JP2000045069A - Magnetron sputtering device and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of the thickness of a film on a substrate and to prolong the service life of a target by oppositely arranging a substrate and a planar target in a film forming chamber, placing their centers on the same axis and introducing sputtering gases from plural gas introducing ports therein in such a manner that the amounts thereof to be introduced are respectively controllable. SOLUTION: In a chamber provided with a chimney 16 for preventing sticking and connected to a vacuum pump 8, a circular substrate 1 and a planar target 2 are oppositely arranged, and the respective centers are placed on a center axis C. This chamber 7 is provided with sputtering gas introducing ports 18 at >=3 places, from which sputtering gases are introduced through mass flow controllers 5' and 5" and valves 6' and 6". Then, voltage is applied from a high voltage power source 10 to an electrode 9 provided with a magnet placed with a target 2. In this way, plasma is generated, and the target 2 is sputtered to form a thin film on a substrate 1. At this time, while flow rate set value in the mass flow controllers 5' and 5" is changed from the initial stage of the use of the target 2 to the end of the life, the amounts of the gases to be introduced are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetron sputtering apparatus and a sputtering method.

[0002]

2. Description of the Related Art As a technique for depositing a thin film on a substrate, a magnetron sputtering technique is used. The magnetron sputtering technique can perform low-temperature high-speed sputtering, and is the mainstream in a film forming apparatus using the current sputtering technique. Magnetron sputtering technology generates plasma near the target by discharging, etc.
Particles are sputtered by colliding ions of the plasma with a target, and a thin film is formed by a method of attaching the sputtered particles to a substrate.

A conventional example will be described with reference to FIGS. 6, 7 and 8. FIG. 6 is a sectional view showing a film forming chamber of a magnetron sputtering apparatus using a conventionally used flat plate target. First, the structure of the apparatus will be described. 2 is a flat target, 3 is a magnet arranged on the back of the target, 4 is a magnet 2
Is a magnetic field formed by Further, 5 is a mass flow controller for controlling a flow rate of a sputtering gas (generally, an argon gas) to be introduced to generate a discharge.
Is a valve for shutting off the sputtering gas when the chamber 7 is evacuated to a high vacuum, 8 is a pump for evacuating the chamber 7 to a high vacuum, and 10 is a high voltage power supply for applying a high voltage to the electrode 9. Reference numeral 17 denotes an earth shield.

Next, the operation will be described. In the chamber 7, the substrate 1 and the flat plate target 2 are arranged so as to face each other such that their centers are coaxial with respect to the central axis C.
Is supplied to the target 2 from the high-voltage power supply 10 for glow discharge, high-density plasma for sputtering confined by the magnetic field lines of the magnetic field 4 is generated. When the ions in the plasma collide with the surface of the target 2, atoms of the target 2 are sputtered and adhere to the surface of the substrate 1 facing the target 2 to form a thin film.

[0005]

In the above magnetron sputtering apparatus, the density of the plasma is
In the region indicated by reference numeral 11 in FIG. Since the target 2 is eroded by the plasma, the erosion rate of the target 2 increases near the region 11 where the plasma density is high, and particularly the target 2 near the region indicated by the reference numeral 12 located immediately below the center of the region 11 where the plasma density is high. The erosion rate of No. 2 is locally increased. FIG. 7 is a diagram showing the erosion shape in a cross section including the central axis C when the target 2 used in the above configuration is used up to the utilization limit (hereinafter referred to as “lifetime”). However, parts symmetrical with respect to the central axis C are omitted. In FIG. 7, reference numeral 13 denotes an outer shape of the target 2 before sputtering, 14 denotes a sputtered portion, 15
Is the portion left without being sputtered. As shown in FIG. 7, the vicinity of point D (corresponding to the portion indicated by reference numeral 12 in FIG. 6) is significantly eroded, and an eroded surface having a V-shaped cross section is generated.

FIG. 8 shows a plan view of a target 2 having a planar circular shape using the magnetron sputtering apparatus shown in FIG.
FIG. 3 is a diagram showing film thickness distributions at upper, lower, left, and right positions in the plane of the substrate 1 when a film is formed using the substrate 1. In the figure, the abscissa indicates the distance apart from the center of the substrate (that is, the center axis C) along the up, down, left, and right directions, and the ordinate indicates the film at each separation distance when the film thickness at the center of the substrate is 1. It is a relative film thickness. As shown in the figure, there is a variation in film thickness in the circumferential direction,
There is a problem in the uniformity of the in-plane film thickness of the substrate 1. In particular,
Optical thin films such as optical disks are required to have a high film thickness uniformity of ± 2% or less, which is a major technical problem. In addition, since the erosion depth of the target 2 varies depending on the location, the target 2 cannot be used sufficiently,
This also leads to an increase in manufacturing costs.

[0007] The present invention solves these problems described above,
It is an object of the present invention to provide a magnetron sputtering apparatus and a sputtering method that improve the uniformity of film thickness and extend the life of a target.

[0008]

In order to achieve the above object, a first magnetron sputtering apparatus according to the present invention forms a film so that a substrate and a flat plate target are located coaxially with each other. In a magnetron sputtering apparatus opposed to a room, three or more gas inlets for introducing a sputtering gas into the film forming chamber are provided. In order to achieve the above object, a first sputtering method according to the present invention comprises: disposing a substrate and a flat plate target in a film forming chamber so that their centers are coaxially positioned; While introducing a sputtering gas from the above gas inlet into the film forming chamber,
It is characterized in that the setting is performed while changing the flow rate set value of the mass flow controller provided at the gas inlet from the initial use of the target to the end of its life. In order to achieve the above object, a second magnetron sputtering apparatus according to the present invention provides a magnetron sputtering apparatus in which a substrate and a flat plate target are opposed to each other in a film forming chamber such that their respective centers are located coaxially. In the sputtering apparatus, a lower member surrounding the flat plate target and standing upright toward the substrate,
A vacuum exhaust port having an opening through which the entire surface of the substrate is exposed, having a diameter larger than that of the lower member, and being formed coaxially with a lid-like upper member surrounding the substrate-side end of the lower member. It is provided in a film formation chamber. In order to achieve the above object, a second sputtering method according to the present invention is characterized in that the second sputtering method is performed using the second magnetron sputtering apparatus while evacuating from a vacuum exhaust port.

[0009]

In the magnetron sputtering apparatus, the deposition rate depends on various parameters such as the degree of vacuum, the input power, the crystal orientation of the target, the electric field distribution, the magnetic flux density and distribution near the target. Regarding the thickness distribution in the circumferential direction on a circular substrate, the degree of vacuum in the vicinity of the target is particularly large. Therefore, by making the degree of vacuum in the vicinity of the target constant, it is possible to reduce variations in the thickness of the circular substrate in the circumferential direction. Therefore, in the present invention, argon gas for sputtering film formation, or three or more inlet ports for argon gas and reactive gas are installed, respectively,
A configuration (first magnetron sputtering device) for controlling the gas flow rate in each population, or a lower member surrounding the target and standing upright toward the substrate, and an opening exposing the entire surface of the substrate, In addition, the target is formed by providing a vacuum exhaust port formed by coaxially disposing a lid-like upper member surrounding the substrate-side end of the lower member in the film forming chamber (a second magnetron sputtering apparatus). By keeping the degree of vacuum in the vicinity constant, a high film thickness uniformity of, for example, within ± 2% can be obtained from the initial stage of the target to the end of its life. In addition, local erosion of the target can be prevented, and the life of the target can be improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, an outer diameter 20
An example of a magnetron sputtering apparatus using a circular target having a thickness of 3 mm and a thickness of 6 mm will be described below with reference to FIGS. (First Embodiment) First, FIG. 1 shows a sectional view of a film forming chamber in a magnetron sputtering apparatus according to a first embodiment of the present invention. The structure of the cathode portion used here is rotationally symmetric with respect to the central axis C, and a cylindrical chimney 16 is mounted around the substrate 1 and the target 2 so that the film does not easily adhere to the chamber 7. . Further, an argon gas and a reactive gas (oxygen, nitrogen, methane, nitrous oxide, ammonia, hydrogen sulfide, hydrogen gas, etc.) are supplied to the mass flow controller 5 ′ via the gas introduction valves 6 ′ and 6 ″, respectively.
And 5 ". The chimney 16 is also provided at regular intervals along its circumferential direction and at the same height from the target 2 as shown in the top view of FIG.
Eight gas inlets 18 are provided. The other configuration is the same as that of the magnetron sputtering apparatus shown in FIG.

In the above, each gas inlet 18
Gas flow from the mass flow controllers 5 ', 5 "
And the gas flow in the film forming chamber is made uniform. The reason why the gas flow rate is changed for each installation location of the gas inlet 18 is that high vacuum evacuation is usually performed by one vacuum pump 8, so that the degree of vacuum at each location in the vicinity of the target depends on the erosion shape of the target 2. This is because they are slightly different. Further, since the degree of vacuum at each location differs depending on the mounting position of the pump 8 and the like, it is necessary to adjust the flow rate balance to correct the degree of vacuum. The flow rate set values of the mass flow controllers 5 'and 5 "are changed from the initial use of the target 2 to the end of its life.
The erosion depth / shape is substantially proportional to the integrated power, and the target life is reached when the integrated power exceeds a certain value. Therefore, by changing the flow rate set value of each mass flow controller 5 ′, 5 ″ according to the integrated power, the substrate 1
Can be minimized in the circumferential direction. In addition, the life of the target 2 can be confirmed visually, and while the erosion state of the target 2 is visually observed,
The flow rate set values of the mass flow controllers 5 ′ and 5 ″ may be changed in accordance with this. In an example of the gas flow rate adjustment, the erosion state of the target 2 at the gas inlet 18 at the position shown in FIG. The mass flow controller connected to each of the mass flow controllers is changed in accordance with the value of the target 2. In addition, the gas flow rate is increased at the gas inlet having a large gas flow rate with the decrease in the target 2, so that the gas flow rate is increased.
On the other hand, the flow rate set values of the respective mass flow controllers are changed so that the gas flow rate becomes smaller at the gas inlet having a smaller gas flow rate. Thereby, the erosion of the target 2 can be made uniform, the life of the target can be extended, and the film thickness distribution on the substrate can be made uniform.

Using the above magnetron sputtering apparatus, the target 2 was made of zinc sulfide (ZnS).
The argon gas and the reactive gas were introduced by adjusting the gas flow rate from each gas inlet 18 as shown in FIG. At that time, as the target 2 decreases, the gas flow rate is reduced at the gas introduction port whose gas flow rate is less than 2.0, and the gas flow rate is increased at the gas introduction port whose gas flow rate exceeds 2.0. Further, in the gas inlet having a gas flow rate of 2.0, the flow rate set value of each mass flow controller was changed so as to maintain the gas flow rate as it was. The deposition conditions are
The target 2 was used at the beginning of use, and the gas pressure in the film formation chamber was 5 mTorr and the input power was 1 KW.

[0013]

[Table 1]

After the film formation, the in-plane film thickness distribution of the substrate 1 was measured according to FIG. The results are shown in FIG. 3. As shown in FIG. 8, the variation in the circumferential direction was significantly reduced as compared with FIG. 8 in which a film was formed using a conventional magnetron sputtering apparatus.

Further, using a conventional magnetron sputtering apparatus, a target 2 having a limited use limit is mounted, and the same film forming conditions as those described above (gas pressure 5 mTorr, input power 1
KW). FIG. 4 shows the in-plane film thickness distribution of the substrate 1, and the variation of the film thickness in the circumferential direction of the substrate 1 is increasing. Therefore, the target 2 having the usage limit was attached to the magnetron sputtering apparatus of the present embodiment, and the film was formed by adjusting the gas flow rate as shown in Table 1. The film forming conditions are the same. As a result, a film thickness distribution having no variation as shown in FIG. 3 could be obtained. This indicates that the target 2 can be effectively used by adjusting the gas flow rate.

As described above, by mounting the gas inlet 18 and the mass flow controllers 5 'and 5 "at a plurality of locations (three or more locations) in the film forming chamber, variations in the film thickness in the circumferential direction of the substrate occur. Can be modified by changing the balance of the degree of vacuum, so that the degree of freedom is large.

In the above, various changes can be made to the gas inlet 18. For example, the position of the gas inlet 18 in the chimney 16 is not limited, and may be on the side closer to the substrate 1 or on the side closer to the target 2. Further, the gas inlet 18 can be provided in the earth shield 17. Further, the gas inlet 18 may be configured such that a tube connected to the mass flow controllers 5 ′ and 5 ″ may be directly introduced instead of a configuration in which a hole is formed in the chimney 16. There is no problem if there are three or more places, not limited to the three places.

(Second Embodiment) As shown in FIG. 5, a magnetron sputtering apparatus according to a second embodiment includes a lower member 20 surrounding the periphery of a target 2 and erected in the direction of the substrate 1; An upper member having an opening exposing the entire surface of the lower member 20 and having a diameter larger than that of the lower member 20 and surrounding the substrate-side end of the lower member 20 (here, the chimney 16 is substituted).
Are arranged coaxially, and a vacuum exhaust port 19 is formed at an overlapping portion of the two members 16 and 20. The gas is evacuated uniformly by the vacuum exhaust port 19, and uniform and stable film formation is performed. The gas inlet 18 is provided in the lower member 20, and the valves 6 ', 6 "and the mass flow controllers 5', 5" are connected to the lower member 20.

The magnetron sputtering apparatus of this embodiment is effective when the gas pressure in the film forming chamber is high. For example, the vacuum exhaust port 19 is provided in the conventional magnetron sputtering apparatus shown in FIG. 6 and the gas pressure is 30 mTorr.
When the film was formed at a high value of r, a film thickness distribution without variation was obtained as in FIG. When the same experiment was performed by changing the interval between the two members 16 and 20 forming the evacuation port 19, a good film thickness distribution was obtained when the interval was in the range of 0.5 to 10 mm. From this, it can be said that the distance between the upper and lower members is optimally in the range of 0.5 to 10 mm. A similar experiment was conducted by changing the length of the overlapped portion between the two members 16 and 20 (vertical direction in the drawing), but no particular effect on the film thickness distribution was observed.

As described above, the magnetron sputtering apparatuses according to the first and second embodiments according to the present invention have been described. In the magnetron sputtering technique, main dependent parameters differ depending on the degree of vacuum for film formation. Therefore, the magnetron sputtering apparatus according to the first or second embodiment can be selected according to the film forming conditions. However, if the uniform gas introduction by the magnetron sputtering apparatus of the first embodiment and the uniform vacuum exhaustion by the magnetron sputtering apparatus of the second embodiment are used together, the film thickness uniformity can be improved as compared with the case where each is used alone. It will be even better. Specifically, the thickness distribution in the circumferential direction of the substrate can be suppressed to ± 2% variation by using the magnetron sputtering apparatus of the first embodiment. By combining with uniform vacuum evacuation by the ring device, it is possible to reduce the variation of the film thickness distribution to 1.5% or less.

Further, the present invention is not limited to the above embodiment, and various modifications are possible. For example, the introduced gas is not a mixed system of an argon gas and a reactive gas, but may be an argon gas alone. The discharge method may be a DC magnetron discharge in addition to the high-frequency magnetron discharge.

[0022]

As described above, according to the present invention,
Even when the target is used from the initial use to the use limit, a uniform thin film can be formed on the substrate in the circumferential direction. In addition, the use efficiency of expensive targets is increased, and waste is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a magnetron sputtering apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of a gas introduction method according to the first embodiment.

FIG. 3 is a diagram showing a film thickness distribution according to the first embodiment.

FIG. 4 is a diagram showing a film thickness distribution at the time of a target use limit in the first embodiment.

FIG. 5 is a view showing a second embodiment of the magnetron sputtering apparatus of the present invention.

FIG. 6 is a sectional view showing a configuration of a conventional magnetron sputtering apparatus.

FIG. 7 is a diagram showing an eroded surface of a conventional magnetron sputtering apparatus when a target has a limited use.

FIG. 8 is a diagram showing a conventional film thickness distribution at the initial stage of using a target.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Target 5, 5 ', 5 "mass flow controller 16 Chimney (upper member) 17 Earth shield 18 Gas introduction port 19 Vacuum exhaust port 20 Lower member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Suemitsu 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 4K029 BA51 DA06 DC05 DC35 DC39 EA04 EA09 5F103 AA08 BB06 BB58 RR06 RR08

Claims (8)

[Claims] In a magnetron sputtering apparatus in which a substrate and a flat target are opposed to each other in a film forming chamber such that their centers are located coaxially, a gas inlet for introducing a sputtering gas into the film forming chamber. A magnetron sputtering apparatus, wherein three or more are mounted. 2. The magnetron sputtering apparatus according to claim 1, wherein a mass flow controller for controlling an amount of sputter gas introduced is mounted at a base of each gas inlet. 3. The magnetron sputtering apparatus according to claim 1, wherein a mass flow controller for an argon gas or an argon gas and a reactive gas is mounted at a base of each gas inlet. 4. A substrate and a flat plate target are opposed to each other in a film forming chamber such that their centers are located coaxially.
Sputter gas is introduced into the deposition chamber from three or more gas inlets, and sputtering is performed while changing the flow rate set value of the mass flow controller provided in the gas inlet from the initial use of the target to the end of its life. Sputtering method. 5. A substrate and a flat plate target are opposed to each other in a film forming chamber such that their centers are located coaxially.
The sputtering gas is introduced into the film forming chamber from three or more gas inlets, and the flow rate set value of the mass flow controller provided in the gas inlet is changed from the initial use of the target to the life thereof based on the integrated power. A sputtering method characterized by the above-mentioned. 6. In a magnetron sputtering apparatus in which a substrate and a flat plate target are opposed to each other in a film forming chamber such that their centers are located coaxially, the magnet surrounds the periphery of the flat plate target and stands upright toward the substrate. A vacuum exhaust port formed by coaxially disposing a lower member and an upper member having an opening through which the entire surface of the substrate is exposed, having a diameter larger than that of the lower member, and surrounding an end of the lower member on the substrate side; A magnetron sputtering apparatus comprising: 7. The distance between the upper member and the lower member is 0.5 to 0.5.
7. The magnetron sputtering apparatus according to claim 6, wherein the thickness is 10 mm. 8. A sputtering method using the magnetron sputtering apparatus according to claim 6, wherein the sputtering is performed while evacuating from a vacuum exhaust port.