JP2013069641A - Ceramics heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramics heater capable of ensuring such temperature distribution that the temperature changes monotonously from the central part to the periphery of a mounting surface.SOLUTION: A ceramics heater 1 comprises a ceramics substrate 2 having a mounting surface S on which a heated article W is mounted, an inside heating resistor Q1 embedded in the ceramics substrate 2, an outside heating resistor Q2 embedded in the ceramics substrate 2 on the outside of the inside heating resistor Q1, and a control section capable of controlling the power supplied to the heating resistor Q1, Q2 independently. When the distance from the center point O to the outer end of the upper surface of the ceramics substrate 2 is R, the inside heating resistor Q1 is disposed in a region of 0-0.5R around the center point O in the plan view, and the outside heating resistor Q2 is disposed in a region of 0.8R-R around the center point O in the plan view.

Description

  The present invention relates to a ceramic heater for heating an object to be heated such as a semiconductor wafer.

  In a ceramic heater, a ceramic substrate on which an object to be heated such as a semiconductor wafer to be processed such as film formation or etching is placed is divided into two zones, an inner peripheral side and an outer peripheral side. A two-zone heater in which a heating resistor is embedded has been proposed (see, for example, Patent Documents 1 and 2). In the two-zone heater, the amount of heat generated by each heating resistor is controlled independently, so that temperature control can be performed in a different manner for each zone.

Japanese Patent No. 3897563 Japanese Patent No. 4028149

  However, for example, when the ceramic substrate and the shaft supporting the ceramic substrate are made of a material having high thermal conductivity such as aluminum nitride, the heat generated in the ceramic substrate is dissipated through the hollow shaft. Therefore, even if the amount of heat generated by each heating resistor is controlled, the temperature near the center of the mounting surface, which is the upper surface of the ceramic substrate, becomes lower than the temperature in the surrounding area. Therefore, it has been difficult to obtain a temperature distribution that monotonously decreases in temperature from the center to the outer periphery of the mounting surface.

  Therefore, an object of the present invention is to provide a ceramic heater capable of obtaining a temperature distribution that monotonously changes in temperature from the center portion to the outer peripheral portion of the mounting surface.

  The present invention comprises a ceramic substrate made of ceramics, on which an object to be heated is placed, an inner heating resistor embedded in the ceramic substrate, and embedded in the ceramic substrate outside the inner heating resistor. A ceramic heater comprising: an outer heating resistor; and a control unit capable of independently controlling power supplied to the inner heating resistor and the outer heating resistor, the center point of the upper surface of the ceramic substrate When the distance from the outer end to the outer end is R, the inner heating resistor is arranged in a region of 0 to 0.5R centered on the center point in a top view, and the outer heating resistor is a top view. It is characterized by being arranged in a region of 0.8R to R centering on the center point.

  According to the ceramic heater of the present invention, the inner heating resistor and the outer heating resistor are not arranged adjacent to each other as in the prior art, and an interval of at least 0.3R is provided between them. For this reason, since the region where the inner heating resistor exists is narrower than in the conventional case, the temperature of the mounting surface located above the region where the inner heating resistor exists is effectively increased if the heat generation amount is the same. be able to.

  Therefore, for example, even when heat is radiated through the shaft connected to the central portion of the lower surface of the ceramic substrate, the temperature near the central portion of the mounting surface can be increased similarly to the surrounding region. Therefore, it is possible to obtain a temperature distribution in which the temperature decreases monotonously from the center portion to the outer peripheral portion of the placement surface.

  In addition, for example, even if heat is dissipated through a flange connected to the outer peripheral portion of the lower surface of the ceramic substrate, the temperature in the vicinity of the outer peripheral portion of the mounting surface can be increased similarly to the surrounding region. Therefore, it is possible to obtain a temperature distribution in which the temperature decreases monotonously from the outer peripheral portion to the center portion of the mounting surface.

  In this way, it becomes possible to make the temperature distribution on the mounting surface monotonous.

  In the present invention, it is preferable that the inner heating resistor is disposed above the outer heating resistor.

  In this case, the heat generated by the inner heating resistor is more efficiently transmitted to the upper mounting surface, and the vicinity of the center portion of the mounting surface can be further heated.

  In the present invention, it is also preferable that a plurality of the inner heating resistors are stacked in the vertical direction.

  In this case, the arrangement | positioning area | region of an inner side heating resistor becomes small, and it becomes possible to make still higher temperature vicinity of the center part of a mounting surface. Since the shaft is joined to the center and the area in which the inner heating resistor can be placed is narrow, multilayering the inner heating resistor is an effective means for increasing the amount of heat generated by the inner heating resistor. It is.

  Therefore, in these cases, even when the shaft is connected to the central portion of the lower surface of the ceramic substrate, a temperature distribution that monotonously decreases in temperature from the central portion to the outer peripheral portion of the mounting surface is more easily obtained. It becomes possible.

  In the present invention, a hollow shaft made of ceramics and connected to a central portion of the lower surface of the ceramic substrate is provided, and an outer end of a joint portion between the ceramic substrate and the shaft is centered on the central point in a top view. It is preferably located within the range of 0.1R to 0.3R.

  This is because if it is smaller than 0.1R, the wiring space to the heating element inside the shaft becomes narrow. On the other hand, if it is larger than 0.3 R, the placement surface center temperature is significantly lower than the placement surface temperature immediately above the joint, and the temperature distribution in the radial direction of the placement surface is not monotonous.

The schematic longitudinal cross-sectional view of the ceramic heater which concerns on embodiment of this invention. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. 1. The graph which shows the simulation result of the temperature distribution aspect of the radial direction of the mounting surface in an Example. The graph which shows the simulation result of the temperature distribution aspect of the radial direction of the mounting surface in a comparative example.

(Configuration of ceramic heater)
As shown in FIG. 1, a ceramic heater 1 according to an embodiment of the present invention includes a ceramic substrate 2 having a mounting surface S on which an object to be heated W such as a semiconductor wafer is mounted, and an embedded ceramic substrate 2. The inner heating resistor Q1, the outer heating resistor Q2 embedded in the ceramic substrate 2 outside the inner heating resistor Q1, and a hollow made of ceramic and connected to the center of the lower surface 2a of the ceramic substrate 2 The two-zone heater provided with the shaft 3.

  The ceramic heater 1 is applied to a ceramic product constituting a semiconductor manufacturing apparatus (for example, a film forming apparatus, an etching apparatus, or an inspection apparatus) used in various semiconductor manufacturing processes.

The ceramic substrate 2 is formed of a substantially disk-shaped ceramic sintered body having a radius R. The ceramic substrate 2 is made of, for example, aluminum nitride (AlN), alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), boron nitride so that the volume resistivity at the operating temperature is 10 ⁸ Ω · cm or more. (BN), yttria (Y ₂ O ₃ ), silicon carbide (SiC), and quartz are included as main components, and a sintering aid and the like are included as subcomponents.

  In particular, high thermal conductive ceramics mainly composed of aluminum nitride have a high thermal conductivity of 80 to 170 W / m · K and excellent temperature followability. Therefore, the ceramic substrate 2 of the ceramic heater 1 that requires good heat response is required. Suitable as a material.

  The ceramic molded body obtained by press-molding the heat-generating resistors Q1, Q2 installed on the raw powder press-molded body and further placing the raw material powder thereon is fired by hot pressing, By appropriately performing processing such as surface polishing, the ceramic substrate 2 in which the heating resistors Q1 and Q2 are embedded is manufactured. The heating resistors Q1 and Q2 are formed in the same layer, and may be formed by, for example, a screen printing method.

  The heating resistors Q1 and Q2 are made of a heat-resistant metal such as molybdenum (Mo) or tungsten (W) in any shape such as foil, film, plate, wire, mesh, fiber, coil, ribbon, etc. It is arranged in any form such as a folded shape.

  As shown in FIG. 2, when the center point of the upper surface of the ceramic substrate 2 is O, the inner heating resistor Q1 is in a circular region of 0 to 0.5R centered on the center point O in the top view. The outer heating resistor Q2 is disposed in a region of 0.8R to R centered on the center point O in a top view. And the heating resistor is not arrange | positioned in the annular area | region of 0.5R-0.8R centering on the center point O by the top view.

  The ceramic substrate 2 has a connection terminal (not shown) embedded in the center of its lower surface. The heating resistors Q1 and Q2 are connected to a pair of connection terminals by current supply members (not shown) embedded in the ceramic substrate 2, respectively. A power supply line (not shown) wired through the hollow portion of the shaft 3 is connected to each connection terminal. The feeder line is connected to a power source (not shown).

  The current supply member and the connection terminal are brazed or welded. The current supply member is made of molybdenum (Mo) or tungsten (W). The connection terminals are mainly foil, plate, massive nickel (Ni), Kovar (registered trademark) (Fe-Ni-Co), molybdenum (Mo), tungsten (W), or molybdenum (Mo) and tungsten (W). It is composed of a heat-resistant metal such as a heat-resistant alloy as a component.

  Further, the ceramic heater 1 includes a control unit (not shown) configured by a computer. The control unit independently controls power supplied from the power source to each of the heating resistors Q1 and Q2. As a result, the amount of heat generated by each of the heating resistors Q1 and Q2, and the temperature distribution of the mounting surface S of the ceramic substrate 2 in each of the two zones defined by the heating resistors Q1 and Q2 are controlled.

  As shown in FIG. 1, the shaft 3 is a hollow ceramic sintered body joined to the central portion of the lower surface 2 a of the ceramic substrate 2. The shaft 3 has a substantially cylindrical shape, and has an enlarged portion 3b in which the outer diameter of the joint portion with the ceramic substrate 2 is larger than that of the other shaft portion 3a, and the upper surface of the enlarged portion 3b is a joint surface with the ceramic substrate 2. It has become. The material of the shaft 3 may be the same as the material of the ceramic substrate 2, but may be formed of a material having a lower thermal conductivity than the material of the ceramic substrate 2 in order to improve heat insulation.

  The lower surface 2a of the ceramic substrate 2 and the upper end surface of the shaft 3 are bonded by diffusion bonding or solid-layer bonding using a bonding material such as ceramics or glass. The ceramic substrate 2 and the shaft 3 may be connected by screwing or brazing.

  The outer end of the joint between the ceramic substrate 2 and the shaft 3 is preferably located in a region of 0.1R to 0.3R with the center point O as the center when viewed from above.

  Although not shown, the lower end portion of the shaft 3 is connected to the vacuum chamber via a flange or the like, and the hollow portion of the shaft 3 is configured to have the same atmosphere as the inside of the vacuum chamber.

  As described above, in the ceramic heater 1, the inner heating resistor Q1 and the outer heating resistor Q2 are not disposed adjacent to each other as in the prior art, and the upper surface (mounting surface) of the ceramic substrate 2 is interposed therebetween. When the outer radius of S is R, an interval of at least 0.3R is provided.

  Therefore, since the region where the inner heating resistor Q1 exists is narrower than in the conventional case, the temperature of the mounting surface S positioned above the region where the inner heating resistor Q1 exists is more effective if the heat generation amount is the same. Can be raised. Therefore, even if heat is radiated through the shaft 3, the temperature in the vicinity of the center portion of the mounting surface S can be increased as in the surrounding area. Therefore, it is possible to obtain a temperature distribution in which the temperature decreases monotonously from the center to the outer periphery.

  The object of the present invention is to increase the temperature distribution near the center of the mounting surface S. However, the same effect may be obtained by adding a thermal resistance configuration between the ceramic substrate 2 and the shaft 3 or by significantly reducing the thermal conductivity of the shaft 3.

  However, according to the present invention, the ratio of the heat generation amount of the inner heating resistor Q1 and the heat generation amount of the outer heating resistor generator Q2 can be easily changed by an external control unit. It is possible to easily realize an arbitrary monotonic temperature distribution including increasing and decreasing the temperature distribution near the portion.

(Examples 1 and 2, comparative example)
For the ceramic heater 1, the total heating value of the heating resistors Q1 and Q2 is set to 1300 W, and the heating value ratio of each heating resistor Q1 and Q2 is changed to change the radial position of the mounting surface S in the steady state. The temperature of was determined by simulation.

  In Examples 1 and 2 and the comparative example, settings were made as follows.

  The ceramic substrate 2 is made of aluminum nitride and has a disk shape with a radius of R170 mm and a thickness of 20 mm.

  The heating resistors Q1 and Q2 are both film-like films made of molybdenum, and are arranged 10 mm below the mounting surface S.

The shaft 3 is made of aluminum nitride, and the shaft portion 3a has an outer radius of 25 mm (0.15R).
The disk 4 has a thickness of 4 mm and a length of 250 mm, and the enlarged portion 3 b has a cylindrical shape with an outer radius of 33.5 mm (0.20R), a thickness of 6 mm, and a length of 15 mm. The shaft 3 is assumed to be integrated with the ceramic substrate 2.

  In the first embodiment, the inner heating resistor Q1 is arranged in the entire 0 to 80 mm (0.47R) circular region centered on the center point O when viewed from above. The outer heating resistor Q2 is arranged on the entire surface in an annular region of 136 mm (0.80R) to 165 mm (0.97R) with the center point O as the center when viewed from above.

  In the second embodiment, the inner heating resistor Q1 is arranged in the entire circular area of 0 to 60 mm (0.35R) with the center point O as the center when viewed from above. The outer heating resistor Q2 is arranged on the entire surface in an annular region of 136 mm (0.80R) to 165 mm (0.97R) with the center point O as the center when viewed from above.

  In the comparative example, the inner heating resistor Q1 is disposed within the entire circular region of 0 to 126 mm (0.74R) centering on the center point O in top view. The outer heating resistor Q2 is arranged on the entire surface in an annular region of 136 mm (0.80R) to 165 mm (0.97R) with the center point O as the center when viewed from above.

  The simulation result of the temperature distribution aspect of the radial direction of the mounting surface S of the ceramic substrate 2 in Examples 1 and 2 is shown in FIG. In FIG. 3, the case where the heat generation rate of the inner heating resistor Q1 is 90% and the heat generation rate of the outer heating resistor Q2 is 10% in Example 1 is a triangle. The case where the heat generation rate is 10% and the heat generation rate of the outer heating resistor Q2 is 90% is X. In Example 2, the heat generation rate of the inner heating resistor Q1 is 90%, and the heat generation of the outer heating resistor Q2 The case where the amount ratio is 10% is a quadrangle and plotted.

  The simulation result of the temperature distribution aspect of the radial direction of the mounting surface S of the ceramic substrate 2 in a comparative example is shown in FIG. In FIG. 4, the case where the heat generation rate ratio of the inner heating resistor Q1 is 90% and the heat generation rate ratio of the outer heating resistor Q2 is 10% is X, and the heat generation rate ratio of the inner heating resistor Q1 is 70%. The case where the heating value ratio of the heating resistor Q2 is 30% is triangular, the heating value ratio of the inner heating resistor Q1 is 60%, and the heating value ratio of the outer heating resistor Q2 is 40%, When the heat generation rate ratio of the inner heating resistor Q1 is 30% and the heat generation rate ratio of the outer heating resistor Q2 is 70%, rhombuses are plotted.

  3 and 4, the ceramic heaters of Examples 1 and 2 have no temperature drop in the vicinity of the center portion of the mounting surface S as compared with the ceramic heaters of the comparative examples, and from the center portion to the outer peripheral portion. It was found that a temperature distribution that monotonously decreases in temperature can be obtained.

  Further, from FIG. 3, when the heat generation rate ratio of the inner heating resistor Q1 is 90% and the heat generation rate ratio of the outer heating resistor Q2 is 10%, the ceramic heater of Example 2 is the same as the ceramic heater of Example 1. In comparison, it was found that the temperature near the center of the mounting surface S was high.

(Other embodiments)
In the ceramic heater 1 according to the above-described embodiment, the heating resistors Q1 and Q2 are formed in the same layer. However, the inner heating resistor Q1 may be formed in an upper layer than the outer heating resistor Q2. In this case, the heat generated by the inner heating resistor Q1 is more efficiently transmitted to the upper mounting surface S, and the vicinity of the center portion of the mounting surface S can be further heated.

  Further, in the ceramic heater according to the above-described embodiment, the heating resistors Q1 and Q2 are formed of a single layer. However, the inner heating resistor Q1 may be multilayered. In this case, the arrangement | positioning area | region of the inner side heating resistor Q1 becomes small, and it becomes possible to make the vicinity of the center part of the mounting surface S still higher temperature. Since the shaft 3 is joined to the center and the region where the inner heating resistor Q1 can be disposed is narrow, the multilayering of the inner heating resistor Q1 increases the amount of heat generated by the inner heating resistor Q1. It is an effective means.

  As mentioned above, although embodiment of this invention and its modification were demonstrated, this invention is not limited to this. For example, the shape of the ceramic substrate is not limited to a disk shape, and may be an arbitrary shape such as an elliptical plate shape or a polygonal plate shape.

  And when the distance from the center point of the upper surface of the ceramic substrate to the outer end is R, the inner heating resistor Q1 is disposed in a region of 0 to 0.5R centered on the center point O in top view, The outer heating resistor Q2 may be disposed in a region of 0.8R to R centered on the center point O when viewed from above. Accordingly, the heating resistors Q1 and Q2 are arranged in a region similar to the shape of the upper surface of the ceramic substrate with the center point O as the center when viewed from above.

  The shape of the shaft is not limited to a cylindrical shape, and may be an arbitrary hollow shape such as an elliptical cylindrical shape or a polygonal cylindrical shape. And the center axis | shaft of a ceramic substrate and a shaft does not necessarily need to correspond.

  Further, the present invention is not limited to the structure in which the hollow shaft 3 is joined to the ceramic substrate 2 so that the heat flow generated from the heating resistors Q1 and Q2 is radiated through the shaft 3.

  For example, the present invention can also be applied to a case where a ring-shaped flange is connected to the lower surface of the outer peripheral portion of the ceramic substrate 2 and the heat flow is dissipated from the outer peripheral portion of the ceramic substrate 2 via this flange. In this case, it is possible to realize a monotonous temperature distribution in which the temperature at the center of the ceramic substrate 2 is low and the temperature at the outer periphery is high.

  DESCRIPTION OF SYMBOLS 1 ... Ceramic heater, 2 ... Ceramic substrate, 3 ... Shaft, 3a ... Shaft part, 3b ... Diameter expansion part, Q1 ... Inside heating resistor, Q2 ... Outside heating resistor, S ... Mounting surface (upper surface), W ... Object to be heated.

Claims (4)

A ceramic substrate made of ceramic and on which an object to be heated is placed;
An inner heating resistor embedded in the ceramic substrate;
An outer heating resistor embedded in the ceramic substrate outside the inner heating resistor;
A ceramic heater comprising a control unit capable of independently controlling power supplied to the inner heating resistor and the outer heating resistor,
When the distance from the center point of the upper surface of the ceramic substrate to the outer end is R, the inner heating resistor is disposed in a region of 0 to 0.5R centered on the center point in the top view, The outer heating resistor is disposed in a region of 0.8R to R centering on the center point in a top view.   The ceramic heater according to claim 1, wherein the inner heating resistor is disposed above the outer heating resistor.   The ceramic heater according to claim 1, wherein a plurality of the inner heating resistors are stacked one above the other. Made of ceramics, comprising a hollow shaft connected to the center of the lower surface of the ceramic substrate,
The outer end of the joint between the ceramic substrate and the shaft is located in a region of 0.1R to 0.3R centered on the center point in a top view. The ceramic heater according to item 1.

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