JPH10149874A - Resistance heating heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistance heating heater capable of satisfactorily applying heat treatment to a semiconductor wafer without generating large temperature irregularities on the surface of the heater. SOLUTION: This resistance heating heater 1 is constituted of a heater main body 2 made of a C/C composite and a silicon carbide film 3 covered and formed on the radiation face of the heater main body 2 by chemical vapor deposition. The silicon carbide film 3 is strongly oriented on the (220) plane of (111) plane in the Miller indices so that the X-ray diffraction intensity ratio becomes 90% or above at the peak intensity. Thus, the electric resistance value, heat conductivity and thermal strain (thermal expansion) are unified by aligning the crystal orientation of the silicon carbide film 3, no large temperature irregularities are generated on the film surface, i.e., heater surface, and the temperature of the film surface can be kept uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance heating heater used for directly heating a semiconductor wafer in a semiconductor manufacturing apparatus. The present invention relates to a resistance heating heater coated with a silicon carbide film.

[0002]

2. Description of the Related Art In a film forming process, an oxidizing process, an annealing process and the like by a semiconductor manufacturing apparatus, as shown in FIG. 4, a semiconductor wafer 10 supported by an appropriate jig 11 is generally made of graphite or C / C composite. (Carbon fiber reinforced carbon composite material) or the like is directly heated by a resistance heating heater 1. However, graphite or the like as a resistance heating material contains unavoidable impurities. 1 may contaminate the semiconductor wafer 10.

Therefore, it has been conventionally proposed to cover the heater surface with a high-purity silicon carbide film by chemical vapor deposition (CVD) so as to prevent the emission of contaminants from the heater.

[0004]

By the way, in the above-mentioned semiconductor wafer heat treatment step, the semiconductor wafer 10
It is extremely important to uniformly heat-treat the surface of the heater. Therefore, it is required to strictly control the surface temperature of the resistance heating heater 1.

However, depending on the resistance heating heater 1 whose surface is covered with a silicon carbide film, the heat generation temperature on the film surface is not uniform, and large temperature unevenness occurs, resulting in uneven heat radiation from the film surface. The fact is that the heat treatment of the semiconductor wafer 10 could not be performed well. The temperature unevenness on the film surface refers to the temperature difference between the highest temperature point and the lowest temperature point on the film surface when the temperature at a certain point on the film surface is kept constant, and is covered with a silicon carbide film. In the conventional heater described above, generally, 3
It has been pointed out that temperature unevenness of 0 ° C. or more occurs.

Accordingly, the present inventor has conducted various experiments and studies in order to investigate the cause of the temperature unevenness on the film surface. As a result, the crystal unevenness of the carbon silicon film, which is a chemical vapor deposition film, has been found. Was found to be due to

That is, when silicon carbide is chemically vapor-deposited under ordinary film-forming conditions, the crystal plane of the vapor-deposited film becomes non-oriented or weakly oriented to the (111) plane in Miller index. The crystal orientation varies. On the other hand, since silicon carbide is a kind of semiconductor material, when the heater 1 generates heat and heats the silicon carbide film, the conductivity of the silicon carbide film improves as the temperature increases. Therefore, when the silicon carbide film is non-oriented or weakly oriented to the (111) plane, the electric resistance value varies depending on the crystal orientation, the heat generation state of the silicon carbide film is not uniform, and the temperature is uneven. Will occur.
Furthermore, since the thermal conductivity depends on the crystal orientation,
The thermal conductivity of the silicon carbide film varies depending on the crystal orientation, and the heat distortion (thermal expansion) of the silicon carbide film due to the heat generated by the heater is not uniform, and the film surface is deformed into a wavy uneven surface. Become. When the surface of the film undulates in this manner, radiation from the surface of the film naturally becomes non-uniform, and this also causes uneven temperature. Of course, such a non-uniform phenomenon of thermal strain on the film surface becomes more remarkable when the heat generation state becomes non-uniform due to the difference in electric resistance as described above.

As described above, the silicon carbide film is non-oriented or (1)
11) In a silicon carbide film having a weak orientation to the plane, since the crystal orientation is different, the electric resistance value, the thermal conductivity, and the thermal strain become non-uniform. Heat is not generated uniformly, and temperature unevenness occurs on the film surface.

SUMMARY OF THE INVENTION The present invention has been made based on the above findings, and it is an object of the present invention to provide a resistance heating heater capable of performing a heat treatment of a semiconductor wafer satisfactorily without causing large temperature unevenness on the surface of a silicon carbide film. It is assumed that.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a resistance heating heater in which a silicon carbide film is formed by chemical vapor deposition on a heat radiation surface of a heater body made of a carbonaceous material. The silicon film is placed on one crystal plane specified by Miller index (hereinafter referred to as “oriented plane”)
It is proposed that the material is strongly oriented so that the line diffraction intensity ratio is 90% or more in peak intensity. The plane to be oriented can be arbitrarily selected according to the deposition conditions and the like, but it is generally preferable that the plane is strongly oriented to the (220) plane or the (111) plane in Miller index display.

Here, the X-ray diffraction intensity ratio of the plane to be oriented is
Strictly speaking, in the peak intensity measured by an X-ray diffractometer (corrected by the powder X-ray diffraction value based on the US ASTM standard), the orientation is determined based on the sum of the peak intensities in all the crystal planes including the orientation plane. It refers to the ratio of the peak intensity of the plane, and generally, the degree of orientation of the crystal plane is (111)
Since the (220) plane is the highest following the plane, in the following description, for convenience, when the plane to be oriented is a (220) plane other than the (111) plane,
It refers to the ratio to the total peak intensity of the plane to be oriented and the (111) plane, and when the plane to be oriented is the (111) plane, the ratio to the total peak intensity of the plane to be oriented and the (220) plane. Shall be referred to. So, for example,
If the plane to be oriented is the (220) plane or the like and the X-ray diffraction intensity ratio is 90%, it means that the (111) plane has an X-ray diffraction intensity ratio of 10%. The plane to be oriented is the (111) plane, and its X-ray diffraction intensity ratio is 90%.
Means that the X-ray diffraction intensity ratio of the (220) plane is 10%.

As described above, the silicon carbide film is chemically oriented on the heat radiating surface of the heater main body in a state where the silicon carbide film is strongly oriented on one surface to be oriented, that is, when the X-ray diffraction intensity ratio of the surface to be oriented is 90% or more. By vapor deposition, the temperature of the film surface is made uniform, and no large temperature unevenness occurs.

That is, in the silicon carbide film, since the crystal orientation is aligned with the direction of the plane to be oriented, the electric resistance value and the thermal conductivity are uniform at any point of the silicon carbide film. As a result, the heat generation state and heat distortion on the film surface become uniform. As a result, the occurrence of temperature unevenness on the film surface is suppressed as much as possible.

By the way, as the degree of orientation on the surface to be oriented increases, that is, as the X-ray diffraction intensity ratio of the surface to be oriented increases, the uniformity of the electrical resistance and thermal conductivity of the silicon carbide film increases. The uniformization of the film surface temperature is further promoted. In particular, the X-ray diffraction intensity ratio of the plane to be oriented is 95%.
With the above, the temperature unevenness on the film surface is reduced to an almost negligible level, and the heat treatment of the semiconductor wafer can be performed extremely well. Therefore, when a semiconductor wafer is heat-treated by using a resistance heating heater coated with a silicon carbide film having an X-ray diffraction intensity ratio of 95% or more on the plane to be oriented, other manufacturing steps are considered to be appropriate. By doing so, the highest quality semiconductor can be obtained. From this point, it is more preferable that the X-ray diffraction intensity ratio of the plane to be oriented is 95% or more. Theoretically, it is most preferable to set the X-ray diffraction intensity ratio of the plane to be oriented to 100%. However, in a strict sense, the silicon carbide film with the X-ray diffraction intensity ratio of the plane to be oriented being 100% is a single crystal film. Therefore, in practice, the X-ray diffraction intensity ratio of the plane to be oriented is not limited to 100%. It is most preferable to keep them close.
In addition, the surface to be oriented can be arbitrarily selected as described above without any particular difference from the surface of the heat generation function inherent in the heater. In consideration of properties and the like, it is more preferable that the (220) plane be strongly oriented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

That is, the resistance heating heater 1 according to the present invention.
As shown in FIG. 1 and FIG. 2, a heater body 2 is a resistance heating element made of a carbonaceous material, and a silicon carbide film 3 is formed on a heat radiation surface by chemical vapor deposition.

As shown in FIG. 1, the heater main body 2 is
To form a thin disk made of carbonaceous material.
Reverse direction spirally extending from the vicinity of the center point A toward the outer periphery
Are formed by forming the slits 4a and 4b. sand
That is, the heat generating portions 5a, which are spiral band-shaped portions made of carbonaceous material,
5b is a center point in the opposed state sandwiching the slits 4a and 4b.
A extends in the opposite direction from A. Each heating part 5
a, 5b are connected to a current-carrying electrode (carbon
The current-carrying parts 6a and 6b for attaching and connecting electrodes
And by energizing the energizing sections 6a and 6b.
Therefore, the heater body 2, that is, the heat generating portions 5a and 5b generate resistance heat.
It is supposed to be. The slits 4a and 4b
The peripheral shapes of the chair heating parts 5a and 5b are the center point A and the energized state.
Symmetry with respect to the horizontal center line XX passing through the portions 6a and 6b
It has an arc shape, and in FIG. 1, the horizontal center line XX
On the upper side of the line, the first
Point O ₁A semi-circular shape centered on the center line, and the horizontal center line XX
On the lower side, the second point located on the left side of the center point A
O_TwoIn the form of a semicircle centered at. First point O₁When
2nd point O_TwoIs located on the horizontal center line XX,
The same amount L is deviated in the opposite direction from the center point A. Also,
Width W of lits 4a and 4b₀Is the width W of the heat generating portions 5a and 5b.
Very small compared to. The thickness of the slit body 2
Is appropriately set in consideration of its outer diameter, rigidity,
It is generally set to about 1 to 5 mm
Is preferred.

As a constituent material of the heater main body 2, any carbonaceous material generally used as a constituent material of a resistance heating element can be used.
^{-2 ~10 -3 Ω} · ^- cm approximately a C / C composite, sintered graphite, pyrolytic graphite, reaction sintering silicon carbide, pressureless sintering of silicon carbide, hot press sintering silicon carbide or the like is used.

The silicon carbide film 3 is formed by chemical vapor deposition with a uniform thickness on the heat radiating surface of the heater body 1, that is, on both surfaces of the heat generating portions 5a and 5b except for the conductive portions 6a and 6b. Thus, the silicon carbide film 3 is strongly oriented so that the X-ray diffraction intensity ratio is 90% or more on one surface to be oriented by controlling the deposition conditions. The planes to be oriented include (220) plane and (111) plane in Miller index notation.
Plane, (200) plane and the like can be arbitrarily selected. The strong orientation on the surface to be oriented is performed by appropriately controlling the deposition temperature, the film forming speed, and the like according to the conditions such as the surface to be oriented and the film thickness. Specifically, when the (220) plane is strongly oriented, for example, in a non-oxidizing atmosphere, the deposition temperature is 1300 to 1500 ° C., and the film formation rate is 10 to several tens μm / h.
Chemical vapor deposition is performed under the following conditions. When the (111) plane is strongly oriented, for example, chemical vapor deposition is performed in a reduced-pressure atmosphere of about 30 mmHg at a film forming rate of about 50 μm / hr. Note that, depending on the deposition conditions, a silicon carbide film may also be formed on the arc-shaped side surfaces of the heat-generating portions 5a and 5b opposed to each other across the slits 4a and 4b, and such arc-shaped side surfaces are shown in FIG. In the heat treatment of the semiconductor wafer 10 performed in such a form, there is no heat dissipation surface, and the presence or absence of the formation of the silicon carbide film does not bring about any particular advantage or disadvantage. Of course, it is also possible to devise the deposition conditions so that the silicon carbide film is not formed on the arcuate side surface or the silicon carbide film is formed on the opposite side.

As a constituent material of the silicon carbide film 3, high-purity silicon carbide is used. Generally, β-type silicon carbide is preferably used. The thickness of silicon carbide film 3 is generally at least 20 μm, more preferably at least 50 μm, and preferably at most 200 μm. That is, when the film thickness is less than 20 μm, pinholes are generated in the silicon carbide film, and there is a possibility that the heater main body 2 is oxidized and reduced, and it is difficult to guarantee the heater life. In consideration of the oxidation consumption of the silicon carbide film 3 itself and the adhesive strength (non-peeling property) to the heater body as a base material, it is more preferable to set the film thickness to 50 μm or more in view of the heater life. Further, the silicon carbide film 3 needs to cover the heat radiating surface of the heater body 2 with a uniform thickness, but if the film thickness exceeds 200 μm, the silicon carbide film 3 having a uniform thickness may be formed. It is difficult, and on the contrary, the uniformity of heat generation may be impaired, and it is economically useless.

The resistance heating heater 1 according to the present invention comprises:
The present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention. In particular, the shape of the heater main body 2 can be arbitrarily changed according to the shape of the semiconductor wafer 10 and the like, for example, as shown in FIG. That is, in the example shown in FIG. 3A, the entire heater main body 2 has a disk shape, and a plurality of linear slits 4c... The portion 5c is formed in a meandering shape.
In addition, in the one shown in FIG. 2B, the entire heater main body 2 has a rectangular plate shape, and a plurality of straight lines extending alternately in parallel in the facing direction similarly to the one shown in FIG. The strip-shaped heat generating portions 5d are formed in a meandering shape by the slits 4e, 4f. Further, in FIG. 9C, a single strip-shaped heat generating portion 5e is spirally formed by a single spiral slit 4g. In this case, one energizing section 6 b is formed at the center of the heater main body 2.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment, four heater bodies 2 are shown in FIG.
(Plate thickness: 8 mm, center point A and first point O ₁₎
Alternatively, the distance L from the second point O ₂ is 14 mm, and the heat generating portions 5a and 5
b width W: 25 mm, slits W 4, 4 b width W ₀ : 3
mm, the outermost peripheral edge of the arc radius of the heat generating portion 5b around the arc radius and the second point O ₂ of the outermost peripheral edge of the heat generating portion 5a around the first point O _1: 175mm) to Toyo Tanso Co. Each heater body 2 is manufactured using sintered carbon (IG11).
High-purity β-type silicon carbide was chemically vapor-deposited on both surfaces of the heat-generating portions 5a and 5b, which are heat-radiating surfaces, to obtain heaters 11 to _{14 according} to the _first to _fourth embodiments of the present invention. At this time, by controlling the deposition conditions in each separate, crystal planes in the silicon carbide film 3, first in Example heater 1 ₁ (220) plane to the X-ray diffraction intensity ratio of 95
% ((111) X-ray diffraction intensity ratio of the face 5%) and a way is allowed strong orientation, the second embodiment in the heater 1 ₂ (11
1) The X-ray diffraction intensity ratio of 95% (X of the (220) plane)
Line diffraction intensity ratio is 5%).
Third Embodiment In the heater 1 ₃ (220) plane to the X-ray diffraction intensity ratio of 90% ((111) plane X-ray diffraction intensity ratio of 10
%) And so as to be brought into strong orientation, the fourth embodiment in the heater 1 ₄ (111) plane to the X-ray diffraction intensity ratio of 90%
(The X-ray diffraction intensity ratio of the (220) plane is 10%). The thickness of silicon carbide film 3 in each heater was 250 μm.

As a comparative example, the same shape as in the above embodiment was used.
And five heater bodies 2 of the same material are manufactured.
Silicon carbide of the same material as the above embodiment
The first to fifth comparative example heaters 1 'are formed by chemical vapor deposition.₁~ 1 '_Five
I got At this time, as in the above embodiment,
By controlling the conditions separately, the crystal plane in silicon carbide film 3
However, the first comparative example heater 1 ′₁Then, on the (220) plane,
X-ray diffraction intensity ratio of 80% (X-ray diffraction intensity ratio of (111) plane is
20%).
Ta1 '_TwoThen, the (111) plane has an X-ray diffraction intensity ratio of 80%
(X-ray diffraction intensity ratio of (220) plane is 20%)
And the third comparative example heater 1 ′ _ThreeThen (22
The (0) plane has an X-ray diffraction intensity ratio of 50% (X of the (111) plane).
Line diffraction intensity ratio is 50%).
Fourth comparative example heater 1 '_FourThen the (111) plane shows the X-ray
The folding intensity ratio is 50% (the X-ray diffraction intensity ratio of the (220) plane is 50%).
%) So that it can be oriented strongly.
5 Comparative example heater 1 '_FiveNow, the crystal plane in silicon carbide film 3
Was made non-oriented. The charcoal in each heater
The thickness of the silicon oxide film 3 was the same as in the above-described embodiment.

[0024] Then, by energizing the respective examples heater ₁ 1 to 1 ₄ and Comparative Example heaters _1'1 ～1' _5, using optical pyrometer (the Chino Co. IRU), in the membrane surface of each heater While maintaining the average temperature of the central portion A at 1500 ° C., FIG.
The temperature at five points B to E shown in FIG.
The temperature difference (temperature unevenness) between the highest temperature point and the lowest temperature point in the points A to E was determined. A, B, D and E are points on the horizontal center line XX, and C and F are points on the vertical center line YY passing through the center point A and orthogonal to the horizontal center line XX. It is.

As a result, the third or fourth comparative example heaters 1 ′ ₃ , 1 ′ ₄ or silicon carbide film 3 in which the oriented (220) plane or (111) plane has an X-ray diffraction intensity of 50% is 50%.
There In the fifth comparative example 1 _'5 is a non-oriented, temperature unevenness exceeds a much a 30 ° C.. On the other hand, oriented (220)
Or 1st comparative example heater 1 ′ ₁ , 1 in which the X-ray diffraction intensity of the plane or the (111) plane is 80% which is close to 90%.
In ' ₂ , the temperature unevenness was slightly smaller than 30 ° C. As described above, in the comparative example heaters 1 ′ _{1 to 1} ′ ₅ , the temperature unevenness was at least about 30 ° C., and it was confirmed that the temperature unevenness was insufficient for performing the heat treatment of the semiconductor wafer satisfactorily.

[0026] In contrast, Example heater ₁ 1 to 1 ₄ in which is strongly oriented in the film crystal plane (220) plane or (110) plane
In each case, the temperature unevenness on the film surface was 15 ° C. or less, and it was confirmed that the occurrence of temperature unevenness was effectively suppressed. In particular, the strongly oriented (220) plane or (1)
11) faces the first or the second embodiment the heater 1 _1, 1 ₂ X-ray diffraction intensity is 95%, is below the detection limit (10 ° C.) by an optical pyrometer the temperature unevenness can be determined However, at least it is clear that the temperature unevenness is less than 10 °, and the temperature unevenness hardly occurs, or even if it occurs, it is extremely negligible compared to the heat generation temperature (1600 ° C.). It is easily speculated that it is small.

From the above, the X-ray diffraction intensity ratio of the crystal plane of the film to one plane to be oriented is 90% or more (more preferably, 9%).
(5% or more)
The heat generation temperature on the film surface can be made as uniform as possible,
It was confirmed that heat radiation from the heater could be performed uniformly. Also, there is no difference in the effect of equalizing the film surface temperature depending on the difference in the orientation surface, and the degree of the effect is mainly due to the degree of orientation of the orientation surface, that is, the level of the X-ray diffraction intensity ratio of the orientation surface. It is understood that as the X-ray diffraction intensity ratio increases, the effect of uniformizing the film surface temperature is more remarkably exhibited.

[0028]

As can be easily understood from the above description, the resistance heating heater according to the present invention has an electric resistance value, thermal conductivity,
Since thermal distortion (thermal expansion) is made uniform, large temperature unevenness does not occur on the film surface as the heater surface, and the temperature on the film surface can be maintained uniformly.
Therefore, by using the resistance heating heater of the present invention, a semiconductor wafer can be heat-treated uniformly and well, the temperature can be controlled accurately and appropriately, and a high-quality semiconductor can be manufactured. it can.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a resistance heating heater according to the present invention.

FIG. 2 is a vertical sectional side view of a main part of the heater.

FIG. 3 is a plan view showing a modification of the resistance heating heater.

FIG. 4 is a vertical sectional side view showing a positional relationship between the semiconductor wafer and a resistance heating heater in a heat treatment step of the semiconductor wafer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Resistance heating heater, 2 ... Heater main body, 3 ... Silicon carbide film, 4a, 4b, 4c, 4d, 4e, 4f, 4g ... Slit, 5a, 5b, 5c, 5d, 5e ... Heating part, 6a,
6b ... energizing section.

Claims (2)

[Claims] In a resistance heating heater in which a heat-dissipating surface of a heater body made of a carbonaceous material is formed by coating a silicon carbide film by chemical vapor deposition, the silicon carbide film is formed on one crystal plane specified by Miller index. A resistance heating heater characterized in that it is strongly oriented so that its X-ray diffraction intensity ratio becomes 90% or more in peak intensity. 2. The resistance heating heater according to claim 1, wherein the one crystal plane is a (220) plane or a (111) plane in Miller index notation.