JP3045860B2 - Heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus used for plasma CVD, low pressure CVD, plasma etching, optical etching, sputtering, and the like.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus requiring a super clean state, a corrosive gas such as a chlorine-based gas or a fluorine-based gas is used as a corrosive gas, an etching gas, or a cleaning gas. Therefore, as a heating device for heating the wafer in contact with these corrosive gases, the surface of the resistance heating element is made of stainless steel,
When a conventional heater coated with a metal such as Inconel is used, undesired particles having a particle size of several μm such as chlorides, oxides and fluorides are generated by exposure to these gases.

[0003] Therefore, an infrared lamp is installed outside the container exposed to the deposition gas or the like, an infrared transmission window is provided on the outer wall of the container, and infrared rays are radiated to a heated body made of a material having good corrosion resistance such as graphite. A wafer heating apparatus of an indirect heating method for heating a wafer placed on an upper surface of an object to be heated has been developed. However, in this method,
The heat loss is large compared to the direct heating type, the temperature rise takes time, and the attachment of the CVD film to the infrared transmission window gradually impedes the transmission of infrared light, causing heat absorption in the infrared transmission window. There were problems such as overheating of windows.

[0004] To solve the above problem, the present inventor has
For example, a disk-shaped substrate was made of silicon nitride or the like, and at this time, a ceramic heater was manufactured by burying a resistance heating element inside the disk-shaped substrate.

[0005]

However, it has been found that the temperature measurement becomes difficult when the above-mentioned disk-shaped ceramic heater is used. That is, in a thermal CVD apparatus or the like, the pressure in the container fluctuates greatly. Further, it is necessary to attach one end of a thermocouple to the surface of the ceramic heater and control the temperature of the heater while detecting the temperature. Such a heating device does not have a major problem when used at a normal constant pressure, but when the pressure inside the container is changed, a malfunction may occur in the thermocouple, and an accurate heater temperature may be obtained. The problem arises that the control cannot be performed.

The present inventor has conducted various studies on the cause of such malfunction of the thermocouple and obtained the following knowledge. That is, when a thermocouple is inserted into the hole of the ceramic heater, the heat transfer between the heater and the thermocouple depends on the gas that changes in pressure. In particular, in a vacuum, the behavior of gas molecules around the thermocouple is in a viscous flow region in a vacuum state from atmospheric pressure to 1 torr, but moves to a molecular flow region when the degree of vacuum is increased. Since the manner of heat transfer in the surroundings changes significantly, accurate temperature measurement cannot be performed. It was also found that, even in the viscous basin, if the pressure fluctuation was large, there was a temperature measurement error.

In order to solve such a problem, the present inventor has developed a technique in which a thermocouple is housed inside a hollow sheath (sheath) and the tip of the hollow sheath is glass-bonded to the back surface of the ceramic heater (Japanese Patent Application No. Hei 10-26139). 2-17322). Thereby, since the thermocouple is not exposed to the atmosphere in the container, stable temperature measurement and detection can be performed. However, it is difficult to form the hollow sheath with molybdenum or the like, and particularly difficult to sharpen the tip of the hollow sheath. To join the tip of the hollow sheath to the ceramic heater, manufacture the glass powder, fix the hollow sheath,
There were many complicated steps such as melting glass by heating at about 1500 ° C., making production difficult and low in productivity.

Further, the present inventor made a cylindrical body using a silicon nitride sintered body or the like, bonded the cylindrical body to the back of the ceramic heater by glass, and installed a thermocouple in the inner space of the cylindrical body ( Japanese Patent Application No. 3-84575). However, such cylindrical bodies are expensive to manufacture. In addition, both the cylindrical body and the heater material are ceramics, and both need to be glass-bonded, but it has been difficult to glass-bond with sufficient strength. Further, many steps as described above are required for glass bonding, and the productivity is low.

An object of the present invention is to provide a heating apparatus capable of stably measuring and controlling the temperature of a ceramic heater, and which can be efficiently produced without requiring any special glass joining technology or the like. That is.

[0010]

According to the present invention, there is provided a base made of dense ceramics; a resistance heating element buried inside the base; connected to an end of the resistance heating element and exposed to the surface of the base. A terminal having a concave portion; made of a heat-resistant metal;
The present invention relates to a heating device including a cylindrical body having a tip inserted and fixed in the concave portion; a power supply for supplying power to the cylindrical body; and a temperature measuring device fixed inside the cylindrical body.

[0011]

FIG. 2 is a schematic sectional view showing a state in which a heating apparatus according to an embodiment of the present invention is mounted on a container of a semiconductor manufacturing apparatus. FIG. 1 is an enlarged sectional view of a main part of the heating apparatus. In this example, the flange 6 is installed on the upper side of the container body 20,
A support 19 extends below the flange 6. Support
The ceramic heater 1 is supported by 19.
The back surface 1a of the heater 1 faces the flange 6, and the heating surface 1b faces the inside of the container. The container body 20 and the flange 6 are hermetically sealed by the O-ring 13.

For example, the disk-shaped substrate 21 is made of dense ceramics. The resistance heating element 3 is embedded in the base 21. The resistance heating element 3 can be buried in a spiral shape in a plan view, for example. Terminals 4 are respectively connected to both ends of the resistance heating element 3. The shape of the terminal 4 may be a column, a square, a hexagon, or the like. Terminal 4 front surface 1a
Exposed to the side. For example, a flat circular recess 4b is formed near the center of the terminal 4, and a female screw is formed so as to face the recess 4b.
4a is formed.

The cylindrical body 5 is made of a heat-resistant metal. The tip 5a of the cylindrical body 5 has a slightly smaller diameter, and the tip 5a
Is formed with a male screw 5b, and the tip is a bag tube.
Set the cylindrical body 5 almost perpendicular to the back surface 1a,
5b is screwed into female screw 4a. The flange 6 is provided with a through hole 6a.
Is installed, and the seal cap 14 is installed on the insulating material 12. The space between the flange 6 and the insulating material 12 and the space between the insulating material 12 and the seal cap 14 are hermetically sealed by an O-ring 13, and the through holes 6a and 12a are aligned. A notch 14a is formed above the seal cap 14, and the O-ring 13 is accommodated therein. The cylindrical body 5 extends through the through holes 6a and 12a, further inside the seal cap 14, and above. A presser piece 16 is inserted above the notch 14a, and a presser 15 is installed on the presser piece 16.
The presser 15 and the seal cap 14 are screwed together, and the pressure applied to the O-ring 13 is adjusted by rotating the presser 15.

A female screw 5c is formed on the inner periphery of the upper end of the cylindrical body 5, and a male screw of the seal member 9 is screwed to the female screw 5c. Near the center of the inner space 7 of the cylindrical body 5, an elongated temperature measuring device 8 is fixed. The tip of the temperature measuring device 8 is inserted into the inner space 5d of the tip 5a. In this example, the temperature measuring device 8 includes a thermocouple and a sheath surrounding the thermocouple. Lead 10 on the upper side of sealing member 9
And a pair of lead wires 11 is accommodated inside the lead 10. Each of the lead wires 11 is connected to one of the thermocouples. A lead wire 17 is connected to the outer periphery of the upper end of the cylindrical body 5, and a pair of lead wires 17 is connected to an AC power supply 18.

When the ceramic heater is operated, the AC power supply 18 is turned on, and power is supplied to the resistance heating element 3 via the lead wire 17, the cylindrical body 5, and the terminal 4. Also,
In the inner space 5d, the amount of heat reaching the tip of the thermocouple is detected, and thereby the temperature of the ceramic heater is measured. Although this detection value has a slight difference from the surface temperature on the heating surface 1b, controlling the temperature on the heating surface 1b on the basis of this detection value may be a problem in terms of the temperature stability of the heater. In this embodiment, since the temperature measuring device 8 is accommodated inside the cylindrical body 5, the atmosphere around the thermocouple is not affected by the pressure change in the container. For this reason, for example, even if the pressure in the container is reduced to a high degree of vacuum or the gas for CVD is suddenly supplied, the thermocouple is not affected. Therefore, stable temperature measurement can always be performed in correspondence with the actual calorific value of the ceramic heater. Further, the calorific value of the ceramic heater can always be accurately controlled without being affected by the pressure fluctuation in the container.

A terminal 4 made of a heat-resistant metal and a cylindrical body 5
Can be mass-produced by metal working. And, unlike the case of glass joining of ceramics, it is easy to increase the joining strength of both members, and a complicated glass joining step is not required.

As the material of the base 21, silicon nitride, sialon, aluminum nitride and the like are particularly preferable. The material of the resistance heating element 3 and the terminal 4 is preferably a high melting point metal such as platinum, molybdenum, tungsten, and nickel. The cylindrical body 5 can be formed of molybdenum, tungsten, nickel, inconel, or the like. Inconel, which is easy to process and is stable to the atmosphere, is particularly preferable. Since the atmosphere is present inside the cylindrical body 5, when the opening of the cylindrical body 5 is sealed with the sealing member 9, new oxygen does not enter and the cylindrical body 5 and the temperature measuring device 8 are hardly corroded. The space between the cylindrical body 5 and the temperature measuring device 8 is filled with magnesium oxide or the like to insulate it. The insulating property is preferably 1 MΩ or more in order to avoid mixing and induction of the thermocouple by the heater control power supply.
Similar effects can be obtained even when the temperature measuring device 8 is a sheath thermocouple.

When the female screw 4a and the male screw 5b are screwed and fitted together, the contact area between the female screw 4a and the male screw 5b is increased. It becomes difficult to invade. As a result, the heat transfer between the terminal 4 and the tip 5a is particularly advantageous because the contact heat transfer is dominant. Although the contact heat conduction at the time of screw fitting is effective, it is impossible to form a female screw on the ceramic base material when the size is as small as M3 or the like. In the present invention, since the electrode terminal is made of a metal body, processing is possible. As described above, by performing the power supply and the temperature measurement simultaneously at the electrode body, sufficient contact heat conduction is realized. The female screw 4a of the terminal 4
Can be provided by electric discharge machining.

The tip 5a can be pressed into the recess 4b. In this case, the female screw 4a and the male screw 5b are not provided. In this case, a metal foil may be interposed between the tip 5a and the recess 4b. Further, after the above screwing or press fitting is performed, a molten material of a high melting point metal can be poured between the wall surface of the concave portion 4b and the tip portion 5a to close the gap.
Such a high melting point metal used as a brazing material is Mo.
, Pd, Ni, Fe, Co, Mn, Au, Pt, Y, Ag, Cu,
Examples include Zr, Cr, Nb, Ti, V, and Ta. Tip 5
In order to connect a with the recess 4b, there is a method of using a caulking method, or a method of mechanically pressing with a spring or an elastic board.

The shape of the cylindrical body 5 may be changed to a square cylinder, a hexagonal cylinder, or the like. The shape and structure of the temperature measuring device 8 can also be changed. In the example of FIG. 2, the temperature is measured at two places. However, the temperature may be measured at one place or at three or more places.

FIG. 3 is a sectional view of a main part showing another embodiment of the present invention. The same members as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof may be omitted. In this embodiment, the cylindrical insulator 22 is installed substantially concentrically with the cylindrical body 5 so as to surround the outside of the cylindrical body 5. The tip of the insulator 22 is brought into contact with the back surface 1a. A lid 25 is provided on the insulating material 12, and the space between the lid 25 and the insulating material 12 is sealed by an O-ring 13. A cylinder 26 is attached to the inner peripheral surface of the through hole of the lid 25, and a seal cap 14A is attached to the inner peripheral surface of the upper end of the cylinder 26. The O-ring 13 is housed inside the seal cap 14A. The cylindrical body 5 extends through the inside of the seal cap 14A and above. Presser piece 16 inside seal cap 14A
A is inserted, and the holding tool 15A is installed on the holding piece 16A. Holder 15A and seal cap 14A
The pressure applied to the O-ring 13 is adjusted by rotating the presser 15A.

The insulator 22 is inserted into the cylinder 26 through the through holes 6a and 12a and further through the through hole of the lid 25. Upper end of insulator 22 and seal cap
There is a slight gap between the lower end of 14A. A purge port 24 is provided on the seal cap 14A. A cooling flange 23 is attached to the outer periphery of the upper end of the cylindrical body 5. Cooling water is supplied to the cooling flange 23 as shown by arrow B. When an inert gas such as an argon gas flows from the purge port 24 as shown by an arrow A, the inert gas flows downward between the insulator 22 and the cylindrical body 5, and a gap between the back surface 1a and the tip of the insulator 22 is formed. Blow out as shown by arrow C.

According to this embodiment, in addition to the same effects as those of the above-described embodiment, the following effects can be obtained. That is, particularly in a metal CVD apparatus, the CVD gas may flow around the back surface 1a, and a metal film may be deposited on the back surface 1a. In this case, between two or more cylindrical bodies 5,
The insulation between the cylindrical body 5 and the case is reduced, and discharge and ground fault may occur. In this regard, in this example, the insulator 22
In addition to ensuring insulation, the inert gas is blown out from the contact portion between the insulator 22 and the heater back surface 1a to prevent the deposition gas from diffusing inside the insulator 22. This prevents the insulating property from being reduced due to the formation of the metal film and the corrosion of the cylindrical body 5 due to the deposition gas. Since the temperature is measured around the terminal 4, the insulator 22 is preferably formed of a material having low thermal conductivity, for example, quartz glass, alumina or the like. The amount of the inert gas such as argon gas introduced from the purge port 24 is preferably determined according to the degree of vacuum in the CVD apparatus and the diffusivity of the gas. It is preferable that the blowing amount of the inert gas from the contact portion be 1 m / sec or more at the gas flow rate.

[0024]

According to the present invention, the terminal is provided with the concave portion, the tip of the cylindrical body made of heat-resistant metal is inserted and fixed in the concave portion, and power is supplied to the cylindrical body. Then, the temperature measuring device is fixed inside the cylindrical body. Therefore, the atmosphere around the temperature measuring device is not affected by the pressure change in the container. For this reason, for example, even if the pressure in the container is reduced to a high vacuum or the gas is suddenly supplied, the temperature measuring device is not affected. Therefore, stable temperature measurement can always be performed in correspondence with the actual calorific value of the ceramic heater. Further, the calorific value of the ceramic heater can always be accurately controlled without being affected by the pressure fluctuation in the container. Also, heat-resistant metal terminals and cylindrical bodies are
Mass production by metal processing. And, unlike the case of glass joining of ceramics, it is easy to increase the joining strength of both members, and a complicated glass joining step is not required.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a heating device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a state where the heating device of FIG. 1 is attached to a container.

FIG. 3 is an enlarged sectional view of a main part of a heating device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic heater 3 Resistance heating element 4 Cylindrical terminal 4b Recess 5 Cylindrical body 5a Tip 5d, 7 Inside space 8 Temperature measuring device 18 AC power supply 21 Disc-shaped base 22 Insulator 24 Purge port A, C Flow of inert gas

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-68924 (JP, A) JP-A-4-63281 (JP, A) JP-A-4-296485 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/31 H01L 21/365 H05B 3/20 356

Claims (1)

(57) [Claims] 1. A base made of dense ceramics; a resistance heating element embedded in the base; a terminal connected to an end of the resistance heating element and exposed on the surface of the base and having a recess; A heating device comprising: a cylindrical body having a tip inserted and fixed in the recess; a power supply for supplying power to the cylindrical body; and a temperature measuring instrument fixed inside the cylindrical body.