JP5227638B2 - Vacuum processing equipment - Google Patents

Description

  The present invention relates to a vacuum processing apparatus, and more particularly to a vacuum processing apparatus using an electrostatic chuck.

  In general, various types of vacuum processing apparatuses for processing a substrate in a vacuum, such as sputtering, are used for manufacturing a semiconductor device. In such a vacuum processing apparatus, an electrostatic chuck is generally used for mounting and supporting a substrate to be processed in a vacuum chamber.

  In general, this type of electrostatic chuck has a built-in chuck electrode and is connected to a DC high-voltage power supply installed outside. By applying a high voltage to the chuck electrode, a coulomb is generated between the chuck electrode and the substrate, and the substrate is electrostatically attracted. Further, the electrostatic chuck is provided with a gas introduction mechanism for controlling the substrate temperature, and the gas introduction is performed by introducing an inert gas such as Ar gas into the back surface of the electrostatically adsorbed substrate. In other words, the heat transfer between the substrate and the electrostatic chuck is improved to improve the in-plane temperature distribution of the substrate. Prior art of this type of electrostatic chuck includes an insulating substrate adsorption (see Patent Document 1), and the electrostatic force is corrected according to the holding force of the object to be processed. Examples include a configuration in which the degree of adhesion is constant (see Patent Document 2), a configuration in which it is possible to determine whether or not an object to be processed is adsorbed on the adsorption surface (see Patent Document 3), and the like. .

In a vacuum processing apparatus equipped with this type of electrostatic chuck, for example, at the start of the process, the substrate transferred to the electrostatic chuck is electrostatically adsorbed, and then backside gas is introduced. Control at the time of gas introduction is performed by a control means attached to the gas system, and the gas flow rate is controlled so that the pressure in the piping becomes a set pressure.
When the process is completed, the box operation first exhausts the Ar gas filled in the piping, and after confirming that the pressure in the piping is equal to or lower than the predetermined pressure, electrostatic adsorption is stopped, and then the wafer Perform the unload operation.
Further, in order to control the substrate temperature during the process, it is desirable to make the pressure distribution of the Ar gas filled between the substrate and the electrostatic chuck constant.

In the conventional electrostatic chuck mechanism, Ar gas filled between the substrate and the electrostatic chuck is prevented from leaking into the vacuum chamber by electrostatically attracting the substrate to the electrostatic chuck.
The electrostatic chuck is generally provided with a heating mechanism, and may be heated to around 500 ° C. depending on the process. Therefore, it is important that the material of the surface on which the substrate is attracted to the electrostatic chuck should have heat resistance, the amount of emitted gas is small, and no contamination occurs.

  However, there is a limit to reliably sealing the Ar gas supplied between the substrate and the electrostatic chuck. In addition, in order to improve the productivity of the apparatus, it is necessary to shorten the processing time for one substrate, and for that purpose, it is required to raise and stabilize the substrate temperature in a short time. In order to satisfy the requirement, it is required to fill the gas between the substrate and the electrostatic chuck in a short time to the set pressure, and therefore it is desirable to perform feedback control with respect to the pressure. Therefore, the pressure in the gas pipe is monitored using a vacuum gauge so that the pressure in the gas pipe is always constant, and the flow rate of Ar gas flowing in the gas pipe is controlled according to the pressure state. .

Therefore, the flow rate of Ar gas supplied between the substrate and the electrostatic chuck always fluctuates.
Regarding the fluctuation amount of Ar gas, the individual difference of the measuring device, the electrostatic attraction force, the pipe volume and the shape are the fluctuation factors, so it is impossible to determine the fluctuation amount between the apparatuses and between the modules in advance.

  Even if the substrate adsorption failure occurs for some reason, if the pressure in the gas pipe can be controlled, the process is executed no matter how the Ar gas flow rate fluctuates, resulting in a product failure. An abnormality occurred.

  Therefore, the present invention has been made based on such circumstances, and an object of the present invention is to provide a vacuum processing apparatus capable of accurately monitoring the leakage amount of filled Ar gas and preventing substrate temperature abnormality. It is said.

A vacuum processing apparatus according to the present invention includes a vacuum chamber, a pair of electrodes, an electrostatic chuck that attracts a substrate on an upper surface, a ring-shaped seal member formed on the surface of the electrostatic chuck, a substrate, and an electrostatic chuck At least one heat medium introduction system for introducing a heat medium between the pressure medium, a pressure monitoring means for monitoring the pressure of the heat medium introduced between the substrate and the electrostatic chuck via the heat medium introduction system, A control means for controlling the pressure monitoring means so that the pressure of the heat medium introduced between the substrate and the electrostatic chuck via the medium introduction system becomes a predetermined pressure set in advance; have a detection means for detecting the leakage of the heat medium to the vacuum chamber from between a pair of electrodes of the electrostatic chuck consists of a circular electrode and a ring-shaped electrode, a ring-shaped electrode is located below the sealing member The circular electrode is phosphorous It is characterized in that it is arranged concentrically inside the shape electrode.

  Further, the seal member may define a distance between the substrate to which the heat medium is introduced and the electrostatic chuck.

In the vacuum processing apparatus according to the present invention, an electrostatic chuck that includes a pair of electrodes in the vacuum chamber and that adsorbs the substrate on the upper surface is provided, and a ring-shaped seal member is provided on the surface of the electrostatic chuck, and at least one A heat medium is introduced between the substrate and the electrostatic chuck via the heat medium introduction system, and the pressure of the heat medium introduced between the substrate and the electrostatic chuck is monitored by pressure monitoring means, and the heat medium introduction system A control means is provided for controlling the pressure monitoring means so that the pressure of the heat medium introduced between the substrate and the electrostatic chuck is set to a predetermined pressure, and between the seal portion and the substrate. Since there is a detection means to detect the leakage of the heat medium from the vacuum chamber to the vacuum chamber, the pressure of the heat medium filled between the substrate and the electrostatic chuck in the process without depending on the specification of the apparatus, especially the control method One distribution It can be, thereby, it is possible to control the substrate temperature to the desired level of planned so that it may be prevented substrate temperature abnormality.
The pair of electrodes of the electrostatic chuck is composed of a circular electrode and a ring electrode, the ring electrode is located under the seal member, and the circular electrode is concentrically disposed inside the ring electrode. As a result, the suction force of the substrate at the seal portion is large, and the substrate is sucked at the seal portion, so that leakage is reduced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a vacuum processing apparatus embodying the present invention, wherein 1 is a vacuum chamber, and the vacuum chamber 1 is an exhaust system (not shown) for exhausting the inside of the vacuum chamber 1 to a high vacuum. It is connected to the. As an exhaust system, a turbo molecular pump can be used for main exhaust. In addition, a metal base 2 is provided at the bottom of the vacuum chamber 1, and an electrostatic chuck 3 is mounted on the top of the base 2, and the electrostatic chuck 3 delivers the substrate 4 to be processed and the substrate. 4 has a function of heating. That is, the electrostatic chuck 3 includes an ESC chuck electrode 3a, and a heater electrode 3b can be incorporated as necessary.

  FIG. 2 shows an embodiment of the electrostatic chuck 3. The illustrated electrostatic chuck 3 has a disk-shaped main body 31, and the upper surface of the disk-shaped main body 31 is annular along the outer periphery thereof. A seal member 32, that is, a seal ring is provided. A circular electrode 33 is provided at the center of the disk-shaped main body 31, and a ring electrode 34 is provided concentrically with the circular electrode 33. The circular electrode 33 and the ring electrode 34 are substantially formed. Located in the same plane. The pair of electrodes 33 and 34 are connected to an external DC power source (not shown). A through hole 35 extending in the thickness direction is formed at the center of the main body 31 and the central circular electrode 33.

  Referring again to FIG. 1, a through hole 5 is formed in the longitudinal direction in the center of the electrostatic chuck 3, and the upper end of the through hole 5 is defined by the upper surface of the electrostatic chuck 3, that is, the seal member 32 and the substrate 4. Open to the open space 6. The lower end of the through hole 5 is connected to the heat medium introduction system 8 through the through hole 7 provided in the base 2.

  The heat medium introduction system 8 includes a pressure monitoring unit 9, which can be a vacuum gauge, a valve 10, and a flow meter 11, and the pressure monitoring unit 9, the valve 10, and the flow meter 11 are connected to the control unit 12. The heat medium introduction system 8 is connected to a supply source (not shown) of an inert gas such as Ar gas via a valve 13. The vacuum gauge 9 is configured to monitor the pressure in the space 6 defined between the heat medium introduction system 8 and thus the electrostatic chuck 3 and the substrate 4. The valve 10 functions to control the flow rate of a heat medium such as Ar gas in the heat medium introduction system 8. The flow meter 11 functions to monitor the flow rate of Ar gas in the heat medium introduction system 8.

  The vacuum chamber 1 is provided with a mass analyzer 14, which acts as a detection means for detecting a heat medium leaking from between the seal member 32 and the substrate 4 to the vacuum chamber 1. Yes. That is, the gas analyzer in the vacuum chamber 1 can be monitored by the mass analyzer 14.

An embodiment using the apparatus configured as described above will be described below.
The case of the sputtering apparatus will be described as an example. The substrate 4f to be sputtered is transferred onto the electrostatic chuck 3 in the vacuum chamber 1 by a transfer robot (not shown). Next, the substrate 4 is electrostatically attracted to the electrostatic chuck 3 by applying a DC voltage to an electrode of the electrostatic chuck 3 from a DC high voltage power source (not shown). In this state, the substrate 4 is electrostatically attracted electrostatically onto the seal member 32 of the electrostatic chuck 3.

  In this state, Ar gas is introduced from the heat medium introduction system 8 into the space 6 between the substrate 4 and the electrostatic chuck 3 in order to control the temperature of the substrate 4 prior to processing. The subsequent operation sequence will be described as follows.

  An electric signal corresponding to the set pressure is supplied from the control means 12 to the vacuum gauge 9. As a control method in this case, the control mode can be such that the pressure is increased in 10 seconds up to the set pressure and maintained after 10 seconds. The information obtained from each component at this time is shown in the graph of FIG. In the graph of FIG. 3, the curve A is the gas pressure indication value obtained from the vacuum gauge 9, and the curve B is the gas flow indication value obtained from the flow meter 11.

  Simultaneously with the pressure increase in the space 6 between the substrate 4 and the electrostatic chuck 3 by Ar gas, the Ar gas flow rate increases as shown by curve B, and when the pressure reaches the set pressure, a flow rate control signal from the control means 12. As a result, the valve 10 is throttled, whereby the Ar gas flow rate is lowered and the flow rate necessary to maintain the pressure is supplied.

When comparing the analog waveform of FIG. 3 with the actual waveform obtained from the apparatus, it becomes as shown in FIG. 4, in which curve A becomes curve A ′ and curve B becomes curve B ′.
Although the pressure waveform curve A ′ is to be controlled so as to be always equal to the set pressure, there is a gas leak between the substrate 4 and the electrostatic chuck 3 even if electrostatic pressure adsorption is performed. Therefore, the pressure is controlled with the width C.

At that time, the flow rate of the gas supplied to the space 6 between the substrate 4 and the electrostatic chuck 3 also fluctuates, so that the flow rate flowing per unit time repeatedly increases and decreases as shown by the curve B ′. . In this way, the waveform shown in the graph of FIG. 3 is used in an actual apparatus.
In this case, the interlock at the time of operation is set in order to operate the apparatus stably, but since the feedback is performed for the pressure value, the interlock setting for the pressure value may not be meaningful. Recognize. Therefore, the interlock value is generally set for the flow rate of the gas supplied to the space 6 between the substrate 4 and the electrostatic chuck 3, but in the present invention, the substrate 4 and the electrostatic chuck 3 are set. The gas flow rate in the space 6 between the substrate 4 and the electrostatic chuck 3 is kept constant by constantly adjusting the flow rate of the gas supplied to the space 6 between the substrate 4 and the electrostatic chuck 3. Therefore, it can be easily assumed that it is difficult to set the interlock value. When the pressure of the heat medium leaking into the vacuum chamber exceeds a predetermined value, a display notifying adsorption failure appears on the display.

  In addition, since it does not directly monitor the amount of gas leaking from between the substrate and the electrostatic chuck due to a decrease in electrostatic attraction force, it is not suitable as an interlock for monitoring electrostatic attraction force. I understand that.

Next, the result of monitoring the gas pressure in the vacuum chamber 1 by the mass analyzer 14 shown in FIGS. 5 and 6 will be described below.
Curves D and D ″ in FIGS. 5 and 6 are waveforms during the process by the mass analyzer 14.

  FIG. 5 is a graph when the electrostatically attracted substrate 4 and the electrostatic chuck 3 are operating normally. It can be seen that the waveform of the mass analyzer 14 represented by the curve D is stable even when the curve B ′ is fluctuating.

FIG. 6 is a graph at the time of abnormality when the adsorption force of the substrate 4 by the electrostatic chuck 3 is reduced.
It can be seen that although the waveform of the curve B ″ is distorted due to the decrease in the adsorption force, it is a waveform that repeatedly increases and decreases. However, the waveform of the mass analyzer 14 represented by the curve D ″ is the adsorption force. Due to the decrease, the amount of leak of the gas supplied to the space 6 between the substrate 4 and the electrostatic chuck 3 is increased.

  Thus, in the present invention, it can be seen that monitoring the waveform of the mass analyzer 14 serves as a monitor of the electrostatic attraction force applied to the substrate.

  By the way, in the illustrated embodiment, the hole 5 for supplying gas into the space 6 between the substrate 4 and the electrostatic chuck 3 is provided in the central portion of the electrostatic chuck 3. 3 may be provided with one or more holes in the main body portion between the circular electrode 33 and the ring-shaped electrode 34.

  Further, the contour of the electrostatic chuck 3 does not need to be circular, and can be configured in an arbitrary polygon shape according to the shape of the substrate to be processed.

The schematic diagram which shows one Embodiment of the vacuum processing apparatus by which this invention is implemented. The schematic section which expands and shows one embodiment of the electrostatic chuck in the present invention. The graph which shows the concept of the gas pressure and gas flow volume between an electrostatic chuck and a board | substrate. 3 is a graph showing gas pressure and gas flow rate between an electrostatic chuck and a substrate according to an embodiment of the present invention. The graph which shows the monitoring result of a mass spectrometer in case control of the gas pressure between the electrostatic chuck and board | substrate by embodiment of this invention is normal. The graph which shows the monitoring result of a mass spectrometer when control of the gas pressure between the electrostatic chuck and a board | substrate by embodiment of this invention is abnormal.

Explanation of symbols

1: Vacuum chamber 2: Metal base 3: Electrostatic chuck 3a: ESC chuck electrode 3b: Heater electrode 31: Disk-shaped main body 32: Annular seal member 33: Circular electrode 34: Ring electrode 35: Through-hole 5: Through-hole 6: Space defined by the seal member 32 and the substrate 4 7: Through-hole provided in the base 2 8: Heat medium introduction system 9: Vacuum gauge (pressure monitoring means)
10: valve 11: flow meter 12: control means 13: valve 14: mass analyzer (detection means)

Claims (2)

A vacuum chamber;
An electrostatic chuck comprising a pair of electrodes and attracting the substrate to the upper surface;
A ring-shaped seal member formed on the surface of the electrostatic chuck;
At least one heat medium introduction system for introducing a heat medium between the substrate and the electrostatic chuck;
Pressure monitoring means for monitoring the pressure of the heat medium introduced between the substrate and the electrostatic chuck via a heat medium introduction system;
Control means for controlling the pressure monitoring means so that the pressure of the heat medium introduced between the substrate and the electrostatic chuck via the heat medium introduction system becomes a predetermined pressure set in advance;
Detecting means for detecting leakage of a heat medium from between the seal portion and the substrate to the vacuum chamber;
A pair of electrodes of the electrostatic chuck comprises a circular electrode and a ring-shaped electrode, the ring-shaped electrode is located under the seal member, and the circular electrode is concentrically inside the ring-shaped electrode. vacuum processing apparatus characterized in that it is arranged.   The vacuum processing apparatus according to claim 1, wherein the seal member defines an interval between the substrate into which the heat medium is introduced and the electrostatic chuck.

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