JP5522220B2 - Electrostatic chuck device - Google Patents

Description

  The present invention relates to an electrostatic chuck device, and more particularly to an electrostatic chuck device that is suitably used in an etching apparatus, a CVD apparatus, and the like using plasma, and has excellent durability against rapid temperature rise and fall. is there.

  In recent years, in the semiconductor industry that supports IT technology, which is rapidly progressing, higher integration and higher performance of elements are required. For this reason, further improvement in microfabrication technology is also required in the semiconductor manufacturing process. . In this semiconductor manufacturing process, the etching technique is an important one of the microfabrication techniques. In recent years, the plasma etching technique capable of high-efficiency and large-area microfabrication has become the mainstream among the etching techniques. .

  This plasma etching technique is a kind of dry etching technique. A mask pattern is formed with a resist on a solid material to be processed, and this solid material is supported in a vacuum. By introducing and applying a high-frequency electric field to this reactive gas, the accelerated electrons collide with gas molecules to form a plasma state, and radicals (free radicals) and ions generated from this plasma react with the solid material. This is a technique for forming a fine pattern in a solid material by removing it as a reaction product.

  On the other hand, there is a plasma CVD method as one of thin film growth techniques in which source gases are combined by the action of plasma and the obtained compound is deposited on a substrate. This method is a film forming method in which plasma discharge is performed by applying a high-frequency electric field to a gas containing source molecules, source molecules are decomposed by electrons accelerated by the plasma discharge, and the obtained compound is deposited. . Reactions that did not occur only at thermal excitation at low temperatures are also possible in the plasma because the gases in the system collide with each other and are activated to become radicals.

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus using plasma such as a plasma etching apparatus and a plasma CVD apparatus, an electrostatic chuck apparatus is used as an apparatus for simply mounting and fixing a wafer on a sample stage and maintaining the wafer at a desired temperature. Is used.
As such an electrostatic chuck device, for example, the upper surface of a ceramic substrate is used as a mounting surface on which a plate-like sample such as a wafer is placed, and a plate electrode for electrostatic adsorption made of a refractory metal is embedded therein. A substrate mounting table in which an electrostatic chuck portion and a cooling member formed of a composite material of ceramics and aluminum and having a coolant channel for circulating cooling water formed therein are joined and integrated by a joining layer made of an aluminum alloy. It has been proposed (Patent Document 1).

A wafer holding device shown in FIG. 7 has also been proposed (Patent Document 2).
In this wafer holding device 1, the upper surface of a disk-shaped ceramic body 3 is used as a holding surface 4 for a wafer W, and an electrostatic chucking electrode 5 and a heater electrode 6 are embedded in the ceramic body 3. The holding substrate 2 and the base substrate 11 in which the pores of the porous ceramic body 12 are filled with the metal 14 are joined via a brazing material 9 whose main component is aluminum, and an electrode 5, In this configuration, a recess communicating with 6 is formed, and power supply terminals 7 and 8 for energizing the electrodes 5 and 6 are joined to the recess.

JP-A-2005-101108 JP-A-11-163109

By the way, in various conventional electrostatic chuck apparatuses, a new problem has arisen as the diameter of a plate-like sample such as a wafer increases (increase in area), and in particular, the increase in 300 mm wafers in recent years. Along with this, problems are becoming more prominent.
In a conventional electrostatic chuck apparatus, a plate-like sample such as a wafer is electrostatically adsorbed, and the plate-like sample is maintained in a desired temperature pattern using a heater or a refrigerant, and various plasma treatments are performed on the plate-like sample. Although it can be applied, if the temperature is raised and lowered rapidly in order to increase the productivity (improvement of throughput) of plasma processing on this plate-like sample, the electrostatic chuck portion or wafer holding substrate on which the plate-like sample is placed There was a problem that cracks occurred in the substrate and the durability as an electrostatic chuck device was not sufficient.

In plasma etching or the like, it is necessary to repeat heating, temperature holding, and cooling of the plate-shaped sample every time plasma etching is performed on the plate-shaped sample. However, in the conventional electrostatic chuck apparatus, the heat capacity of the electrostatic chuck portion and the wafer holding base is large, and the heat exchange efficiency between the cooling member for temperature adjustment or the base base and the plate-like sample to be placed is The thermal response is not sufficient, and therefore it is difficult to follow a rapid temperature change, resulting in variations in the in-plane temperature of the plate-like sample and fluctuations over time. There is a problem that the in-plane temperature of the sample cannot be maintained in a desired temperature pattern.
In particular, in a plate sample with a large diameter (large area), in order to further improve the yield of the obtained product, it is required to control the in-plane temperature of the plate sample with high accuracy. There is an urgent need to further increase the in-plane temperature controllability of the sample.

In addition, since it is difficult to follow a rapid temperature change, it is very difficult to further shorten the time required for heating and cooling. Therefore, it is difficult to further shorten the process time, and it is difficult to improve productivity. there were.
Further, in the conventional electrostatic chuck device, the heater pattern, particularly the heater pattern built in the electrostatic chuck portion, is directly reflected on the plate-like sample, and the in-plane temperature of the plate-like sample is maintained in a desired temperature pattern. There was a problem that it was not possible.

  The present invention has been made to solve the above-described problems, and there is no possibility that cracks or the like may occur in the electrostatic chuck portion even when the placed plate-like sample is rapidly raised and lowered. Excellent durability, low heat capacity, excellent heat exchange efficiency and thermal response with the plate-shaped sample placed, and easy to maintain the in-plane temperature of the plate-shaped sample in the desired temperature pattern Furthermore, an object of the present invention is to provide an electrostatic chuck capable of maintaining the in-plane temperature of the plate-like sample in a desired temperature pattern without reflecting the heater pattern on the plate-like sample.

As a result of intensive studies to solve the above problems, the inventors of the present invention, an electrostatic chuck portion,
A temperature-adjusting base, a thin heater element made of a nonmagnetic metal having a thickness of 200 μm or less, disposed between the electrostatic chuck and the temperature-adjusting base, and the electrostatic chuck and the temperature-adjusting It is found that the above-mentioned problem can be easily solved if it is provided with an organic adhesive layer having a two-layer structure in which a heater element is sandwiched and integrated with a base portion, The present invention has been completed.

That is, the electrostatic chuck device of the present invention has an electrostatic chuck portion in which one principal surface is a mounting surface on which a plate-like sample is placed and an electrostatic adsorption internal electrode is provided inside, and a heat medium inside And a thin plate heater made of a nonmagnetic metal having a thickness of 200 μm or less, disposed between the electrostatic chuck portion and the temperature adjustment base portion. An organic adhesive layer formed by sandwiching the heater element and adhering and integrating the element and the electrostatic chuck portion and the temperature adjusting base portion with a certain distance therebetween, The adhesive layer includes a first organic adhesive layer that is bonded and integrated with the temperature adjusting base portion, and a second organic adhesive layer that bonds and integrates the first organic adhesive layer and the electrostatic chuck portion. a two-layer structure of the organic adhesive layer, By these first organic adhesive layer and the second organic adhesive layer is characterized by being obtained by sandwiching the heater element.

In this electrostatic chuck device, a thin plate heater made of a nonmagnetic metal having a thickness of 200 μm or less and disposed between the electrostatic chuck portion, the temperature adjustment base portion, and the electrostatic chuck portion and the temperature adjustment base portion. comprising the element, an organic adhesive layer formed by sandwiching the heater element while bonding and integrating the these electrostatic chuck portion and the temperature-controlling base portion while maintaining the constant spacing, the organic adhesive A first organic adhesive layer for bonding and integrating the layer with the temperature adjusting base portion, and a second organic adhesive for bonding and integrating the first organic adhesive layer and the electrostatic chuck portion. When the plate-like sample to be placed is rapidly raised or lowered by sandwiching the heater element between the first organic adhesive layer and the second organic adhesive layer. In the heater element Organic adhesive layer of 2-layer structure sandwiching the functions as a buffer layer to mitigate the rapid expansion and contraction with respect to the electrostatic chuck portion, to prevent the cracks occur in the electrostatic chuck portion. Thereby, the durability of the electrostatic chuck portion is improved.

  In addition, by using a thin plate-like heater element made of a nonmagnetic metal having a thickness of 200 μm or less, the pattern of the heater element is hardly reflected on the plate-like sample, and the in-plane temperature of the plate-like sample is a desired temperature pattern. Easy to maintain.

  In the electrostatic chuck device of the present invention, the organic adhesive layer contains a filler made of surface-coated aluminum nitride particles, and the heat transfer coefficient of the second organic adhesive layer is set to the first adhesive layer. It is characterized by being larger than the heat transfer coefficient of the organic adhesive layer.

  In this electrostatic chuck device, the heat transfer coefficient of the second organic adhesive layer is made larger than the heat transfer coefficient of the first organic adhesive layer. The heat generated from the heater element sandwiched by the agent layer moves from the second organic adhesive layer substantially vertically toward the electrostatic chuck portion, and the plate placed on the electrostatic chuck portion The in-plane temperature of the shaped sample can be maintained in a desired temperature pattern.

The organic adhesive layer is made of a silicone resin.
The thickness of the first organic adhesive layer is 100 μm or more and 350 μm or less, and the thickness of the second organic adhesive layer is 10 μm or more and 100 μm or less.
The first organic adhesive layer has a built-in spacer.

According to the electrostatic chuck device of the present invention, the electrostatic chuck portion, the temperature adjusting base portion, and the non-magnetic metal having a thickness of 200 μm or less disposed between the electrostatic chuck portion and the temperature adjusting base portion. comprising a thin plate heater element, and an organic adhesive layer formed by sandwiching the heater element while bonding and integrating the these electrostatic chuck portion and the temperature-controlling base portion while maintaining a predetermined distance, the organic A first organic adhesive layer for bonding and integrating the adhesive layer with the temperature adjusting base portion, and a second organic for bonding and integrating the first organic adhesive layer and the electrostatic chuck portion. Since the heater element is sandwiched between the first organic adhesive layer and the second organic adhesive layer , even when the temperature of the plate-like sample is rapidly raised and lowered , Cracks in the electrostatic chuck It is possible to prevent the occurrence, it is possible to improve the durability.
Therefore, the productivity of plasma processing for the plate-like sample can be increased, and the throughput can be improved.

  In addition, since a thin plate heater element made of a nonmagnetic metal having a thickness of 200 μm or less is used, the pattern of the heater element can be made difficult to be reflected on the plate sample, and the in-plane temperature of the plate sample can be set to a desired value. The temperature pattern can be maintained.

In addition , the thickness of the electrostatic chuck itself can be reduced, so that the heat capacity can be reduced, the efficiency of heat exchange with the plate-like sample to be placed can be improved, and the thermal response is improved. Can be made.
Further, by reducing the thickness of the electrostatic chuck portion, it is possible to easily follow a rapid temperature change, and the time required for heating and cooling can be further shortened. Therefore, the process time can be further shortened, and the productivity can be further improved.

  Further, since the heat transfer coefficient of the second organic adhesive layer is made larger than the heat transfer coefficient of the first organic adhesive layer, the second organic adhesive layer is sandwiched between the first and second organic adhesive layers. The in-plane temperature of the plate-like sample can be maintained in a desired temperature pattern by moving the heat generated from the heater element from the second organic adhesive layer substantially vertically toward the electrostatic chuck portion. it can.

It is sectional drawing which shows the electrostatic chuck apparatus of one Embodiment of this invention. It is a top view which shows an example of the heater pattern of the heater element of the electrostatic chuck apparatus of one Embodiment of this invention. It is a figure which shows the in-plane temperature distribution of the silicon wafer at the time of cooling of the electrostatic chuck apparatus of an Example. It is a figure which shows the in-plane temperature distribution of the silicon wafer when hold | maintaining at 50 degreeC of the electrostatic chuck apparatus of an Example. It is a figure which shows the in-plane temperature distribution of the silicon wafer at the time of temperature rising of the electrostatic chuck apparatus of an Example. It is sectional drawing which shows the conventional wafer holding device.

The form for implementing the electrostatic chuck apparatus of this invention is demonstrated based on drawing.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

  FIG. 1 is a cross-sectional view showing an electrostatic chuck device according to an embodiment of the present invention. The electrostatic chuck device 21 includes a disk-shaped electrostatic chuck portion 22 and a lower portion of the electrostatic chuck portion 22. A thick disc-shaped temperature adjusting base portion 23, an organic adhesive layer 24 for bonding and integrating the electrostatic chuck portion 22 and the temperature adjusting base portion 23, and the organic adhesive layer The heater element (heating member) 25 built in 24 is mainly configured.

  The electrostatic chuck portion 22 is made of a mounting plate 31 made of ceramic whose upper surface is a mounting surface 31a on which a plate-like sample W such as a silicon wafer is placed, and ceramics that supports the mounting plate 31 from below. Electrostatic adsorption provided through the support plate 32, the internal electrode 33 for electrostatic adsorption and the annular insulating material 34 provided between the mounting plate 31 and the support plate 32, and the support plate 32 The power supply terminal 35 is configured to apply a DC voltage to the internal electrode 33.

The mounting plate 31 and the support plate 32 are disk-like ones having the same overlapping surface shape and are made of an insulating ceramic sintered body.
The ceramic is not particularly limited as long as it has a volume resistivity of about 10 ¹³ to 10 ¹⁵ Ω · cm, mechanical strength, and durability against a corrosive gas and its plasma. For example, an alumina (Al ₂ O ₃ ) sintered body, an aluminum nitride (AlN) sintered body, an alumina (Al ₂ O ₃ ) -silicon carbide (SiC) composite sintered body, or the like is preferably used.

  The total thickness of the mounting plate 31 and the support plate 32, that is, the thickness of the electrostatic chuck portion 22, is preferably 0.7 mm or more and 3.0 mm or less. The reason is that if the thickness of the electrostatic chuck portion 22 is less than 0.7 mm, the mechanical strength of the electrostatic chuck portion 22 cannot be secured, while the thickness of the electrostatic chuck portion 22 is 3.0 mm. If it exceeds the upper limit, the heat capacity of the electrostatic chuck portion 22 is increased, the heat exchange efficiency with the plate-like sample W to be placed is lowered, the thermal responsiveness is deteriorated, and the heat transfer is caused by the organic adhesive layer. This is because it is more likely to occur in the horizontal direction (left and right direction in FIG. 1) than 24 vertical directions, and it becomes difficult to maintain the in-plane temperature of the plate-like sample W in a desired temperature pattern.

  The thickness of the mounting plate 31 is preferably 0.2 mm or more and 1.5 mm or less, and particularly preferably 0.5 mm or more and 1.0 mm or less. The reason is that if the thickness of the mounting plate 31 is less than 0.2 mm, a sufficient withstand voltage cannot be ensured. The thermal conductivity between the plate-like sample W placed on the placement surface 31a of the placement plate 31 and the temperature adjusting base portion 23 is lowered, and the temperature of the plate-like sample W being processed is changed to a desired temperature pattern. This is because it is difficult to keep.

  Further, the thickness of the support plate 32 is preferably 0.5 mm or more and 2.8 mm or less, and particularly preferably 1.0 mm or more and 2.0 mm or less. The reason is that if the thickness of the support plate 32 is less than 0.5 mm, sufficient withstand voltage cannot be ensured, while if it exceeds 2.8 mm, the support plate 32 is placed on the placement surface 31 a of the placement plate 31. This is because the thermal conductivity between the placed plate-like sample W and the temperature adjusting base portion 23 is lowered, and it becomes difficult to keep the temperature of the plate-like sample W being processed in a desired temperature pattern.

The internal electrode 33 for electrostatic adsorption is used as an electrode for electrostatic chuck for generating electric charges and fixing the plate-like sample W to the mounting surface 31a by electrostatic adsorption force. And the size is adjusted as appropriate.
Examples of the material constituting the internal electrode 33 for electrostatic adsorption include refractory metals such as titanium, tungsten, molybdenum, and platinum, carbon materials such as graphite and carbon, and conductive ceramics such as silicon carbide, titanium nitride, and titanium carbide. Are preferably used. It is desirable that the thermal expansion coefficients of these materials approximate the thermal expansion coefficients of the mounting plate 31 and the support plate 32 as much as possible.

The thickness of the electrostatic adsorption internal electrode 33 is not particularly limited, but is preferably 0.1 μm or more and 100 μm or less when the temperature adjusting base 23 is used as a plasma generating electrode. Preferably they are 5 micrometers or more and 20 micrometers or less. The reason is that if the thickness is less than 0.1 μm, sufficient conductivity cannot be ensured. On the other hand, if the thickness exceeds 100 μm, the mounting plate 31 and the support plate 32 and the electrostatic chucking internal electrode 33 are not secured. This is because cracks are likely to occur at the bonding interface between the mounting plate 31 and the support plate 32 due to the difference in thermal expansion coefficient between the mounting plate 31 and the supporting plate 32.
The electrostatic adsorption internal electrode 33 having such a thickness can be easily formed by a film forming method such as a sputtering method or a vapor deposition method, or a coating method such as a screen printing method.

  The annular insulating material 34 surrounds the electrostatic adsorption internal electrode 33 and protects the electrostatic adsorption internal electrode 33 from corrosive gas and plasma thereof. The same composition or the main component is made of the same insulating material, and the mounting plate 31 and the support plate 32 are joined and integrated by the insulating material 34 via the internal electrode 33 for electrostatic attraction.

The power feeding terminal 35 is a rod-shaped member provided to apply a DC voltage to the electrostatic adsorption internal electrode 33. The number and shape of the power supply terminal 35 is the form of the electrostatic adsorption internal electrode 33, that is, this It is determined depending on whether the electrostatic attraction internal electrode 33 is a monopolar type or a bipolar type.
The material of the power feeding terminal 35 is not particularly limited as long as it is a conductive material having excellent heat resistance. However, the thermal expansion coefficient is equal to the thermal expansion coefficient of the electrostatic adsorption internal electrode 33 and the support plate 32. Approximate ones are preferable. For example, metal materials such as Kovar alloy and niobium (Nb), and various conductive ceramics are preferably used.
The power feeding terminal 35 penetrates the organic adhesive layer 24 and the temperature adjusting base 23 and is connected to an external power source (not shown).

  The temperature adjusting base portion 23 is for adjusting the electrostatic chuck portion 22 to a desired temperature pattern, and is a thick disk-shaped member made of metal and / or ceramics. The temperature adjusting base portion 23 also serves as an internal electrode for plasma generation, and a flow path 41 for circulating a heat medium such as water, He gas, N 2 gas, etc. is formed in the inside thereof, and the casing is externally provided. It is connected to a high frequency power supply (not shown).

The material constituting the temperature adjusting base portion 23 is not particularly limited as long as it is a metal excellent in thermal conductivity, conductivity, and workability, or a composite material containing these metals. For example, aluminum (Al) , Copper (Cu), stainless steel (SUS) and the like are preferably used. It is preferable that at least the surface of the temperature adjusting base portion 23 exposed to the plasma is anodized or an insulating film such as alumina is formed.
The temperature adjusting base portion 23 has an alumite treatment or an insulating film formed on at least a surface exposed to plasma, thereby improving plasma resistance and preventing abnormal discharge. Plasma stability is improved. Moreover, since it becomes difficult for a surface to be damaged, generation | occurrence | production of a damage | wound can be prevented.

  The organic adhesive layer 24 has a thermal stress relieving action, and includes a first organic adhesive layer 24a that is bonded and integrated with the temperature adjusting base 23, and the organic adhesive layer 24a and the electrostatic adhesive layer 24a. The heat transfer coefficient of the organic adhesive layer 24a is the two-layer structure of the second organic adhesive layer 24b that bonds and integrates the chuck portion 22 with the organic adhesive layer 24a. It is said that it is bigger than.

The thickness of the organic adhesive layer 24 is preferably 100 μm or more and 500 μm or less in total thickness of the organic adhesive layer 24a and the organic adhesive layer 24b.
When the thickness of the organic adhesive layer 24 is less than 100 μm, the thermal conductivity between the electrostatic chuck portion 22 and the temperature adjusting base portion 23 becomes good, but the thermal stress relaxation becomes insufficient, cracking and On the other hand, if the thickness of the organic adhesive layer 24 exceeds 500 μm, sufficient thermal conductivity between the electrostatic chuck portion 22 and the temperature adjusting base portion 23 can be secured. Because it becomes impossible.

  The thickness of the organic adhesive layer 24a is preferably 100 μm or more and 350 μm or less. When the thickness of the organic adhesive layer 24a is less than 100 μm, the difference from the thickness of the organic adhesive layer 24b is substantially eliminated, and the heat transfer rate of the organic adhesive layer 24b is reduced. On the other hand, when the thickness of the organic adhesive layer 24a exceeds 350 μm, the temperature controllability of the temperature adjusting base portion 23 is lowered, which is not preferable.

  The thickness of the organic adhesive layer 24b is preferably 10 μm or more and 100 μm or less. The reason is that when the thickness of the organic adhesive layer 24b is less than 10 μm, the shape of the built-in heater element 25 is reflected in the plate sample W, temperature unevenness is likely to occur in the plate sample W, and stress relaxation is performed. This is because it becomes insufficient, and as a result, there is a possibility that the electrostatic chuck portion 22 is broken due to thermal stress. On the other hand, when the thickness of the organic adhesive layer 24b exceeds 100 μm, the difference from the thickness of the organic adhesive layer 24a is substantially eliminated, and the heat transfer coefficient of the organic adhesive layer 24b is reduced to the organic adhesive layer. This is because it becomes difficult to make it larger than that of 24a.

  The organic adhesive layer 24 is formed of, for example, a cured body of a silicone resin composition. This silicone resin composition is a resin excellent in heat resistance and elasticity, and is a silicon compound having a siloxane bond (Si—O—Si). This silicone resin composition can be represented, for example, by the chemical formula of the following formula (1) or formula (2).

Here, R is, H or an alkyl group _{(C n H 2n + 1 -} : n is an integer) is.

Here, R is, H or an alkyl group _{(C n H 2n + 1 -} : n is an integer) is.

As such a silicone resin, it is particularly preferable to use a silicone resin having a thermosetting temperature of 70 ° C to 140 ° C.
Here, when the thermosetting temperature is lower than 70 ° C., when the support plate 32 of the electrostatic chuck portion 22 and the temperature adjusting base portion 23 are joined, curing starts in the middle of the joining process, and the joining work is performed. On the other hand, if the thermosetting temperature exceeds 140 ° C., the thermal expansion difference between the support plate 32 and the temperature adjusting base portion 23 cannot be absorbed, and the mounting plate 31 is not preferred. Not only is the flatness of the mounting surface 31a lowered, but also the bonding force between the support plate 32 and the temperature adjusting base portion 23 is lowered, and there is a risk that peeling will occur between them.

  It is preferable to use a silicone resin having a Young's modulus after curing of 8 MPa or less. Here, if the Young's modulus after curing exceeds 8 MPa, the thermal expansion difference between the support plate 32 and the temperature adjusting base portion 23 when the organic adhesive layer 24 is subjected to a temperature cycle of increasing and decreasing temperatures. Cannot be absorbed, and the durability of the organic adhesive layer 24 is lowered, which is not preferable.

The organic adhesive layer 24 is a surface-coated nitride in which a coating layer made of silicon oxide (SiO ₂ ) is formed on the surface of a filler having an average particle diameter of 1 μm or more and 10 μm or less, for example, aluminum nitride (AlN) particles. It is preferable that aluminum (AlN) particles are contained.
The surface-coated aluminum nitride (AlN) particles are mixed in order to improve the thermal conductivity of the silicone resin. By adjusting the mixing rate, the heat transfer rates of the organic adhesive layers 24a and 14b are adjusted. Can be controlled.

That is, by increasing the mixing rate of the surface-coated aluminum nitride (AlN) particles, the heat transfer rate of the organic adhesive constituting the organic adhesive layer 24b on the electrostatic chuck portion 22 side can be increased.
In addition, since a coating layer made of silicon oxide (SiO ₂ ) is formed on the surface of aluminum nitride (AlN) particles, it has superior water resistance compared to simple aluminum nitride (AlN) particles that are not surface-coated. It has sex. Therefore, the durability of the organic adhesive layer 24 containing the silicone resin composition as a main component can be ensured, and as a result, the durability of the electrostatic chuck device 21 can be dramatically improved.

In this surface-coated aluminum nitride (AlN) particle, the surface of the aluminum nitride (AlN) particle is coated with a coating layer made of silicon oxide (SiO ₂ ) having excellent water resistance. There is no possibility of being hydrolyzed by water in the atmosphere, and there is no possibility that the heat transfer rate of aluminum nitride (AlN) is reduced, and the durability of the organic adhesive layer 24 is improved.
The surface-coated aluminum nitride (AlN) particles are unlikely to become a contamination source for the plate-like sample W such as a semiconductor wafer.

  Since the surface-coated aluminum nitride (AlN) particles can obtain a strong bonding state with Si in the coating layer and the silicone-based resin composition, the stretchability of the organic adhesive layer 24 can be improved. Is possible. Thereby, the thermal stress resulting from the difference between the thermal expansion coefficient of the support plate 32 of the electrostatic chuck part 22 and the thermal expansion coefficient of the temperature adjustment base part 23 can be relieved. The base portion 23 for use can be bonded firmly with high accuracy. Further, the durability against the heat cycle load during use becomes sufficient, and the durability of the electrostatic chuck device 21 is improved.

The average particle diameter of the surface-coated aluminum nitride (AlN) particles is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 5 μm or less.
Here, when the average particle size of the surface-coated aluminum nitride (AlN) particles is less than 1 μm, the contact between the particles becomes insufficient, and as a result, the heat transfer rate may be lowered, and the particle size is small. If it is too much, workability such as handling is reduced, which is not preferable. On the other hand, if the average particle size exceeds 10 μm, the proportion of the silicone resin composition in the organic adhesive layer locally decreases, leading to a decrease in the extensibility and adhesive strength of the organic adhesive layer 24. There is a fear.

The thickness of the coating layer of the surface-coated aluminum nitride (AlN) particles is preferably 0.005 μm or more and 0.05 μm or less, more preferably 0.005 μm or more and 0.03 μm or less.
If the thickness of the coating layer is less than 0.005 μm, the water resistance (moisture resistance) of aluminum nitride (AlN) cannot be sufficiently exhibited, and therefore, simple aluminum nitride (AlN) that is not subjected to surface coating. This is because only the same properties as the particles can be obtained, and it is chemically unstable. On the other hand, if the thickness of the coating layer exceeds 0.05 μm, the heat transfer coefficient as particles decreases, and consequently the mounting plate The heat transfer coefficient between the plate-like sample W placed on the placement surface 31a of 31 and the temperature adjusting base 23 is lowered, and the temperature of the plate-like sample W being processed is kept in a desired temperature pattern. This is because it becomes difficult.

  The heater element 25 is disposed at the bonding interface between the organic adhesive layer 24a and the organic adhesive layer 24b. For example, as shown in FIG. The inner heater 25a formed on the outer heater 25a and the outer heater 25b formed on the outer periphery of the inner heater 25a are connected to power supply terminals at both ends of the inner heater 25a and the outer heater 25b. 26 is connected to a power feeding terminal 51 (not shown).

Each of the inner heater 25a and the outer heater 25b has a pattern in which a narrow band-shaped metal material meanders is repeatedly arranged around the axis, and adjacent patterns are connected to each other. One continuous belt-like heater pattern is formed.
In the heater element 25, the in-plane temperature distribution of the plate-like sample W fixed to the mounting surface 31a of the mounting plate 31 by electrostatic adsorption is controlled by independently controlling the inner heater 25a and the outer heater 25b. Is controlled with high accuracy.

  The heater pattern of the heater element 25 may be constituted by two or more heater patterns independent from each other as described above, or may be constituted by one heater pattern. When the heater element 25 is composed of two or more heater patterns independent of each other like the outer heater 25b, the temperature of the plate-like sample W being processed can be freely controlled by individually controlling these mutually independent heater patterns. It is preferable because it can be controlled.

The heater element 25 is made of a non-magnetic metal thin plate having a constant thickness of 200 μm or less, preferably 100 μm or less, such as a titanium (Ti) thin plate, a tungsten (W) thin plate, a molybdenum (Mo) thin plate or the like. It is formed by etching the pattern.
Here, the reason why the thickness of the heater element 25 is set to 200 μm or less is that when the thickness exceeds 200 μm, the pattern shape of the heater element 25 is reflected as the temperature distribution of the plate sample W, and the in-plane temperature of the plate sample W is changed. This is because it becomes difficult to maintain a desired temperature pattern.

Further, when the heater element 25 is formed of a nonmagnetic metal, the heater element does not self-heat due to the high frequency even when the electrostatic chuck device 1 is used in a high frequency atmosphere. This is preferable because it is easy to maintain a constant temperature pattern.
Further, when the heater element 5 is formed of a non-magnetic metal thin plate having a constant thickness, the thickness of the heater element 5 is constant over the entire heating surface, and the amount of heat generation is also constant over the entire heating surface, so that the temperature distribution can be made uniform. it can.

In the heater element 25, the inner heater 25 a and the outer heater 25 b are controlled independently, so that the heater pattern of the heater element 25 can be made difficult to be reflected in the plate-like sample W, and the mounting plate 31 is mounted. The in-plane temperature distribution of the plate-like sample W fixed to the placement surface 31a by electrostatic adsorption can be accurately controlled to a desired temperature pattern .

The power feeding terminal 51 is for applying electric power to the heater element 25. The number, shape, etc. of the power supply terminal 51 are configured by the heater of the heater element 25, that is, by one heater, or the above-mentioned It is determined depending on whether the heater 25a and the outer heater 25b are constituted by two or more independent heaters.
The material of the power supply terminal 51 is not particularly limited as long as it is a conductive material having excellent heat resistance, but preferably has a thermal expansion coefficient that approximates the thermal expansion coefficient of the heater element 25. Metal materials such as Kovar alloy and niobium (Nb), and various conductive ceramics are preferably used.

  As described above, the heater element 25 is sandwiched between the organic adhesive layers 24a and 24b having a thermal stress relieving action so that the heater element 25 is built in the organic adhesive layer 24. Even if the plate-like sample W is rapidly raised or lowered in order to increase the productivity of plasma processing on the sample W, there is no possibility of thermal stress breakdown (crack) occurring in the electrostatic chuck portion 22. That is, the Young's modulus of the organic adhesive is smaller than the Young's modulus of ceramics, and thermal stress is reduced by disposing the heater element 25 in the organic adhesive layer 24 rather than disposing the heater element 25 in the ceramic. Therefore, even if the plate sample W is rapidly raised and lowered in order to increase the productivity of plasma processing on the plate sample W, no cracks are generated in the electrostatic chuck portion 22. The electrostatic chuck device 21 is excellent in durability.

Further, since the heater element 25 is disposed in the organic adhesive layer 24, the thickness of the electrostatic chuck portion 22, that is, the total thickness of the mounting plate 31 and the support plate 32 is, for example, 0.7 mm or more and 3 The heat capacity is small, the heat exchange efficiency with the plate sample W to be placed is good, and the thermal response is excellent.
Moreover, the heat transfer is likely to occur in the vertical direction (vertical direction in FIG. 1) of the organic adhesive layer 24, and the electrostatic temperature capable of maintaining the in-plane temperature of the plate-like sample W in a desired temperature pattern. The chuck device 21 is obtained.

  Furthermore, the organic adhesive layer 24 has a two-layer structure of an organic adhesive layer 24a and an organic adhesive layer 24b, and the heat transfer coefficient of the organic adhesive layer 24b on the electrostatic chuck portion 22 side is increased. Since the heater element 25 is disposed at the interface between the organic adhesive layers 24a and 24b, the heat generated by energizing the heater element 25 is transferred to the electrostatic chuck portion 22 side, that is, the mounting surface of the electrostatic chuck portion 22. It becomes easy to efficiently move to the plate-like sample W placed on 31a and keep the temperature of the plate-like sample W being processed in a desired temperature pattern.

  Next, the manufacturing method of the electrostatic chuck device 21 will be described with emphasis on the bonding method between the electrostatic chuck portion 22 and the temperature adjusting base portion 23.

First, the electrostatic chuck portion 22 and the temperature adjusting base portion 23 are manufactured by a known method.
On the other hand, a silicone resin and a filler for improving thermal conductivity are mixed at a predetermined ratio, and this mixture is subjected to stirring and defoaming treatment to obtain a mixture of a silicone resin and a filler for improving thermal conductivity (hereinafter referred to as “silicone”). (Referred to as "system resin composition").
You may adjust the viscosity of this silicone type resin composition with organic solvents, such as toluene and xylene, so that it may become a predetermined viscosity, for example, 50-300 Pa.s so that it may be suitable for application | coating.
Next, the joint surface of the electrostatic chuck portion 22 with the temperature adjustment base portion 23 is degreased and washed using, for example, acetone, and a silicone resin composition is fixed on the joint surface using, for example, a by coater. Apply to a thickness.

Next, a titanium (Ti) thin plate is placed on the coated surface, and the silicone resin composition is cured. Thereby, the cured body of the silicone resin composition becomes the organic adhesive layer 24 b on the electrostatic chuck portion 22 side in the organic adhesive layer 24.
Next, this titanium (Ti) thin plate is etched by, for example, a photolithography method to obtain a heater element 25 having a desired shape (heater pattern). Further, a power feeding terminal 51 is erected on the heater element 25 by using, for example, a welding method.

On the other hand, the joint surface of the temperature adjusting base portion 23 with the electrostatic chuck portion 22 is degreased and cleaned using, for example, acetone, and a ceramic spacer (not shown) is placed on the joint surface with a room temperature curing type silicone adhesive. Use to fix.
In this spacer, the electrostatic chuck portion 22 and the temperature adjusting base portion 23 are joined to each other at a predetermined interval, so that the thickness of the organic adhesive layer 24 sandwiched therebetween is set to a predetermined thickness. Therefore, the number of spacers may be appropriate. Further, the arrangement position is between the heater patterns of the heater element 25.

Next, the temperature adjusting base 23 is left at room temperature for a predetermined time to sufficiently cure the room temperature curable silicone adhesive, and a silicone resin composition for forming the organic adhesive layer 24a is applied thereon. To do. The application amount of the silicone-based resin composition is set within a predetermined amount so that the electrostatic chuck portion 22 and the temperature adjusting base portion 23 can be joined and integrated with the spacer kept at a constant interval.
As a method for applying the silicone resin composition, a bar coating method, a screen printing method, or the like can be used in addition to manual application using a spatula or the like.

After the application, the electrostatic chuck portion 22 and the temperature adjusting base portion 23 are overlapped with each other via the silicone resin composition. At this time, the power supply terminal 51 erected is inserted into a power supply terminal accommodation hole (not shown) drilled in the temperature adjusting base portion 23.
Then, the space between the electrostatic chuck portion 22 and the temperature adjusting base portion 23 is dropped until the thickness of the spacer is reached, and the extruded excess silicone resin composition is removed.
It is preferable to perform the dropping at a temperature at which the fluidity of the silicone resin composition is most obtained. The cured body of the silicone resin composition constitutes the organic adhesive layer 24a on the temperature adjusting base portion 23 side in the organic adhesive layer 24 having a two-layer structure.

The electrostatic chuck device 21 thus obtained has a practical strength in which the bonding strength between the electrostatic chuck portion 22 and the temperature adjusting plate portion 23 is 3 MPa or more. The organic adhesive layer 24 has a heat transfer coefficient of 0.5 W / mK or more and a Young's modulus of 8 MPa or less, and is excellent in thermal conductivity and extensibility.
In addition, since the heater element 25 is disposed in the organic adhesive layer 24 and the organic adhesive layer 24 has a thermal stress mitigating action, in order to increase the productivity of plasma processing on the plate-like sample W. Even if the temperature of the plate-like sample W is rapidly raised and lowered, no cracks are generated in the electrostatic chuck portion 22.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

"Example"
(Production of electrostatic chuck device)
An electrostatic chuck portion 22 having an internal electrode 33 for electrostatic attraction having a thickness of 20 μm embedded therein was produced by a known method.
The mounting plate 31 of the electrostatic chuck portion 22 is an alumina-silicon carbide composite sintered body containing 8% by mass of silicon carbide, and has a disk shape with a diameter of 298 mm and a thickness of 0.5 mm. Further, the electrostatic adsorption surface of the mounting plate 31 is formed as an uneven surface by forming a large number of protrusions having a height of 40 μm, and the top surface of these protrusions is used as a holding surface for the plate-like sample, and the concave and electrostatic The cooling gas can be allowed to flow in a groove formed between the adsorbed plate sample. The total area of the top surfaces of these protrusions was 15% of the area of the electrostatic adsorption surface.

Similarly to the mounting plate 31, the support plate 32 was an alumina-silicon carbide composite sintered body containing 8% by mass of silicon carbide, and had a disk shape with a diameter of 298 mm and a thickness of 1.0 mm.
By joining and integrating the mounting plate 31 and the support plate 32, the overall thickness of the electrostatic chuck portion 22 was 1.5 mm.

On the other hand, an aluminum temperature adjusting base portion 23 having a diameter of 340 mm and a height of 30 mm was produced by machining. A flow path 41 for circulating the refrigerant is formed inside the temperature adjusting base portion 23.
In addition, a square spacer having a width of 1 mm, a length of 1 mm, and a height of 300 μm was prepared from an alumina sintered body.

Moreover, the silicone resin TSE3221 to (Momentive Performance Materials Japan Ltd. GK), the surface of silicon oxide surface-coated aluminum nitride coated with (SiO ₂₎ (AlN) (manufactured by Toyo Aluminum Co.) powder TOYALNITE Are mixed so that the total volume of the silicone resin and the surface-coated aluminum nitride (AlN) powder is 30 vol%, and the mixture is stirred and defoamed to obtain a first silicone resin composition. Got.
The aluminum nitride powder used had an average particle size of 7 to 20 μm selected by a wet sieve. The thickness of silicon oxide (SiO ₂ ), which is a coating layer of this surface-coated aluminum nitride (AlN) powder, was 0.008 μm.

  Next, the joint surface of the electrostatic chuck portion 22 with the temperature adjustment plate portion 23 is sufficiently degreased and washed with acetone, and the first silicone resin composition is cured on the joint surface to a thickness of 40 μm. This was applied using a bar coater, and a titanium (Ti) thin plate having a thickness of 100 μm was placed on the coated surface. Subsequently, the electrostatic chuck part 22 and the titanium (Ti) thin plate were bonded and fixed in the atmosphere at 115 ° C. for 12 hours.

Next, the titanium (Ti) thin plate was etched into the heater pattern shown in FIG. Further, a titanium power feeding terminal 51 was erected on the heater element 25 using a welding method.
On the other hand, the joint surface of the temperature adjusting base portion 23 with the electrostatic chuck portion 22 is degreased and washed with acetone, and the spacer is placed on the joint surface with a room temperature curing type silicone adhesive, Shin-Etsu Silicone KE4895T (Shin-Etsu). Adhesion was performed using a chemical industry.
Next, the temperature adjusting plate part 23 was left in the atmosphere for 5 hours to sufficiently cure the room temperature curable silicone adhesive.

Moreover, the silicone resin TSE3221 to (Momentive Performance Materials Japan Ltd. GK), surface-coated surface-coated aluminum nitride by silicon oxide (SiO ₂₎ (AlN) (manufactured by Toyo Aluminum Co.) powder TOYALNITE Is mixed so as to be 20 vol% with respect to the total volume of the above-mentioned silicone resin and surface-coated aluminum nitride (AlN) powder, and this mixture is subjected to stirring and defoaming treatment to obtain a second silicone resin composition Got.
The aluminum nitride powder used had an average particle size of 7 to 20 μm selected by a wet sieve. The thickness of silicon oxide (SiO ₂ ), which is a coating layer of this surface-coated aluminum nitride (AlN) powder, was 0.008 μm.

Next, the second silicone resin composition was applied to the bonding surfaces of the electrostatic chuck portion 22 and the temperature adjusting base portion 23 using a spatula.
After the application, it was kept under conditions of 50 ° C. and 1 Pa or less for 30 minutes to perform vacuum defoaming treatment. Next, the electrostatic chuck portion 22 and the temperature adjustment base portion 23 are overlapped, and the gap between the electrostatic chuck portion 22 and the temperature adjustment base portion 23 is 300 μm in the atmosphere at 50 ° C., that is, a square shape. It dropped until it reached the height of the spacer.
Subsequently, it hold | maintains at 115 degreeC in air | atmosphere for 12 hours, the 2nd silicone resin composition is hardened, the electrostatic chuck part 22 and the base part 23 for temperature adjustment are joined, and the electrostatic chuck apparatus 21 of an Example Was made.

(Evaluation)
(1) Durability The silicon wafer having a diameter of 300 mm is electrostatically adsorbed on the mounting surface 31a of the electrostatic chuck portion 22, and the outside water is circulated through the flow path 41 of the temperature adjusting base portion 23 while circulating the cooling water at 20 ° C. By energizing only the heater element 25b, the temperature of the silicon wafer is raised from 25 ° C. to 80 ° C. at a rate of 3 ° C./second, held at 80 ° C. for 5 minutes, and then the heater element 25 is energized. And a thermal cycle for cooling to 25 ° C. was loaded 500 times.
As a result, no abnormality was found in the electrostatic chuck device.

(2) In-plane temperature control and heating / cooling characteristics of silicon wafer a. A silicon wafer having a diameter of 300 mm is electrostatically adsorbed on the mounting surface 31a of the electrostatic chuck portion 22, and the center temperature of the silicon wafer is 50 while circulating cooling water at 20 ° C. through the flow path 41 of the temperature adjusting base portion 23. The outer heater 25b and the inner heater 25a of the heater element 25 were energized so that the temperature was 0 ° C., and the in-plane temperature distribution of the silicon wafer at this time was measured using a thermography TVS-200EX (manufactured by Avionics, Japan). The result is shown in FIG. In the figure, A shows the in-plane temperature distribution in the one-diameter direction of the silicon wafer, and B shows the in-plane temperature distribution in the diametric direction perpendicular to the one-diameter direction of the silicon wafer.

next,
b. The energization amount of the outer heater 25b of the heater element 25 is increased, and the temperature of the outer peripheral portion of the silicon wafer is increased at a temperature increase rate of 3.6 ° C./second so that the temperature of the outer peripheral portion of the silicon wafer becomes 70 ° C. The temperature distribution was measured using a thermography TVS-200EX (Nippon Avionics). The result is shown in FIG. In the figure, A shows the in-plane temperature distribution in the one-diameter direction of the silicon wafer, and B shows the in-plane temperature distribution in the diametric direction perpendicular to the one-diameter direction of the silicon wafer.

further,
c. The energization of the outer heater 25b of the heater element 25 is stopped, and the temperature is lowered at a rate of temperature drop of 4.0 ° C./second so that the temperature of the outer peripheral portion of the silicon wafer becomes 30 ° C. It measured using thermography TVS-200EX (made by Nippon Avionics). The result is shown in FIG. In the figure, A shows the in-plane temperature distribution in the one-diameter direction of the silicon wafer, and B shows the in-plane temperature distribution in the diametric direction perpendicular to the one-diameter direction of the silicon wafer.

  According to the measurement results a to c above, it was found that the in-plane temperature of the silicon wafer was well controlled within a range of ± 20 ° C.

(3) In-plane temperature control of silicon wafer under pseudo plasma heat input The electrostatic chuck device 21 was fixed in a vacuum chamber, and the in-plane temperature of the silicon wafer under pseudo plasma heat input was measured. Here, as the pseudo-plasma heat input, heating is performed by an external heater which is disposed 40 mm above the mounting surface of the electrostatic chuck device 21 and has a surface shape with a diameter of 300 mm and whose outer peripheral portion generates a larger amount of heat than the inside. Using. A He gas having a pressure of 30 torr was passed through a groove formed between the silicon wafer and the electrostatic chucking surface of the electrostatic chuck portion.

  Here, first, a silicon wafer having a diameter of 300 mm is electrostatically adsorbed on the mounting surface 31a of the electrostatic chuck portion 22, and the silicon wafer is circulated through the flow path 41 of the temperature adjusting base portion 23 while circulating cooling water at 20 ° C. The outer heater 25b and the inner heater 25a of the heater element 25 were energized so that the temperature of the entire area was 40 ° C.

Then
d. The outer heater 25b was further energized while maintaining the above energized state. When the in-plane temperature of the silicon wafer at this time was measured with a thermocouple, the temperature at the center of the silicon wafer was 60 ° C., and the temperature at the outer periphery of the silicon wafer was 70 ° C.
Then
e. While the energization of the inner heater 25a and the outer heater 25b of the heater element 25 was maintained, the energization amount of the outer heater 25b of the heater element 25 was lowered. When the in-plane temperature of the silicon wafer at this time was measured with a thermocouple, the temperature was constant at 60 ° C. throughout the silicon wafer.

  According to the measurement results of de above, it was found that the in-plane temperature of the silicon wafer was well controlled within the range of 10 ° C. even under pseudo plasma heat input.

"Comparative example"
(Production of electrostatic chuck device)
According to the example, an electrostatic chuck device of a comparative example was produced.
However, the thickness of the electrostatic chuck portion is 3.5 mm, and this electrostatic chuck portion is the same as the embodiment formed by a molybdenum (Mo) thin plate having a thickness of 100 μm 1.5 mm below the internal electrode for electrostatic adsorption. Shaped heater elements were arranged.
In addition, the electrostatic chuck portion and the temperature adjusting base portion were bonded and integrated in the same manner as in the example using the first and second silicone resin compositions.

(Evaluation)
(1) Durability Durability of the electrostatic chuck device of the comparative example was evaluated according to the example.
As a result, it was confirmed that a large number of cracks were generated in the electrostatic chuck portion by applying one thermal cycle, and the electrostatic chuck device was destroyed.
(2) In-plane temperature control and temperature rise / fall characteristics of silicon wafer Using the electrostatic chuck device of the comparative example, the in-plane temperature control and temperature rise / fall characteristics of the silicon wafer were evaluated according to the examples.

According to these results, in any of the cases a to c, the controllable in-plane temperature is within the range of ± 10 ° C., and the in-plane temperature of the silicon wafer is controlled within the range of ± 20 ° C. Was inferior to the in-plane temperature control characteristics of the electrostatic chuck device of the example.
Moreover, the maximum value of the temperature raising / lowering rate for raising the temperature of the outer peripheral portion of the silicon wafer from 50 ° C. to 70 ° C. or lowering the temperature from 50 ° C. to 30 ° C. is 2 ° C./second. It was inferior to the temperature rise characteristic of the apparatus.

DESCRIPTION OF SYMBOLS 21 Electrostatic chuck apparatus 22 Electrostatic chuck part 23 Temperature adjustment base part 24 Organic adhesive layer 24a 1st organic adhesive layer 24b 2nd organic adhesive layer 25 Heater element 25a Inner heater 25b Outer heater 26 Connection position with power supply terminal 31 Mounting plate 31a Mounting surface 32 Support plate 33 Electrostatic adsorption internal electrode 34 Insulating material 35 Power supply terminal 41 Flow path 51 Power supply terminal

Claims (5)

An electrostatic chuck portion in which one principal surface is a mounting surface on which a plate-like sample is placed and an internal electrode for electrostatic attraction is provided;
A temperature adjusting base formed by forming a flow path for circulating the heat medium therein;
A thin plate-like heater element made of a nonmagnetic metal having a thickness of 200 μm or less, disposed between the electrostatic chuck portion and the temperature adjusting base portion;
An organic adhesive layer formed by adhering and integrating the electrostatic chuck portion and the temperature adjusting base portion while maintaining a certain interval, and sandwiching the heater element,
The organic adhesive layer adhesively integrates the first organic adhesive layer that is bonded and integrated with the temperature adjusting base portion, and the first organic adhesive layer and the electrostatic chuck portion. It has a two-layer structure with a second organic adhesive layer, and the heater element is sandwiched between the first organic adhesive layer and the second organic adhesive layer. Chuck device. The organic adhesive layer contains a filler made of surface-coated aluminum nitride particles, and the heat transfer coefficient of the second organic adhesive layer is higher than the heat transfer coefficient of the first organic adhesive layer. 2. The electrostatic chuck device according to claim 1 , wherein the electrostatic chuck device is large. The electrostatic chuck device according to claim 1 , wherein the organic adhesive layer is made of a silicone resin. The thickness of the first organic adhesive layer is 100 μm or more and 350 μm or less, and the thickness of the second organic adhesive layer is 10 μm or more and 100 μm or less . electrostatic chucking device according to any one. The electrostatic chuck apparatus according to claim 1, wherein the first organic adhesive layer includes a spacer.