JPH0831415B2 - Semiconductor manufacturing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor manufacturing apparatus for growing a compound semiconductor layer in a vacuum chamber, particularly in a vacuum chemical epitaxy (VCE) system.

[Conventional technology]

In recent years, compound semiconductors, especially III-V compounds (eg G
The demand for aAs) is increasing as it has superior performance to conventional silicon semiconductors. As a method of manufacturing such a compound semiconductor, the atoms necessary for the compound to be epitaxially grown in an ultrahigh vacuum are evaporated from a solid material by a heat gun, and this is made to collide with the substrate in the form of a molecular beam, Beam growth ([MBE] Molecular Beam Epitaxy) method for growing a film of H2O or vaporization of metal methyl or ethyl compounds is sent by carrier gas such as H ₂ and introduced into a reaction chamber under normal pressure or reduced pressure, where V Metalorganic CVD ([MOCVD] Metalorgamic C
hemical vapor deposition) method.

[Problems to be solved by the invention]

However, among the above, the molecular beam epitaxy method has a problem that it is difficult to mass-produce and it is difficult to supply as much as to meet market demand. Further, the organometallic CVD method has a higher production capacity than the above molecular beam epitaxy method, but has a problem that the reaction gas used is expensive and the utilization efficiency of the reaction gas is deteriorated due to its growth mechanism. are doing. Therefore, it is difficult to use it for any purpose other than the special purpose where high price is not a problem. Further, the above-mentioned organometallic CVD method produces a large amount of unreacted gas (toxic gas) due to the poor utilization efficiency of the reaction gas as described above, and also a large amount for the purpose of gasifying and transporting a group III compound having a low vapor pressure. Since the carrier gas such as H ₂ used for the above is added to the above unreacted gas, a large amount of toxic waste gas is generated, and there is a great problem in the disposal of this. A conventional apparatus using such a metal organic CVD method is as shown in FIG. That is, the heater 2 arranged in the vacuum chamber 1
A substrate 3 is placed on the substrate 3, and a gaseous compound for semiconductor growth is discharged toward the substrate 3 from a nozzle 4 provided on the upper side in the vacuum chamber 1 as shown by an arrow A. There is.
In this apparatus, a large volume vacuum chamber 1 is filled with a gaseous compound (reaction gas) for semiconductor growth for each treatment,
Since the waste gas is discarded after processing, the waste gas contains a considerably large amount of unreacted gas that is not involved in semiconductor growth, resulting in poor utilization efficiency of the reaction gas. Further, in the above apparatus, since the substrate 3 is placed on the heater 2 and the substrate 3 is heated from the lower side, thermal convection as shown by an arrow B occurs above the substrate 3 and the substrate heated by the heater 2 is generated. Heat dissipated from 3 is generated in the vicinity of the upper surface of substrate 3 as indicated by arrow C. As a result, the gaseous compound discharged from the nozzle 4 is pushed up by the heat convection indicated by the arrow B and the radiated heat indicated by the arrow C to disturb the flow, and uniform film growth cannot be performed on the upper surface of the substrate 3. . Therefore, the above device has a major drawback that it is difficult to finish the surface of the obtained semiconductor film (semiconductor layer) to be smooth. This defect is promoted by the fact that Ga / As particle flags generated by contact reaction in the air that cannot reach the surface of the substrate 3 due to the thermal convection of the arrow B float in the air and randomly adhere to the semiconductor film. To be done.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a semiconductor manufacturing apparatus capable of efficiently producing a high-quality semiconductor having a smooth semiconductor layer surface by combining the advantages of MBE and MOCVD.

[Means for solving problems]

In order to achieve the above object, a semiconductor manufacturing apparatus of the present invention includes a vacuum chamber capable of forming a highly vacuum, a substrate support for supporting a substrate disposed in the vacuum chamber, a reaction gas supply unit, and a substrate. In the semiconductor manufacturing apparatus provided with the heating means, a reaction chamber consisting of a bottom wall and a peripheral wall standing upright from the outer peripheral edge thereof and an upper plate for opening and closing the reaction space surrounded by the peripheral wall is provided in the vacuum chamber. A holding part for holding the substrate in contact with the reaction space is provided on the upper plate of the reaction chamber, and a reaction gas is discharged to the substrate held by the holding part on the bottom face of the reaction chamber. And a reaction gas discharge passage is provided between the peripheral wall of the reaction chamber or this peripheral wall and the upper plate, and the heating unit is positioned and arranged above the upper plate of the reaction chamber. .

[Action effect]

That is, in the semiconductor manufacturing apparatus of the present invention, the vacuum chamber is highly evacuated to increase the mean free path of the reaction gas molecules so that the gas molecules efficiently collide with the substrate as a molecular beam. A reaction chamber with a smaller volume than the chamber is newly installed, and the substrate is placed in this reaction chamber and the reaction gas is supplied to the reaction chamber to grow the semiconductor layer, so the reaction gas utilization efficiency is greatly improved. Come to do. Further, in this apparatus, even a group III compound having a low vapor pressure can be directly gasified and used as it is because the vacuum chamber is highly vacuumed, and therefore a carrier gas for gasifying and transporting the group III compound becomes unnecessary. Therefore, a small amount of gas can be disposed of after use. In addition, the upper plate that constitutes the reaction chamber holds the substrate, the reaction gas discharge part is provided at the bottom of the reaction chamber, and the heater is provided above the upper plate of the reaction chamber so that the reaction gas discharged into the reaction chamber is heated. Since it is not affected by convection or the like, it becomes possible to form a semiconductor layer having an extremely smooth surface.

Next, the present invention will be described in detail based on examples.

〔Example〕

1 to 4 show a semiconductor manufacturing apparatus according to an embodiment of the present invention. In these drawings, 200 is a vacuum chamber in a vacuum chemical epitaxy system, and the reaction chamber 10 is provided in the vacuum chamber 200. The reaction chamber 10 has a square plate-like floor plate 12, a peripheral wall 16 extending upward from the four peripheral edges of the square plate-like floor plate 12, and a slidable state in one direction on the upper end of the peripheral wall 16. It is composed of the upper plate 18 placed on. The upper plate 18 is provided with two holes 18a at the center thereof, and the disk-shaped GaAs substrate 300 is provided in each of the holes 18a.
It is detachably attached to the stepped portion 18b provided on the inner peripheral edge of the hole portion 18a with its surface facing downward. The upper plate 18 has both right and left side edges bent downward, and the bent portion is a slide step portion provided inside a pair of left and right peripheral walls 16 among the peripheral walls 16 of the four sides. By being supported by 16a, it is possible to slide toward the substrate attaching / detaching chamber 50 (see FIG. 4) that is connected to the vacuum chamber 200. In FIG. 4, 51 is a valve from the substrate mounting / demounting chamber 50.
With a magic hand that opens 52 and extends into the vacuum chamber 200, the upper plate 18 is slidably moved in a state of sandwiching the curved portion of the upper plate 18, and the upper plate 18 is properly attached to and detached from the reaction chamber 10. Reference numeral 53 is a vacuum pump that brings the substrate attaching / detaching chamber 50 into a vacuum state similar to that of the vacuum chamber 200 before opening the valve 52. An exhaust port 20 is provided on the peripheral wall of the reaction chamber 10 along the outer periphery with a predetermined gap so that unreacted gas or excess reaction gas in the reaction chamber 10 is discharged to the vacuum chamber 10. The total area of these exhaust ports 20 is set to approximately 4% of the area of the upper plate 18 of the reaction chamber 10. 14 are fixed intervals (25.
4 mm) and a 3.2 mm diameter nozzle hole formed so as to be perpendicular to the substrate 300 (it becomes a conical shape in the opposite direction from the lower side to the upper side, and the reaction gas is uniformly discharged. ), Which communicates with the hole 26 or 34 formed in the ceiling of the first mixing chamber 24 disposed below the reaction chamber 10. As shown in FIG. 5, the same number of holes 26 and 34 are arranged alternately, the holes 26 communicate with the inside of the first mixing chamber 24, and the holes 34 inside the first mixing chamber 24. A second mixing chamber provided below the mixing chamber 24 via a duct 32 penetrating therethrough.
It communicates with 30. As shown in FIG. 2, the raw material injection pipe 22 communicates with the inside of the first mixing chamber 24 through the side wall,
A group III compound (reaction gas) such as trimethylgallium (TMGa) or triethylgallium (TEGa) is fed into the first mixing chamber 24 from the raw material injection pipe 22, and the n-type and p-type dopants are used alone or as described above. It is fed into the first mixing chamber 24 together with the group III compound. The compound or the like is uniformly mixed in the first mixing chamber 24, then passes through the holes 26 and the nozzle holes 14, and is discharged toward the substrate 300 arranged above in a uniform distribution state. Further, the second mixing chamber 30 has an opening on the lower side, and an exhaust valve 36, which is a poppet valve for opening and closing the opening, is provided at the opening so as to be able to move forward and backward. A raw material injection pipe 28 is connected to the side wall of the second mixing chamber 30. From the raw material injection pipe 28, n-type and p-type dopants or group III compounds such as triethylaluminum (TEAl) are fed into the second mixing chamber 30. The group III compound is uniformly mixed in the second mixing chamber 30 and the duct 32, and then discharged from the nozzle hole 14 toward the substrate 300 through the hole 34 in a uniform distribution state. In addition,
The duct 32 serves as a flow resistance of the reaction gas in the first mixing chamber 24 and has a stirring action, which contributes to improvement of the mixing property of the reaction gas in the first mixing chamber 24. The first and second mixing chambers 24 and 30 are made of a stainless steel block integrally formed and are supported by a stainless steel support 40. 42 is V such as AsH ₃
A supply pipe for supplying a group compound (reaction gas) into the reaction chamber 10. The supply pipe is arranged at a position on the floor plate 12 where the holes 26 and 34 are divided into two equal numbers on the left and right sides as shown in FIG. . A plurality of holes 42a and a plurality of holes 42b are formed in the supply pipe 42 in two rows on the left and right sides with a constant interval. As a result, the group V compound is supplied into the reaction chamber 10 in a uniform distribution state. 44 is a heater disposed above the upper plate 18 of the reaction chamber 10, and 44c is a soaking plate, which heats the substrate 300 mainly from the top by axial heat, so that the substrate 300 has a semiconductor compound on its surface. At the same time as heating the silicon to a temperature at which it can grow, the heating allows the semiconductor layer to grow uniformly on the surface of the substrate 300 without being affected by thermal convection or the like. As shown in FIG. 1 (b), the heater 44 is configured by alternately providing streak cuts 44a in a plate-like carbon graphite and attaching electrodes 44b at both ends. The heater 44 is capable of uniformly heating the surface, but the uniform heating plate 44c provided below the heater 44 makes the surface heating more uniform.

In operation, in order to grow and form the MESFET epitaxy layer, the upper plate 18 with the substrate 300 (the surface of which is on the lower side) is attached to the reaction chamber 10 as shown in FIG.
The inside is brought to a vacuum state having a degree of vacuum of 10 ⁻⁷ Torr, and an electric charge is applied to the heater 44 to heat the heater 44 to heat the atmosphere temperature to 650 ° C. In that state, the substrate 300 is heated for about 15 minutes. Then, from the raw material injection pipe 22 of the reaction chamber 10, trimethylgallium (TMGa), triethylgallium (TEGa), etc.
After the group III compound (reaction gas) is fed into the first mixing chamber 24 and mixed in the mixing chamber 24 in a uniform state, it is discharged from the nozzle holes 14 toward the surface of the substrate 300 in a uniform distribution state, and at the same time, A group V compound (reaction gas) such as AsH ₃ or alkylarsine, for example, triethylarsine (TEAs) is fed into the supply pipe 42, and is excessively discharged into the reaction chamber 10 through the holes 42a and 42b. As a result, the group V compound supplied into the reaction chamber 10 flows along the group III compound and the like across the surface of the substrate 300 toward the exhaust port 20 while diffusing. In the meantime, AsH ₃ and TEAs are thermally decomposed to As ₂ and come into contact with the surface of the substrate 300 together with gallium of the above-mentioned gallium compound and grow as an undoped gallium arsenide (GaAs) layer. In addition, the unreacted compound that does not come into contact with the substrate 300 is discharged to the outside through the exhaust port 20, and the vacuum chamber 200
Is sucked in by the exhaust means. The GaAs layer is preferably grown at a growth rate of about 2 μm per hour, and is preferably formed to have a thickness of about 10 ⁴ Å. In this case, the impurity concentration in the undoped GaAs layer is 1 × 10.
It is preferably set to ¹⁵ atoms / cm ³ or less. Next, an n-type dopant is discharged from the second mixing chamber 30 into the reaction chamber 10 together with the group III or group V compound, or alone, to form an n-type dopant on the surface of the undoped GaAs layer.
Growing the mold active layer. This n-type active layer has a thickness of about 2 μm / hour.
It is preferable to grow at a growth rate of m, the thickness is 2 × 10 ³ Å, and the concentration of the n-type dopant therein is approximately 2 × 1.
It is preferable that the concentration is 0 ¹⁷ atoms / cm ³ . After that, the gas supply is stopped for about 15 minutes. Then, after cooling the substrate 300, the reaction chamber (vacuum chamber 20
0) Take out from 10. This extraction is performed as follows. That is, the degree of vacuum in the substrate attachment / detachment chamber 50 is increased to the same level as the vacuum chamber 200, the valve 52 is then opened, and the magic hand 51 is extended to grasp the upper plate 18 (having the substrate 300) of the reaction chamber 10 Then, the magic hand 51 is retracted and the upper plate 18 is slid to be removed from the peripheral wall 16 of the reaction chamber 10 and accommodated in the substrate attachment / detachment chamber 50. Then, the taken-out substrate 300 is provided with a signal source electrode, a drain electrode and a gate electrode by known means. In this way, a III-V compound semiconductor having a uniform MESFET semiconductor layer can be obtained.

Next, the growth and formation of the HEMT epitaxy layer is performed by ejecting the group III compound from the first mixing chamber 24 into the reaction chamber 10 and ejecting the group V compound from the supply pipe 42 onto the substrate 300 as described above. To grow an undoped GaAs layer,
In addition to the group III compound and the group V compound, a group III compound containing Al such as triethylaluminum (TEAl) is supplied from the second mixing chamber 30 to grow a HEMT epitaxy layer made of AlGaAs. Next, the n-type dopant is discharged into the reaction chamber 10 together with the Al-containing group III compound, and the n-type AlGaAs layer is grown on the AlGaAs layer. After that, the supply of the Al-containing group III compound is stopped and the n-type GaAs layer containing the n-type dopant is grown. In this way HEMT
An epitaxy layer is grown and formed.

In the above-mentioned device, the substrate 300 from the nozzle hole 14
Is shorter than the mean free path of the gas molecules of the group III compound in the vacuum state (the distance traveled until the gas molecules collide with other molecules and react), and the compound to the surface of the substrate 300 Set so that the dispersed state of is uniform. Explaining this in more detail, the substrate 300 is arranged at a position where the circles formed at the tips of the group III compound or the like that diffuse in a conical shape from the nozzle holes 14 intersect with each other, and reach the substrate 300. The distribution state of the gas molecules and the collision speed thereof are set so that the gas molecules grow on the surface of the substrate 300 at an appropriate speed. Alternatively, the degree of vacuum in the vacuum chamber 200 and the discharge rate of the gaseous compound are adjusted in accordance with a preset distance from the nozzle hole 14 to the substrate 300, the number of the holes 26, 34 and the nozzle hole 14, Adjust the diameter etc. This makes it possible to obtain a semiconductor layer having a thickness within the specified thickness ± 5%, more preferably within the specified thickness ± 1%. Also, TEGa
In general, the reaction rate when GaAs is obtained from AsH _{3 and the} like is such that the higher the temperature of the substrate 300, the faster the reaction rate. Evaporates and reduces the layer growth rate. Therefore, the temperature of the substrate 300 is preferably 500 to 700 ° C, and particularly preferably 600 to 650 ° C. Further, the vacuum state in the reaction chamber 10 is preferably 10 ⁻⁶ Torr or less.

In addition, in the apparatus of the above-mentioned embodiment, when the mixing chamber is added, the exhaust valve 36 may be provided in the lowermost mixing chamber or each mixing chamber. Further, in the above embodiment, the exhaust port 20 is provided in the peripheral wall 16 of the reaction chamber 10, but the exhaust port 20 is not provided in the peripheral wall 16 so that the gap between the peripheral wall 16 and the upper plate 18 serves as an exhaust path. Good. Further, in the apparatus of the above embodiment and the apparatus of FIG. 1, the mixing chambers 24 and 30 are separated from each other, and different source gases are sent to the reaction chamber 10 from the nozzle holes 14 communicating with the respective mixing chambers. But
The mixing chambers 24 and 30 may be communicated with each other through holes or the like, and the raw material gases sent from the respective raw material injection pipes 22 and 28 may be mixed in the mixing chamber 24 and then sent to the reaction chamber 10. Further, a cooling jacket or the like may be provided in the mixing chamber and cooling water or the like may be sent to the mixing chamber to cool the gaseous compound to an appropriate temperature. This makes it possible to prevent the temperature of the gaseous compound from becoming excessively high and prevent the early reaction of the gaseous compound.

As described above, in the apparatus of the above-described embodiment, the heater 44 is provided on the upper plate.
The heater 44 is provided above the heater 18 to heat the substrate 300 from above, and to discharge the gaseous compound for semiconductor growth upward from below the substrate 300 toward the substrate 300.
Proper treatment can be carried out without being affected by gas convection due to heat generation, and a semiconductor layer having a high surface smoothness can be uniformly grown. Further, since the semiconductor manufacturing apparatus is capable of discharging different kinds of gaseous group III compounds and the like from the mixing chamber 24 and the mixing chamber 30 toward the substrate 300, it is possible to cut the valve like a conventional apparatus. Efficient semiconductor manufacturing can be performed without the need for replacement work. Also, the nozzle hole
No other kind of gaseous compound remains in 14 and it does not deteriorate the quality of the semiconductor obtained as an impurity. In addition, a plurality of nozzle holes 14 communicating with the mixing chambers 24 and 30 are arranged on the same plane at regular intervals, and the plurality of nozzle holes 14 are divided into two parts.
By supplying the group V compound from 42 to the reaction chamber 10 and discharging the unreacted reaction gas from the discharge port 20 to the outside of the reaction chamber 10, the reaction gas having a constant flow rate can be generated in the reaction chamber 10. Since the flow is generated, the reaction gas can be sent to the surface of the substrate 300 in a uniform state, and the semiconductor layer made of a III-V group compound can be grown in a uniform state. Further, since the exhaust valve 36 is provided in the second mixing chamber 30, it is possible to intermittently supply the gaseous compound to the substrate 300. Furthermore, the usage efficiency of the reaction gas is high and there is no need to use carrier gas, so the amount of gas used becomes small,
Processing such as disposal becomes easy.

[Brief description of drawings]

FIG. 1 (a) is a longitudinal sectional view showing a semiconductor manufacturing apparatus according to an embodiment of the present invention, FIG. 1 (b) is a plan view of the heater, and FIG. 2 is a main part of FIG. 1 (a). FIG. 3 is an enlarged view, FIG. 3 is a perspective view of the reaction chamber, FIG. 4 is a plan sectional view including a substrate supply device, and FIG. 5 is a plan view showing a distribution state of nozzle holes and supply pipes of the reaction chamber. FIG. 6 is a sectional view of a conventional example. 10 ... Reaction chamber, 12 ... Floor plate, 14 ... Nozzle hole, 16 ... Peripheral wall, 18 ... Upper plate, 18a ... Hole part, 18b ... Step part, 20 ... Exhaust port, 22, 28 ... … Raw material injection pipe, 24, 30 …… Mixing chamber, 26 ……
Hole, 32 ... Duct, 36 ... Exhaust valve, 42 ... Supply pipe, 42a,
42b ... hole, 44 ... heater, 44c ... soaking plate, 200 ... vacuum chamber, 300 ... substrate

Claims (3)

[Claims] 1. A semiconductor manufacturing apparatus provided with a vacuum chamber capable of forming a highly vacuum, a substrate supporting member for supporting a substrate arranged in the vacuum chamber, a reaction gas supply unit, and a substrate heating unit. A reaction chamber consisting of a bottom surface and a peripheral wall standing upright from the outer peripheral edge thereof and an upper plate for opening and closing the reaction space surrounded by the peripheral wall is provided in the vacuum chamber, and the upper plate of the reaction chamber is provided with a substrate. Is provided in a state of being in contact with the reaction space, and at the bottom of the reaction chamber, a reaction gas supply unit for discharging a reaction gas to the substrate held by the holding unit is provided. A semiconductor manufacturing apparatus in which a reaction gas discharge passage is provided on a peripheral wall or between the peripheral wall and an upper plate, and a heating means is positioned and arranged above the upper plate of the reaction chamber. 2. A plurality of nozzle holes for discharging a reaction gas are provided on the bottom surface of the reaction chamber, and first and second mixing chambers are provided in a multi-stage below the reaction chamber. Injecting means for injecting different reaction gases into the two mixing chambers is provided, and an outlet for introducing the reaction gas in the mixing chamber to a predetermined nozzle hole in the bottom portion of the reaction chamber is provided in the ceiling of the first mixing chamber. An outlet is provided in the ceiling of the second mixing chamber for taking out the reaction gas in the second mixing chamber, and a predetermined nozzle hole at the bottom of the reaction chamber passes through the first mixing chamber from the outlet. The semiconductor manufacturing apparatus according to claim 1, further comprising an extending reaction gas passage. 3. The reaction chamber is provided on the bottom surface of the reaction chamber so as to divide the plurality of nozzle holes for discharging the reaction gas provided on the bottom surface of the reaction chamber into groups of substantially the same number on the left and right. The semiconductor manufacturing apparatus according to claim 1, further comprising a discharge source for discharging the reaction gas.