JP5196474B2 - Thin film manufacturing equipment - Google Patents

Description

  The present invention relates to a thin film manufacturing apparatus for forming a thin film on a substrate held in a reaction vessel.

One method for forming a thin film on a substrate is MOCVD (Metal Organic Chemical Vapor Deposition). MOCVD is a type of CVD (Chemical Vapor Deposition), which introduces a gas containing a source gas near the substrate surface and uses a chemical reaction to form a compound such as GaAs or GaN on the substrate. It is known as a method for crystal growth of a semiconductor (see Patent Document 1).
JP 2004-200225 A

  In an MOCVD apparatus for performing the MOCVD method, a process for depositing a compound semiconductor on the substrate is performed after the upper surface of the reaction vessel holding the substrate is closed with a lid and the reaction vessel is sealed. When the film forming process is performed, particles are formed inside the reaction vessel or the lower surface of the lid, and if the particles generated on the lower surface of the lid fall on the substrate, the reliability of the product may be lowered. In particular, in the case where the gas is introduced into the reaction vessel by the shower-like introduction means provided on the lower surface of the lid, the film is excellent in uniformity of the film formation. There was a tendency that particles generated on the lower surface of the product easily fall and contaminate the product. For this reason, in the conventional MOCVD apparatus, the deposition gas is supplied from the side to the substrate, and then the adhesion prevention plate is attached to the lower surface of the lid with screws, etc., and the dirty adhesion prevention plate is cleaned. I am trying to replace it regularly.

  The problem to be solved by the present invention is to provide a thin film manufacturing apparatus capable of easily performing the replacement work of the deposition preventing plate.

The thin film manufacturing apparatus according to the present invention made to solve the above problems is for forming a thin film on the surface of a substrate held horizontally in a reaction vessel,
a gas supply means for supplying a film forming gas to the substrate of a) the reaction vessel,
b) an openable / closable lid for closing the reaction vessel;
c) an adhesion preventing plate detachably provided on the surface of the lid on the reaction container side;
d) opening and closing means for opening and closing the lid;
e) an adjusting means for adjusting an angle of the lid with respect to the substrate so as to maintain a state where the lid is raised in a vertical state with respect to the substrate in a state where the lid is opened by the opening / closing means ;
It is characterized by providing.

  In the thin film manufacturing apparatus according to the present invention, when the deposition plate is soiled, the lid is opened using the opening / closing means, and the angle of the lid is adjusted using the adjustment unit so as not to obstruct the attachment / detachment work of the deposition plate. To do. If it does so, an operator can perform the attachment or detachment operation | work of a protection board easily. Also, when cleaning the inside of the container, the angle of the lid can be appropriately adjusted so as not to obstruct the cleaning.

Hereinafter, an embodiment in which the present invention is applied to a MOCVD apparatus will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a thin film manufacturing apparatus according to the present embodiment. The thin film manufacturing apparatus 10 of this embodiment includes a glove box 12 having a door 12a and an operation unit 12b on the front surface, a reaction vessel 14 disposed in the glove box 12, and the like. The reaction vessel 14 includes an upper opening 14a and an upper lid 14b that closes the upper opening 14a. A substrate table 16 is provided in the reaction vessel 14, and a plurality of substrates 18 are placed on the substrate table 16 on the susceptor 2 made of silicon carbide or the like.

  FIG. 2 is a schematic view of the reaction vessel 14 shown with the upper lid 14b open. As shown in FIGS. 1 and 2, a quartz plate 24 as an adhesion preventing plate having excellent heat resistance is detachably attached to a lower surface (surface on the reaction vessel 14 side) of the upper lid 14 b through a plurality of bolts 26. ing. Between the quartz plate 24 and the upper lid 14b, a carbon sheet 28 for increasing the cooling efficiency of the quartz plate 24 is provided.

  The glove box 12 is for maintaining the periphery of the reaction vessel 14 at a pressure higher than atmospheric pressure. Thus, by setting the periphery of the reaction vessel 14 to a pressure higher than the atmospheric pressure, when the upper cover 14b of the reaction vessel 14 is opened and the quartz plate 24 is replaced or the substrate 18 is transported, Oxygen and moisture can be prevented from entering the reaction vessel 14. When oxygen and moisture in the atmosphere enter the reaction vessel 14, the crystallinity tends to deteriorate particularly during the formation of a nitride semiconductor or the like. The inside of the glove box 12 is filled with nitrogen gas or the like, and the nitrogen gas circulates through an oxygen removal filter and a moisture removal filter (not shown) to always remove trace amounts of oxygen and moisture. Further, nitrogen gas corresponding to the removed oxygen and moisture is always replenished inside the glove box 12. The exchanged quartz plate 24 and the substrate 18 placed on the susceptor 2 can be taken out of the glove box 12 through a load lock chamber (not shown) provided adjacent to the glove box 12.

  A gas inlet 20 for introducing a film forming gas into the reaction container 14 and a gas outlet 22 for discharging the film forming gas that has passed through the surface of the substrate 18 are formed on the inner surface of the reaction container 14. The film forming gas introduced from the gas inlet 20 is supplied to the substrate 18 from the side.

The upper lid 14 b is provided so as to close the upper opening of the reaction vessel 14, and is configured to be able to contact and separate from the reaction vessel 14 by the elevating and rotating device 30.
The lifting / lowering rotating device 30 includes a lifting / lowering mechanism 32, a rotating mechanism 34, a lid support portion 36, and the like. The lid support portion 36 includes a pair of support shafts 37 fixed to the upper lid 14 b and a pair of support plates 38 that rotatably support the support shafts 37, and is lifted and lowered by the lifting mechanism 32.

As shown in FIG. 3, the rotating mechanism 34 includes a pair of bearings 39 disposed on one of a pair of support plates 38, a single round rack 40 supported by the bearing 39, and the round rack 40 in the direction of arrow A. The air cylinder 41 and the gear 42 meshing with the teeth of the round rack 40 are configured. The gear 42 is fixed to the support shaft 37, and rotates in the arrow B direction together with the support shaft 37 as the round rack 40 is driven in the arrow A direction.
The elevating mechanism 32 includes, for example, a conveyor chain (not shown), a drive motor 32a, and the like.

  Next, the internal structure of the reaction vessel 14 of the thin film manufacturing apparatus 10 according to the present invention will be described in detail. FIG. 4 is a plan view of the main part in the reaction vessel 14. A rotatable susceptor 2 is provided in the reaction vessel 14, and a plurality of substrates 18 are placed on the susceptor 2. The gas introduction unit 4 is integrally connected to the reaction vessel 14. An upper lid 14 b that closes the upper opening 14 a of the reaction vessel 14 is provided immediately above the susceptor 2.

  The gas introduction unit 4 includes a gas opening 5 and a gas input unit 6. The opening 5 is a space for discharging gas to the susceptor 2 in the reaction vessel 14, that is, to the substrate 18. The gas input unit 6 is integrally connected to the gas opening 5, and gas is supplied from a gas input port 7 provided at one end of the gas input unit 6 in parallel with the surface of the substrate 18, that is, the susceptor 2. The gas is introduced perpendicularly to the direction of gas discharge from the opening 5 (rightward in FIG. 4) (may be slightly inclined). In the present specification, the “gas discharge direction from the gas opening 5” refers to a direction from the gas opening 5 toward the susceptor 2.

FIG. 5 is a cross-sectional view of the reaction vessel 14 of the thin film manufacturing apparatus. There may be only one gas input port 7 as shown in FIG. 5 (A), or as shown in FIG. 5 (B), the gas input port 7 is a first gas in the thickness direction of the substrate. An input port 7a and a second gas input port 7b can also be provided. As shown in FIG. 5C, three gas input ports (first to third gas input ports 7a to 7c) or more gas input ports can be provided.
The gas supply means of the present invention introduces a gas that is connected to the gas introduction port 20 and the gas introduction port 20, parallel to the substrate surface and perpendicular to the gas discharge direction from the gas introduction port 20. It consists of a gas input port 7.

As shown in FIGS. 4 and 5, a plurality of (9 in FIG. 4) rectifying plates 8 are installed in the gas opening 5 in a direction perpendicular to the flow of gas introduced from the gas input unit 6. Has been. By providing the rectifying plate 8, the nonuniformity of the gas discharged from the gas opening 5 to the substrate 18 can be controlled.
That is, by providing the rectifying plate 8, the amount (flow velocity) of gas discharged from the gas opening 5 side close to the gas input port 7 and the gas discharged from the gas opening 5 side far from the gas input port 7 are provided. There is a difference between the quantity (flow rate). In general, the flow rate of the gas discharged from the gas openings 5 to the substrate 18 is made uniform as the number of rectifying plates 8 increases, and the non-uniformity in the gas flow rate as the number of rectifying plates 8 decreases. Increase. Therefore, by adjusting the number of the rectifying plates 8 and causing the concentration and speed of the gas discharged from the gas opening 5 to be inclined in the plane of the gas opening 5, as a result, the substrate 18 has high uniformity. A film can be formed. The rectifying plate 8 does not have to be completely perpendicular to the flow of gas introduced from the gas input unit 6 and may be slightly inclined.
In addition, the non-uniformity of the gas discharged from the gas opening 5 to the substrate 18 can be adjusted by the speed of the gas input from the gas input port 7.

In the thin film manufacturing apparatus according to the present invention, the gas that has passed through the surface of the substrate 18 is exhausted to the outside of the reaction vessel 14 through an exhaust port (not shown in FIGS. 4 and 5). The exhaust port may take any form, but the way of gas flow on the susceptor 2 may change depending on the location of the exhaust port and the exhaust strength.
In the example shown in FIG. 4, the susceptor 2 rotates counterclockwise, but the susceptor 2 may rotate clockwise.

The present inventors confirmed by simulation calculation how the gas flows in the reaction vessel 14 by the configuration of the reaction vessel 14 of the thin film manufacturing apparatus. Here, simulation calculation was performed for a reaction vessel having a gas input port and an exhaust port on the same side as shown in FIG. FIG. 6 shows the simulation result. FIG. 7 is a graph showing the flow velocity in the X direction (left and right direction in FIG. 6) in the AA ′ section (cross section passing through the center of the susceptor) in FIG.
From the simulation results of FIGS. 6 and 7, the flow rate of the gas discharged from the gas opening 5 toward the susceptor 2 is higher as it is closer to the gas input port 7, and is lower as it is farther from the gas input port 7. It was confirmed that gas was discharged non-uniformly (with a monotonously increasing / decreasing slope) from the gas opening 5. Since the gas flow velocity has a monotonous gradient over the entire region of the susceptor 2, it is possible to form a uniform film on the surface of the substrate 18 only by revolving the susceptor 2 without rotating the substrate 18.

  As will be described later, at the time of film formation, the tray on which the substrate 18 is placed is about 10 times per minute so that the film-forming gas supplied from the side to the substrate 18 is uniformly epitaxially grown on the substrate 18. Rotate with For example, when epitaxially growing gallium nitride, a heater (not shown) provided inside the substrate table 16 is heated to heat the surface temperature of the substrate 18 to about 1000 ° C. Thus, in order to heat the surface of the substrate 18 to a high temperature, the film forming gas introduced from the gas inlet 20 tends to rise in the direction of the upper lid 14b, and the epitaxial growth may not be performed efficiently. Therefore, the quartz plate 24 is preferably provided with an inclination that directs the flow of the deposition gas toward the substrate 18. Thereby, since the deposition gas flows toward the substrate 18, the epitaxial growth can be performed more uniformly and efficiently. Further, since the surface temperature of the substrate 18 is heated to about 1000 ° C. as described above, the surface temperature of the quartz plate 24 provided above the substrate 18 (about 10 mm) is also heated to about 1000 ° C. Therefore, it is preferable that cooling water is circulated inside the upper lid 14 b to cool the quartz plate 24 through the carbon sheet 28 so that the surface temperature of the quartz plate 24 is about 200 to 400 ° C.

  Next, in order to confirm the effect of the thin film manufacturing apparatus according to the present invention, an experiment conducted by the inventors will be described. In the experiment described below, an apparatus having the configuration shown in FIG. 8 was used. In this apparatus, the exhaust port is provided on the same side as the gas input port 7. Further, the same number of rectifying plates as the rectifying plates 8 provided in the gas openings 5 are arranged also on the exhaust side of the reaction vessel 14 for the purpose of rectifying the exhausted gas. The height of the reaction vessel 14 and the gas introduction part 4 was 10 mm. As shown in FIG. 5C, the gas is input to the substrate 18 through the three gas input ports 7 including the first gas input port 7a, the second gas input port 7b, and the third gas input port 7c. It was performed by providing in the vertical direction.

[Experimental Example 1]
GaN was grown on the C surface of the sapphire substrate in the following steps. Trimethylgallium (TMG) was used as the Group 3 material, and ammonia (NH3) was used as the Group 5 material.
First, the inside of the glove box 12 was filled with nitrogen at a pressure slightly higher than atmospheric pressure. The upper lid 14b provided so as to close the upper opening 14a of the reaction vessel 14 was raised directly above by the elevating mechanism 32, and then rotated by the rotating mechanism 34 to erect the upper lid 14b in a substantially vertical state. In this state, the bolt 26 at the center of the lower surface of the upper lid 14b was removed through the glove of the operation portion 12b provided on the front surface of the glove box 12, and a fixing jig was inserted into the bolt hole. Then, while preventing the quartz plate 24 from falling, the remaining bolts 26 were sequentially removed, and finally the fixing jig was removed from the bolt hole, and the quartz plate 24 was removed from the upper lid 14b. Next, the quartz plate 24 was taken out from the glove box 12 via a load lock chamber provided adjacent to the glove box 12. Thereafter, a new quartz plate 24 was attached to the lower surface of the upper lid 14b in the reverse procedure of removing the quartz plate 24.

(1) A 2 inch φ sapphire substrate after washing was placed on the susceptor 2. Next, the rotating mechanism 34 was used to rotate the upper lid 14b from the standing vertical state to the horizontal state, and the upper / lower rotating device 30 returned the upper lid 14b to the original position, thereby sealing the reaction vessel 14.
(2) The air in the stainless steel reaction vessel 14 was evacuated with a vacuum pump, and H 2 gas was introduced into the reaction vessel 14 until the pressure reached 300 Torr. At the same time, the susceptor 2 started to rotate at a rotation speed of 10 rpm.
(3) Next, H2 gas was supplied at 2 L / min from the third gas input port 7c. While maintaining the pressure in the reaction vessel 14, the susceptor 2 was heated to 1100 ° C.

(4) Hold this state for 10 minutes to clean the surface of the sapphire substrate, and then lower the temperature of the substrate to 500 ° C. to stabilize it.
(5) Subsequently, H2 gas as a carrier gas was supplied to the reaction vessel at a flow rate of 5 L / min, N2 gas at 5 L / min, and ammonia gas at 5 L / min from the third gas input port 7c. Further, from the first gas input port 7a, H2 as a top gas is supplied to the reaction vessel at a flow rate of 5 L / min and top gas N2 is supplied to the reaction vessel at a flow rate of 5 L / min. In this state, the temperature, pressure and gas flow are changed. Stabilized.
(6) After stabilization of the temperature, etc., TMG gas began to be supplied from the third gas input port 7c. The supply amount of TMG gas was 149 μmol / min (bubbling gas H2 30 sccm). This state was continued for 2 minutes, and an amorphous GaN buffer layer that relaxed the lattice mismatch was grown on the surface of the sapphire substrate by ˜20 nm.

(7) Next, the supply of TMG gas was stopped, and the temperature of the substrate 18 was raised to 1050 ° C. while supplying other gases. After the substrate was heated to 1000 ° C., the ammonia supply amount from the third gas input port 7c was changed to 20 L / min, and the N2 supply amount from the third gas input port 7c was changed to 15 L / min. Furthermore, the top gases N2 and H2 from the first gas input port 7a were each changed to 15 L / min. In this state, it waited until the substrate temperature was stabilized at 1050 degreeC.
(8) After the substrate temperature was stabilized, TMG gas was supplied at a flow rate of 456 μmol / min (bubble gas H2 120 sccm) at the third gas input port 7c, and GaN was grown for 60 minutes.
(9) The atmosphere was returned to normal temperature and normal pressure, the upper lid was raised directly above by the lifting mechanism, the substrate 18 was taken out from the reaction vessel 14, and the film thickness distribution was measured with a film thickness meter.

  As a result, the semiconductor crystal film obtained in Experimental Example 1 was grown on the entire surface of the 2-inch sapphire substrate, the surface was a mirror surface, and the film thickness was 1.8 μm ± 1% over the entire surface of the 2-inch substrate. . Moreover, the result of having performed CL (cathode luminescence) measurement is shown in FIG. As shown in FIG. 9, sharp GaN band edge emission was observed at 363.2 nm. Further, when the surface of the semiconductor crystal film was visually observed, no particles dropped from the upper lid 14b.

[Experiment 2]
An InGaN / GaN multilayer film was grown on the C surface of the sapphire substrate in the following steps. Since the steps (1) to (8) are the same as those in Experimental Example 1, they are omitted.
(9) The temperature of the substrate 18 was slowly lowered to 800 ° C., and the carrier gas H2 introduced from the third gas input port 7c was changed to N2 (5 L / min). Further, the top gas H2 supplied from the first gas input port 7a was stopped, and N2 (15 L / min) was used instead. In this state, the substrate temperature, pressure, and gas flow were stabilized.
(10) After the temperature was stabilized, the supply of TMG gas was started from the third gas input port 7c. The flow rate of TMG gas was 39.6 μmol / min (bubbling gas N2 5 sccm). The GaN layer was grown by continuing this state for 3 minutes.

  (11) The supply of TMI (trimethylindium) gas was started from the third gas input port 7c while the supply of TMG was continued. The flow rate of TMI gas was 30.8 μmol / min (bubbling gas N2 20 sccm). This was continued for 90 seconds to grow an InGaN layer.

(12) Further, (10) to (11) were repeated 5 times to produce GaN and InGaN quantum wells.
(13) Finally, step (10) was performed again to grow GaN for 20 minutes.

  The CL measurement results of the thin film obtained as described above are shown in FIG. From this result, the emission of the main peak emission wavelength (λ = 413 nm) of InGaN was obtained and the standard deviation σ was obtained. As a result, σ = 1.88 nm, and a film with a very good in-plane distribution of the emission wavelength was produced. It was confirmed that Further, when the surface of the semiconductor crystal film was visually observed, no particles dropped from the upper lid 14b.

In the thin film manufacturing apparatus according to the present invention, the quartz plate 24 that has become dirty due to particles adhering to it can be removed from the upper lid 14b and replaced with a new quartz plate 24. The work for exchanging the quartz plate 24 is as follows.
First, it is confirmed that the inside of the glove box 12 is filled with nitrogen gas at a pressure higher than atmospheric pressure. Subsequently, the upper lid 14b is raised directly above by the lifting mechanism 32 of the lifting / lowering rotating device 30, and then rotated by the rotating mechanism 34 to erect the upper lid 14b in a substantially vertical state. In this state, the bolt 26 at the center of the lower surface of the upper lid 14b is removed through the glove of the operation unit 12b provided on the front surface of the glove box 12, and a fixing jig (none of which is shown) is inserted into the bolt hole. This prevents the quartz plate 24 from falling. Subsequently, the remaining bolts 26 are sequentially removed, and finally the fixing jig is removed from the bolt holes, and the quartz plate 24 is removed from the upper lid 14b. Then, the quartz plate 24 is taken out from the glove box 12 via a load lock chamber provided adjacent to the glove box 12. Next, a new quartz plate 24 is attached to the lower surface of the upper lid 14b in the reverse procedure to the removal of the quartz plate 24, and the upper lid 14b is returned to its original position by the elevating and rotating device 30, and the reaction vessel 14 is sealed.

  As described above, the thin film manufacturing apparatus 10 of the present embodiment can stand the upper lid 14b lifted from the reaction vessel 14 in a vertical state, and thus can work while visually confirming the attachment / detachment of the bolt 26. For this reason, it is possible to prevent the bolt 26 from being accidentally dropped into the reaction vessel 14 as much as possible, and the quartz plate 24 can be easily replaced. Further, since the upper lid 14b can be erected in a vertical state, it becomes easy to check the degree of contamination of the quartz plate 24. Since the quartz plate 24 itself is less likely to drop from the upper lid 14b, the quartz plate 24 can be easily replaced.

  Furthermore, the cleaning operation in the reaction vessel 14 can be easily performed by appropriately adjusting the angle of the upper lid 14 b by the lifting and rotating device 30. Furthermore, when the substrate 18 is taken out from the reaction vessel 14 or the substrate 18 is put into the reaction vessel 14, if the upper lid 14 b is tilted even a little, there is an effect that the operation is easy.

  In addition, although the example which rotates the upper cover 14b in the perpendicular state, ie, 90 degree | times was demonstrated, the rotation angle of the upper cover 14b is not limited to 90 degree | times. For example, by rotating the upper lid 14b more than 90 degrees, it is possible to further prevent particles adhering to the quartz plate 24 from falling into the reaction vessel 14 when the quartz plate 24 is removed from the upper lid 14b.

  In the thin film manufacturing apparatus according to the present invention, the gas is introduced in the gas input unit 6 connected to the gas opening 5 in parallel to the surface of the substrate 18 and perpendicular to the gas discharge direction from the gas opening 5. Is done. As a result, the concentration and speed of the gas discharged from the gas opening 5 are inclined in the plane of the gas opening 5, and as a result, a highly uniform film is formed on the substrate 18 placed on the susceptor 2. Is done.

  Furthermore, in the thin film manufacturing apparatus according to the present invention, the flow of the gas introduced onto the substrate 18 is naturally inclined only by structural contrivance in the gas opening 5 and the gas input unit 6. Therefore, it is not necessary to prepare a special mechanism for controlling the gas flow, which is very advantageous in terms of cost. Further, since it is not necessary to rotate the substrate 18 on the susceptor 2, it is possible to avoid the problem that particles are mixed in the reaction container 14.

  Further, by appropriately providing the rectifying plate 8 in the gas opening 5, the non-uniformity control of the flow of the gas discharged to the susceptor 2 (that is, the substrate 18) can be performed by a simple method.

  Although the thin film manufacturing apparatus according to the present invention has been described above, the above is only an example, and modifications and changes can be appropriately made within the spirit of the present invention.

The schematic block diagram of the thin film manufacturing apparatus which concerns on one Example of this invention. The schematic of the reaction container shown in the state which open | released the upper cover. The figure which expands and shows a rotation mechanism. The top view of the principal part of one Example of the thin film manufacturing apparatus which concerns on this invention. Sectional drawing of the principal part of one Example of the thin film manufacturing apparatus which concerns on this invention. The figure which shows the flow-velocity simulation result in the thin film manufacturing apparatus which concerns on this invention. The graph which shows the flow velocity in the AA 'cross section of FIG. The top view of the thin film manufacturing apparatus which inventors conducted experiment. The graph which shows the CL measurement result of the substrate surface which formed GaN into a film using the thin film manufacturing apparatus which concerns on this invention. The graph which shows the CL measurement result of the substrate surface which formed InGaN into a film using the thin film manufacturing apparatus which concerns on this invention.

Explanation of symbols

2... Susceptor 4... Gas introduction part 5... Gas opening part 6... Gas input part 7. Manufacturing apparatus 12 ... Glove box 14 ... Reaction vessel 14b ... Upper lid 16 ... Substrate base 18 ... Substrate 20 ... Gas inlet (gas supply means)
22 ... Gas outlet 24 ... Quartz plate (protection plate)
26 ... Bolt 30 ... Elevating and rotating device 32 ... Elevating mechanism 34 ... Rotating mechanism 36 ... Lid support part

Claims (2)

In a thin film manufacturing apparatus for forming a thin film on the surface of a substrate held horizontally in a reaction vessel,
a) a gas supply means for supplying a film forming gas to the substrate in the reaction vessel;
b) an openable / closable lid for closing the reaction vessel;
c) an adhesion preventing plate detachably provided on the surface of the lid on the reaction container side;
d) opening and closing means for opening and closing the lid;
e) an adjusting means for adjusting an angle of the lid with respect to the substrate so as to maintain a state where the lid is raised in a vertical state with respect to the substrate in a state where the lid is opened by the opening / closing means ;
A thin film manufacturing apparatus comprising:   2. The thin film manufacturing apparatus according to claim 1, wherein the thin film manufacturing apparatus is a CVD apparatus for forming a film by a chemical reaction.

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