TWI784323B - Lower electrode assembly for plasma treatment equipment and plasma treatment equipment - Google Patents

Abstract

A lower electrode assembly for plasma processing equipment and plasma processing equipment, a radio frequency resistance structure is connected in series between the radio frequency high voltage conductor part of the lower electrode assembly and the ground, one end of which is connected to the radio frequency high voltage conductor part, and the other end is grounded, and the radio frequency resistance The DC resistance of the structure is less than or equal to 100MΩ, and the radio frequency impedance is greater than or equal to 100KΩ. The present invention adds a radio frequency resistance structure between the radio frequency high-voltage components and the grounding. 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 radio frequency to pass through the radio frequency resistance structure. At the same time, the radio frequency resistance structure The DC resistance is small, so that the generated static electricity can be guided to the ground through the radio frequency resistor, so it is beneficial to prevent high-voltage breakdown damage caused by static electricity accumulation.

Description

Lower electrode assembly for plasma treatment equipment and plasma treatment equipment

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

In the field of semiconductor manufacturing technology, it is often necessary to perform plasma treatment on the substrate to be treated. The plasma treatment process of the substrate to be treated needs to be carried out in the plasma treatment equipment.

Plasma processing equipment generally includes a vacuum reaction chamber, and a carrier platform for carrying the substrate to be processed is arranged in the vacuum reaction chamber. The carrier platform usually includes a base and an electrostatic chuck arranged above the base for fixing the substrate. A radio frequency high-voltage conductor part is arranged under the base, and the radio frequency high-voltage conductor part is connected to a radio frequency source, and a reaction gas is introduced into the vacuum reaction chamber. Under radio frequency excitation, the reaction gas is ionized to generate plasma to process the substrate. The substrate will generate heat during the processing. In order to reduce the heat of the substrate, cooling pipes are usually installed in the base, and the heat on the electrostatic chuck and the substrate is taken away by means of circulating refrigeration. Because it works in a radio frequency environment, the heat transfer medium in the cooling pipe in the base uses 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 on the radio frequency high voltage conductor parts. The RF high-voltage conductor parts usually conduct radio frequency through capacitance, so they are in a suspended state for DC. When static charges accumulate on the RF high-voltage conductor parts, the potential of the RF high-voltage conductor parts will rise sharply. When it reaches a certain threshold , such as 1-2 kV, will break through the fragile insulating parts and discharge to the ground through the arc, causing damage to devices such as insulating liquid transmission pipes and radio frequency isolation magnetic rings.

The invention provides a lower electrode assembly for plasma processing equipment and 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 object, the present invention provides a lower electrode assembly for plasma processing equipment, comprising:

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

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

A cooling pipeline, which is arranged in the base, and the two ends of the cooling pipeline are led out of the vacuum reaction chamber and connected to the cooling liquid storage device;

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

A radio frequency resistance structure, one end of which is connected to the radio frequency high-voltage conductor part, and the other end is grounded, the DC 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 part includes: a device board, a radio frequency rod connected with the device board and a matcher connected with the radio frequency rod.

In one embodiment of the present invention, one end of the radio frequency resistor 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 shell 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 one embodiment of the invention, the RF resistor structure only includes RF resistors.

In another embodiment of the present invention, the RF resistor structure includes a RF resistor and a non-RF resistor connected in series, the RF resistor has a resistance of 100KΩ-10MΩ, and the non-RF resistor has a resistance of 10MΩ-100MΩ.

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

In one 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; a radio frequency filter located between the AC source and the temperature-controllable electrostatic chuck device; a radio frequency isolation magnetic ring located in the radio frequency filter.

In one 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, serving as a radio frequency resistor.

The present invention also provides a plasma treatment equipment, comprising:

Vacuum reaction chamber;

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

Lower electrode assembly.

The plasma processing equipment is capacitively coupled plasma processing equipment or 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 radio frequency to pass through the radio frequency resistance structure to ground At the same time, the DC resistance of the radio frequency resistance structure is small, so that the generated static electricity can be introduced to the ground through the radio frequency resistance, so it is beneficial to prevent the high voltage breakdown damage caused by the accumulation of the static electricity.

Embodiments of the present invention will be specifically described below with reference to FIG. 1 to FIG. 5 .

FIG. 1 is a schematic structural diagram of a plasma treatment device including a lower electrode assembly provided by the present invention.

As shown in FIG. 1 , the plasma processing equipment includes a vacuum reaction chamber 1. A base 2 is arranged in the vacuum reaction chamber 1. An electrostatic chuck 3 is arranged on the base 2. The electrostatic chuck 3 is used to carry a substrate W to be processed. The base 2 is provided with a cooling pipeline 4, and the two ends of the cooling pipeline 4 lead out to the vacuum reaction chamber 1, which is connected with the cooling liquid storage device (not shown in the figure). The insulating liquid circulates in the cooling pipeline 4 and is taken away through heat exchange. Heat on base 2 and electrostatic chuck 3. The lower part of the base 2 is provided with a radio frequency high voltage conductor component, which includes: a device board 5 , a radio frequency rod 18 connected to the device board 5 , and a matching device 9 connected to the radio frequency rod 18 . The equipment board 5 is arranged on the lower part of the base 2 , and the connection joints at both ends of the cooling pipeline 4 are fixed on the equipment board 5 . The vacuum reaction chamber 1 is also provided with a grounding ring 6, which 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 plays an airtight role. 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 provided between the grounding ring 6 and the equipment board 5 , and the insulating ring 7 implements electrical isolation between the equipment board 5 and the grounding ring 6 . The top of the vacuum reaction chamber 1 is provided with an air inlet device 8 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 gas inlet 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 equipment board 5 through the matcher 9, so that the plasma is evenly distributed on the surface of the base 2, which is conducive 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 set on the top of the vacuum reaction chamber 1. An inductive coil is arranged on the insulating window. The inductive coil is connected to the radio frequency power source 10, so that the reaction The gas is converted into plasma, and the bias power source 10 is connected to the device board 5 through the matching device 9, so that the plasma moves to 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, and 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 and the ground are DC insulated. The purpose is to block the loop of the RF through the DC path to the ground, so that the RF transmission cannot enter the vacuum reaction chamber and directly connect to the ground. short circuit. Usually, a relatively large distance is kept between the RF high-voltage components and the side wall of the vacuum reaction chamber, so that the capacitance value is small, and 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 pipeline will generate static charge accumulation during the flow process. It has been found experimentally that this static charge will accumulate on the RF high-voltage parts that are insulated to the ground. The greater the maximum voltage of the static charge accumulation, the greater the breakdown of the insulation. The higher the likelihood of the material, the greater the risk.

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

The DC resistance of the RF resistor structure is small, making its DC resistance to ground less than or equal to 100 megabytes, so that the generated static electricity can be introduced into the ground through the RF resistor, which can effectively eliminate the high-voltage breakdown damage caused by static electricity accumulation. At the same time, the series-connected radio frequency resistance structure also needs to meet the characteristics of high radio frequency impedance, making it difficult for radio frequency to directly ground through the loop.

In one embodiment of the present invention, the device board 5 is a metal part in the lower electrode assembly, and static electricity can be released by connecting a high-impedance radio-frequency resistance structure between it and the ground. The radio-frequency impedance of the radio-frequency resistance structure is relatively low. Large, making it difficult for radio frequency to ground 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 structure, and the effect of eliminating the accumulated static charge can be achieved. 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 this radio frequency resistor 11 should be less than 100MΩ. At the same time, this 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 directly grounding through this loop, the radio frequency resistor 11 is directly connected in series between the device board and the ground, which can continuously and effectively prevent the accumulation of static electricity.

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

An oscilloscope is used to measure the present invention. When the RF resistance structure is not connected in series between the equipment board and the ground, it is detected that the maximum voltage accumulated by the static charge on the RF high-voltage part of the lower electrode assembly reaches about 2800V, and between the equipment board and the ground. After the 100MΩ RF resistance structure was connected in series, the sudden change in the voltage curve caused by the accumulation of static charges disappeared, and there was no significant increase in the baseline (<10V). It can be seen that the present invention can effectively eliminate the high-voltage breakdown damage caused by static electricity accumulation. The RF resistance structure is directly connected in series between the device board and the ground, which can continuously and effectively prevent the accumulation of static electricity.

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 Figure 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 placed in the matcher 9, one end of the radio frequency resistor 12 is connected to the radio frequency rod 18, the other end is connected to the shell of the matcher 9, and grounded through the shell of the matcher, the DC resistance of the radio frequency resistor 12 is the same It should be less than 100MΩ, so that the generated static electricity can be guided to the ground through the radio frequency resistor, and the radio frequency impedance is above 100KΩ, making it difficult for the radio frequency to be grounded through the radio frequency resistor.

In addition, setting the radio frequency resistance structure in the matcher facilitates installation and maintenance. It only needs to remove the matcher for maintenance, without destroying the vacuum reaction chamber and disassembling various components in the vacuum reaction chamber.

In another embodiment of the present invention, the radio frequency resistance structure can also be arranged outside the matching device, 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 , which minimizes electrostatic discharge arcing. One end of the RF resistor 13 is connected to the RF rod 18, and the other end is grounded. The RF resistor 13 can be made of antistatic material, such as ESD (electrostatic discharge) plastic, or the RF resistor 13 can also be made of conductive impurity ceramic material.

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

Since the price of RF resistors is relatively expensive, the higher the resistance value, the more expensive the price. In order to reduce the cost, consider whether it is possible to replace RF resistors with DC resistors. However, with the same resistance value of 100MΩ, the heat generation of the DC resistance is not optimistic, and it is difficult to meet the restriction that there is basically no heat generation in the radio frequency field. As shown in Figure 5, a resistance combination is used to replace the radio frequency resistance 11 in Fig. 2 and the radio frequency resistance 12 in Fig. 3, the resistance combination comprises the radio frequency resistance 14 connected with the radio frequency high voltage conductor part and the two ends are respectively connected with the radio frequency resistance 14 and 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 resistor 14 is connected with the radio frequency high-voltage conductor part, most of the radio frequency is blocked by the radio frequency resistor 14, so the radio frequency reaching the DC resistor 15 is less, that is, it is difficult for the radio frequency to pass through the radio frequency resistor to ground. 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 to the ground through the RF resistor.

The invention connects the radio frequency resistance to the ground in series on the radio frequency high voltage part of the lower electrode assembly, and releases static electricity through the radio frequency resistance, thereby effectively eliminating the high voltage breakdown damage caused by the accumulation of static electricity, 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 understood that the above description should not be considered as limiting the present invention. Various modifications and substitutions of the present invention will be apparent to those of ordinary skill in the art after reading the foregoing disclosure. Therefore, the protection scope of the present invention should be defined by the scope of the appended patent application.

1: Vacuum reaction chamber 2: Base 3: Electrostatic chuck 4: cooling pipe 5: Device board 6: Grounding ring 7: insulating ring 8: Air intake device 9: Matcher 10: Bias power source 11,12,13,14: RF resistors 15: DC resistance 16: Grounding ring 17: Isolation block 18: RF Rod W: Substrate to be processed

Fig. 1 is a schematic structural view of a plasma treatment device comprising a lower electrode assembly provided by the present invention; Fig. 2 is a schematic diagram of the structure of the lower electrode assembly connected to the radio frequency resistor in one embodiment of the present invention; Fig. 3 is a schematic diagram of the lower electrode assembly connected to the radio frequency resistor structure in another embodiment of the present invention; Fig. 4 is a schematic diagram of the structure of the lower electrode assembly connected to the radio frequency resistor in another embodiment of the present invention; Fig. 5 is a schematic diagram of the structure of connecting the lower electrode assembly to the radio frequency resistor in another embodiment of the present invention.

5: Device board

6: Grounding ring

11: RF resistance

Claims (11)

A lower electrode assembly for plasma processing equipment, which includes: a base, which is arranged 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 for Carrying a substrate to be processed; a cooling pipeline, which is arranged in the base, and the two ends of the cooling pipeline are led out of the vacuum reaction chamber and 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 part arranged under the base; a radio-frequency resistance structure, one end of which is connected to the radio-frequency high-voltage conductor part and the other end is grounded, the DC 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 lower electrode assembly for plasma treatment equipment as described in claim 1, wherein the radio frequency high voltage conductor part comprises: an equipment board located under the base, a radio frequency rod connected to the equipment board and connected to the radio frequency rod A matcher for the connection. The lower electrode assembly for plasma processing equipment as claimed in 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 as described in 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 shell of the matcher . The lower electrode assembly for plasma processing equipment as described in claim 2, wherein the lower electrode assembly further comprises: a spacer block surrounding the radio frequency rod, the radio frequency resistance structure is located in the spacer block, the radio frequency resistance structure is located in Outside of this matcher, One end is connected to this RF pole and the other end is grounded. The lower electrode assembly for plasma processing equipment as described in claim 1, wherein the radio frequency resistance structure includes a radio frequency resistance connected to the radio frequency high voltage conductor part and a DC resistance connected to the radio frequency resistance and ground respectively at both ends ; The resistance value of the radio frequency resistor is 100KΩ~10MΩ, and the resistance value of the DC resistor is 10MΩ~100MΩ. The lower electrode assembly for plasma processing equipment as claimed in claim 2, wherein the lower electrode assembly further includes: a radio frequency power source connected to the matcher. The lower electrode assembly for plasma processing equipment as described in 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-controllable electrostatic chuck; a radio frequency isolation magnetic ring located in the radio frequency filter. The lower electrode assembly for plasma processing equipment as described in claim 2, wherein the lower electrode assembly further includes: an insulating ring located below the equipment board; the material of the insulating ring is an antistatic material as a radio frequency resistor. A plasma processing equipment, which includes: a vacuum reaction chamber; an air inlet device, which is arranged on the top of the vacuum reaction chamber, for providing reaction gas into the vacuum reaction chamber; as in any one of claim items 1-9 electrode assembly as described below. The plasma processing equipment as described in Claim 10, wherein the plasma processing equipment is capacitively coupled plasma processing equipment or inductively coupled plasma processing equipment.

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