JP2771442B2 - Method and apparatus for heating object - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for heating an object to be processed when the object to be processed is processed in a vacuum vessel. The present invention also relates to a heating method and a heating apparatus for heating an object to be processed by the Joule heat.

[0002]

2. Description of the Related Art When a semiconductor or a liquid crystal is manufactured by processing an object such as a wafer or a glass substrate in a vacuum container, first, the object is placed on an upper surface of a mounting table arranged in the vacuum container. Can be A passage through which temperature-controlled hot water flows is formed inside the mounting table, and the mounting table is heated by the hot water. When the mounting table is heated, the object placed on the mounting table is heated by the heat from the mounting table. In this case, the mechanism for transferring heat from the mounting table to the object to be processed includes heat conduction through a contact surface between the upper surface of the mounting table and the back surface of the object to be processed, and heat radiation from the mounting table to the object to be processed. There are two.

[0003] As a method of heating the mounting table, an electric heater is buried inside the mounting table instead of flowing hot water into the mounting table, or an object to be processed is not in the mounting table but in a vacuum vessel. A method of disposing a far-infrared heater in the vicinity of is also known.

[0004]

However, in the above prior art, the heat transfer mechanism in a vacuum is limited to conduction and radiation, and heat transfer by convection is not performed. There is a problem that heat transfer to the object to be processed becomes insufficient. That is, since the upper surface of the mounting table or the back surface of the processing object has many irregularities when viewed microscopically,
The contact area between the upper surface of the mounting table and the back surface of the processing object is reduced, and the efficiency of heat conduction from the mounting table to the processing object is significantly reduced. As a result, it has been difficult to control the temperature of the processing target when processing the processing target to the optimum temperature for processing.

Further, when the contact area between the upper surface of the mounting table and the back surface of the object is microscopically observed, the microscopic contact area is not uniform throughout the object. For this reason, the heat transfer efficiency from the mounting table to the processing object is not uniform throughout the processing object, and the temperature distribution in the surface of the processing object varies.
This variation in the temperature distribution brings about a disadvantage that, for example, when an etching process is performed on a large-diameter wafer, the etching rate of the wafer differs depending on the location on the surface to be processed of the wafer. Eventually, there is a problem in that, although the semiconductor device is manufactured from a single wafer, the quality among the devices varies, thereby lowering the product yield.

Further, when processing a plurality of objects to be processed one after another, the contact area between the mounting surface and the back surface of the object to be processed is reduced due to the irregularities existing on the upper surface of the mounting table and the back surface of the object to be processed. It is not constant during a series of processes. For this reason, even when the temperature condition of the hot water for heating the mounting table is constant, the heat transfer efficiency from the mounting table to the processing target is not constant, and as a result, the temperature of the processing target during processing is reduced. It varies among the objects to be processed. The variation in the temperature during processing among the objects to be processed causes a variation in quality of a finally completed product (semiconductor element or the like), which causes a problem of lowering the yield of the product. For the same reason, even in a batch process in which a plurality of workpieces are processed at the same time, the processing varies among the workpieces.

Further, when a far-infrared heater is provided in a vacuum vessel, the heat transfer mechanism to the object is limited to radiation, so that it is difficult to efficiently heat the object. . Further, in order to uniformly heat the entire object to be processed, the positional relationship between the object to be processed and the heater must be properly determined, but in practice, it is very difficult due to the limited space in the vacuum vessel. However, it is impossible to uniformly heat the object. Further, in the case where the processing surface of the object to be processed has already been processed in the previous step to form an uneven shape on the surface, radiant heat to the concave portion is blocked by the convex portion. For this reason, the heating of the concave portion becomes insufficient, and it becomes difficult to uniformly heat the entire object to be processed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for processing an object to be processed in a vacuum vessel, whereby the object to be processed can be uniformly heated over its entirety and the temperature of the object can be appropriately controlled. Accordingly, an object of the present invention is to provide a method and a heating apparatus for heating an object to be processed, which can achieve an optimum temperature for processing.

[0009]

In order to achieve the above object, the present invention relates to a method for heating an object to be processed in a vacuum vessel, wherein an electric current is supplied to the object. The object is heated by Joule heat generated inside the object by flowing the current.

[0010] Further, the current to be passed through the object is uniformly distributed over the entire object, so that the entire object can be uniformly heated.

Further, it is preferable to control the heating temperature of the object by changing the magnitude of the current flowing through the object according to the change in the temperature of the object.

Further, by controlling on / off of a current flowing through the object according to a change in temperature of the object, the amount of Joule heat generated inside the object is controlled, and The heating temperature of the processed material can be controlled.

Further, the mounting table on which the object is mounted is heated by the heating means, and the object is processed by both the heat from the heated mounting table and the Joule heat generated by the current flowing inside the object. It can also be heated.

[0014]

When an electric current is applied to an object in a vacuum vessel, Joule heat is generated inside the object according to the inherent resistance value of the object, and the object is heated. Here, assuming that the current flowing through the object to be processed is i, the specific resistance value of the object to be processed is R, the Joule heat generated inside the object to be processed is Q, and the energizing time is t, the generation rate dQ of the Joule heat Q is / Dt is dQ / dt =
It is represented by i ² R.

[0015] Further, the current flowing through the object is uniformly distributed over the entire object, thereby uniformly heating the entire object and uniformly processing the object. be able to.

Further, by controlling the magnitude of the current i flowing through the object according to the change in the temperature of the object,
Generation rate of Joule heat Q generated inside the object to be processed dQ /
dt can be controlled, whereby the heating temperature of the object can be controlled.

Further, by controlling on / off of a current flowing through the object to be processed in accordance with a change in temperature of the object to be processed, it is possible to control an amount of Joule heat generated inside the object to be processed. It is possible to control the heating temperature of the object to be processed.

Further, the mounting table is heated by a heating means,
By heating the object by both the heat from the heated mounting table and the Joule heat generated by the current flowing inside the object, the object can be efficiently heated.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an apparatus for heating an object to be processed according to the present invention.

In FIG. 1, reference numeral 1 denotes a vacuum vessel,
The vacuum vessel 1 is connected to an exhaust means (not shown) for exhausting the inside of the vacuum vessel 1 to make it vacuum. A mounting table 2 having a rectangular parallelepiped outer shape is provided inside the vacuum vessel 1 so as to be insulated from the vacuum vessel 1.

A temperature measuring means (not shown) for measuring the temperature of the substrate A to be processed mounted on this surface is provided on the upper surface of the mounting table 2. The temperature measuring means is arranged so as to come into contact with the back surface of the substrate A when the substrate A is placed on the mounting table 2. In addition, a thermocouple or the like is used as the temperature measuring means.

A fluid passage is formed inside the mounting table 2, and hot water controlled at a predetermined temperature flows through the fluid passage.

In the vicinity of the mounting table 2, a plurality of heating wires 3,
3 ... 3 are provided, and these heating wires 3, 3 ...
Terminals 4, 4... 4 are attached to one end of each of the three.

The heating wires 3, 3,... 3 are electrically connected to a heating power supply (not shown). The heating power supply has voltage control means (not shown) for controlling the magnitude of the applied voltage. This voltage control means is electrically connected to a temperature measuring means for measuring the temperature of the substrate A to be processed.

As the power supply for heating, either a DC power supply or an AC power supply can be used.

Next, the operation of the apparatus for heating an object to be processed according to the present invention having the above-described structure will be described.

In FIG. 1, first, the substrate A to be processed is mounted on the upper surface of the mounting table 2, and the inside of the vacuum vessel 1 is evacuated to a vacuum by the exhaust means. A thin film a is formed on the upper surface of the substrate A to be processed, and the thin film a is an object to be processed. The thin film a is formed in a rectangular shape on the upper surface of the substrate A to be processed, leaving a certain width near the outer periphery of the upper surface.

When the substrate A is placed on the upper surface of the mounting table 2, the mounting table 2 is heated by the warm water flowing through the inside of the mounting table 2, so that the substrate A is heated by conduction heat and radiant heat from the mounting table 2. Is done. Further, the temperature measuring means provided on the upper surface of the mounting table 2 comes into contact with the back surface of the processing substrate A at the same time that the processing substrate A is mounted on the mounting table 2.

Next, a plurality of terminals 4, 4,...
4 is attached. The terminals 4, 4,..., 4 are attached so that the terminals 4, 4,..., 4 are arranged linearly at equal intervals in the vicinity of a pair of long sides of the rectangular thin film a. I do.

The terminals 4, 4,...
3 are connected to a heating power supply. Of these terminals 4, 4..., A first terminal group arranged in a line near one long side of the thin film a is a heating terminal. The second terminal group connected to one terminal of the power supply and arranged in a line near the other long side of the thin film a is connected to the other terminal of the heating power supply.

Next, the heating power supply is turned on to supply a current to the heating wires 3, 3,...
4 flows into the thin film a formed on the upper surface of the substrate A to be processed. Since the first terminal group and the second terminal group of the terminals 4, 4,... 4 are symmetrically arranged on the upper surface of the thin film a, the current flowing into the thin film a flows uniformly in the thin film a. . Due to the current flowing in the thin film a, Joule heat corresponding to the resistance value of the thin film a is generated in the thin film a, and the Joule heat heats the thin film a.

After the heated thin film a reaches a predetermined temperature, a reactive gas or the like is introduced into the vacuum vessel 1 to start the processing of the thin film a. Normally, when the processing operation is started, reaction heat or the like is generated in the thin film a with the processing, and the temperature of the thin film a and the substrate A to be processed is changed by the reaction heat.

Therefore, in order to control the temperature of the thin film a to a predetermined value, the temperature of the substrate A is measured with a thermocouple in contact with the back surface of the substrate A. The signal from the thermocouple is sent to voltage control means for controlling the voltage of the heating power supply.
If the temperature of the substrate A during processing becomes higher than a predetermined temperature, the applied voltage is reduced or set to zero to limit the amount of current flowing through the inside of the thin film a.
To reduce the heating rate. Conversely, when the temperature of the substrate A becomes lower than the predetermined temperature, the applied voltage is increased to increase the amount of current flowing through the inside of the thin film a.
Increase the heating rate.

As described above, the temperature of the substrate A is measured during processing, and the amount of current flowing through the inside of the thin film a is controlled in accordance with this temperature, whereby the temperature of the thin film a is controlled to a desired value. can do.

The thin film a is made of molybdenum (M
o), molybdenum compound (molybdenum tantalum etc.), aluminum (Al), aluminum alloy, chromium (C
r), chromium alloy, titanium (Ti), titanium compound (T
iN, etc.), a metal film such as tungsten (W), a tungsten compound (TiW, etc.), or silicon (Si),
A semiconductor film such as germanium (Ge) or gallium arsenide (GaAs), a liquid crystal, or the like is a target.

The object to be treated in this embodiment is rectangular, but the heating method and the heating apparatus according to the present invention are as follows.
It can be applied to objects other than rectangular objects, for example, objects having a disk shape (such as silicon wafers).
It is also possible to apply to.

Further, terminals 4, 4,... 4 on the upper surface of the thin film a
4 is formed of, for example, a material having an appropriate weight, and the terminals 4, 4,.
4 and the terminals 4, 4... 4 attached by their own weights. An adhesive conductive material is applied to the mounting positions of the terminals 4, 4,. 4. A method of electrically connecting the thin film a to the terminals 4, 4,... 4 by attaching the thin films a to the terminals 4, 4,.
4 are electrically connected by clipping them, and the terminals 4, 4,..., 4 are formed of a material having a structure that expands and contracts with an appropriate spring force, and the terminals 4, 4,. , And the thin film a and the terminals 4, 4,... 4
In the above-described various methods, the portions of the terminals 4, 4,... 4 that are in contact with the thin film a are made needle-like, so that an organic thin film or the like is , There is a method of electrically connecting the thin film a to the terminals 4, 4... 4 through the organic thin film.

The terminals 4, 4,... 4 may be formed of a pair of elongated strip-shaped conductors or elongated plate-shaped conductors. In this case, one conductor is placed on the upper surface of the thin film a near one of the pair of long sides of the thin film a so as to be parallel to the long side, and the other strip-shaped conductor is placed on the other long side of the thin film a. In the vicinity, it is placed on the upper surface of the thin film a so as to be parallel to this long side. As described above, by using a pair of elongated strip-shaped or plate-shaped conductors and arranging the two conductors in parallel with each other, the distribution of the current flowing inside the thin film a can be made uniform.

[0039]

As is apparent from the above description, according to the present invention, the object is heated by Joule heat generated inside the object by applying a current to the object. Although the object is placed in a vacuum, the object can be reliably heated.

Further, by appropriately selecting the arrangement of the terminals to be attached to the object to be processed according to the shape of the object to be processed, the distribution of the current flowing in the object to be processed can be made uniform over the entire object to be processed. Since it is possible to uniformly heat the object to be processed, it is possible to uniformly perform processing over the entire object to be processed.

Further, since the amount of current flowing through the object to be processed is controlled in accordance with the temperature of the object to be processed, the temperature of the object to be processed during processing can be controlled accurately, and Good processing can be performed while maintaining the temperature at the optimum temperature for processing.

Further, since the on / off of the current flowing through the object is controlled in accordance with the change in the temperature of the object, the amount of Joule heat generated inside the object is controlled. This makes it possible to precisely control the heating temperature of the object to be processed, and to maintain the temperature of the object at an optimum temperature for processing, thereby performing a good process.

Further, the mounting table on which the object to be processed is mounted is heated by a heating means, and the object to be processed is heated by both the heat from the heated mounting table and the Joule heat generated by the current flowing inside the object. Is heated, the object to be processed can be efficiently heated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an apparatus for heating an object to be processed according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Mounting table 3 Heating wire 4 Terminal A Substrate to be processed a Thin film formed on the upper surface of a substrate to be processed

Claims (5)

(57) [Claims] 1. A mounting table is mounted on the bottom of the vacuum container insulated from the vacuum container. The workpiece is mounted on the mounting table. The mounting table is heated by heating means. Wherein the object mounted on the mounting table is heated by both heat from the heated mounting table and Joule heat generated by a current flowing inside the processing object. The method of heating the object to be treated. 2. A vacuum vessel, a mounting table insulatedly attached to the bottom of the vacuum vessel, a heating wire provided inside the vacuum vessel, and a current flowing through the heating wire. A heating power supply, and the heating wire is electrically connected to the workpiece placed on the mounting table, and a current flows through the workpiece through the heating wire. ,
Joule heat is generated inside the object by the electric current, and the object is heated by the Joule heat. 3. The apparatus for heating an object to be processed according to claim 2, wherein the current flowing through the object to be processed is uniformly flowed over the entirety of the object to be processed. 4. The heating power supply has voltage control means for controlling the magnitude of the voltage applied to the heating power supply. The voltage control means controls the magnitude of the current flowing through the workpiece by controlling the applied voltage. The apparatus for heating an object to be processed according to claim 2, wherein the size is controlled. 5. The mounting table is heated by a heating means.
The object according to claim 2, wherein the object is heated by both heat from the heated mounting table and Joule heat generated by an electric current flowing inside the object. Heating equipment for processed materials.