JP3131010B2 - Semiconductor wafer 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 plasma CVD, low pressure CV
D, which relates to a semiconductor wafer heating apparatus used for plasma etching, optical etching apparatus 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. Further, a so-called indirect heating type semiconductor wafer heating apparatus has been developed. However, this type has a larger heat loss than the direct heating type, takes longer time to raise the temperature, and has a CV to the infrared transmission window.
Due to the adhesion of the D film, transmission of infrared rays is gradually hindered, and there is a problem that heat absorption occurs in the infrared transmission window and the window is overheated.

[0003]

In order to solve the above-mentioned problems, the present inventors embed a resistance heating element in a disk-shaped dense ceramic, and hold the ceramic heater in a graphite case. Was considered. As a result, it has been found that this heating device is an extremely excellent device that has eliminated the problems described above. However, in such a heating device, it is necessary to attach electrodes and terminals for power supply, thermocouples, and the like to the back side of the disc-shaped ceramic heater. When these metal members are exposed to a high-temperature corrosive gas, they are corroded. Also,
When a conductive film gradually accumulates on the rear surface of the ceramic heater, electric discharge or electric leakage occurs between the pair of electrodes and between the electrodes and the case. An object of the present invention is to prevent corrosion of power supply electrodes and terminals, thermocouples, and the like, and to prevent discharge and leakage between electrodes.

[0004]

SUMMARY OF THE INVENTION The present invention provides a ceramic heater in which a resistance heating element is embedded in a disk-shaped substrate made of dense ceramics, and a cylindrical heater made of dense ceramics, both ends of which are open. Body, a soft metal annular member provided between the board-shaped substrate and an end face of the tubular body, a support member for supporting a side peripheral surface of the ceramic heater, and the tubular body A pressing member for pressing the plate-shaped substrate and the cylindrical body against the annular member so that the space between the disk-shaped substrate and the cylindrical body can be hermetically sealed. Configured in the
The present invention relates to a semiconductor wafer heating device.

[0005] In the above semiconductor wafer heating apparatus,
It is particularly preferable that the pressing member is a spring that is substantially in a constant temperature state, and that the cylindrical body is pressed toward the board-like substrate by using a compression load or a tensile load of the spring. Here, "substantially in a constant temperature state" refers to a state in which the ambient temperature of the spring is kept substantially constant, and therefore, the spring constant of the spring is kept substantially constant.

[0006]

FIG. 1 is a sectional view showing a state in which a heating device of the present embodiment is attached to a semiconductor manufacturing apparatus. The container 17 is provided with through holes 15 and 16, and the heating device of the present embodiment is installed in the internal space 14 of the container 17. On the upper wall surface of the container 17, a circular through hole 20A and a water cooling jacket 18 are provided. The cylindrical body 6 is made of dense and gas-tight ceramic,
It comprises a cylindrical main body 6c and an annular flange 6a provided at the end of the main body 6c. The main body 6c is inserted into and fixed to the circular through hole 20A, and the main body 6c and the container 17 are hermetically sealed by the O-ring 8.

The substantially disc-shaped ceramic heater 1 comprises a substantially disc-shaped base 2 and a resistance heating element 3 embedded inside the base 2. The base 2 is made of a dense and gas-tight ceramic. The resistance heating element 3 is embedded, for example, in a spiral shape, and both ends of the resistance heating element 3 are connected to terminals 12.
It is connected to. The surface of each terminal 12 is the rear surface 2b of the base 2.
A round bar-shaped electrode 9 is connected to the exposed surface of each terminal 12 and a lead wire 10 is connected to the end of each electrode 9.
The tip of the thermocouple 11 is fixed to the back surface 2b of the base 2.
The electrode 9 and the thermocouple 11 extend vertically in the inner space 6b of the cylindrical body 6. An annular flange is provided on the outer peripheral surface of the base 2.
2a is formed, a flange 4a is formed on the lower inner peripheral surface of the support member 4, and the flange 2a is placed on the flange 4a. The holding plate 5 is installed on the supporting member 4, and the supporting member 4 and the holding plate 5 are fastened with bolts or the like.

The main body 6c is inserted into the circular through hole 5a of the holding plate 5, and the flange 6a is in contact with the lower surface of the holding plate 5. An annular member 7 is provided between the flange 6a and the surface of the base 2. The cross section in the width direction of the annular member 7 is circular,
Made of soft metal. The holding plate and the support member 4 are fastened by tightening the bolt 22 as a pressing member, a load is applied between the base 2 and the cylindrical body 6, and the annular member 7 is moved against the flange 6a and the back surface 2b. Press and seal hermetically. Thereby, the ventilation between the gap 13A and the inner space 6b is substantially blocked.

The ceramic heater 1 can be manufactured by hot press sintering and normal pressure sintering. The cylindrical body 6 can be manufactured by injection molding or extrusion molding, press molding, isostatic press molding, and normal pressure sintering.

According to the heating apparatus of this embodiment, it is possible to solve the problems of contamination as in the case of the conventional metal heater and deterioration of the thermal efficiency as in the case of the indirect heating method. Further, since the electrodes 9 and the terminals 12 are not exposed to the atmosphere of the internal space 14 of the container, corrosion of the electrodes 9 and the like, contamination from the electrodes 9, and further, between the electrodes in a vacuum or between the electrodes and the container 17. There is no risk of electric discharge and leakage.

According to the study of the present applicant, especially in a vacuum, the behavior of gas molecules around a thermocouple is between atmospheric pressure and atmospheric pressure.
In the state of 1 torr, it is in the viscous flow area, but when the degree of vacuum is increased, it shifts to the molecular flow area, and the mode of heat transfer in the thermocouple changes drastically. ing. It is also known that a temperature measurement error exists in a viscous flow area when the pressure fluctuation is large. In this regard, in the present embodiment, since the thermocouple 11 is not exposed to the atmosphere in the container, the above-described problem of the temperature measurement error does not occur.

It is important that the cylindrical body 6 and the ceramic heater 1 can be sealed by the annular member 7 made of a soft metal, so that the sealing becomes very easy and stable. The present inventor also studied glass joining of the ceramic heater 1 and the cylindrical body 6, but it is quite difficult in manufacturing to increase the joining strength of the two and prevent cracking or destruction of the joining portion. I understand. This is because thermal stress concentrates on the glass joint. Also, in order to perform such glass bonding, generally,
Heat treatment at a temperature of 1400 ° C. or higher is required, but at this time, there is an adverse effect such as deterioration of the tungsten wire.

Although the use of rubber O-rings has been considered, the upper limit of the operating temperature is at most 300 ° C., which limits the use to low-temperature applications. In addition, with Inconel or stainless metal O-rings or metal C-rings, it is difficult to hermetically seal ceramics, and when a large load is applied to improve airtightness, cracks may occur in the ceramics.

Further, since the cylindrical body 6 and the ceramic heater 1 are separate bodies, if a failure such as a crack occurs in either of them, it is possible to separate them and replace only the failed one. it can. When the cylindrical body 6 and the ceramics heater 1 are glass-bonded, cracks are easily formed in the bonded portions, and once cracks are formed, they must be replaced at once. In addition, since the soft metal annular member 7 has a stress relaxing action, it is possible to absorb the thermal stress of each member. Further, by adjusting the fastening force of the bolt 22, the annular member 7
Can be changed, and accordingly, the sealing performance of the annular member 7 can be appropriately changed.

As the soft metal constituting the annular member 7, platinum having high corrosion resistance and high melting point is most preferable. In addition, nickel, silver, and gold are preferable in terms of corrosion resistance. Copper can adversely affect semiconductors.

As the material of the base 2 and the cylindrical body 6, silicon nitride, sialon, aluminum nitride and the like are preferable, and silicon nitride and sialon are more preferable in terms of thermal shock resistance. Aluminum nitride is most preferable in terms of corrosion resistance to halogen-based corrosive gas. The material of the resistance heating element 3 is preferably tungsten, molybdenum, platinum or the like. Sealing between the container 17 and the cylindrical body 6 is performed by diffusion bonding, friction welding, friction welding with a metal thin film provided on the surface by sputtering, glass welding, metal backing, etc. in addition to the O-ring shown in FIG. Can be.

The annular member 7 can be easily manufactured, for example, as shown in FIG. First, as shown in FIG. 2 (a), a wire 7A made of a soft metal is prepared, and as shown in FIG. 2 (b), the wire 7A is processed into a circular shape and both ends are spot-welded. In the figure, reference numeral 23 denotes an expanded portion due to welding. Then
The expanded portion is scraped off to obtain the annular member 7 shown in FIG.

As shown in FIG. 3, a ring-shaped groove 19 can be formed on the lower end surface of the flange 6a. The cross-sectional shape in the width direction of the groove 19 is rectangular, and the annular member 7 is provided in the groove 19.
Houses the upper half of the

FIG. 4 shows a heating device according to another embodiment in a container.
FIG. 17 is a cross-sectional view showing a state of being attached to 17. The same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, a cylindrical body 26 having a relatively large width is used. An annular support flange 26d extending outward is provided at the upper end of the cylindrical main body 26c. An annular flange 26a is also provided at the lower end of the cylindrical main body 26c to project therefrom. Container 17
A circular through hole 20B is provided in the upper wall surface of the
c is inserted through the circular through hole 20b, and the support flange 26d is bridged over the upper wall surface of the container 17. Support flange 26d
The space between the container and the container 17 is hermetically sealed by an O-ring 8.

A holding plate 21 is fastened to the upper end of the support member 4 by bolts 22, and the holding plate 21 is supported on the flange 26a. An annular member 7B is provided between the flange 26a and the back surface 2b, thereby providing an airtight seal between the inner space 26b and the gap 13B.

In this embodiment, in addition to the above effects,
The following effects can be obtained. (1) Since the diameter of the tubular body 26 is large and is comparable to the diameter of the base 2, the load is dispersed and the ceramic is hardly broken. (2) In the case of a thermal CVD apparatus, it is necessary to clean a CVD film deposited on a part other than a semiconductor wafer with plasma.
In this case, since the plasma electrode can be arranged in the inner space 26b, the plasma electrode is not exposed to the gas atmosphere in the container. (3) By installing a cooling structure in the inner space 26b,
Responsiveness during cooling can be improved. (4) By providing heat insulation and cooling means in the inner space 26b in accordance with the temperature distribution on the chuck surface of the semiconductor wafer,
The temperature distribution on the chuck surface can be controlled.

The heating device shown in FIG. 1 was manufactured. The annular member 7 was formed of platinum, the base 2, the cylindrical body 6, the support member 4, and the holding plate 5 were formed of silicon nitride, and the resistance heating element 3, the terminal 12, and the electrode 9 were formed of tungsten. The pressure in the container 17 was set to 1 × 10 ^-4 mmHg,
C., and a helium gas was flown into the inner space 6b to perform a leak test. The leak amount was 6.5 × 10 ⁻⁹ atm · cc / sec or less.

In each of the above examples, the substantially disk-shaped substrate 2
The shapes of the cylindrical body 6 and the cylindrical body 26 can be variously changed, and accordingly, the planar shapes of the annular members 7, 7B can also be variously changed. Further, the outer shape of the cross section in the width direction of the annular members 7, 7B can be changed to a ring shape, a C-shape, or the like.

FIG. 5 is a sectional view schematically showing a state in which a semiconductor wafer heating apparatus according to another embodiment of the present invention is mounted on a container 17. In this embodiment, a flange 27a is provided on the inner peripheral surface of the lower end of the support member 27, and the flange 27b on the outer peripheral surface of the upper end of the support member 27 is fixed to the container 17 with bolts 22. The flange 2a of the disk-shaped substrate 2 is supported on the flange 27a via an annular heat insulating material 30A. Flange
A heat insulating material 30B is interposed between the outer peripheral surface of 2a and the support member 27. The heat insulating materials 30A and 30B are preferably formed of alumina or the like.

A through hole 20C is provided in the wall surface of the container 17, and a cylindrical projection 28 extends upward so as to surround the through hole 20C. A cylindrical body 6 is provided above the back surface 2b of the disc-shaped base 2, and the space between the flange portion 6a and the back surface 2b is sealed by an annular member 7. The cylindrical body 6 extends through the through hole 20C to a position above the projecting portion 28. An O-ring 8A hermetically seals the space between the inner periphery of the upper end of the projecting portion 28 and the outer peripheral surface of the cylindrical body 6, and a cooling jacket 29 is provided so as to surround the outer periphery of the projecting portion 28. In this embodiment, a female screw is formed on the terminal 12A, and a male screw is formed on the tip of the round rod-shaped electrode 9.
The female screw and the male screw are screwed together. In addition, thermocouple 11A
Is fixed to the back surface 2b side.

A plurality of shafts 31, preferably a plurality of shafts, are fixed to the upper wall surface of the container 17 by screwing or the like. A through hole 34a is provided at a predetermined position of the base plate 34, and each through hole 34a
Through the shaft 31 respectively. A female screw (not shown) is provided on a part of the shaft 31, a nut 32 is fitted on the female screw (not shown), and a disc spring is provided between the nut 32 and the base plate 34.
Fix 33. A circular inner plate 35 is installed inside the base plate 34, and the electrode 9 is inserted into a through hole of the inner plate 35.
And the thermocouple 11A is inserted, and the space between the electrode 9 and the thermocouple 11A and the inner plate 35 is sealed with an O-ring 8C.

A hemispherical seat 36a is formed on the upper end surface of the jig 36, and the seat 36a is brought into contact with the center of the inner plate 35. The electrode 9 and the thermocouple 11A pass through the inside of the jig 36, and a cylindrical recess 36b is provided in the lower half of the inner peripheral surface of the jig 36. Hollow 36b
The upper end of the cylindrical body 6 is accommodated in the inside, and a cushioning material 37 made of a soft metal is sandwiched between the upper end surface of the cylindrical body 6 and the jig 36. The space between the outer peripheral surface of the cylindrical body 6 and the inner peripheral surface of the lower end of the jig 36 is hermetically sealed with an O-ring 8. The cooling jacket 29 is installed so as to surround the outer periphery of the lower half of the jig 36.

The nut 32 is tightened to apply a compressive load to the disc spring 33 to press the base plate 34 and the inner plate 35 downward, thereby pushing the ball seat 36a downward. This pressing force is transmitted to the annular member 7 and the back surface 2b via the jig 36, the cushioning material 37, and the cylindrical body 6. Shaft 31 and support member 27
Are fixed to the container 17 together.

According to this embodiment, the effects described in the example of FIG. 1 can be obtained. Moreover, it is important that the disc spring 33 as the pressing member is located outside the container 17. That is, even when the temperature of the ceramic heater 1 is increased, the elastic restoring force of the disc spring 33 does not substantially change because the disc spring 33 is outside the container. Therefore, even when the ceramic heater 1 generates heat, the pressure applied to the annular member 7 does not change much, and accordingly, the sealing performance can be maintained.

It is important that the inner plate 35 and the jig 36 are formed separately. That is, assuming that these are integrated, if the stress applied by the disc spring 33 is not evenly distributed in the circumferential direction as viewed in plan, a large uneven load (bending) is applied to the end face of the ceramic cylindrical body 6. (Stress, shear stress) may be applied directly, and the cylindrical body 6 may be broken. Also, when the plates 34 and 35 and the jig 36 are separated, if the two members are brought into solid contact in a plane, if the contact surfaces are not machined with very high precision, the contact between the flat surfaces An eccentric load will be applied depending on the tolerance of the part. Such high-precision processing is difficult and expensive. In this embodiment, the above-mentioned problem is solved by forming the jig 36 separately from the plate and by temporarily concentrating the load on the ball seat 36a at the center of the jig 36.

A cushioning material made of copper, gold, nickel, etc.
By bringing the 37 into contact with the end face of the cylindrical body 6, the unbalanced load applied to this end face is reduced, and the ceramic constituting the cylindrical body 6 is prevented from being broken or chipped. In this example, the space between the cylindrical body 6 and the container 17 is sealed with a rubber O-ring 8A. The present inventor also studied metal packing, but was disadvantageous in terms of dimensional accuracy and cost during processing. However, when the temperature of the ceramic heater 1 is increased,
A large amount of heat is generated, and the O-ring 8A may be melted. Therefore, the space between the O-ring 8A and the heater is increased by sealing at the tip of the extension 28, and the periphery of the O-ring 8A is cooled by the cooling jacket 29. Further, for the same reason as described above, the space between the jig 36 and the cylindrical body 6 is sealed with an O-ring 8B, and the cooling jacket 29 is provided outside the O-ring 8B.

The heat insulating materials 30A and 30B prevent the heat of the ceramic heater 1 from being transmitted to the supporting member 27. Such a support member 27 is made of metal, and thermally expands when exposed to a high temperature, and the position of the semiconductor wafer installation surface in the container shifts, so that productivity may decrease. Further, a part of the metal component in the support member 27 may evaporate at a high temperature, and may become a contamination source. Therefore, insulation materials 30A, 3
At 0B, the temperature rise of the support member 27 was minimized.

As a material constituting the heat insulating materials 30A and 30B, alumina is preferable. The present inventors have confirmed that alumina is stable against halogen-based corrosive gases such as ClF ₃ and NF ₃ . However, alumina has a low tensile strength, but in this example, since a compressive stress is applied to the heat insulating material 30A, even if they are formed of alumina, they are not easily broken. Further, when the heat insulating material 30A made of alumina is made thick, thermal shock resistance may be caused because the thermal shock resistance of alumina is low. Therefore, for example, the heat insulating material 30A is formed of a thin plate having a thickness of 1.5 mm, and two or more heat insulating materials 30A are laminated to prevent thermal shock destruction of the heat insulating material 30A.

[0034]

According to the heating apparatus of the present invention, it is possible to solve the problems of contamination as in the case of the conventional metal heater and deterioration of the thermal efficiency as in the case of the indirect heating method. Also, electrodes,
Since the terminals etc. are not exposed to the atmosphere of the inner space of the container, there is no danger of corrosion of the electrodes etc., contamination from the electrodes, and furthermore, there is no risk of electric discharge between the electrodes in a vacuum or between the electrodes and the container, or leakage. .

It is also important that the cylindrical body and the ceramic heater can be sealed with an annular member made of a soft metal, so that the sealing becomes very easy, stable and easy to manufacture. . In addition, since the cylindrical body and the ceramic heater are separate bodies, when a failure such as a crack occurs in either of them, both can be separated and only the failed one can be replaced. Further, since the annular member has a stress relaxing action, the cylindrical body and the ceramic heater are not easily broken. Further, a pressing member for pressing the cylindrical body toward the board-shaped base is provided, and by adjusting the pressing force by the pressing member, the pressure applied to the annular member is adjusted,
Its sealing performance can be adjusted.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a heating device according to an embodiment of the present invention is attached to a container 17. FIG.

2 (a), 2 (b) and 2 (c) are plan views showing respective steps of manufacturing an annular member 7. FIG.

FIG. 3 is a partially enlarged sectional view illustrating an example in which an annular member 7 is housed in a groove 19;

FIG. 4 is a cross-sectional view showing a state where a heating device according to another embodiment is attached to a container 17.

FIG. 5 is a sectional view showing a state in which a heating device according to still another embodiment is attached to a container 17.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic heater 2 Disc-shaped base 2b Back surface 3 Resistance heating element 4,27 Supporting member 6 Cylindrical body 7, 7B annular member 9 Electrode 11, 11A Thermocouple 12, 12A Terminal 22 Volt (Example of pressing member) 26 tubes Shape 33 Disc spring (Example of pressing member)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/3065

Claims (2)

(57) [Claims] 1. A ceramic heater in which a resistance heating element is buried inside a board-shaped substrate made of dense ceramics, a cylindrical body made of dense ceramics, both ends of which are open; An annular member made of a soft metal placed between the end surface of the cylindrical body, a supporting member for supporting a side peripheral surface of the ceramic heater, and pressing the cylindrical body toward the board-shaped base. A semiconductor wafer heating device comprising a pressing member, wherein the board-shaped base and the tubular body are pressed against the annular member so that the board-shaped base and the tubular body can be hermetically sealed. apparatus. 2. The semiconductor wafer heating apparatus according to claim 1, wherein said pressing member is a spring which is substantially in a constant temperature state.