JP2004200156A - Metal heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal heater in which a distance between a heated material of a semiconductor wafer or the like and a heating surface of the heater can be made constant, and the heated material of the semiconductor wafer or the like can be heated uniformly, because the flatness of the heating surface is secured. <P>SOLUTION: The metal heater is constituted of a plurality of metal plates and exothermic bodies, the exothermic bodies are pinched and maintained between the metal plates, and on the heating surface facing the heated material of the metal plates, corresponding to a region where the exothermic bodies are formed, a convex part for supporting the heated material is installed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

The present invention relates to a metal heater mainly used in a semiconductor industry, an optical industry, and the like.

2. Description of the Related Art In a semiconductor manufacturing and inspection apparatus including an etching apparatus, a chemical vapor deposition apparatus, and the like, a metal heater using a metal base material such as stainless steel or an aluminum alloy as a substrate has been conventionally used.
FIG. 5 is a cross-sectional view schematically showing a metal heater having a configuration conventionally used.

As described in Patent Document 1, the metal heater 50 is a heater in which a heating element in which a nichrome wire 52 is sandwiched between silicon rubbers 61 is wired on an aluminum plate 51 having a thickness of 15 mm.

JP-A-11-40330

However, the metal heater 50 having such a structure has the following problems.
The metal plate 51 used for the metal heater 50 had to have a certain thickness. The reason is that when the metal plate 51 is thin, the rigidity becomes small, so that the metal plate 51 receives pressure from the surroundings due to thermal expansion caused by heating, and the coefficient of thermal expansion between the support container 60 and the metal plate 51 is reduced. This is because the metal plate 51 is warped or bent due to the difference.
When such a warp or a bend occurs in the metal plate 51, the semiconductor wafer 59 placed on the metal plate is not heated uniformly, causing a variation in the temperature, Sometimes it was scratched.

However, when the thickness of the metal plate 51 is too large, the heat capacity of the metal plate 51 increases, and when the object to be heated is heated or cooled, the metal plate 51 is not affected by changes in the voltage or current applied to the heating element. There has been a problem that the temperature of the heating surface does not quickly follow, making it difficult to control the temperature.
Further, when the semiconductor wafer 59 is placed on the metal plate 51 and the temperature of the heating surface 51a of the metal plate 51 suddenly drops, the time required for returning the temperature to the original temperature (recovery time) becomes longer. However, there is a problem that productivity is reduced.
Further, in such a metal heater 50, when the temperature rises, there is an overshoot phenomenon in which the temperature temporarily deviates upward from the set temperature. When this overshoot occurs, the heating surface of the metal heater 50 is set. It took more time to reach the temperature.

Further, in the metal heater 50, as shown in FIG. 6, an appropriate number of support pins 58 are formed on the heating surface 51a of the metal plate 51 in accordance with the area where the heating element 65 is formed (the size of the semiconductor wafer 59). Since the semiconductor wafer 59 is not provided, the semiconductor wafer 59 is bent, and as a result, the distance between the semiconductor wafer 59 and the metal plate 51 greatly differs depending on the location of the semiconductor wafer 59. There was a problem that heating was not uniform.

With the recent increase in the diameter of semiconductor wafers and the like, a metal heater having a larger diameter has been required. However, as the diameter of the metal plate increases, the temperature distribution of the metal plate itself also varies. In addition to the above, the warpage, the bending, and the like also easily occur, and the above-mentioned temperature uniformity of the semiconductor wafer is further reduced.

In view of the above-described problems, the present inventor has excellent in-plane uniformity during transition, has a relatively short recovery time, and does not bend the object to be heated such as a semiconductor wafer during heating. As a result of intensive research aimed at obtaining a metal heater that can heat uniformly, a heating element is sandwiched between multiple metal plates and a heating element is formed on the heating surface of the metal plate facing the object to be heated. It has been found that the provision of the projections corresponding to the set regions allows the semiconductor wafer to be uniformly heated without causing bending of the semiconductor wafer, thereby completing the present invention.

That is, the metal heater of the present invention is a metal heater comprising a plurality of metal plates and a heating element, wherein the heating element is sandwiched between the metal plates, and the heating surface of the metal plate facing the object to be heated. Is provided with a convex portion for supporting an object to be heated, corresponding to a region where the heating element is formed.

The metal heater of the present invention has a plurality of metal plates, and the heater is sandwiched between these metal plates. In a metal heater having such a configuration, compared to a metal heater including only one metal plate and a heater provided on a surface opposite to a heating surface of the metal plate, a metal plate on a heating surface side of the heater is closer to the heating surface. Since the thickness can be made smaller than that of the one metal plate, an object to be heated such as a semiconductor wafer can be quickly heated, and the recovery time can be shortened.

Furthermore, in the metal heater according to the present invention, the convex portion for supporting the object to be heated is provided on the heating surface of the metal plate facing the object to be heated, corresponding to the region where the heating element is formed. In addition, the semiconductor wafer or the like to be heated hardly bends. For this reason, the distance between the semiconductor wafer or the like and the heating surface of the metal plate can be made constant, and the entire semiconductor wafer can be uniformly heated.

In the present invention, "corresponding to the area in which the heating element is formed, a convex portion for supporting the object to be heated is provided" means the size of the area in which the heating element of the metal plate is formed, This means that an appropriate number of protrusions are provided at appropriate positions on the heating surface of the metal plate according to the size of the semiconductor wafer to be heated.
The “area where the heating element is formed” is defined as the internal area of the smallest circle including the entire heating element pattern when the heating element pattern formed on the metal plate is vertically shifted to the heating surface of the metal plate. Means

When the diameter of the region where the heating element is formed is 250 mm or more and less than 300 mm, the number of the protrusions is preferably 6 or more. In such a case, if the number of the convex portions is less than 6, the interval between the convex portions becomes too wide, and the semiconductor wafer bends. As a result, the distance between the semiconductor wafer and the metal plate varies, and It becomes difficult to uniformly heat the entire wafer. When the diameter of the region where the heating element is formed is 200 mm or more and less than 250 mm, the number of the protrusions is desirably 5 or more. When the diameter of the region where the heating element is formed is 300 mm or more, 7 The above is desirable.

The upper limit of the number of protrusions provided on the heating surface of the metal plate is not particularly limited, but is preferably 20 or less when the diameter of the region where the heating element is formed is 250 mm or more and less than 300 mm. . This is from the viewpoint of avoiding the complexity of the manufacturing process, suppressing the manufacturing cost, and making the temperature of the heating surface more uniform. When the diameter of the region where the heating element is formed is 200 mm or more and less than 250 mm, the number of the projections is desirably 15 or less.

In addition, for the position where the convex portion is provided, for example, in a region that is a relatively outer peripheral portion of the metal plate, on the circumference of a concentric circle with the metal plate, a plurality of convex portions are provided at equal intervals, and An arrangement in which one support pin is provided at the center portion, a plurality of regions are provided on the circumference of a concentric circle with the metal plate, and on the circumference of a concentric circle which is the inner periphery thereof, in a region which is a relatively outer periphery of the metal plate. There is an arrangement in which support pins are provided at equal intervals, and one support pin is provided at the center of the metal plate.

Further, it is desirable that the positions at which the convex portions are provided are widely dispersed on the metal plate and provided at positions to be rotated with respect to the center. By providing the convex portion at such a position, when the semiconductor wafer is heated, the semiconductor wafer does not bend, the distance between the semiconductor wafer and the metal plate becomes uniform, and the semiconductor wafer can be heated uniformly. It is.
On the other hand, when the convex portions are unevenly distributed on the metal plate and / or are provided at irregular intervals, a portion having a large interval between the convex portions is formed, and the semiconductor wafer is bent at the portion. As a result, the distance between the semiconductor wafer and the metal plate becomes uneven, making it difficult to heat the semiconductor wafer uniformly.

In addition, for example, the convex portion has a concave portion formed on a heating surface of a metal plate, and a support pin is inserted and fixed in the concave portion, or a through hole is formed in the metal plate, and a support pin is formed in the through hole. It can be installed on the heating surface of the metal plate by inserting or fixing. In addition, the through hole for the support pin and the recess may be provided in combination.
By using such a method, the support pins can be relatively easily fixed to the metal plate.
Further, as a method of fixing the support pin to the concave portion, for example, a support pin having a head like a nail may be formed on a heating surface of a metal plate such that the head is on the metal plate side. A method of inserting a C-shaped spring into a concave portion formed of a columnar hollow portion, fitting the C-shaped spring around the support pin so as to abut the concave portion, and fixing the spring by the force of the spring is used.
By using such a method, the support pins are securely fixed without falling off from the metal plate.

As the metal heater of the present invention, the one in which the area where the heating element is formed has a diameter of 250 mm or more and six or more support pins are provided on the heating surface of the metal plate is optimal. It is preferable that at least one support pin is provided at the center of the area where the heating element is formed.

The shape of the support pin is desirably, for example, a spire having a conical tip, a spire having a pyramid shape, or a hemispherical shape. This is because, when the semiconductor wafer is placed on the support pins, the semiconductor wafer comes into point contact with the semiconductor wafer and no hot spot or the like is formed on the semiconductor wafer.

When the shape other than the tip of the support pin is cylindrical, the diameter is preferably 1 to 10 mm. If the thickness is less than 1 mm, the stable supporting performance of the support pins themselves may be impaired when the semiconductor wafer is mounted, and if it exceeds 10 mm, a hot spot or the like may be formed on the semiconductor wafer.
Further, the height of the columnar portion of the support pin is desirably 1 to 10 mm. If the thickness is less than 1 mm, the support pins may not be securely fixed to the heating surface of the metal plate. If the thickness exceeds 10 mm, the semiconductor wafer may not be heated uniformly.
Further, when the support pin has a shape having a head like a nail, it is desirable that the head has a shape and a size that can be fitted into the concave portion. If the head is too small compared to the size of the recess, the support pins will not be stable.

The support pins are desirably made of ceramic, and are preferably oxide ceramics such as alumina and silica in consideration of the point that thermal deformation is relatively small and that they are not easily worn on a silicon wafer, productivity, cost, and the like. desirable.

In the above-described metal heater, it is desirable that the support pins protrude from the heating surface of the metal plate at the same height. If the protruding heights of the support pins are all the same, when the semiconductor wafer is placed, the semiconductor wafer is parallel to the heating surface of the metal plate, and since all the support pins support the semiconductor wafer, there is a deflection. Does not occur. As a result, the distance between the semiconductor wafer and the metal plate becomes uniform, and the semiconductor wafer can be heated uniformly. On the other hand, when the protruding heights of the support pins are different, the semiconductor wafer is tilted, and the support pins having a low height do not come into contact with the semiconductor wafer, so that bending occurs. As a result, the distance between the semiconductor wafer and the metal plate varies, making it difficult to uniformly heat the semiconductor wafer.

The height at which the support pins protrude from the heating surface of the metal plate is preferably 5 to 5000 μm, that is, it is desirable to hold the object to be heated at a distance of 5 to 5000 μm from the heating surface of the metal plate. If it is less than 5 μm, the temperature of the semiconductor wafer becomes uneven due to the influence of the temperature distribution of the metal plate, and the wafer may come into contact with the metal plate. If the thickness exceeds 5000 μm, the temperature of the semiconductor wafer hardly rises, and particularly, the temperature of the outer peripheral portion of the semiconductor wafer decreases.
The object to be heated and the heating surface of the metal plate are more preferably separated from each other by 5 to 500 µm, and further preferably separated from 20 to 200 µm.

The diameter of the concave portion in which the support pin is provided and the through hole for the support pin is desirably 1 to 10 mm. If the thickness is less than 1 mm, the support pin cannot be securely fixed, and if it exceeds 10 mm, a cooling spot is generated.
Further, the depth of the concave portion is desirably 1 to 10 mm. If it is less than 1 mm, the support pin may be detached, and if it is more than 10 mm, a cooling spot is generated.

In the metal heater of the present invention, it is preferable that, of the plurality of metal plates, the thickness of the metal plate on the heating surface side of the heater is larger than the thickness of the metal plate on the opposite side.
When the thickness of the metal plate on the heating surface side is large, the heat capacity of the metal plate on the opposite side of the heating surface is relatively smaller than the heat capacity of the metal plate on the heating surface side. Therefore, accumulation of heat is less likely to occur in the metal plate on the opposite side of the heating surface than in the metal plate on the heating surface side. Therefore, even when a normal temperature silicon wafer is sequentially placed on the heating surface and continuous processing is performed, heat conduction from the metal plate on the opposite side to the heating surface to the metal plate on the heating surface hardly occurs, and, of course, Temperature change of the metal plate on the heating surface side due to an overshoot phenomenon caused by heat conduction from the metal plate on the side opposite to the heating surface to the metal plate on the heating surface side is also unlikely to occur. Therefore, the temperature control of the metal plate on the heating surface side is easy, and the heat treatment temperature can be kept constant.

The metal heater of the present invention may have a configuration in which another metal plate is attached to a heating element provided on a metal plate, that is, a configuration in which a heating element is sandwiched between two metal plates. A configuration in which a heating element is sandwiched between the above metal plates may be adopted.

When the metal heater of the present invention has three or more metal plates, the thickness of the metal plate on the heating surface side is the thickness of the metal plate existing above the uppermost heater (hereinafter, also referred to as the upper metal plate). That is, the thickness of the metal plate on the opposite side to the heating surface (hereinafter also referred to as a lower metal plate) refers to the total thickness of the metal plates existing below the uppermost heater.

Here, the configuration of a metal heater having three metal plates is shown in FIG. FIG. 4 shows only the metal plate and the heater.
In the case of the metal heater as shown in FIG. 4, the thickness of the upper metal plate means the thickness a of the metal plate A existing above the uppermost heater A, and the thickness of the lower metal plate is This refers to the sum of the thicknesses b + c of the metal plates B and C existing below the uppermost heater A. The thickness of the upper metal plate is preferably larger than the thickness of the lower metal plate. .

When the thickness of the upper metal plate is large, the heat capacity of the lower metal plate is relatively smaller than the heat capacity of the upper metal plate. Therefore, heat accumulation is less likely to occur in the lower metal plate than in the upper metal plate. Therefore, even when silicon wafers at room temperature are sequentially placed on the heating surface and continuous processing is performed, heat conduction from the lower metal plate to the upper metal plate hardly occurs, and, of course, the lower metal plate transfers to the upper metal plate. The temperature change of the upper metal plate due to the overshoot phenomenon caused by the heat conduction hardly occurs. Therefore, the temperature control of the upper metal plate is easy, and the heat treatment temperature can be kept constant.

Hereinafter, in the present specification, a metal heater having a configuration in which a heater is sandwiched between two metal plates will be mainly described.
In the metal heater of the present invention, the lower limit of the thickness of the upper metal plate is desirably 1 mm.
If the thickness of the upper metal plate is less than 1 mm, the distance between the heating element and the heating surface is too short, and the pattern of the heating element is reflected in the temperature distribution on the heating surface. In some cases, the object cannot be heated uniformly. On the other hand, when the thickness of the upper metal plate is in the above range, the object to be heated can be uniformly heated without the heating element pattern being reflected in the temperature distribution on the heating surface.
Further, when the thickness of the upper substrate is within the above range, the mechanical strength is excellent, and the metal plate does not warp or bend, so that the flatness of the heating surface can be more reliably ensured. .
More preferably, the lower limit of the thickness of the upper metal plate is 5 mm.

The upper limit of the thickness of the upper metal plate is desirably 50 mm. If the thickness of the upper metal plate exceeds 50 mm, it becomes difficult for the temperature of the heating surface of the metal plate to follow changes in the voltage or current applied to the heating element, and the object to be heated such as a semiconductor wafer is quickly heated. In some cases, and the time required to restore the reduced temperature when the semiconductor wafer is placed on the heating surface (recovery time) becomes longer, which leads to longer working time and lower productivity. May be connected.

In addition, in the above configuration, a desirable upper limit of the thickness of the lower metal plate is 50 mm, a desirable lower limit is 1 mm, a more desirable upper limit is 30 mm, and a more desirable lower limit is 3 mm.

Further, the ratio of the thickness of the upper metal plate to the thickness of the lower metal plate (thickness of the upper metal plate / thickness of the lower metal plate) is desirably 1 to 10. If it is less than 1, distortion may occur on the heating surface, and the object to be heated may not be heated uniformly. If it exceeds 10, the heat capacity of the upper metal plate becomes too large, and it may not be possible to quickly heat the object to be heated. Further, when the heat capacity of the upper metal plate becomes too large, the temperature difference between the outer peripheral portion and the inner peripheral portion increases, and the temperature uniformity of the heated surface may be reduced. In particular, the case where it exceeds 1 is optimal. This is because the heating surface in the steady state has excellent temperature uniformity.

In the metal heater of the present invention, a heater is sandwiched between the upper metal plate and the lower metal plate, and a heating element is formed inside the heater. It is desirable that it be divided into two or more.
When the circuit of the heating element is divided into two or more, it is possible to perform fine temperature control at the outermost periphery of the metal heater whose temperature is apt to decrease, and it is possible to suppress variations in the temperature of the metal heater.
Further, in the metal heater of the present invention, it is desirable that all of the plurality of metal plates and the heater have the same diameter. This is because heat from the heater can be uniformly transmitted to the heating surface of the metal plate.
In the case where a heat insulating ring or the like is provided between the metal plate and the support container, the diameters of the metal plates may be different from each other.

In the metal heater of the present invention, the diameter of the metal plate is desirably 200 mm or more. This is because the larger the diameter of the metal heater, the more likely the temperature of the semiconductor wafer becomes non-uniform during heating, and the configuration of the present invention functions effectively. In addition, a substrate having such a large diameter can mount a large-diameter semiconductor wafer.
The metal plate preferably has a diameter of 12 inches (300 mm) or more. This is because it will become the mainstream of next generation semiconductor wafers.

It is desirable that the metal plate constituting the metal heater of the present invention has a flatness on the surface of 50 μm or less. When a semiconductor wafer is heated using the metal heater of the present invention, the distance between the semiconductor wafer and the metal plate can be made substantially constant, so that the entire semiconductor wafer is heated so as to be uniform. Can be.
More preferably, the metal plate has a flatness of 30 μm or less on its surface.
In addition, in this specification, flatness shall mean the difference between the highest part and the lowest part on the surface of a metal plate.

In order to realize such a metal heater having excellent flatness, it is necessary to prevent the metal plate from being bent due to pressure from the side surface when the metal plate thermally expands. For this reason, it is desirable to secure a space so that the side surface of the metal plate and the support container (bottom plate) do not adhere to each other.

In the present invention, it is desirable that the plurality of metal plates be made of the same material. In addition, the material of these metal plates is preferably excellent in thermal conductivity, high in rigidity, and hardly deformed even when thermally expanded, and more excellent in flatness when the processing of the metal plate itself is completed. It is desirable to have

As the material of the metal plate constituting the metal heater of the present invention, for example, aluminum, aluminum alloy, copper, copper alloy, stainless steel, inconel, steel and the like can be used. Among these, aluminum alloy is preferable. , An aluminum-copper alloy is more desirable. Aluminum-copper alloys have high mechanical strength, and therefore do not warp or warp due to heating even when the thickness of the metal plate is reduced. Therefore, the metal plate can be made thin and light. In addition, since an aluminum-copper alloy is also excellent in thermal conductivity, when used as a metal plate, the temperature of the heating surface can be quickly followed in accordance with the temperature change of the heating element. That is, the temperature of the heating surface of the upper metal plate can be controlled by changing the voltage and the current value to change the temperature of the heating element.

In addition to aluminum and copper, magnesium, manganese, silicon, zinc, and the like may be added to the aluminum-copper alloy. This is because various functions such as workability, corrosion resistance, and low expansion property can be improved.

When aluminum, an aluminum alloy, or the like is used as the material of the metal plate, it is desirable that the surface of the metal plate be subjected to alumite treatment. The alumite treatment refers to a treatment in which an aluminum or aluminum alloy is subjected to an electrochemical treatment (anodized film treatment) to form a thin film of aluminum oxide on the surface.
By performing such a treatment, the corrosion resistance of the metal plate is improved, and the surface is hardened, so that the metal plate is hardly damaged. Further, even when the metal plate is used in an actual semiconductor manufacturing / inspection process, the metal plate is less likely to be corroded by a resist solution, a corrosive gas or the like.
Further, by performing the anodic oxide film treatment at a lower temperature, a higher voltage, and a higher current density than the ordinary alumite treatment, a hard alumite treatment can be performed. In such a hard alumite treatment, a harder and thicker film can be obtained.
The thickness of the coating is preferably 1 μm or more, but the thickness of the coating can be 3 μm or more in the hard alumite treatment.

In the metal heater according to the present invention, it is desirable that the outer edge of the region where the heating element is formed is located at a position within 25% of the diameter of the metal plate from the outer periphery of the metal plate. Usually, in the outer peripheral portion of the metal plate, heat is generated from the outer edge portion of the metal plate, so that the temperature is lower than that of the central portion of the metal plate. As a result, the temperature of the heating surface is likely to be non-uniform. In the metal heater, since the heating element is also provided in such an outer peripheral portion, the object to be heated, such as a semiconductor wafer, can be uniformly heated without a temperature variation.

Further, it is desirable that the heating element is divided into two or more.
This is because, when the heating element is divided into two or more, by separately controlling the temperature of each heating element, the temperature of the heating surface can be made more uniform. Specifically, for example, by making the heating element pattern formed on the outermost periphery into a complicatedly divided pattern, it becomes possible to perform fine temperature control on the outermost periphery of the metal heater, which is apt to decrease in temperature, Variations in the temperature of the heating surface can be suppressed.

In the metal heater of the present invention, a wafer guide ring may be provided on a side surface of the metal plate or on an outer edge or surface of a heating surface of the metal plate.
When the above-mentioned metal heater is used by attaching it to a supporting container, for example, an airflow which flows from the side of the metal plate toward the semiconductor wafer placed on the metal heater is generated, and this airflow causes the uniformity of the temperature of the semiconductor wafer. However, by providing the above-mentioned wafer guide ring, the airflow flowing toward the semiconductor wafer can be prevented, so that the temperature uniformity of the semiconductor wafer can be further ensured.

Further, the metal heater of the present invention can be used for a heater module or the like by fixing an optical waveguide such as quartz. At this time, the optical waveguide can be supported by the projection.

The metal heater of the present invention comprises a single metal plate, and heats an object to be heated such as a semiconductor wafer more quickly than a metal heater in which a heater is provided on a surface opposite to a heating surface of the metal plate. be able to.

Furthermore, in the metal heater according to the present invention, the convex portion for supporting the object to be heated is provided on the heating surface of the metal plate facing the object to be heated, corresponding to the region where the heating element is formed. In addition, the semiconductor wafer or the like to be heated hardly bends. For this reason, the distance between the semiconductor wafer or the like and the heating surface of the metal plate can be made constant, and the entire semiconductor wafer can be uniformly heated.

The metal heater according to the present invention is a metal heater including a plurality of metal plates and a heating element, wherein the heating element is sandwiched between the metal plates, and a heating surface of the metal plate facing an object to be heated is provided. A projection for supporting an object to be heated is provided corresponding to a region where the heating element is formed.

As an example of the metal heater of the present invention, a metal heater having a configuration in which a heater is sandwiched between two metal plates will be described with reference to the drawings.
FIG. 1A is a cross-sectional view schematically showing such a metal heater, and FIG. 1B is a foil for joining a heating element and a conductive wire in the metal heater shown in FIG. 1A. It is a figure which shows typically the method of joining by caulking through. FIG. 2 is a plan view of the metal heater shown in FIG. FIG. 3 is a horizontal sectional view schematically showing a heater which is a part of the metal heater shown in FIG. In FIG. 2, the heating element is shown by a broken line.

In this metal heater 10, a heater 12 is sandwiched between a disc-shaped upper metal plate 11 and a lower metal plate 21, and the upper metal plate 11, the heater 12, and the lower metal plate 21 are fixed to the metal plate. It is configured to be fixed and tightened by screws 17 so that the heat of the heater 12 is transmitted well to the upper metal plate 11.
Further, the thickness of the upper metal plate 11 is larger than the thickness of the lower metal plate 21. Therefore, as described above, the flatness of the heating surface is ensured, the temperature of the heating surface becomes uniform, and the object to be heated can be uniformly heated.
Further, since the metal plate is fixed with the metal plate fixing screw 17, the substantial thickness of the metal plate is increased, so that the flatness of the heating surface is further improved.

In the metal heater 10, a support pin 18 having a head like a nail is inserted into a concave portion 28 formed of a columnar cavity formed on the upper metal plate 11, and a C-shaped spring 27 is attached to the support pin 18. The support pin 18 is fixed to the heating surface 11 a of the upper metal plate 11 by fitting the surrounding 18 into contact with the recess 28.
In the present embodiment, the support pins are installed on the heating surface of the metal plate by using the means shown in FIG. 1, but the means for installing the support pins on the heating surface of the metal plate are as shown in FIG. The present invention is not limited to the illustrated means. For example, a method of screwing a support pin having a screw portion into a concave portion having a thread groove may be used.
Further, as shown in FIG. 2, the heating surface 11 a of the upper metal plate 11 is provided on the heating surface 11 a of the upper metal plate 11 in a relatively outer peripheral region with eight pieces on the circumference of a circle concentric with the upper metal plate 11. A total of nine support pins 18 are provided at the center of the metal plate 11. In order to prevent the semiconductor wafer 19 from bending, the support pins on the same circumference are provided at equal intervals.

The upper metal plate 11, the heater 12, and the lower metal plate 21 fixed by the metal plate fixing screws 17 are supported by a support plate 25 provided on the bottom surface of a cylindrical support container 20 having a bottom. The portion other than the portion that is in contact with the support container 20 does not contact the support container 20. A heat shield plate 23 for shielding heat is provided below the support container 20.

In the metal heater 10 of the present invention, by adopting the above structure, it is possible to realize a flatness of 50 μm or less on the heating surface 11 a of the upper metal plate 11. By realizing such flatness, when heating the semiconductor wafer, the distance between the semiconductor wafer and the metal plate can be made substantially constant, and the semiconductor wafer is heated so as to have a uniform temperature. be able to.
In the metal heater 10 of the present invention, a wafer guide ring 26 or a barrier ring 32 may be provided at the peripheral portion of the heating surface 11a in order to prevent a change in temperature due to inflow of gas from the periphery. .

The metal heater 10 of the present invention differs from the metal heater 50 shown in FIGS. 5 and 6 in the following points.

First, as described above, in the metal heater 10, a total of nine support pins 18 are provided on the heating surface 11a of the upper metal plate 11, whereas in the metal heater 50, the heating of the metal plate 51 is performed. The difference is that the number of support pins 58 provided on the surface 51a is five in total. Therefore, in the metal heater 10, since the interval between the support pins 18 is small, the semiconductor wafer 19 is unlikely to be bent. Therefore, the distance between the semiconductor wafer 19 and the heating surface 11a of the upper metal plate 11 can be made constant, and the entire semiconductor wafer 19 can be uniformly heated.

Further, the metal heater 10 has the side surfaces of the upper metal plate 11, the heater 12, and the lower metal plate 21 that are not in close contact with the support container 20 and are fixed in a non-contact state, and also support the lower metal plate 21. It is not in direct contact with the bottom surface of the container 20 and is supported by the support plate 25. As described above, by making the side surfaces of the upper metal plate 11, the heater 12, and the lower metal plate 21 not contact with the supporting container 20, the upper metal plate 11 is prevented from bending due to compression from the side surface when thermally expanded. can do. In addition, the upper metal plate 11, the heater 12, and the lower metal plate 21 are supported only through the support plate 25, and are not in contact with other parts. Compared to the case where the side surfaces of the plate 11, the heater 12, and the lower metal plate 21 are in close contact with the support container 20, heat is less escaping from the metal plate and the like, and the object to be heated can be heated quickly. In this case, the air layer functions as a heat insulating layer.
Note that the upper metal plate 11, the heater 12, the lower metal plate 21, and the like may be directly mounted on the bottom surface of the support container 20 without providing the support plate 25 on the bottom surface of the support container 20.

In some cases, it is necessary to rapidly cool the upper metal plate 11, the heater 12, and the lower metal plate 21 after heating. For example, a cooling pipe or the like is connected to the bottom plate of the support container 20 to cool the air or the like. Can be quickly cooled by introducing the gas into the support container 20.

Further, in the metal heater 10, the metal plate fixing screw 17 does not penetrate the support container 20, but penetrates only the upper metal plate 11, the heater 12, and the lower metal plate 21, and fixes them. With such a configuration, it is possible to prevent deformation of the upper metal plate 11 due to a difference in coefficient of thermal expansion between the upper metal plate 11 and the support container 20, and to heat an object to be heated. In addition, heat is hardly dissipated from a metal plate or the like, and the object to be heated can be quickly heated.

Further, a heat shield plate 23 is provided at the bottom of the support container 20 so that heat from the upper metal plate 11 and the lower metal plate 21 can be prevented from being transmitted to the device.

A bottomed hole 14 is formed in the metal heater 10, and a temperature measuring element 16 for measuring the temperature of the upper metal plate 11 is embedded in the bottomed hole 14.

Further, in the metal heater 10, a support pin 18 having a spire-shaped tip is provided on a heating surface, and the semiconductor wafer 19 is supported via the support pin 18, so that the semiconductor wafer 19 is supported by the upper metal plate 11. It can be supported and heated with a certain distance from the heating surface.

The metal heater 10 is also provided with a through hole 15 that penetrates through the upper metal plate 11, the heater 12, the lower metal plate 21, and the support container 20, and a columnar lifter pin or the like is inserted into the through hole 15. Also, the semiconductor wafer 19 as an object to be heated can be supported while the semiconductor wafer 19 is supported at a predetermined distance from the heating surface 11a of the upper metal plate 11, and the semiconductor wafer 19 can be transferred.

The heater 12 is connected to the conductive wire 24. The conductive wire 24 is drawn out of the support container 20 and the through hole formed in the heat shield plate 23 to the outside, and connected to a power source or the like (not shown). I have.
In the metal heater 10 shown in FIG. 1, a through hole is formed in the lower metal plate 21, and the conductive wire 24 is inserted into the through hole. It may be connected to a heating element installed inside the heater.

In the metal heater 10, the upper metal plate 11, the heater 12 and the lower metal plate 21 are fixed by metal plate fixing screws 17. The metal plate fixing screw 17 is attached so as to penetrate the heater 12 and the lower metal plate 21 but not to penetrate the upper metal plate 11.
As described above, when the upper metal plate 11 and the like are fixed by the metal plate fixing screw 17, the length of the portion of the metal plate fixing screw 17 inserted into the upper metal plate 11 is three times the thickness of the upper metal plate. / 4 or less is desirable.
When the length of the portion of the metal plate fixing screw 17 inserted into the upper metal plate 11 is longer than ３ of the thickness of the upper metal plate 11, of the heating surface of the metal plate, The temperature of the portion immediately above becomes higher than the surrounding temperature, and the object to be heated may not be heated uniformly.

As shown in FIG. 3, the heater 12 has a circular shape in plan view like the upper metal plate 11 and the lower metal plate 21 so that the temperature of the entire heating surface 11 a of the upper metal plate 11 becomes uniform. Heaters 25a and 25b each having a closed circuit are arranged inside the heater 12 for heating.

As for the heater 12, a heating element 25b composed of a pattern in which a bent line is repeatedly formed in an annular shape on the outer peripheral portion of the heater 12 to form a closed circuit is arranged, and the heating element 25b is repeatedly formed so as to draw a part of a concentric circle. A heating element 25a composed of a pattern on which a circuit is formed is arranged.
Further, although not shown, the heater 12 has a configuration in which the heating element 25 is sandwiched and fixed by two mica plates 26, and the heating element 25 heats the mica plate 26 during energization, The object to be heated can be heated by the secondary radiation of the mica plate 26.

In the metal heater 10 of the present invention, it is preferable that the outer edge of the heating element 25 formed inside the heater 12 be located at a position within 25% of the diameter of the metal plate 11 from the outer periphery of the metal plate 11. Usually, in the outer peripheral portion of the metal plate 11, the temperature tends to be uneven due to heat radiation from the surface of the outer peripheral portion of the metal plate 11, but in the metal heater 10 of the present invention, a heating element is also provided in such an outer peripheral portion. This is because the semiconductor wafers and the like to be heated can be uniformly heated without variation in temperature.

Next, the material and the shape of the metal heater constituting the present invention will be described in more detail.

In the metal heater of the present invention, the metal plate is provided with a bottomed hole from the side opposite to the heating surface on which the object to be heated is placed toward the heating surface, and the bottom of the bottomed hole is relatively positioned relative to the heating element. It is desirable to form it near the heating surface, and to provide a temperature measuring element (not shown) such as a thermocouple in the hole with the bottom.

Further, the distance between the bottom of the bottomed hole and the heating surface is preferably 0.1 mm to 1/2 of the thickness of the metal plate.
Thereby, the temperature measurement location is closer to the heating surface than the heating element, and the temperature of the semiconductor wafer can be measured more accurately.

If the distance between the bottom of the bottomed hole and the heating surface is less than 0.1 mm, heat is dissipated and a temperature distribution is formed on the heating surface. If the thickness exceeds half of the thickness, the temperature is affected by the temperature of the heating element. This is because temperature control becomes impossible and temperature distribution is formed on the heating surface.

The diameter of the bottomed hole is desirably 0.3 mm to 5 mm. This is because if it is too large, the heat dissipation will be large, and if it is too small, the workability will be reduced, making it impossible to equalize the distance to the heating surface.

Examples of the temperature measuring element include a thermocouple, a platinum temperature measuring resistor, a thermistor, and the like.
Examples of the thermocouple include K-type, R-type, B-type, S-type, E-type, J-type, and T-type thermocouples as described in JIS-C-1602 (1980). Of these, a K-type thermocouple is preferred.

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

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

As the above-mentioned gold solder, 37-80.5% by weight Au-63-19.5% by weight Cu alloy, 81.5-82.5% by weight: Au-18.5-17.5% by weight: Ni alloy At least one selected is desirable. These are because the melting temperature is 900 ° C. or higher and it is difficult to melt even in a high temperature region.
As the silver solder, for example, an Ag-Cu-based one can be used.

As the heater, a mica heater, a silicon rubber heater, or the like as shown in FIG. 3 can be used. Further, a heater in which a heating wire is simply formed on an insulating seal can be used as a heater.
As the mica heater, a heater in which a heating element such as a nichrome wire formed in an arbitrary pattern is sandwiched between mica plates, which are insulators, can be used.
Further, as the above-mentioned silicon rubber heater, a heater in which a heating element such as a nichrome wire formed in an arbitrary pattern is sandwiched by silicon rubber as an insulator can be used.

The heating element for heating the heater is not limited to the above-described nichrome wire, but may be another metal wire such as a tungsten wire or a molybdenum wire, as long as it generates heat when a voltage is applied. .
Further, as the heating element, a metal foil can be used in addition to the metal wire. As the above-mentioned metal foil, it is desirable to use a nickel foil or a stainless steel foil as a heating element by forming a pattern by etching or the like. The patterned metal foil may be bonded with a resin film or the like.
Furthermore, the insulator covering the heating element is also not limited to the above-described mica plate and silicon rubber as long as it can prevent short circuit and can withstand high temperatures. , Polybenzimidazole (PBI) or the like, or a mat-like fiber made of ceramic or the like may be used.

When the metal heater has a shape in which the heater is sandwiched between metal plates, a plurality of the heaters may be provided. In this case, it is desirable that the heating elements are formed in some layers so that the patterns of the respective layers complement each other, and that when viewed from above the heating surface, the patterns are formed in any regions. As such a structure, for example, there is a structure in which the staggered arrangement is provided.

Further, the pattern of the heating element in the metal heater of the present invention is not limited to the pattern shown in FIG. 3, and for example, a concentric pattern, a spiral pattern, an eccentric pattern and the like can be used. . Further, a pattern in which these are combined may be used.
Further, it is desirable that the heating element is divided into two or more as described above.

The area resistivity of the heating element is preferably 0.1 to 10 Ω / □. If the sheet resistivity exceeds 10Ω / □, the diameter of the heating element must be made very small in order to secure a desired heating value. It fluctuates. Further, when the sheet resistivity is less than 0.1 Ω / □, the heat generation amount cannot be secured unless the diameter of the heating element is increased, as a result, the degree of freedom of the heating element pattern design is reduced, and the temperature of the heating surface is reduced. It is difficult to make the uniformity.

As a means for connecting the heating element and the power source, as shown in FIG. 1, a part of the heating element made of metal foil is exposed to form a connection foil, and one end of the conductive wire is wrapped by the connection foil. A mounting member having a caulking portion may be attached to the portion, and the connection may be performed by caulking the caulking portion.A conductive wire may be attached to both ends of the heating element with solder or the like, and a power source or the like may be connected via the conductive wire. A terminal may be attached to both ends of the heating element, and the terminal may be connected to a power source or the like via the terminal.
Further, it is desirable that the terminal is attached to the heating element by soldering, brazing material, pressure bonding, caulking, or the like. The reason that it is desirable to attach the terminals via solder is because nickel prevents the thermal diffusion of the solder. Examples of the connection terminal include an external terminal made of Kovar.

When connecting the connection terminals, alloys such as silver-lead, lead-tin, and bismuth-tin can be used as the solder. Note that the thickness of the solder layer is preferably 0.1 to 50 μm. This is because the range is sufficient to secure connection by soldering.

In the metal heater of the present invention, an intermediate plate may be provided between the metal plate and the heater. By providing such an intermediate plate, the heat generated by the heating element can be transmitted to the metal plate in a more uniform state. As the material of the middle plate, a metal having excellent heat conductivity is desirable, and for example, copper, a copper alloy, or the like can be used.

Further, in the metal heater shown in FIG. 1A, the side surface of the metal plate and the supporting container are not in contact with each other. It is desirable to provide an insulating ring between the supporting container and the supporting container. Dissipation of heat at the outer peripheral portion of the metal plate can prevent temperature variations on the heating surface of the metal plate.

The support container and the heat shield plate may be integrated, and the heat shield plate may be connected and fixed to the support container, but the support container and the heat shield plate are integrally formed. It is desirable. This is because the strength of the entire metal heater can be secured.

Preferably, the support container has a cylindrical shape, and the heat shield plate has a disk shape.
Further, it is desirable that the thickness of the support container and the heat shield plate is 0.1 to 5 mm. If the thickness is less than 0.1 mm, the strength is poor, and if it exceeds 5 mm, the heat capacity increases.

The supporting container and the heat shield plate are made of SUS, aluminum, inconel (a nickel-based material containing 16% of chromium and 7% of iron so as to be easily processed and have excellent mechanical properties, and to secure the strength of the entire metal heater. It is desirable to be composed of a metal such as
When the support container and the heat shield plate are not integrated, as the heat shield plate, for example, a heat-resistant resin, a ceramic plate, a heat-resistant organic fiber, It is also possible to use a material having a low thermal conductivity and excellent heat resistance, such as a composite plate mixed with a resin or an inorganic fiber.

Further, a refrigerant introduction pipe may be attached to the support container or the heat shield plate. This is because the temperature of the metal heater can be rapidly lowered by introducing a forced cooling refrigerant or the like for cooling the metal heater. Further, the support container or the heat shield plate may be provided with a through hole for discharging the introduced forced cooling refrigerant or the like.

Next, as an example of a method for manufacturing a metal heater according to the present invention, a method for manufacturing a metal heater 10 shown in FIG. 1A will be described.

(1) Step of preparing metal plate A plate made of aluminum-copper alloy or the like is subjected to outer diameter processing using an NC lathe to form a disk, and then the plate is subjected to end face processing, surface processing, and back surface processing. Processing is performed in order.
At this time, it is desirable that the thickness of the plate-shaped body serving as the upper metal plate be larger than the thickness of the plate-shaped body serving as the lower metal plate. In the present invention, the upper metal plate and the lower metal plate are made of the same material.

Next, using a machining center (MC) or the like, a portion to be a through hole for inserting a lifter pin for supporting a semiconductor wafer, a concave portion for installing a support pin, and a device for embedding a temperature measuring element such as a thermocouple. A portion that becomes a bottomed hole is formed. Similarly, after a bottomed hole is formed at a predetermined position, a screw groove is formed in the bottomed hole to form a screw hole for inserting a screw for fixing a metal plate.

The recesses for installing the support pins are formed such that the support pins are widely dispersed on the metal plate and are arranged at equal intervals. For example, as shown in FIG. 2, a plurality of support pins are provided at equal intervals on the circumference of a concentric circle with the metal plate, and one support pin is provided at the center of the metal plate. Can be mentioned. Accordingly, when the semiconductor wafer is heated, the semiconductor wafer does not bend and the distance between the semiconductor wafer and the metal plate becomes uniform, so that the semiconductor wafer can be heated uniformly.

Then, the upper metal plate and the lower metal plate are manufactured by subjecting the plate-shaped body serving as the upper metal plate to a surface grinding treatment using a rotary grinder. By performing this surface grinding treatment, the flatness of the surface of the metal plate can be reduced to about 20 to 30 μm.
Further, a wafer guide ring for suppressing the flow of the atmospheric gas may be formed on the side surface of the upper metal plate or on the outer edge or surface of the heating surface of the metal plate, if necessary. The wafer guide ring can be formed of, for example, an aluminum-copper alloy, SUS, or the like. For the same purpose, a barrier ring may be provided at the top of the support container.
By providing the wafer guide ring and the barrier ring, the flow of the atmospheric gas inside and outside the heating region is hindered, and as a result, the object to be heated can be heated uniformly.

Next, an alumite treatment is performed on the upper metal plate and the lower metal plate to form an oxide film on the surfaces of the upper metal plate and the lower metal plate. By performing such a treatment, the corrosion resistance of the metal plate is improved, and the surface is hardened, so that the metal plate is hardly damaged. Further, even when the metal plate is used in an actual semiconductor manufacturing / inspection process, the metal plate is less likely to be corroded by a resist solution, a corrosive gas, or the like.
As the alumite treatment (anodized film treatment), for example, a sulfuric acid method, an oxalic acid method, or the like can be used. However, it is preferable to use an oxalic acid method because generation of surface pinholes can be prevented.

(2) Installation of heater A heater in which a heating element such as a nichrome wire, a metal foil, or a stainless steel foil processed into a predetermined pattern is sandwiched between ceramic plates such as mica is installed between an upper metal plate and a lower metal plate. After the screw for fixing the metal plate is inserted into the screw hole provided in the heater, the screw is tightened to integrate the lower metal plate and the heater.
In addition, since it is necessary for the heating element to make the entire heater have a uniform temperature, it is preferable to form a pattern based on the repetition such that the bent line repeats in an annular shape or draws a part of a concentric circle.
Further, a middle plate made of a material having excellent thermal conductivity such as copper may be sandwiched between the metal plate and the heater. Thereby, the heat radiated from the heater can be transmitted to the upper metal plate in a more uniform state.

(3) Attachment of support container Then, the integrated metal plate and heater are placed on a support plate 25 of a cylindrical support container as shown in FIG. I do.
In addition, a heat shield plate made of the same material as the support container is installed on the bottom surface of the support container, and a through hole is formed in the support container so that a temperature measuring element, a conductive wire, or the like can be inserted therethrough.

In the metal heater of the present invention, as shown in FIG. 1A, it is desirable that the side surface of the metal plate and the heater and the supporting container are supported and fixed in a non-contact state.
This is because heat may escape from the side surfaces of the metal plate and the heater, and the temperature of the outer peripheral portion of the heating surface of the metal plate may become low.
When the metal plate and the side surfaces of the heater and the support container are supported and fixed in contact with each other, a heat insulating ring made of polyimide resin, fluororesin, or the like is provided between the metal plate and the support container. It is desirable.

(4) Connection to power supply, etc. Terminals (external terminals) for connection to the power supply are attached to both ends of the heating element provided in the heater with solder, brazing material, or by crimping, screwing, caulking, or the like. Attach using a mechanical attachment method (attachment means) and connect to an external power supply or the like. Then, after inserting the support pins into the concave portions formed on the heating surface of the metal plate, the support pins are fixed using a spring or the like, and the manufacture of the metal heater is completed.

Hereinafter, the present invention will be described in more detail with reference to Examples.
In the present embodiment, a metal heater for heating a semiconductor wafer is shown as an example, but the present invention can also be used as a heater for adjusting the temperature of an optical waveguide.

(Example 1)
Manufacture of metal heaters (see FIGS. 1 (a), 1 (b) and 2) (1) NC lathe (manufactured by Washino Machine Co., Ltd.) on a plate made of aluminum-copper alloy (A2219 (JIS-H4000)) After the outer diameter is processed by using to obtain a disk shape, the disk body is subjected to an end face processing, a surface processing, and a back surface processing, thereby forming a disk body for the upper metal plate and a disk for the lower metal plate. Body manufactured.

Next, using a machining center (manufactured by Hitachi Seiki Co., Ltd.), a portion serving as a through hole 15 for inserting a lifter pin for supporting the semiconductor wafer 19 into these discs, and a concave portion 28 for installing a support pin 18. And a portion to be the bottomed hole 14 for embedding the temperature measuring element 16 were formed.
In addition, the part which becomes the through-hole 15 was formed in three places, and the part which became the recessed part 28 for installing the support pin 18 was formed in nine places. As shown in FIG. 1A, eight support pins are provided at regular intervals on the circumference of a circle concentric with the upper metal plate, and one support pin is provided at the center of the upper metal plate. Was set up so that it could be installed.

Similarly, after forming a bottomed hole or a through hole at a predetermined position, a screw groove is formed in the bottomed hole or the through hole, so that the metal plate fixing screw 17 is inserted into the disc body. Screw holes were formed.
A screw hole having a depth of ネ ジ of the thickness was formed in the upper metal plate and the plate.

(2) Next, the surface of the disk for the upper metal plate manufactured in the step (1) on the heating surface side is subjected to a surface grinding treatment using a rotary grinder (manufactured by Okamoto Machine Tool Works, Ltd.), An upper metal plate 11 having a thickness of 15 mm and a diameter of 330 mm and a lower metal plate 21 having a thickness of 5 mm and a diameter of 330 mm were obtained.

Further, a barrier ring for a wafer to be heated was provided on the side surface of the upper metal plate 11 by the following method.
That is, the barrier ring 32 was provided by increasing the height of the outer peripheral edge of the support container from the upper surface of the heating surface of the upper metal plate.
In this embodiment, the thickness of the upper metal plate 11 is larger than the thickness of the lower metal plate 21.

(3) Next, the upper metal plate 11 and the lower metal plate 21 are subjected to alumite treatment under the conditions of an electrolytic solution of 10% H ₂ SO ₄ , a voltage of 10 V, a current density of 0.8 A / dm ² and a liquid temperature of 20 ° C. An oxide film having a thickness of 15 μm was formed on the surfaces of the metal plate 11 and the lower metal plate 21.

(4) A heating element made of a stainless steel foil having a thickness of 200 μm and processed into a pattern in which the bending lines are repeated in an annular shape as shown in FIG. A heater 12 having a diameter of 330 mm was obtained by being sandwiched between two 0.3 mm mica plates.
The heater 12 was formed such that the diameter of the region where the heating element was formed was 320 mm, and the total number of circuits of the heating element was four.
The mica plate 26 is formed in advance with a portion serving as the through hole 15, a portion serving as the bottomed hole 14, and a portion serving as a screw hole for inserting the metal plate fixing screw 17.

Thereafter, the heater 12 is sandwiched between the upper metal plate 11 and the lower metal plate 21 manufactured in the steps (1) to (3), and the screw 17 for fixing the metal plate is inserted into the screw holes provided in the lower metal plate 21 and the heater 12. After insertion, the upper metal plate 11, the lower metal plate 21, and the heater 12 were integrated by tightening them.

(5) Next, a SUS support container 20 having a bottomed cylindrical shape as shown in FIG. 1A is manufactured, a support plate 25 is provided on the bottom surface of the support container 20, and the through hole 15 is formed. A portion serving as the bottomed hole 14 and a through hole for inserting the conductive wire 24 were formed, and then a disc-shaped heat shield plate 23 made of SUS was placed at the bottom of the support container 20.
Then, the heater 12 manufactured in (4) and the upper metal plate 11 to which the lower metal plate 21 is attached are placed via the support plate 25 inside the support container 20 in which the heat shield plate 23 is installed. The side surfaces of the metal plate 11, the heater 12, and the lower metal plate 21 and the support container 20 were firmly fixed so as to be in non-contact.

(6) After inserting the Pt temperature measuring element 16 composed of a Pt temperature measuring resistor for temperature control into the bottomed hole 14, the bottomed hole 14 is sealed with a sealing material (Aron Ceramic, manufactured by Toagosei Co., Ltd.). did. Also, alumina support pins 18 having a shape as shown in FIG. 1A are inserted into nine recesses 28 formed on the heating surface of the upper metal plate 11 to support the C-shaped spring 27. The pin 18 was fixed to the heating surface 11 a of the upper metal plate 11 by being fitted so as to be in contact with the surrounding recess 28.

(7) Next, the conductive wire 24 is wrapped by the stainless steel foil 30 for connection taken out of the stainless steel foil 29 which is a heating element provided on the heater 12, and these are caulked in a state where the mounting member 31 is fitted. Thus, the conductive wire 24 was attached to the stainless steel foil 30 for connection and connected to an external power supply or the like, and the metal heater 10 was obtained.

(Example 2)
Production of Metal Heater The thickness of the upper metal plate 11 was 20 mm, the thickness of the lower metal plate 21 was 5 mm, and the number of pins was one at the center and five on the same circumference around the center, for a total of six. A metal heater was manufactured in the same manner as in Example 1 except that the heating was performed.

(Example 3)
Manufacture of Metal Heater The thickness of the upper metal plate 11 was 25 mm, the thickness of the lower metal plate 21 was 10 mm, the number of pins was one at the center, six on the same circumference around the center, and A metal heater was manufactured in the same manner as in Example 1 except that a total of 19 pieces were formed on 12 pieces on the same circumference.

(Example 4)
Production of Metal Heater A metal heater was produced in the same manner as in Example 1, except that the thickness of the upper metal plate 11 was 40 mm and the thickness of the lower metal plate 21 was 5 mm.

(Example 5)
In the step (2) of the first embodiment, five concave portions for installing the support pins are formed on the heating surface side surface of the disk for the upper metal plate, and in the step (6), the upper metal plate is formed. A metal heater was manufactured in the same manner as in Example 1 except that the support pins were provided in the five concave portions formed on the heating surface of Example 1. In the fifth embodiment, a total of five support pins are provided on the heating surface of the upper metal plate, and four support pins are arranged at equal intervals on the circumference of a concentric circle with the upper metal plate. The arrangement was such that one support pin was provided at the center of the plate.

(Example 6)
The present embodiment employs a metal heater in the same manner as in the first embodiment, except that the heater is 220 mm in diameter, and the number of pins is one at the center and four on the same circumference around the pin, for a total of five pins. Manufactured.

(Example 7)
This example was implemented except that the heater was 220 mm in diameter, and the number of pins was one at the center, four around the center, and ten outside the center, each on the same circumference to make a total of fifteen. A metal heater was manufactured in the same manner as in Example 1.

(Test Example 1)
In this test row, a metal heater was manufactured in the same manner as in Example 1 except that the number of pins was one at the center, and three pins were arranged on the same circumference to make a total of four pins.

(Test Example 2)
In this test example, a metal heater was manufactured in the same manner as in Example 6, except that the number of pins was three at equal intervals on the circumference of a concentric circle with the upper metal plate.

(Test Example 3)
In the step (5) of the first embodiment, the support container 20 is manufactured by setting the inner diameter of the support container 20 to be substantially the same as the diameter (330 mm) of the upper metal plate 11, and the upper metal plate 11, the heater 12, and the lower metal plate 11 are assembled. A metal heater was manufactured in the same manner as in Example 1 except that the metal heater was installed inside the support container 20 and fixed so that the side surfaces thereof and the support container 20 were in close contact with each other.

(Comparative Example 1)
A metal heater having a copper middle plate and a heater installed on the bottom surface of a metal plate was manufactured. The thickness of the metal plate was 55 mm, the pattern of the heating element was the same as in Example 1, and no support pins were formed.

The temperature was raised by energizing the metal heaters according to Examples 1 to 4, Test Examples 1 to 3, and Comparative Example 1. (1) In-plane temperature uniformity during steady state, (2) In-plane temperature uniformity during transition Properties, (3) measurement of flatness, and (4) evaluation of the amount of overshoot. Table 1 shows the results.
In addition, each evaluation was performed using the following method.

(1) In-plane temperature uniformity during steady state After the temperature of the metal heater was raised to 140 ° C., a wafer with a temperature sensor equipped with a thermocouple was placed on the heating surface of the metal heater, and the temperature distribution of the heating surface was measured. . The temperature distribution is indicated by the maximum value of the temperature difference between the highest temperature and the lowest temperature during the temperature rise.

(2) In-plane temperature uniformity during transition The temperature distribution in the surface of the wafer with the temperature sensor when the wafer with the temperature sensor was heated from room temperature to 140 ° C. by the metal heater was measured. The temperature distribution is measured at 100 ° C., 120 ° C., and 130 ° C., and is indicated by the maximum value of the temperature difference between the highest temperature and the lowest temperature.
FIGS. 7 to 9 show the relationship between the temperature and time at each measurement point of the wafer with the temperature sensor when the measurement was performed using the metal heater according to the first embodiment. 10 to 12 show the relationship between the temperature and the time at each measurement point on the wafer with the temperature sensor when the measurement was performed.
7 and 10 show the relationship between temperature and time near 100 ° C., FIGS. 8 and 11 show the relationship between temperature and time near 120 to 130 ° C., and FIGS. 9 and 12 show the relationship between temperature and time near 140 ° C. Show the relationship.

(3) Measurement of flatness The metal heater was heated from room temperature to 140 ° C. At that time, the flatness of the heated surface of the upper metal plate at room temperature and 140 ° C. was measured using a laser displacement meter (manufactured by Keyence Corporation).

(4) Overshoot The amount of overshoot (the value obtained by subtracting the set temperature from the maximum temperature during processing) when 20 silicon wafers were processed at 140 ° C. was measured.
Regarding the evaluation of the flatness measurement of (3), FIG. 13 shows a three-dimensional shape of a part of the metal heater heating surface according to Example 1 at room temperature, and illustrates the metal heater heating surface according to Example 1 at 140 ° C. 14 is shown in FIG. 14, and the three-dimensional shape of a part of the metal heater heating surface according to Comparative Example 1 at 140 ° C. is shown in FIG.

As shown in Table 1 and FIGS. 7 to 9, in the metal heaters according to Examples 1 to 4, the temperature of the heating surface of the upper metal plate during the steady state and during the transition was uniform. This is considered to be because the thickness of the metal plate on the heating surface side is equal to or more than a certain value, and the heat transmitted through the metal plate is sufficiently diffused, so that the heating element pattern is not reflected on the heating surface.
In particular, the temperature was uniform during the transition, because the distance between the support pins was small, the sensor wafer did not bend, and the distance between the heated surface of the upper metal plate and the sensor wafer did not vary. It is thought that it was.

Further, since the flatness of the metal heaters of Examples 1 to 4 is 50 μm or less as shown in Table 1, FIG. 13 and FIG. 14, there is no variation in the distance between the upper metal plate and the sensor wafer, and uniform heating is possible. It is thought that it was.
Further, in the metal heaters according to Examples 1 to 4, since the lower metal plate having a certain thickness is provided on the bottom surface of the heater, it is considered that the heat rays emitted from the heater were uniformed. .

On the other hand, in the metal heater according to Example 5, as shown in Table 1 and FIGS. 10 to 12, the temperature of the heating surface of the upper metal plate during the transition was not uniform. During the transition, the temperature of the heating surface fluctuated because the spacing between the support pins caused the sensor wafer to bend slightly, and the distance between the heating surface of the upper metal plate and the sensor wafer to slightly fluctuate. Is considered to have occurred. However, the temperature of the heating surface of the upper metal plate in the steady state was almost uniform, and there was no practical problem.

Further, in the metal heaters according to Examples 6 and 7, as shown in Table 1, the temperature of the heating surface of the upper metal plate during the steady state and during the transition was uniform. This is because a sufficient number of support pins are arranged on the heating surface, the semiconductor wafer does not bend, and the clearance between the heating surface and the semiconductor wafer is accurately maintained. This is considered to be due to the fact that it is easy to ensure the uniformity of the temperature, particularly the temperature of the heating surface during the transition.

As shown in Table 1, in the metal heater according to Test Example 1, the temperature of the heating surface of the upper metal plate during transition was uneven compared to the metal heater according to Example 12. Further, in the metal heater according to Test Example 2, as shown in Table 1, the temperature of the heating surface of the upper metal plate during the transition was not uniform as compared with the metal heater described in Example 6. During the transition, the temperature of the heating surface fluctuated because the distance between the support pins was so large that the sensor wafer slightly bent and the distance between the heating surface of the upper metal plate and the sensor wafer slightly fluctuated. Is considered to have occurred.

Further, in the metal heater according to Test Example 3, since the side surface of the metal plate and the supporting container are in close contact with each other, the metal plate bends due to compression from the side surface when the metal plate thermally expands. It is considered that the flatness of the surface was reduced, and as a result, the temperature on the heated surface became non-uniform.

In the metal heater according to Comparative Example 1, as shown in Table 1, the temperature of the heating surface of the upper metal plate during the steady state and during the transition was not uniform. It is considered that the reason why the temperature of the heating surface fluctuated was that the distance between the metal plate and the sensor wafer fluctuated due to the large waviness.

Regarding the amount of overshoot, the results of measurements by the metal heaters according to Examples 1 to 7, Test Examples 1 to 3, and Comparative Example 1 were all substantially the same.

(A) is sectional drawing which shows typically an example of the metal heater which concerns on this invention. (B) is a figure which shows typically the method of joining by caulking the heating element and the conductive wire via the joining foil in the metal heater shown to Fig.1 (a). FIG. 2 is a plan view of the metal heater illustrated in FIG. FIG. 2 is a horizontal sectional view of a heater constituting a part of the metal heater shown in FIG. It is sectional drawing which shows typically the metal plate and heater of the metal heater which concerns on this invention. It is sectional drawing which shows an example of the conventional metal heater typically. It is a top view of the metal heater shown in FIG. 6 is a graph showing a relationship between a wafer temperature and time at around 100 ° C. when the metal heater according to the first embodiment is used. 6 is a graph showing a relationship between a wafer temperature and a time around 120 to 130 ° C. when the metal heater according to the first embodiment is used. 4 is a graph showing a relationship between a wafer temperature and time around 140 ° C. when the metal heater according to the first embodiment is used. 13 is a graph showing the relationship between wafer temperature and time around 100 ° C. when the metal heater according to Example 5 is used. 13 is a graph showing a relationship between a wafer temperature and time at around 120 to 130 ° C. when the metal heater according to Example 5 is used. 14 is a graph showing the relationship between the wafer temperature and the time around 140 ° C. when the metal heater according to the fifth embodiment is used. FIG. 3 is a diagram illustrating a three-dimensional shape of a part of a metal heater heating surface according to the first embodiment at normal temperature. It is a figure which shows the three-dimensional shape of a part of metal heater heating surface concerning Example 1 at 140 degreeC. FIG. 6 is a diagram illustrating a three-dimensional shape of a part of a metal heater heating surface according to Comparative Example 1 at 140 ° C.

Explanation of reference numerals

REFERENCE SIGNS LIST 10 metal heater 11 upper metal plate 11 a heating surface 12 heater 14 bottomed hole 15 through hole 16 temperature measuring element 17 metal plate fixing screw 18 support pin 19 semiconductor wafer 20 support container 21 lower metal plate 22 holding plate 23 heat shield plate 24 Conductive wire 25 Support plate 27 Spring 28 Recess 29 Stainless steel foil 30 Stainless steel foil 31 for connection 31 Mounting member 32 Barrier ring

Claims (4)

A metal heater comprising a plurality of metal plates and a heating element, wherein the heating element is sandwiched between the metal plates,
A metal heater, wherein a convex portion for supporting the object to be heated is provided on a heating surface of the metal plate facing the object to be heated, corresponding to a region where the heating element is formed. . 2. The metal heater according to claim 1, wherein a diameter of a region where the heating element is formed is 250 mm or more, and a number of the protrusions is 6 or more. 2. The metal heater according to claim 1, wherein a diameter of the region where the heating element is formed is 200 to 250 nm, and the number of the protrusions is 5 or more. The metal heater according to any one of claims 1 to 3, wherein the heating element is divided into two or more.

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