JPH0797582B2 - Surface treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a surface treatment apparatus such as a dry etching apparatus or a thin film deposition apparatus used in a manufacturing process of a semiconductor integrated circuit element, and particularly to a reaction. The present invention relates to a surface treatment apparatus capable of heating and maintaining an inner wall of a container at a predetermined temperature to improve reproducibility of a process and reduce dust which causes a decrease in yield of elements.

(Prior Art) A manufacturing process of a semiconductor integrated circuit device is mainly performed by repeating thin film deposition and fine processing.

Conventionally, a physical vapor deposition method such as a sputtering method or a vapor deposition method or a chemical vapor deposition method has been generally used as a thin film deposition process. The chemical vapor deposition method under reduced pressure (reduced pressure CVD method) is becoming mainstream because it is easy to control and the coating property of the film on the step portion of the substrate surface is good.

On the other hand, for fine processing of thin films, dry etching techniques such as reactive ion etching (RIE) and plasma etching are used.

Both the dry etching method and the low pressure CVD method have a common point that surface treatment is performed under reduced pressure inside a vacuum container.

The stability of the process in these surface treatment steps is greatly influenced by the state of the inner wall of the vacuum container. That is, for example, when a deposited film formed by an etching product or a reaction gas adheres to the inner wall of the container, the resistance to a high-frequency voltage or a DC voltage, which is an excitation source of plasma, changes, and the released gas is re-emitted from the deposited film. These affect the etching rate, the thin film formation rate, or the thin film composition, and deteriorate the reproducibility of the process. Further, when the deposited film attached to the inner wall of the vacuum container is peeled off, dust is attached to the substrate to be processed,
The yield of the device is deteriorated.

To prevent the adhesion of the deposited film to the inner wall of the container and the peeling of the deposited film, heat the inner wall to a certain temperature or higher and keep the temperature constant to suppress the fatigue of the film due to the temperature change. Is effective.

(Problems to be Solved by the Invention) As means for heating the inner wall of the vacuum container, there are a method of heating from the outside of the entire vacuum container and a method of inserting a heater inside the vacuum container to heat only the inner wall. To be

The former method is characterized in that the entire container can be heated uniformly. However, the gate valve for loading the wafer into the vacuum container, the gas and introduction valve, and the vacuum exhaust valve are also heated at the same time. Therefore, it is necessary to use heat-resistant materials for all these vacuum sealing materials. There is. In this case, polyimide is a relatively high heat-resistant sealing material,
The practical heat resistance temperature is about 200 ° C, and it cannot be used at higher temperatures. Also, metal seals and Teflon seals have high heat resistance, but once plastic deformation occurs,
Since it has a property that it does not return to its original shape and many semiconductor wafers are repeatedly processed, it cannot be used in a semiconductor manufacturing apparatus in which the valve operation frequency is high. Moreover, since the temperature rises around the vacuum container, it is difficult to arrange the driving parts such as the motor near the vacuum container.

On the other hand, when the heater is inserted inside the vacuum container as in the latter case, it is possible to cool the drive parts for transportation such as the seal portion and the motor outside the container. For example, the inner wall of the container may be covered with a heater in which a conductive heating element is coated with an insulating material, and the outside of the container may be water-cooled to protect external parts and O-ring seals. it can.

However, in this case, the temperature of the wall in contact with the heater is low, and a large temperature gradient is generated inside the heater. This temperature gradient deteriorates the uniformity of temperature above the heater.
That is, the temperature is high just above the heating element and is low at the portion without the heating element, resulting in uneven temperature.

When such a temperature difference occurs on the upper surface of the heater, there is a problem in that the deposited film is remarkably promoted in the high temperature portion or the low temperature portion, or the deposited film at the boundary portion between the two becomes unstable and is more likely to be peeled off. .

Therefore, in the conventional surface treatment apparatus using the vacuum container, the heating temperature of the container is set to 200 ° C. or lower, or the uniformity of the inner wall temperature is sacrificed, and the heating means having a large local temperature unevenness has to be used. It was

(Object of the Invention) The present invention eliminates the above-mentioned drawbacks of the prior art, enables the inner surface of the container to be uniformly heated to 200 ° C. or more, and cools the outer wall of the container and the vacuum-sealed portion. It is an object of the present invention to provide a surface treatment apparatus which is effective for the stability of surface treatment and reduction of dust in

[Structure of Invention]

(Means for Solving the Problem) A surface treatment apparatus of the present invention comprises a vacuum container for accommodating a substrate to be treated and a means for evacuating the inside of the container, and introducing a predetermined reaction gas into the vacuum container. Then, in the surface treatment apparatus for performing etching or thin film shape on the surface of the substrate to be treated, having a laminated structure of a thermally anisotropic insulating material and a conductive material,
An electric heater having a function of heating the inner wall of the vacuum container to 200 ° C. or higher is installed in contact with the inner wall of the vacuum container so that the direction in which the thermal conductivity of the thermally anisotropic insulating material is maximum coincides with the wall surface direction. It is characterized by having done.

(Operation) In the surface treatment apparatus of the present invention configured as described above, since the thermal anisotropic material is used as the insulating material of the heating means, no temperature gradient occurs inside the heater. This is because the thermal conductivity in the in-plane direction, which maximizes the thermal conductivity, is sufficiently high, and the thermal conductivity is easy in the in-plane direction, while the thermal conductivity in the direction perpendicular to it is small, and the thermal conductivity is perpendicular to the wall surface. This is because it is difficult for heat to transfer in this direction.

Therefore, there is no difference in temperature between the temperature directly above the heating element and the gap between the heating elements, and the uniformity of the heater upper temperature is improved.

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

FIG. 1 is a schematic configuration diagram showing a copper dry etching apparatus according to a first embodiment of the present invention.

In the figure, on the upper and lower surfaces of the vacuum container 1, first and second electrodes 2 and 3 forming a part thereof are arranged so as to face each other. The first electrode (anode) 2 is directly fixed to the upper surface of the vacuum container 1 and is directly grounded by the lead wire 4. Second
The electrode (cathode) 3 is fixed to the lower surface of the vacuum container 1 via the insulator 5, and high frequency power is applied from the high frequency power supply 7 via the matching circuit 6.

The inner surface of the vacuum container 1, the inner surface of the exhaust pipe 8 from the vacuum container 1 to the exhaust means, and the inner surface of the vacuum partition valve 9 inserted in the middle of the exhaust pipe 8 are coated with heating means 10, respectively.

On the upper surface of the second electrode (cathode) 3, a sample table 11 for mounting a substrate to be etched is mounted. A heating means (not shown) for heating the substrate to be etched is provided inside the sample table.

A water cooling pipe 12 is arranged on the outer surface of the vacuum container 1. Reference numeral 13 denotes a gas introduction pipe which penetrates the first electrode 2 and the heating means 10 and opens in the vacuum container 1.

As shown in FIG. 2, the heating means 10 comprises an electric heater having a structure in which an insulating material 10a and a conductive material 10b are laminated.
In this electric heater, graphite is used as the conductive material 10b that functions as a heating element, and the insulating material 1b is used.
As 0a, for example, a thermally anisotropic material such as hexagonal boron nitride BN is used. The electric heater has a thermal anisotropy material whose thermal conductivity is maximized in the wall surface direction to be coated,
The wall surface of the vacuum container 1 or the like is covered in a predetermined direction.

As described above, in the surface treatment apparatus of the present invention, a thermally anisotropic material (for example, hexagonal BN) is used as the insulating material of the electric heater, so that as shown in FIG. There is no temperature gradient. As shown in FIG. 2, the thermal conductivity in the a-axis direction, which maximizes the thermal conductivity, is sufficiently large, for example, 0.5 cal / sec / cm ² / ° C / cm, and the thermal conductivity is in the in-plane direction. However, the thermal conductivity in the c-axis direction perpendicular to the a-axis is as small as 0.037 cal / sec / cm ² / ° C / cm, and it is difficult for heat to be transmitted in the direction perpendicular to the plane. In addition, in FIG. 2, the length of the arrow represents the magnitude of the thermal conductivity of the a-axis and the c-axis.

Further, since the outer surfaces of the vacuum container 1 and the exhaust pipe 8 are cooled by flowing the cooling water through the water cooling pipe 12, as shown in FIG. 4, the O-ring 14 used in the vacuum partition valve is used.
Are kept at a low temperature. That is, as a result of the experiment, if the distance from the O-ring 14 to the electric heater 10 is set to 20 mm or more, even if the inside of the vacuum container 1 or the exhaust pipe 8 is heated to 300 ° C or more, the O-ring temperature rises to 150 ° C or more. It turns out not to.

According to the vacuum device configured as described above, the inner surface of the vacuum container can be maintained at a temperature of 200 ° C. or higher, for example, 300 ° C., and moreover, the etching product of copper Cu can be attached to the inner surface of the vacuum container. Without the need for copper etching.

FIG. 5 is a schematic view showing a dry etching apparatus for silicon Si according to the second embodiment of the present invention. In this embodiment, the heating means 10 is coated only on the inner surface of the first electrode 2 and the inner surface of the side wall of the container 1, and other configurations are the same as those in FIG.

FIG. 6 is a top view of FIG. 5, and a thermal oxide film 15 having a thickness of about 1,000 angstroms is formed on a part of the lower surface of the electric heater which is the heating means 10 and covers the inner wall of the first electrode 2. Has been placed.

Here, the electric heater 10 is turned off, chlorine gas C12 is introduced into the vacuum container 1 through the gas introduction pipe 13, and high frequency power is applied from the high frequency power supply 7 to the second electrode 3 through the matching circuit 6. And is mounted on the sample base 11
The Si substrate was etched to form a deposition film of etching products on the thermal oxide film 15.

The amount of this deposited film depends on the distance from the center of the vacuum container 1.

FIG. 7 shows the relationship between the distance from the center of the vacuum container and the deposition rate of etching products. At this time, the vacuum container 1
As a result of measuring the inner wall temperature at 10 points at equal intervals, the uniformity [(Max-Min) / (Max + Min)] was 50%.

Next, the temperature of the electric heater was set to 200 ° C., and the same experiment as above was performed without changing other conditions. The relationship between the distance from the center of the vacuum container and the deposition rate was as shown in FIG. The uniformity of the inner wall temperature of the vacuum vessel was within 10%.

FIGS. 9 and 10 show the temperature of the electric heater 10 at 100 ° C., 200 ° C. and the heater O when the Si substrate is etched with chlorine gas C12 in the surface treatment apparatus having the same configuration as FIGS. 5 and 6.
The number of etchings in the case of FF and the corresponding
FIG. 7 is a characteristic diagram showing a relationship with the Si etching rate or the number of dusts.

As is clear from Fig. 9, the temperature of the electric heater is 200 ° C.
In that case, the etching rate is almost constant even when 75 sheets are etched, but when the electric heater temperature is 100 ° C. or the heater is turned off, the etching rate decreases from around 25 sheets. Also, as can be seen from FIG. 10, when the electric heater temperature is 100 ° C. or the heater is OFF, dust rapidly increases when the number of etchings exceeds 25, but when the heater temperature is 200 ° C. Occurrence of is suppressed.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 11 shows a CVD apparatus using microwave electron cyclotron resonance (ECR) plasma. In the vacuum chamber 1, a microwave 21 of 2.45 GHz is introduced through a rectangular waveguide 22. The inner surface of the vacuum container 1 is coated with the heating means 10 having the same structure as described with reference to FIG.

A magnetic coil 23 is provided around the vacuum container 1 to realize an electron cyclotron condition. The etching gas is introduced into the vacuum container 1 through the gas introduction pipe 13 and is guided to the exhaust means (not shown) through the exhaust pipe 8. In addition, in the cooling chamber 24 provided outside the vacuum container 1, the pipe 25
Cooling water is introduced via. The sample is placed on the sample table 11.
26 is placed and surface treatment such as dry etching and thin film deposition is performed.

FIG. 12 shows a temperature-voltage characteristic diagram of the heating means 10 provided in the above-mentioned first, second and third embodiments, in which a deposited film is not formed on the inner wall of the vacuum container 1, and The uniformity of the temperature inside the vacuum vessel is also greatly improved.

〔The invention's effect〕

As described above, the surface treatment apparatus of the present invention has a laminated structure of a thermally anisotropic insulating material and a conductive material, and the thermal conductivity of the thermally anisotropic insulating material is maximized. Since the electric heater configured so as to match the wall surface direction is installed in contact with the inner wall of the container, the inner wall of the container can be uniformly heated to 200 ° C. or higher, and the stability of the surface treatment in the manufacturing process of the semiconductor element and the dust It can greatly contribute to the reduction.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a surface treatment apparatus showing a first embodiment of the present invention, FIG. 2 is an explanatory view of heating means (electrothermal heater) used in the apparatus of the present invention, and FIG. 3 is shown in FIG. 4 is a graph showing the relationship between the internal position of the heating means and the temperature, FIG. 4 is a vertical cross-sectional view of the vicinity of the mounting portion of the vacuum partition valve, and FIG. 5 is a schematic configuration of a surface treatment apparatus showing a second embodiment of the present invention. Figure,
FIG. 6 is a top view (reduction) of FIG. 5, FIGS. 7 and 8 are characteristic diagrams of the deposition rate of etching products with respect to the distance from the center of the vacuum vessel in the apparatus of FIG. 6, and FIG. Fig. 10 is a characteristic diagram of the etching rate with respect to the number of sheets, Fig. 10 is a characteristic diagram showing the relationship of the number of dust with respect to the number of etchings
FIG. 11 is a schematic configuration diagram of a surface treatment apparatus according to the third embodiment of the present invention, and FIG. 12 is a heating means 10 used in the present invention.
It is a characteristic view showing a temperature-voltage relationship of. 1 ... Vacuum container, 2 ... First electrode, 3 ... Second electrode, 4 ... Lead wire, 5 ... Insulator, 6 ... Matching circuit, 7 ... High frequency power supply, 8 ... Discharge Tube, 9 ... Vacuum partition valve, 10 ... Heating means, 11 ... Sample mounting table, 12 ...
Water cooling pipe, 13 …… Gas introduction pipe, 14 …… O-ring, 21…
… Microwave, 22 …… rectangular waveguide, 23 …… magnetic coil,
24 …… Cooling chamber, 25 …… Piping, 26 …… Sample.

Claims (1)

[Claims] 1. A vacuum container for accommodating a substrate to be processed, and means for evacuating the inside of the container, wherein a predetermined reaction gas is introduced into the vacuum container to form an etching or thin film on the surface of the substrate to be processed. In the surface treatment apparatus for performing, a thermoelectric insulating material having a laminated structure of a conductive material and an electrically conductive heater having a function of heating the inner wall of the vacuum container to 200 ° C. or higher, A surface treatment apparatus, wherein the surface treatment apparatus is installed in contact with the inner wall of the vacuum container so that the direction in which the thermal conductivity is maximum coincides with the wall surface direction.