JP2022169005A - Heater and wafer heating device - Google Patents

Abstract

To provide a heater that secures uniformity of a temperature and that hardly goes wrong.SOLUTION: There is provided a heater comprising a disk-like substrate 30 composed of an insulating substance and a circuit pattern 7 composed of a metal resistance heating element, the resistance heating element being arranged so as to be in contact with the substrate, the circuit pattern being provided with a plurality of first pattern parts 71, each of the first pattern parts being composed of a plurality of first circular arc parts along a specific circumference concentric with the substrate and a first bent part that connects the adjoining first circular arc parts. A length of each of the first pattern parts along a specific circumference is greater than or equal to a reference length, and the length of each of the first circular arc parts is less than the reference length. A reference length Ls satisfies Ls=|ΔL/{ΔT×(α1-α2)}|, where ΔL represents a permissible value of difference between the thermal expansion amount of the insulating substance and the thermal expansion amount of metal, ΔT represents a temperature difference between the maximum working temperature of the circuit pattern and a normal temperature, α1 represents a linear expansion coefficient of the insulating substance, and α2 represents a linear expansion coefficient of metal.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to heaters and wafer heating apparatuses.

Japanese Unexamined Patent Application Publication No. 2002-200000 discloses a wafer heating apparatus that heats a wafer in, for example, a photolithography process. The wafer heating apparatus of Patent Document 1 includes a heater unit that heats the wafer and a movable cooling module that cools the heater unit. A wafer is placed on the upper surface of the heater unit. The heater unit includes a heater including a resistive heating element. The movable cooling module is configured to be vertically movable. The heater unit is cooled by the movable cooling module contacting the lower surface of the heater unit.

The heater includes a disc-shaped base material made of an insulator and a circuit pattern of a resistance heating element integrated with the base material. The circuit pattern is configured by, for example, combining a plurality of circular arc portions and a plurality of straight line portions. Of course, the circuit pattern may include portions other than arcuate portions and linear portions, such as meandering portions.

JP 2011-129577 A

The inventors of the present disclosure arrived at solutions by discovering the following problems. If the arc portion and the straight portion included in the circuit pattern are too long, the difference between the amount of thermal expansion of the arc portion and the straight portion and the amount of thermal expansion of the substrate becomes large when the circuit pattern generates heat. If the adhesion between the circuit pattern and the substrate is reduced due to the difference in the amount of thermal expansion, the heat of the circuit pattern may be difficult to transfer to the wafer holding plate. As a result, the uniformity of the temperature of the heater may be impaired. In addition, the circuit pattern may be abnormally overheated, and in some cases the circuit pattern and substrate may be damaged.

If the difference between the amount of thermal expansion of the arcuate portion and the linear portion and the amount of thermal expansion of the substrate becomes large, the heater may be deformed. As a result, a gap is formed between the wafer holding plate on which the wafer is placed and the heater, which may reduce the uniformity of the temperature of the heater.

One object of the present disclosure is to obtain a heater that is less likely to fail while ensuring uniformity of temperature. SUMMARY OF THE INVENTION It is an object of the present disclosure to provide a wafer heating apparatus that ensures temperature uniformity and is less likely to fail because a gap is less likely to form between a wafer holding plate and a heater during heating.

A first heater of the present disclosure includes:
A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of first pattern parts,
Each first pattern portion includes a plurality of first arc portions along a specific circumference concentric with the base material, and a first bend connecting first arc portions adjacent to each other in a direction along the specific circumference. is composed of
The length along the specific circumference of each first pattern portion is equal to or greater than the reference length Ls,
The length of each first arc portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the linear expansion coefficient of the metal.

The second heater of the present disclosure includes
A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of third pattern parts,
Each third pattern portion is composed of a plurality of first linear portions along a specific straight line and a second bent portion connecting the first linear portions adjacent to each other in the direction along the specific straight line,
The length of each third pattern portion along the specific straight line is equal to or greater than the reference length Ls,
The length of each first straight portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the linear expansion coefficient of the metal.

The wafer heating apparatus of the present disclosure is
a disk-shaped wafer holding plate having an upper surface on which the wafer is placed;
A wafer heating apparatus comprising a heater for heating the wafer holding plate,
The heater is the heater of the present disclosure.

According to the present disclosure, it is possible to obtain a heater and a wafer heating apparatus that are less likely to fail while ensuring temperature uniformity.

FIG. 1 is a schematic configuration diagram of a wafer heating apparatus according to Embodiment 1. FIG. FIG. 2 is a schematic plan view of the heater according to Embodiment 1. FIG. FIG. 3 is an enlarged view of a portion surrounded by a dashed line in FIG. FIG. 4 is a schematic diagram of a first pattern portion provided in the heater according to Embodiment 1. FIG. FIG. 5 is a schematic diagram of a second pattern portion provided in a heater according to Embodiment 2. FIG. FIG. 6 is a schematic diagram of a third pattern portion provided in a heater according to Embodiment 3. FIG. FIG. 7 is a schematic diagram of a fourth pattern portion provided in a heater according to Embodiment 3. FIG.

[Description of Embodiments of the Present Disclosure]
Embodiments of the present disclosure are listed and described below.

<1> The heater according to the embodiment is
A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of first pattern parts,
Each first pattern portion includes a plurality of first arc portions along a specific circumference concentric with the base material, and a first bend connecting first arc portions adjacent to each other in a direction along the specific circumference. is composed of
The length along the specific circumference of each first pattern portion is equal to or greater than the reference length Ls,
The length of each first arc portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the linear expansion coefficient of the metal.

The heater according to form <1> is difficult to deform. Moreover, in the heater according to the above aspect <1>, the adhesion between the circuit pattern and the substrate is less likely to deteriorate.
In the heater according to the above aspect <1>, the first pattern portion whose length along the specific circumference concentric with the base material is equal to or greater than the reference length Ls includes a plurality of first arc portions having a length less than the reference length Ls. is divided into The reference length Ls is a length determined based on the allowable value ΔL of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal. Therefore, if the first arc portion is less than the reference length Ls, the difference between the amount of thermal expansion of the first arc portion and the amount of thermal expansion of the substrate in contact with the first arc portion does not exceed the allowable value ΔL. . As a result, deformation of the heater around the first pattern portion is suppressed. How to obtain the reference length Ls and its significance will be described in detail in the embodiments described later.

<2> As one form of the heater according to the embodiment,
The circuit pattern further comprises a plurality of second pattern parts,
Each second pattern portion is configured by a second arc portion along the circumferential direction of the base material,
The length of each second arc portion is equal to or greater than the reference length Ls,
The number S1 of the first pattern portions and the number S2 of the second pattern portions may satisfy 0.7≦S1/(S1+S2).

The second pattern portion configured by the second arc portion having the reference length Ls or longer does not contribute to suppressing deformation of the heater. Since the heater of the embodiment mainly includes a plurality of first pattern portions that suppress deformation of the heater, it is permissible for the circuit pattern to include the second pattern portions. However, it is preferable that the number of second pattern portions included in the circuit pattern is small. As defined in the above mode <2>, if the number of the first pattern portions in the total number of the first pattern portions and the number of the second pattern portions is 70% or more, the deformation of the heater is effective. Suppressed.

<3> As one form of the heater according to the embodiment,
A mode in which each length of all arcuate portions provided in the circuit pattern is less than the reference length Ls can be mentioned.

As defined in form <3> above, if all the arc portions included in the circuit pattern are shorter than the reference length Ls, deformation of the heater is suppressed over the entire surface of the heater.

<4> The heater according to the embodiment is
A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of third pattern parts,
Each third pattern portion is composed of a plurality of first linear portions along a specific straight line and a second bent portion connecting the first linear portions adjacent to each other in the direction along the specific straight line,
The length of each third pattern portion along the specific straight line is equal to or greater than the reference length Ls,
The length of each first straight portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the linear expansion coefficient of the metal.

The heater according to form <4> is difficult to deform. Further, in the heater according to the above aspect <4>, the adhesion between the circuit pattern and the substrate is less likely to deteriorate.
In the heater according to the above aspect <4>, the third pattern portion whose length along the specific straight line is equal to or longer than the reference length Ls is divided into a plurality of first straight portions each having a length less than the reference length Ls. The reference length Ls is a length determined based on the allowable value ΔL of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal. Therefore, if the first straight portion is shorter than the reference length Ls, the difference between the amount of thermal expansion of the first straight portion and the amount of thermal expansion of the substrate in contact with the first straight portion does not exceed the allowable value ΔL. As a result, deformation of the heater around the third pattern portion is suppressed.

<5> As one form of the heater according to the above form <4>,
The circuit pattern further comprises a plurality of fourth pattern parts,
Each fourth pattern portion is composed of a second linear portion,
The length of each second straight portion is equal to or greater than the reference length Ls,
The number S3 of the third pattern portions and the number S4 of the fourth pattern portions may satisfy 0.7≦S3/(S3+S4).

The fourth pattern portion composed of the second linear portion having the reference length Ls or longer does not contribute to suppressing the deformation of the heater. Since the heater according to the embodiment mainly includes a plurality of third pattern portions that suppress deformation of the heater, it is permissible for the circuit pattern to include the fourth pattern portion. However, it is preferable that the number of fourth pattern portions included in the circuit pattern is small. As defined in the above mode <5>, if the number of the third pattern portions to the total number of the third pattern portions and the number of the fourth pattern portions is 70% or more, the deformation of the heater is effective. Suppressed.

<6> As one form of the heater according to the above form <4>,
A mode in which each length of all linear portions provided in the circuit pattern is less than the reference length Ls can be mentioned.

As defined in mode <6> above, if all the linear portions included in the circuit pattern are shorter than the reference length Ls, deformation of the heater is suppressed over the entire surface of the heater.

<7> As one form of the heater according to the embodiment,
For example, the allowable value ΔL is 0.2 mm, and the temperature difference ΔT is 280°C.

If the allowable value ΔL is 0.2 mm when the temperature difference ΔT is 280° C., deformation of the heater can be effectively suppressed. The temperature difference of 280°C is a value when the maximum operating temperature of the circuit pattern is 300°C and the normal temperature is 20°C.

<8> As one form of the heater according to the embodiment,
A mode in which the metal is stainless steel is exemplified.

Stainless steel has excellent heat resistance. Stainless steel is readily available and can be easily processed into a foil shape and patterned by etching.

<9> As one form of the heater according to the embodiment,
The insulator may be polyimide.

Polyimide has excellent heat resistance. Therefore, damage to the substrate due to use of the heater is suppressed.

<10> The wafer heating apparatus according to the embodiment includes:
a disk-shaped wafer holding plate having an upper surface on which the wafer is placed;
A wafer heating apparatus comprising a heater for heating the wafer holding plate,
The heater is a heater according to any one of the above modes <1> to <9>.

A wafer heating apparatus according to an embodiment includes a heater according to an embodiment. Since the heater according to the embodiment is less likely to be deformed during heating, it is less likely that a gap will be formed between the heater and the wafer holding plate. Therefore, the contact between the heater and the wafer holding plate is easily maintained over the entire surface of the heater. As a result, the uniformity of the temperature of the wafer holding plate is improved, so that the wafer heating apparatus of the aspect <10> can uniformly heat the entire surface of the wafer.

[Details of the embodiment of the present disclosure]
Specific examples of a wafer heating apparatus and a heater according to embodiments of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same or corresponding parts. The sizes of the members shown in the drawings are expressed for the purpose of clarity of explanation and do not necessarily represent actual dimensions. The present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

<Embodiment 1>
≪Overall composition≫
A wafer heating apparatus 1 of the embodiment shown in FIG. 1 is used for pre-baking and the like in a photolithography process. Pre-baking is heat treatment for volatilizing the solvent of the photoresist solution applied to the surface of the wafer 100 . The wafer heating apparatus 1 includes a heater unit 10 that heats the wafer 100 and a cooling unit 11 that cools the heater unit 10 . A cooling plate 5 provided in the cooling unit 11 is configured to be vertically movable, and cools the heater unit 10 as required. Hereinafter, each configuration of the wafer heating apparatus 1 according to the embodiment will be described in detail.

≪Heater unit≫
The heater unit 10 of this example includes a wafer holding plate 2, a heater 3, and a support plate 4 in order from above. The support plate 4 is not essential.

[Wafer holding plate]
The wafer holding plate 2 has a flat upper surface 2U on which the wafer 100 is placed. The upper surface 2U constitutes an upper surface 10U of the heater unit 10. As shown in FIG. The wafer holding plate 2 is a disc. The diameter of the disk should be larger than the wafer 100 placed on the upper surface 10U, and is, for example, 200 mm or more and 400 mm or less.

The material of the wafer holding plate 2 is preferably a material that has excellent thermal conductivity and is resistant to deformation due to heat. Preferred materials include copper, aluminum, or alloys containing these. The surface of the wafer holding plate 2 is preferably nickel-plated or alumite-treated. Ceramics can also be used as the material of the wafer holding plate 2 . Examples of ceramics include ceramics such as aluminum nitride, silicon carbide (SiC), aluminum oxide, or silicon nitride, or composites of these ceramics and silicon (Si). In particular, Si—SiC, which is a SiC porous body impregnated with metallic silicon, is preferable as the material for the wafer holding plate 2 .

The wafer holding plate 2 may have projections (not shown), vacuum ports, lift pin holes, and the like. A projection is provided on the upper surface 2U. The protrusion forms a minute gap between the upper surface 2U and the wafer 100. FIG. The vacuum port and lift pin holes are holes penetrating the wafer holding plate 2 in the thickness direction. When air is sucked from the gap between the upper surface 2U and the wafer 100 through the vacuum port, the wafer 100 is corrected to a nearly flat state. The lift pin holes are holes through which lift pins for lifting the wafer 100 from the upper surface 2U are inserted. Vacuum ports and lift pin holes are also provided in heaters 3 and support plates 4, which will be described later.

A temperature measuring element 25 is provided on the lower surface 2D of the wafer holding plate 2 of this example. The temperature of the wafer holding plate 2 measured by the temperature measuring element 25 is used for controlling the heater 3, which will be described later. The temperature measuring element 25 is arranged, for example, in the counterbored hole 20 provided in the lower surface 2D. As the temperature measuring element 25, for example, a temperature measuring element obtained by depositing a platinum resistor on ceramics may be used. The temperature measuring element 25 is fixed with, for example, a silicone adhesive. A wiring (not shown) is connected to the temperature measuring element 25 .

[heater]
The heater 3 is a member that heats the wafer holding plate 2 . The wafer 100 is heat-treated by the wafer holding plate 2 heated by the heater 3 . The heater 3 includes a disc-shaped base material 30 made of an insulator, and a circuit pattern 7 made of a metal resistance heating element. The base material 30 constitutes the outer shape of the heater 3 . The substrate 30 of this example is disk-shaped and has the same outer diameter as the wafer holding plate 2 . In the heater 3 of this example, the circuit pattern 7 is arranged inside the base material 30 . The circuit pattern 7 is composed of, for example, a metal thin film that generates heat when energized.

As an insulator forming the base material 30, for example, an insulating resin having excellent heat resistance such as polyimide can be used. Other insulators include, for example, resin-impregnated mica sheets and ceramics. Examples of the metal forming the circuit pattern 7 include stainless steel and nickel-chromium steel. In this example, the heater 3 is produced by sandwiching the circuit pattern 7 between two polyimide sheets. The circuit pattern 7 is formed by partially etching a stainless steel foil, for example.

The circuit pattern 7 may be formed on the lower surface 2D of the wafer holding plate 2 by metallization. In that case, the heater 3 integrated with the lower surface 2D is formed by coating the lower surface 2D including the circuit pattern 7 with an insulating resin or the like.

The linear expansion coefficient α1 of the insulator and the linear expansion coefficient α2 of the metal may differ greatly. For example, the coefficient of linear expansion α1 of polyimide is about 20 ppm/°C to 24 ppm/°C. The linear expansion coefficient α2 of stainless steel is approximately 17.3 ppm/°C, and the linear expansion coefficient α2 of nickel-chromium steel is approximately 14.0 ppm/°C. Here, when the circuit pattern 7 has an arc portion of length L, the effect of the difference between the linear expansion coefficient α1 and the linear expansion coefficient α2 on the heater 3 will be considered. The length L is the length along the arc direction of the arc portion. When the circuit pattern 7 reaches the maximum operating temperature, an expansion difference ΔX is generated between the amount of thermal expansion in the arc direction of the arc portion and the amount of thermal expansion in the arc direction of the substrate 30 in close contact with the arc portion. The expansion difference ΔX is represented by the following formula (1).
ΔX=|(L×ΔT×α1)−(L×ΔT×α2)|
ΔT: Temperature difference between maximum operating temperature of circuit pattern 7 and normal temperature

If the expansion difference ΔX exceeds a predetermined value, the adhesion between the circuit pattern 7 and the substrate 30 may deteriorate. In addition, the heater 3 may be deformed, for example, by bending in the thickness direction. Therefore, the allowable value ΔL of the expansion difference ΔX is set, and the length L of the arc portion at which the heater 3 is difficult to deform is obtained. By substituting ΔL for ΔX in the equation (1) and modifying the equation (1), the following equation (2) is obtained.
L=|ΔL/{ΔT×(α1−α2)}|

The expansion difference ΔX is always equal to or less than the allowable value ΔL in the arc portion having the length L or less obtained from the above formula (2). Therefore, the heater 3 having an arc portion with a length L or less is less likely to deform. Hereinafter, the length L obtained by the formula (2) is defined as a reference length Ls.

The allowable value ΔL to be substituted into equation (2) is, for example, 0.2 mm. If deformation of the heater 3 is suppressed more reliably, the allowable value ΔL is 0.1 mm. The temperature difference ΔT to be substituted into equation (2) is, for example, 280°C. This value is obtained by setting the maximum operating temperature of the circuit pattern 7 to 300.degree. C. and normal temperature to 20.degree. As is clear from equation (2), the larger the temperature difference ΔT, the shorter the reference length Ls.

The heater 3 of this example is designed in consideration of the reference length Ls mentioned above. First, the overall structure of the heater 3 will be described with reference to the plan view of FIG. Next, details of the circuit pattern 7 provided in the heater 3 will be described with reference to FIGS. 3 and 4. FIG.

The heater 3 of this example comprises a plurality of heating zones 8, as shown in the plan view of FIG. The plurality of heating zones 8 includes three heating zones 8A arranged on the inner peripheral side and three heating zones 8B arranged on the outer peripheral side. The point where the three heating zones 8A meet is the center 30c of the substrate 30. As shown in FIG. The heating zone 8A on the inner peripheral side is fan-shaped with an internal angle of 120°. The heating zone 8B on the outer peripheral side has a band shape having an inner peripheral arc and an outer peripheral arc with an internal angle of 120°. Although not shown in FIG. 2, each heating zone 8 has an independent circuit pattern 7 (see FIG. 3). Here, the number of heating zones 8 and the shape of the heating zones 8 are not particularly limited. The number of heating zones 8 may be one.

FIG. 3 is an enlarged view of the heater 3 shown in FIG. 2, enlarging a portion surrounded by a dashed line. The circuit pattern 7 of the heater 3 shown in FIG. 3 has two terminals 70, 70 to which wiring (not shown) is connected. By energizing between the terminals 70, 70, the circuit pattern 7 generates heat. A base material 30 of the heater 3 is provided with a through hole 30h. A wiring connected to the temperature measuring element 25 of FIG. 1 is arranged in the through hole 30h.

The circuit pattern 7 of this example includes a plurality of circular arc portions 7b and a plurality of straight line portions 7s. The plurality of arcuate portions 7b include first arcuate portions 711, 712 along the circumference concentric with the substrate 30, transition portions 76A, 76B having centers different from the center of the substrate 30, and the like. The linear portion 7 s in this example extends along the radial direction of the substrate 30 . The straight portion 7s may extend along a direction crossing the radial direction.

The circuit pattern 7 has a first pattern portion 71 including a plurality of arc portions 7b that satisfy a predetermined condition. The first pattern portion 71 is arranged between the transition portion 76A and the transition portion 76B. Each first pattern portion 71 is composed of two first arc portions 711 and 712 and one first bent portion 713, as shown in FIG. The first circular arc portions 711 and 712 are a kind of circular arc portion 7b. The first circular arc portion 711 and the first circular arc portion 712 are arranged along a specific circumference 91 indicated by a two-dot chain line. A particular circumference 91 is a circumference concentric with center 30c of substrate 30 shown in FIG. The transition portions 76A and 76B arranged at both ends of the first pattern portion 71 are semicircular arc portions 7b that connect the two arc portions 7b and 7b that are arranged in the radial direction of the substrate 30 . Transition portions 76A and 76B are arc portions 7b having centers different from the center of substrate 30. FIG. Therefore, the location where the curvature changes is the boundary between the first pattern portion 71 and the transition portions 76A and 76B.

The first bent portion 713 connects two first circular arc portions 711 and 712 arranged on a specific circumference 91 . The first bent portion 713 is formed in a substantially U shape in plan view. The first bent portion 713 may be substantially V-shaped in plan view. The first bent portion 713 is curved in a direction opposite to the direction in which the first arc portions 711 and 712 are curved. The first bent portion 713 may be curved in the same direction as the curved direction of the first arc portions 711 and 712 .

The first pattern portion 71 may include k first arc portions 711 and 712 . In that case, the number of first bent portions 713 is k−1. k is a natural number of 3 or more.

A length L1 along the specific circumference 91 of the first pattern portion 71 is equal to or greater than the reference length Ls. The length L11 of the first arc portion 711 and the length L12 of the first arc portion 712 provided in the first pattern portion 71 are less than the reference length Ls. Also, the length along the U-shape of the first bent portion 713 is extremely short. In other words, there is no portion of the first pattern portion 71 that becomes equal to or greater than the allowable value ΔL during heating. Therefore, deformation of the heater 3 is suppressed in the vicinity of the first pattern portion 71 .

The circuit pattern 7 of this example includes, as shown in FIG. 3, an arc portion 77 having a length less than the reference length Ls, in addition to the first arc portions 711 and 712 and the transition portions 76A and 76B. In this example, the lengths of all arcuate portions 7b provided in the circuit pattern 7 are less than the reference length Ls. Furthermore, the lengths of all straight portions 7s provided in the circuit pattern 7 of this example are also less than the reference length Ls. The heater 3 having such a circuit pattern 7 is less likely to deform during heating. Moreover, the adhesion between the circuit pattern 7 and the substrate 30 is less likely to deteriorate.

[Support plate]
The support plate 4 supports the heater 3 from below, as shown in FIG. Since the flatness of the wafer holding plate 2 is maintained by the supporting plate 4, the uniformity of the temperature of the wafer holding plate 2 is improved. Since the supporting plate 4 is a highly rigid body, the thickness of the heater unit 10 including the wafer holding plate 2 can be reduced. As a result, the heat capacity of the heater unit 10 is reduced, and the temperature rise rate and temperature drop rate of the heater unit 10 are improved. In this example, the lower surface 4D of the support plate 4 constitutes the lower surface 10D of the heater unit 10. As shown in FIG. The cooling plate 5 of the cooling unit 11 contacts the lower surface 4D of the support plate 4 when the heater unit 10 is cooled. Since the support plate 4 prevents the cooling plate 5 from directly contacting the lower surface 3D of the heater 3, the heater 3 is less likely to be damaged. The supporting plate 4 of this example is disk-shaped and has the same outer diameter as the wafer holding plate 2 . In this example, the supporting plate 4, the wafer holding plate 2, and the heater 3 are integrated with fastening screws (not shown). Like the wafer holding plate 2, the supporting plate 4 is preferably made of ceramics.

≪Cooling unit≫
The cooling unit 11 is configured to cool the heater unit 10 as necessary. The cooling unit 11 has a cooling plate 5 and a cooling stage 6 .

[Cooling stage]
The cooling stage 6 is maintained at a low temperature by coolant or the like. For example, a coolant flow path is formed inside the cooling stage 6 . The cooling stage 6 has a role of cooling the cooling plate 5 . The cooling stage 6 also has a role of holding the heater unit 10 above the cooling stage 6 . Specifically, the cooling stage 6 and the heater unit 10 are connected by a fixed shaft 60 . The fixed shaft 60 passes through the cooling plate 5 and the cooling plate 5 is not fixed by the fixed shaft 60 .

[Cooling plate]
The cooling plate 5 is configured to be vertically movable. For example, a cooling plate 5 is attached to the tip of a rod of an air cylinder (not shown). When the heater unit 10 is cooled, the cooling plate 5 at a low temperature moves upward via the cooling stage 6 and contacts the lower surface 4D of the support plate 4, that is, the lower surface 10D of the heater unit 10. FIG. Since the upper surface 5U of the cooling plate 5 contacts the lower surface 10D of the heater unit 10, the heater unit 10 is quickly cooled, and the temperature of the heater unit 10 is adjusted to a desired temperature. After the cooling of the heater unit 10 is completed, the cooling plate 5 separates from the lower surface 4D of the support plate 4 and descends to a position where the lower surface 5D contacts the cooling stage 6 .

The cooling plate 5 of this example includes a disk-shaped main body 50 and an upper layer 51 arranged on the upper surface of the main body 50 . Unlike this example, the cooling plate 5 may not have the upper layer 51 . The main body 50 is preferably made of a material with excellent thermal conductivity, such as metal. The main body 50 of this example is made of an aluminum alloy.

The upper layer 51 has the function of improving the adhesion between the cooling plate 5 and the heater unit 10 . The upper layer 51 of this example is a resin sheet. The material of the upper layer 51 is preferably, for example, a highly flexible material containing silicone or fluorine as a main component. The upper layer 51 having excellent flexibility improves the adhesion between the cooling plate 5 and the heater unit 10 and improves the cooling efficiency of the heater unit 10 by the cooling plate 5 . Moreover, the upper layer 51 having excellent flexibility suppresses damage to the main body 50 of the cooling plate 5 and the heater unit 10 when the cooling plate 5 comes into contact with the heater unit 10 .

A wafer heating apparatus 1 according to the embodiment includes a heater 3 that is difficult to deform during heating. If the heater 3 is difficult to deform, it is difficult to form a gap between the heater 3 and the wafer holding plate 2 , and the contact between the heater 3 and the wafer holding plate 2 is likely to be maintained over the entire surface of the heater 3 . Therefore, the heater 3 improves the temperature uniformity of the wafer holding plate 2, so that the wafer 100 placed on the upper surface 10U of the wafer holding plate 2 is uniformly heated.

<Embodiment 2>
In the second embodiment, the heater 3 and the wafer heating device 1 in which the circuit pattern 7 includes the second pattern portion 72 having the reference length Ls or longer will be described. In the description of the second embodiment, reference is made to FIG. 5 in addition to FIGS. 1 to 4. FIG. The configuration of the second embodiment is the same as that of the first embodiment except that the circuit pattern 7 includes the second pattern portion 72 .

The circuit pattern 7 of this example includes a second pattern portion 72 shown in FIG. 5 in addition to the first pattern portion 71 shown in FIG. The second pattern portion 72 is composed of one second circular arc portion 720 . A second arc 720 follows a particular circumference 92 concentric with substrate 30 . The length L2 of the second arc portion 720 is equal to or longer than the reference length Ls. This second pattern portion 72 does not contribute to suppressing deformation of the heater 3 . Since the deformation of the heater 3 is suppressed by the first pattern portion 71, the inclusion of the second pattern portion 72 in the circuit pattern 7 is permitted. However, it is preferable that the number of the second pattern portions 72 included in the circuit pattern 7 is small. For example, the number S1 of the first pattern portions 71 and the number S2 of the second pattern portions 72 preferably satisfy the following formula (3).
0.7≦S1/(S1+S2) Expression (3)

Equation (3) above indicates that the number S1 of the first pattern portions 71 is relatively larger than the number S2 of the second pattern portions 72 . The closer S1/(S1+S2) is to 1, the better. Therefore, S1/(S1+S2) is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 0.95 or more. Most preferably, the second pattern portion 72 is absent, as shown in the first embodiment.

From the viewpoint of suppressing deformation of the entire heater 3 , in the case of the heater 3 including the first pattern portion 71 and the second pattern portion 72 , the plurality of first pattern portions 71 that suppress deformation of the heater 3 are formed on the entire surface of the heater 3 . are preferably distributed in the It is preferable that the plurality of second pattern portions 72 be distributed over the entire surface of the heater 3 rather than locally arranged on the heater 3 . When the first pattern portion 71 is arranged near the second pattern portion 72, the heater 3 is less likely to deform.

<Embodiment 3>
In the heaters 3 of Embodiments 1 and 2, there is no linear portion 7s having a length equal to or longer than the reference length Ls. However, depending on the pattern shape of the circuit pattern 7, a linearly extending pattern portion having a length equal to or greater than the reference length Ls may be formed. In the third embodiment, a configuration in which the pattern portion extending linearly with the reference length Ls or longer is replaced with the third pattern portion 73 will be described with reference to FIG.

As shown in FIG. 6 , the circuit pattern 7 provided in the heater 3 of this example has a third pattern portion 73 . The third pattern portion 73 is arranged between the transition portion 76C and the transition portion 76D. The third pattern portion 73 of this example is composed of two first linear portions 731 and 732 and one second bent portion 733 . The first linear portions 731 and 732 are a kind of linear portion 7s. The first straight portion 731 and the first straight portion 732 are arranged along a specific straight line 93 indicated by a two-dot chain line. A specific straight line 93 extends along the radial direction of the substrate 30 . Transition portions 76C and 76D arranged at both ends of the third pattern portion 73 are curved portions that connect to the arc portion 7b or another straight portion 7s.

The third pattern portion 73 may include k first linear portions 731 and 732 . In that case, the number of second bending portions 733 is k−1. k is a natural number of 3 or more.

A length L3 along the specific straight line 93 of the third pattern portion 73 is equal to or longer than the reference length Ls. The length L31 of the first linear portion 731 and the length L32 of the first linear portion 732 provided in the third pattern portion 73 are less than the reference length Ls. The deformation of the heater 3 is suppressed by the third pattern portion 73 .

The circuit pattern 7 may have a fourth pattern portion 74 shown in FIG. The fourth pattern portion 74 is composed of one second linear portion 740 . A second straight portion 740 is along a particular straight line 94 . The length L4 of the second straight portion 740 is equal to or longer than the reference length Ls. The fourth pattern portion 74 does not contribute to suppressing deformation of the heater 3 . Since the deformation of the heater 3 is suppressed by the third pattern portion 73, the inclusion of the fourth pattern portion 74 in the circuit pattern 7 is permitted. However, it is preferable that the number of the fourth pattern portions 74 included in the circuit pattern 7 is small. For example, the number S3 of the third pattern portions 73 and the number S4 of the fourth pattern portions 74 preferably satisfy the following formula (4).
0.7≦S3/(S3+S4) Expression (4)

Equation (4) above indicates that the number S3 of the third pattern portions 73 is relatively larger than the number S4 of the fourth pattern portions 74 . The closer S3/(S3+S4) is to 1, the better. Therefore, S3/(S3+S4) is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 0.95 or more. Most preferably, the fourth pattern portion 74 is absent, as shown in the first embodiment.

From the viewpoint of suppressing deformation of the entire heater 3 , in the case of the heater 3 including the third pattern portion 73 and the fourth pattern portion 74 , the plurality of third pattern portions 73 are arranged dispersedly over the entire surface of the heater 3 . is preferred. Similarly, it is preferable that the plurality of fourth pattern portions 74 are also distributed over the entire surface of the heater 3 . When the third pattern portion 73 is arranged near the fourth pattern portion 74, the heater 3 is less likely to deform.

Reference Signs List 100 wafer 1 wafer heating device 10 heater unit 10D lower surface 10U upper surface 11 cooling unit 2 wafer holding plate 2D lower surface 2U upper surface 20 counterbore 25 temperature measuring element 3 heater 3D lower surface 30 substrate 30c center 30h through hole 4 Support plate 4D Lower surface 5 Cooling plate 5D Lower surface 5U Upper surface 50 Main body 51 Upper layer 6 Cooling stage 60 Fixed axis 7 Circuit pattern 7b Arc portion 7s Linear portion 70 Terminal 71 First pattern portion 711, 712 First arc portion 713 first curved portion 72 second pattern portion 720 second arc portion 73 third pattern portion 731, 732 first straight portion 733 second curved portion 74 fourth pattern portion 740 second straight portion 76A, 76B, 76C , 76D transition portion 77 arc portion 8, 8A, 8B heating zones 91, 92 specific circumferences 93, 94 specific straight lines L1, L2, L3, L4, L11, L12, L31, L32 length Ls reference length

Claims (10)

A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of first pattern parts,
Each first pattern portion includes a plurality of first arc portions along a specific circumference concentric with the base material, and a first bend connecting first arc portions adjacent to each other in a direction along the specific circumference. is composed of
The length along the specific circumference of each first pattern portion is equal to or greater than the reference length Ls,
The length of each first arc portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the coefficient of linear expansion of the metal,
heater. The circuit pattern further comprises a plurality of second pattern parts,
Each second pattern portion is configured by a second arc portion along the circumferential direction of the base material,
The length of each second arc portion is equal to or greater than the reference length Ls,
2. The heater according to claim 1, wherein the number S1 of said first pattern portions and the number S2 of said second pattern portions satisfy 0.7≦S1/(S1+S2). 2. The heater according to claim 1, wherein each length of all arcuate portions provided in said circuit pattern is less than said reference length Ls. A heater for heating a wafer,
a disc-shaped base material made of an insulator;
and a circuit pattern configured by a metal resistance heating element,
The resistance heating element is arranged so as to be in contact with the base material,
The circuit pattern comprises a plurality of third pattern parts,
Each third pattern portion is composed of a plurality of first linear portions along a specific straight line and a second bent portion connecting the first linear portions adjacent to each other in the direction along the specific straight line,
The length of each third pattern portion along the specific straight line is equal to or greater than the reference length Ls,
The length of each first straight portion is less than the reference length Ls,
The reference length Ls satisfies Ls=|ΔL/{ΔT×(α1−α2)}|
ΔL is the allowable value of the difference between the amount of thermal expansion of the insulator and the amount of thermal expansion of the metal;
ΔT is the temperature difference between the maximum operating temperature of the circuit pattern and normal temperature,
α1 is the coefficient of linear expansion of the insulator,
α2 is the coefficient of linear expansion of the metal,
heater. The circuit pattern further comprises a plurality of fourth pattern parts,
Each fourth pattern portion is composed of a second linear portion,
The length of each second straight portion is equal to or greater than the reference length Ls,
5. The heater according to claim 4, wherein the number S3 of the third pattern portions and the number S4 of the fourth pattern portions satisfy 0.7≦S3/(S3+S4). 5. The heater according to claim 4, wherein each length of all straight portions provided in said circuit pattern is less than said reference length Ls. The heater according to any one of claims 1 to 6, wherein the allowable value ΔL is 0.2 mm and the temperature difference ΔT is 280°C. A heater according to any preceding claim, wherein the metal is stainless steel. A heater according to any preceding claim, wherein the insulator is polyimide. a disk-shaped wafer holding plate having an upper surface on which the wafer is placed;
A wafer heating apparatus comprising a heater for heating the wafer holding plate,
The heater is the heater according to any one of claims 1 to 9,
Wafer heating equipment.

Images