JP2000285843A - Vent device for vacuum preliminary chamber and substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vent method and a substrate processing device for a vacuum preliminary chamber capable of certainly preventing a pressure application of a vacuum preliminary chamber at the time of venting even if a relief valve is not used and a particle deposition to the substrate. SOLUTION: An exhaust center three-position directional control valve 48 for discharging air at both sides of a piston 36 of a double acting cylinder 34 at a center position is used at a cylinder control circuit 42a for controlling the double acting cylinder 34 for opening/closing a flap valve 4 partitioning the inside and the outside of the vacuum preliminary chamber. The three position directional control valve 48 is changed to a center position at approximately the same time of an opening of a vent valve to carry out an vent of the vacuum preliminary chamber. Thereby, the flap valve 4 has a function of a relief valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for introducing a vent gas into a pre-vacuum chamber constituting a substrate processing apparatus for processing a substrate in a vacuum by an ion beam or the like, such as an ion implantation apparatus and a thin film forming apparatus. The present invention relates to a venting method for venting the vacuum preparatory chamber (that is, returning to the atmospheric pressure) and a substrate processing apparatus for performing such a venting method, and more specifically, means for preventing pressurization of the vacuum preparatory chamber by a vent gas. Regarding improvement.

[0002]

2. Description of the Related Art A vacuum preparatory chamber (also referred to as a load lock chamber) is used to carry a substrate in and out without opening a processing chamber evacuated to a vacuum (usually a high vacuum) to the atmosphere.
This is provided between the processing chamber and the atmospheric pressure side, and by providing this, the throughput can be improved.

FIG. 3 shows an example of a substrate processing apparatus having such a vacuum preparatory chamber. In this apparatus, a vacuum preparatory chamber 2 is provided above a processing chamber 18 for processing a substrate (for example, a semiconductor wafer) 22 (for example, for performing ion implantation) via a vertically movable substrate support table 20 also serving as a valve element. Adjacent configuration. The substrate support table 20 is moved up and down by the elevating device 28 via the shaft 24 as shown by the arrow C.
26 is a bearing part having a vacuum sealing function.

An opening 3 through which the substrate 22 is inserted into and taken out from the atmosphere side is provided in a side surface of the vacuum preparatory chamber 2. A flap valve 4 is provided. A flap valve is a valve that opens and closes by rotating about a rotation shaft 6 at one end of a valve body, such as a one-sided door. A ceiling lid 8 is provided at the ceiling of the vacuum preparatory chamber 2. 3
Reference numerals 0 to 32 denote packings (for example, O-rings) for vacuum sealing.

Conventionally, the flap valve 4 is opened and closed by a flap valve driving device as shown in FIG. In this example, the flap valve driving device includes a pneumatic double-acting cylinder 34 for driving the flap valve 4 to open and close,
Arm 40 for converting the reciprocating linear motion of the piston 36 of FIG. 4 as shown by arrow B into the reciprocating rotary motion (opening and closing motion) of the flap valve 4 as shown by arrow A, and cylinder control for controlling the motion of the double-acting cylinder 34 And a circuit 42.

The cylinder control circuit 42 includes a compressed air source 44
And the compressed air from the port a of the double-acting cylinder 34
And a two-position switching valve 46 for switching and supplying between the b-side and the b-side. When the two-position switching valve 46 is switched to the closed side as shown in the figure, compressed air is supplied to the port a behind the double-acting cylinder 34, the piston 36 moves forward, and the flap valve 4 is closed. When the two-position switching valve 46 is switched to the open side, compressed air is supplied to the port b in front of the double-acting cylinder 34, the piston 36 moves rearward, and the flap valve 4 opens. In this state, for example, the transfer robot (not shown) on the atmospheric pressure side can carry the substrate 22 into and out of the vacuum preliminary chamber 2 through the opened flap valve 4.

The vacuum preparatory chamber 2 is evacuated to a vacuum by a vacuum exhaust device (not shown) via the exhaust valve 10 before the substrate support table 20 is moved up and down to transfer the substrate 22 to and from the processing chamber 18. You. Before the flap valve 4 is opened to transport the substrate 22 to and from the atmospheric pressure side, the vent valve 12 is opened and the vent gas 14 is introduced to vent.

Referring to FIG. 5, a conventional example of this venting method will be described. After the exhaust valve 10 is closed, the vent valve 12 is opened (step 60), and the vent gas 14 is supplied to the pre-vacuum chamber 2.
And return to atmospheric pressure. The vent gas 14 is, for example, a nitrogen gas, and its pressure is a somewhat positive pressure (for example, a gauge pressure of about 0.5 kg / cm ² ).

It is determined whether or not the vacuum preparatory chamber 2 has reached the atmospheric pressure.
It is detected by the atmospheric pressure sensor 16 connected to the pre-vacuum chamber 2, and after the detection (step 61), the vent valve 12 is closed (step 62).
4, the flap valve 4 is opened (step 63), and the substrate 22 is transported.

[0010]

As described above, in the method of detecting that the vacuum preparatory chamber 2 has reached the atmospheric pressure by the atmospheric pressure sensor 16, the vacuum preparatory chamber 2 is somewhat evacuated due to an error of the atmospheric pressure sensor 16. Atmospheric pressure may be detected in a vacuum state, and even if the user attempts to open the flap valve 4 in that state, the force of the atmosphere pushing the flap valve 4 from the outside (in other words, the force of suctioning the flap valve 4 by vacuum). Since the driving force of the double-acting cylinder 34 is larger than that of the double-acting cylinder 34, the flap valve 4 does not open. Therefore, usually, the flap valve 4 is opened after the vacuum preliminary chamber 2 is slightly pressurized by the vent gas 14.

However, when venting the pre-vacuum chamber 2, a failure or the like occurs in the atmospheric pressure sensor 16 or the control system for controlling the vent, and the vent gas 14 continues to be supplied even though all the valves are closed. Then, the pre-vacuum chamber 2 may be excessively pressurized and the pre-vacuum chamber 2 may be damaged. Conventionally, as a countermeasure, the ceiling lid 8 which has a large area and is easily affected by pressure is freed without being fixed, or is elastically pressed against the vacuum preliminary chamber 2 by a spring (not shown). In addition, a relief mechanism is adopted in which the ceiling lid 8 is lifted and the pressure is released when the pressure in the pre-vacuum chamber 2 exceeds a certain level.

However, if the vent gas 14 is not stopped, the ceiling lid 8 rises when the pressure reaches a specified pressure, and falls when the pressure decreases, so that vibration occurs in the ceiling lid 8, whereby the ceiling lid 8 rubs against the opposing surface. Particles (garbage) are generated. Since the ceiling lid 8 is located above the substrate 22, the generated particles are
2 and contaminate the surface. In recent years, in particular, the integration and miniaturization of semiconductor devices have been progressing, and the problem of particle adhesion is serious.

Although it is considered that a normal relief valve (safety valve) used for a pneumatic circuit is used instead of using the ceiling lid 8 as a relief mechanism, the relief valve is originally used for pressure relief in a high pressure area. This valve is not designed to be used in a vacuum region, and has a problem that when it is connected to the vacuum preparatory chamber 2 and pulled toward the vacuum side, vacuum leakage is likely to occur.

Therefore, the present invention provides a vent in a vacuum preparatory chamber which can surely prevent pressurization of the vacuum preparatory chamber at the time of venting without using a relief valve, and can prevent particles from adhering to a substrate. It is a primary object to provide a method and a substrate processing apparatus for performing such a venting method.

[0015]

According to a vent method according to the present invention, an exhaust center type three-position switching valve for discharging air on both sides of a piston of a double acting cylinder at a center position to a switching valve of the cylinder control circuit. The three-position switching valve is switched to the center position almost simultaneously with the opening of the vent valve, and the vacuum preliminary chamber is vented.

According to the venting method, since the three-position switching valve is switched as described above, the double-acting cylinder and the flap valve connected to the double-acting cylinder can be freely moved almost simultaneously with the start of the venting of the pre-vacuum chamber. However, while the vacuum prechamber is in vacuum, the flap valve is pressed inward by the atmospheric pressure, and when the vacuum prechamber vents and the vacuum prechamber reaches atmospheric pressure, the flap valve may be opened slightly. it can.

In this case, even if the vent gas does not stop due to a failure or error of the atmospheric pressure sensor at the time of venting and the vacuum preparatory chamber attempts to be pressurized, the flap valve is automatically pushed and opened by the pressure of the vent gas. So that the pressure can be released. Therefore, the pressurization of the pre-vacuum chamber at the time of venting can be reliably prevented without using a relief valve.

Moreover, since the flap valve is originally made for opening and closing, even if it is opened as described above at the time of venting, almost no particles are generated. Even if particles are generated in the flap valve during the pressure relief operation, the flap valve is provided on the side surface of the pre-vacuum chamber and is not located above the substrate in the pre-vacuum chamber. As a result, the particles flow outward, so that the particles can be prevented from adhering to the substrate.

In the substrate processing apparatus according to the present invention, an exhaust center type three-position switching valve for discharging air on both sides of a piston of the double-acting cylinder at a central position is used as a switching valve of the cylinder control circuit. A control circuit is provided for controlling the switching of the three-position switching valve to the center position and venting of the vacuum spare chamber almost simultaneously with the opening of the vent valve.

According to this substrate processing apparatus, since the above-described venting method can be performed, the same effects as those of the above-described venting method can be obtained.

[0021]

FIG. 1 is a diagram showing an example of a flap valve driving device of a substrate processing apparatus for performing a venting method according to the present invention. FIG. 2 is a flowchart showing an example of the venting method according to the present invention. The same or corresponding parts as those in the conventional example shown in FIGS. 4 and 5 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below. The configuration of the entire substrate processing apparatus including the vacuum preparatory chamber is the same as, for example, that shown in FIG. 3 and will be referred to here, and redundant description will be omitted here.

In this example, a switching valve of a cylinder control circuit 42a corresponding to the cylinder control circuit 42 discharges air on both sides of a piston 36 of the double-acting cylinder 34 at a central position, that is, a so-called exhaust center type three-position valve. A switching valve 48 is used. The three-position switching valve 48 is an electromagnetic valve in this example.

In this example, the cylinder control circuit 42a controls the speed of the opening / closing operation of the pressure regulating valve 50 for regulating the pressure of the compressed air supplied from the compressed air source 44, the double-acting cylinder 34 and the flap valve 4. The flow rate adjusting valves 52 and 54 for adjusting are provided. However, these do not affect the essence of the present invention.

The switching operation of the three-position switching valve 48 and the opening / closing operation of the vent valve 12, that is, the venting method as shown in FIG. 2, is performed by control of a control circuit 56 in this example. The control circuit 56 is supplied with an atmospheric pressure detection signal from the atmospheric pressure sensor 16.

The method of venting the pre-vacuum chamber 2 is mainly shown in FIG.
First, similarly to the conventional example, the exhaust valve 1
After closing 0, the control circuit 56 sends an open signal to the vent valve 12 to open the vent valve 12 and start introducing the vent gas 14 into the vacuum preparatory chamber 2 (step 60).

At about the same time (including at the same time as the opening of the vent valve 12), the control circuit 56 supplies a switching signal to the three-position switching valve 48 to switch the three-position switching valve 48 to the center position (step 60a). Thereby, the three-position switching valve 48
Is released, the air on both sides of the piston 36 of the double-acting cylinder 34 is discharged (discharged) from the three-position switching valve 48, and the piston 36 of the double-acting cylinder 34 and the flap valve 4 connected to the piston 36 are in a free state. That is, the flap valve 4 has the function of a relief valve. Note that the switching signal may be the same as the open signal to the vent valve 12.

Thereafter, step 61 in FIG.
Since these are the same as in to 63, repeated description is omitted.

According to this venting method, the three-position switching valve 4
8 is switched as described above, the double-acting cylinder 34 and the flap valve 4 connected to the double-acting cylinder 34 become freely movable (free state) almost simultaneously with the start of venting of the pre-vacuum chamber 2. However, while the vacuum preparatory chamber 2 is under vacuum, the flap valve 4 is pressed inward by the atmospheric pressure, and the venting of the vacuum preparatory chamber 2 proceeds, and only when the vacuum preparatory chamber 2 is almost at atmospheric pressure. The flap valve 4 can be opened lightly (that is, with a small force).

In this case, even if the vent gas 14 does not stop due to a failure or an error of the atmospheric pressure sensor 16 at the time of venting and the vacuum preparatory chamber 2 is to be pressurized, the flap valve 4 is operated by the pressure of the vent gas 14. The pressure is released automatically so that the pressure can be released. Therefore, pressurization of the pre-vacuum chamber 2 at the time of venting can be reliably prevented without using a relief valve as in the conventional example.

As a result, it is not necessary to use the ceiling lid 8 as a relief mechanism as in the conventional example, and the ceiling lid 8 can be fixed on the upper part of the vacuum preliminary chamber 2. Also, unlike the conventional example, there is no problem of reliability such as a vacuum leak of the relief valve.

Further, since the flap valve 4 is originally made for opening and closing, even if it is opened as described above at the time of venting, there is almost no generation of particles. what if,
Even if particles are generated at the flap valve 4 during the pressure relief operation, the flap valve 4 is provided on the side surface of the vacuum preliminary chamber 2 and is not located above the substrate 22 in the vacuum preliminary chamber 2. Moreover, since the particles are swept outward by the flow of the vent gas 14, the particles can be prevented from adhering to the surface of the substrate 22.

Further, since the pressurization of the pre-vacuum chamber 2 can be reliably prevented as described above, and the adhesion of particles to the substrate 22 can also be prevented, the vent gas 14 introduced into the pre-vacuum chamber 2 can be prevented. Can be made higher than before. For example, the gauge pressure can be increased to about 2.5 kg / cm ^2, which is five times the conventional value. As a result, it is possible to shorten the venting time of the pre-vacuum chamber 2 and to improve the throughput of the substrate processing apparatus.

The mechanism for converting the linear motion of the double-acting cylinder 34 into the opening / closing motion of the flap valve 4 is based on the arm 40.
Other than these, for example, a combination of a rack and a pinion may be used.

[0034]

As described above, according to the present invention, the flap valve can be opened by the pressure and the pressure can be released even if the pre-vacuum chamber is pressurized at the time of venting. Even if it is not provided, pressurization of the pre-vacuum chamber at the time of venting can be reliably prevented.

Further, even if the pressure is released from the flap valve as described above, almost no particles are generated, and even if it is generated, the flap valve is not above the substrate and the particles are directed outward by the vent gas. Therefore, particles can be prevented from adhering to the substrate.

Further, as described above, the pressurization of the pre-vacuum chamber can be reliably prevented, and the particles can be prevented from adhering to the substrate. Higher, and as a result, it is possible to shorten the vent time of the pre-vacuum chamber, and thereby improve the throughput of the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a flap valve driving device of a substrate processing apparatus that performs a venting method according to the present invention.

FIG. 2 is a flowchart showing an example of a venting method according to the present invention.

FIG. 3 is a cross-sectional view illustrating an example of a substrate processing apparatus including a vacuum preparatory chamber.

FIG. 4 is a view showing a conventional example of a flap valve driving device for opening and closing the flap valve in FIG. 2;

FIG. 5 is a flowchart showing an example of a conventional venting method.

[Explanation of symbols]

 2 Pre-vacuum chamber 4 Flap valve 12 Vent valve 14 Vent gas 16 Atmospheric pressure sensor 22 Substrate 34 Double-acting cylinder 42a Cylinder control circuit 44 Compressed air source 48 3-position switching valve

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Yoshiyuki Yamamoto, Inventor F-term (reference) 5C001 AA02 BB03 CC07 5C033 KK01 KK09 5C034 CC07 CC09 CC16 in 47 Nisshin Electric Co., Ltd.

Claims (2)

[Claims] 1. A vacuum preparatory chamber, which is repeatedly evacuated to a vacuum and vented to atmospheric pressure by introducing a vent gas, and provided on a side surface of the vacuum preparatory chamber, An externally-opening flap valve that partitions the inside and outside, a double-acting cylinder that opens and closes the flap valve, a cylinder control circuit that controls the movement of the double-acting cylinder, and has a compressed air source and a switching valve; A vent valve for opening and closing a vent gas introduced into a chamber, wherein a switching valve of the cylinder control circuit is provided with an exhaust center type three-position switching valve for discharging air on both sides of a piston of the double acting cylinder at a central position. And venting the vacuum preparatory chamber by switching the three-position switching valve to the center position almost simultaneously with the opening of the vent valve. Method. 2. A vacuum preparatory chamber, which is repeatedly evacuated to a vacuum and vented to the atmospheric pressure by introducing a vent gas, and provided on a side surface of the vacuum preparatory chamber, An externally-opening flap valve that partitions the inside and outside, a double-acting cylinder that opens and closes the flap valve, a cylinder control circuit that controls the movement of the double-acting cylinder, and has a compressed air source and a switching valve; A vent valve for opening and closing a vent gas introduced into a chamber, wherein a switching valve of the cylinder control circuit is provided with an exhaust center type three-position switching valve for discharging air on both sides of a piston of the double acting cylinder at a central position. And a control circuit for controlling the switching of the three-position switching valve to the center position and venting of the vacuum spare chamber almost simultaneously with the opening of the vent valve. A substrate processing apparatus, comprising: