JP2018006768A - Electrostatic chuck - Google Patents

Abstract

An electrostatic chuck capable of easily and efficiently controlling the temperature of an object to be adsorbed while achieving uniform temperature of the object to be adsorbed. An electrostatic chuck (1) includes a metal base part (3) and an adsorption electrode (21) that is disposed on the metal base part (3) and attracts an object to be adsorbed by electrostatic attraction, and from the metal base part (3). And a ceramic adsorbing portion 2 having a low thermal conductivity. The metal base portion 3 is disposed closer to the ceramic adsorbing portion 2 than the cooling portion 31 in the stacking direction X of the metal base portion 3 and the ceramic adsorbing portion 2 and the cooling portion 31 having the refrigerant flow path 311 for circulating the refrigerant. A first heater section 33 is also provided. The ceramic adsorption unit 2 is provided with a second heater unit 22 configured to be able to adjust the temperatures of a plurality of regions formed in the ceramic adsorption unit 2. [Selection] Figure 2

Description

  The present invention relates to an electrostatic chuck used for fixing a semiconductor wafer, correcting the flatness of a semiconductor wafer, and the like.

  Conventionally, in a semiconductor manufacturing apparatus, a process such as dry etching (for example, plasma etching) is performed on a semiconductor wafer (for example, a silicon wafer). In order to improve processing accuracy such as dry etching, it is necessary to securely fix the semiconductor wafer. For this reason, an electrostatic chuck for fixing a semiconductor wafer by electrostatic attraction has been proposed as a fixing means for fixing the semiconductor wafer.

  For example, the electrostatic chuck described in Patent Document 1 has an adsorption electrode in a ceramic insulating plate (ceramic adsorption portion), and uses an electrostatic attractive force generated when a voltage is applied to the adsorption electrode. Thus, the semiconductor wafer is adsorbed on the upper surface (adsorption surface) of the ceramic insulating plate. This electrostatic chuck is configured by joining a metal base portion to the lower surface of a ceramic insulating plate.

  2. Description of the Related Art In recent years, a technique in which an electrostatic chuck has a function of adjusting the temperature of a semiconductor wafer is known in order to suitably process a semiconductor wafer. For example, Patent Document 2 discloses an electrostatic chuck in which a heater electrode is provided in a ceramic insulating plate. In the electrostatic chuck having such a configuration, the semiconductor wafer adsorbed on the adsorption surface of the ceramic insulating plate can be heated by heating the ceramic insulating plate with the heater electrode.

JP 2008-205510 A JP 2004-71647 A

  However, in the electrostatic chuck configured as in Patent Document 2, the heater electrode is provided in a ceramic insulating plate made of a ceramic having a lower thermal conductivity than that of metal or the like. Therefore, when heating by the heater electrode, temperature unevenness (temperature variation in the plane direction) occurs on the adsorption surface of the ceramic insulating plate, and furthermore, temperature unevenness also occurs on the semiconductor wafer adsorbed on the adsorption surface of the ceramic insulating plate There is. In such a case, there is a possibility that variations may occur in processing such as dry etching on the semiconductor wafer. On the other hand, in processing such as dry etching on a semiconductor wafer, there is a problem that the processing varies depending on the reaction gas concentration, plasma density, and the like.

  The present invention has been made in view of such a background, and is capable of local temperature adjustment of an object to be adsorbed while achieving uniform temperature of the object to be adsorbed, and further having an excellent temperature rise characteristic. Is to provide.

The electrostatic chuck of the present invention has a metal base portion and an electrode for adsorption that is disposed on the metal base portion and adsorbs an object to be adsorbed by electrostatic attraction, and has a thermal conductivity higher than that of the metal base portion. A low-temperature ceramic adsorbing part, and the metal base part includes a cooling part having a refrigerant flow path for circulating a refrigerant, and the ceramic is more than the cooling part in the stacking direction of the metal base part and the ceramic adsorbing part. A first heater unit disposed on the side of the adsorption unit, and the ceramic adsorption unit includes a second heater unit configured to be capable of adjusting temperatures of a plurality of regions formed in the ceramic adsorption unit. Is provided.

  In the electrostatic chuck, the metal base portion is provided with a cooling portion and a first heater portion. Therefore, the entire electrostatic chuck can be uniformly heated through the metal base portion having high thermal conductivity by generating heat in the first heater portion. Thereby, it is possible to equalize the object to be adsorbed such as a semiconductor wafer adsorbed on the ceramic adsorbing portion, and to improve the processing accuracy in processing such as dry etching. Further, the temperature of the entire electrostatic chuck can be stabilized by circulating the refrigerant through the refrigerant flow path of the cooling unit.

  Moreover, the ceramic adsorption | suction part is provided with the 2nd heater part comprised so that the temperature of several area | regions was each adjustable. Therefore, the temperature adjustment of each region of the ceramic suction portion can be performed with high accuracy. As a result, the local temperature adjustment of an object to be adsorbed such as a semiconductor wafer adsorbed on the ceramic adsorbing portion can be performed, and variations in processing such as dry etching can be suppressed.

  For example, when temperature unevenness occurs in the ceramic adsorbing portion and the processing such as dry etching varies, the temperature of each region can be adjusted so that the temperature variation becomes small. On the other hand, if variations in processing such as dry etching occur due to the reaction gas concentration or plasma density, the temperature of each region should be adjusted so that the variation in processing is reduced by creating a temperature difference between the regions. Can do.

  In addition, as described above, the electrostatic chuck includes two heater portions including a first heater portion provided on the metal base portion and a second heater portion provided on the ceramic suction portion. Therefore, when the object to be adsorbed is heated via the electrostatic chuck (ceramic adsorbing part), the object to be adsorbed can be heated quickly by using these two heater parts, and the temperature rise characteristic is improved. Can do.

As described above, according to the present invention, it is possible to locally adjust the temperature of an object to be adsorbed while achieving uniform temperature of the object to be adsorbed, and to provide an electrostatic chuck having excellent temperature rise characteristics. it can.
In the electrostatic chuck, the thermal conductivity of each of the metal base portion and the ceramic suction portion indicates the thermal conductivity of a material mainly constituting the metal base portion and the ceramic suction portion.

  In addition, the first heater unit is configured to generate heat, and after the first heater unit reaches a predetermined temperature, the second heater unit is configured to generate heat. It may be configured such that the amount of power input to the power supply is different. In this case, after the first adsorbent is sufficiently soaked by the first heater unit, the local temperature adjustment of the adsorbent can be accurately performed by the second heater unit.

  The amount of power input when the first heater unit generates heat may be configured to be greater than the amount of power input when the second heater unit generates heat. In this case, the first heater part provided in the metal base part can be mainly used, and the second heater part provided in the ceramic suction part can be used supplementarily. This makes it possible to locally adjust the temperature of the object to be adsorbed by the second heater unit while sufficiently obtaining the effect of soaking the object to be adsorbed by the first heater unit.

The amount of power input when the first heater unit generates heat may be configured to be smaller than the amount of power input when the second heater unit generates heat. In this case, the temperature adjustment of each region of the ceramic adsorbing portion by the second heater portion and the local temperature adjustment of the object to be adsorbed can be performed with higher accuracy. In particular, it is very effective when a temperature difference is to be made between the areas of the ceramic adsorption portion.

  The main material (insulating material other than the conductive portion) constituting the ceramic adsorbing portion is mainly composed of high-temperature fired ceramic such as alumina, yttria (yttrium oxide), aluminum nitride, boron nitride, silicon carbide, silicon nitride. And the like. Depending on the application, a sintered body mainly composed of a low-temperature fired ceramic such as a glass ceramic obtained by adding an inorganic ceramic filler such as alumina to a borosilicate glass or a lead borosilicate glass may be selected. Alternatively, a sintered body mainly composed of a dielectric ceramic such as barium titanate, lead titanate, or strontium titanate may be selected.

  In each process such as dry etching in semiconductor manufacturing, various techniques using plasma are employed. In the treatment using plasma, corrosive gas such as halogen gas is frequently used. For this reason, high corrosion resistance is required for the electrostatic chuck exposed to corrosive gas or plasma. Therefore, the ceramic adsorbing portion is preferably made of a material having corrosion resistance against corrosive gas or plasma, for example, a material mainly composed of alumina or yttria.

  Further, the ceramic adsorbing portion can be configured by laminating a plurality of ceramic layers. In this case, various structures (for example, an adsorption electrode, a second heater portion, etc.) can be easily formed in the ceramic adsorption portion.

The adsorption electrode can be formed by using a conductive paste containing a metal powder, applying the paste by a conventionally known method, for example, a printing method, and then baking.
Moreover, copper (Cu), aluminum (Al), iron (Fe), titanium (Ti) etc. can be used as main materials which comprise the said metal base part.

  Moreover, the said metal base part and the said ceramic adsorption | suction part can be joined by the contact bonding layer etc., for example. As a material constituting the adhesive layer, for example, a resin material such as a silicone resin, an acrylic resin, an epoxy resin, a polyimide resin, a polyamideimide resin, a polyamide resin, or a metal material such as indium can be selected. In particular, various resin adhesives having heat resistance of, for example, 100 ° C. or higher are preferable.

  Moreover, the difference in coefficient of thermal expansion is large between the ceramic adsorption portion made of a ceramic material and the metal base portion made of a metal material. Therefore, the adhesive layer disposed between the two is particularly preferably made of an elastically deformable (flexible) resin material having a function as a buffer material.

  Moreover, as a to-be-adsorbed object adsorb | sucked by a ceramic adsorption | suction part, a semiconductor wafer, a glass substrate, etc. are mentioned, for example.

3 is a perspective view showing a partial cross section of the electrostatic chuck in Embodiment 1. FIG. FIG. 3 is a cross-sectional view of the electrostatic chuck in the first embodiment. FIG. 5 is an explanatory diagram illustrating an arrangement state of a second heater unit (heater electrode) in the first embodiment. It is explanatory drawing which shows the arrangement | positioning state of the 1st heater part (sheath heater) in Embodiment 1. FIG. 6 is a cross-sectional view of an electrostatic chuck in Embodiment 2. FIG. FIG. 6 is a cross-sectional view of an electrostatic chuck in a third embodiment. It is sectional drawing of the electrostatic chuck in other embodiment.

(Embodiment 1)
An embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 4, the electrostatic chuck 1 of the present embodiment is disposed on the metal base portion 3 and the metal base portion 3, and sucks an object (semiconductor wafer) 8 by electrostatic attraction. The ceramic adsorbing part 2 having the adsorbing electrode 21 and having a lower thermal conductivity than the metal base part 3 is provided.

  As shown in the figure, the metal base portion 3 has a cooling portion 31 having a refrigerant flow path 311 for circulating a refrigerant, and a ceramic than the cooling portion 31 in the stacking direction X of the metal base portion 3 and the ceramic adsorption portion 2. A first heater unit 33 disposed on the suction unit 2 side is provided. The ceramic suction part 2 is provided with a second heater part 22 configured to be able to adjust the temperatures of a plurality of regions (center part 231 and outer peripheral part 232) formed in the ceramic suction part 2 respectively. This will be described in detail below.

  As shown in FIG. 1, the electrostatic chuck 1 is for attracting and holding a semiconductor wafer 8 that is an object to be attracted, and includes a metal base portion 3 and a ceramic attracting portion 2 disposed on the metal base portion 3. And. The metal base part 3 and the ceramic adsorption | suction part 2 are joined by the contact bonding layer 41 which consists of a silicone resin arrange | positioned between both. Hereinafter, in the present embodiment, one side (the ceramic suction part 2 side) in the stacking direction X of the metal base part 3 and the ceramic suction part 2 will be described as the upper side, and the other side (the metal base part 3 side) will be the lower side.

  As shown in FIG. 2, the upper surface of the circular plate-shaped ceramic adsorption portion 2 is an adsorption surface 201 that adsorbs the semiconductor wafer 8. Moreover, the ceramic adsorption | suction part 2 is comprised by laminating | stacking the several ceramic layer (not shown) which has insulation. Each ceramic layer is made of an alumina sintered body containing alumina as a main component. Further, the ceramic adsorbing portion 2 (insulating portion excluding the adsorbing electrode 21 described later) has a lower thermal conductivity than the metal base portion 3 (first base layer 3a, second base layer 3b described later). In addition, the thermal conductivity of the ceramic adsorption | suction part 2 is 30 W / m * K, and the thermal conductivity of the metal base part 3 is 155 W / m * K.

  In addition, a pair of suction electrodes 21 having a semicircular planar shape is disposed inside the ceramic suction portion 2. The attracting electrode 21 applies a DC high voltage between them to generate an electrostatic attractive force, and the electrostatic attractive force attracts and fixes the semiconductor wafer 8 to the attracting surface 201 of the ceramic attracting portion 2. The adsorption electrode 21 is connected to an electrode power source (not shown). The adsorption electrode 21 is made of tungsten.

  A second heater portion 22 is disposed inside the ceramic suction portion 2. The second heater unit 22 is composed of two heater electrodes 221 and 222. Further, the second heater portion 22 is arranged on the metal base portion 3 side with respect to the adsorption electrode 21 in the stacking direction X.

  As shown in FIG. 3, the ceramic suction portion 2 has two regions of a central portion 231 and an outer peripheral portion 232. Heater electrodes 221 and 222 are disposed on the central portion 231 and the outer peripheral portion 232, respectively. The heater electrodes 221 and 222 are configured to be capable of temperature control independently of each other. That is, the second heater unit 22 is configured to be able to adjust the temperature of each region of the central portion 231 and the outer peripheral portion 232 by the two heater electrodes 221 and 222.

As shown in FIG. 2, the metal base portion 3 has a circular plate-shaped first in the stacking direction X.
A base layer 3a and a second base layer 3b are laminated in order from the ceramic suction portion 2 side. The first base layer 3a and the second base layer 3b are made of a material mainly composed of aluminum.

  A first heater portion 33 is provided on the first base layer 3a. The second base layer 3b is provided with a cooling unit 31. The first heater unit 33 is arranged on the ceramic adsorption unit 2 side with respect to the cooling unit 31 in the stacking direction X.

  On the lower surface of the first base layer 3a, an accommodation groove portion 301 for accommodating the sheath heater 331 constituting the first heater portion 33 is formed. The housing groove 301 is formed in a spiral shape over the entire lower surface of the first base layer 3a. A sheath heater 331 is disposed in the housing groove 301.

  As shown in FIG. 4, the long sheath heater 331, which is a heating element, is arranged in a spiral shape along the accommodation groove 301. The sheath heater 331 is joined to the first base layer 3a by brazing. The sheath heater 331 is connected to a heater power supply (not shown).

  As shown in FIG. 2, a coolant channel 311 constituting the cooling unit 31 is provided inside the second base layer 3 b. For example, a refrigerant such as a fluorinated liquid or pure water can be circulated in the refrigerant flow path 311. The refrigerant flow path 311 is provided with an introduction part 312 for introducing the refrigerant and a discharge part 313 for discharging the refrigerant.

  As shown in FIG. 1, a cooling gas supply path 51, which is a passage for supplying a cooling gas such as helium for cooling the semiconductor wafer 8, is provided inside the ceramic adsorption unit 2 and the metal base unit 3. . On the adsorption surface 201 of the ceramic adsorption unit 2, a plurality of cooling openings 52 formed by opening the cooling gas supply passages 51, and the cooling gas supplied from the cooling openings 52 are formed on the entire adsorption surface 201. An annular cooling groove 53 formed so as to expand is provided.

Next, a method for manufacturing the electrostatic chuck 1 will be briefly described.
In producing the ceramic adsorbing part 2, a plurality of alumina green sheets to be a ceramic layer constituting the ceramic adsorbing part 2 were formed. And the space etc. used as the flow path of cooling gas, such as the cooling gas supply path 51, were formed in the required location with respect to the several alumina green sheet. In addition, a slurry-like electrode material for forming the adsorption electrode 21 and the second heater portion 22 (heater electrodes 221 and 222) was printed at a necessary location on the alumina green sheet by, for example, a screen printing method or the like.

  Next, a plurality of alumina green sheets were thermocompression bonded and cut into a predetermined shape (circular plate shape) to produce an intermediate laminate. And this intermediate laminated body was baked for the predetermined time at the temperature of 1400-1600 degreeC in reducing atmosphere. Thereby, the ceramic adsorption | suction part 2 comprised by the several ceramic layer was produced.

  In producing the metal base portion 3, the first base layer 3a and the second base layer 3b constituting the metal base portion 3 were produced. At this time, the receiving groove 301 was cut in the first base layer 3a. In addition, the coolant channel 311 constituting the cooling unit 31 was formed in the second base layer 3b.

  Next, after the sheath heater 331 constituting the first heater portion 33 was fitted and disposed in the accommodation groove portion 301 of the first base layer 3a, the first base layer 3a and the second base layer 3b were joined by brazing. Thereby, the metal base part 3 was produced.

  Next, an adhesive made of silicone resin was interposed between the ceramic adsorbing part 2 and the metal base part 3, and both were laminated. Thereby, the ceramic adsorption | suction part 2 and the metal base part 3 were joined by the contact bonding layer 41. FIG. Thus, the electrostatic chuck 1 was produced.

Next, temperature control of the semiconductor wafer 8 using the electrostatic chuck 1 will be briefly described.
Here, the case where the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is controlled to different temperatures (10 ° C. and 60 ° C.) will be described.

  For example, when the temperature of the semiconductor wafer 8 is raised (when controlled to 60 ° C.), the first heater 33 is heated (set temperature 55 ° C.) and the entire electrostatic chuck 1 is heated uniformly through the metal base 3. To do. Then, the 2nd heater part 22 is made to heat-generate (setting temperature 55-60 degreeC), and the temperature adjustment of each area | region (center part 231 and the outer peripheral part 232) of the ceramic adsorption | suction part 2 is performed.

  Note that the amount of power input when the first heater unit 33 generates heat is approximately 99% of the total. In addition, the amount of power input to each region (the center portion 231 and the outer peripheral portion 232) when the second heater portion 22 generates heat, that is, the amount of power input to the heater electrode 221 is 0.5% of the total, and the heater electrode The amount of power input to 222 is 0.5% of the total.

  At this time, a refrigerant (set temperature of 10 ° C.) is circulated through the refrigerant flow path 311 of the first cooling unit 31 to stabilize the temperature of the entire electrostatic chuck 1. Thereby, the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is heated and controlled to a predetermined temperature (60 ° C.).

  On the other hand, when the temperature of the semiconductor wafer 8 is lowered (when controlled to 10 ° C.), the heat generation of the first heater unit 33 and the second heater unit 22 is stopped. Then, the refrigerant (set temperature 10 ° C.) is caused to flow through the refrigerant flow path 311 of the cooling unit 31. Thereby, the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is cooled and controlled to a predetermined temperature (10 ° C.).

Next, the effect of the electrostatic chuck 1 of this embodiment will be described.
In the electrostatic chuck 1 of the present embodiment, the metal base portion 3 is provided with a cooling portion 31 and a first heater portion 33. Therefore, the entire electrostatic chuck 1 can be uniformly heated through the metal base portion 3 having a high thermal conductivity by causing the first heater portion 33 to generate heat. As a result, the semiconductor wafer 8 adsorbed on the ceramic adsorbing portion 2 can be soaked, and the processing accuracy in processing such as dry etching can be improved. In addition, the temperature of the entire electrostatic chuck 1 can be stabilized by circulating the refrigerant through the refrigerant flow path 311 of the cooling unit 31.

  In addition, the ceramic adsorption unit 2 is provided with a second heater unit 22 configured to be able to adjust the temperatures of a plurality of regions (a center portion 231 and an outer peripheral portion 232). Therefore, the temperature adjustment of each area | region of the ceramic adsorption | suction part 2 can be performed accurately. Thereby, local temperature adjustment of the semiconductor wafer 8 adsorbed on the ceramic adsorbing portion 2 can be performed, and variations in processing such as dry etching can be suppressed.

  For example, when temperature unevenness occurs in the ceramic adsorbing portion 2 and variation occurs in processing such as dry etching, the temperature of each region can be adjusted so that the variation in temperature becomes small. On the other hand, if variations in processing such as dry etching occur due to the reaction gas concentration or plasma density, the temperature of each region should be adjusted so that the variation in processing is reduced by creating a temperature difference between the regions. Can do.

Further, as described above, the electrostatic chuck 1 includes two heater portions, that is, the first heater portion 33 provided in the metal base portion 3 and the second heater portion 22 provided in the ceramic suction portion 2. . For this reason, when the semiconductor wafer 8 is heated via the electrostatic chuck 1 (ceramic suction portion 2), the two heater portions (the first heater portion 33 and the second heater portion 22) are used. Can be heated quickly, and the temperature rise characteristics can be improved.

  In the present embodiment, the first heater unit 33 is configured to generate heat, and after the first heater unit 33 reaches a predetermined temperature, the second heater unit 22 is configured to generate heat. The amount of electric power supplied to each region (center portion 231 and outer peripheral portion 232) during heat generation is configured to be different. Therefore, after the semiconductor wafer 8 is sufficiently soaked by the first heater unit 33, the local temperature adjustment of the semiconductor wafer 8 can be accurately performed by the second heater unit 22.

  Further, the amount of power input when the first heater unit 33 generates heat is configured to be larger than the amount of power input when the second heater unit 22 generates heat. Therefore, the first heater part 33 provided on the metal base part 3 can be mainly used, and the second heater part 22 provided on the ceramic suction part 2 can be used supplementarily. As a result, the temperature of the semiconductor wafer 8 can be locally adjusted by the second heater unit 22 while sufficiently obtaining the effect of soaking the semiconductor wafer 8 by the first heater unit 33.

  As described above, according to this embodiment, it is possible to locally adjust the temperature of the semiconductor wafer 8 while keeping the temperature of the semiconductor wafer 8 that is the object to be adsorbed, and to further improve the electrostatic property. A chuck 1 can be provided.

(Embodiment 2)
This embodiment is an example in which a heat insulating portion 34 is provided on the metal base portion 3 as shown in FIG.
As shown in the figure, in the stacking direction X, a heat insulating part 34 having a lower thermal conductivity than the metal base part 3 is disposed between the cooling part 31 and the first heater part 33. The heat insulating part 34 is joined to the metal base part 3 by brazing. This will be described in detail below.

  As shown in the figure, the metal base portion 3 is configured by laminating a circular plate-like first base layer 3a, second base layer 3b, and third base layer 3c in this order from the ceramic adsorption portion 2 side. The basic configuration of the first base layer 3a is the same as that of the first base layer 3a (see FIG. 2) of the first embodiment described above. The basic configuration of the third base layer 3c is the same as that of the second base layer 3b (see FIG. 2) of the first embodiment.

  An accommodation recess 302 for accommodating the heat insulating portion 34 is formed on the lower surface of the second base layer 3b. A circular plate-shaped heat insulating portion 34 is disposed in the housing recess 302. The heat insulating part 34 is joined to the second base layer 3b by brazing.

  The heat insulating part 34 is embedded in the metal base part 3. Specifically, in a process such as dry etching on the semiconductor wafer 8, when the inside of the chamber is set to a vacuum atmosphere, the heat insulating portion 34 is not exposed from the metal base portion 3 at a location in contact with the vacuum atmosphere.

  As shown in the figure, in the stacking direction X, the heat insulating part 34 is disposed between the cooling part 31 (refrigerant flow path 311) and the first heater part 33 (sheath heater 331). Further, the heat insulating portion 34 has a larger outer diameter in the direction (radial direction) orthogonal to the stacking direction X than the first heater portion 33 (region where the sheath heater 331 is disposed).

The heat insulating portion 34 is made of a material mainly composed of aluminum, like the metal base portion 3. The heat insulating part 34 is a porous body, and has a higher porosity and lower thermal conductivity than the metal base part 3 (first base layer 3a, second base layer 3b, third base layer 3c). The heat insulating portion 34 has a porosity of 90% and a thermal conductivity of 16 W / m · K. The metal base portion 3 has a porosity of approximately 0% and a thermal conductivity of 155 W / m · K.

  As the heat insulating part 34, a dense bulk body can be used. Moreover, as a material which comprises the heat insulation part 34, stainless steel, titanium, constantan, monel metal, nichrome etc. can also be used, for example. Other basic configurations are the same as those of the first embodiment.

Next, the effect of this embodiment is demonstrated.
In the electrostatic chuck 1 of the present embodiment, a heat insulating part 34 having a lower thermal conductivity than the metal base part 3 is disposed between the cooling part 31 and the first heater part 33 in the metal base part 3. Therefore, when the semiconductor wafer 8 is heated via the electrostatic chuck 1 (ceramic suction part 2), heat is transferred from the first heater part 33 to the cooling part 31 (heat escape from the first heater part 33). Therefore, the first heater unit 33 can generate heat efficiently. Thereby, the semiconductor wafer 8 can be heated rapidly, and a temperature rise characteristic can be improved.

  For example, when controlling the semiconductor wafer 8 to a different temperature in a process such as dry etching on the semiconductor wafer 8, temperature control of the semiconductor wafer 8 can be easily performed even when the temperature difference to be controlled is large. Can do. That is, it becomes possible to make a difference in the temperature to be controlled.

  Further, the heat insulating portion 34 has a portion having an outer diameter larger than that of the first heater portion 33 in the direction orthogonal to the stacking direction X. Therefore, the heat transfer from the first heater unit 33 to the cooling unit 31 (heat escape from the first heater unit 33) can be further suppressed by the heat insulating unit 34.

  The heat insulating part 34 is embedded in the metal base part 3. Therefore, it can be used even if the heat insulation part 34 is a porous body like this embodiment. Moreover, corrosion of the heat insulation part 34 by the reactive gas used for processes, such as dry etching with respect to the semiconductor wafer 8, can be prevented.

  The heat insulating portion 34 is made of the same material as the metal base portion 3 and has a higher porosity than the metal base portion 3. Therefore, it becomes easy to join the heat insulating part 34 to the metal base part 3 (second base layer 3b) by brazing. Further, the thermal conductivity of the heat insulating portion 34 can be made lower than that of the metal base portion 3 only by making the porosity of the heat insulating portion 34 smaller than that of the metal base portion 3. Other functions and effects are the same as those of the first embodiment.

(Embodiment 3)
In the present embodiment, as shown in FIG. 6, two cooling units are provided in the metal base unit 3.
As shown in the figure, in addition to the cooling unit 31 of the first embodiment (hereinafter referred to as the first cooling unit 31 in the present embodiment), the metal base unit 3 has a refrigerant channel 321 for circulating the refrigerant. In addition, a second cooling part 32 disposed on the ceramic suction part 2 side with respect to the first cooling part 31 in the stacking direction X is provided. This will be described in detail below.

  As shown in the figure, a coolant channel 321 constituting the second cooling unit 32 is provided in the first base layer 3a. In the refrigerant flow path 321, for example, a refrigerant such as a fluorinated liquid or pure water can be circulated. The refrigerant flow path 321 is provided with an introduction part 322 for introducing the refrigerant and a discharge part 323 for discharging the refrigerant.

  Further, the second cooling unit 32 is arranged in the stacking direction X above the first heater unit 33 (on the ceramic suction unit 2 side). Further, the first cooling unit 31 is disposed below the first heater unit 33 in the stacking direction X. That is, the first heater unit 33 is disposed between the first cooling unit 31 and the second cooling unit 32 in the stacking direction X. Other basic configurations are the same as those of the first embodiment.

Next, temperature control of the semiconductor wafer 8 using the electrostatic chuck 1 will be briefly described.
Here, the case where the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is controlled to different temperatures (10 ° C. and 60 ° C.) will be described.

  For example, when the temperature of the semiconductor wafer 8 is raised (when controlled to 60 ° C.), the first heater 33 is heated (set temperature 55 ° C.) and the entire electrostatic chuck 1 is heated uniformly through the metal base 3. To do. Then, the 2nd heater part 22 is made to heat-generate (setting temperature 55-60 degreeC), and the temperature adjustment of each area | region (center part 231 and the outer peripheral part 232) of the ceramic adsorption | suction part 2 is performed. The amount of electric power that is input when the first heater unit 33 and the second heater unit 22 generate heat is the same as in the first embodiment.

  At this time, a refrigerant (set temperature of 50 ° C.) is circulated through the refrigerant flow path 311 of the first cooling unit 31 to stabilize the temperature of the entire electrostatic chuck 1. Further, the refrigerant is not circulated through the refrigerant flow path 321 of the second cooling unit 32. Thereby, the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is heated and controlled to a predetermined temperature (60 ° C.).

  On the other hand, when the temperature of the semiconductor wafer 8 is lowered (when controlled to 10 ° C.), the heat generation of the first heater unit 33 and the second heater unit 22 is stopped. Further, the refrigerant is not circulated through the refrigerant flow path 311 of the first cooling unit 31. Then, the refrigerant (set temperature 10 ° C.) is circulated through the refrigerant flow path 321 of the second cooling unit 32. Thereby, the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is cooled and controlled to a predetermined temperature (10 ° C.).

Next, the effect of this embodiment is demonstrated.
In the electrostatic chuck 1 of the present embodiment, the metal base portion 3 is provided with a first cooling portion 31 and a second cooling portion 32. Therefore, when the temperature of the semiconductor wafer 8 adsorbed on the adsorption surface 201 of the ceramic adsorption unit 2 is increased, the first heater unit 33 generates heat, and the refrigerant flows through the refrigerant flow path 311 of the first cooling unit 31. As a result, the electrostatic chuck 1 can be appropriately heated and the temperature of the entire electrostatic chuck 1 can be stabilized.

  At this time, the temperature of the refrigerant (50 ° C.) flowing through the refrigerant flow path 311 of the first cooling unit 31 is brought closer to the set temperature (55 ° C.) of the first heater unit 33, thereby the first cooling from the first heater unit 33. Transmission of heat to the part 31 (heat escape of the first heater part 33) can be suppressed, and the first heater part 33 can efficiently generate heat. Thereby, the semiconductor wafer 8 can be heated rapidly and the temperature rise characteristic can be improved. Furthermore, by preventing the refrigerant from flowing through the refrigerant flow path 321 of the second cooling unit 32, the above-described temperature rise characteristic improvement effect can be further enhanced.

  On the other hand, when the temperature of the semiconductor wafer 8 is lowered, the heat generation of the first heater unit 33 is stopped and the refrigerant is circulated through the refrigerant flow path 321 of the second cooling unit 32. Thereby, the semiconductor wafer 8 can be rapidly cooled, and the temperature drop characteristic can be improved. Furthermore, by preventing the refrigerant from flowing through the refrigerant flow path 311 of the first cooling unit 31, the above-described temperature-falling characteristic improvement effect can be further enhanced.

  Therefore, for example, in processing such as dry etching on the semiconductor wafer 8, even when the semiconductor wafer 8 is controlled at different temperatures and processing is performed at each temperature, the temperature control of the semiconductor wafer 8 is easily and quickly performed. be able to. That is, even when the temperature difference to be controlled is large, the semiconductor wafer 8 can be easily controlled to a desired temperature. Moreover, the temperature control (temperature increase / decrease) can be performed quickly.

  Further, the temperature (50 ° C.) of the refrigerant flowing through the refrigerant flow path 311 of the first cooling unit 31 is higher than the temperature (10 ° C.) of the refrigerant flowing through the refrigerant flow path 321 of the second cooling unit 32. Therefore, both the temperature rise characteristic improvement effect by the first cooling unit 31 and the temperature drop improvement effect by the second cooling unit 32 can be sufficiently obtained, and the temperature control characteristic can be further improved.

  Further, when the first heater unit 33 generates heat, the flow rate of the refrigerant flowing through the refrigerant flow path 311 of the first cooling unit 31 is larger than the flow rate of the refrigerant flowing through the refrigerant flow path 321 of the second cooling unit 32. In addition, when the heat generation of the first heater unit 33 is stopped, the flow rate of the refrigerant flowing through the refrigerant channel 321 of the second cooling unit 32 is higher than the flow rate of the refrigerant flowing through the refrigerant channel 311 of the first cooling unit 31. It is configured to increase. Therefore, when the first heater unit 33 generates heat, the effect of improving the temperature rise by the first cooling unit 31 can be further enhanced, and when the first heater unit 33 stops generating heat, the second cooling unit 32 decreases the temperature. The characteristic improvement effect can be further enhanced. Other functions and effects are the same as those of the first embodiment.

In addition, this invention is not limited to the above-mentioned Embodiments 1-3, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
For example, the amount of power input when the first heater unit 33 generates heat may be configured to be smaller than the amount of power input when the second heater unit 22 generates heat. In this case, the temperature adjustment of each region of the ceramic adsorption unit 2 by the second heater unit 22 and the local temperature adjustment of the semiconductor wafer 8 can be performed with higher accuracy. In particular, this is very effective when it is desired to create a temperature difference between the areas of the ceramic suction portion 2.

  Moreover, as shown in FIG. 7, it can also be set as the structure provided with both the heat insulation part 34 of the above-mentioned Embodiment 2, and the 2nd cooling part 32 of the above-mentioned Embodiment 3. FIG.

DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck 2 ... Ceramic adsorption | suction part 21 ... Electrode for adsorption | suction 22 ... 2nd heater part 3 ... Metal base part 31 ... Cooling part 311 ... Refrigerant flow path 33 ... 1st heater part 8 ... Adsorbed object (semiconductor wafer)
X: Stacking direction

The electrostatic chuck of the present invention has a metal base portion and an electrode for adsorption that is disposed on the metal base portion and adsorbs an object to be adsorbed by electrostatic attraction, and has a thermal conductivity higher than that of the metal base portion. A low-temperature ceramic adsorbing part, and the metal base part includes a cooling part having a refrigerant flow path for circulating a refrigerant, and the ceramic is more than the cooling part in the stacking direction of the metal base part and the ceramic adsorbing part. A first heater unit disposed on the side of the adsorption unit, and the ceramic adsorption unit includes a second heater unit configured to be capable of adjusting temperatures of a plurality of regions formed in the ceramic adsorption unit. And a heat insulating part made of a bulk body or a porous body having a lower thermal conductivity than the metal base part is disposed between the cooling part and the first heater part .

Further, as described above, in the electrostatic chuck, the heat insulating portion having a lower thermal conductivity than the metal base portion is disposed between the cooling portion and the first heater portion.
For this reason, when, for example, a semiconductor wafer is heated via the electrostatic chuck, the transfer of heat from the first heater unit to the cooling unit can be suppressed, and the first heater unit can efficiently generate heat. Thereby, for example, a semiconductor wafer can be heated rapidly, and the temperature rise characteristic can be enhanced.
And, for example, when controlling the semiconductor wafer to a different temperature in a process such as dry etching on the semiconductor wafer, for example, the temperature control of the semiconductor wafer can be easily performed even when the temperature difference to be controlled is large. . That is, it becomes possible to make a difference in the temperature to be controlled.
As described above, according to the present invention, it is possible to locally adjust the temperature of an object to be adsorbed while achieving uniform temperature of the object to be adsorbed, and to provide an electrostatic chuck having excellent temperature rise characteristics. it can.
In the electrostatic chuck, the thermal conductivity of each of the metal base portion and the ceramic suction portion indicates the thermal conductivity of a material mainly constituting the metal base portion and the ceramic suction portion.
Further, the heat insulating part may be configured to have an outer diameter larger than that of the first heater part in a direction orthogonal to the stacking direction.
Moreover, the said heat insulation part may consist of the same material as the said metal base part, and may be comprised so that a porosity may be higher than the said metal base part.

Claims (4)

A metal base,
A ceramic adsorbing portion disposed on the metal base portion, having an adsorbing electrode for adsorbing an object to be adsorbed by electrostatic attraction, and having a lower thermal conductivity than the metal base portion;
The metal base portion includes a cooling portion having a refrigerant flow path for circulating a refrigerant, and a first portion disposed closer to the ceramic adsorption portion than the cooling portion in the stacking direction of the metal base portion and the ceramic adsorption portion. Heater part is provided,
2. The electrostatic chuck according to claim 1, wherein the ceramic suction portion is provided with a second heater portion configured to be capable of adjusting temperatures of a plurality of regions formed in the ceramic suction portion.   The first heater unit is configured to generate heat, and after the first heater unit reaches a predetermined temperature, the second heater unit is configured to generate heat. The electrostatic chuck according to claim 1, wherein the amount of electric power to be generated is different.   The power amount input when the first heater unit generates heat is configured to be larger than the power amount input when the second heater unit generates heat. Electrostatic chuck.   The power amount input when the first heater unit generates heat is configured to be smaller than the amount of power input when the second heater unit generates heat. Electrostatic chuck.

Images