JP2000164582A - Plasma processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plasma processing system in which the reproducibility and reliability of process can be sustained for a long term at low cost without causing any fluctuation in the etching characteristics due to aging by controlling the inner temperature of a reactor and deposition of reaction products on the wall surface. SOLUTION: A plasma processing system processes a wafer W by generated plasma in a processing chamber 100 through interaction of electromagnetic wave radiated from a UHF band antenna 110 disposed in the processing chamber and a magnetic field formed by a field forming means 101 disposed on the periphery of the processing chamber 100. A jacket 103 is held replaceably on the side wall 102 of the processing chamber 100 in order to control the temperature on the inner surface of the side wall at a constant level. With regard to components which can be applied with a bias in the reactor, i.e., a ring 116 and a sample ring 132, a structure for applying a bias is provided at least to a part thereof and total thermal capacity of the component is reduced sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus suitable for forming a fine pattern in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a plasma processing apparatus is widely used in a fine processing process such as film formation, etching and ashing. The process by the plasma processing is performed by converting a process gas introduced into a vacuum chamber (reactor) into plasma by a plasma generating means, reacting on a semiconductor wafer surface, performing fine processing, and exhausting volatile reaction products. , And performs predetermined processing.

[0003] In this plasma processing process, the temperature of the inner wall of the reactor or the wafer, or the state of deposition of reaction products on the inner wall has a great effect on the process. Further, if the reaction products deposited inside the reactor are peeled off, they cause dust, leading to deterioration of element characteristics and a decrease in yield.

For this reason, in a plasma processing apparatus,
In order to keep the process stable and suppress the generation of foreign matter, it is important to control the temperature inside the reactor and the accumulation of reaction products on the surface.

[0005] For example, Japanese Patent Application Laid-Open No. Hei 8-144072 discloses that
In order to improve the selectivity in the dry etching step of the silicon oxide film, the temperature of each part inside the reactor is raised by 150 ° C. or more higher than the temperature of the etching stage.
℃ to 300 ℃ (preferably 200 to 250 ℃
A dry etching apparatus for controlling and maintaining a high temperature value of the following (3) with an accuracy of within ± 5 ° C. is described. By controlling the temperature of each part of the inner surface of the reactor to a high temperature in this manner, the amount of the plasma polymer adhering to the inner surface of the reactor decreases, the amount of the plasma polymer adhering to the semiconductor wafer increases, and the selectivity increases. improves.

Japanese Patent Application Laid-Open No. 5-275385 discloses that in a parallel plate type plasma processing apparatus, at least one of a clamp ring (processing object holding means) and a focus ring (plasma concentrating means) is generated by plasma processing. An apparatus provided with a heating means for raising / maintaining a temperature at which a reaction product does not adhere is described. As the heating means, a resistance heating element is used. Since the adhesion of the reaction product can be prevented by heating, peeling of the reaction product and adhesion of particles to the surface of the object to be processed are reduced.

[0007]

As described above, in a plasma processing apparatus, it is important to control the temperature of the inner wall surface of the chamber and the deposition of reaction products on the inner wall surface.

However, when the temperature of the inner wall surface of the chamber, particularly the side wall surface having a large area, is set to a high temperature of about 200 ° C. to 250 ° C. or more, the etching characteristics become very sensitive to the temperature of the inner wall surface, and the process reproducibility and There is a problem that the reliability tends to decrease.

For example, SCMcNevin, et al., J. Vac.
ci.Technol. B 15 (2) Mar / Apr 1997, p.21, 'Chemical
In the challenge of submicron oxide etching ', in inductively coupled plasma, the side wall temperature is 200 ° C to 17 ° C.
It is shown that when the temperature changes to 0 ° C., the oxide film etch rate increases by 5% or more. It is presumed that the reason is that more carbon is adsorbed on the wall due to the decrease in the side wall temperature, the carbon deposition on the wafer is reduced, and the oxide film etch rate is increased.

As described above, particularly in the case of high-density plasma, since plasma strongly interacts with the inner wall of the reactor in a high-temperature region, a change in temperature balance inside the reactor causes deposition of reaction products on the inner wall surface and composition of the surface. The change proceeds rapidly and appears as a change in the etching characteristics.

Further, in a high temperature region, the interaction between the plasma and the inner wall becomes very sensitive to a change in temperature. For example, when quartz (SiO ₂ ) is used as the inner wall surface material, a thermodynamic relation between the etch rate of F ₂ atoms of SiO ₂ and the wall temperature has been reported, and (DLFlamm,
et al., J. Appl. Phys., 50, p.6211 (1979)), when this relational expression is applied to a temperature range of 150 ° C or higher, the wall temperature becomes 2
From 00 ° C. to 250 ° C. or higher, the etch rate rapidly increases exponentially.

Therefore, in such a high-temperature region, high accuracy is required for temperature control, for example, within ± 5 ° C. However, since the inner wall surface is exposed to high-density plasma, it is not easy to control the temperature of the wall surface in such a high-temperature region with high accuracy. In order to realize this, a temperature detecting means and a heating means such as a heater or a lamp are used for the temperature control, but the mechanism and means of the temperature control are overwhelming. Further, in such a high-temperature region, since no reaction product is deposited on the inner wall surface, the wall surface is consumed by being etched by the plasma. Therefore, it is necessary to periodically replace parts on the inner wall surface, which leads to an increase in cost of consumables. Further, since large energy is required for heating, it is not preferable from the viewpoint of energy consumption.

A similar problem applies to the heating of the ring around the electrode. Although heating the ring to raise the temperature can prevent the reaction products from adhering, the heating mechanism such as a resistance heating element complicates the device configuration. Further, even if the adhesion of the reaction product can be prevented, if the ring and the inner wall surface are etched and consumed by the plasma, the constituent material itself may become a new dust generation source. Furthermore, when parts of the ring and the inner wall surface are worn, they need to be replaced periodically, which leads to an increase in running cost of the apparatus.

One way to solve these problems is to
That is, a contaminant which may become a foreign substance attached to the inner wall surface of the chamber is protected by a polymer surface coating layer. For example, in Japanese Patent Application Laid-Open No. 7-312363, a gas which forms a polymer in an etching gas (processing gas) is added, and the temperature of a support of a work piece (workpiece) is higher than that of a chamber wall. A plasma etching apparatus is described, which is maintained as described above and formed into a coating layer by forming a contaminant surface coating layer attached to the inner wall surface of the chamber. Then, by capturing and accumulating the contaminant particles in the polymer film, the residual accumulation of the contaminant in the chamber due to the reaction product is reduced.

However, in this case, the purpose is not to protect the wall surface but to capture the contaminant particles. In addition, special means such as introducing a gas different from the etching gas to form a surface coating layer on the inner wall surface of the chamber or capturing a reaction product by etching with the surface coating layer formed by the added gas are used. I need. The temperature of the wall surface at the time of forming the surface coating layer is described as a value lower than the work piece (workpiece) by 5 ° C. or more in order to prevent the formation of the coating layer on the work piece. And the accuracy of the control is not taken into account.
The pressure range is also a high pressure range of several hundred mtorr (several tens of Pa). However, it is assumed that the deposition temperature of the film changes the composition and quality of the film, and affects the peel strength of the film and the generation of foreign matter. Further, the temperature fluctuation of the deposited film is predicted to lead to the generation and cracking of cracks due to the repetition of thermal expansion and contraction, and to cause foreign matters, and the accuracy of temperature control is an important factor. In addition, several tens mtorr or less (several Pa or less)
In the pressure range described above, it is considered that the film deposition situation is different due to high ion energy and a long mean free path of molecules. Further, in the above-mentioned known example, it is necessary to remove the coating layer containing the contaminants from the wall surface of the plasma processing chamber, which directly affects the throughput of the apparatus and the cost of consumables, but this point is not considered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reproduces a process by controlling the temperature inside the reactor and the deposition of reaction products without introducing a special additive gas. It is an object of the present invention to provide a plasma processing apparatus capable of maintaining performance and reliability over a long period of time and at low cost.

[0017]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that, in the region where the pressure in the reactor is several Pa or less, the temperature of the wall surface of the processing chamber provided in the vacuum vessel is constant. It was found that a strong coating film was formed on the inner wall surface due to the composition of the etching gas when the control was performed. As a result of more detailed analysis, this coating film has a solid layered structure formed by polymer polymerization progressing as the temperature at the time of film formation is lower, and by controlling the temperature at the time of film formation to be constant. That is, it was found that the film surface was not peeled or damaged and did not cause dust generation.

In the above, the temperature of the inner wall surface of the reactor should be lower than the temperature of the wafer by 5 ° C. or more, preferably 20 ° C.
Control within ± 10 ° C within the range of ℃ or lower.

Meanwhile, inside the reactor,
There are also parts or components that are difficult to control in the low temperature range as described above. The present inventors have studied these points and found a method of controlling the temperature and the deposition of reaction products on the surface without having a complicated heating mechanism such as a heating resistor. Reached.

The present invention provides a vacuum vessel evacuated by vacuum evacuation means, gas introduction means for introducing a processing gas into the vacuum vessel, and a static chamber for mounting a wafer inside the vacuum vessel. Electroadsorption device, a lower electrode, a bias power supply for supplying bias power connected to the lower electrode, having means for radiating high frequency in the vacuum vessel,
In the plasma processing apparatus for processing the sample to be processed by converting the processing gas into plasma, a disk-shaped conductor connected to a high-frequency bias power supply and opposed to the lower electrode in the vacuum vessel; An antenna composed of a plate in contact with the conductive body is provided, preferably, a distance between the plate and the wafer is set to 30 mm or more and 150 mm or less, and the vacuum chamber forms a processing chamber having a side wall, Provides a plasma processing apparatus in which the temperature is controlled to form a coating film on the inner wall surface by the composition of a processing gas at the time of etching.

The present invention further provides a plasma processing apparatus in which the side walls are controlled in temperature by the circulating supply of the heat medium from the heat medium supply means.

The present invention further provides a plasma processing apparatus in which a ring is provided on an outer peripheral side of the plate, and the ring forms a coating film by a processing gas composition on a surface in contact with plasma during etching processing. .

Another feature of the embodiment of the present invention is that the inner wall component has a ring shape, and the surface area of the component in contact with plasma is not more than 20% of the total area of the processing chamber wall.

Another feature of the embodiment of the present invention is that the component in which the bias is applied to at least a part of the inside of the processing chamber in contact with the plasma is ring-shaped,
The thickness is 6 mm or less, and the inner diameter is not less than the sample diameter.

Still another feature of the embodiment of the present invention is that, in the above-described plasma processing apparatus, the plasma generating apparatus uses a magnetic field UHF band electromagnetic wave radiation system.

According to the present invention, a part of the processing gas is polymerized by the plasma discharge, and a surface coating layer of a polymer is formed on a part of the inner wall surface of the processing chamber which is in contact with the plasma or on the surface of the component. Then, by controlling the temperature of the inner wall surface of the reactor to a constant temperature at the above-described temperature, the polymer polymerization of the coating layer proceeds, and a firm layered structure can be formed. Therefore, since the inner wall surface is not consumed by being etched by the plasma, the frequency of replacement of parts on the inner wall surface can be reduced, and the running cost can be reduced. In addition, since the coating layer has a close film composition, even if it is exposed to plasma, the surface does not peel or damage, so that it does not cause dust generation.

Further, since the temperature of the inner wall surface of the chamber is set to the above-mentioned temperature range, the interaction between the plasma and the inner wall surface is weaker than when the inner wall surface is set to a high temperature region of 200 ° C. or more. Moreover, it is not sensitive to temperature changes. For this reason, the reproducibility and reliability of the process are unlikely to decrease over a long period of time, and the accuracy of temperature control may be, for example, within ± 10 ° C., and can be relatively easily realized without using a complicated mechanism for temperature control. It becomes possible.

When a polymer film exceeding a predetermined value is formed on the inner wall surface, it is necessary to remove this film. This film removal process is not cleaning, but the device is opened to the atmosphere, the components on the wall of the processing chamber where the polymerized film is formed are replaced, the device is started again, and the film is removed by removing it from the chamber by wet cleaning etc. By performing the ex-situ and regenerating the inner wall surface, the downtime of the apparatus is reduced and the throughput is not reduced, and the cost of consumables can be reduced by regenerating and repeatedly using parts. Further, by adding a process for suppressing the growth of the polymer film during the treatment, the time until the device is opened and the cleaning can be extended.

On the other hand, according to still another feature of the embodiment of the present invention, a structure in which a bias is applied to at least a part of a part or a component in which temperature control is difficult in the above-described region inside the reactor. And the heat capacity of the whole part is made sufficiently small, so that the whole part can be controlled in a high temperature range without using a complicated mechanism such as a heater or a lamp. It is possible to reduce the generation of foreign matter due to the separation of the product. Also, by reducing the surface area of the component, even if the temperature or the surface state changes, the influence on the process can be suppressed. Further, by adjusting the degree of the bias applied to the above-mentioned components, and setting the temperature in the range of 100 ° C. or more and 250 ° C. or less, preferably 150 ° C. or more and 200 ° C. or less,
Compared to a case where the temperature is set to a high temperature range of about 250 ° C. or more, the temperature is less sensitive to a temperature change, so that there is an advantage that the temperature fluctuation of the components can be reduced to a level that does not substantially affect the process.

[0030] According to yet another aspect of the present invention,
The temperature of components that come into contact with the plasma inside the processing chamber can be controlled more actively and precisely in the high-temperature region using infrared irradiation and gas heat transfer, so that excessive deposition of reaction products is suppressed and reaction generation is suppressed. It is possible to reduce the generation of foreign substances due to the peeling of the object and to suppress the influence on the process by suppressing the fluctuation of the temperature and the surface state. Furthermore, by controlling the temperature within the range of 100 ° C. or more and 250 ° C. or less, desirably within the range of 150 ° C. or more and 200 ° C. or less with a precision of ± 10 ° C., compared with the case where the temperature is set to a high temperature region of approximately 250 ° C. or more,
Since it is not sensitive to a temperature change, there is an advantage that the temperature fluctuation of the component can be reduced to a level that does not substantially affect even finer processes.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a magnetic field UHF band electromagnetic wave radiation discharge type plasma etching apparatus, and is a schematic sectional view of the plasma etching apparatus.

In FIG. 1, the processing chamber 100 has a ^{capacity of} 10 ^−6.
A vacuum container capable of achieving a degree of vacuum of about Torr, an antenna 110 for emitting electromagnetic waves as plasma generating means is provided at an upper part thereof, and a lower electrode 130 for mounting a sample W such as a wafer is provided at a lower part thereof. I have. Antenna 110
And the lower electrode 130 are installed so as to face each other in parallel. An electromagnetic coil 101 is provided around the processing chamber 100.
A, 101B, yoke 101C magnetic field forming means 1
01 is provided, and a magnetic field having a predetermined distribution and intensity is formed. Then, by the interaction between the electromagnetic wave radiated from the antenna 110 and the magnetic field formed by the magnetic field forming means 101, the processing gas introduced into the processing chamber is turned into plasma to generate plasma P and process the sample W. .

A jacket 103 for controlling the temperature of the inner surface of the side wall is exchangeably held on the side wall 102 of the processing chamber 100. Then, the heat medium is circulated and supplied from the heat medium supply means 104 to the inside of the jacket 103 to control the temperature. The temperature of the jacket is controlled in the range of 0 ° C to 100 ° C, preferably 20 ° C to 80 ° C, with an accuracy within ± 10 ° C. On the other hand, the processing chamber 100 is evacuated by the evacuation system 106 connected to the vacuum chamber 105, and
The inside of 0 is adjusted to a predetermined processing pressure of 0.1 Pa or more and 10 Pa or less, preferably 0.5 Pa or more and 4 Pa or less. The processing chamber 100 and the vacuum chamber 105 are at the ground potential. Side wall 102 of processing chamber 100, jacket 10
Numeral 3 is a non-magnetic metal material containing no heavy metal and having good heat conductivity, such as aluminum, and may be subjected to a surface treatment such as plasma-resistant alumite on the surface.

An antenna 110 for radiating an electromagnetic wave includes a disk-shaped conductor 111, a dielectric 112, and a dielectric ring 113, and is held by a housing 114 as a part of a vacuum vessel. Further, a plate 115 is provided on the surface of the disc-shaped conductor 111 which is in contact with the plasma, and a ring 116 is provided on the outer periphery thereof. A processing gas for performing processing such as sample etching and film formation is supplied from the gas supply means 117 at a predetermined flow rate and a predetermined mixing ratio.
11 and through a number of holes provided in the plate 115,
The gas is supplied to the processing chamber 100 while being controlled to a predetermined distribution.

The antenna power supply 1 is connected to the disc-shaped conductor 111.
21, an antenna high-frequency power supply 122 is connected via a matching circuit / filter system 123, 124, respectively.
Also, it is connected to the ground through the filter 125. The antenna power supply 121 is desirably from 300 MHz to 900
MHz UHF band frequency, and the antenna 11
Electromagnetic waves in the UHF band from 0 are emitted. On the other hand, the antenna high-frequency power supply 122 applies a low frequency of, for example, about 100 kHz, or several MHz to 10 M
By applying a high frequency bias of about Hz, the reaction on the surface of the plate 115 in contact with the disc-shaped conductor 111 is controlled. Since the plate 115 is opposed to the wafer, it has the greatest influence on the processing process. However, by applying a bias to this surface and not depositing a reaction product, the apparatus process is stabilized. Also, for example, CF
In the oxide film etching using a system gas, the material of the plate 115 is made of high-purity silicon or carbon, so that F radicals or CF on the surface of the plate 115 can be formed.
By controlling the reaction of the x radical, the composition ratio of the radical is adjusted. Distance between the lower surface of plate 115 and wafer W (hereinafter, referred to as
The gap is called 30 mm or more and 150 mm or less, preferably 50 mm or more and 120 mm or less.

The temperature of the disc-shaped conductor 111 is maintained at a predetermined value by a temperature control means (not shown), that is, a heat medium circulating in the inside, and the surface temperature of the plate 115 in contact with the disc-shaped conductor 111 is controlled. Is done. Ring 116
Is heated by a bias from the antenna high-frequency power supply 122 and temperature controlled, which will be described in detail later.

An antenna 110 is provided below the processing chamber 100.
The lower electrode 130 is provided so as to face. A bias power supply 141 for supplying a bias power in a range of 400 kHz to 13.56 MHz is connected to the lower electrode 130 via a matching circuit / filter system 142 so that the sample W
And the filter 14
3 to ground.

A sample W such as a wafer is mounted and held on the upper surface, that is, the sample mounting surface, by the electrostatic chuck 131. The electrostatic attraction device 131 has a dielectric layer for electrostatic attraction (hereinafter abbreviated as an electrostatic attraction film) formed on an upper surface thereof. The DC power supply 144 for electrostatic attraction and the filter 1
45 to apply a DC voltage of several 100V to several kV,
By generating a Coulomb force acting between the sample W and the electrostatic suction device 111 via the electrostatic suction film, the sample W is sucked and held on the lower electrode 130. As the electrostatic adsorption film, for example, aluminum oxide or an insulating film in which titanium oxide is mixed with aluminum oxide is used.

Further, the surface temperature of the sample W is controlled to a predetermined temperature by temperature control means (not shown) in order to control the surface reaction. For this purpose, the lower electrode 13
At 0, an inert gas, for example, He gas is supplied at a predetermined flow rate and pressure to increase the heat transfer between the electrostatic adsorption device 131 and the sample W. This allows
The temperature of the wafer is controlled in a range of at most about 100C to 110C or less.

The sample W on the upper surface of the electrostatic chuck 131 is
A sample stage ring 132 is provided on the outside of the.
For the sample stage ring 132, ceramics such as SiC, or carbon, silicon, or quartz material is used. Sample table ring 1
Reference numeral 32 denotes a dielectric 133 such as alumina, which is insulated from the electrostatic chuck 131. Further, the bias power from the bias power source 141 is partially leaked to the sample stage ring 132 via the insulator 133 and is applied to the sample stage ring 132.
It is also possible to adjust the bias application to 2 to control the reaction on its surface. For example, in the case of oxide film etching using a CF-based gas, if the material of the sample stage ring 132 is made of high-purity silicon, the reaction of F radicals and CFx radicals on the surface of the sample stage ring 132 by the scavenging action of silicon. Adjustment can improve the etching uniformity particularly at the outer peripheral portion of the wafer. The sample stage ring 132 is heated by the bias,
The temperature is controlled by cooling with the heat transfer gas, which will be described in detail later.

The plasma etching apparatus according to the present embodiment is configured as described above, and a specific process for etching a silicon oxide film using the plasma etching apparatus will be described with reference to FIG. I do.

First, a wafer W to be processed is loaded into the processing chamber 100 from a sample loading mechanism (not shown), and then placed and sucked on the lower electrode 130. Then, if necessary, the height of the lower electrode is adjusted to a predetermined gap. Next, the inside of the processing chamber 100 is evacuated by the evacuation system 106. On the other hand, gases necessary for etching the sample W, for example, C ₄ F ₈ and Ar
From the plate 115 of the antenna 110 at a predetermined flow rate and mixing ratio, for example, an Ar flow rate of 300 sccm and a C ₄ F ₈ flow rate of 8 sccm from the gas supply means 117.
Supplied to At the same time, the processing chamber 100 is
The pressure in the processing chamber 100 is adjusted to a predetermined processing pressure, for example, 1 Pa. On the other hand, the magnetic field forming means 101 forms a magnetic field having a predetermined distribution and strength. Then, the antenna 1 is
An electromagnetic wave in the UHF band is emitted from 10, and a plasma P is generated in the processing chamber 100 by interaction with a magnetic field. The plasma P dissociates the processing gas to generate ions and radicals.
By controlling the bias power supply 141, processing such as etching is performed on the wafer W. Then, with the end of the etching process, the supply of the power and the processing gas is stopped, and the etching is ended.

The plasma processing apparatus according to the present embodiment is constructed as described above. However, each part in the reactor, in particular, the inner surface of the side wall 103 and the ring 116, the sample stage ring
132 temperature control and reaction product deposition control
This will be described specifically.

First, the side wall 103 will be described with reference to FIG. As described above, the side wall 10 of the processing chamber 100
A jacket 103 is held inside 2 so that the temperature can be controlled by a heat medium.

The present inventors have conducted experiments at a pressure of 2 Pa using a mixed gas system of C ₄ F ₈ and Ar as a processing gas for etching an oxide film. As a result, the temperature of the inner wall surface of the reactor was set to a wafer temperature (about 100 ° C.). It has been found that a strong coating film is formed on the inner wall surface when the temperature is controlled within a range of 25 ° C. to 80 ° C., which is sufficiently lower than about (° C.), with a precision within ± 10 ° C. Dozens of mtor like this
In the pressure range of r or less (several Pa or less), ions with high energy increase, and it is considered that the effect of ion assist in film deposition increases and a tight film is formed. The state of the deposited film was such that when the side wall temperature was low, a dense and strong film was formed, and when the side wall temperature was high, the structure was slightly rough.
In order to quantitatively clarify this change in film quality, the composition (element concentration ratio) of the film deposited at side wall temperatures of 25 ° C., 50 ° C., and 80 ° C. was analyzed by XPS (X-ray photoelectron spectroscopy).
The following results were obtained.

Side wall temperature C (%) F (%) C / F ratio 25 ° C. 45.6 51.1 0.89 50 ° C. 43.9 53.8 0.82 80 ° C. 40.6 58.2 0.70 As is clear from this result, the lower the side wall temperature, the higher the carbon-rich film quality. Although not shown here, the analysis of the Cls peak shows that the lower the side wall temperature is, the more the bonding between carbons is progressing, and that the polymer polymerization is progressing. It can be inferred that this was observed as a dense and strong film in the macro.

In this experiment, the temperature of the side wall surface was ± 1.
Since the temperature is controlled with an accuracy of 0 ° C. or less, no internal stress is generated due to a temperature change during the deposition of the film, and the film structure is expected to be dense. As a result of observation with an electron microscope, it was confirmed that a firm layered structure was formed.
This film was very tight and strong. Even when the film was deposited to a film thickness of about 200 μm in the accelerated deposition test, no peeling of the film was observed in the tape peeling or friction test. Furthermore, it was found that this film showed high resistance to plasma, and that no peeling or damage was observed on the film surface even by the plasma treatment, which did not cause dust generation.

As described above, by controlling the temperature of the inner wall surface of the reactor at a temperature sufficiently lower than the wafer temperature, it is possible to form a strong deposited film in which no thermal stress is generated inside the inner wall surface of the reactor. This film has sufficient plasma resistance and acts as a protective film on the inner wall of the reactor because the separation of reaction products and the adhesion of particles to the sample surface are reduced. Therefore, since the side wall is not worn out or damaged, the frequency of replacement of parts on the side wall can be reduced, leading to a reduction in running cost. Further, since the side wall is protected by the deposited film, it is not necessary to use ceramics such as SiC having high plasma resistance, and the cost of parts can be reduced. In particular, if the side wall temperature is controlled in the range of from room temperature to about 50 ° C., less energy is required for heating the side wall, which leads to energy saving. As the sidewall material, a metal that does not contain heavy metals and has good heat conductivity, for example, aluminum may be used.

In the initial state where no deposited film exists,
Because the aluminum is exposed, the surface may be damaged due to the plasma damage. Therefore, in order to prevent this, the surface may be coated with a polymer material. Alternatively, the aluminum surface may be alumite-treated, for example, and the fine pores generated by the alumite treatment may be sealed with a polymer material. Of course, this sealing treatment can be applied without being limited to the alumite treatment of aluminum. In this way, by interposing a film made of a polymer at the interface between the aluminum surface and the deposited film, the adhesion between the aluminum surface and the deposited film is improved, and there is also an effect that the deposited film is hardly peeled off. Also,
Depending on the process, the film may be excessively deposited.In this case, by controlling the film deposition using a short-time plasma cleaning after the wafer processing, the film thickness can be kept constant. Good.

Next, the sample stage ring will be described. As already described in the embodiment of FIG.
2 controls the reaction on the surface by applying a bias, thereby making the etching characteristics particularly uniform at the outer peripheral portion of the wafer. At this time, the sample stage ring 132 is heated by the bias, but it is necessary to control the applied bias and the temperature in order to control the reaction on the surface and the deposition of the film. Moreover, it is desirable that the applied bias and the temperature can be controlled without incorporating a complicated mechanism into the lower electrode in which the electrostatic chuck 131 is incorporated. This can be realized by controlling the leakage bias and balancing the heating by the bias and the cooling by the gas heat transfer. This example
This will be described with reference to a sectional view (right half) of the lower electrode 130 shown in FIG.

The sample W is held by the electrostatic chuck 131. The electrostatic attraction device 131 is insulated from the ground 135 by the insulator 134. In this embodiment, the sample stage ring 13
2 is provided to the electrostatic attraction device 131 via the insulator 133 so that a part of the bias power supplied from the bias power supply 141 is leaked and applied. The applied bias can be adjusted by the thickness and material of the insulator 133. With such a bias application structure, the sample stage ring 1
There is no need to provide a wiring structure to the sample stage 32 or to connect another bias power source to the sample stage ring 132.

The electrostatic attraction device 131 is maintained at a predetermined temperature by circulating a heating medium for temperature control (not shown). A flow path 1 of a heat transfer gas (for example, He gas) is provided between the sample W and the surface of the electrostatic adsorption device 131.
36 are formed, and the heat transfer gas is introduced to maintain good heat conduction. Here, in the present embodiment, heat transfer gas flow paths 136A and 136B are also formed between the sample stage ring 132, the insulator 133, and the electrostatic adsorption device 131. Then, a part of the heat transfer gas for cooling the wafer is introduced, so that the heat conduction at the contact portion is kept good. For this reason, the sample stage ring 132 is connected to the electrostatic adsorption device 13 maintained at a predetermined temperature.
1 is kept good and the temperature is kept stable. As a result, the temperature fluctuation due to the application of the bias to the sample stage ring 132 is suppressed, and the surface reaction and the processing characteristics of the sample in the sample stage ring 132 can be stabilized. At the same time, since the deposition of the reaction product can be prevented by the heating by the bias and the ion assist, the exfoliation of the reaction product and the adhesion of the particles to the sample surface are reduced.

As described above, the sample stage ring can control the surface reaction, the temperature, and the film deposition with a simple structure by the application of the leakage bias, the balance between the heating by the bias, and the cooling by the gas heat transfer. Stabilization and reduction of foreign matter can be achieved.

In this embodiment, the heat transfer is ensured by the heat transfer gas. However, other heat transfer means such as a heat conductive sheet may be used.

Next, the antenna 110 will be described.
As already described in the embodiment of FIG.
An antenna high frequency power supply 122 is connected to
A bias of about Hz or several MHz is applied.
The temperature of the disc-shaped conductor 111 is maintained at a predetermined value by the heat medium. Therefore, a bias is applied to the plate 115 in contact with the disc-shaped conductor 111, and the surface temperature is controlled. Since the plate 115 is opposed to the wafer, it greatly affects the processing process. However, a bias is applied to this surface so that no reaction product is deposited, and the plate is made of high-purity silicon to use a scavenging effect. The process can be stabilized by using the surface reaction according to.

On the other hand, the ring 1 on the outer periphery of the plate 115
16 is the antenna high-frequency power source 1 as in the plate 115.
The responsiveness to temperature change is enhanced by heating with a bias from the antenna 22 and the antenna power supply 121 and further reducing the heat capacity of the ring 116. This will be described with reference to FIG.

FIG. 3 is an embodiment showing a method for controlling the temperature of the ring 116. In the present embodiment, the shape of the ring 116 is reduced, and a part thereof
Further, it is configured such that thermal contact with the dielectric ring 113 and the plate 115 is reduced. In this case, when the antenna high-frequency power is applied to the plate 115, ions are attracted to the surface of the ring 116 as indicated by the arrow in the drawing due to the bias on the plate 115. In this embodiment,
Since a heating mechanism such as a heater or a lamp is not used, there is an advantage that the mechanism is not complicated.

The width w of the bias applied portion of the ring 116
Is set to, for example, 10 mm or more so that heating by bias can be performed efficiently. The thickness of the ring 116 is, for example, 6 mm or less, preferably 4 mm or less in order to be effectively heated by the bias.

With such a thin shape, the heat capacity of the ring 116 is reduced. As a result, the entire ring is heated to about 100 ° C. to 250 ° C., preferably 150 ° C.
It becomes possible to heat to 200 ° C. or lower. As a result, the deposition of the reaction product is suppressed, and the generation of foreign matter due to the separation of the reaction product can be reduced. Further, in this temperature range, the change in the surface reaction is less sensitive to the temperature change than in the high temperature region of about 250 ° C. or higher, so that the temperature fluctuation of the component parts is small to a level that does not substantially affect the process. There are advantages that can be done.

The thickness of the ring 116 is determined by controlling the power and frequency of the antenna bias so that the deposition of the deposition film can be suppressed and the ring surface is not sputtered by ions and consumed.
It is determined by the balance between the material of the ring 116, the deposition rate of the reaction product on the ring 116, and the like. Further, as shown in the figure, the heat capacity of the entire ring may be further reduced by reducing the thickness except for the portion to which the bias is applied.
As described above, by reducing the heat capacity of the ring 116, the temperature rises with a high response in a short time in the initial stage of the processing, and thus the influence on the processing characteristics is small. Ring 1
It is desirable that the inner diameter d of 16 be larger than the diameter of the sample. Since the inner diameter of the reactor is about 1.5 times the sample,
For a sample diameter of 300 mm, the ring width s is about 50 mm
And the surface area is sufficiently small, for example, 20% or less with respect to the entire inner wall surface of the reactor. In this way, by reducing the surface area of the component, even if the temperature or the surface state changes, the influence on the process can be suppressed. Moreover, since the ring 116 is located on the outer peripheral portion of the wafer, the influence on the process is further reduced.

In the above embodiment, since the heating is performed by the passive heating using plasma, a certain degree of temperature fluctuation cannot be avoided. Even if this change does not become apparent in the current process, it may affect the etching characteristics due to the miniaturization of the processing process. In this case, a positive temperature control mechanism such as a lamp or heater is required. Becomes FIG. 4 shows an embodiment of a temperature control mechanism using lamp heating.

In this embodiment, the dielectric ring 113
A part of A is configured so that a bias can be applied by a structure 116A similar to the above-mentioned ring 116, and further, the dielectric ring 113A absorbs infrared light and far-infrared light on the side closer to the plasma, for example. An infrared absorber 151 such as an alumina thin film is formed. And infrared radiation means 1
Infrared light and far-infrared light are radiated from 52 and the infrared transmission window 15
3, pass through the dielectric ring 113A and pass through the infrared absorber 15
And heats the ring 116. Infrared absorber 1
Since 51 can be remotely heated by infrared rays, the temperature of the surface of the dielectric ring 113 exposed to plasma can be controlled with higher accuracy by installing the infrared absorber 151 on the side of the dielectric ring 113A close to the plasma. It becomes possible.

Further, since the infrared absorption is used for the heating mechanism, there is an advantage that the response is better than the heating by the heating resistor. Further, the dielectric ring 113A is also heated by the bias by the bias applying unit 116A, so that the temperature response is improved.

On the other hand, the infrared radiation means 152
4, the holder 154 and the dielectric ring 113
A gap is provided between the gas supply means A and the gas supply means 1.
Through 55, a heat transfer gas for temperature control is supplied. The heat transfer gas is sealed by vacuum sealing means 156A, 156B. Due to this gas heat transfer, the dielectric ring 113A is radiated through the holder 154. Therefore, for example, the heating is performed by the bias and the lamp at the start of the process, and the heat is released by the gas heat transfer during the process, thereby improving the accuracy of the temperature control. As a result, the temperature of the dielectric ring 123 is increased from about 100 ° C. to 250 ° C., preferably from 150 ° C. to 200 ° C.
It can be controlled with an accuracy of about ± 5 to 10 ° C. in the range of ° C. At this temperature, the deposition of the film is reduced, so that the generation of foreign matter due to the peeling of the film is suppressed. In addition, since the surface state of the dielectric ring 113A does not largely depend on the temperature, the surface state does not change, and stable plasma processing can be performed for a long time.

In each of the embodiments shown in FIGS. 3 and 4, the ring 116 in contact with the plasma and the dielectric ring 113A are heated to reduce the deposition of the film. As in the case of the inner surface of the side wall described in 1, the temperature can be controlled to be lower than the wafer temperature to form a stable deposited film. FIG. 5 shows this embodiment, in which the dielectric ring 113B is controlled in a temperature range of about 20 ° C. to 100 ° C. by temperature control using a refrigerant.

In this embodiment, a coolant for temperature control is supplied from a heat medium supply means 162 to a coolant passage 161 provided in the dielectric ring 113B. The cooling medium is a sealing means 1
Sealed at 63. The temperature of the dielectric ring 113B is maintained at a predetermined value by a temperature controller or a temperature detector (not shown). With such a configuration, the temperature of the dielectric ring 113B is set to 20 ° C. to 100 ° C. during the plasma processing.
It can be maintained in the range of about ° C. For this reason, a stable and strong film of the reaction product is deposited on the surface of the dielectric ring 123, so that the surface of the dielectric ring 123 is not worn away. If the film is excessively deposited by the process, use plasma cleaning together
The membrane may be kept at a constant thickness.

In each of the above embodiments, the plasma processing apparatus of the electromagnetic wave radiation discharge system having a magnetic field in the UHF band is used. However, the emitted electromagnetic wave is not limited to the UHF band, and may be a 2.45 GHz microwave. Waves or tens
The VHF band from about MHz to about 300 MHz may be used.
Further, the magnetic field is not always essential. For example, a magnetic field-free microwave discharge may be used. Further, in addition to the above, each of the above embodiments can be applied to, for example, a magnetron type plasma processing apparatus using a magnetic field, a parallel plate type capacitively coupled plasma processing apparatus, or an inductively coupled plasma processing apparatus.

FIG. 6 shows an embodiment of the present invention in which an RIE device using a magnetic field (a magnetron RIE device or a magnetically enhanced RIE device) is used.
RIE equipment). The processing chamber 100 as a vacuum container includes a side wall 102, a lower electrode 130 on which a sample W such as a wafer is placed via an electrostatic chuck 131, and an upper electrode 201 which is grounded in opposition thereto. Gas supply means 117 for introducing a predetermined gas into the vacuum vessel
A vacuum evacuation system 106 for depressurizing and evacuating the inside of the vacuum vessel, an electric field generating means 203 for generating an electric field between the lower electrode and the upper electrode, and a magnetic field generating means 202 for generating a magnetic field in the vacuum vessel. . The magnetic field generating means 202 has a plurality of permanent magnets or coils arranged in a ring shape on the outer periphery of the processing chamber 100, and forms a magnetic field substantially parallel to the electrodes inside the processing chamber. Then, the processing gas is turned into plasma by an electric field generated between the electrodes, thereby generating plasma P, and processing the sample W. Further, in the magnetron RIE, a magnetic field is formed in a direction substantially orthogonal to the electric field by the magnetic field generating means 202, so that the frequency of collision between electrons and molecules and atoms in the plasma increases, the plasma density increases, and the etching characteristics increase. Is obtained.

In this embodiment, similarly to the embodiment described with reference to FIG. 1, a jacket 103 for controlling the temperature of the inner surface of the side wall is exchangeably held on the side wall 102, and heat is supplied from the heating medium supply means 104 inside the jacket 103. The medium is circulated,
The temperature of the jacket is from 0 ° C to about 100 ° C, preferably 20 ° C.
The temperature is controlled within an accuracy of ± 10 ° C. within a range of from about 80 ° C. to about 80 ° C. The jacket 103 is made of, for example, anodized aluminum.

With this configuration, the inner wall surface of the reactor can be controlled at a temperature sufficiently lower than the wafer temperature, so that a strong deposited film can be formed on the inner wall surface of the reactor. This film has sufficient plasma resistance and acts as a protective film on the inner wall of the reactor, which reduces the separation of reaction products and the attachment of particles to the sample surface. Therefore, since the side wall is not worn out or damaged, the frequency of replacement of the side wall component can be reduced, leading to a reduction in running cost, and there is no need to use ceramics such as SiC having high plasma resistance, thereby reducing the component cost. Becomes possible.

Further, in this embodiment, similarly to the embodiment described with reference to FIGS. 1 and 2, a structure in which a part of the bias power supplied from the electric field generating means 203 is leaked to the sample stage ring 132, Cooling by gas heat transfer can stabilize the surface reaction on the sample stage ring 132 and the processing characteristics of the sample. At the same time, the deposition of the reaction product can be prevented by the heating by the bias and the ion assist, so that the separation of the reaction product and the adhesion of the particles to the sample surface are reduced.

FIG. 7 shows an example in which the present invention is applied to a parallel plate type plasma processing apparatus. Processing chamber 1 as vacuum vessel
Reference numeral 00 denotes a side wall 102, a lower electrode 130 on which a sample W such as a wafer is placed, an upper electrode 210 facing the lower electrode 130, and an electric field generator 221 for supplying electric power to the upper electrode 210 to generate an electric field between the electrodes. And A predetermined processing gas is supplied into the processing chamber 100 from the gas supply means 117, and the inside of the vacuum vessel is evacuated and evacuated by the evacuation system 106. Then, the processing gas is turned into plasma by an electric field generated between the electrodes, thereby generating plasma P, and processing the sample W. The upper electrode 210 includes an electrode plate 211 having an insulator 212,
The housing 214 is held insulated at 213. A plate 215 is provided on the surface of the electrode plate 211 on the side in contact with the plasma, and a shield ring 216 is provided on the outer periphery thereof. The shield ring 216 includes the insulators 212 and 21.
3 is protected from the plasma, and
2, the plasma density is improved by confining the plasma P in the processing chamber 100, and high etching characteristics are obtained.

In this embodiment, similarly to the embodiment described with reference to FIG. 1, the temperature of the inner surface of the side wall 102 is controlled by the jacket 103 in the range of 0 ° C. to about 100 ° C., preferably 20 ° C. to about 80 ° C., and ± 10 ° C. Since the control is performed with an accuracy within ° C., a deposited film having plasma resistance is formed and acts as a protective film on the inner wall of the reactor, so that it is possible to reduce particles and reduce the frequency of replacing parts on the side wall. Also, the surface reaction and the processing characteristics of the sample can be stabilized by the leak bias applying structure and the gas cooling of the sample stage ring 132, and the deposition of the reaction product is prevented to reduce the generation of particles. Further, the shield ring 216 has a thin shape as in the embodiment of FIG.
6 is configured so as to cover a part thereof and reduce thermal contact with other parts. For this reason, the plate 11
When power is applied to 5, the shield ring 216 is heated by the ions due to the self-bias, the deposition of the reaction product is suppressed, and the generation of foreign substances can be reduced.

FIG. 8 shows an example in which the present invention is applied to an inductively coupled plasma processing apparatus. The processing chamber 100 as a vacuum vessel includes a side wall 102, a lower electrode 130 on which a sample W such as a wafer is placed, and a top plate 230, and is evacuated and evacuated by an evacuation system 106. An induction discharge coil 231 is disposed above the top plate 230, and the high frequency power supply 2
32 supplies high frequency power. The processing gas is supplied from the gas supply means 117 and is converted into plasma by the induction discharge by the induction discharge coil 231 to generate plasma P, thereby processing the sample W. In an inductively coupled plasma processing apparatus,
By using silicon for the top plate to stabilize the process, or by suppressing the interaction between the plasma and the wall by means such as a Faraday shield or a magnetic field, high etching characteristics are stabilized even when the side wall is lower than the wafer. Obtained.

In this embodiment, as in the embodiment described with reference to FIG. 1, the temperature of the inner surface of the side wall 102 is controlled by the jacket 103 so as to fall within a range of 0 ° C. to about 100 ° C., preferably 20 ° C. to about 80 ° C. It is controlled with accuracy within ° C. For this reason, a deposited film having plasma resistance is formed and acts as a protective film on the inner wall of the reactor, so that particles can be reduced and the frequency of replacement of the side wall components can be reduced. Also, the sample stage ring 13
As for No. 2, due to the leakage bias applying structure and gas cooling,
The surface reaction and the processing characteristics of the sample can be stabilized, and the deposition of reaction products can be prevented to reduce the generation of particles.

In each of the above embodiments, the processing target is a semiconductor wafer and the etching processing is performed on the semiconductor wafer. However, the present invention is not limited to this. For example, the processing target is a liquid crystal substrate. Also, the processing itself is not limited to etching, and can be applied to, for example, sputtering or CVD processing.

[0078]

According to the present invention, by controlling the temperature inside the reactor and the state of the wall surface, the reproducibility of the process can be improved without causing a change over time in the etching characteristics.
A plasma processing apparatus which can maintain reliability at low cost for a long period of time can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a plasma etching apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a method of controlling the temperature of a sample stage ring, which is one embodiment of the present invention.

FIG. 3 is a diagram showing a method for controlling the temperature of a ring, which is one embodiment of the present invention.

FIG. 4 is a diagram showing a method for controlling the temperature of a ring using an infrared lamp according to an embodiment of the present invention.

FIG. 5 is a diagram showing a method of controlling the temperature of a ring by a refrigerant, which is one embodiment of the present invention.

FIG. 6 is a schematic sectional view of a magnetic field RIE plasma etching apparatus according to an embodiment of the present invention.

FIG. 7 is a schematic sectional view of a parallel plate type plasma etching apparatus according to an embodiment of the present invention.

FIG. 8 is a schematic sectional view of an inductively coupled plasma etching apparatus according to an embodiment of the present invention.

[Explanation of symbols]

100: processing chamber, 101: magnetic field forming means, 102: processing chamber side wall, 103: jacket, 104, 117, 155
... gas supply means, 105 ... vacuum chamber, 106 ... vacuum evacuation system, 110 ... antenna, 111 ... disk-shaped conductor, 112
... dielectric, 113 ... dielectric ring, 115 ... plate,
116: temperature control means, 121: antenna power supply, 122
... Antenna high frequency power supply, 130 ... Lower electrode, 131 ... Electrostatic adsorption device, 132 ... Sample stage ring, 133,143 ...
Insulator, 141: bias power supply, 147: refrigerant flow path, 1
51: infrared absorber, 152: infrared radiation means, 153: infrared transmission window.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C23C 14/34 C23C 14/34 M 14/54 14/54 B H01L 21/205 H01L 21/205 ( 72) Inventor: Mitsuru Suehiro 794, Higashi-Toyoi, Kazamatsu, Kamamatsu, Yamaguchi Prefecture Inside the Kasado Plant, Hitachi, Ltd. (72) Inventor Saburo Kanai 794, Higashi-Toyoi, Kazamatsu City, Yamaguchi Prefecture Inside the Kasado Plant of Hitachi, Ltd.

Claims (4)

[Claims] 1. A vacuum vessel evacuated by vacuum evacuation means, a gas introduction means for introducing a processing gas into the vacuum vessel, and an electrostatic chuck for mounting a wafer inside the vacuum vessel. An apparatus, a lower electrode, a bias power supply connected to the lower electrode for supplying bias power, and a unit for radiating a high frequency wave into the vacuum vessel, and the processing gas is turned into plasma to process a sample to be processed. In the plasma processing apparatus, an antenna configured by a disc-shaped conductor connected to a high-frequency bias power supply and a plate in contact with the disc-shaped conductor in the vacuum vessel, facing the lower electrode. The vacuum vessel is provided with a processing chamber having a side wall, and the side wall does not have a temperature control for forming a coating film by a composition of a processing gas on an inner wall surface thereof during an etching process. The plasma processing apparatus according to claim Rukoto. 2. A vacuum vessel evacuated by vacuum evacuation means, a gas introduction means for introducing a processing gas into the vacuum vessel, and an electrostatic chuck for mounting a wafer inside the vacuum vessel. An apparatus, a lower electrode, a bias power supply connected to the lower electrode for supplying bias power, and a unit for radiating a high frequency wave into the vacuum vessel, and the processing gas is turned into plasma to process a sample to be processed. In the plasma processing apparatus for performing the above, in the vacuum container, an antenna constituted by a disc-shaped conductor connected to a high-frequency bias power supply and a plate in contact with the disc-shaped conductor, facing the lower electrode. The distance between the plate and the wafer is 30 mm or more and 150 m
m or less, wherein the vacuum container forms a processing chamber having a side wall, and the side wall is subjected to temperature control for forming a coating film on the inner wall surface by a composition of a processing gas at the time of etching. Plasma processing apparatus. 3. The plasma processing apparatus according to claim 1, wherein the temperature of the side wall is controlled by a heat medium circulating supply from a heat medium supply unit. 4. The plate according to claim 1, wherein a ring is provided on an outer peripheral side of the plate, and the ring forms a coating film based on a composition of a processing gas when etching is performed on a surface which is in contact with plasma. Characteristic plasma processing apparatus.