JPH0280567A - Substrate heater - Google Patents

Abstract

PURPOSE:To accurately heat a substrate to be treated to a target temp. by fixing the substrate to a high-temp. heat stage through a gap in a sputtering device, etc., and passing a mixture of two kinds of gases having different heat conductivities in a variable ratio through the gap based on the difference between the measured temp. and set temp. of the substrate. CONSTITUTION:The metallic heat stage 1 heated to a specified temp. by the heater 12 controlled by a thermocouple 11 and a temp. controller 10 is placed in the vacuum vessel 5 of the sputtering device provided with a target 8, and the substrate 2 to be treated is fixed through a gap (d). The substrate 2 is heated to a preset temp., and a thin film is formed from the target 8. In this case, the temp. of the substrate 2 is measured by a radiation thermometer 7, and the measured temp. is compared with the substrate set temp. by the temp. controller 13. The flow rates of the Ar and He having conductivities largely different from each other are controlled by flow regulators 3a and 3b based on the deviation, and the gases are passed through the gap (d). The temp. of the substrate 2 is precisely held at the target temp. by regulating the heat conductivity of the gaseous mixture, and the quality of the thin film on the substrate 2 is stabilized and made constant.

Description

[Detailed Description of the Invention] (Summary) This invention relates to a substrate heating device used in a sputtering device or the like, and in particular to a substrate heating device that heats a substrate by utilizing thermal conduction of gas between it and a heat stage. The purpose of this device is to provide a substrate heating device that can quickly control the substrate temperature even when the heat flow flowing into the substrate changes. a heat stage on which the substrate is mounted and faces the substrate through a gap in the other area, a gas supply means for introducing a mixed gas consisting of two or more types of gases having different thermal conductivities into the gap, and a substrate temperature detection means. and a control means for controlling the mixing ratio of the mixed gas so as to control the substrate temperature by changing the amount of heat flowing from the heat stage to the substrate based on the detection result.

[Industrial application field]

The present invention relates to a substrate heating device used in sputtering equipment and the like, and more particularly to a substrate heating device that heats a substrate using heat conduction of gas between the device and a heat stage.

It is known that when a thin film is grown on a substrate using vacuum evaporation or sputtering, the properties of the grown thin film are significantly dependent on the substrate temperature during growth. Therefore, it is desired that these thin film growth apparatuses be able to uniformly and reproducibly heat a substrate held in a vacuum.

[Conventional technology]

In the manufacturing process of wafers for semiconductor devices, AIJP
When forming a film of a wiring material such as an AI alloy on a substrate, a good film can be obtained by increasing the substrate temperature.

Therefore, film formation is performed while heating the substrate, but heat conduction by gas molecules is small in the vacuum chamber where evaporation or sputtering is performed, and it is difficult to uniformly contact the substrate with the heat source, so infrared rays are used. Traditionally, boat fishing is a heating method using radiation using a lamp or the like. However, in the case of semiconductor substrates such as silicon used in the manufacturing process of semiconductor devices, the transmittance of the substrate is high in the wavelength range that is effective for heating the substrate by radiation, and the specific resistance of the substrate and the film that exists on the front and back of the substrate are large. Since the transmittance changes depending on the above factors, it is difficult to heat the substrate with good reproducibility.

In order to eliminate this drawback, a heating method shown in FIG. 4 has been proposed. (U.S. Patent No. 4,680,061) In this method, a metal heat stage 1 heated by a heater 12 is disposed in a vacuum container 5, and the periphery of the substrate 2 is brought into contact with the heat stage 1 serving as a heat source using a clamping chuck 14. From the gas inlet 4 into the gap between the heat stage 1 and the base Fi2,
By introducing a rare gas G such as Ar at a constant pressure,
The substrate is heated using the thermal conduction of gas.

In this method, since the contribution of radiation from the heat source is small, the problem that the temperature increase characteristics of the substrate vary depending on the type of substrate is reduced. However, since the heat capacity of the heat stage becomes large, it is difficult to change the temperature of the heat stage in a short period of time on the order of seconds. Therefore, during thin film growth, the temperature of the heat stage is usually controlled 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 flowing into the substrate from a source other than the heat stage with time fluctuations, even if the substrate temperature can be monitored, the heat flow flowing into the substrate from the heat stage side cannot be rapidly varied, so the substrate temperature It is difficult to keep constant.

[Problem to be solved by the invention]

In sputtering equipment, etc. that forms films on semiconductor substrates, heat radiation, secondary electrons, target atoms, etc. flow into the substrate surface from the target surface during film formation, resulting in temperatures of up to 200°C.
A moderate temperature rise occurs.

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

In addition, if the substrate temperature can be quickly raised or lowered before and after the film deposition process or when equipment trouble occurs, the operating time of the equipment can be shortened and throughput can be improved, but the temperature control response is limited by the thermal capacity of the heat stage. There is also the problem that it is difficult to perform this with the above-mentioned conventional substrate heating device, which is slow and has a constant coefficient of heat conduction to the substrate.

The present invention was created in view of the above problems, and an object of the present invention is to provide a substrate heating device that can quickly control the substrate temperature regardless of the type of substrate and even when the heat flow flowing into the substrate changes. do.

[Means to solve the problem]

The above problem is that the substrate heating device used in the film forming apparatus has a heat stage on which the substrate is placed in the peripheral area and faces the substrate through a gap in other areas, and a heat stage that has a different thermal conductivity in the gap. a gas supply means for introducing a mixed gas consisting of two or more types of gas; a substrate temperature detection means; The problem is solved by the substrate heating device of the present invention, which is characterized by having a control means for controlling the gas mixture ratio.

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, reference numeral 1 denotes a heat stage, which is maintained at a constant temperature by an embedded thermocouple thermometer 11, a heater 12, and a temperature regulator (not shown).

2 is a substrate to be heated, which is mechanically clamped to the heat stage 1. The heat stage 1 is in contact with the periphery of the substrate 2, and most of the substrate 2 other than the periphery faces the heat stage 1 with a gap d interposed therebetween. Then, two gases A and B having different thermal conductivities are mixed through flow rate regulators 3a and 3b, and flowed into the gap d through the inlet 4.

Since the contact between the periphery of the group Fi2 and the heat stage l is not vacuum-sealed, the mixed gas flowing into the gap d flows into the vacuum container 5 through the contact portion and is evacuated by the vacuum pump 6. . Therefore, the entire flow rate of gases A and B needs to be made to flow continuously to such an extent that the pressure of the mixed gas in the gap d between the heat stage 1 and the substrate 2 is maintained at a predetermined value. The substrate temperature is measured by the radiation thermometer 7, and the control means 13 controls the flow rate regulators 3a and 3b based on the deviation between the measured value and the preset substrate temperature and the amount of change over time. Change the mixing ratio of A and H.

[Effect]

If the gap d between the heat stage and the substrate is about 0.5 to 1 Torr and the pressure P of the mixed gas is 1 to 5 Torr, the heat conduction flowing into the substrate through this gap is considered to be viscous flow heat conduction. be able to. And the temperature of the heat stage is 50
When the temperature is below 0℃, the heating of the substrate due to radiation can be ignored, so the thermal conductivity coefficient between the heat stage and the substrate is
(However, it is proportional to the thermal conductivity of the gas).

For example, if we use a rare gas meter and He as the two types of gases, the thermal conductivity is about 10 times different between the two gases, so the flow rate ratio [He/(He + Ar)) should be set from 0 to
By changing the coefficient l within a range, it is possible to change the coefficient of thermal conductivity between the heat stage and the substrate over a range of about 10 times. Therefore, by changing the gas flow rate ratio in response 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 heat stage constant. It is possible to control the temperature by keeping it constant or raising or lowering it rapidly.

〔Example〕

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a block diagram of one embodiment of the present invention, which is incorporated into a sputtering apparatus.

In the figure, l is the heat stage, which consists of an integrated metal block, including a temperature measuring thermocouple 11 and a temperature controller l.
The temperature is controlled to a predetermined temperature by a heater 12 controlled by O. Reference numeral 2 denotes a semiconductor substrate to be heated, and its periphery is clamped to the heat stage 1 by a clamping chuck 14 .

Reference numeral 8 denotes a sputter target, which is attached to the vacuum container 5 via an insulating material 8a, with its target throat face facing the substrate 2, and sputtering gas such as Ar is supplied into the vacuum container 5 from a gas inlet 9. be introduced.

And most of the substrate surface is the heat stage l and 0.5~
It faces the heat stage 1 with a gap of about 1 m in between. 4 is a gas inlet port that supplies gas to the gap d between the heat stage 1 and the substrate 2, through which Ar gas and He gas are mixed through independently controllable flow rate regulators 3a and 3b.
Gas is now supplied. Since the contact surface between the substrate periphery and the heat stage is not airtightly sealed, gas determined by the conductance due to the gap in the contact portion flows into the vacuum container 5 and is evacuated by the vacuum pump 6 connected via the gate valve 6a. . Therefore, the total flow rate of the mixed gas must be such that the gas pressure between the heat stage and the substrate is maintained at a predetermined value. The temperature of the board is measured using a radiation thermometer 7.
is measured and sent to the control means 13.

In the case of control to keep the substrate temperature constant, the control means 13 controls the flow rate regulators 3a and 3b according to the deviation between the measurement point and the preset temperature and the amount of change in the deviation over time, and
The total flow rate of the mixed gas of e gas and Ar gas is constant, and the thermal conductivity of the mixed gas is varied to maintain the substrate temperature at a set temperature.

Since the temperature of the heat stage is kept constant, this control is performed by PID (proportional, integral, differential) control of the flow rate regulator based on the reading of the radiation thermometer 7 and the deviation and change amount of the set temperature. .

Figure 3 shows an example in which sputtering was performed using the substrate heating device having the above configuration, in which a room-temperature substrate was clamped to a heat stage and heated to the set temperature of 400°C, and then sputtered using an aluminum target. 7 is a time chart showing changes in the substrate temperature and the flow rates of gases He and Ar when an AI film with a thickness of 1 μl is grown by applying a sputtering power of −7 to 7. It can be seen that as the substrate temperature approaches 400°C, the flow rate of He gas with high thermal conductivity decreases, the heat flow from the heat stage to the substrate decreases, and overshoot of the substrate temperature is prevented. . And the substrate temperature is 400
It can be seen that when sputtering starts when the temperature becomes stable at .degree. C., the heat flow flowing into the substrate increases, so that the flow rate of He gas is further reduced to maintain the substrate temperature constant.

In addition, in the case of control that rapidly raises or lowers the substrate temperature, at the same time as raising or lowering the temperature of the heat stage, the flow rate ratio of the mixed gas is adjusted so that the coefficient of thermal conduction to the substrate is maximized or minimized. By controlling the temperature of the substrate, the temperature of the substrate can be quickly changed.

〔Effect of the invention〕

As explained above, according to the substrate heating device of the present invention, it is possible to heat the substrate with good reproducibility regardless of the type of substrate, and to rapidly control the substrate temperature, and it is possible to heat the substrate with good reproducibility regardless of the type of substrate, and it is possible to rapidly control the substrate temperature, and it is possible to heat the substrate with good reproducibility regardless of the type of substrate. When used in equipment, it has a remarkable effect on stabilizing the quality of thin films and improving equipment throughput.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a diagram of an embodiment of the present invention, FIG. 3 is a time chart of changes in substrate temperature and gas flow rate, and FIG. 4 is a schematic diagram of a conventional substrate heating device. It is. In the figure, 1 - heat stage, 2 - one substrate, 3a, 3b -
Flow rate regulator, 4-Gas inlet, 5-Vacuum container
6-vacuum pump, 7-radiation thermometer,
8-sputter target, 9
・- Sputtering gas inlet, 10-
Temperature controller, 11-・-Thermocouple, 12-・
- heater, 13 - flow rate control means, d. - gap between the heat stage and the substrate. ■ The present invention is based on the figure 9 and 7 of the ``Fang Fang Self I column'' of the first figure 1 and 7]7. Soshit□ship＾Shime time 1000 V vine map

Claims (1)

[Claims] A substrate heating device used in a film forming apparatus, which heats a substrate (2) on its periphery and faces the substrate (2) through a gap (d) in other areas. a stage (1); a gas supply means (3a, 3b) for introducing a mixed gas consisting of two or more types of gases having different thermal conductivities into the gap (d); a substrate temperature detection means (7); a control means for controlling the mixing ratio of the mixed gas so as to control the substrate temperature by changing the amount of heat flowing from the heat stage (1) to the substrate (2) based on the result;
13) A substrate heating device comprising: