JP2002203666A - Ceramic heater and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a ceramic heater of which, the temperature of a heating surface is uniform, preventing the generation of disconnection caused by the heat generated at a heating resistor, or repeated rise and fall of the temperature. SOLUTION: For the manufacturing method of the ceramic heater, the resistance of a heating resistor is controlled by forming a notch on a heating resistor formed on a ceramic base board by irradiation of laser beam. The direction of the notch is approximately parallel with the current flowing direction, and the notch is formed so that the notch formed part is constructed by only one current flow path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater for drying and sputtering used mainly in the semiconductor industry, a method for manufacturing the same, and a use as a chuck top plate for an electrostatic chuck or a wafer prober. In particular, the present invention relates to a ceramic heater for semiconductor manufacturing and inspection equipment and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, heaters and wafer probers using a metal base material such as stainless steel or an aluminum alloy have been used as semiconductor manufacturing / inspection devices including etching devices and chemical vapor deposition devices. Was.

However, since the heater made of metal has a thick heater plate, there is a problem that the heater is heavy and bulky.
Further, there is a problem in the temperature followability due to these.

Therefore, Japanese Patent Application Laid-Open No. 11-40330 discloses a plate-like body (ceramic substrate) made of a nitride ceramic or a carbide ceramic having a high thermal conductivity and a high strength as a substrate. On the surface of
A ceramic heater provided with a heating element formed by sintering metal particles is disclosed.

As a method of forming a resistance heating element when manufacturing such a ceramic heater, conventionally, a ceramic substrate having a predetermined shape is manufactured, and then the resistance heating element is formed by a coating method using a method such as screen printing. And a method of forming a resistance heating element using a physical vapor deposition method such as sputtering or a plating method.

In the method of forming a resistance heating element by a coating method, a ceramic substrate having a predetermined shape is manufactured, and then a conductor paste layer of a heating element pattern is formed on the surface of the ceramic substrate by a method such as screen printing. , Heating and baking to form a resistance heating element.

However, in this method, although a resistance heating element can be formed at a relatively low cost, there is a problem that the resistance value of the formed resistance heating element varies because the thickness of printing varies. I was

In a method of forming a resistance heating element using a physical vapor deposition method such as sputtering or a plating method, after a ceramic substrate having a predetermined shape is manufactured, a metal layer is formed on a predetermined region of the ceramic substrate by these methods. After that, an etching resist is formed so as to cover a portion of the heating element pattern, and then an etching process is performed to form a resistance heating element having a predetermined pattern. The other parts are covered with a resin or the like, and thereafter, the above-described processing is performed, thereby forming a predetermined pattern of the resistance heating element on the surface of the ceramic substrate by one processing.

[0009] However, in this method such as sputtering or plating, a precise pattern can be formed. However, in order to form a resistive heating element having a predetermined pattern, the surface of the ceramic substrate is etched using a photolithography technique. Since it is necessary to form a resist, a plating resist and the like, there has been a problem that the cost is high.

As a method for solving these problems, there is a method having an advantage that a precise heating element pattern can be formed at a relatively low cost, that is, a strip-shaped or annular conductor layer having a predetermined width. Is formed, a portion other than the heating element pattern is removed (trimmed) using a laser beam irradiation device or the like to form a precise heating element pattern, or after forming a resistance heating element by the above method. A method of precisely adjusting the resistance value by irradiating a laser beam to remove (trim) a part of the resistance heating element has been performed.

In such a trimming method, in order to adjust the width of the groove formed by trimming, a plurality of grooves are formed in parallel with a portion adjacent to the initially formed groove, and the width of the groove is expanded. Was.

FIG. 10 shows a conventional trimming method.
FIG. 4 is a plan view schematically showing a method of forming a groove. When adjusting the resistance value of the resistance heating element 62 by trimming the resistance heating element 62 formed on the ceramic substrate to form a groove,
First, as shown in FIG. 10A, a groove 630a is formed. After that, by repeating the trimming, FIG.
The groove 630b shown in FIG. 10B and the groove 630 shown in FIG.
As shown in c, the width of the groove is expanded.

FIG. 11 is a perspective view schematically showing a resistance heating element in which a groove is formed by the method shown in FIG.
A groove 630 is formed at the center of the surface of the resistance heating element 62 formed on the surface of the ceramic substrate by the method shown in FIG. 10, and current paths 640 are formed on both sides of the groove 630 by forming the groove 630. Is formed.

[0014]

However, in a ceramic heater in which the resistance value of the resistance heating element is adjusted by such a method, the resistance heating element is disconnected at the time of heat generation or by repeating temperature rise and fall. There was something. In addition, the disconnection occurred at a position where a groove was formed by trimming.

The inventors of the present invention have conducted research and found that the disconnection occurs at a portion where a groove is formed by trimming because the formation of the groove partially increases the current path of the resistance heating element to two or more. Because there is a branch point,
It has been found that the individual current paths become narrower in that portion, and as a result, disconnection is likely to occur due to melting at the time of heat generation, heat cycles, and the like. Further, by branching, the circuit becomes a parallel circuit, and even if the variation of the resistance value is small on average, the variation of the resistance value occurs locally, and as a result, the heat generation amount differs and a new temperature distribution occurs. It becomes a factor.

[0016]

The inventors of the present invention have further studied and found that when adjusting the resistance value of the resistance heating element, a notch was formed in the resistance heating element, and the portion where the notch was formed was formed. Is constituted by only one current path, not only disconnection at the time of trimming of the resistance heating element, but also at the time of heat generation,
The inventors have found that disconnection due to repeated heating and cooling can be prevented, and have completed the present invention.

That is, in the method of manufacturing a ceramic heater according to the present invention, after forming a resistive heating element of a predetermined pattern on the surface of a ceramic substrate, a cutout is formed by irradiating the resistive heating element with a laser beam. A method for manufacturing a ceramic heater for adjusting a resistance value of a body, wherein a main wall surface formed by a notch is substantially parallel to a direction in which a current flows, and a notch forming portion is formed by only one current path. In other words, the notch is formed so as not to form a parallel circuit.

Further, in the ceramic heater of the present invention, a resistance heating element comprising a plurality of circuits is formed on the surface of the ceramic substrate, and a cutout is formed in a part of the resistance heating element to adjust the resistance value. A main wall formed by the notch is formed so as to be substantially parallel to a method of flowing an electric current, and the notch forming portion is provided with one current passage so as not to form a parallel circuit. Is formed.

According to the method for manufacturing a ceramic heater of the present invention, the width of the resistance heating element is changed by forming a notch in the resistance heating element and the resistance value is precisely adjusted, so that the variation in the amount of heat generation is reduced. The temperature of the heating surface of the ceramic heater can be made uniform. In addition, a portion where the notch is formed (hereinafter, also referred to as a notch forming portion).
However, since it is constituted by only one current path, a groove is formed in the resistance heating element, and compared with the case where two or more current paths are provided,
The width of the current path can be widened, and disconnection due to heat generation and disconnection due to repetition of heating and cooling can be suppressed. Further, even if the notch is formed, a parallel circuit is not formed, local variation in resistance value is eliminated, and uniformity of temperature on the heating surface can be ensured. According to the ceramic heater of the present invention, as in the case of the ceramic heater obtained by the method for manufacturing a ceramic heater,
The temperature of the heating surface of the ceramic heater can be made uniform, and occurrence of disconnection due to repetition of temperature rise and temperature fall can be suppressed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method of manufacturing a ceramic heater according to the present invention, a notch is formed by irradiating a laser beam to a resistance heating element after forming a predetermined pattern of resistance heating element on the surface of a ceramic substrate. A method of manufacturing a ceramic heater for adjusting a resistance value of a resistance heating element, wherein a main wall surface formed by a notch is substantially in a direction in which a current flows, and a notch forming portion is formed by only one current path. Thus, the notch is formed.

Further, in the ceramic heater of the present invention, a resistance heating element comprising a plurality of circuits is formed on the surface of the ceramic substrate, and a cutout is formed in a part of the resistance heating element to adjust the resistance value. A main wall formed by the notch is formed so as to be substantially parallel to a current flowing method, and the notch forming portion has only one current path. It is characterized by the following.

First, in the method of manufacturing a ceramic heater according to the present invention, a trimming apparatus used for performing laser trimming will be described, and then laser trimming using this apparatus will be described.

FIG. 1 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. Table 10c
As shown in FIG. 1, a disc-shaped ceramic substrate 11 on which a resistance heating element 12 having a desired pattern is formed,
Are fixed using the fixing projections 10b and the like.

The table 10c is provided with a motor and the like (not shown), and the motor and the like are connected to the control unit 17, and the motor and the like are driven by a signal from the control unit 17. Thus, the table 10c can be freely moved in the θ direction (the rotation direction of the ceramic substrate) and the xy directions.

On the other hand, a galvanometer mirror 15 is provided above the table 10c, and the angle of the galvanometer mirror 15 can be freely changed by the motor 16 around the x direction. And a laser irradiation device 25 also arranged above the table 10c.
The laser beam 22 emitted from the galvanomirror 1
5 and is configured to reflect and irradiate the ceramic substrate 11. Note that the galvanomirror provided in the laser trimming device used in the method of manufacturing a ceramic heater according to the present invention need only 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 16 and the laser irradiation device 2
Reference numeral 5 is connected to the control unit 17, and drives the motor 16 and the laser irradiation device 25 by a signal from the control unit 17, thereby rotating the galvanometer mirror 15 by a predetermined angle around the x direction. In addition, by driving a motor (not shown) provided on the table 10c by a signal from the control unit 17, the table 10c is rotated in the θ direction. The irradiation position on the ceramic substrate 11 can be freely set by the rotation of the galvanometer mirror 15 about the x direction and the rotation of the table 10c in the θ direction. The table 10c can move not only in the θ direction but also in the xy directions.

As described above, by moving the table 10c on which the ceramic substrate 11 is mounted and / or the galvanomirror 15, it is possible to irradiate an arbitrary position on the ceramic substrate 11 with the laser beam 22.

On the other hand, above the table 10c, a camera 21 is also installed, whereby the ceramic substrate 1
1, the position (r, θ or xy) of the resistance heating element 12 can be recognized. This camera 2
1 is connected to the storage unit 18 so that the position (r, θ or x−) of the resistance heating element 12 on the ceramic substrate 11 is
y) is recognized, and the position is irradiated with the laser beam 22.

The input unit 20 is connected to the storage unit 18 and has a keyboard or the like (not shown) as a terminal. A predetermined instruction or the like is input via the storage unit 18 or the keyboard. It is supposed to be.

Further, this laser trimming device is provided with a calculation unit 19, based on data such as the position and thickness of the ceramic substrate 11 recognized by the camera 21.
Calculation for controlling the irradiation position, irradiation speed, laser light intensity, etc. of the laser light 22 is performed, and based on the calculation result, the control unit 17 issues an instruction to the motor 16, the laser irradiation device 25, and the like, and the galvanomirror 15 Is rotated or the table 10c is moved or rotated to irradiate the laser beam 22 to trim the resistance heating element 12,
Form a notch.

The laser trimming device has a resistance measuring unit 23. The resistance measurement unit 23 includes a plurality of tester pins 24, 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 of manufacturing a ceramic heater using such a laser trimming device will be specifically described. Here, the step of forming a notch by laser trimming in order to adjust the resistance value of the resistance heating element, which is a main part of the present invention, will be described in detail, and other steps will be described in detail later. A brief description will be given.

(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. Therefore, a method of adjusting the resistance value by trimming is effective. When forming this resistance heating element, the surface roughness Ra of the resistance heating element is 0.01 μm.
m or more. This is because the reflection of the laser beam on the surface of the resistance heating element can be prevented, and the notch having the width, depth, and the like as set can be formed.

(3) Next, using the fixing projection 10b and the fitting projection (not shown) provided on the table 10c,
The ceramic substrate 11 on which the resistance heating element 12 is formed is fixed on the table 10c.

(4) Next, the fixed ceramic substrate 1
1 is photographed by the camera 21 so that the resistance heating element 12
Are stored in the storage unit 18.

(5) Next, the resistance value of each portion of the formed resistance heating element 12 is measured by the resistance measuring section 23 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 24. The data of the resistance value of the resistance heating element measured in this way is stored in the storage unit 18.

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 the data of the irradiation conditions such as
Is used to calculate the length, depth, and width of the notch, and the result is stored in the storage unit 18 as control data.
Is stored.

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.
_The distance for irradiating the laser to form the notch can be set by the rotation distance (θ ₁ −θ ₂ ). 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, the control unit 17 generates a control signal based on the trimming data, and irradiates the laser beam 22 while driving the motor 16 of the galvanomirror 15 and / or the motor of the table 10c, thereby performing trimming. Perform processing.

FIGS. 2A to 2C are plan views schematically showing a method of forming a notch by trimming in the method of manufacturing a ceramic heater according to the present invention. Resistance heating element 1
When trimming 2, first, as shown in FIG. 2A, a notch 130 a is formed in the resistance heating element 12. At this time, the main wall surface 150a of the notch 130a is substantially parallel to the direction in which current flows.

The notch is a kind of notch formed so as to include the side surface of the resistance heating element in order to locally reduce the width of the resistance heating element.
The narrow portion of the resistance heating element is formed with a substantially constant width and has a certain length. The notch may be formed so that the thickness of the resistance heating element is partially reduced, or may be formed such that the bottom of the notch reaches the surface of the ceramic substrate. Further, in the present invention, the main wall surface is a wall surface of a portion where a notch is formed, and refers to a surface that can be observed from a side surface direction. For example, in FIG. I will call it the wall. Furthermore, in the present invention, being substantially parallel means that the direction in which the current flows and the main wall surface of the notch are not only mathematically parallel, but also that the direction in which the current flows and the main wall surface of the notch. The included angle includes an acute angle.

In the present invention, next, the notch 13 is provided on the side of the main wall surface 150a of the notch 130a (the left side in FIG. 3B).
The notch 130b close to 0a is formed, and the width of the notch 130a is increased. At this time, the main wall surface 150b of the expanded notch 130a is made substantially parallel to the direction in which the current flows. Further, the main wall surface 150 of the expanded notch 130a
On the b side (the left side in FIG. 3C), a notch 130c close to the notch 130b is formed, and the width of the notch 130a is further increased. At this time, the main wall surface 150c of the expanded notch 130a is set to be substantially parallel to the direction in which current flows.

Thereafter, a notch (not shown) close to the notch 130 is sequentially formed on the main wall surface 150 of the notch 130 as needed, and the notch 130 is expanded. The number of cutouts (including the first cutout) may be one or three, and is not particularly limited. The process can be repeated until the resistance value of the resistance heating element can be adjusted.

That is, the method of forming the above notch is as follows:
This is a method in which notches close to the formed notches are sequentially formed, and the width is increased. By forming the notch by such a method, even if the irradiation position of the laser beam or the position of the resistive heating element pattern is misaligned, it is difficult for the notch position to be largely misaligned, and the notch having the intended shape is formed. Can be formed. As a result, even when the resistance value of the resistance heating element is adjusted, disconnection or the like hardly occurs.

FIG. 3 is a perspective view schematically showing a resistance heating element in which a notch is formed by the method shown in FIG. FIG. 2 shows the resistance heating element 12 formed on the surface of the ceramic substrate.
The notch 130 is formed by the method shown in (1), and the main wall surface 150 of the notch 130 is substantially parallel to the direction in which current flows. It should be noted that there is only one current path 140 in the notch 130 forming portion. In the present invention, since the current path is formed by only one current in the notch forming portion of the resistance heating element, the groove is formed in the resistance heating element and the current path is thicker than when two current paths are formed. Wide)
As a result, a current path can be secured, and as a result, disconnection due to heat generation of the resistance heating element and disconnection due to repeated heating and cooling can be suppressed.

Further, in the present invention, as described above, notches are formed from one side of the resistance heating element, and the notches are formed from both sides of the resistance heating element.
It is also possible to take a method of sequentially forming notches close to the formed notches and increasing the width of the notches.

FIGS. 4A to 4C are plan views schematically showing another example of a method of forming a notch by trimming in the method of manufacturing a ceramic heater according to the present invention. When trimming the resistance heating element 12, first, FIG.
As shown in (a), a notch 131a is formed in the resistance heating element 12. At this time, the main wall surface 151a of the notch 131a is made substantially parallel to the direction in which the current flows.

Next, a notch 131b is formed on the side where the notch 131a is not formed (the left side of the resistance heating element in FIG. 4B) in the notch 131a forming portion. At this time, the main wall surface 151b of the notch 131b is substantially parallel to the direction in which the current flows. Further, the notch 1 is formed on the side of the main wall surface 151a of the notch 131a (the right side in FIG. 4C).
A notch 131c adjacent to 31a is formed. At this time,
The main wall surface 151c of the expanded 131a is substantially parallel to the direction in which the current flows.

Thereafter, a notch (not shown) close to the notch 131 is sequentially formed on the main wall surface 151 side of the notch 131 as necessary, and the width of the notch is increased. At this time, notch 13
Although 1 is present on both sides of the resistance heating element 12, a notch close to the notch can be formed for either of the notches. The number of cutouts is not particularly limited, and the cutout can be repeated until the resistance of the resistance heating element can be adjusted.

FIG. 5 is a perspective view schematically showing a resistance heating element in which a notch is formed by the method shown in FIG. Resistance heating element 12 formed on ceramic substrate surface
The notch 131 is formed by the method shown in FIG. 4, and the main wall surface 151 of the notch 131 is substantially parallel to the direction in which current flows. In the notch 131 forming portion, there is only one current path 141. Even when the trimming is performed by the method shown in FIG. 4, similar to the method shown in FIG. 2, the notch forming portion of the resistance heating element has only one current path, so that it is thick (wide).
As a result, a current path can be secured, and as a result, disconnection due to heat generation of the resistance heating element and disconnection due to repeated heating and cooling can be suppressed.

In the method of manufacturing a ceramic heater according to the present invention, any of the above-described methods may be used to form the notch in the resistance heating element. 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-described adjustment of the resistance value may be performed by a trimming operation or the like by moving the table in the xy directions using xy as the coordinates.

In the present invention, the notch formed by the trimming preferably has a depth of 20% or more of the thickness of the resistance heating element, and more preferably has a depth of 50% or more. 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 resistance heating element pattern width is desirably 0.6 mm or more. If the thickness is less than 0.6 mm, it is difficult to perform trimming substantially parallel to the direction in which the current of the resistance heating element flows, and to form a notch.

The width of the notch can be up to 20% of the width of the resistance heating element pattern, that is, 20% of the width of the resistance heating element pattern.
% Is desirable. If the width of the notch exceeds 20% of the width of the resistance heating element pattern, disconnection or the like is likely to occur. When performing trimming by laser light, the laser spot diameter is adjusted to 1 μm to 2 cm.

In the notch forming portion of the resistance heating element,
The thickness (width) of the current path is desirably 0.5 mm or more. By securing a thick (wide) current path, it is possible to suppress the occurrence of disconnection at the time of heat generation of the resistance heating element and the occurrence of disconnection due to repeated rise and fall of temperature. On the other hand, if it is less than 0.5 mm, the current path becomes narrow (narrow), and as a result, disconnection due to heat generation or disconnection due to repetition of temperature increase and decrease occurs in the resistance heating element. There is a risk.

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

The trimming is desirably performed 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.

The resistive 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.

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 resistance heating element, 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 the YAG laser, an SAG manufactured by NEC Corporation can be 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 it exceeds 100 mm / sec, notches 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 notch is formed so as to reach the ceramic substrate, the output of the laser is desirably 0.3 W or more.

Further, the ceramic heater of the present invention can adjust the resistance value of the resistance heating element by using a polishing process such as a sand blast or a belt sander in addition to the laser trimming described above. However, since the resistance heating element is usually formed of a metal or a conductive paste made of a metal and an oxide, it is desirable that the cutout having the above-described shape is formed by laser trimming. 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.

The ceramic heater manufactured by the method for manufacturing a ceramic heater of the present invention and the ceramic heater of the present invention have the same configuration. Therefore, in the following, a ceramic heater manufactured by the method for manufacturing a ceramic heater of the present invention and a ceramic heater of the present invention will be described. The invention will be described in parallel, and in particular, when there is no need to distinguish between the two inventions, it is simply referred to as the ceramic heater according to the invention.

The pattern of the resistance heating element of the ceramic heater according to the present invention is not particularly limited, and examples thereof include the following resistance heating element patterns.

FIG. 6 is a bottom view schematically showing a ceramic heater according to the present invention, and FIG. 7 is a partially enlarged sectional view thereof. The resistance heating elements 12a to 12 shown in FIG.
g does not show a groove formed by trimming.

The ceramic heater 10 has a resistance heating element 12 (12a to 12g) on a bottom surface 11b opposite to a heating surface 11a of a ceramic substrate 11 formed in a disk shape.
Are formed.

Since the resistance heating element 12 is heated so that the entire temperature of the heating surface 11a becomes uniform, a pattern formed on the basis of arcs and concentric circles repeatedly formed so as to draw a part of concentric circles is used. Is formed.

That is, the resistance heating element 12 closest to the outer periphery
In a to 12d, an arc-shaped pattern obtained by dividing a concentric circle into four parts is repeatedly formed, and ends of adjacent arcs are connected by bending lines to form a series of circuits. Then, the 4 comprising the resistance heating elements 12a to 12d having such a pattern.
Two circuits are formed close to each other around the outer circumference,
An overall annular pattern is formed.

The ends of the circuit composed 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.
Therefore, the end of the outer circuit is extended toward the inner side.

Resistance heating elements 12a-12 formed on the outer periphery
On the inner side of d, resistance heating elements 12e, 12f, and 12g, each of which is formed of a circuit of a concentric pattern with a very small part thereof cut off, are formed, and these resistance heating elements 12e, 12f, and 12g are formed.
In g, a series of circuits is configured 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 12a
Between d, 12e, 12f and 12g, belt-like (annular)
Heating element non-forming area is provided, and also in the center part,
A circular heating element non-formation area is provided.

Therefore, when viewed as a whole, annular resistance heating element forming areas and heating element non-forming areas 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.

After the resistance heating elements 12a to 12g are trimmed, as shown in FIG. 7, a metal coating layer 120a is formed to prevent corrosion and the like. The external terminal 33 is connected via a solder layer.

The ceramic substrate 11 is provided with three through-holes 35 at positions where no heating element is to be formed.
In addition to placing the semiconductor wafer 39 in contact with the heating surface 11a and heating it, as shown in FIG. 7, lifter pins 36 are inserted into these through holes 35, and the semiconductor wafer 39 and the like are heated by the lifter pins 36. By holding the object, the object to be heated can be heated in a state where the object is separated from the ceramic substrate 11 by a certain distance.

By moving the lifter pins 36 up and down, an object to be heated such as a silicon wafer 39 is received from the transfer device, the object to be heated is placed on the ceramic substrate 11, and the object to be heated is supported. It can be heated as it is.

A recess is formed on the heating surface 11a of the ceramic substrate 11, supporting pins are provided in the recess and the like so as to slightly protrude from the heating surface 11a, and the semiconductor wafer 39 is supported by the supporting pins. The semiconductor wafer 39 may be supported while being separated from the heating surface by 5 to 5000 μm, and heating may be performed.

The bottom surface 11b of the ceramic substrate 11 is provided with a bottomed hole 34 in a region where no heating element is formed. In this bottomed hole 34, a temperature measuring element 37 such as a thermocouple is inserted. The temperature of a portion near the heating surface 11a can be measured.

In the ceramic heater having the above-described resistance heating element pattern, a pattern in which a series of circuits are formed by a combination of arcs and bent lines repeatedly formed so as to draw a part of a concentric circle on a disk-shaped ceramic substrate. (Hereinafter, also referred to as a circular arc repetition pattern), and a partially cut concentric circle is linearly connected at adjacent ends to form a series of circuits (hereinafter, also referred to as a concentric pattern), and has a resistance. Since the heating element is configured, most of such a resistance heating element pattern can be represented by the distance r from the center of the ceramic substrate and the rotation angle (θ ₁ −θ ₂ ).

Therefore, when performing laser trimming,
If the ceramic heater is rotated around the center, the resistance value of the resistance heating element can be adjusted relatively easily. In a ceramic heater having a resistance heating element whose resistance value is adjusted by such a method, the heating surface can be adjusted. The temperature becomes uniform, and an object to be heated such as a semiconductor wafer can be heated at a uniform temperature.

The ceramic heater according to the present invention is not limited to the resistance heating element having the pattern shown in FIG. 6. For example, the above-described arc repetition pattern, concentric pattern, repetition pattern of bent lines, etc. may be used alone. May be formed, and these patterns may be arbitrarily combined.

FIG. 8 is a plan view schematically showing another embodiment of the ceramic heater according to the present invention. In this ceramic heater, as shown in FIG. 8, each of the resistance heating elements 6 mainly formed of a bent line and formed in a wide annular shape.
2a to 62d, 62e and 62f are formed radially as a whole with the ring-shaped heating element non-formation area and the heating element non-formation area in the center part interposed therebetween. The other parts are configured in the same manner as in the case of the ceramic heater 10 shown in FIG. 6, and the bottomed holes 64, the through holes 65, and the like are similarly formed.

It is desirable that the resistance heating element formed on the surface of the ceramic substrate be divided into at least two or more circuits as shown in FIGS. This is because, by dividing the circuit, the amount of heat generated can be changed by controlling the power supplied to each circuit, and the temperature of the heating surface of the silicon wafer can be adjusted.

When such a resistive heating element pattern is formed, if the pattern between the wirings of the resistive heating element is wide as shown in FIG. 8, the resistive heating element can be easily formed by screen printing. However, in the case of forming a complicated (crowded) pattern with a narrow interval as shown in FIG. 6, an annular conductor layer composed of a wide band of lines is formed, and laser light is used. By a method of trimming a portion (unnecessary portion) that is not the resistance heating element, the resistance heating element can be formed relatively easily.

When the resistance heating element is formed on the surface of the ceramic substrate, the thickness of the resistance heating element is preferably 1 to 30 μm, more preferably 1 to 10 μm. Further, the width of the resistance heating element is preferably 0.1 to 20 mm, and 0.1 to 5 mm.
Is more preferred. 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 will be high, and eventually, a heat distribution similar to the pattern of the resistance heating element will occur 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.

Regarding the variation of the resistance value of the resistance heating element, the variation of the resistance value with respect to the average resistance value is preferably 5% or less, more preferably 1%. The resistance heating element of the ceramic heater according to the present invention is divided into a plurality of circuits. By reducing the variation in the resistance value in this way, the number of divisions of the resistance heating element can be reduced and the temperature can be easily controlled. be able to. Further, it is possible to make the temperature of the heating surface uniform during the transition of the temperature rise.

Normally, such a resistance heating element is formed by applying a conductive paste containing metal particles or conductive ceramic particles for securing conductivity on a ceramic substrate and firing it. The conductive paste is not particularly limited, but preferably contains not only the metal particles or the conductive ceramic but also a resin, a solvent, a thickener, and the like.

As the metal particles, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like are preferable. 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 particle size of these metal particles or conductive ceramic particles is preferably 1 to 100 μm. If it is too fine, less than 1 μm, the surface roughness Ra of the resistance heating element is 0.01
μm, it is easy to reflect the laser light at the time of trimming by irradiation with the laser light, it is not possible to form the cutout as set, on the other hand, if the particle size of the metal particles etc. exceeds 100 μm, This is because sintering becomes difficult and the resistance value increases.

Although the shape of the metal particles is spherical,
It may be scaly, but more preferably spherical. This is because the surface roughness of the resistance heating element tends to be rougher. Further, even if it has a scale shape, if its aspect ratio (width or length / thickness) is not so large, it tends to be perpendicular or oblique to the surface on which the resistance heating element is formed. The roughness can be increased.

When these metal particles are used, they may be a mixture of the above-mentioned spherical material and the above-mentioned scaly material. When the metal particles are scaly, or a mixture of spherical and scaly, it is easy to hold the metal oxide between the metal particles, and the adhesion between the resistance heating element and the nitride ceramic, etc. And it is advantageous because the resistance value can be increased. Furthermore, if the needle-like particles have a small aspect ratio (length with respect to the diameter), the surface tends to be perpendicular or oblique to the surface on which the resistance heating element is formed, so that the surface roughness is increased. be able to.

The resin used for the conductor paste is as follows.
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.

As the conductor paste, one obtained by adding a metal oxide to metal particles is used, and it is desirable to apply the metal paste to a ceramic substrate and then sinter the metal particles and the metal oxide. . By sintering the metal oxide together with the metal particles in this manner, the ceramic substrate, such as a nitride ceramic, and the metal particles can be more closely adhered to each other.

It is not clear why the mixing with the metal oxide improves the adhesion to the nitride ceramic or the like. However, the surface of the metal particles or the surface of the nitride ceramic 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,
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
Without increasing the resistance value of the heating element 12,
Adhesion with nitride ceramics etc. can be improved
Because.

The ratio of the above-mentioned lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is 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 addition amount of the metal oxide 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 12 is formed using the conductor paste having such a configuration is 1 to 45 mΩ / □.
Is preferred.

If the area resistivity exceeds 45 mΩ / □, the amount of heat generated becomes too large with respect to the applied voltage, and the amount of heat generated in the ceramic substrate 11 provided with the resistance heating element 12 on the surface of the ceramic substrate is controlled. Because it is hard to do. If the addition amount of the metal oxide is 10% by weight or more, the sheet resistivity exceeds 50 mΩ / □, the calorific value becomes too large, the temperature control becomes difficult, and the uniformity of the temperature distribution decreases. . Further, if necessary, the sheet resistivity is set to 50 mΩ.
/ □ to 10Ω / □. When the sheet resistivity is increased, the width of the pattern can be increased, so that there is no problem of disconnection.

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. Such a metal coating layer is formed after performing the above-described trimming processing.

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, nickel and the like. . These may be used alone or in combination of two or more. Of these, nickel is preferred.

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

The ceramic substrate in the ceramic heater according to the present invention is desirably a disc, and desirably has a diameter exceeding 200 mm. This is because such a large-diameter substrate can mount a large-diameter semiconductor wafer. The diameter of the ceramic substrate is preferably 1
It is desirable that it be 2 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

The thickness of the ceramic substrate of the ceramic heater according to the present invention is desirably 25 mm or less. This is because if the thickness of the ceramic substrate exceeds 25 mm, the temperature followability decreases. Also, its thickness is
More preferably, it is more than 1.5 mm and 5 mm or less. If the thickness is more than 5 mm, the heat is difficult to propagate, and the heating efficiency tends to decrease. May occur, and the strength of the ceramic substrate may be reduced to cause breakage.

In the ceramic heater 10 according to the present invention,
Although ceramic is used as a material of the substrate, the ceramic is not particularly limited, and examples thereof include a nitride ceramic, a carbide ceramic, and an oxide ceramic. Among these, a nitride ceramic or a carbide ceramic is preferable as the material of the ceramic substrate 11. This is because it has excellent heat conduction characteristics.

As the nitride ceramic, for example,
Examples include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Examples of the carbide ceramic include silicon carbide, titanium carbide, and boron carbide.
Further, examples of the oxide ceramic include alumina, cordierite, mullite, silica, beryllia and the like. These may be used alone or in combination of two or more. Of these, aluminum nitride is most preferred. This is because the thermal conductivity is the highest at 180 W / m · K.

However, the ceramic substrate 11 is preferably made of a material that does not easily absorb laser light. For example, in the case of an aluminum nitride substrate, the carbon content is 5000p.
Those having a small carbon content of pm or less are preferred. Also,
Polish the surface to determine the surface roughness of the surface according to JIS B 0601
It is desirable that Ra be 20 μm or less. This is because when the surface roughness is large, the laser light is absorbed. If necessary, a heat-resistant ceramic layer may be provided between the resistance heating element and the ceramic substrate. For example, in the case of a non-oxide ceramic, an oxide ceramic may be formed on the surface.

As a method of forming a resistance heating element on the surface of a ceramic substrate by using the above method, a conductor paste is applied in a planar shape (annular shape) to a predetermined area of the ceramic substrate, and then the heating element pattern is formed by laser trimming. Or a method of baking a conductive paste and then performing laser trimming to form a resistive heating element having a predetermined pattern. Of these methods, after baking the conductor paste, a method of forming a resistance heating element pattern,
This is preferable because peeling of the conductive paste layer due to laser light irradiation does not occur.

The sintering of the metal is sufficient if the metal particles and the metal particle and the ceramic are fused.
Alternatively, a conductor layer may be formed in a predetermined region by using a method such as plating or sputtering, and a resistance heating element pattern may be formed by laser trimming.

Next, a method of manufacturing a ceramic heater according to the present invention other than the laser trimming step described above will be described with reference to FIG.
It will be described based on. FIGS. 9A to 9D are cross-sectional views schematically showing a part of the method for manufacturing a ceramic heater of the present invention including laser processing.

(1) Manufacturing process of ceramic substrate Powder of ceramic such as aluminum nitride is added as necessary.
And yttria (Y_Two O _Three ), Na, Ca
Is prepared by blending a compound containing
After that, this slurry is granulated by a method such as spray drying.
And put the granules in a mold and press
It is formed into a plate or the like to produce a green body (green).
Note that the green sheet formed by the doctor blade method, etc.
The formed form may be produced by laminating the sheets.

Next, as necessary, a portion serving as a through-hole 35 for inserting a lifter pin 36 for carrying an object to be heated such as a silicon wafer 39 or a temperature measuring element such as a thermocouple is provided in the formed body. A portion serving as a bottomed hole 34 for embedding is formed.

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 (see FIG. 9A), but may be formed into a shape that can be used as it is after firing. Further, for example, by performing heating and baking while applying pressure from above and below, it becomes possible to manufacture a ceramic substrate 11 having no pores.
Heating and firing may be at least the sintering temperature, for example,
For nitride ceramics, the temperature is 1000-2500C.

Normally, after firing, a through hole 35 and a bottomed hole (not shown) for inserting a temperature measuring element are provided. The through holes 35 and the like can be formed by performing blasting such as sand blasting using SiC particles or the like after surface polishing.

(2) Step of Printing Conductive Paste on Ceramic Substrate The conductive paste is generally a high-viscosity fluid composed of metal particles, resin and solvent. The viscosity of the conductor paste is preferably from 70 to 90 Pa · s from the viewpoint that a conductor layer having a relatively uniform thickness can be formed.

By using the conductor paste by screen printing or the like, a conductor paste layer serving as a resistance heater pattern is formed so that there are a plurality of circuits of the resistance heater. The temperature of the heating and firing is preferably from 500 to 1000C. When the above-described 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. .

Since the temperature of the resistance heating element needs to be uniform over the entire ceramic substrate, an arc or a concentric circle repeatedly formed so as to draw a part of a concentric circle as shown in FIG. 6 is used. A basic pattern is desirable. Note that, in addition to the method described above, the conductor layer can be formed by plating.

(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, sinter the metal particles, and baked on the bottom surface of the ceramic substrate 11.
The resistance heating element 12 is formed (see FIG. 9B). The temperature of the heating and firing is preferably from 500 to 1000C.

(4) Adjustment of Resistance Value of Resistance Heating Element After that, unnecessary portions are removed by using the above-described trimming method of the present invention to form notches 130 (see FIG. 9C). ).

(5) Formation of Metal Coating Layer It is desirable to provide a metal coating layer 120 on the surface of the resistance heating element 12 as shown in FIG. Metal coating layer 120
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 33) for connection to a power supply are attached to the ends of the pattern of the resistance heating element 12 via solder (see FIG. 9D). Further, a thermocouple (not shown) is inserted into the bottomed hole 34 and sealed with a heat-resistant resin such as polyimide or the like, and the production of the ceramic heater is completed.

The ceramic heater of the present invention can be used as an electrostatic chuck by providing an electrostatic electrode inside the ceramic substrate, and a chaptop conductor layer is provided on the surface, and a guard electrode or the like is provided inside. By providing a ground electrode, it can be used as a wafer prober.

[0128]

The present invention will be described in more detail with reference to the following examples. Example 1 Adjustment of Resistance Value of Resistance Heating Element by Laser Trimming (See FIGS. 2, 3, 6, and 7) (1) Aluminum Nitride Powder (Average Particle Size: 0.6 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 granular powder was put into a mold and molded into a flat plate to obtain a green body (green).

(3) Next, the green compact was hot-pressed at 1800 ° C. and a pressure of 20 MPa to obtain an aluminum nitride plate having a thickness of about 3 mm. Next, a disk having a diameter of 210 mm was cut out from the plate to obtain a ceramic plate (ceramic substrate 11). The ceramic substrate was drilled to form a through hole 35 for inserting a lifter pin 36 of a silicon wafer and a bottomed hole 34 (diameter: 1.1 mm, depth: 2 mm) for embedding a thermocouple.

(4) The ceramic substrate 11 obtained in the above (3)
Then, a conductor paste layer was formed by screen printing. The printing pattern was a pattern as shown in FIG.
Ag: 48% by weight, Pt:
21 wt%, SiO _2: 1.0 _{wt%, B 2 O 3: 1} .
2% by weight, ZnO: 4.1% by weight, PbO: 3.4% by weight, ethyl acetate: 3.4% by weight, butyl carbitol:
A composition having a composition of 17.9% by weight was used. This conductor paste is an Ag-Pt paste, and the silver particles (Ag-540 manufactured by Shoei Chemical Co., Ltd.) have an average particle size of 4.5 μm.
Was scaly. The Pt particles (Pd-221 manufactured by Shoei Chemical Co., Ltd.) were spherical with an average particle size of 6.8 μm. At this time, the viscosity of the conductor paste is 80P.
a · s.

(5) Further, after the conductor paste layer of the heating element pattern is formed, the ceramic substrate 11 is heated at 850 ° C. for 1 hour.
Ag in the conductor paste by heating and baking for 0 to 20 minutes,
Pt was sintered and baked on the ceramic substrate 11.

As shown in FIG. 6, the pattern of the resistance heating elements is seven channels 12a to 12g. Perimeter 4
The variation of the resistance value in one of the channels (the resistance heating elements 12a to 12d) before trimming is 7.4 to
12.4%. Note that a channel refers to a circuit that performs one control by applying the same voltage when performing control. In the present embodiment, each resistance heating element (12a to 12g) formed as a continuous body is shown. .

Each of the channels (the resistance heating elements 12a to 12a)
The resistance variation in 12d) was obtained as follows. That is, first, the channel is divided into 20, the resistance is measured at both ends within the divided range, the average is taken as the average divided resistance value, and the difference between the highest resistance value and the lowest resistance value in the channel and the average divided value Variation was calculated from the resistance value. In addition, each channel (the resistance heating elements 12a to 12
The resistance value in d) is the sum of all resistance values measured separately.

(6) Next, as a trimming device, a YAG laser having a wavelength of 1060 nm (S14 manufactured by NEC Corporation)
3AL output 5W, pulse frequency setting range 0.1-4
0 kHz) and the pulse frequency was set to 1.0 kHz. This device consists of an XY stage, a galvanometer mirror,
It has a CCD camera, an Nd: YAG laser, and a built-in controller that controls the stage and galvanometer mirror. The controller is a computer (NEC FC
-9821). The computer has a CPU that doubles as an arithmetic unit and a storage unit. In addition, it has a hard disk serving as a storage unit and an input unit, and a 3.5-inch FD drive.

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). Calculate necessary control data, irradiate the heating element pattern almost in parallel along the direction of current flow, reduce the thickness of the resistance heating element at that portion, and form a notch as shown in FIG. Thereby, the resistance value was adjusted.

When the notch is formed, as shown in FIG.
Notch formed first (width: 75 μm, depth: 1 to 50 μm)
In m), notches of the same shape were sequentially formed close to each other, and the width of the notches was adjusted. The number of notches formed to expand the width of the notches was 0 to 50 in total. In the ceramic heater 10, the thickness (width) of the current path in the notch forming portion was 0.5 to 5 mm.

The resistance heating element had a thickness of 5 μm and a width of 2.4 mm. The laser has a frequency of 1 kHz,
The output was 0.4 W, the bite size was 10 μm, and the processing speed was 10 mm / sec.

After the trimming is performed and the resistance value of the resistance heating element is adjusted, the variation in resistance value of the four outer peripheral channels (resistance heating elements 12a to 12d) is 1.0%.
５5.0%.

(8) Next, a portion to which the external terminal 33 for securing the connection to the power supply is to be plated with Ni, and then silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) is printed by screen printing, and A layer was formed. Next, the external terminal 33 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 temperature control was sealed with polyimide to obtain a ceramic heater 10.

Example 2 Adjustment of Resistance Value of Resistance Heating Element by Laser Trimming (See FIGS. 4 and 5) When notches are formed in the resistance heating element, as shown in FIG. Example 1 except that notches were formed
In the same manner as in the above, a ceramic heater was manufactured. When forming the notch, first, as shown in FIG. 4, a notch (width: 75 μm, depth: 15 to 15) is provided on both sides of the resistance heating element.
30 μm) and successively formed notches of the same shape close to either one of the notches to adjust the width of the notches. The number of cutouts formed to expand the width of the cutouts is 1 to 1 in total.
There were 24. In this ceramic heater, the thickness (width) of the current path in the notch forming portion is 0.9 to 0.9.
It was 2.9 mm. Further, after the trimming was performed and the resistance value of the resistance heating element was adjusted, the variation of the resistance value of the four outer peripheral channels was 1.7 to 3.1%, and the variation was very small.

(Embodiment 3) Adjustment of resistance value of resistance heating element by laser trimming (see FIGS. 2, 3 and 8) Except that the resistance heating element pattern was a repeated pattern of bent lines as shown in FIG. In the same manner as in Example 1,
A ceramic heater was manufactured. When forming the notch, as shown in FIG. 2, the first notch (width: 75
μm, depth: 15 μm), the notches of the same shape were sequentially formed, and the width of the notches was adjusted. The number of cutouts formed to expand the width of the cutouts was 1 to 24 in total. In this ceramic heater, the thickness (width) of the current path in the cutout forming portion was 0.8 to 2.9 mm. Further, after the trimming was performed and the resistance value of the resistance heating element was adjusted, the variation in the resistance value of the four outer peripheral channels was 1.8 to 3.15%, and the variation was extremely small.

Comparative Example 1 Adjustment of Resistance Value of Resistance Heating Element by Laser Trimming (See FIG. 11) When adjusting the resistance value of the resistance heating element, as shown in FIG. Groove (width: 75 μm, depth:
A ceramic heater was manufactured in the same manner as in Example 1 except that a ceramic heater was formed. The current path in the notch forming portion was bifurcated, and each had a thickness of 0.4 to 1.5 mm. Further, after the trimming was performed and the resistance value of the resistance heating element was adjusted, the variation of the resistance value of the four outer peripheral channels was 1.8 to 3.1%, and the variation was very small.

(Comparative Example 2) Adjustment of resistance value of resistance heating element by laser trimming (see FIG. 11) The resistance heating element pattern was a repetitive pattern of bent lines as shown in FIG. When adjusting the resistance value, as shown in FIG. 11, a ceramic heater was manufactured in the same manner as in Example 1, except that a groove (width: 75 μm, depth: 15 μm) was formed in the center of the surface of the resistance heating element. did. The current path in the notch forming portion was bifurcated, and each had a thickness of 0.4 to 1.5 mm. Further, after the trimming was performed to adjust the resistance value of the resistance heating element, the variation of the resistance values of the four outer peripheral channels was 1.8 to 3.1%, and the variation was very small.

A ceramic heater (E5ZE manufactured by OMRON Corporation) was attached to the ceramic heaters according to Examples 1 to 3 and Comparative Examples 1 and 2 obtained through the above steps, and evaluated by the following indexes. Table 1 shows the results.

[0146]Evaluation method  (1) Temperature measurement of heating surface
To a set temperature of 300 ° C. for 10 minutes.
The interruption of the power supply for 0 minutes is repeated 1000 times.
Then, the temperature is raised to 200 ° C., and the temperature of the heating surface of the ceramic substrate is increased.
Thermo Viewer (IR-1620 manufactured by Nippon Datum Co., Ltd.)
12-0012), the minimum temperature and the maximum temperature
Was determined. Table 1 shows the results. Table 1 Temperature
The difference is a temperature difference between the minimum temperature and the maximum temperature.

[0147]

[Table 1]

As is clear from Table 1, the ceramic heaters according to the examples had uniform in-plane temperatures of the heating surfaces, whereas the ceramic heaters according to the comparative examples had extremely high in-plane temperatures of the heating surfaces. Was scattered. The ceramic heater according to the example and the ceramic heater according to the comparative example both have an in-plane heating surface of the ceramic heater according to the comparative example, even though the variation in the resistance value of the resistance heating element is adjusted. As a result of examining the cause of the temperature variation, in the ceramic heater according to Comparative Example 1, disconnection occurred in two of the seven channels, and in the ceramic heater according to Comparative Example 2, 12
It was found that disconnection occurred in two of the channels. In addition, the disconnection, in the place where the resistance value of the resistance heating element was all adjusted,
Had occurred. In addition, in the ceramic heater according to the example, no disconnection occurred.

In the ceramic heater according to the example, the disconnection occurred, and in the ceramic heater according to the comparative example, the disconnection did not occur. Because it is composed of only the current path, a thick (wide) current path can be secured, and as a result, disconnection due to heat generation of the resistance heating element and disconnection due to repeated temperature rise and fall are suppressed. On the other hand, in the ceramic heater according to the comparative example, since the notch forming portion is constituted by the bifurcated current paths, each current path becomes narrow (narrow).
As a result, it is considered that disconnection due to heat generation of the resistance heating element and disconnection due to repetition of temperature rise and temperature decrease occurred.

[0150]

According to the method of manufacturing a ceramic heater of the present invention, since the resistance value of the resistance heating element is adjusted by forming a notch in the resistance heating element, the variation in the amount of generated heat is small and the local resistance is reduced. It is possible to obtain a ceramic heater having a uniform heating surface temperature without any variation in values. Also,
Since the notch is formed such that the notch forming portion is constituted by only one current path, disconnection due to heat generation and disconnection due to repeated temperature rise and temperature decrease can be suppressed in the resistance heating element.

Further, according to the ceramic heater of the present invention, since the resistance value of the resistance heating element is adjusted by forming the notch in the resistance heating element, the variation in the heating value is small, and the local resistance is reduced. There is no variation in the values, and the temperature of the heating surface of the ceramic heater becomes uniform. In addition, since the notch forming portion is constituted by only one current path, disconnection due to heat generation and disconnection due to repeated rise and fall of temperature can be suppressed in the resistance heating element.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a laser trimming apparatus used in a method of manufacturing a ceramic heater according to the present invention.

FIGS. 2A to 2C are plan views showing a trimming method by laser beam irradiation according to the present invention.

FIG. 3 is a perspective view schematically showing grooves formed when the resistance heating element is subjected to a trimming process by the method shown in FIG. 2;

4 (a) to 4 (c) are plan views showing a trimming method by laser beam irradiation according to the present invention.

FIG. 5 is a perspective view schematically showing grooves formed when the resistance heating element is subjected to a trimming process by the method shown in FIG. 4;

FIG. 6 is a bottom view schematically showing a ceramic heater manufactured by the method for manufacturing a ceramic heater of the present invention and an example of the ceramic heater of the present invention.

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

FIG. 8 is a bottom view schematically showing a ceramic heater manufactured by the method for manufacturing a ceramic heater of the present invention and another example of 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 of the present invention.

FIGS. 10A to 10C are plan views showing a conventional trimming method using laser light irradiation.

11 is a perspective view schematically showing a groove formed when the resistance heating element is subjected to a trimming process by the method shown in FIG.

[Explanation of symbols]

10, 40 Ceramic heater 11, 41 Ceramic substrate 11a Heating surface 11b Bottom surface 12 (12a to 12g), 42 (42a to 42f) Resistance heating element 120a Metal coating layer 130 (130a to 130c), 131 (131a to 1)
31c) Notch 140, 141 Current path 10b Fixing projection 10c Stage 14 Laser irradiation device 15 Galvanometer mirror 16 Motor 17 Control unit 18 Storage unit 19 Operation unit 20 Input unit 21 Camera 22 Laser beam 23 Resistance measurement unit 24 Tester pin 25 Laser beam Irradiation device 33 External terminal 34, 44 Bottom hole 35, 45 Through hole 36 Lifter pin 39 Silicon wafer

Claims (2)

[Claims] 1. A ceramic heater for forming a predetermined pattern of a resistance heating element on a surface of a ceramic substrate and then irradiating the resistance heating element with a laser beam to form a notch to adjust the resistance value of the resistance heating element. A method of manufacturing a ceramic heater, wherein the notch is formed so as to be substantially parallel to a direction in which a current flows and so that the notch forming portion is formed by only one current path. 2. A ceramic heater in which a resistance heating element including a plurality of circuits is formed on a surface of a ceramic substrate, and a cutout is formed in a part of the resistance heating element, and a resistance value thereof is adjusted, A ceramic heater, wherein the notch is formed so as to be substantially parallel to a method of flowing an electric current, and the notch forming portion has only one current path.