JP2004055896A - Heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device which can heat the entire surface of a wafer uniformly and is excellent in soaking property. <P>SOLUTION: The heating device has a reaction container and a heating element disposed planar inside the reaction container. It makes the heating element generate heat by energization to a high frequency induction coil wound on the heating element and heats a workpiece. The high frequency induction coil is formed by winding a coil strand outside the reaction container. The high frequency induction coil is provided with a pair of plane parts wherein the coil strand is arranged parallel inside a pair of surfaces parallel to an installation part of the heating element. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating apparatus provided in, for example, a low-pressure CVD apparatus, which can be suitably used for performing a heating process on a wafer.
[0002]
[Prior art]
As is well known, various IC process devices such as an oxidation / diffusion treatment device, a vapor phase epitaxial growth device, a low pressure CVD device (LPCVD device), and an annealing device are used in a semiconductor integrated circuit manufacturing process. These devices are provided with a heating device for heating the silicon wafer.
[0003]
In the above-described heating apparatus, a radiant heating method using an electric heater or a lamp or an induction heating method using induction heating is generally used as a heating means. The radiation heating method has an advantage that a large number of wafers can be processed at one time, but the electric heater method has a problem that rapid heating is difficult and it takes time to cope with a high heat treatment of 500 to 1200 ° C. In addition, in the lamp method, the life of the lamp is problematic, and a large number of lamps are required to improve the uniformity of the wafer (the temperature distribution does not occur in the wafer). There was a problem that it was not suitable for mass processing because it could not be heated.
[0004]
On the other hand, in the induction heating method, a heating element capable of generating heat by induction heating is used as a wafer support plate called a susceptor, and the support is heated by a high-frequency induction coil installed on the lower surface of the support, and is directly placed on the support. This is a method for directly heating a wafer that has been heated, and has the advantage that rapid heating is possible.
[0005]
FIG. 5 shows a cross-sectional explanatory view of a heating device using a conventional induction heating method. In the heating device 30, a disk-shaped support plate (susceptor; made of, for example, graphite) 33 on which wafers 32 are placed one by one is arranged in a reaction vessel 31 made of, for example, quartz glass or the like. At a position below the support plate 33 outside the reaction vessel 31, a high-frequency induction coil 34 for heating the support plate 33 and directly heating the wafer 32 placed thereon is provided in a circumferential direction of the support plate 33. Is spirally wound along. The power supply was omitted. An openable / closable gas supply port 35 for introducing a reaction gas or the like is provided on the left side of the reaction vessel 31, and an exhaust port 36 is provided on the opposite side thereof. It is configured to be able to flow while forming a substantially laminar flow on the surface.
[0006]
However, in the conventional induction heating device 30 shown in FIG. 5, since the spiral high-frequency induction coil is provided, the central portion of the support plate 33 cannot be sufficiently heated, and the uniform heating property is not obtained. There was a problem of inferiority. The fact that the heating device has poor thermal uniformity means that when a silicon epitaxial layer is formed on the wafer surface by vapor phase growth, the state of formation of the epitaxial layer becomes non-uniform, which is a problem. Further, in the heating device 30, only one support plate 33 can be provided due to the magnetic field formed by induction heating, and there is a problem that the efficiency of the heat treatment of the wafer 32 is inferior.
[0007]
[Problems to be solved by the invention]
In order to solve the above problems, the present inventors have formed a cylinder with a heating element, arranged this cylindrical heating element inside the reaction vessel, and provided a high-frequency induction coil along the outer periphery of the reaction vessel. A heating device having a wound configuration has been invented and has already been filed (Japanese Patent Application No. 2001-351579). FIG. 6 shows a schematic sectional view of the heating device of this application. The heating device 40 includes a reaction vessel 41 made of quartz, which is closed in a dome shape with a circular cross section, a glass-like carbon cylinder 42 provided in the reaction vessel 41, A manifold 45 is provided on the inside, and a wafer mounting board 44 for mounting a large number of wafers 43 in the vertical direction. Further, the heating device 40 includes an air-core coil-type high-frequency induction coil 47 (a power supply device and a temperature control device are omitted) that is disposed concentrically with the outside of the reaction vessel 41. The manifold 45 includes gas injectors 47a and 47b for introducing a reaction gas and the like inside the cylindrical body 42, and has a gas exhaust port 48 for discharging a reacted gas or an unreacted gas from the reaction container 41. I have.
[0008]
The heating device 40 heats the glass body 42 made of glassy carbon by induction heating using a high-frequency induction coil 47, and heats the wafer 43 with radiant heat from the cylindrical body 42. Therefore, a large number of wafers 43 can be heated at one time, and rapid heating can be performed by using induction heating, so that the heat treatment efficiency is extremely excellent.
[0009]
However, since the radiant heat from the cylindrical body 42 is used to heat the wafer 43, it is difficult to completely eliminate the possibility that the temperature distribution in the radial direction of the wafer 43 will occur, and such a property that high uniformity is required. In the case of the heat treatment, further improvement was expected.
[0010]
Therefore, in the present invention, on the premise that a heating device utilizing an induction heating method capable of rapid heating is used, it has been set as an object to provide a heating device having excellent heat uniformity capable of uniformly heating the entire surface of a wafer.
[0011]
[Means for solving the problem]
A heating apparatus according to the present invention according to claim 1, which has solved the above-mentioned problem, includes a reaction vessel, and a heating element installed in a plane in the reaction vessel, and a high-frequency induction coil for winding the heating element. A heating device that generates heat by heating a heating element and heats an object to be heated, wherein the high-frequency induction coil is formed by winding a coil element wire outside a reaction vessel. The gist is that the coil is provided with a pair of flat portions in which the coil wires are arranged in parallel within a pair of surfaces parallel to the installation portion of the heating element.
[0012]
By arranging a pair of flat portions parallel to the heating element installation portion on the coil, an induction magnetic field is formed in the vicinity of the heating element in the same direction as the surface direction of the heating element. By employing this configuration, it has become possible to uniformly heat the entire heating element. Note that “a heating element installed in a plane” means a heating element installed in one plane, for example, one plane is formed by a heating element that is a single plate. The concept includes not only the case where two or more rod-shaped bodies or tubular bodies but also physically separated heating elements are installed so as to be located in the same plane.
[0013]
A heating device according to a second aspect is the heating device according to the first aspect, wherein two or more heating element installation portions are arranged in parallel in the reaction vessel. Even when two or more heating element installation parts are provided, since the respective magnetic fields are formed from the opposing coil plane parts, the heating elements located within the range of the action of the magnetic field are heated by induction heating. Can be.
[0014]
In the heating device according to claim 3, the heating element is made of glassy carbon. As the heating element, a material capable of generating heat by induction heating, such as graphite and metal, can of course be used, but glassy carbon is most preferable because it generates very few impurities.
[0015]
According to a fourth aspect of the present invention, there is provided a heating apparatus in which the heating apparatus according to any one of the first to third aspects and a reaction vessel having a heating element and having no high-frequency induction coil are alternately arranged. Device. Since the magnetic field is formed around the coil, by arranging the reaction vessel without the coil side by side next to the reaction vessel with the coil, the action of the magnetic field of this coil is reduced within the reaction vessel without the coil. , The heating element can also be heated.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the heating device of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view for explaining the heating device of the present invention, and FIG. 2 is a sectional view thereof. The heating device 1 has a configuration in which a rectangular parallelepiped reaction vessel 2 is housed inside a high-frequency induction coil 3. Although not shown in FIG. 1, flat heating elements 5a and 5b are installed horizontally inside the reaction vessel 2 while being vertically separated (FIG. 2).
[0017]
The high-frequency induction coil 3 is configured by winding the coil wire 4 so as to pass through the upper surface and the lower surface of the reaction vessel 2 in parallel with the installation portions of the heating elements 5a and 5b. In FIG. 1, a coil wire 4 is wound on the upper surface of the reaction vessel 2 from the other side of the drawing to the front. Although the illustration of the center of the coil 3 is omitted, the coil 3 is of course continuous. The coil 3 is connected to a high-frequency power supply (not shown). Wafers 6a and 6b are placed on the heating elements 5a and 5b, and the heating elements 5a and 5b simultaneously function as a support (susceptor).
[0018]
The point of the heating device 1 of the present invention is that the upper flat portion 3a and the lower flat portion 3b of the coil 3 are parallel to the installation portions of the heating elements 5a and 5b in the reaction vessel 2. As shown in FIG. 1, on the upper surface side of the reaction vessel 2, the coil wires 4a, 4a,... Are arranged in parallel while maintaining a linear state, and the positional relationship in the vertical direction is as shown in FIG. The fixed distance L1 from the heating element 5a is maintained. That is, the coil wires 4a, 4a,... On the upper surface side of the reaction vessel 2 are all located on the same plane. Therefore, the coil 3 formed by the coil wires 4a, 4a,... On the upper surface side of the reaction vessel 2 forms a flat surface. In the present invention, the upper flat portion 3a of the coil 3 is connected to the heating element 5a. Must be in a parallel relationship (same for lower side).
[0019]
As a result, when a high-frequency current is flowing through the coil 3 in the directions shown in FIGS. 2 and 3, the lines of magnetic force 7 a formed by the coil upper flat portion 3 a are below the coil upper flat portion 3 a on the right side of the drawing. Head left. Further, since the coil upper flat portion 3a and the heating element 5a are parallel, the magnetic force lines 7a pass over the entire surface of the heating element 5a, and the induced current flows in a direction orthogonal to the magnetic force lines 7a. Therefore, if the heating element 5a is installed at a position where the current density is the highest (at a position separated by L1 from the coil element wire 4a), the induced current flows over the entire surface of the heating element 5a, and the surface of the heating element 5a The whole is rapidly and uniformly heated.
[0020]
The principle of the uniform heating is the same for the heating element 5b on the lower side of the reaction vessel 2 and the coil lower flat part 3b. Therefore, the heating element 5b is located at the position where the current density is the highest (the coil element wire 4b). It is most preferable to dispose them at a distance of L2 from the above.
[0021]
In the present invention, since the heating elements 5a and 5b are heated according to the above principle, the coil wires 4a and 4b located on the upper flat portion 3a and the lower flat portion 3b of the coil must be linear. The coil wire 4 other than this portion, that is, the coil wire 4 located on the front and rear side surfaces of the reaction vessel 2 in FIG. 1 is at a position where the magnetic force lines 7a and 7b acting on the heating elements 5a and 5b are not adversely affected. Is preferred. Therefore, it is preferable that the trajectory of the coil 3 draws a circular arc on the front and rear side surfaces of the reaction vessel 2 so as to be as far as possible from the heating elements 5a and 5b. For this reason, it is preferable that the coil 3 has such a shape that a pair of upper and lower straight lines are connected by a pair of left and right arcs in a side view of FIG.
[0022]
In the heating device of the present invention, the pitch P of the coil wires 4 (4a, 4b) is preferably in the range of 10 to 30 mm in order to increase the uniformity of the heating element. In order to maximize the heating efficiency of the heating elements 5a and 5b, it is preferable that L1 and L2 be in the range of 10 to 40 mm. In the case where the height of the reaction vessel 2 is low and the ranges of L1 and L2 overlap, a configuration may be adopted in which one heating element is provided just in the middle between the upper and lower coils 3a and 3b.
[0023]
Further, in the heating device of the present invention, since the coil 3 has the pair of flat portions 3a, 3b parallel to the heating element (installation portion), the magnetic force lines formed by these flat portions 3a, 3b extend. If it is a position, three or more heating elements may be installed. From the viewpoint of heating efficiency, it is preferable to dispose each heating element within a range of 10 to 40 mm from the coil surface. The thickness of the heating element is not particularly limited, but is usually about 1 to several mm.
[0024]
The heating device of the present invention is a combination of the heating device 1 shown in FIG. 1 and a reaction vessel without a high-frequency induction coil, in addition to the configuration in which the heating device 1 shown in FIG. 1 is used as one unit. Can also be adopted. For example, in FIG. 4, on a heating device 11 having the same configuration as that shown in FIG. 1, a reaction vessel 20 in which two heating elements 25a and 25b are vertically arranged is disposed. 5 shows a heating device 17 having a configuration in which the heating device 14 having the same configuration as that shown in FIG.
[0025]
In the heating device 17, the heating element 25 b on the lower side of the reaction vessel 20 having no coil generates heat by an induction current formed by the coil lower flat portion 13 a of the heating device 11. 26b can be heated. Further, the heating element 25a on the upper side of the reaction container 20 generates heat by an induced current formed by the coil lower flat portion 16b of the heating device 14, so that the wafer 26a on the heating element 25a can be heated.
[0026]
The number of heating devices 11 and 14 having coils and the number of reaction vessels 20 having no coils are not limited as long as they are arranged alternately. When the reaction vessel having no coil is arranged at the bottom or the top of the apparatus, the number and arrangement position of the heating elements may be determined in consideration of the effective range of the magnetic field.
[0027]
Although the reaction vessel 2 is shown as a rectangular parallelepiped in FIG. 1, the coil 3 is arranged so that the pair of flat portions (the upper flat portion 3a and the lower flat portion 3b) of the coil 3 and the heating element installation portion are kept parallel. If wound, the shape of the reaction vessel 2 itself is not particularly limited, such as a bell shape, a cylindrical shape, and a polygonal shape. The reaction vessel 2 is usually made of quartz having high heat resistance.
[0028]
On the other hand, the heating element must be made of a material that generates heat by induction heating. Examples of such a material include metal, graphite, glassy carbon (GC) coated graphite, silicon carbide (SiC) coated graphite, and glassy carbon. Among them, carbon materials having characteristics such as light weight, heat resistance, corrosion resistance, and conductivity, which are properties of general carbon materials, are preferable, and in particular, high purity, high strength, gas impermeability, and low dust generation are preferable. Glassy carbon that does not emit impurity particles or gas even under high temperature and corrosive environment, has low gas adsorption, and is chemically stable and does not pollute the wafer is most suitable. preferable. The glassy carbon can be obtained, for example, by firing and carbonizing a cured product of a thermosetting resin in an inert gas or in a vacuum.
[0029]
The heating element is not limited to a plate-like member such as a rectangular plate or a disk, and may be a net-like member or the like. Further, a configuration in which a plurality of heating elements such as prisms or tubes are installed in parallel in the same plane can also be adopted.
[0030]
Although the heating device having a configuration in which the heating element is installed horizontally has been shown in the examples of the drawings so far, the heating device has a configuration in which the heating element is installed vertically and the left, right, front and rear sides of the reaction vessel are wound by coils. You may. In this case, the object to be heated can be quickly and uniformly heated by installing the object to be heated near the heating element in parallel with the heating element without supporting the object to be heated by the heating element.
[0031]
Of course, the heating apparatus of the present invention may include various known additional means necessary for performing a known process in a semiconductor manufacturing process involving heat treatment of a wafer, such as an atmosphere gas introduction / discharge means. Alternatively, it can be used to heat a heated object other than the wafer.
[0032]
【Example】
Example 1
A quartz plate with a diameter of 80 mm and a thickness of 10 mm is placed in a vacuum-resistant reaction vessel made of quartz having a width of 100 mm, a length of 150 mm, a height of 30 mm, and a thickness of 4 mm. A glassy carbon substrate (a disc having a thickness of 2 mm and a diameter of 65 mm) manufactured by firing was installed as a heating element. The reaction vessel was wound with a copper tube having an outer diameter of 6 mm so as to have the same coil shape as in FIG. The distance between the coil and the upper surface of the reaction vessel was 2 mm, and the same was applied to the bottom surface. The pitch of the coil wires (the distance between the centers of the copper tubes) in the upper flat portion and the lower flat portion of the coil was 10 mm, and the number of turns was 15 times.
[0033]
When a high-frequency voltage of 400 kHz and 2.5 kW was applied to the coil, the heating element (glassy carbon substrate) rose to 800 ° C. in 20 seconds. The in-plane temperature distribution of the heating element at 800 ° C. was within 5 ° C.
[0034]
Example 2
A glass-like carbon substrate having the same material and the same shape as that of Example 1 and a quartz plate having a diameter of 80 mm and a thickness of 10 mm is placed in a vacuum-resistant reaction vessel made of quartz having a width of 100 mm, a length of 150 mm, a height of 42 mm, and a thickness of 4 mm. Were alternately superposed two by two. In the same manner as in Example 1, the reaction vessel was wound with a high-frequency dielectric coil.
[0035]
When a high-frequency voltage of 400 kHz and 4 kW was applied to the coil, each of the two heating elements rose to 800 ° C. in 25 seconds. Further, the in-plane temperature distribution of the heating element at 800 ° C. was all within 5 ° C.
[0036]
Comparative Example 1
A cylindrical (dome-shaped tip) vacuum vessel having an outer diameter of 80 mm was used as a reaction vessel. A quartz tube having an outer diameter of 60 mm was disposed at the center of the bottom of the reaction vessel, and a glassy carbon substrate of the same material and the same shape as in Example 1 was placed thereon as a heating element. A copper tube coil having an outer diameter of 6 mm was wound concentrically around the reaction vessel. The distance between the inner diameter of the coil and the container was 5 mm, and the pitch of the copper tube was 10 mm.
[0037]
When a high-frequency voltage of 400 kHz and 1.2 kW was applied to the coil, the temperature of the periphery of the disk-shaped heating element rose to 800 ° C. in 20 seconds, but the center of the heating element was 600 ° C. or less. The temperature difference from the center was 200 ° C. or more.
[0038]
【The invention's effect】
Since the heating element and the pair of flat portions of the high-frequency induction coil are configured to be parallel, an induction magnetic field is formed in the same direction as the surface direction of the heating element in the vicinity of the heating element. Flow in the direction (direction perpendicular to the magnetic field). By employing this configuration, it has become possible to uniformly and rapidly heat the entire heating element.
[0039]
Therefore, the heating apparatus of the present invention is useful as a heating apparatus for heating a silicon wafer in various IC processing apparatuses such as an oxidation / diffusion processing apparatus, a vapor phase epitaxial growth apparatus, a low pressure CVD apparatus (LPCVD apparatus), and an annealing apparatus. It is.
[Brief description of the drawings]
FIG. 1 is a perspective explanatory view schematically showing a heating device of the present invention.
FIG. 2 is a schematic sectional view of the heating device of FIG.
FIG. 3 is a schematic diagram illustrating the direction of an induced magnetic field.
FIG. 4 is a schematic sectional view illustrating a heating device according to a fourth embodiment.
FIG. 5 is an explanatory sectional view of a conventional heating device.
FIG. 6 is an explanatory sectional view of a heating device according to the prior application of the present inventors.

Claims (4)

A heating device that includes a reaction vessel and a heating element disposed in a planar shape in the reaction vessel, and heats the heating element by heating a high-frequency induction coil that winds the heating element and heats an object to be heated. So,
The high-frequency induction coil is formed by winding a coil wire outside the reaction vessel,
A heating device, wherein the high-frequency induction coil is provided with a pair of flat portions in which the coil element wires are arranged in parallel within a pair of surfaces parallel to the installation portion of the heating element. The heating device according to claim 1, wherein two or more heating element installation sections are arranged in parallel in the reaction vessel. The heating device according to claim 1, wherein the heating element is made of glassy carbon. A heating device, wherein the heating device according to any one of claims 1 to 3 and a reaction vessel provided with a heating element and not provided with a high-frequency induction coil are alternately arranged.

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