JP2912616B1 - Plate heating device - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To heat a thin plate-shaped heating object from behind by an electron impact and to measure the temperature of the heating object from behind an electron impact filament disposed thereon, the temperature by the electron impact of a temperature measuring element. The measurement value is prevented from rising, the temperature is accurately measured, and the heating temperature of the heating object is accurately controlled based on the obtained temperature measurement value. SOLUTION: The plate heating device is a thin plate-shaped heating object a.
And a filament 9 which is provided in a space behind the heating portion 2 of the heating material support member 1 and which generates thermoelectrons.
And an electron accelerating power supply 11 for causing the thermoelectrons generated by the filament 9 to collide with the heating section 2 of the heated object support member 1;
The heating object support member 1 has a reflector 3 that reflects radiant heat generated from the heating unit 2 and is electrically independent of the filament 9 and the heating unit 2. Further, the heating unit 2
Having a thermocouple 12 in which a measurement point is arranged in a space behind the
A cylindrical shield 15 held at the same potential as the reflector 3 is provided so as to surround the thermocouple 12 and its measurement point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate heating apparatus for heating a thin flat plate-like heating object such as a semiconductor wafer to a high temperature, and more particularly, it has a temperature measuring means for measuring a heating temperature of the heating object.
The present invention relates to a plate heating device capable of controlling a heating current of a filament heating power supply based on a temperature measurement value measured by the temperature measuring means.

[0002]

BACKGROUND OF THE INVENTION At present, there are 200 semiconductor manufacturers.
The company is aiming for a mass production system for 12-inch wafers with a target of 0 years. The supply of silicon wafers has become almost uncertain, and now we are moving to semiconductor manufacturing technology using it, for example, development of manufacturing equipment and its evaluation. The technology that forms the basis of the process technology is a substrate heater, and (a) thermal uniformity, (b) cleanness, and (c) reliability are required.

Conventionally used plate heating means include electric resistance heating, induction heating and lamp heating.
Two measures have been used. From the viewpoint of (a) thermal uniformity, (b) cleanliness, and (c) reliability, the heating means that can cope with a 12-inch large area wafer has been developed with improved electric resistance heating and lamp heating. Is underway.

[0004]

In order to accurately heat a heated object such as a semiconductor wafer at a predetermined temperature,
The energy, such as heat or electrons, supplied to a heating means such as a resistor or a filament must be accurately controlled. For example, at the start of heating, by supplying energy at full power, the rate of temperature rise of the heated object must be increased, but when the desired temperature is reached,
It is necessary to control the supply energy promptly so as to supply only the energy corresponding to the energy lost at that temperature. At this time, it is important to accurately measure the temperature of the heated object, feed this measured value back to the control system of the filament heating power supply, and accurately control the power supply.

In a plate heating apparatus in a semiconductor processing apparatus, the heating temperature of a heated object such as a semiconductor wafer cannot be measured from the upper surface side using a thermocouple or the like. This is because when a semiconductor wafer or the like is irradiated with particles such as molecules, ions or electrons, a thermocouple or the like blocks the flight space of the particles, and normal semiconductor processing cannot be performed. In addition, when monitoring the heating temperature of the heating object from the side, there is a disadvantage that the heating temperature at the center cannot be accurately measured.

What is considered here is a means for measuring from the back side of the heated object which does not hinder the flight of particles. However, in the case of a plate heating device that performs electron impact heating by colliding electrons from the back surface of a hot plate on which a heated object is placed, the following problems occur. When the temperature measuring element is set to the same potential as the substrate, the temperature measuring point of the temperature measuring element is also subjected to electron impact, so that an accurate temperature cannot be measured. For example, when a sheath-type thermocouple is used as a temperature measuring element, the sheath tube is heated not only by radiant heat received from the substrate but also by electron impact,
The measured temperature is higher than the actual temperature of the heated object. If the temperature measuring element is set at a potential equal to or lower than the potential of the filament that generates thermoelectrons, electrons do not fly to the temperature measuring element, so that the problem of temperature rise due to electron impact is eliminated. However, in this case, the electric potential of the temperature measuring element has to be measured by floating, so that the measuring electric circuit becomes very complicated. That is, since the hot plate side of the substrate heating device is normally grounded, the filament for generating thermoelectrons needs to have a negative potential. It is necessary to set the temperature measuring element at a potential lower than the filament.

The present invention has been made in view of the problems in such a plate heating apparatus, and has as its first object to heat a heated object from behind by an electron impact and to arrange the heated object with an electron impact filament. It is an object of the present invention to prevent a rise in a temperature measurement value due to the electron impact and to accurately measure the temperature regardless of the potential of the temperature measuring element when measuring the temperature from behind. Furthermore, a second object of the present invention is to make it possible to accurately control the heating temperature of a heated object based on the obtained temperature measurement value.

[0008]

According to the present invention, in order to achieve the above object, a filament 9 for generating thermoelectrons is arranged behind a heating section 2 of a heating object support member 1 on which a heating object a is placed, The thermoelectrons generated by the filament 9 are accelerated and collide with the back surface of the heating unit 2, and the energy thereof is used for the heating unit 2.
The heating object a is heated through. Further, a reflector 3 is arranged behind the heating unit 2 to reflect radiant heat generated by heating the heating unit 2. Further, a temperature measuring point of the temperature measuring element is arranged behind the heating section 2, and the temperature measuring element and its temperature measuring point are surrounded by a cylindrical shield 15, and the shield 15 is set to the same potential as the reflector 3. did. Shield 1
The reflector 5 and the reflector 3 are electrically independent of the filament 9 and the heating unit 2.

That is, the plate heating apparatus according to the present invention comprises:
A heat-resistant heating object support member 1 having a flat heating portion 2 on which a thin flat heating object a is placed, and a heating electron support member 1 is provided in a space behind the heating portion 2 of the heating object support member 1 to generate thermoelectrons. The generated filament 9, the thermoelectrons generated by the filament 9 are caused to collide with the heating section 2 of the heated object support member 1, and the radiant heat generated from the heating section 2 of the heated object support member 1 is reflected. And the filament 9 and the heating section 2
A reflector 3 which is electrically independent of the above, a temperature measuring element having a measuring point disposed in a space behind the heating section 2, and surrounding the temperature measuring element and its measuring point, and having the same potential as the reflector 3. And a cylindrical shield 15 held.

In such a plate heating device, while the filament 9 and the temperature measuring point of the temperature measuring element are both arranged behind the heating section 2, the temperature measuring element is set at the same potential as the electrically independent filament. By surrounding with the shield 15 of
Electrons can be prevented from colliding with the temperature measuring element. Furthermore, since there is no electron impact on the shield 15, the temperature rise of the temperature measuring element due to the electron impact can be prevented, and the temperature of the heating unit 2 can be accurately measured.

The temperature measured by the temperature measuring element is fed back to a control circuit for controlling the filament heating power supply 10 and the electron acceleration power supply 11 for the filament 9, and the heating current and the acceleration voltage for the filament 9 are controlled. The temperature of the heating object a can be controlled to a desired temperature with high accuracy. When a flange 18 is extended outward from the end of the shield 15 near the heating section 2 of the heating object supporting member 1 so as to face the rear surface of the heating section 2, the temperature of the temperature measuring element is particularly increased to the temperature measuring point. Electrons can be effectively prevented, and more accurate temperature measurement can be performed.

The measuring point of the temperature measuring element can be brought into direct contact with the back surface of the heating section 2 of the heating object support member 1 or can be embedded. On the other hand, the temperature measuring point may be brought into contact with the back surface of the heating unit 2 or may be attached to the heat receiving plate 13 having good heat conduction which is in close proximity. In this case, it is easy to replace the temperature measuring element. When the temperature measuring point of the temperature measuring element or the heat receiving plate provided with the temperature measuring point is not in contact with the heating section 2 of the heated object supporting member 1, the heated object supporting member 1 made of Si-impregnated SiC or the like having high reactivity is used. This is advantageous in that a chemical change does not occur in the heating section 2 and that the temperature of the heating section does not drop due to contact. On the other hand, when the temperature measuring point of the temperature measuring element or the heat receiving plate provided with the temperature measuring point is brought into contact with the heating section 2 of the heating object supporting member 1, it is possible to measure the absolute temperature of the heating section. In any case, the reason why the accurate temperature can be measured is due to the effect of providing the shield 15.

[0013]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings.
FIG. 1 shows an example of a semiconductor manufacturing apparatus using a plate heating device according to the present invention. In FIG. 1, the depressurizing vessel is not shown, and only the stage 17 is shown. However, in practice, the depressurizing vessel is surrounded from both sides of the stage 17 over the stage.

A cooling liquid passage 7 is formed in the wall of the stage portion 17, and the stage portion 17 can be cooled by passing a cooling liquid such as water through the cooling liquid passage 7. On the stage section 17, a heat-resistant heated object support member 1 having a flat heating section 2 on which a thin plate-shaped heated object a such as a silicon wafer is placed is installed. 1 has a space that is airtightly separated from the space outside the space. More specifically, the heating object support member 1
Has a cylindrical shape in which the upper surface side is closed by the heating unit 2 and the lower surface side is open, and the flat upper surface of the heating unit 2 is wider than a thin plate-shaped heating object such as a silicon wafer. The lower edge portion of the heated object support member 1 is fixed to the upper surface of the stage section 7 by being applied thereto, and is hermetically sealed by a vacuum seal material 8.

The heating member support member 1 as a whole or at least the heating portion 2 is made of silicon-impregnated silicon carbide, ceramic such as alumina, silicon nitride or the like. When the heating object support member 1 is made of an insulator such as ceramic, a conductor film is formed on the inner surface of the heating unit 2, and the conductor film is grounded via the stage unit 17. An exhaust passage 4 is formed in the stage section 17, and a space inside the heated object support member 1 is evacuated and evacuated by a vacuum pump 5 connected to the exhaust passage 4. Further, a filament 9 and a reflector 3 are provided inside the heated object support member 1.

The filament 9 is provided behind the heating section 2 of the heated object support member 1, and a filament heating power supply 10 is connected to the filament 9 via an insulating seal terminal 16. Further, an acceleration voltage of the electron acceleration power supply 11 is applied between the filament 9 and the heating section 2 via the stage section 17 and the heated object support member 1.
In the case shown, the electron acceleration power supply 11 is connected between the junction 6 of the stage 17 and the filament 9 side of the filament heating power supply 10. The heating section 2 is grounded via the heated object support member 1 and the stage section 17, and is kept at a positive potential with respect to the filament 9.

The reflector 3 is provided behind the filament 9 with respect to the heating section 2 of the heating object supporting member 1.
The reflector 3 is formed of a metal having a high reflectivity such as gold or silver, or a metal having a high melting point such as molybdenum.
It is a mirror surface and reflects infrared rays. The reflector 3 is electrically insulated from the heated object support member 1 but is kept at substantially the same potential as the filament 9. As a result, electrons do not fly to the reflector 3 and heating by electron impact does not occur. Such filaments 9 can be arranged in multiple layers.

At the center of the reflector 3, a shield 15 made of a cylindrical conductor is erected.
5 and the reflector 3 are electrically connected to each other and have the same potential. The upper end side of the shield 15 reaches near the lower surface of the heating section 2 of the heated object support member 1, and a flange 18 extends outward from the upper end of the shield 15, and the flange 18 faces the lower surface of the heating section 2. ing.

A sheath-type thermocouple 12 as a temperature measuring element is vertically inserted from the center of the stage 17, and its upper end is disposed in the shield 15 in a non-contact state. The upper end of the thermocouple 12 is a temperature measuring point where a pair of thermocouple wires are joined, and the junction is embedded in a disc-shaped heat receiving plate 13 having good heat conduction. This heat receiving plate 13
It is fixed to the sheath of the thermocouple 12 and faces or is in contact with or near the lower surface of the heating section 2 of the heating object support member 1 in a non-contact state. The thermocouple 12 is drawn out of the vacuum chamber from the stage section 17, and its compensating lead wire 14 shown in FIG. 1 is connected to a temperature measuring device including a zero-point compensation circuit shown in FIG.

In such a plate heating apparatus, as shown in FIG. 1, a flat plate-like heating object such as a silicon wafer is placed on the flat upper surface of the heating section 2 of the heating object support member 1. . In this state, the internal space of the heated object support member 1 is depressurized to a vacuum. Next, the filament 9 as a heating means
Then, a thermoelectron is emitted from the filament heating power supply 10 and is caused to collide with the lower surface of the heating section 2 of the heating object support member 1 by the acceleration voltage applied by the electron acceleration power supply 11. The heating portion 2 of the heated object support member 1 is heated by the electron impact energy, and the heated object placed on the upper surface of the heated portion 2 is heated.

At this time, since the inside of the heated object support member 1 is a vacuum space, heat is not released from the heating portion 2 of the heated object support member 1 to the back thereof by convection, but heat is radiated. Only release occurs. The radiant heat radiated to the rear of the heating unit 2 is reflected by the reflector 3 toward the heating unit 2 of the heating object support member 1, so that the release of heat to the rear surface of the reflector 3 is prevented, and Heating can be performed efficiently. Thereby, the heating object can be heated to a high temperature in a short time.

At this time, the heat receiving plate 13 receives the temperature of the heating object a through the heating unit 2 in a non-contact or contact state, and a thermoelectromotive force is generated by the thermocouple 12, and the temperature is measured by the electromotive force. Measure the temperature with the instrument. The measured temperature value is fed back to a control circuit for controlling the filament heating power supply 10 and the electron acceleration power supply 11 of the filament 9, whereby the heating of the heating object a is controlled to a desired temperature.

FIG. 2 shows an example of a power supply circuit having a filament heating power supply 10 for supplying a filament heating current to the filament 9, an electron acceleration power supply 11 for applying an acceleration voltage between the filament 9 and the heating section 2, and a control circuit therefor. Is shown. The electron accelerating power supply 11 transforms a commercial 200 V power supply by a transformer and rectifies it by a rectifier, and applies an acceleration voltage of 1 to 2 kV between the filament 9 and the heating unit 2. Also,
The filament heating power supply 10 transforms a voltage from the commercial 200 V power supply by a transformer via a noise filter, and supplies a filament current to the filament 9. At this time, a control current is given to the gate of the triac through the isolation amplifier, comparator and driver,
Controlling the filament current. In the comparator,
The temperature measurement value measured by the thermocouple 12 is fed back, and the temperature measurement value is compared with the temperature measurement value measured before and the temperature to be controlled in the comparator, and the filament current supplied to the filament 9 is controlled based on the result. Is done. Thereby, the filament current is controlled so that the heating object a is heated to a desired temperature.

In the above example, a thermocouple is used as a temperature measuring element, but a thermocouple made of, for example, a platinum wire and a platinum rhodium wire is used. The heat receiving surface of the heat receiving plate 12 facing the back side of the heating unit 2 may be subjected to a surface treatment for increasing the emissivity. For example, as a surface treatment for increasing the emissivity of the heat receiving surface 6 of the heat receiving plate 12, a platinum black treatment can be given.

Further, as a temperature measuring element, in addition to a thermocouple,
A temperature measuring resistor or the like may be used, and the temperature measuring element may be either non-contact or contact with the heating section 2 of the heated object support member 1. When non-contact, highly reactive S
This is advantageous in that a chemical change does not occur in the heating section 2 of the heating object support member 1 made of i-impregnated SiC or the like, and further, a temperature drop of the heating section due to contact does not occur. On the other hand, when contact is made, it is possible to measure the absolute temperature of the heating section.

[0026]

As described above, according to the present invention, while the filament 9 and the temperature measuring element of the temperature measuring element are both arranged behind the heating section 2, electrons collide with the temperature measuring element. Can be prevented. Furthermore, since there is no electron impact on the shield 15, the temperature rise of the temperature measuring element due to the electron impact can be prevented, and the temperature of the heating unit 2 can be accurately measured. The heating current and the accelerating voltage of the filament 9 can be controlled by the temperature measured by the temperature measuring element, whereby the temperature of the heating object a can be controlled to a desired temperature with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a plate heating apparatus and a plate processing apparatus using the same according to the present invention.

FIG. 2 is a circuit diagram showing a power supply circuit and a control circuit of the plate heating device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heated material support member 2 Heated material support member heating part 3 Reflector 9 Filament 10 Filament heating power supply 11 Electron acceleration power supply 12 Thermocouple 15 Shield 18 Shield flange a Heated material

Claims (4)

(57) [Claims] 1. A plate heating apparatus for heating a thin flat plate-shaped heating object (a) placed on a heating section (2) for heating the heating object (a) from the back side thereof. a) a heat-resistant heating member support member (1) having a flat heating portion (2) on which the heating member (2) is placed, and a heat source supporting member (1) provided in a space behind the heating portion (2); A filament (9) for generating electrons, an electron accelerating power supply (11) for causing thermal electrons generated by the filament (9) to collide with a heating section (2) of the heated object support member (1), and the heated object support member (1) a reflector (3) that reflects radiant heat generated from the heating section (2) and is electrically independent of the filament (9) and the heating section (2); and a reflector (3) behind the heating section (2). A temperature measuring element in which a measuring point is arranged in a space, and surrounding the temperature measuring element and its measuring point, A plate heating device comprising a reflector (3) and a cylindrical shield (15) maintained at the same potential. 2. A flange (18) at an end of the shield (15) near the heating portion (2) of the heating member support member (1) facing outward so as to face the back surface of the heating portion (2). The plate heating device according to claim 1, wherein the plate is extended. 3. A measuring point of the temperature measuring element is attached to a heat receiving plate (13) having good heat conduction, which is opposed to and close to the back surface of the heating section (2) of the heating object supporting member (1). The plate heating apparatus according to claim 1 or 2, wherein: 4. A power supply control circuit for controlling a filament heating current of a filament heating power supply (10) of a filament (9) by feeding back a temperature measured value by a temperature measuring element.
3. The plate heating device according to any one of 3.