TW201816150A - Film formation method - Google Patents

Abstract

Provided is a film formation method capable of efficiently forming an aluminum oxide film with stress within specified values while maintaining a specified film formation rate. In the present invention, an aluminum oxide film is formed by: disposing an object S on which a film is to be formed inside a vacuum chamber 1 so as to face aluminum targets 21 and 22; introducing a diluting gas and oxygen gas into the vacuum chamber that is under vacuum; and applying a specified electric power on the targets to sputter the targets and adhere and accumulate the reaction product of the aluminum atoms with oxygen on the surface of the object on which the film is being formed. When doing so, water vapor is introduced inside the vacuum chamber. The pressure of the water vapor is in the range of 1*10<SP>-3</SP> Pa-0.1 Pa.

Description

   Film formation method   

The present invention relates to a film forming method, and more specifically, to a method for forming an aluminum oxide film on the surface of a film formed by sputtering.

From the prior art, an aluminum oxide film has been used as a protective film (passivation film) or an insulating film of a thin film transistor or the like in a display device or a semiconductor device. In the film formation of such an alumina film, those caused by the sputtering method are generally known (for example, refer to Patent Documents 1 and 2), and among them, those using a so-called reactive sputtering method are also used. For general use. In this case, aluminum is used as a target material, and the target material and the film-formed material are arranged in a vacuum chamber to perform vacuum evacuation. If a specific pressure is reached, a rare gas and oxygen for discharge are used. The reaction gas is introduced, for example, a specific electric power having a negative potential is applied to the target, and sputtering is performed on the target. As a result, the reaction product between the aluminum atoms and oxygen scattered from the target material adheres to and accumulates on the film-formed material, and an aluminum oxide film is formed on the surface thereof.

The alumina film formed as described above generally has a stress in the compression direction. However, if the compressive stress becomes large, problems such as a large degree of bending of the substrate may be caused. In this case, if the electric power input to the target is gradually increased, the compressive stress will increase along with this, and if the film formation by sputtering is made, the flow rate of the rare gas used for discharge is reduced and If the pressure in the vacuum chamber is gradually reduced, the same compressive stress will increase. Therefore, if the power input to the target is reduced or the pressure in the vacuum chamber during film formation is increased, an aluminum oxide film with a film stress within a specific value (for example, ± 500 MPa) can be formed. In the future, the film formation rate will decrease.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2003-3259

[Patent Document 2] Japanese Patent Laid-Open No. 2010-114413

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for forming an aluminum oxide film capable of efficiently forming a film stress within a specific value while maintaining a specific film formation rate. .

In order to solve the above problems, the present invention is a film forming method, which is characterized in that: a film forming object and a target made of aluminum or alumina are arranged in a vacuum chamber, and a vacuum chamber in a vacuum atmosphere is arranged; Inside, a rare gas and an oxygen-containing reaction gas are introduced, or only a rare gas is introduced, and a specific power is input to the target to sputter the target, thereby forming alumina on the surface of the film to be formed. For the membrane, hydrogen or water vapor is introduced into the vacuum chamber.

According to the present invention, hydrogen or water vapor is introduced without changing the input power to the target, the partial pressure of the rare gas in the vacuum chamber during the film formation, and the partial pressure of the reaction gas (the amount of sputtering gas introduced). It is an aluminum oxide film capable of forming a film with a lower stress than a case where hydrogen or water vapor is not introduced, while maintaining a specific film forming rate.

In the present invention, when introduced into the vacuum chamber where water vapor is, when caused by the deposition of the sputtering, the ideal, the system inside the vacuum chamber of the steam partial pressure of 1 × 10 ^{- 3} Pa ~ 0.1Pa. According to this, it is possible to reliably reduce the stress of the alumina film while maintaining a specific film formation rate. When the partial pressure of water vapor is 1 × 10 ^-2 Pa, it is confirmed that The compressive stress is set to about -50 MPa. In addition, if the partial pressure of water vapor becomes lower than 1 × 10 ^-3 Pa, it is impossible to form an aluminum oxide film in a state in which the stress is effectively reduced, and if the partial pressure of water vapor becomes If it is higher than 0.1 Pa, for example, an abnormal discharge may be induced and an aluminum oxide film may not be formed.

SM‧‧‧Sputtering Device

1‧‧‧vacuum chamber

2 ₁ 、 2 ₂ ‧‧‧ target

42a‧‧‧Gas tube (for rare gases)

43a‧‧‧Mass flow controller (for rare gases)

42b‧‧‧Gas tube (for reaction gas)

43b‧‧‧mass flow controller (for reaction gas)

42c‧‧‧Gas tube (for water vapor)

43c‧‧‧Mass flow controller (for water vapor)

S‧‧‧ substrate (film-formed)

[Fig. 1] It is a schematic sectional view of a sputtering apparatus which can implement the film forming method of the present invention.

[Fig. 2] A graph showing results of experimental examples showing the effects of the present invention.

Hereinafter, with reference to the drawings, a case where the target is made of aluminum and the film-formed object is a rectangular glass substrate (hereinafter referred to as a substrate S), and an aluminum oxide film is formed by reactive sputtering. As an example, a film forming method according to an embodiment of the present invention will be described.

Referring to FIG. 1, SM is a sputtering system of a magnetron method capable of implementing the film forming method of the present invention. The sputtering device SM is provided with a vacuum chamber 1 having a partitioned film forming chamber 11. In the following, the terms representing the direction such as up and down are based on the posture of the sputtering device SM shown in FIG. 1. At the side wall of the vacuum chamber 1, an exhaust port 12 is opened, and at the exhaust port 12, a vacuum exhaust constituted by a rotary pump, a dry pump, a turbo molecular pump, and the like is connected. The exhaust pipe 13 coming from the means P is configured to be able to evacuate the inside of the film forming chamber 11 and maintain it at a specific pressure (for example, 1 × 10 ^-5 Pa).

In the portion of the vacuum chamber 1 below, is provided by an aluminum-based (e.g., a purity of 99.999%) of the target _{21, 22} and the magnet unit _31, two of the cathode unit ₃₂ composed of Cu. Each of the targets 2 ₁ and 2 ₂ are formed into the same substantially rectangular parallelepiped shape, and underneath them, they are respectively joined by a bonding material (not shown) such as indium, and are sputtered by sputtering. During the film formation, a copper back plate 22 made of the targets 2 ₁ and 2 _{2 was} cooled. Then, in a state of being joined to the back plate 22, each of the targets 2 ₁ and 2 ₂ is provided on the inner surface of the lower portion of the vacuum chamber 1 via an insulator 23 that also serves as a vacuum seal. In this case, each of the targets 2 ₁ and 2 ₂ is vacated with a specific interval in the left-right direction of the film forming chamber 11 and the upper surfaces of the targets 2 ₁ and 2 ₂ when not in use are positioned as described later. The substrates S are parallel in the same plane. In each of the target _21, at _22, are connected to an output line coming from the AC power Pk Ps, and Ps become the AC power by a particular frequency while the targets _21, two _two inputs (e.g. , 1kHz ~ 100kHz) AC power.

The magnet units 3 ₁ and 3 ₂ which are arranged below the back plates 22 (outside of the vacuum chamber 1) are respectively provided with the same shape. The magnet units 3 ₁ and 3 ₂ are provided with The back plate 22 is a support plate 31 (yoke) which is provided in parallel and is made of a flat plate made of a magnetic material. On the support plate 31, a center magnet 32 arranged on the center line of the support plate 31 and a circle arranged along the outer periphery of the support plate 31 so as to surround the periphery of the center magnet 32 are arranged. The peripheral magnets 33 are arranged in such a manner that the polarities of the targets 2 ₁ and 2 _{2 are} changed. In this case, for example, the conversion of the volume of the center magnet 32 into the same magnetization and the conversion of the surrounding magnet 33 surrounding it to the sum of the same magnetization volume (peripheral magnet: central magnet: peripheral magnet = 1: 2: 1 (refer to Figure 1)). As a result, a tunnel-like leakage magnetic field (not shown) is formed above each of the targets 2 ₁ and 2 ₂ in a balanced manner. The central magnet 32 and the peripheral magnets 33 are well-known things such as neodymium magnets. These central magnets 32 and the peripheral magnets 33 may be integrated, or a plurality of magnet pieces of a specific volume may be provided in plural. Set up the composition. Further, for example, the target _{21, 22} of the improved efficiency, may also be configured as system _31, connected to drive means (not shown), and the sputtering film formation due to the magnet unit 3 ₂ In the middle, at least one direction of the up-down direction or the left-right direction is reciprocated with a specific stroke.

Further, gas supply ports 41a and 41b are opened at the side walls of the vacuum chamber 1, and gas pipes 42a and 42b are connected to the gas supply ports 41a and 41b, respectively. The gas pipes 42a and 42b are passed through the mass flow controllers 43a and 43b, and are respectively connected to a gas source of a rare gas such as argon and the like and a gas source of an oxygen-containing reaction gas such as oxygen or ozone. In addition, a rare gas and a reaction gas whose flow rate can be introduced into the film forming chamber 11 can be introduced.

In the case where each target 2 ₁ , 2 ₂ is sputtered by the above-mentioned sputtering device SM, and an aluminum oxide film is formed by reactive sputtering on the surface of the substrate S, it is based on The vacuum conveying robot places the substrate S at a specific position on the upper part of the film forming chamber 11 opposite to the targets 2 ₁ and 2 ₂ arranged side by side, and evacuates the film forming chamber 11 to a specific pressure all the time. until. When the film forming chamber 11 reaches a specific pressure, the mass flow controllers 43a and 43b are controlled to introduce a rare gas and a reaction gas, and AC power is input between the targets 2 ₁ and 2 ₂ by an AC power source Ps. . As a result, a high-density plasma is generated in a racetrack shape above each of the targets 2 ₁ and 2 ₂ . In addition, the targets 2 ₁ and 2 ₂ are sputtered by the ions of the rare gas in the plasma. As a result, the reaction product between the aluminum atoms and oxygen scattered from the targets 2 ₁ and 2 ₂ is deposited and deposited on the surface of the substrate S to form an aluminum oxide film.

Here, the alumina film formed as described above generally has a stress in the compression direction. However, if the compressive stress becomes large, problems such as a large degree of bending of the substrate may be caused. Therefore, it is necessary to be an aluminum oxide film capable of efficiently forming a film forming stress within a specific value (for example, ± 500 MPa) while maintaining a specific film forming rate. In this embodiment, a gas supply port 41c is further provided at the side wall of the vacuum chamber 1, and a gas pipe 42c in which a mass flow controller 43c is interposed is connected to the gas supply port 41c, so that it can be configured for film formation. The chamber 11 is supplied with water vapor whose flow rate is controlled. In addition, for example, in the case of film formation by sputtering, it is assumed that water vapor is introduced into the film formation chamber 11 by controlling the mass flow controller 43c. In this case, it is desirable to use the mass flow controller 43c so that the partial pressure of the water vapor in the film forming chamber 11 during film formation will be in the range of 1 × 10 ^-3 Pa to 0.1 Pa. Control the flow of water vapor.

According to the above configuration, the input power to the targets 2 ₁ and 2 ₂ and the partial pressure of the rare gas and the reaction gas during film formation are not changed (that is, the mass flow controllers 43 a and 43 b) The introduction of water vapor by controlling the introduction amount of the rare gas and the reaction gas) can reduce the stress of film formation compared with the case where no water vapor is introduced, while maintaining a specific film formation rate. Alumina film. At this time, if the water vapor partial pressure range of 1 × 10 ^-3 Pa ~ 0.1Pa, the system is able to reliably reduce the stress of the aluminum oxide film, for example, when the partial pressure of water vapor of 1 × 10 ^{- At 2} Pa, it was confirmed that the compressive stress can be set to about -50 MPa. In addition, if the partial pressure of water vapor becomes lower than 1 × 10 ^-3 Pa, it is impossible to form an aluminum oxide film in a state in which the stress is effectively reduced, and if the partial pressure of water vapor becomes If it is higher than 0.1 Pa, for example, an abnormal discharge may be induced and an aluminum oxide film may not be formed.

In order to confirm the above effects, an experiment was performed to form an aluminum oxide film on the surface of the substrate S using the sputtering device SM shown in FIG. 1. First, as a comparative experiment, the distance between each of the targets 2 ₁ and 2 ₂ and the substrate S was set to 180 mm, and the input power (AC power) between the targets 2 ₁ and 2 ₂ caused by the AC power source Ps was set. It was set to 40 kW, and the sputtering time was set to 271 seconds. The mass flow controllers 43a and 43b were operated in such a manner that the pressure in the film forming chamber 11 being vacuum-evacuated was maintained at 0.5 Pa. Argon and oxygen as rare gases were controlled to be introduced at a flow rate of 8: 2. The film formation rate and stress of the alumina film formed on the surface of the substrate S were measured at the center of the substrate S. As a result, the film formation rate was 10.56 nm / min and the stress was About -1000MPa (compressive stress). The film thickness was measured using an elliptical polarimeter, and the stress was measured using a thin film stress measuring device.

Next, as an experiment to demonstrate the effect of the present invention, the sputtering conditions were set to be the same as described above, and during film formation, the mass flow controller 43c was controlled and water vapor was also introduced at a specific flow rate. In this case, the partial pressure of water vapor is changed in the range of 5 × 10 ^-4 Pa ~ 1Pa, and the change in stress (MPa) of the alumina film at this time is shown in FIG. 2. According to this, if water vapor is introduced, the stress of the alumina film is reduced. When the partial pressure of water vapor is 1 × 10 ^-3 Pa, it can be known that the stress of the alumina film can be reduced to about − Around 500MPa. The film formation rate at this time was 10.48 nm / min, and it was confirmed that there was almost no change in the film formation rate. It was also confirmed that until the partial pressure of water vapor becomes 1 × 10 ^-2 Pa, the stress of the alumina film is further reduced in proportion to the partial pressure of the water vapor, and when the partial pressure of water vapor becomes 1 × At 10 ^-2 Pa, the stress of the alumina film can be set to about -50 MPa. The film formation rate at this time was 11.00 nm / min. It was also confirmed that if the partial pressure of water vapor is further increased, the stress of the alumina film becomes a stress having a tensile direction (tensile stress), even when the partial pressure of water vapor is 0.1 Pa, The stress of the alumina film can also be set to about +100 MPa. The film formation rate at this time was 11.20 nm / min. However, if the partial pressure of water vapor becomes higher than 0.1 Pa, an abnormal discharge is induced, and an alumina film cannot be formed normally.

Although the embodiment of the film-forming method of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment. In the above-mentioned embodiment, the case where water vapor is introduced at a specific partial pressure during film formation by sputtering is described as an example, but it is confirmed that even if the When hydrogen gas is introduced at a specific partial pressure, the stress of the alumina film can be reduced. In the above-mentioned embodiment, although the introduction of rare gas, oxygen, and water vapor from the gas supply ports 41a, 41b, and 41c provided on the side wall of the vacuum chamber 1 has been described as an example, but , Department is not limited to this. Although it is not particularly illustrated, for example, a gas pipe may be installed through the bottom wall of the vacuum chamber 1 and ejected from the front end of the gas pipe located around the targets 2 ₁ and 2 ₂ . Noble gas, oxygen or water vapor.

In the above embodiment, the case where the targets 2 ₁ and 2 _{2 are} made of aluminum has been described as an example. However, even if the targets 2 ₁ and 2 _{2 are} made of alumina The present invention can also be applied to the case where only a rare gas is introduced, or oxygen is introduced together with the rare gas, and high-frequency power is input while sputtering the target materials 2 ₁ and 2 ₂ into a film. Furthermore, although a plurality of targets 2 ₁ and 2 _{2 are} arranged side by side, and a pair of targets are inputted with AC power through the AC power source Ps as an example, the system is not limited to this. Therefore, the present invention can be applied to a case where one target is used and DC power is inputted from a DC power source. Furthermore, in the above-mentioned embodiment, although the case where the film-formation object was made into the glass substrate was demonstrated as an example, for example, the film-formation thing can also be set as the resin base material. In this case, even when the sheet-like substrate is moved at a constant speed between the driving roller and the winding roller, and an aluminum oxide film is formed by sputtering on one surface of the substrate, , Can also apply the present invention.

Claims (2)

    A film forming method is characterized in that: a film forming object and an aluminum or alumina target are arranged in a vacuum chamber, and a rare gas and an oxygen-containing reaction are introduced into the vacuum chamber in a vacuum atmosphere A gas or only a rare gas is introduced, and a specific power is input to the target to perform sputtering on the target, thereby forming an aluminum oxide film on the surface of the film to be formed, and introducing hydrogen or water vapor.     The film-forming method described in the scope of patent application No. 1 is for a person who introduces water vapor into a vacuum chamber, and when the film is formed by the sputtering, the partial pressure of the water vapor in the vacuum chamber is reduced. The range is 1 × 10 ^-3 Pa to 0.1 Pa.