JP5156897B2 - Film forming apparatus and film thickness measuring method - Google Patents

Description

  The present invention generally relates to a thin film forming apparatus and a film thickness measuring method used therefor, and more specifically to a technique for realizing highly accurate film thickness measurement.

  FIG. 6 is a diagram of a conventional film forming apparatus 200. The film forming apparatus 200 is disposed opposite to the vacuum source 1 and the evaporation source 2 for evaporating the vapor deposition material disposed on the bottom surface of the vacuum chamber 1, which is composed of a sealed container connected to a vacuum exhaust device (not shown). A substrate dome 3 that holds the film formation substrate 31, an RF power source 4 for applying a high frequency voltage to the substrate dome 3, a crystal monitor 5 made of a crystal resonator, and a measuring means 60 for measuring the oscillation frequency of the crystal monitor 5 (For example, Patent Document 1).

  The RF power source 4 applies a high frequency (for example, 13.56 MHz / 1 KW) to the substrate dome 3 through a matching box (not shown) to generate a glow discharge in the space between the substrate dome 3 and the evaporation source 2 to form a plasma state. To be provided. Thus, a self-induced negative DC electric field is generated on the surface of the film formation substrate 31 mounted on the substrate dome 3, and a thin film having a high packing density is formed on the film formation substrate 31 with the high energy.

  The measuring means 60 measures the film thickness by utilizing the property that the oscillation frequency varies depending on the evaporation material deposited on the surface of the crystal resonator of the crystal monitor 5. Based on the film thickness measurement result, the evaporation rate is controlled by a control system (not shown).

FIG. 7 shows an electrical connection configuration around the crystal monitor 5. The crystal monitor 5 has electrodes A and B, both of which are connected to the measuring means 60, and the electrode A on the film forming surface side is electrically connected to the vacuum chamber 1 and becomes a ground potential. For convenience of explanation, the above electrical connection is shown by wiring, but it may be connected via a conductive member or the like.
In the measuring means 60, the wires from the electrodes A and B are connected to the oscillation circuit 62 and the measurement control unit 64 via the coaxial cable 61. The measurement control unit 64 is connected to a control system (not shown).
JP 2004-354372 A

By the way, reviewing the arrangement of the crystal monitor 5 has been studied for the purpose of improving the monitor accuracy. FIG. 8 shows an evaporation distribution 21 from the evaporation source 2 inside the vacuum chamber 1. When the substrate plane is set horizontally with respect to the evaporation source, the film thickness t0 at a point immediately above the evaporation point and the film thickness t1 at an arbitrary point on the substrate plane are expressed by t1 / t0 = Cos ⁿ θ. Although the evaporation distribution 21 is slightly different depending on the evaporation material or the like, it is represented by Cos ⁿ θ, and the crystal monitor 5 is included only at the end of the evaporation distribution 21. Therefore, with such an arrangement of the crystal monitor, there is a problem that the evaporation material is not reliably deposited and the film thickness cannot be measured with high accuracy.

Therefore, as shown in FIG. 1, when the crystal monitor 5 is disposed in the center of the substrate dome 3 (in a state electrically insulated from the substrate dome 3), the crystal monitor 5 is positioned at the center of the evaporation distribution 21. Thus, the film thickness can be measured with high accuracy.
However, it has been found that when the crystal monitor 5 is arranged at the center of the substrate dome 3, the following problems occur due to the close distance between the crystal monitor 5 and the substrate 3 dome.

When the connection of FIG. 7 is used in the configuration of FIG. 1, the potential of the substrate dome 3 becomes lower than the potential of the crystal monitor 5 (that is, the ground potential of the vacuum chamber 1). A high frequency voltage from the RF power source 4 is applied to the substrate dome 3, but a voltage V ₃ in which the high frequency voltage is offset to the negative side is generated in the substrate dome 3 due to the action of the negative electric field due to the plasma described above. This negative DC component varies depending on the high frequency power to be applied, the area ratio between the substrate dome 3 and the ground potential, the evaporation material, and the like.

Ions (+ potential) in the plasma are accelerated by the voltage V ₃ and enter the substrate dome 3. At this time, ions also enter the crystal monitor 5 (ground potential) in the vicinity of the substrate dome 3.
As a result, the deposited film on the electrode A of the crystal monitor is etched by the incidence of ions, and there is a problem in that normal film thickness measurement cannot be performed.

  Therefore, an object of the present invention is to provide a film forming apparatus capable of measuring a normal film thickness even when the crystal monitor 5 is arranged at the center of the substrate dome 3. In other words, an object of the present invention is to realize a configuration in which the crystal monitor 5 reliably captures the deposit from the evaporation source 2 but avoids etching due to the incidence of ions in the plasma.

  A first aspect of the present invention includes a vacuum chamber, an evaporation source in the vacuum chamber, a substrate dome arranged to face the evaporation source and on which a film formation target substrate is mounted, an ion generation means for irradiating ions to the substrate dome, and a substrate A film forming apparatus including a crystal monitor disposed in the center of the dome and a measuring unit for measuring an oscillation frequency of the crystal monitor, wherein the crystal monitor is electrically insulated from the vacuum chamber and the substrate dome. Device.

  The second aspect of the present invention is a vacuum chamber, an evaporation source in the vacuum chamber, a substrate dome disposed opposite to the evaporation source and mounted with a film formation target substrate, an ion generating means for irradiating the substrate dome with ions, a substrate A film forming apparatus provided with a crystal monitor disposed in the center of the dome and a measuring means for measuring the oscillation frequency of the crystal monitor, and further, a voltage ( Vext) is a film forming apparatus provided with a bias power source for applying a voltage equal to or higher than Vext).

  In the film forming apparatus according to the first or second aspect, the ion generating means is an RF power source for applying a high frequency voltage to the substrate dome, one end of the output of the RF power source is connected to the substrate dome, and the other is grounded The crystal monitor is electrically insulated from the vacuum chamber and the substrate dome.

  According to a third aspect of the present invention, there is provided a film thickness measuring method in a film forming apparatus, wherein (A) the evaporation material is evaporated from an evaporation source to a film formation target substrate mounted on the substrate dome, and the substrate dome is Irradiating with ions, and (B) measuring the oscillation frequency of a crystal monitor disposed in the center of the substrate dome. In steps (A) and (B), the crystal monitor is removed from the vacuum chamber and the substrate dome. This is a film thickness measurement method in which the insulating layer is electrically insulated to form a floating potential.

  According to a fourth aspect of the present invention, there is provided a film thickness measuring method in a film forming apparatus, wherein (A) the evaporation material is evaporated from an evaporation source to a film formation target substrate mounted on the substrate dome, and A step of irradiating ions, (B) a step of measuring an oscillation frequency of a crystal monitor disposed in the central portion of the substrate dome, and (C) a potential (Vext) or higher that blocks the incidence of ions on the crystal monitor to the crystal monitor This is a film thickness measuring method comprising the step of biasing the voltage.

  According to the present invention, even when the crystal monitor is arranged at the center of the substrate dome, the crystal monitor is configured to avoid the etching due to the incidence of ions in the plasma while reliably capturing the deposit from the evaporation source. In addition, accurate film thickness measurement can be performed.

FIG. 1 shows a film forming apparatus 100 of the present invention. The vacuum chamber 1, the evaporation source 2, the substrate dome 3 and the RF power source 4 are the same as those of the conventional example shown in FIG.
As described above, the crystal monitor 5 is disposed at the center of the substrate dome 3 while being electrically insulated from the substrate dome 3.

  FIG. 2 is a diagram showing an electrical connection configuration of the crystal monitor 5 according to the first embodiment of the present invention. The difference from FIG. 7 of the conventional example is that the electrode A of the crystal monitor 5 is electrically insulated from the vacuum chamber 1 and the crystal monitor 5 is electrically floating. In practice, the crystal monitor 5 is supported or coupled to the vacuum chamber 1 directly or indirectly via an insulating member (not shown).

  In the measuring means 6, the wires from the electrodes A and B are connected to the measurement control unit 64 via the coaxial cable 61, the oscillation circuit 62, the photocoupler 63 and the coaxial cable 61. Until the input of the photocoupler 63 is floated, the reference potential from the output of the photocoupler 63 becomes the same ground as in the prior art.

  In the above configuration, the ions are incident on the electrode surface of the crystal monitor 5 in the floating state, although the amount is small. ).

  As described above, by setting the crystal monitor 5 to the floating potential, the crystal monitor 5 can avoid the etching due to the incidence of ions while ensuring the reliable deposition of the evaporation material, and can measure the film thickness with high accuracy. It became.

FIGS. 3A and 3B are principle diagrams of a reflected electric field type ion beam analyzer. In FIG. 3A, the electrode 50 corresponds to the crystal monitor 5. As shown in FIG. 3B, when the voltage of the variable voltage source Vret is increased, the ion current Ii starts to decrease from a certain point, and finally the ion current Ii becomes zero. The voltage at this time is Vext. This Vext does not necessarily depend on the ground potential but changes with ion energy.
Therefore, by applying a voltage corresponding to Vext to the crystal monitor 5, it is possible to prevent the incidence of ions.

  Note that the potential Vext for completely blocking the incidence of ions may be obtained by actual measurement. A plasma excitation state is created in the apparatus in advance, the oscillation frequency of the crystal monitor is measured while changing the voltage of the bias power supply, and the lowest potential at which the oscillation frequency does not change may be set to Vext.

FIG. 4 is a diagram showing a crystal monitor connection configuration according to the second embodiment of the present invention. The difference from FIG. 2 is that a bias power source 7 for biasing a DC voltage is added to the crystal monitor 5. The potential V ₅ of crystal monitor 5 is intended to be fixed to a constant voltage value or more potential to completely block the entrance of the ions by a bias voltage 7. The inside of the measuring means 6 is the same as that in FIG.

Although the aspect of the present embodiment is disadvantageous in cost as compared with the first embodiment in that the bias power supply 7 has to be added, the effect of the present invention can be surely obtained.
Further, since the potential of the substrate dome (negative potential with respect to the ground) varies depending on the applied high frequency power, the area of the substrate dome 3, the evaporation material, etc., the output voltage of the bias power source 7 is made variable so as to optimize the value. It may be.

  FIG. 5 shows a third embodiment of the present invention. The vacuum chamber 1, the evaporation source 2, and the substrate dome 3 are the same as those in FIG. The difference from FIG. 1 is that an ion gun 8 is provided instead of the RF power source that applies a high-frequency voltage to the substrate dome. The crystal monitor 5 is disposed at the center of the substrate dome 3 in the connection configuration shown in FIG. 2 or 4 while being electrically insulated from the substrate dome 3 and the vacuum chamber 1. The substrate dome 3 is irradiated with an ion beam from the ion gun 8, and by setting the crystal monitor 5 to a floating potential or applying a bias voltage to the crystal monitor 5, the substrate dome 3 is irradiated with ions. Etching can be avoided and highly accurate film thickness measurement is possible.

  Although the ion gun is provided in the third embodiment, the present invention is not limited to this, and the effects of the present invention can be obtained as long as other ion generation means (or plasma generation means) are provided and the substrate dome is irradiated with ions. Examples of other ion generating means (or plasma generating means) include the use of an ion plating electrode and the use of a plasma gun.

In each of the above-described embodiments, as the most preferable examples, the crystal monitor 5 is floated and the crystal monitor 5 is biased with a DC voltage. However, the configuration in which V ₅ ≧ Vext is satisfied during film formation. Any other voltage waveform or circuit configuration may be used, and these are also included in the scope of the present invention.

It is the schematic of the film-forming apparatus of this invention. It is a figure which shows the crystal monitor connection structure of the 1st Example of this invention. It is a figure explaining the 1st Example of this invention. It is a figure which shows the crystal monitor connection structure of the 2nd Example of this invention. It is a figure which shows the 3rd Example of this invention. It is the schematic of the film-forming apparatus of a prior art example. It is a figure which shows the crystal monitor connection structure of a prior art example. It is a figure explaining a general film-forming apparatus.

Explanation of symbols

1. Vacuum chamber 2. 2. Evaporation source 3. Substrate dome 4. RF power supply Crystal monitor 6. Measuring means 7. Bias power supply8. Ion gun 31. Substrate 61. Coaxial cable 62. Oscillation circuit 63. Photocoupler 64. Measurement control unit 100. Deposition equipment

Claims (5)

A vacuum chamber, an evaporation source in the vacuum chamber, a substrate dome disposed opposite to the evaporation source and on which a substrate to be deposited is mounted, an ion generating means for irradiating the substrate dome with ions, and a central portion of the substrate dome A film forming apparatus including a disposed crystal monitor and a measurement unit that measures an oscillation frequency of the crystal monitor,
A film forming apparatus in which the crystal monitor is electrically insulated from the vacuum chamber and the substrate dome. A vacuum chamber, an evaporation source in the vacuum chamber, a substrate dome disposed opposite to the evaporation source and on which a substrate to be deposited is mounted, an ion generating means for irradiating the substrate dome with ions, and a central portion of the substrate dome A film forming apparatus including a disposed crystal monitor and a measurement unit that measures an oscillation frequency of the crystal monitor,
And a bias power supply that applies a voltage equal to or higher than a voltage (Vext) that blocks the incidence of ions to the crystal monitor to the crystal monitor.   3. The film forming apparatus according to claim 1, wherein the ion generating means is an RF power source for applying a high-frequency voltage to the substrate dome, and one of output terminals of the RF power source is connected to the substrate dome, and the other Is a film forming apparatus in which the crystal monitor is electrically insulated from the vacuum chamber and the substrate dome. A film thickness measuring method in a film forming apparatus,
(A) a step of evaporating vapor deposition material from an evaporation source to a film formation target substrate mounted on the substrate dome, and irradiating the substrate dome with ions; and (B) disposed at a central portion of the substrate dome. It consists of the step of measuring the oscillation frequency of the crystal monitor,
In the steps (A) and (B), the film thickness measuring method in which the crystal monitor is electrically insulated from the vacuum chamber and the substrate dome so as to have a floating potential. A film thickness measuring method in a film forming apparatus,
(A) a step of evaporating a deposition material from an evaporation source on a deposition target substrate mounted on the substrate dome and irradiating the substrate dome with ions;
(B) a step of measuring an oscillation frequency of a crystal monitor disposed at the center of the substrate dome; and (C) a voltage equal to or higher than a potential (Vext) that blocks the incidence of ions on the crystal monitor. A film thickness measurement method comprising a step of biasing.

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