JPH0676924A - Semiconductor wafer heating device - Google Patents

Abstract

PURPOSE:To uniformize further a temperature of a wafer heating surface in a disk shape ceramics heater formed by using resistance heating elements. CONSTITUTION:In a semiconductor wafer heating device 1 having a disk shape ceramics base material 2 and resistance heaving elements 3 buried inside of this ceramics base material 2, connecting parts 3b are arranged to connect inside circular arc parts and outside circular arc parts of plural concentrical circular arc parts 3a having a different diameter in a plane shape in the resistance heating elements in order so that the resistance heating elements are continued in a series form each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer heating apparatus used in plasma CVD, low pressure CVD, plasma etching, photo etching apparatus and the like.

[0002]

2. Description of the Related Art In semiconductor manufacturing equipment requiring a super clean state, a corrosive gas such as chlorine gas or fluorine gas is used as a deposition gas, an etching gas and a cleaning gas. Therefore, as a heating device for heating the wafer in contact with these corrosive gases, if a conventional heater in which the surface of the resistance heating element is covered with a metal such as stainless steel or Inconel is used, The exposure to the above-mentioned gas produces undesired particles such as chlorides, oxides and fluorides having a particle size of several μ.

Therefore, an infrared lamp is installed outside the container exposed to the deposition gas and the like, and an infrared transmitting window is provided on the outer wall of the container to radiate infrared rays to a heated object made of a material having good corrosion resistance such as graphite. An indirect heating type wafer heating device for heating a wafer placed on the upper surface of an object to be heated has been developed.

However, in this type, the heat loss is larger than that in the direct heating type, the temperature rise takes a long time, and the transmission of infrared rays is gradually hindered by the adhesion of the CVD film to the infrared transmitting window. However, there has been a problem that heat absorption occurs in the infrared transmitting window and the object to be heated cannot be sufficiently heated.

In order to solve the above problems, the present inventors have studied a heating device in which a resistance heating element is newly embedded in a disc-shaped dense ceramic and the ceramic heater is held in a graphite case. As a result, this heating device was found to be an extremely excellent device that eliminated the above-mentioned problems.

[0006]

However, a new problem has arisen in the temperature control of such a disk-shaped ceramics heater. That is, when the resistance heating element is embedded in the ceramics base material of the ceramics heater, the resistance heating element has a spiral shape and a constant pitch in order to make the heating surface of the wafer uniform.

However, in such a spiral-shaped resistance heating element having a constant pitch, a portion where the resistance heating element is not buried is always generated in the outer peripheral portion of the heater, and the surface area of the equipment with respect to the amount of heat generated by the buried resistance heating element, That is, the area through which heat escapes becomes large, and this portion becomes a cool spot on the heating surface of the semiconductor wafer, making it difficult to uniformly heat the semiconductor wafer.

FIG. 6 is a diagram showing an example of such a ceramic heater. In FIG. 6, the disc-shaped heating device 1 has a structure in which a resistance heating element 3 made of tungsten or the like is spirally embedded inside a dense and gas-tight inorganic base material 2 such as silicon nitride. Electric power is supplied to the resistance heating element 3 from the end 4 on the center side and the end 5 on the peripheral edge side of the resistance heating element 3 via the lead wire 6 shown in FIG. 2 to heat the disc-shaped heating device 1. You can

As described above, in the spiral structure having a constant pitch, a cool spot is formed in the area C shown in the figure.

It is an object of the present invention to provide a semiconductor wafer heating apparatus which can make the temperature of the wafer heating surface more uniform in the disk-shaped ceramic heater using such a resistance heating element.

[0011]

In order to achieve this object, a semiconductor wafer heating apparatus of the present invention is a semiconductor wafer having a disk-shaped ceramic base material and a resistance heating element embedded inside the ceramic base material. In the heating device, a plurality of concentric arc portions having different diameters in the plane shape of the resistance heating element, and a connecting portion that connects the inner arc portion and the outer arc portion so that the resistance heating element forms a series. It is characterized by being provided.

[0012]

According to this structure, by providing concentric circles also in the resistance heating element on the outermost periphery, the surface area of the base material with respect to the amount of heat generated by embedding the resistance heating element, that is, the area through which heat escapes can be made constant. Therefore, the cool spot on the heating surface can be eliminated, and the heating surface of the semiconductor wafer can be heated more uniformly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor wafer heating apparatus of the present invention will be described with reference to FIGS. Referring to FIG. 1, a disk-shaped heating device 1 includes a resistor 3 made of tungsten or the like inside a dense and gastight inorganic substrate 2 such as silicon nitride.
Is embedded in a spiral shape. The resistor 3 has
A concentric arc portion 3a having a different diameter and a connecting portion 3b for connecting the outer arc portion 3a and the inner arc portion 3a are provided so that the resistor 3 becomes a series. From the viewpoint of heat uniformity, it is preferable that the pitch Pa of the arc portion and the pitch Pb of the connection portion be substantially the same. It is possible to heat the disc-shaped heating device 1 to, for example, about 1000 ° C. by externally supplying electric power from the end portion 4 on the center side and the end portion 5 on the peripheral edge side of the resistor 3 via the conductive wire 6 shown in FIG. .

FIG. 2 is a sectional view showing a state in which the heating apparatus 1 of this embodiment is attached to a thermal CVD apparatus for semiconductor production. As shown in FIG. 2, a wafer heating surface 7 is formed on the upper surface of the heating device 1. The size of the wafer heating surface 7 is, for example, 4 to 8 inches, and is set to have the same diameter as the wafer W or a size that can be set. 8 is thermal CVD for semiconductor manufacturing
The heating device 1 is fixed to the chamber 8. The bottom of the chamber is closed by a flange 9.

The material of the inorganic base material 2 must be a dense body in order to prevent adsorption of the deposition gas, and a material having a water absorption rate of 0.01% or less is preferable. In addition, thermal shock resistance that can withstand heating and cooling from room temperature to 1000 ° C is required, although mechanical stress is not applied. From these points, it is preferable to use a silicon nitride sintered body, sialon, aluminum nitride, or the like, which is a ceramic having high strength at high temperature.

Further, the substrate 2 is hot pressed or H
Firing by the IP method is effective in obtaining a dense body.

In addition, it is necessary to prevent the invasion of alkaline earth metals in the semiconductor manufacturing equipment, and it is preferable not to use alkaline earth metals such as magnesium as a sintering aid for the substrate 1. Yttria, alumina, ytterbium. Systems are preferred.

As the resistance heating element 3 embedded in the base body 2, it is suitable to use tungsten, molybdenum, platinum or the like which has a high melting point and is excellent in adhesion to silicon nitride. As the resistance heating element, a wire rod, a thin sheet, or the like is used. It is preferable that the wafer heating surface 7 is a smooth surface, and especially when the wafer W is directly set on the wafer heating surface 7, the flatness is 500 μm.
It is desirable to prevent the deposition gas from entering the back surface of the wafer W by setting m or less.

FIG. 3 is a diagram showing another embodiment of the semiconductor wafer heating apparatus of the present invention. The apparatus of this embodiment is configured by two lines of lines connecting the resistance heating elements 3 near the center and one line of the outermost circumference. That is, the innermost concentric circular arc portions 3a1 and 3a2 are connected by the connecting portion 3c in the same direction, and the innermost concentric circular arc portion 3a is connected.
The other end of 1 is connected to the opposing ends of the concentric arc portions 3a3 of the third row, and in this manner, the second row and the fourth row, the third row and the fifth row, and the fourth row are sequentially skipped. The concentric circular arc portions of the sixth and sixth rows are connected on opposite sides. Further, the other end of the concentric arc portion in the sixth row is connected to the terminal 9 and the other end of the concentric arc portion in the fifth row is connected to the terminal 10. Further, one end of the concentric arc portion in the seventh row is connected to the terminal 11, and the other end is connected to the terminal 9.

In heating the resistance heating element 3, the apparatus of this embodiment can employ a two-step heating method. That is, one of them is a method of supplying power from the terminals 9 and 10. In this case, the area from the innermost concentric arc 3a1 to the concentric arc 3a2 in the sixth column can be heated. The other is a method of supplying power from terminals 9 and 10, 11. In this case, the region from the innermost concentric circular arc 3a1 to the outermost concentric circular arc 3a7 can be heated.

Thus, by dividing the heating region into two stages, it is possible to perform appropriate heating while maintaining the uniform heating property of the heating surface in accordance with the size of the semiconductor wafer to be heated. In addition, since the heating device of this embodiment has a structure in which the series of spiral shapes of the resistance heating element 3 are folded back at the central portion, the terminals 9, 10 and 11 can be provided in the vicinity of the outer periphery of the disk-shaped heating device, and therefore, in general, In addition to the above terminals, a planar terminal or the like can be used, which is advantageous in supplying electric power to the resistance heating element, and is also effective in making the wafer heating apparatus compact.

FIG. 4 is a diagram showing still another embodiment of the semiconductor heating apparatus of the present invention. The heating device of this embodiment is
Similar to the device of the embodiment shown in FIG. 1, terminals 12 and 13 for power supply are provided at one end of the innermost concentric arc portion and the other end of the outermost concentric arc portion, respectively. The terminal 14 is provided on the.

Also in this embodiment, the heating region can be divided into two stages for heating, as in the apparatus of the embodiment shown in FIG. That is, in heating, if power is supplied from the terminals 12 and 13, the entire region of the resistance heating element 3 can be heated, and if power is supplied from the terminals 12 and 14, the region from the terminal 12 to the terminal 14 can be heated.

Next, the results of a comparative test of the temperature distribution during heating of the wafer heating surface of the semiconductor wafer heating apparatus of the present invention will be described.

FIG. 5 is a diagram showing an apparatus used for the comparative test. In the decompression chamber 15, the heating device of the present invention or the heating device 16 of the comparative example is fixed. Electricity is supplied to the heating device 16 through a lead wire 17. An opening 18 is provided at the bottom of the decompression chamber, a sapphire window 19 is fixed to the opening 18, and an infrared camera 20 is arranged below the window 19.

As a comparative example, a resistance heating element according to the present invention in which the buried shape is a concentric circular arc and has one zone is used as a comparative example A.
In the case of 1 and 2 zones, A 2 was used, while in comparison, the resistance heating element having a spiral embedded shape was used as Comparative Example B.

For the measurement, the inside of the decompression chamber was set to 10-5.
After reducing the pressure to torr and supplying power to the heating device 16 to heat, the temperature distribution of the semiconductor heating surface was measured with an infrared camera through the window 19 of the sapphire. The measured value represents the temperature distribution on the surface of the wafer heating surface when the heater center temperature was heated to 400 ° C. in width.

Table 1 shows the test results.

[Table 1] As shown in Table 1, in the heating device of Comparative Example B in which the embedded shape of the resistance heating element was spiral, the temperature distribution width of the wafer heating surface was 34 ° C., while the embedded shape of the resistance heating element was concentric. The arc-shaped one has a temperature distribution width of 16 ° C on the wafer heating surface.
The heating device of Comparative Example A1 according to the present invention has the following temperature distribution width of the heating device of Comparative Example B. In addition, the temperature range of the wafer heating surface was further reduced to 10 ° C. by setting the heating zone in two zones.

The width of the temperature distribution of the heating device of Comparative Example B, in which the resistance heating element is formed in a spiral shape, has a wide temperature distribution width because there is a portion where the resistance heating element is not embedded in the outer peripheral portion, and this portion is a cool spot. This is because

[0030]

As described in detail above, according to the semiconductor wafer heating apparatus of the present invention, a plurality of concentric arc portions having different diameters in the plane shape of the resistance heating element and the resistance heating element are arranged in series. Since a connecting portion for sequentially connecting the inner arc portion and the outer arc portion to each other is provided, while maintaining the advantage of low heat loss in the semiconductor wafer heating device in which the resistance heating element is embedded in the dense ceramics, Since the temperature distribution width of the wafer heating surface during heating can be made extremely small, more uniform heating can be achieved during heating of the semiconductor wafer.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a semiconductor wafer heating apparatus of the present invention.

FIG. 2 is a vertical cross-sectional view of the heating device of FIG.

FIG. 3 is a perspective view showing another embodiment of the semiconductor wafer heating apparatus of the present invention.

FIG. 4 is a perspective view showing still another embodiment of the semiconductor wafer heating apparatus of the present invention.

FIG. 5 is a cross-sectional view showing an apparatus used for a comparative test of the temperature distribution on the heating surface of the semiconductor wafer heating apparatus of the present invention.

FIG. 6 is a plan view showing an example of a conventional semiconductor wafer heating apparatus.

[Explanation of symbols]

 1 Disk-shaped heating device 2 Base material 3 Resistance heating element 3a, 3a 1 to 7 Concentric arc part 3b Connection part 4, 5 End part 6 Conductor wire 7 Wafer heating surface W Wafer 8 Semiconductor heating chamber 9, 10, 11, 12 , 13, 14 Terminal 15 Decompression chamber 16 Heating device 17 Conductor 18 Opening 19 Sapphire window 20 Infrared camera

Claims (1)

[Claims] 1. A semiconductor wafer heating apparatus having a disk-shaped ceramic base material and a resistance heating element embedded inside the ceramic base material, wherein a plurality of concentric arcs having different diameters are formed in a planar shape of the resistance heating element. A semiconductor wafer heating apparatus comprising: a portion; and a connecting portion that sequentially connects an inner arc portion and an outer arc portion so that the resistance heating element is a series.