JP2003249330A - Foil-like resistance heater element, its manufacturing method and flat heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foil-like mesh-shaped resistance heater element capable of avoiding or preventing generation of an in-plane temperature gradient, and to provide its manufacturing method and a flat heater excellent in durability. <P>SOLUTION: This foil-like resistance heater element is characterized in that a mesh-like pattern is formed by using a tungsten foil or a molybdenum foil as its material, and the open area ratio of the mesh is set to 5-75%. The foil-like resistance heater element like this can be manufactured by: a process for masking for etching corresponding to the mesh-like heater element pattern on the principal surface of the tungsten foil or the molybdenum foil; a process for applying a chemical etching process to the masked metal foil to form the mesh- like heater element pattern by selective etching of an exposed part; and a process for removing the mask for etching. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foil resistance heating element, a method for manufacturing the same, and a sheet heater.

[0002]

2. Description of the Related Art For example, in manufacturing a semiconductor, a semiconductor wafer is subjected to processing such as PVD, plasma CVD, plasma etching, and photoetching.
In addition, these processing treatments are generally performed while the object to be processed is placed on a planar heater (heating element) and the object to be processed is heated. In order to obtain semiconductors with high performance or high reliability in good yield and in mass production,
Heat treatment is one important factor.

Here, in the planar heater, for example, a resistance heating wire (or coil) such as a tungsten wire or a molybdenum wire is embedded inside a dense and gastight ceramics sintered body layer, for example, in a spiral shape or a zigzag shape. It is a thing. The lead terminal or electrode portion of the resistance heating element is led out of the ceramic sintered body. Examples of ceramics include alumina-based, silica-based, aluminum nitride-based, silicon nitride-based, and sialon. Among them, aluminum nitride-based ceramics have thermal conductivity, corrosion resistance, and thermal expansion coefficient close to that of tungsten. Suitable in terms.

Further, this type of sheet heater is generally manufactured by the following means. The first means is
A resistance heating element formed by the resistance heating wire is arranged on one main surface of the ceramic base material (green sheet),
While stacking the heater cover sheet on the surface of the resistance heating element, after incorporating the lead terminals, degreasing under predetermined conditions, hot pressing at the required temperature, etc.
It is a method of manufacturing by integrating.

The second means is to prepare two plate-shaped ceramic sintered bodies in advance and dispose the resistance heating element formed by the resistance heating wire between the surfaces of the ceramic sintered bodies while the bonding agent layer is formed. It is a method of manufacturing by inserting and joining and integrating. In any of the first and second means, the resistance heating element is formed by screen printing of a paste for the resistance heating element, laser processing of a tungsten plate, punch punching, or the like.

By the way, in the heat treatment in the semiconductor manufacturing process, the durability of the sheet heater used as a heat source and good heating due to uniform or high temperature accuracy are favorable from the viewpoints of working efficiency and cost reduction. In order to secure the yield, it is required that the in-plane temperature distribution be uniform.

[0007]

The uniformity of the in-plane temperature distribution of the sheet heater is made possible by setting the resistance heating element to a fine wire and setting the winding or winding pitch to be small. That is, by arranging or patterning the resistance heating elements with high accuracy and setting the heating temperature as uniform as possible so that the heating temperature is as uniform as possible, the planar heater has a uniform in-plane temperature distribution. It will be possible to meet the above demand.

However, in the case of the resistance heating element, the following disadvantages are recognized in practical use. That is, since the tungsten wire or the molybdenum wire is a hard material, it is difficult to perform fine bending work, and it is necessary to work the softened wire by heating. Here, the processing in the state of being softened by heating can be finely bent, wound, coiled, etc., but not only warping or deformation is likely to occur after cooling, but also the surface is oxidized,
Processing accuracy is impaired. Therefore, when a planar heater is used, the in-plane temperature distribution is affected.

On the other hand, since the resistance heating element is usually formed by screen printing by many times of overprinting, not only the operation for obtaining the positioning accuracy is complicated but also there is a problem in the dimensional accuracy. However, there is also a disadvantage that productivity is poor. Also, laser processing of tungsten plate,
Alternatively, the resistance heating element patterned by punching has a disadvantage that it is difficult to perform fine processing and the durability is easily deteriorated. That is, the patterning means of the resistance heating element by screen printing, laser processing or punching has a limit in dimensional accuracy, etc., and provides a resistance heating element for a planar heater having an excellent in-plane temperature distribution. Is difficult.

The uniformity or ease of setting of the in-plane temperature distribution is important in order to increase the manufacturing / processing efficiency or productivity and to increase the diameter of the workpiece (eg, semiconductor wafer). It will be a point. That is, in increasing the diameter of the sheet heater corresponding to the increase in the diameter of the object to be processed, it is necessary to control the heat radiation of the sheet heater, control the heating temperature and accuracy, or set the temperature uniformly. In contrast,
Poor shape and dimensional accuracy of the resistance heating element may cause uneven heat generation, which easily causes an in-plane temperature gradient.

The present invention has been made in view of the above circumstances, and has a good dimensional accuracy and a foil-shaped mesh resistance heating element capable of avoiding or preventing the occurrence of an in-plane temperature gradient, its manufacturing method and durability. The purpose is to provide an excellent sheet heater.

[0012]

According to a first aspect of the present invention, a tungsten foil or a molybdenum foil is used as a material to form a mesh pattern, and the mesh has an aperture ratio of 5 to 5.
The foil-shaped resistance heating element is characterized by being 75%.

According to a second aspect of the invention, in the foil-shaped resistance heating element according to the first aspect, the mesh aperture ratio on the outer peripheral region side is set to be larger than the mesh aperture ratio on the central region. .

According to a third aspect of the present invention, in the foil-shaped resistance heating element according to the first or second aspect, the mesh opening diameter on the outer peripheral region side is set larger than the mesh opening diameter on the central region. Is characterized by.

According to a fourth aspect of the present invention, a step of performing etching masking on the main surface of the tungsten foil or molybdenum foil corresponding to the mesh-shaped heating element pattern, and a step of chemically etching the masked metal foil to expose the exposed portion A method of manufacturing a foil-shaped resistance heating element, comprising: a step of patterning a mesh-shaped heating element by selective etching; and a step of removing the etching mask.

According to a fifth aspect of the present invention, the aluminum nitride sintered body layer forming the heat radiation / heating surface and the aluminum nitride sintered body layer are embedded and arranged, and the lead terminal pair is led out to the other main surface side. And a mesh-shaped resistance heating element having a patterned tungsten foil or molybdenum foil, wherein the mesh-shaped resistance heating element has an aperture ratio of 5 to 75%. is there.

According to a sixth aspect of the invention, in the planar heater according to the fifth aspect, the aperture ratio of the mesh resistance heating element on the outer peripheral region side is set to be larger than the aperture ratio of the central region. And

That is, the invention of claims 1 to 4 uses tungsten foil or molybdenum foil as the material of the resistance heating element, and the resistance heating element is patterned by etching or the like. The main point is that is processed into a mesh shape.
On the other hand, the gist of the inventions of claims 5 and 6 is to embed / embed the mesh-shaped resistance heating element with an aluminum nitride-based sintered body layer having a relatively large thermal conductivity and excellent corrosion resistance. .

In the invention of claims 1 to 6, the tungsten foil or molybdenum foil forming the mesh-shaped resistance heating element has a thickness of, for example, 30 to 500 μm, preferably 1.
It is about 50 ± 10 μm, and the width (generally 180 to 500 μm) and the total length of the mesh pattern are selected and set in consideration of the target resistance heating capacity. Further, the mesh-shaped patterning of the metal foil can be performed by a laser processing method or a punching method, but it is disadvantageous because fine processing is difficult as compared with the etching processing.

Here, the etching treatment is an acidic corrosive solution (for example, a hydrogen fluoride-nitric acid-based etching solution) or an alkaline corrosive solution (for example, a sodium hydroxide-based etching solution) for a metal foil or a thin metal plate. ) Is used for selective etching. That is, it is carried out by a general etching treatment means in which one or both main surfaces of the tungsten foil are made to correspond to a desired mesh pattern, masked with an etching resist, and immersed in an etching solution.

In the patterning by this etching process, of the mesh-shaped opening region to be removed by etching and the edge portion in the pattern width direction, the edge portion in the pattern width direction has a thickness (depth) by a so-called side etching action. ) Direction is formed in a taper shape that forms a substantially V shape. When the taper is embedded in the ceramics substrate and embedded therein, the tapered edge portion meshes with the ceramics layer, which promotes strong integration. The conditions such as the material of the metal foil, the thickness of the metal foil, the masking of the etching resist, the type of the etching solution, and the temperature and time of the etching treatment are appropriately selected and set.

In the invention of claims 1 to 6, when the aperture ratio of the mesh-shaped resistance heating element is selected in the range of 5 to 75%, a bonding agent is introduced into the mesh openings to firmly bond the upper and lower base materials. Contribute to. That is, if the mesh opening ratio of the foil-shaped resistance heating element pattern is less than 5%, the bondability when embedded in ceramics is insufficient, and if the mesh opening ratio exceeds 75%, the mechanical strength and resistance heating property are increased. Is likely to be impaired, it is necessary to set within the above range. Here, the mesh openings in the foil-shaped resistance heating element pattern may be substantially uniform as a whole, but more preferably, they are set as follows.

That is, the numerical aperture of the foil-shaped resistance heating element pattern is set to be larger in the outer peripheral region than in the central region, or the size of the mesh opening diameter in the outer peripheral region is larger than that in the central region. The mesh opening ratio in the outer peripheral area is set to a large value. The size of this aperture and the distribution of aperture ratio
By the setting, heat generation in the foil-shaped resistance heating element pattern is controlled, and the uniformity of the temperature distribution, in other words, a function as a planar heater, facilitates exhibiting a good in-plane temperature distribution.

In the fifth and sixth aspects of the invention, the aluminum nitride-based sintered body layer in which the foil-shaped resistance heating element is embedded / built in is sintered to, for example, an aluminum nitride powder having an average particle diameter of about 0.01 to 5 μm. Granulate from a slurry obtained by adding and mixing an auxiliary agent and a binder, and mold this into a molded product having a required shape and size.
It is produced by sintering in a high temperature inert atmosphere at 00 ° C. or higher. Here, the sintering aid is exemplified by yttrium oxide, and the binder is exemplified by polyvinyl butyral. Prior to the high temperature sintering, it is desirable to previously provide a groove for arranging and embedding the resistance heating element on one main surface of the molded body.

The foil-shaped resistance heating element is embedded in the aluminum nitride based sintered body layer by positioning the resistance heating element between the facing surfaces of the aluminum nitride based sintered body members to be combined, while A bonding agent such as aluminum nitride-yttrium oxide-lithium oxide paste is printed or applied on the surfaces where the sintered body members face each other to form a bonding layer, and a load of 6 g / cm ² or more is applied to the surface, and an inert atmosphere is applied. It is performed by heating at a temperature of about 1550 to 1750 ° C. in a medium or reduced pressure atmosphere. The resistance heating element can also be embedded by stacking a plurality of so-called green sheets and integrally sintering them under high pressure and high temperature.

Further, in the embedded structure of the resistance heating element, if the lead terminals of the resistance heating element are collectively led to the side opposite to the heating / radiating surface for easy handling, the structure is While simplifying, it also facilitates space saving.

According to the inventions of claims 1 to 3, claim 5 and claim 6, the resistance heating element is made of a foil of tungsten or molybdenum, has a mesh shape, and forms and holds a pattern having a highly precise size and shape. To do. Therefore, as a whole, the resistance heating property as set is secured, and the required in-plane temperature distribution is easily exhibited. Further, since the resistance heating element pattern is formed in a mesh shape, when it is used as a planar ceramics heater, the adhesiveness or bonding force with the ceramic base material or the bonding agent is improved, and stable embedding / integration is maintained. .

That is, in repeated use as a heat source, the ceramic base material and the resistance heating element are separated from each other.
Separation is avoided, durability is improved and stable in-plane temperature distribution is secured. In particular, the function of avoiding / preventing the peeling phenomenon is remarkable when the temperature rises rapidly.

According to the fourth aspect of the present invention, the resistance heating property as set is secured, and not only the required in-plane temperature distribution is easily exhibited, but also the adhesion or the bonding force with the ceramic base material or the bonding agent is improved. Thus, it is possible to mass-produce the mesh-shaped resistance heating element in which stable embedding is maintained.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, FIG. 1 (a), (b),
An embodiment will be described with reference to (c) and FIG.

FIGS. 1A and 1B are plan views showing a schematic structure of a mesh resistance heating element according to the first embodiment.
(A) is a general view, (b), (c) is a partially enlarged view.
Here, 1 is a pair of external terminals 1a, 1b in the center,
This is a mesh-shaped resistance heating element which is connected to the external terminals 1a and 1b and patterned in a substantially spiral shape. The mesh resistance heating element 1 has a thickness of 150 ± 10 μm.
The pattern width is about 200 μm and is made of a tungsten foil or a molybdenum foil.

The pattern forming the resistance heating element 1 has a structure in which the mesh aperture ratio is changed in correspondence with the extension from the central region to the outer peripheral region. That is, the aperture ratios of the patterns 1c ₁ , 1c ₂ , 1c ₃ ... Extending and arranged from the central region to the outer peripheral region are 1c ₁ <1.
It is set so that c ₂ <1c ₃ <... Here, the distribution of the mesh-shaped aperture ratio may be adjusted depending on the number of numerical apertures or the like, but as shown in a partially enlarged plan view in FIGS. 2A and 2B, the pattern 1c ₁ , 1c ₂ , 1c ₃
It is also possible to set the opening diameter of ... to be 1c ₁ <1c ₂ <1c ₃ <...

Next, a manufacturing example of the resistance heating element 1 according to the embodiment will be described. First, a tungsten foil or a molybdenum foil, for example, a tungsten foil having a thickness of about 150 μm is prepared, and both main surfaces of the tungsten foil 1 are opposed to each other.
A mesh pattern was masked with an etching resist on a spiral pattern having a width of about 2.5 mm. In this mesh-shaped masking, the mesh-shaped pattern is such that the numerical aperture per unit area on the central region side of the spiral pattern is smaller than the numerical aperture per unit area on the peripheral region region side.

Next, the tungsten foil masked with the above etching resist is held by a support, and an acidic etching solution such as hydrogen fluoride (HF) and nitric acid (HN) is used.
In a mixed system of O ₃ , it is immersed for about 30 hours in an etching solution heated and maintained at about 20 ° C. to selectively remove the exposed tungsten foil (excess part) by etching. After that, by removing from the etching solution and washing, while removing the etching resist, a spiral mesh-shaped resistance heating element 1 having a high dimensional or shape accuracy was produced.

In this etching process, the area outside the area masked with the etching resist (exposed area) is selectively removed in the thickness direction by etching. This etching erosion in the thickness direction causes the region to be etched to become narrower in sequence, so that V in the depth direction does not occur.
The pattern end faces (the pattern width direction end edges) are tapered because they progress in a letter shape and are separated.

Next, an embodiment of a sheet-shaped ceramics heater having the above-mentioned mesh-shaped resistance heating element 1 built-in therein will be described. That is, the mesh-shaped resistance heating element 1 is spirally embedded and arranged in an aluminum nitride-based sintered body layer whose one main surface side constitutes a heat radiation / heating surface. Here, the lead terminal portions 1a and 1b of the mesh-shaped resistance heating element 1 are led out to the other main surface side of the aluminum nitride-based sintered body layer.

The aluminum nitride based sintered body layer has a diameter of 2 mm.
It is composed of two aluminum nitride-based sintered body members each having a thickness of about 40 mm and a thickness of about 10 mm. That is, the mesh-shaped resistance heating element 1 is positioned and arranged between the facing surfaces of both aluminum nitride-based sintered body members.
The structure is integrated by the bonding agent layer provided on the arrangement surface. In positioning and arranging the mesh-shaped resistance heating element 1, it is preferable to provide a concave portion with which the mesh-shaped resistance heating element 1 is engaged, on at least one of the facing surfaces of the aluminum nitride-based sintered body member.

The planar heater having the above structure not only exhibits good heat conductivity, heat resistance and plasma resistance of the aluminum nitride-based sintered body layer, but also has a high dimensional accuracy of the mesh resistance heating element 1. In other words, the required heat generation and heat dissipation can be ensured with the interior and provision of the mesh resistance heating element 1 whose required heat generation capacity and the like are easily controlled and adjusted.
Moreover, when the mesh-shaped resistance heating element 1 is embedded / embedded in the aluminum nitride-based sintered body layer, a stable embedding is ensured by improving the adhesive force by forming the mesh.
It functions as a heating element that does not generate (or hardly generates) a temperature gradient as a whole. In this example, the taper (protrusion) at the edge of the mesh-shaped resistance heating element 1 bites into the aluminum nitride-based sintered body layer, which helps ensure stable installation and mounting. To be done.

For example, when a heating test was repeated at a temperature of 800 ° C. by applying a required electric power to the planar heater having the above structure, the temperature of the heating surface was always 800 ° C. ± 2.
It exhibited excellent in-plane temperature uniformity at ℃. That is, diameter 2
It was also confirmed that the circular surface of 30 mm showed an almost uniform heating temperature as a whole, the fear of breakage and damage of the sheet heater itself was completely eliminated or avoided, and that the heater had excellent durability.

In the above configuration example, the configuration of the mesh-shaped resistance heating element using the tungsten foil as the material, the example of the manufacturing method, and the configuration example of the planar heater have been described. The effect was recognized.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the invention. For example, the mesh distribution and opening diameter of the mesh-shaped resistance heating element, the shape and size of the mesh-shaped resistance heating element, the input power, or the diameter, thickness, shape and size of the planar heater can be selected and set according to the application. Further, by changing the pattern of the metal foil, it can be applied as an electrode for an electrostatic chuck or a susceptor.

[0042]

According to the first to third aspects of the invention, the resistance heating element forms and holds a pattern having a required size and shape, and at the same time, has good adhesion to a ceramic or the like embedded or built in by forming a mesh. Exhibits sexuality or bondability.
Therefore, the resistance heating property as set is ensured, and not only the required in-plane temperature distribution is easily exhibited, but when embedded in ceramics, it is engaged and integrated with the peripheral portion, so that Peelability is also greatly improved and durability is also improved.

According to the fourth aspect of the present invention, the resistance heating property as set is secured, and the required in-plane temperature distribution is easily exhibited.
In addition, since the adhesion or the bonding force with the ceramic base material and the bonding agent is improved, a mesh-shaped resistance heating element in which stable embedding and built-in are maintained is mass-produced.

According to the fifth and sixth aspects of the present invention, there is provided a sheet heater which has uniform in-plane heat generation and heat radiation and is capable of heating the entire object to be processed without temperature unevenness and having excellent durability. it can.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of a mesh resistance heating element according to an embodiment, (a) is an overall view, (b) is a partially enlarged view, and (c) is another partially enlarged view.

2A and 2B are partially enlarged plan views showing a schematic configuration of different mesh-shaped resistance heating elements according to another embodiment.

[Explanation of symbols]

1 ...... meshed resistive heating elements 1a, 1b ...... external terminal portions _1c of the mesh-like resistance heating element, 1c _1, 1c 2, 1c ₃ ...... mesh-like resistance heating element pattern

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 3/74 H05B 3/74 (72) Inventor Koji Oishi 30 Soya, Hadano City, Kanagawa Prefecture Toshiba Ceramics Co., Ltd. In-development laboratory (72) Inventor Mitsuhiro Fujita 30 Soya, Hadano-shi, Kanagawa Toshiba Ceramics Co., Ltd. Development laboratory F-term (reference) 3K034 AA02 AA04 AA15 AA24 AA33 BA06 BB06 BB14 BC09 BC17 3K092 PP09 QA05 QB02 QB31 QB41 QB03 Q62 RF11 RF17 RF27 VV22

Claims (6)

[Claims] 1. A foil-shaped resistance heating element, which is made of tungsten foil or molybdenum foil to form a mesh pattern and has an aperture ratio of 5 to 75%. 2. The foil resistance heating element according to claim 1, wherein the mesh aperture ratio on the outer peripheral region side is set to be larger than the mesh aperture ratio on the central region. 3. The foil resistance heating element according to claim 1, wherein the mesh opening diameter on the outer peripheral side is set to be larger than the mesh opening diameter on the central area. 4. A step of performing a masking for etching corresponding to a mesh-shaped heating element pattern on a main surface of a tungsten foil or a molybdenum foil, and performing a chemical etching process on the masked metal foil to selectively etch the exposed portion of the mesh. A method for manufacturing a foil-shaped resistance heating element, comprising: a step of patterning a heating element for heating a sheet; and a step of removing the etching mask. 5. An aluminum nitride-based sintered body layer forming a heat radiation / heating surface, and a tungsten foil embedded and arranged in the aluminum nitride-based sintered body layer and having lead terminal pairs led out to the other main surface side. A planar heater comprising a molybdenum foil patterned mesh resistance heating element, wherein the mesh resistance heating element has an aperture ratio of 5 to 75%.
A planar heater characterized in that 6. The sheet heater according to claim 5, wherein the mesh-shaped resistance heating element has a larger opening ratio on the outer peripheral region side than that of the central region.