater 17 for heating the substrate 10 and a rotation drive mechanism 18 for rotating the susceptor 11 are arranged. Further, an exhaust port 14 having a predetermined opening diameter is provided at a predetermined position in the vacuum vessel 13. An inlet pipe 15 having a predetermined shape is connected to the exhaust port 14 and a vacuum exhaust device 16 is attached thereto. The pressure in the vacuum vessel 13 is adjusted within the pressure range (10 ⁻⁴ or less 10 ^{−4) in which the} source gas behaves as a molecular flow by adjusting the gas ejection amount of the gas supply nozzle 12 and the exhaust amount of the vacuum exhaust device 16. It is desirable that it is not less than torr, more preferably not more than 5 torr, still more preferably not more than 3 torr and not less than 0.01 torr.

  As shown in FIG. 2A, the gas supply nozzle 12 has supply pipes 24 and 25 that take in the first and second source gases from the outside of the vacuum container 13 of the nozzle 12, respectively. On the ejection surface 21 of the gas supply nozzle 12, rows of ejection ports 22 that eject the first source gas and rows of ejection ports 23 that eject the second source gas are alternately arranged. . Inside the nozzle 12, a flow path for guiding the first source gas supplied from the supply pipe 24 to the jet outlet 22, and a flow path for guiding the second source gas supplied by the supply pipe 25 to the jet outlet 23 are provided. Is provided. Accordingly, the first source gas and the second source gas can be ejected from the ejection port 22 and the second source gas can be ejected from the ejection port 23 without bringing the first source gas and the second source gas into contact with each other. .

  The direction of the jet ports 22 and 23 of the gas supply nozzle 12 is set so that the flow of the jetted source gas enters the substrate 10 at a predetermined incident angle θ1. That is, the gas ejection surface 21 on which the ejection ports 22 and 23 are disposed is disposed so as to be inclined obliquely from above and face the substrate 10, and the angle formed between the normal line of the gas ejection surface 21 and the main plane of the substrate 10 is The angle θ1 is set. The size of the gas ejection surface 21 is determined so that the entire surface of the substrate 1 is irradiated when the gas ejected from the position advances straight. Thereby, two kinds of source gases are respectively ejected from the jet outlets 22 and 23 of the gas supply nozzle 12 into the vacuum vessel 13 set in a pressure range in which the source gas behaves as a molecular flow. The source gas goes straight and enters the entire surface of the substrate 10 at an incident angle θ1. The wall surface of the gas introduction part of the vacuum vessel 13 is shaped so as not to hinder the flow of the source gas. In addition, the row direction of the ejection ports 22 and 23 on the ejection surface can be arranged in parallel to the surface including the incident angle θ1 as shown in FIG. 2A, or as shown in FIG. In addition, it may be arranged perpendicular to the plane including the incident angle θ1.

  The exhaust port 14 of the vacuum vessel 13 is arranged in a direction symmetrical to the gas supply nozzle 12 with the substrate 10 interposed therebetween so that the flow of the source gas reflected by the substrate 10 is directly incident without colliding with an obstacle or the like. Yes. That is, the path connecting the gas supply nozzle 12, the substrate 10, and the exhaust port 14 is a V-shaped path. The size of the opening of the exhaust port 14 is determined such that the flow of the source gas reflected from the entire substrate 1 can enter. In addition, the wall 15a close to the substrate 10 is connected to the substrate 10 so that the flow of the source gas incident from the exhaust port 14 can proceed to the vacuum exhaust device 16 without colliding with the wall. The angle θ2 (= θ1) is set. The wall surface 15b far from the substrate 10 is less set to form an angle θ2 with the substrate 10 because the straightness of the flow of the source gas decreases as the distance from the substrate 10 increases, and the source gas is supplied to the vacuum exhaust device 16. Its shape is determined to guide. As a result, the flow of the raw material gas injected from the gas supply nozzle 12 is incident on the substrate 1 at an incident angle θ1 and reflected by the surface of the substrate 1 toward the exit angle θ2 (= θ1) due to elastic scattering. The flow of the reflected source gas directly enters the exhaust port 14 and reaches the vacuum exhaust device 16 to be exhausted.

  A window 19 is provided on the extension of the wall surface 15a of the introduction tube 15 at a position where the substrate 10 can be directly viewed. In addition to the purpose of visually observing the substrate 10, the window 19 can irradiate the film formed on the substrate 10 through the window 19 and receive the reflected light to measure the film thickness. Is possible. In order to irradiate high energy ultraviolet rays to promote the reaction of the source gas on the substrate 10, or to irradiate high energy infrared rays to improve the migration of the reaction product on the substrate 10, A window 19 can also be used.

  The gas supply nozzle 12 is provided with a temperature adjusting device (for example, a water cooling device) for adjusting the temperature of the source gas, which is not shown. By this temperature adjusting device, the raw material gas is adjusted so as to maintain a temperature lower than the self-decomposition temperature and the raw material gas does not become liquid in the nozzle 12. For example, when a group II compound gas and a group VI compound gas are used as the source gas, the temperature of the gas supply nozzle 12 is preferably set to a temperature from room temperature to about 200 ° C.

The distance L between the ejection surface 21 of the gas supply nozzle 12 and the substrate 10 is better as the value (L / W) divided by the average free path (W) of the source gas is smaller. That is, it is desired that the distance (L) is short or the mean free path (W) is long. However, since the relationship between the two is limited by the source gas concentration on the substrate 10 and the geometric and temperature of the gas supply nozzle 12, the following relationship is desirable. In the pressure region where the pressure in the vacuum vessel 13 is 10 ⁻² torr or less from the high vacuum region, the mean free path of the source gas is relatively long (for example, in the case of O ₂ , W≈5 mm at 10 ⁻² torr). The distance from the nozzle 12 to the substrate 10 can be increased. If the nozzle 12 is far from the substrate surface, the influence of heat received from the substrate 10 is small, and the raw material gas can be prevented from unexpectedly decomposing at the nozzle 12 portion. Specifically, the distance L is desirably set to 200 mm or less, and more desirably 150 mm or less. Further, in the pressure region of 10 ⁻² torr or more and 10 torr or less, the mean free path becomes short (for example, in the case of O ₂ , W≈5 μm at 10 torr). Is preferably set to 150 mm or less, more preferably 100 mm or less. On the other hand, the closest distance between the supply nozzle 12 and the substrate 10 is preferably 30 mm or more, more preferably 40 mm or more when the substrate temperature is 600 ° C. or less. Further, when the substrate temperature is 1000 ° C. or lower, it is preferably 40 mm or more, and more preferably 50 mm or more.

  The supply angle and the exhaust angle of the source gas with respect to the substrate 10 are determined by the angle θ1 (= θ2) formed by the gas supply nozzle 12 and the substrate 10. In order to obtain smooth exhaust gas, it is desirable that θ2 (= θ1) is large, and in order to reduce the overlap in the space between the supply gas and the exhaust gas, it is desirable that θ1 is small. When the pressure in the vacuum vessel is low (high vacuum), θ1 can be increased, and when the pressure is high, θ1 is preferably small. Specifically, θ1 is preferably 30 ° or more and 70 ° or less, and more preferably 40 ° or more and 60 ° or less.

  On the other hand, the pressure in the vacuum vessel balanced by the raw material gas flow rate and the exhaust speed is preferably 10 torr or less, desirably 3 torr or less, more desirably 1 torr or less and 0.01 torr or more.

  In the region where the mean free path of the source gas is short in the submolecular flow region where the pressure in the vacuum vessel 13 is 0.01 to 10 torr, the number of collisions of the source gas (the number of collisions between the group II compound gas and the group VI compound gas) is reduced. It is also possible to adopt means for making it happen. For example, a partition plate or an inert gas layer is disposed between the ejection ports 22 and 23 ejected from the source gas supply nozzle 12, and the two types of ejected gas flows are kept from contacting each other. It is possible to proceed to near, mix a low-reactive gas into the raw material gas, or use a low-reactive gas as the raw material gas itself.

  Next, a method for growing a ZnO layer, which is a II-VI group compound semiconductor, on the substrate 10 using the MOCVD apparatus of FIG. 1 will be described.

As the substrate 10, a sapphire single crystal, a ZnO single crystal, or the like can be used. The first source gas uses a group II compound gas, and the second source gas uses a group VI compound gas. As the group II compound gas, a gas containing at least one of dimethyl zinc (denoted as DMZ), diethyl zinc (denoted as DEZ), and cyclopentadienyl magnesium (denoted as Cp2Mg) can be used. As the group VI compound gas, a gas containing at least one of water vapor (H ₂ O), oxygen (O ₂ ), nitrous acid gas (NO ₂ ), and laughing gas (N ₂ O) can be used. For example, DMZ can be used as the group II compound gas, and oxygen or water vapor can be used as the group VI compound gas. Further, DEZ can be used as the group II compound gas, and oxygen or water vapor can be used as the group VI compound gas.

The substrate 10 is mounted on the susceptor 11 in the vacuum vessel 13. Thereafter, the vacuum evacuation device 16 is operated to evacuate to a predetermined degree of vacuum, and then the substrate 10 is heated by the heater 17. The temperature of the substrate 10 is desirably set to 300 ° C. to 900 ° C., and can be set to 400 ° C. or higher, for example, when the ZnO layer is epitaxially grown. In this state, the II group compound gas and the VI group compound gas are supplied into the gas supply nozzle 25 from the supply pipes 24 and 25, respectively, and are ejected from the separate outlets 22 and 23, respectively. The supply amount of the source gas and the exhaust amount of the vacuum exhaust device 16 are controlled so that the pressure in the vacuum vessel 13 becomes 10 ⁻⁴ torr to 10 torr. The temperature of the gas supply nozzle 12 is controlled by a temperature adjusting device so that the temperature at which the source gas does not become liquid is maintained at a temperature lower than the self-decomposition temperature of the two types of source gases.

By controlling the pressure in the vacuum vessel 13 in this way, the group II compound gas and the group VI compound gas released into the vacuum vessel 13 from the ejection ports 22 and 23 of the gas supply nozzle 12 become a molecular flow. And go straight ahead. Since the gas supply nozzle 12 is disposed obliquely above the main plane of the substrate 10 at an angle θ1 as described above, the two kinds of source gases have an incident angle θ1 as shown in FIG. Is incident on the upper surface of the substrate 10. When two types of source gases are incident on the substrate 10, the two types of source gases collide with each other on the substrate 10 to cause a chemical reaction, and ZnO is generated. For example, when DMZ ((CH ₃ ) ₂ Zn) is used as the group II compound gas and oxygen is used as the group VI compound gas, both molecules collide on the substrate 10 and react as shown in the following formula (1). ZnO is produced.
(CH ₃ ) ₂ Zn + 1 / 2O ₂ → ZnO (1)

The generated ZnO is arranged along the crystal axis (c-axis) of the sapphire (Al ₂ O ₃ ) substrate 10 to form a ZnO layer. Thereafter, ZnO is sequentially bonded onto the ZnO layer, whereby a ZnO crystal grows, and the ZnO crystal layer can be epitaxially grown.

  On the other hand, of the two kinds of source gases incident on the substrate 10, the source gas that did not cause the chemical reaction of the formula (1) is reflected by the surface of the substrate 10 due to elastic scattering, and the incident angle θ1 as shown in FIG. Is reflected at an emission angle θ2 equal to. In the present embodiment, since the exhaust port 14 is disposed in the traveling direction of the source gas reflected at the emission angle θ2, all the source gas reflected by the substrate 10 can be incident into the exhaust port 14. The raw material gas that has traveled straight through the introduction pipe 15 is directed away from the substrate 10 toward the vacuum exhaust device 16 at a position where the straight travel energy is weakened and exhausted by the vacuum exhaust device 16. Therefore, the source gas reflected by the substrate 10 is quickly exhausted by the vacuum exhaust device 16 without returning to the direction of the substrate 10 again. By controlling the traveling direction of the source gas after reflection in this way, two types of highly reactive source gases can be prevented from returning to the direction of the substrate 10 again. It is possible to prevent a phenomenon in which the raw material gas reacts as a turbulent flow in an unexpected space such as an upper space and forms ZnO crystal grains. Thereby, deposition of ZnO crystal grains on the substrate 10 can be prevented and epitaxial growth can be continued.

In the MOCVD apparatus of the present embodiment, since the reaction of the above formula (1) occurs on the substrate 10 or in the very vicinity of the substrate 10 as described above, not only the molecular migration (thermal motion) but also the formula ( The reaction energy of 1) can be used to generate the bond between the outermost surface atom of the substrate 10 and ZnO and the bond between ZnO. Therefore, there is an advantage that the obtained ZnO crystal layer has higher crystallinity as compared with the MBE method in which Zn and O ₂ reach the substrate in advance and are arranged only by molecular migration by energy obtained from the substrate temperature. There is also an advantage that the crystal growth rate is higher than that of the MBE method. Therefore, a high-performance optical element can be efficiently manufactured by manufacturing an optical element using a ZnO crystal layer with the MOCVD apparatus of this embodiment.

  Further, in the MOCVD apparatus of the present embodiment, the bonding of ZnO on the substrate 10 is promoted by irradiating the substrate 19 with ultraviolet rays having an energy level equal to the bonding level of Zn and O. In addition, crystallinity can be improved. It is also possible to promote the reaction of the formula (1) by supplying the energy necessary for advancing the reaction from the left side to the right side of the formula (1) from the window 19 with ultraviolet rays. Furthermore, by irradiating infrared rays from the window 19, it is possible to activate ZnO migration (thermal motion) on the substrate 10 and improve crystallinity.

Further, the gas supply nozzle 12 having a structure as shown in FIG. The gas supply nozzle 12 of FIG. 3A is provided with a structure for reducing collisions between the source gases before reaching the substrate 10 from the gas supply nozzle 12. Specifically, the gas supply nozzle 12 shown in FIG. 3A is supplied with an inert gas in addition to the supply pipes 24 and 25 for supplying the first and second source gases. A tube 27 is provided. Further, the ejection surface 21 has a slit shape for ejecting an inert gas between a row of ejection ports 22 that eject the first source gas and a row of ejection ports 23 that eject the second source gas. A spout 26 is provided. The inert gas supplied from the supply pipe 27 is guided to the slit-like outlet 26 without being mixed with the first and second source gases. In this way, by ejecting the inert gas from the slit-shaped ejection port 26, the first source gas layer 32 ejected from the row of the ejection ports 22 and the ejection port 23 as shown in FIG. An inert gas layer 36 is sandwiched between the second source gas layer 33 and the second source gas layer 33. Therefore, even if a collision occurs with a probability determined by the mean free path, the first source gas and the second source gas are separated because the first source gas and the second source gas are separated by the inert gas layer. The probability of colliding with will drop significantly. Accordingly, even when the pressure in the vacuum vessel 13 is set to a pressure in the submolecular flow region (10 ⁻² torr or more and 10 torr or less), the reaction product is caused by collision between the source gases in the space in front of the substrate 10. Probability of occurrence can be reduced, and epitaxial growth can be performed better.

Further, the gas supply nozzle 12 having the structure shown in FIG. 7 can be used. As shown in FIG. 7, the gas supply nozzle 12 of FIG. 7 reduces the collision between the source gases until reaching the substrate 10 from the gas supply nozzle 12, as shown in FIG. And a separation plate 71 made of quartz is disposed between the second raw material gas outlet 23. The length of the separation plate 71 is set to about ½ of the distance L from the gas supply nozzle 12 to the substrate 10. Thereby, the collision frequency between the source gases until reaching the substrate 10 can be reduced to about ½, and the generation of reaction products in the space in front of the substrate 10 can be reduced.
(Second Embodiment)

  Next, a semiconductor manufacturing apparatus according to the second embodiment will be described with reference to FIG. The apparatus shown in FIG. 4 is a multi-sheet MOCVD apparatus. In the MOCVD apparatus of FIG. 4, parts having the same functions as those of the MOCVD apparatus of FIG.

  The MOCVD apparatus shown in FIG. 4 includes a susceptor 11 on which six substrates 10 can be mounted as shown in FIG. The susceptor 11 has a structure in which each of the substrates 10 is rotated by a cam mechanism disposed in the susceptor 11 at the same time as the entire susceptor 11 is rotated by transmitting a rotational driving force by the rotational driving mechanism 18. .

At the center of the susceptor 11, a center spacer 41 for changing the direction of the flow of the source gas reflected by the substrate 10 upward is disposed. The shape of the spacer 41 is a truncated cone shape obtained by horizontally cutting the apex of the cone, and the outer peripheral surface thereof is a curved surface in which the generatrix draws an arc. Therefore, the flow of the source gas that has not reacted on the substrate 10 can be raised along the outer peripheral surface of the center spacer 41. Thereby, even if there is a flow of the source gas traveling in an irregular direction, the substrate 10 positioned on the opposite side across the center is not reached. When the pressure in the vacuum vessel 13 is set to 10 ⁻² torr or less, the source gas is reflected at the same angle as the incident angle on the surface of the substrate 10, so that the control of the traveling direction is easy, and the center spacer 41 is It is not necessary to use it. When the pressure in the vacuum vessel 13 is set to be greater than 10 ⁻² torr and less than or equal to 10 torr, it is desirable to dispose a center spacer 41 and control the traveling direction of the source gas.

  The gas supply nozzle 12 has the same configuration as the gas supply nozzle 12 shown in FIG. 2A, FIG. 2B, FIG. 3 or FIG. 7 of the first embodiment. The gas supply nozzle 12 is arranged along the outer periphery of the susceptor 11. The ejection surface 21 is directed so that the source gas is incident on the substrate 10 at an incident angle θ1 = 45 °. Therefore, the gas ejection nozzle 12 of the present embodiment uniformly irradiates the substrate 10 with the flow of the first and second source gases from the entire outer periphery of the susceptor 11. As shown in FIGS. 2A, 2 </ b> B, and 3, the ejection surface 21 includes a row of ejection ports 22 that eject the first source gas and a row of ejection ports 23 that eject the second source gas. Are arranged alternately. When the gas supply nozzle 12 of FIG. 3 is used, an inert gas jet 26 is further disposed between the jets 22 and 23.

  A spacer 42 is disposed below the gas ejection nozzle 12 so as not to cause a reservoir of source gas. The material of the spacer 42 is stainless steel, quartz or ceramics. By arranging the spacer 42 and preventing gas accumulation, it is possible to prevent reaction products and intermediate products from being formed under the gas ejection nozzle 12 and moving on the substrate 10 to hinder epitaxial growth. An effect is obtained. In addition, when the type of the source gas is changed, there is an effect of preventing a delay in the exchange of the source gas due to the gas reservoir. Since the flow of the raw material gas comes into contact with the spacer 42, it is desirable to set the temperature to be the same as that of the gas supply nozzle 12. For this purpose, it is desirable to provide a temperature adjusting mechanism such as a water cooling mechanism in the spacer 42.

  The vacuum vessel 13 has a diameter equivalent to the diameter (2 × r) of the region where the substrate 10 of the susceptor 11 is disposed. In the multi-plate MOCVD apparatus of FIG. 4, the first and second source gases are irradiated toward the substrate 10 from the entire outer periphery of the susceptor 11. Proceed toward the entire outer circumferential direction. Therefore, in the MOCVD apparatus of FIG. 4, the height of the ceiling 43 of the vacuum vessel 13 is increased, and the vertical and smooth side wall 44 is provided, and the uppermost part (three places) of the side wall 44 is circumferentially arranged. Three exhaust ports 14 are arranged at equal angles. As a result, the raw material gas that has not reacted at the substrate 10 is reflected while partially adhering to the side wall 44, reaches the vicinity of the ceiling 43, and is exhausted through the three exhaust ports 14. Since the source gas travels toward the exhaust port 14 while being reflected by the side wall 44, the straight traveling energy is weakened, so that the traveling direction is changed by the exhaust force of the exhaust port 14 and is taken into the exhaust port 14. Accordingly, since the source gas does not collide with the ceiling 43 with a large amount of energy traveling straight, the phenomenon that the source gas is reflected by the ceiling 43 and returned to the substrate 10 can be prevented. For this reason, it is desirable that the height of the ceiling 43 is high. Specifically, the height H from the position of the substrate 10 of the vacuum vessel 13 to the ceiling 43 is designed to satisfy H ≧ 3 × r. Is desirable. (Where r is the radius of the vacuum vessel 13). Further, the diameter of the exhaust port 14 is preferably not less than r.

  The three exhaust ports 14 are connected to introduction pipes 115a and 115b, respectively, and a vacuum exhaust device 16 is attached thereto. The direction of the introduction pipes 115a and 115b can be parallel to the flow direction of the source gas as in the introduction pipe 115a in FIG. 4, or can be oriented in the horizontal direction as in the introduction pipe 115b. is there. When reaching the introduction pipes 115a and 115b, most of the raw material gas has weakened straight energy, so that even the horizontal introduction pipe 115b can be exhausted well.

  A plurality of windows 19 are arranged on the ceiling 43 of the vacuum vessel. The window 19 is irradiated with light on the substrate 10 and the reflected light is received to measure the film thickness on the substrate 10, and the reaction of the source gas on the substrate 10 is promoted or migrated. It is possible to arrange a light source for irradiating ultraviolet light or infrared light to promote the above.

  A procedure for forming a ZnO crystal layer on the substrate 10 using the multi-plate MOCVD apparatus of the second embodiment will be briefly described. The substrate 10 and the type of source gas used are the same as those in the first embodiment. On the susceptor 11, it is mounted on six substrates 10, evacuated, the substrate 10 is heated to a predetermined temperature, and the first and second source gases are discharged from the gas supply nozzle 12. The first and second source gases travel straight from the entire outer peripheral direction of the susceptor 11 toward the substrate 10 and enter the substrate 10 at an incident angle of 45 °. As a result, the first and second source gases collide and react on the substrate 10 to generate ZnO. ZnO is epitaxially grown on the substrate 10. The source gas that has not reacted on the substrate 10 rises along the side surface of the center spacer 41, proceeds upward while being reflected by the smooth side wall 44 of the vacuum vessel 13, is taken into the exhaust port 14, and is evacuated to the vacuum exhaust device 16. Exhausted by Since the height H of the ceiling 43 is designed so that H ≧ 3 × r (where r is the radius of the vacuum vessel 13), the raw material gas that has reached the vicinity of the ceiling 43 has already weakened the energy of traveling straight ahead, Even if it collides with the ceiling 43, the reflected source gas does not reach the substrate 10 again. Because of such a configuration, even in a multi-plate MOCVD apparatus, the source gas that has not reacted on the substrate 10 can be exhausted without returning to the substrate 10, so that a plurality of substrates 10 can be discharged at once. It is possible to cause epitaxial growth.

As in the first embodiment, the pressure in the vacuum vessel 13 is desirably 10 ⁻⁴ torr to 10 torr, more preferably 5 torr or less, and still more preferably 0.01 to 3 torr. is there. When the pressure is set to 0.01 torr to 10 torr, the behavior as a viscous fluid also appears. Therefore, it is desirable to arrange the guide plate 61 on the upper part of the gas supply nozzle 12 as shown in FIG. Thereby, even if the raw material gas discharged from the gas supply nozzle 12 shows a convection phenomenon toward the upper part due to the behavior of the viscous fluid, it can be suppressed by the guide plate 61 and directed toward the substrate 10. Is possible.

  In addition, as shown in FIG. 8, a plurality of adhesion plates 81 can be arranged inside the side wall 44 of the vacuum vessel 13. Each of the adhering plates 81 is disposed so as to make a round along the circumferential direction of the side wall 44. The main plane of the adhesion plate 81 is oriented so as to be orthogonal to the flow of the source gas reflected by the substrate 10. Thereby, the source gas that has not caused a reaction on the substrate 10 can collide with the adhesion plate 81 and react on the adhesion plate 81 to adhere and capture the reaction product. An effect of reducing the adhesion of reaction products in the vacuum exhaust device 16 is obtained.

  Similarly, as shown in FIG. 9, it is possible to attach a suction jacket 91 inside the side wall 44 of the vacuum vessel 13. The adsorption jacket 91 has a structure in which cooling water is supplied from the outside to the inside of the vacuum vessel 13 through pipes 92 and 93 to be cooled. Thereby, when the gas which did not react on the board | substrate 10 collides with a cooling jacket, it can cool and adhere, and can be trapped. Therefore, the effect of reducing adhesion of reaction products in the vacuum exhaust device 16 can be obtained.

  Further, in the multi-plate MOCVD apparatus according to the second embodiment, the direction of the gas supply nozzle 12 is set so that the incident angle θ1 of the gas flow to the substrate 10 is 45 degrees or more as in the apparatus of FIG. It is also possible to arrange the exhaust port 14 in the direction of the reflection angle of the source gas by the substrate 10. In this case, as in the first embodiment, the source gas reflected by the substrate 10 can be directly incident on the exhaust port 14 to be exhausted.

  In the first and second embodiments, the MOCVD apparatus shown in FIGS. 1, 4, and 8 to 10 has the gas supply nozzle 12 and the vacuum exhaust device 16 disposed above the susceptor 11. Although the configuration, the present invention is not limited to this arrangement. Of course, the MOCVD apparatus can be inverted and the gas supply nozzle 12 and the vacuum exhaust apparatus 16 can be arranged below the susceptor 11.

As described above, by using the MOCVD apparatus according to the first and second embodiments of the present invention, by performing the MOCVD method while controlling the flow of the source gas at 10 ⁻⁴ torr to 10 torr, II-VI Even a compound semiconductor having a high reactivity of the source gas such as a group compound semiconductor can be epitaxially grown. A compound semiconductor layer obtained by this method has higher crystallinity than a compound semiconductor layer obtained by the MBE method or the like, and is suitable for use in an optical element or the like.

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Susceptor, 12 ... Gas supply nozzle, 13 ... Vacuum container, 14 ... Exhaust port, 15 ... Introducing pipe, 16 ... Vacuum exhaust apparatus, 17 ... Heater, 18 ... Rotation drive mechanism, 19 ... Window, 21 DESCRIPTION OF SYMBOLS ... Ejection surface, 22 ... First source gas outlet, 23 ... Second source gas outlet, 24 ... First source gas supply pipe, 25 ... Second source gas supply pipe, 26 ... Inert gas slit-like outlet, 27 ... inert gas supply pipe, 32 ... first source gas layer, 33 ... second source gas layer, 36 ... inert gas layer, 41 ... center spacer, 42 ... Spacer, 43 ... ceiling, 44 ... side wall, 45 ... sensor, 61 ... induction plate, 71 ... separation plate, 81 ... adhesion plate, 91 ... adsorption jacket.

Claims (6)

A vacuum vessel;
A substrate mounting portion for disposing the substrate in the vacuum vessel;
A gas supply unit for ejecting two or more source gases to the substrate;
Anda exhaust port provided in the vacuum vessel to evacuate the gas in the vacuum chamber,
The gas supply unit is disposed at a position for ejecting the source gas from an oblique direction with respect to the substrate surface, and has a plurality of first ejection ports arranged in a row for ejecting the first source gas. And a plurality of second jet nozzles arranged in a row for jetting the second source gas, and the row of first jet nozzles and the row of second jet nozzles are arranged alternately. Has been
The exhaust port uses a semiconductor manufacturing apparatus disposed at a position where the source gas is reflected unreacted on the substrate and is reflected by a side wall of the vacuum vessel.
A step of setting the pressure in the submolecular flow region in the vacuum vessel;
And a step of growing a ZnO single crystal by ejecting the first source gas and the second source gas onto the substrate.   2. The method for producing a ZnO semiconductor single crystal layer according to claim 1, wherein an angle formed by the gas supply unit and the substrate is 30 ° or more and 70 ° or less.   3. The method for producing a ZnO semiconductor single crystal layer according to claim 1, wherein a distance between the source gas ejection surface of the gas supply unit and the substrate is 30 mm or more and 200 mm or less.   The gas supply unit ejects an inert gas layer that separates a first source gas layer ejected from the first ejection port and a second source gas layer ejected from the second ejection port. Therefore, the ZnO semiconductor unit according to any one of claims 1 to 3, further comprising an inert gas jet port disposed between the first jet port and the second jet port. Crystal layer manufacturing method.   The separation plate for reducing the collision between raw material gas is further attached between the said 1st line-shaped jet nozzle and the 2nd line-shaped jet nozzle, The thru | or 1 characterized by the above-mentioned. 4. The method for producing a ZnO semiconductor single crystal layer according to claim 1.   The substrate mounting portion can mount a plurality of the substrates, and a projection for controlling the direction of the gas reflected on the substrate surface is provided at a central portion of the substrate mounting portion. Item 6. The method for producing a ZnO semiconductor single crystal layer according to any one of Items 1 to 5.

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