JPH0487321A - Holding device of object to be treated in vacuum treatment apparatus - Google Patents

Abstract

PURPOSE:To cool an electrostatic chuck and an object, to be treated, which is held on it to 0 deg.C or lower even when they are cooled by cooling water at about room temperature by a method wherein a thermoelectric cooling element is arranged and installed on an electrode provided inside a vacuum container and the electrostatic chuck is provided on it. CONSTITUTION:A Peltier element sheet 16 as a thermoelectric cooling element and an electrostatic chuck 18 are fixed and installed sequentially, in a contact state, on a recessed part 14A on the surface side of an electrode block 14. A cooling-water passage 14C is formed inside the electrode block 14 and is connected to a cooling-water pipe 22. A DC electric current at about 20 V is applied to the Peltier element sheet 16 from a constant-current power supply 34. A temperature difference of about 40 deg.C can be set between the cooling side coming into contact with the electrostatic chuck sheet 18 and the heating side coming into contact with the electrode block 14. The temperature of the electrostatic chuck 18 is detected by using a temperature sensor 30 and is transmitted to a temperature control device 32. The temperature control device 32 changes the constant current value of a constant-current power supply 34 and controls the temperature of the electrostatic chuck sheet 18 and of a wafer.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a vacuum processing apparatus such as an etching apparatus used in the manufacturing process of semiconductor elements such as ICs and LSIs, and more specifically relates to a vacuum processing apparatus such as an etching apparatus used in the manufacturing process of semiconductor elements such as ICs and LSIs. The present invention relates to an object holding device.

[Prior art j] With the miniaturization of LSIs in recent years, development is performed by etching the resist layer using a vacuum processing device such as a reactive ion etching device that generates gas plasma such as oxygen plasma. Dry development processes have been proposed to form resist patterns.

By the way, in such a dry development process, the mask and the substrate to be processed are heated by the heat of chemical reaction with plasma and the impact energy of ions, electrons, etc., and if the temperature is not well controlled, , the desired fine pattern cannot be formed due to deformation of the substrate or the like.

Therefore, various techniques for cooling the substrate have been proposed in order to eliminate such inconveniences.

For example, in Japanese Patent Application Laid-Open No. 1-302726, an electrostatic chuck is disposed on an electrode in which a coolant passage is formed, and the entire electrode is cooled by introducing liquid nitrogen, a fluorine-based coolant, etc. into the coolant passage. , a technique has been disclosed in which a workpiece adsorbed by an electrostatic jack is cooled.

[Problem to be Solved by the Invention 1] However, when the entire electrode is cooled using a refrigerant as in the past, there are the following problems.

(1) It is not easy to maintain the temperature of the substrate, which is the object to be processed, at a required temperature, for example, 0° C. or lower. And 0
In order to maintain the temperature below ℃, a large amount of refrigerant is required to be circulated, and a large chiller is also required.

(2) The refrigerant must be supplied through the vibrator, and there is a risk of damage to other loom parts due to dew condensation on the vibrator's surface.

(3) Since the heat capacity of the entire electrode is large, the responsiveness of temperature control of the substrate to be processed is poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve such conventional problems and provide a workpiece holding device for a vacuum processing apparatus that is capable of temperature control using ordinary cooling water and has excellent temperature control responsiveness. .

[Means for Solving the Problems] In order to achieve such objects, the present invention provides an electrode provided in a vacuum container, a thermoelectric cooling element disposed on the electrode, and the thermoelectric cooling element. An electrostatic chuck disposed on the electrostatic chuck.

[Function 1] According to the present invention, an object to be processed is held in an adsorbed state by an electrostatic chuck disposed on a thermoelectric cooling element on an electrode, and a predetermined vacuum processing is performed.

At this time, a predetermined current is passed through the thermoelectric cooling element. As a result, the electrostatic chuck side (primary side) of the thermoelectric cooling element is cooled and the electrode side (secondary side) is heated due to the Beltier effect, creating a predetermined temperature difference between the two.

Therefore, even if the electrode is cooled, for example, with cooling water at about room temperature, the electrostatic chuck and the workpiece held thereon can be kept at a temperature of, for example, 0°C or less, which is a simple and low-cost solution. Desired temperature control can be performed using a cooling device.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

1 to 3 show an embodiment in which the present invention is applied to a reactive ion etching apparatus.

In the figure, IO is a reaction vessel, and the vessel itself constitutes an electrode.

A support stand 12 is provided on the lower side of the reaction vessel 10, and this support stand 12 has a built-in mechanical wafer lift mechanism for raising and lowering a wafer serving as a substrate to be processed.
An electrode block I4 is provided on top of the electrode block I4. A disk-shaped recess 14A is formed on the upper surface side of the electrode block 14, and a Vertier element plate 16 and an electrostatic chuck plate 18 as a thermoelectric cooling element, which will be described later, are placed in this recess 14A.
are fixedly connected in order.

Through holes 14B,
16A and 18A are formed.

In the electrode block 14, a permanent magnet 20 is provided sandwiching the through hole 14B, and pole pieces 20A and 20B made of a magnetic material are provided at both ends of the permanent magnet 20, respectively. Pole pieces 20A and 20B are offset to face both ends of recess 14A. A cooling water passage 14C is provided in the electrode block 14, and a cooling water pipe 22
It is connected to the.

Since the structure of the Beltier element plate 16 is widely known, a detailed explanation will be omitted, but in this embodiment,
It consists of diodes with alternating electrodes arranged between upper and lower alumina plates. It is possible to use a commercially available product.

The electrostatic chuck plate 18 is preferably a bipolar type in which at least two flat plate electrodes are embedded in a ferroelectric material made of a polymeric material such as polyvinylidene fluoride or a ceramic such as alumina, From the viewpoint of thermal conductivity, ceramic is preferable. Further, as for the shape of the flat plate electrode, it is preferable to use a circular electrode and an annular electrode surrounding it, or a plurality of concentric rings with different radii, which alternately serve as positive and negative electrodes.

As shown in FIG. 3, a plurality of concentric inert gas introduction grooves 18C are formed on the surface of the electrostatic chuck plate 18, and the introduction grooves 180 are communicated with each other by a radial groove 18D.

An introduction hole 18E formed through the electrostatic chuck 18 is opened in the radial groove 18D.

Note that the shape of the groove is not particularly limited as long as it can fill inert gas between the wafer and the electrostatic chuck plate 18 (for example, it may be spiral or grid-like). Good too.

Further, the electrostatic chuck plate 18 is provided with openings 18B extending in three radial directions at equal angular intervals, and a wafer receiver 24A of the lid 24 for loading and unloading wafers is disposed in the openings 18B.

A presser plate 26 made of stainless steel is provided on the outer peripheral edge of the electrostatic chuck plate 18, which is installed on the electrode block 14.
are provided, and by tightening the presser plate 26 with screws 2g, 28..., the Peltier element plate 16 and the electrostatic chuck plate 18 are fitted into the recess 14A of the electrode block 14.
It is fixed inside while maintaining the contact state.

Note that 30 is a temperature sensor embedded in the electrostatic chuck plate 18 and connected to a temperature control device 32. Furthermore, the temperature control device 32 includes a side of the Peltier element plate 16 that contacts the electrostatic chuck plate 18 (cooling side);
and a constant current power source 34 for the Bertier element, which is connected to the side (heating side) in contact with the electrode block 14, respectively.

Furthermore, a high voltage of 0 to 2 KV is supplied to the electrodes of the electrostatic chuck plate 18 from a high voltage power source 36 for electrostatic chuck.

Further, the electrode block 14 is connected to a high frequency power source 38.

Therefore, in the reactive ion etching apparatus of this embodiment, the reaction vessel 1 is etched by a pump from the exhaust port 40.
After evacuating the inside of 0 to a high vacuum, remove the vibrator 4 from the reaction gas container.
2, a reaction gas such as oxygen, or together with this reaction gas an inert gas such as nitrogen, is introduced into the reaction vessel 1O via flow control valves. High frequency power is applied from a high frequency power supply 38 to the electrode block 14 to generate plasma of a reactive gas, and the wafer suctioned and fixed to the electrostatic chuck plate 18 is etched.

In this etching step, a space formed by the wafer (not shown) and the inert gas introduction groove 18G of the electrostatic chuck plate 18 has a supply vibrator 4 communicating with the introduction hole 18E.
A refrigerant gas such as helium is introduced through the wafer 4 and conducts the heat generated on the wafer to the electrostatic chuck plate 18 side. However, in the cooling water passage 14G in the electrode block 14,
Cooling water at about room temperature is circulated and supplied via the cooling water pipe 22, and the electrode block 14 is maintained at about room temperature.

Furthermore, the Beltier element plate 16 is connected to a constant current power source 34.
A DC voltage of approximately 0 V is applied, and a temperature difference is generated between the cooling side in contact with the electrostatic chuck plate 18 and the heating side in contact with the electrode block 14, depending on the applied current.

Therefore, for the Beltier element plate 16, it is possible to set this temperature difference to about 40°C, and even if the electrode block 14 is at about room temperature, the temperature of the electrostatic chuck plate 18 is 0°C or less, As a result, it is possible to reduce the temperature of the wafer to a desired temperature of 0° C. or lower.

This means that in the case of the conventional method of bringing the electrostatic chuck and electrode block into direct contact and cooling the electrode block with a coolant, in order to keep the electrostatic chuck below 0°C, the electrode block must also be kept below 0°C. This is very different from what we are forced to do.

Note that the temperature of the electrostatic chuck plate 18 is detected by a temperature sensor 30 and sent to a temperature control device 32. The temperature control device 32 changes the constant current value of the constant current electric current 1a34 to control the temperature of the electrostatic chuck plate 18 and, by extension, the wafer.

According to the present invention, the time required to control the electrostatic chuck plate 18 to a predetermined temperature, that is, to shift from a changing state to a stable state (hereinafter referred to as "characteristic time"), is 30 seconds or less. It was possible.

Next, FIG. 4 shows an embodiment in which the present invention is applied to other types of equipment.

In this embodiment, microwaves are used as plasma generation means, and anisotropy is imparted to the plasma by applying low frequency power to the electrode block holding the wafer and other electrodes.

In this embodiment, parts that are functionally the same as those in the previous embodiment are given the same reference numerals to avoid redundant explanation.

In this embodiment, a quartz window 10 is provided at the top of the reaction vessel 10.
A is provided, and a microwave waveguide 10B and a microwave oscillator IOC are provided through this quartz window 10A.

An electrode block 14 is provided on the support stand 12 on the lower side of the reactor 10, facing the quartz window 10A, and a small Vertier element plate 16 is provided on the upper surface of the electrode block 14.
0.160... are placed individually, and an electrostatic chuck plate 18 is placed on top of them. and,
The outer periphery of the electrostatic chuck plate 18 and the electrode block 14 are directly fastened with screws 28, and the Veltier element plate 160, the electrostatic chuck plate 18, and the electrode block 14
It is believed that there is close contact with

Furthermore, the outer peripheries of the electrostatic chuck plate 18 and the electrode block 14 are covered with a glass cover 50.

This is to prevent a large amount of reactive gas plasma from reaching the side surface of the Peltier element plate 160 and damaging the Vertier element plate 160. Furthermore, the electrode block 14 in this embodiment is connected to a low frequency power source (50 to 100 Kt(z)) 52.

In this embodiment, as in the previous embodiment, during the etching process, cooling water at about room temperature is circulated through the cooling passage 14G of the electrode block 14 through the cooling water pipe 22, and a DC voltage is applied to the Peltier element plate 160. By this,
It is possible to cool the electrostatic chuck plate 18, and thus the wafer, to below 0°C.

[Effect of the invention 1] As is clear from the above explanation, the workpiece holding device of the vacuum processing apparatus of the present invention can hold the workpiece at, for example, 0°C.
During cooling, temperature can be controlled using ordinary cooling water, and costs can be reduced. Furthermore, since the temperature control has excellent responsiveness, it is also advantageous in terms of work efficiency.

In particular, the present invention is suitable for a reactive ion etching apparatus as a dry developing apparatus for dry developing resist.

FIG. 3 is a plan view of an embodiment of the present invention; FIG. 4 is a sectional view showing another embodiment of the present invention.

lO...reaction container, 14...electrode block, 14A...cooling water passage, 16.160...Bertier element board, 18... Electrostatic chuck plate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
Enlarged view of part of the figure,

Claims (1)

[Claims] 1) An electrode provided in a vacuum container, a thermoelectric cooling element disposed on the electrode, and an electrostatic chuck disposed on the thermoelectric cooling element. Features: A workpiece holding device for vacuum processing equipment.