JP2010229495A - Film deposition system and film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition system and a film deposition method by which the reproducibility of the film deposition rate and the film deposition thickness of a thin film deposited is improved in a high precision. <P>SOLUTION: The film deposition system 1 for performing film deposition on a substrate 100 by using a target 101 includes: a material mounting part 4 for mounting the target 101 thereon; a substrate holder 3 for allowing the substrate 100 to face to the target 101; a shutter 5 provided between the material mounting part 4 and the substrate holder 3; a first sensor 6A which is arranged in the vicinity of the substrate holder 3 and measures film deposition rate and the film deposition thickness of a thin film deposited on the substrate 100; a sensor part 6 including a second sensor 6B arranged between the material mounting part 4 and the shutter 5; and a control part 7 for controlling the film deposition rate and the film deposition thickness of the thin film. The control part 7 performs control based on the second sensor 6B immediately after the shutter 5 is retreated and performs control based on the first sensor 6A after the first sensor 6A is stabilized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a film forming apparatus and a film forming method for forming a thin film.

  When forming a film on the surface of an object such as a substrate using a film forming apparatus, it is important to ensure the reproducibility of the film thickness, which is the thickness of the film deposited by film formation. In order to improve reproducibility, it has been proposed to improve the reproducibility of film thickness by feedback control using sensors that detect values such as film deposition speed and film thickness of the actually formed thin film. ing.

  For example, in Patent Document 1, in a vapor deposition apparatus that irradiates a vapor deposition raw material with an electron beam to form a film on a target object, a shutter and a vapor deposition material provided so as to be retractable between the target object and the vapor deposition material. A vapor deposition apparatus is proposed in which a second film thickness monitor is disposed between the two.

In this vapor deposition apparatus, when the shutter is in a closed state that shields between the vapor deposition material and the object to be processed, the power of the electron gun that irradiates the electron beam is controlled based on the signal of the second film thickness monitor. . The control is switched to the control based on the signal of the first film thickness monitor disposed in the vicinity of the object to be processed after a while after the shutter is in the retracted open state.
Thereby, the film forming speed can be stabilized even when the detection value of the first film thickness monitor is unstable and the shutter is in the open state.

JP 2003-328115 A

  However, although the deposition rate of Patent Document 1 can stabilize the deposition rate, there is a problem that the unstable state is not resolved for the deposition thickness value output by the first thickness monitor. .

FIG. 4 is a graph showing the transition of the output value of the film forming speed of the first film thickness monitor in the film forming apparatus having the same configuration as that of Patent Document 1. By controlling the film formation speed using the second film thickness monitor, the film formation speed is already stabilized at 1 nanometer per second (nm / sec) at the start of film formation when the shutter is retracted. Thus, it can be seen that a certain time (about 5 seconds in the graph of FIG. 4) is required until the film formation rate value output from the first film thickness monitor is stabilized.
This is because the film thickness value detected by the first film thickness monitor is unstable at the start of film formation when the shutter is retracted and film formation starts on the first film thickness monitor. (The film forming speed is calculated from the time change of the film forming thickness.) Therefore, the film forming thickness value detected by the first film thickness monitor is the film forming thickness actually formed on the target object such as the substrate. Is a different value.
FIG. 5 is a graph showing the film thickness value output by the first film thickness monitor. As described above, since the film formation rate is already stabilized at 1 nm / sec, the actual film thickness at the time when 5 seconds have elapsed since the start of film formation is approximately 5 nm, but as shown in FIG. The film thickness value output from the first film thickness monitor cannot accurately reflect this. As described above, it is not easy to improve the accuracy of the film thickness value for which reproducibility is finally improved.

  Further, the time required until the film formation rate value of the first film thickness monitor shown in FIG. 4 is stabilized is not the same every time, but varies depending on the film formation conditions, the state inside the vacuum chamber, and the like. Therefore, when a predetermined time (for example, 5 seconds) elapses from the start of film formation when the shutter is retracted, the detection value used for controlling the film formation speed is changed from that of the second film thickness monitor to that of the first film thickness monitor. When it is set to switch to one, the detection value of the first film thickness monitor may not be stable at that time. In this case, since film formation is controlled based on an inaccurate detection value of the first film thickness monitor, the accuracy of film thickness control is further lowered, which is a problem.

  In addition, when the detection value used for film formation control is switched from the second film thickness monitor to the first film thickness monitor, it may be a while after the detection value of the first film thickness monitor is sufficiently stabilized. It is possible. In this case, if the first film thickness monitor is sufficiently stable, it is more accurate to switch to the first film thickness monitor that can detect the film thickness on the object to be processed more accurately and control the film formation as soon as possible. Although control can be performed for a long time, the control is performed using the second film thickness monitor for a long time, so that the accuracy of control decreases.

  The present invention has been made in view of the above circumstances, and provides a film forming apparatus and a film forming method capable of improving the film forming speed and the reproducibility of the film thickness of a formed thin film with high accuracy. With the goal.

  A first aspect of the present invention is a film forming apparatus that forms a film on a surface of an object using a film forming material, the material setting unit on which the film forming material is placed, and the object An object support unit that supports the film forming material placed on the material installation unit so as to oppose, and the material installation unit and the object support unit between the material installation unit and the object support unit, A first sensor capable of measuring a film forming speed and a film thickness of a thin film formed on the object; A sensor unit having a second sensor disposed between the material setting unit and the shutter; and a control unit configured to be able to control the film formation speed and the film thickness based on the measurement result of the sensor unit; And the control unit sets the output value of the second sensor immediately after retracting the shutter. Then, the film formation speed is controlled, and the film formation speed is controlled based on the output value of the first sensor after the output value of the first sensor is stabilized, and the shutter is retracted. The output value of the second sensor is adopted as the initial film formation thickness until the start of the film formation speed control based on the output value of the first sensor, and the initial film formation thickness is based on the output value of the first sensor. The film thickness is controlled based on a total film thickness value obtained by integrating the output values of the film thickness of the first sensor after the start of control.

  According to the film forming apparatus of the present invention, the output value is stable rather than the film thickness value of the first sensor having low reliability until the output of the first sensor is stabilized after the shutter is retracted. The film thickness value of the second sensor is adopted as the initial film thickness, and the film thickness value of the first sensor after the stabilization of the first sensor is added to this to obtain the total film thickness value, so that it is more accurate. A suitable film thickness value is obtained.

  The control unit may include a determination unit that automatically determines a control start timing based on an output value of the first sensor based on a predetermined condition. In this case, the control output source can be switched to the first sensor that reflects the deposition speed and deposition thickness of the surface of the object more accurately at an earlier timing, and deposition can be performed with higher accuracy.

  A second aspect of the present invention is a film forming method for forming a film on the surface of an object using a film forming material, wherein the film forming material and the object are shielded by a shutter, A preliminary step of stabilizing a film forming speed by feedback control using a shutter side sensor disposed between the shutter and the film forming material; and the target while continuing the feedback control after retracting the shutter. A film forming step of forming a thin film made of the film forming material on the surface of the object, and an output source for feedback control of the film forming speed in the film forming step are arranged in the vicinity of the object from the shutter side sensor, A switching step of switching to an object-side sensor capable of measuring the film forming speed and film forming thickness of the thin film formed on the object, and the film forming thickness of the thin film on the surface of the object within a predetermined range System The film thickness of the thin film formed from when the shutter is retracted until the output source is switched to the object side sensor in the switching step. The film thickness obtained based on the output value of the shutter side sensor as the film thickness and the film thickness of the thin film formed after the output source is switched to the object side sensor is the output value of the object side sensor. Based on the initial film thickness, the total film thickness value of the thin film is obtained, and in the film thickness control step, the film thickness of the thin film is calculated based on the total film thickness value. It is controlled.

  In the film-forming method of this invention, it further has the determination process which determines whether the output value of the said object side sensor was stabilized based on predetermined conditions, and the output value of the said object side sensor is the said determination process. The switching step may be executed when it is determined to be stable.

  According to the film forming apparatus and the film forming method of the present invention, the reproducibility of the film forming speed and the film forming thickness of the formed thin film can be improved with high accuracy.

It is a figure which shows the structure of the film-forming apparatus of 1st Embodiment of this invention. It is a flowchart which shows the flow of the film-forming method using the film-forming apparatus. It is a table | surface which shows the result of having formed into multiple times in the Example and comparative example of the film-forming apparatus. It is a graph which shows transition of the film-forming speed value which the 1st film thickness monitor near the film-forming target object in the conventional film-forming apparatus outputs. It is a graph which shows transition of the film thickness value which the 1st film thickness monitor outputs.

A film forming apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a film forming apparatus 1 of the present embodiment.
The film formation apparatus 1 is an apparatus for performing film formation by sputtering, and is provided with a vacuum chamber 2 and a substrate holder (target) that is provided above the inside of the vacuum chamber 2 and holds a substrate 100 that is an example of a film formation target. Object support unit 3, a material installation unit 4 provided in the lower part inside the vacuum chamber 2, a shutter 5 provided between the substrate holding unit 3 and the material installation unit 4, a film formation speed and a film formation thickness. And a control unit 7 for controlling the film forming speed and the film thickness in the film forming apparatus 1 within a predetermined range based on the detection value of the sensor unit 6. Has been.

  A discharge gas introduction port 8 is formed on the side surface of the vacuum chamber 2. The flow rate of the discharge gas is controlled by the mass flow controller 19, thereby controlling the gas pressure in the vacuum chamber 2.

  The substrate holder 3 is configured to be rotatable about a rotation shaft 9, and a substrate 100 that is a film formation target is installed on the lower surface of the substrate holder 3 (the side facing the material installation unit 4). . The rotating shaft 9 is connected to a driving source such as a motor (not shown), and the substrate holder 3 can be rotated around the rotating shaft 9.

The material placement unit 4 has a known configuration including a backing plate 10 on which a film forming material is placed and a magnetron cathode 11 provided below the backing plate 10. On the backing plate 10, a target (film forming material) 101 of an appropriately selected material is placed. In the present embodiment, as an example, granules having a particle diameter of 0.1 to 10 millimeters (mm) of magnesium fluoride (MgF ₂ ) are used as the target 101, and are backed up in a state where the quartz dish 12 is filled. It is placed on the plate 10.
A power source 13 is connected to the magnetron cathode 11, and a thin film made of the material of the target 101 can be formed on the surface of the substrate 100 by applying a voltage from the power source 13 to the magnetron cathode 11.

  The shutter 5 is supported and fixed to a rotating shaft 14 provided at the lower part of the vacuum chamber 2 so as to be rotatable around its axis. The shutter 5 shields between the target 101 and the substrate 100 until the film formation environment such as the film formation speed is stabilized, and controls the film formation on the substrate 100 not to be performed. The rotation shaft 14 is connected to a drive unit 15 having a known configuration such as a motor, and the drive unit 15 rotates the rotation shaft 14 to retract the shutter 5 from between the substrate 100 and the target 101. It is possible.

  The sensor unit 6 includes two crystal sensors, a first sensor (object side sensor) 6A and a second sensor (shutter side sensor) 6B. The first sensor 6A is installed in the vicinity of the substrate holder 3, and can calculate and output the film formation speed from the temporal change of the film formation thickness. On the other hand, the second sensor 6B is disposed between the shutter 5 and the target 101 and is supported by the vacuum chamber 2 at a position near the shutter 5. Since the sensors 6A and 6B have different positions, the film thicknesses actually deposited on the sensors 6A and 6B are different, but the sensor 6B and the sensor 6A are displayed to be equal to the film thickness of the substrate 100, respectively. The display value is corrected. Each sensor 6 </ b> A, 6 </ b> B is connected to the control unit 7.

  The control unit 7 includes a control unit main body 16 that controls the entire film forming apparatus 1, a switching unit 17 that switches an output source to be subjected to feedback control between the first sensor 6 </ b> A and the second sensor 6 </ b> B, and a switching unit 17. And a determination unit 18 for determining the switching timing.

  The control unit main body 16 is connected to the power source 13, the drive unit 15, and the mass flow controller 19, and can control these outputs. The control unit body 16 includes an input mechanism (not shown) so that the user can input a target film formation speed, a set film formation thickness, and the like.

An operation at the time of use of the film forming apparatus 1 configured as described above will be described.
FIG. 2 is a flowchart showing the flow of the film forming method of the present embodiment using the film forming apparatus 1. The film forming method of this embodiment includes a preliminary process S10 for stabilizing the film forming speed before the start of film forming, a film forming process S20 for forming a thin film on the surface of the object, A determination step S30 for determining whether the output of one sensor 6A is stable, and a switching step S40 for switching the output source of the feedback control when it is determined that the output of the first sensor 6A is stable in the determination step S30. And a film thickness control step S50 for controlling the film thickness on the surface of the object within a predetermined range.

  First, as a preparation before film formation, the user places the substrate 100 on the substrate holder 3 and places the target 101 on the backing plate 10. At this time, the shutter 5 is positioned so as to shield between the substrate 100 and the target 101 (hereinafter, the position of the shutter 5 is referred to as a “closed position”). Then, the vacuum chamber 2 is evacuated by an evacuation unit (not shown), and the vacuum chamber 2 is evacuated.

  Subsequently, after the reaction gas is introduced from the introduction port 8, power is applied from the power source 13 to the magnetron cathode 11 to generate the plasma 20. The target 101 is heated by the generated plasma 20 and simultaneously sputtered by the reactive gas ions in the plasma 20 to start scattering into the vacuum chamber 2. At this point, the preparation for film formation is completed, and the process proceeds to the preliminary process in step S10.

In step S10, the control unit main body 16 performs feedback control of the power supply amount of the power supply 13 so that the film forming speed becomes a desired speed, for example, 1.0 nm / sec with the shutter 5 in the closed position. At this time, the control unit main body 16 is set to adopt the output value of the second sensor 6B as an output source for feedback.
The desired film formation speed is previously input to the control unit main body 16 by the user via the input mechanism. Further, if necessary, pre-sputtering may be performed for a predetermined time in step S10.

  When the film formation speed value measured by the second sensor 6B is stabilized within a desired range, the process proceeds to the film formation process in step S20, and the control unit body 16 rotates the rotation shaft 14 via the drive unit 15. Thus, the shutter 5 is retracted from between the substrate 100 and the target 101, the rotating shaft 9 is rotated via a driving source (not shown), and the substrate holder 3 is rotated around the rotating shaft 9. As a result, the target 101 starts to adhere to the surface of the substrate 100 and film formation on the substrate 100 is started. The film thickness that adheres to the second sensor 6B from the time when the shutter 5 is retracted is counted by the second sensor 6B. Accordingly, the film formation on the first sensor 6A is started and the measurement by the first sensor 6A is started. At the initial stage of step S20, the control unit body 16 outputs the output of the second sensor 6B in the same manner as in step S10. Based on the value, the feedback control of the power source 13 is continued.

While continuing the film forming step S20, in the determination step of step S30, it is determined whether the source of the output value used for feedback control can be switched to the first sensor 6A closer to the substrate 100. Specifically, the determination unit 18 determines whether or not the output value of the first sensor 6A is stabilized within a predetermined range including a desired film formation speed based on the output value of the first sensor 6A.
The determination criterion as to whether or not it is stable may be set by the user as appropriate depending on the required accuracy of the film thickness and the type of film formation target. In this embodiment, as an example, when the output value is 1.0 nm / sec plus or minus 5% in four consecutive samplings of the first sensor 6A performed every 250 milliseconds (msec). The determination unit 18 is set to determine that the output of the first sensor 6A is stable (“Yes”).
The determination unit 18 repeats the determination step S30 until the determination is “Yes”. When the determination is “Yes”, the process proceeds to step S40.

  In step S40, upon receiving a Yes determination from the determination unit 18, the output source of the feedback control is switched from the second sensor 6B to the first sensor 6A. Thereafter, the feedback of the power source 13 is performed based on the deposition rate value output from the first sensor 6A.

  In step S40, the film thickness value is adjusted in parallel with the switching of the output source. First, based on the output value of the second sensor 6B, the control unit main body 16 takes out the film thickness value during the time from when the shutter 5 is retracted until the output source is switched as the initial film thickness. Then, the total film thickness after the start of film formation is obtained by accumulating the film thickness after switching the output source to the initial film thickness based on the output value of the first sensor 6A. The film thickness on the substrate 100 is monitored based on the film thickness value.

In step S50, it is determined by the control unit main body 16 based on the total film thickness value described above whether the film thickness on the substrate 100 has reached a desired value. If this determination is “No”, the film formation is continued. When “Yes” is determined, the control unit main body 16 cuts off the power supply to the magnetron cathode 11 by the power source 13 and rotates the rotating shaft 14. The shutter 5 is returned to the closed position to finish the film formation.
The film forming apparatus 1 described above will be further described using examples and comparative examples.

(Example)
A substrate 100 made of optical glass (trade name S-BSL7: manufactured by OHARA INC.) Was used and attached to the substrate holder 3. As the target 101, MgF ₂ granules having a particle size of 0.1 to 10 mm were used. Thereafter, the atmosphere in the vacuum chamber 2 was evacuated to 1 × 10 ⁻⁴ Pascal (Pa) by a vacuum pump (not shown). At this time, the substrate 100 was not heated.

Thereafter, O ₂ gas as a discharge gas was introduced into the vacuum chamber 2 from the introduction port 8 while controlling the flow rate by the mass flow controller 19, and the gas pressure was adjusted to 4 × 10 ⁻¹ Pa. Then, high frequency power was supplied from the power source 13 to the magnetron cathode 11 to generate plasma 20.

  The set film formation rate was 1.0 nm / sec, and the film thickness of the thin film to be formed was set to 100 nm. The determination standard for the output value stabilization of the first sensor 6A is the case where the output value is 1.0 nm / sec plus or minus 5% in all four consecutive samplings, as described above.

(Comparative example)
The substrate 100 and the target 101 were the same as those in the example. The output source is always switched after 10 seconds have elapsed after the shutter 5 is retracted, and the determination unit 18 does not determine whether the output value of the first sensor 6A has stabilized. As the film thickness value, the integrated value of the first sensor 6A was used as it was. The set film formation speed and the film thickness of the thin film to be formed were the same as in the example.

  FIG. 3 shows the results of film formation performed 10 times in each of the example and the comparative example. In the example, the film thickness was kept in the range of plus or minus 0.1% of the set film thickness after 10 film formations, and the film thickness could be controlled with extremely high accuracy. On the other hand, in the comparative example, the range of the film thickness in the 10 film formations was in the range of plus or minus 2.5% of the set film thickness, and the accuracy was lower than in the example.

  According to the film forming apparatus 1 of the present embodiment, when the output source of the feedback control is switched from the second sensor 6B to the first sensor 6A in the switching step S40, the film formation is performed as the film thickness value that has been formed so far. The output value of the second sensor 6B whose output value is already stable at the start is taken out as the initial film thickness. Then, the film thickness value of the first sensor 6A after switching the output source is integrated to obtain the total film thickness value. Therefore, since the total film thickness value can be obtained by eliminating the initial film thickness value of the first sensor 6A based on the unstable output immediately after the start of film formation, more accurate film thickness control is performed. be able to.

  Further, in the determination step S30, the determination unit 18 automatically determines the timing for performing the switching step S40 based on the output value of the first sensor 6A, so that it changes slightly depending on the film forming conditions and the state inside the vacuum chamber 2. It is possible to accurately detect the output stabilization timing of the first sensor 6A. As a result, the output source is switched to the first sensor 6A that more accurately reflects the film formation state of the substrate 100 at an earlier timing while preventing the output source from being switched before the output of the first sensor 6A is stabilized. Thus, the film thickness value can be acquired and the film formation speed feedback control can be performed, so that the film thickness can be controlled with higher accuracy. .

Although one embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in each of the above-described embodiments, an example of a film forming apparatus that forms a film by sputtering has been described. However, the present invention can also be applied to a film forming apparatus that forms a film by another method such as an evaporation method. .

Further, the film forming material is not limited to the above-mentioned MgF _2, and various materials such as metals, metal compounds, and ceramics can be appropriately selected. Further, the shape is not limited to the granule, and various shapes such as a plate shape and a powder shape may be appropriately selected.

  In the above-described embodiment, an example in which the sensor unit 6 is configured by a quartz sensor has been described. However, an optical film thickness sensor may be used instead of the quartz sensor. Further, the sensor unit may be configured by appropriately combining these sensors, such as monitoring the deposition rate with a quartz sensor and monitoring the deposition thickness with an optical sensor.

  In the above-described embodiment, the switching unit 17 and the determination unit 18 are separately arranged outside the control unit main body 16. However, the switching unit 17 and the determination unit 18 are incorporated in the control unit main body 16 and integrated. It may be.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 3 Object support part 4 Material installation part 5 Shutter 6 Sensor part 6A 1st sensor (object side sensor)
6B Second sensor (shutter side sensor)
7 Control Unit 18 Determination Unit S10 Preliminary Process S20 Film Formation Process S30 Determination Process S40 Switching Process S50 Film Thickness Control Process

Claims (4)

A film forming apparatus for forming a film on the surface of an object using a film forming material,
A material installation part on which the film forming material is placed;
An object support unit for supporting the object so as to face the film forming material placed on the material installation unit;
A shutter provided between the material installation unit and the object support unit so as to be retractable from between the material installation unit and the object support unit;
A first sensor that is disposed in the vicinity of the object support unit and that can measure a film formation speed and a film thickness of a thin film formed on the object, and is disposed between the material installation unit and the shutter. A sensor unit having a second sensor;
A control unit configured to be able to control the deposition rate and the deposition thickness based on the measurement result of the sensor unit;
With
The controller is
Immediately after the shutter is retracted, the film forming speed is controlled based on the output value of the second sensor, and after the output value of the first sensor is stabilized, the film forming speed is controlled based on the output value of the first sensor. Configured to control the membrane velocity,
The output value of the second sensor is adopted as the initial film thickness from when the shutter is retracted until the start of film deposition speed control based on the output value of the first sensor, and the first film thickness is set to the first film thickness. A film forming apparatus for controlling the film thickness based on a total film thickness value obtained by integrating output values of film thicknesses of the first sensor after the start of control based on an output value of one sensor.   The film forming apparatus according to claim 1, wherein the control unit includes a determination unit that automatically determines a control start timing based on an output value of the first sensor based on a predetermined condition. A film forming method for forming a film on the surface of an object using a film forming material,
Preliminary step of stabilizing the film forming speed by feedback control using a shutter side sensor arranged between the shutter and the film forming material in a state where the film forming material and the object are shielded by a shutter. When,
A film forming step of forming a thin film made of the film forming material on the surface of the object while continuing the feedback control after retracting the shutter;
An output source for feedback control of the film formation speed in the film formation process is arranged in the vicinity of the object from the shutter side sensor, and the film formation speed and film thickness of the thin film formed on the object Switching step to the object side sensor capable of measuring,
A film thickness control step for controlling the film thickness of the thin film on the surface of the object within a predetermined range;
With
In the switching step,
The film thickness of the thin film formed from when the shutter is retracted until the output source is switched to the object side sensor is acquired as the initial film thickness based on the output value of the shutter side sensor. ,
The film thickness of the thin film formed after the output source is switched to the object-side sensor is integrated with the initial film thickness based on the output value of the object-side sensor. The total film thickness value of
In the film formation thickness control step, the film formation thickness of the thin film is controlled based on the total film formation thickness value. A determination step of determining whether the output value of the object side sensor is stable based on a predetermined condition;
The film forming method according to claim 3, wherein the switching step is executed when it is determined in the determination step that an output value of the object side sensor is stable.

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