JP2001244059A - Ceramic heater and wafer heating apparatus using the same - Google Patents

Abstract

(57) Abstract: A ceramic heater having a heating element on one main surface of a plate-shaped body made of ceramics and a power supply portion electrically connected to the heating element. When the thickness of the plate is reduced, the temperature distribution generated by the heating resistor is not sufficiently relaxed, and the temperature of the mounted wafer is not easily uniform. A resistance adjusting section is formed by trimming at least a part of the heating resistor to a resistance value within three times the resistance value of a surrounding pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer heating apparatus mainly used for heating a wafer and a ceramic heater used for the same. For example, the present invention relates to a semiconductor wafer, a liquid crystal substrate or a circuit substrate. The present invention relates to a wafer heating apparatus suitable for forming a thin film or forming a resist film by drying and baking a resist solution applied on the wafer.

[0002]

2. Description of the Related Art For example, in a semiconductor thin film forming process, an etching process, a resist film baking process, etc. in a manufacturing process of a semiconductor manufacturing apparatus, a semiconductor wafer (hereinafter abbreviated as "wafer") is heated to heat a semiconductor wafer. The device is used.

A conventional semiconductor manufacturing apparatus uses a batch-type apparatus for forming a plurality of wafers at a time. However, as the size of a wafer increases from 8 inches to 12 inches, the processing accuracy increases. In order to increase the quality, a technique called a single-wafer processing that processes one sheet at a time has been implemented in recent years. However, in the case of the single-wafer method, the number of processes per one process is reduced, so that the processing time of the wafer is required to be shortened. For this reason, there has been a demand for the wafer support member to shorten the heating time of the wafer, speed up the suction and desorption of the wafer, and simultaneously improve the heating temperature accuracy.

As an example of the above-described wafer heating apparatus 1, there is a wafer heating apparatus as disclosed in, for example, JP-A-11-283729. As shown in FIG. 9, the wafer heating apparatus mainly includes a support 31, a heat equalizing plate 22, and a stainless steel plate 33 as a plate-like reflector. The support 31 is a bottomed metal member (in this case, an aluminum member), and has an opening 34 having a circular cross section on an upper side thereof. Three pin insertion holes 35 for inserting wafer support pins (not shown) are formed in the center of the support 31. Pin insertion hole 35
By moving the wafer support pins inserted through the
Is transferred to the transfer device, and the wafer W is received from the transfer device. A conductive terminal 27 is brazed to a terminal portion of a heating resistor (not shown), and the conductive terminal 27 is configured to be inserted through a hole 57 formed in the stainless steel plate 33. Further, several holes 36 for leading out lead wires are formed in the outer peripheral portion of the bottom portion 31a.
A lead (not shown) for supplying a current to the heating resistor is inserted into the hole 36, and the lead is connected to the conduction terminal 27.

A ceramic material constituting the heat equalizing plate 22 is nitride ceramics or carbide ceramics. The heating resistor 25 is energized in a plurality of concentric patterns as shown in FIG. Thus, a device using a ceramic heater that heats the heat equalizing plate 22 has been proposed.

Meanwhile, the temperature uniforming plate 22 as the wafer heating device needs to precisely control the temperature distribution in the plane of the wafer W within a range of ± 0.5 ° C. For this reason, recently
As shown in FIG. 1, the wafer W is formed on the heat equalizing plate 22 so as to be parallel to the heat equalizing plate 22 at a position spaced apart from the aluminum heat equalizing plate 22 having a heating means or a cooling means. It has been proposed that the substrate is heat-treated while being spaced apart and supported by a spherical support pin 59 provided in the recessed portion 58 (JP-A-8-70007).

As described above, by keeping the wafer W apart from the heat equalizing plate 22, the temperature variation caused by the contact / non-contact caused by the warpage and the difference in flatness between the heat equalizing plate 22 and the wafer W is reduced. It is possible. When such a method is used for a conventionally used aluminum soaking plate 22, since the soaking plate 22 itself is thick, the temperature distribution generated by the heating resistor 25 is reduced by the heating soot plate 22. Since the thickness can be alleviated by the thickness, more favorable soaking can be maintained. This aluminum soaking plate 2
The second problem is that the operation of heating and cooling takes a very long time because the amount of heat is large.

On the other hand, there has recently been a demand for reducing the running cost of the apparatus by shortening the processing time. That is, after the wafer W is placed on the heat equalizing plate 22, the heating resistor is formed on the thin ceramic heat equalizing plate 22 having high rigidity and high thermal conductivity so that processing such as drying of the resist can be performed in a short time. And heating methods have been proposed.

[0009]

However, in the above-described wafer heating apparatus, when the thickness of the heat equalizing plate is reduced, the temperature distribution generated in the heating resistor is not sufficiently relaxed, and the temperature of the wafer W is relatively uniform. There was a problem that did not become.

The heat equalizing plate used in a single wafer type wafer heating apparatus, which has been attracting attention in recent years, is reduced in thickness to 1 to 7 mm in order to shorten the tact time for processing a wafer, and is heated and cooled. It is necessary to make an adjustment so that the cycle time of the data becomes short. However, in order to uniformly heat the entire surface of the wafer to a level of ± 0.5 ° C., there is a problem that a target cannot be achieved only by forming a heating resistor by a normal printing method.

In order to enhance the thermal response, even if a ceramic having a thermal conductivity of 50 W or more is used as the material of the heat equalizing plate 2, the temperature distribution formed by the heating resistor 5 will not be improved at such a thickness. It cannot be eased.

[0012]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a ceramic heater constituting a wafer heating device has a heating resistor on one main surface of a ceramic plate. And a power supply unit electrically connected to the heating resistor,
By providing at least a part of the heating resistor with a resistance adjusting portion adjusted so as to have a resistance value within three times the surrounding resistance value, the entire heating balance is made uniform and a good temperature distribution is obtained. Was found to be.

As a method for adjusting the resistance distribution, it has been found that polishing in the thickness direction of the heating resistor and laser trimming substantially parallel to the heating resistor pattern are effective.

[0014]

Embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view showing an example of a wafer heating apparatus according to the present invention. One main surface of a heat equalizing plate 2 made of a ceramic plate containing silicon carbide, alumina or aluminum nitride as a main component. Is a mounting surface 3 on which the wafer W is mounted, and a heating resistor 5 is formed on the other main surface via an insulating layer 4 made of glass, resin, or the like, and power is supplied to be electrically connected to the heating resistor 5. A ceramic heater is provided with the section 6.

The pattern of the heating resistor 5 may be a spiral or folded pattern as shown in FIG. 2 or divided into a plurality of blocks as shown in FIGS. A spiral or zigzag folded shape composed of an arc-shaped pattern and a linear pattern can be obtained. When the heating resistor 5 is divided into a plurality of blocks, it is preferable to control the temperature of each block independently so that the mounting surface 3 can be uniformly heated.

The heating resistor 5 of the present invention has a resistance adjusting portion having a resistance value different from that of the surroundings at least in a part thereof so that the heating resistor 5 can uniformly heat the uniform heat plate 2. It is characterized by. In addition, the adjustment range of the resistance value is within three times. However, if the resistance value is adjusted more than three times as compared with the surrounding area, the resistance adjustment part generates abnormal heat and the durability of the heating resistor deteriorates. This is because

As a method of forming the resistance adjusting portion, the heating resistor 5 shown in FIG. 5A is polished in a thickness direction using, for example, a luter having a rubber grindstone attached to the tip thereof. Thereby, as shown in FIG. 5B, the heating resistor 5 is shaved, and the resistance adjusting section 52 having a smaller thickness than the surroundings and as a result, a higher resistance value can be formed.

For example, when the heating resistor 5 divided into a plurality of blocks is formed on the heat equalizing plate 2 as shown in FIG.
A low-temperature portion is easily formed between the blocks. In such a case, a portion near the block of the heat-generating resistor 5 is shaved using a luter having a rubber whetstone attached to the tip thereof to form a resistance adjusting portion 52 having a high resistance value, and the amount of heat generated in this portion is reduced. By increasing it, the heat equalizing plate 2
The entire temperature distribution can be made uniform.

In general, since the current tends to flow the shortest distance, the current flows between the blocks as described above at a distance larger than an apparent interval. The temperature tends to decrease. Therefore, it is also possible to finely adjust the resistance distribution in the width direction by tapering the surface to be cut so that the outside of the resistance adjusting section 52 becomes thick.

As described above, the temperature accuracy of the heat equalizing plate 2 can be improved by forming the resistance adjusting portion 52 at a necessary portion of the heating resistor 5.

Next, another method for forming the resistance adjusting section 52 will be described. As shown in FIGS. 6A and 6B, a recess 1 is formed in a part of the heating resistor 5 along the entire length thereof.
4 can be formed by laser trimming, and this portion can be used as the resistance adjusting section 52. In this case, by forming a plurality of concave portions 14 in the heating resistor 5 in parallel, it is possible to expand the resistance adjustment range.

Further, since the heating resistor 5 is formed by a printing method, there is a thickness variation when viewed microscopically, and it has a porous structure. Therefore, when the laser is trimmed to a level where the resistance can be adjusted, a part of the insulating resistor is made of glass. Layer 4
The laser may reach up to. When the laser trimming reaches the insulating layer 4, cracks tend to occur in the insulating layer 4 due to thermal shock during heating and cooling, and as a result, cracks also occur in the heating resistor 5. Further, cracks grow due to repetition of temperature rise and fall during use, and the heating resistor 5
This causes a problem that the resistance of the semiconductor device greatly changes.

In order to solve this problem, as shown in FIG. 6, the depth of the concave portion 14 formed by using a low output laser trimming of about 0.7 to 2 W is set to 2/3 of the thickness of the heating resistor 5. By setting the degree, the generation of cracks in the heating resistor 5 was prevented. Normally, laser trimming has been improved in the direction of reducing the beam diameter and processing the depth deeper, but the laser trimming of the present invention is
Rather, it is oriented to trim wide and shallow. As described above, by lowering the output of the laser trimming, the heating resistor 5 having the resistance adjusting portion 14 formed therein is formed.
In addition, the generation of the crack 16 as shown in FIG. 7 and the reaction layer 51 as shown in FIG.
Can be prevented from decreasing in durability.

Here, the trimming has been described using the output of the laser as a parameter. However, the laser processing is defined by the output times the time, and when the processing speed is changed, the processing amount fluctuates as a whole. Incidentally, this evaluation was performed by using a YAG laser having a laser wavelength of 1.06 μm and setting the trimming speed to 5 mm / sec.

At the time of laser trimming, it is preferable that cracks are not generated in the insulating layer 4 and the heating resistor 5, but as shown in FIG. The recess 1
It has been found that when the thickness is 4 to 100 μm or less, good durability can be maintained.

Further, as shown in FIG. 8, the width b of the reaction layer 51 which appears as swelling on the surface of the heating resistor 5 when laser trimming is performed is set to 150 μm or less from the laser trimmed recess 14. ,
It was found that good durability was obtained. This reaction layer 51
Can be confirmed as swelling of the heating resistor 5 by an electron micrograph near the trimming pattern. As described above, since the heating resistor 5 around the concave portion 14 formed in the resistance adjusting section 52 is changed by the heat of the laser, when the width b of the reaction layer 51 is larger than 150 μm, the durability is deteriorated.

The durability was determined by examining the resistance change before and after repeating 5000 cycles of heating to 250 ° C. in 1 minute, holding for 3 minutes, and cooling to 40 ° C. or less in 2 minutes by forced air cooling. evaluated.

Since the laser trimming is usually performed in the atmosphere, the conductive components contained in the heating resistor 5 include a Pt group metal having good heat resistance and oxidation resistance, Au,
Alternatively, it is preferable to use an alloy mainly containing these alloys. The heating resistor 5 is preferably mixed with a glass component of 30 to 75% by weight in order to improve the adhesion to the insulating layer 4 and the sinterability of the heating resistor 5 itself.

Furthermore, the wafer heating apparatus of the present invention
As shown in FIG. 5, a ceramic heater comprising the heat equalizing plate 2 and the heating resistor 5 is joined to a support 11 and
Is connected to a conduction terminal 7. At this time, since the connecting means between the power supply unit 6 and the conductive terminal 7 is pressed by the elastic body 8, a difference in expansion between the heat equalizing plate 2 and the support 11 due to a temperature difference can be reduced by sliding of the contact portion. A favorable wafer heating apparatus can be provided for a thermal cycle during use. As the elastic body 8 serving as the pressing means, a coiled spring as shown in FIG. 1 or a leaf spring or the like may be used for pressing.

The pressing force of these elastic members 8 is set at 0.1.
What is necessary is just to apply a load of 3 N or more to the conductive terminal 7. The reason why the pressing force of the elastic body 8 is set to 0.3 N or more is that the conductive terminal 7 must move in response to a dimensional change due to expansion and contraction of the heat equalizing plate 2 and the support 11. Since the upper conductive terminal 7 is pressed against the power supply unit 6 from the lower surface of the heat equalizing plate 2, the conductive terminal 7 is prevented from separating from the power supply unit 6 due to friction with the sliding portion of the conductive terminal 7. is there.

The diameter of the conductive terminal 7 on the contact surface side with the power supply section 6 is preferably 1.5 to 4 mm. Further, as the insulating material 9 holding the conductive terminal 7, at a temperature of 200 ° C. or less, a PEEK (polyethoxyethoxyketone resin) material in which glass fibers are dispersed can be used depending on the use temperature. In addition, when used at a higher temperature, a ceramic insulating material 9 made of alumina, mullite, or the like can be used.

At this time, it is preferable that at least the contact portion of the conduction terminal 7 with the power supply portion 6 is formed of a metal composed of at least one of Ni, Cr, Ag, Au, stainless steel and a platinum group metal. . Specifically, the conductive terminal 7 itself is formed of the above metal, or the conductive terminal 7
May be provided with a coating layer made of the metal.
In addition, by inserting a metal foil made of the above-described metal between the conductive terminal 7 and the power supply unit 6, it is possible to prevent contact failure due to oxidation of the surface of the conductive terminal 7 and improve the durability of the heat equalizing plate 2. It is. Specifically, a metal foil 1 made of at least one of Ni, Cr, Ag, Au, stainless steel, and platinum group metal is provided between the power supply unit 6 and the conduction terminal 7.
When 6 is inserted, the reliability of the electrical contact is increased, and at the same time, the dimensional difference caused by the temperature difference between the heat equalizing plate 2 and the support 11 can be reduced by sliding the surface of the metal foil.

When the surface of the conductive terminal 7 is subjected to a breaking process or a sandblasting process to prevent the contact from becoming a point contact by roughening the surface, the reliability of the contact can be further improved.

The soaking plate 2 is attached to a metal support 11.
It is installed so as to cover the opening. The metal support 11 has a side wall and a single or multilayer plate-like structure 13. In the plate-like structure portion 13, a conducting terminal 7 for conducting electricity to a power supply portion 6 for supplying power to the heating resistor 5 of the heat equalizing plate 2 is provided via an insulating material 9. The hot plate 2 is pressed against the power supply section 6 on the surface. Also,
The thermocouple 10 is installed in the center of the heat equalizing plate 2 and immediately near the wafer mounting surface 3, and adjusts the temperature of the heat equalizing plate 2 based on the temperature of the thermocouple 10. When the heating resistor 5 is divided into a plurality of blocks and the temperature is individually controlled, a thermocouple 10 for temperature measurement is installed in each block of the heating resistor 5.

The heat equalizing plate 2 may be provided with a gas injection port (not shown) for cooling the heat equalizing plate 2 and an opening for discharging gas. Thus, the soaking plate 2
By providing the cooling mechanism described above, a tact time can be reduced by forming a semiconductor thin film or a resist film on the surface of the wafer W or by etching the surface.

It is preferable that the plate-like structure 13 has two or more layers. If this is a single layer, it takes a long time to achieve uniform heat, which is not preferable. It is desirable that the uppermost layer of the plate-like structure portion 13 be installed at a distance of 5 to 15 mm from the heat equalizing plate 2. This facilitates soaking by the radiant heat between the soaking plate 2 and the plate-like structure portion 13, and
Since there is a heat insulating effect with the other layers, the time required for uniform heating is shortened. Further, at the time of cooling, the gas that has received the heat of the surface of the heat equalizing plate 2 from the gas injection ports 12 is sequentially discharged to the outside of the layer, and a new cooling gas can cool the surface of the heat equalizing plate 2.
Cooling time can be reduced.

Further, operations such as mounting the wafer W on the mounting surface 3 and lifting the wafer W from the mounting surface 3 are performed by lift pins (not shown) installed in the support 7 so as to be able to move up and down. The wafer W is held in a state of being floated from the mounting surface 3 by wafer support pins (not shown) so as to prevent a temperature variation due to a one-sided contact or the like.

In order to heat the wafer W by the wafer heating apparatus 1, the mounting surface 3
Is supported by lift pins (not shown), and the lift pins 8 are lowered to place the wafer W on the mounting surface 3.

When the heat equalizing plate 2 is formed of, for example, a silicon carbide sintered body, a boron carbide sintered body, a boron nitride sintered body, an aluminum nitride sintered body or a silicon nitride sintered body, heat is applied. Even though the deformation is small and the plate thickness can be reduced, the heating time until heating to a predetermined processing temperature and the cooling time from cooling from a predetermined processing temperature to around room temperature can be shortened, and productivity can be reduced. Can be enhanced.

The silicon carbide sintered body forming the heat equalizing plate 2 is
Boron (B) and carbon (C) are added as sintering aids to silicon carbide as a main component, or alumina (Al
₂ O ₃ ) and a metal oxide such as yttria (Y ₂ O ₃ ) are added and mixed well, processed into a plate shape,
It is obtained by firing at 2100 ° C. Silicon carbide may be any of those mainly composed of α-type and those mainly composed of β-type.

As the boron carbide sintered body, 3 to 10% by weight of carbon is mixed as a sintering aid with boron carbide as a main component, and the mixture is sintered by hot pressing at 2000 to 2200 ° C. You can get the body.

As the boron nitride sintered body, 30 to 45% by weight as a sintering aid is added to boron nitride as a main component.
Of aluminum nitride and 5 to 10% by weight of a rare earth element oxide, and hot-pressed at 1900 to 2100 ° C. to obtain a sintered body. As another method for obtaining a sintered body of boron nitride, there is a method in which borosilicate glass is mixed and sintered, but this method is not preferable because the thermal conductivity is significantly reduced.

The aluminum nitride sintered body forming the heat equalizing plate 2 needs a rare earth element oxide such as Y ₂ O ₃ or Yb ₂ O ₃ as a sintering aid for aluminum nitride as a main component. According to the above, an alkaline earth metal oxide such as CaO is added, mixed well, processed into a plate shape,
It is obtained by firing at 0 to 2100 ° C.

As the boron carbide sintered body, 3 to 10% by weight of carbon is mixed as a sintering aid with boron carbide as a main component, and the mixture is sintered by hot pressing at 2100 to 2200 ° C. You can get the body.

As the silicon nitride sintered body forming the heat equalizing plate 2, 3 to 12% by weight of a rare earth oxide and 0.5 to 3 wt. weight%
Of Al ₂ O _3, further mixing SiO ₂ so that 1.5 to 5 wt% as SiO ₂ content in the sintered body, 16
A sintered body can be obtained by performing hot press firing at 50 to 1750 ° C. The amount of SiO ₂ shown here is
Si generated from impurity oxygen contained in silicon nitride raw material
O ₂ and SiO as impurities contained in other additives
₂ and SiO ₂ intentionally added including the influence from the atmosphere
Is the sum of

The temperature of the soaking plate 2 is measured by a thermocouple 10 whose tip is embedded in the soaking plate 2. As the thermocouple 10, from the viewpoint of its responsiveness and workability of holding,
It is preferable to use a sheath-type thermocouple 10 having an outer diameter of 1.0 mm or less. Further, the middle of the thermocouple 10 is held by the plate-like structure portion 13 of the support portion 7 so that no force is applied to the tip portion embedded in the heat equalizing plate 2. The distal end of the thermocouple 10 has a hole formed in the heat equalizing plate 2 and is fixed to the inner wall surface of the cylindrical metal body provided therein by a spring material to improve the reliability of temperature measurement. Preferred for.

Further, when the wafer heating apparatus 1 is used for forming a resist film, if a material containing nitride as a main component is used for the heat equalizing plate 2, it reacts with moisture in the atmosphere and ammonia gas In this case, it is preferable to use a heat equalizing plate 2 made of a carbide such as silicon carbide or boron carbide.

At this time, it is necessary to prevent the sintering aid from containing a nitride which may react with water to form ammonia or an amine. Thus, fine wiring can be formed on the wafer W at a high density.

Further, the main surface of the heat equalizing plate 2 opposite to the mounting surface 3 has a flatness of not more than 20 μm and a surface roughness of the center line from the viewpoint of enhancing the adhesion to the insulating layer 4 made of glass or resin. It is preferable to polish to an average roughness (Ra) of 0.1 μm to 0.5 μm.

On the other hand, when a silicon carbide sintered body is used as the heat equalizing plate 2, the insulating layer 4 for maintaining insulation between the heat equalizing plate 2 having semiconductivity and the heating resistor 5 is made of glass or glass. It is possible to use a resin. Here, when using glass, if the thickness is less than 100 μm, the withstand voltage is 1.5 k
When the thickness is less than V and the insulating property cannot be maintained, and when the thickness exceeds 600 μm, the thermal expansion difference with the silicon carbide sintered body forming the heat equalizing plate 2 becomes too large, so that cracks are generated and insulation occurs. It no longer functions as layer 4. Therefore, when glass is used as the insulating layer 4, the thickness of the insulating layer 4 is 100 μm to 6 μm.
It is preferably formed in the range of 00 μm, and more preferably in the range of 200 μm to 350 μm.

When the soaking plate 2 is formed of a ceramic sintered body containing aluminum nitride as a main component, the soaking plate 2
The insulating layer 4 made of glass is formed in order to improve the adhesion of the heating resistor 5 to the insulating layer 4. However, when sufficient glass is added to the heat generating resistor 5 and a sufficient adhesion strength can be obtained by this, it can be omitted.

The glass forming the insulating layer 4 may be crystalline or amorphous, and has a heat resistance of 200 ° C. or more and a thermal expansion coefficient in a temperature range of 0 ° C. to 200 ° C. It is preferable to appropriately select and use a ceramic having a coefficient of thermal expansion in the range of -5 to + 5 × 10 ⁻⁷ / ° C. with respect to the thermal expansion coefficient of the ceramic constituting the plate 2. In other words, when a glass having a coefficient of thermal expansion outside the above range is used, the difference in thermal expansion between the ceramic forming the soaking plate 2 and the ceramic becomes too large.
This is because defects such as cracks and peeling easily occur during cooling after baking of the glass.

Next, when a resin is used for the insulating layer 4, if the thickness is less than 30 μm, the withstand voltage falls below 1.5 kV, the insulation cannot be maintained, and the heating resistor 5 is trimmed by, for example, laser processing. In this case, the insulating layer 4 is damaged and does not function as the insulating layer 4. Conversely, when the thickness exceeds 150 μm, the amount of evaporation of the solvent and water generated during baking of the resin increases, and a foam-like peeling portion called blister is formed between the heat equalizing plate 2 and the presence of this peeling portion. Since the heat transfer becomes worse, the soaking of the mounting surface 3 is hindered. Therefore, when a resin is used as the insulating layer 4, the thickness of the insulating layer 4 is preferably in the range of 30 μm to 150 μm, and more preferably in the range of 60 μm to 150 μm.

When the insulating layer 4 is formed of a resin, polyimide resin, polyimide amide resin, or the like may be used in consideration of heat resistance of 200 ° C. or more and adhesion to the heating resistor 5.
It is preferable to use a polyamide resin or the like.

As a means for applying the insulating layer 4 made of glass or resin on the soaking plate 2, an appropriate amount of the glass paste or resin paste is dropped on the center of the soaking plate 2, and spin coating is performed. Stretch and apply uniformly, or apply evenly by screen printing, dipping, spray coating, etc., then at a temperature of 600 ° C. for glass paste and 3 for resin paste.
What is necessary is just to bake at the temperature of 00 degreeC or more. Also, the insulating layer 4
When glass is used as the material, a heat equalizing plate 2 made of a silicon carbide-based sintered body or an aluminum nitride-based sintered body is previously 1200
By heating to a temperature of about ° C. and oxidizing the surface on which the insulating layer 4 is to be adhered, the adhesion with the insulating layer 4 made of glass can be increased.

[0057]

EXAMPLES Example 1 A plurality of disc-shaped soaking plates 2 having a thickness of 4 mm and an outer diameter of 230 mm were manufactured by grinding a silicon carbide sintered body having a thermal conductivity of 80 W / m · K. A glass paste prepared by kneading ethyl cellulose as a binder and terpineol as an organic solvent with glass powder is laid by screen printing in order to apply the insulating layer 4 to one main surface of each heat equalizing plate 2. Then, the organic solvent is dried by heating to 150 ° C., then subjected to a degreasing treatment at 550 ° C. for 30 minutes, and further baked at a temperature of 700 to 900 ° C.
An insulating layer 4 made of glass and having a thickness of 200 μm was formed.
Then, in order to apply the heating resistor 5 on the insulating layer 4, a paste obtained by mixing 20% by weight of Au powder, 10% by weight of Pt powder, and 70% by weight of glass as a conductive material with a predetermined amount of a binder and a solvent is used. After printing in a predetermined pattern shape by a screen printing method, the organic solvent is dried by heating to 150 ° C., further subjected to a degreasing treatment at 450 ° C. for 30 minutes, and then baked at a temperature of 500 to 700 ° C. Thereby, the heating resistor 5 having a thickness of 50 μm was formed. The heating resistor 5 has a five-pattern configuration in which a central portion and an outer peripheral portion are divided into four in the circumferential direction.

A part of the heating resistor 5 thus prepared is trimmed to have a resistance of 20%, 50% and 1% with respect to the surrounding resistance.
To increase the resistance by 00%, 200%, 250%
The heating resistor 5 was polished in the thickness direction with a rotating rubber grindstone to adjust the resistance value. The same resistance adjustment was performed by laser trimming to remove 90% of the thickness of the heating resistor 5 in a direction substantially parallel to the entire length of the heating resistor 5 to adjust the resistance.

Thereafter, the temperature of the entire heat equalizing plate 2 is reduced to 3 in one minute.
After applying a voltage of 50 ° C. and holding for 3 minutes,
5000 thermal cycles of cooling to 40 ° C. or less per minute were performed, and the change in resistance value of the trimmed portion before and after the thermal cycle was investigated.

The resistance was measured by a four-terminal method so that the contact resistance was negligible. Also, as evaluation criteria,
In the above durability test, those having a resistance change rate within 5% were evaluated as OK, and those exceeding 5% as NG.

The results are as shown in Table 1.

[0062]

[Table 1]

As can be seen from Table 1, with respect to the sample in which the resistance portion of 2Ω was trimmed, No. 3 was trimmed so that the resistance value became 3.5 times. Nos. 6 and 11 were trimmed so that the resistance was in the range of 1 to 3 times, while the resistance was changed by 5% or more. In Nos. 1 to 5 and 7 to 11, the resistance change rate by the durability test was 5% or less.

Example 2 Here, the method of laser trimming was evaluated.

Using the sample prepared in the same manner as in Example 1, the conditions for laser trimming were changed, and the trimming depth was set to 50%, 70%, 80%,
Samples having resistance values adjusted to 90% and 100% were produced. The laser-trimmed portion having a resistance value of 2Ω was trimmed so as to have a resistance of 3Ω after the laser trimming, and the resistance change of each sample after durability was examined.

As for the trimming depth, five depths were confirmed using a surface roughness meter, and the depth of each deepest part was averaged to obtain the trimming depth.

The durability of the thus prepared sample was evaluated in the same manner as in Example 1, and the presence or absence of cracks before and after the sample and the change in resistance of the trimming portion were confirmed.

Regarding the crack length, a photograph of the trimming pattern was taken, a line having an average width of the trimming pattern was drawn, and a protruding distance in a direction perpendicular to the line was measured as the crack length.

The results are shown in Table 2.

[0070]

[Table 2]

As can be seen from Table 2, the laser trimming depth is 95%, 100%, of the thickness of the heating resistor 5.
% With No. In Nos. 6 and 7, the resistance change rate of the portion where the trimming pattern 14 was formed was as large as 4% or more.

On the other hand, the laser trimming depth of 90% or less with respect to the thickness of the heating resistor 5 was no more than No. 1-5
It was found that the resistance change rate of the portion where the trimming pattern 14 was formed was reduced to 3% or less.

Embodiment 3 Here, the heating resistor 5 in the case of laser trimming was used.
Was evaluated for the crack length a and the durability. The crack length a was prepared for each level by adjusting the laser trimming conditions. Crack width a
Was confirmed by electron micrographs of 200 to 400 times. The sample preparation method was the same as in Example 1, and the evaluation method and the measurement method were the same as in Example 2. The resistance of each sample was adjusted by laser trimming so that the initial 2Ω portion became 3Ω, and the durability of each sample was evaluated.

The results are shown in Table 3.

[0075]

[Table 3]

As can be seen from Table 3, the crack length a at the initial stage of the durability test was 134 μm. In No. 7, cracks grew after durability, and the rate of change in resistance was significantly increased. On the other hand, when the crack length a is 100 μm or less,
o. In Nos. 1 to 6, cracks did not grow and the resistance change rate was 1% or less, indicating good durability.

Embodiment 4 Here, the heating resistor 5 in the case of laser trimming was used.
Was evaluated for the relationship between the width b of the reaction layer 51 generated during the test and the durability. The width “b” of the reaction layer 51 was confirmed by measuring the width “b” of the raised portion around the trimming pattern 14 formed on the heating resistor 5 by an electron micrograph. The sample preparation method was the same as in Example 1, and the evaluation method and the measurement method were the same as in Example 2. The resistance of each sample was adjusted by laser trimming so that the initial 2Ω portion became 3Ω, and the durability of each sample was evaluated.

The results are shown in Table 4.

[0079]

[Table 4]

As can be seen from Table 4, the width b of the reaction layer 51 exceeds 150 μm. In No. 7, the rate of change in resistance after endurance exceeded 4%. On the other hand, when the width b of the reaction layer 51 was 150 μm or less, the sample No. In Nos. 1 to 6, the resistance change rate was 3% or less, indicating good durability.

Embodiment 5 Here, the heating resistor 5 for laser trimming was used.
The relationship between the material and the durability was investigated. The sample preparation method was the same as in Example 1, and the evaluation method and measurement method were the same as in Example 2. Trimming depth is 8 of heating resistor thickness
0%. As a material of the heat generating resistor 5, Au, Au-Cu, Au-Ni,
Each sample was produced using Au-Pt, Au-Rh, and Pt, each containing 30% by weight and the balance being glass.

The results are shown in Table 5.

[0083]

[Table 5]

As can be seen from Table 5, Au was used as the metal component.
No. using Cu—Au—Ni. In samples 2 and 3, the rate of change in resistance after the durability test was as large as about 3 to 4.3%.
This was presumed that the metal materials used, such as Cu and Ni, were oxidized during the durability test. In contrast, A
No. u, Au-Pt, Au-Rh, and Pt. 1,
In Nos. 3 to 6, the rate of change in resistance after the durability test was as small as 1% or less, indicating good durability.

[0085]

As described above, according to the present invention, the plate-shaped body made of ceramics has the heating resistor on one main surface and the power supply section electrically connected to the heating resistor. A ceramic heater having excellent heat uniformity by having at least a part of the heating resistor trimmed to a resistance value within three times the resistance value of the surrounding pattern. By using this, a wafer heating apparatus having excellent heat uniformity can be obtained.

As for the method of trimming the resistance value, a method of shaving the heating resistor in the thickness direction or a method of laser trimming the heating resistor to a depth of 90% or less in the thickness direction substantially in the full length direction can be used. It is. Further, when the resistance is adjusted by laser trimming, the crack of the heating resistor generated by the laser is 100 μm.
The following is preferred. The width of the reaction layer generated by laser trimming is preferably set to 150 μm or less. By adjusting the laser trimming conditions in this manner, a wafer heating apparatus having excellent heat uniformity and good durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a wafer heating apparatus according to the present invention.

FIG. 2 is a plan view showing an example of a heating resistor of the wafer heating device according to the present invention.

FIG. 3 is a plan view showing an example of a heating resistor of the wafer heating device of the present invention.

FIG. 4 is a plan view showing an example of a heating resistor of the wafer heating device of the present invention.

5A and 5B are views showing a heating resistor of the wafer heating apparatus according to the present invention, wherein FIG. 5A is an enlarged sectional view before trimming, and FIG. 5B is an enlarged sectional view after trimming.

6A and 6B are views showing laser trimming of a heating resistor in a wafer heating apparatus according to the present invention, wherein FIG.
(B) is the XX sectional drawing.

FIG. 7 is a schematic diagram of cracks generated in a trimming pattern of a heating resistor in a wafer heating apparatus according to the present invention by laser.

FIG. 8 is a schematic view showing a reaction layer generated by laser trimming of a heating resistor in the wafer heating device of the present invention.

FIG. 9 is an exploded perspective view showing a conventional wafer heating device.

FIG. 10 is a plan view showing a heating resistor in a conventional wafer heating device.

FIG. 11 is a sectional view of a heat equalizing plate in a conventional wafer heating apparatus.

[Explanation of symbols]

 1: Wafer heating device 2: Heat equalizing plate 3: Placement surface 4: Insulating layer 5: Heating resistor 6: Power supply unit 7: Conductive terminal 8: Elastic body 10: Thermocouple 11: Support body 14: Trimming pattern 16: Crack 17: Reaction layer a: Length b: Width 52: Resistance adjuster W: Semiconductor wafer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05B 3/12 H05B 3/68 // H05B 3/68 H01L 21/302 BF Term (Reference) 3K034 AA02 AA21 AA22 AA34 BB06 BB14 BC04 BC12 BC29 CA02 CA03 CA15 CA28 DA04 EA07 EA15 FA14 FA17 HA01 HA10 JA01 JA02 3K092 PP09 QA05 QB02 QB44 QB45 QB71 QB76 QC02 QC05 QC07 QC08 QC38 RF03 RF11 RF17 RF22 SS18 SS24 TT22 UA05 V18 V01 V28 V01 V28 V01 V18 V18 V18 V18 V18 V18 V18 V18 V18 V18 V01 HA02 HA18 HA19 HA37 MA24 MA28 MA32 5F045 EK08 EK21 EM09

Claims (9)

[Claims] 1. A ceramic heater comprising: a heating plate on one main surface of a plate made of ceramics; and a power supply portion electrically connected to the heating resistor. Characterized in that at least a part of the ceramic heater has a resistance adjusting section adjusted to have a resistance value within three times the surrounding resistance value. 2. The ceramic heater according to claim 1, wherein said resistance adjusting section is thinner than its surroundings. 3. The ceramic heater according to claim 1, wherein said resistance adjusting section has a recess substantially parallel to a pattern of the heating resistor. 4. The ceramic heater according to claim 3, wherein the depth of the recess is 90% or less of the thickness of the heating resistor. 5. The ceramic heater according to claim 3, wherein said concave portion is formed by laser trimming, and a width of a crack generated in said heating resistor is 100 μm or less from said concave portion. 6. The ceramic heater according to claim 3, wherein said concave portion is formed by laser trimming, and a width of a reaction layer generated in the heating resistor is 150 μm or less from said concave portion. 7. A conductive component constituting the heating resistor is P
4. The ceramic heater according to claim 3, wherein the main component is a t-group metal, Au, or an alloy thereof. 8. The ceramic heater according to claim 1, wherein a main surface of the plate-shaped body opposite to the heating resistor is used as a wafer mounting surface for heating the wafer. 9. A wafer heating apparatus, wherein the ceramic heater according to claim 8 is joined to a support, and a conduction terminal is connected to the power supply section.