JPH06112132A - Organometal vapor growth device - Google Patents

Abstract

PURPOSE:To provide a device capable of preventing the generation of a film defect due to the dust of a reaction product and a device capable of excellently forming a film, to which a doping element is doped uniformly and sufficiently. CONSTITUTION:In a device, an angle alpha1 formed by the axis of an organometallic gas supply nozzle 2 and a substrate 1 carried in the horizontal direction to the underside (a film forming surface) of the substrate 1 satisfies 0 deg.<alpha1<90 deg., and an edge section not faced oppositely to the substrate l of the opening section 21 of the nozzle is arranged so as to be recessed from a surface vertical to the substrate 1 passing through an edge section oppositely faced to the substrate 1. It is more preferable that a dust reservoir section 22 is mounted to the nozzle. A uniformly doped film can be obtained in a device, in which a plurality of the nozzles having separately different angles formed by the nozzle axis and the substrate are installed and the same position of the substrate 1 can be supplied simultaneously with a plurality of kinds of gases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metalorganic vapor phase epitaxy apparatus.

[0002]

2. Description of the Related Art In the metal organic chemical vapor deposition method (MOCVD method), as a method of supplying a gas onto a substrate on which a film is to be formed, a substrate holder in a reaction chamber 5 has conventionally been used as shown in FIG. 4, a vertical type in which a gas is vertically blown to the film-forming surface of the substrate 1 mounted horizontally on the substrate 1 and flowed as indicated by a dotted arrow, and a substrate holder in the reaction chamber 5 as shown in an explanatory view of main parts of FIG. A barrel type in which gas is caused to flow along the film forming surface of the substrate 1 mounted vertically on the substrate 4 as shown by a dotted arrow has been widely used. However, it is difficult to form a film with a uniform film thickness by these methods, and film defects occur due to the adhesion of dust on the substrate, the adhesion of dust of the reaction product of the organometallic gas, and the like. However, there is a problem that it is difficult to increase the area of the film. As a remedy for such a problem, FIG.
As shown in the explanatory view of the main part of FIG. 1, while transporting the substrate 1 in the reaction chamber 5 filled with the reactive gas in the horizontal direction as shown by the arrow A, the organometallic gas is supplied from the gas supply nozzle 2 to the lower surface of the substrate 1. A method is known in which a film is sprayed vertically as indicated by a dotted arrow.

[0003]

However, while the substrate is transported horizontally in the above-mentioned reactive gas atmosphere,
Even in the method of vertically spraying the organometallic gas onto the lower surface of the substrate, the problem of film defects due to dust of the organometallic gas reaction product has not been sufficiently solved. This is because the reaction product accumulated on the side wall of the reaction chamber, the upper wall, and the substrate holder is peeled off, and the dust generated falls into the gas supply nozzle.
This is because the gas blows up from the nozzle and adheres to the lower surface of the substrate (film forming surface).

Further, as described above, in the case of the method of vertically spraying the organic metal gas onto the lower surface of the substrate, the gas blown out from the gas supply nozzle 2 is shown by a dotted arrow as shown in the explanatory view of the main part of FIG. Moreover, since the light is reflected on the lower surface of the substrate 1, it is difficult to improve the use efficiency of the gas used for film formation. That is,
In the stage where the reaction depends on the gas supply amount, the film formation rate can be increased by increasing the gas flow rate (flow rate). However, increasing the flow rate increases the amount of gas reflected by the substrate, The above reaction does not react and the amount of gas exhausted increases, resulting in less efficient use than expected.

In order to solve the problems of dust adhesion of the reaction product and gas use efficiency as described above, it is sufficient to make the gas flow horizontal with respect to the substrate as seen in the barrel type.
As shown in the principal part explanatory view of FIG. 7, when the substrate 1 is fixed by the substrate holder 4 and the mask 6, a delicate space is generated between the gas flow and the substrate surface, and the film formation efficiency is reduced. It will be.

Further, the MOC is obtained by using the first organometallic gas.
In the VD method, another metal-organic gas is caused to flow during film formation to dope the other metal into the film to form a desired functional film. In this case, the above-mentioned substrate is used. In the method of vertically spraying the organometallic gas onto the lower surface of the substrate while transporting the gas in the horizontal direction, the first organometallic gas is blown out by the gas supply nozzle 2 as shown in the explanatory view of the main part of FIG. After the reactive gas reacts on the substrate 1 (after the base film 7 is formed to some extent), another organometallic gas is sequentially supplied by the gas supply nozzle 2a, the nozzle 2b, .... There is a problem that the doping element is not uniformly and sufficiently diffused in the film, because the organic metal is doped by being blown out to cause a reaction. This problem becomes more serious as the number of elements to be doped increases and the positions of the second and subsequent gas supply nozzles move away from the first organometallic gas nozzle. As a method of solving this, it is most effective to mix the first organic metal gas and the organic metal gas used for doping and blow it out from one nozzle. If a reaction occurs, this measure cannot be taken.

The present invention has been made in view of the above points, and the dust of the reaction product falls into the gas supply nozzle, and the dust is blown out together with the gas and adheres to the substrate surface during film formation. A first problem to be solved is to provide an organometallic vapor phase epitaxy apparatus capable of preventing a film defect from occurring. Another object of the present invention is to provide a metal-organic vapor phase epitaxy apparatus capable of uniformly and sufficiently doping a doping element with another metal-organic gas into a film formed with the first metal-organic gas. The second issue.

[0008]

According to the present invention, the above-mentioned first object is to use an organometallic gas on a lower surface of a substrate which is horizontally conveyed in a reaction chamber filled with a reactive gas by a gas supply nozzle. In the metal-organic vapor phase epitaxy apparatus for supplying a gas to form a functional film on the lower surface of the substrate, the angle α ₁ formed by the axis of the gas supply nozzle and the lower surface of the substrate is 0 ° <α ₁ <90 °. In addition, the metal-organic vapor phase epitaxy apparatus has a configuration in which an edge portion of the gas outlet of the gas supply nozzle that does not face the substrate is retracted from a plane that passes through the edge portion that faces the substrate and is perpendicular to the substrate. Will be solved by

At this time, further, the direction of the gas outlet of the gas supply nozzle is opposite to the substrate carrying direction,
It is preferable to provide a vacuum exhaust port of the apparatus on the side opposite to the substrate transport direction and to provide a substrate transport speed varying mechanism, since it is possible to improve gas use efficiency and productivity. Further, it is more preferable to provide a reservoir for the reaction product dust of the organometallic gas in the middle of the gas supply nozzle or the gas piping line to the gas supply nozzle.

The second problem is that in the metal-organic vapor phase epitaxy apparatus capable of solving the first problem, the gas supply nozzles have different angles α ₁ between the axis of the gas supply nozzle and the lower surface of the substrate. This can be solved by using a metal-organic vapor phase epitaxy apparatus that is provided with a plurality of nozzles and can simultaneously supply a plurality of types of gases to the same location on a substrate.

[0011]

[Function] The angle α ₁ formed by the lower surface, which is the film forming surface of the substrate conveyed in the horizontal direction, and the axis of the gas supply nozzle is 0 ° <α ₁ <
The reaction is performed at 90 ° and the edge of the gas outlet of the gas supply nozzle that does not face the substrate is recessed from the plane perpendicular to the substrate that passes through the edge that faces the substrate. It is possible to prevent the dust of the reaction product separated from the chamber side wall and the upper wall from falling into the nozzle, and it is possible to prevent the generation of a film defect due to the dust of the reaction product. In particular, the larger the substrate, the greater the difference from the prior art, which is effective. The closer α ₁ is to 0, the more effective it is. Also, if the gas outlet of the gas supply nozzle is oriented in the direction opposite to the substrate transport direction and the vacuum exhaust port of the device is installed on the opposite side of the substrate transport direction, the gas flow will be parallel to the substrate surface. Therefore, the gas remaining unreacted at the gas blowing position reacts behind the substrate and contributes to film formation, so that the gas use efficiency is improved. At that time, if the substrate transport speed is constant, the film thickness behind the substrate becomes thicker than the film thickness in front of the substrate in the substrate transport direction. However, this phenomenon is accompanied by a mechanism that can change the substrate transport speed. This can be avoided by moderately accelerating the substrate transfer speed in the rearward direction from the front side of the substrate, which is preferable because it further improves productivity and gas use efficiency.

Even with the apparatus as described above, it is difficult to completely prevent the dust of the reaction product of the organometallic gas from falling into the nozzle, and even a very small amount of dust falls into the nozzle. Then, this is blown out along with the gas flow to generate a film defect. For this reason, it is advisable to provide a dust collecting portion outside the passage through which the gas flows in the nozzle or in the gas piping line to the nozzle, and collect the falling dust here so that it does not get into the gas flow. .
Further, in this case, if the gas flow rate and the film formation pressure in the reaction chamber are appropriately selected so that the lower part of the dust reservoir can be opened to the outside, and the dust falling into the nozzle can be discharged to the outside from the opening, This is desirable because the number of times of cleaning inside the reservoir can be reduced and the operability of the device improves.

Next, in the above apparatus, the gas supply nozzle
Angle α between the axis of the ₁Are different
Providing multiple gas supply nozzles at the same location on the substrate simultaneously
Configured so that several types of gas can be supplied
And a functional film containing a doping element uniformly in the film
The film can be formed favorably. That is, such a device
When used, the base film is formed from one nozzle.
While blowing gas to react on the substrate, the reaction
Doping element from another nozzle to where it is awake
The gas produced by the reaction can be blown out and reacted.
The film, the doping element is uniformly and sufficiently doped.
It becomes possible.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is an explanatory view of essential parts of a MOCVD apparatus of an embodiment for solving the first problem of the present invention. In a reaction chamber (not shown) filled with a reactive gas, an opening 21 as a gas outlet has a rectangular gas supply to the lower surface of the substrate 1 conveyed in the horizontal direction as shown by an arrow A. The nozzle 2 directs the opening 21 in the direction opposite to the arrow A,
1 has one longitudinal edge parallel to the lower surface of the substrate 1, and the angle α ₁ between the axis and the lower surface of the substrate ₁ is 45.
It is arranged so that it becomes °. Then, the opening 21
Is an imaginary plane X which is perpendicular to the lower surface of the substrate 1 and an imaginary plane Y which passes through the edge of the rectangular side of the opening 21 facing the substrate 1 in the longitudinal direction with respect to the lower surface of the substrate 1. The opening is inclined so that the angle β ₁ formed by and becomes 15 °.
That is, the other edge of the opening 21 is retracted from the surface X according to the distance from the lower surface of the substrate 1 with respect to the edge of one side of the rectangular shape of the opening 21 in the longitudinal direction. Reference numeral 3 denotes a gas pipe for supplying an organometallic gas to the gas supply nozzle 2, and a portion 22 below the gas supply nozzle 2 which is deviated from a gas flow indicated by a dotted arrow at a connecting portion between the gas supply nozzle 2 and the gas pipe 3. Form a dust accumulation portion of the reaction product dust. Also, in this apparatus, although not shown, the exhaust port of the reaction chamber is provided in a portion opposite to the substrate transport direction, and further, a mechanism for varying the substrate transport speed is additionally provided, which is required. It is possible to change the transport speed according to the above.

The light emitting layer is MO
An EL device was prepared by forming by CVD. Using a substrate having a size of 200 mm × 150 mm on which a transparent electrode is formed, the substrate is horizontally transported with the transparent electrode as the lower surface in a reaction chamber filled with the reactive gas hydrogen sulfide H ₂ S, and the organic metal gas DMZn ( Dimethyl zinc: Zn (CH ₃ ) ₂ )
Is sprayed to form a light emitting layer, and then an electrode is formed thereon to form an EL element. 10 produced in this way
For each sample, the number of film defects due to dust adhesion on the light emitting layer surface after film formation and the quality of product characteristics in the aging process were examined. In this case, the substrate was transported at a constant speed.

The results are shown in Table 1.

[0017]

[Table 1]

Comparative Example 1 For comparison, an example of forming a light emitting layer was changed except that the gas supply nozzle of the organometallic gas was changed to a nozzle vertical to the substrate as shown in FIG. EL devices were produced in the same manner as in Example 1, and the number of film defects and the quality of product characteristics in the aging process were examined for the 10 samples of Comparative Example 1. The results are shown in Table 2.

[0019]

[Table 2]

From Tables 1 and 2, the film defects in Example 1 are much smaller than those in Comparative Example 1. As a result, the number of products having characteristic defects in the aging process is significantly reduced and the non-defective rate is high. It can be seen that it has improved from 30% to 70%. The effect of the present invention is obvious. Embodiment 2 FIG. 2 is a longitudinal sectional view of a main part of an MOCVD apparatus according to an embodiment for solving the second problem of the present invention.
Further, a gas supply nozzle 2a having the same structure as the gas supply nozzle shown in FIG. 1 and blowing another organometallic gas is added to the apparatus shown in FIG. The same parts as those of the device shown in FIG. 1 are designated by the same reference numerals. The angle α ₂ formed by the axis of the gas supply nozzle 2a and the substrate 1 is 30 °, and the opening 21a passes through the edge of one side in the longitudinal direction of the rectangle parallel to the lower surface of the substrate of the opening 21a and is perpendicular to the lower surface of the substrate 1. The angle β ₂ formed by the imaginary plane X _a and the imaginary plane Y _a formed by the opening is inclined and opened so that the gas supplied from the gas supply nozzle 2 a supplies gas onto the substrate. The nozzles 2 are relatively arranged so that the gas blown out from the nozzle 2 is blown to the same place as it is blown.

Using the apparatus as described above, an EL element having a film doped with an appropriate element as a light emitting layer is manufactured.
In a reaction chamber filled with H ₂ S as a reactive gas, the same substrate as in Example 1 was horizontally transported with the transparent electrode as the lower surface, while DMZ was supplied from the gas supply nozzle 2 and BCPM was supplied from the gas supply nozzle 2a. (bis-methyl cyclopentadienyl _{manganese: Mn (CH 3 C 5 H} 4) 2) were simultaneously reacted by spraying in the same location, thereby forming a doped ZnS film of Mn. In this case, in order to make the film thickness from the front part to the rear part in the substrate transfer direction more uniform, the film formation is performed while changing the transfer speed of the substrate so that it becomes faster as the rear part of the substrate approaches the gas blowing position. I went. Then, an electrode was formed on it to obtain an EL device.

Comparative Example 2 For comparison, regarding the film formation of the light emitting layer, the gas supply nozzle 2 of the organometallic gas for film formation and the gas supply nozzle 2a of the organometallic gas for doping are shown in FIG. 8 of the prior art. EL elements were prepared in the same manner as in Example 2 except that the nozzles were changed to those perpendicular to the substrate and the substrate transport speed was kept constant.
A device was produced.

For the devices of Example 2 and Comparative Example 2, the uniformity and diffusivity of the doping element in the thickness direction of the light emitting layer were examined by a scanning electron microscope (SEM). The result is shown in the diagram of FIG. In FIG. 9, the horizontal axis represents the position of the cross section of the light emitting layer from the substrate side toward the film surface, and the vertical axis represents S.
The intensity of the doping element examined by EM is shown. As can be seen from FIG. 9, the doping element in Example 2 is more uniformly distributed than in Comparative Example 2 in a large amount. From this, using the apparatus of the present invention, in a reaction chamber filled with a reactive gas,
Doping produced by blowing out a first organic metal gas from the gas supply nozzle 2 to cause a reaction to form a film and simultaneously blowing out another second organic metal gas from the second gas supply nozzle 2a to cause a reaction at the same location. It is apparent that doping the element into the film makes it possible to obtain a film in which the doping element is uniformly and sufficiently doped.

Also, the luminance-voltage characteristics of these devices were examined. The result is shown in the diagram of FIG. As can be seen in FIG. 10, the luminance of the device of Example 2 is improved by ²⁰ cd / m ^{2 on} average as compared with the device of Comparative Example 2. This is because the doping element was uniformly and heavily doped in the film of the light emitting layer, and the effect of the present invention is clear.

In the first embodiment described above, the angle α ₁ formed by the axis of the gas supply nozzle 2 and the substrate 1 is 45 °, and the opening 2 is formed.
The angle β ₁ formed by an imaginary plane X perpendicular to the lower surface of the substrate 1 and an imaginary plane Y formed by the opening is 15 °. However, the present invention is not limited to this, and 0 ° <α ₁ <90
It is also effective within the range of ° and 0 ° <β ₁ . Further, α ₂ and β ₂ of Example 2 are 0 ° <α ₁ <α ₂ <90 °, 0 °
It is similarly effective within the range of <β ₂ . Furthermore, when the number of doping elements is not one but n, the number of gas supply nozzles for the doping elements is n, and 0 ° <α _n <α _n-1
<... <α ₂ <α ₁ <90 °, 0 ° <β _1, β _2, ...
, Β _n-1 , and β _n .

[0026]

According to the present invention, the metal-organic vapor phase epitaxy apparatus for forming a functional film on the lower surface of a substrate by supplying the metal-organic gas to the lower surface of the substrate transported in the horizontal direction by a gas supply nozzle. In, the angle α ₁ between the axis of the gas supply nozzle and the lower surface of the substrate is 0 ° <α ₁ <90 °, and the edge of the gas outlet of the gas supply nozzle that does not face the substrate is the substrate. The device is recessed more than the plane perpendicular to the substrate passing through the facing edges. By using such an apparatus, it becomes possible to form a good film with few film defects due to dust of gas reaction products. At this time, if the direction of the gas outlet of the gas supply nozzle is opposite to the substrate transport direction and the vacuum exhaust port of the apparatus is provided on the side opposite to the substrate transport direction, the gas use efficiency is improved. Is obtained, which is preferable. Further, it is preferable to provide a substrate transfer speed varying mechanism because the film thickness can be more uniformly formed. Furthermore, it is preferable to provide a reservoir for the dust of the reaction product of the organometallic gas in the middle of the gas supply nozzle or the gas piping line to the gas supply nozzle, because it is possible to further reduce the occurrence of film defects.

Further, in the above apparatus, a plurality of gas supply nozzles having different angles α ₁ between the axis of the gas supply nozzle and the lower surface of the substrate are provided, and a plurality of kinds of gases are simultaneously supplied to the same location on the substrate. With such a configuration, it is possible to form a film in which one or many kinds of doping elements are uniformly and sufficiently doped. By using such a device, for example, an EL element having good characteristics and high brightness can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of a main part of an embodiment of an apparatus for solving the first problem of the present invention.

FIG. 2 is an explanatory view of a main part of an embodiment of an apparatus for solving the second problem of the present invention.

FIG. 3 is an explanatory view of main parts of an example of a conventional vertical type device.

FIG. 4 is an explanatory view of a main part of an example of a conventional barrel type device.

FIG. 5 is an explanatory view of a main part of a conventional substrate horizontal transfer type device.

FIG. 6 is an explanatory view of a main part showing gas reflection on a substrate in the apparatus of FIG.

7 is an explanatory view of a main part showing a mounting state of a substrate on a substrate holder in the apparatus of FIG.

8 is an explanatory view of a main part showing an example in which a gas supply nozzle is additionally provided for doping a doping element in the apparatus of FIG.

FIG. 9 is a diagram showing a distribution state of doping elements by SEM of a film cross section.

FIG. 10 is a diagram showing luminance-voltage characteristics of EL element samples.

[Explanation of symbols]

1 Substrate 2 Gas Supply Nozzle 2 _a Gas Supply Nozzle 3 Gas Pipe 4 Substrate Holder 5 Reaction Chamber 6 Mask 7 Membrane 21 Opening 21 _a Opening 22 Dust Collecting Part

Claims (5)

[Claims] 1. An organic metal for forming a functional film on the lower surface of the substrate by supplying an organic metal gas to the lower surface of the substrate horizontally conveyed in a reaction chamber filled with the reactive gas with a gas supply nozzle. In the vapor phase growth apparatus, the angle α ₁ between the axis of the gas supply nozzle and the lower surface of the substrate is 0 ° <α ₁ <90 °, and the edge of the gas outlet of the gas supply nozzle that does not face the substrate. A metal-organic vapor phase epitaxy apparatus characterized in that a portion is recessed from a surface perpendicular to the substrate passing through an edge portion facing the substrate. 2. The gas outlet of the gas supply nozzle is oriented in the direction opposite to the substrate transport direction, and the vacuum exhaust port of the reaction chamber is disposed on the side opposite to the substrate transport direction. The organic metal vapor phase growth apparatus described. 3. A metal-organic vapor phase epitaxy apparatus according to claim 2, further comprising a substrate transfer speed varying mechanism. 4. The gas supply nozzle or a gas pipe line to the gas supply nozzle is provided with a reservoir for the dust of the reaction product of the organometallic gas.
The metal-organic chemical vapor deposition apparatus according to any one of the above. 5. A plurality of gas supply nozzles having different angles α ₁ between the axis of the gas supply nozzle and the lower surface of the substrate are provided, and a plurality of kinds of gases can be simultaneously supplied to the same position on the substrate. The metal-organic vapor phase epitaxy apparatus according to any one of claims 1 to 4.