JPH07109031B2 - Substrate heating device - Google Patents

Description

The present invention relates to a substrate heating device used in a sputtering device, etc., and particularly to a substrate heating device having good responsiveness to temperature changes of a heat stage. For the purpose of providing a substrate heating device that can be controlled by time, a heat stage on which a substrate is placed and a heating unit that faces the heat stage with a gap and has a larger heat capacity than the heat stage. And a gas inlet for introducing gas into the gap, and is configured to control the pressure of the gas to regulate the inflow of the amount of heat from the heating unit to the heat stage.

[Industrial application field]

The present invention relates to a substrate heating device used in a sputtering device or the like, and more particularly to a substrate heating device having good responsiveness to temperature changes of a heat stage.

It is known that when a thin film is grown on a substrate by using vacuum deposition or sputtering, the properties of the grown thin film remarkably depend on the substrate temperature during growth. Therefore, it is desired that these thin film growth apparatuses can uniformly and reproducibly heat the substrate held in a vacuum.

[Conventional technology]

In the process of manufacturing a semiconductor device wafer, when forming a wiring material such as Al or Al alloy on a substrate, a good film can be obtained by raising the substrate temperature.

Therefore, the film is formed while heating the substrate.However, because the heat conduction by gas molecules is small in the vacuum container where vapor deposition and sputtering are performed, and it is difficult to uniformly contact the substrate with the heat source, infrared rays are used. A heating method by radiation using a lamp or the like has heretofore been general. However, in the case of a semiconductor substrate such as silicon used in the manufacturing process of semiconductor devices, the transmittance of the substrate in the wavelength region effective for heating the substrate by radiation is large, and the resistivity of the substrate and the film present on the front and back of the substrate Since the transmittance changes depending on factors such as the above, it is difficult to heat the substrate with good reproducibility.

In order to eliminate this drawback, the heating method shown in FIG. 2 has been proposed.

In this, a heat stage 11 heated by a heat generating portion 12 is arranged in a vacuum container 5, a substrate 2 is held by a clamping chuck 14 in the periphery and placed on the heat stage 11, and the heat stage 1 and the substrate 2 are placed. From the gas inlet 4 into the gap between
The substrate 2 is heated by using the heat conduction of the gas by introducing a rare gas such as the above at a constant pressure.

The heat stage 11 has a substantially cylindrical shape, has a substrate mounting surface 11a, and a heat generating portion 12 is in contact with and integrated with the lower surface thereof. The substrate mounting surface 11a is in contact with the substrate at the periphery of the substrate 2, and the other portion is formed so as to face most of the substrate with a gap a therebetween.
It is composed of a metal block such as stainless steel in which a heating element such as a and a temperature measuring means such as a thermocouple 12b are embedded.

In general, a metal block having a large heat capacity is used for the heat generating section 12 so that the amount of heat from a plurality of heat generating elements arranged discontinuously is dispersed so that the entire substrate mounting surface has a uniform temperature distribution.

In this method, since the contribution of radiation from the heat source is small, the problem that the temperature rising characteristic of the substrate changes depending on the type of substrate is reduced. However, since the heat stage is integrated with the heat generating portion having a large heat capacity, it is difficult to change the temperature of the substrate mounting surface of the heat stage in a short time of seconds. Therefore, during thin film growth, it is usual to control the temperature of the heat stage to be constant, and therefore the substrate temperature can only be adjusted by two factors: the set temperature of the heat stage and the substrate clamping time. Therefore, if there is a heat flow that flows into the substrate from a place other than the heat stage with time fluctuations, even if the substrate temperature can be monitored, for example, the heat flow that flows into the substrate from the heat stage side cannot be rapidly changed, and thus the substrate temperature Is difficult to keep constant.

[Problems to be Solved by the Invention] In a sputtering apparatus or the like for forming a film on a semiconductor substrate, thermal radiation from a target surface during film formation, secondary electrons, and target atoms and the like flow into the substrate surface of about 200 ° C. Temperature rise occurs.

When the above-described conventional substrate heating device for heating the substrate of such a film forming apparatus is used, there is a problem that the substrate temperature rises with time after the start of sputtering and cannot be controlled to be constant.

In addition, when equipment trouble occurs during sputtering, it may be returned to atmospheric pressure in the vacuum container.Before that, to prevent oxidation of the substrate surface layer, it is necessary to lower the substrate temperature to a low temperature where rapid oxidation does not occur. However, since the heat stage is integrated with the heating part with a large heat capacity, the temperature drop rate is slow even if the heating of the heating part is stopped, and it takes time to reheat to the set temperature when restarting the operation. There is also a problem that the down time of the device becomes long and the operation rate decreases.

The present invention was created in view of the above problems, and an object of the present invention is to provide a substrate heating apparatus capable of controlling the temperature of the substrate mounting surface of the heat stage in a short time.

[Means for Solving the Problems]

The above problem is a substrate heating apparatus used in a film forming apparatus, including a heat stage on which a substrate is placed, a heating unit facing the heat stage with a gap and having a larger heat capacity than the heat stage, A gas inlet for introducing gas into the gap, and is configured to control the pressure of the gas to regulate the inflow of the amount of heat from the heating unit to the heat stage. It is solved by a substrate heating device.

[Action]

Since there is a gap between the heat stage and the heating unit, the amount of heat transferred from the heating unit to the heat stage does not depend on the heat conduction in the solid but on the heat conduction in the gas via the gas introduced into the gap.

Since the thermal conductivity of gas greatly changes depending on its pressure, the thermal conductivity coefficient between the heat stage and the heating unit can be changed by controlling the pressure of the gas.
And since the heat capacity of the heat stage is smaller than that of the heating part, by changing the thermal conductivity coefficient,
It is possible to quickly control only the temperature of the heat stage while keeping the temperature of the heating unit constant.

Therefore, by changing the gas pressure according to the deviation between the substrate temperature and the set temperature, it is possible to quickly change the heat flow flowing into the substrate while keeping the temperature of the heating unit constant, and to keep the substrate temperature constant. It is easy to control the temperature and the heating and cooling time of the substrate can be shortened.

〔Example〕

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, which is incorporated in a sputtering apparatus.

In the figure, the substrate heating apparatus of the present invention comprises a substantially cylindrical heat stage 61 and a thick disk-shaped heating portion 62, and the substrate mounting surface 61 a of the heat stage 61 is sputtered so as to be positioned inside the vacuum container 5. It is attached to the device.

The heat stage 61 is made of a thin SUS material or the like having substantially the same outer diameter as the substrate 2, and the upper substrate mounting surface 61a has a protrusion 61b having a height of 0.5 to 1 mm for mounting the substrate 2 and a chuck 6 for clamping.
1c is provided around, and the inner surface surrounded by the protrusion 61b faces the substrate 2 with a gap a. An assist gas introduction port 7 is opened in the center of the gap a, and an assist gas such as Ar that transfers the heat of the heat stage 61 by heat conduction to heat the substrate 2 is introduced. . A ring-shaped cooling water channel 61d is formed in the lower portion of the protruding portion 61c, and cooling water is appropriately flowed,
The heat of the high-temperature substrate mounting surface 61 is attached to the vacuum container 5 by the mounting portion 61e.
It is cut off so as not to conduct to.

The heat generating portion 62 is made of a thick disk-shaped metal block such as SUS, has a hole for penetrating the assist gas introducing port 7 with a gap in the center, and most of the upper surface thereof is the heat stage 61.
It is provided inside the heat stage 61 so as to face the lower surface of the gap d. A cartridge heater 63, which is a heating element, and a thermocouple thermometer 64 are embedded in a predetermined manner and are kept at a constant temperature by a temperature controller (not shown).

Further, the lower partition wall 65 and the heat stage 61 form a closed space that is shielded from the atmosphere, and the gas inlet 66 penetrating the partition wall 65 opens near the center of the lower surface of the heat generating portion 62, and also the partition wall.
An exhaust port 67 is provided around the periphery of 65. Then, the inert gas G such as Ar or N ₂ supplied to the gas introduction port 66 through the flow rate controller 68 causes a gap d between the heat stage 61 and the heat generating portion 62.
Is filled with air and is discharged from the exhaust port 67. As described above, since the heating unit 62, which is always in a high temperature heating state, is not in contact with the atmosphere, the surface is not oxidized and there is an effect that the life is extended.

In the substrate heating apparatus having the above configuration, the heating unit 62 has a large mass and thus a large heat capacity, and the heat stage 61 has a small mass and thus a small heat capacity. Since the heating part 62 and the heat stage 61 are not in contact with each other and are separated by the gap d, there is no heat conduction through the contact part with the heating part 62, and most of the heat quantity is of the gas filled in the gap d. The heat is transferred to the heat stage 61 via heat conduction. And this thermal conductivity coefficient can be changed over a wide range by the pressure of the gas. For example, when d is 1 mm, the thermal conductivity coefficient in the gas shows the lowest value at 0.1 Torr, becomes a thermal insulation layer and blocks the heat flow from the heating part, and reaches the maximum value at 10 Torr or more and heats up in a short time. The stage is heated to the temperature of the heating section.

Therefore, by appropriately controlling the vacuum pump (not shown) connected to the flow rate controller 68 and the exhaust port 67 to change the pressure of the gas G introduced into the gap d from vacuum to atmospheric pressure, the heat stage 61 The temperature of can be changed rapidly.

For example, the cooling time for lowering the heat stage heated to 600 ° C. to 200 ° C. or lower at which rapid oxidation does not occur requires 1 hour or more in the conventional heating unit integrated type, but according to the present invention, It took only a minute and could be reduced to less than 1/10.

Further, since the temperature response of the heat stage becomes faster, it becomes easy to keep the substrate temperature constant after the start of sputtering by automatically controlling the flow rate controller based on the measured value of the substrate temperature.

〔The invention's effect〕

As described above, according to the substrate heating apparatus of the present invention, a gap serving as a thermal buffer layer is provided between the heat stage and the heating unit, and the temperature of the heat stage is controlled by controlling the pressure of the gas introduced into the gap. Can be changed rapidly, and it has a remarkable effect in stabilizing the film quality of the thin film and improving the operating rate of the apparatus when used in a film forming apparatus such as a sputtering apparatus.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a substrate heating apparatus of the present invention, and FIG. 2 is a view showing a conventional substrate heating apparatus. In the figure, 2 ... Substrate, 5 ... Sputtering device vacuum container, 61 ... Heat stage, 61a ... Substrate mounting surface, 62 ... Heating part, 63
…… Cartridge heater, 64 …… Thermocouple thermometer, 65 ……
Partition wall, 66 ... Gas inlet, 67 ... Exhaust port, 68 ... Flow controller, d ... Gap between heat stage and heating section.

Claims (1)

[Claims] 1. A substrate heating apparatus used in a film forming apparatus, comprising: a heat stage (61) on which a substrate (2) is placed, and a heat stage (61) opposed to each other via a gap (d). A heating unit (6) having a larger heat capacity than the heat stage (61).
2) and a gas introduction port (66) for introducing gas (G) into the gap (d), and controlling the pressure of the gas (G) from the heating unit (62) to the heat stage (61). ). A substrate heating device configured to regulate the inflow of heat into the substrate.