JP2003282393A - Wafer-heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a wafer placed on a loading base is prone to warpage and not being heated evenly, depending on the flatness of the surface of the base, when the heater resistor area is increased to improve uniform heating of a heat leveling plate. <P>SOLUTION: When S(%) represents the ratio of the heater resistor area to one main surface area of the heat leveling plate, the wafer-heating device is set to the relation 15≤S≤50. <P>COPYRIGHT: (C)2004,JPO

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. For example, a thin film is formed on a wafer such as a semiconductor wafer, a liquid crystal device, a circuit board, or the like. It is suitable for forming a resist film by drying and baking the resist solution applied on the wafer.

[0002]

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

The conventional semiconductor manufacturing apparatus used was a batch type in which a plurality of wafers were collectively processed for film formation. However, as the size of the wafers increased from 200 mm to 300 mm, the processing accuracy was increased. In recent years, a method called a single-wafer processing for processing one sheet at a time has been implemented. However, if the single-wafer type is used, the number of processes per process is reduced, and therefore, it is necessary to shorten the wafer processing time. Therefore, it has been required for the wafer supporting member to shorten the heating time of the wafer and improve the temperature accuracy.

Of these, when forming a resist film on a semiconductor wafer, one main surface of a heat equalizing plate 2 made of ceramics such as silicon carbide, aluminum nitride or alumina as shown in FIG. On the mounting surface,
A wafer heating device 1 having a structure in which a heating resistor 5 is installed on the other main surface via an insulating layer 4 and a conduction terminal 7 is fixed to the heating resistor 5 by an elastic body 8 has been used ( (See Japanese Patent Laid-Open No. 2001-189276). The heat equalizing plate 2 is fixed to the support 11 with bolts 17, and the thermocouple 10 is inserted inside the heat equalizing plate 2.
As a result, the system adjusts the electric power supplied from the conduction terminal 7 to the heating resistor 5 so as to keep the temperature of the heat equalizing plate 2 at a predetermined value. In addition, the introduction terminal 7 has the plate-shaped structure 3
Was fixed via the insulating layer 9.

Then, on the mounting surface 3 of the wafer heating apparatus 1,
After the wafer W coated with the resist solution is placed, the heating resistor 5 is caused to generate heat to heat the wafer W on the placement surface 3 via the heat equalizing plate 2, and the resist solution is dried and baked to dry the wafer. A resist film was formed on W.

The heating resistor 5 is disclosed in Japanese Patent Laid-Open No. 1999-4.
As shown in the 0330 patent, gold, silver, platinum,
It has been introduced that the thickness is set to 10 to 20 μm by using a metal such as palladium, lead, tungsten, nickel, etc., but what is actually studied is the silver-lead type heating resistor 5.

In such a wafer heating apparatus 1, in order to form a uniform film on the entire surface of the wafer W or to homogenize the heating reaction state of the resist film, the temperature distribution of the wafer W should be uniform. is important. In order to reduce the temperature distribution of the wafer W, in the wafer heating device 1 having a built-in heater for heating, the resistance distribution of the heating resistor 5 is adjusted, the temperature of the heating resistor 5 is divided and controlled, and heat is drawn. It has been proposed to increase the amount of heat generated at the connecting portion when connecting a structural portion that is likely to occur.

Further, semiconductor design rules are advancing toward miniaturization year by year, and there is a demand for a wafer heating apparatus 1 capable of heating a photosensitive resin with a more uniform temperature distribution in order to miniaturize a wiring pattern. There is.

[0009]

However, the conventional wafer heating device has a problem in that the mounting surface is warped and the wafer W placed on the mounting surface cannot be heated to a predetermined temperature. .

When the cause was investigated, it was found that the formation of the heating resistor had an influence on the warp. Conventionally, in order to keep the temperature distribution on the surface of the heat equalizing plate constant, the heat generating area is increased by increasing the area where the heating resistor is formed to about 60% of the main surface of the heat equalizing plate. However, it was thought that it was effective in reducing the temperature distribution on the surface of the soaking plate, but after firing the aluminum nitride plate that is the base material of the soaking plate, a heating resistor was formed on one of its main surfaces. Then, it was found that warpage occurs due to the difference in thermal expansion coefficient between the heating resistor and the heat equalizing plate, which is not preferable.

[0011]

The wafer heating apparatus of the present invention was devised in order to solve the above-mentioned problems. One of the main surfaces of a heat equalizing plate made of aluminum nitride ceramics is used as a wafer heating device. A wafer heating apparatus comprising a placing surface, a heating resistor on the other main surface, and a power feeding portion electrically connected to the heating resistor on the other main surface, wherein Assuming that the area ratio of the heating resistor to the area of the one main surface is S (%), 15 ≦
It is characterized in that S ≦ 50.

Further, the line width of at least one heating resistor formed on the outer peripheral side of the heat equalizing plate is narrower than the line width of the heating resistor formed on the inner peripheral side.

The ratio w1: g1 of the line width w1 of the heat generating resistor and the distance g1 between adjacent lines is 0.2: 1 to.
The line width w1 is 0.8: 1 and the line width w1 is 4 mm or less.

Further, the heat generating resistor is divided into a central portion and an outer peripheral portion, and among these, the heat generating resistor formed on the outer peripheral portion is divided into four or more in the circumferential direction, so that heat generation in the outer peripheral portion is achieved. The power density of the resistor is 100 to 200% of the power density of the central portion.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view showing an example of a wafer heating apparatus 1 according to the present invention. A wafer W is placed on one main surface of a heat equalizing plate 2 made of ceramics containing aluminum nitride as a main component. In addition to the placement surface 3, the heating resistor 5 is formed on the other main surface.

Further, the heat generating resistor 5 is provided with a power feeding portion 6 made of a material such as gold, silver, palladium, platinum or the like, and the conductive terminal 7 is pressed against and brought into contact with the power feeding portion 6.
Continuity is secured.

Further, a bolt 17 is passed through the outer periphery of the heat equalizing plate 2 and the support 11 and is elastically fixed by screwing a nut from the side of the heat equalizing plate 2 with an elastic body and a washer interposed. . As a result, even if the temperature of the heat equalizing plate 2 is changed or a wafer is placed on the mounting surface 3 and the support body 11 is deformed when the temperature of the heat equalizing plate 2 is changed, the elastic body 8 can prevent the deformation. It is possible to prevent the warpage of the heat equalizing plate 2 by this, and to prevent the temperature distribution from being generated on the surface of the wafer W during the heating of the wafer.

The wafer W is held in a state of being lifted by about 100 μm from the mounting surface 3 by the support pins 17 installed on the mounting surface 3, and due to poor contact with the heat equalizing plate 2. The temperature distribution was prevented from occurring and the structure was heated by the heat radiation from the heat equalizing plate 2.

The support 11 is composed of a plate-shaped structure and a side wall, and a conductive terminal 7 for supplying electric power to the heating resistor 5 is installed on the plate-shaped structure through an insulating material. The air injection port 12 and the thermocouple fixing portion are formed. And
The conduction terminal 7 is structured to be fixed to the power feeding portion 6 by a conductive bonding material such as a brazing material.

In the wafer heating apparatus 1 of the present invention, when the area ratio of the heating resistor 5 to the area of the mounting surface 3 of the heat equalizing plate 2 is S (%), 15 ≦ S ≦ 50. Characterize. Here, the area of the heating resistor 5 means only the pattern portion where the conductor component is formed, and does not include the gap between the patterns.

The heating resistor 5 is not normally fired at the same time as the soaking plate 2, but after firing the soaking plate 2, both main surfaces of the soaking plate 2 are surface-ground, and then the heating resistor 5 is printed. It is formed by using a technique such as transfer, and is formed by baking at a temperature of 800 to 1200 ° C. The thickness of the heating resistor 5 is usually 10 to 20.
It is adjusted to μm.

As the heating resistor 5, an Ag paste to which a glass frit is added is usually used. The apparent thermal expansion coefficient of this Ag paste is determined by the volume ratio of the glass frit and Ag, and the thermal expansion coefficient is 15 to 16 × 10 ^−6.
/ ° C. On the other hand, the coefficient of thermal expansion of the soaking plate 2 is
4.5 × 10 ⁻⁶ / ° C., and 12 × 10 between the two.
There is a difference in thermal expansion of ^-6 / ° C.

Due to this difference in the coefficient of thermal expansion, thermal stress is generated in the uniform heat plate 2, and due to this thermal stress, the uniform heat plate 2 is warped such that the mounting surface 3 side of the uniform heat plate 2 is convex. Had occurred.
Up to now, in order to reduce the temperature distribution generated on the surface of the heat equalizing plate 2, the area ratio S of the heating resistor 5 to the area of the mounting surface 3 of the heat equalizing plate 2 has been set to about 60%. It was found that when the area ratio is increased, the warp becomes too large, which is not preferable.

In order to reduce the warpage of the heat equalizing plate 2, the thickness of the heat equalizing plate 2 may be increased, but if the thickness of the heat equalizing plate 2 is excessively increased, the cooling performance of the heat equalizing plate 2 deteriorates. Will end up. Therefore, the thickness of the soaking plate 2 is adjusted to 4 mm or less. Also,
In order to prevent the warp, it is preferable that the soaking plate 2 has a thickness of 2 mm or more. More preferably, the soaking plate 2 has a thickness of about 3 mm ± 0.5 mm.

Recently, it has been required to reduce the processing time of the single wafer processing for individually processing each wafer W individually, and the temperature of the wafer W installed on the mounting surface 3 side is raised. It is required to improve the thermal uniformity during the transition, and the time until the wafer W is maintained at 150 ± 0.3 ° C. after removing the processed wafer W and installing a new wafer W is 5
It is required to be 0 seconds or less. For this,
It has been found that it is preferable to adjust the warp so that the mounting surface 3 side is convex about 20 to 60 μm. Since the temperature of the outer peripheral portion is less likely to rise than that of the central portion, heat generation in the central portion is adjusted to be smaller than that of the outer peripheral portion. For this reason, it is difficult for the temperature of the central portion of the wafer to rise when the wafer W is replaced. Therefore, the central portion of the mounting surface 3 is adjusted to be convex as compared with the outer periphery. For this purpose, the area ratio S of the heating resistor 5 to the area of the mounting surface 3 of the heat equalizing plate 2 is set to 1
It has been found that 5 to 50% is preferable.

When the area ratio S is less than 15%, the heat uniformity of the heat equalizing plate 2 is impaired, and the temperature distribution of the wafer W mounted on the mounting surface 3 reaches 150 ± 0.3 ° C. This is not preferable because it takes a long time.

If the area ratio S exceeds 50%, the warp of the heat equalizing plate 2 exceeds 60 μm, and the temperature rise in the central portion becomes too fast, which is not preferable. Further, the area ratio S is preferably set to 15 to 40%.

This area ratio can be calculated from the design value of the area of the mounting surface and the area of the heating resistor. Further, when the measurement is performed directly from the actual soaking plate 2, it can be calculated by image analysis.

Further, as shown in FIG. 3, the line width w1 of at least one heating resistor 5 formed on the outer peripheral side of the heat equalizing plate 2 is the line width of the heating resistor 5 formed on the inner peripheral side. w2
It is preferably formed so as to be narrower than the above. By thus forming the line width w1 of the heating resistor 5 on the outer peripheral portion to be narrower than the line width w2 of the heating resistor 5 formed on the inner peripheral portion of the heat equalizing plate 2, the linear thermal expansion of the heating resistor 5 is performed. By dividing the thermal stress due to the difference in the rate, the stress of the warp is relaxed, and the warp can be reduced. Preferably w1 /
It is preferable to adjust w2 to be smaller than 0.9. Making the line width w1 of the outer peripheral portion smaller than the line width w2 of the inner peripheral portion is also effective for effectively increasing the temperature of the outer peripheral portion where heat dissipation is large. If the heating resistor 5 is radially divided into three blocks, w1 means the line width of the outermost block and w2 means the line width of the central block. The line widths w1 and w2 are averages of the line widths of the respective blocks.

The ratio w1: g1 of the line width w1 of the heat generating resistor 5 in the outer peripheral portion to the line distance g1 adjacent to the line is set to 0.2: 1 to 0.8: 1, and the line width w1 is 4 mm. The following is preferable. When the line width w1 is larger than 4 mm, the current flows in the bent portion in a concentrated manner and the temperature of the outer peripheral portion of the bent portion is hard to rise, so that the temperature of the heat equalizing plate 2 is ± 0.3. It becomes difficult to keep at ℃. In particular, when the heating resistor 5 is divided into a plurality of blocks, it becomes difficult to adjust the temperature distribution near the boundaries between the blocks. More preferably, the line width w1 is 1.0 to 2.
It is preferably 5 mm.

The relationship w1 between the line width w1 and the gap g1
In view of the temperature distribution, it is advantageous to make w1 / g1 larger than 1 in order to increase the heat generation area and reduce the temperature distribution. Since the warp of 2 becomes large, w1: g1 is set to 0.
Adjust to 2: 1 to 0.8: 1. More preferably, w
It is preferable to set 1: g1 to 0.3: 1 to 0.6: 1.

The relationship between the line width w1 and the inter-line distance g1 is the same for the line width w2 and the gap g2 of the inner peripheral portion, but the ratio of the outer peripheral portion is particularly important for warping.

It is preferable that the relationship between the line width w2 of the heating resistor 5 on the inner peripheral portion and the line distance g2 be the same.

Further, the heat generating resistor 5 is divided into at least a central portion and an outer peripheral portion, and the heat generating resistor 5 formed in the outer peripheral portion is divided into four or more in the circumferential direction. It is preferable that the power density of the heating resistor 5 in the central part is 100 to 200% of the power density in the central part.
The power density means the amount of heat generated per unit area of the conductor portion of the heating resistor 5 when the heating resistor 5 is heated. In order to adjust the temperature distribution in the circumferential direction within ± 0.3 ° C., it is necessary to divide the heating resistor 5 in the outer peripheral portion into at least four or more. Further, the power density of the outer peripheral portion is 100 to 200% with respect to the power density of the inner peripheral portion, more preferably 1
It is good to adjust to 30-160%.

Considering the heat radiation characteristics of the heat equalizing plate 2, the central portion is easy to heat without heating so much due to the heat conduction from the outer peripheral portion, but the outer peripheral portion has a large amount of heat radiation compared to the central portion, so If the calorific value is not increased compared to the parts, the uniform heating cannot be maintained. Regarding the heat equalizing plate 2 of the present invention in which the thickness of the heat equalizing plate 2 is as thin as 2 to 4 mm, the heat capacity of the heat equalizing plate 2 is small,
Temperature distribution is likely to occur. When the uniform heat plate 2 having such a small thickness is used, if the uniform heat plate 2 is warped due to the temperature distribution, the temperature distribution of the wafer W placed on the mounting surface 2 is further increased.

Therefore, it is also necessary to reduce the temperature distribution during the temperature rise transition when the wafer W is exchanged. Therefore, regarding the resistance distribution of the heating resistor 5, it is preferable that the resistance value gradually increases from the central portion toward the outer peripheral portion so that the temperature distribution becomes smaller after the temperature rise transient.

The thickness of the heating resistor 5 is 10 to 50.
It is preferable that the thickness is μm. If the thickness is less than 10 μm, there is a difference in thermal expansion between the heating resistor 5 and the soaking plate 2. Therefore, the resistance value of the heating resistor 5 increases and decreases due to the heat cycle during the temperature rise and decrease. However, it is not preferable because it will lead to disconnection. If the thickness of the heating resistor 5 exceeds 50 μm,
The stress due to the difference in thermal expansion between the heating resistor 5 and the heat equalizing plate 2 increases, and the warpage of the heat equalizing plate 2 increases, which is not preferable.
More preferably, it is 20 to 40 μm.

Further, the structure of the wafer heating apparatus 1 of the present invention will be described with reference to the drawings.

The wafer heating apparatus 1 of the present invention is shown in FIG.
As shown in FIG. 3, a plurality of recesses 21 are formed on the mounting surface 3, and support pins 17 for supporting the wafer W are arranged in the recesses 21. The protruding height of the support pin 17 from the mounting surface 3 is 0.05 to 0.5 mm, and the support pin 17 has one wafer center portion and at least three wafer diameters × 0. The support pins 17 are arranged on the outer circumference of 6 or more concentric circles, and the height variation of the support pins 17 is 15
The height of the support pin 17 at the central portion is adjusted to be lower than the height of the support pin 17 on the outer circumference.

If the protrusion height is less than 0.05 mm, the temperature of the heat equalizing plate 2 is likely to be picked up, and the temperature variation during the temperature rise transition becomes too large, which is not preferable. Also,
When the protrusion height exceeds 0.5 mm, the temperature responsiveness of the temperature of the wafer W after the exchange of the wafer W deteriorates, and the time until the temperature of the wafer W stabilizes is undesirably long. On the other hand, when the protrusion height is set to 0.05 to 0.5 mm, it is possible to reduce the temperature variation during the temperature rise transition and to stabilize the temperature of the wafer W promptly. More preferably, the range is 0.05 to 0.3 mm.

Further, the tip of the support pin 17 has a curved shape, and the surface roughness of the curved portion is Ra ≦ 0.8.
Must be μm. This is because, in order to reduce the adhesion of particles to the wafer W, the member supporting the wafer W should not damage the wafer W, and the area in contact with the wafer W should be small. Is. In order to minimize the area in contact with the wafer W, the tip of the support pin 17 should have a sharp shape, but on the contrary, the wafer W may be scraped off to generate particles. Therefore, the tip of the support pin 17 has a curved shape, and the surface roughness of the curved portion is R.
If a ≦ 0.8 μm, even if the wafer W slides, the wafer W
Also, the support pin 17 must have a smooth finish so as not to damage the support pin 17 itself.

The support pin 17 need not be joined to the recess 21 but simply placed. In that case, in order to prevent the falling off, as shown in FIG.
Installed on top of. This fixing jig 24 is provided with a support pin 17
There is no particular problem with or without contact with, and there is no problem even if a commercially available snap ring is used as the fixing jig 24. However, the material of the fixing jig 24 is Ni or SU.
A refractory metal such as S316, SUS631, 42 alloy, Inconel, Incoloy should be used.

Further, by elastically holding the heat equalizing plate 2 on the support body 11, the warp caused by the temperature distribution in the support body 11 can be alleviated by this elastic structure, so the heat equalizing plate It is possible to maintain the flatness of 2.

By the way, the metal support 11 has a side wall and a plate-like structure 13, and the plate-like structure 13 has an opening corresponding to 5 to 50% of its area. In addition, the plate-like structure 13 may further include a conduction terminal 7 for conducting a power supply portion 6 for supplying power to the heating resistor 5 of the heat equalizing plate 2 and a heat equalizing plate 2 if necessary. A gas outlet for this purpose and a thermocouple 10 for measuring the temperature of the soaking plate 2 are installed.

Further, a lift pin (not shown) is installed in the support 11 so as to be able to move up and down, and is used for mounting the wafer W on the mounting surface 3 or lifting it from the mounting surface 3. Then, in order to heat the semiconductor wafer W by the wafer heating device 1, after the wafer W carried to the upper side of the mounting surface 3 by a transfer arm (not shown) is supported by lift pins, the lift pins are lowered to lower the wafer W. Is placed on the placing surface 3.
Next, the power supply unit 6 is energized to generate heat in the heating resistor 5, and the wafer W on the mounting surface 3 is heated via the insulating layer 4 and the heat equalizing plate 2.

At this time, according to the present invention, since the soaking plate 2 is formed of an aluminum nitride sintered body,
Since deformation is small even if heat is applied and the plate thickness can be made thin, it is possible to shorten the temperature rising time until heating to a predetermined processing temperature and the cooling time until cooling from a predetermined processing temperature to near room temperature. Productivity can be increased and 1
Since it has a high thermal conductivity of 80 W / m · K, the Joule heat of the heating resistor 5 can be quickly transmitted even with a thin plate thickness, and the temperature variation of the mounting surface 3 can be made extremely small.

The aluminum nitride-based sintered body contains aluminum nitride as a main component, rare earth element oxides such as Y ₂ O ₃ and Yb ₂ O ₃ as sintering aids, and CaO and the like as necessary. After adding an alkaline earth metal oxide and mixing it well, and processing it into a flat plate, it is 1900 to 210 in nitrogen gas.
Obtained by firing at 0 ° C.

Further, the main surface of the heat equalizing plate 2 opposite to the mounting surface 3 has a flatness of 20 μm or less and a surface roughness of 0.1 μm to 0.5 μm in terms of center line average roughness (Ra). Preferably.

However, when silver is used for the heating resistor 5,
Since migration may occur, in such a case, a dense coating for preventing migration may be formed so as to cover the heating resistor 5.

[0051]

EXAMPLES Example 1 3% by weight of yttrium oxide was mixed with an aluminum nitride raw material by using an appropriate amount of a binder and a solvent, granulated, and then molded at a molding pressure of 100 MPa, 1900 to 2100 ° C.
To obtain a disc-shaped aluminum nitride-based sintered body having a thermal conductivity of 180 W / m · K and an outer diameter of 200 mm.

Both main surfaces of this sintered body were ground to obtain a disk-shaped soaking plate 2 having a plate thickness of 4 mm and an outer diameter of 200 mm, which was further heat-treated in the atmosphere at 1200 ° C. for 1 hour to carry out the firing. An oxide film 24 was formed on the surface of the bonded body. Next, in order to deposit the heating resistor 5 on the oxide film 24, a glass paste in which Au powder and Pt powder are mixed as a conductive material is printed in a predetermined pattern shape by a screen printing method, and then heated to 80 ° C. And dry the organic solvent.
After degreasing treatment at 0 ° C for 30 minutes, 700 ~ 900
By baking at a temperature of ℃, the thickness is 30 μm
The heating resistor 5 was formed. In addition, the mounting surface 3 of the heat equalizing plate 2
The area ratio S of the heating resistor 5 to the area of
Those prepared by changing 5%, 25%, 30%, 40%, 50% and 60% were prepared.

As shown in FIG. 2, the heating resistor 5 has a central portion and an outer peripheral portion which are radially divided into three equal parts, and the outer peripheral portion is divided into four peripheral portions.
Six patterns were equally divided. After that, the heat feeding resistor 5 was fixed to the power feeding portion 6 with a conductive adhesive to manufacture the soaking plate 2.

The support 11 is made of SUS304 having a thickness of 2.5 mm and having openings formed in 40% of the main surface.
A plate-shaped structure 13 is prepared, and one of the plate-shaped structures 13 is formed with thermocouples 10 and 10 conductive terminals 7 at predetermined positions, and the same is fixed to the side wall made of SUS304 by screwing. The support 11 was prepared.

Then, the soaking plate 2 is placed on the support 11.
The wafer heating apparatus 1 of the present invention shown in FIG.

Further, the feeding portion 6 made of gold paste was formed by the transfer method and baked at 900 ° C. After that, the outer periphery of the support 11 having the conductive terminals 7 having springs attached thereto is screwed with the elastic body 8 between them to obtain the wafer heating apparatus 1 of the present invention shown in FIG.

The height of protrusion of the support pin 17 from the mounting surface 3 was 100 μm.

Then, the conductive terminals 7 of the wafer heating apparatus 1 thus obtained are energized and held at 200 ° C., and the temperature distribution of the wafer surface placed on the placing surface 3 is determined by the soaking plate 2
Concentric circles with radiuses of 40 mm, 60 mm, and 90 mm, and a total of 10 points of 9 points that divide the circle into three equal points have a temperature variation of ± 0.3.
After confirming that the temperature is within ℃, further increase the temperature to 150 ℃.
Hold for 0 minutes, then place the wafer W on the wafer W
The transient characteristics of the temperature variation within the wafer surface until the temperature was maintained at 0 ° C. were evaluated.

As an evaluation criterion, a temperature overshoot within 1.0 ° C. when the temperature of the wafer surface rises was set to OK, and a temperature overshoot exceeding NG was set to NG. The overshoot amount mentioned here is a temperature difference that is excessively higher than the set temperature when the temperature of the soaking plate 2 is controlled to control the temperature of the wafer W to a predetermined temperature. Is.

Further, the temperature when the wafers are replaced is ±
The time to stabilize at 0.3 ° C. was measured at the same time. Regarding this, those that were stable within 50 seconds were judged to be good, and those that required more time were judged to be defective.

The results are shown in Table 1.

[0062]

[Table 1]

As can be seen from Table 1, No. 1 having an area ratio of the heating resistor 5 of 10%. 1 indicates that the temperature distribution generated when the heating resistor 5 generates heat does not easily become uniform and is ± 0.3.
The time required for the temperature distribution of the wafer to stabilize within 50% exceeds the target of 50 seconds. Further, in No. 3 in which the area of the heating resistor 5 is 60%. No. 6 has a soaking plate 2 with a warp of 80 μm
Similarly, the time for the temperature distribution of the wafer to stabilize within ± 0.3% exceeded the target of 50 seconds.

On the other hand, the area ratio of the heating resistor 5 is 1
No. 5 to 50%. In Nos. 2 to 5, the stable time was within 50 seconds and good temperature rising characteristics were exhibited.

Example 2 Here, the relationship between the line width w1 of the outer peripheral portion of the heating resistor 5, the line width w2 of the inner peripheral portion, and the warp of the heat equalizing plate 2 was investigated.
An aluminum nitride plate having an outer diameter of 320 mmφ and a thickness of 3 mm was flat-polished using a double-sided polishing machine so that the parallelism between the two main surfaces was 10 μm or less, and then Ag was used as a conductor component on the surface as a binder. The heating resistor 5 containing glass was formed into a print with a thickness of 20 μm and baked at 800 ° C., after which the warpage of the soaking plate was evaluated. w1 / w2 is 1: 1,
The warpage of the soaking plate 2 was confirmed by changing to 0.8: 1, 0.6: 1 and 0.4: 1. Here, as the line widths w1 and w2, the average value of the line widths at arbitrary 10 points in each of the outermost block and the central block was taken.

The results are shown in Table 2.

[0067]

[Table 2]

As can be seen from Table 2, No. 1 with the width ratio w1 / w2 of the heating resistor 5 being 1: 1. 1, the warpage of the heat equalizing plate 2 was 80 μm, but the ratio w1 / w2 was 1: 1.
The smaller No. 2 to 7 showed a tendency that the warp was reduced as the ratio was decreased. The temperature stabilization time is also
There was a tendency for improvement as the area ratio w1 / w2 of the heating resistor 5 was reduced.

It has been found that the warp of the heat equalizing plate 2 can be reduced by narrowing the line width w1 of the outer peripheral portion of the heating resistor 5 compared with the line width w2 of the inner peripheral portion.

Example 3 Here, the relationship between the ratio w1: g1 of the line width w1 of the outer peripheral portion of the heating resistor 5 and the distance g1 between the lines and the warp of the heat equalizing plate 2 was investigated. w1: g1 is 1: 1, 0.8:
1, 0.6: 1, 0.5: 1, 0.4: 1, 0.3:
The warpage of the soaking plate 2 was confirmed by changing the values to 1, 0.2: 1 and 0.1: 1. In addition, by incorporating the heat equalizing plate 2 into the support 11, the temperature stabilization time until the temperature of the wafer W becomes uniform when the wafer W is remounted was measured as in Example 1. As the heating resistor 5, a paste obtained by printing 40 μm of a mixture of 78% by weight of Ag and 22% by weight of zinc-borosilicate glass which is a low melting point glass was used.

The heating resistor 5 was arranged in a pattern in which the heating resistor 5 was divided into a central portion and an outer peripheral portion, and the heating resistor 5 on the outer periphery was divided into four in the circumferential direction.

The results are shown in Table 3.

[0073]

[Table 3]

As can be seen from Table 3, No. 1 in which the width ratio w1: g1 of the heating resistor 5 was 1: 1. In No. 1, the warp of the heat equalizing plate 2 was 80 μm, but the ratio w1: g1 was 1: 1.
The smaller No. 2 to 7 showed a tendency that the warp was reduced as the ratio was decreased. The temperature stabilization time is also
There was a tendency for improvement as the ratio w1: g1 of the heating resistor 5 was reduced. However, when the ratio w1: g1 is 0.1: 1, the temperature stabilization time tends to increase probably because the line width w1 is too narrow with respect to the line distance g1. Therefore, the ratio w1: g1 is preferably 0.2: 1 to 0.8:
I decided that it would be better to set it to 1.

[0075]

As described above, according to the present invention, one main surface of the heat equalizing plate made of aluminum nitride ceramics serves as a wafer mounting surface, and the other main surface has a heating resistor. In a wafer heating apparatus having a power supply portion electrically connected to the heating resistor on the other main surface, the area ratio of the heating resistor to the area of one main surface of the heat equalizing plate is S ( %), By setting 30 ≦ S ≦ 50, the overshoot during the temperature rise transition of the wafer when the wafer is exchanged is reduced to 8 ° C. or less, the overshoot amount is reduced, and the predetermined temperature is reduced. ± 0.
It has become possible to provide a wafer heating apparatus capable of stabilizing the wafer temperature at 3 ° C. in a short time of 50 seconds or less.

Further, by making the line width of the heating resistor narrower at the outer peripheral portion than at the inner peripheral portion, it is possible to reduce the warpage of the heat equalizing plate, and the temperature recovery time at the time of wafer replacement is reduced. It can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a wafer heating apparatus of the present invention.

FIG. 2 is an enlarged sectional view of a support pin installation portion of the wafer heating apparatus of the present invention.

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

[Explanation of symbols]

1: Wafer heating device 2: Soaking plate 3: Mounting surface 4: Insulation layer 5: Heating resistor 6: Power supply unit 7: Conductive terminal 8: Elastic body 10: Thermocouple 11: Support 20: Support pin 21: Recess 24: Fixing jig W: Wafer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 3/20 373 H01L 21/30 567 3/74 21/302 101G F term (reference) 3K034 AA02 AA08 AA10 AA15 AA16 AA19 AA34 BB06 BB14 BC04 BC12 BC24 BC29 CA02 CA17 CA22 CA27 CA32. BB01 BB08 EK09 EM09 5F046 KA04

Claims (4)

[Claims] 1. A soaking plate made of aluminum nitride ceramics has one main surface as a wafer mounting surface, the other main surface has a heating resistor, and is electrically connected to the heating resistor. In a wafer heating apparatus having a power feeding portion on the other main surface, when the area ratio of the heating resistor to the area of one main surface of the heat equalizing plate is S (%),
A wafer heating apparatus, wherein 15 ≦ S ≦ 50. 2. The line width of at least one heat generating resistor formed on the outer peripheral side of the heat equalizing plate is narrower than the line width of the heat generating resistor formed on the inner peripheral side. Wafer heating apparatus described. 3. A ratio w1: of a line width w1 of a heating resistor formed on the outer peripheral portion of the heat equalizing plate and a distance g1 between adjacent lines.
2. The wafer heating apparatus according to claim 1, wherein g1 is 0.2: 1 to 0.8: 1 and line width w1 is 4 mm or less. 4. The heat generating resistor is divided into a central portion and an outer peripheral portion, and among these, the heat generating resistor formed on the outer peripheral portion is divided into four or more in the circumferential direction, and heat generation in the outer peripheral portion. The power density of the resistor is 100 to the power density of the central part.
The wafer heating apparatus according to claim 1, wherein the wafer heating rate is 200%.