JP5337532B2 - Vacuum processing equipment - Google Patents

Description

  The present invention relates to a vacuum processing apparatus, and more particularly to a vacuum processing apparatus provided with a vacuum preliminary chamber (load lock chamber) for evacuating a sample atmosphere when a sample is introduced into a sample chamber.

  In an apparatus for measuring and inspecting a semiconductor wafer or mask, which is a kind of vacuum processing apparatus, a preliminary exhaust chamber is connected to a sample chamber for holding a sample. When the sample is carried into the vacuum sample chamber, the gate valve between the vacuum preparatory chamber and the atmospheric transfer system is opened and the sample is carried into the preexhaust chamber. Next, the preliminary exhaust chamber is evacuated, the gate valve connected to the sample chamber is opened, and the sample is carried into the sample chamber. The processed sample is transported to the vacuum preparatory chamber by opening the gate valve between the sample chamber and the vacuum preparatory chamber. The vacuum preliminary chamber is opened to the atmosphere, and the sample is carried out by the atmospheric transfer system.

  When the vacuum preliminary chamber is opened to the atmosphere, particles floating in the chamber or particles deposited on the wall surface are carried by the air flow and adhere to the sample, thereby reducing the yield of the product.

  When opening the atmosphere, the pressure difference between the pressure in the vacuum prechamber and the inert gas to be injected is large, and the flow velocity around the air supply valve increases. In order to reduce the flow velocity around the air supply valve, it is effective to use a slow start valve that controls the air supply flow rate and a diffusion filter that increases the surface area of the air supply port.

  Patent Document 1 discloses a technique for performing exhaust while supplying air in order to avoid a sudden pressure change when the atmosphere is released.

JP 2002-231783 A

  As described in Patent Document 1, by supplying air while exhausting when the atmosphere is released, it is possible to avoid sudden pressure fluctuations and discharge particles along with the flow of exhaust. However, since exhaust is performed together with the supply air, it takes time until the atmosphere is released. In addition, when the pressure in the vacuum atmosphere is low, it is difficult to suppress a pressure gradient that occurs suddenly even if exhaust is performed together with air supply. That is, turbulence may be generated in the vacuum chamber when the pressure rises to near atmospheric pressure when the atmosphere is released.

  Below, a vacuum processing apparatus for the purpose of preventing the rolling-up of particles based on the generation of a pressure gradient while suppressing the time required for opening to the atmosphere will be described.

  In order to achieve the above object, when the pressure in the load lock chamber rises to a predetermined first pressure when the load lock chamber is opened to the atmosphere by introducing gas from the air supply pipe, the load lock using the exhaust pipe is used. A vacuum processing apparatus is proposed that starts exhausting a room and stops exhaust using an exhaust pipe when the pressure in the load lock chamber rises to a second pressure higher than the first pressure.

  According to the above configuration, it is possible to achieve both suppression of the time required for opening to the atmosphere and suppression of particle winding.

Schematic explanatory drawing of the vacuum processing apparatus containing a scanning electron microscope. The flowchart explaining an air release process. The graph explaining the relationship between the elapsed time and the pressure in the load lock chamber when the atmosphere is open. The figure explaining the arrangement | positioning conditions of the sample in a load lock chamber.

  Below, a vacuum processing device is mainly provided with an air supply opening when the vacuum preparatory chamber (load lock chamber) is opened to the atmosphere near the upper center of the sample and provided with flow control valves such as a diffusion filter and a slow start valve. explain. However, the method relating to the air release described below can be applied to other vacuum processing apparatuses as long as the gist of the invention is not changed. Further, in this example apparatus, the clearance between the sample and the upper cover of the vacuum preliminary chamber was set to 10 mm or less. The exhaust port was arranged near the center below the sample. Further, when the pressure in the vacuum preparatory chamber is 10 Pa to 10000 Pa when the atmosphere is opened, the air is exhausted together with the supply air.

  In addition, when opening the air supply valve when releasing the atmosphere, a vacuum starter is used while controlling a sudden pressure gradient around the air supply port using a slow start valve that controls the air supply itself or a diffusion filter. Increase chamber pressure. When the pressure in the vacuum preparatory chamber becomes 10 Pa or more, the exhaust valve is opened, exhaust is performed together with air supply, and floating particles are discharged out of the vacuum preparatory chamber together with the airflow.

  The discharged volume is a volume that replaces the capacity of the vacuum preliminary chamber when the pressure of the vacuum preliminary chamber is 10,000 Pa. At this time, the clearance between the sample and the upper cover of the vacuum prechamber is set to 10 mm or less, and a gap of 10 mm or more is formed around the sample to create an air flow from the upper surface of the sample to the lower surface. The flow can be maintained and the adhesion of particles to the sample can be suppressed. Then stop the exhaust and raise the pressure to the atmosphere. The pressure in the vacuum preparatory chamber when closing the exhaust valve is 10000 Pa or less, and particles are discharged before the turbulence of the air current occurs.

  The apparatus of this embodiment effectively exhausts the particles that are rolled up and floated together with the exhaust gas without adhering to the sample surface while minimizing the air release time by optimally exhausting the air when the air is open. It is a device to do.

  In the vacuum preliminary chamber, an air supply pipe having a diffusion filter on the upper surface near the center of the sample is prepared. The outlet of the supply pipe has a shape that gently spreads toward the sample, and creates a laminar flow in the upper surface of the sample in the viscous flow region. There should be no moving parts that cause particles between the air supply pipe and the sample. The cover of the preliminary chamber on the top surface of the sample is managed cleanly by surface treatment and cleaning. The exhaust pipe is disposed on the lower surface of the sample. An air release valve is provided on the lower surface of the sample so that the inside of the chamber does not become a positive pressure.

  With reference to FIG. 1, the specific structure of the vacuum processing apparatus which comprises a part of measuring and test | inspection apparatus is demonstrated. The measurement and inspection apparatus of this example has a sample chamber 4, a lens barrel 3 that houses an electron optical system, and a preliminary exhaust chamber 9. The sample chamber 4 and the lens barrel 3 are connected, and both are evacuated. The sample chamber 4 and the preliminary exhaust chamber 9 are connected by a passage 5, and a sample chamber side gate valve 6 is provided in the passage 5. The preliminary exhaust chamber 9 and the atmosphere are connected by a passage 10, and an atmosphere-side gate valve 11 is provided in the passage 10.

  A sample chamber exhaust pipe 7 is connected to the bottom of the sample chamber 4. The sample chamber exhaust pipe 7 is provided with a sample chamber exhaust valve 8 and a vacuum exhaust device (not shown). The vacuum exhaust device is, for example, a vacuum pump. By opening the sample chamber exhaust valve 8 and operating the vacuum exhaust device, the inside of the sample chamber 4 is evacuated.

  A preliminary exhaust chamber exhaust pipe 12 and an atmosphere release pipe 14 are connected to the bottom of the preliminary exhaust chamber 9. A preliminary exhaust chamber exhaust valve 13 and a vacuum exhaust device (not shown) are connected to the preliminary exhaust chamber exhaust pipe 12. By opening the preliminary exhaust chamber exhaust valve 13 and operating the vacuum exhaust device, the interior of the preliminary exhaust chamber 9 is evacuated.

  The atmosphere release pipe 14 is provided with an atmosphere release valve 15 connected to the atmosphere. The air release valve 15 is a check valve, and opens when the pressure is higher than a predetermined pressure, and closes when the pressure is lower than the predetermined pressure. The operating pressure of the air release valve 15 may be higher than the atmospheric pressure. The atmosphere release valve 15 may be a control valve or a release valve. When the inside of the preliminary exhaust chamber 9 becomes higher than the atmospheric pressure and further exceeds a predetermined pressure, the atmosphere release valve 15 is opened, and the gas in the preliminary exhaust chamber 9 is released to the atmosphere. This prevents the inside of the preliminary exhaust chamber 9 from becoming a positive pressure than the set pressure above the atmosphere.

  An air supply pipe 16 is connected to the ceiling of the preliminary exhaust chamber 9. An air supply valve 17 and an air supply tank (not shown) are connected to the air supply pipe 16. The air supply valve is a slow exhaust valve or a valve combined with flow control. By opening the air supply valve 17, dry nitrogen is introduced into the preliminary exhaust chamber 9 from the air supply tank. In this example, dry nitrogen is used, but a dry inert gas other than dry nitrogen may be used. The vacuum processing apparatus of this embodiment is controlled by a control device (not shown), and controls the supply / exhaust control as described above and the operation of components related to the vacuum processing apparatus described later.

  With reference to FIG. 1, a process of carrying the sample 1 from the outside into the preliminary exhaust chamber 9 and further carrying it into the sample chamber 4 will be described. The sample chamber side gate valve 6 is closed, the preliminary exhaust chamber exhaust valve 13 and the air supply valve 17 are closed, and the preliminary exhaust chamber is in an atmospheric state. Open the atmosphere side gate valve 11. Next, the sample 1 is carried into the preliminary exhaust chamber 9 from the outside via the passage 10 and fixed on the sample holder 2. The atmosphere side gate valve 11 is closed. The preliminary exhaust chamber exhaust valve 13 is opened, and the preliminary exhaust chamber 9 into which the sample 1 is carried is evacuated. The sample chamber side gate valve 6 is opened, and the sample 1 is transported to the sample chamber 4 in a vacuum state via the passage 5 while being fixed to the sample holder. Next, the sample chamber side gate valve 6 is closed.

  Next, the process of carrying the sample 1 in the sample chamber 4 into the preliminary exhaust chamber 9 and carrying it out to the atmosphere will be described. Open the sample chamber side gate valve 6. It is assumed that the preliminary exhaust chamber 9 is evacuated. Next, the sample 1 held on the sample holder 2 is carried together with the sample holder 2 from the sample chamber 4 to the preliminary exhaust chamber 9 via the passage 5. Next, the sample chamber side gate valve 6 is closed. The preliminary exhaust chamber exhaust valve 13 is closed. Open the air supply valve 17. Thereby, dry nitrogen is injected into the preliminary exhaust chamber 9. When the pressure in the preliminary exhaust chamber 9 becomes atmospheric pressure, the air release valve is opened. The air supply valve 17 is closed, the atmosphere side gate valve 11 is opened, and the atmosphere release valve is closed. The sample 1 is conveyed to the outside via the passage 10.

  With reference to FIG. 1, a method for opening the preliminary exhaust chamber to the atmosphere using the apparatus of this embodiment will be described. Here, as shown in FIG. 1, it is assumed that the sample 1 held on the sample holder 2 is unloaded from the sample chamber 4 and arranged in the preliminary exhaust chamber 9. In step 01, the sample chamber side gate valve 6 is closed. In step 02, the preliminary exhaust chamber exhaust valve 13 is closed. In step 03, the preliminary exhaust air supply valve 17 is opened. Dry nitrogen is introduced into the preliminary exhaust chamber 9. The flow rate of dry nitrogen is gradually increased by a slow exhaust valve and a valve combined with flow control. The pressure in the preliminary exhaust chamber 9 increases. In step 04, it is confirmed by the vacuum gauge 18 which is a pressure detector in the preliminary exhaust chamber 9 that the pressure in the vacuum preliminary chamber has increased to 10 Pa. In step 05, the preliminary exhaust chamber exhaust valve 13 is opened.

  A pipe connected to the preliminary exhaust chamber exhaust valve is connected to a dry pump and a pressure of several Pa is prepared. The pressure in the preliminary exhaust chamber temporarily decreases to a pressure that balances the flow rate from the supply valve 17 and the flow rate in the preliminary exhaust chamber exhaust valve 13, and gradually increases as the flow rate from the supply valve 17 increases. The floating particles are discharged together with the exhaust gas from the preliminary exhaust chamber 9 through the preliminary exhaust chamber pipe 12. In step 06, an exhaust time waiting is set.

  The waiting time set at this time sets the time for the exhaust system to which the auxiliary exhaust chamber exhaust valve is connected to exhaust the volume replacing the capacity of the auxiliary exhaust chamber at 1000 Pa. The volume is 10% of the preliminary exhaust chamber 9 in the atmospheric state. In step 07, the preliminary exhaust chamber exhaust valve 13 is closed. After confirming that the pressure in the preliminary exhaust chamber 9 has further increased and the pressure has increased to the atmosphere in step 08, the step 09 atmosphere release valve 15 is opened. In step 10, the supply valve 17 is closed.

  FIG. 3 is a graph showing a change in pressure in the vacuum preparatory chamber when each component of the vacuum processing apparatus is controlled along the flowchart illustrated in FIG. In the present embodiment, the preliminary exhaust chamber exhaust valve 13 is closed at approximately 1000 Pa, but may be closed at other pressures of 10,000 Pa or less. FIG. 4 is a diagram for explaining the positional relationship between the sample 1 and the inner wall of the preliminary exhaust chamber 9. In the apparatus of this embodiment, the distance between the ceiling portion provided with the opening of the air supply pipe 16 at the time of opening to the atmosphere and the sample 1 is 10 mm or less, the periphery of the sample 1 (semiconductor wafer edge), and preliminary exhaust. The distance from the inner wall side of the chamber 9 was set to 10 mm or more. In other words, the sample is held such that an interval of 10 mm or more is maintained from the side of the cylinder indicated by the dotted line in the surface direction of the semiconductor wafer. In the present embodiment, the configuration in which the sample is arranged on the sample holder 2 is described. However, in the case of an apparatus for transporting the sample between the preliminary exhaust chamber 9 and the sample chamber 4 without the sample holder, the preliminary exhaust chamber is provided. A sample holding mechanism is provided for holding the sample in 9.

DESCRIPTION OF SYMBOLS 1 Sample 2 Sample holder 3 Electro-optic system lens tube 4 Sample chambers 5 and 10 Passage 6 Sample chamber side gate valve 7 Sample chamber exhaust pipe 8 Sample chamber exhaust valve 9 Preliminary exhaust chamber 11 Air side gate valve 12 Preliminary exhaust chamber exhaust pipe 13 Preliminary exhaust chamber exhaust valve 14 Air release pipe 15 Air release valve 16 Air supply pipe 17 Air supply valve 18 Vacuum gauge

Claims (4)

A load lock chamber that is connected to a vacuum chamber and evacuates the sample atmosphere when a sample is introduced into the vacuum chamber, a supply pipe that introduces gas into the load lock chamber, and exhausts the gas in the load lock chamber In a vacuum processing apparatus provided with an exhaust pipe to be controlled and a control device for controlling supply and exhaust of the air supply pipe and the exhaust pipe,
A detector for detecting the pressure in the load lock chamber;
When the detector detects that the pressure in the load lock chamber has increased to a predetermined first pressure when the load lock chamber is opened to the atmosphere by introducing gas from the air supply pipe. When the detector detects that the pressure in the load lock chamber has started to be exhausted using the exhaust pipe and the pressure in the load lock chamber has increased to a second pressure higher than the first pressure. , Stopping the exhaust using the exhaust pipe, and controlling the supply / exhaust so as to supply air using the air supply pipe until the load lock chamber is in an atmospheric state after the exhaust is stopped. Vacuum processing equipment. In claim 1,
The vacuum processing apparatus, wherein the control device performs the exhaust in a range of 10 Pa to 10,000 Pa. In claim 1,
A support table for supporting the sample in the load lock chamber, wherein the support table has a greater distance between the sample and the inner wall side surface of the load lock chamber than a distance between the sample and the inner wall upper surface of the load lock chamber; The vacuum processing apparatus is characterized in that the sample is supported. In claim 3,
A vacuum processing apparatus characterized in that the distance between the sample and the upper surface of the inner wall of the load lock chamber is 10 mm or less, and the distance between the sample and the inner wall side surface of the load lock chamber is 10 mm or more.

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