JP2002175867A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater, having superior temperature control property, without excessively making the dividing number of resistor exothermic body excessive, where the temperature of the heated face of a semiconductor wafer becomes uniform. SOLUTION: This ceramic heater with the resistor exothermic body being composed of an least two circuits formed on a disc shaped ceramic substrate, and the resistor exothermic body, notches or grooves being formed at the resistor exothermic body, dispersions in resistance values to the average resistance value of the resistor exothermic body are set to be not more than 5%, and the total number of the circuits of the resistor exothermic body set to be not more than 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater used mainly in the semiconductor industry for drying, sputtering and the like, and more particularly to a ceramic heater which is easy to control the temperature and has excellent temperature uniformity on a heating surface.

[0002]

2. Description of the Related Art Semiconductor products are manufactured through a process of forming a photosensitive resin on a semiconductor wafer as an etching resist and etching the semiconductor wafer. This photosensitive resin is a liquid and is applied to the surface of the semiconductor wafer using a spin coater or the like.However, it must be dried after application, and the applied semiconductor wafer is placed on a heater and heated. become. Conventionally, as a metal heater used for such an application, a heater in which a resistance heating element is arranged on the back surface of an aluminum plate has been adopted.

[0003] However, such a metal heater has the following problems.
There were the following problems. First, because it is made of metal,
The thickness of the ceramic substrate must be as thick as about 15 mm. This is because, in a thin metal plate, warping or distortion occurs due to thermal expansion caused by heating, and the semiconductor wafer mounted on the metal plate is damaged or tilted. However, when the thickness of the ceramic substrate is increased, the weight of the heater increases and the heater becomes bulky.

[0004] The heating temperature is controlled by changing the voltage or the amount of current applied to the resistance heating element.
Since the metal plate is thick, the temperature of the ceramic substrate does not quickly follow changes in voltage and current amount, and it is difficult to control the temperature.

Therefore, as proposed in Japanese Patent Publication No. 8-8247 and the like, there has been proposed a technique of using a nitride ceramic having a heating element and controlling the temperature while measuring the temperature in the vicinity of the heating element. Have been.

[0006]

However, when a semiconductor wafer is to be heated by using such a technique, a temperature difference occurs on a surface of the ceramic heater to be heated (hereinafter referred to as a heating surface), and the semiconductor wafer is heated. The temperature difference between the semiconductor wafers is increased, the degree of curing of the resin cured product on the semiconductor wafer becomes uneven, and the semiconductor wafer is damaged by thermal shock caused by the temperature difference on the heater surface. .
Therefore, the present inventors have recalled that the resistance heating element is divided into two or more circuits, and different power is supplied to each circuit based on the result of temperature measurement to perform temperature control.

However, in order to improve the accuracy of temperature control, it is necessary to increase the number of circuits of the resistance heating element, and until the semiconductor wafer can be heated uniformly, the number of circuits of the resistance heating element is reduced. If the number is increased, the temperature control becomes very complicated, so that a problem such as failure of a temperature control device such as a ceramic heater and a temperature controller occurs frequently. Further, in such a ceramic heater, manufacturing steps such as formation of a resistance heating element and connection of a temperature control device are complicated, so that manufacturing costs are increased.
On the other hand, even if the number of divisions of the circuit of the resistance heating element is increased, it is sometimes difficult to suppress the temperature variation on the heating surface of the ceramic heater.

Therefore, as a result of research conducted by the present inventors, it is sometimes difficult to suppress temperature variations on the heating surface of the ceramic heater even if the number of circuit divisions of the resistance heating element is increased. Because the heating element is formed using a technique such as screen printing, the thickness and width of the printing greatly vary, and as a result, the resistance value varies, making it difficult to control the temperature. I found it.

[0009]

The inventors of the present invention have conducted further studies. As a result, in order to control the temperature of the above ceramic heater reliably, trimming or the like is performed to reduce the resistance value of the resistance heating element. After adjustment, it has been found that temperature control may be performed for each divided circuit of the resistance heating element. Furthermore, with a ceramic heater in which the variation of the resistance value of the resistance heating element is suppressed to a certain value or less, even if the number of divisions of the circuit of the resistance heating element is set to eight or less, temperature control can be performed with extremely high accuracy. Since it is not necessary to increase the number of circuit divisions, it has been found that temperature control is not complicated, and the present invention has been completed.

That is, the ceramic heater of the present invention is a ceramic heater in which a resistance heating element composed of two or more circuits is formed on a disk-shaped ceramic substrate, wherein the resistance heating element has a notch or a groove. A ceramic heater which is formed and has a resistance value variation of 5% or less with respect to an average resistance value of the resistance heating element, and a total number of circuits of the resistance heating element is 8 or less.

According to the present invention, the variation in the resistance value of the resistance heating element is reduced to 5% or less due to trimming by laser light or blast processing or the like. There is little variation, heat can be generated uniformly in the circuit part,
The resistance heating element including such a circuit can uniformly heat the ceramic substrate. As a result, the number of circuit divisions of the resistance heating element can be reduced, and the temperature can be easily controlled. If the resistance value of the resistance heating element has a large variation, the amount of heat generated in one circuit varies. To compensate for this, the circuit is finely divided, and the temperature is controlled by changing the input power amount for each circuit. Need to be
In the present invention, since there is almost no variation in the resistance value, fine division is not required, and the temperature can be easily controlled.
Further, since the variation in the resistance value is small, the controllability is improved, and the temperature of the heating surface of the ceramic heater can be made uniform. The number of circuit divisions of the resistance heating element is 8
Since the number of divisions is not excessive, temperature control does not become complicated, and troubles such as failure of a temperature control device such as a ceramic heater and a temperature controller can be suppressed. Also, such ceramic heaters
The complexity of the manufacturing process is eliminated, and the manufacturing cost can be reduced.

[0012]

Next, a ceramic heater according to the present invention will be described. The ceramic heater according to the present invention is a ceramic heater in which a resistance heating element including two or more circuits is formed on a disk-shaped ceramic substrate, wherein the resistance heating element has a cutout or a groove formed therein. A ceramic heater characterized in that the variation of the resistance value with respect to the average resistance value of the heating element is 5% or less, and the total number of circuits of the resistance heating element is 8 or less.

As a method of adjusting the resistance value of the resistance heating element, for example, a method of trimming the resistance heating element formed on the ceramic substrate and forming a groove or a notch in the resistance heating element to adjust the resistance value, When a resistive heating element is formed by printing a conductive paste made of a metal or a metal and an oxide on a ceramic substrate by screen printing, the pattern of the conductive paste to be printed, that is, the pattern of the resistive heating element is devised. Examples of the method include adjusting the value.

Among the above-mentioned methods, it is desirable to trim the resistance heating element formed on the ceramic substrate and form a groove or notch in the resistance heating element to adjust the resistance value. This is because the resistance value can be adjusted more accurately. Note that two of the above methods can be used in combination. That is, a method of forming a resistance heating element having a pattern devised so as to reduce variation in resistance value, and adjusting the resistance value by trimming the resistance heating element. As a result, the resistance value can be adjusted more accurately.

FIGS. 1A to 1C are perspective views schematically showing grooves and notches formed when trimming is performed on a resistance heating element.

The groove 120 shown in FIG. 1A is a groove formed by trimming the surface of the resistance heating element 12 substantially in parallel along the direction of current flow.
The notch 130 shown in (b) is a notch formed by trimming the side surface of the resistance heating element 12 substantially perpendicularly to the direction in which current flows, and the notch 130 shown in FIG.
Reference numeral 40 denotes a groove formed by trimming a part of the thickness of the resistance heating element 12 thinly over the entire width. The notch refers to one kind of cut formed to locally reduce the width of the resistance heating element. By making a cut, the width of the resistance heating element is locally reduced to adjust the resistance value. Is what you do. At that time, the notch may be formed so that the thickness of the resistance heating element is partially reduced,
The notch may be formed so that the bottom of the notch reaches the surface of the ceramic substrate.

In the present invention, the resistance value of the resistance heating element can be adjusted by any of these methods to reduce the variation in the resistance value to 5% or less.
As shown in (1), it is desirable to form a groove by trimming the surface of the resistance heating element substantially parallel to the direction in which current flows, and to adjust the resistance value. This is because the resistance value can be adjusted relatively easily and accurately.

If a notch is formed on the side surface of the resistance heating element such that the bottom of the notch reaches the surface of the ceramic substrate, a portion where the resistance value is locally increased occurs, and the resistance heating element is melted by heat generation. In some cases, when the notch having the shape shown in FIG. 1C is to be formed, it is difficult to control the thickness.

Next, as shown in FIG. 1A, a description will be given of a groove formed by trimming the surface of a resistance heating element substantially parallel to the direction in which current flows.
FIGS. 2A to 2C are perspective views schematically showing another embodiment of the groove formed by trimming the surface of the resistance heating element substantially parallel to the current flowing direction.

2A, two grooves 121 parallel to the resistance heating element 12 are formed on the surface of the resistance heating element 12, and FIG. 2C, a groove 122 is formed so as to draw a curve. In FIG. 2C, a groove 123 is formed on the surface of the resistance heating element so as to draw an oblique line with respect to the current propagation direction. ing.

Even if any of the grooves shown in FIGS. 2A to 2C is formed, the resistance value can be easily and accurately adjusted. In other words, being substantially parallel means that the current propagation direction and the groove formation direction need not be mathematically parallel, and the groove formation direction is parallel to the current propagation direction.
Alternatively, the angle formed between the current propagation direction and the groove forming direction may be an acute angle.

The groove formed by the trimming desirably has a depth of 20% or more of the thickness of the resistance heating element.
It is more desirable to have the above depth. If it is less than 20%, there is almost no change in the resistance value.

When the trimming is performed by the above-described method, the width of the resistance heating element pattern is preferably 0.5 mm or more. If the thickness is less than 0.5 mm, it is difficult to perform trimming substantially parallel to the direction in which the current flows through the resistance heating element.

The width of the groove is desirably about 1 to 100 μm. If the width exceeds 100 μm, disconnection or the like is likely to occur, while if the width is less than 1 μm, it becomes difficult to adjust the resistance value of the resistance heating element. When performing trimming by laser light, the laser spot diameter is adjusted to 1 μm to 2 cm.

The variation of the resistance value of the resistance heating element is as follows.
When printing the resistance heating element, it is desirable to make the thickness, width, and the like uniform to suppress the resistance heating element to 25% or less. This is because the smaller the variation at the printing stage of the resistance heating element, the easier the adjustment by trimming.

It is desirable that the trimming is performed by measuring the resistance value of the resistance heating element and based on the measured value. This is because the resistance value can be accurately adjusted. In the measurement of the resistance value, the resistance heating element pattern is divided into a plurality of sections, and the resistance value is measured for each section. Then, a trimming process is performed on a section having a low resistance value.

After the completion of the trimming process, the resistance value may be measured again, and the trimming may be further performed if necessary. That is, the resistance value measurement and the trimming may be performed not only once but also two or more times.

The trimming is preferably carried out after printing the resistive heating element paste and firing it. This is because the resistance value fluctuates due to baking, and in the case of trimming using laser light, if trimming is performed before baking, there is a possibility of peeling due to irradiation with laser light.

Alternatively, the resistance heating element paste may be first printed in a planar shape (so-called solid shape) and then patterned by trimming. When trying to print in a pattern from the beginning, the thickness varies depending on the printing direction, but when printing in a plane, it is possible to print with a uniform thickness, so this is trimmed and patterned. Thereby, a heating element pattern having a uniform thickness can be obtained.

The above-mentioned trimming can be performed by using a laser beam irradiation or a polishing process such as sandblasting or belt sanding. However, since the resistance heating element is usually formed of a metal or a conductive paste made of a metal and an oxide, the groove having the above-described shape can be formed by trimming using laser light (hereinafter, also referred to as laser trimming). desirable. This is because the metal is evaporated and removed by the laser, but the ceramic is not removed.
As a result, accurate trimming can be realized without any removal residue and without damaging the ceramic substrate.

FIG. 3 is a block diagram showing an outline of a laser trimming device used for adjusting the resistance value of a resistance heating element formed on a ceramic substrate. As shown in FIG. 3, a disc-shaped ceramic substrate 11 on which a resistive heating element 12 having a desired pattern is formed is fixed on the table 23 using fixing protrusions 23b and the like.

The table 23 is provided with a motor and the like (not shown). The motor and the like are connected to a control unit 27, and the motor and the like are driven by a signal from the control unit 27. As a result, the table 23
It can be freely moved in the direction (rotation direction of the ceramic substrate) and the xy directions.

On the other hand, a galvanometer mirror 25 is provided above the table 23, and the angle of the galvanometer mirror 25 can be freely changed in the x direction by a motor 26. Table 2
The laser beam 32 emitted from the laser irradiation device 24 disposed above the laser beam 3 strikes the galvanomirror 25 and is reflected to irradiate the ceramic substrate 11. Note that the galvanometer mirror provided in the laser trimming device used for manufacturing the ceramic heater of the present invention only needs to rotate in one direction. This is because if only control in one direction (r direction) is performed, the laser can be applied to an arbitrary position on the ceramic substrate in combination with rotation of the table or the like.

The motor 26 and the laser irradiation device 3
Reference numeral 5 is connected to the control unit 27, and drives the motor 26 and the laser irradiation device 35 by a signal from the control unit 27, thereby rotating the galvanometer mirror 25 by a predetermined angle around the x direction. The table 23 is rotated in the θ direction by driving a motor (not shown) provided on the table 23 with a signal from the control unit 27. Rotation of the galvanometer mirror 25 about the x direction and the table 23
The irradiation position on the ceramic substrate 11 can be freely set by the rotation in the θ direction. The table 23 can move not only in the θ direction but also in the xy directions.

As described above, by moving the table 23 on which the ceramic substrate 11 is placed and / or the galvanomirror 25, an arbitrary position on the ceramic substrate 11 can be irradiated with the laser beam 32.

On the other hand, above the table 23, the camera 3
1 is also installed, and thereby, the ceramic substrate 11
The position (r, θ or xy) of the upper resistance heating element 12 can be recognized. This camera 31
Is connected to the storage unit 28, whereby the position (r, θ or xy) of the resistance heating element 12 on the ceramic substrate 11 is
The laser beam 32 is applied to the position.

The input unit 30 is connected to the storage unit 28 and has a keyboard or the like (not shown) as a terminal. A predetermined instruction or the like is input through the storage unit 28 or the keyboard. It is supposed to be.

Further, this laser trimming device is provided with a calculation unit 29, and based on data such as the position and thickness of the ceramic substrate 11 recognized by the camera 31,
Calculation for controlling the irradiation position, irradiation speed, laser light intensity, and the like of the laser light 32 is performed, and based on the calculation result, an instruction is issued from the control unit 27 to the motor 26, the laser irradiation device 35, and the like. Or the table 23 is moved or rotated to irradiate the laser beam 32 to trim the resistance heating element 12 to form a groove or a notch.

The laser trimming device has a resistance measuring section 33. The resistance measurement unit 33 includes a plurality of tester pins 34, divides the resistance heating element into a plurality of sections, makes the tester pins contact each section, measures the resistance value of the formed resistance heating element pattern, By irradiating the corresponding section with the laser, the thickness and width of the resistance heating element are adjusted, and a resistance heating element having a desired resistance value can be obtained.

Next, a method for manufacturing a ceramic heater using such a laser trimming device will be specifically described. Here, the step of forming a resistive heating element pattern using laser trimming, which is a main part of the present invention, will be described in detail, and the other steps will be described in detail later, and thus will be briefly described here.

(1) First, a ceramic substrate is manufactured. First, a formed body made of ceramic powder and resin is prepared. As a method of producing the formed body, a method of producing granules containing a ceramic powder and a resin, then putting the granules in a mold or the like and applying a press pressure, and a method of laminating and pressing green sheets are used. There is a manufacturing method, and a more appropriate method is selected depending on whether or not another conductive layer such as an electrostatic electrode is formed inside. Thereafter, the formed substrate is degreased and fired to produce a ceramic substrate. Thereafter, a through hole for inserting a lifter pin into the ceramic substrate, a bottomed hole for burying a temperature measuring element, and the like are formed.

(2) Next, a conductor paste layer is formed on the ceramic substrate 11 by screen printing or the like.
The resistance heating element 12 is obtained by firing. The resistance heating element 12 is formed using a physical vapor deposition method such as plating or sputtering.
May be formed. In the case of plating, by forming a plating resist, in the case of sputtering, etc.,
By performing selective etching, the resistance heating element 12
Can be formed. However, in the case of screen printing, the problem of unevenness in the thickness of the resistance heating element is more likely to occur than in the plating method or the like, so that a method of adjusting the resistance value by trimming is effective.

(3) Next, the ceramic substrate 11 on which the resistance heating element 12 is formed is fixed on the table 23 using fixing projections 23b and fitting projections (not shown) provided on the table 23. .

(4) Next, the fixed ceramic substrate 1
1 is photographed by the camera 31 so that the resistance heating element 12
Are stored in the storage unit 28.

(5) Next, the resistance value of each portion of the formed resistance heating element 12 is measured by the resistance measuring section 33 of the laser trimming device. The resistance value is measured by dividing the resistance heating element pattern into a plurality of sections and measuring the resistance value of each section using the tester pins 34. The data of the resistance value of the resistance heating element measured in this way is stored in the storage unit 28.

The position (shape) data of the resistance heating element 12, the data of the resistance value in each part of the resistance heating element, and the laser irradiation intensity determined based on the characteristics (material, thickness, etc.) of the resistance heating element Based on data of irradiation conditions such as
Is performed to calculate the length, depth, and width of the groove or notch, and the result is stored in the storage unit 28 as control data.

At this time, if the resistance heating element 12 is based on concentric circle patterns, most of these patterns can be represented by the distance r from the center of the ceramic substrate 11 and the rotation angle θ. The data is, for example, a distance r ₁ from the center A and an angle θ as a laser irradiation start position.
Set with ₁ and the distance of the groove etc. is the rotation distance (θ ₁ −θ ₂ )
Can be set with. That is, it is possible to simplify the system and program for setting the position, and it is possible to easily, quickly and accurately adjust the resistance value of the resistance heating element.

(6) Next, a trimming process is actually performed according to the stored trimming data. Specifically, a control signal is generated from the control unit 27 based on the trimming data, and while the motor 26 of the galvanomirror 25 and / or the motor of the table 23 are driven,
The trimming process is performed by irradiating a laser beam. By performing such trimming, for example, sequentially on sections having a resistance value lower than a desired value, the adjustment of the resistance value is completed.

The above-mentioned adjustment of the resistance value may be carried out by a trimming operation or the like by moving the table in the xy directions with xy as the coordinates.

When the resistance value is adjusted by laser trimming as described above, the portion to be trimmed by laser light irradiation is trimmed, but the ceramic substrate underneath is greatly affected by the laser light irradiation. It is important that there is no.

Therefore, it is necessary to select a laser beam that is well absorbed by metal particles and the like constituting the conductor layer and the like, but is hardly absorbed by the ceramic substrate. Examples of such a type of laser include a YAG laser, a carbon dioxide laser, an excimer (KrF) laser, a UV (ultraviolet) laser, and the like. Among them, YAG
Lasers and excimer (KrF) lasers are most suitable.

As a YAG laser, an SAG manufactured by NEC Corporation is used.
L432H, SL436G, SL432GT, SL41
1B can be adopted. Preferably, the laser is pulsed light. This is because large energy can be applied to the resistance heating element in an extremely short time, and damage to the ceramic substrate can be reduced. The pulse is preferably 2 kHz or less, more preferably 1 kHz or less. When the frequency exceeds 2 kHz, the energy of the first pulse of the laser becomes too large, and a groove wider than the setting is formed, so that a resistive heating element having a shape as set cannot be formed.

The processing speed is desirably 100 mm / sec or less. If the speed exceeds 100 mm / sec, grooves cannot be formed unless the frequency is increased. As described above, since the upper limit of the frequency is 2 kHz or less, the frequency is preferably 100 mm / sec or less. Further, when the resistance heating element is completely disconnected, the output of the laser is set to 0.
3 W or more is desirable.

When a conductive paste made of a metal or a metal and an oxide is printed on a ceramic substrate by screen printing to form a resistance heating element, a pattern of the conductor paste to be printed, that is, a pattern of the resistance heating element is devised. This makes it possible to adjust the resistance value.

FIG. 4 is an explanatory view showing a state in which a spiral resistance heating element pattern is printed, and FIG. 5 is an explanatory view showing a state in which a bent resistance heating element pattern is printed.

In FIG. 4, a spiral-shaped resistance heating element 42 is formed along the printing direction indicated by the arrow. In this case, in the resistance heating element 42, in a region A where the printing direction and the formation direction of the resistance heating element are close to a right angle, the thickness of the resistance heating element is large, while the printing direction and the formation direction of the resistance heating element are parallel. In the region B which is close to the above, the thickness of the resistance heating element tends to be thin. Therefore, the resistance value is low in the region A, and the resistance value is high in the region B, and a temperature variation occurs on the heating surface.

On the other hand, in FIG. 5, a resistance heating element 52 having a repetitive pattern of a bent line is formed along the printing direction indicated by the arrow. In this case, in the bent portion of the resistance heating element 52, a part C in which the printing direction is substantially perpendicular to the forming direction of the resistance heating element and a part D in which the direction is parallel are generated, so that the amount of generated heat is uniform as a whole. . For this reason, it is possible to reduce the temperature variation caused by the variation in the resistance value of the resistance heating element 52.

As described above, by making the pattern of the resistance heating element a repetitive pattern of a bent line shape or a pattern composed of a bent line, it is possible to suppress the variation in the resistance value.

In the ceramic heater according to the present invention, the total number of circuits of the resistance heating element whose variation in resistance is suppressed to 5% or less by the above-described method or the like is 8 or less.

In the ceramic heater of the present invention, the number of divisions of the circuit of the resistance heating element is set to eight or less, so that the number of divisions is not excessive, and as a result, the temperature control is not complicated, It is possible to suppress troubles such as a failure of a temperature control device such as a heater and a temperature controller. Further, such a ceramic heater can reduce the complexity of the manufacturing process and reduce the manufacturing cost.

Although the temperature control can be performed even if the number of circuit divisions is set to be more than 8, the temperature control becomes complicated, so that the ceramic heater and the temperature controller are not used. Troubles such as failure of the temperature control device are likely to occur.

FIG. 6 is a bottom view schematically showing one example of the ceramic heater of the present invention, and FIG. 7 is a partially enlarged sectional view showing a part thereof.

In this ceramic heater 10, a groove (not shown) or the like is formed by trimming or the like on the bottom surface 11b opposite to the heating surface 11a of the ceramic substrate 11 formed in a disk shape. Is adjusted to 5% or less.

The resistance heating elements 12 are formed on the outermost periphery of the ceramic substrate 11 in an arc pattern repeatedly formed so as to draw a part of a concentric circle.
2d are arranged therein, and resistance heating elements 12e to 12g, which are concentric circular patterns partially cut away, are arranged therein.

The outermost resistive heating element 12a is formed by repeatedly forming an arc-shaped pattern obtained by dividing a concentric circle into four in the circumferential direction, and ends of adjacent arcs are connected by a bent line to form a series of circuits. ing. Then, four circuits of the resistance heating elements 12a to 12d having the same pattern are formed close to each other so as to surround the outer periphery, and constitute an overall annular pattern.

The ends of the resistance heating elements 12a to 12d are formed inside an annular pattern in order to prevent the occurrence of a cooling spot or the like. It is extended toward.

Resistance heating elements 12a-1 formed on the outermost periphery
Inside the 2d, there are formed resistance heating elements 12e to 12g each formed of a circuit of a concentric pattern whose part is cut off. In the resistance heating elements 12e to 12g, a series of circuits is formed by connecting the ends of adjacent concentric circles sequentially with a resistance heating element formed of a straight line.

The resistance heating elements 12a to 12d, 12
Between e, 12f, and 12g, a belt-shaped (annular) non-heating element non-forming area is provided, and a circular heating element non-forming area is also provided at the center.

Accordingly, as a whole, the annular resistance heating element forming area and the heating element non-forming area are alternately formed from the outside to the inside, and these areas are defined by the size (diameter) of the ceramic substrate. ), Thickness, etc., the temperature can be made uniform by setting the temperature appropriately.

Further, the resistance heating elements 12 (12a to 12a)
In (g), external terminals 13 serving as input / output terminals are connected to both ends thereof via a metal coating layer 120a. A through hole 15 for inserting a lifter pin 16 supporting a semiconductor wafer 39 is formed in a portion near the center, and a bottomed hole 14 for inserting a thermocouple 17 as a temperature measuring element is formed. Is formed.

FIG. 8 is a bottom view schematically showing another embodiment of the ceramic heater of the present invention. In the ceramic heater 60, a groove (not shown) or the like is formed by trimming or the like on the bottom surface opposite to the heating surface of the ceramic substrate 61 formed in a disc shape, and the variation in resistance value is reduced to 5% or less. An adjusted resistance heating element 62 is formed.

In the resistance heating element 62, resistance heating elements 62a to 62d each having a repetitive pattern of bent lines are arranged on the outermost periphery of the ceramic substrate 61, and resistance heating elements 62e to 62h each having a concentric pattern are disposed inside the resistance heating elements 62e to 62h. Are located.

The total number of circuits of the resistance heating element formed in the ceramic heater of the present invention must be 2 or more and 8 or less, but the total number of circuits is not particularly limited as long as it is within the range. It is not something to be done. However, in order to make the temperature of the heating surface of the ceramic heater more uniform, when the diameter of the ceramic substrate is 200 to 300 mm, the total number of circuits is preferably 2 to 7. Also, if the diameter of the ceramic substrate is 3
If it exceeds 00 mm, the total number of circuits is preferably 7 to 8.

The pattern of the resistance heating element is not particularly limited. For example, the pattern shown in FIG. 6, which is a combination of a repetition pattern of arcs and a concentric pattern, FIG.
, A combined pattern of a bent line and a concentric pattern, a spiral pattern, an eccentric pattern, and a repeated pattern of a bent line. These can be used in combination.

Among them, it is desirable to use a repetition pattern of a circular arc, a concentric pattern, and a repetition pattern of a bent line. As described above, the use of the circular arc repetition pattern and / or the concentric pattern makes it possible to easily and accurately set the laser irradiation position when performing laser trimming, and as a result, to adjust the resistance value with high accuracy. In addition, when a repetitive pattern of bent lines is used, variation in the thickness of the resistance heating element due to screen printing can be reduced, and as a result, variation in the resistance value can be suppressed. .

Further, with regard to the pattern arrangement, finer control of the amount of generated heat can be performed in the outer peripheral portion of the ceramic substrate which has a large amount of heat radiation. Therefore, as shown in the patterns of FIGS. A resistance heating element composed of at least two or more circuits is arranged on the outer circumference in the circumferential direction, and a resistance heating element composed of another circuit is arranged inside the resistance heating element arranged on the outermost circumference. Pattern is desirable.

The pattern divided in the circumferential direction means that a plurality of line segments are drawn from the center of the ceramic substrate to the outer periphery.
This is a pattern formed in a region divided by the line segment. Usually, it is desirable that all the areas have the same size.

In FIGS. 6 and 8, the resistance heating element 1
2a to 12d and 62a to 62d are resistance heating elements arranged at the outermost periphery, and such resistance heating elements at the outermost periphery are:
It is desirable that the area be formed in a region 90% or more from the center to the distance from the outer periphery to the center. If it is less than 90%, the area of the resistance heating element formed on the outermost periphery becomes too large, so that it becomes difficult to control the temperature of the heating surface.

Further, it is desirable that the number of circuits of the resistance heating element formed on the outermost periphery and the number of circuits of the resistance heating element formed therein are substantially equal. If the number of circuits on the outermost periphery is extremely large, the number of circuits in the inside will be small, and it will be difficult to accurately control the amount of heat generation inside the ceramic substrate. This is because accurate temperature control cannot be performed.

In the ceramic heater of the present invention, the thickness of the resistance heating element formed on the surface of the ceramic substrate is 1
-30 μm is preferable, and 1-10 μm is more preferable.
Further, the width of the resistance heating element is preferably from 0.1 to 20 mm, more preferably from 0.1 to 5 mm. Although the resistance value of the resistance heating element can be varied depending on its width or thickness, the above range is most practical.

The resistance heating element may have a rectangular or elliptical cross section, but is preferably flat. This is because the flat surface is more likely to dissipate heat toward the heating surface, so that the temperature distribution on the heating surface is less likely to occur. The aspect ratio of the cross section (the width of the resistance heating element / the thickness of the resistance heating element) is 10 to 50.
00 is desirable. By adjusting to this range, the resistance value of the resistance heating element can be increased, and the uniformity of the temperature of the heating surface can be ensured.

When the thickness of the resistance heating element is constant, if the aspect ratio is smaller than the above range, the amount of heat transmission in the direction of the heating surface of the ceramic substrate becomes small, and the heat distribution approximates the pattern of the resistance heating element. If the aspect ratio is too large, on the other hand, if the aspect ratio is too large, the temperature immediately above the center of the resistance heating element becomes high, and eventually, a heat distribution similar to the pattern of the resistance heating element occurs on the heating surface. Would. Therefore, considering the temperature distribution, the aspect ratio of the cross section is 1
It is preferably from 0 to 5000.

The conductive paste is not particularly limited, but preferably contains not only metal particles or conductive ceramic for ensuring conductivity, but also resin, solvent, thickener and the like.

The metal particles are preferably, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like. These may be used alone or in combination of two or more. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat. Examples of the conductive ceramic include carbides of tungsten and molybdenum. These may be used alone or in combination of two or more.

The metal particles or conductive ceramic particles preferably have a particle size of 0.1 to 100 μm. 0.1μ
If the particle size is too small, it is easily oxidized.
If the thickness exceeds μm, sintering becomes difficult and the resistance value increases.

Although the shape of the metal particles is spherical,
It may be scaly. When these metal particles are used, they may be a mixture of the above-mentioned spheres and the above-mentioned flakes. When the metal particles are flakes or a mixture of spheres and flakes, the metal oxide between the metal particles is easily retained, and the adhesion between the resistance heating element and the nitride ceramic or the like is improved. And it is advantageous because the resistance value can be increased.

As the resin used for the conductor paste,
For example, an epoxy resin, a phenol resin, and the like can be given. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose and the like.

It is preferable that the conductor paste is obtained by adding a metal oxide to metal particles and sintering the resistance heating element, the metal particles and the metal oxide. In this way, by sintering the metal oxide together with the metal particles, the ceramic substrate, such as a nitride ceramic, and the metal particles can be more closely adhered.

It is not clear why the mixing with the metal oxide improves the adhesion to the nitride ceramic or the like, but the surface of the metal particles or the surface of the nitride ceramic or the like is slightly oxidized to form an oxide film. It is considered that these oxide films are sintered and integrated via the metal oxide, and the metal particles and the nitride ceramics or the like adhere to each other. Further, when the ceramic constituting the ceramic substrate is an oxide ceramic, the surface is naturally made of an oxide, so that a conductor layer having excellent adhesion is formed.

As the metal oxide, for example, oxidized
Lead, zinc oxide, silica, boron oxide (B _Two O_Three ), Al
Selected from the group consisting of Mina, Yttria and Titania
At least one is preferred. These oxides have resistance
Nitriding of metal particles without increasing the resistance of the heating element
Can improve the adhesion to ceramics etc.
It is.

The ratios of the above-mentioned lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania are as follows. 1-10, silica 1-30, boron oxide 5-50, zinc oxide 20-70, alumina 1
-10, yttria 1-50, titania 1-50, and the total is preferably adjusted within a range not exceeding 100 parts by weight. By adjusting the amounts of these oxides within these ranges, the adhesion to nitride ceramics and the like can be particularly improved.

The amount of the metal oxide added to the metal particles is preferably 0.1% by weight or more and less than 10% by weight. The area resistivity when the resistance heating element is formed using the conductor paste having such a configuration is preferably 0.1 to 10 Ω / □.

When the area resistivity is less than 0.1 Ω / □, the width of the resistive heating element pattern is set to 0.
The thickness must be very thin, about 1 to 1 mm. For this reason, if the pattern breaks due to a slight chipping or the like, the resistance value fluctuates, and if the area resistivity exceeds 10Ω / □, the resistance heating element Without increasing the width of the pattern, the amount of heat generated cannot be secured, and as a result, the degree of freedom in pattern design decreases,
This is because it is difficult to make the temperature of the heating surface uniform.

When the resistance heating element is formed on the surface of the ceramic substrate, it is desirable that a metal coating layer is formed on the surface of the resistance heating element. This is to prevent the internal metal sintered body from being oxidized to change the resistance value.
The thickness of the metal coating layer to be formed is preferably 0.1 to 10 μm.

The metal used for forming the metal coating layer is not particularly limited as long as it is a non-oxidizing metal, and specific examples thereof include gold, silver, palladium, platinum and nickel. . These may be used alone or in combination of two or more. Of these, nickel is preferred.

The resistance heating element requires a terminal for connection to a power source, and this terminal is attached to the resistance heating element via solder. Nickel prevents thermal diffusion of the solder. Examples of the connection terminal include those made of Kovar.

The ceramic forming the ceramic heater of the present invention is preferably a nitride ceramic or a carbide ceramic. Nitride ceramics and carbide ceramics have a lower coefficient of thermal expansion than metals and have much higher mechanical strength than metals, so even if the thickness of the ceramic substrate is reduced, it does not warp or warp due to heating .
Therefore, the ceramic substrate can be made thin and light. Furthermore, the thermal conductivity of the ceramic substrate is high,
Since the ceramic substrate itself is thin, the surface temperature of the ceramic substrate quickly follows the temperature change of the resistance heating element. That is, the surface temperature of the ceramic substrate can be controlled by changing the voltage and the current value to change the temperature of the resistance heating element. In addition, nitride ceramics and carbide ceramics have a high thermal conductivity, so that the temperature variation due to the heating element pattern is likely to occur. Therefore, the configuration of the present invention functions more effectively than oxide ceramics.

As the nitride ceramic, for example,
Examples include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. These may be used alone or 2
More than one species may be used in combination.

Examples of the carbide ceramic include, for example, silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, tungsten carbide and the like. These may be used alone or in combination of two or more.

Of these, aluminum nitride is most preferred. The highest thermal conductivity is 180W / m · K,
This is because it has excellent temperature followability.

When a nitride ceramic, a carbide ceramic, or the like is used as the ceramic substrate, an insulating layer may be formed as necessary. Nitride ceramics have a tendency to decrease in volume resistance at high temperatures due to oxygen solid solution, etc.Carbide ceramics have conductivity unless particularly highly purified. This is because, even if it contains, a short circuit between circuits can be prevented and the temperature controllability can be secured.

The insulating layer is preferably made of an oxide ceramic, specifically, silica, alumina, mullite,
Cordierite, beryllia and the like can be used.
Such an insulating layer may be formed by spin-coating a sol solution obtained by hydrolyzing and polymerizing an alkoxide on a ceramic substrate, followed by drying and firing, or by sputtering, CVD, or the like. Further, an oxide layer may be provided by oxidizing the surface of the ceramic substrate.

The thickness of the insulating layer is desirably 0.1 to 1000 μm. If the thickness is less than 0.1 μm, the insulating property cannot be secured, and if the thickness exceeds 1000 μm, the thermal conductivity from the resistance heating element to the ceramic substrate is hindered.
Further, it is desirable that the volume resistivity of the insulating layer is 10 times or more (same measurement temperature) as the volume resistivity of the ceramic substrate. If it is less than 10 times, a short circuit cannot be prevented.

The thickness of the ceramic substrate 11 is 0.5 to 5
mm is preferred. If the thickness is less than 0.5 mm, the strength is reduced and the material is easily damaged. On the other hand, if the thickness is more than 5 mm, heat is difficult to propagate, and the heating efficiency is deteriorated.

The diameter of the ceramic substrate 11 is 20
0 mm or more is desirable. This is because the configuration of the present invention functions effectively because the temperature of the heating surface is more likely to be non-uniform as the diameter of the ceramic substrate is larger and the number of circuit divisions needs to be increased. In addition, a substrate having such a large diameter can mount a large-diameter semiconductor wafer. The diameter of the ceramic substrate is particularly preferably 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

In the ceramic heater according to the present invention, the ceramic substrate is provided with a bottomed hole from the side opposite to the heating surface on which the object to be heated is placed toward the heating surface, and the bottom of the bottomed hole is set by the resistance heating element. It is also preferable to form the temperature measuring element such as a thermocouple in the bottomed hole relatively.

The distance between the bottom of the bottomed hole and the heating surface is:
It is desirable that the thickness be 0.1 mm to 1/2 of the thickness of the ceramic substrate. Thereby, the temperature measurement location is closer to the heating surface than the resistance heating element, and the temperature of the semiconductor wafer can be measured more accurately.

The distance between the bottom of the bottomed hole and the heating surface is 0.1 mm
If the thickness is less than the above, heat is dissipated, and a temperature distribution is formed on the heating surface. If the thickness is more than 1/2 of the thickness, the temperature of the resistance heating element becomes more susceptible to temperature control, and the temperature distribution cannot be controlled. Is formed.

It is desirable that the diameter of the bottomed hole is 0.3 mm to 5 mm. This is because if it is too large, the heat dissipation will be large, and if it is too small, the workability will be reduced and the distance to the heating surface cannot be equalized.

As shown in FIG. 1, it is desirable that a plurality of the bottomed holes are arranged symmetrically with respect to the center of the ceramic substrate and form a cross. This is because the temperature of the entire heating surface can be measured.

As the temperature measuring element, for example, a thermocouple,
Platinum resistance thermometers, thermistors and the like can be mentioned. As the thermocouple, for example, JIS-C-1602 (1
980), K type, R type, B type, S type
Type, E-type, J-type, and T-type thermocouples, and among them, a K-type thermocouple is preferable.

It is desirable that the size of the junction of the thermocouple is the same as or larger than the diameter of the strand, and is 0.5 mm or less. This is because, if the junction is large, the heat capacity increases and the responsiveness decreases. It is difficult to make the diameter smaller than the diameter of the strand.

The temperature measuring element may be adhered to the bottom of the bottomed hole using gold brazing or silver brazing, or may be inserted into the bottomed hole and then sealed with a heat-resistant resin. , May be used in combination. Examples of the heat-resistant resin include a thermosetting resin, particularly an epoxy resin, a polyimide resin, a bismaleimide-triazine resin, and the like. These resins may be used alone or in combination of two or more.

The above-mentioned gold brazing fillers include 37-80.5% by weight Au-63-19.5% by weight Cu alloy, 81.5-8%
2.5% by weight: Au-18.5 to 17.5% by weight: Ni
At least one selected from alloys is desirable. These are because the melting temperature is 900 ° C. or higher and it is difficult to melt even in a high temperature region. As a silver solder, for example, Ag
-A Cu-based material can be used.

Next, a method for manufacturing the ceramic heater of the present invention will be described. 9A to 9D are cross-sectional views schematically showing a method for manufacturing a ceramic heater in which a resistance heating element on the bottom surface of a ceramic substrate is formed.

(1) Step of Manufacturing Ceramic Substrate The above-mentioned ceramic powder such as nitride such as aluminum nitride or silicon carbide is added to yttria (Y ₂ O
₃ ) and sintering aids such as B ₄ C, compounds containing Na and Ca,
After preparing a slurry by blending a binder and the like, the slurry is formed into granules by a method such as spray drying, and the granules are put into a mold or the like and pressed to be formed into a plate shape, thereby forming a green body (green). Is prepared. Next, the formed body is heated, fired and sintered to produce a ceramic plate. Thereafter, the ceramic substrate 11 is manufactured by processing into a predetermined shape, but may be formed into a shape that can be used as it is after firing (FIG. 9).
(A)).

By performing heating and firing while applying pressure, it is possible to manufacture a ceramic substrate 11 having no pores. Heating and firing may be performed at a sintering temperature or higher.
0 to 2500 ° C. In oxide ceramics,
1500 ° C to 2000 ° C.

Next, as necessary, a portion serving as a through hole 15 for inserting a lifter pin for supporting a semiconductor wafer and a bottomed hole for embedding a temperature measuring element such as a thermocouple 17 are formed in the ceramic substrate 11. A portion to be 14 is formed.

(2) Step of Printing Conductive Paste on Ceramic Substrate The conductive paste is a high-viscosity fluid composed of metal particles composed of two or more kinds of noble metals, a resin, and a solvent. A conductor paste layer serving as a resistance heating element pattern is formed by using the conductor paste by screen printing or the like so that the total number of circuits of the resistance heating element 12 provided on the ceramic substrate 11 is 8 or less.

At this time, a conductor paste layer is formed on the outermost periphery of the ceramic substrate so as to form at least two circuits divided in the circumferential direction, and the inside of the conductor paste layer printed on the outermost periphery is formed. It is desirable to form a conductor paste layer that becomes another circuit. Further, as the resistance heating element pattern, a circular arc repetition pattern and / or
Alternatively, when using a concentric pattern, the laser irradiation position can be easily and accurately set when performing laser trimming, and when performing screen printing using a repetitive pattern of bent lines, the thickness of the resistance heating element can be reduced. Variation can be suppressed.

(3) Firing of Conductive Paste The conductive paste layer printed on the bottom surface of the ceramic substrate 11 is heated and fired to remove the resin and the solvent, and sinter the metal particles.
The resistance heating element 12 is formed (FIG. 9B). The temperature of the heating and firing is preferably from 500 to 1000C. If the above-mentioned oxide is added to the conductor paste, the metal particles, the ceramic substrate and the oxide are sintered and integrated, so that the adhesion between the resistance heating element 12 and the ceramic substrate 11 is improved.

(4) Adjustment of the resistance value of the resistance heating element Next, as described above, the resistance value was measured, and the resistance heating element 1 was measured.
The resistance value is adjusted by forming the groove 120 and the like in FIG. 2 (FIG. 9C). At this time, it is desirable to adjust the resistance value of the resistance heating element 12 by laser trimming, since the resistance value can be easily and accurately adjusted.

(5) Formation of Metal Coating Layer A metal coating layer (not shown) is provided on the surface of the resistance heating element 12. The metal coating layer (not shown) can be formed by electrolytic plating, electroless plating, sputtering, or the like, but in consideration of mass productivity, electroless plating is optimal.

(6) Attachment of Terminals and the like Terminals (external terminals 13) for connection to a power supply are attached to the end of the pattern of the resistance heating element 12 by soldering. Further, the thermocouple 17 is fixed to the bottomed hole 14 with silver brazing, gold brazing or the like,
After sealing with a heat-resistant resin such as polyimide, the manufacture of the ceramic heater is completed (FIG. 9D). In the ceramic heater of the present invention, an electrostatic chuck may be provided by providing an electrostatic electrode, or a chuck top plate for a wafer prober may be provided by providing a chaptop conductor layer.

[0125]

The present invention will be described in more detail below. Example 1 Production of Aluminum Nitride Ceramic Heater (See FIG. 1) (1) Aluminum Nitride Powder (Average Particle Size: 1.1 μm) 1
A composition comprising 00 parts by weight, 4 parts by weight of yttria (average particle size: 0.4 μm), 12 parts by weight of an acrylic binder and alcohol was spray-dried to prepare a granular powder.

(2) Next, the granulated powder was put in a mold and formed into a flat plate to obtain a formed product (green). (3) The processed form is processed at 1800 ° C., pressure: 2
Hot pressing was performed at 0 MPa to obtain an aluminum nitride plate having a thickness of 3 mm. Next, a diameter of 300
mm was cut out to obtain a ceramic plate (ceramic substrate) 11.

Drilling is performed on this molded body to form a portion serving as a through hole 15 for inserting a lifter pin for supporting a semiconductor wafer and a portion serving as a bottomed hole 14 for embedding a thermocouple (diameter: 1.1 mm, depth: (2 mm) (FIG. 9).
(A)).

(4) The ceramic substrate 11 obtained in the above (3)
Then, a conductor paste was printed by screen printing, and a conductor paste layer was formed such that the total number of circuits of the resistance heating element 12 became 7. This is a value set so that the total number of circuits of the resistance heating element 12 provided on the ceramic substrate 11 is 8 or less. Further, as shown in FIG. 6, as a printing pattern, a repetition pattern of circular arcs formed by dividing a concentric circle in the outermost circumference in the circumferential direction and a concentric pattern inside the same are formed.

As the conductive paste, Solvest PS603D manufactured by Tokurika Kagaku Kenkyusho used for forming through holes in a printed wiring board was used. This conductor paste is a silver-lead paste, and is based on 100 parts by weight of silver.
Containing 7.5 parts by weight of a metal oxide consisting of lead oxide (5% by weight), zinc oxide (55% by weight), silica (10% by weight), boron oxide (25% by weight) and alumina (5% by weight) Met. The silver particles have an average particle size of 4.5 μm.
m, it was scaly.

(5) Next, the ceramic substrate 11 on which the conductive paste is printed is heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to form the ceramic substrate 11
To form a resistance heating element 12 (see FIG. 9B).

As shown in FIG. 6, the pattern of the resistance heating elements is such that 12a to 12d have four channels, 12e to 12g.
Are 1 channel each, that is, 7 channels in total. Note that a channel refers to a circuit that performs the same control by applying the same voltage when performing control. In this embodiment, each channel indicates a resistance heating element formed as a continuous body.

(6) Next, each channel was further divided into 9 sections, and a tester pin was brought into contact with each section to measure the resistance value. Based on the result, trimming was performed using a YAG laser having a wavelength of 1060 nm (manufactured by NEC Corporation, S143AL, output 5 W, pulse frequency 0.1 to 40 kHz) to adjust the resistance value. This apparatus includes an XY stage, a galvanometer mirror, a CCD camera, and an Nd: YAG laser, and has a built-in controller for controlling the stage and the galvanometer mirror. This controller is connected to a computer (FC-9821 manufactured by NEC Corporation). In addition, the computer has a CPU that also serves as an arithmetic unit and a storage unit, and has a hard disk that also serves as a storage unit and an input unit, and a 3.5-inch FD drive. Note that the XY stage can be rotated by an arbitrary angle θ about the center axis A of the fixed ceramic substrate.

The heating element pattern data is input from the FD drive to the computer, and the position of the resistance heating element is read (reading is based on a specific portion of the resistance heating element or a marker formed on the ceramic substrate). ,
The necessary control data is calculated, the heating element pattern is irradiated substantially parallel to the direction in which the current flows, the resistive heating element at that portion is removed, and a groove having a width of 50 μm is formed until reaching the ceramic substrate (FIG. 9). (C)).

The silver-lead resistance heating element 12 has a thickness of 5 μm.
m and a width of 2.4 mm. The laser had a frequency of 1 kHz, an output of 0.4 W, a bite size of 10 μm, and a processing speed of 10 mm / sec. The adjustment of the resistance value by trimming is performed on all the resistance heating elements 12a to 12g.
Made against.

(7) The above electroless nickel plating bath consisting of an aqueous solution having a concentration of 80 g / l nickel sulfate, 24 g / l sodium hypophosphite, 12 g / l sodium acetate, 8 g / l boric acid, and 6 g / l ammonium chloride was used. The ceramic substrate 11 prepared in (6) is immersed in the silver-lead resistance heating element 1.
On the surface of No. 2, a metal coating layer (not shown) having a thickness of 1 μm was deposited.

(8) A silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) was printed by screen printing on a portion where a terminal for securing connection to a power supply was to be formed, to form a solder layer. Next, the external terminal 13 made of Kovar was placed on the solder layer, and heated and reflowed at 420 ° C., and the external terminal 33 was attached to the surface of the resistance heating element 12.

(9) A thermocouple for controlling temperature is formed in the bottomed hole 14.
And a ceramic adhesive (Aron Ceramic manufactured by Toa Gosei Co., Ltd.)
Was obtained (see FIG. 9D).

Example 2 Manufacture of a Ceramic Heater Made of Silicon Carbide (See FIG. 8) Average particle size 1.1 μm (Yakushima Electric Works Co., Ltd.
C-1000) silicon carbide and a sintering temperature of 190
0 ° C., and the surface of the obtained ceramic substrate was 1500 ° C.
For 2 hours to form a SiO ₂ layer having a thickness of 1 μm on the surface, and as a printing pattern, as shown in FIG.
A ceramic heater made of silicon carbide was manufactured in the same manner as in Example 1 except that a repetitive pattern of bent lines and a concentric pattern were formed inside the outermost periphery. Also,
The total number of circuits in the pattern was eight.

Comparative Example 1 Production of Aluminum Nitride Ceramic Heater Example 1 was repeated except that the resistance of the resistance heating element was not adjusted.
A ceramic heater was manufactured in the same manner as described above. The total number of circuits in the pattern was set to eight.

(Comparative Example 2) Manufacture of a ceramic heater made of aluminum nitride Regarding the pattern of the resistance heating element, the total number of circuits is 8 A ceramic heater was manufactured in the same manner as in Example 1 except that the number of concentric patterns was 6, and the total number was 14.

(Comparative Example 3) Manufacturing of a ceramic heater made of aluminum nitride The resistance value of the resistance heating element was not adjusted, and the total number of circuits was divided in the circumferential direction into the outermost circumference for the pattern of the resistance heating element. The repeating pattern of the formed arc is 8,
A ceramic heater was manufactured in the same manner as in Example 1 except that the number of concentric patterns was 6 on the inner side and the total number was 14.

A temperature controller (E5ZE manufactured by OMRON) was attached to the ceramic heaters according to Examples 1 and 2 and Comparative Examples 1 to 3 obtained through the above steps, and evaluated by the following indexes.
The results are shown in Tables 1 and 2.

[0143]Evaluation method  (1) Variation of resistance value Measure the resistance value of the channel on the outer periphery of the resistance heating element, and
The variation within the channel was calculated. Resistance in channel
Variations are obtained by dividing the channel further into 20
The resistance value is measured at both ends within the range, and the average is averaged.
Split resistance, and the highest and lowest resistance in the channel.
The variation is calculated from the difference from the low resistance value and the average divided resistance value.
Calculated. From the obtained variation within each channel, the average
The calculated value is used to calculate the resistance of the ceramic heater.
Table 1 shows the variation of the resistance value. Also, the resistance value
Measurements were taken for all ceramic heaters.
The test was performed after the completion of the manufacture of the quita. The outer channel
Is the resistance in the ceramic heater according to the first embodiment.
The anti-heating elements 12a to 12d and the ceramic according to the second embodiment.
In the heater, the resistance heating elements 62a to 62d
You. In the ceramic heater according to Comparative Example 1,
Measures the resistance value of the four channels arranged on the outer circumference
In the ceramic heaters according to Comparative Examples 2 and 3,
Measures the resistance value of eight channels arranged on the outer circumference
did.

(2) In-Plane Temperature Uniformity The distribution of the in-plane temperature was measured using a silicon wafer with a 17-point temperature measuring element, and is shown in Table 1. In addition,
The temperature distribution is indicated by a temperature difference between the highest temperature and the lowest temperature at a setting of 200 ° C. (3) Transient in-plane temperature uniformity The distribution of the in-plane temperature when the temperature was raised from room temperature to 130 ° C. was measured and described in Table 1. The temperature distribution is indicated by the maximum value of the temperature difference between the highest temperature and the lowest temperature during the temperature rise. (4) Recovery time When a silicon wafer at 25 ° C. was placed at a set temperature of 140 ° C., the time required to recover to 140 ° C. (recovery time) was measured.

[0145]

[Table 1]

As is clear from Table 1, the ceramic heaters according to Examples 1 and 2 and Comparative Example 2 had a resistance variation of 5% or less, whereas the ceramic heaters according to Comparative Examples 1 and 3 The variation of the resistance value was 5% or more. This is probably because the ceramic heaters according to Examples 1 and 2 and Comparative Example 2 adjusted the resistance value of the resistance heating element by trimming.

The variation in the resistance value of the ceramic heater according to the second embodiment was much smaller than that of the ceramic heater according to the first embodiment. this is,
Since the pattern of the resistance heating element of the ceramic heater according to Example 2 was a repetitive pattern of a bent line shape, the variation in the thickness of the resistance heating element could be suppressed, and as a result, the variation in the resistance value was extremely small. It is thought that it was possible.

The ceramic heaters according to Examples 1 and 2 and Comparative Example 2 were superior to the ceramic heaters according to Comparative Examples 1 and 3 in the in-plane temperature uniformity in a steady state. This is because in the ceramic heaters according to Examples 1 and 2 and Comparative Example 2, the resistance value of the resistance heating element is adjusted by trimming, so that the resistance value in the channel varies and the resistance value between the channels increases. It is considered that there is little variation.

The ceramic heaters according to Examples 1 and 2 and Comparative Example 1 were superior to the ceramic heaters according to Comparative Examples 2 and 3 in in-plane temperature uniformity during transition. This is because the ceramic heaters according to Examples 1 and 2 and Comparative Example 1 have a small number of channels of 8 or less and can perform temperature control relatively simply, so that the in-plane temperature during transition is made uniform. On the other hand, the ceramic heaters according to Comparative Examples 2 and 3 have many channels,
Since the temperature control is complicated, it is considered that the in-plane temperature during the transition varies.

Furthermore, the recovery time of the ceramic heaters according to Examples 1 and 2 was shorter than the ceramic heaters according to Comparative Examples 1 to 3. This is the same as in Examples 1 and 2.
The ceramic heater according to Comparative Examples 1 and 2 has a small variation in resistance value and the number of circuit divisions is small, so that the recovery time is short. On the other hand, the ceramic heaters according to Comparative Examples 1 to 3 have large variation in resistance value. It is considered that the recovery time was prolonged due to large variations in resistance value.

The ceramic heaters according to Comparative Examples 2 and 3 were different from the ceramic heaters according to Examples 1 and 2 and Comparative Example 1 in adjusting the resistance value by trimming in the process of manufacturing the ceramic heater, and for controlling the external terminals. It took a lot of time to connect.

[0152]

As described above, according to the ceramic heater of the present invention, the variation of the resistance value of the resistance heating element is 5%.
Since it is smaller than the following, the number of circuit divisions of the resistance heating element can be reduced, and as a result, temperature control can be easily performed. Further, since the variation in the resistance value is small, the controllability is improved, and the temperature of the heating surface of the ceramic heater can be made uniform. Further, since the number of divisions of the circuit of the resistance heating element is set to eight or less, the number of divisions is not excessive, and as a result, temperature control does not become complicated,
It is possible to suppress troubles such as failure of a temperature control device such as a ceramic heater and a temperature controller. Also,
Such a ceramic heater can reduce the complexity of the manufacturing process and reduce the manufacturing cost.

[Brief description of the drawings]

FIGS. 1A to 1C are perspective views schematically showing a resistance heating element in which a groove and a notch are formed by trimming.

FIGS. 2A to 2C are perspective views schematically showing a resistance heating element in which grooves formed by trimming are formed substantially in parallel along a direction in which current flows.

FIG. 3 is a block diagram showing an outline of a laser trimming device used for adjusting a resistance value of a resistance heating element formed on a ceramic substrate.

FIG. 4 is an explanatory diagram showing a state in which a pattern of a spiral resistance heating element is printed.

FIG. 5 is an explanatory view showing a state in which a pattern of a bent resistance heating element is printed.

FIG. 6 is a bottom view schematically showing one example of the ceramic heater of the present invention.

7 is a partially enlarged cross-sectional view schematically showing a part of the ceramic heater shown in FIG.

FIG. 8 is a bottom view schematically showing another example of the pattern of the resistance heating element in the ceramic heater of the present invention.

FIGS. 9A to 9D are cross-sectional views schematically showing a part of the manufacturing process of the ceramic heater.

[Explanation of symbols]

10, 60 Ceramic heater 11, 61 Ceramic substrate 11a Heating surface 11b Bottom surface 12 (12a-12h), 42, 52, 62 (62a-
62h) resistance heating element 120, 121, 122, 123 groove 120a metal coating layer 13 external terminal 130 cutout 14, 64 bottomed hole 140 groove 15, 65 through hole 16 lifter pin 17 thermocouple 23 table 23b fixing projection 25 galvanometer mirror Reference Signs List 26 motor 27 control unit 28 storage unit 29 operation unit 30 input unit 31 camera 32 laser beam 33 resistance heating element 34 tester pin 35 laser irradiation device 39 semiconductor wafer

 ──────────────────────────────────────────────────の Continuing on the front page F term (reference) 3K092 PP20 QA05 QB02 QB04 QB17 QB18 QB32 QB44 QB45 QB47 QB60 QB69 QB76 QB78 QC18 QC43 QC52 QC65 QC66 RF03 RF11 RF17 RF22 UA05 UA17 UA18 VV03 VO18 5V04 5B38F

Claims (1)

[Claims] 1. A ceramic heater in which a resistance heating element composed of two or more circuits is formed on a disc-shaped ceramic substrate, wherein the resistance heating element has a cutout or a groove formed therein. Wherein the variation of the resistance value with respect to the average resistance value is 5% or less, and the total number of circuits of the resistance heating element is 8 or less.