CN117558674A - Plasma processing device, electrostatic chuck and temperature adjustment method thereof - Google Patents
Plasma processing device, electrostatic chuck and temperature adjustment method thereof Download PDFInfo
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- CN117558674A CN117558674A CN202210939078.4A CN202210939078A CN117558674A CN 117558674 A CN117558674 A CN 117558674A CN 202210939078 A CN202210939078 A CN 202210939078A CN 117558674 A CN117558674 A CN 117558674A
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- H10P72/72—
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/32715—Workpiece holder
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/32715—Workpiece holder
- H01J37/32724—Temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32917—Plasma diagnostics
- H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge
- H01J37/32954—Electron temperature measurement
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- H10P72/0434—
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- H10P72/722—
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Abstract
本发明提供一种静电吸盘，包含：基座，其内部设有至少两路冷却流体通道，至少两路冷却流体通道之间互不连通且分别连通不同的冷却流体源，且相邻的冷却流体通道之间进行热传递；介电层，设置在所述基座上，所述介电层内部设有用于产生吸附力的电极，以吸附承载于介电层上方的晶圆。本发明还提供一种等离子体处理装置和一种静电吸盘的温度调节方法。通过本发明无需在反应腔和冷却流体源之间额外设置温度切换装置或冷却液混合箱，即可实现按区域对静电吸盘进行变温控制。
The invention provides an electrostatic chuck, which includes: a base, at least two cooling fluid channels are provided inside the base, the at least two cooling fluid channels are not connected to each other and are connected to different cooling fluid sources respectively, and adjacent cooling fluid channels Heat is transferred between the channels; a dielectric layer is provided on the base, and an electrode for generating adsorption force is provided inside the dielectric layer to adsorb the wafer carried above the dielectric layer. The invention also provides a plasma processing device and a temperature adjustment method of an electrostatic chuck. Through the present invention, there is no need to install an additional temperature switching device or a cooling liquid mixing box between the reaction chamber and the cooling fluid source, so that the temperature of the electrostatic chuck can be controlled by region.
Description
Technical Field
The present invention relates to the field of semiconductor manufacturing, and more particularly, to a plasma processing apparatus, an electrostatic chuck, and a temperature adjustment method thereof.
Background
In the field of semiconductor manufacturing technology, it is often necessary to perform plasma processing on a wafer to be processed in a plasma processing apparatus. The plasma processing apparatus has a vacuum reaction chamber that includes an electrostatic chuck (Electrostatic chuck, ESC) for providing electrostatic clamping to a wafer during processing.
In semiconductor processing, it is important to control the surface temperature of a wafer in order to ensure the process effect of wafer processing. The heat dissipation of the back surface of the wafer can be improved to enable the local high temperature of the wafer to be immediately dissipated, so that the surface temperature of the wafer can be ensured to meet the process requirement. The method relies on the electrostatic chuck to conduct heat to the wafer. The metal base of the electrostatic chuck is internally provided with a cooling fluid channel communicated with an external refrigerator, and the heat conducted to the base by the wafer is conducted away by cooling liquid flowing in the cooling fluid channel so as to control the temperature of the base and control the temperature of the wafer.
Different process steps often require different temperatures for the susceptor; even for different stages of the same process, the susceptor temperature needs to be changed. For the temperature change requirement of the electrostatic chuck under high temperature change power, two solutions are commonly used in the industry: in the first scheme, a cooling liquid storage tank (tank) communicated with a cooling fluid channel is switched and controlled through a temperature switching device, but a complicated valve and a switching pipeline are required to be designed in the temperature switching device, so that the cost is high. The second scheme is that after the cooling liquid from different liquid storage tanks is premixed to a set temperature by a cooling liquid mixing tank, the cooling liquid is provided for a cooling fluid channel in the base; this solution also requires the addition of additional devices and is less efficient.
In some cases it may also be desirable to vary the susceptor temperature by region to achieve zone-wise adjustment of the wafer surface temperature. How to simply and effectively control the temperature change of each area of the base and improve the processing yield and efficiency of the wafer is a general concern in the industry.
Disclosure of Invention
The invention aims to provide a plasma processing device, an electrostatic chuck and a temperature regulation method thereof, wherein a temperature switching device or a cooling liquid mixing box is not required to be additionally arranged between a reaction cavity and a cooling fluid source, and a plurality of paths of cooling fluid channels communicated with different cooling fluid sources realize temperature change control of the electrostatic chuck through heat transfer in the electrostatic chuck.
In order to achieve the above object, the present invention provides an electrostatic chuck comprising:
the base is internally provided with at least two paths of cooling fluid channels, the at least two paths of cooling fluid channels are not communicated with each other and are respectively communicated with different cooling fluid sources, and heat transfer is carried out between the adjacent cooling fluid channels;
the dielectric layer is arranged on the base, and an electrode for generating adsorption force is arranged in the dielectric layer so as to adsorb the wafer borne on the dielectric layer.
Optionally, the at least two cooling fluid channels are located at the same horizontal plane; the cooling fluid channels are of mosquito-repellent incense type coiling structures, and at least two paths of cooling fluid channels are coiled along the radial direction of the base.
Optionally, the at least two cooling fluid channels are located on the same horizontal plane and are all annular channels with the same central axis as the base.
Optionally, the at least two cooling fluid channels are arranged at intervals in the vertical direction, and the projection parts of any two adjacent cooling fluid channels in the at least two cooling fluid channels on the surface of the base are overlapped.
Optionally, the at least two cooling fluid channels are spirally wound around the central axis of the base from top to bottom or from bottom to top.
Optionally, the base is virtually divided into a plurality of base partitions; each of the susceptor sections may be provided with multiple cooling fluid passages for zone-wise adjustment of the temperature of the susceptor.
Optionally, the plurality of base partitions are a plurality of concentric annular regions, and the center of the concentric annular regions coincides with the center of the base; each annular region contains the at least two cooling fluid passages.
Optionally, the number of cooling fluid passages within the plurality of base partitions is the same or different.
Optionally, a plurality of heating elements are disposed within the dielectric layer.
Optionally, a cooling gas channel is further provided inside the electrostatic chuck for delivering cooling gas to the gap between the wafer and the dielectric layer.
Optionally, a plasma corrosion resistant coating is provided on the outer sidewall of the base.
The present invention also provides a plasma processing apparatus comprising:
a reaction chamber;
the electrostatic chuck is arranged at the bottom of the reaction cavity and is used for bearing a wafer.
Optionally, the plasma processing apparatus is an inductively coupled plasma processing apparatus, further comprising:
the lining is arranged inside the reaction cavity and used for protecting the inner wall of the reaction cavity from being corroded by plasma;
the insulating window is arranged at the top of the reaction cavity; a reaction gas injection port is arranged at one end of the side wall of the reaction cavity, which is close to the insulation window;
the inductance coupling coils are arranged above the insulation window and connected with a radio frequency source; the inductive coupling coil generates an inductive magnetic field under the excitation of the radio frequency source, and the reaction gas in the reaction cavity generates plasma under the action of the inductive magnetic field.
Optionally, the plasma processing apparatus is a capacitively coupled plasma processing apparatus, further comprising:
the gas spray head is arranged above the reaction cavity and opposite to the electrostatic chuck and is used for conveying reaction gas into the reaction cavity; the gas spray header is used as an upper electrode of the reaction cavity; the base of the electrostatic chuck is used as a lower electrode of the reaction cavity; at least one RF source is applied to the upper electrode or the lower electrode, and an RF electric field is generated between the upper electrode and the lower electrode to dissociate the reactive gas into plasma.
Optionally, the plasma processing apparatus further includes:
a plurality of first flow regulating valves and a plurality of second flow regulating valves; the liquid inlet and the liquid outlet of each cooling fluid channel are respectively provided with a first flow regulating valve and a second flow regulating valve so as to control the flow of the cooling liquid flowing into the cooling fluid channel and flowing out of the cooling fluid channel;
a plurality of first temperature sensors and a plurality of second temperature sensors; the liquid inlet and the liquid outlet of each cooling fluid channel are respectively provided with a first temperature sensor and a second temperature sensor so as to detect the temperature of the cooling liquid corresponding to the liquid inlet and the liquid outlet;
and a controller configured to adjust the valve opening degree of the corresponding first and/or second flow rate adjustment valve based on the target temperature value of the second temperature sensor, the temperature value detected by the second temperature sensor, and the temperature value detected by the corresponding first temperature sensor.
Optionally, the plasma processing apparatus further comprises a plurality of third temperature sensors disposed in the susceptor for measuring temperatures of the plurality of susceptor sections, respectively; the controller adjusts the valve opening corresponding to the first and/or second flow regulating valve based on the target temperature value of the base partition and the temperature value detected by the corresponding third temperature sensor, so as to realize the adjustment of the base temperature according to the area.
Optionally, the controller controls the valve opening of the first and/or second flow regulating valve by using a proportional-integral-derivative regulating method.
Optionally, the plasma processing apparatus further comprises a heating power source and a fourth temperature sensor; the heating power source is electrically connected with the heating element in the dielectric layer and is used for providing heating electric energy for the heating element; the fourth temperature sensor is used for detecting the temperature of the dielectric layer; the controller also adjusts one or more of the output power and the working time of the heating power source based on the target temperature value of the dielectric layer and the temperature value detected by the fourth temperature sensor.
Optionally, the plasma processing apparatus further comprises a cooling gas pump; a cooling gas channel inside the electrostatic chuck is communicated with a cooling gas source through the cooling gas pump; the controller also adjusts the power of the cooling gas pump based on the target temperature value of the dielectric layer, the temperature value detected by the fourth temperature sensor.
Optionally, the first temperature sensor and the second temperature sensor are integrated on the corresponding first flow regulating valve and second flow regulating valve.
The invention also provides a temperature adjusting method of the electrostatic chuck, which is used for the plasma processing device, and comprises the following steps: and conveying cooling fluid of different cooling fluid sources into corresponding cooling fluid channels in the base, and realizing temperature adjustment of the base through heat transfer of the cooling fluid in the different cooling fluid channels in the base.
Optionally, the method for adjusting the temperature of the electrostatic chuck includes the steps of:
the first temperature sensor and the second temperature sensor respectively detect the temperature of the cooling liquid corresponding to the liquid inlet and the liquid outlet;
the controller adjusts the valve opening degree of the corresponding first and/or second flow rate regulating valve based on the target temperature value of the second temperature sensor, the temperature value detected by the first temperature sensor, and the temperature value detected by the second temperature sensor.
Optionally, the method for adjusting the temperature of the electrostatic chuck further comprises the steps of:
the plurality of third temperature sensors respectively detect temperatures of the plurality of base partitions;
the controller adjusts the valve opening corresponding to the first and/or second flow regulating valve based on the target temperature value of the base partition and the temperature value detected by the corresponding third temperature sensor, so as to realize the adjustment of the base temperature according to the area.
Optionally, the method for adjusting the temperature of the electrostatic chuck further comprises the steps of:
a fourth temperature sensor detects the temperature of the dielectric layer;
the controller adjusts one or more of the output power and the operating time of the heating power source based on the target temperature value of the dielectric layer and the temperature value detected by the fourth temperature sensor.
Optionally, the method for adjusting the temperature of the electrostatic chuck further comprises the steps of:
The controller also adjusts the power of the cooling gas pump based on the target temperature value of the dielectric layer, the temperature value detected by the fourth temperature sensor.
Compared with the prior art, the plasma processing device, the electrostatic chuck and the temperature adjusting method thereof have the beneficial effects that:
1) According to the invention, the temperature change control can be rapidly and accurately performed on the electrostatic chuck without additionally arranging a temperature switching device or a cooling liquid mixing box between the plasma processing device and an external cooling liquid source, so that the wafer temperature can be accurately adjusted in real time according to the process progress, and the process effect of wafer processing is ensured; the invention greatly reduces the cost of wafer processing because of no need of a temperature switching device; the cooling liquid of each path does not need to be premixed in the mixing box, and the temperature regulation speed of the electrostatic chuck and the processing efficiency of the wafer are greatly improved;
2) The invention arranges a plurality of cooling fluid channels according to the areas and independently controls each cooling fluid channel of each area, thus the invention can realize controlling the temperature of the electrostatic chuck according to the areas so as to adjust the etching rate of the wafer according to the areas and ensure the processing precision of the wafer;
3) According to the invention, complicated valves and pipelines are not needed, and the multi-gear temperature adjustment of each region of the electrostatic chuck is realized by controlling the opening/closing of the corresponding first flow adjusting valve and the second flow adjusting valve; stepless temperature regulation of each region of the electrostatic chuck is realized by controlling the valve opening degree of the corresponding first and/or second flow regulating valve; the temperature adjusting method has simple steps and is easy to realize;
4) The temperature regulation method adopts proportional-integral-derivative (PID) regulation, has good adaptability, rapid reaction in the control process, and easy acquisition and mutual independence of control parameters;
5) The invention further improves the temperature regulation efficiency of the electrostatic chuck by controlling the heating power of the heating power source and the power of the cooling gas pump.
Drawings
For a clearer description of the technical solutions of the present invention, the drawings that are needed in the description will be briefly introduced below, it being obvious that the drawings in the following description are one embodiment of the present invention, and that, without inventive effort, other drawings can be obtained by those skilled in the art from these drawings:
FIG. 1 is a schematic view of an electrostatic chuck;
FIG. 2 is a schematic diagram of a refrigerator in fluid communication with a plasma processing apparatus through a temperature switching device;
FIG. 3 is a schematic illustration of a refrigerator in fluid communication with a plasma processing apparatus through a coolant mixing tank;
FIG. 4 is a schematic view of a plasma processing apparatus according to the present invention;
FIG. 5 is an enlarged view of the electrostatic chuck of FIG. 4;
FIG. 6 is a view a-a of FIG. 5;
FIG. 7 is a schematic view of another electrostatic chuck according to the present invention;
FIG. 8 is a schematic view of an electrostatic chuck in accordance with another embodiment of the present invention;
FIG. 9 is a schematic diagram of an electrostatic chuck according to a second embodiment of the present invention;
FIG. 10 is a view b-b of FIG. 9 in accordance with the present invention;
FIG. 11 is a schematic view of an electrostatic chuck in accordance with another embodiment of the present invention;
FIG. 12 is a schematic view of an electrostatic chuck in accordance with a third embodiment of the present invention;
fig. 13 is a schematic view of an electrostatic chuck according to a fourth embodiment of the present invention;
FIG. 14 is a schematic view of a plasma processing apparatus according to a fifth embodiment of the present invention;
FIG. 15 is a schematic diagram showing the steps of a method for adjusting the temperature of an electrostatic chuck according to one embodiment of the present invention;
FIG. 16 is a schematic diagram showing the steps of a method for adjusting the temperature of an electrostatic chuck according to another embodiment of the present invention;
FIG. 17 is a schematic diagram showing the steps of a method for adjusting the temperature of an electrostatic chuck according to another embodiment of the present invention;
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In semiconductor processing, wafers are typically processed within a reaction chamber of a plasma processing apparatus. The etching and deposition rates of different material layers have different sensitivity to temperature. Different process steps often require different wafer temperatures, and even different stages of the same process step require changing the wafer temperature. Wafer temperature is one of the key parameters affecting process performance. Taking an etching process as an example, the sensitivity of a material layer to temperature is often utilized in the process to keep the wafer at a set temperature, so as to adjust the etching selection ratio of the current material layer to the next material layer, thereby increasing the process window for interface etching and controlling the process index (such as critical dimension Critical Dimension, CD). For some wafers of complex structure, different interfaces may occur, as well as different temperature requirements for each processing stage. For example, in the photoresist mask etching (mask open) stage, a relatively low temperature is needed to prevent the opening from being oversized; in the over etch (over etch) stage, it is necessary to increase the selectivity to the stop layer (landing layer) with high temperature while controlling the bottom critical dimension.
The electrostatic suction is generally generated by an electrostatic chuck in the reaction chamber to support and hold the wafer to be processed during the process. The wafer is fixed by an electrostatic chuck, and comprises: the electrostatic suction force is uniformly distributed, the electrostatic suction force is continuous and stable, the wafer cannot warp and deform, the wafer is not damaged, and the like.
As shown in fig. 1, the electrostatic chuck comprises a base 110 (typically a metallic material such as aluminum) made of a thermally conductive material, the interior of the base 110 typically being provided with a cooling fluid passage 111 in communication with an external cooling fluid source. The heat transferred from the wafer W to the susceptor 110 is conducted away by the cooling fluid in the cooling fluid passage to adjust the wafer temperature.
For the temperature change requirement of the electrostatic chuck under high temperature change power, two solutions are commonly used in the industry: as shown in fig. 2, at least two cooling liquid storage tanks 121 capable of setting temperature independently are provided at the end of the refrigerator 120, and each cooling liquid storage tank 121 is communicated with a cooling fluid channel 111 in the base 110 (located in the reaction chamber of the plasma processing apparatus 10) through a corresponding cooling liquid pipeline 122. A temperature switching device 130 is also added between the plasma processing apparatus 10 and the refrigerator 120. The cooling liquid pipeline 122 communicated with the cooling liquid channel 111 is switched and controlled by the temperature switching device 130, when the electrostatic chuck in the plasma processing device 10 needs to be heated, the electrostatic chuck is communicated to the cooling liquid storage tank 121 with high temperature; when the electrostatic chuck needs to be cooled, the electrostatic chuck is connected to the low temperature tank 121. This solution requires an additional temperature switching device 130, and the interior of the temperature switching device 130 requires complicated valve and switching pipeline design, which is costly. As shown in fig. 3, a cooling liquid mixing tank 140 is provided between the refrigerator 120 and the plasma processing apparatus 10, and the cooling liquid from the different liquid tanks 121 is mixed to a set temperature in the cooling liquid mixing tank 140 and then supplied to the cooling fluid passage 111 in the susceptor 110. This solution also requires the addition of additional devices and is less efficient.
It would be desirable to be able to simply control the communication/disconnection between the cooling fluid channel 111 and the corresponding cooling fluid reservoir 121 and to eliminate the premixing step prior to the cooling fluid entering the cooling fluid channel 111 to achieve a rapid and accurate adjustment of the temperature of the electrostatic chuck per region; meanwhile, the stepless temperature regulation and the multi-gear temperature regulation of the electrostatic chuck are also expected. When stepless temperature regulation is performed, the temperature curve of the electrostatic chuck changes smoothly, and the method is particularly suitable for the situation that the temperature regulation range of the electrostatic chuck is smaller. When the temperature of the electrostatic chuck is regulated in multiple gears, the temperature curve of the electrostatic chuck usually shows step change, and when the temperature change is large, the temperature of the electrostatic chuck is quickly regulated.
Example 1
The invention provides a plasma processing apparatus. As shown in fig. 4, the plasma processing apparatus in this embodiment is a capacitively coupled plasma (capacitively coupled plasma CCP) processing apparatus, which includes a vacuum chamber 200, a plurality of first flow rate adjusting valves 231, a plurality of second flow rate adjusting valves 232, a plurality of temperature sensors, and a controller (not shown).
As shown in fig. 4, the reaction chamber 200 includes a substantially cylindrical reaction chamber sidewall 201 made of a metal material, and an opening 202 is provided in the reaction chamber sidewall 201 for receiving the wafer W therein and therein. The bottom of the vacuum reaction chamber is provided with an electrostatic chuck (comprising a pedestal 210 and a dielectric layer 212) according to the present invention, through which a wafer W to be processed is carried. The gas shower head 213 is disposed above the reaction chamber and opposite to the electrostatic chuck, and is used for supplying a reaction gas into the reaction chamber. The gas spray header 213 is used as an upper electrode of the reaction chamber; the base 210 of the electrostatic chuck serves as a lower electrode of the reaction chamber; a reaction region is formed between the upper electrode and the lower electrode. At least one rf source 240 is applied to the upper electrode or the lower electrode, generating an rf electric field between the upper electrode and the lower electrode to dissociate the reactant gas into plasma. The plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules, free radicals and the like, and the active particles can react with the surface of the wafer W to be processed in various physical and chemical ways, so that the appearance of the surface of the wafer is changed, and the etching process is completed. An exhaust pump 250 is also disposed below the vacuum reaction chamber 201 for exhausting the reaction byproducts out of the reaction chamber to maintain the vacuum environment of the reaction chamber.
As shown in fig. 4, the dielectric layer 212 (typically made of ceramic) is disposed on the base 210, and a dc voltage is applied to the electrode 214 inside the dielectric layer to generate electrostatic attraction force on the electrostatic chuck, so as to attract the wafer W carried on the dielectric layer. Inside the dielectric layer, a plurality of heating elements 215 for heating the dielectric layer 212 are provided, and heat energy is radiated to the wafer W through the dielectric layer 212. The heating power source 241 is electrically connected to the heating element 215, and is configured to provide heating power to the heating element 215.
As shown in fig. 4, the base 210 is typically made of a heat conductive material (e.g., aluminum), and the outer sidewall of the base 210 is typically provided with a coating film that resists plasma corrosion. Inside the base is provided a multi-way cooling fluid channel 211 (two cooling fluid channels 211a and 211b are shown in fig. 4), said multi-way cooling fluid channel 211. Respectively, to communicate with different sources of cooling fluid (the reservoir 221 in fig. 4). Any two paths of cooling fluid channels 211 are not communicated with each other, and heat transfer can be performed between adjacent cooling fluid channels 211. The cooling fluid in the different cooling fluid channels is heat transferred within the base to condition the base 210. The multiple cooling fluid channels 211 are located at the same level or are spaced apart in the vertical direction.
Fig. 5 is an enlarged view of the electrostatic chuck of fig. 4, and fig. 6 is a-a view of fig. 5. In this embodiment, as shown in fig. 4, 5, and 6, the cooling fluid passages 211a and 211b are located on the same horizontal plane. As shown in fig. 6, the cooling fluid channels 211a and 211b are commonly coiled in the radial direction of the base, forming a mosquito coil type coil structure. The distance between the cooling fluid passages 211a, 211b is 0.1mm to 0.3mm in the radial direction of the base 210.
When the interval between two adjacent cooling fluid channels 211 is greater than 0.3mm, the heat transfer effect between them is poor, which is not beneficial to the temperature control of the electrostatic chuck. In the present embodiment, since the space between the adjacent cooling fluid passages 211 (the cooling fluid passage 211a and the cooling fluid passage 211 b) is small, heat transfer can be performed efficiently. By heat transfer between adjacent cooling fluid channels 211, "mixing" of the cooling fluid of different cooling fluid sources inside the susceptor is achieved. Thus eliminating the need to pre-mix multiple temperature cooling fluids in the cooling fluid mixing tank before the cooling fluid enters the cooling fluid channel 211 in the base. Therefore, the invention not only reduces the cost of wafer processing, but also greatly improves the temperature regulation speed of the electrostatic chuck and the wafer processing efficiency.
When the spacing between the adjacent cooling fluid channels 211 is smaller than 0.1mm, the difficulty in manufacturing the base 210 is increased, and the mechanical strength between the adjacent cooling fluid channels 211 is low, so that the pressure of the cooling fluid on the inner wall of the cooling fluid channel can damage the cooling fluid channel 211 to cause leakage.
In another embodiment, the multiple cooling fluid channels are located in the same horizontal plane and are all annular channels concentric with the base. In FIG. 7, 3 annular cooling fluid passages 311 a-311 c are shown concentric with the base 310. The distance between the cooling fluid channels 311a and 311b and between the cooling fluid channels 311b and 311c is 0.1mm to 0.3mm in the radial direction of the susceptor. The spacing can ensure both thermal conductivity and mechanical strength between adjacent cooling fluid channels. The number of cooling fluid passages in fig. 7 is by way of example only and not by way of limitation of the present invention.
In another embodiment, as shown in fig. 8, the inside of the base 410 is provided with cooling fluid channels 411a and cooling fluid channels 411b at intervals in the vertical direction, which are located on different planes. The projections of cooling fluid channel 411a and cooling fluid channel 411b on the base surface at least partially overlap, which enables interaction between cooling fluid channel 411a and cooling fluid channel 411b, facilitating heat transfer. In the vertical direction, the distance between the cooling fluid channel 411a and the cooling fluid channel 411b is 0.1mm to 0.3mm, and the meaning of setting the distance is similar to that described above, and the description thereof will be omitted. The number of cooling fluid passages in fig. 8 is by way of example only and not by way of limitation of the present invention.
In another embodiment, two cooling fluid channels for heat transfer are provided in the base, and the two cooling fluid channels spiral up and jointly coil the central axis of the base.
As shown in fig. 4, the liquid inlet 261 and the liquid outlet 262 of the different cooling fluid channels 211 are respectively provided with one of the first flow rate adjusting valve 231 and one of the second flow rate adjusting valves 232. The valve opening of the first flow rate adjusting valve 231 and the second flow rate adjusting valve 232 are controlled by a controller to control the flow rate of the cooling liquid flowing into the cooling fluid channel 211 and flowing out of the cooling fluid channel 211, thereby realizing adjustment of the electrostatic chuck temperature. When the preset working temperature of the electrostatic chuck is lower, the valve opening of the first flow adjusting valve 231 and the second flow adjusting valve 232 corresponding to at least one path of cooling fluid channel 211 can be increased, so that the cooling fluid flowing through the corresponding cooling fluid channel 211 is increased, and the more heat is taken away by the cooling fluid, the lower preset working temperature of the electrostatic chuck can be achieved. Conversely, when the preset operating temperature of the electrostatic chuck is higher, the valve opening of the first flow adjusting valve 231 and the second flow adjusting valve 232 corresponding to the at least one cooling fluid channel 211 can be reduced, so that the cooling fluid flowing through the corresponding cooling fluid channel 211 is reduced, and the more heat is taken away by the cooling fluid, the higher preset operating temperature of the electrostatic chuck is facilitated. Meanwhile, the controller can also control on and off between the cooling fluid source (the tank 221) and the corresponding cooling fluid channel 211.
The plurality of temperature sensors includes a plurality of first temperature sensors and a plurality of second temperature sensors. The liquid inlet 261 and the liquid outlet 262 of the cooling fluid channel 211 are respectively provided with a first temperature sensor and a second temperature sensor to respectively detect the temperature of the cooling liquid corresponding to the liquid inlet 261 and the liquid outlet 262. In this embodiment, the first temperature sensor and the second temperature sensor are integrated on the corresponding first flow rate adjustment valve 231 and second flow rate adjustment valve 232. The controller is configured to adjust the valve opening degree of the corresponding first flow rate adjustment valve 231 and/or the second flow rate adjustment valve 232 based on the target temperature value of the second temperature sensor, the temperature value detected by the second temperature sensor, and the temperature value detected by the corresponding first temperature sensor.
There is a need in the art to provide a temperature switching device between a plurality of cooling fluid sources and a plasma processing apparatus to select a cooling fluid source communicating with a cooling fluid channel from among the plurality of cooling fluid sources and to control the flow rate of the cooling fluid flowing into the cooling fluid channel through complicated valves and switching lines inside the temperature switching device. In the invention, the controller independently controls the cooling fluid channels 211 through the corresponding first flow regulating valve 231 and the second flow regulating valve 232, and the cooling fluid channels 211 are not interfered with each other. According to the invention, the cooling fluid channels 211 are independently controlled to be communicated or not communicated with corresponding cooling fluid sources, and the flow of the cooling fluid of each cooling fluid channel 211 is independently controlled, so that the temperature of the cooling fluid of different cooling fluid sources after 'mixing' in the base is changed, and finally the temperature of the electrostatic chuck is adjusted. Therefore, the invention does not need a temperature switching device and a cooling liquid mixing box, further saves the processing cost of the wafer, and simplifies the control operation of the cooling fluid channel 211.
On the other hand, the invention can control the constant temperature, stepless temperature change and multi-gear temperature change of the electrostatic chuck by independently controlling the cooling fluid channel 211, thereby meeting the requirements of actual processes.
In this embodiment, as shown in fig. 5, the liquid inlet 261a and the liquid outlet 262a of the cooling fluid channel 211a are respectively provided with a first flow rate adjustment valve 231a and a second flow rate adjustment valve 232a integrated with temperature sensors. The liquid inlet 261b and the liquid outlet 262b of the cooling fluid passage 211b are provided with a first flow rate adjustment valve 231b and a second flow rate adjustment valve 232b, respectively, to which temperature sensors are integrated. The target temperatures of the second flow rate adjustment valve 232a and the second flow rate adjustment valve 232b are T1 and T2, respectively (T1 and T2 may be the same or different). The actual temperatures detected by the first and second flow rate adjustment valves 231a, 232a are denoted as T1-in, T1-out, respectively. The actual temperatures detected by the first and second flow rate adjustment valves 231b, 232b are denoted as T2-in, T2-out, respectively. The flow rates measured by the first flow rate adjustment valve 231a and the second flow rate adjustment valve 231b are L1 and L2, respectively.
During a certain process, the electrostatic chuck is kept at a constant temperature, T1 may be equal to T2. At this time, the controller operates in a constant temperature mode to ensure that the susceptor is maintained at a set temperature. For example, the controller may adjust the valve opening of the first flow rate adjustment valve 231a and/or the second flow rate adjustment valve 232a based on T1, T1-in, T1-out using a proportional-integral-derivative (PID) adjustment method; the controller also adjusts the valve opening of the first flow rate adjustment valve 231b and/or the second flow rate adjustment valve 232b based on T2, T2-in, T2-out. Wherein T1-out, T2-out are provided as feedback signals to the controller.
According to the process requirement, the controller can steplessly change the temperature of the electrostatic chuck, and is particularly suitable for the situation that the temperature adjustment precision of the electrostatic chuck is high. For example, in the previous process, the temperature of the electrostatic chuck needs to be maintained at 14 ℃ to 15 ℃, the target temperature T1 of the second flow rate adjustment valve 232a of the cooling fluid channel 211a is set at 10 ℃, and the target temperature T2 of the second flow rate adjustment valve 232b of the cooling fluid channel 211b is set at 20 ℃. The first flow rate adjustment valve 231a and the first flow rate adjustment valve 231b are both opened. In the current process, the temperature of the electrostatic chuck needs to be maintained at 16 ℃ to 17 ℃. At this time, the first flow rate adjustment valve 231a, 231b are still open, and the electrostatic chuck temperature may be adjusted in a variety of ways:
1) The second flow rate adjustment valve 232a of the cooling fluid passage 211a is adjusted to 13 ℃ at the target temperature T1, and the valve opening degree of the first flow rate adjustment valve 231a and/or the second flow rate adjustment valve 232a is adjusted based on the target temperature T1.
2) The second flow rate adjustment valve 232b of the cooling fluid passage 211b is adjusted to the target temperature T2 of 23 ℃, and the valve opening degree of the first flow rate adjustment valve 231b and/or the second flow rate adjustment valve 232b is adjusted based on the target temperature T2.
3) The second flow rate adjustment valve 232a target temperature T1 of the cooling fluid passage 211a is adjusted to 12 ℃, and the second flow rate adjustment valve 232b target temperature T2 of the cooling fluid passage 211b is adjusted to 22 ℃; the valve opening degree of the first flow rate adjustment valve 231a and/or the second flow rate adjustment valve 232a is adjusted based on the target temperature T1, and the valve opening degree of the first flow rate adjustment valve 231b and/or the second flow rate adjustment valve 232b is adjusted based on the target temperature T2.
The controller can also change the temperature of the electrostatic chuck at multiple gears, so that the temperature of the electrostatic chuck can be quickly adjusted to the target temperature. The second flow rate adjustment valve 232a target temperature T1 of the cooling fluid passage 211a is set to 5 ℃, and the second flow rate adjustment valve 232b target temperature T2 of the cooling fluid passage 211b is set to 30 ℃. It is assumed that the temperature of the electrostatic chuck needs to be maintained at 5 c to 8 c in the current process, and the temperature of the electrostatic chuck needs to be maintained at 30 c to 40 c in the next process. Then in the current process, the first flow rate adjustment valve 231a is opened and the first flow rate adjustment valve 231b is closed (l2=0); in the next process, the first flow rate adjustment valve 231a (l1=0) is closed, and the first flow rate adjustment valve 231b is opened. Thus, the temperature of the electrostatic chuck can be simply and quickly switched between multiple gears.
Example two
In this embodiment, the susceptor is virtually divided into a plurality of susceptor sections, each of which may be provided with multiple cooling fluid passages for adjusting the temperature of the susceptor by region. The number of cooling fluid passages within the plurality of base partitions may be the same or different.
In this embodiment, as shown in fig. 9 and 10, the base 510 includes: a central region a (disk-shaped) and an edge region C (annular) surrounding the central region a. The area outside the virtual circle in fig. 10 is the center area a, and the area inside the virtual circle is the edge area C. In fig. 9 and 10, the center region a is provided with a cooling fluid passage 511a and a cooling fluid passage 511b, between which heat is transferred. The cooling fluid passage 511a and the cooling fluid passage 511b are wound around the central axis of the base together in the radial direction of the base 510 to form a mosquito coil type coil structure. The edge region C is also provided with cooling fluid channels 511C and 511d, between which heat transfer takes place. The cooling fluid passage 511c and the cooling fluid passage 511d are wound together in the radial direction of the susceptor and surround the outer circumferences of the cooling fluid passage 511a and the cooling fluid passage 511 b.
In another embodiment, as shown in fig. 11, the base 610 includes: a central area a ' (disc-shaped, located inside the small virtual circle in fig. 11), a middle area B ' (circular ring-shaped, located between the small virtual circle and the large virtual circle in fig. 11), and an edge area C ' (circular ring-shaped, located outside the large virtual circle in fig. 11), which surround the central area a ', the middle area B ' being located between the central area a ' and the edge area C '. A plurality of annular cooling fluid passages 611 concentric with the base 610 are provided in each annular region, and heat transfer occurs between adjacent cooling fluid passages 611.
In this embodiment, the electrostatic chuck further comprises a plurality of third temperature sensors 550 disposed in the susceptor for measuring the temperatures of the plurality of susceptor sections, respectively, as shown in fig. 9. The controller adjusts the valve opening of the first flow rate adjustment valve 531 and/or the second flow rate adjustment valve 532 corresponding to the base partition based on the target temperature value of the base partition and the temperature value detected by the corresponding third temperature sensor.
According to the invention, the plurality of cooling fluid channels are arranged according to the areas, and the cooling fluid channels of each area are independently controlled, so that the temperature of the electrostatic chuck can be controlled according to the areas, the etching rate of the wafer can be adjusted according to the areas, and the processing precision of the wafer can be ensured.
Example III
The electrostatic chuck in this embodiment also includes a fourth temperature sensor 760. A fourth temperature sensor 760 as depicted in fig. 12 is disposed within the dielectric layer 712 for detecting the temperature of the dielectric layer 712. In this embodiment, the controller further adjusts one or more of the output power and the operating time of the heating power source 741 based on the target temperature value of the dielectric layer 712 and the temperature value detected by the fourth temperature sensor 760.
When the temperature detected by the fourth temperature sensor 760 is higher than the target temperature value of the dielectric layer 712, the controller decreases the output power of the heating power source 741 (or turns off the heating power source 741, stops the output of the heating power to the heating element 715), and may also increase the valve opening of the corresponding first flow rate adjustment valve 731 and/or second flow rate adjustment valve 732. When the temperature detected by the fourth temperature sensor 760 is lower than the target temperature value of the dielectric layer 712, the controller increases the output power and/or the heating period of the heating power source 741, and may also decrease the valve opening of the first flow rate adjustment valve 731 and/or the second flow rate adjustment valve 732. The temperature regulation speed and the regulation efficiency of the electrostatic chuck are further improved in the embodiment.
Example IV
As shown in fig. 13, a cooling gas channel 816 is also provided inside the electrostatic chuck for delivering a cooling gas (e.g., helium) to the gap between the wafer W and the dielectric layer 812. Heat from the wafer W can be carried away by heat transfer between the cooling gas and the wafer W.
The plasma processing apparatus in this embodiment further includes a cooling gas pump (not shown in the drawing) through which the cooling gas channel 816 inside the electrostatic chuck communicates with a cooling gas source. The controller also adjusts the power of the cooling gas pump based on the target temperature value of the dielectric layer 812, the temperature value detected by the fourth temperature sensor 860.
When the temperature detected by the fourth temperature sensor 860 is higher than the target temperature value of the dielectric layer 812, the controller increases the power of the cooling gas pump to introduce more cooling gas to the back surface of the wafer, increases the maintenance pressure of the cooling gas to enhance the heat exchange between the wafer and the dielectric layer of the electrostatic chuck, and may also increase the valve opening corresponding to the first flow regulating valve 831 and/or the second flow regulating valve 832. When the temperature detected by the fourth temperature sensor 860 is lower than the target temperature value of the dielectric layer 812, the controller reduces the power of the cooling gas pump to introduce less cooling gas to the backside of the wafer, reduces the maintenance pressure of the wafer backside cooling gas to reduce the heat exchange between the wafer and the dielectric layer of the electrostatic chuck, and may also reduce the valve opening of the first flow regulating valve 831 and/or the second flow regulating valve 832. The temperature regulation speed and the regulation efficiency of the electrostatic chuck are further improved in the embodiment.
Example five
The plasma processing apparatus in this embodiment is an inductively coupled plasma (Inductive Coupled Plasma ICP) processing apparatus, please refer to fig. 14, which includes: a reaction chamber 900, a liner 920, an insulating window 917, a plurality of inductively coupled coils 915, an electrostatic chuck.
The reaction chamber 900 includes a substantially cylindrical reaction chamber sidewall 901 made of a metal material, and the liner 920 is disposed inside the reaction chamber to protect the inner wall of the reaction chamber 900 from plasma. The insulating window 917 is disposed at the top of the reaction chamber 900, and a reaction gas injection port 903 is disposed at one end of the side wall 901 of the reaction chamber close to the insulating window 917. The inductive coupling coil 915 is disposed above the insulating window 917 and is connected to the rf source 918 via the rf matching network 916; the inductive coupling coil 915 generates an inductive magnetic field under the excitation of the radio frequency source 918, and the reaction gas in the reaction chamber generates plasma under the action of the inductive magnetic field.
The electrostatic chuck is arranged at the bottom of the reaction cavity and is used for bearing the wafer W. The electrostatic chuck comprises a base 910 and a dielectric layer 912. The dielectric layer 912 is disposed on the base 910, and an electrode 914 for generating an adsorption force is disposed inside the dielectric layer 912 to adsorb the wafer W carried on the dielectric layer 912. A bias rf power source 950 applies a bias rf voltage to the pedestal 910 for controlling the direction of bombardment of charged particles in the plasma. The base 910 has a plurality of cooling fluid passages 911 which are not connected to each other and are respectively connected to different cooling fluid sources 921, and heat transfer is performed between the adjacent cooling fluid passages 911. The cooling fluids in the different cooling fluid channels 911 are mutually transferred by heat in the base to temperature-regulate the base 910.
The invention also provides a temperature adjusting method of the electrostatic chuck, which is used for the plasma processing device, and comprises the following steps: and conveying cooling fluid of different cooling fluid sources into corresponding cooling fluid channels in the base, and realizing temperature adjustment of the base through heat transfer of the cooling fluid in the different cooling fluid channels in the base.
In one embodiment, as shown in fig. 15, the method for adjusting the temperature of the electrostatic chuck comprises the steps of:
s101, a first temperature sensor and a second temperature sensor respectively detect the temperature of cooling liquid corresponding to a liquid inlet and a liquid outlet;
s102, the controller adjusts the valve opening of the corresponding first and/or second flow regulating valve based on the target temperature value of the second temperature sensor, the temperature value detected by the first temperature sensor and the temperature value detected by the second temperature sensor.
In another embodiment, as shown in fig. 16, the method for adjusting the temperature of the electrostatic chuck includes the steps of:
s201, a first temperature sensor and a second temperature sensor respectively detect the temperature of cooling liquid corresponding to a liquid inlet and a liquid outlet;
s202, the controller adjusts the valve opening of the corresponding first and/or second flow regulating valve based on the target temperature value of the second temperature sensor, the temperature value detected by the first temperature sensor and the temperature value detected by the second temperature sensor;
S203, detecting the temperature of the dielectric layer by a fourth temperature sensor;
and S204, the controller adjusts one or more of the output power of the heating power source, the working time of the heating power source and the power of the cooling gas pump based on the target temperature value of the dielectric layer and the temperature value detected by the fourth temperature sensor.
In another embodiment, as shown in fig. 17, the method for adjusting the temperature of the electrostatic chuck includes the steps of:
s301, a plurality of third temperature sensors respectively detect temperatures of a plurality of base partitions;
s302, the controller adjusts the valve opening degree of the corresponding first and/or second flow regulating valve based on the target temperature value of the base partition and the temperature value detected by the corresponding third temperature sensor, so as to realize the adjustment of the base temperature according to the area.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (25)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210939078.4A CN117558674A (en) | 2022-08-05 | 2022-08-05 | Plasma processing device, electrostatic chuck and temperature adjustment method thereof |
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| CN202210939078.4A CN117558674A (en) | 2022-08-05 | 2022-08-05 | Plasma processing device, electrostatic chuck and temperature adjustment method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN119943738A (en) * | 2025-01-24 | 2025-05-06 | 迈睿捷(南京)半导体科技有限公司 | A novel etching electrostatic chuck, temperature adaptive control device and method |
| WO2025250315A1 (en) * | 2024-05-31 | 2025-12-04 | Applied Materials, Inc. | Ultra-fast temperature switching pedestal |
-
2022
- 2022-08-05 CN CN202210939078.4A patent/CN117558674A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2025250315A1 (en) * | 2024-05-31 | 2025-12-04 | Applied Materials, Inc. | Ultra-fast temperature switching pedestal |
| CN119943738A (en) * | 2025-01-24 | 2025-05-06 | 迈睿捷(南京)半导体科技有限公司 | A novel etching electrostatic chuck, temperature adaptive control device and method |
| CN119943738B (en) * | 2025-01-24 | 2025-09-12 | 迈睿捷(南京)半导体科技有限公司 | Novel etching electrostatic chuck, temperature self-adaptive control device and method |
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