JPS58170532A - Vacuum heating apparatus - Google Patents

Abstract

PURPOSE:To carry out stable high temp. heating in vacuum, by constituting a vacuum heating apparatus consisting a heat generating body and an aluminum oxynitride sintered body and provided with a heat conductive material for conducting heat generated from the heat generating body to an object. CONSTITUTION:A heater 12 being a heat generating body is interposed between an upper flat plate 11 and a lower flat plate 13 to form a heating apparatus 10. The heater 12 is formed, for example, by using tungsten and processed into an almost U-shaped continuous shape. In addition, the upper flat plate 11 and the lower flat plate 13 is formed from an aluminum oxynitride sintered body (Al3 NO3) being ceramic having a spinel crystal structure. This aluminum oxinitride sintered body is formed by hot press or sintering under atmospheric pressure and one of which relative density is 99.9% or more to true density of 3.45g/cm<2> is used. This apparatus generates no breakage at 1,200 deg.C or more and can uniformly heat an object.

Description

[Detailed description of the invention] [Technical field of invention].

The present invention relates to a heating device, and particularly to a vacuum heating device for heating an object in a vacuum state.

[Technical background of the invention and its problems]

Conventionally, in the manufacturing process of semiconductor R-sized chairs, etc., the work of heating substrates, specimens, etc. (hereinafter collectively referred to as "objects") in order to ensure good crystal growth or surface bonding. This is the well-known energization process.

Such heating means include resistance heating, Rade heating, electron beam heating, high frequency heating, and direct current heating, but it is difficult to uniformly heat a large object with any of them, so crystal technology or! It is not possible to sufficiently meet the technical costs of Kachika, which is becoming possible to use large-diameter silicon wafers due to the development of process technology.

Furthermore, various demands on de-9 chairs in recent years have led to the complexity of de-9 chairs, which in turn has made the manufacturing process more complicated. There are increasing demands for reliable and stable operation.

In particular, the materials that make up the vacuum heating device must be stable even at high temperatures and do not react with the object or cause the composition to diffuse into the object. It must be made of a stable material with no unnecessary gas emissions and low vapor pressure; it must have sufficient external mechanical strength without damage or deterioration due to thermal cycles of heating up, holding at high temperature, and cooling down, etc. Thermal shock resistance, low thermal expansion, high thermal conductivity, high electrical insulation, and good thermal response characteristics are required.

In response to such technical demands, sintered ceramics ξ, ri have been proposed as apJr for heating devices, but they do not fully satisfy the above conditions. [Objective of the Invention] This invention was developed in view of the above circumstances. The object of the present invention is to provide a vacuum heating device capable of stably heating at a high temperature even in a high vacuum.

[Summary of the invention]

That is, in the present invention, the thermally conductive material constituting the vacuum heating device is formed of an aluminum nitride sintered body, and the relative density of this sintered body is made as high as 99.9%. This enables stable high-temperature heating.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vacuum heating device according to the present invention will be described in detail below according to embodiments shown in the accompanying drawings.

FIG. 1 is a perspective view showing a vacuum heating apparatus according to the present invention, particularly a heating apparatus for heating a substrate such as a silicon wafer. The heating device 10 in FIG. However, as shown in the figure, it has a continuous approximately U-shape.

Next, the upper flat plate 11 and the lower daughter plate 13 are formed of an aluminum nitoxide sintered body (MuA1N0j), which is a ceramic having a spinel type crystal structure. This aluminum nitride sintered body is formed by hot pressing or pressureless sintering, and the relative vfJ degree is true η degree 3.4!
Use 99.9 or more for 5jl/-.

In order to compare the properties of this aluminum nitride sintered body with single crystal sapphire and alumina porcelain, various quantities are shown in the table.

First of all, the composition of aluminum nitride sintered bodies is different from that of single-crystal safa or alumina porcelain in that it contains nitrogen (N).

Compressive strength and bending strength are equivalent to single crystal sapphire, and as is clear from the fact that sapphire is used as jewelry, it has sufficient mechanical strength. Next, m
The impact resistance is the highest compared to the comparative materials, and the thermal expansion coefficient is the lowest. Furthermore, although it is inferior to single crystal sapphire in thermal conductivity, its dielectric strength is comparable to alumina porcelain. In other words, the aluminum nitride ζ sintered body has the advantages of single-crystal sapphire, except for thermal conductivity, and the advantages of aluminum-based porcelain. Although the thermal conductivity is approximately 1/6 lower than that of copper (Cm)K, it has a considerably higher value than other ceramic materials such as steatite and zircon.

FIG. 2 shows a predetermined example using a heating device using an aluminum nitride sintered body having the above characteristics. In this figure, the vacuum evaporation equipment [20] has a table 22 at the center of the bottom of its belt gear 21, and gas is supplied from the bottom of the table 22 in the direction of arrow F1 in the figure by means of a vacuum pump system (not shown). is pulled, and the inside of the Pel jar 21 is constructed to be an appropriate vacuum.

On the table 22 are nine heating devices 10 shown in FIG.
is placed and fixed thereon, and silicon wafers SA and SR, which are objects, are placed on top of it. Further, the heater 12 of the heating device 10 is led out of the Pelger 21 via a suitable hermetic electrode, and is connected to a power source (not shown).

On the other hand, poles 23 and 24 are provided across the chisol 22, and an electrode 2 is provided between these poles 23 and 24.
A filament 27 is installed through the filament 27, and a wire-like metal 28 formed into a substantially U-shape is suspended from the filament 27. Said I-ru 23, 24
It is also led out to the wire and connected to a power source (not shown).

Next, referring to FIG. 2, the formation of the metal film 28 on the silicon wafers SA, 8B will be described. First, the interior of the belt jar 21 is brought to an appropriate vacuum using a vacuum ring system (not shown). Next, before the metal 28 is vapor-deposited, electricity is applied to the surface cleaning heater 12 of the silicon wafer S, 8B to heat the silicon wafer 81.degree. 8B. Generally, it is required that silicon Cueva SA, 811 be heated to 1000° C. or higher. At this time, the gas contained in the upper and lower flat plates 11.13 is released,
As mentioned above, the relative density of the aluminum nitride sintered bodies forming the upper and lower flat plates 11.13 is 99.9-, so there are almost no vacuoles inside, and the amount of gas released by this heating is small. will be extremely small. Therefore, even in an ultra-high vacuum state where the atmospheric pressure is 10 Torr or less, there is almost no effect on the vacuum state. Regarding this invention, data from heating experiments in a prototype device are shown below. Upper and lower flat plates 11
．． Let 13 be a square with a side length of 120 m5 and a thickness of 1. The heater 12 is a tungsten wire, and the heater 12 is made of tungsten wire.
From room temperature to 1200℃ under Torr vacuum condition6
The temperature was raised to 1,200°C for 10 minutes, and then the temperature was lowered to room temperature by natural cooling.

During this heating cycle, the degree of vacuum was 101 Torr.
It held well. In addition, a silicon wafer H with a diameter of 75 wm and a thickness of 0.45 mm was placed on the upper flat plate ll.
No chemical reaction was observed between A, 8B and the upper flat plate 11. Furthermore, the above heating cycle was repeated 50 times, but
Damage to upper and lower plates 11 and 13 or heater 12
No chemical reaction was observed with the silicon wafer. Next, after cleaning the silicon wafer SA
Silicon wafer SA by adjusting the amount of electricity supplied to the heater 12,
When the temperature of the metal 811 is adjusted to the required constant temperature and the filament 27 is further energized, the metal 28 is melted and evaporated, and the metal 28 is deposited on the surfaces of the silicon wafers SA and SB.
8 films are formed.

In the above embodiments, the object to be heated is a silicon wafer, but other metals, insulators, etc. may be used. Further, the heating device according to the present invention may be used not only in the vacuum evaporation described above but also in manufacturing processes such as molecular beam epitaxy, and may also be used in analysis and measurement devices such as Auger spectroscopy. Furthermore, the shape of the heating device is not limited to the above-mentioned flat plate shape, and may be of various shapes.
It is also possible to embed a heater by shaping the material into a certain shape during sintering. It is also possible to use it in combination with other beryllia porcelain.

〔Effect of the invention〕

As explained above, KoO! According to the disclosed vacuum heating device, the part surrounding the heating element and in contact with the object is formed of an aluminum nitride sintered body.
The object can be heated uniformly and well with low heat loss without any damage even at high temperatures of 200°C or higher, and by making it possible to create a heating device with a large surface area, the size is suitable for the object. Furthermore, since the relative blue change of the sintered body is 99.9%, unnecessary gas release can be reduced and adverse effects on the vacuum state can be prevented, and it is stable at high temperatures in high vacuum. It has an excellent effect of heating the object.

In addition, as an application example of this invention, Eva I, such as a low melting point metal,
The rotor or crucible may be formed of sintered aluminum nitride. In addition, depending on the nature of the work using vacuum equipment, there may be parts that are exposed to extremely high temperatures and require good insulation. For example, in the example shown in FIG. 2, if the poles 23 and 240 are used as the insulating members 30 and 31, the temperature of the I-rules 23 and 24 will decrease as the filament 270 generates heat. Good insulation can be maintained even when the temperature rises.

Furthermore, dielectric heating may be performed by applying an alternating electric field to the aluminum nitride sintered body.
%, it is also possible to heat a gas or liquid by providing a plurality of oversized parts in the aluminum nitride sintered body, or by forming it into a cylindrical shape and performing dielectric heating.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a vacuum heating device according to the present invention, and FIG. 2 is a perspective view showing an example of a vacuum evaporation device using the heating device shown in FIG. DESCRIPTION OF SYMBOLS 10... Vacuum heating device, 11... Upper flat plate which is a thermally conductive material, 12... Heater which is a heating element, 13...
The lower flat plate is a thermally conductive material.

Claims (1)

[Claims] A vacuum heating device used in a vacuum, comprising a heating element and a thermally conductive material that conducts heat generated from the heating element to an object, wherein the thermally conductive material is made of nitrogen. A vacuum heating device characterized by being formed of an aluminum oxide sintered body. (2) The vacuum heating device according to claim 0, wherein the aluminum nitoxide sintered body has a relative density of 99.9 or more.