JP3163342B2 - Semiconductor manufacturing 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 manufacturing apparatus for forming a group III-V compound semiconductor layer in a vacuum chamber, particularly in a vacuum chemical epitaxy (VCE) system.

[0002]

2. Description of the Related Art In recent years, demand for compound semiconductors, particularly III-V compounds (for example, GaAs), has been increasing as they have better performance than conventional silicon semiconductors. As a method of manufacturing such a compound semiconductor, in an ultra-high vacuum,
The atoms required for the compound to be epitaxially grown are evaporated from a solid material by a heat gun, and this is collided with a substrate in the form of a molecular beam to grow a crystal film, such as a molecular beam epitaxy (MBE) method or a metal methyl or ethyl compound. Vapor is sent by a carrier gas such as H ₂ into a reaction chamber at normal pressure or reduced pressure, where it is mixed with a group V hydrogen compound, and then reacted on a heated substrate to grow crystals. There is a law.

[0003] However, the above MBE method has a
^-11 Torr order ultra-high vacuum is required, downtime occurs when refilling raw materials, substrate rotation mechanism is required for uniform growth, etc. It is difficult to secure enough supply to meet demand. Further, since the MOCVD method is a process in a laminar flow region, distribution tends to occur in the flow direction, and it is difficult to analyze the flow at the time of scale-up.
There is a problem that the reaction gas is expensive and the utilization efficiency of the reaction gas is low due to its growth mechanism. Further, since the utilization efficiency of the reactive gas is low, a large amount of toxic gas is generated because it is added to a large amount of unreacted gas, and disposal of the toxic gas is a serious problem.

[0004] The present applicant has succeeded in developing a semiconductor manufacturing apparatus utilizing the merits by solving the mutual disadvantages by combining the above two methods, and has already filed an application (Japanese Patent Application No. 1-91651). , Filed April 10, 2001). As shown in FIG. 5, this apparatus is a substantially cylindrical body made entirely of stainless steel, and the bottom side is connected to a turbo-molecular pump (not shown) and is evacuated as shown by an arrow A to form a vacuum chamber 1 inside. It has become. A heater 2 is suspended from the ceiling in the vacuum chamber 1, and a heat equalizing plate 2a is mounted below the heater. A reaction chamber 6 including a top plate 3, a peripheral wall 4, and a bottom plate 5 is provided below the heat equalizing plate 2a, and a step portion of an opening 7 provided at the center of the top plate 3 is provided. 8, a substrate 9 is mounted downward with a holder 10 interposed therebetween. The bottom plate 5 of the reaction chamber 6 also serves as a top plate of a manifold block 11 for supplying two kinds of reaction gases, and the two kinds of gas discharge ports 12 and 13 formed in the bottom plate 5 allow the reaction chamber 6 to be cooled. Two kinds of reaction gases are introduced therein. That is,
A manifold block 16 having a first diffusion chamber 14 and a second diffusion chamber 15 is attached to the lower side of the bottom plate 5. The manifold block 16 has a first diffusion chamber 14 and a first diffusion chamber 14. The first reaction gas such as arsine (AsH ₃ ) introduced into the inside is diffused in the circumferential direction by the flange 19, and is supplied into the reaction chamber 6 from the gas discharge port 12 of the bottom plate 5 as indicated by a dashed arrow. It has become. Also, the second
The second reaction gas introduced into the second diffusion chamber 15 from the reaction gas supply pipe 18 is diffused in the circumferential direction by the baffle plate 20, and the gas discharge port 1 of the bottom plate 5 as shown by the solid arrow.
3 is supplied into the reaction chamber 6. The gap B formed in the upper circumferential direction of the reaction chamber 6 is:
Acts as a reaction gas outlet. Reference numeral 21 denotes a refrigerant passage for cooling the reaction chamber 6. Therefore, according to this device, the inside of the vacuum chamber 1 is brought into a high vacuum state,
Is turned on, and a gas necessary for a target semiconductor production is appropriately supplied from the first reaction gas supply pipe 17 and the second reaction gas supply pipe 18, thereby forming a uniform semiconductor thin film crystal on the surface of the substrate 9. Can be formed.

[0005]

By the way, recently,
Research and technology in the field of semiconductor manufacturing have advanced further,
Accordingly, an interface having a high-quality heterojunction and a superlattice structure as a multilayer structure thereof have been designed and manufactured, and controllability at an atomic layer level is required in a crystal growth technique. And as a form near the ultimate, 2
An atomic layer epitaxy (ALE) method of alternately supplying more than one kind of raw materials and growing semiconductor crystals one atomic layer at a time has been proposed, and there is a strong demand for the development of an apparatus capable of performing this with good reproducibility. In this regard, the apparatus shown in FIG. 5 can obtain good results in the formation of a semiconductor film using normal epitaxy growth. However, it has been found that there are some problems when the ALE method is applied.
For example, in the above-described apparatus, even if two kinds of reaction gases are alternately introduced into the reaction chamber 6 to grow crystals one atomic layer at a time, the reaction gas supplied first replaces the next reaction gas. It takes time, and the atom remaining in the reaction chamber 6 mixes with the next atom, and in some cases, the layer interface becomes rough. Further, in the above-described apparatus, the pressure in the reaction chamber 6 is adjusted by the pressure of the reaction gas introduced into the reaction chamber 6, and a pressure adjustment valve provided at the base of the reaction gas supply pipes 17 and 18 is operated. Therefore, in some cases, the response to the reaction chamber 6 is poor, and it is difficult to properly control the reaction conditions.

The present invention has been made in view of such circumstances, and has as its object to provide a semiconductor manufacturing apparatus capable of accurately growing a plurality of different types of semiconductors one atomic layer at a time.

[0007]

In order to achieve the above object, a semiconductor manufacturing apparatus according to the present invention comprises a vacuum chamber capable of achieving a high degree of vacuum, and a bottom plate, a peripheral wall, and a top plate provided in the vacuum chamber. A reaction chamber, a stepped opening formed on a top plate of the reaction chamber and capable of holding the substrate surface facing the reaction chamber, and a reaction gas supply means for supplying a reaction gas into the reaction chamber from the bottom side of the reaction chamber And a heating means for applying radiant heat from the back side to the substrate held in the opening of the reaction chamber top plate, wherein at least a part of the reaction chamber peripheral wall is freely movable with respect to the top plate. The clearance between the top plate and the peripheral wall is appropriately opened and closed by at least part of the peripheral wall moving forward and backward.

[0008]

That is, in this semiconductor manufacturing apparatus, at least a part of the peripheral wall is provided between the top plate of the reaction chamber and the peripheral wall in the circumferential direction.
The device is configured so as to be able to advance and retreat with respect to the top plate, so that the gap between the top plate and the peripheral wall can be appropriately opened and closed by the advance and retreat. Therefore, according to this apparatus, after the first reaction gas is supplied to form the first semiconductor layer, the peripheral wall is largely retracted from the top plate side and the periphery of the reaction chamber is greatly opened, so that the residual gas is instantaneously obtained. Can be removed and replaced with a second reaction gas. For this reason, the atoms of the interface between the first semiconductor layer and the next semiconductor layer do not mix with each other. Therefore, it is possible to control not the layer thickness but the film thickness at the atomic layer level, and to control how many atoms are stacked. Moreover, doping can also be controlled at the atomic layer level (doping atoms can be placed only where needed). In addition, since the gap between the reaction chambers serving as the exhaust ports can be appropriately adjusted by the retreat of the peripheral wall, the pressure in the reaction chamber during the reaction can be controlled with good responsiveness, and the film thickness can be increased. It can be controlled with precision.

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

[0010]

FIG. 1 shows an embodiment of the present invention. This semiconductor manufacturing apparatus has a vacuum chamber 1 like the apparatus shown in FIG.
The heater 2, the soaking plate 2 a, and the reaction chamber 6 are provided therein, and the step portion 8 of the central opening 7 of the top plate 3 of the reaction chamber 6
The substrate 9 is mounted downward via the holder 10.

In this apparatus, the peripheral wall 20 of the reaction chamber 6 has an upright wall 22 which rises from the outer peripheral edge of the bottom plate 21 of the reaction chamber 6, and a ring-shaped outer wall slidably fitted on an upper portion thereof. It is constituted by a sliding wall 23. The sliding wall 2
3 is supported by four support rods 26 that stand upright from a lifting base 25 that moves up and down by a cylinder 24 attached to the lower surface of the vacuum chamber 1. Therefore, the sliding wall 23 rises and falls along the outer periphery of the upright wall 22 as shown by the arrow B in accordance with the operation of the cylinder 24, and a gap between the top plate 3 and the peripheral wall 20 is generated when descending. I have. In addition, a jacket portion 23 a through which a refrigerant and a heat medium pass is formed in a lower portion of the sliding wall 23.

On the other hand, the bottom plate 21 of the reaction chamber 6 is shown in FIG.
Four gas discharge ports 27 are formed at equal intervals, and a first reaction gas communication pipe 28 with a flange is fitted in each discharge port 27, and a manifold 30 provided below the bottom plate 21 is provided.
, The first reaction gas is introduced as shown by the solid arrow. Then, each of the discharge ports 27
A second reaction gas supply pipe 29 extends from the side so as not to overlap in plan view. The distal end face of the pipe 29 is closed, and a small hole 29a is formed in the circumferential direction, so that the second reaction gas is supplied as shown by a broken arrow. A water jacket 37 is formed annularly on the lower surface of the manifold 30, and a water supply pipe 38 and a water discharge pipe 39 communicate with each other, so that the inside of the manifold 30 can be cooled immediately after the reaction is completed. It has become.

On the outer peripheral side of the bottom plate 21, 16 exhaust holes 31 are formed at regular intervals, and the same is applied to a reaction chamber holding base 32 and a low friction spacer 33 provided thereunder. A hole 31a is formed. Then, a guide ring 34 with upper and lower flanges that is fitted to the outside of the manifold 30
A hole 34a similar to the above is also formed in the upper flange 34 '. As shown in FIG. 3, the guide ring 34 has gear teeth formed on the outer peripheral portion of the lower flange 34 ″ and meshes with the gear teeth of the small-diameter gear 35.
When a rotational drive is given to the motor 5 via a motor or the like (not shown), the guide ring 34 rotates in the circumferential direction as shown in the figure. Therefore, the guide ring 34
By rotating the upper flange 3 by an appropriate angle.
The hole 34a provided in the exhaust hole 3 '
1, 31a overlaps to form a through hole in the vertical direction,
Alternatively, the amount of exhaust from the reaction chamber 6 can be adjusted by closing this to block ventilation.
The guide ring 34 is provided with a low friction spacer 33 '.
And is received from below by the manifold lower plate 36.

Further, in this semiconductor manufacturing apparatus, the upper portion of the heater 2 and the four front, rear, left and right sides are surrounded by a downward concave heat shield plate 40 formed in a U-shaped cross section. As shown in FIG. 4, the heat shield plate 40 is formed of a laminated plate having an eight-layer structure. The inner four layers 41 are formed of molybdenum, and the outer four layers 42 are formed of stainless steel. According to this structure, the heat retention is extremely high, so that the heating area of the heater 2 can be limited, and the thermal efficiency for the substrate 9 can be greatly improved.

The heat shield plate 40 (FIG. 1 returns).
Is connected at its upper surface to a piston rod of a cylinder 43 attached to the upper surface of the vacuum chamber 1, and is movable up and down as indicated by an arrow C. This is because the lower end is brought close to the vicinity of the top plate 3 of the reaction chamber 6 in order to increase the thermal efficiency by the heat shielding plate 40, so that when the substrate 9 is mounted / removed (loading / unloading), the top plate is removed. In order to avoid contact with a substrate holding jig (not shown) that advances and retreats from the side on the top of the substrate 3, the operation of the cylinder 43 causes the heat shield plate 40 to move in a dashed line when the substrate 9 is mounted and removed. The jig is raised to the position shown to prevent the jig from moving back and forth.

A heat shield cylinder 45 made of a laminated plate of the same material as the heat shield plate 40 is provided inside the peripheral wall of the vacuum chamber 1, and the heat of the heater 2 is transmitted to the peripheral wall of the vacuum chamber 1. It is devised not to. Further, the heat shielding cylinder 45
A ring-shaped jacket 46 into which liquid nitrogen flows is provided. The stainless steel plate 46a which stands upright while being in contact with the outer periphery of the jacket 46 is cooled to transfer heat to the peripheral wall of the vacuum chamber 1. It is completely shut off. The jacket 46 and the cooled inner peripheral surface of the stainless steel plate 46a can capture the impurity gas remaining in the vacuum chamber 1 after the gas exchange.

As described above, in this device, the periphery of the heater 2 is covered with the heat shield plate 40, and the amount of gas discharged from the reaction chamber 6 is adjusted by the height of the sliding wall 23 and the opening of the exhaust hole 31. Since the heat medium is introduced into the jacket 23a in the sliding wall 23 which forms a part of the peripheral wall of the reaction chamber 6, the inside of the reaction chamber 6 is set to an appropriate temperature and pressure. be able to. Therefore, after supplying the first reaction gas, the desired reaction conditions can be realized in the reaction chamber 6 with good responsiveness, and the one atomic layer of the semiconductor layer derived from the first reaction gas can be precisely formed. Can be manufactured. After completion of the reaction, a coolant (water) is introduced into the jacket portion 23a and the water jacket 37 below the manifold 30, so that the reaction chamber 6 and the manifold 30
Can be instantaneously cooled, and the sliding wall 23 around the reaction chamber 6 can be lowered to make a large gap with the top plate 3 so that exhaust can be performed instantaneously. Therefore, when the second reaction gas is supplied next, the inside of the reaction chamber 6 is immediately replaced with the second reaction gas, and the first reaction gas does not remain. Then, the sliding wall 23 is raised again to narrow the gap between the reaction chamber 6 and the top plate 3 to an appropriate distance, and the exhaust holes 31
By adjusting the opening degree of the substrate and heating the reaction chamber 6, a one-atom semiconductor layer derived from the second reaction gas can be manufactured with high accuracy. By repeating this alternately, a semiconductor having a superlattice structure having a very clean layer interface can be obtained. More specifically, in the apparatus shown in FIG. 5, the pressure in the reaction chamber is determined by the flow rate of the source gas to be introduced and the conductance of the outlet, and the conductance of the outlet of the reaction chamber itself cannot be changed during the process. Therefore, when trying to change the pressure of the reaction chamber, it is necessary to change the flow rate of the introduced gas or the conductance of the evacuation system for evacuating the vacuum chamber to change the pressure of the reaction chamber and the entire vacuum chamber. In such a case, in the former, it is difficult to change the reaction pressure by more than two orders of magnitude, and in the case of switching the gas after introducing one source gas at a high pressure, it takes time to exhaust the residual gas in the reaction chamber. There was a problem that it took. According to the embodiment of the present invention, these can be solved. In the latter case, not only the pressure in the reaction chamber but also the entire vacuum chamber is changed, so that the pressure cannot be largely changed in a short time, and the reaction chamber is set to a high pressure such as a viscous flow region. In such a case, problems such as heat and an increase in impurity concentration in the atmosphere occur. According to the embodiment of the present invention, these can be solved.

In the above embodiment, the peripheral wall 20 is constituted by combining the upright wall 22 and the sliding wall 23, and the sliding wall 23 is configured to be able to advance and retreat with respect to the top plate 3. Alternatively, it may be configured to be able to advance and retreat with respect to the top plate 3.
However, in this case, the reaction gas supplied into the reaction chamber 6 leaks from the joint between the bottom plate 21 and the peripheral wall 20 and the flow of the reaction gas to the substrate 9 is easily hindered. Is an important issue.

Further, in the above embodiment, the heat shield plate 40 for covering the heater 2 from the upper surface side is provided. However, when a semiconductor having a relatively low reaction temperature is manufactured, it is not particularly necessary to provide the heat shield plate.

Further, the shape of the manifold 30 and the first reaction gas supply method and the second reaction gas supply method are not limited to those in the above embodiment, but can be set as appropriate.

In the above embodiment, the jacket 23a for passing the refrigerant / heat medium is formed inside the sliding wall 23, but this is not always necessary. However, it is preferable to heat the vicinity of the reaction chamber 6 to increase the heating efficiency. As such a heating method, besides passing a heat medium through the jacket portion 23a, a method of winding a heating heat coil or the like around the sliding wall 23 may be mentioned.

Further, in the above embodiment, the manifold 3
By rotating the guide ring 34 externally fitted to the outer periphery 0 in the circumferential direction, the exhaust holes 3 provided in the bottom plate 21 of the reaction chamber 6 are formed.
Although the exhaust amount is adjusted by adjusting the opening degree of 1, the exhaust amount at the time of reaction is adjusted only by adjusting the gap between the sliding wall 23 and the top plate 3 without providing this mechanism. There is no harm in doing so.

In the above embodiment, the substrate 9 is mounted horizontally. However, the present invention may be applied to an apparatus of a type in which the substrate 9 is mounted vertically and gas is supplied from a horizontal direction. Good.

In the semiconductor manufacturing apparatus according to the present invention, the bottom surface 21 of the reaction chamber 6 is formed of molybdenum,
Is preferably formed of any of tantalum, tungsten and surface-nitrided stainless steel. Alternatively, bottom surface 21 may be formed of metal, and sliding wall 23 may be formed of graphite coated with silicon carbide. When these combinations are used, molybdenum is a high melting point metal material, so the raw material hardly evaporates from the molybdenum material during growth, and radiant heat from the heater is efficiently received, and the wall of the reaction chamber is appropriately heated. Group III metalorganic molecules, group V As
Since atoms are efficiently used for the growth reaction without being adsorbed, a semiconductor of excellent quality can be obtained.

[0025]

As described above, in the semiconductor manufacturing apparatus according to the present invention, at least a part of the peripheral wall of the reaction chamber is configured to be able to advance and retreat with respect to the top plate, and the gap between the top plate and the peripheral wall is appropriately adjusted by the advance and retreat. It can be opened and closed. Therefore, according to this apparatus, the first reactant gas is supplied and the first reactant gas is supplied.
After the semiconductor layer is formed, the peripheral wall is largely retracted from the top plate side and the periphery of the reaction chamber is greatly opened, whereby the residual gas can be instantaneously removed and replaced with the second reaction gas. Therefore, atoms do not mix with each other at the boundary surface between the first semiconductor layer and the next semiconductor layer, and controllability of the film thickness and doping at the atomic layer level can be obtained. In addition, since the gap between the reaction chambers serving as the exhaust ports can be appropriately adjusted by the retreat of the peripheral wall, the pressure in the reaction chamber during the reaction can be controlled with good responsiveness, which is optimal for a growing semiconductor. A simple reaction space can be easily formed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a view of the bottom plate of the reaction chamber of the above embodiment as viewed from above.

FIG. 3 is an explanatory diagram of a displacement adjusting mechanism of the embodiment.

FIG. 4 is an explanatory diagram of a configuration of a heat shield plate of the above embodiment.

FIG. 5 is a longitudinal sectional view showing a conventional semiconductor manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Heater 3 Top plate 6 Reaction chamber 7 Opening 8 Step 20 Peripheral wall 21 Bottom plate 22 Standing wall 23 Sliding wall 24 Cylinder 27 Gas discharge port 28 First reaction gas communication pipe 29 Second reaction gas supply pipe 30 Manifold

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshihisa Fujisaki 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Central Research Laboratory (72) Inventor Toshimitsu Miyata 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (56) References JP-A-3-183128 (JP, A) JP-A-4-349929 (JP) , A) JP-A-1-257323 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/205

Claims (5)

(57) [Claims] 1. A vacuum chamber capable of achieving a high degree of vacuum, a reaction chamber provided in the vacuum chamber, comprising a bottom plate, a peripheral wall, and a top plate, and a substrate surface formed on the top plate of the reaction chamber with the substrate surface facing the reaction chamber. A stepped opening that can be held in a state where it is held, a reaction gas supply means for supplying a reaction gas into the reaction chamber from the bottom side of the reaction chamber, and radiant heat from the back side to the substrate held in the opening of the reaction chamber top plate. And a heating means for applying the heat, wherein at least a part of the peripheral wall of the reaction chamber is configured to be able to advance and retreat with respect to the top plate, and a gap between the top plate and the peripheral wall is formed by at least a part of the peripheral wall. A semiconductor manufacturing apparatus characterized in that it is opened and closed appropriately. 2. The reaction chamber according to claim 1, wherein a bottom plate of the reaction chamber is formed of molybdenum, and a peripheral wall portion capable of moving back and forth with respect to the top plate is formed of any of tantalum, tungsten, and stainless steel subjected to surface nitriding. Semiconductor manufacturing equipment. 3. The semiconductor manufacturing apparatus according to claim 1, wherein a bottom plate of the reaction chamber is formed of metal, and a peripheral wall portion capable of moving forward and backward with respect to the top plate is formed of graphite coated with silicon carbide. 4. The apparatus according to claim 1, wherein a second substrate heating means is provided at or near the peripheral wall of the reaction chamber.
The semiconductor manufacturing apparatus according to any one of the above. 5. The semiconductor manufacturing apparatus according to claim 1, wherein a substrate cooling means is provided at or near the peripheral wall of the reaction chamber.