JPH10259478A - Sputtering apparatus, sputtering method and its sputtering target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the adjustment of the film thickness distribution of thin films, to enable the formation of the films at a uniform film thickness to a large area at a high deposition rate, to keep a sputtering rate constant and to improve the use efficiency of targets by completely prohibiting the change of the erosion regions of these targets with time. SOLUTION: This apparatus has a pair of the targets of a concentric circle shape consisting of the outer target T2 having a sputtering surface on its inside surface and the inner target T1 having the sputtering surface on its outside surface, means 151 for generating radial magnetic fields from the inner target T1 toward the outer target T2 and a substrate holding means 41 arranging alongside a pair of the targets. The substrate 40 arranged alongside a pair of the targets is subjected to deposition by generating the radial magnetic fields from the inner target toward the outer target of a pair of the targets of the concentric circule shape consisting of the outer target T2 having the sputtering surface on its inside surface and the inner target T1 having the sputtering surface on its outside surface, introducing a sputtering gas therein and impressing a negative voltage on the targets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus, a sputtering method, and a sputtering target thereof.
More specifically, in a facing target type sputtering apparatus in which a pair of targets face each other at a predetermined interval and a thin film is formed on a substrate arranged on one side and one side thereof, a film formation rate formed on the substrate The present invention relates to a facing target type sputtering apparatus in which the sputtering speed is constant at a high speed and the film thickness is uniform, and the use efficiency of a target is improved.

[0002]

2. Description of the Related Art A conventional facing target type sputtering apparatus is described in "Applied Physics", Vol. 48 (1979) No. 6, p.
As shown in FIG. 559, as shown in FIG. 7, a pair of targets tl and t2 serving as cathodes are provided so that their sputtering surfaces face each other with a space therebetween, and a magnetic field H in a direction perpendicular to the sputtering surfaces is generated. Means h1 and h2 for forming a thin film on the substrate 5 attached to the holder 6 disposed on the side of the space between the targets. is there. That is, in FIG. 7, if a magnetic field H of 300 to 500 Oe is generated in a direction perpendicular to the sputtering surfaces t1s, t2s, the sputtering surfaces t1s, t2
High-energy electrons emitted from s can be confined. Therefore, since the large number of electrons do not reach the substrate 5, an electric field for converging the ions is not formed, and the ionization of the sputter gas is promoted to increase the sputtering speed. Further, since there is almost no electron collision with the substrate 5, the substrate temperature does not rise so much.

[0003]

However, when sputtering is performed with the above-described opposed target device having a rectangular target, a phenomenon is observed in which the erosion region of the target is concentrated at the center of the target as the applied power increases. In particular, such a phenomenon is remarkable when the target is a non-magnetic material. Such concentration of the erosion region not only adversely affects the film thickness distribution but also causes a spark when a large power is applied in order to increase the speed of sputtering, which is not preferable. In addition, the erosion at the center of the target results in the target life being defined, and the target utilization efficiency is not always sufficient. In addition, in the method of devising the shield cover of the target, although the concentration of discharge in the central portion is prevented, effective sputtering cannot be performed in the peripheral portion, and the distribution of film thickness, the use efficiency of the target, etc. Is not completely solved in terms of In addition, if sputtering is continued for a long time, the target surface shape changes with the progress of erosion, and the magnetic field distribution changes, which causes a problem that the discharge intensity changes and the film thickness distribution deteriorates. Furthermore, in order to cope with a large-area substrate, measures have been taken to improve the film thickness distribution in the longitudinal direction by increasing the length of the target in the longitudinal direction with respect to the effective width of the substrate. Although the method in which the substrate passes through the side surface of the space S between them was adopted,
This method was not always an effective method because of the drawbacks such as a decrease in the effective utilization rate of the target and the film formation rate and an increase in the size of the apparatus.

Therefore, the present invention solves the above-mentioned problems in the conventional opposed target sputtering apparatus, and completely prevents the erosion region of the target from changing over time, thereby making it easy to adjust the film thickness distribution of the thin film. It is another object of the present invention to provide a facing target type sputtering apparatus capable of forming a uniform film with a large film thickness at a high film forming rate, keeping the sputtering rate constant, and improving the use efficiency of the target.

[0005]

In order to solve the above-mentioned problems, the present invention provides a pair of targets arranged so that sputtering surfaces face each other, and a direction perpendicular to the sputtering surface provided on the back surface of the targets. And a magnetic field generating means for generating a magnetic field, a facing target type sputtering apparatus for forming a film on a substrate disposed so as to face the space on the side of the sputtering surface, wherein the pair of targets is Consisting of an outer target having a sputtered surface on the inner surface and a concentric target of an inner target having a sputtered surface on the outer surface, wherein the magnetic field generating means has means for radially generating from the inner target to the outer target. It is characterized by. Further, in the facing target type sputtering apparatus of the present invention, the pair of targets may include:
It is characterized in that it has a concentric cylindrical shape at a predetermined interval. Further, the opposed target type sputtering apparatus of the present invention is characterized in that the pair of targets have a concentric oval shape separated by a predetermined distance. Further, the opposed target type sputtering apparatus of the present invention is characterized in that a plurality of sets of the pair of targets are arranged.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the configuration of the present invention described above,
A set of targets has a concentric cylindrical shape or an oval shape facing each other at a predetermined interval, and the sputtering surface is an inner surface of the outer target and an outer surface of the inner target, and the magnetic field generation is radially generated from the inner target to the outer target. By providing a means for generating, the condition that the electric field and the magnetic field are parallel in any region of the target center becomes the same, it is possible to generate the opposed discharge in a closed loop, and avoid the central part of the discharge And spatters can be effectively generated. In addition, by making the target shape an oval shape and optimizing the length in the long side and the short side direction, it is possible to form a thin film uniformly on a large area substrate that passes through the target side. Become. Further, by arranging a plurality of sets of the targets, the film forming speed can be improved. Therefore, the film thickness distribution on a large-area substrate is more uniform than before,
And, by reducing the change in distribution over time,
The distribution of the film thickness can be kept uniform. In addition, large power can be applied, and by arranging a plurality of sets, the sputtering speed is increased, and the use efficiency of the target can be improved.

Next, the specific contents of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a facing target type sputtering apparatus according to the present invention, and FIGS. 2 and 3 are front views of the target portion. In FIG. 1, reference numeral 10 denotes a vacuum chamber, 2
Reference numeral 0 denotes an exhaust system including a vacuum pump for exhausting the chamber 10, and reference numeral 30 denotes a gas introduction system. In the vacuum chamber 10, as shown, the chamber 10, the insulating member 1
Target holders 15 and 16 are provided, which are fixed via 1, 12, 13 and 14. A pair of cylindrical targets T1s and T2s are disposed on the holders 15 and 16 so as to face each other in parallel with a space therebetween. I have. Behind these targets T1 and T2, cylindrical permanent magnets 151 and 161 which are magnetic field generating means are arranged to face each other. Cooling water circulates through the cooling pipes 154 and 164 between the targets T1 and T2 and the target holders 15 and 16 corresponding to the targets T1 and T2 and the permanent magnets 15 and 16.
1, 161 are cooled. Magnet 15
Numerals 1 and 161 are provided so that the N pole and the S pole face each other with respect to the targets T1 and T2. In order to further increase the magnetic flux density in the space between the pair of cylindrical targets T1 and T2, a ferromagnetic material such as permalloy or soft iron is used. A closed loop is formed by the permanent magnets 151 and 161 in the core 17 formed by.
Reference numerals 18 and 19 denote shield covers used as insulating plates for the insulating members 11, 12, 13, 14 and the target holders 15, 16, and also function as anodes.
Further, the substrate holding means 41 for holding the long substrate 40 on which the thin film is formed is moved by the substrate transfer system 50 to the target surface T1.
It is possible to reciprocate in the direction shown in the drawing while being held in a direction perpendicular to s and T2s, so that the substrate 40 can also move in a direction perpendicular to the sputtering surfaces T1s and T2s. Note that a heating means 42 capable of adjusting the temperature from the back surface of the substrate 40 is provided.

On the other hand, a power supply means 60 composed of a DC power supply for supplying sputtering power has the plus side connected to the ground and the minus side connected to the targets T1 and T2. Note that the substrate 40 is used to protect the substrate 40 during pre-sputtering.
A shutter (not shown) is provided between the target and the targets T1 and T2. By the way, as mentioned above,
Behind the targets T1 and T2, a magnetic field generating means composed of a permanent magnet and a core forming a closed loop is provided, and the magnetic flux traverses the surface of the target T1 vertically from the magnet at the center and is further installed at the outer periphery through the space. Perpendicularly crosses the surface of the target T2 and reaches the outer peripheral magnet. The magnetic flux traversing the outer magnet passes through the inside of the core made of ferromagnetic material and reaches the inner magnet to form a closed loop. By forming a closed loop in this manner, a magnetic field crossing the surfaces of the targets T1 and T2 perpendicularly can be formed. Further, by making the targets T1 and T2 cylindrical or oval, a similar magnetic field can be formed at any position of the target.

Therefore, when a gas such as Ar is introduced and DC power is applied, a vertical electric field is formed on the surfaces of the targets T1 and T2. When the magnetic field and the electric field are formed in parallel in this manner, the electrons rotate so as to surround the magnetic field, collide with gas molecules, and are ionized to generate plasma. Target T1, T
Since a negative voltage is applied to DC power supply 2 from the DC power supply, ionized gas molecules are attracted while accelerating to targets T1 and T2, collide with the target and repel target material, thereby causing opposing sputtering. At this time, as described above, the targets T1 and T2 are cylindrical, and the electric field and the magnetic field are formed perpendicularly and radially to the surfaces of the targets T1 and T2. Counter sputtering occurs in the entire area of the cylindrical target without performing the above, and the effective use efficiency of the target can be improved. In the conventional counter sputtering, a region where the electric field and the magnetic field are almost parallel is formed at the center of the target, and the erosion region is concentrated. When a large amount of electric power is applied, abnormal discharge occurs due to power concentration. With the increase in the area of the plasma and the increase in the efficiency of plasma confinement, it was possible to apply a large amount of power and to shorten the distance between the target and the substrate, thereby increasing the deposition rate. Further, even in a low vacuum region where the discharge cannot be maintained by the magnetron discharge, the sputtering can be performed by increasing the plasma confinement efficiency, and a high quality film with less impurities such as sputter gas can be formed. Since the targets T1 and T2 have different sputtered areas, the thickness of the inner target T1 having a small area is preferably larger than T2 in order to make the target life the same.

Next, uniformity of the film thickness distribution in the longitudinal direction can be maintained by the following method. In general, when the substrate 40 is fed as shown in the figure during sputtering, the film thickness in the transport direction can be made uniform, but the peripheral portion becomes thin in the direction perpendicular to the transport direction. Therefore, the cylindrical targets T1 and T2 are formed in an oval shape to optimize the size in the substrate transport direction and the vertical direction with respect to the substrate transport, or by arranging a plurality of cylindrical targets more in the peripheral portion than in the central portion of the substrate to achieve uniformity. A thin film can be obtained over a large area. In addition,
According to the present invention, as described above, it is possible to form a film with a short distance between the target and the substrate by increasing the plasma confinement efficiency, so that the composition ratio of the film adhesion can be reduced from the erosion near the substrate in any minute area of the substrate. It is possible to increase the former of the composition ratio of the sputtered particles to be sputtered and the sputtered particles to fly from the erosion far away. Therefore, compared to the conventional method, the difference in the sputtering conditions and the emission angle distribution of various targets makes it possible to alleviate the uniformity of the film thickness distribution over a wide area, and to achieve the optimization.

[0011]

Embodiments of the present invention will be described below. [Embodiment 1] In Embodiment 1, FIGS.
The film formation was performed using the facing target sputtering apparatus of the present invention shown in FIG. First, the substrate 40 has a thickness of 1.1 mm and a length of 300 m.
A blue plate glass substrate having a size of mx 300 mm was used, and 99.99% as a target material was used for the targets T1 and T2.
The outer target T2 is 320 mm in thickness and 6 mm in thickness, with copper (Cu) having a purity of 0.1 mm and a long direction of the outer target T <b> 2 arranged so that the long direction of the oval shape is oriented at right angles to the transport direction of the substrate. A T2 target having a thickness of 12 mm was used. The height of each of the T1 and T2 cylindrical targets was 100 mm, and the distance between the sputter surfaces of the inner target T1 and the outer target T2 was 60 m.
m. At this time, the intensity of the magnetic field from the T1 sputtering surface to the direction substantially perpendicular to the T2 sputtering surface is 400 Oe.
Met.

The main conditions for sputtering are Ar
The gas pressure was set to 3 × 10 ⁻³ Torr and the distance from the target end to the substrate was set to 30 mm. (If the distance from the target end to the substrate surface is shorter than 10 mm, plasma damage due to heat, electrons, ions, etc. cannot be ignored. On the other hand, if the distance exceeds 60 mm, the film adheres to the wall surface other than the substrate, the transport drive system, etc., which causes a trouble in the transport system apparatus, and causes the generation of contamination and particles. From 60m
The range of m is preferred. ) In addition, the substrate transfer speed is 1
A direct current electric field of 8 kW was applied to T1 and T2 as the power for sputtering, at 50 mm / min. A thin film made of copper was formed by sputtering on a glass substrate as described above. The thickness of the copper film formed under these conditions was about 1 μm,
When the film thickness distribution in the m □ substrate was measured, as shown in FIG. 4, good results were obtained within an error of ± 10% over the entire region of the substrate.

(Comparative Example 1) As a comparison with Example 1, a similar film-forming experiment was performed using a conventional opposed target sputtering apparatus. A rectangular target having a thickness of 6 mm and a size of 320 mm × 100 mm made of copper (Cu) having a purity of 99.99% is used as a target material for the opposing targets t1 and t2, and the longitudinal direction of the target is perpendicular to the substrate transfer direction. So that the substrate passes through the long surface side. The distance between the targets was 100 mm, and the intensity of the magnetic field from the t1 sputtering surface to the direction substantially perpendicular to the t2 sputtering surface at that time was 400 Oe as in the first embodiment.
And The main conditions of the sputtering were as follows: the Ar gas pressure was 3 × 10 ⁻³ Torr, the distance from the target end to the substrate was 30 mm, the substrate transfer speed was 150 mm / min, and sputtering was applied to T1 and T2. An 8 kW DC electric field was applied as electric power. As described above, a thin film made of copper was sputter-deposited on a glass substrate by a conventional method.
The thickness was about 1 μm at the center of the mm □ substrate, and the film thickness distribution within the 300 mm □ substrate was measured, as shown in FIG.
The thickness distribution region of 10% was about 150 mm, which is about half of the substrate width of 300 mm.

[Embodiment 2] In Embodiment 2, 1.1
A flat plate film LC2040 made by Sanyo Chemical Co., Ltd. is spin-coated on a 300 mm square glass substrate with a thickness of 1 μm, and post-baked. The AlSiCu alloy film was formed using the conventional facing target sputtering apparatus and the facing target sputtering apparatus of the present invention with the distance changed to 30 mm from the target end to the substrate in the same manner as in the above example. At that time, a temp plate made by Wahl was attached to the back side of the substrate, and the temperature rise of the substrate was measured. As a result, when a film is formed by the opposed target sputtering apparatus of the present invention, the substrate temperature from the first to the 100th is stable in the range of 93 ° C. to 121 ° C.,
No abnormalities were observed on the film surface.
By the 00th sheet, the temperature increased from 115 ° C to 171 ° C and tended to increase as the number of sheets increased. Further, in the 90th and subsequent substrates, wrinkles appearing as thermal damage of the planarizing film LC2040 occurred on the film surface.

Example 3 In Example 3, a film was formed in the same manner as in Example 1 above, except that a sintered body of ITO (filling rate: 95%) as a transparent conductive film material was used for the targets T1 and T2. An experiment was performed. As main sputtering conditions, 1.5% oxygen gas was mixed with Ar gas, the sputtering pressure was set to 3 × 10 ⁻³ Torr, and DC power of 1 kW was applied to T1 and T2 to perform sputtering. At that time, a micro arc monitor manufactured by Landmark Technology Co., Ltd. was installed and the number of arc discharges was measured. As a result, the number of arcs in the case of continuous film formation for 10 hours was 16 times. This is T1,
It is considered that since the erosion of T2 was uniform, the magnetic flux was not concentrated at the center of the target and a uniform discharge was maintained, so that a stable sputtering with a very small number of arc discharges could be performed.

[Embodiment 4] In Embodiment 4, the targets T1 and T2 described in the above embodiments and the targets t1 and t2 used in the comparative example are used as shown in FIGS. It was used until just one hole became clear), the weight of each was measured, and the value of utilization efficiency = (weight before use−weight after use) / weight before use was measured. As a result, it was found that the target utilization efficiency of the target according to the present invention was about 45%, while the utilization efficiency of the target by the conventional facing sputtering was about 20%.

[0017]

According to the above-mentioned structure, the opposed target type sputtering apparatus of the present invention can easily adjust the film thickness distribution of a thin film, can form a film at a high speed at a high speed, and can form a uniform film over a large area. And the use efficiency of the target can be improved. Further, the facing target type sputtering apparatus of the present invention incorporates the advantages of the conventional facing sputtering, and in addition to being able to perform high-speed and low-temperature sputtering, it is also possible to efficiently perform sputtering on a peripheral portion that was impossible with the conventional sputtering. Sputtering with higher target utilization efficiency can be performed at higher speed. Further, according to the opposed target type sputtering apparatus of the present invention, there is no concentration of magnetic flux at the center of the target, stable sputtering with little arc discharge can be performed for a long time, and mass production is facilitated. Further, according to the facing target type sputtering apparatus of the present invention, a portion having a good film thickness distribution can be set in a wide range, and a change with time can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a facing sputtering apparatus according to the present invention.

FIG. 2 is a front view of a concentric cathode.

FIG. 3 is a front view of an oval-shaped cathode.

FIG. 4 is a film thickness distribution comparison.

FIG. 5 is a target erosion diagram of the present invention.

FIG. 6 is a target erosion diagram of a conventional system.

FIG. 7 is a cross-sectional view of a conventional facing sputtering apparatus.

[Explanation of symbols]

 10: Vacuum chamber 11, 12, 13, 14 ... Insulating member 15, 16: Target holder 17: Core 18, 19: Shield plate 20: Exhaust system 30: Gas introduction system 40: Substrate 41: Substrate holding means 42: Heating means 50: substrate transport system 60: power supply means 151, 161: magnetic field generation means 152, 164: cooling pipe T1, T2: target

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryuji Bilo 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hidehiro Kanazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Non Corporation

Claims (9)

[Claims] A means for generating a radial magnetic field from the inner target toward the outer target; a pair of concentric targets each comprising an outer target having a sputter surface on an inner surface, an inner target having a sputter surface on an outer surface; And a substrate holding means disposed laterally on the pair of targets. 2. The sputtering apparatus according to claim 1, wherein said pair of targets have a concentric cylindrical shape or an oval shape. 3. The sputtering apparatus according to claim 1, wherein the sputtering apparatus includes a plurality of the pair of targets. 4. The sputtering apparatus according to claim 1, further comprising a substrate transfer system for moving said substrate holding means in a direction perpendicular to said sputtering surface. 5. The sputtering apparatus according to claim 1, wherein said magnetic field generating means has a magnet and a core provided inside the inside target and outside the outside target, respectively. 6. A radial magnetic field is generated from an inner target to an outer target between a pair of concentric targets including an outer target having a sputter surface on an inner surface and an inner target having a sputter surface on an outer surface. A sputtering gas is introduced, a negative voltage is applied to the target, and a film is formed on a substrate disposed laterally on the pair of targets. 7. The sputtering method according to claim 6, wherein the substrate is moved in a direction perpendicular to the sputtering surface during the film formation. 8. A sputter target comprising: an outer target having a sputter surface on an inner surface; and an inner target having a sputter surface on an outer surface. 9. The sputter target according to claim 8, wherein said target has a concentric cylindrical shape or an oval shape.