JP2001068255A - Disc heater - Google Patents

Abstract

(57) [Problem] To be suitably used as a heating device for a wafer or the like,
Obtain a disc-shaped heater excellent in heat uniformity. An upper surface of a disc-shaped ceramic base is used as a work mounting surface, and a heating pattern of a predetermined pattern is buried in the base to heat the work. In the heater 1, the heating resistor pattern in the area where the workpiece Z is placed is shifted from the center x of the disc-shaped ceramic base 2 by a predetermined distance w to two concentric semicircles centered on two points a and b. The pattern of the heating resistor 4 is constituted by groups a _{1 to} a ₄ and b _{1 to} b ₄ , and is formed by connecting all the semicircles a _{1 to} a ₄ and b _{1 to} b ₄ in series. Power supply electrodes 5a and 5b are formed at both ends, and the power supply electrodes 5a and 5b are formed in an area outside the processing object mounting area c. Further, the distance w and the diameter D of the disc-shaped ceramic substrate are determined. Is set to 0.01 to 0.1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, plasma CVD and reduced pressure CV in the manufacturing process of a semiconductor manufacturing apparatus.
The present invention relates to a disc-shaped heater used for a device for supporting and heating a disc-shaped wafer used in a film forming apparatus such as D, photo-CVD, PVD or the like, or an etching apparatus such as plasma etching or photo-etching.

[0002]

2. Description of the Related Art Conventionally, in a film forming apparatus such as a plasma CVD, a low pressure CVD, a photo CVD and a PVD used in a manufacturing process of a semiconductor element, and an etching apparatus such as a plasma etching and a photo etching, a deposition gas or the like is used. A chlorine-based or fluorine-based corrosive gas has been used as an etching gas or a cleaning gas.

[0003] As a wafer heating device for holding a semiconductor wafer (hereinafter, referred to as a wafer) in a gas atmosphere and heating the semiconductor wafer to a processing temperature, a stainless steel heater having a built-in resistance heating element, or a graphite heated by an infrared lamp is used. Heaters and the like were used. However, the stainless steel heater has a problem that corrosive wear occurs due to the above-mentioned corrosive gas and particles are generated.A graphite heater is excellent in corrosion resistance, but has inferior thermal efficiency due to indirect heating, and a low temperature rising rate. There was the problem I said.

In order to solve such a problem, the upper surface of a disk-shaped dense ceramic base is used as a mounting surface for an object to be processed such as a wafer, and heat generated from a high melting point metal is contained therein. A disk-shaped heater for a wafer heating device in which a resistor is embedded in a heat generation pattern has been proposed.

[0005]

However, in a heater in which a heating resistor is buried, the temperature distribution on the surface on which an object is to be processed may not be uniform due to its pattern shape. In the vicinity, the heat generation density per unit area decreases, and a cold spot often occurs.

For example, in Japanese Unexamined Patent Application Publication No. 6-76924, as shown in FIG.
Thus, a plurality of concentric circles 23 having basically different diameters are formed, and a connecting portion 24 for connecting the inner and outer arcs in accordance with the inner and outer arcs is provided so that the concentric circles 23 are all connected in series.

However, in this method, the heating element pattern has a so-called spiral shape, and one end of the serially connected pattern is formed at the center of the disk, and the other end is formed at the outer periphery of the spiral. There was a problem that the routing of electric wires was restricted. Further, in this heating element pattern, it is necessary to partially form a pattern different from the other area such as the connection portion 24, and as a result, there is a problem that the uniformity in the circumferential direction is impaired.

Further, in the method using a metal wire as a heating element as disclosed in Japanese Patent Application Laid-Open No. 6-76924, the bending workability of the metal wire is also limited, and the pattern shape is very limited. This limits the pattern design for increasing the thermal property.

In order to solve these problems, for example, in Japanese Patent Application No. 9-360092, as shown in FIG. 4, a resistive heating element 25 is printed and applied in a predetermined pattern by a screen printing method using a conductive paste. It has been proposed to form. In addition, the pattern shape is the arc portion 2
It has been proposed that they are arranged in series by a combination of 6 and the folded portion 27.

However, in the heating element pattern as shown in FIG. 4, since the current densities of the arc portion 26 and the folded portion 27 are not uniform, a hot spot is formed particularly inside the folded portion 27, and There is a problem that a cold spot is formed on the outside and the object to be processed on the mounting surface cannot be heated uniformly.

Accordingly, an object of the present invention is to provide a disk-shaped heater which is used as a device for heating a semiconductor wafer or the like and which has excellent heat uniformity and in which local hot spots and cold spots are suppressed. Is what you do.

[0012]

The inventors of the present invention have made various studies on the above objects and as a result, have found that the upper surface of a disc-shaped ceramic substrate is used as a surface on which an object to be processed is placed, and the object to be processed is placed inside the substrate. In order to heat an object, in a disk-shaped heater in which a heat-generating pattern made of a heat-generating resistor is buried, the heat-generating pattern in an area where the object to be processed is mounted is shifted by a predetermined distance w from the center of the disk-shaped ceramic base. By forming two concentric semicircle groups having the two points as center points, and connecting all the semicircles in series, it is possible to eliminate a linear folded portion and to form a hot spot or It has been found that the generation of cold spots can be suppressed and the heat uniformity can be improved.

In this configuration, the distance w
And the diameter D of the disc-shaped ceramic substrate (w / D)
Is preferably in the range of 0.01 to 0.1 in order to enhance heat uniformity.

Further, a power supply electrode is formed at both ends of the heating pattern connected in series, and the power supply electrode is formed in a region outside a region where the object to be processed is placed. This can reduce the effect of the power supply electrode on the heat uniformity.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic perspective view (a) and a schematic sectional view (b) of a disc-shaped heater according to an embodiment of the present invention, and FIG. 2 is a disc-shaped heater of FIG. FIG. 4 is a plan view for explaining a heating resistor pattern of FIG.

The disc-shaped heater 1 shown in FIGS. 1 and 2 is made of a dense ceramic base 2, has an upper surface serving as a wafer W heating surface 3, and has a heating element pattern as shown in FIG. The heating resistor 4 is embedded. In addition,
The heating element patterns are connected in series, and at both ends,
A pair of power supply electrodes 5 for energizing the heating resistor 4 are attached, and a voltage is applied to the power supply electrode 5 to cause the heating resistor 4 to generate heat so that the wafer W mounted on the heating surface 3 can be uniformly formed. It is designed to be heated.

The disk-shaped ceramic substrate 2 constituting the disk-shaped heater 1 is formed of a ceramic mainly composed of alumina, silicon nitride, silicon carbide, sialon, and aluminum nitride having excellent wear resistance and heat resistance. In particular,
Aluminum nitride ceramics is 50W / mK or more,
In particular, it has a high thermal conductivity of 100 W / m · K or more, and is excellent in corrosion resistance and plasma resistance to fluorine-based and chlorine-based corrosive gases, and is therefore most suitable as the ceramic substrate 2. Specifically, a high-purity aluminum nitride having a purity of 99.7% or more or a sintering aid such as Y ₂ O ₃ or Er ₂ O _{3 is} added to aluminum nitride in an amount of 1 to 20% by weight.
It is preferable to use the contained aluminum nitride ceramics.

The heating resistor 4 embedded in the ceramic base 2 is made of a high melting point metal such as tungsten, molybdenum, rhenium, platinum or the like, or an alloy thereof, or the fourth element of the periodic table.
A group a, group 5a, or group 6a carbide or nitride can be used, and a material having a small thermal expansion difference from the ceramic substrate 2 may be appropriately selected and used.

According to the present invention, in the disk-shaped heater having the above-described basic configuration, the heating resistor 4 has a predetermined distance w from the center x of the disk-shaped ceramic base 2 as shown in FIG.
It is a great feature that it is constituted by two concentric semicircle groups centered on two points a and b shifted by only one point.

That is, according to FIG. 2, when the heating element pattern is divided by a straight line YY passing through the center of the base 2, a straight line Y-Y
On the surface above Y, a group of concentric semicircles a ₁ , a ₂ , a ₃ , a ₄ centering on the point a is formed, and on the surface below the straight line Y-Y Form a semicircle group of concentric semicircles b ₁ , b ₂ , b ₃ , b _{4 about} the point b.

Of the two semicircle groups, the semicircles a ₁ and b ₁ closest to the center are each formed by a semicircle having a radius w, and a ₂ and b ₂ each have a radius of 3 w. formed by a semicircular, n-th semicircular a _n, by setting as the radius r _n of b _n is (1 + 2n · w), each semicircular a ₁ ~ from the center point a, b a ₄ , b ₁ -b
₄ are all connected in series.

In other words, the semicircle groups a _{1 to} a ₄ and the semicircle groups b _{1 to} b ₄ have a 180 ° rotationally symmetric shape with respect to the center x of the ceramic base 2.

[0023] Then, at least the inside of the workpiece mounting surface on the upper surface of the ceramic base is formed by the above-described two semicircle groups, and the end of the pattern is formed in a region outside the workpiece mounting surface. Are formed with power supply electrodes 5a and 5b.

At this time, the dimensions of the semicircle group need only be optimally determined according to the size of the surface on which the object is to be processed and the target temperature distribution. The ratio (w / D) of the distance w and the diameter D of the disc-shaped ceramic substrate is determined as appropriate by the thickness, the resistivity of the heating resistor, the target heating temperature, the applied voltage / current, and the like. It is desirable to be in the range of 0.1 to improve the heat uniformity.

The power supply electrodes 5a and 5b are connected, for example, through through-hole conductors provided in the ceramic base 2.
It penetrates through the back surface of the ceramic base 2 and is connected to a power supply (not shown). In FIG. 3, the formation position of the power supply electrode 5 is formed at a position that is point-symmetric with respect to the center x of the ceramic base 2, but the positions of the power supply electrodes 5 a and 5 b are
However, the present invention is not limited to this, and there is no problem even if the power supply electrodes 5a and 5b are provided at close positions on the outside of the workpiece mounting surface.

Next, the temperature distribution during heating by the disk-shaped heater of the present invention was evaluated by the finite element method. The product of the present invention has a ceramic substrate having a thermal conductivity of 80 W / m ·
A pattern in which two semicircle groups consisting of four concentric semicircles from the centers a and b were used in series with a diameter D of 22 cm and a width of 3 mm using K aluminum nitride ceramics was used.

As shown in FIG. 4, Comparative Example 1 has four spiral patterns from the center a, and Comparative Example 2 has four concentric circles from the ceramic substrate as shown in FIG. What consisted of the pattern by the combination with a folded part was used.

In each case, the inside of a circle having a radius of 17 cm from the center of the ceramic substrate was determined as the surface to be processed, and the pattern width was 4 mm and the thickness was 20 μm.

Then, about 92 W of electric power was supplied and heated in the air at 25 ° C., and the temperature distribution on the workpiece mounting surface was determined. As a result, the temperature distribution width of the processing object mounting surface when the center of the heater was heated to 200 ° C. was measured.

As a result, in the disk-shaped heater of the present invention, 8
° C, 15 ° C in Comparative Example 1, and 12 ° C in Comparative Example 2. It was found that the product of the present invention had a smaller temperature distribution width than the other Comparative Examples.

[0031]

As described above, according to the disk-shaped heater of the present invention, the upper surface of the disk-shaped ceramic base is used as the heating surface, and the heater pattern formed of the band-shaped heating resistor is embedded therein. In the disk-shaped heater, by forming the heating element pattern by two semicircle groups connected in series, no hot spots and no cold spots are generated, and the pattern can be made uniform.
A more uniform heat generation distribution can be obtained. As a result, the wafer can be more uniformly heated when applied to a wafer heating device or the like for manufacturing semiconductor devices, so that the yield of manufacturing semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1A is a schematic perspective view and FIG. 1B is a schematic sectional view of an embodiment of a disk-shaped heater according to the present invention.

FIG. 2 is a plan view for explaining a pattern of a heating resistor in the disk-shaped heater of the present invention.

FIG. 3 is a diagram showing a heating resistor pattern of a conventional disk-shaped heater.

FIG. 4 is a diagram showing a heating resistor pattern of another conventional disk-shaped heater.

[Explanation of symbols]

1 disk-shaped heater 2 ceramic base 3 treatment object mounting surface 4 heating resistor 5 feeding electrode Z to be treated a ₁ ~a _4, b ₁ ~b ₄ semicircle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C23C 16/46 C23C 16/46 F term (reference) 3K034 AA02 AA16 AA17 AA21 BA06 BB06 BB14 BC17 HA01 HA10 JA10 3K092 PP09 QA05 QB02 QB33 QB44 QC38 RF03 RF11 RF17 RF26 4K029 DA08 4K030 KA22 5F045 BB08 EK09 EK21

Claims (3)

[Claims] 1. A disk-shaped heater in which an upper surface of a disk-shaped ceramic substrate is used as a surface on which an object to be processed is placed, and a heat-generating pattern comprising a heating resistor is buried in the substrate to heat the object to be processed. The heat generation pattern in the area where the object is placed is shifted by a predetermined distance w from the center of the disc-shaped ceramic substrate.
A disk-shaped heater comprising two concentric semicircle groups centered on two points, wherein all semicircles are connected in series. 2. A power supply electrode is formed at both ends of the heating pattern connected in series, and the power supply electrode is formed in a region outside a region on which the object to be processed is placed. The disk-shaped heater according to claim 1, wherein: 3. The disk-shaped heater according to claim 1, wherein a ratio (w / D) of the distance w to the diameter D of the disk-shaped ceramic substrate is in a range of 0.01 to 0.1. .