JPH05166732A - Vacuum film forming apparatus - Google Patents

Abstract

PURPOSE:To reduce defects during film formation and to control generation of defectives without a rapid rough suction mainly causing particle deposition on a substrate by controlling the exhaust speed by a particle monitor. CONSTITUTION:A vacuum chamber is fitted with a particle monitor, and a vacuum exhaust system is equipped with a bypass valve Vl and an actuator- mounted conductance valve V3. First, slow exhaust is started by the bypass valve V1. After a constant pressure is reached, a booster MB1 is started to open the valve V2 and the bypass valve V1 and to slightly open the conductance valve V3, resulting in switching of the exhaust route. While the opening of V3 is controlled by signals of the particle monitor, slow exhaust is continued. The V3 is fully opened with open-close actions repeated to keep the particle count below a reference value. After rough suction is conducted to a pressure of about 0.2Torr, switching is made by a main exhaust pump CP1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum processing apparatus and an optical disk for performing film forming processing and etching processing on a semiconductor substrate.
The present invention relates to a vacuum film forming apparatus (sputtering, ion plating, vapor deposition, CVD) for forming a recording film such as a magnetic disk.

[0002]

2. Description of the Related Art In a vacuum film forming apparatus, it is necessary to set a substrate in the atmosphere and evacuate it with a vacuum pump to create a vacuum atmosphere. A laminated film is formed on the inner wall of the vacuum film forming apparatus and the substrate mounting portion by a steady film forming process.

When setting a substrate to be formed in a clean room, the laminated film is separated from the inner wall and the substrate mounting portion to generate particles, and the particles adhere to the substrate in the vacuum chamber. Particularly, in the roughing in which the exhaust is started from the atmosphere, the air in the vacuum chamber is agitated, so that the film is peeled off and the particles rise up from the bottom of the chamber, and the particles are easily attached to the substrate.

When vacuum film formation is performed on a substrate to which particles adhere, the portion is peeled off after vacuum film formation to form a pinhole, or a convex portion is formed to be a defect. Then, such a defect at the time of film formation affects, for example, a byte error rate (BER) of a recording disk,
Reduce yield.

As a method of preventing particle adhesion during roughing, it is known to make the initial roughing gentle, which is called slow exhaust. However, what to do with the slow exhaust time and to what pressure the slow exhaust should be done are only empirically determined by the person in charge of each device.

If the slow exhaust is not sufficient, particles are generated even when switching to the rough evacuation. Therefore, it is considered safe to perform a long slow exhaust, but this is not preferable from the viewpoint of process productivity.

Next, the roughing exhaust system of the conventional vacuum processing apparatus will be described. 2 to 4 are piping diagrams in the case of a one-chamber type vacuum film forming chamber, in which the laminated film adheres to the inner wall and the jig during continuous use and is easily peeled off.

FIG. 2 is a piping diagram of the simplest type vacuum processing apparatus. After activating the rotary pump RP2, the valve V5 is opened to reduce the pressure to a constant pressure P1. Next, a mechanical booster MB2 is added and rough evacuation is performed. When the pressure P2 is reached, V5 is closed and the valve V6 of CP2 for main exhaust is opened. Here, there is no room for consideration of preventing the generation of particles due to the device configuration.

In the piping diagram of FIG. 3, a rotary pump RP is used.
After starting 3, the bypass valve V7 is opened first and the pressure is exhausted to a constant pressure P1. As a result, slow exhaust is performed, and the initial generation of particles is suppressed. But V
7 is closed, the mechanical booster MB3 is activated, and the particles are generated when the valve V8 is opened.
I can not respond. After finishing roughing, as in the case of FIG.
V8 is closed and V9 is opened for main exhaust.

The piping diagram of FIG. 4 is provided with a valve V11 for half-opening, and the rotary pump RP4 is started to perform slow exhaust with the valves V10 open and V11 half open. Then, after exhausting to a constant pressure P1, the mechanical booster MB4 is started, V10 is fully opened, and exhaust is performed.

In this case, the half-opening degree of V11 can be determined empirically, and therefore it cannot be adjusted to the particle generation state for each batch. After the rough evacuation, as in the case of FIGS. 2 and 3, V10 and V11
Is closed, V12 is fully opened, and main exhaust is performed.

The particle monitor used this time is one in which the sensor section is mounted in a vacuum chamber and particles passing through the sensor window section are measured by utilizing the scattering of laser light.

Japanese Utility Model Application Laid-Open No. 2-132938 describes a vacuum processing apparatus equipped with a particle monitor, which is about how to set the particle monitor in the vacuum processing apparatus. In this publication, the vacuum film formation process is devised so that the film does not adhere to the particle monitor, but the method for controlling the slow exhaust is not described.

[0014]

The problem to be solved by the present invention is to reduce defects during film formation without performing rapid roughing, which is the main cause of particle adhesion to the substrate, and to reduce defective products. It is an object of the present invention to provide a vacuum film forming apparatus capable of appropriately determining a slow exhaust condition so as to suppress the occurrence of

[0015]

In order to solve the above problems, the present invention provides a vacuum film forming apparatus having a mechanism for controlling the exhaust speed by a particle monitor.

As shown in FIG. 1, the vacuum film forming apparatus according to the present invention has a particle monitor attached to a vacuum chamber and a vacuum exhaust system having a bypass valve V1 and a conductance valve V3 with an actuator. The particle monitor is preferably mounted in the chamber, but depending on the device, the same effect can be obtained by mounting the particle monitor in the roughing exhaust pipe section (between the chamber and the roughing valve V2).

Next, a method of controlling the exhaust system for preventing the generation of harmful particles will be described.

First, slow exhaust is started by the bypass valve V1. A small-diameter pipe, which was previously confirmed by a particle monitor so that the particle generation at this time is 0, is connected to V1.

Constant pressure P1 (200 to 100 Torr)
After that, MB1 is started, valve V2 is opened, bypass valve V1 is closed, and conductance valve V3 is opened very slightly to switch the exhaust path. Then, the slow exhaust is continued while controlling the opening of V3 by the signal of the particle monitor. In order to keep the particle count below the reference value, V
3 is fully opened. Then, the roughing is performed under the pressure P2, that is, 0.
After performing up to about 2 Torr, switch to the main exhaust pump CP1. The above operation is shown in the flowchart of FIG.

Further, even if the bypass exhaust from the bypass valve is controlled by using the particle monitor, the device configuration may be the same, and the constraint that the piping system must be determined in advance is removed.

[0021]

EXAMPLE A case of a four-chamber type in-line sputtering apparatus for a magneto-optical disk in which an exhaust rate control mechanism by a particle monitor is actually incorporated will be described. Figure 6
Shows the schematic diagram. However, the vacuum exhaust system other than the loading chamber is omitted.

In this apparatus, a plurality of disk substrates are set on a carrier, placed in a loading chamber and evacuated to a vacuum.

After that, the chamber is moved to the SP1 chamber, and the first-layer dielectric strip film is formed by sputtering. Subsequently, a second layer recording film, a third layer dielectric band film, and a fourth layer reflecting film are formed in each sputtering chamber. Each chamber is partitioned by a door valve to prevent contamination during sputtering film formation. Then, the atmospheric pressure is returned to the unload chamber and the disk substrate is taken out.

It is the loading chamber that evacuates the carrier to practice the invention. Since this chamber itself is separated from the sputter chamber by the door valve, no film is attached. However, there is a possibility that a laminated film adheres to the carrier for setting the disc by continuous use, and the laminated film is peeled off to generate particles. Therefore, it is necessary to perform slow exhaust appropriately.

This loading chamber contains 3/8
An inch bypass valve and a 2 inch conductance valve are connected. The conductance valve is a throttle type butterfly valve and is driven by a pulse motor. The molecular flow conductance is 150 l / sec and the time constant is 0.1 sec.

A particle monitor is set in the chamber. The particle monitor can detect particles of 0.5 μm or less, and the sampling time is set to several seconds. Then, the conductance valve opening / closing control is performed so that the count for each sampling time becomes equal to or less than the allowable value.

The allowable value at this time can be obtained from the relationship between the count by the particle monitor of FIG. 7 and the byte error rate (BER). If the permissible value is 10 / second, the BER can be managed to about 7 × 10 ⁻⁶ .

FIG. 8 shows changes in exhaust speed and particle count, with the time elapsed from the start of rough evacuation being plotted on the horizontal axis. However, the pumping speed is represented by the open area ratio% of the conductance valve to the rated pumping speed.

FIG. 9 shows the BER of a disk formed in one batch by such an exhaust process. From FIG.
It can be understood that the vacuum film forming apparatus of the present invention can reduce the error caused by film formation to a low level.

[0030]

According to the vacuum film forming apparatus of the present invention, defects such as pinholes in disks due to vacuum film formation are reduced, and the product yield is improved.

[Brief description of drawings]

FIG. 1 is an example of a configuration diagram of a vacuum film forming apparatus of the present invention.

FIG. 2 is a configuration diagram of a conventional one-chamber type vacuum film forming apparatus.

FIG. 3 is a configuration diagram of a conventional one-chamber type vacuum film forming apparatus.

FIG. 4 is a configuration diagram of a conventional one-chamber type vacuum film forming apparatus.

FIG. 5 is a flowchart showing a control method of the vacuum film forming apparatus of the present invention.

FIG. 6 is a schematic diagram of a four-chamber type in-line sputtering apparatus for a magneto-optical disk used in the examples.

FIG. 7 is a chart showing a relationship between a count by a particle monitor and a byte error rate (BER).

FIG. 8 is a chart showing changes in exhaust speed, pressure, and particle count with the lapse of time from the start of rough evacuation.

FIG. 9 is a chart showing the BER and the frequency of occurrence of disks formed in one batch.

[Explanation of symbols]

 1 Bypass valve 2 Roughing pump 3 Conductance valve 4 Mains valve V1 to V12 Vacuum valve RP Rotary pump RP1 to RP4 Rotary pump MB Mechanical booster MB1 to MB4 Mechanical booster CP Cryo pump CP1 to CP4 Cryo pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Yamato Inventor Masayuki Yamato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. 21-1 -A210

Claims (1)

[Claims] 1. A vacuum film forming apparatus having a mechanism for controlling an exhaust speed by a particle monitor.