JP2007096313A - Wafer heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the subject that, since the resistance temperature coefficient of a heat-generating resistor is as large as more than 4,000/°C, when rapid temperature rising is attempted for a wafer exchange or set temperature change, a temperature control is not successful and the temperature variation of the wafer cannot be reduced in a wafer heating apparatus which uses a single substance of metal like Au, Ag or Pt as the heat-generating resistor. <P>SOLUTION: The resistance value distribution of the heat-generating resistor is adjusted on the heat equalizing plate of the wafer heating apparatus by making small the part of the resistance values of the heat-generating resistor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer heating apparatus mainly used for heating a wafer, a ceramic heater used therefor, and a method for manufacturing the same, for example, generating a semiconductor thin film on a wafer such as a semiconductor wafer, a liquid crystal substrate, or a circuit substrate. And a wafer heating apparatus suitable for forming a resist film by drying and baking a resist solution applied on the wafer.

  For example, a wafer heating apparatus is used to heat a semiconductor wafer (hereinafter abbreviated as a wafer) in a semiconductor thin film forming process, an etching process, a resist film baking process, and the like in a manufacturing process of a semiconductor manufacturing apparatus. Yes.

  Conventional semiconductor manufacturing equipment used batch-type processing that forms a plurality of wafers together. To increase processing accuracy as the wafer size increases from 8 inches to 12 inches, In recent years, a method called 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 decreases, so that it is necessary to shorten the wafer processing time. For this reason, the wafer support member has been required to improve the heating temperature accuracy at the same time as shortening the heating time of the wafer and speeding up the adsorption and desorption of the wafer.

  As an example of the wafer heating apparatus as described above, for example, in Patent Document 1, “a heating element formed by sintering metal particles on the surface of a plate-like body made of nitride ceramics or carbide ceramics is provided. "Heater".

  In forming a resist film on a semiconductor wafer using such a ceramic heater, for example, as shown in FIG. 1, one main plate of a soaking plate 2 made of ceramic such as silicon carbide, aluminum nitride, or alumina is used. The surface is a mounting surface 3 on which the wafer W is placed, and the other main surface is provided with a heating resistor 5 through an oxide film and an insulating layer 4, and a conduction terminal 7 is connected to the heating resistor 5 with an elastic body 8. A wafer heating apparatus 1 having a structure fixed by the above has been proposed. The soaking plate 2 is fixed to the support 11 with bolts 17, and a thermocouple 10 is inserted into the soaking plate 2, thereby keeping the temperature of the soaking plate 2 at a predetermined temperature. In this system, the power supplied from the conduction terminal 7 to the heating resistor 5 is adjusted. Further, the conduction terminal 7 was fixed to the plate-like structure portion 13 via the insulating layer 9.

  Then, after the wafer W coated with the resist solution is placed on the placement surface 3 of the wafer heating apparatus 1, the heating resistor 5 is caused to generate heat, thereby allowing the wafer on the placement surface 3 to pass through the soaking plate 2. W was heated and the resist solution was dried and baked to form a resist film on the wafer W.

Further, as the heating resistor 5, one made of Au, Ag, Pt, Pd, Pb, Ni or the like was used.
Japanese Patent Laid-Open No. 11-40330

  However, for example, when a single metal such as Au, Ag, Pd, or Pt is used as a heating resistor, the temperature coefficient of resistance is as large as 4000 ppm / ° C. or more, so let's quickly raise the temperature to replace the wafer or change the set temperature. When this is done, due to the variation in the resistance distribution, the high resistance part mainly consumes power, and the temperature of this part rises selectively, so the resistance value further rises. It has been found that there is a tendency to worsen the overall temperature distribution as it increases. Further, it has been found that this tendency changes depending on the temperature distribution of the soaking plate at the time of voltage application, and that the reproducibility of the temperature distribution at the time of temperature rise is not good.

  In order to make the temperature distribution of the wafer uniform, it is necessary to precisely control the resistance value distribution of the heating resistor. Therefore, the present inventors have proposed that the resistance value distribution of the heating resistor is controlled by laser trimming. However, the technique called laser trimming is a method of adjusting the resistance value by scratching the once formed heating resistor. Therefore, with regard to durability, there is a possibility that a change in resistance value may occur when the use conditions become severe.

  As a result of intensive studies on the above problems, the inventors of the present invention have one main surface of a plate-shaped body made of ceramics as a wafer mounting surface and an insulating layer made of glass having a thickness of 10 to 600 μm on the other main surface. In the wafer heating apparatus provided with the heating resistor on the insulating layer, the temperature distribution of the wafer is obtained by adjusting the resistance value distribution of the heating resistor by reducing a part of the resistance value on the heating resistor. It has been found that the problem of durability can be solved.

  Further, it has been found that, as a method for adjusting the resistance value of the heating resistor, the durability problem can be solved by repeatedly coating the resistor pattern on the heating resistor pattern.

  According to the present invention, in the wafer heating apparatus provided with an insulating layer made of glass having a thickness of 10 to 600 μm on one main surface of a plate-like body made of ceramics, the heat generating element is provided with a heating resistor on the insulating layer. It has been found that the durability problem can be solved by adjusting the resistance value distribution of the heating resistor by reducing a part of the resistance value on the resistor.

  In addition, regarding a method for adjusting the resistance value of the heating resistor, a wafer having an insulating layer made of glass having a thickness of 10 to 600 μm on one main surface of a plate made of ceramics, and the heating resistor provided on the insulating layer. In the heating device, the heating resistor is a wafer heating device in which the resistance value distribution is adjusted by repeatedly coating the resistor pattern on the heating resistor, so that the heating resistor 5 has excellent durability. You can get

  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, in which one main surface of a soaking plate 2 made of ceramics is used as a mounting surface 3 on which a wafer W is placed, and is formed on the other main surface. A heating resistor 5 is formed on the SiO ₂ film through an insulating layer 4 made of glass, and a wafer heating apparatus is configured by including a power feeding portion 6 electrically connected to the heating resistor 5. .

  Further, as the pattern shape of the heating resistor 5, a pattern that can uniformly heat the mounting surface 3, such as a substantially concentric circular shape including a circular electrode portion and a linear electrode portion, or a spiral shape. Any shape is acceptable. In order to improve the heat uniformity, the heating resistor 5 can be divided into a plurality of patterns.

  The heating resistor 5 is made of a metal having a temperature coefficient of resistance of 2000 ppm / ° C. or less. This is because if the temperature coefficient of resistance exceeds 2000 ppm / ° C., the temperature control of the soaking plate 2 cannot be performed well at the time of rapid temperature rise when changing the wafer or changing the set temperature, and within the target 10 ° C. This is because it becomes difficult to maintain the temperature variation. The heating resistor 5 is usually formed on the insulating layer 4 formed on the heat equalizing plate 2 by a printing method or a transfer method. However, since there is a certain thickness variation, the resistance value distribution of the heating resistor 5 is unavoidable. The variation will remain. If full power is applied in order to rapidly raise the temperature of the wafer W there, the voltage is concentrated at a high resistance value and the heat generation is biased. It was found that when the heat generation is biased in this way, the resistance value of this portion further increases and the variation in resistance value further increases. It has been found that this tendency increases as the wafer size increases from 8 inches to 12 inches.

  On the other hand, it has been found that when the temperature coefficient of resistance of the heating resistor 5 is 2000 ppm / ° C. or less, the above change can be reduced by a synergistic effect with the effect of heat conduction of the soaking plate 2.

  In order to set the temperature coefficient of resistance of the heating resistor 5 to 2000 ppm / ° C. or less, it is effective to alloy the metal material. For example, when the heating resistor 5 is formed on the surface of the soaking plate 2 as in the present invention, Au, Au, Pd, Pt, Au—Pt, Au—Ag, Pt—Rh, Ag—Pd, etc. An alloy composed of two or more metals having good heat resistance such as Rh and Ir may be used as the heating resistor 5. More preferably, a combination of Au—Pt group metals is preferable in order to prevent a change in resistance value due to oxidation of the metal material. In this case, a metal alloyed from the beginning may be used, or powder may be mixed and alloyed during sintering. Further, when alloying at the time of sintering, Au—Pt, Au—Ag, and Ag—Pd may be fired in the air at 900 to 1100 ° C. In the case of Pt—Rh, it may be fired at 1300 to 1500 ° C.

  If the temperature coefficient of resistance is 2000 ppm / ° C. or less, even if there is a deviation in the resistance value distribution of the heat generating resistor 5, the heat generation variation can be absorbed by heat conduction through the heat equalizing plate 2. Can be rapidly heated with a good temperature distribution.

  Here, an example of a two-component system is shown, but the same applies to the resistance temperature coefficient of the heating resistor 5 made of a three-component or four-component metal.

  The resistance of the metal increases as the temperature is increased. It is known that when the temperature is increased, the Brownian motion of electrons due to heat becomes active, which hinders electrical conduction. For this reason, as the temperature is raised, the resistance value of the metal converges to a certain level. On the other hand, when the metal is alloyed, the resistance value near room temperature increases due to the change in crystallinity and the influence of a newly generated crystal interface, so that the apparent temperature coefficient of resistance decreases. Accordingly, the resistance temperature coefficient decreases as the amount of different metals mixed increases.

  Further, the heating resistor 5 includes glass for improving adhesion to the insulating layer 4, and the processing accuracy of the heating resistor 5 is that the softening point of the glass is lower than the transition point of the glass included in the insulating layer 4. It is preferable for improving the ratio. Glass is considered to be a highly viscous fluid at temperatures above the transition point. For this reason, the softening point of the glass contained in the heating resistor 5 is made lower than the transition point of the glass contained in the insulating layer 4 so that the insulating layer 4 serving as a substrate is not affected when the heating resistor 5 is baked. To do.

  The reason for forming the heating resistor 5 on the surface of the soaking plate 2 is to further adjust the resistance value distribution of the heating resistor 5 after the heating resistor 5 is formed. As a method for adjustment, there is a method in which a part of the heating resistor 5 is scraped off. However, in this method, a defect is necessarily generated in the heating resistor 5. Therefore, in the present invention, by using a technique in which a resistor pattern is overcoated on the heating resistor 5, the generation of defects in the heating resistor 5 is prevented and the durability is improved.

  Here, a method of adjusting the resistance value of the heating resistor 5 will be described with reference to FIG. When the resistance value adjusting unit 5a higher than the target resistance value is present in the heating resistor 5, a new resistor pattern 5 'is overcoated on the resistance value adjusting unit 5a, and the resistance value distribution is set to the target value level. Can be adjusted.

  It is an object of the present invention to control the resistance value distribution by reducing the resistance value of the portion by overcoating the resistor pattern 5 '. In resistance value distribution control by laser trimming, the resistance value distribution is controlled by the reverse operation in the present invention, while processing is performed to increase the resistance value of the heating resistor 5 pattern where the resistance value is low. Will do.

  Regarding the place where the resistor pattern 5 ′ is formed, the heating resistor 5 is divided into a number of subdivided blocks, and the target resistance value of each block is set, and the resistance value is shifted from the target value. Adjust the resistance value so that only the part that is present matches the target value.

  In addition, since the width of the resistance value control by pattern formation can be reduced by adjusting the specific resistance of the resistor pattern 5 ′ for correcting the resistance higher than the specific resistance of the heating resistor 5, the resistance of the heating resistor 5 can be reduced. The value can be adjusted precisely. Preferably, it is better to adjust the specific resistance higher by 10% or more. When the resistance value is adjusted by overcoating, if the resistance value adjustment width is small, it is necessary to reduce the width for applying the resistor pattern 5 'or reduce the application thickness. This coating accuracy is one factor that determines the variation in resistance value correction.

  The paste forming the resistor pattern 5 ′ can be applied by a printing method or by applying the resistor pattern 5 ′ having a resistance value adjustment width set in advance. Further, it is preferable that the paste forming the resistor pattern 5 ′ is baked at a temperature lower by 10 ° C. or more than the baking temperature of the heating resistor 5. By processing the baking of the resistor pattern 5 ′ as described above, it is possible to suppress the initial resistance value of the heating resistor 5 from changing depending on the baking temperature of the paste forming the resistor paste 5 ′.

  The structure of the wafer heating apparatus 1 which is one embodiment of the present invention will be described in detail with reference to FIG. An insulating layer 4 is formed on the surface of the soaking plate 2 made of ceramic, and a heating resistor 5 made of at least two kinds of Au, Pd, Ag, and Pt group metals is formed on the insulating layer 4. The resistor 5 is provided with a power feeding portion 6 to constitute the soaking plate 2. The heat equalizing plate 2 is joined to the support 11 and the conductive terminal 7 is pressed and connected to the power feeding portion 6 to constitute a wafer heating apparatus. The wafer W is held away from the placement surface 3 by the support pins 22. This prevents the problem that the wafer W hits the soaking plate 2 and the temperature distribution is deteriorated.

  The insulating layer 4 made of glass has a thickness of 10 to 600 μm. If the thickness is less than 10 μm, the electrical insulation between the soaking plate 2 and the heating resistor 5 becomes insufficient. On the other hand, if the thickness exceeds 600 μm, the glass has a low thermal conductivity, which is not preferable because heat transfer from the heating resistor 5 to the wafer W mounting surface 3 becomes slow.

  The flatness of the surface of the insulating layer 4 made of glass is preferably 300 μm or less. If the flatness exceeds 300 μm, the thickness variation when the heating resistor 5 is formed on the surface of the insulating layer 4 increases, and the resistance value variation of the heating resistor 5 increases, which is not preferable.

In order to set the flatness of the insulating layer 4 made of glass to 300 μm or less, the flatness on the side where the insulating layer 4 of the soaking plate 2 is applied is set to 300 μm or less, and at the same time, the heat of the ceramics constituting the soaking plate 2 It is preferable to reduce the thermal expansion coefficient of the glass in the range of ⁰ to 0.9 × 10 ⁻⁶ deg ⁻¹ with respect to the expansion coefficient. This is because the stress due to shrinkage when the glass is sintered is not sufficiently relieved by the heat treatment at the time of baking, and warping that makes the insulating layer 4 side concave is likely to remain. Thus, reducing the warpage of the soaking plate 2 by making the thermal expansion coefficient of the glass smaller than that of the ceramic forming the soaking plate 2 is effective in improving the flatness.

  When the flatness of the insulating layer 4 is greater than 300 μm, the heating resistor 5 whose film thickness is controlled in advance is formed on the transfer sheet, and the heating resistor 5 is formed on the insulating layer 4 by transfer. Thus, the thickness of the heating resistor 5 is made uniform so that the soaking plate 2 can be heated uniformly.

  The insulating layer 4 made of glass is formed by forming a film having a certain thickness by printing or transferring, and heat-treating it at a temperature equal to or higher than the working point of the glass. The coefficient of thermal expansion of the glass is preferably a coefficient of thermal expansion slightly smaller than the coefficient of thermal expansion of the ceramic base material of the soaking plate 2. This is because when the glass is sintered and melted, the stress due to the shrinkage is not sufficiently relaxed, and the stress due to the shrinkage remains in the form of warping, and this is absorbed. As a result, the stress remaining in the glass becomes a compressive stress, so that cracks hardly occur due to thermal stress.

  Further, the flatness of the soaking plate 2 after being fixed to the support 11 is preferably 80 μm or less, more preferably 40 μm or less. The reason why the flatness of the soaking plate 2 is 80 μm or less is that by controlling the distance between the wafer W and the soaking plate 2, the temperature in the wafer W surface is precisely adjusted when the temperature of the wafer W is rapidly raised. This is so that it can be managed.

  Further, it is preferable that the center portion of the space between the soaking plate 2 and the wafer W is narrower than the outer peripheral portion. In order to make the temperature distribution of the heat equalizing plate 2 constant, the heat generation distribution of the heat generating resistor 5 is such that the heat generation amount is larger in the outer peripheral portion where heat is likely to escape from the center portion. For this reason, when the temperature is rapidly raised, the temperature rise at the center of the wafer W tends to be delayed. In order to reduce this tendency, it is preferable that the distance between the heat equalizing plate 2 and the wafer W is narrower at the center than at the outer peripheral portion because the responsiveness to the temperature change of the heat equalizing plate 2 becomes faster.

  Moreover, as ceramics which form the soaking | uniform-heating board 2, what has as a main component any one or more of silicon carbide, boron carbide, boron nitride, silicon nitride, and aluminum nitride can be used.

As the silicon carbide sintered body, a sintering aid containing boron (B) and carbon (C) as sintering aids for the main component silicon carbide, or a sintering aid for the main component silicon carbide. As the agent, a sintered body containing alumina (Al ₂ O ₃ ) and yttria (Y ₂ O ₃ ) and fired at 1900 to 2200 ° C. can be used, and silicon carbide is mainly composed of α-type, or Any of those mainly composed of β type may be used.

  The boron carbide sintered body is obtained by mixing 3 to 10% by weight of carbon as a sintering aid with boron carbide as a main component, and performing hot press firing at 2000 to 2200 ° C. be able to.

  In the boron nitride sintered body, 30 to 45% by weight of aluminum nitride and 5 to 10% by weight of rare earth element oxide are mixed as a sintering aid with respect to boron nitride as a main component, and 1900 to 2100. A sintered body can be obtained by hot-press firing at ° C. Another method for obtaining a sintered body of boron nitride is to mix and sinter borosilicate glass, but this is not preferable because the thermal conductivity is significantly reduced.

The silicon nitride sintered body is composed of 3 to 12% by weight of rare earth element oxide and 0.5 to 3% by weight of Al ₂ O ₃ as a sintering aid with respect to silicon nitride as a main component. A sintered body can be obtained by mixing SiO ₂ so that the amount of SiO ₂ contained in the bonded body is 1.5 to 5% by weight and performing hot press firing at 1650 to 1750 ° C. The amount of SiO ₂ shown here is the sum of SiO ₂ generated from impurity oxygen contained in the silicon nitride raw material, SiO ₂ as impurities contained in other additives, and SiO ₂ intentionally added. .

In addition, as the aluminum nitride-based sintered body, a rare earth element oxide such as Y ₂ O ₃ or Yb ₂ O ₃ as an auxiliary sintering agent and an alkaline earth such as CaO as necessary with respect to aluminum nitride as a main component It is obtained by adding a metal oxide, mixing sufficiently, processing it into a flat plate shape, and baking it at 1900-2100 ° C. in nitrogen gas.

  Further, the heat equalizing plate 2 is elastic by passing bolts 17 through the outer periphery of the heat equalizing plate 2 and the support 11 and screwing a nut 19 through an elastic body 8 and a washer 18 from the heat equalizing plate 2 side. It is fixed to. As a result, even when the temperature of the soaking plate 2 is changed or the temperature of the soaking plate 2 is fluctuated by placing a wafer on the mounting surface 3 and the support 11 is deformed, the elastic body 8 absorbs this. Thus, warpage of the soaking plate 2 can be prevented, and temperature distribution on the surface of the wafer W during heating of the wafer W can be prevented.

  The thermocouple 10 for adjusting the temperature of the soaking plate 2 is installed in the center of the soaking plate 2 in the vicinity of the wafer mounting surface 3, and the temperature of the soaking plate 2 is adjusted based on the temperature of the thermocouple 10. adjust. 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 resistors 5. As the thermocouple 10, it is preferable to use a sheath type thermocouple 10 having an outer diameter of 1.0 mm or less from the viewpoint of responsiveness and workability of holding. Further, the middle portion 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 soaking plate 2. The tip of the thermocouple 10 has a hole formed in the soaking plate 2 and is pressed and fixed to the inner wall surface of the cylindrical metal body installed therein by a spring material to improve the reliability of temperature measurement. Therefore, it is preferable.

  Further, when the heating resistor 5 is divided into a plurality of blocks, it is preferable to install a thermocouple 10 for temperature control at the center of each block and control the temperature independently of each other.

  As shown in FIG. 3, the holding structure of the thermocouple 10 is formed by forming a recess 27 on the main surface of the heat equalizing plate 2 on the side where the heating resistor 5 is formed, and the thermocouple 10 is formed in the recess 27. In order to improve the reliability of temperature measurement, the thermocouple 10 is installed through the metal foil 23 having a thermal conductivity of 65 W / (m · K) or more, and the thermal conductivity is 40 from that of the soaking plate 2 from above. It is preferable to have a structure in which the metal tip 22 ˜170%, the holding jig 24 having a thermal conductivity of 50 W / (m · K) or less, and the support rod 25 are pressed and fixed by the elastic body 26. The diameter of the recess 27 is preferably 3 to 5 mmφ.

  The support 11 is composed of a plate-like structure 13 and a side wall, and the plate-like structure 13 is provided with a conduction terminal 7 for supplying power to the heating resistor 5 through an insulating material 9 and is not used. The illustrated air injection port and thermocouple holding part are formed. The conduction terminal 7 is configured to be pressed against the power feeding unit 6 by the elastic body 8. The plate-like structure 13 is composed of a plurality of layers.

  Further, the connection between the power feeding portion 6 and the conduction terminal 7 formed on the heat equalizing plate 2 is set to contact by pressing, so that the difference in expansion between the heat equalizing plate 2 and the support 11 due to the temperature difference between the two portions is contacted. Therefore, it is possible to provide a wafer heating apparatus with good durability against the thermal cycle during use. As the elastic body 8 as the pressing means, a coiled spring as shown in FIG. 1 or a plate spring or the like may be used for pressing.

  The pressing force of the elastic body 8 may be such that a load of 0.3 N or more is applied to the conduction terminal 7. The reason why the pressing force of the elastic body 8 is 0.3 N or more is that the conduction terminal 7 must move in response to the dimensional change due to the expansion and contraction of the heat equalizing plate 2 and the support body 11. The upper conductive terminal 7 is pressed against the power feeding portion 6 from the lower surface of the heat equalizing plate 2, so that the conductive terminal 7 is prevented from separating from the power feeding portion 6 due to friction with the sliding portion of the conductive terminal 7. is there.

  Moreover, it is preferable that the diameter of the contact surface side with the electric power feeding part 6 of the conduction terminal 7 shall be 1.5-4 mm. Furthermore, as the insulating material 9 for holding the conductive terminal 7, a PEEK (polyethoxyethoxyketone resin) material in which glass fibers are dispersed can be used at a temperature of 200 ° C. or lower depending on the use temperature. In addition, when used at a temperature higher than that, it is possible to use a ceramic insulating material 9 made of alumina, mullite or the like.

  At this time, it is preferable that at least the contact portion of the conduction terminal 7 with the power feeding portion 6 is formed of a metal composed of at least one of Ni, Cr, Ag, Au, stainless steel, and platinum group metals. Specifically, the conductive terminal 7 itself can be formed of the above metal, or a coating layer made of the metal can be provided on the surface of the conductive terminal 7.

  Alternatively, by inserting a metal foil made of the above metal between the conductive terminal 7 and the power feeding portion 6, it is possible to prevent contact failure due to oxidation of the surface of the conductive terminal 7 and to improve the durability of the soaking plate 2. It becomes.

  Further, if the surface of the conductive terminal 7 is subjected to brazing or sandblasting to prevent the contact from becoming a point contact by roughening the surface, the contact reliability can be further improved. The wafer heating device 1 is adjusted so that the temperature in the surface of the soaking plate 2 is uniform. However, the structure of the temperature of the soaking plate 2 and the support 9 is structurally different during heating and wafer replacement. It is not constant. Due to this temperature difference, the power feeding unit 6 and the conductive terminal 7 often come into contact with each other in a twisted positional relationship. Therefore, when these contact points are processed flat, contact with each other tends to occur and contact failure is likely to occur.

  In order to heat the wafer W by the wafer heating apparatus 1, the wafer W carried to the upper side of the mounting surface 3 by the unillustrated transfer arm is supported by the unillustrated lift pins, and then the lift pins 8 are lowered. Then, the wafer W is placed on the placement surface 3.

  Next, the power supply unit 6 is energized to cause the heating resistor 5 to generate heat, and the wafer W on the mounting surface 3 is heated via the insulating layer 4 and the heat equalizing plate 2. When the soaking plate 2 is formed of a silicon carbide sintered body, deformation is small even when heat is applied, and the plate thickness can be reduced, so that the temperature rise time until heating to a predetermined processing temperature and the predetermined processing temperature to room temperature. The cooling time until cooling to the vicinity can be shortened, the productivity can be increased, and the thermal conductivity of 80 W / (m · K) or more can be obtained. Joule heat can be transmitted quickly, and the temperature variation of the mounting surface 3 can be made extremely small.

Silicon carbide raw material is mixed with 3 wt% B ₄ C and 2 wt% carbon using an appropriate amount of binder and solvent, granulated, molded at a molding pressure of 100 MPa, and fired at 1900-2100 ° C in a non-oxidizing atmosphere. Thus, a disk-shaped silicon carbide sintered body having a thermal conductivity of 80 W / (m · K) and an outer diameter of 230 mm was obtained. Then, after both surfaces are ground, a heat treatment of 1200 ° C. × 1 hour is performed to form a film made of SiO ₂ , a 200 μm glass paste is printed on one surface, and a baking process is performed at 1000 ° C. An insulating layer 4 was formed. The glass had a coefficient of thermal expansion of 3.4 × 10 ⁻⁶ deg ⁻¹ .

  Table 1 shows the five-part blocks including the center part and the four-part blocks formed on the surface of the disc-shaped silicon carbide sintered body on which an insulating layer made of glass is formed, and the outer periphery is 90 degrees apart. A paste made of glass having a composition of Au, Ag, Au—Pt, Au—Pd, Au—Ag, Au—Pt and a working point of 750 ° C. is applied and baked at 750 ° C. to form the heating resistor 5. Formed.

  In addition, as the support 11, two plate-like structures 13 made of SUS304 having a thickness of 2.5 mm with an opening formed in 30% of the main surface are prepared, and five of them are in a predetermined position. The temperature adjusting thermocouple 10 and ten conduction terminals 7 were formed, and fixed to the side wall portion made of SUS304 by screwing to prepare the support 11. The thermocouple 10 was installed in the center portion of each heating resistor block with the structure shown in FIG.

  After that, the soaking plate 2 was stacked on the support 11 and the outer periphery thereof was screwed through the elastic body 8 to obtain the wafer heating apparatus 1 shown in FIG.

  A wafer W on which a thermocouple 10a for temperature measurement was fixed was placed on the mounting surface 3 of the wafer heating apparatus 1, and the temperature distribution in the wafer W surface was measured by the thermocouple 10a. The thermocouples 10a for measurement were installed at six equal points and a center at a radius half the radius of the wafer W.

  The wafer heating apparatus 1 thus prepared is held at 150 ° C. and adjusted so that the temperature distribution in the wafer W plane is within ± 0.5 ° C., and then the temperature is lowered to 50 ° C. to change the temperature distribution in the wafer W plane to ± The maximum value of the temperature distribution in the wafer W surface when the temperature was raised to 200 ° C. within 0.4 ° C. was evaluated. Five samples of each sample were prepared and the temperature distribution was confirmed.

The results are shown in Table 1.

  As shown in Table 1, as the heating resistor 5, No. 1 using Pt, Ag, Pd, and Pt alone having a resistance temperature coefficient exceeding 2000 ppm / ° C. In 1 to 5 and 12, the temperature variation at the time of rapid temperature increase was 10 ° C. or more. On the other hand, No. in which the temperature coefficient of resistance is 2000 ppm / ° C. or less. In 6-11 and 13-16, the temperature variation at the time of rapid temperature rise was less than 10 ° C., and it was found that good temperature distribution control was possible.

  Here, No. 1 of Example 1 is used. Using the samples Nos. 8 and 13 to 16, the resistance change after energizing each heating resistor 5 and heating to 350 ° C. and holding for 500 hours was confirmed.

The results are shown in Table 2.

  As shown in Table 2, No. 1 containing Ag or Pd. In 13 and 14, the resistance value increased by 0.5% or more compared to the initial value. This is presumably because Ag and Pd were partially oxidized in the durability test under test. On the other hand, as a heating resistor 5, an alloy of Au and Pt group metal was used. 8, 15, and 16 had very small resistance changes. It has been found that it is preferable to use a combination of two or more Au—Pt group metals as the heating resistor 5 used in an oxidizing atmosphere.

  Here, a method of adjusting the resistance value distribution of the heating resistor 5 was examined.

  Twenty samples in which the resistance value adjusting portion 5a in which the resistance value is adjusted to 1.5 times the target resistance value are formed in a part of the heating resistor pattern are the same as in the first embodiment. Made. As the paste for forming the resistor pattern 5 ', a paste in which the Au: Pt weight ratio was adjusted to 50:50 was used. Thereafter, the resistance value adjusting portion 5a is adjusted by repeatedly applying a resistance pattern 5 ′ for adjusting the resistance value within ± 3% with respect to the target resistance value using the same paste as the heating resistor 5. The resistance value of the heating resistor 5 was adjusted by baking at a temperature 10 ° C. lower than the baking condition of the heating resistor 5. Ten samples were prepared under each condition, and an average value of resistance value variations with respect to the target resistance value was defined as resistance value correction variation.

  Further, the same resistor pattern 5 is used by using five kinds of pastes that form a resistor pattern 5 'in which the specific resistance is increased by -10%, the same, 10%, 30%, and 50% as compared with the pattern of the heating resistor 5. The resistance value was adjusted by '. No. 7, the resistance value was adjusted using a resistor pattern 5 ′ prepared for transfer using a resistor paste with a 50% specific resistance adjusted. And the resistance value variation after baking was evaluated about each sample with respect to the resistance value adjustment target. In addition, resistance trimming data of laser trimming is shown for comparison. This is a part where the resistance value is adjusted to 2/3 of the target resistance value in a part of the heating resistor 5, the resistance value is adjusted by laser trimming, and the variation of the adjusted resistance value is investigated. did.

  Furthermore, the maximum value of the temperature distribution in the wafer surface when the temperature was rapidly raised by the same method as in Example 1 was evaluated.

  As for durability, a cycle in which the wafer temperature is raised from 50 ° C. to 300 ° C. over 3 minutes by self-heating of the heating resistor 5, held for 2 minutes, and then cooled to 50 ° C. or less within 5 minutes by forced air cooling. The durability test was repeated 1000 cycles, and the resistance change before and after the durability test was investigated.

The results are shown in Table 3.

  As shown in Table 3, the specific resistance of the paste forming the resistor pattern 5 ′ was adjusted to be −10% with respect to the specific resistance of the paste forming the heating resistor 5. 1 is not preferable because the resistance value correction variation is as large as 18%. On the other hand, No. 1 using a paste that forms a resistor pattern 5 ′ having a specific resistance adjusted higher than that of the heating resistor 5. Nos. 3 to 5 are No. using laser trimming. It was possible to adjust the resistance value variation within 6%, which is comparable to 7 and 8.

  In addition, a resistor pattern 5 ′ having a resistance value adjustment width set in advance was adjusted by transfer. No. 6 was able to be adjusted with a resistance value adjustment variation of 1%.

  As for the change in resistance value after the durability test, the laser trimmed No. Nos. 7 and 8 have the resistance values adjusted by repeatedly applying the paste forming the resistor pattern 5 'in spite of the change of the resistance value by 0.2 to 0.3%. Nos. 1 to 6 showed good durability with a resistance value change rate of 0.1% or less.

It is sectional drawing which shows the wafer heating apparatus of this invention. (A) is a partial enlarged plan view of the heating resistor of the wafer heating apparatus of the present invention, and (b) is a cross-sectional view thereof. It is a partial expanded sectional view of the wafer heating device of the present invention.

Explanation of symbols

1: Wafer heating device 2: Soaking plate 3: Placement surface 4: Insulating layer 5: Heating resistor 5 ': Conductive pattern 5a: Resistance value adjusting unit 6: Power feeding unit 7: Conducting terminal 8: Elastic body 10: Thermoelectric Pair 11: Support W: Semiconductor wafer

Claims (4)

Wafer heating with one main surface of a ceramic plate as a wafer mounting surface, an insulating layer made of glass having a thickness of 10 to 600 μm on the other main surface, and a heating resistor on the insulating layer In the apparatus, a resistance value distribution of the heating resistor is prepared by reducing a resistance value of a part of the heating resistor. Wafer heating with one main surface of a ceramic plate as a wafer mounting surface, an insulating layer made of glass having a thickness of 10 to 600 μm on the other main surface, and a heating resistor on the insulating layer An apparatus for heating a wafer, wherein a resistor pattern is overcoated on a part of the heating resistor. 3. The wafer heating apparatus according to claim 2, wherein a specific resistance of the resistor pattern to be overcoated is larger than a specific resistance of the heating resistor. The wafer heating apparatus according to claim 2, wherein the resistor pattern is formed by transfer.

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