TWI736839B - Film forming method - Google Patents

Abstract

The present invention provides a film forming method that can suppress the unevenness of the film quality in the X-axis direction of the substrate when an indium oxide-based oxide film is formed on the surface of a substrate. The film forming method of the present invention sets the directions orthogonal to each other in the substrate (Sw) plane as the X-axis direction and the Y-axis direction, and in the vacuum processing chamber (11), the length of the substrate and the X-axis direction are compared The longer targets (Tg ₁ ～Tg ₈ ) of this substrate are arranged concentrically opposite to each other. Rare gases and oxygen are introduced into the vacuum processing chamber in a vacuum environment, and electricity is applied to each target material and the rareness in the plasma environment is used. The ions of the gas sputter the target material, thereby forming an indium oxide-based oxide film on the surface of the substrate. The direction from the target side to the substrate is set upward, and oxygen is introduced toward the substrate from at least one of the first position and the second position. The first position is a position directly below the substrate end region (Sa) in the X-axis direction ; The second position is a position directly below the extended area (Ea) extending from the substrate end (Se) toward the target end in the X-axis direction.

Description

Film forming method

The present invention relates to a film formation method, and more specifically, relates to a film formation of an indium oxide-based oxide film by reactive sputtering in which oxygen is introduced.

For example, in the process of manufacturing a flat panel display (FPD), there is a process of forming a transparent conductive film. In this type of transparent electrode film, an indium oxide-based oxide film such as an ITO film or an ITIO film is used. Condition. In addition, the sputtering method is generally used to form the indium oxide-based oxide film on the surface of the substrate (for example, refer to Patent Document 1).

In addition, when the substrate is a large area such as a glass substrate for FPD, as a sputtering device for forming a film on such a substrate, the X-axis direction is used in the direction orthogonal to each other in the substrate surface. And Y-axis direction, and in the vacuum processing chamber, a plurality of targets whose long sides are in the Y-axis direction are juxtaposed at equal intervals in the X-axis direction so that the length in the X-axis direction becomes longer than the substrate. Situation (for example, refer to Patent Document 2). Among them, the direction from each target material to the substrate is set upward, and a gas pipe is arranged separately from each target material on the lower side of each target material, and from the gas injection port formed in this gas pipe, The reactive gas such as oxygen introduced during the film formation by the reactive sputtering method is introduced.

According to the above configuration, if the reactant gas is introduced through the gas pipe during film formation, the reactant gas will once diffuse in the space below each target, and then be supplied to the space through the gaps between adjacent targets. Substrate. Thereby, it is possible to prevent the reaction gas from being locally and concentratedly supplied to the substrate, and it is possible to prevent the problem of uneven reactivity in the surface of the substrate. However, it has been found that if the sputtering apparatus of this conventional example is used to form an indium oxide-based oxide film by reactive sputtering on a substrate that has become larger in recent years, it is possible to suppress damage to the substrate. When the reactive gas is locally and concentratedly supplied, the film quality in the X-axis direction of the substrate (for example, sheet resistance (Rs)) becomes non-uniform. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2015-994 [Patent Document 2] Japanese Patent No. 4707693

[The problem to be solved by the invention]

Therefore, in view of the above problems, the present invention aims to provide a film forming method that can control the unevenness of the film quality in the X-axis direction of the substrate when forming an indium oxide-based oxide film on the surface of the substrate. . [Means to solve the problem]

In order to solve the above-mentioned problems, the film forming method of the present invention for forming an indium oxide-based oxide film on the surface of a substrate is characterized in that the directions orthogonal to each other in the surface of the substrate are the X-axis direction and the Y-axis direction, and In the vacuum processing chamber, the substrate and the target material longer in the X-axis direction are arranged concentrically opposite to each other, and the rare gas and oxygen are respectively introduced into the vacuum processing chamber in a vacuum environment, and power is applied to each target material. The target material is sputtered with the ions of the rare gas in the plasma environment, by which an indium oxide-based oxide film is formed on the surface of the substrate, and the film forming method includes: from the target side toward the substrate The direction of is set as the process of introducing oxygen from at least one of the first position and the second position toward the substrate. The first position is a position directly below the substrate end region in the X-axis direction; the second position is A position directly below the extended area extending from the substrate end to the target end in the X-axis direction.

According to the present invention, it can be confirmed that even when an indium oxide-based oxide film is formed by reactive sputtering for a large-area substrate in recent years, the X-axis direction of the substrate can be The film quality (for example, sheet resistance value (Rs)) becomes substantially uniform. In addition, in the present invention, the so-called "substrate end area" in the X-axis direction refers to the X-axis direction of the substrate, from the substrate end to within 10% of the length of the substrate in the X-axis direction. The part that extends inside. In this case, it can be confirmed that if it exceeds the range of 10% or less of the length of the substrate in the X-axis direction from the end of the substrate, no matter whether oxygen is introduced from the second position toward the substrate, it cannot be used as a product. The degree of uniformity of the film quality in the X-axis direction of the substrate.

In the present invention, it is more desirable to further introduce the oxygen gas toward the substrate from two positions of the first position and the second position. Based on this, it can be confirmed that the film quality (for example, sheet resistance value (Rs)) in the X-axis direction of the substrate can be made more uniform.

In addition, in the present invention, the aforementioned target material is composed of a plurality of targets arranged at intervals in the X-axis direction, and the area where the targets are arranged as the target material arrangement area is used The length of the target juxtaposition area in the X-axis direction is longer than that of the substrate. In this case, the aforementioned specific position can be set lower than the target juxtaposition area and pass through the gap between two adjacent targets. To introduce oxygen toward the target.

Hereinafter, referring to the drawings, a rectangular glass substrate (for example, a long side of 3400 mm) is used as the substrate Sw, an indium oxide-based oxide film is used as an ITO film, and a reactive sputtering method is used on one of the substrates Sw. The case of forming an ITO film on the surface is taken as an example, and an embodiment of the film forming method of the present invention will be described.

Referring to Figures 1 and 2, SM is a magnetron sputtering device that can implement the film forming method of the present invention. In addition, in the following, the direction from each target toward the substrate Sw based on the posture shown in Fig. 1 is set to be upward, and the surface (below ) The juxtaposition direction of each parallel target material is set as the X-axis direction, and the longitudinal direction of the target material orthogonal to it is set as the Y-axis direction.

The sputtering device SM is, for example, of an in-line type, and has a vacuum chamber 1 that can be maintained at a specific degree of vacuum through vacuum exhaust means (not shown) such as a rotary pump, a turbo molecular pump, etc. And divide the vacuum processing chamber 11. A substrate conveying means 2 is provided in the upper part of the vacuum chamber 1. The substrate conveying means 2 has a well-known structure. For example, it has a carrier 21 that holds the substrate Sw in a state where the bottom surface of the film formation surface is open, and the driving means not shown in the figure is intermittently driven, so that it can be The posture in which the long side matches the X-axis direction sequentially transports the substrate Sw to a specific position in the vacuum processing chamber 11. Next, on the lower side of the vacuum chamber 1 facing the substrate Sw in the vacuum processing chamber 11, a specific number of targets Tg having the same form are juxtaposed at equal intervals in the X-axis direction. In addition, in Figure 1, only the four targets Tg ₁ , Tg ₂ , Tg ₃ , and Tg ₄ on the left in the X-axis direction and the four targets Tg ₅ , Tg ₆ , and Tg 5 on the right in the X-axis direction are shown. Tg ₇ and Tg ₈ , and omit those located between the target material Tg ₄ and Tg ₅ in the center region in the X-axis direction.

Each target material Tg ₁ to Tg ₈ is made of ITO with a specific composition ratio, and has a rectangular outline when viewed in a plane with the long side in the Y-axis direction (see Fig. 2). Each target material Tg ₁ to Tg _{8 is} based on the sputtering surface Ts when it is not in use being located on the same plane parallel to the substrate Sw, and the area where each target material Tg ₁ to Tg ₈ is provided is used as the target The material juxtaposition area Ta is set so that the X-axis direction length of the target juxtaposition area Ta is longer than that of the substrate Sw. The length in the X-axis direction of the target juxtaposition area Ta, for example, is the X-axis direction of the substrate Sw in consideration of the uniformity of the thickness distribution of the ITO film in the X-axis direction when the ITO film is formed under the substrate Sw The width of 1.1 to 1.3 times of the way to make appropriate settings. Further, the width of the X-axis direction of the targets of Tg ₁ ~ Tg _8, although each target Tg considering operability and the like ₁ ~ Tg ₈ to make the appropriate design, but since the targets Tg ₁ ~ Tg ₈ itself may be based Use well-known people, so further explanation will be omitted.

In addition, the targets Tg ₁ to Tg ₈ are bonded to the back plate Bp for cooling the _{targets Tg 1} to Tg ₈ through a bonding material such as indium or tin during sputtering, and are The vacuum processing chamber 11 is installed via an insulating material (not shown) so that the inside of the vacuum processing chamber 11 becomes a potential floating state. In addition, the first ground shield 31 is arranged between the first ground shield 31 and the substrate conveying means 2 so _{as to surround the periphery of each target material Tg 1} to Tg _{8 to prevent sputtering particles and the like from adhering to the vacuum chamber 1} The second ground shield 32 of the inner wall or carrier 21.

Furthermore, the magnet unit 4 is respectively provided below each target material Tg ₁ -Tg ₈ (the side opposite to the sputtering surface Ts). As the magnet unit 4 itself, since a well-known person can be used, a detailed description is omitted here. Next, with the respective magnet unit 4, above the targets of Tg ₁ ~ Tg ₈ (Ts sputtering surface side) are formed of mutually balanced closed loop tunnel-shaped magnetic flux, and for each of the target Tg ₁ The electrons ionized in front of ~Tg ₈ and the secondary electrons generated by sputtering are captured. By this, the electron density in front of _{each target Tg 1} to Tg _{8 can be obtained} Increase and increase the plasma density. Each magnet unit 4 may be connected to the drive shaft 51 of the drive means 5 constituted by a motor or an air cylinder, etc., and be integrated at two locations along the X-axis direction in parallel and at a constant speed. To move back and forth.

Tg in the targets ₁ ~ Tg _8, are connected to output lines from the DC power cables Pk Ps, the Tg may become the targets of ₁ ~ Tg ₈ were put certain power having a negative potential. In addition, a _{plurality of targets can be set as pairs among the target materials Tg 1} to Tg ₈ , and a specific voltage can be alternately changed at a specific frequency (1 to 400KHz) to the paired target materials by alternating current power supply. .

The vacuum chamber 1 is provided with a first gas introduction means 6 for introducing a rare gas such as Ar. The gas introduction means 6 has a gas pipe 61 installed on the side wall of the vacuum chamber 1. The gas pipe 61 is connected to a gas source outside the figure via a mass flow controller 62, and is capable of supplying rare gas at a specific flow rate. It is introduced into the vacuum processing chamber 11. In addition, a second gas introduction means 7 is provided at a specific position in the vacuum chamber 1 below each target material Tg ₁ to Tg _8.

The second gas introduction means 7 has a plurality of gas pipes 71 arranged at equal intervals in the X-axis direction and having a long side in the Y-axis direction. Each gas pipe 71, having a diameter of, for example, based ø5 ~ 10mm of stainless steel, and has a length of the targets Tg ₁ - Tg ₈ equivalent of the Y-axis direction, and in each of the gap Tg ₈ ~ in the target Tg ₁ The position directly below Tp is arranged so as to extend in parallel with the gap Tp. One end of each gas pipe 71 is respectively connected to a collection pipe 72, and the collection pipe 72 is connected to an oxygen source outside the figure via a mass flow controller 73. _{On the target Tg 1} to Tg ₈ side of each gas pipe 71, for example, four injection ports 74 are provided with specific intervals. Next, if the reaction gas is injected from each injection port 74, oxygen gas is supplied toward the substrate Sw through each gap Tp of _{each target material Tg 1} to Tg _8. In addition, the opening diameter of the injection port 74 is appropriately set in accordance with the wall thickness of the gas pipe 71, for example, is set to a range of Φ 0.2 mm to 1 mm (in this embodiment, it is set to 0.4 mm).

In the case of using the sputtering device SM to form an ITO film on the underside of the substrate Sw, the substrate Sw is transported by the substrate transporting means 2, and is set in the target juxtaposition area Ta in the vacuum chamber 1. Concentric location. Next, when the vacuum processing chamber 11 becomes a vacuum environment with a specific pressure, the rare gas at a specific flow rate is introduced through the first gas introduction means 6 and oxygen at a specific flow rate is introduced through the second gas introduction means 7. Next, a specific power having a negative potential is applied to each target Tg ₁ to Tg ₈ through the DC power supply Ps, and a plasma environment is formed in the space between the target juxtaposition area Ta and the substrate Sw. rare gas ions of each target Tg ₁ ~ Tg ₈ for sputtering, and Tg ₁ ~ Tg ₈ scattering of sputtered particles and the reaction product of oxygen adhering to and depositing on the substrate from each of the following target Sw, And the ITO film is formed into a film.

Here, when the ITO film is formed by the sputtering device SM, depending on the size of the substrate Sw (for example, the long side is 3400 mm), if oxygen is introduced through all the gaps Tp between _{the targets Tg 1} to Tg ₈ , The film quality in the X-axis direction of the substrate Sw (for example, sheet resistance (Rs)) will become non-uniform. Therefore, it is necessary to suppress this problem. Therefore, in this embodiment, the portion extending from the substrate end in the range of 10% or less of the length in the X-axis direction of the substrate Sw toward the inner side is defined as the substrate end region Se, and the substrate end faces the target. The part where the material end (that is, the _{outer ends of the target materials Tg 1} and Tg _{8 in} the X-axis direction) extends is set as the extended area Ea, from a specific position directly below the substrate end area Se (this is the first position) and the extended area At least one of the specific positions directly below Ea (here, the second position) introduces oxygen gas toward the substrate Sw. In this embodiment, the first gas pipe 71a and the second gas pipe 71b are present at the first position, and the third gas pipe 71c is present at the second position. 71b and the third gas pipe 71c introduce oxygen gas toward the substrate Sw through the gap Tp between the targets (that is, only from the four targets Tg ₁ , Tg ₂ , Tg ₃ , and Tg _{4 on the left side in the X-axis direction).} The gaps Tp and the gaps Tp between the four targets Tg ₅ , Tg ₆ , Tg ₇ , and Tg ₈ on the right side in the X-axis direction are used to supply oxygen to the substrate Sw).

According to the above, even in the case where an ITO film is formed by reactive sputtering on a substrate Sw that has been enlarged in recent years, the film quality in the X-axis direction of the substrate Sw (for example, the sheet resistance value ( Rs)) becomes approximately equal. In addition, if it exceeds 10% or less of the length of the substrate Sw in the X-axis direction from the substrate end, no matter whether oxygen is introduced from the second position toward the substrate Sw, the substrate X cannot be obtained to the extent that it can be used as a product. The uniformity of the film quality in the axial direction. Moreover, even if oxygen is introduced toward the substrate Sw from the X-axis direction outside the target juxtaposition area Ta, the uniformity of the film quality cannot be obtained similarly.

Next, in order to confirm the effect of the present invention, using the sputtering apparatus shown in FIG. 1, the following experiments were performed to form an ITO film on the substrate Sw by reactive sputtering. Set the target materials Tg ₁ to Tg ₈ to a specific composition ratio made of ITO, and have a profile of 200mm×3400mm×thickness 10mm, and _{set 17 targets Tg 1} to Tg ₈ in the vacuum chamber 1 at an interval of 250mm Inside. In addition, gas pipes 71 (16) are respectively provided below all the gaps Tp between the _{targets Tg 1} to Tg _{8 to be configured to selectively introduce oxygen.} Furthermore, the substrate Sw was set as a glass substrate with a long side of 3400 mm, and as sputtering conditions, the power _{input from each DC power supply Ps to each target Tg 1} to Tg _{8 was} set to 16 kW, and the vacuum processing chamber The pressure in 11 is maintained at 0.4 Pa to control the mass flow controller 62 and introduce Ar, which is a sputtering gas, and introduce oxygen at a specific flow rate.

In invention experiment 1, oxygen was introduced only from the third gas pipes 71c and 71c at the second position and the second gas pipes 71b and 71b at the first position. _{All gas pipes 71 below all gaps Tp between 1} and Tg ₈ introduce oxygen to form an ITO film, and measure the sheet resistance value of the ITO film in the X-axis direction by a well-known method. Figure 3 is a graph showing the standard value of sheet resistance (Rs) relative to the position of the substrate in the X-axis direction. In addition, the standard value of sheet resistance (Rs) is obtained from the average value. Based on this, in Invention Experiment 1, it can be confirmed that the in-plane distribution of the sheet resistance value of the ITO film in the X-axis direction can be better than that of the comparative experiment.

In addition, as another invention experiment, the oxygen introduction position was appropriately changed and the in-plane uniformity of the sheet resistance value was measured. Based on this, when the unevenness of the in-plane distribution in the comparative experiment is set to 1, oxygen is introduced only from the third gas pipes 71c and 71c at the second position and the second gas pipes 71b and 71b at the first position. In the case (invention experiment 1), the in-plane distribution system is 0.2. In addition, when oxygen was introduced only from the first to third gas pipes 71a, 71a, 71b, 71b, 71c, and 71c (invention experiment 2), the in-plane distribution was 0.3. Furthermore, when oxygen was introduced only from the second gas pipes 71b and 71b and the first gas pipes 71a and 71a at the first position (invention experiment 3), the in-plane distribution was 0.3. In addition, in the case where oxygen is introduced only from the third gas pipes 71c and 71c at the second position (invention experiment 4), the in-plane distribution is 0.4, and it is found that only from the first position directly below the substrate end area Sa And/or when oxygen is introduced at the second position directly below the extended area Ea, the in-plane distribution is sufficiently improved. In addition, it can be confirmed that if it exceeds the range of 10% or less of the length of the substrate Sw in the X-axis direction from the substrate end Se, the film quality in the X-axis direction of the substrate Sw cannot be obtained to the extent that it can be used as a product. sex.

Although the above description is directed to the embodiments of the present invention, various modifications can be made without departing from the scope of the technical idea of the present invention. In the above-mentioned embodiment, although the case where an ITO film is formed as an indium oxide-based oxide film is described as an example, it is not limited to this, and the present invention can also be applied to other indium oxide such as ITIO film. In the formation of oxide film. In addition, in the above-mentioned embodiment, as the sputtering apparatus SM that can implement the film forming method of the present invention, although a plurality of targets are used and oxygen is introduced toward the substrate through the gap Tp between the targets. Although the description has been made, as long as it is capable of introducing oxygen from a specific position directly below the substrate end region in the X-axis direction toward the substrate, it is not limited to this, and sputtering apparatuses of other structures may also be applicable.

SM. Substrate (substrate) Sa‧‧‧Substrate end area Se‧‧‧Substrate end Tg ₁ ～Tg ₈ ‧‧‧ITO target Tp‧‧‧Gap between targets

[Figure 1] is a schematic cross-sectional view showing a sputtering apparatus that can implement the film forming method of the embodiment of the present invention, omitting a part of it. [Figure 2] A plan view illustrating the relationship between the target material and the introduction position of the reactive gas. [Figure 3] is a graph of an experiment showing the effect of the present invention.

2‧‧‧Substrate conveying means

4‧‧‧Magnet unit

5‧‧‧Drive

6‧‧‧Gas introduction means

7‧‧‧Second gas introduction means

11‧‧‧Vacuum processing chamber

21‧‧‧Carrier

31‧‧‧First ground shield

32‧‧‧Second ground shield

51‧‧‧Drive shaft

61‧‧‧Gas tube

62‧‧‧Mass Flow Controller

71‧‧‧ (for oxygen) gas tube

71a‧‧‧The first gas pipe

71b‧‧‧Second gas pipe

71c‧‧‧The third gas pipe

72‧‧‧Assembly piping

73‧‧‧Mass Flow Controller

74‧‧‧Injection port

Bp‧‧‧Back plate

Ea‧‧‧Extended area

Pk‧‧‧Output cable

Ps‧‧‧DC power supply

Sw‧‧‧Glass substrate (substrate)

Sa‧‧‧Substrate end area

Se‧‧‧Substrate side

SM‧‧‧(The film forming method of the present invention can be implemented) sputtering device

Tg ₁ ~Tg ₈ ‧‧‧ITO target

Tp‧‧‧Gap between targets

Ts‧‧‧Sputtering surface

Claims (4)

A method of film formation, which is based on the formation of an indium oxide-based oxide film on the surface of a substrate. The substrate and the target material whose length in the X-axis direction is longer than this substrate are arranged concentrically opposite to each other, and the rare gas and oxygen are respectively introduced into the vacuum processing chamber in a vacuum environment, and power is applied to each target material and placed in a plasma environment The rare gas ions are used to sputter the target, thereby forming an indium oxide-based oxide film on the surface of the substrate. The film forming method includes: It is the process of introducing oxygen from at least one of the first position and the second position toward the substrate. The first position is the position directly below the substrate end area in the X-axis direction; the second position is the X-axis The position directly below the extended area extending from the end of the substrate to the end of the target. The aforementioned end of the substrate extends from the end of the substrate within 10% of the length of the substrate in the X-axis direction toward the inside of the X-axis direction. part. The film forming method described in the first item of the scope of the patent application includes a process of further introducing the oxygen gas toward the substrate only from two positions of the first position and the second position. Such as the film forming method described in item 1 or item 2 of the scope of patent application, which Among them, the aforementioned target material is composed of a plurality of targets arranged at intervals in the X-axis direction, and the area where the targets are arranged is the target arrangement area and the targets are arranged in parallel The length of the region in the X-axis direction is longer than that of the substrate, and the aforementioned specific position is set below the target parallel region, and oxygen is introduced toward the target through the gap between the two adjacent targets. The film forming method described in item 3 of the scope of patent application, wherein the oxygen gas is introduced toward the substrate from only two positions of the first position and the second position, and the oxygen gas introduced from the first position is Only through the gap between the two adjacent targets directly below the substrate end area and the gap at the outermost position on one of the X-axis directions and at the outermost position on the other side in the X-axis direction It is introduced intermittently.

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