JP3236533B2 - Electrostatic attraction electrode device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic attraction electrode device used for supporting a wafer in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In recent years, a method of supporting a wafer has become an issue in increasing the diameter of a semiconductor wafer (from 6 inches to 8, 12 inches). In the conventional mechanical clamping method, when a large-diameter wafer is used, the in-plane wafer temperature varies.
Further, due to the influence of the clamp ring, the characteristics of the peripheral portion of the wafer are poor, and the number of semiconductor products to be obtained decreases. In addition, there are other problems such as the curvature of the wafer, the large number of components in the reaction chamber, and the generation of particles due to the dropout of by-products attached to the clamp ring. Currently, the wafer is held and the temperature of the wafer is controlled using static electricity such as Coulomb force and Johnsen-Rahbek force. In this case, the process characteristics of the wafer become uniform up to the peripheral portion, thereby increasing the number of wafers that can be removed. In addition, the number of components in the reaction chamber is reduced, and there is no direct contact with the wafer, so that generation of particles can be suppressed.

An example of the above-mentioned conventional electrostatic attraction electrode will be described below with reference to the drawings. FIG. 5 is a structural view of a conventional electrostatic attraction electrode, and FIG. 6 is an enlarged view of an outer peripheral portion of the electrode. In FIG. 5, reference numeral 1 denotes a wafer to be processed. 2
Is an electrostatic attraction electrode. Reference numeral 3 denotes a focus ring for protecting the outer peripheral portion of the electrostatic chucking electrode or for confining plasma, and reference numeral 4 denotes a high-frequency oscillator for applying high-frequency power to the wafer. Reference numeral 5 denotes a power supply for applying a DC high voltage to the electrostatic attraction electrode 2, reference numeral 6 denotes a resistor for preventing a high frequency from entering the DC high-voltage power supply 5, and reference numeral 7 denotes a mechanism for correcting the high voltage. 9 is a by-product produced by the process, and 16 is a deposit of the by-product.

[0004] The operation of the electrostatic chucking electrode configured as described above will be described below using a dry etching apparatus as an example. First, the wafer 1 to be processed by the transfer system of the apparatus is transferred and installed on the electrostatic chucking electrode 2.
The wafer 1 is transferred so as not to contact the focus ring 3. After adjusting the gas flow rate and pressure in the reaction chamber, high-frequency power is applied to the electrostatic chucking electrode 2 from the high-frequency oscillator 4 and the wafer 1 is etched. By applying a high DC voltage from the DC power supply 5 to the electrode 2 before and after the application of the high-frequency power, static electricity is generated between the wafer 1 and the electrode 2,
Etching is performed by adsorbing the wafer 1 to the electrode 2. At that time, mechanisms 6 and 7 for blocking and correcting the effects of high frequency
Is incorporated.

[0005]

However, in the above-described structure, as the etching proceeds, the (by-) product 9 having a low vapor pressure among the reaction products becomes an electrode as shown in FIG. 2 is deposited on the outer peripheral portion of the focus ring 3 and on the focus ring 3 to form a deposit 16, so that the peripheral portion or the whole of the wafer 1 does not come into contact with the electrode 2 due to the deposit 16, the temperature of the wafer during etching rises, Fluctuates. Further, cleaning (maintenance) for removing the deposit 16 is required. For this reason, there was a problem that the yield and the equipment operation rate were reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrostatic attraction electrode device capable of suppressing and preventing the accumulation of deposits on the outer peripheral portion of the electrostatic attraction electrode and the focus ring.

[0007]

In order to solve the above-mentioned problems, an electrostatic attraction electrode device according to claim 1 of the present invention comprises:
An electrostatic chucking electrode for mounting a wafer, a power supply for applying a voltage to the electrostatic chucking electrode to suck the wafer, and a mechanism for introducing a cooling gas to the back surface of the wafer to cool the wafer; Blows between the wafer and the electrostatic attraction electrode
The electrostatic suction is used to form a space through which the discharge gas flows.
The dimple-shaped protrusion or groove provided on the surface of the electrode is
By expanding to the outer periphery of the electroadsorption electrode,
A mechanism for allowing the discharge gas to reach the outer periphery of the wafer and blowing the discharge gas from the outer periphery of the wafer toward the outer periphery of the wafer.

As described above, the blowing between the wafer and the electrostatic attraction electrode is performed.
Electrostatic adsorption is used to create a space for pumping gas to flow.
Electrostatic adsorption of dimple-shaped protrusions or grooves provided on the pole surface
By expanding to the outer periphery of the electrode,
The allowed to reach the outer periphery of the wafer, and the outer peripheral portion of the wafer to blow balloon gas to the outer circumference of the wafer machine
With the structure, by-products having a low vapor pressure among the reaction products can be prevented from being deposited on the outer peripheral portion of the electrostatic adsorption electrode. Therefore, the wafer adheres to the surface of the electrostatic attraction electrode,
The wafer temperature can be controlled in a stable state. Also, usually
The surface of the electrostatic chuck has protrusions so that the cooling gas can spread.
Or dimples, as described above.
To extend the protrusion or groove to the outer periphery of the electrostatic chucking electrode
A configuration may be employed in which the blowing gas is blown to the outer periphery of the wafer. As a result, no deposits are deposited on the outer peripheral portion of the electrostatic attraction electrode. In this case, it is effective when the processing pressure in the reaction chamber is equal to or higher than the medium pressure region, and the deposition of the deposit can be suppressed even when the blowing amount of the cooling gas is small.

According to a second aspect of the present invention, there is provided an electrostatic attraction electrode device for mounting a wafer, a power supply for applying a voltage to the electrostatic attraction electrode for attracting the wafer, and a wafer for cooling the wafer. A mechanism for introducing a cooling gas to the back surface, a focus ring for protecting an electrostatic chucking electrode arranged on the outer periphery of the wafer, and a pipe for flowing a blowing gas to the focus ring are provided. The gas for blowing was blown out from the blow-out opening opened at the end. As described above, the gas for blowing is blown out from the outlet of the pipe opened on the surface of the focus ring, so that by-products are blown away by this gas, and deposits are deposited on the outer peripheral portion of the electrostatic adsorption electrode and the focus ring. I will not do it. In this case, it is effective even in a low pressure region other than the high and medium pressure regions where the processing pressure in the reaction chamber is high.

According to a third aspect of the present invention, in the electrostatic attraction electrode device according to the first or second aspect , the blowing gas is a cooling gas. Since the cooling gas is blown out in this manner, a cooling gas for cooling the wafer can be used.
Further, since the deposition is suppressed by using a cooling gas for cooling the wafer, the configuration can be easily made with only a slight change as compared with a conventional apparatus. Further, the cooling gas is usually an inert gas such as helium, has no reactivity, and does not affect the semiconductor device manufacturing process.

According to a fourth aspect of the present invention, in the first aspect , the blowing gas is a process gas. Since the process gas is blown out in this way, no other gas is mixed into the process gas.
It does not affect the process. An electrostatic attraction electrode device according to claim 5, wherein an electrostatic attraction electrode for mounting a wafer,
A power supply for applying voltage to the electrostatic chucking electrode to attract the wafer, a mechanism for introducing a cooling gas to the back side of the wafer to cool the wafer, and a protective mechanism arranged on the outer periphery of the wafer to protect the electrostatic chucking electrode And a heating mechanism for heating the focus ring. in this way,
Since a heating mechanism for heating the focus ring is provided, by-setting the focus ring to a temperature higher than the boiling point or sublimation point of the by-product prevents the by-product from being deposited. And the wafer temperature can be controlled in a stable state. This is effective when only one or a small amount of process gas is used in the low pressure region. Further, no other gas is mixed into the process gas.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic attraction electrode device according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view of an outer peripheral portion of an electrode of an electrostatic chucking electrode device according to a first embodiment of the present invention, and FIG. 2 is a conceptual diagram showing an entire configuration of the electrostatic chucking electrode device. In FIG. 2, 1 is a wafer to be processed, 2 is an electrostatic attraction electrode, and 3 is a focus ring (guide ring, covering) for protecting the outer peripheral portion of the electrostatic attraction electrode or for confining plasma. A high DC voltage is applied to the electrostatic attraction electrode 2 by a DC high voltage power supply 5 to attract the wafer 1. In general, helium gas used as a cooling gas is distributed over the entire surface of the wafer 1 by dimples or grooves on the surface of the electrostatic attraction electrode 2. This is used as a coolant for cooling the wafer 1, and has a structure in which the wafer 1 is shut off at the outer peripheral portion and does not leak into the reaction chamber. Also in this embodiment, as shown in FIG. 1, dimple-shaped projections 8 are provided on the surface of the electrostatic attraction electrode 2 in order to form a space between the wafer 1 and the electrostatic attraction electrode 2 where helium gas flows efficiently. It is. Also, the wafer 1
1 equipped with a mechanism for blowing gas for blowing in the outer circumferential direction
I have. In this case, the helium gas is blown from the back surface of the wafer 1 toward the focus ring 3 by expanding the protrusion 8 to the outer peripheral portion. The helium gas to be blown out can be controlled by the flow rate or the pressure. Note that a groove through which helium gas flows may be formed on the surface of the electrostatic attraction electrode 2 instead of the projection 8.

In FIG. 2, 4 is a high-frequency oscillator for applying high-frequency power to the wafer 1, 6 is a resistor for preventing high-frequency power from entering the DC high-voltage power supply 5, and 7 is a high-voltage corrector. Mechanism. In FIG. 1, reference numeral 9 denotes a by-product generated by the process, and reference numeral 10 denotes a flow of helium gas. The operation of the electrostatic chucking electrode device configured as described above will be described below with reference to FIG. Here, the case of a dry etching apparatus will be described.

First, the wafer 1 to be processed by the transfer system of the apparatus is transferred and set on the electrostatic attraction electrode 2. The wafer 1 is transported so as not to come into contact with and run on the focus ring 3. After adjusting the gas flow rate and pressure in the reaction chamber, high-frequency power is applied to the electrostatic chucking electrode 2 from the high-frequency oscillator 4 and the wafer 1 is etched. By applying a high DC voltage to the electrostatic attraction electrode 2 from the DC high voltage power supply 5 before and after applying the high frequency power (before applying the high frequency power in the case of the bipolar method, and after applying the high frequency power in the case of the monopolar method), By generating static electricity such as Coulomb force or Jansen-Rahbek force between the wafer 1 and the electrostatic attraction electrode 2, the wafer 1 is attracted to the electrode 2 to perform etching. Thereby, the wafer temperature can be controlled, and stable etching can be realized. At this time, the effect of the high frequency is cut off by the resistor 6 and the high voltage is corrected by the correction mechanism 7.

Further, as described above, the helium gas spreads over the entire wafer 1 and the helium gas is made to reach the focus ring 3, so that the helium gas generated by etching has a low vapor pressure. The product 9 is not deposited as a deposit on the outer peripheral portion of the electrostatic attraction electrode 2 or on the focus ring 3. At this time, the shape of the focus ring 3 on the side of the wafer 1 is changed (a tapered shape or a large number of holes are formed in the focus ring 3), and the exhaust direction of the process gas is shifted downward from the outer peripheral portion of the focus ring 3. By doing so, the flow of helium gas into the wafer surface is suppressed.

This embodiment is effective when the etching processing pressure is in the middle pressure range or higher. Even when the amount of helium gas blown out is small, the deposition of deposits can be suppressed. This helium gas is an inert gas, has no reactivity, and hardly contributes to the process. As described above, according to this embodiment, by providing a mechanism for blowing helium gas near the focus ring 3,
Since deposits do not accumulate on the outer peripheral portion of the electrostatic chucking electrode 2 and the focus ring 3, a part or the whole of the wafer due to the deposits does not float off the electrode surface as in the related art.
Therefore, the wafer temperature during the etching can be controlled stably. In addition, the yield can be improved, maintenance can be performed, and the time between maintenance can be extended, so that the equipment operation rate can be improved.

A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view of an outer peripheral portion of an electrode of an electrostatic chucking electrode device according to a second embodiment of the present invention. In the figure, reference numeral 11 denotes a mass flow controller (hereinafter abbreviated as MFC) for controlling a helium gas flow rate, and 12 denotes a gas pipe for flowing helium gas through a focus ring 3.
The outlet 12a opened on the surface of the focus ring 3
Gas is blown out from In this case, the outlets 12a are provided in two directions on the side surface and the upper surface of the focus ring 3 on the side of the electrostatic attraction electrode 2. However, either one of the outlets 12a may be used. In addition, this structure is provided at eight or more locations on the outer periphery of the electrostatic attraction electrode 2.

Further, unlike the first embodiment, the mechanism for introducing helium gas to the back surface of the wafer 1 does not extend the protrusions and the like to the outer peripheral portion of the electrostatic chucking electrode 2, The surface of the adsorption electrode 2 has a structure in which helium gas is confined between the adsorption electrode 2 and the wafer 1 (similar to the conventional method). Other configurations are the same as those of the first embodiment. The operation of the electrostatic attraction electrode device configured as described above will be described below.

The process up to the transfer of the wafer 1 and the dry etching is the same as that of the first embodiment. In this case, helium gas is blown out from the focus ring 3 to suppress the deposition of deposits. MFC1 newly provided
1 controls the flow rate of the helium gas and sends the helium gas to the focus ring 3 via the gas pipe 12. The by-product 9 is blown off by the helium gas discharged from the outlet 12 a, and does not accumulate on the focus ring 3.

As described above, according to this embodiment,
By adopting a structure in which helium gas is blown out from the focus ring 3, the same effect as in the first embodiment can be obtained. However, this embodiment is also effective in a low pressure region other than the high and medium pressure regions. In addition, gas outlet 12
If a is limited to the upper part of the focus ring 3, it is possible to directly blow out a process gas instead of a helium gas. This is because the gas diffuses immediately in the low pressure region.

A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of an outer peripheral portion of an electrode of an electrostatic chucking electrode device according to a third embodiment of the present invention. In the figure, 13 is a temperature adjusting mechanism, 14 is a heater for heating the focus ring 3, and 15 is a thermocouple for measuring the temperature.
The difference from the first and second embodiments is that the focus ring 3 is heated in this manner. Also, wafer 1
The mechanism for introducing the helium gas into the back surface of the device is the same as that of the second embodiment, and the surface of the electrostatic chucking electrode 2 has a structure in which the helium gas is confined to the wafer 1 (as compared with the conventional method). Similar). Other configurations are the same as those of the first embodiment.

The operation of the electrostatic attraction electrode device configured as described above will be described below. The steps up to the transfer of the wafer 1 and the dry etching are the same as those of the first embodiment. Then, this time, the heater 14 embedded in the focus ring 3 is heated by using the temperature adjustment mechanism 13. By setting the focus ring 3 to a temperature higher than the boiling point or sublimation point of the by-product, the by-product 9 will not be deposited. For example, when etching polysilicon, 100 ° C.
By doing so, no by-products are deposited. The temperature of the heater 14 is controlled by a thermocouple 15.

By heating the focus ring as described above, the same effects as in the first embodiment can be obtained. However, it is also effective when only one or a small amount of process gas is used in the low pressure region. Further, unlike the first and second embodiments, helium gas is not mixed into the process gas. In the third embodiment, the heater 14 is used as the heating method. However, depending on the temperature range, brine such as water whose temperature is controlled may be used.

Although the three embodiments have been described above, it is also possible to combine any of them instead of using each of them alone.

[0025]

According to the electrostatic attraction electrode device according to the first aspect of the present invention , a blowing gas is provided between the wafer and the electrostatic attraction electrode.
On the surface of the electrostatic attraction electrode to form a space through which
Provide the dimple-shaped protrusion or groove provided on the outer periphery of the electrostatic attraction electrode.
Gas to the wafer
A mechanism to reach the outer periphery and blow out the blowing gas from the outer periphery of the wafer toward the outer periphery of the wafer is provided, so that by-products having a low vapor pressure among the reaction products are removed at the outer periphery of the electrostatic adsorption electrode. Can be prevented. Therefore, the wafer is in close contact with the surface of the electrostatic chucking electrode, and the temperature of the wafer can be controlled in a stable state, the yield can be improved, the maintenance time can be extended, and the equipment operation rate can be improved. Also, usually, the surface of the electrostatic adsorption
Are provided with protrusions or grooves so that the cooling gas
The dimple-shaped protrusions or grooves as described above.
By expanding to the outer periphery of the adsorption electrode,
Can be sprayed around the wafer.
You. As a result, deposits are formed on the outer peripheral portion of the electrostatic attraction electrode.
It does not accumulate. In this case, the processing pressure in the reaction chamber
Effective in the medium pressure range and above.
Even when the amount is small, accumulation of sediment can be suppressed.

[0026]

According to the second aspect of the present invention , the blowing gas is blown out from the outlet of the pipe opened to the surface of the focus ring, so that by-products are blown off by this gas, and the by-product is blown off to the outer peripheral portion of the electrostatic attraction electrode and the focus ring. No sediment is deposited. In this case, it is effective even in a low pressure region other than the high and medium pressure regions where the processing pressure in the reaction chamber is high. Claim
In 3 , the cooling gas is blown out, so that a cooling gas for cooling the wafer can be used. Further, since the deposition is suppressed by using a cooling gas for cooling the wafer, the configuration can be easily made with only a slight change as compared with a conventional apparatus. In addition, the cooling gas is usually an inert gas such as helium, there is no reactivity at all,
It does not affect the semiconductor device manufacturing process.

According to the fourth aspect , since the process gas is blown out, no other gas is mixed into the process gas, and the process gas is not affected. According to the electrostatic attraction electrode device according to claim 5 of the present invention, since the heating mechanism for heating the focus ring is provided, by setting the focus ring to a temperature higher than the boiling point or the sublimation point of the by-product, As a result, the wafer is brought into close contact with the surface of the electrostatic attraction electrode, and the temperature of the wafer can be controlled in a stable state. This is effective when only one or a small amount of process gas is used in the low pressure region. Further, no other gas is mixed into the process gas.

[Brief description of the drawings]

FIG. 1 is a sectional view of an outer peripheral portion of an electrode of an electrostatic chucking electrode device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing the entire configuration of the electrostatic chucking electrode device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of an outer peripheral portion of an electrode of an electrostatic chucking electrode device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an outer peripheral portion of an electrode of an electrostatic attraction electrode device according to a third embodiment of the present invention.

FIG. 5 is a conceptual diagram showing an overall configuration of an electrostatic attraction electrode device according to a conventional embodiment.

FIG. 6 is an explanatory view showing a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wafer to be processed 2 Electrostatic attraction electrode 3 Focus ring for protecting the outer periphery of the electrostatic attraction electrode or for confining plasma 4 High frequency oscillator for applying high frequency power to wafer 5 Electrostatic attraction electrode A power supply for applying a DC high voltage 6 A resistor for preventing a high frequency from entering a DC power supply 7 A mechanism for correcting a high voltage 8 A dimple-like projection or groove for efficiently flowing helium gas between the wafer and the electrode surface Reference Signs List 11 mass flow controller for controlling helium gas flow rate 12 gas pipe for flowing helium gas through focus ring 12a outlet 13 temperature control mechanism 14 heater for heating focus ring 15 thermocouple for measuring temperature

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/68

Claims (5)

(57) [Claims] 1. An electrostatic chuck electrode for mounting a wafer, a power supply for applying a voltage to the electrostatic chuck electrode for sucking the wafer, and a cooling gas introduced to the back surface of the wafer for cooling the wafer. Mechanism and the electrostatic absorption
To form a space for blowing gas to flow between the electrodes
The dimple-like projections provided on the surface of the electrostatic chucking electrode
Or extending the groove to the outer periphery of the electrostatic chucking electrode.
The blowing gas reaches the outer periphery of the wafer
Is allowed, the electrostatic chucking electrode apparatus having a mechanism which is the outer peripheral portion of the wafer to blow balloon gas to the outer circumference of the wafer. 2. An electrostatic chucking electrode for mounting a wafer ,
Apply voltage to the electrostatic chucking electrode to chuck the wafer
Power supply and the backside of the wafer to cool the wafer
A mechanism for introducing a cooling gas to the outside of the wafer;
Focus for protecting the electrostatic attraction electrode arranged on the circumference
Flowing gas for blowing into the ring and the focus ring
Pipes for fitting, and the surface of the focus ring of the pipe
Blows out the gas for blowing from the blowing port
Electrostatic attraction electrode device for smooth operation . 3. The blowing gas is a cooling gas.
Item 3. The electrostatic attraction electrode device according to Item 1 or 2 . 4. The method according to claim 1, wherein the blowing gas is a process gas.
3. The electrostatic attraction electrode device according to claim 1 or 2 . 5. An electrostatic chuck electrode on which a wafer is placed;
Apply voltage to the electrostatic chucking electrode to chuck the wafer
Power supply and the backside of the wafer to cool the wafer
A mechanism for introducing a cooling gas to the outside of the wafer;
A focus ring arranged around the periphery to protect the electrostatic chucking electrode
And a heating mechanism for heating the focus ring.
Comprising the electrostatic chucking electrode device.