JP3810132B2 - Sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering apparatus that can efficiently form a high-quality thin film.
[0002]
[Prior art]
Sputtering is used to form a thin film such as an antireflection film or a transparent conductive film on a substrate. Sputtering introduces a discharge gas into the vacuum chamber, accelerates cations generated by glow discharge to collide with the target, and deposits atoms hit from the target with the collision energy on 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 into a vacuum chamber in a high vacuum up to an appropriate gas pressure. In the case of chemical reactive sputtering, in addition to argon gas, a reactive gas such as oxygen gas or nitrogen gas is introduced corresponding to the type of chemical reaction. Sputtering has the advantage that a thin film with a dense film structure, excellent physicochemical properties, and high durability can be obtained compared to resistance heating evaporation and electron beam heating evaporation. There is a difficulty that it takes.
[0003]
In order to solve the above problems, a sputtering apparatus described in Japanese Patent Application Laid-Open No. 7-70748 by the present applicant is known. In this apparatus, by reducing the internal volume in the vacuum chamber as much as possible, the exhaust process, which is a pre-process for performing the sputtering film formation, can be performed in a short time. In addition, a plurality of substrates to be deposited with thin films are held on a drum-shaped substrate holder, and the substrate holder is appropriately rotated to form a film on the plurality of substrates after one evacuation step. It is possible to perform sputtering, and if necessary, sputtering can be performed using a different target material after a single exhaust process.
[0004]
In the apparatus described in the above publication, a plate-like material is used as the target material. Therefore, when the surface area of the target material is increased for efficient sputtering film formation, the target holding mechanism including the electrode is enlarged, and the vacuum chamber Is also easy to enlarge. In this regard, when the target material is made into a cylindrical shape and the electrode is accommodated in the hollow portion, space efficiency can be improved while increasing the surface area of the target material, resulting in an increase in the internal volume of the vacuum chamber. Therefore, the exhaust time can be shortened.
[0005]
[Problems to be solved by the invention]
An apparatus that uses a target material in a cylindrical shape is described in, for example, Japanese Patent Application Laid-Open No. 59-179782. In this apparatus, a cylindrical target material is installed at the center of a vacuum chamber, and a substrate is fixedly disposed so as to surround it. The film is formed by generating glow discharge over the entire circumference of the target material. However, it is very difficult to maintain a uniform and stable glow discharge over the entire circumference of the target material, and local unevenness is likely to occur when sputtering is performed, and a uniform thin film is formed on a plurality of substrates. I can't. Furthermore, although a magnetic field is used in combination for improving the sputtering rate, it is difficult to form a uniform thin film because a constant magnetic field is applied to the target material.
[0006]
The present invention has been made in consideration of the above circumstances, and can accommodate a target material in a plurality of locations without increasing the size of the vacuum chamber, and can efficiently form a uniform thin film. An object is to provide a sputtering apparatus.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a drum-shaped substrate holder for holding a plurality of substrates to be coated with a thin film inside a cylindrical vacuum chamber, and a plurality of locations on the cylindrical outer wall of the vacuum chamber. In addition, a cylindrical target house is projected, and a target structure is installed in the 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.
[0008]
Since glow discharge is performed mainly in a region where the substrate and the cylindrical target material face each other, it is advantageous in terms of cost 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 is affected by the glow discharge, and particles unnecessary for forming the original thin film may be scattered. When these particles adhere to the substrate, the quality of the thin film deteriorates. Therefore, a shield plate is provided near the boundary between the target house and the vacuum chamber so that these particles and atoms do not reach the substrate. Trap means may be provided on the inner wall.
[0009]
When the sputtering rate is improved by using a magnetic field effect in combination, it is preferable to apply a magnetic field to the target material on average rather than to apply a constant magnetic field locally to the target material. Therefore, a rotating shaft is provided along the axial direction inside the support cylinder holding the target material, and a disk-shaped magnet is tilted and fixed with respect to the rotating shaft. It is convenient and effective in structure to be able to give a change.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 showing a sputtering apparatus to which the present invention is applied, a vacuum chamber 2 comprises a cylindrical bell jar main body 3, a lid 4 and a base plate 5 that hermetically cover the upper surface and the bottom surface of the bell jar main body 3, respectively. Sputtering is performed. An exhaust hole is formed in the central portion of the base plate 5, and a variable-speed molecular turbo pump 6 and a scroll-type dry vacuum pump 7 are connected through the exhaust hole. By driving these vacuum pumps, the inside of the vacuum chamber 2 can be set to a high vacuum of 10 ⁻⁶ Torr or less.
[0011]
A semi-cylindrical target house 10 protrudes from four locations on the side surface of the bell jar body 3. The target house 10 is composed of a door 12 whose main part 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 depending on the composition of the thin film to be produced. Here, it is assumed that it is a metal material for convenience.
[0012]
A drum-shaped substrate holder 16 is rotatably accommodated 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 to be deposited is attached to the peripheral surface of the substrate holder 16. By opening the lid 4, the substrate holder 16 can be removed from the vacuum chamber 2, and the substrate 18 is attached to and detached from the substrate holder 16. And when performing sputtering, this substrate holder 16 is used as a positive electrode.
[0013]
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 covered with a covering material 21 made of an inexpensive insulating material with high heat resistance.
[0014]
A pair of shielding plates 23 are fixed to the boundary between the bell jar body 3 and the target house 10. These shielding plates 23 are for preventing atoms jumping out of the covering material 21 from being scattered toward the substrate 18 when sputtering is performed, and the length L and the inclination angle θ are the types of the target material 15. And appropriately adjusted according to the discharge voltage during sputtering. A large number of fins 25 are provided on the inner wall of the target house 10 as trapping means for trapping atoms that have jumped out of the covering material 21. As such trapping means, a structure having a large surface area such as a fine wire mesh, a material having a large number of irregularities, or a porous material may be disposed along the inner wall of the target house 10. . The length L and the angle θ of each shielding plate 23 may be changed with each other according to the rotation direction of the substrate holder 16.
[0015]
FIG. 4 shows a schematic cross-sectional view of the target structure 14. Insulating plates 26 and 27 are fitted into both ends of the support cylinder 20, and the rotating shaft 28 is supported by these plates 26 and 27. As shown in the figure, 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 36, which are sequentially arranged. On the other hand, it is fixed in a state inclined at a certain angle.
[0016]
A gear 37 is fixed to the lower end portion of the rotating shaft 28, and the rotating shaft 28 rotates through the gear 37 by driving the motor. A hollow pipe is used for the rotating shaft 28, and a drain hole 28a is formed at the upper end thereof. The space surrounded by the support cylinder 20 and the plates 26 and 27 has a watertight structure. Then, cooling water is supplied from a water supply pipe 38 attached to the plate 27 and drained through the rotary shaft 28. Thereby, the target material 15 heated by sputtering can be cooled. Note that the configuration of the target house 10 described above is common to the other three target houses 10, and similarly, the target structure 14 is also common.
[0017]
In order to perform sputtering film formation with the above apparatus, first, the molecular turbo pump 6 and the scroll type dry vacuum pump 7 are operated to make the inside of the vacuum chamber 2 into a high vacuum. Thereafter, a discharge gas for generating glow discharge is introduced from a gas introduction tube (not shown) to a prescribed gas pressure. An inert gas such as argon gas is used as the discharge gas, and the amount of the discharge gas introduced is adjusted by a valve provided in the gas introduction tube so that the prescribed gas pressure is maintained.
[0018]
The motor is driven to rotate the rotary shaft 28 and cooling water is introduced from the water supply pipe 38. The magnets 30, 32, 34, and 36 are rotated by the rotation of the rotating shaft 28. Since these magnets are tilted and fixed with respect to the rotating shaft 28, the magnetic field alternately moves in the direction perpendicular to FIG. In addition, the introduction of the cooling water prevents the target material 15 from reaching a high temperature, and a stable glow discharge can be continued.
[0019]
Next, while slowly rotating the substrate holder 16, a DC voltage is applied using the substrate holder 16 as an anode and the support tube 20 as a cathode. As the voltage is gradually increased, glow discharge occurs between the 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 accelerated by the superimposing action of the electric field between the substrate holder 16 and the support cylinder 20 and the magnetic field generated by the magnets 30, 32, 34, and 36 toward the support cylinder 20 serving as a cathode. It moves and collides with the surface of the target material 15. Atoms are knocked out of the target material 15 by this collision energy and adhere to the substrate 16 to start forming a thin film.
[0020]
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 the thin film. However, some cations enter the target material 15 and collide with the coating material 21. To do. For this reason, atoms constituting the covering material 21 may be scattered. The scattered atoms are unrelated to the composition of the thin film to be formed by sputtering. Therefore, when these different kinds of atoms reach the substrate 18, impurities are mixed into the thin film and cause deterioration of the quality of the thin film. However, since these different 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 into the thin film.
[0021]
In addition, if the target material 15 is held around the entire circumference of the support cylinder 20, such a mixture of different kinds of atoms can be avoided. However, since the target material on the side that does not face the substrate 18 is only subjected to sputtering, such a target material is used. The use of the target material 15 for the portion is costly. For this reason, it is advantageous to use the inexpensive covering material 21 as described above, and by using the fins 25 and the shielding plate 23, it is possible to prevent foreign atoms from the covering material 21 from being mixed into the thin film. it can.
[0022]
Further, the magnets 30, 32, 34, and 36 are rotated together with the rotating shaft 28 during the sputtering. Since these magnets are attached 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 the lines of magnetic force along the surface of the target material 15 changes with the rotation of the magnet. For this reason, the magnetic field is averaged over the entire surface of the target material 15, and sputtering is performed on average from the entire surface of the target material 15, so that the target material 15 is locally consumed and the glow discharge becomes unstable. In addition, the film thickness does not become locally uneven in the process of forming a thin film, and stable sputtering can be performed. In addition, compared with what moves a magnet up and down, since said effect | action is acquired only by rotation of a magnet, it is advantageous also in aiming at simplification of a structure.
[0023]
During sputtering film formation, the target material 15 and the support cylinder 20 are heated by the collision energy received from cations. However, since cooling water is supplied into the support cylinder 20, they cannot reach an extremely high temperature. And stable glow discharge can be continued. While the substrate holder 16 rotates once, sputtering is sequentially performed while the substrate 18 passes through the four target houses 10. After sputtering to a predetermined film thickness, the voltage application between both electrodes is cut off, the exhaust system valve and the discharge gas introduction valve are closed, the substrate holder 16 is rotated, and the cooling water is supplied. After stopping, the inside of the vacuum chamber 2 is gradually leaked to the atmospheric pressure. Then, the lid 4 is opened and the substrate holder 16 is taken out.
[0024]
As described above, the present invention has been described based on the illustrated embodiment. However, if the target material 15 is a metal, sputtering by direct current can be performed as described above, but when the target material is an insulating material. Can be sputtered by applying an alternating voltage. Furthermore, although the example which made the shape of the target house 10, the support cylinder 20, and the target material 15 cylindrical or semi-cylindrical shape was demonstrated, these may be a polygonal cylinder shape and a semi-cylinder shape. However, the number is not limited to four.
[0025]
In addition, it is possible to perform sputtering using different target materials for each target house installed at a plurality of locations. In this case, one rotation of the substrate holder 16 is set as one cycle, and the rotation phase of the substrate holder 16 is adjusted. Then, it is only necessary to sequentially apply a voltage to the target structure 14 in the target house and to stack thin films of the respective target materials in a predetermined order. Furthermore, if the substrate holder 16 is provided with a substrate rotation mechanism that can reverse 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 evacuation process. If necessary, a reactive gas such as oxygen may be introduced in addition to the discharge gas to perform chemical reactive sputtering.
[0026]
【The invention's effect】
According to the apparatus of the present invention, a cylindrical target house is provided to project at a plurality of locations on the cylindrical outer wall constituting the vacuum chamber, and a target structure including a cylindrical target material is installed therein, and a substrate holder Sputtering is performed sequentially on the substrate that has been moved by the rotation of the substrate, so that the electrode structure on the target material side is not increased in size, and the sputtering is performed on the same substrate at a plurality of locations in the vacuum chamber. And a thin film can be efficiently formed in a short time.
[0027]
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 the film formation. Therefore, the cost can be reduced by using a semi-cylindrical target material only on the side facing the substrate and using an inexpensive coating material on the opposite side instead of an expensive target material. Even if such a covering material is used, since the shielding plate or the trap means is provided at an appropriate place, even if foreign particles are scattered from the covering material due to the influence of the glow discharge, it is applied to the substrate. There is nothing wrong, and the quality of the thin film is not impaired.
[0028]
Further, since the rotating shaft is provided in the support cylinder and the magnet is fixed in a state inclined with respect to the rotating shaft, the magnet is relatively moved in the rotating shaft direction only by rotating the rotating shaft, and the target material Thus, the magnetic field can be averaged along the surface of the substrate, and the target material can be effectively used without unevenness, and at the same time, it is very effective in forming a uniform thin film on the substrate.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential 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 chamber 3 Bell jar body 10 Target house 14 Target structure 15 Target material 16 Substrate holder 18 Substrate 20 Supporting cylinder 21 Covering material 23 Shielding plate 25 Fin 28 Rotating shaft 30, 32, 34, 36 Magnet

Claims (4)

A cylindrical vacuum chamber, and a drum-shaped substrate holder that is rotatably disposed inside the vacuum chamber and holds a plurality of substrates to which thin films are to be deposited, on the outer peripheral surface. Attached to the substrate are atoms knocked out of the target material of the target structure by performing a discharge between the substrate target and the cylindrical target structure disposed so as to face the outer peripheral surface of the substrate holder. In a sputtering apparatus for forming a thin film,
The target structure is a cylindrical support tube that serves as one electrode when performing the glow discharge, and the semi-cylindrical target material attached to the peripheral surface of the support tube on the side facing the substrate holder And a non-target material attached to the peripheral surface of the support cylinder on the side that does not face the substrate holder, and the target structure includes a plurality of cylindrical outer walls of the vacuum chamber along the rotation direction of the substrate holder. sputtering apparatus characterized by being arranged to place the interior of the plurality of targets house which is projected into a semi-cylindrical shape. Wherein in the vicinity boundary of the target house and the cylindrical portion of the vacuum chamber, the sputtering apparatus according to claim 1, characterized in that a shielding plate for blocking the particles scattered from the non-target material. The sputtering apparatus according to claim 2 , wherein trap means for capturing particles scattered from the non-target material is installed on an inner wall of the target house. A rotating shaft is provided along the axial direction inside the support cylinder, and a disc-shaped magnet is fixed to be inclined with respect to the rotating shaft, and the magnetic field generated by the magnet is changed by rotation of the rotating shaft. The sputtering apparatus according to any one of claims 1 to 3, wherein :

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