JP3168277B2 - Semiconductor crystal growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor crystal growth apparatus for growing a thin film crystal on a substrate, and in particular, it is possible to greatly improve the utilization efficiency of a source gas and to form an excellent semiconductor layer. And a safe and reliable semiconductor crystal growth apparatus.

[0002]

2. Description of the Related Art Vacuum chemical epitaxy (VCE), which combines the advantages of molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD), is known as a method for producing a group III-V compound (for example, GaAs) semiconductor. . This VCE method is shown, for example, in FIG.
A group III-V compound is produced using an apparatus as shown in JP-A-1-257322. That is, in the figure, the growth chamber 21 is maintained in a vacuum state, the reaction chamber 22 is installed in the growth chamber 21, and a plurality of nozzle holes 24 are provided at regular intervals in the bottom 23 thereof. Discharge ports 25 are provided at regular intervals along the edge on the outer peripheral portion of. The ceiling 26 is freely detachable from the lower side of the reaction chamber 22, a substrate 27 is fixed at the center thereof, and a pipe 28 reacts with a V-group compound sent from a discharge port. The liquid is discharged into the chamber 22. Also,
Above the reaction chamber, a soaking plate 30 and a substrate heating heater 29 are provided. Further, a mixing chamber 32 provided with a plurality of nozzle ports 31 communicating with the nozzle ports 24 is connected to the lower surface of the reaction chamber 22, and two mixing ports 32 connected to the upper side and the lower side of the mixing chamber 32, respectively. III sent inside via pipes A and B
A group compound and a dopant are mixed, and the mixture is discharged from the nozzle holes 31 and 24 toward the substrate 27.
In addition, a vacuum pump (not shown) is provided below the growth chamber 21 to discharge the unreacted gas downward through the outlet 25. With such a configuration, the substrate 27
A semiconductor layer is formed on the lower surface of the substrate.

[0003]

However, in the conventional apparatus as described above, the bottom portion 23 and the peripheral portion of the reaction chamber form a hot wall due to heat radiation by the substrate heater 29, so that adsorption of the source gas does not occur. However, since the reaction chamber itself does not have a temperature control mechanism, the reaction gas and unreacted gas may be adsorbed to the reaction chamber bottom portion 23 and the peripheral portion depending on the type of gas used.
Also, since there is no substrate rotation mechanism, there is almost no problem in growing at a pressure lower than the intermediate flow region, but when growing at a high pressure close to the viscous flow region, the temperature,
In order to obtain excellent uniformity, it is difficult to control the gas pressure on the surface of the substrate because the distribution of the gas flow tends to occur, and since the distance between the substrate holding plate and the nozzle at the bottom of the reaction chamber is constant, it is difficult to control the gas pressure on the substrate surface. The range of the growth pressure used is limited. In addition, the utilization efficiency of the source gas used is about 20%.
Although it is extremely high for a CVD system, it still emits 80% of harmful exhaust gas, and it is desired to achieve a higher source gas utilization efficiency from the viewpoint of reducing the load on the exhaust system pump and the problem of exhaust gas treatment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to greatly improve the utilization efficiency of a source gas, to enable the formation of an excellent semiconductor layer, and to improve the safety. And to provide a highly reliable semiconductor crystal growth apparatus.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a growth tank for covering a substrate, a heating device for heating the substrate, an exhaust device for evacuating the growth tank to an ultra-high vacuum, In a semiconductor crystal growth apparatus provided with a gas supply control device for supplying a gas containing a component to be grown on a substrate at a predetermined flow rate and time, a substrate holding portion and a reactor portion facing the substrate are provided inside the growth tank. Reaction chamber,
In addition, the present invention can be attained by providing a semiconductor crystal growing apparatus characterized in that the temperature of the reactor section can be controlled independently. In addition, a nozzle is provided in the reactor to discharge the gas uniformly on the substrate, and further, a substrate rotation mechanism and a moving mechanism for moving the substrate holding part forward and backward with respect to the reactor are provided. Results can be obtained.

[0006]

According to the semiconductor crystal growth apparatus having the above-mentioned structure, the utilization efficiency of the source gas is greatly improved by forming a hot wall by controlling the temperature of a small reaction chamber and heating and rotating the substrate. The above gas flow can be made uniform. Further, the crystal growth conditions such as the distance between the substrate and the reaction gas discharge port and the pressure of the reaction chamber can be optimized, and the gas pressure in the reaction chamber can be controlled within a high pressure range. As a result, the use efficiency of the source gas, the uniformity of the thin film grown on the substrate and the controllability of the gas pressure on the substrate surface are remarkably improved, so that the amount of unreacted gas is small, the safety is excellent, and the film growth Can be shortened.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The semiconductor crystal growth apparatus of the present invention will be more specifically described below with reference to embodiments. FIG. 1 shows the configuration of an embodiment of the apparatus of the present invention. In the figure, reference numeral 1 denotes a growth tank, in which a reaction chamber 2 is provided. The reaction chamber 2 is provided with several nozzles 4 for supplying a reaction gas, and has a spherical or elliptical bottom surface made of a molybdenum reactor section 3. The volume of the reaction chamber 2 can be freely changed. And a substrate holding plate 5. A GaAs substrate 6 is detachably mounted on the substrate holding plate 5 at the center thereof, with the GaAs substrate 6 supported on a step provided on the inner peripheral edge of the center hole with the surface facing down. Above the substrate holding plate 5, a driving mechanism 9 for vertically moving or rotating the substrate heating heater 7, the heat shield plate 8, and the substrate holding plate 5 is provided. Also,
Group V compound gas such as arsine (As
A reaction gas supply pipe 10 for feeding H ₃ ) or the like is connected, and a gas discharge hole 11 for discharging a gas to the substrate in a uniform distribution state is provided at a tip of the reaction gas supply pipe 10. On the other hand, a heater 12 using a carbon heater or the like (three-layer structure) laminated with pyrolytic boron nitride (pBN), which is stable against the reaction gas, is provided below the reactor 3 and measured with a thermocouple or the like. While controlling the temperature of the reactor 3 independently. A gas supply chamber 13 for supplying a reaction gas is provided below the heater 12, and a group III compound gas such as an organic metal gas such as trimethylgallium (TMGa) or triethylgallium (TEGa) is supplied to the reaction gas. The substrate 6 is fed from the supply pipe 14 b and is passed through the nozzle 4 communicating with the reaction chamber 2.
Are discharged in a uniform distribution toward. Further, the gas supply chamber 13 is provided with a water channel 15, a cooling water inlet pipe 16, and a cooling water outlet pipe 17, so that the reactor 3 and the nozzle 4 can be cooled by conduction.

Next, the operation of forming a thin film using the apparatus of the present invention will be described. First, a pressure of 10 to ⁷ Tor
r and a substrate 6 with a heater 7
To 300-650 ° C. Next, in order to set the pressure in the reaction chamber 2 suitable for layer growth, the substrate holding plate 5 is moved to set the space volume of the reaction chamber 2 to a predetermined volume. In this state, a group III compound gas such as TMGa, T
At the same time, an organic metal gas such as EGa is discharged from the nozzle 4 toward the substrate 6 in a uniform distribution state through the reaction gas supply pipe 14b, and a V group compound gas such as AsH _{3 is} supplied to the reaction gas supply pipe 1b.
Excessive discharge into the reaction chamber 2 through 0. As a result,
A layer of gallium arsenide or the like can be grown on the substrate 6. On the other hand, the group V compound gas supplied to the reaction chamber 2 flows while diffusing into the discharge port 18 between the substrate holding plate 5 and the reaction chamber along with the group III compound gas across the substrate 6 to exhaust the growth tank. Exhausted by a large pump.

At this time, the temperature of the reactor 3 is set to an optimum temperature for the component gas of the growth layer, and a hot wall is formed. The periphery of the nozzle 4 is cooled so that the supplied compound gas (organic metal gas) does not decompose. For example, TM
In the case of Ga, the temperature is controlled to 150 ° C or less. by this,
Adsorption of the compound gas to be supplied to the bottom surface, the peripheral wall portion, and the like of the reactor 3 is eliminated, so that the reflection efficiency of the reaction gas can be promoted, and the reaction gas can be used effectively. The temperature of the reactor 3 is in the range of 100 to 650 ° C. In addition, experiments conducted by the inventors have revealed that the use of molybdenum as a material for forming the reaction chamber makes it difficult to cause a reaction with the compound gas. The reaction gas utilization efficiency is improved by about 3 to 4 times (that is, up to 70 to 80%) as compared with the case of using conventional carbon graphite or SiC-coated carbon graphite. The same effect can be obtained when using a high melting point metal such as tungsten or tantalum or stainless steel subjected to surface nitriding.

After completion of the crystal growth, the substrate holding plate 5 is moved upward by the driving mechanism 9 and the substrate holding plate 5 and the reactor 3 are moved.
Unreacted gas in the reaction chamber 2 is exhausted at a high speed from the gap between the reaction gas and the reaction gas.
Thereby, the pressure in the reaction chamber 2 can be switched at high speed.

By repeating the above series of operations, a thin film can be formed on the substrate surface in units of atomic layers. In addition, the formation of the heterostructure atomic layer using two or more different gases can be realized by synchronizing the high-speed switching of the pressure in the reaction chamber 2 by the driving mechanism 9 with the switching of the reaction gas.

Next, one embodiment of the reactor shape is shown in FIG. In the example of FIG. 2, the surface of the reactor is made to have a wavefront shape. By making the surface corrugated, the reflection efficiency of heat and gas is further improved, and the formation of a hot wall can prevent the compound gas from adsorbing on the wall surface, thereby increasing the utilization efficiency of the source gas. As a result, the load on the exhaust system pump can be reduced, and a device with high safety and high operation rate can be provided. Needless to say, this leads to cost reduction of expensive raw material gas.

[0013]

As described above, by using the semiconductor crystal growth apparatus of the present invention as an apparatus according to the present invention, the problems of the prior art can be solved and the utilization efficiency of the source gas can be greatly improved. Thus, an excellent semiconductor layer can be formed, and a safe and reliable semiconductor crystal growth apparatus can be provided.

Specifically, the following effects can be obtained. (1) A reactor having a spherical or elliptical bottom surface in a reaction chamber, and a highly uniform thin-film crystal can be formed by a hot wall configuration by controlling the temperature of the reactor. (2) The reaction gas utilization efficiency should be about 70 to 80%. (3) The substrate temperature and the gas flow on the substrate can be made uniform by rotating the substrate holding unit. (4) The unreacted toxic gas can be reduced by improving the utilization efficiency of (2), and the load on the exhaust pump and the like can be greatly reduced, so that the pump life can be improved.

(5) Since the consumption of the raw material gas can be greatly reduced, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a semiconductor crystal growth apparatus of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of an embodiment (a surface having a corrugated surface) of a reactor section of the apparatus of the present invention.

FIG. 3 is a sectional view showing a schematic configuration of a conventional vacuum chemical epitaxy (VCE) apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Growth tank, 2 ... Reaction chamber, 3 ... Reactor, 4 ... Peripheral wall, 5
... substrate holding plate, 6 ... substrate, 7 ... substrate heater, 8 ... heat shield plate, 9 ... drive mechanism, 10 ... reaction gas supply pipe, 11 ...
Gas discharge hole, 12 ... heater, 13 ... gas supply chamber, 14 ... reaction gas supply pipe, 15 ... water channel, 16 ... cooling water inlet, 17 ... cooling water outlet, 18 ... outlet, 21 ... growth chamber, 22 ... Reaction chamber, 23: bottom, 24: nozzle hole, 25: outlet, 26: ceiling, 27: substrate, 28: pipe, 29: heater, 30: soaking plate, 31: nozzle hole, 32: mixing chamber.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Noriyuki Omori 2-6-40 Chikushinmachi, Sakai City, Osaka Daido Oxygen Co., Ltd. Sakai Plant (56) References JP-A-2-311 (JP, A) Kaihei 5-74705 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 C30B 25/10 C30B 25/14

Claims (5)

(57) [Claims] 1. A growth tank for covering a substrate, a heating device for heating the substrate, an exhaust device for evacuating the growth tank to an ultra-high vacuum, and a component to be grown on an internal substrate from outside the growth tank. In a semiconductor crystal growth apparatus provided with a gas supply control device that supplies a gas containing gas at a predetermined flow rate and time, a reaction chamber including a substrate holding unit and a reactor unit facing the substrate is provided inside the growth tank, and A semiconductor crystal growth apparatus, wherein the temperature of the reactor section can be controlled independently. 2. The semiconductor crystal growth apparatus according to claim 1, wherein a bottom surface of said reactor portion is spherical or elliptical. 3. The semiconductor crystal growth apparatus according to claim 1, wherein the surface of the reactor section whose bottom surface is spherical or elliptical has a wavefront shape. 4. A method according to claim 1, wherein said reactor is made of molybdenum, and said substrate holder is made of any one of molybdenum, tantalum, tungsten and stainless steel subjected to surface nitriding. Semiconductor crystal growth equipment. 5. The apparatus according to claim 1, wherein a rotation mechanism is provided in said substrate holding section, and a gas pressure on a substrate surface is controlled by moving said substrate holding section forward and backward. Semiconductor crystal growth equipment.