Patent Application
20110290638
The present invention relates to a sputter device and a method of manufacturing a magnetic storage medium, and in more detail, to a sputter device and a method of manufacturing a magnetic storage medium for burying a predetermined material in a concave part in a layer (for example, a recording layer) in which concave/convex parts are formed.
Conventionally, as a scheme for burying a pattern frequently used for semiconductor devices, a scheme is used, in which a target and a substrate are separated, only ionized sputter particles are attracted by a substrate bias, and they are caused to enter in a direction perpendicular to the substrate. According to this scheme, it is possible to improve bottom coverage. However, by such a scheme, when a recording layer having a concave/convex pattern is formed on a substrate, there may be a case where a difference in level in the pattern is not relaxed because films are deposited also on the top (convex part) side of the pattern more than those on the bottom (concave part) side.
Because of this, in a magnetic recording medium for which flattening is indispensable, such as BPM (Bit Patterned Media) and DTM (Discrete Track Media), films are deposited thick once and etching is performed using an etching means, such as IBE (Ion Beam Etching) and RIE (Reactive Ion Etching) (see Patent Document 1).
[Patent Document 1] Japanese Patent Laid-Open No. 2005-235357
However, when the difference in level of the film surface in a concave/convex pattern formed in a recording layer etc. is large, it is necessary to repeat several times the cycle of forming a film to be buried in the concave part and etching for flattening, and therefore, reduction in production efficiency and a rise in device cost result.
The present invention has been made in view of such problems and an object thereof is to provide a sputter device and a method of manufacturing a magnetic storage medium capable of forming a buried layer with higher production efficiency.
In order to achieve the above-mentioned object, the present invention is a sputter device characterized by comprising a vacuum vessel, two cathodes arranged in opposition to each other in the vacuum vessel and capable of generating plasma in a region between the two cathodes by supply of high-frequency power, and a phase adjustment mechanism capable of adjusting phases of high-frequency power outputs to be supplied to each of the two cathodes into the same phase, and by being configured such that a substrate holding mechanism to hold a substrate is disposed in the region between the two cathodes where plasma is generated.
Moreover, the present invention is a method of manufacturing a magnetic recording medium for performing deposition of a buried layer by the high-frequency sputtering method for a concave/convex pattern of a recording magnetic layer provided on a substrate, characterized by comprising the steps of disposing a substrate holding mechanism to hold a substrate having the recording magnetic layer in a region between two cathodes arranged in opposition to each other in a vacuum vessel and supporting a target and generating plasma on both surfaces of the substrate by introducing a discharge gas into the vacuum vessel and supplying high-frequency power in the same phase to the two cathodes, and in that the deposition of the buried layer is performed by the high-frequency sputtering method using sputter particles generated from the target by sputter using the plasma and ions of the discharge gas.
According to the present invention, it is possible to form flat films on both surfaces using high-frequency waves.
In order to solve the above-mentioned problems, in the present invention, deposition of a buried layer is performed by supplying high-frequency power in the same phase to cathodes arranged in opposition to each other on both sides of a substrate at a predetermined interval to generate plasma on both surfaces of the substrate and by sputtering a target provided on both sides of the substrate. It is preferable for the above-mentioned predetermined interval to be 70 mm or less. It may also be possible to perform deposition of the above-mentioned buried layer by forming an attracting electric field to attract positive ions in the plasma into the substrate when sputtering the target and attracting the positive ions into the substrate by the attracting electric field.
It is possible to appropriately utilize the present invention in forming a buried layer of a recording magnetic layer in a magnetic recording medium (a layer buried in a concave part formed in a recording magnetic layer having concave/convex parts as in a concave/convex pattern). The structure and the constituent material of such a magnetic recording medium are not limited as long as it is a magnetic recording medium having a buried layer by the high-frequency sputtering method.
The formation of a buried layer in the present invention is explained using
As described above, it is necessary to sufficiently supply gas ions (for example, the ions 2 of the discharge gas) for etching to the concave/convex pattern provided on the substrate and at the same time, to increase the proportion of the gas ions (for example, the ionized sputter particles 4) corresponding to the deposition particles that reach the concave/convex pattern provided on the substrate, in order to implement selective etching by ions on the surface of the concave/convex pattern of the substrate, in particular, on the top side of the concave/convex pattern.
In order to supply gas ions to the concave/convex pattern provided on the substrate, it is effective to reduce the distance between the cathode and the substrate and attract the gas ions generated by the target discharge on the cathode by the substrate bias. In order to increase the proportion of the gas ions (deposition particle gas ions) corresponding to the deposition particles, the sputter deposition by high-frequency waves is most suitable.
However, the reduction in the distance between the cathode of the high-frequency discharge and the substrate leads to mutual interference between the high-frequency waves of both the cathodes. Because of this, in order to solve this problem, in the present invention, a mechanism to control the phase of the high-frequency power output to be supplied to the cathode is provided and thereby the phase of the high-frequency power source provided on both sides of the substrate is controlled and thus the plasma distribution is made uniform and the deposition distribution is improved.
The distance between the cathode and the substrate placed on the substrate holding mechanism 210 is set so that the distance from the surface of the target 209 to the substrate surface (hereinafter, also referred to as “T/S value”) is not less than 20 mm and not more than 70 mm, or preferably, not more than 40 mm. Due to this, it is possible to uniformly supply ions generated when the discharge gas introduced from the gas introduction system 214 is turned into plasma to the surface to be processed of the substrate and to promote etching of the deposited film by the ions. It may also be possible to set the distance described above by adjusting the thickness of a cathode spacer 202 provided between the cathode and the vacuum vessel 205. The diameter of the cathode or the substrate is not limited in particular in the present invention and it is possible to appropriately use a disc-shaped target having a diameter greater than that of the disc-shaped substrate. For example, it is possible to use a substrate having a diameter of about 40 to 100 mm for a target having a diameter of 164 mm.
The high-frequency power sources 208A, 208B supply high-frequency power (for example, 13.56 MHz to 100 MHz) to the cathode. By using the high-frequency power source, it is possible to increase the ionization rate of the discharge gas and to increase the etching rate by the ions of the discharge gas. The magnitude of the supplied power is not limited in particular and for example, may be set to 100 W to 500 W. The cathodes on both sides are connected to the different high-frequency power sources respectively via the matching devices. The matching device is a matching device to match the input impedance to the cathode with the output impedance on the high-frequency power source side and includes a variable impedance element, such as a variable capacitor and variable inductor, for example.
The vacuum vessel is grounded and due to this, a discharge is caused to occur between the vacuum vessel and the cathode by the introduction 204 of the discharge gas using the vacuum vessel as a ground electrode.
A phase adjuster (phase adjustment mechanism) 213 has a phase difference detection unit 217 that detects each phase (in the diagram, the phase of potential on each transmission path between each cathode and each matching device) of the voltage (high-frequency power output) supplied to the cathode on both sides of the substrate holding mechanism 210 and detects its phase difference and a phase adjustment unit 216 that makes the phases of the power (high-frequency power outputs) to be supplied to the two cathodes into the same phase (phase difference 0°±45°) by controlling each of the high-frequency power sources 208A, 208B when the phases of the power output to both the cathodes are different. In the example in
For example, when the phases of power to be supplied to the two cathodes are made opposite to each other, a discharge is caused to occur between the two cathodes because the distance between the substrate 201 and the target 209 is set to a comparatively short distance as described above, and therefore, plasma exists in a comparatively limited region. On the contrary to this, when the phases of power to be supplied to the two cathodes is made the same, a discharge is caused to occur between the substrate 201 and the sidewall of the grounded vacuum vessel 205, and the cathode, and plasma is formed in a region larger than that in the case where the phases are made opposite, and therefore, in the region in the vicinity of the substrate, the plasma density becomes uniform.
The adjustment of phases is made between an interval of deposition processing, however, it may also be made during the period of deposition processing.
By means of the magnet mechanism 206 provided on the back side of the cathode, it is possible to form a magnetic field in the vacuum vessel, which is horizontal with the target surface and perpendicular to the electric field for forming plasma. Due to this magnetic field, plasma is confined to the target surface in a high density and a magnetron discharge is caused to occur. The magnet mechanism 206 is not an indispensable component in the present invention, however, by causing a magnetron discharge on both sides of the substrate, it is possible to further increase the proportion of the discharge gas ions that reach the substrate.
As shown in the front view in
The gas introduction system 214 is provided so as to introduce a discharge gas (for example, Ar) from the top of the vacuum vessel 205 and the exhaust means 212 (cryopump, turbo molecular pump, etc.) is provided at the lower part to exhaust the interior of the sputter device. Due to this, it is possible to keep the pressure at the time of sputter at, for example, 1 Pa to 10 Pa. By keeping a comparatively high pressure, it is possible to increase the plasma density of the discharge gas and to promote etching by ionization of the discharge gas.
A stacked layer body in step 1 in
For this stacked layer body, a buried layer 305 is formed so as to fill the grove of the recording magnetic layer 304 by using the sputter device shown in
After that, the excess buried layer 305 is removed by etching etc. and after the recording magnetic layer 304 is exposed (step 3 in
The conditions may also be changed so that as the irregularities become smaller, the amount of etching is increased when, for example, removing the excess buried layer 305.
In the present invention, it is particularly preferable to form a buried material into a film by the high-frequency sputtering method under the conditions that the deposition rate ratio compared to that when the attracting electric field is not formed is 90% or less. Here, the deposition rate ratio compared to that when the attracting electric field is not formed is a ratio of the deposition rate when forming a film on a flat surface while forming the attracting electric field, to the deposition rate when forming a film on a flat surface under the same conditions without forming the attracting electric field, in forming a film using a deposition gas (for example, a gas including ionized deposition particles) and an etching gas (for example, a discharge gas). The deposition rate is on the basis of the film thickness of a film formed per unit time.
When the deposition rate ratio exceeds 90%, the attracting of the etching gas into the substrate by the attracting electric field becomes weak, the etching becomes insufficient, and the effect of flattening the film surface becomes slight. Under the condition of too large an amount of etching, there may be a case where the deposition efficiency is reduced and the film thickness distribution is reduced. Consequently, although not limited, it is preferable to select the deposition rate ratio from among the range of 55% to 75%.
In order to obtain the target deposition rate ratio, a deposition rate when forming a film using a buried material on the flat surface of the substrate in a state where the attracting electric field is not applied is found, a deposition rate when the attracting electric field is applied under the same deposition condition is found, and the ratio of these rates is calculated. If the target deposition rate ratio is not obtained by the above-mentioned operation, the deposition conditions are changed in a variety of ways so that the target deposition rate ratio is obtained. By using the deposition conditions with which the target deposition rate ratio is obtained as described above, a buried layer is actually formed.
It is possible to adjust the deposition rate ratio by one or more parameters selected from among the pressure in the vacuum vessel at the time of deposition (process pressure), the application condition of the attracting electric field, the distance between the substrate and the target, etc. Among these conditions, it is preferable to adjust the deposition rate ratio using both the bias voltage to be applied to the substrate to adjust the attracting electric field and the process pressure.
It is possible to use the high-frequency sputter device for forming a film on both sides according to the present invention also when forming the above-mentioned recording magnetic layer 304, the foundation layer 303, other etching stop layers, etc., in addition to the buried layer 305 and it is possible to form a film on both sides with high uniformity in film thickness by making the electric power to be supplied to the cathodes arranged on both sides of the substrate into the same phase.
As described above, in the present invention, high-frequency power in the same phase is supplied to the two cathodes arranged in opposition to each other, and therefore, even if the distance between the substrate and each of the cathodes is reduced (for example, 70 mm or less) to reduce the interval between the two cathodes, it is possible to suppress the high frequency waves supplied to the two cathodes from interfering with each other. Consequently, even if the distance between the two cathodes is reduced and high-frequency power is supplied to the cathodes, the interference of the high-frequency power can be suppressed, and therefore, it is possible to make uniform the plasma formed by the above-mentioned cathodes. Further, the high-frequency power can be used in a state where the above-mentioned interference is reduced, and therefore, it is possible to efficiently generate gas ions corresponding to the deposition particles.
Because of the above, according to the present invention, even when the difference in level of the surface is large in the concave/convex pattern formed in the recording magnetic layer, it is possible to make uniform the distribution of thickness of the film formed by the above-mentioned uniform plasma and to suppress the irregularities formed in the buried layer from occurring. Consequently, it is possible to make an attempt to flatten the buried layer without the need to repeat deposition of the buried layer and etching and to suppress the reduction in production efficiency and the rise in device cost.
In Example 1, the sputter device shown in
As a result of this, it has been found that when the phase difference between the high frequency waves to be supplied to both the cathodes is 0°, that is, in the state where they are in phase, the uniformity of the film thickness distribution on the substrate is more excellent and the deposition rate is somewhat lower compared to when the phases are opposite as shown in Table 1. This can be thought because the discharge between the cathodes spreads in the widest range and thereby the discharge distribution in the vicinity of the substrate becomes more uniform.
In Example 2, the sputter device shown in
As a result, it has been found that the irregularities on the film surface after the deposition are more suppressed from occurring when the T/S value is set to 40 mm compared to when the condition of the T/S value is 100 mm.
In Example 3, a relationship among the process pressure, the bias voltage, and the deposition rate ratio was examined. The sputter device (T/S value: 40 mm) shown in
Under the same condition described above as to each deposition rate ratio, a film was formed on the DTM medium substrate on which a plurality of grooves with a pitch of 100 nm (groove width 50 nm) and a depth of 20 nm was formed in the direction of the diameter.
As shown in
From the above, it is preferable for the deposition rate ratio to be 90% or less to sufficiently achieve the effect of the film surface flattening. Under the condition that the amount of etching is too much, there may be a case where not only the deposition efficiency but also the film thickness distribution becomes poor. Because of this, although not limited, it is preferable for the deposition rate ratio to be selected from the range of 55% to 75%.
In the present invention, when an attracting electric field is used as described above, it is preferable to set the deposition rate ratio to 90% or less or more preferably, 55% to 75%. What is important in the present invention is to make the phase of high-frequency power to be supplied to the two cathodes into the same phase when supplying high-frequency power to the two cathodes arranged in opposition to each other. By setting so, it is possible to suppress interference between high-frequency power and to form uniform plasma even if the two cathodes are arranged in close proximity, and therefore, it is possible to make an attempt to flatten a buried layer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-334095 | Dec 2008 | JP | national |
This application is a continuation application of International Application No. PCT/JP2009/071645, filed Dec. 25, 2009, which claims the benefit of Japanese Patent Application No. 2008-334095, filed Dec. 26, 2008. The contents of the aforementioned applications are incorporated herein by reference in their entities.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2009/071645 | Dec 2009 | US |
| Child | 13168560 | US |
