JP2017226887A - Film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method capable of efficiently depositing an aluminum oxide film having a stress within a specified range, while keeping a predetermined film deposition rate.SOLUTION: A material S on which a film is deposited is arranged oppositely to targets 2,2made of aluminum in a vacuum chamber 1. A rare gas and oxygen gas are introduced into the vacuum chamber under a vacuum atmosphere. Specified electric power is applied to the targets to subject the targets to sputtering and thus a reaction product of an aluminum atom and oxygen is stuck to and deposited on the surface of the material on which a film is deposited to form an aluminum oxide film. At the same time, steam having a partial pressure in the range of 1×10Pa-0.1 Pa is introduced into the vacuum chamber.SELECTED DRAWING: Figure 1

Description

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

  An aluminum oxide film is conventionally used as a protective film (passivation film) or an insulating film for an element such as a thin film transistor in a display device or a semiconductor device. For the formation of such an aluminum oxide film, a sputtering method is generally known (for example, see Patent Documents 1 and 2), and among these, a method using a so-called reactive sputtering method is generally used. In this case, a target made of aluminum is used as the target, and the target and the deposition target are placed in a vacuum chamber and evacuated. Then, for example, a predetermined power having a negative potential is applied to the target to sputter the target. As a result, a reaction product of aluminum atoms and oxygen scattered from the target adheres to and deposits on the deposition target, and an aluminum oxide film is formed on the surface.

  The aluminum oxide film formed as described above usually has a stress in the compression direction. However, when the compressive stress increases, problems such as an increase in warpage of the substrate are caused. In this case, as the power supplied to the target is increased, the compressive stress increases accordingly, and the flow rate of the rare gas for discharge is decreased during the film formation by sputtering to lower the pressure in the vacuum chamber. Similarly, the compressive stress increases as well. For this reason, an aluminum oxide film having a stress within a predetermined value (for example, ± 500 MPa) can be formed by lowering the electric power supplied to the target or increasing the pressure of the vacuum chamber at the time of film formation. The film formation rate is lowered.

JP 2003-3259 A JP 2010-114413 A

  In view of the above, it is an object of the present invention to provide a film forming method capable of efficiently forming an aluminum oxide film having a stress within a predetermined value while maintaining a predetermined film forming rate. Is.

  In order to solve the above-described problems, the present invention provides a deposition object and an aluminum or aluminum oxide target in a vacuum chamber, and a reaction containing a rare gas and oxygen in the vacuum chamber in a vacuum atmosphere. In a film formation method for forming an aluminum oxide film on the surface of an object to be deposited by introducing only a gas or a rare gas, applying a predetermined power to the target, and sputtering the target, hydrogen gas or water vapor is placed in a vacuum chamber It is characterized by introducing.

  According to the present invention, by introducing hydrogen gas or water vapor without changing the input power to the target and the partial pressure of the rare gas and reaction gas in the vacuum chamber during deposition (introduction amount of sputtering gas), a predetermined value is obtained. Thus, an aluminum oxide film having a lower stress can be formed as compared with the case where hydrogen gas or water vapor is not introduced while maintaining the film formation rate.

In this invention, when water vapor | steam is introduce | transduced in a vacuum chamber, it is preferable to make the partial pressure of the said water vapor | steam in a vacuum chamber into the range of 1 * 10 < ^-3 > Pa-0.1Pa at the time of the film-forming by the said sputtering. According to this, the stress of the aluminum oxide film can be reliably reduced while maintaining a predetermined film formation rate. When the partial pressure of water vapor is 1 × 10 ⁻² Pa, the compressive stress is reduced to about −50 MPa. It was confirmed that it was possible. When the partial pressure of water vapor is lower than 1 × 10 ⁻³ Pa, an aluminum oxide film cannot be formed in a state where stress is effectively reduced, and the partial pressure of water vapor is higher than 0.1 Pa. In this case, for example, an abnormal discharge may be induced and an aluminum oxide film may not be formed.

The schematic cross section of the sputtering device which can enforce the film-forming method of this invention. The graph which shows the result of the experiment example which shows the effect of this invention.

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

Referring to FIG. 1, SM is a magnetron type sputtering apparatus capable of performing the film forming method of the present invention. The sputtering apparatus SM includes a vacuum chamber 1 that defines a film forming chamber 11. In the following, terms indicating directions such as “up” and “down” are based on the attitude of the sputtering apparatus SM shown in FIG. An exhaust port 12 is formed in the side wall of the vacuum chamber 1, and an exhaust pipe 13 from a vacuum exhaust means P configured by a rotary pump, a dry pump, a turbo molecular pump, or the like is connected to the exhaust port 12 to form a film forming chamber. 11 is evacuated and can be maintained at a predetermined pressure (for example, 1 × 10 ⁻⁵ Pa).

In the lower part of the vacuum chamber 1, two cathode units Cu composed of targets 2 ₁ and 2 ₂ made of aluminum (for example, purity 99.999%) and magnet units 3 ₁ and 3 ₂ are provided. . Each of the targets 2 ₁ and 2 ₂ is formed in the same substantially rectangular parallelepiped shape, and a copper backing plate 22 for cooling the targets 2 ₁ and 2 ₂ is formed on the lower surface of the targets 2 ₁ and 2 ₂ during the film formation by sputtering. Each of them is bonded via a bonding material (not shown) such as indium. Then, the targets 2 ₁ and 2 ₂ are installed on the lower inner surface of the vacuum chamber 1 through an insulator 23 that also serves as a vacuum seal while being bonded to the backing plate 22. In this case, the targets 2 ₁ and 2 ₂ are spaced apart from each other by a predetermined distance 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 parallel to a substrate S to be described later. It is located in the same plane. Each target ₂ 1, _{2 2,} AC power supply output Pk from Ps are respectively connected, the AC power source each target ₂ 1 by Ps, _{2 2} between the predetermined frequency (e.g., 1 kHz to 100 kHz) AC power is turned on It has become so.

The magnet units 3 ₁ and 3 ₂ arranged below the respective backing plates 22 (outside the vacuum chamber 1) have the same configuration, and the magnet units 3 ₁ and 3 ₂ are parallel to the backing plate 22. Provided with a support plate 31 (yoke) composed of a flat plate made of a magnetic material. On the support plate 31, a central magnet 32 disposed on the center line of the support plate 31, and a periphery disposed annularly along the outer periphery of the upper surface of the support plate 31 so as to surround the center magnet 32 A magnet 33 is provided to change the polarity of the targets 2 ₁ and 2 ₂ . In this case, for example, the volume when converted into the same magnetization of the central magnet 32 and the volume when converted into the same magnetization of the peripheral magnet 33 surrounding the periphery (peripheral magnet: central magnet: peripheral magnet = 1: 2: 1 (see FIG. 1)). As a result, tunnel-like leakage magnetic fields (not shown) balanced above the targets 2 ₁ and 2 ₂ are formed. The central magnet 32 and the peripheral magnet 33 are known ones such as neodymium magnets, and these central magnets and peripheral magnets may be integrated, or may be configured by arranging a plurality of magnet pieces having a predetermined volume. . For example, in order to increase the utilization efficiency of the targets 2 ₁ and 2 ₂ , a driving means (not shown) is connected to the magnet units 3 ₁ and 3 ₂ , and at least one of the vertical direction and the horizontal direction is formed during film formation by sputtering. You may make it reciprocate by a predetermined stroke in a direction.

  Gas supply ports 41a and 41b are opened on 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 connected to a gas source of a rare gas (not shown) such as argon and a gas source of an oxygen-containing reaction gas such as oxygen gas and ozone via the mass flow controllers 43a and 43b, respectively. A rare gas and a reactive gas whose flow rate is controlled can be introduced into the film chamber 11.

When sputtering the targets 2 ₁ and 2 ₂ by the sputtering apparatus SM and forming an aluminum oxide film on the surface of the substrate S by reactive sputtering, the targets 2 ₁ and 2 arranged in parallel by a vacuum transfer robot (not shown). _The substrate S is set at a predetermined position above the film forming chamber 11 facing _2, and the film forming chamber 11 is evacuated to a predetermined pressure. When the film forming chamber 11 reaches a predetermined pressure, the noble gas and the reactive gas are introduced by controlling the mass flow controllers 43a and 43b, and AC power is supplied between the targets 2 ₁ and 2 ₂ by the AC power source Ps. Thereby, high-density plasma is generated in a racetrack above each of the targets 2 ₁ and 2 ₂ . Then, the targets 2 ₁ and 2 ₂ are sputtered by rare gas ions in the plasma. As a result, a reaction product of aluminum atoms and oxygen scattered from the targets 2 ₁ and 2 ₂ adheres to and accumulates on the surface of the substrate S to form an aluminum oxide film.

Here, the aluminum oxide film formed as described above usually has a stress in the compression direction. However, when the compressive stress increases, problems such as an increase in the warpage of the substrate are caused. For this reason, it is necessary to be able to form an aluminum oxide film having a stress within a predetermined value (for example, ± 500 MPa) while maintaining a predetermined film formation rate. In the present embodiment, a gas supply port 41 c is further opened on the side wall of the vacuum chamber 1, and a gas pipe 42 c with a mass flow controller 43 c interposed is connected to the gas supply port 41 c so that the flow rate is controlled in the film forming chamber 11. Water vapor can be introduced. For example, during film formation by sputtering, the mass flow controller 43 c is controlled to introduce water vapor into the film formation chamber 11. In this case, it is preferable to control the flow rate of water vapor by the mass flow controller 43c so that the partial pressure of water vapor in the film formation chamber 11 during film formation is in the range of 1 × 10 ⁻³ Pa to 0.1 Pa.

According to the above, the input power to the targets 2 ₁ and 2 ₂ , the partial pressure of the rare gas and the oxygen gas at the time of film formation (that is, the introduction amount of the rare gas and the reactive gas by the control of the mass flow controllers 43a and 43b). By introducing water vapor without changing the temperature, it is possible to form an aluminum oxide film having a lower stress than in the case where water vapor is not introduced while maintaining a predetermined film formation rate. At this time, if the partial pressure of water vapor is in the range of 1 × 10 ⁻³ Pa to 0.1 Pa, the stress of the aluminum oxide film can be reliably reduced. For example, the partial pressure of water vapor is 1 × 10 ^−2. When it was Pa, it was confirmed that the compressive stress could be about -50 MPa. When the partial pressure of water vapor is lower than 1 × 10 ⁻³ Pa, an aluminum oxide film cannot be formed in a state where stress is effectively reduced, and the partial pressure of water vapor is higher than 0.1 Pa. In this case, 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 in which an aluminum oxide film was formed on the surface of the substrate S using the sputtering apparatus SM shown in FIG. First, as a comparative experiment, the distance between the targets 2 ₁ and 2 ₂ and the substrate S is 180 mm, the input power (AC power) between the targets 2 ₁ and 2 ₂ by the AC power source Ps is 40 kW, and the sputtering time is 271. And the mass flow controllers 43a and 43b are controlled so that the argon and oxygen gases as rare gases are set to 8 so that the pressure in the film forming chamber 11 being evacuated is maintained at 0.5 Pa. : Introduced at a flow rate ratio of 2. Then, when the film formation rate and stress of the aluminum oxide film formed on the surface of the substrate S were measured at the center of the substrate S, the film formation rate was 10.56 nm / min and the stress was about −1000 MPa (compressive stress). )Met. The film thickness was measured using an ellipsometer, and the stress was measured using a thin film stress measuring device.

Next, as an experiment showing the effect of the present invention, the sputtering conditions were the same as described above, and water vapor was also introduced at a predetermined flow rate by controlling the mass flow controller 43c during film formation. In this case, the partial pressure of water vapor is changed in the range of 5 × 10 ⁻⁴ Pa to 1 Pa, and the change in stress (MPa) of the aluminum oxide film at that time is shown in FIG. According to this, when water vapor is introduced, the stress of the aluminum oxide film is reduced, and when the partial pressure of the water vapor is 1 × 10 ⁻³ Pa, it can be seen that the stress of the aluminum oxide film can be reduced to about −500 MPa. . The film formation rate at this time was 10.48 nm / min, and it was confirmed that the film formation rate hardly changed. And until the partial pressure of water vapor reaches 1 × 10 ⁻² Pa, the stress of the aluminum oxide film is further reduced in inverse proportion to the partial pressure of water vapor, and when the partial pressure of water vapor is 1 × 10 ⁻² Pa It was confirmed that the stress of the aluminum oxide film could be about -50 MPa. The film formation rate at this time was 11.00 nm / min. Further, when the partial pressure of water vapor is increased, the aluminum oxide film has a stress in the tensile direction (tensile stress), and even when the partial pressure of water vapor is 0.1 Pa, the stress of the aluminum oxide film is increased to about +100 MPa. It was confirmed that it was possible. The film formation rate at this time was 11.20 nm / min. However, when the partial pressure was higher than 0.1 Pa, abnormal discharge was induced and the aluminum oxide film could not be formed normally.

Although the embodiments of the film forming method of the present invention have been described above, the present invention is not limited to the above. In the above embodiment, the case where water vapor is introduced at a predetermined partial pressure during film formation by sputtering has been described as an example. However, the present invention is not limited to this, and the case where hydrogen gas is introduced at a predetermined partial pressure is also described. It was confirmed that the stress of the aluminum oxide film can be reduced. In the above embodiment, the case where the rare gas, the oxygen gas, and the water vapor are introduced from the gas supply ports 41a, 41b, 41c opened on the side wall of the vacuum chamber 1 has been described as an example. However, the present invention is not limited to this. . Although not specifically illustrated and described, for example, a gas pipe is inserted into the bottom of the vacuum chamber 1 and rare gas, oxygen gas, or water vapor is ejected from the tip of the gas pipe positioned around the targets 2 ₁ and 2 _2. You may do it.

In the above embodiment, the target 2 ₁ , 2 ₂ is made of aluminum. However, the target 2 ₁ , 2 ₂ is made of aluminum oxide, and only the rare gas or oxygen added to the rare gas is used. The present invention can also be applied to the case where the target 2 ₁ , 2 ₂ is sputtered by forming a film while introducing high frequency power. Furthermore, the description has been given by taking as an example the case where a plurality of targets 2 ₁ and 2 ₂ are arranged side by side and AC power is supplied to the pair of targets by the AC power supply Ps, but the present invention is not limited to this, and the targets are not limited. The present invention can also be applied to a case in which DC power is supplied from a DC power source. Furthermore, although the said embodiment demonstrated to the example the case where a film-forming thing was used as the glass substrate, it is good also considering a film-forming thing as a resin-made base material, for example. In this case, the present invention can also be applied to an apparatus in which an aluminum oxide film is formed on one surface of a base material by sputtering while moving the sheet-like base material at a constant speed between a driving roller and a take-up roller. .

SM ... Sputtering device, 1 ... Vacuum chamber, 2 ₁ , 2 ₂ ... Target, 42a ... Gas pipe (for rare gas), 43a ... Mass flow controller (for rare gas), 42b ... Gas pipe (for reactive gas), 43b ... Mass flow controller (for reaction gas), 42c ... gas pipe (for water vapor), 43c ... mass flow controller (for water vapor), S ... substrate (film formation).

In order to solve the above-described problems, the present invention provides a deposition object and an aluminum or aluminum oxide target in a vacuum chamber, and a reaction containing a rare gas and oxygen in the vacuum chamber in a vacuum atmosphere. In a film formation method for forming an aluminum oxide film on the surface of an object to be deposited by introducing only a gas or a rare gas, applying a predetermined power to the target, and sputtering the target, hydrogen gas or water vapor is placed in a vacuum chamber. When forming a film by sputtering, water vapor is present in the vacuum chamber at a predetermined partial pressure, and an aluminum oxide film having a stress within a predetermined value is obtained . In this case, it is more preferable that the partial pressure of the water vapor is in the range of 2 × 10 ⁻³ Pa to 0.1 Pa. Preferably, at least two of the targets are provided in a vacuum chamber, and each target is sputtered by supplying AC power of a predetermined frequency between the paired targets.

Claims (2)

An object to be deposited and a target made of aluminum or aluminum oxide are placed in a vacuum chamber, and only a rare gas and an oxygen-containing reactive gas or a rare gas are introduced into the vacuum chamber in a vacuum atmosphere, and a predetermined target is applied to the target. In a film formation method for forming an aluminum oxide film on the surface of an object to be deposited by applying power and sputtering a target,
A film forming method, wherein hydrogen gas or water vapor is introduced into a vacuum chamber. The film forming method according to claim 1, wherein water vapor is introduced into the vacuum chamber.
The film forming method according to claim 1, wherein the partial pressure of the water vapor in the vacuum chamber is set to a range of 1 × 10 ⁻³ Pa to 0.1 Pa during the film formation by sputtering.

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