JPH0776774A - Substrate holder - Google Patents

Abstract

PURPOSE:To provide the substrate holder having a large cooling capacity in spite of use of a fluid medium, capable of rapidly detecting leakage of this fluid medium in case of leakage of the fluid medium and less affecting a vacuum device. CONSTITUTION:This substrate holder has a substrate holding section 24 disposed in a vacuum vessel 30 and a detector 26 mounted at this vacuum vessel 30. This substrate holding section 4 has a substrate base 4 which is used to support a substrate 2 and is cooled by a refrigerant 8, a substrate retainer 14 which presses the peripheral edge of the substrate 2 toward this substrate base 4 and a cooling pad 16 which is installed on the substrate base 4 so as to be held between the substrate base 4 and the substrate 2 and is formed by sealing the fluid medium 22 of a relatively high vapor pressure incorporated in a small amt. in the fluid medium 20 of a relatively high vapor pressure into a flexible bag 18. The detector 26 detects that the fluid medium 22 of the high vapor pressure in the cooling pad 16 of the substrate holding part 24 leaks into the vacuum vessel 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam, plasma, electron beam on a substrate in a vacuum or reduced pressure atmosphere such as an ion implantation apparatus, a sputtering apparatus, a dry etching apparatus, an electron beam irradiation apparatus and the like. The present invention relates to a substrate holding device used when a particle having energy such as is incident.

[0002]

2. Description of the Related Art Electric power applied to a substrate such as a semiconductor or a liquid crystal display by an ion beam or plasma when a treatment such as ion implantation or etching is performed in a vacuum or a reduced pressure atmosphere. In order to suppress the temperature rise of the substrate due to the above, a substrate holding device as shown in FIG. 2 is proposed.

In this substrate holding device, the substrate 2 is placed on a substrate table 4 on which a flexible and thin sheet 10 is stretched, and the sheet 10 is placed on the substrate 2 by a fluid medium 12 such as pressurized water or vacuum pump oil. The close contact with the back surface improves the contact area with the substrate 2 and reduces the thermal resistance. The peripheral edge of the substrate 2 is pressed by the substrate holder 14 toward the substrate table 4. The substrate table 4 has a coolant passage 6 inside, and is cooled by flowing a coolant 8 such as cooling water from the outside into the coolant passage 6.

[0004]

However, in the above-mentioned substrate holding device, there is a possibility that the sheet 10 is broken due to abrasion of the sheet 10 due to contact with the substrate 2 or abnormal pressure rise of the fluid medium 12, and the sheet 10 is broken. When is broken, a large amount of the fluid medium 12 leaks out into the vacuum atmosphere, so that there is a problem that a vacuum device such as a vacuum pump is greatly damaged.

Moreover, since no means has been provided for detecting that the fluid medium 12 has leaked into the atmosphere, there is a problem in that it cannot be detected early.

In view of the above, the present invention uses a fluid medium, has a large cooling capacity, and is capable of promptly detecting if the fluid medium leaks out, and has little influence on the vacuum apparatus. The main purpose is to provide.

[0007]

In order to achieve the above object, a substrate holding device of the present invention is provided for supporting a substrate, and a substrate table cooled by a coolant, and an edge of the substrate. And a substrate holder that is pressed toward the substrate holder and is provided on the substrate holder so as to be sandwiched between the substrate holder and the substrate, and has a relatively high vapor pressure in a fluid medium having a relatively low vapor pressure. It has a cooling pad formed by enclosing a small amount of a fluid medium in a flexible bag, and a substrate holder provided in a vacuum container and a relatively high temperature inside the cooling pad of the substrate holder. And a detector for detecting that the vapor pressure fluid medium leaks into the vacuum container.

[0008]

[Function] By sandwiching the cooling pad in which the fluid medium is enclosed in a flexible bag between the substrate stand and the substrate,
The fluid medium in the cooling pad is free to deform to an isotropic pressure. As a result, the cooling pad has a uniform thickness within the surface of the substrate, and a uniform cooling capacity can be obtained. Moreover, since the surface of the cooling pad is deformed according to the unevenness of the substrate or the substrate table, the contact area with the substrate surface and the substrate table surface is large, and therefore a very large cooling capacity can be obtained.

If the cooling pad bag is damaged and the fluid medium leaks into the vacuum container, the fluid medium having a high vapor pressure is vaporized and diffused into the atmosphere, which is detected. It can be quickly detected by the instrument.

Moreover, since a high vapor pressure fluid medium is mixed in only a small amount, most of the fluid that leaks out is a low vapor pressure fluid medium, and even if this leaks into the vacuum container, it affects the vacuum device. There is almost no. This is because the fluid medium having a low vapor pressure does not scatter even if it leaks into the vacuum atmosphere, and remains at the leaking location.

[0011]

FIG. 1 is a sectional view showing a substrate holding device according to an embodiment of the present invention. This substrate holding device includes a substrate holding unit 24 provided in a vacuum container 30 that is evacuated by a vacuum pump (not shown), and a detector 26 attached to the vacuum container 30.

The substrate holder 24 is used for the substrate 2 as described above.
It is sandwiched between the substrate table 4 for supporting the substrate 4 and the substrate retainer 14 that retains the edge of the substrate 2 toward the substrate platform 4 and the substrate 4 on the substrate 4. And the cooling pad 16 provided as described above.

The substrate table 4 has a coolant passage 6 inside, and is cooled by flowing a coolant 8 such as cooling water or a CFC substitute from the outside.

The substrate table 4 holds one substrate 2 in this embodiment, but it may be a large disk and holds a plurality of substrates 2 at its peripheral portion.

The substrate retainer 14 has an annular shape in this embodiment and retains the peripheral edge of the substrate 2.
It is also possible to press the edge of the substrate 2 at a plurality of places.

The cooling pad 16 is a flexible bag 18 in which a small amount of a relatively high vapor pressure fluid medium 22 is mixed in a relatively low vapor pressure fluid medium 20.

For the fluid medium 20 having a low vapor pressure, it is preferable to use vacuum grease containing silicone grease as a main component. The vacuum grease is a grease that has a low vapor pressure, does not evaporate even when placed in a vacuum atmosphere, and therefore does not reduce the vacuum degree of the atmosphere.

The high vapor pressure fluid medium 22 may be a gas such as hydrogen, nitrogen, a rare gas (eg, helium), or a liquid such as ethyl alcohol or water.

The amount of the high vapor pressure fluid medium 22 mixed in the low vapor pressure fluid medium 20 is preferably as small as possible within the range detectable by the detector 26. This is to reduce the influence of the leakage of the high vapor pressure fluid medium 22 on the vacuum device and the substrate 2 as much as possible.

The bag 18 is made by sealing a flexible sheet made of, for example, a fluororesin film or a polyimide film into a bag shape.

The cooling pad 16 is preferably fixed on the substrate table 4 with an adhesive or the like so as not to shift on the substrate table 4.

The detector 26 detects that the high vapor pressure fluid medium 22 in the cooling pad 16 has leaked into the vacuum container 30. In this embodiment, gas molecules in the vacuum container 30 are detected. A quadrupole mass spectrometer that measures the partial pressure of is used.

In the substrate holder 24, the cooling pad 16 in which the fluid mediums 20 and 22 are enclosed in a flexible bag 18 is sandwiched between the substrate base 4 and the substrate 2 so that the flow inside the cooling pad 16 is prevented. The sexual media 20, 22 are free to deform to an isotropic pressure. As a result, the cooling pad 16 has a uniform thickness within the surface of the substrate 2, and a uniform cooling capacity can be obtained. Moreover, the cooling pad 16
Since the surface of the substrate is deformed according to the unevenness of the substrate 2 and the substrate table 4, the contact area with the substrate surface and the substrate table surface is large, and thus a very large cooling capacity can be obtained.

If the bag 18 of the cooling pad 16 is damaged and the fluid mediums 20 and 22 leak into the vacuum container 30, the fluid medium 22 having a high vapor pressure is vaporized and is exposed to the atmosphere. Since it diffuses, it can be quickly detected by the detector 26.

Moreover, since the fluid medium 22 of high vapor pressure is mixed in only a small amount, most of the fluid that leaks out is the fluid medium 20 of low vapor pressure. There is almost no influence on the vacuum device and the substrate 2 by the above. This is because the low-vapor-pressure fluid medium 20 does not scatter even if it leaks into the vacuum atmosphere, but remains at the leaking location.

According to this substrate holding device, since a large cooling capacity can be obtained as described above, when the surface of a substrate such as a semiconductor or a liquid crystal display is subjected to a treatment such as ion implantation or etching, an ion beam or The temperature rise of the substrate due to the electric power applied to the substrate by the plasma can be effectively suppressed. As a result, various processing processes used in conventional semiconductor processing processes can be used at high processing rates.

For example, the implantation time can be shortened by increasing the ion current density during ion implantation. Also,
By suppressing the temperature rise of the substrate, it is possible to use a resist, and it is possible to suppress unnecessary polycrystallization of the ion implantation part. Also, the plasma density can be increased for fast etching. If the temperature rise of the substrate is large, the resist cannot be used. Therefore, if a metal is used instead of the resist, the pre-process and post-process of ion implantation must be changed, and the device structure must be changed. However, since the resist can be used by using this substrate holding device, it is possible to improve the processing capability without changing the front-back process or the element structure.

Next, two experimental examples will be described.

(Experimental Example 1) As the cooling pad 16, a vacuum vapor containing silicone grease as a main component was used as a fluid medium 20 having a low vapor pressure in a bag 18 made of a fluororesin film. A medium in which helium gas was enclosed was used as the medium 22. In addition, the detector 26
A quadrupole mass spectrometer was used as. Vacuum container 3 under normal conditions
The total pressure in 0 is 5 × 10 ⁻⁷ Torr, and the partial pressure of helium measured by the quadrupole mass spectrometer at that time is 1 × 10 7.
^{While the} pressure was below ^-10 Torr (detection limit), the partial pressure of helium when the bag 18 was damaged could be detected within the range of 10 ^-7 Torr to 10 ^-4 Torr depending on the damage condition. did it. Further, the leaked helium did not affect the vacuum device.

(Experimental Example 2) As a cooling pad 16, a bag 18 made of a fluororesin film, a low vapor pressure fluid medium 20, a vacuum grease containing silicone grease as a main component, and a high vapor pressure fluidity were used. A medium in which ethyl alcohol was enclosed was used as the medium 22. A quadrupole mass spectrometer was used as the detector 26. Under normal conditions, the total pressure in the vacuum container 30 is 5 × 10 ⁻⁷ Torr, and the partial pressure of hydrocarbons measured by the quadrupole mass spectrometer at that time is 1 × 1.
While it was on the order of 0 ^-8 Torr, the partial pressure of hydrocarbons when the bag 18 was damaged was 10 ^-6 Tor depending on the damage condition.
It was possible to detect in the range of about rr to 10 ⁻³ Torr. Moreover, the leaked ethyl alcohol had no effect on the vacuum apparatus.

[0031]

As described above, according to the present invention, the cooling pad in which the fluid medium is enclosed in the flexible bag is interposed between the substrate stand and the substrate, and the fluidity in the cooling pad is improved. Since the medium is freely modified so as to have an isotropic pressure, the cooling pad has a uniform thickness in the plane of the substrate, and a uniform cooling capacity can be obtained. Moreover, since the surface of the cooling pad is deformed according to the unevenness of the substrate or the substrate table, the contact area with the substrate surface and the substrate table surface is large, and therefore a very large cooling capacity can be obtained.

If the cooling pad bag is damaged and the fluid medium leaks into the vacuum container, the fluid medium with high vapor pressure is vaporized and diffused into the atmosphere. It can be quickly detected by the instrument.

Moreover, since only a small amount of the high vapor pressure fluid medium is mixed, most of the fluid that leaks out is the low vapor pressure fluid medium, and even if it leaks into the vacuum container, it does not scatter. Since it stopped at the place where it leaked out, it had almost no effect on the vacuum device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a substrate holding device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional substrate holding device.

[Explanation of symbols]

 2 substrate 4 substrate stage 8 refrigerant 14 substrate retainer 16 cooling pad 18 bag 20 low vapor pressure fluid medium 22 high vapor pressure fluid medium 24 substrate holder 26 detector 30 vacuum container

Claims (1)

[Claims] 1. A substrate table for supporting a substrate, which is cooled by a coolant, a substrate holder for pressing an edge of the substrate toward the substrate table, and the substrate table and the substrate on the substrate table. It is placed so that it is sandwiched between the two, and a small amount of a fluid medium with a relatively high vapor pressure is mixed in a fluid medium with a relatively low vapor pressure, which is sealed in a flexible bag. A substrate holding unit having a pad and provided in the vacuum container, and detection for detecting that a fluid medium having a relatively high vapor pressure in the cooling pad of the substrate holding unit leaks into the vacuum container. And a substrate holding device.