TW202121487A - Lower electrode member for plasma processing equipment and plasma processing equipment for preventing high-voltage breakdown damage caused by accumulation of static electricity - Google Patents

Abstract

The invention relates to a lower electrode member for plasma processing equipment and a plasma processing equipment. A radio frequency resistance structure is connected in series between the radio frequency high-voltage conductor component of the lower electrode member and the ground, in which one end is connected to the radio frequency high-voltage conductor component and the other end is grounded. The direct-current resistance of the radio frequency resistance structure is less than or equal to 100MOhm, and the radio frequency impedance thereof is greater than or equal to 100KOhm. By adding the radio frequency resistance structure between the radio frequency high-voltage component and the ground in the invention, although the insulation liquid may generate static electricity during flowing process, the radio frequency impedance of the radio frequency resistance structure is larger so the radio frequency can hardly be grounded through the radio frequency resistance structure. Furthermore, because the direct-current resistance of the radio frequency resistance structure is smaller, the generated static electricity is able to be grounded through the radio frequency resistance structure. Thus, the invention is beneficial to prevent the high-voltage breakdown damage caused by accumulation of static electricity.

Description

Lower electrode assembly for plasma processing equipment and plasma processing equipment

The present invention relates to the technical field of semiconductor equipment, in particular to a lower electrode assembly used in plasma processing equipment and plasma processing equipment.

In the field of semiconductor manufacturing technology, it is often necessary to perform plasma processing on the substrate to be processed. The process of plasma processing the substrate to be processed needs to be performed in the plasma processing equipment.

Plasma processing equipment generally includes a vacuum reaction chamber. The vacuum reaction chamber is provided with a carrying table for carrying the substrate to be processed. The carrying table usually includes a susceptor and an electrostatic chuck arranged above the susceptor for fixing the substrate. A radio frequency high voltage conductor component is arranged under the base, and the radio frequency high voltage conductor component is connected to a radio frequency source. The reaction gas is introduced into the vacuum reaction chamber. Under the excitation of radio frequency, the reaction gas ionizes to generate plasma to process the substrate. During the processing, the substrate will generate heat. In order to reduce the heat of the substrate, a cooling pipe is usually installed in the base, and a circulating cooling method is used to remove the heat from the electrostatic chuck and the substrate. Because it works in a radio frequency environment, the heat conduction medium in the cooling pipe in the base adopts insulating liquid, but the insulating liquid will rub against some insulators in the cooling pipe during the flow process to generate static electricity, and the static charge will accumulate in the radio frequency high-voltage conductor Parts. The radio frequency high voltage conductor parts usually conduct radio frequency through capacitance, so for direct current it is in a floating state. When the static charge accumulates on the radio frequency high voltage conductor parts, the potential of the radio frequency high voltage conductor parts will rise sharply when reaching a certain threshold. , Such as 1-2 kV, will break down the fragile insulating parts through an arc to discharge to the ground, causing damage to devices such as insulating liquid transmission pipelines and radio frequency isolation magnetic rings.

The invention provides a lower electrode assembly and a plasma processing device for plasma processing equipment, which can effectively eliminate high-voltage breakdown damage caused by static electricity accumulation and solve the problem of static charge accumulation caused by existing high-resistance cooling pipes.

In order to achieve the above objective, the present invention provides a lower electrode assembly for plasma processing equipment, including:

A base, which is arranged in the vacuum reaction chamber of the plasma processing equipment;

The electrostatic chuck is arranged on the base, and the electrostatic chuck carries the substrate to be processed;

The cooling pipe is arranged in the base, and the two ends of the cooling pipe lead out the vacuum reaction chamber and then are connected with the cooling liquid storage equipment;

The radio frequency high voltage conductor part is arranged under the base;

The radio frequency resistance structure has one end connected to the radio frequency high-voltage conductor component and the other end is grounded. The direct current resistance of the radio frequency resistance structure is less than or equal to 100MΩ, and the radio frequency impedance is greater than or equal to 100KΩ.

The radio frequency high-voltage conductor components include: an equipment board, a radio frequency rod connected with the equipment board, and a matching device connected with the radio frequency rod.

In an embodiment of the present invention, one end of the radio frequency resistance structure is connected to the device board, and the other end is grounded.

In another embodiment of the present invention, the radio frequency resistance structure is located in the matcher, one end of the radio frequency resistance structure is connected to the radio frequency rod, and the other end is connected to the housing of the matcher.

In another embodiment of the present invention, the lower electrode assembly further includes: an isolation block surrounding the radio frequency rod, the radio frequency resistance structure is located in the isolation block, the radio frequency resistance structure is located outside the matcher, one end is connected to the radio frequency rod, and the other end is grounded.

In an embodiment of the present invention, the radio frequency resistance structure only includes radio frequency resistance.

In another embodiment of the present invention, the radio frequency resistance structure includes a radio frequency resistance and a non-radio frequency resistance connected in series, the resistance value of the radio frequency resistance is 100KΩ-10MΩ, and the resistance value of the non-radio frequency resistance is 10MΩ-100MΩ.

In an embodiment of the present invention, the lower electrode assembly further includes: a radio frequency power source connected to the matcher.

In an embodiment of the present invention, when the electrostatic chuck is a temperature-controllable electrostatic chuck, the lower electrode assembly further includes: an AC source connected to the temperature-controllable electrostatic chuck; and a radio frequency filter located between the AC source and the temperature-controllable electrostatic chuck器: The radio frequency isolation magnetic ring located in the radio frequency filter.

In an embodiment of the present invention, the lower electrode assembly further includes: an insulating ring located under the device board; the material of the insulating ring is an antistatic material, which serves as a radio frequency resistor.

The present invention also provides a plasma processing equipment, including:

Vacuum reaction chamber;

An air inlet device, which is arranged on the top of the vacuum reaction chamber and is used to provide reaction gas into the vacuum reaction chamber;

Lower electrode assembly.

The plasma processing equipment is a capacitively coupled plasma processing equipment or an inductively coupled plasma processing equipment. Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

In the lower electrode assembly of the present invention, by adding a radio frequency resistance structure between the radio frequency high voltage component and the ground, although the insulating liquid generates static electricity during the flow process, the radio frequency impedance of the radio frequency resistance structure is relatively large, making it difficult for the radio frequency to be grounded through the radio frequency resistance structure At the same time, the DC resistance of the radio frequency resistance structure is small, so that the generated static electricity can be introduced into the ground through the radio frequency resistance, and therefore, it is beneficial to prevent the high voltage breakdown damage caused by the accumulation of static electricity.

Hereinafter, the embodiments of the present invention will be described in detail based on FIGS. 1 to 5.

FIG. 1 is a schematic structural diagram of a plasma processing equipment including a bottom electrode assembly provided by the present invention.

As shown in FIG. 1, the plasma processing equipment includes a vacuum reaction chamber 1, a susceptor 2 is provided in the vacuum reaction chamber 1, and an electrostatic chuck 3 is provided on the susceptor 2, and the electrostatic chuck 3 is used to carry a substrate W to be processed. The base 2 is provided with a cooling pipe 4. The two ends of the cooling pipe 4 lead out of the vacuum reaction chamber 1 and are connected to a cooling liquid storage device (not shown in the figure). The insulating liquid circulates in the cooling pipe 4 and is taken away by heat exchange. The heat on the base 2 and the electrostatic chuck 3. The lower part of the base 2 is provided with a radio frequency high voltage conductor component. The radio frequency high voltage conductor component includes: an equipment board 5, a radio frequency rod 18 connected to the equipment board 5, and a matcher 9 connected to the radio frequency rod 18. The equipment board 5 is arranged at the lower part of the base 2, and the connecting joints at both ends of the cooling pipe 4 are fixed on the equipment board 5. The vacuum reaction chamber 1 is also provided with a grounding ring 6. The grounding ring 6 surrounds the base 2 and the equipment board 5, and can guide the coupled radio frequency current in the vacuum reaction chamber 1 to the ground. The grounding ring 6 also serves as an airtight seal. The grounding ring 6 The inside is a vacuum environment, full of radio frequency fields, and the outside of the grounding ring 6 is an atmospheric environment. An insulating ring 7 is arranged between the grounding ring 6 and the equipment board 5, and the insulating ring 7 realizes electrical isolation between the equipment board 5 and the grounding ring 6. An air inlet device 8 is provided on the top of the vacuum reaction chamber 1 for supplying reaction gas into the vacuum reaction chamber 1.

In this embodiment, the plasma processing equipment is a capacitively coupled plasma processing equipment (CCP), the air intake device 8 is used as the upper electrode, the base 2 is used as the lower electrode, and the radio frequency power source is connected to the upper electrode or the lower electrode. The radio frequency signal generated by the radio frequency power source converts the reaction gas into plasma through the capacitance formed by the upper electrode and the lower electrode. The bias power source 10 is connected to the device board 5 through the matcher 9 so that the plasma is evenly distributed to the surface of the base 2, which is beneficial to the movement of the plasma to the surface of the substrate W to be processed, and the substrate W to be processed is processed.

In other embodiments, the plasma processing equipment is an inductively coupled plasma processing equipment (ICP), an insulating window is opened on the top of the vacuum reaction chamber 1, and an inductance coil is arranged on the insulating window, and the inductance coil is connected to the radio frequency power source 10 to make the reaction The gas is converted into plasma, and the bias power source 10 is connected to the device board 5 through the matcher 9 so that the plasma moves toward the surface of the base 2, which is beneficial for the plasma to process the substrate W to be processed.

In other embodiments, when the electrostatic chuck is a temperature-controllable electrostatic chuck, the electrostatic chuck is also connected to an AC source, a radio frequency filter is arranged between the AC source and the temperature-controllable electrostatic chuck, and a radio frequency isolation magnetic ring is arranged in the radio frequency filter. The RF high-voltage components are usually isolated from the ground, that is, the RF high-voltage components are DC insulated from the ground. The purpose is to cut off the RF transmission through the DC path to the ground, so that the RF transmission cannot enter the vacuum reaction chamber and directly to the ground. Short circuit. Generally, a relatively large distance is maintained between the RF high-voltage component and the side wall of the vacuum reaction chamber, so that the capacitance value is small. The RF current mainly passes through the main capacitors of the upper and lower plates to the ground, so that it passes through the plasma.

The insulating liquid in the cooling pipe will generate static charge accumulation during the flow process. Experiments have found that this static charge will accumulate on the RF high-voltage components insulated to the ground. The higher the maximum voltage of the static charge accumulation, the greater the breakdown of the insulation. The higher the possibility of the material, the greater the risk.

In order to solve the problem of static charge accumulation on the lower electrode assembly, a radio frequency resistance structure can be directly connected in series with the radio frequency high-voltage component. The radio frequency resistance structure is applied in a radio frequency environment to block radio frequency transmission and prevent heat generation.

The DC resistance of the RF resistance structure is small, so that the DC resistance to the ground is less than or equal to one hundred megabytes, so that the generated static electricity can be introduced into the ground through the RF resistance, which can effectively eliminate the high voltage breakdown damage caused by the accumulation of static electricity. At the same time, the series radio frequency resistance structure also needs to meet the characteristics of high radio frequency impedance, making it difficult for the radio frequency to be directly grounded through the loop.

In an embodiment of the present invention, the device board 5 is a metal part in the lower electrode assembly. Static electricity can be discharged by connecting it with the ground in series with a DC high-impedance radio frequency resistance structure. The radio frequency resistance of the radio frequency resistance structure is higher. Large, making it difficult for the radio frequency to be grounded through the radio frequency resistance structure, and at the same time, the DC resistance of the radio frequency resistance structure is small, so that the generated static electricity can be introduced into the ground through the radio frequency resistance structure, which can achieve the effect of eliminating the accumulated charge of static electricity. As shown in Figure 2, a radio frequency resistor 11 is connected in series with the equipment board 5 and the ground. According to the experimental data, the DC resistance of the radio frequency resistor 11 should be less than 100MΩ. At the same time, the radio frequency resistor 11 should be a high impedance device, and its radio frequency impedance should be Above 100KΩ, in order to prevent the radio frequency from passing through this loop and directly grounding, the radio frequency resistance 11 is directly connected in series between the equipment board and the ground, which can continue to effectively prevent the accumulation of static electricity.

Ground the RF resistance structure. In order to achieve grounding, the RF resistance structure can be connected to the side wall of the reaction chamber, and the RF resistance structure can also be connected to a grounding ring. As shown in Figure 1, the grounding ring 6 is set in the vacuum reaction chamber 1, and the grounding ring 6 Surrounding the base 2 and the equipment board 5, the coupled radio frequency current in the vacuum reaction chamber can be led to the ground.

The present invention is measured by an oscilloscope. When the RF resistance structure is not connected in series between the equipment board and the ground, the maximum voltage of static charge accumulation on the RF high-voltage components of the lower electrode assembly is detected to reach approximately 2800V, which is between the equipment board and the ground. After connecting a 100MΩ RF resistance structure in series, the voltage curve generated by static charge accumulation disappeared, and the baseline did not increase significantly (<10V). It can be seen that the present invention can effectively eliminate high voltage breakdown damage caused by static electricity accumulation. The RF resistance structure is directly connected in series between the equipment board and the ground, which can continue to effectively prevent static electricity from accumulating.

In order to reduce the damage to the integrity of the vacuum reaction chamber, in another embodiment of the present invention, the radio frequency resistance structure can be arranged in the matcher. As shown in FIG. 3, one end of the matcher 9 is connected to the radio frequency power source 10. The other end is connected to the device board 5 through the radio frequency rod 18. As shown in Figure 3, a radio frequency resistor 12 is located in the matcher 9. One end of the radio frequency resistor 12 is connected to the radio frequency rod 18, and the other end is connected to the housing of the matcher 9, grounded through the housing of the matcher. The DC resistance of the radio frequency resistor 12 is also It should be less than 100MΩ, so that the generated static electricity can be introduced into the ground through the RF resistance, and the RF impedance is above 100KΩ, making it difficult for the RF to be grounded through the RF resistance.

In addition, arranging the RF resistance structure in the matching device facilitates installation and maintenance. Only the matching device needs to be disassembled for maintenance, and there is no need to destroy the vacuum reaction chamber and disassemble various parts in the vacuum reaction chamber.

In another embodiment of the present invention, the radio frequency resistance structure can also be arranged outside the matcher, and one end is connected to the radio frequency rod 18, and the other end is grounded. As shown in FIG. 4, the radio frequency resistance 13 is arranged in the isolation block 17. , Can minimize the electrostatic discharge arc. One end of the radio frequency resistance 13 is connected to the radio frequency rod 18, and the other end is grounded. The radio frequency resistance 13 can be made of antistatic materials, such as ESD (electrostatic discharge) plastic, or the radio frequency resistance 13 can also be made of conductive impurity ceramic materials.

In another embodiment of the present invention, as shown in FIG. 1, one end of the radio frequency rod 18 is connected to the device board 5, and the other end passes through the insulating ring 7, the ground ring 16 and the vacuum reaction chamber 1, and is connected to the matching device 9, which can be seen Out, the insulating ring 7 is in contact with both the radio frequency rod 18 and the ground. Therefore, the insulating ring 7 can be directly transformed into a radio frequency resistance by replacing the material of the insulating ring 7 with antistatic materials (such as ESD plastic) or conductive impurity ceramic materials. , So that the insulating ring 7 is used as a radio frequency resistor to realize the grounding of the radio frequency high-voltage components and discharge static electricity.

Because the price of radio frequency resistance is more expensive, the higher the resistance value, the more expensive the price. In order to reduce the cost, consider whether the radio frequency resistance can be replaced by a DC resistance. However, with the same resistance value of 100MΩ, the heating of the DC resistor is not optimistic, and it is difficult to meet the limit condition of basically no heating in the RF field. As shown in Figure 5, a resistance combination is used to replace the radio frequency resistance 11 in Figure 2 and the radio frequency resistance 12 in Figure 3. The resistance combination includes the radio frequency resistance 14 connected to the radio frequency high-voltage conductor component and the two ends are respectively connected to the radio frequency resistance 14 and The DC resistor 15 connected to the ground; the resistance value of the radio frequency resistor 14 is 100KΩ～10MΩ, and the resistance value of the DC resistor 15 is 10MΩ～100MΩ. Since the radio frequency resistance 14 is connected to the radio frequency high-voltage conductor component, most of the radio frequency is blocked by the radio frequency resistance 14, so the radio frequency reaching the DC resistance 15 is less, that is, it is difficult for the radio frequency to be grounded through the radio frequency resistance. At the same time, since the radio frequency reaching the DC resistor 15 is less, the DC resistor 15 is not easy to generate heat, and because the resistance of the DC resistor 15 is small, the generated static electricity can be introduced into the ground through the radio frequency resistor.

The invention connects the radio frequency resistance to the ground in series on the radio frequency high voltage component of the lower electrode assembly, and discharges static electricity through the radio frequency resistance, thereby effectively eliminating high voltage breakdown damage caused by static electricity accumulation, and solving the problem of static charge accumulation caused by the existing high-resistance cooling pipeline.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation to the present invention. Various modifications and alternatives to the present invention will be obvious after reading the above content by those with ordinary knowledge in the technical field. Therefore, the scope of protection of the present invention should be defined by the scope of the attached patent application.

1: Vacuum reaction chamber 2: pedestal 3: Electrostatic chuck 4: Cooling pipe 5: Device board 6: Grounding ring 7: Insulation ring 8: Intake device 9: matcher 10: Bias power source 11,12,13,14: RF resistance 15: DC resistance 16: Grounding ring 17: Isolation block 18: RF rod W: substrate to be processed

Fig. 1 is a schematic structural diagram of a plasma processing equipment including a lower electrode assembly provided by the present invention; FIG. 2 is a schematic diagram of a structure of connecting a lower electrode assembly to a radio frequency resistor in an embodiment of the present invention; FIG. 3 is a schematic diagram of a lower electrode assembly connected to a radio frequency resistor structure in another embodiment of the present invention; FIG. 4 is a schematic diagram of the lower electrode assembly connected to the radio frequency resistor structure in another embodiment of the present invention; FIG. 5 is a schematic diagram of a lower electrode assembly connected to a radio frequency resistor structure in another embodiment of the present invention.

5: Device board

6: Grounding ring

11: RF resistance

Claims (12)

A lower electrode assembly for plasma processing equipment, which comprises: A base set in a vacuum reaction chamber of the plasma processing equipment; An electrostatic chuck, which is arranged on the base, and the electrostatic chuck is used to carry a substrate to be processed; A cooling pipe arranged in the base, two ends of the cooling pipe lead out of the vacuum reaction chamber and then connected to a cooling liquid storage device, and an insulating liquid is stored in the cooling liquid storage device; A radio frequency high-voltage conductor component arranged under the base; A radio frequency resistance structure, one end of which is connected to the radio frequency high-voltage conductor component, and the other end is grounded, the radio frequency resistance structure has a DC resistance of less than or equal to 100 MΩ, and a radio frequency impedance of greater than or equal to 100 KΩ. The lower electrode assembly for plasma processing equipment according to claim 1, wherein the radio frequency high voltage conductor component includes: an equipment board located below the base, a radio frequency rod connected to the equipment board, and the radio frequency rod A matcher connected. The lower electrode assembly for plasma processing equipment according to claim 2, wherein one end of the radio frequency resistance structure is connected to the equipment board, and the other end is grounded. The lower electrode assembly for plasma processing equipment according to claim 2, wherein the radio frequency resistance structure is located in the matcher, one end of the radio frequency resistance structure is connected to the radio frequency rod, and the other end is connected to the housing of the matcher . The lower electrode assembly for plasma processing equipment according to claim 2, wherein the lower electrode assembly further comprises: an isolation block surrounding the radio frequency rod, the radio frequency resistance structure is located in the isolation block, and the radio frequency resistance structure is located Outside the matcher, one end is connected to the radio frequency rod, and the other end is grounded. The lower electrode assembly for plasma processing equipment according to claim 1, wherein the radio frequency resistance structure only includes a radio frequency resistance. The lower electrode assembly for plasma processing equipment according to claim 1, wherein the radio frequency resistance structure includes a radio frequency resistance connected to the radio frequency high voltage conductor component and a DC resistance connected to the radio frequency resistance and ground at both ends respectively The resistance value of the radio frequency resistance is 100KΩ～10MΩ, and the resistance value of the DC resistance is 10MΩ～100MΩ. The lower electrode assembly for plasma processing equipment according to claim 2, wherein the lower electrode assembly further comprises: a radio frequency power source connected to the matcher. The lower electrode assembly for plasma processing equipment according to claim 1, wherein when the electrostatic chuck is a temperature-controllable electrostatic chuck, the lower electrode assembly further includes: an AC source connected to the temperature-controllable electrostatic chuck ; A radio frequency filter located between the AC source and the temperature-controlled electrostatic chuck; a radio frequency isolation magnetic ring located in the radio frequency filter. The lower electrode assembly for plasma processing equipment according to claim 2, wherein the lower electrode assembly further comprises: an insulating ring located below the equipment board; the insulating ring is made of antistatic material, which serves as a radio frequency resistor. A plasma processing equipment, which comprises: A vacuum reaction chamber; An air inlet device, which is arranged on the top of the vacuum reaction chamber, and is used to provide reaction gas into the vacuum reaction chamber; The lower electrode assembly as described in any one of claims 1-10. The plasma processing equipment according to claim 11, wherein the plasma processing equipment is a capacitively coupled plasma processing equipment or an inductively coupled plasma processing equipment.

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