JPH09316633A - Sputtering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable effective and uniform sputtering film formation without making a vacuum tank a large scale. SOLUTION: A vacuum tank is constituted of a cylindrical bell jar main body 3, a cover 4 and a base plate. A drum-shaped substrate holder 16 is freely ratatably housed in the vacuum tank. A cylindrical target houses 10 are protruded at four places of the outer circumference 4 of the main body 3. A target structural body 14 is set to the inside of the target house 10. The target structural body 14 has a semicylindrical target material 15 on the side opposite to a target 18. By glow discharge generated in the region between the target material 15 and substrate 18, in the meanwhile the substrate holder 16 is rotated for one time, sputtering film formation is executed at the four places.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus capable of efficiently forming a high quality thin film.

[0002]

2. Description of the Related Art Sputtering is used to form a thin film such as an antireflection film or a transparent conductive film on a substrate.
Sputtering involves introducing a discharge gas into a vacuum chamber, accelerating cations generated by glow discharge to collide with a target, and depositing a thin film by depositing atoms knocked out of the target with the collision energy onto the substrate surface. Form.
In order to generate a stable glow discharge, an inert gas such as argon gas is introduced as a discharge gas up to an appropriate gas pressure in a high vacuum vacuum chamber. Further, in the case of chemically reactive sputtering, in addition to argon gas, a reactive gas such as oxygen gas or nitrogen gas is introduced according to the type of chemical reaction. Sputtering has an advantage over the resistance heating evaporation method and electron beam heating evaporation method in that it has a dense film structure, excellent physicochemical properties, and a highly durable thin film. There is a drawback of this.

In order to solve the above-mentioned problems, a sputtering apparatus disclosed in Japanese Patent Application Laid-Open No. 7-70748 by the present applicant is known. In this apparatus, the inner volume in the vacuum chamber is made as small as possible so that the exhaust step, which is a pre-step for performing sputtering film formation, can be performed in a short time. In addition, a plurality of substrates to which thin films are to be deposited are held by a drum-shaped substrate holder, and the substrate holder is appropriately rotated to form a film on a plurality of substrates after one evacuation process. It is possible to perform the sputtering, and if necessary, it is also possible to perform the sputtering using a different target material after one exhaust step.

In the apparatus described in the above publication, a plate-like material is used as the target material. Therefore, when an attempt is made to increase the surface area of the target material for efficient sputtering film formation, the target holding mechanism including the electrodes becomes large. It is easy to upsize the vacuum chamber. In this respect, if the target material is made cylindrical and the electrode is housed in the hollow portion, the space efficiency can be improved while increasing the surface area of the target material, and as a result, the internal volume of the vacuum chamber can be increased. Therefore, the exhaust time can be shortened.

[0005]

An apparatus for using a target material in a cylindrical shape is disclosed in, for example, JP-A-59-179782.
In this device, a cylindrical target material is placed in the center of a vacuum chamber, and a substrate is fixedly placed so as to surround the target material, and glow discharge is generated over the entire circumference of the target material to form a film. It has a structure. However, it is very difficult to maintain a uniform and stable glow discharge over the entire circumference of the target material,
Local unevenness is likely to occur when sputtering is performed, and a uniform thin film cannot be formed on a plurality of substrates. Further, although a magnetic field is used together to improve the sputtering rate, it is still difficult to form a uniform thin film because a constant magnetic field is applied to the target material.

The present invention has been made in consideration of the above circumstances, and the target material can be accommodated in a plurality of places without enlarging the vacuum chamber, and a uniform thin film can be efficiently formed. It is an object of the present invention to provide a sputtering device thus configured.

[0007]

In order to achieve the above object, the present invention provides a drum-shaped substrate holder for holding a plurality of substrates on which thin films are to be deposited, in a cylindrical vacuum chamber. A cylindrical target house is projected at a plurality of positions on the cylindrical outer wall of the vacuum chamber, and a target structure is installed in this target house. The target structure has a cylindrical target material, and sputtering film formation is performed on the substrate that has moved to a position facing the cylindrical target material by the rotation of the substrate holder.

Since the glow discharge is mainly performed in a region where the substrate and the cylindrical target material face each other, it is cost effective to use an inexpensive material instead of the target material on the side not facing the substrate. . However, in this case, even the non-target material may be affected by the glow discharge, and particles unnecessary for the original thin film formation may be scattered. When such particles adhere to the substrate, the quality of the thin film deteriorates.Therefore, in order to prevent such particles and atoms from wrapping around to the substrate, a shielding plate may be provided near the boundary between the target house and the vacuum chamber or the target house A trap means may be provided on the inner wall.

When the sputtering rate is improved by using the magnetic field action together, it is preferable to apply the magnetic field to the target material on average, rather than to locally apply a constant magnetic field to the target material. Therefore, a rotating shaft is provided along the axial direction inside the support cylinder that holds the target material, and the disk-shaped magnet is tilted and fixed with respect to this rotating shaft, and the rotating shaft rotates to generate a magnetic field. It is structurally simple and effective to make changes possible.

[0010]

1 and 2 showing a sputtering apparatus to which the present invention is applied, a vacuum chamber 2 includes a bell jar main body 3 having a cylindrical shape, a lid 4 and a base plate 5 that hermetically cover the top and bottom of the bell jar main body 3, respectively. And sputtering is performed in the internal space. Base plate 5
An exhaust hole is formed in the central part of the, and the variable rotation speed type molecular turbo pump 6 and the scroll type dry vacuum pump 7 are connected through this exhaust hole. By driving these vacuum pumps, the inside of the vacuum chamber 2 can be made a high vacuum of 10 ⁻⁶ Torr or less.

Semi-cylindrical target houses 10 are provided at four locations on the side surface of the bell jar body 3 so as to project therefrom. A main part of the target house 10 is composed of a door 12 which can be opened and closed by a hinge mechanism 11. A target structure 14 is provided inside each target house 10, and a semi-cylindrical target material 15 is held toward the center of the bell jar body 3. The target material 15 is appropriately selected according to the composition of the thin film to be formed, but here, for convenience, it will be described as a metal material.

A drum-shaped substrate holder 16 is rotatably housed inside the vacuum chamber 2, and can be rotated at a speed of 2 to 20 rpm by a drive mechanism (not shown). A substrate 18 to which a thin film is attached is attached to the peripheral surface of the substrate holder 16. The substrate holder 16 can be taken out of the vacuum chamber 2 by opening the lid 4, and the substrate 18 is attached to and detached from the substrate holder 16. When performing the sputtering, the substrate holder 16
Is used as the positive electrode.

FIG. 3 shows the internal structure of the target house 10. The semi-cylindrical target material 15 is fixed to a hollow support cylinder 20 so as to face the substrate 18. The support cylinder 20 has conductivity and is used as a cathode when performing sputtering. The peripheral surface on the opposite side of the support cylinder 20 is a covering material 2 made of an inexpensive insulating material having high heat resistance.
Covered with 1.

A pair of shield plates 23 are fixed at the boundary between the bell jar body 3 and the target house 10. These shield plates 23 are for preventing atoms that fly out of the coating material 21 from being scattered toward the substrate 18 when sputtering is performed. The length L and the inclination angle θ of the shield plate 23 depend on the type of the target material 15. Or appropriately adjusted according to the discharge voltage at the time of sputtering. Target house 10
A large number of fins 25 are provided on the inner wall of the as a trap means for trapping the atoms that have jumped out from the coating material 21. As such a trap means, a fine wire mesh, a structure having a large surface area such as a material having many irregularities or a porous material is used as the target house 10.
It may be arranged along the inner wall of the. The substrate holder 1
The length L and the angle θ of each shield plate 23 may be changed depending on the rotating direction of the shield 6.

FIG. 4 is a schematic sectional view of the target structure 14. An insulating plate 26 is provided at both ends of the support cylinder 20,
27 is fitted in, and the rotary shaft 28 is supported by these plates 26, 27. As shown in the drawing, the rotating shaft 28 includes a disk-shaped magnet 30, a soft iron plate 31, a magnet 32, a spacer 33, a magnet 34, a soft iron plate 35, and a magnet 3.
6 are sequentially arranged, and these are fixed in a state of being inclined at a constant angle with respect to the rotating shaft 28.

A gear 37 is fixed to the lower end of the rotary shaft 28, and is driven by the motor to drive the rotary shaft 2 through the gear 37.
8 rotates. A hollow pipe is used for the rotary shaft 28, and a drainage hole 28a is opened at the upper end thereof. The space surrounded by the support cylinder 20 and the plates 26, 27 has a watertight structure. Then, the cooling water is supplied from the water supply pipe 38 attached to the plate 27, and the drainage is performed through the rotary shaft 28. Thereby, the target material 15 heated by sputtering can be cooled. The configuration of the target house 10 described above is common to the other three target houses 10, and similarly, the target structures 14 are also common.

In order to form a film by sputtering with the above apparatus, first, the molecular turbo pump 6 and the scroll type dry vacuum pump 7 are operated to bring the inside of the vacuum chamber 2 to a high vacuum.
After that, a discharge gas for causing glow discharge is introduced up to a specified gas pressure from a gas introduction pipe (not shown). An inert gas such as argon gas is used as the discharge gas,
The amount of discharge gas introduced is adjusted so that the specified gas pressure is maintained by a valve provided in the gas introduction pipe.

The motor is driven to rotate the rotary shaft 28,
Further, cooling water is introduced from the water supply pipe 38. The rotation of the rotary shaft 28 causes the magnets 30, 32, 34, 36 to rotate. Since these magnets are inclined and fixed with respect to the rotation shaft 28, the magnetic field alternately moves in the direction perpendicular to FIG. 4 as the magnets rotate. Further, the introduction of the cooling water prevents the target material 15 from reaching a high temperature, and stable glow discharge can be continued.

Next, while rotating the substrate holder 16 slowly, a DC voltage is applied using the substrate holder 16 as an anode and the support cylinder 20 as a cathode. When the voltage is gradually increased, glow discharge occurs between both electrodes and a discharge current flows. When glow discharge occurs between both electrodes, the discharge gas in the discharge space is ionized. The cations generated here are generated by the electric field between the substrate holder 16 and the support cylinder 20 and the magnet 3.
It is accelerated by the superposition effect of the magnetic field of 0, 32, 34, 36, moves toward the support cylinder 20 serving as the cathode, and collides with the surface of the target material 15. Atoms are knocked out from the target material 15 by this collision energy and adhere to the substrate 16 to start forming a thin film.

Most of the cations generated by the glow discharge collide with the surface of the semi-cylindrical target material 15 and contribute to the formation of a thin film, but some cations wrap around the target material 15 to cover the coating material. Collide with 21. For this reason, the atoms forming the coating material 21 may be scattered. The atoms thus scattered have nothing to do with the composition of the thin film to be formed by sputtering. Therefore, when these foreign atoms reach the substrate 18, impurities are mixed into the thin film, which causes deterioration of the quality of the thin film. However, since these foreign atoms are captured by the fins 25 installed on the inner wall of the target house 10 and further blocked by the pair of shielding plates 23, they are not mixed in the thin film.

Incidentally, if the target material 15 is held on the entire circumference of the support cylinder 20, it is possible to avoid mixing of such different kinds of atoms, but a small amount of the target material on the side not facing the substrate 18 is used for sputtering. Using the target material 15 even in such a portion imposes a heavy cost burden. Therefore, it is more advantageous to use the inexpensive covering material 21 as described above, and the fin 2
5 and the shielding plate 23 can prevent foreign atoms from the coating material 21 from being mixed into the thin film.

During the sputtering,
The magnets 30, 32, 34 and 36 rotate together with the rotating shaft 28. Since these magnets are attached so as to be inclined with respect to the rotating shaft 28, the magnetic poles periodically move in the vertical direction within the support cylinder 20. Therefore, the density of magnetic lines of force along the surface of the target material 15 changes as the magnet rotates. Therefore, the magnetic field is averaged over the entire surface of the target material 15, so that the sputtering is performed evenly from the entire surface of the target material 15, the target material 15 is locally consumed, and the glow discharge becomes unstable. In addition, stable sputtering can be performed without causing the film thickness to become locally uneven in the process of forming a thin film. It should be noted that, as compared with the case where the magnet is simply moved up and down, the above-described action can be obtained only by rotating the magnet, which is also advantageous in simplifying the structure.

During the sputtering film formation, the target material 15 and the support cylinder 20 are heated by the collision energy received from the cations, but since cooling water is supplied into the support cylinder 20, they are exposed to extremely high temperatures. The stable glow discharge can be continued without reaching the target. Sputtering is sequentially performed while the substrate 18 passes through the four target houses 10 while the substrate holder 16 rotates once. After sputtering to a predetermined film thickness, the voltage application between the electrodes is cut off to close the exhaust system valve and the discharge gas introduction valve, rotate the substrate holder 16, and supply cooling water. Stop the vacuum chamber 2
The inside is gradually leaked to atmospheric pressure. Then, the lid 4 may be opened and the substrate holder 16 may be taken out.

The present invention has been described above based on the illustrated embodiment. If the target material 15 is a metal, the direct current sputtering can be performed as described above, but the target material is an insulating material. In some cases, sputtering can be performed by applying an AC voltage. Furthermore, the target house 10 and the support cylinder 20
Also, an example in which the shape of the target material 15 is a cylinder or a semi-cylindrical shape has been described, but these may be a polygonal cylindrical shape or a semi-cylindrical shape.
The number of 0s is not limited to four.

It is also possible to perform sputtering using different target materials for each target house installed in a plurality of places. In this case, one rotation of the substrate holder 16 is defined as one cycle, and the rotation of the substrate holder 16 is performed. A voltage may be sequentially applied to the target structures 14 in the target house in accordance with the phase, and thin films of the respective target materials may be stacked in a predetermined order. Furthermore, if the substrate holder 16 is provided with a substrate rotating mechanism capable of reversing the front and back of the substrate 18, it is possible to perform sputtering on the front and back of the substrate 18 in a single vacuuming process. If necessary, a reactive gas such as oxygen may be introduced in addition to the discharge gas to perform the chemical reactive sputtering.

[0026]

According to the apparatus of the present invention, a cylindrical target house is provided at a plurality of locations on a cylindrical outer wall forming a vacuum chamber, and a target structure containing a cylindrical target material is installed therein. Since the substrate moved by the rotation of the substrate holder is sequentially sputtered, there is no need to increase the size of the electrode structure on the target material side. Sputtering can be performed at a location, and a thin film can be efficiently formed in a short time.

When sputtering is performed between the cylindrical target material and the substrate, the target material on the side not facing the substrate hardly contributes to film formation. Therefore, the cost can be reduced by using the semi-cylindrical target material only on the side facing the substrate and using the inexpensive covering material instead of the expensive target material on the opposite side. Even if such a covering material is used, the shielding plate or the trap means is provided at an appropriate location,
Even if foreign particles are scattered from the coating material due to the effect of glow discharge, they do not adhere to the substrate,
It does not impair the quality of the thin film.

Further, since the rotary shaft is provided in the support cylinder and the magnet is fixed in a state of being inclined with respect to the rotary shaft, the magnet is relatively moved in the rotary shaft direction only by rotating the rotary shaft. , It becomes possible to change the magnetic field evenly along the surface of the target material, so that the target material can be used effectively and evenly, and it is very effective in forming a uniform thin film on the substrate. is there.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a sputtering film forming apparatus of the present invention.

FIG. 2 is an external view of a sputtering film forming apparatus of the present invention.

FIG. 3 is a schematic sectional view of a target house.

FIG. 4 is a schematic cross-sectional view of a target structure.

[Explanation of symbols]

 2 vacuum tank 3 bell jar main body 10 target house 14 target structure 15 target material 16 substrate holder 18 substrate 20 support cylinder 21 coating material 23 shielding plate 25 fins 28 rotating shafts 30, 32, 34, 36 magnets

Claims (5)

[Claims] 1. A cylindrical vacuum chamber, a drum-shaped substrate holder rotatably disposed inside the vacuum chamber and holding a plurality of substrates to which thin films are to be adhered, and the substrate holder. It has a target material placed inside the vacuum chamber so as to face the substrate when it moves, and discharges between the substrate and the target material to attach atoms knocked out from the target material to the substrate. In the sputtering apparatus for forming a thin film, a cylindrical target house is formed so as to project at a plurality of positions on the cylindrical outer wall of the vacuum chamber along the rotation direction of the substrate holder, and the space inside the target house is formed. A sputtering apparatus provided with a target structure containing a cylindrical target material. 2. The target structure comprises a support cylinder that serves as one electrode during glow discharge, and a semi-cylindrical target material attached to the peripheral surface of the support cylinder on the side facing the substrate. 2. The sputtering apparatus according to claim 1, further comprising a coating material made of a non-target material attached to a peripheral surface of the support cylinder on a side not facing the substrate. 3. The sputtering apparatus according to claim 2, wherein a shielding plate for shielding particles scattered from the non-target material is provided in the vicinity of the boundary between the target house and the vacuum chamber. 4. The sputtering apparatus according to claim 3, wherein a trap means for trapping particles scattered from the non-target material is installed on the inner wall of the target house. 5. A rotation shaft is provided inside the support cylinder along the axial direction, and a disk-shaped magnet is fixed by inclining with respect to the rotation shaft, and the magnetic field generated by the magnet is changed by rotation of the rotation shaft. The sputtering apparatus according to any one of claims 2 to 4, wherein the sputtering apparatus is adapted to perform.