JP2009200112A - Method of producing group iii element added zinc oxide, and substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide group III element added zinc oxide with high crystallinity. <P>SOLUTION: A raw material gas containing a zinc-containing compound, a group III element-containing compound, an oxygen source, and a carrier is passed through a first discharge space 23 (pre-excitation step). Then, the raw material gas is passed through a second discharge space 33 to be brought into contact with a substrate 9 disposed inside or outside the second discharge space 33 (formal discharge processing step). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing zinc oxide to which a group III element is added and a substrate subjected to film formation by the method.

For example, Patent Document 1 discloses a method of imparting conductivity by doping zinc oxide with gallium which is a group III element.
It is known that the conductivity of gallium-doped zinc oxide increases with better crystallinity. Zinc oxide crystals are hexagonal, and the higher the orientation to the (002) plane, the better the quality.
JP 2007-115656 A

When a source gas containing a zinc-containing compound and oxygen is turned into plasma and brought into contact with a substrate, zinc oxide crystals can be generated. According to the experiments by the inventors, the oxygen concentration in the zinc oxide is reduced by increasing the oxygen concentration in the source gas, and the crystal of zinc oxide is preferentially oriented in the (002) plane and the crystallinity is improved. This was confirmed by X-ray diffraction. However, when a gallium-containing compound is further included in the source gas so as to dope the group III element gallium into the crystal, as shown in FIG. 5, as the oxygen concentration in the source gas is increased, (002) The orientation collapsed and the (100) orientation became stronger, and the crystallinity was deteriorated.
In view of the above circumstances, an object of the present invention is to increase the crystallinity of zinc oxide to which a group III element such as gallium is added.

As a result of intensive studies, the inventors have shown that when gallium-containing gas is pre-excited by creeping discharge or the like and then glow-discharged and brought into contact with the substrate, the crystallinity of gallium-doped zinc oxide is good as shown in FIG. I found out that
The present invention has been made based on the above findings, and is a method for producing zinc oxide doped with a group III element on the surface of a substrate,
A preliminary excitation step of passing a source gas containing a zinc-containing compound, a group III element-containing compound, and an oxygen source through the first discharge space;
A main discharge treatment step of passing the source gas after passing through the first discharge space through the second discharge space and contacting a substrate disposed inside or outside the second discharge space;
It is characterized by performing.
Thereby, the crystallinity of the group III element-added zinc oxide can be improved, and the conductivity can be improved.

The zinc-containing compound is selected from the group consisting of a zinc alkoxide compound, a zinc β-diketone compound, a zinc carboxylate compound, a zinc cyclopentadinier compound, and a zinc alkyl compound, preferably a zinc β-diketone compound It is.
The Group III element-containing compound comprises an aluminum or gallium alkoxide compound, an aluminum or gallium β-diketone compound, an aluminum or gallium carboxylate compound, an aluminum or gallium cyclopentadinier compound, or an aluminum or gallium alkyl compound. It is selected from the group and is preferably a β-diketone compound of aluminum or gallium.

  In addition, the present invention is characterized by a substrate having a surface coated with a group III element-added zinc oxide produced by the above method.

  According to the present invention, group III element-added zinc oxide having high crystallinity preferentially oriented in the (002) plane can be generated.

Hereinafter, an embodiment of the present invention will be described.
The present invention produces high crystallinity group III element-added zinc oxide preferentially oriented in the (002) plane. Examples of group III elements include gallium and aluminum. Examples of the group III element-doped zinc oxide include gallium-doped zinc oxide doped with gallium and aluminum-doped zinc oxide doped with aluminum. Here, for example, gallium-doped zinc oxide is generated.

  Group III element-added zinc oxide such as gallium-doped zinc oxide or aluminum-doped zinc oxide is deposited on the surface of the substrate. The substrate may be a silicon wafer, a glass substrate used for a flat panel display (FPD) such as a liquid crystal display or a plasma display, or an organic film used for a flexible substrate.

FIG. 1 schematically shows an example of an apparatus M1 for forming a group III element-added zinc oxide on a substrate 9. The film forming apparatus M1 includes a source gas supply system 10, a preliminary excitation unit 20, and a main discharge processing unit 30.
The source gas supply system 10 generates a source gas having a predetermined composition and supplies the source gas to the preliminary excitation unit 20. The source gas contains a zinc-containing compound (Zn source), a Group III element-containing compound (Group III element source), an oxygen source, and a carrier.

Examples of the zinc-containing compound include a zinc alkoxide compound, a zinc β-diketone compound, a zinc carboxylate compound, a zinc cyclopentadinier compound, an alkyl zinc compound, and the like, and preferably a zinc β-diketone compound. The flow rate ratio of the zinc-containing compound in the raw material gas is preferably 1 × 10 ⁻⁶ to 1 × 10 ⁻⁴ vol%.

Examples of the group III element-containing compound include a gallium-containing compound (Ga source) and an aluminum-containing compound (Al source).
Examples of the gallium-containing compound include gallium alkoxide compounds, gallium β-diketone compounds, gallium carboxylate compounds, gallium cyclopentadinier compounds, gallium alkyl compounds, and the like, preferably gallium β-diketone compounds. .
Examples of the aluminum-containing compound include an aluminum alkoxide compound, an aluminum β-diketone compound, an aluminum carboxylate compound, an aluminum cyclopentadiniel compound, an aluminum alkyl compound, and preferably an aluminum β-diketone compound. .
The flow rate ratio of the group III element-containing compound in the raw material gas is preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁵ vol%.

Examples of the oxygen source include oxygen (O ₂ ), an oxygen-containing compound, H ₂ O, alcohol, and the like, and preferably oxygen (O ₂ ) is used.
The flow rate ratio of the oxygen source (here, oxygen (O ₂ )) in the raw material gas is preferably about 5 to 95 vol%.

The carrier is a gas that can carry and transport the zinc-containing compound or the group III element-containing compound and is inert to the zinc-containing compound or the group III element-containing compound, and preferably a gas that also serves as a plasma source. Is used. Examples of such a gas include He and Ar. He or Ar tends to generate plasma discharge. N ₂ or H ₂ may be used as a carrier, or a mixed gas of N ₂ and H ₂ may be used. When the zinc-containing compound or the group III element-containing compound is a liquid, a gas that is a carrier may be passed through the liquid, or a carrier gas may be passed through a container that stores the liquid.
The flow rate ratio of the carrier in the raw material gas is preferably about 5 to 95 vol%.

  The preliminary excitation unit 20 has a pair of electrodes 21 and 22. One electrode 21 is connected to the power source 6 and the other electrode 22 is electrically grounded. By supplying a voltage from the power source 6, a discharge is generated between the electrodes 21 and 22, and a space between the electrodes 21 and 22 becomes a preliminary excitation space 23 (first discharge space).

  The applied voltage between the electrodes 21 and 22 is preferably about 1 to 20 kV. The distance between the electrodes 21 and 22 is preferably about 0.5 to 2.0 mm. The pressure in the preliminary excitation space 23 is preferably 10 to 100 kPa, and more preferably about 50 kPa. The discharge form of the preliminary excitation space 23 may be creeping discharge, corona discharge, or glow discharge. More preferable is a discharge with uneven appearance such as creeping discharge or corona discharge.

A source gas is introduced into the preliminary excitation space 23. Thereby, the source gas is turned into plasma (decomposition, ionization, excitation, activation, radicalization, ionization, etc.) (preliminary excitation step).
No substrate is disposed in the preliminary excitation space 23.

  The main discharge processing unit 30 is connected to the downstream side of the preliminary excitation unit 20. The discharge processing unit 30 has a pair of electrodes 31 and 32. One electrode 31 is connected to the power source 7 and the other electrode 32 is electrically grounded. By supplying a voltage from the power source 7, a discharge is generated between the electrodes 31, 32, and a space between the electrodes 31, 32 becomes a main discharge space 33 (second discharge space).

  The applied voltage between the pair of electrodes 31 and 32 is preferably about 2 to 15 kV. The distance between the electrodes 31 and 32 is preferably about 0.2 to 2.0 mm. The pressure in the main discharge space 33 is preferably 10 to 100 kPa, and more preferably about 50 kPa. The discharge form of the main discharge space 33 is preferably an apparently uniform glow discharge.

  A substrate 9 is disposed inside the discharge space 33. The substrate 9 is heated by the heater 8. The temperature of the substrate 9 is preferably room temperature to 400 ° C.

The downstream end of the preliminary excitation space 23 is connected to the main discharge space 33.
As a result, the source gas converted into plasma in the preliminary excitation space 23 is introduced into the main discharge space 33. In the main discharge space 33, the source gas is further converted into plasma (decomposition, ionization, excitation, activation, radicalization, ionization, etc.). This source gas converted into plasma comes into contact with the substrate 9. Thereby, a film of group III element-added zinc oxide such as gallium-doped zinc oxide or aluminum-doped zinc oxide having good crystallinity can be formed on the surface of the substrate 9 (this discharge treatment step).

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings for the same configurations as those already described, and the description thereof is omitted.
The substrate 9 may be disposed outside the main discharge space 33 as in the film forming apparatus M2 illustrated in FIG. The source gas is converted into plasma (decomposition, ionization, excitation, activation, radicalization, ionization, etc.) in two stages in the pre-excitation space 23 and the main discharge space 33, and then the jet outlet connected to the downstream end of the main discharge space 33. 34 is ejected from 34 and brought into contact with the substrate 9. Thereby, a film of group III element-added zinc oxide such as gallium-doped zinc oxide or aluminum-doped zinc oxide having good crystallinity can be formed on the surface of the substrate 9.

  In FIG. 2, reference numeral 5 denotes a stage (substrate placement unit) on which the substrate 9 is placed. As the board | substrate arrangement | positioning part 5, you may use what has moving mechanisms, such as a roller conveyor.

Like the film forming apparatus M3 shown in FIG. 3, the preliminary excitation space 23 may be generated by a pair of electrodes that generate the main discharge space 33.
The film forming apparatus M3 includes electrode units 50 and 60 that are vertically opposed to each other. The upper electrode unit 50 has a metal electrode 51. A power source 7 is connected to the electrode 51. The electrode 51 is accommodated in an electrode holder 52 made of a dielectric such as AlN. A frame 53 made of quartz or the like is provided around the holder 52. Gas guide plates 54 and 55 made of a dielectric material such as Al ₂ O ₃ are provided on the left and right outer sides of the frame 53.

The lower electrode unit 60 has a metal electrode 61. The electrode 61 is electrically grounded. A heater 8 is provided inside the electrode 61. A plate 62 that also serves as a substrate mounting portion is provided on the electrode 61. The plate 62 is made of a dielectric such as AlN. A substrate 9 is set on this plate. Gas induction plates 64 and 65 made of a dielectric material such as AlN and Al ₂ O ₃ are provided on the left and right outer sides of the plate. A gas introduction path 6a is defined between the upper and lower gas guide plates 54, 64 on the left side.

  According to the film forming apparatus M3, the voltage is supplied from the power source 7 to the electrode 51, and the source gas is introduced into the gas introduction path 6a by the source gas supply system 10. Here, He or Ar which is easily discharged is used as a carrier component in the source gas. Alternatively, oxygen that tends to cause unstable discharge is used as a carrier. In addition, the supply voltage is increased, the substrate temperature is increased, and the pressure in the space between the electrode units 50 and 60 is decreased as compared with the normal glow discharge generation. Thereby, a glow discharge is generated between the upper and lower electrodes 51 and 61, and a creeping discharge is generated outside the glow discharge. As a result, the central portion of the space between the holder 52 and the substrate 9 becomes the main discharge space 33 in which glow discharge is generated, and the left and right outer portions of the main discharge space 33 are reserved in which creeping discharge is generated. It becomes an excitation space 23.

  The source gas from the introduction path 6 a is converted into plasma in the creeping discharge space 23, then introduced into the main discharge space 33, further converted into plasma, and contacts the substrate 9. Thereby, a film of a group III element-added zinc oxide such as gallium-doped zinc oxide or aluminum-doped zinc oxide having good crystallinity and conductivity can be formed on the surface of the substrate 9. Thereafter, the source gas is discharged through an exhaust path 6b defined between the right gas guide plates 55 and 65.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope obvious to those skilled in the art.
For example, oxygen (O ₂ ) may be used as a carrier. Oxygen (O ₂ ) may be used as an oxygen source and a carrier.
In the embodiment of FIGS. 1 and 2, the pre-excitation power source 6 and the main discharge processing power source 7 may be a common single power source.

Examples will be described. The present invention is not limited to this embodiment.
A gallium-doped zinc oxide film was formed using the apparatus M3 in FIG.
The components and flow rates of the source gas are as follows.
Zn (THD) ₂ as a zinc-containing compound is 9.7 × 10 ⁻³ sccm
As a gallium-containing compound, Ga (THD) ₃ is 4.5 × 10 ⁻⁴ sccm.
Oxygen (O ₂ ) 550 sccm
80sccm the _{N 2} as a carrier
As the substrate 9, a silicon substrate was used. The size of the substrate 9 was 25 mm × 25 mm. The temperature of the substrate 9 was 350 ° C.
The pressure in the space between the upper and lower electrode units 50, 60 was 50 kPa.
The supply voltage was 6 kV.
The distance between the lower surface of the power electrode 51 and the upper surface of the ground electrode 61 was 1 mm.

A creeping discharge 23 was formed on both sides of the glow discharge 33 by applying a voltage between the electrodes 51 and 61.
As shown in FIG. 4, gallium-doped zinc oxide films 9 a and 9 b were formed on the left edge and the center of the substrate 9. The gallium-doped zinc oxide film 9a at the left edge is formed only by the creeping discharge 23, and the gallium-doped zinc oxide film 9b at the center is formed by normal glow discharge after creeping discharge (preliminary excitation). It has been done.

The gallium concentration in the gallium-doped zinc oxide film 9a on the left edge was 3.0 atm%. The gallium concentration in the central portion of the gallium-doped zinc oxide film 9b was 3.2 atm%.
When the films 9a and 9b were analyzed by X-ray diffraction, as shown in FIG. 6, the gallium-doped zinc oxide film 9a on the left edge showed poor orientation but was oriented in the (100) and (101) directions. It became a film. On the other hand, the gallium-doped zinc oxide film 9b in the central portion showed a very strong orientation only in the (002) direction and became a film having high crystallinity. Therefore, it has been found that a gallium-doped zinc oxide film with extremely good crystal orientation can be obtained by performing the main discharge after the preliminary excitation.

  The present invention is applicable to a transparent electrode such as a flat panel display.

1 is a schematic configuration diagram of a film forming apparatus according to a first embodiment of the present invention. It is a schematic block diagram of the film-forming apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the film-forming apparatus which concerns on 3rd Embodiment of this invention. 3 is a plan view of a substrate that has been subjected to film formation according to Example 1. FIG. 6 is an X-ray diffraction chart of zinc oxide (ZnO) and gallium-doped zinc oxide (Ga: ZnO) film-formed by a conventional method. 2 is an X-ray diffraction chart of gallium-doped zinc oxide (Ga: ZnO) film-formed according to Example 1. FIG.

Explanation of symbols

M1, M2, M3 Film forming apparatus 9 Substrate 10 Source gas supply system 20 Preliminary excitation unit 23 Preliminary excitation space (first discharge space)
30 This discharge processing part 33 This discharge space (2nd discharge space)

Claims (4)

A method for producing zinc oxide doped with a group III element on the surface of a substrate,
A preliminary excitation step of passing a source gas containing a zinc-containing compound, a group III element-containing compound, and an oxygen source through the first discharge space;
A main discharge treatment step of passing the source gas after passing through the first discharge space through the second discharge space and contacting a substrate disposed inside or outside the second discharge space;
A method for producing a group III element-added zinc oxide, characterized in that   2. The production method according to claim 1, wherein the zinc-containing compound is selected from the group consisting of an alkoxide compound, a β-diketone compound, a carboxylate compound, a cyclopentadinyl compound, and an alkyl compound of zinc. .   The group III element-containing compound is selected from the group consisting of aluminum or gallium alkoxide compounds, β-diketone compounds, carboxylate compounds, cyclopentadinier compounds, and alkyl compounds. 2. The production method according to 2.   A substrate comprising a surface coated with a group III element-added zinc oxide produced by the method according to claim 1.

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