JP5613243B2 - Film forming apparatus and film forming method - Google Patents

Description

The present invention relates to a magnetron sputtering film forming apparatus and film forming method for forming a film on the surface of a substrate, and more particularly, to a magnetron sputtering device including a magnetic field forming means for forming a magnetic field that fluctuates at a constant period on the surface of a target BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus of a type and a film forming method using this apparatus.
This application claims priority on November 18, 2010 based on Japanese Patent Application No. 2010-257863 for which it applied to Japan, and uses the content here.

Conventionally, for example, a film forming apparatus using a sputtering method (hereinafter referred to as a “sputtering apparatus”) is used in a film forming process in manufacturing a semiconductor device.
There are various sputtering apparatuses depending on the voltage applied between the electrodes, the electrode structure, and the like. Among them, there is a magnetron sputtering apparatus. The magnetron sputtering apparatus has an advantage that the deposition rate can be increased and the productivity can be improved by arranging the sputtering cathode by arranging the magnetic field forming means on the back side of the target electrode where the target is arranged on the surface.

  Such magnetron sputtering apparatuses include a type that fixes the magnetic field and a type that changes the magnetic field at a constant period. Of these types, the magnetic field is changed for a reason that the film thickness distribution to be formed can be improved by improving the magnetic field at a constant period, and the use efficiency and life of the target can be improved. Things are mainly used.

  Magnetron sputtering devices that vary the magnetic field include a device that swings a magnet disposed on the back side of the target, and a device that rotates the magnet eccentrically about the center of the target (see, for example, Patent Document 1). ). In these apparatuses, the fluctuation period of the magnetic field is generally constant regardless of the film thickness formed on the substrate.

Japanese Unexamined Patent Publication No. 9-41137

  By the way, in recent sputtering apparatuses, in order to improve the performance of sputtering, the input power at the time of sputtering is increased. As a result, film formation can be performed in a shorter time, and throughput can be improved.

  In addition, in the sputtering apparatus for such applications, in the film forming process of LEDs, optical films, etc., the required film thickness is becoming thinner and it is strongly required that the film can be formed with good film thickness uniformity. .

  For example, in the case of the magnetron sputtering apparatus that rotates the magnet eccentrically as described above, it is preferable that the film formation time is sufficiently long with respect to the rotation period of the magnet in order to further improve the film thickness uniformity. However, since the film formation time is shortened as the film thickness is reduced and the input power is increased, there is a problem that the film formation time is not sufficient with respect to the rotation period of the magnet.

  For example, if the rotation period of the magnet is 1 second (60 rpm) while the sputter film formation time is 1.5 seconds, the magnet will make one and a half rotations during the sputter film formation time. In this case, the last 0.5 seconds of the sputter deposition time of 1.5 seconds causes the film thickness non-uniformity, and the film thickness distribution is greatly impaired. In other words, since the magnet rotates 540 ° in a sputter film formation time of 1.5 seconds, a non-uniform film thickness is formed in an extra rotation (180 °) with respect to 360 ° of one revolution.

  To solve this problem, a method of improving the film thickness distribution by further increasing the rotational speed of the magnet can be considered. However, there is a problem that increasing the rotation speed leads to an increase in power consumption of the film forming apparatus and a shortened life of the rotation apparatus.

  The present invention has been made in consideration of such circumstances, and its purpose is to make the film thickness uniform, to reduce the power consumption during sputtering, and to extend the life of the driving means for rotating the magnet. It is an object of the present invention to provide a film forming apparatus and a film forming method capable of realizing the above.

In order to achieve the above object, the present invention provides the following.
(1) One embodiment of the present invention includes a chamber in which a substrate on which a film is formed by sputtering film formation is disposed; a target including the film forming material disposed in the chamber; and a back surface of the target And a magnetic field forming device that forms a magnetic field that fluctuates at a constant period on the surface of the target; and the fluctuation period of the magnetic field for each different sputter deposition time required for forming a film having a desired film thickness. And a control device that changes the magnetic field fluctuation period to be an integral multiple of the fluctuation period of the magnetic field.

(2) In the film forming apparatus described in (1) above, the control device sets the fluctuation period of the magnetic field formed by the magnetic field forming device to sputter when the sputter film forming time is 1 second or more and less than 30 seconds. The film forming time may be controlled to be equal to the film forming time. When the sputter film forming time is not less than 30 seconds and less than 60 seconds, it is controlled to be half the sputter film forming time .
(3) In the film forming apparatus according to the above (1) or (2), the control device has a monitoring function for monitoring a delay in the rise of the sputter discharge, and senses the delay in the rise of the sputter discharge. In this case, control may be performed to delay the sputtering end time by the same time as the rise delay time of the sputtering discharge.

(4) According to another aspect of the present invention, there is provided a chamber in which a substrate on which a film is formed by sputtering film formation is disposed; a target including the film forming material disposed in the chamber; A magnetic field forming apparatus that is disposed on the back side and that forms a magnetic field that fluctuates at a constant period on the surface of the target, wherein the fluctuation period of the magnetic field is desired The magnetic field forming apparatus is controlled by changing it to an integral multiple of the fluctuation period of the magnetic field at every different sputtering film forming time required for forming a film having a thickness of.

(5) In the film formation method described in (4) above, the fluctuation period of the magnetic field is controlled to be equal to the sputter film formation time when the sputter film formation time is 1 second or more and less than 30 seconds. If the film time is 30 seconds or more and less than 60 seconds, control may be performed so that it is half the sputter film formation time .
(6) In the film forming method described in the above (4) or (5), when the delay in the rise of the sputter discharge is detected by monitoring the delay in the rise of the sputter discharge, The spatter discharge may be delayed for the same time as the rise delay time.

According to the aspect described in the above (1) or (4), in a film forming apparatus including a magnetic field forming apparatus that forms a magnetic field that fluctuates at a constant period on the surface of a target, a film having a desired film thickness is formed. The film thickness distribution can be made more uniform by providing a control device that performs control for determining the fluctuation period so that the required sputter deposition time is an integral multiple of the fluctuation period of the magnetic field.
In the case of (2) or (5) above, the magnetic field forming device includes a magnet arranged eccentric from the center of the target, and a drive device that rotates the magnet around the center of the target. In this case, since the rotational speed of the magnet is reduced, power consumption can be suppressed and the life of the apparatus can be extended.

  Furthermore, in the case of the above (3) or (6), it has a monitoring function. In this case, even if the rise of the sputter discharge is delayed, the sputter deposition time does not change, so the delay of the rise of the sputter discharge does not affect the film thickness distribution.

It is a schematic sectional drawing of the film-forming apparatus of this invention. It is a top view of the permanent magnet which follows the AA line of FIG. It is a figure which shows the film thickness measurement point on a board | substrate. It is a graph which shows the relationship between sputter | spatter film-forming time and a rotational speed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made based on the technical idea of the present invention.

(Sputtering equipment)
FIG. 1 is a schematic cross-sectional view of a sputtering apparatus 1 (film forming apparatus) according to this embodiment. In the present embodiment, the sputtering apparatus 1 is configured as a magnetron sputtering apparatus. The sputtering apparatus 1 includes a vacuum chamber 2 capable of hermetically sealing the inside, a substrate support 3 disposed inside the vacuum chamber 2, a sputtering cathode 4 and the like.

  The vacuum chamber 2 defines a processing chamber 5 therein, and the processing chamber 5 can be depressurized to a predetermined degree of vacuum via a vacuum exhaust unit (not shown). Further, a gas introduction nozzle (not shown) for introducing a process gas such as argon gas or a reactive gas such as oxygen or nitrogen is attached to a predetermined position of the vacuum chamber 2 inside the processing chamber 5.

  The substrate support 3 (also referred to as a stage) is configured to be able to heat the substrate W placed on the substrate support 3 to a predetermined temperature using a temperature adjusting means (not shown). The substrate W is fixed to the substrate support 3 by, for example, an electrostatic chuck.

  The sputtering cathode 4 includes a target electrode 7 attached to the upper portion of the chamber 2 via an insulating ring 6, a magnetic field forming device 8 (magnetic field forming means) provided on the back side of the target electrode 7, and the like. The target electrode 7 is made of any material such as Cu, Al, Ti, Ta, and a magnetic material (Ni, Co) formed on the substrate W so as to face the lower surface of the target electrode 7 in parallel with the substrate W. The target 9 is mounted. The target electrode 7 is connected to the negative electrode of the DC power supply 15.

  The magnetic field forming device 8 includes a magnet support base 10, a permanent magnet 11 fixed to the magnet support base 10, and a drive unit 13 such as a motor that rotates the magnet support base 10 via a rotating shaft 12. . The rotary shaft 12 is provided so that the axis center of the rotary shaft 12 coincides with the center of the target 9, whereby the magnet support 10 and the permanent magnet 11 can be rotated about the center of the target 9. ing.

  The magnetic field forming device 8 is configured such that the magnetic flux F leaks on the surface of the target 9 and can form a magnetic field of a desired shape. As shown in FIG. 2, the permanent magnet 11 includes ring-shaped magnets 11a and 11b having different sizes. The centers of the magnets 11a and 11b are eccentric from the center of the target. In addition, the magnet 11 is configured so that the outer side is the N pole and the inner side is the S pole. However, the absolute value of the magnetic field strength on the surface of the target 9 is a problem. A magnet can also be comprised so that it may become N pole.

  The magnetic field forming device 8, the drive unit 13, and the like constituting the sputtering apparatus 1 are controlled by a control device 14 (control unit). For example, the control device 14 can rotate the rotating shaft 4 at a predetermined rotation speed. That is, the user can rotate the magnet 11 fixed to the magnet support 10 at a desired rotation speed S (rpm) and rotation cycle P (seconds).

Further, the control device 14 has a function of calculating the sputter film formation time T (seconds) from the sputter film formation speed determined by the specifications of the sputtering apparatus 1 and the film thickness desired by the user.
Further, the control device 14 has a function of determining the rotation period P according to the calculated sputter deposition time T. Here, the rotation period P is the time (seconds) required for the magnet support base 10 to make one rotation. When the rotation speed of the magnet support base 10 is Srpm (rotations / minute), P = 60 / S. The value to be calculated.

The control device 14 controls the sputter film formation time T to be an integral multiple of the rotation period P.
That is, when the sputter deposition time is T, the rotation period P is calculated as in the following formula 1. n represents an integer.
T = n × P (Formula 1)
That is, the rotation period P is calculated by the following formula 2.
P = (1 / n) × T (Expression 2)
The magnet support base 10 (permanent magnet 11) is controlled during the sputter deposition time T by performing control to rotate the magnet support base 10 at the rotational speed S so that the rotational period P calculated by such a method is obtained. N turns exactly.

  In other words, during the sputter deposition time T, the rotation period P (rotation speed S) is determined so that the magnet support 10 rotates accurately (360 × n) ° at a constant speed. As a matter of course, the time during which sputter film formation is performed (sputter film formation time T) is also accurately controlled.

In consideration of the power consumption, the life of the driving means 13, and the problem of eddy current generated in the target material, it is preferable that the rotation speed S is slow (the rotation period P is long). That is, n is preferably a small integer.
However, if the rotation period P is too long, that is, the rotation speed S becomes too slow, problems such as film thickness uniformity and drive motor vibration occur. Therefore, the longest rotation period Pmax (minimum rotation speed) is set. It is preferable to keep it. When the calculated rotation period P is less than the longest rotation period Pmax, recalculation is performed so as not to exceed the longest rotation period Pmax by sequentially increasing the value of n in the above calculation formula.

  On the other hand, it is preferable to set the shortest rotation period Pmin (maximum rotation speed) so as to avoid vibration of the driving means 13 and local temperature increase of the target. Even when n = 1, if a rotation period P lower than the shortest rotation period Pmin is calculated, a warning is displayed on a display device (not shown), and then processing is performed with the shortest rotation period Pmin.

In addition, when the sputter deposition time T can be predicted to some extent, a method may be used in which the number of rotations with respect to the sputter deposition time T (integer n in the above formula) is determined in advance.
For example, if the sputter deposition time T can be predicted to be 60 seconds or less, and if the sputter deposition time is 1 second or more and less than 30 seconds, the magnet support 10 is rotated once during the sputter deposition time T. Determine to control. Further, when the sputter deposition time T is not less than 30 seconds and not more than 60 seconds, the sputter deposition time T is determined to be controlled so that the magnet support 10 is rotated twice. By preparing such a data table, the rotation period P (rotational speed S) can be calculated more easily.

  For example, in the case of the data table as described above, when the sputter deposition time T is calculated to be 50 seconds, control is performed so that the magnet support 10 is rotated twice. That is, the rotation period P is calculated as (50 seconds / 2 rotations = 25 seconds).

  The control device 14 has a monitoring function for mainly controlling the sputtering time. The control device 14 determines the sputter deposition time T in the process as described above, and outputs a sputter start command and a sputter end command in accordance with the sputter deposition time T. The voltage during discharge is constantly monitored.

  The monitoring function monitors the time from when the sputter start command is output until the sputter discharge is actually started. For example, when the start of the sputter discharge is delayed by d seconds, the sputter end command is delayed by d seconds. The sputter deposition time T is controlled so as not to change. The sputtering discharge is monitored by detecting the actual output of the sputtering power source at the sputtering power source internal voltage measuring unit and taking it into the PC of the control device 14 via the analog input board. Here, a non-negligible time lag (for example, 0.5 seconds) may occur between the time until the actual output of the sputtering power source is taken into the PC and the time until the output of the PC is reflected in the actual output of the sputtering power source. When the measurement period of the control device is slow, the sputtering time becomes long. Since the time lag is substantially constant, it suffices to stop the sputtering earlier by a time considering a constant value of the time lag.

According to this embodiment, the controller 14 forms the substrate W by controlling the rotational speed S of the magnet support 11 so that the sputter deposition time T is an integral multiple of the rotational period P of the magnet 11. The film thickness distribution of the film to be formed can be made more uniform.
Moreover, since the rotational speed S of the magnet support base 11 is reduced as compared with the conventional sputtering apparatus, the power consumption can be suppressed and the lifetime of the sputtering apparatus 1 can be increased.

  Furthermore, since the monitoring function of the control device 14 performs control so that the sputter deposition time T does not change even when the rise of the sputter discharge is delayed, the delay in the rise of the sputter discharge affects the film thickness distribution. There is nothing.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to these Examples.

<Example>
In the example, a Ti film was formed using the sputtering apparatus 1 shown in FIG. As the substrate W, a φ200 mm Si wafer was used. A target having a Ti composition ratio of 99% and a sputter surface diameter of 300 mm was used. The thickness of the Ti film to be formed was 14 nm to 21 nm. The sputtering speed of the sputtering apparatus 1 is 7.0 nm / second.

Further, the film thickness distribution d [%] was measured after the film formation. The film thickness distribution d is calculated from the following equation 3 when the film thickness at nine points on the substrate W as shown in FIG. 3 is measured after film formation, and the maximum value of the film thickness is Fmax and the minimum value is Fmin. Value.
d [%] = (Fmax−Fmin) / (Fmax + Fmin) × 100 Expression 3

  Table 1 shows the results.

  In Table 1, for example, when the required film thickness is 14 nm, the sputtering film formation time T is (14 nm / 7.0 nm / second =) 2.0 seconds from the sputtering speed (7.0 nm / second) of the sputtering apparatus 1. calculated. If the magnet support 10 is rotated once in 2.0 seconds, the rotation period P is ((1/1) × 2.0 =) 2.0 seconds (30 rpm) from P = (1 / n) × T. )

  When the film was formed under these conditions, the film thickness distribution was 4.1% because the magnet support 10 rotated exactly once in a film formation time of 2.0 seconds. Similarly, the required film thickness was changed from 15.4 nm to 21 nm, and the film was formed by controlling the rotation speed S in accordance with the sputtering film formation time T that varies depending on the required film thickness. The distribution was between 3.9% and 4.1%.

<Comparative example>
The film formation was performed in the same manner as in the example except that the rotation speed S (rotation period P) was not controlled. The rotation speed was 60 rpm (the rotation period P was 1 second). Table 2 shows the results.

From Table 2, when the required film thicknesses were 14.0 nm and 21.0 nm, the film thickness distribution was good because the sputter film formation time T was an integral multiple of the rotation period P (1 second). (4.0%, 3.9%). On the other hand, in the case of the required film thicknesses of 2.2 nm, 2.4 nm, 2.6 nm, and 2.8 nm that deviate from an integral multiple of the rotation period, the film thickness distribution deteriorated ( 5.3% to 6.3%).
For example, in the case of a required film thickness of 16.8 nm requiring a film formation time of 2.4 seconds, the film formed during the 0.4 second from the start of sputtering film formation to 2.0 seconds until the end of sputtering film thickness It seems to be a factor of the distribution deterioration.

  FIG. 4 is a graph in which the film thickness distribution (vertical axis) is plotted against the sputter deposition time T (horizontal axis). When comparing the example and the comparative example with reference to FIG. 4, the film thickness distribution of the example shows a high uniformity, whereas the film thickness distribution of the comparative example shows a film formation time of 2 The uniformity is low in the range of 2 seconds to 2.8 seconds. This is because the film formation time is not an integral multiple of the rotation period (1 second) while the rotation period of the magnet of the sputtering apparatus used in the comparative example is 1 second. it is conceivable that. In particular, it can be seen that the film thickness distribution deteriorates as the difference from the film formation time of 2 or 3 seconds, which is an integral multiple of the rotation period, increases.

The magnetic field forming device 8 is not limited to the rotary type as described above, and may be any device that can change the magnetic field at a constant period. For example, an oscillating magnetron sputtering apparatus that oscillates the magnet structure can be employed.
Moreover, as a magnet which comprises a magnetic field formation means, you may employ | adopt an electromagnet instead of a permanent magnet. In this case, the film thickness distribution is controlled by controlling the fluctuation period X so that the sputter deposition time T is an integral multiple of the reciprocal (1 / X) of the fluctuation period X (Hz) of the magnetic field formed by the electromagnet. Can be made uniform.
Further, when the electromagnet is arranged not on the cathode side but on the stage or the side surface of the vacuum chamber, the film thickness distribution can be improved by adjusting the period in the same manner.

  According to the present invention, the film thickness can be made uniform, power consumption during sputtering can be suppressed, and the life of the driving means for rotating the magnet can be realized.

F magnetic flux
P Rotation cycle
S Rotational speed W Substrate 1 Sputtering device (film forming device)
2 Vacuum chamber (chamber)
3 Substrate support 4 Sputtering cathode 5 Processing chamber 6 Insulating ring 7 Target electrode 8 Magnetic field forming device 9 Target 10 Magnet support 11 Permanent magnet 12 Rotating shaft 13 Driving means 14 Control device.

Claims (6)

A chamber in which a substrate on which a film is formed by sputter deposition is disposed;
A target disposed within the chamber and comprising the film-forming material;
A magnetic field forming device that is arranged on the back side of the target and forms a magnetic field that fluctuates at a constant period on the surface of the target;
A control device that changes the fluctuation period of the magnetic field so as to be an integral multiple of the fluctuation period of the magnetic field for each different sputtering film formation time required for forming a film having a desired film thickness;
A film forming apparatus comprising: The control device controls the fluctuation period of the magnetic field formed by the magnetic field forming device to be equal to the sputter film formation time when the sputter film formation time is 1 second or more and less than 30 seconds, and the sputter film formation time is 30. If it is not less than 60 seconds and not more than 60 seconds, it is controlled to be half the sputter deposition time ;
The film forming apparatus according to claim 1. The control device has a monitoring function for monitoring a delay in the rise of the sputter discharge, and when the delay in the rise of the sputter discharge is detected, the sputter end time is set to the same time as the rise delay time of the sputter discharge. The film forming apparatus according to claim 1, wherein a delaying control is performed. A chamber in which a substrate on which a film is formed by sputter deposition is disposed;
A target disposed within the chamber and comprising the film-forming material;
A magnetic field forming device that is arranged on the back side of the target and forms a magnetic field that fluctuates at a constant period on the surface of the target;
A film forming method using a film forming apparatus comprising:
The magnetic field fluctuation device is controlled by changing the magnetic field fluctuation period to be an integral multiple of the magnetic field fluctuation period for each different sputtering film formation time required for forming a film having a desired film thickness. A film forming method. The fluctuation period of the magnetic field is controlled to be equal to the sputter film formation time when the sputter film formation time is 1 second or more and less than 30 seconds, and when the sputter film formation time is 30 seconds or more and 60 seconds or less, the sputter film formation time is controlled. Control to be half the membrane time ;
The film forming method according to claim 4.   5. The sputter end time is delayed by the same time as the spatter discharge rise delay time when the sputter discharge rise delay is detected by monitoring the spatter discharge rise delay. Or the film-forming method of 5.

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