JP2721888B2 - Low pressure vapor phase growth equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a reduced-pressure vapor deposition apparatus for forming a thin film on a substrate surface under reduced pressure.

(Problems to be Solved by Conventional Techniques and the Invention) In recent years, with the miniaturization of semiconductor circuits, a higher-performance reduced-pressure vapor deposition apparatus has been required. Conventionally, in a cold wall type low pressure vapor deposition apparatus, an indirect heating method has been used as a method for heating a substrate. In this method, a holder on which a substrate is placed is heated, and the substrate is heated by heat transfer due to contact between the holder and the substrate. In this indirect heating method, the temperature of the substrate is 60 to 80% as compared with the temperature of the holder in a pressure range for forming a thin film (for example, 0.1 to 0.5 Torr). For this reason, the set temperature of the holder should be 25 to 67
%, It is necessary to form a thin film in a higher temperature range. For example, in the case of high-speed deposition of a tungsten film, the temperature of the holder is 800 to 1000 ° C. As described above, as the temperature of the holder increases, the following problems occur.

With the thermal expansion of the holder, warpage occurs, and the adhesion to the substrate deteriorates. As a result, the temperature distribution of the substrate deteriorates.

The concentration of impurities in the film increases due to an increase in outgassing such as H ₂ O and CO.

The method of fixing around the holder is complicated.

Therefore, in order to solve the above problems, a so-called direct heating method is adopted in which a light-transmitting support is used instead of a conventional holder for mounting a substrate, and only the substrate is directly heated. There is.

FIGS. 5 (a) and 5 (b) show a conventional general direct heating type reduced pressure vapor phase growth apparatus using the above-mentioned light transmitting support.

FIG. 5 (a) shows that an opening 11 is provided at the lower end of the reaction chamber 1, and the substrate 4 is placed on the light-transmitting support base 5 having a diameter larger than the opening 11. Is reaction room 1
I'm facing inside. An infrared lamp 6 is provided on the back side of the substrate 4 at a position close to the light-transmitting support table 5. Then, the substrate 4 is directly heated by the irradiation light from the infrared lamp 6 passing through the light-transmitting support base 5 and irradiating the back surface of the substrate 4. The reaction gas supplied into the reaction chamber 1 from the gas supply port 2 causes a chemical reaction on the surface of the substrate 4 to form a desired thin film, while the reacted gas and the like are discharged from the gas discharge port 3. ing.

FIG. 5 (b) shows that a support 5 'is installed in the reaction chamber 1 having an opening 12 at the upper end, and the substrate 4 is placed on the support 5'.
Is placed. A light-transmitting plate 7 having a diameter larger than the diameter of the opening 12 is fixed to the outside of the opening 12, and an infrared lamp 6 is installed near the light-transmitting plate 7. The substrate 4 is directly heated by the irradiation light from the infrared lamp 6 passing through the light transmitting plate 7 and irradiating the surface of the substrate 4. The process of film formation is the same as in the case of FIG. 5 (a).

In the above-described substrate heating method, any one of a closed-loop temperature control and an open-loop temperature control is currently used to control the temperature of the substrate.
The closed-loop temperature control uses a thermocouple or a radiation thermometer, and feeds back a signal from the thermocouple or the radiation thermometer to an infrared lamp to adjust the substrate temperature so that the substrate is maintained at a predetermined temperature. Control. Since a feedback loop is used, temperature reproducibility and stability are good. However, when the thermocouple is brought into direct contact with the substrate, contamination and poor reproducibility of contact force occur. Also, in the substrate temperature measurement using a radiation thermometer, the emissivity of the substrate before film formation and the emissivity of the substrate after film formation depend on various parameters (type of thin film, thickness, particle size, And the calibration was very difficult because of the coating on the back surface of the substrate.

On the other hand, open loop temperature control is a power control method. Compared with the above-described closed loop temperature control, there is an advantage that the substrate temperature in the temperature control is determined only by the amount of supplied electric power, and accurate measurement of the temperature is not required. However, as the temperature of the permeable support increases over time, the heat transfer causes the substrate temperature to increase. Therefore, it is difficult to stabilize the substrate temperature by the conventional method in which only the electric power is controlled as described above. This will be described with reference to FIG. 2 showing the temperature characteristics of the substrate 4. Curve (a) shows the temperature characteristic of the substrate when the power (power of the infrared lamp) is constant in the conventional technique described with reference to FIG. 5 (a).
According to this, the temperature of the substrate rises rapidly with the start of heating, and then gradually rises with time. The reason for this is that the light-transmitting support base has a lower light absorption rate than the substrate and is gradually heated. That is,
The temperature of the substrate is stabilized by equilibrium between the thermal energy given by the infrared lamp and the thermal energy emitted to the light-transmitting support that is in contact with the substrate, but the temperature of the light-transmitting support gradually increases. Since the temperature rises and becomes unstable, the temperature of the substrate does not reach equilibrium and is not stable.

(Purpose of the Invention) An object of the invention of each claim of the present application is to solve the above-mentioned problems, and to provide a reduced-pressure vapor deposition apparatus capable of stabilizing the temperature of a substrate.

(Means for Solving the Problems) The invention of each claim of the present application has
It has the following configuration.

That is, the invention of claim (1) provides a light-transmitting support on which a substrate is placed in a reaction chamber, a gas supply unit for supplying a reaction gas to the substrate, and a light-transmitting support passing through the light-transmitting support. An infrared lamp that radiates and heats the substrate from the back side, and an exhaust unit that exhausts the reaction chamber is provided.By supplying a predetermined reaction gas from the gas supply unit, an anti-gas under reduced pressure is chemically reacted on the substrate surface. A reduced pressure vapor phase epitaxy apparatus for forming a thin film by causing a reaction, comprising a cooling mechanism for supplying a cooling medium so as to be in contact with the light transmitting support and for directly cooling the light transmitting support. It has the structure of.

According to a second aspect of the present invention, in the configuration of the first aspect, a light transmissive plate is provided on the back surface side of the light transmissive support, and the cooling mechanism includes the light transmissive support and the light transmissive support. It is configured to supply a light transmitting cooling medium to a space between the light transmitting plate and the light transmitting plate.

Further, the invention according to claim (3) provides a support table on which a substrate is placed, a gas supply unit that supplies a reaction gas to the substrate,
An infrared lamp that radiatively heats the substrate from the front side, and an exhaust unit that exhausts gas from a space where the substrate is present, by supplying a predetermined reaction gas from the gas supply unit, the reaction gas under reduced pressure is supplied to the substrate. In a reduced pressure vapor deposition apparatus for forming a thin film by causing a chemical reaction on the surface, the power of the infrared lamp is reduced by forcibly cooling the support and removing heat energy obtained by light absorption by the support. A cooling mechanism is provided to stabilize the temperature of the substrate when open-loop control is performed.

Further, according to the invention of claim (4), in the configuration of claim (3), a plate is provided on the back surface side of the support base,
The cooling mechanism has a configuration configured to supply a cooling medium to a space between the support base and the plate.

According to a fifth aspect of the present invention, in the configuration of the third aspect, the support has a gap for circulating the cooling medium therein, and the cooling mechanism supplies the cooling medium to the gap in the support. It is configured to supply and circulate and then to discharge.

The invention of claim (6) has a structure in which, in the constitution of claim (4) or (5), the cooling medium is an inert gas or oil having high thermal conductivity, or water or air.

(Operation) In the reduced pressure vapor phase epitaxy apparatus according to each aspect of the present invention configured as described above, the substrate is heated by absorbing the irradiation light from the infrared lamp. At this time, the light transmissive support or the support is also heated, but the light transmissive support or the support is forcibly and directly cooled by the cooling medium with which the light transmissive support or the support is in contact. Therefore, the temperature of the substrate is stabilized. In the inventions of claims (3) to (6), since the power of the infrared lamp is controlled in an open loop, it is not necessary to measure the substrate temperature accurately.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that the same components as those in the related art will be described using the same reference numerals.

FIG. 1 shows a first embodiment of the present invention.
An opening 11 is provided at the lower end of the reaction chamber 1, and a gas supply port 2 for supplying and exhausting a reaction gas and a carry gas is provided.
And the gas outlet 3 are connected. The substrate 4 is placed on a light-transmitting support base 5 having a diameter larger than that of the opening 11 as in FIG. 5 (a). The light transmissive support 5 is
The surface of the substrate 4 is installed so as to face the inside of the reaction chamber 1, thereby closing the opening 11. The light-transmitting support base 5 is formed to have a larger area than the substrate 4 as described above in order to prevent the generated film from adhering and depositing on the back surface of the substrate. Outside the light-transmitting support 5, a cooling chamber 8 formed between the light-transmitting plate 7 and the light-transmitting support 5 is provided. The cooling chamber 8 is provided in contact with the light-transmitting support 5 for the purpose of preventing a temperature rise of the light-transmitting support 5. The cooling chamber 8 has a supply port 9 for an inert gas and a discharge port 10 therefor.

Then, the substrate 4 is heated by the irradiation light from the infrared lamp 6 via the light transmitting plate 7 and the light transmitting support 5.

Hereinafter, the operation of the reduced-pressure vapor deposition apparatus according to the present embodiment will be described.

The substrate 4 placed on the light-transmitting support 5 absorbs light emitted from the light-transmitting plate 7, the cooling chamber 8, and the infrared lamp 6 passing through the light-transmitting support 5, and is heated to 300 to 650 ° C. Heated. Into the cooling chamber 8, a light-transmissive inert gas is supplied as a cooling medium from the gas supply port 9 so as to come into contact with the light-transmissive support table 5, and the gas is discharged from the discharge port 10. Thus, the light-transmitting support base 5 is cooled by the cooling medium introduced into the cooling chamber 8. The pressure in the reaction chamber 1 during film formation is about 0.1 to 10 Torr.

In FIG. 2, a curve (b) shows a temperature characteristic of the substrate 4 when the light transmitting support 5 on which the substrate 4 is placed is forcibly cooled. The example of the curve (b) is an example of the case where the power of the infrared lamp 6 is controlled in an open loop, as in the case of the above-described conventional curve (a).
Is the temperature characteristic of the substrate 4 when the power of the substrate 4 is constant.
According to this, it can be seen that the maximum attainable temperature is low at the same power as in the above-described conventional case, but is almost stable in about 10 minutes. Also, the time from the film formation start point A to the film formation end point B (for example, about 10 minutes in a normal tungsten film formation process)
Temperature difference is within 30 ° C., which is within a practically allowable range. Furthermore, when the heating is repeatedly performed, the reproducibility of the substrate temperature is within ± 1.5%, and the reproducibility of the temperature characteristics of the substrate can be found. The reason for the reproducibility of the temperature characteristics of the substrate is that the light-transmitting support base 5 having a small absorptance to the heat radiation of the infrared lamp suppresses the temperature rise by forcible direct cooling by the cooling medium,
As a result, the temperature of the substrate reaches thermal equilibrium in a short time.

The cooling medium to be supplied into the cooling chamber 8 is not limited to the inert gas as described above, but may be any light-transmitting material.
It is also possible to introduce air and water.

FIG. 3 shows a second embodiment of the present invention.
Although the cooling mechanism in this embodiment has the same configuration as that of the first embodiment, the irradiation position of the infrared lamp 6 is different from that of the first embodiment. That is, the irradiation position of the infrared lamp 6 in this embodiment is set such that the irradiation light from the infrared lamp 6 is transmitted from the outside of the upper end opening 12 of the reaction chamber 1 to the light transmitting plate 7 as shown in FIG. And the surface of the substrate 4 is irradiated and heated.

The irradiation position of the infrared lamp 6 is the first position as described above.
Due to the difference from the embodiment, the support base 5 'and the plate 7' constituting the cooling chamber 8 are not necessarily the same as the light-transmitting support base and the light-transmitting plate 7 of the first embodiment shown in FIG. It is not necessary that the member has a light transmitting property.

FIG. 4 shows a third embodiment of the present invention. As a mechanism for forcibly cooling the support table 5 'in this embodiment, a space is provided inside the support table 5'
An inert gas or oil, water, or air having high thermal conductivity is supplied from the gas supply port 13 into the cooling chamber 8, circulated through the cooling chamber 8, and discharged from the discharge port 14. ing. For this reason, the support table 5 'on which the substrate 4 is placed is forcibly cooled, and the temperature rise of the substrate 4 heated by receiving the irradiation light from the infrared lamp 6 can be suppressed.

In each of the above embodiments, the power of the infrared lamp 4 is controlled in an open loop, but the power of the infrared lamp 4 may be controlled in a closed loop. In the configuration in which the light-transmitting support 5 or the support 5 'is forcibly and directly cooled by the contacting cooling medium, whichever control is performed,
This contributes to stabilizing the temperature of the substrate 4.

(Effects of the Invention) According to the reduced pressure vapor phase epitaxy apparatus according to claims (1) to (6) of the present invention, the cooling medium supplied into the cooling chamber exhibits a cooling effect, so that light is transmitted during thin film production. Thus, the temperature of the support or the support can be prevented from rising, and as a result, the temperature of the substrate can be stabilized. In particular, according to the reduced-pressure vapor deposition apparatus according to claims (3) to (6), since the power of the infrared lamp is controlled in an open loop, it is not necessary to accurately measure the substrate temperature. Therefore, the problem of contamination and poor reproducibility of contact force when measuring the substrate temperature by directly contacting the thermocouple to the substrate, and the difficulty of calibration when measuring the substrate temperature with a radiation thermometer, Does not occur with these devices.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reduced pressure vapor phase growth apparatus showing a first embodiment of the present invention, FIG. 2 is a graph showing temperature characteristics of a substrate, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a schematic view of a reduced pressure vapor phase growth apparatus, FIG. 4 is a schematic view of a reduced pressure vapor phase growth apparatus showing a third embodiment of the present invention, and FIGS. 5 (a) and (b) are conventional vacuum pressure vapor phase growth apparatuses. FIG. 1 ... reaction chamber, 2 ... gas supply port, 3 ... gas discharge port,
4... Substrate, 5... Light-transmitting support, 5 ′.
6 ... Infrared lamp, 7 ... Light transmissive plate, 7 '...
... plate, 8 ... cooling chamber, 9, 13 ... gas supply port, 1
0, 14 ... Gas outlet.

Claims (6)

(57) [Claims] A light-transmitting support for mounting a substrate in a reaction chamber; a gas supply unit for supplying a reaction gas to the substrate;
An infrared lamp that radiates and heats the substrate from the back side through the light-transmitting support, and an exhaust unit that exhausts the reaction chamber, and supplies a predetermined reaction gas from the gas supply unit to reduce the pressure. In a reduced pressure vapor phase epitaxy apparatus for forming a thin film by causing a chemical reaction of a reaction gas below on a substrate surface, a cooling medium is supplied so as to be in contact with the light-transmitting support, thereby forcing the light-transmitting support. A reduced pressure vapor phase epitaxy, comprising a cooling mechanism for directly and directly cooling. 2. A light transmissive plate is provided on a back surface side of the light transmissive support, and the cooling mechanism transmits light to a space between the light transmissive support and the light transmissive plate. The reduced-pressure vapor phase growth apparatus according to claim 1, wherein the apparatus is configured to supply a cooling medium having a characteristic. 3. A support for mounting a substrate, a gas supply unit for supplying a reactive gas to the substrate, an infrared lamp for radiantly heating the substrate from the front side, and discharging a gas from a space where the substrate exists. A reduced pressure gas phase growth apparatus for forming a thin film by causing a reaction gas under reduced pressure to cause a chemical reaction on a substrate surface by supplying a predetermined reaction gas from the gas supply unit. A cooling mechanism that stabilizes the temperature of the substrate when open-loop control of the power of the infrared lamp is performed by forcibly cooling the substrate to remove thermal energy obtained by light absorption by the support base. Reduced pressure vapor phase growth apparatus. 4. A plate is provided on the back side of the support base, and the cooling mechanism is configured to supply a cooling medium to a space between the support base and the plate. The reduced pressure vapor phase growth apparatus according to claim 3, wherein: 5. The supporting base has a gap for circulating a cooling medium therein, and the cooling mechanism is configured to supply the cooling medium to the gap in the supporting base, circulate the cooling medium, and then discharge the cooling medium. The reduced pressure vapor phase epitaxy apparatus according to claim 3, wherein: 6. The reduced pressure vapor phase growth apparatus according to claim 4, wherein the cooling medium is an inert gas or oil having a high thermal conductivity, or water or air.