JP2006241598A - Sputtering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a bottom coverage rate while maintaining a required film deposition rate even in the case of a large substrate. <P>SOLUTION: In a magnet mechanism 4 composing a cathode 2, leakage lines of magnetic force going from one part in the surface of a target 5 and entering the other part in the surface of the target 5 is circularly ranged onto the surface of the target 5, so as to set a plurality of circular magnetic fields. In this way, a plurality of erosion regions 50 made into circular shape upon the stillness of the magnet mechanism 4 are formed without being crossed. Among the erosion regions 50, in the part on which sputter particles are made incident from the deepest part of the erosion at the widest incident angle, the incident angle is made narrow compared with the case of one erosion region. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The invention of the present application relates to a sputtering apparatus, and more particularly to a sputtering apparatus used in a film forming process in manufacturing a semiconductor integrated circuit or the like.

Thin film formation by sputtering, especially sputtering used in the film formation process in the production of highly integrated semiconductor devices, requires a high coverage on the bottom of fine holes with a high aspect ratio, that is, improved bottom coverage. ing.
In response to such demands, a device has been devised in which only sputtered particles having a small incident angle are incident on a fine hole to form a film. One of these is called collimated sputtering.

FIG. 10 is a diagram illustrating an outline of a collimated sputtering apparatus which is an example of a conventional sputtering apparatus with an improved bottom coverage rate. In the apparatus shown in FIG. 10, a cathode 2 and a substrate holder 3 are disposed to face each other in a vacuum vessel 1. The cathode 2 includes a magnet mechanism 4 and a target 5 disposed on the front side of the magnet mechanism 4, and a substrate 30 on which a film is formed is placed on the front surface of the substrate holder 3.
A collimator 6 is provided in the space between the cathode 2 and the substrate holder 3. The collimator 6 has a structure in which a large number of small cylindrical members are arranged in a segment shape such that a direction perpendicular to the substrate 30 (hereinafter referred to as an axial direction) is a height direction, and sputter particles along the axial direction. A large number of flow paths are formed in segments. Such a structure is often referred to as “lattice” or “honeycomb”.

Since the sputtered particles emitted from the target 5 have a distribution according to the cosine law, many sputtered particles having a large incident angle also enter the collimator 6. However, since many of such sputtered particles adhere to the wall portion of each flow path of the collimator 6, as a result, most of the sputtered particles that exit the collimator 6 have a small emission angle. Become. For this reason, only a small incident angle is incident on the substrate 30 and the coverage of the bottom of the fine holes formed on the surface of the substrate 30 is improved.
However, in the collimating sputtering apparatus, the cross-sectional area of each flow path of the collimator 6 is reduced due to adhesion of the sputtered particles to the collimator 6, and the amount of sputtered particles that can pass through the collimator 6 decreases with time. For this reason, the sputtering rate decreases with time.

As a sputtering apparatus having a high bottom coverage rate without such a problem, an apparatus called a low-pressure remote sputtering apparatus having a long target-to-substrate distance (hereinafter referred to as TS distance) (3 to 6 times the conventional) has been recently developed. Yes. FIG. 11 is a diagram illustrating an outline of a low-pressure remote sputtering apparatus which is another example of a conventional sputtering apparatus.
In the apparatus shown in FIG. 11, as in FIG. 10, the cathode 2 and the substrate holder 3 are disposed opposite to each other inside the vacuum vessel 1, the target 5 is provided on the front side of the magnet mechanism 4, and the substrate is mounted on the front surface of the substrate holder 3. To place. The TS distance is, for example, about 150 mm to 360 mm. Moreover, the pressure in the vacuum vessel 1 is lower than that of the prior art and is about 1 mTorr or less. This is to increase the mean free path of the sputtered particles and reduce the scattering of the sputtered particles. As a result of less scattering of sputtered particles, more sputtered particles can be incident in a direction substantially perpendicular to the substrate, and the bottom coverage rate of minute holes can be improved.
For example, Japanese Patent Application Laid-Open No. 7-292474 discloses that the bottom coverage rate is improved under the conditions of a target diameter of 250 mm, a substrate diameter of 200 mm, a TS distance of 300 mm, and a pressure of 3 × 10 ⁻² Pa.
Japanese Patent Laid-Open No. 04-074861 JP-A-62-2001865 Japanese Patent Laid-Open No. 05-209267 JP 07-292474 A

  However, as described in Table 3 of the above publication, when the TS distance is increased in order to improve the bottom coverage rate, the film formation rate is significantly reduced. For this reason, low-pressure remote sputtering is effective for forming a fine hole in a process after 256 megabits (line width: 0.25 μm, aspect ratio: 4 to 6), but remains a problem in terms of productivity. ing. When the TS distance is shortened in order to increase the film formation speed, the bottom coverage rate decreases, so that it is difficult to apply to processes of 256 megabits and beyond. That is, in low-pressure remote sputtering, the film formation rate and the bottom coverage rate are in a trade-off relationship and are not compatible.

On the other hand, another point required for the sputtering process is to cope with an increase in the size of the substrate. In the semiconductor device process as described above, since the number of devices produced from one substrate is increased to improve productivity, the substrate size tends to increase. Also, in the sputtering process on a glass substrate when manufacturing a liquid crystal display, the substrate tends to be enlarged in order to increase the display area.
Such an increase in substrate size is intricately intertwined with factors such as TS distance and film formation speed in the low-pressure remote sputtering.
First, when the substrate size is increased, there arises a problem that the bottom coverage rate becomes insufficient in the peripheral portion of the substrate far from the center even in the low-pressure remote sputtering as described above. This point will be described with reference to FIGS.

12 and 13 are diagrams for explaining problems in forming a film on a large substrate using the apparatus shown in FIG. 11. FIG. 12 is a partial view of a target and a substrate in the apparatus. FIG. 5 is a cross-sectional view showing the bottom coverage ratio in the vicinity of the center and the periphery of the substrate.
As shown in FIG. 12, the target 5 and the substrate 30 are arranged to face each other in parallel, and the central axis 20 (the axis passing through the center and perpendicular to the surface) is located on the same straight line. FIG. 12 illustrates a portion on one side from the central axis 20.

When the sputtering is performed, erosion (erosion) as shown by hatching in FIG. 12 occurs on the surface of the target 5. At this time, the state of film formation on the minute hole 301 formed in the substrate 30 differs between the vicinity of the center and the peripheral portion as shown in FIG. That is, as shown in FIG. 13A, in the vicinity of the center of the substrate 30, a film 302 is deposited on the bottom of the minute hole 301 with good coverage. However, in the peripheral portion of the substrate 30 that is larger than the diameter of the target 5, as shown in FIG. 13B, the number of sputtered particles incident at a large incident angle from the central axis side increases. Although the film 302 is deposited on the peripheral wall surface of the substrate 30, it is not deposited on the wall surface and bottom surface on the central axis side.
Such a state becomes a fatal defect in the case of forming a barrier metal (diffusion prevention film) on the inner surface of the contact hole. Therefore, when the substrate is enlarged, the target must be enlarged accordingly.

Now, such a problem of increasing the size of the substrate is intricately entangled with the above-mentioned problem of incompatibility between the film formation speed and the TS distance necessary for the bottom coverage rate, and the problem is further increased. This will be explained using the applicant's internal data.
14 to 17 show experimental data on low-pressure remote sputtering. Among these, FIG. 14 is data showing the pressure and TS distance dependency of the bottom coverage rate, and FIG. 15 is data showing the pressure and TS distance dependency of the sheet resistance distribution of the obtained thin film. 16 and 17 are data showing the relationship of the bottom coverage ratio with respect to the aspect ratio. FIG. 16 shows data when the TS distance is 340 mm, and FIG. 17 shows data when the TS distance is 260 mm. These data are obtained under conditions of a substrate diameter of 6 inches and a target diameter of 269 mm.

First, as shown in FIG. 14, the bottom coverage rate is improved on the low pressure side, and a higher bottom coverage rate is obtained when the TS distance is 100 mm compared to the TS distance of 65 mm. Further, a higher bottom coverage rate is obtained in the peripheral portion than in the vicinity of the center of the substrate.
Further, as shown in FIG. 15, when the TS distance is increased, the uniformity of the sheet resistance distribution tends to deteriorate, but when the pressure is decreased, this tendency is alleviated. That is, when the length is 2.0 mTorr or less, the sheet resistance distribution hardly changes even when the TS distance is increased.

  Next, looking at the relationship between the aspect ratio and the bottom coverage ratio, a bottom coverage ratio of 40 to 45% is obtained at an aspect ratio of 2, as shown in FIG. Generally, if the bottom coverage ratio is about 15%, it is said that there are no problems in various characteristics of the device. From this, it can be seen that the low-pressure remote sputtering method is a remarkably excellent technique. Incidentally, in the case of the collimated sputtering apparatus as shown in FIG. 10, the bottom coverage rate is about 15%, and the superiority of the low-pressure remote sputtering method can be seen again compared with this.

In FIG. 16, the ◯ marks indicate the bottom coverage rate near the center of the substrate, and the ● marks indicate the bottom coverage rate at the periphery. Both data are almost aligned on the same line, and it can be seen that the bottom coverage rate in the plane of the substrate maintains high uniformity. The deposition rate is about 600 angstroms per minute, which is the same as that of the collimated sputtering method, and is reduced to about 1/3 to 1/4 compared with the conventional sputtering.
On the other hand, when the TS distance is shortened to 260 mm, the deposition rate is improved to 1000 angstroms per minute, but the bottom coverage ratio is reduced to about 28 to 35% at an aspect ratio of 2, as shown in FIG. However, even in this case, it is higher than 15% of the collimated sputtering method.

Now, from these results, it will be examined what happens to the bottom coverage rate and the film formation rate when the substrate is enlarged to a diameter of, for example, 300 mm. FIG. 18 is a diagram showing the results of studying the influence of the increase in the size of the substrate on the bottom coverage rate and the deposition rate. In FIG. 18, the cross-sectional shape of erosion in the target 5 is indicated by oblique lines.
First, as shown in FIG. 17, an excellent bottom coverage rate can be obtained under the conditions of a target diameter of 269 mm and a TS distance of 340 mm (FIG. 18A). This is the same when the substrate 30 has a diameter of 8 inches smaller than the target 5.
Next, when the substrate 30 becomes 300 mm larger than the target 5, it is necessary to enlarge the target 5 to the same extent as the substrate 30 as described above. In this case, in order to obtain the same bottom coverage rate, it is considered that the TS distance must be further increased.

The above point will be described by representing the flight path of sputtered particles from the deepest part of the erosion. In many sputtering, a specific portion in the radial direction of the target tends to be eroded most deeply in a region where erosion occurs on the target (hereinafter referred to as erosion region) (hereinafter, this portion is referred to as the deepest erosion portion). The sputtered particles emitted from this portion have the most dominant influence on the film formation state. The shape of the deepest part of erosion is drawn in many cases because the erosion region is circumferential in flat-plate magnetron sputtering or the like which is currently mainstream.
19 and 20 are diagrams for explaining the point where the deepest erosion portion has a circumferential shape. FIG. 19 is a schematic perspective view of a magnet mechanism in a conventional apparatus, and FIG. 20 is a schematic perspective view of a cathode in the conventional apparatus. is there. 10 and 11, the magnet mechanism 4 disposed on the back side of the flat target 5 includes a central columnar central magnet 412 and a central magnet 412 fixed on a disk-shaped yoke 411. And a cylindrical peripheral magnet 413 that surrounds with a gap.

  Different magnetic poles appear on the front surface of the central magnet 412 and the front surface of the peripheral magnet 413. For example, when the center magnet 412 has an N-pole and the peripheral magnet 413 has an S-pole, the magnetic field lines emitted from the center magnet 412 pass through the target 5 and leak out from a place on the surface of the target 5, and FIG. As shown in FIG. 20, after swelling in an arc shape, it enters another place on the surface of the target 5, passes through the target 5 and reaches the peripheral magnet 413. Such leakage lines of magnetic force continue along the shape of the gap between the center magnet 412 and the peripheral magnet 413, and a circumferential magnetic field as shown in FIGS. 19 and 20 is formed.

In sputtering using the action of a magnetic field such as magnetron sputtering, electrons are captured by the magnetic field and the ionization efficiency of gas molecules is improved. Therefore, the shape of the region where the target 5 is sputtered by ions, that is, the erosion region 50, corresponds to the shape of the magnetic field, and is circumferential in the above example in which the circumferential magnetic field is set.
In magnetron sputtering, electrons perform magnetron motion at a portion where an electric field and a magnetic field are orthogonal, and ionization efficiency is maximized. Accordingly, in the configuration shown in FIGS. 19 and 20, an orthogonal relationship between the electric field and the magnetic field is established at the top portion of the arc-shaped leakage magnetic field lines, and strong erosion tends to occur in a portion below this portion. That is, the erosion deepest part draws a circumferential shape located below the top part of the arc-shaped leakage magnetic field lines.

As described above, since sputtered particles are actively emitted from the deepest erosion portion, the geometrical arrangement of the deepest erosion portion is considered to have the most influence on the state of film formation on the substrate. Here, when the target 5 and the substrate 30 are coaxially disposed opposite to each other as shown in FIGS. 10 and 11, the erosion deepest part of one half of the target 5 is half of the same side of the substrate 30. It is considered that the film formation on the region is affected and the film formation on the other half region is not affected. This is because the erosion for the half circumference on the opposite side of the target 5 also affects the surface of the substrate 30 on the opposite side.
Considering the sputtered particles emitted from the deepest erosion portion of this half circumference, the incident angle incident on the substrate 30 has the largest incident angle near the center of the substrate 30. When the radius of the deepest erosion portion is ½ or less of the radius of the target 5, sputtered particles incident on the peripheral portion of the substrate 30 have the smallest incident angle, but this is rare.

Now, in the example of FIG. 18A in which the target diameter is 269 mm, when the deepest erosion occurs at a position of, for example, 70 mm (diameter 140 mm) from the central axis 20, The incident angle θ is about 11.6 ° under the condition of the TS distance of 340 mm.
On the other hand, when the substrate 30 is increased to 300 mm, the target 5 must be increased to a similar size as described above. As shown in FIG. 18B, when the target 5 having a diameter of 314 mm slightly larger than the substrate 30 is used and the deepest erosion portion is generated at a position having a diameter of 163 mm, if the TS distance is the same, the sputtered particles near the center The incident angle θ is enlarged to about 13.5 °. Accordingly, in order to obtain the same bottom coverage rate with the same incident angle as in FIG. 18A, the TS distance must be actually increased to 397 mm. If the TS distance is increased so far, the film forming speed is reduced to a level where it cannot be put to practical use.

Therefore, as shown in FIG. 18 (d), when the TS distance is set to a practical range of 303 mm (approximately the same as the substrate diameter), the incident angle θ near the center becomes 15.0 °, and FIG. Compared to the case of b), it is enlarged to (15.0 / 11.3) = about 1.3 times. This incident angle of 15.0 ° is the same as when the TS distance is set to about 260 mm when the conventional 269 mm size target 5 (the deepest erosion diameter 140 mm) is used (FIG. 18C). This configuration is the sputtering itself from which the data of FIG. 17 was obtained, and only a bottom coverage rate of about 28 to 35% is obtained for a minute hole with an aspect ratio of 2.
As described above, it is difficult to maintain the necessary film formation rate and improve the bottom coverage rate while the substrate is enlarged, even with the low pressure remote sputtering.

In order to solve the above-mentioned problems, the invention of claim 1 of the present application is directed to a vacuum vessel provided with an exhaust system, a disk-shaped target disposed at a predetermined position in the vacuum vessel, and a magnetic field on the surface side of the target. And a magnet mechanism for setting, a circular substrate is arranged in parallel on the same central axis so as to face the target, and the target is sputtered while capturing the electrons by the magnetic field generated by the magnet mechanism, and is applied to the surface of the substrate. A sputtering apparatus for producing a thin film,
The magnet mechanism sets a leakage magnetic field line that exits from a place on the surface of the target and enters another place on the surface of the target, and has a circumferential shape formed by continuously connecting the leakage magnetic field lines on the surface of the target. In a sputtering apparatus in which a magnetic field is set, and an erosion region that is circumferential when the magnet mechanism is stationary relative to the target is formed on the surface of the target by the circumferential magnetic field,
The magnet mechanism has a first magnetic pole magnet whose surface on the target side is the first magnetic pole, and a second magnetic pole magnet whose magnetic pole on the surface on the target side is a second magnetic pole different from the first magnetic pole. And
The first magnetic pole magnet, when viewed in a plane, includes a circumferential portion that extends along the periphery of the target and has a center on the center axis of the target, and a partition portion that partitions the inside of the circumferential portion. Is extended at a position off the central axis of the target and divides the inside of the circumference into two regions of different sizes,
The second magnetic pole magnets are respectively disposed in two regions in the circumferential portion defined by the partitioning portion of the first magnetic pole magnet,
A plurality of circumferential magnetic fields are set on the surface of the target by the first magnetic pole magnet and each second magnetic pole magnet, and a plurality of circumferential erosion regions are formed so as not to intersect with each other. Have
Similarly, in order to solve the above-described problem, the invention according to claim 2 has a configuration in which the substrate is arranged at a distance of 150 mm or more and 360 mm or less from the target in the configuration of claim 1.
Similarly, in order to solve the above-mentioned problem, the invention described in claim 3 has a configuration in which the rotation mechanism for rotating the magnet mechanism around the central axis of the target is provided in the configuration of claim 1.

As described below, according to the invention described in each claim of the present application, the bottom coverage rate can be improved while maintaining a necessary film forming rate even for a large-sized substrate. As a practical film forming technique for use, it is optimal.
According to the invention of claim 3, in addition to the above effect, the erosion of the target is made uniform, and the utilization efficiency of the target can be improved.

Embodiments of the present invention will be described below.
FIG. 1 is a diagram for explaining the outline of a sputtering apparatus according to the first embodiment of the present invention. A sputtering apparatus shown in FIG. 1 includes a vacuum vessel 1 having an exhaust system 11, a cathode 2 and a substrate holder 3 arranged to face the vacuum vessel 1, and a gas for introducing a predetermined gas into the vacuum vessel 1. The system is mainly composed of an introduction system 7 and a cathode power source 21 that applies a predetermined voltage to the cathode 2.
The apparatus of FIG. 1 has a great feature in the configuration of the cathode 2. 2 and 3 are views for explaining the structure of the cathode 2 in the apparatus of FIG. 1, FIG. 2 is a schematic perspective view for explaining the structure of the magnet mechanism 4, and FIG. 3 is a target 5 by the magnet mechanism 4 of FIG. It is a perspective schematic diagram explaining the structure of the above surrounding magnetic field.
The cathode 2 includes a magnet mechanism 4 and a target 5 disposed on the front side of the magnet mechanism 4, and a predetermined voltage is applied by a cathode power source 21. A characteristic point of this embodiment is that a plurality of circumferential magnetic fields are set on the surface of the target 5 so that circumferential erosion regions do not intersect with each other.
More specifically, the magnet mechanism 4 includes a disc-shaped yoke 421, one N-pole magnet 422 fixed on the yoke 421, and two S-pole magnets 423 and 424. As shown in FIG. 2, the N-pole magnet 422 includes a ring-shaped circumferential portion extending along the periphery of the yoke 421, and a partition portion extending so as to partition a space inside the circumferential portion at a position off the center. It is the shape which consists of. One of the two S-pole magnets is a first S-pole magnet 423 located at the center of the larger space among the spaces partitioned by the outer periphery, and the other is at the center of the smaller space. The second S-pole magnet 424 is located. The central axis 20 is configured to pass near the center of the gap between the first S-pole magnet 423 and the partition portion of the N-pole magnet 422. As can be seen from FIGS. 2 and 3, the circumferential portion of the N-pole magnet 422 extends along the periphery of the target 5.

  According to the magnet mechanism 4 according to the above configuration, two circumferential magnetic fields having different sizes are set on the surface of the target 5 as shown in FIG. That is, the arc-shaped leakage magnetic field lines that come out of the N-pole magnet 422 and reach the first S-pole magnet 423 are connected to the upper circumference around the first S-pole magnet 423 to form a first circumferential magnetic field. The arc-shaped leakage magnetic field lines that come out of the pole magnet 422 and reach the second S-pole magnet 424 form a second circumferential magnetic field that continues in a circumferential manner above the periphery of the second S-pole magnet 424. Then, such two circumferential magnetic fields form two circumferential erosion regions 50 as shown in FIG. 3 without intersecting each other.

The magnet mechanism 4 in the present embodiment is rotated by the rotating mechanism 22 as will be described later. Needless to say, the formation of a plurality of the erosion regions 50 is a state in which the magnet mechanism 4 is stationary. When the magnet mechanism 4 rotates, the erosion region 50 rotates around the central axis 20, so that the erosion region spreads over almost the entire surface of the target 5 (the number of regions is one).
When a plurality of erosion regions 50 having a circumferential shape are formed on the target 5 without intersecting with each other, the diameter of the deepest erosion portion of the erosion region 50 (if the shape of the deepest erosion portion is not circular, The length (width) of the straight line connecting any two points on the circumference passing through the center is the shortest), which is always smaller than the diameter of the conventional deepest erosion portion having one erosion region 50. Become. And if the diameter of the erosion deepest part becomes small, the incident angle of sputtered particles can be made small, without expanding TS distance.

The above point will be described in detail with reference to FIG. FIG. 4 is a schematic cross-sectional view for explaining the effects of the embodiment shown in FIGS. 1 to 3.
In the erosion cross-sectional shape of the target 5 shown by oblique lines in FIG. 4, when the substrate 30 is viewed from the deepest part of the erosion, the positions on the surface of the substrate 30 where the incident angles are the same and the incident angles are the same are shown in FIG. In the same manner as shown in Fig. 5, the position is located coaxially with the center of the deepest part of the circumferential erosion. Then, the incident angle θ of the sputtered particles incident on this portion from the deepest erosion portion is clearly smaller than that in the case of one erosion region as shown in FIG. As shown in FIG. 4, the width of the deepest erosion portion viewed in the direction passing through the center (hereinafter simply referred to as the width of the deepest erosion portion) is φ1 and φ2.

Thus, according to the configuration of the present embodiment, the incident angle of sputtered particles can be reduced without increasing the TS distance. Therefore, it is possible to improve the bottom coverage rate while ensuring a necessary film forming speed, and it is optimal as a practical film forming technique for the next generation integrated circuit that is further highly integrated.
Note that when the distance between the two erosion regions 50 is increased, the incident angle may be maximized at a location on the substrate 30 facing the separated portion. Therefore, the separation distance of the erosion region 50 should be as small as possible, and ideally it should be ½ or less of the width of the deepest part of the erosion.

Moreover, it is preferable from the point of the bottom coverage rate improvement that the width | variety of each erosion deepest part shall be below a board | substrate diameter. When the diameter exceeds the diameter of the substrate 30, the incident angle of the sputtered particles becomes larger than the limit as in the conventional case. However, it is assumed that this situation does not occur unless a target that is abnormally large compared to the substrate or a substrate that is abnormally small compared to the target is used.
Further, the limit of the width of each erosion deepest part with respect to the TS distance is determined by the aspect ratio of the minute hole to be covered. FIG. 5 is a diagram for explaining the relationship between the width of each erosion deepest portion and the aspect ratio with respect to the TS distance.

  As described above, in order to manufacture an integrated circuit of 256 megabits or more, film formation for minute holes having an aspect ratio of 2 or more is required. Here, considering the case where the film is formed in the minute hole 301 having the aspect ratio of 2 by the deepest erosion portion equal to the TS distance, the sputtered particles emitted from the deepest erosion portion are near the edge 303 of the hole opening as shown in FIG. Through to the opposite edge 304 of the bottom of the hole. That is, in the film formation with respect to a minute hole having an aspect ratio of 2, (erosion deepest part width) = (TS distance) is the limit, and if the width of the erosion deepest part becomes larger than that, the bottom coverage ratio is remarkably lowered. Therefore, for the next-generation film forming technology having an aspect ratio of 2 or more, it is desirable that the width of the deepest erosion portion is equal to or less than the TS distance.

Next, the configuration of the other parts of this embodiment and the overall operation will be briefly described.
First, an exhaust system 11 that can exhaust to about 10 ⁻⁸ Torr is adopted. During film formation, a discharge gas such as argon is introduced into the vacuum vessel 1 to maintain a vacuum pressure of about 0.3 mTorr. As in the low-pressure remote sputtering described above, the effect of preventing the scattering of sputtered particles is obtained.
The vessel wall of the vacuum vessel 1 is provided with a gate valve (not shown), and is provided with a transfer system (not shown) that loads and unloads the substrate 30 through the gate valve. In addition, a load lock chamber (not shown) is arranged in parallel in the vacuum container 1 via a gate valve, and the substrate 30 is returned to an atmospheric pressure atmosphere in the load lock chamber isolated from the vacuum container 1. .

  The configuration of the cathode 2 is as described above, but in this embodiment, a rotating mechanism 22 that rotates the cathode 2 around the central axis 20 is attached. The rotation mechanism 22 makes the erosion on the target 5 uniform, and includes a rotation shaft 221 that is coaxial with the central shaft 20 connected to the back surface of the yoke 421, a drive source 222 that rotates the rotation shaft 221, and the like. ing. As described above, since the vicinity of the center axis 20 of the target 5 is included in the erosion region 50, this portion is prevented from remaining without being eroded when the magnet mechanism 4 is rotated. Use efficiency improves.

The substrate holder 3 is provided with a mechanism for attracting and holding the substrate 30 by electrostatic attraction and a heating mechanism for heating the substrate 30 to a predetermined temperature during film formation. A bias power source for applying a predetermined bias voltage to the substrate 30 is connected to the substrate holder 3 as necessary.
The gas introduction system 7 introduces a gas necessary for sputtering discharge into the vacuum vessel 1, and includes a pipe 71 connected to a cylinder (not shown), a flow regulator 72 and a valve 73 provided on the pipe, and the like. Consists of. When reactive sputtering or the like is performed, a reactive gas may be mixed with a discharge gas and introduced.

  The cathode power source 21 is configured to apply a predetermined negative DC voltage or high-frequency voltage necessary for sputtering discharge to the cathode 2. When the target 5 is a metal, a negative DC voltage is applied. When the target 5 is a dielectric or the like, a high-frequency voltage is often applied. The vacuum vessel 1 and the substrate holder 3 when no bias is applied are grounded, and are electrically maintained at the ground potential. The voltage applied to the cathode 2 generates an electric field with these members, and sputter discharge is generated by this electric field.

  In the sputtering apparatus of the present embodiment having the above-described configuration, the substrate 30 is transported into the vacuum vessel 1 through a gate valve (not shown) by a transport system (not shown) and placed on the substrate holder 3. Next, while operating the gas introduction system 7 to introduce a predetermined gas into the vacuum vessel 1, the cathode power source 21 is operated to apply a predetermined voltage to the cathode 2 to generate sputter discharge as described above. As a result, sputtered particles are released from the target 5 and reach the sputtered particle 30 plate for deposition to form a predetermined film.

Here, as described above, in this embodiment, since the erosion region 50 having a small diameter is formed on the target 5, the incident angle of the sputtered particles incident on the substrate 30 is reduced. Therefore, the bottom coverage ratio to the minute holes is remarkably improved as compared with the conventional case.
Next, a second embodiment of the present invention will be described.
FIG. 6 is a schematic perspective view illustrating the configuration of the cathode according to the second embodiment of the present invention. In the second embodiment, three circumferential magnetic fields are set as shown in FIG. In other words, in the present embodiment, the magnet mechanism 4 constituting the cathode 2 includes an N-pole magnet 432 fixed on the yoke 431 and three S-pole magnets 433, and the N-pole magnet 432 is disposed on the periphery of the yoke 431. A ring-shaped outer peripheral portion along the inner periphery, and the inside of the outer peripheral portion has a shape composed of three spaces. And the S pole magnet 433 is each arrange | positioned in the center position of the three spaces in an outer peripheral part.

Three erosion regions 50 are formed on the target 5 without intersecting by the three circumferential magnetic fields shown in FIG. Therefore, the diameter of the deepest part of erosion is reduced also in the second embodiment, and the effect of reducing the incident angle of sputtered particles can be obtained as in the first embodiment. Further, in comparison with the first embodiment, in the present embodiment in which three circumferential magnetic fields are set, the diameter of the erosion region 50 can be further reduced as compared with the case of two circumferential magnetic fields.
Since the configuration other than the magnet mechanism 4 can be the same as that of the first embodiment described above, the description thereof is omitted.

  Next, a third embodiment of the present invention will be described. 7 and 8 are views for explaining a third embodiment of the present invention. FIG. 7 is a plan view and FIG. 8 is a side sectional view. In the first and second embodiments described above, the magnet mechanism 4 is composed of a permanent magnet, but in the third embodiment, it is composed of an electromagnet. That is, the magnet mechanism 4 includes a plate-shaped iron core body 441 and first to fifth five magnetic pole bodies 442, 443, 444, 445, and 446 that are fixed on the iron core body 441 and leak magnetic lines of force on the target 5. And a magnetic field coil 447 wound around the iron core body 441.

  The iron core body 441 is a rectangular plate-like member and is arranged in parallel with the target 5. The five magnetic pole bodies 442, 443, 444, 445, and 446 are band plate-like members arranged with the width direction directed toward the target 5, and are fixed to the surface of the iron core body 441 by welding or the like. . The five magnetic pole bodies 442, 443, 444, 445, 446 are fixed in a posture in which the direction of the short side of the rectangular iron core body 441 is the length direction. Specifically, first and fifth magnetic pole bodies 442 and 446 having N poles are fixed to the edges of the short side portions of the iron core body 441 facing each other, and the fifth magnetic pole body 446 is arranged from the middle in the long side direction. Further, a third magnetic pole body 444 that is also an N pole is fixed at a further position. Then, the second magnetic pole body 443 serving as the S pole is fixed at an intermediate position between the first magnetic pole body 442 and the third magnetic pole body 444, and is similarly positioned at an intermediate position between the third magnetic pole body 444 and the fifth magnetic pole body 446. A fourth magnetic pole body 445 serving as an S pole is fixed.

  Further, between the first magnetic pole body 442 and the second magnetic pole body 443, between the second magnetic pole body 443 and the third magnetic pole body 444, between the third magnetic pole body 444 and the fourth magnetic pole body 445, and the fourth magnetic pole body. Magnetic field coils 447 are wound around portions of the iron core body 441 between the 445 and the fifth magnetic pole body 446, respectively. Then, when a direct current of a predetermined direction flows through each magnetic field coil 447, the first magnetic pole body 442 that is the N pole and the second magnetic pole body 443 that is the S pole are output from the first magnetic pole body 442 and the second magnetic pole body 443. One leakage magnetic field line and a second leakage magnetic field line that exits from the third magnetic pole body 444 as the N pole and the fifth magnetic pole body 446 and reaches the fourth magnetic pole body 445 as the S pole are set.

  Further, eight auxiliary iron core bodies 451, 452, 453, 454, 455, 456, 457, and 458 are arranged on both sides of the iron core body 441 as shown in FIG. The eight auxiliary iron cores 451, 452, 453, 454, 455, 456, 457, and 458 are formed in a plate-like shape like a four-segment fan. Each of the auxiliary iron cores 451, 452, 453, 454, 455, 456, 457, and 458 is fixed to a belt-shaped peripheral magnetic pole body 459 fixed along the peripheral part of the fan and the central part of the fan. A columnar central magnetic pole body 460 is provided.

  Of the eight auxiliary iron cores 451, 452, 453, 454, 455, 456, 457, and 458, the first to fourth auxiliary iron cores 451, 452, 453, and 454 are the first and third magnetic pole bodies. The fifth to eighth auxiliary iron cores 455, 456, 457, and 458 have a radius that is substantially equal to the separation distance between the second magnetic pole body 443 and the second magnetic pole body 443, and the fifth to eighth auxiliary iron core bodies 455, 456, 457, and 458 And the fourth magnetic pole body 445 have a radius substantially equal to the separation distance. Each auxiliary iron core body 451, 452, 453, 454, 455, 456, 457, 458 has a magnetic field coil 447 so that arc-shaped leakage magnetic field lines are set across the peripheral magnetic pole body 459 and the central magnetic pole body 460. It is rolled up.

As shown in FIG. 7, the first to fourth auxiliary iron cores 451, 452, 453, and 454 have their center magnetic poles 460 located in the vicinity of both ends of the second magnetic pole body 443 and their peripheral magnetic poles. The body 459 is arranged so as to form a circumferential shape together with the first magnetic pole body 442 and the third magnetic pole body 443. Similarly, in the fifth to eighth auxiliary iron cores 455, 456, 457, and 458, the central magnetic pole body 460 is located in the vicinity of both ends of the fourth magnetic pole body 445, and the peripheral magnetic pole body 459 is the third magnetic pole body 459. The magnetic pole body 444 and the fifth magnetic pole body 446 are arranged so as to form a circumferential shape.
With such an arrangement, arc-shaped magnetic field lines set by the magnetic pole bodies are arranged in a circumferential shape, and two circumferential magnetic fields are arranged side by side. Then, if the target 5 is arranged coaxially so that the intermediate portion between the second magnetic pole body 443 and the third magnetic pole body 444 is the central axis 20, the cathode substantially equivalent to the magnet mechanism 4 shown in FIG. Two configurations are achieved by electromagnets. Also in the third embodiment, if the magnet mechanism 4 is rotated around the central axis 20, the erosion can be made uniform and the utilization efficiency of the target 5 can be improved.

In the third embodiment using an electromagnet, the magnetic field distribution can be adjusted by controlling the current supplied to each magnetic field coil 447 to improve the film thickness distribution. This point will be described with reference to FIG. FIG. 9 is an explanatory diagram of an application example in which current control means for independently controlling the current supplied to each magnetic field coil is added in the third embodiment shown in FIGS. 7 and 8.
In this example, the current control means includes a DC power supply 448 that supplies a DC current to each of the magnetic field coils 447A, 447B,... 447L, and on each supply circuit from the DC power supply 448 to the magnetic field coils 447A, 447B,. Are mainly composed of a current regulator 449 and a programmable controller 450 that controls the current regulator 449 to adjust the amount of current supplied to each of the magnetic field coils 447A, 447B,.

When the film formation is performed using the cathode 2 shown in FIGS. 7 and 8, for example, the film formation rate in the peripheral part of the substrate 30 is lower than that in the central part, and the in-plane uniformity of the film thickness distribution is not sufficient. When the determination is made, control is performed so that the amount of current supplied to the magnetic field coil 447 wound around the eight auxiliary iron cores 451, 452, 453, 454, 455, 456, 457, 458 is relatively increased. For example, as the current regulator 449, a current regulator that can turn on and off the current in a predetermined cycle using a thyristor or the like is adopted, and the on / off cycle is adjusted by a signal from the programmable controller 450.
And compared with the ON period of the current to the four magnetic field coils 447 wound around the iron core body 441 shown in FIG. 7, the eight coils wound around the auxiliary iron core bodies 451, 452, 453, 454, 455, 456, 457, 458 The ON period of the current to the two magnetic field coils 447 is lengthened considerably. As a result, the magnetic flux density of the leakage magnetic field lines in the portions of the auxiliary iron core bodies 451, 452, 453, 454, 455, 456, 457, and 458 becomes relatively high, and the erosion in the peripheral portion of the target 5 is strengthened. The film forming speed in the peripheral portion of 30 is improved, and the in-plane uniformity of the film thickness distribution is improved.

Such independent control of the amount of supplied current may be independently controllable between groups of two electromagnets that set two circumferential magnetic fields, or may be independently controllable for all individual electromagnets. If independent control is possible for at least two groups, some sort of magnetic field distribution adjustment function is exhibited.
In the configuration of each embodiment described above, the number of circumferential magnetic fields is 2 or 3, but it may be 4 or more. Increasing the number of circumferential magnetic fields generally reduces the incident angle of sputtered particles at the same TS distance, which is preferable from the viewpoint of improving the bottom coverage ratio.

Further, the rotation mechanism 22 may rotate the target 5 instead of rotating the magnet mechanism 4. Further, the central axis 20 of the magnet mechanism 4 may be arranged eccentrically by a predetermined distance from the central axis of the target 5, and the magnet mechanism 4 may be rotated around the central axis of the target 5.
In addition, the “circumferential shape” in the present specification has the widest meaning and includes all shapes such as a circumferential shape, an elliptical circumferential shape, an elliptical circumferential shape, a rectangular circumferential shape, and a circumferential shape enveloping like a wavy line. . Moreover, it does not need to be a completely connected circumferential shape, and may be partially cut off. For example, even in the case of a circumferential magnetic field or a circumferential erosion region 50 with a part of the part, problems such as non-uniform film thickness due to the magnetic field may be less than the limit.

Further, the deepest erosion portion may not be linear but may have a band shape, that is, a considerable width. Further, the erosion deepest part may be from the deepest part to a considerably shallow part. The deepest erosion part is a concept for determining which part of the erosion region has the most influence on the film formation, and is therefore determined appropriately according to the degree of influence on the film formation.
Further, the erosion region is a place where substantial erosion occurs due to the action of a magnetic field. A very small number of ions that diffuse out of the erosion region and reach the substrate hit the target, so that a shallow erosion may occur over time outside the erosion region. Since it does not affect, it is judged that it is not substantial erosion. For example, assuming that the average erosion speed in the erosion region is 100, a region where erosion at a speed of 5% or less occurs is not substantially an erosion region.

Next, examples belonging to the first embodiment will be described as examples. In the first embodiment,
Target diameter: 314mm,
TS distance: 303mm,
Substrate diameter: 300 mm,
Pressure: 0.3 mTorr,
Supply voltage to the cathode: -600V,
Eccentric distance of the linear part of the N pole magnet (distance d in FIG. 2): 40 mm,
First erosion deepest part width (φ1 in FIG. 4): 200 mm,
Second erosion deepest part width (φ2 in FIG. 4): 100 mm,
Rotation speed of magnet mechanism: 200 rpm
Substrate temperature: 300 ° C.
Target material: Titanium,
Discharge gas: Argon,
As a result of sputtering under the above conditions, it was confirmed that film formation can be performed at a bottom coverage ratio of 40 to 45% with respect to minute holes having an aspect ratio of 2. At this time, the deposition rate was 1000 angstroms per minute.

It is a figure explaining the outline of the sputtering device which concerns on 1st embodiment of this invention. It is a figure explaining the structure of the cathode in the apparatus of FIG. 1, and is a schematic perspective view explaining the structure of a magnet mechanism. It is a figure explaining the structure of the cathode in the apparatus of FIG. 1, and is a schematic perspective view explaining the structure of the circumferential magnetic field on the target by a magnet mechanism. It is a figure explaining the effect of embodiment shown in FIGS. 1-3, and is sectional drawing in the XX direction of FIG. It is the figure explaining the relationship between the width | variety of each erosion deepest part with respect to TS distance, and an aspect-ratio. It is a perspective schematic diagram explaining the structure of the cathode in 2nd embodiment of this invention. It is a top view explaining 3rd embodiment of this invention. It is a sectional side view explaining 3rd embodiment of this invention. FIG. 9 is an explanatory diagram of an application example in which a current control unit for independently controlling a supply current to each magnetic field coil is added in the third embodiment shown in FIGS. 7 and 8. It is the figure explaining the outline of the collimated sputtering apparatus which is an example of the conventional sputtering apparatus which improved the bottom coverage rate. It is the figure explaining the outline of the low voltage | pressure remote sputtering apparatus which is another example of the conventional sputtering apparatus. It is the figure explaining the problem at the time of forming into a film on a large sized board | substrate using the apparatus shown in FIG. 11, and is a partial figure of the target and board | substrate in an apparatus. FIG. 13 is a diagram illustrating a problem in the case of forming a film on a large substrate using the apparatus shown in FIG. 11 as in FIG. 12, and is a cross-sectional view showing the bottom coverage ratio near the center of the substrate and in the peripheral portion. is there. The experimental data regarding a low-pressure remote sputtering is shown, and it is the data which shows the pressure and TS distance dependence of a bottom coverage rate. Similarly, it shows experimental data relating to low-pressure remote sputtering, and is data showing the pressure and TS distance dependence of the sheet resistance distribution of the obtained thin film. Similarly, it shows experimental data regarding low-pressure remote sputtering, and is data showing the relationship of the bottom coverage ratio to the aspect ratio when the TS distance is 340 mm. Similarly, experimental data regarding low-pressure remote sputtering is shown, and is a data showing the relationship of the bottom coverage ratio to the aspect ratio when the TS distance is 260 mm. It is a figure of the result of having examined about the influence which the enlargement of a board | substrate has on the bottom coverage rate and the film-forming rate. It is a figure explaining the point where the erosion deepest part becomes circumferential shape, and is a schematic perspective view of a magnet mechanism in a conventional apparatus. It is a figure explaining the point where the erosion deepest part becomes circumferential shape, and is a perspective schematic view of a cathode in a conventional device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 11 Exhaust system 2 Cathode 20 Center axis 22 Rotation mechanism 3 Substrate holder 30 Substrate 4 Magnet mechanism 5 Target 50 Erosion area

Claims (3)

A vacuum vessel provided with an exhaust system, a disk-shaped target arranged at a predetermined position in the vacuum vessel, and a magnet mechanism for setting a magnetic field on the surface side of the target, and a circular shape facing the target A sputtering apparatus in which a substrate is arranged in parallel on the same central axis, a target is sputtered while capturing electrons by a magnetic field created by the magnet mechanism, and a predetermined thin film is formed on the surface of the substrate,
The magnet mechanism sets a leakage magnetic field line that exits from a place on the surface of the target and enters another place on the surface of the target, and has a circumferential shape formed by continuously connecting the leakage magnetic field lines on the surface of the target. In a sputtering apparatus in which a magnetic field is set, and an erosion region that is circumferential when the magnet mechanism is stationary relative to the target is formed on the surface of the target by the circumferential magnetic field,
The magnet mechanism has a first magnetic pole magnet whose surface on the target side is the first magnetic pole, and a second magnetic pole magnet whose magnetic pole on the surface on the target side is a second magnetic pole different from the first magnetic pole. And
The first magnetic pole magnet, when viewed in a plane, includes a circumferential portion that extends along the periphery of the target and has a center on the center axis of the target, and a partition portion that partitions the inside of the circumferential portion. Is extended at a position off the central axis of the target and divides the inside of the circumference into two regions of different sizes,
The second magnetic pole magnets are respectively disposed in two regions in the circumferential portion defined by the partitioning portion of the first magnetic pole magnet,
A plurality of the circumferential magnetic fields are set on the surface of the target by the first magnetic pole magnet and each of the second magnetic pole magnets, and a plurality of circumferential erosion regions are formed so as not to intersect with each other. A sputtering apparatus characterized. The sputtering apparatus according to claim 1, wherein the substrate is disposed at a distance of 150 mm to 360 mm from the target. The sputtering apparatus according to claim 1, further comprising a rotation mechanism that rotates the magnet mechanism around a central axis of the target.

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