JPH07116601B2 - Thin film production equipment - Google Patents

Description

The present invention relates to a thin film forming apparatus used for forming a thin film of a material such as metal or semiconductor on a substrate.

[Prior Art] Regardless of which method is used for depositing particles, such as vapor deposition and sputtering, rotating the substrate is effective for producing a thin film having a uniform film thickness. For this reason, a thin film forming apparatus having a substrate rotating mechanism is used for forming a thin film having a uniform film thickness. However, when the substrate is heated to about 150 ° C or higher, continuous rotation of the substrate becomes impossible.

That is, the substrate heating is roughly classified into (1) a method of attaching a heating coil to the back side of the substrate, and (2) a method of warming the substrate surface with an infrared lamp heater. In the method (1), the substrate temperature reaches about 700 to 800 ° C. for a 2-inch diameter Si or sapphire wafer or the like, but in this case, wiring is required for passing a current through the coil. Due to the presence of this wiring, when the substrate is rotated at the same time as the substrate is heated, this wire is wrapped around the rotating shaft, and eventually a failure such as disconnection occurs.
Therefore, the method (1) cannot rotate the substrate during heating.

Further, in the method (2), it is possible to simultaneously heat the substrate and rotate the substrate, but the vacuum container is also heated. Since an O-ring that is weak against heat is used in the vacuum container, the allowable heating temperature of the vacuum container is usually up to about 150 ° C. Therefore, under the substrate temperature higher than this, the lamp heater method of (2) cannot be used. Further, when the vacuum container is warmed, impurities adsorbed in the container are released, and the impurities are mixed into the atmosphere in the container, and the impurities are taken in during vapor deposition and sputtering, so that many impurities are contained in the film. Become. Moreover, the presence of the lamp causes a change in the discharge density, which adversely affects the film thickness uniformity. Further, a method of heating the back surface of the substrate holder with a lamp heater or a coil can be considered, but in these cases, since the substrate is warmed by heat conduction from the back surface of the substrate holder, the heating efficiency is poor and the heating temperature changes. Following is very slow. Further, the lamp heater heating has a disadvantage that the vacuum container cannot be heated to 150 ° C. or higher as described above.

For this reason, it was difficult for the conventional apparatus to heat the substrate at about 150 ° C. or higher when rotating the substrate.

Also, when rotating the substrate while cooling the substrate by thermal contact using a coolant such as liquid nitrogen, it is not possible to heat the substrate at any temperature in the range of several hundreds of degrees Celsius, so it is not possible to control to any set temperature. Therefore, it is impossible to form a thin film having a uniform film thickness except at the temperature where it is cooled by the refrigerant.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned drawbacks of the related art, makes it possible to heat the substrate during continuous rotation of the substrate, and makes it possible to set an arbitrary substrate temperature. An object is to provide a manufacturing apparatus.

[Means for Solving the Problems] A thin film manufacturing apparatus according to the present invention is a thin film manufacturing apparatus for forming a thin film on a substrate, wherein the substrate holder is rotatable and holds the substrate, and the substrate of the substrate holder is rotatable. And a substrate heating section which is provided spatially separated from the substrate holding side and which is spatially separated from the substrate holder and generates an alternating magnetic field to heat the substrate.

[Operation] As shown in Fig. 2, the physics shows that the electric current 3 is generated when the changing magnetic field line 2 is passed through the conductor 1. This phenomenon also serves as the principle of generators and transformers, and is one of the important principles in the industrial field, particularly in the field of the electric industry. When the magnetic field lines pass through the conductor, eddy currents are generated around the magnetic field lines, and at the same time, the current is consumed by the resistance of the conductor and converted into heat. In particular, a magnetic conductor such as iron has a property of capturing magnetic field lines and concentrating the magnetic field lines into itself, so that as shown in FIG.
Most of the magnetic lines of force generated from the magnetic field pass through the magnetic conductor, so that current is efficiently generated, and heat is generated in proportion to this. FIG. 3 (b) is a sketch of FIG. 3 (a). The power supply used may be a high frequency power supply of 15 to 40 kHz or a commercial power supply. With an input of about 3kW, heating at about 700-800 ℃ is possible.

[Examples] It was revealed by the present invention that many effects are produced when this phenomenon is applied to substrate heating in a thin-film forming apparatus, as shown in the following examples.

Example 1 FIG. 1 shows a vacuum container part of a thin film forming apparatus to which the substrate heating method of the present invention is applied. Here, 5 is a stainless steel vacuum container, which is evacuated by a pump 6. Substrate 7
It is mounted on a substrate holder 8 made of magnetic stainless steel such as 13% Cr-Fe. The size of the board holder is 25 cm in diameter,
It has a thickness of 5 mm. The substrate holder 8 is given a rotational movement by a motor 9. The substrate heating unit 10 is arranged on the substrate holder 8. The substrate heating unit 10 is preferably non-magnetic and excellent in heat resistance, and austenitic stainless steel, ceramics or the like is used. An insulated heating coil 11 is incorporated therein. coil
11 is a copper wire wound in a spiral in this example. Although the substrate holder 8 and the substrate heating unit 10 are separated in this way, the substrate holder 8 has a property of converging the magnetic field, and therefore the heating efficiency is practically sufficient. A temperature monitor 12 (Pt-Rh thermocouple in this embodiment) is in contact with the center of the substrate holder 8. In this embodiment, two kinds of targets 13, 1 made of different materials are made to face the substrate holder 8.
Placed 4 Shutters 15 and 16 were placed on the target to prevent spattered atoms from scattering during pre-sputtering. Matching boxes 17 and 18 and target power sources 19 and 20 are connected to the target so that they can be discharged. Due to such a configuration, unlike the conventional apparatus, the thin film manufacturing apparatus can rotate the substrate holder 8 freely without being affected by the wiring for heating the substrate, and is similar to the conventional lamp heater heating type apparatus. In addition, the unevenness of the film thickness due to low-temperature heating (up to 150 ° C) due to the concern of protection against high temperature heating of the local part of the vacuum container and discharge abnormality due to the lamp heater is also improved. Here, first, the substrate holder 8 was rotated at 1 rpm by the motor 9, and at the same time, an electric current was passed through the coil 11 to keep the substrate holder 8 at 500 ° C. As the substrate, 8 cm square glass and 3 inch diameter Si wafer were used. Next, after the target 13 (tungsten (W) in this embodiment) and the target 14 ((C) in this embodiment) were pre-sputtered at 240 W and 800 W, respectively, the shutters 15 and 16 were opened to form a multilayer thin film. The number of laminated layers is 50 in the W-C pair. When the in-wafer distribution of the film thickness of this W-C multilayer film was measured using a film thickness meter (Taristep), the film thickness was 2300Å ± 20Å, and the variation was within ± 1%. It was revealed that it was made.

Since the substrate temperature during substrate rotation and the substrate temperature without substrate rotation were the same, the heating coil
If the relationship between the current flowing through 11 and the temperature is measured, it is possible to monitor the temperature by the value of the current flowing through the heating coil 11 without the temperature monitor 12 during operation.

Example 2 A W-C multilayer film was produced under the same conditions as in Example 1 except that the substrate temperature was changed to 700 ° C using an iron substrate holder. In this case, the film thickness and the variation in the film thickness are the same as those in the example, and the variation is within ± 1%.

Embodiment 3 FIG. 4 shows a configuration example of a substrate cooling mechanism and a heating unit of an embodiment in which the substrate holder of FIG. 1 has a substrate cooling mechanism. In this embodiment, the coolant holding portion 21 is made of copper having a good thermal conductivity.
After the liquid nitrogen was introduced into the coolant holding portion 21 from the liquid nitrogen inlet 22 and the substrate was cooled (at this time, the substrate was cooled to −190 ° C.), an electric current was passed through the heating coil 11 to control the substrate temperature to −100 ° C. . After that, the substrate holder was rotated at 2 rpm in the same manner as in Example 1, and under the same conditions as in Example 1 except that a 100-layer multilayer film was formed with a pair of W and C. The film thickness of the W layer is 13Å, the film thickness of the C layer is 10Å, and the in-plane distribution of the total film thickness is 2300Å ± 22Å. A thin film could be produced. It was possible to control to an arbitrary set temperature from room temperature to −190 ° C. with an accuracy of ± 1 ° C. As is clear from this result, compared to the conventional technique, an improvement that the uniform film thickness can be produced by controlling the temperature to an arbitrary set temperature during the rotation of the substrate in the range of room temperature to almost nitrogen temperature is brought.

As described above, in the present invention, the substrate heating unit is spatially separated from the substrate holder on the side opposite to the substrate holding surface of the rotatable substrate holder. It is possible to do it at the same time. Therefore, under an arbitrary set substrate temperature from a low temperature region cooled by a coolant such as liquid nitrogen to a high temperature region of about 700 ° C., a thin film having a uniform film thickness can be formed on a large area substrate such as a 4-inch Si wafer. Has the advantage that it can be manufactured.

The MOCVD method, which is one of the thin film manufacturing methods, requires the substrate to be fixed for heating the substrate. Therefore, the film thickness is about ± 5% (in the 3-inch wafer surface) due to the flow rate distribution of the gas on the substrate. Although the distribution was generated, if the present invention is applied, the uniform variation of the film thickness will be further promoted. In addition, the MBE, CVD, and EB methods, which could not rotate the substrate due to the necessity of heating the substrate, can be used to fabricate various thin films with excellent film thickness uniformity by producing a thin film production apparatus that combines the present invention. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of a thin film forming apparatus of the present invention, FIG. 2 is a principle diagram of an electromagnetic induction effect, and FIG. 3 is a diagram showing a relation between a magnetic field generated by a coil and a current generated in a conductor, FIG. 4 is a diagram showing another embodiment of the present invention. 5 ... Vacuum container, 6 ... Exhaust pump, 7 ... Substrate, 8 ... Substrate holder, 9 ... Motor, 10 ... Substrate heating unit, 11 ... Heating coil, 12 ... Thermocouple for temperature monitor , 13,14 …… Target, 15,16 …… Shutter, 17,18 …… Matching box, 19,20 …… Target power supply.

Claims (3)

[Claims] 1. A thin film manufacturing apparatus for forming a thin film on a substrate, comprising: a rotatable substrate holder for holding the substrate; and a substrate holder on the side of the substrate holder opposite to the side for holding the substrate. And a substrate heating unit that is spatially separated and that generates an alternating magnetic field to heat the substrate. 2. The thin film forming apparatus according to claim 1, wherein the substrate holder has a coolant holding portion. 3. The thin film forming apparatus according to claim 1, wherein the substrate holder is made of a magnetic conductor.