JP3893436B2 - Inclined target type magnetron sputtering system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a thin film forming apparatus used for the manufacture of various semiconductor devices, the formation of corrosion resistance on machine parts and the like, the formation of wear-resistant films, and the formation of decorative films such as crafts and building materials.
[0002]
[Prior art]
Sputtering has the major feature that it can produce evaporated atoms directly from solids, and bipolar sputtering and magnetron sputtering are mainly used as sputtering methods. Especially, as sputtering equipment with high film deposition rate , electric and magnetic fields are used. Magnetron sputtering with a high combined plasma density has been widely implemented. However, there is a big difference in the quality of the film produced by the sputtering method. To obtain a dense and excellent adhesive film , use high-energy sputtered particles that operate at high vacuum, such as ion beam sputtering. A sputtering method capable of depositing a film is effective, but the method is expensive due to the complexity of the apparatus and the film deposition rate.
[0003]
The target used for sputtering can be made of various materials, but it is known that the deposition rate of the film is low and it takes a long time to produce the film, particularly when an insulating target is used. Yes. If the input power is increased to increase the sputtering rate, there is a risk that the target itself will break due to thermal expansion and heat conduction of the insulating target. As a technology to solve this, reactive sputtering has been devised, which uses a metal material with excellent thermal conductivity for the target, introduces a gas that reacts with the metal into a part of the introduced gas, and performs sputtering. In order to obtain a sufficient reaction, a large amount of gas is introduced, resulting in production conditions at a high gas pressure, resulting in a phenomenon in which sputtered particles collide with the gas in the apparatus , and the energy is reduced. not because excellent film dense adhesion obtained such a. The case, from the relationship of gas pressure, a reaction occurs at the target surface, the insulator on the surface of the conductive metal target is formed, there is a problem that Teyajiappu sputtering phenomenon can no longer occur. Therefore, until now, DC sputtering using a DC power source has been impossible, and RF sputtering using a high frequency power source has been used. However, to do film manufactured on a large area at high speed, than the hard RF sputtering impedance matching, who performed a simple DC sputtering is superior in cost.
[0004]
In the magnetron sputtering method currently widely used, a planar magnetron sputtering apparatus is used to increase the processing area, but since the magnet that generates the magnetic field is located at the rear of the target, there is little erosion in that part, and the target is used. ineffective. As a solution to this problem, improvements have been made to move the internal magnet so that the erosion is as uniform as possible. However, this is not an adequate solution.
[0005]
[Problems to be solved by the invention]
In order to solve the above problems, in the present invention, so far as compared with sputtering, to achieve sputtering film can be produced having a dense structure using high-energy sputtering particles and recoil atoms of gas Another object of the present invention is to provide an apparatus characterized by high-speed film deposition .
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention places the target symmetrically by them to a function to be inclined with respect to the substrate, and the generation mechanism of high energy sputter particles and recoil atoms of gas from the target In this state, a mechanism capable of operating at a high degree of vacuum necessary to reach the substrate is provided .
[0007]
Here, in order to use the recoil atoms of the sputtering gas is reflected by the sputtering particles and target states have high energy film deposition, reach the substrate without those generated by the target collide with the vacuum chamber inside of the gas It is necessary to discharge at high vacuum. This condition can be expressed by the fact that the mean free path of sputtered particles is longer than the distance between the substrate and the target. However, it has been difficult to realize this condition in the conventional magnetron sputtering apparatus. Therefore, in the present invention, by distributing a magnet next to the target, a strong electron magnetic electrically floating next to the containment and target by, by reflection of electrons utilizing the floating potential, required for the magnetron mode by ensure smooth electron orbit, characterized by allowing a uniform erosion of the target by operating a high-density and uniform plasma formation in a high vacuum.
Further, at the end of the target, in order to change smoothly to the target in a pair of electron trajectories, the magnetic field generated by the target inner side of the magnet shorter than the outer side of the magnet, the target end It is characterized in that electrons are reflected by a floating potential caused by the arranged metal plate, smooth movement of the electron trajectory between the targets, and operation in a high vacuum is possible.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The sputtering apparatus of the present invention was designed based on the result of detailed analysis of the sputtering phenomenon using Monte Carlo simulation. As an example, FIGS. 5 to 7 show analysis results on the energy and amount of sputtered particles and recoil argon generated when an iron target is irradiated with argon ions accelerated at 1200 V vertically. FIG. 4 shows the angles defined in this simulation. The angle 25 was set to 0 degree with respect to the target surface, and the axis was set to be 90 degrees on the upper part of the target.
[0010]
FIG. 5 shows the angular distribution of the energy of the sputtered particles. The angle 90 degrees is located parallel to the substrate, the average energy of sputtered particles iron is about 3 0 eV, where angle 45 ° inclined 45 degrees, it was Tsu very high and 80 eV. On the other hand, the recoil argon which is a recoil atoms of the sputtering gas, as shown in FIG. 6, at an angle of 90 degrees, according to the average energy 55EV, at an angle 45 degrees location is inclined and 70 eV, the energy there has been a tendency ing moderately large. However, it did not significantly change flower as the energy of the sputtered particles. These results mean that there are high energy sputtered particles and gas recoil atoms in the direction inclined from the target surface, and the inclined direction is higher than the substrate position parallel to the conventional target surface. It shows that film deposition using energy state can be performed.
[0011]
Next, the angular dependence on the amount of each particle was examined . The distribution of sputtered particles showed a regular distribution, and recoil argon showed a gentler distribution. Figure 7, shows the arrival ratio representing the number of recoil argon for one of sputtered particles. At an angle of 90 degrees parallel to the target, the reach ratio is 0.02, but at a 45-degree tilted angle of 45 degrees, the value is 0.08, and at a further tilted angle of 20 degrees 0.3 that Tsu argon impact there more than 10 times of the position parallel to the normal target. In other words, thus increasing the inclination angle from the target, the amount of recoil argon high energy increases, monitor and the sputtered particles of high energy aforementioned film utilizing the shock effect of the recoil argon high energy It can be seen that the fabrication of
[0012]
From the above, the outline of the sputtering phenomenon occurring in the target will be described with reference to FIG. When exposed to ions of the sputtering gas to cause sputtering phenomenon from the target upper 20, the target upper sputtered particles 21 of low energy, the inclined portion of the target lateral, sputtered particles 22 of high energy is released. On the other hand, some of the ions 20 accelerated to cause sputtering phenomenon is reflected by the target, become recoil atoms 23 with a relatively high energy, and reach the substrate. Therefore, the impact effect of these particles can be controlled by changing the inclination of the substrate with respect to the target.
[0013]
The above conditions were reproduced using an ion beam sputtering method that operates in a high vacuum, and the angle dependence of the substrate was examined . As a result, the film quality of the sputtered film changed greatly as the inclination from the target surface increased . The change showed the same change as the change in film quality formed by high energy sputter particles. The change started to be effective at 20 degrees with respect to the position parallel to the target, and it was confirmed that there was a large change at 40 to 50 degrees. Because significantly reduced Tilting more than 75 degrees with respect to the film deposition rate, as the gradient effect, the relationship between the film deposition rate was found effective der Rukoto in the range of 20 degrees to about 75 degrees.
[0014]
Hereinafter, how the sputtering apparatus having this structure works will be described. Unlike a normal sputtering apparatus, the sputtering apparatus of the present invention is installed with the target surface not inclined in parallel to the substrate. By the above action, film deposition using sputtered particles having energy several times larger than the energy of normal sputtered particles becomes possible . Further, since the is several times the number of recoil atoms of the sputtering gas often for sputtering particles per unit, strong impact effect by their also obtained.
[0015]
This indicates that, when reactive sputtering is considered, the number of substrate impacts of the reactive gas introduced to react with the sputtered particles increases, so that stronger reactive sputtering can be performed. Recoil atoms of the reactive gas, the energy near room temperature of the gas in the vacuum device, greatly different, have a high energy of several tens ～100EV, larger than the reaction energy of the conventional materials, chemical reactions Is easy to proceed. Therefore, good reactive sputtering can be performed.
[0016]
Specifically, when an element that becomes reactive sputtering is considered, oxides, nitrides, and the like can be given. In this case, as reactive gases, there are gases such as oxygen, nitrogen, and ammonia containing those elements, but all of them are often lighter than a sputtering gas such as argon. the number of recoil atoms of the reactive gas is reflected by the target is increased, increasing the chance that reaction occurs at the substrate, it is possible to perform an excellent reactive sputtering.
[0017]
In the conventional magnetron sputtering apparatus, since the voltage applied to the cathode and the current characteristics are determined by the introduced gas pressure, it is difficult to control the energy of the sputtered particles. However, the operation in the high vacuum of this configuration has a large voltage change range, and by changing the tilt angle, the energy of the sputtered particles can be controlled, and a wide range of film quality can be controlled. For example, if the desired film quality cannot be obtained with too high energy particles, or if the residual stress due to the substrate impact is too large, the effect can be reduced by making the tilt angle close to parallel. .
[0018]
The angle dependence substantially regular distribution of the sputtered particles by the target material, or by the sputtering conditions, because they are known to exhibit under regular distribution recessed central portion, the control so that the film deposition rate is maximized It is also possible to do. Also, placing the subject targets two as a pair, many sputtered particles do not go in the direction of the substrate attached to the other target, where it is re-sputtered, toward the substrate to form a thin film Sputtered particles are released and a film is formed . Therefore, this action is repeated until the substrate is reached, and a film using the target can be formed efficiently.
[0019]
Here, if you take as large as possible to the substrate, in addition to the high energy components emanating from the target low angle, it will reach on the substrate many vertical low energy component to the target. Therefore, in order to enhance the uniformity of the energy, so that a plate having a certain thickness between the target and the substrate arranged in a lattice shape, recoil atoms sputtered particles and the gas in the angular range of the therein can pass By installing a collimator and blocking low-energy particles, the energy of those particles can be made uniform, and film deposition using sputtered particles or recoil gas with optimum energy is also possible. In order to use the angular dependence of the phenomenon of energy of the sputtered particles to film deposition, sputtered particles it is discharged at high vacuum that does not cause gas collision is essential, it is conducted in the following configuration.
[0020]
Arranged magnet next to the target to form a strong magnetic field on the target surface. Further, such secondary electrons generated by the sputtering phenomenon so as not to go other than the target surface, placed a metal plate next to the target, impart an electron reflection function to float it electrically. Further, in order to perform smooth movement of electrons between two was a set target, the formation of the radial magnetic field distribution around the internal target, a conductive metal plate to a position slightly apart from the target end And electrically floating it so that it has an electron reflection function so that the electron trajectory is looped between the pair of targets, and the electrons necessary for gas ionization are contained on the target.
[0021]
These configuration, not only the operation at high vacuum, for the erosion of the target, one lifting the following features. In a typical magnetron sputtering, the structure to place the magnets to the target lower, there is no magnetic field component parallel to the target at the top of the magnet. For this reason, the plasma density in the portion is small and the sputtering efficiency is deteriorated, so that the erosion of the target is not uniform on the surface. In this configuration, structural portions that are not on the target, there is a horizontal component on the target the entire surface, and, for part of the magnet has an electron-reflecting function using the floating potential and the magnetic field generator, the target surface A uniform plasma density can be formed. As a result, erosion of the target uniformly such order, excellent target utilization efficiency.
[0022]
By using a pair of two targets, it is possible to arrange a part of the low energy sputtered particles emitted in the target vertical direction so as to be blocked by the pair of targets. With optimal settings, only high energy sputtered particles can be used for film deposition . Furthermore, since the configuration of the present invention uses a rectangular target, it can theoretically be extended in the lateral direction, and a large-area film can be produced .
[0023]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of one embodiment, and FIG. 2 is a schematic view of a target, a magnet, a floating potential metal plate, and an electron orbit viewed from above. Figure 3 is a saw device it obliquely. 8, for measuring the uniformity of the energy with respect to recoil atoms sputtered particles and the gas is a schematic view of a collimator portion. This apparatus describes a target portion for performing sputtering. This portion is maintained at a predetermined degree of vacuum by an evacuation apparatus, and a predetermined amount of gas for forming plasma is introduced.
[0024]
Arrange target 1,2 targeting, high energy sputtering particles and recoil atoms of gas to direct on the substrate, and rotating their target about an axis of rotation 11 of the target holder, a target relative to the substrate Install in a state where the surface is inclined. The substrate 3 is attached to the substrate holder 4. To enable the sputtering of a magnetron mode, arranged magnets 5,6 of different magnetic poles next to the target 1, to obtain a horizontal magnetic field 17, 18 on the target surface. The magnetic field is looped by the same target holder 7. Place the metal plate 7 floated electrically between the magnets 5,6 next to the target, or to electrically isolate the conductive magnets 5 and 6, to electrically floating state. Since a negative voltage is applied as a sputtering voltage to the targets 1 and 2, they are insulated from the target holder 8 by the insulating sheet 10. In order to suppress the temperature rise caused by the sputtering, the targets 1 and 2 are water cooled from the back through the water cooling pipe 9.
[0025]
A negative voltage (about several hundred to several thousand volts) is applied to the targets 1 and 2 to cause discharge. In this state, in the sheath 12 portion of the target surface, electrons are pushed back to the plasma 13 on the sheath mainly by an electric field, but in the plasma, the electrons are perpendicular to the magnetic field by the horizontal magnetic field formed by the magnets 5 and 6. Causes cyclotron motion 16 in the direction. However, and the magnetic field disturbance, by the electric field within the plasma, since all electronic exercise is not necessarily the motion of the track 16, the electrically floating metal plate 7 between the magnets 5,6 next to the target arranged to, or to float a magnet 5 and 6 electrically, to form an equilibrium potential of the plasma. Since the potential is closer to the negative cathode potential than the plasma potential, it is a negative potential when viewed from the electrons in the plasma. Therefore, electrons in Rukoto reflected electrons to put hardly disappear, electrons in the plasma in a high vacuum will rotate while on the track 16 to draw the loop.
[0026]
On the other hand, in the target end region 19 where the electron trajectory changes abruptly, the length of the magnet 6 is made shorter than the length of the magnet 5, and the magnetic field direction is changed from 18 to 17 so that the electron trajectory draws an arc. To change. At the same, in order to provide electron reflection function on the target ends, arranged electrically floating metal plate 14 and 15, the pair at its negative floating conductive position was not completely rotate electrons with the Lorentz force caused by the magnetic field Reflect and guide onto the target. As a result, the electrons generated on the target rotate on the orbit 16 without escaping to other parts, efficiently collide and ionize with the gas existing on the orbit, and plasma is formed even in a high vacuum . Positive ions in the plasma bombard the target, generating sputtered particles . Then, to a direction inclined energetic sputtered particles 23 and recoil atoms 24 of gas that form a film to reach the substrate 3. Sputtering particles flying in pairs targets, where it is re-sputtered, part of which reaches the substrate.
[0027]
In this configuration, two rectangular targets are used. However , when the substrate is close to the target, due to the structure, in addition to the high energy component emitted from the target low angle, many low energy components perpendicular to the target reach the substrate. . Therefore, in order to deposit a film with as uniform energy as possible, a plate having a thickness between the target and the substrate is arranged in a lattice 27 so that only sputtered particles perpendicular to the substrate can reach, A collimator 26 that allows only sputtered particles and recoil argon within a certain angle range to pass through the cavity 28 is arranged to cut off the low energy component 22 in the vertical direction to the target . Thus, it measures the uniformity of the energy with respect to sputtering particles arriving from the target to the substrate and the gas recoil atoms, can perform the recoil atoms 24 only in the film deposition of the sputtered particles 23 and the gas having the optimum energy Become . The thickness and interval of the collimator are determined geometrically so as to block the component 22 perpendicular to the target from the positional relationship between the target and the substrate.
[0028]
In the present invention, since the electron trajectories in the plasma is divided into a region 20 of the straight only, a region 19 which transitions to a target to be paired can extend the theoretical straight area 20, a production line A suitable large-area film can be produced . Further, it is possible to produce a film with a large area by repeating this apparatus periodically.
[0029]
【The invention's effect】
The present invention has an effect as described operations to Runode, below, as described above. By a normal plasma sputtering method in which a sputtering gas is ionized with plasma and bombarded perpendicularly to the target, the sputtered particles are in a high energy state due to the operation in a high vacuum and the inclination of the target . On the other hand, the target recoil atoms of the gas in order to have a gentle distribution than regular distribution of the sputtered particles, reach ratio indicating a ratio of the recoil atoms sputtered particles and gas inclined place, to be used in conventional sputtering considerably larger than in the case with parallel, the energy is several tens of eV and a very higher due. Therefore, by inclining the target, the effect of both the bombardment by high energy sputter particles and gas recoil atoms are available, it is possible to produce excellent film dense film structure and adhesion.
[0030]
Furthermore, a rectangular target to effectively achieve the target tilting effect, because of the structure used two in pairs, since it can easily be theoretically extend the length of the target, suitable for production facilities line and, it can have a large-area film formation. In the apparatus of the present invention, discharge is performed at 0.1 mTorr or lower, which is one digit lower than the normal magnetron sputtering operating voltage of 1 mTorr, by confining electrons by a strong horizontal magnetic field and floating potential on the target surface. So, under normal sputtering apparatus, even if the discharge characteristics by varying the voltage, the value of current is substantially a constant value. An arbitrary voltage cannot be selected. However, if the discharge is possible the device in a high vacuum, can be discharged at a higher sputtering voltage than conventional, to be capable of generating higher have sputtered particles and recoil atoms of the gas energy Become. In this region, the average free path of the sputtered particles is several meters, which is much larger than the tens of centimeters of a normal sputtering device, and the high energy particles reach the substrate directly without colliding in the middle. can do. Indeed, when carrying out the film production, between the target and the substrate, often becomes several tens cm, when it is not close to the mean free path 1 m, is to utilize the sputtered particles to their high energy film deposition Have difficulty.
[0031]
Operating in a high vacuum means that the ionization efficiency of the introduced gas in the vicinity of the target is good, and the film deposition rate per unit input power is naturally high and the energy efficiency is also increased. In addition, the plasma density and temperature in the vicinity of the target also increase, and there are many reactive particles. Reactive sputtering using a direct current power source can be easily performed. Depending on the type of target material , the distribution may be a regular distribution or a collapsed under-regular distribution. When it is desired to prioritize the film deposition rate over the film quality, it is possible to increase it by inclining 20 to 30 degrees.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an inclined target type magnetron sputtering apparatus.
FIG. 2 is a top view of a tilted target type magnetron sputtering apparatus.
FIG. 3 is a bird's-eye view of an inclined target type magnetron sputtering apparatus.
FIG. 4 is a schematic view of a sputtering phenomenon.
FIG. 5 is an energy angle distribution diagram of sputtered particles.
FIG. 6 is an energy angle distribution diagram of recoil argon.
FIG. 7 is an angle distribution diagram of the number of recoil argon (unit ratio) per unit sputtered particle.
FIG. 8 is a schematic view of a collimator placed between a target and a substrate as viewed from above.
[Explanation of symbols]
1,2 targets 3 field of the substrate 4 substrate holder 5 magnet 6 magnet 7 the metal plate 8 the target holder 9 water cooling pipe 10 insulating sheet 11 of the target holder rotation shaft 12 plasma sheath 13 plasma 15 metal board 16 orbital 17 target end direction 18 electron transition region 20 the target central area 21 recoiled atoms 25 incident angle of the ion 22 low energy sputtering particles 23 energetic sputtered particles 24 gas for causing sputtering phenomenon 26 between the magnetic field direction 19 pairs on target target Collimator 27 Plate 28 constituting collimator Cavity created by collimator

Claims (3)

For the purpose of obtaining a strong magnetic field on the target surface in order to operate a vacuum in which the average free path of the sputtered particles is longer than the distance between the substrate and the target, the target in a set of two is arranged symmetrically. An external magnet is installed beside the outer surface of the set of targets, and an inner magnet having a polarity different from that of the outer magnet is set beside the facing inner surface of the set of targets, and a looped electron trajectory is formed on the surface of the set of targets. in the sputtering apparatus were placed external magnet to generate a magnetic field so as to obtain a, and is characterized by having a function of tilting the pair of the target to the substrate, high energy generated in the target sputtered particles and the gas recoil atoms by using the film deposition on substrate, film forming apparatus for producing a film of dense structure In the above device, an electrically floating metal plate is disposed between the magnet and the target, an electron reflection function using the floating potential is provided, the electrons are efficiently confined in the upper part of the target , and the device operates at a high degree of vacuum. The film forming apparatus according to claim 1. In the apparatus, a collimator is provided in which a plate having a thickness between the target and the substrate is arranged in a lattice shape, and sputter particles and recoil argon within a certain angle range with respect to the target surface can pass therethrough. installed, film forming apparatus according to claim 1, wherein the attempted equalization of the energy of the sputtered particles arriving from the target to the substrate and the gas recoil atoms

Images