JP2013089512A - Heater and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure in which heater patterns in multi-zones do not cause continuity between each other even when a heater base material is formed with a conductive material such as graphite.SOLUTION: A built-in type multi-zone heater 10 comprises: a graphite heater base material 11 having a configuration where inner/outer heater patterns 12,16 which are independently temperature controllable are combined with a space 19 interposed therebetween, and a plurality of PBN ribs 21 which are intermittently arranged in the space and connect the heater patterns. Since inner/outer heater patterns are connected with an insulative PBN ribs, the continuity between the heater patterns are prevented. The heaters have shape retention property while permitting a certain level of deformation. Consequently, there are exhibited effect of preventing breakage and damage due to thermal expansion coefficient difference of the heater base material and the rib formed of respectively different kinds of materials.

Description

The present invention relates to a ceramic heater suitably used for heating a wafer in a semiconductor process or the like and a method for manufacturing the same.

Ceramic heaters are widely used as heating devices for heating a wafer in a semiconductor process or the like. Conventionally, a predetermined heater pattern is formed on the surface of a disk-shaped heater body and provided at both ends of the heater pattern. A configuration in which a heater pattern is heated by supplying electric power from an external power supply via a power supply terminal portion is often used.

By the way, in order to uniformly heat the wafer, it is necessary to raise the heating surface of the heater uniformly over the entire wafer mounting area. However, the outer peripheral portion is more susceptible to the ambient temperature than the central portion. It is difficult to raise the temperature sufficiently, and a temperature difference tends to occur between the central portion and the outer peripheral portion. In particular, in recent years, the wafer diameter tends to increase, and the difficulty of uniformly heating a large-diameter wafer is increasing.

Under such circumstances, it has been proposed to divide the heater into a plurality of zones inside and outside and control the heat generation amount for each zone (Patent Document 1). In the example of Patent Document 1 (FIG. 1), a total of nine heater elements are concentrically arranged on a single substrate, and terminal pins are provided at both ends of each heater element to control each heater element independently. It is possible.

The heater described in Patent Document 1 is an integrated multi-zone heater in which a plurality of heater elements (heater patterns) are arranged on the same substrate to form a multi-zone. Instead, an outer peripheral portion and a central portion are provided. A separate multi-zone heater that is manufactured as a separate heater and assembled to one heater in a state where the central heater is housed in a ring-shaped outer peripheral heater has also been proposed (Patent Document 2).

JP 2001-052843 A JP 2006-049844 A

The integrated multi-zone heater as described in Patent Document 1 has advantages such that the thermal interference between the inner and outer heaters is relatively stable, and there are few individual differences even when the same heater is manufactured. When the temperature is controlled by individually controlling the pattern, as described in paragraph 0005 of Patent Document 2, a temperature distribution is generated in the integrated base material, and thus the base material may be damaged by local tensile stress. There is. In addition, considering the matching of the thermal expansion coefficient with the PBN in the temperature range (1000 ° C. or higher in some cases) when the PBN coating is formed by CVD (chemical vapor deposition), the material of the heater substrate is considered. Graphite is optimal, but since graphite is a conductive material, if a plurality of heater patterns are provided on the same graphite substrate, conduction occurs and it becomes difficult to strictly control the temperature. Although it is not conceivable to use an insulating material for the heater substrate, in view of the matching suitability of the thermal expansion coefficient, the difficulty of processing, etc., there is no actual material other than graphite.

According to the separate type multi-zone heater as described in Patent Document 2, such a problem is solved or at least reduced, but heat is generated at the boundary between the outer peripheral heater and the central heater when the temperature is raised. Therefore, each design and control are difficult. That is, if the distance between the inner and outer heater elements is too narrow, the temperature at the boundary between the inner and outer heaters will rise too much. Conversely, if the distance is too wide, the temperature at the boundary will be too low. It will be easy to lose balance. In addition, the outer and inner heaters, which are manufactured separately, are assembled into a final product, so that not only the design of each heater (temperature adjustment, etc.) but also the temperature adjustment while maintaining the balance between the inside and outside of the heater. Therefore, even when the same heater is manufactured, it is necessary to make adjustments each time, and skillful techniques are required.

As described above, the integrated multi-zone heater and the separate multi-zone heater have their merits and demerits, and the actual situation is that either one is selected according to the manufacturing environment or the required quality.

In view of such conventional technology, the present invention takes advantage of the advantages of the integrated multi-zone heater, and even when the base material is formed of a conductive material such as graphite, the heater zones of the multi-zone are arranged between each other. The problem is to eliminate the disadvantages of the prior art by adopting a structure that does not cause conduction.

In order to solve the above-mentioned problems, the invention according to claim 1 of the present application provides a heater made of a conductive material having a shape in which a plurality of heater patterns that can be independently temperature controlled are combined with a space between them. It is a heater characterized by having a base material and a plurality of insulating ribs that are intermittently disposed within the interval and insulatively connect the heater patterns.

The invention according to claim 2 is the heater according to claim 1, wherein the heater base has at least an outer peripheral heater pattern and a central heater pattern, and a ring-shaped boundary portion is formed between them. Insulating ribs are intermittently formed in the circumferential direction of the ring-shaped boundary portion.

The invention according to claim 3 is the heater according to claim 1 or 2, wherein the conductive material forming the heater base is graphite, and the insulating material forming the insulating rib is pyrolytic boron nitride (PBN). It is characterized by being.

According to a fourth aspect of the present invention, in the heater according to any one of the first to third aspects, at least an exposed surface of the heater base material is covered with an overcoat coating layer made of an insulating material.

According to a fifth aspect of the present invention, in the heater according to any one of the first to fourth aspects, a plurality of insulating ribs made of an insulating material are intermittently disposed between the heater elements in each heater pattern. The heater elements are connected in an insulating manner.

The invention according to claim 6 is the heater manufacturing method according to claim 1, and has a shape that substantially matches the combined shape of the plurality of heater patterns to be finally obtained, and is provided within the space between the heater patterns. A heater base material made of a conductive material having rib portions for intermittently connecting heater patterns to each other, and coating the heater base material with an insulating material to form a base coat coating layer; In the rib portion of the material, the rib portion of the heater base material is cut out together with the base coat coating layer formed on either the front surface side or the back surface side, leaving only the base coat coating layer formed on the other of the front surface side and the back surface side. This is an insulating rib, and a structure in which a plurality of heater patterns in the heater base material are intermittently connected by the insulating rib. It is a method of manufacture.

The invention according to claim 7 is the method for manufacturing a heater according to claim 6, wherein the conductive material forming the heater base is graphite, and the insulating material forming the insulating rib is pyrolytic boron nitride (PBN). It is characterized by being.

The invention according to claim 8 is the method for manufacturing a heater according to claim 6 or 7, further comprising coating an exposed surface of the structure with an insulating material to form an overcoat coating layer.

According to the first aspect of the present invention, in the heater base material made of a conductive material, the interval is provided between the plurality of heater patterns that can be controlled independently of temperature, and provided intermittently within the interval. Since the heater patterns are insulatively connected by the plurality of insulating ribs, conduction between the heater patterns does not occur. The insulating ribs ensure the integrity of the heater base material while maintaining the spacing between the heater patterns, and at the same time allow a certain degree of deformation, so that the thermal expansion coefficient between the heater base material and the insulating rib formed of different materials is Breakage and breakage due to different things can be prevented. Furthermore, there is an effect that the balance between the integrity and the deformation tolerance of the heater can be freely adjusted by appropriately setting the position, size, and number of the insulating ribs.

According to the invention which concerns on Claim 2, the effect which can prevent conduction | electrical_connection in the heater which has two zones inside and outside is acquired.

According to the invention which concerns on Claim 3, the heater by the suitable combination of the heater base material by the graphite excellent in workability and the PBN rib excellent in insulation can be provided.

According to the invention which concerns on Claim 4, the exposed surface of a heater base material is coat | covered with the overcoat coating layer by insulating materials, such as PBN. In this case, the exposed surface of the heater base material is insulated with one layer of the overcoat coating layer, but other than the exposed surface is insulated with two layers of the basecoat coating layer and the overcoat coating layer, Product life and insulation as a heater can be improved. Furthermore, since the insulating rib is also formed of these two layers, its strength increases, and the handleability and product life can be improved.

According to the invention of claim 5, since the plurality of insulating ribs are intermittently disposed between the heater elements in each heater pattern, a certain degree of deformation is allowed at the same time while preventing distortion in each heater pattern. The effect of preventing the heater from being broken or damaged can be exhibited more remarkably.

According to the invention which concerns on Claim 6, the suitable method for manufacturing the heater which has the structure of Claim 1 is provided.

According to the invention which concerns on Claim 7, the heater by the suitable combination of the heater base material by the graphite excellent in workability and the PBN rib excellent in insulation can be manufactured.

According to the eighth aspect of the invention, since the exposed surface of the heater base material is covered with the overcoat coating layer made of an insulating material such as PBN, a heater having excellent product life and insulation can be manufactured. . Since the heater according to the present invention has a multi-zone and is an integrated structure, it is easy to set conditions when the base coat and overcoat are formed by CVD or the like, and the film can be formed with a uniform film thickness. it can. In addition, by forming a double-coat insulating layer, there is an effect that a large film thickness can be obtained under relatively easy film forming conditions. PBN film formation by CVD is usually limited to about 0.3 mm, and cracking and floating are likely to occur in PBN even if it is attempted to obtain a film thickness larger than that, but such disadvantages are caused by using double coating. A PBN film having a large film thickness (0.5 to 1 mm) can be easily obtained without using it.

It is a top view of the heater by one Embodiment of this invention. It is a perspective view of this heater. It is a flowchart which shows the manufacturing process of this heater. It is a fragmentary sectional view which shows the cross-sectional state of the heater of each step in a manufacture process.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to this embodiment, and various modifications may be made within the scope of the invention described in the claims. Note that can be taken.

The heater 10 shown in FIGS. 1 and 2 has a heater base 11 and ribs 20 and 21. In this embodiment, the heater base 11 is made of graphite, and the ribs 20 and 21 are made of PBN.

The heater base 11 has a shape in which a plurality of heater patterns that can be independently temperature controlled are combined with a space between them. In this embodiment, the inner heater pattern 12 and the outer heater pattern are combined. 16 are combined with a space 15 between them. The inner heater pattern 12 is wound in a substantially spiral shape between the terminals 13a and 13b, and the outer heater pattern 16 is arranged outside the inner heater pattern 12 with a space 15 between them, and is substantially spiral between the terminals 17a and 17b. It is wound around. A gap 19 is also provided between the heater elements extending in a spiral shape in each of the inner heater pattern 12 and the outer heater pattern 16.

The heater 10 according to this embodiment is a so-called post-type heater, and terminal posts 14 a and 14 b are connected to the terminals 13 a and 13 b of the inner heater pattern 12, and terminal posts 18 a and 17 b of the outer heater pattern 16 are connected to the terminals 17 a and 17 b. 18b is connected. Then, power lines (not shown) from an external power source are connected to power supply terminal portions provided at the lower ends of the terminal posts 14a, 14b; 18a, 18b, and the inner heater pattern 12 and the outer heater pattern 16 are separately and independently provided. It is possible to raise the temperature to a controlled temperature. By adopting such a post-type structure, the distance between the surface of the heater 10 and the power supply terminal portion can be increased by the post length, so that an excessive temperature rise in the power supply terminal portion is suppressed and power supply is performed. It is possible to prevent burning of bolts and the like. In addition, since the power supply wiring can be moved away from the heater body, the wiring can be easily routed, and the occurrence of an accident such as a short circuit of the wiring hitting the heater can be prevented. Furthermore, since it is possible to use a power supply bolt made of an inexpensive material such as SUS, a significant cost reduction can be realized. Further, the terminal posts 14a, 14b; 18a, 18b function as power supply means for the inner heater pattern 12 and the outer heater pattern 16, and at the same time, serve as support legs for stably supporting the heater 10.

The PBN rib 20 allows a certain degree of deformation while maintaining the distance 19 between the heater elements in each heater pattern 12, 16, and the PBN rib 21 allows a certain degree of deformation while maintaining the distance 15 between the heater patterns 12, 16. Therefore, the heater patterns 12 and 16 and the heater base material 11 as a combination thereof are ensured to be integrated, and even when the heater 10 is used at a high temperature, materials having different coefficients of thermal expansion (graphite And PBN) to prevent breakage and breakage due to the difference in thermal expansion between the heater base 11 and the ribs 20 and 21.

Further, since the inner heater pattern 12 and the outer heater pattern 16 are connected by the insulating PBN ribs 21, conduction between the heater patterns 12 and 16 is prevented.

Next, a method for manufacturing the heater 10 will be described with reference to FIG. First, a graphite substrate molded into a predetermined shape is prepared (FIG. 3: S1). This graphite base material has a planar shape substantially similar to the planar shape (FIG. 1) of the heater 10 as a finished product described above. In other words, the inner heater pattern 12 between the terminals 13a and 13b and the outer heater pattern 16 between the terminals 17a and 17b are combined, and the heater elements 12 and 16 are intermittently provided in the interval 19 between the heater elements. Ribbed portions (graphite ribs) are provided at positions corresponding to the PBN ribs 20 provided on the PBN ribs and the PBN ribs 21 provided intermittently within the space between the heater patterns 12 and 16. Although the thickness of a graphite base material is not specifically limited, For example, the thickness of about 2-8 mm can be used.

Therefore, as illustrated in FIG. 4A, the graphite base material 22 is, when viewed in cross section, the full thickness portion 23 that becomes the heater patterns 12 and 16 and the intervals 15 and 19 in the heater 10 as a finished product. And a graphite rib 25 provided at a position corresponding to the PBN ribs 20 and 21. In this example, the graphite rib 25 is thinly formed on the bottom surface 27 side of the graphite substrate 22, and the surface 26 side of the graphite rib 25 is a concave groove 28.

Next, this graphite base material 22 is base-coated with PBN (FIG. 3: S2). Thereby, the surface 26 of the graphite base material 22 excluding the openings of the through portions 24 and the concave grooves 28, the back surface 27 of the graphite base material 22 excluding the openings of the through portions 24, the inner surface of the through portions 24, and the concave grooves 28. The PBN coating layer 29 (29a to 29e) is continuously formed on the inner side surface and the bottom surface (FIG. 4B). The thickness of the PBN coating layer 29 by the base coat is about 0.3 to 0.5 mm.

Next, the graphite rib 25 is cut together with the PBN coating layer 29e on the front surface side (the bottom surface of the concave groove 28) or the PBN coating layer 29b on the back surface side (the back surface 27 of the graphite base material), so that the single layer PBN coating layer 29 is cut. These are used as PBN ribs 20 and 21 (FIG. 3: S3, FIG. 4C). In this embodiment, a cutting tool is inserted into the groove 28 to cut away the range indicated by the thickness D and the width W in FIG. As a result, the graphite rib 25 is cut together with the PBN coating layer 29e on the bottom surface of the concave groove 28, and the PBN coating layer 29b (part in the range of the width W) on the back surface side is left.

At this time, as shown in FIG. 4 (c), the inner surface of the cut graphite rib 25 is exposed, and then the obtained structure 30 is overcoated with PBN (FIG. 3: S4). ). As a result, the exposed surface of the graphite base material 22 is also covered with the PBN coating layer 31 to obtain the heater substrate 11 exhibiting good insulation (FIG. 4D), and the terminals 13a, 13b; The terminal posts 14a and 14b; 18a and 18b are attached to complete the heater 10 (FIGS. 1 and 2). The thickness of the PBN coating layer 31 by overcoat is about 0.5 to 0.6 mm.

As understood from the above description, the rib portion (graphite rib 25) in the graphite substrate 22 is a substrate on which the PBN coating layer 29b (width W portion) and the coating layer 29e are formed by the PBN base coat (FIG. 3: S2). As shown in FIG. 3, the heater 10 as a finished product is cut off together with the coating layer 29e on the front surface side or the coating layer coating layer 29b (width W portion) on the back surface side in the step S3. It does not remain. In other words, the graphite ribs 25 that the original graphite base material 22 had are replaced with insulating PBN ribs 20 and 21 in the heater 10 as a finished product.

In FIG. 3: S3, the graphite rib 25 is cut out together with the PBN coating layer 29e on the bottom surface of the concave groove 28 to leave the PBN coating layer 29b (width W portion) on the back surface side. Alternatively, a cutting tool may be inserted from the back surface side of 25, and the graphite rib 25 may be cut out together with the PBN coating layer 29b (width W portion) on the back surface side to leave only the PBN coating layer 29e on the bottom surface of the groove 28. In any case, the remaining PBN coating layer 29b (width W portion) or 29e is composed of an overcoat PBN coating layer 30 and two upper and lower PBN coating layers (total thickness is about 0.8 to 1.0 mm). Thus, the PBN ribs 20 and 21 in the heater 10 as a finished product are formed.

Further, in the graphite base material 22 shown in FIG. 4A, the graphite rib 25 is formed on the back surface 27 side of the groove 28 opened on the front surface 26 side, but the position of the graphite rib 25 is not limited. For example, contrary to the illustrated form, graphite ribs may be formed on the surface 26 side of the concave groove opened on the back surface 27 side, or between the concave grooves opened on both the front and back surfaces (thickness of the graphite substrate 22). A graphite rib may be formed in the intermediate portion in the vertical direction. In either case, after the PBN base coat is performed in the same manner as described above, the graphite rib is cut together with the PBN coating layer 29 on either the front surface side or the back surface side of the graphite rib, and the single layer left without being cut off. The PBN coating layer 29 and the overcoated PBN coating layer 30 form two upper and lower PBN coating layers to form the PBN ribs 20 and 21.

In the embodiment described above, the heater base 11 has two zones of the inner heater pattern 12 and the outer heater pattern 16. However, the present invention is not limited to this, and can be arbitrarily multi-zoned. . For example, a three-zone or a larger number of multi-zone heater patterns can be formed such that a plurality of intervals 15 are formed in a sinusoidal manner between the heater patterns, or radial patterns can be formed at arbitrary angular intervals between the heater patterns. It is possible to make a multi-zone so that the interval 15 is formed, or it is also possible to make a multi-zone by arbitrarily combining them. In either case, conduction between the heater patterns is prevented by the PBN ribs 21 (insulating ribs) intermittently formed at intervals 15 between the heater patterns that can be independently and independently controlled, and the temperature of each heater pattern is increased. It can be strictly controlled.

It should be noted that the PBN ribs 20, 21 (insulating ribs) are formed at their locations, numbers, dimensions, etc., while preventing distortion of the heater patterns 12, 16 and the heater base 11 as a whole, allowing some deformation and breaking or breaking. The PBN ribs 21 (insulating ribs) arranged at the interval 15 between the inner and outer heater patterns 12 and 16 are further controlled to appropriately control the thermal interference between the inner and outer heater patterns 12 and 16. Therefore, the temperature is appropriately set in consideration of being able to accurately perform independent and independent temperature control.

The formation of the PBN coating layer 29 by the base coat (FIG. 3: S2) and the formation of the PBN coating layer 31 by the overcoat (FIG. 3: S4) are both preferably formed by CVD. Since these film formations by the CVD method are known in the art, a detailed description is omitted. In the present invention, these known CVD film forming methods can be arbitrarily employed.

DESCRIPTION OF SYMBOLS 10 Heater 11 Heater base material 12 made of graphite Inner heater patterns 13a, 13b Terminals 14a, 14b of inner heater pattern Terminal posts 15 of inner heater pattern 15 Space between inner / outer heater patterns 16 Outer heater patterns 17a, 17b Outer heater pattern Terminals 19a, 18b Outer heater pattern terminal posts 19a Spacing between heater elements in inner heater pattern 19b Spacing between heater elements in outer heater pattern 20, 21 PBN rib (insulating rib)
22 Graphite base material 23 Full thickness portion 24 Penetration portion 25 Graphite rib 26 Graphite base material surface 27 Graphite base material back surface 28 Concave groove 29 PBN coating layer 30 by base coating PBN coating layer 31 by overcoating graphite rib

Claims (8)

A heater base material made of a conductive material having a shape in which a plurality of heater patterns that can be independently temperature controlled are combined with a space between them, and heater patterns that are intermittently disposed within the space And a plurality of insulating ribs for insulatingly connecting the heaters. The heater base has at least an outer peripheral heater pattern and a central heater pattern, and a ring-shaped boundary is formed between them, and insulating ribs are intermittently formed in the circumferential direction of the ring-shaped boundary. The heater according to claim 1, wherein: The heater according to claim 1 or 2, wherein the conductive material forming the heater base is graphite and the insulating material forming the insulating rib is pyrolytic boron nitride (PBN). The heater according to any one of claims 1 to 3, wherein at least an exposed surface of the heater base material is covered with an overcoat coating layer made of an insulating material. 5. A plurality of insulating ribs made of an insulating material are intermittently disposed between heater elements in each heater pattern to insulate the heater elements from each other. The heater as described in any one of. 2. The method of manufacturing a heater according to claim 1, wherein the heater pattern has a shape that substantially matches a combined shape of a plurality of heater patterns to be finally obtained, and is provided within a space between the heater patterns to intermittently form the heater patterns. After preparing a heater base material made of a conductive material having a rib portion connected to the base material and coating the heater base material with an insulating material to form a base coat covering layer, the surface side or The base coat coating layer formed on one side of the back side and the rib portion of the heater base material are cut away to leave only the base coat coating layer formed on the other of the front side and the back side, which is used as an insulating rib, and the heater A method of manufacturing a heater, comprising: a structure in which a plurality of heater patterns in a base material are intermittently connected by the insulating ribs. 6. The method of manufacturing a heater according to claim 5, wherein the conductive material forming the heater base is graphite, and the insulating material forming the insulating rib is pyrolytic boron nitride (PBN). The heater manufacturing method according to claim 6 or 7, further comprising forming an overcoat coating layer by coating at least a heater base exposed surface of the structure with an insulating material.