JP4323021B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus in which a cathode electrode that holds at least an object to be processed and an anode electrode facing the cathode electrode are provided in a predetermined container.
[0002]
[Prior art]
Conventionally, a so-called parallel plate type plasma processing apparatus has been widely used as a plasma processing apparatus used for plasma processing such as etching. In this parallel plate type plasma processing apparatus, for example, as described in JP-A-7-307334, a cathode electrode and an anode electrode face each other across a predetermined space (plasma processing space) in a processing vessel. Installed. The cathode electrode is installed in the lower part of the processing container, and an object to be processed is placed on the upper surface thereof. The anode electrode is fixed to the inner surface side of the top plate portion of the processing container.
Here, as a method of fixing the anode electrode to the processing vessel, for example, as described in the above publication, a method of fixing the peripheral portion of the anode electrode with a plurality of bolts has been common. .
[0003]
[Problems to be solved by the invention]
However, when the anode electrode is fixed to the processing vessel with a bolt as described above, most of the heat of the plasma flowing into the anode electrode is released to the outside from the peripheral portion of the anode electrode. There is a problem that a temperature difference occurs between the central part and the peripheral part of the substrate, resulting in non-uniform plasma processing performance or damage of the anode due to thermal stress. In addition, if the tightening force for each bolt is not uniform, the temperature distribution of the anode electrode is further uneven, and the above problem is further increased. In recent years, for example, Si wafers to be processed in the semiconductor device manufacturing industry have been increased in size, and the above problem has become more serious due to the accompanying increase in the size of the anode electrode.
The present invention has been made in view of the above circumstances, and an object of the present invention is to make the plasma processing performance uniform in the plasma processing chamber by equalizing the temperature distribution of the anode electrode, and at the same time inside the anode electrode. It is an object of the present invention to provide a plasma processing apparatus capable of suppressing the generation of thermal stress.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plasma processing apparatus in which a cathode electrode for holding an object to be processed and an anode electrode facing the cathode electrode are provided in a predetermined container. An electrostatic chuck electrode connected to a power source and covered with an insulating layer is attached to a holding member to be fixed, and the anode electrode holds the holding by an electrostatic force obtained by supplying a potential to the electrostatic chuck electrode. It is configured as a plasma processing apparatus characterized by being adsorbed and held by a member.
As a result, a temperature difference due to non-uniform tightening force and heat transfer amount does not occur in the anode electrode, and non-uniform plasma processing performance due to the temperature difference of the anode electrode and damage to the anode due to thermal stress can be prevented.
Further, if a substantially uniform gap is formed between the opposing surfaces of the holding member and the anode electrode, and heat transfer gas is supplied to the gap, the uniformity of the heat transfer efficiency over the entire anode electrode can be improved. This further increases the uniformity of the temperature of the anode electrode, and as a result, further improvement in the uniformity of the plasma treatment can be expected.
At this time, if a sealing means for sealing the periphery of the gap is provided, it is possible to prevent a problem that the heat transfer gas leaks into the plasma processing space and adversely affects the plasma processing.
Further, if the clamp for supporting the peripheral portion of the anode electrode is attached to the holding member, the holding of the anode electrode is further ensured.
When the clamp is installed, it is conceivable that seal members for sealing the gap are provided, for example, between the clamp and the holding member and between the clamp and the anode electrode.
[0005]
Further, if a heating means for directly or indirectly heating the anode electrode is installed on the holding member, it becomes possible to actively control the temperature distribution of the anode electrode, and more reliably the temperature distribution of the anode electrode. Can be made uniform.
At this time, temperature measuring means for directly or indirectly measuring the temperature of the anode electrode is installed on the holding member, and the heating means is controlled by the temperature control means based on the temperature measured by the temperature measuring means. By doing so, it is possible to keep the temperature distribution of the anode electrode always uniform by following the temporal fluctuation of the heat flowing into the anode electrode.
[0006]
Furthermore, an antenna for inductively coupled plasma excitation may be installed inside or above the holding member to provide an anode type ICP device.
At this time, if an RF shield means for partially shielding the RF electric field supplied from the antenna is installed at a predetermined position of the holding member or the anode electrode, the range covered by the RF electric field of each antenna is limited. It is possible to improve the controllability of the spatial distribution of plasma density.
When supplying RF power to the anode electrode, an RF coupling electrode connected to a high frequency RF power source and covered with an insulating layer is attached to the holding member, and the RF coupling electrode is connected to the anode electrode. It is also possible to supply the RF power indirectly. Thereby, since it is not necessary to provide a contact point on the anode electrode, local heating at the contact portion can be prevented, and problems such as uneven plasma processing performance and damage to the anode due to thermal stress can be prevented.
In this case, if the electrostatic chuck electrode is also used as the RF coupling electrode, the apparatus configuration and the manufacturing process can be simplified, and cost reduction and reliability improvement can be expected.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. It should be noted that the following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.
FIG. 1 is a schematic longitudinal sectional view showing a schematic configuration of a plasma processing apparatus Z1 according to an embodiment of the present invention, FIG. 2 is an enlarged view of a peripheral portion of the anode electrode 1 in FIG. 1, and FIG. Fig. 4 is a schematic diagram when the electrode has a bipolar structure, Fig. 4 is a schematic diagram when the electrostatic chuck electrode has a bipolar structure, and Fig. 5 and Fig. 6 show the attachment of the sealing material 17 for sealing the gap 8 for filling the heat transfer gas. 7 is an arrangement example of the heater 18 and the temperature measuring element 19, FIG. 8 is a schematic longitudinal sectional view showing a schematic configuration of a plasma processing apparatus Z2 in which the present invention is applied to an anode type ICP, and FIG. 9 is an RF coupling electrode. 10 is a configuration example when the electrostatic chuck electrode 6 is also used as the RF coupling electrode 22, and FIG. 11 is a configuration of the electrostatic chuck electrode 6 or the RF coupling electrode 22 in the plasma processing apparatus Z2. Example, 12 configuration example of a heater 18 'in the plasma processing apparatus Z2, 13 and 14 are arranged of the RF shield ring 24.
[0008]
The plasma processing apparatus Z1 according to the present embodiment has a schematic configuration as shown in FIG. 1 (overall schematic view) and FIG. 2 (enlarged view in the vicinity of the anode electrode).
In the conductive chamber 5 (corresponding to a predetermined container) of the plasma processing apparatus Z1, the cathode electrode 2 and the anode electrode 1 are disposed so as to face each other. A workpiece W is placed on the upper surface of the cathode electrode 2.
A chuck holding block 3 (an example of a holding member) as a top plate is fixed to the upper portion of the chamber 5, and the anode electrode 1 is a ring-shaped clamp 4 fixed to the chuck holding block 3. Is held at the periphery thereof.
Inside the chuck holding block 3, there are a refrigerant groove 9 through which a refrigerant flows, a process gas channel 10 through which a process gas flows, and a heat transfer gas channel 11 through which a heat transfer gas flows, for example, 1 or A plurality are formed. The process gas channel 10 is connected to a plurality of process gas supply ports 12 formed in the anode electrode 1 through a communication path 13, and from the process gas supply port 12, a gas type, a flow rate, etc. for each section. Is supplied to the plasma processing space 15.
[0009]
As shown in FIG. 2, an electrostatic chuck electrode 6 covered with an insulating layer 7 is embedded on the lower surface side of the chuck holding block 3 (the surface facing the anode electrode 1). It is connected to a high voltage power source via a voltage supply line 16. By applying a high voltage to the electrostatic chuck electrode 6, the anode electrode 1 and the electrostatic chuck electrode 6 attract each other by electrostatic force, and the anode electrode 1 is attracted to the lower surface of the chuck holding block 3. Retained. As described above, in the present plasma processing apparatus Z1, the anode electrode 1 is fixed to the chuck holding block 3 by the electrostatic force that acts substantially evenly on the entire surface. Therefore, the temperature due to non-uniform clamping force and heat transfer amount on the anode electrode. There is no difference, and plasma processing performance non-uniformity due to the temperature difference of the anode electrode and anode damage due to thermal stress can be prevented.
Here, as the arrangement method of the electrostatic chuck electrode 6, a single electrode structure in which one electrostatic chuck electrode 6 is made to correspond to the anode electrode 1 as shown in FIG. 3, and an anode electrode as shown in FIG. A bipolar structure in which two electrostatic chuck electrodes 6a and 6b are made to correspond to 1 and a positive and negative high voltage is applied to both of them can be considered. In the case of the monopolar structure shown in FIG. 3, plasma ignition (high voltage supply to the cathode electrode 2) is required for adsorption of the anode electrode 1, but in the case of the bipolar structure shown in FIG. Plasma ignition is not necessary for the adsorption.
[0010]
As shown in FIG. 2, a substantially uniform heat transfer gas filling gap 8 is formed between the lower surface of the chuck holding block 3 and the facing surface of the anode electrode 1. The heat transfer gas is supplied from the heat transfer gas channel 11 through the communication passage 14. By supplying the heat transfer gas to the gap 8 for filling the heat transfer gas, the uniformity of the heat transfer efficiency over the entire surface of the anode electrode 1 is further increased, thereby further increasing the uniformity of the temperature of the anode electrode, and thus the uniformity of the plasma treatment. Further improvement of sex can be expected.
Here, if the heat transfer gas in the heat transfer gas filling gap 8 leaks into the plasma processing space 15, the plasma processing may be adversely affected. Therefore, the heat transfer gas filling gap 8 and the plasma processing space may be adversely affected. It is desirable to provide a sealing means between the two. For example, as shown in FIG. 5, if seals 17 are provided between the clamp 4 and the chuck holding block 3 and between the clamp 4 and the anode electrode 1, the heat transfer gas leaks from the periphery of the anode electrode 1. Can be prevented. Further, as shown in FIG. 6, leakage of heat transfer gas from the communication path 13 can also be prevented by providing a seal 17 around the communication path 13 for supplying process gas. Note that the seal is not necessarily required when the heat transfer gas is the same as at least one of the process gases.
[0011]
As described above, in the plasma processing apparatus Z1 according to the present embodiment, the electrostatic chuck electrode 6 covered with the insulating layer 7 is embedded on the lower surface side of the chuck holding block 3 as the top plate of the chamber 5. Since the anode electrode 1 is attracted and held on the lower surface of the chuck holding block 3 by applying a high voltage thereto, the temperature due to non-uniform tightening force and heat transfer amount on the anode electrode. There is no difference, and plasma processing performance non-uniformity due to the temperature difference of the anode electrode and anode damage due to thermal stress can be prevented.
Further, a substantially uniform heat transfer gas filling gap 8 is formed between the lower surface of the chuck holding block 3 and the facing surface of the anode electrode 1, and the heat transfer gas is supplied thereto. Therefore, the uniformity of the heat transfer efficiency on the entire surface of the anode electrode 1 is further increased, thereby further increasing the uniformity of the temperature of the anode electrode, and further improvement of the uniformity of the plasma processing can be expected.
Further, since the periphery of the anode electrode 1 is supplementarily held by the clamp 4, it is possible to reliably prevent the anode electrode 1 from falling off the chuck holding block 3.
[0012]
【Example】
In the plasma processing apparatus Z1 according to the above-described embodiment, for example, as shown in FIG. 7, one or a plurality of heaters 18 (an example of heating means) are embedded in the chuck holding block 3 to perform temperature control. Therefore, the temperature distribution of the anode electrode 1 can be actively controlled, and the temperature distribution of the anode electrode 1 can be made more uniform. In order to increase the control response speed of the anode electrode as much as possible, the heater 18 is desirably installed at a position close to the anode electrode 1 (for example, in the insulating layer 7 of the electrostatic chuck electrode 6). Further, a light transmitting rod is embedded in the chuck holding block 3 and the anode electrode 1 is irradiated with infrared rays or the like through the light transmitting rod. If this is used as the heater, the anode electrode 1 is directly heated. Therefore, the responsiveness of the temperature control of the anode electrode is further improved.
Further, a temperature measuring element 19 (an example of temperature measuring means) is inserted into the chuck holding block 3 (for example, in the insulating layer 7 of the electrostatic chuck electrode 6), and the temperature measuring element 19 is shown in FIG. By controlling the heater 18 with a temperature controller that does not, the temperature distribution of the anode electrode 1 can always be kept uniform by following the temporal variation of the plasma inflow heat to the anode electrode 1.
The temperature measuring element 19 is preferably an element that can directly measure the temperature of the anode electrode 1. For example, one end of the optical fiber may be disposed on the back surface of the anode electrode 1 and the other end may be connected to a radiation thermometer. As a result, the temperature of the anode electrode can be controlled with higher accuracy.
Further, a heat transfer gas pressure controller (not shown) for controlling the gas pressure in the heat transfer gas filling gap 8 is installed so as to change the pressure of the heat transfer gas in conjunction with the control of the heater 19 by the temperature controller. As a result, the temperature control of the anode electrode 1 can be performed more efficiently. For example, in the plasma generation time zone, the gas pressure in the heat transfer gas filling gap 8 is set to a predetermined value required for heat transfer so that the heat flow from the plasma to the anode electrode 1 is released to the chuck holding block 3 as much as possible. Thus, it is conceivable that the plasma extinction time zone (time zone during which the wafer W is exchanged) is controlled so that the gas pressure is made as low as possible so that the heat quantity of the anode electrode 1 is not transferred to the chuck holding block 3 as much as possible.
[0013]
Further, as shown in the plasma processing apparatus Z2 of FIG. 8, by installing a plurality of inductively coupled plasma excitation antennas 21 in the chuck holding block 3, it is possible to form an anode-type ICP (Inductively Coupled Plasma). is there.
At this time, when RF power is supplied to the anode electrode 1, if RF power is directly connected to the anode electrode 1, the resistance at the contact portion increases and local heating occurs, resulting in non-uniform plasma processing performance. Or a new problem that the anode is damaged due to thermal stress. Therefore, as shown in FIG. 9, for example, an RF coupling electrode 22 is embedded in the insulating layer 7 of the chuck holding block 3, and the anode electrode 1 and the RF coupling electrode 22 are connected in a high-frequency circuit manner by capacitive coupling. If it is configured to communicate with the above, the above problem does not occur.
Furthermore, as shown in FIG. 10, if the electrostatic chuck electrode 6 is also used as the RF coupling electrode 22, the apparatus configuration and the manufacturing process can be simplified, and cost reduction and reliability improvement can be expected.
[0014]
As is well known, in an ICP device, when a conductive member is disposed between an antenna and plasma, the shape of the conductive member needs to be able to prevent the generation of eddy currents. In the plasma processing apparatus Z2, which is an anode-type ICP, the eddy current generation can be prevented by providing the electrostatic chuck electrode 6 and the RF coupling electrode 22 with a slit 23 as shown in FIG. Is possible.
Furthermore, when a heater is installed in the plasma processing apparatus Z2, it is naturally desirable to reduce the mutual inductance between the heater wire and the antenna as much as possible. Specifically, for example, as shown in FIG. 12, the IN side line and the OUT side line of the heater 18 'are paired and embedded in the insulating layer 7, and the interval between the IN side line and the OUT side line is set to a predetermined insulation. It is sufficient to make it as narrow as possible to ensure the property.
[0015]
Further, when a plurality of antennas are used in an ICP apparatus like the plasma processing apparatus Z2, the spatial distribution of the plasma density can be reduced by limiting the range of the RF electric field supplied from each antenna in the plasma processing chamber. Controllability can be improved.
As a specific method for limiting the range covered by the RF electric field supplied from each antenna, for example, as shown in FIGS. 13 and 14, the RF shield ring 24 (an example of the RF shield means) is used as the insulating layer 7 or the anode. It is conceivable to arrange it on the electrode 1. By arranging the RF shield ring 24 as shown in the figure, the plasma generation region by each antenna 21 is limited to the vicinity immediately below each antenna. As a result, if a region having a high plasma density is generated somewhere directly above the wafer that is the object to be processed, the RF power may be adjusted only for the antenna in the vicinity thereof. On the other hand, if the RF shield ring 24 is not arranged, even if a region with a high plasma density occurs locally, the current flowing through all antennas must be adjusted in consideration of the contribution from relatively distant antennas. The control is complicated.
[0016]
【The invention's effect】
As described above, the present invention is a plasma processing apparatus in which a cathode electrode for holding an object to be processed and an anode electrode facing the cathode electrode are provided in a predetermined container, and is fixed to the container. An electrostatic chuck electrode connected to a power source and covered with an insulating layer is attached to the holding member, and the anode electrode is applied to the holding member by electrostatic force obtained by supplying a potential to the electrostatic chuck electrode. Since it is configured as a plasma processing device characterized by being adsorbed and held, there is no temperature difference due to non-uniform clamping force or heat transfer amount in the anode electrode, and the plasma processing performance due to the temperature difference of the anode electrode is prevented. It can prevent the anode from being damaged due to non-uniformity or thermal stress.
Further, if a substantially uniform gap is formed between the opposing surfaces of the holding member and the anode electrode, and heat transfer gas is supplied to the gap, the uniformity of the heat transfer efficiency over the entire anode electrode can be improved. This further increases the uniformity of the temperature of the anode electrode, and as a result, further improvement in the uniformity of the plasma treatment can be expected.
At this time, if a sealing means for sealing the periphery of the gap is provided, it is possible to prevent a problem that the heat transfer gas leaks into the plasma processing space and adversely affects the plasma processing.
Further, if the clamp for supporting the peripheral portion of the anode electrode is attached to the holding member, the holding of the anode electrode is further ensured.
[0017]
Further, if a heating means for directly or indirectly heating the anode electrode is installed on the holding member, it becomes possible to actively control the temperature distribution of the anode electrode, and more reliably the temperature distribution of the anode electrode. Can be made uniform.
At this time, temperature measuring means for directly or indirectly measuring the temperature of the anode electrode is installed on the holding member, and the heating means is controlled by the temperature control means based on the temperature measured by the temperature measuring means. By doing so, it is possible to keep the temperature distribution of the anode electrode always uniform by following the temporal fluctuation of the heat flowing into the anode electrode.
[0018]
Furthermore, an antenna for inductively coupled plasma excitation may be installed inside or above the holding member to provide an anode type ICP device.
At this time, if an RF shield means for partially shielding the RF electric field supplied from the antenna is installed at a predetermined position of the holding member or the anode electrode, the range covered by the RF electric field of each antenna is limited. It is possible to improve the controllability of the spatial distribution of plasma density.
When supplying RF power to the anode electrode, an RF coupling electrode connected to a high frequency RF power source and covered with an insulating layer is attached to the holding member, and the RF coupling electrode is connected to the anode electrode. It is also possible to supply the RF power indirectly. Thereby, since it is not necessary to provide a contact point on the anode electrode, local heating at the contact portion can be prevented, and problems such as uneven plasma processing performance and damage to the anode due to thermal stress can be prevented.
In this case, if the electrostatic chuck electrode is also used as the RF coupling electrode, the apparatus configuration and the manufacturing process can be simplified, and cost reduction and reliability improvement can be expected.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a schematic configuration of a plasma processing apparatus Z1 according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a peripheral portion of an anode electrode 1 in FIG.
FIG. 3 is a schematic diagram when the electrostatic chuck electrode has a monopolar structure.
FIG. 4 is a schematic diagram when the electrostatic chuck electrode has a bipolar structure.
FIG. 5 shows an example of attachment of a sealing material 17 for sealing the gap 8 for filling a heat transfer gas.
FIG. 6 shows another example of how the sealing material 17 is attached.
7 shows an arrangement example of a heater 18 and a temperature measuring element 19. FIG.
FIG. 8 is a schematic longitudinal sectional view showing a schematic configuration of a plasma processing apparatus Z2 in which the present invention is applied to an anode-type ICP.
FIG. 9 shows an arrangement example of an RF coupling electrode 22;
10 is a configuration example when the electrostatic chuck electrode 6 is also used as the RF coupling electrode 22. FIG.
FIG. 11 shows a configuration example of the electrostatic chuck electrode 6 or the RF coupling electrode 22 in the plasma processing apparatus Z2.
FIG. 12 shows a configuration example of a heater 18 ′ in the plasma processing apparatus Z2.
FIG. 13 shows an arrangement example of an RF shield ring 24.
14 shows another arrangement example of the RF shield ring 24. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Anode electrode 2 ... Cathode electrode 3 ... Chuck holding block (an example of a holding member)
4 ... Clamp 5 ... Chamber (corresponding to a predetermined container)
6 ... Electrostatic chuck electrode 7 ... Insulating layer 8 ... Heat transfer gas filling gap 9 ... Refrigerant groove 10 ... Process gas channel 11 ... Heat transfer gas channel 12 ... Process gas supply port 13, 14 ... Communication passage 15 ... Plasma treatment Space 16 ... High voltage supply line 17 ... Seal 18 ... Heater (an example of heating means)
19 ... Temperature measuring element (an example of temperature measuring means)
21 ... Antenna 22 ... RF coupling electrode 23 ... Slit 24 ... RF shield ring (an example of RF shield means)

Claims (7)

To a predetermined vessel, a cathode electrode processing object is retained in the plasma processing apparatus and the anode electrode is provided opposite to the cathode electrode,
A holding member fixed to said container,
An electrostatic chuck electrode that is attached to the surface of the holding member facing the anode electrode, is covered with an insulating layer, and holds the anode electrode by electrostatic force obtained by supplying a potential from a high-voltage power supply ;
A heat transfer gas supply means for supplying a heat transfer gas to a substantially uniform gap formed between the anode electrode and the electrostatic chuck electrode;
A ring-shaped clamp that is attached to the holding member and supplementarily holds the periphery of the anode electrode;
Sealing means provided between the clamp and the holding member and between the clamp and the anode electrode;
The plasma processing apparatus characterized by comprising a. The plasma processing apparatus according to claim 1 , further comprising a heating unit that is installed on the holding member and heats the anode electrode directly or indirectly . Temperature measuring means installed on the holding member and directly or indirectly measuring the temperature of the anode electrode;
Temperature control means for controlling the heating means based on the temperature measured by the temperature measuring means;
The plasma processing apparatus according to claim 2, further comprising: The plasma processing apparatus according to any one of claims 1 to 3, wherein an antenna for inductively coupled plasma excitation is installed inside or above the holding member . 5. The plasma processing apparatus according to claim 4 , wherein RF shielding means for partially shielding an RF electric field supplied from the antenna is installed at a predetermined position of the holding member or the anode electrode . An RF coupling electrode connected to a high frequency RF power source and covered with an insulating layer is attached to the holding member, and the RF power is indirectly supplied from the RF coupling electrode to the anode electrode. 6. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is provided. The plasma processing apparatus according to claim 6 , wherein the electrostatic chuck electrode is also used as the RF coupling electrode .

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