TWI849353B - Electrostatic chuck, lower electrode element and plasma processing device - Google Patents

Abstract

The present invention discloses an electrostatic chuck for a plasma processing device, a lower electrode element and a plasma processing device. The electrostatic chuck comprises: a plurality of regions, a first region of the plurality of regions comprises a protrusion protruding toward the center of the electrostatic chuck; a first vent hole, the first vent hole being arranged in the protrusion.

Description

Electrostatic chuck, lower electrode element and plasma processing device

The present invention relates to the field of semiconductor processing equipment, and in particular to an electrostatic chuck, a lower electrode element and a plasma processing equipment.

The electrostatic chuck (ESC) is one of the most critical components in plasma etching equipment, especially reactive ion etching (RIE) equipment. The electrostatic chuck fixes the wafer to be processed by electrostatic force, and can adjust the temperature of the wafer to be processed through the base below. With the advancement of semiconductor technology and the diversity of etching applications, more stringent requirements are placed on the electrostatic chuck, such as better wafer temperature uniformity and better center-to-edge temperature regulation. In addition, the diversity of application environments requires the electrostatic chuck to work in a wider temperature range, higher power, higher voltage, and a larger RF frequency range. This greatly increases the mechanical, thermal, chemical, and electrical stresses in various parts of the ESD chuck component (i.e., the lower electrode component). If these stresses are not properly handled, the ESD chuck may be damaged. When the ESD chuck is damaged, it usually becomes the main failure of the plasma processing device. The combination of all these factors poses a severe challenge to the design and manufacture of the ESD chuck.

In a first aspect, the present invention provides an electrostatic chuck for a plasma processing device, the electrostatic chuck comprising: a plurality of regions, a first region of the plurality of regions comprising a protrusion protruding toward the center of the electrostatic chuck; a first vent hole, the first vent hole being disposed in the protrusion.

In a second aspect, the present invention provides a lower electrode element for a plasma processing device, comprising: the above-mentioned electrostatic chuck, used to carry a substrate placed thereon; a base, arranged below the electrostatic chuck; and a bonding layer, arranged between the electrostatic chuck and the base, to bond the electrostatic chuck and the base.

The present invention provides a plasma processing device, comprising: a reaction chamber; the above-mentioned lower electrode element, the lower electrode element is arranged in the reaction chamber, and the substrate to be processed is carried on the lower electrode element; a gas supply device, which provides reaction gas to the reaction chamber to generate plasma to process the substrate.

100: Lower electrode element

101,300,400,600,712: Electrostatic suction cup

102,710: Base

103: Binding layer

104: Second gas channel

105: Pipeline

106: First gas channel

200,W:substrate

250,750:RF power supply

310,410: Inner area

311,411: Sealing tape

320,420:Outside area

321,421: Outer ring sealing belt

315,325,415,425,635: Gas channel

450,650: protrusion

501,502: Taiwan Department

610: Central area

620: Middle area

630: Outer area

700: Vacuum reaction chamber

701: Side wall of reaction chamber

702: Open mouth

713: Electrostatic electrode

714: Heating device

720: Gas shower head

725: Gas supply device

732: Focus ring

734: Edge Ring

735: Plasma confinement ring

736: Middle ground ring

737: Lower ground ring

738: Mask ring

752: Matching network

740: Exhaust pump

O: Center of circle

FIG1 shows a schematic diagram of a lower electrode element for a plasma processing device according to an embodiment of the present invention.

FIG. 2 shows a diagram of silicon wafer temperature distribution during semiconductor processing according to one embodiment.

FIG3 shows a top view of an exemplary pattern of the upper surface of an electrostatic chuck according to one embodiment.

FIG. 4 shows a top view of an exemplary pattern of the upper surface of an electrostatic chuck according to another embodiment.

Figures 5a-5b show schematic diagrams of the protruding portion on the upper surface of the electrostatic chuck.

FIG6 shows a top view of an exemplary pattern of the upper surface of an electrostatic chuck according to another embodiment.

FIG7 shows a schematic structural diagram of a capacitively coupled plasma (CCP) etching device according to an embodiment.

In order to make the content of the present invention more clear and easy to understand, the content of the present invention is further explained below in conjunction with the attached drawings of the specification. Of course, the present invention is not limited to the specific embodiment, and general replacements known to ordinary knowledgeable people in the technical field to which the present invention belongs are also covered within the scope of protection of the present invention.

It is necessary to maintain good temperature uniformity across the substrate during plasma processing. It is also desirable to consider the ability to adjust the temperature between the center and edge of the substrate during processing to compensate for non-uniformities caused by other processing processes or hardware conditions in the processing chamber. There are many ways to improve temperature uniformity and adjustability. One method is to construct multiple cooling liquid channels in the base. An alternative method is to construct multiple areas on the surface of the electrostatic chuck. The following briefly describes some factors that affect substrate temperature uniformity and corresponding means.

In order to control the temperature of the substrate being processed during etching, heat can be removed from the substrate by two main mechanisms:

(1) When the substrate is adsorbed by the electrostatic chuck, heat is transferred from the substrate to the electrostatic chuck through solid-solid contact. The physical contact between the back of the substrate and the top of the electrostatic chuck promotes heat conduction. Factors that affect this heat conduction are:

(A) Area between substrate and electrostatic chuck: The overlap area between substrate and electrostatic chuck consists of mechanical contact area and non-mechanical contact area. The surface of the electrostatic chuck usually includes one or more sealing strips to separate the helium between the substrate and the electrostatic chuck, and a stage (or stage points) to provide additional mechanical support points for the substrate placed on the electrostatic chuck. When the space between the substrate and the electrostatic chuck is filled with a gas medium such as helium, heat transfer from the substrate to the electrostatic chuck can pass through the mechanical contact area or the non-mechanical contact area.

(B) Roughness of the electrostatic chuck surface (Ra): A smaller Ra, i.e. a smoother surface, has a higher thermal conductivity between the substrate and the electrostatic chuck.

(C) The clamping voltage between the substrate and the DC electrode buried in the electrostatic chuck, which in turn determines the clamping force between the substrate and the electrostatic chuck. Combining the two factors in (B) and (C) can effectively be converted into the concept of contact pressure.

(2) When the substrate is electrostatically adsorbed by the electrostatic chuck, heat is transferred from the substrate to the electrostatic chuck through the heat-conductive gas between the back of the substrate and the top of the electrostatic chuck via solid-gas-solid contact.

Argon is commonly used in physical vapor deposition (PVD) applications, while helium is commonly used in etching applications. Reasons for using helium in etching applications include:

(I) Helium has the highest thermal conductivity of all gases except hydrogen (see Table 1). For safety reasons, hydrogen is generally avoided unless the benefits of using it outweigh its potential risks. In addition, hydrogen may produce harmful chemical reactions during etching processes. Due to its smaller atomic mass, hydrogen is also more difficult to pump with a turbo pump, so it will have a greater impact on pressure and the chemicals being processed.

(II) Helium is an inert gas and generally has little effect on the etching process. Although argon is also an inert gas, its atomic mass is much larger than that of helium, so it will have a greater impact on the auxiliary ions in the etching process.

Several factors affect the solid-gas-solid thermal conductivity, which process engineers can control during the etching process and design engineers can use when designing the electrostatic chuck function. These factors are:

(A) Overlap area between substrate and electrostatic chuck.

(B) Helium density between substrate and electrostatic chuck: The gas density can be controlled to a desired value by setting a specific gas pressure.

(Gas density is proportional to gas pressure: PV=nRT, where P, V, T are gas pressure, volume and temperature respectively; n is gas density; R is the ideal gas constant.)

(C) Mean free path of gas: When the mean free path of gas is greater than or equal to the gap between substrate and electrostatic chuck surface, the gas density factor is effective for thermal conductivity. Otherwise, thermal conductivity through the gas medium will reach saturation after reaching a certain gas pressure, which is related to the above gas density.

FIG1 shows a schematic diagram of a lower electrode component for a plasma processing device according to an embodiment of the present invention. The lower electrode component 100 is mainly composed of an electrostatic chuck 101 and a base 102. The electrostatic chuck 101 is bonded to the base 102 of the lower electrode through a bonding layer 103. The electrostatic chuck 101 carries a substrate 200 to be processed. The electrostatic chuck 101 is usually made of a semiconductor or insulating ceramic material, such as aluminum oxide or aluminum nitride. The base 102 is usually made of a conductive metal material, such as aluminum, stainless steel or titanium. Typically, radio frequency (RF) power is delivered to the pedestal 102 via the RF power supply 250 to excite the plasma.

The base 102 may include one or more embedded heating elements and a conduit 105 for a cooling fluid to control the lateral temperature distribution of the base 102. The conduit 105 may be fluidly coupled to a fluid source that circulates a temperature-regulated fluid through the conduit 105. The one or more embedded heating elements may be regulated by a heater power supply. In one embodiment, the conduit 105 and the one or more embedded heating elements may be used to control the temperature of the base 102 to heat and/or cool the electrostatic chuck 101 and the substrate 200 being processed. Multiple temperature sensors may be used to monitor the temperature of the electrostatic chuck and the heat transfer base 102, and the temperature sensors may be monitored using a controller.

One or more first gas channels 106 connected to an external gas source are provided in the lower electrode element 100. The first gas channels 106 are connected to one or more second gas channels 104 penetrating the electrostatic chuck 101 to form a gas pipeline. When the substrate 200 is processed, a back gas (e.g., helium) can be provided to the gas pipeline under controlled pressure to enhance heat transfer between the electrostatic chuck 101 and the substrate 200. The factors affecting the heat transfer between the back side of the substrate 200 and the electrostatic chuck 101 have been discussed above.

FIG2 shows a temperature distribution diagram of a silicon wafer during semiconductor processing according to an embodiment. Generally, the temperature of the edge of the substrate is higher than the temperature of the center of the substrate. In this embodiment, the temperature of the middle area between the center area and the edge area of the substrate is the lowest. In practice, it is desirable to reduce the temperature of the edge of the substrate to improve the uniformity of the temperature of the substrate. It is more advantageous to have the ability to adjust the temperature of the edge of the substrate to be higher, equal to, or lower than the center temperature of the substrate.

Two factors contribute to higher temperatures at the edge of the substrate:

(1) The substrate diameter is larger than the electrostatic chuck and hangs about 1-2 mm beyond the edge of the electrostatic chuck (as shown in section 210 in Figure 1). There is no physical contact between the suspended chip area and the electrostatic chuck, so heat cannot be effectively absorbed from the suspended area, resulting in a temperature increase.

(2) The helium pressure in the gas channel in the electrostatic chuck under the substrate is 10-80Torr, and the chamber pressure during the etching process ranges from 5-200mTorr. This means that the gas pressure outside the chip is reduced from 10-80Torr to 5-200mTorr. As the helium pressure decreases, the thermal conductivity decreases and the efficiency of absorbing heat from the substrate also decreases, resulting in an increase in temperature.

To overcome this drawback, multiple helium zones can be constructed on the surface of the electrostatic chuck. For example, a higher helium pressure can be applied to the outer zone to reduce the temperature of the edge of the substrate, while a lower helium pressure can be applied to the inner zone.

FIG3 shows a top view of an exemplary pattern of the upper surface of an electrostatic chuck according to an embodiment. The electrostatic chuck 300 is composed of aluminum nitride (AlN) or aluminum oxide (Al ₂ O ₃ ). The electrostatic chuck 300 may alternatively be composed of titanium oxide (TiO), titanium nitride (TiN), silicon carbide (SiC), or the like. A DC electrode may be buried in the electrostatic chuck 300 to absorb and fix the upper substrate by electrostatic induction. The electrostatic chuck 300 includes two regions: an inner region 310 and an outer region 320. In this embodiment, the inner region 310 is a circular region and the outer region 320 is an annular region. In the inner region 310, four gas channels 315 are provided. In the outer region 320, four gas channels 325 are also provided. For the purpose of illustration, only eight gas channels are shown. However, any number of gas channels may exist in the electrostatic chuck 300. A heat transfer gas, such as helium, is introduced into the gas channels 315 and 325 to absorb heat from the substrate. The inner region 310 corresponds to the central region of the substrate, and the outer region 320 corresponds to the edge region of the substrate.

The inner area 310 and the outer area 320 are separated by a sealing tape 311. The side of the sealing tape 311 is in close contact with the inner area 310 and the outer area 320, and the upper surface is flush with the upper surface of the electrostatic chuck 300 or the upper surface of the table, thereby separating the helium area between the substrate and the electrostatic chuck into two unconnected areas so that the heat transfer efficiency in each area can be independently adjusted. The sealing tape is made of an insulating material, such as silicone. An outer ring sealing tape 321 is also provided on the outer periphery of the outer area 320 of the electrostatic chuck to prevent the helium in the outer area 320 from diffusing into the processing chamber and to confine the helium in the outer area between the electrostatic chuck 300 and the substrate.

In one embodiment, the electrostatic chuck 300 corresponds to the electrostatic chuck 101 in FIG. 1 . The gas channels 315 and 325 correspond to the first gas channel 104 in FIG. 1 .

When the gas channel 325 in the outer region 320 is too close to the edge of the electrostatic chuck, the width of the bonding layer 103 may not be sufficient to reliably prevent the leakage of helium, so that helium leaks from the gap between the electrostatic chuck and the base to the edge of the electrostatic chuck and the cavity. For the electrostatic chuck with double helium zones, the position of the sealing band separating the inner zone from the outer zone is usually in the range of Φ200mm to Φ280mm, depending on the transition point of raising the temperature to the edge of the substrate. For some configurations and applications, the position where the temperature starts to rise is closer to the edge of the electrostatic chuck, which means that the outer zone should be designed to be narrower.

FIG4 shows a top view of an exemplary pattern of the upper surface of an electrostatic suction cup according to another embodiment. In this embodiment, the electrostatic suction cup 400 includes two regions: an inner region 410 and an outer region 420. The outer region 420 includes an annular region and a protrusion 450 protruding toward the center O of the electrostatic suction cup 400. In this embodiment, the protrusion 450 is semicircular. In other embodiments, the protrusion may also be a regular or irregular shape such as a triangle, a trapezoid, a rectangle, etc. A gas channel 425 is provided in the protrusion 450. This makes the gas channel 425 in the outer region 420 farther from the edge of the electrostatic chuck 400 than in FIG. 3 , so that the bonding layer 103 (in conjunction with FIG. 1 ) from the edge of the electrostatic chuck to the gas channel 425 has a sufficient width to provide a sealing effect to prevent gas leakage. In this way, the helium in the gas channel 425 will not leak from the bonding layer 103 to the edge of the electrostatic chuck 400 and the chamber. In this embodiment, the distance from the gas channel 425 in the outer region 420 to the center O is greater than the distance from the gas channel 415 in the inner region 410 to the center O. In other embodiments, the distance from the gas channel 425 in the outer region 420 to the center O is less than or equal to the distance from the gas channel 415 in the inner region 410 to the center O.

As mentioned above, the edge of a substrate being plasma treated is usually hotter than the center. By dividing the electrostatic chuck into two parts, each corresponding to a different area of the substrate, the temperature uniformity of the upper substrate can be adjusted by adjusting the characteristics of each part.

In one embodiment, the pressure of helium gas introduced into the gas channel 425 of the outer region 420 is greater than the pressure of helium gas introduced into the gas channel 415 of the inner region 410. Because the thermal conductivity is positively correlated with the gas pressure, when the pressure of helium gas introduced into the gas channel 425 of the outer region 420 is greater, the heat of the edge region of the substrate can be transferred to the electrostatic chuck and the base more quickly, thereby achieving the effect of regulating the uniformity of the temperature of the substrate. In addition, the sub-regions of the electrostatic chuck can not only be used to control the temperature uniformity of the substrate, but also can be used to adjust the temperature of each region of the substrate according to the needs of a specific process by independently setting the characteristics of each region. For example, the temperature of the edge area of the substrate can be greater than, equal to, or less than the center area of the substrate according to process requirements.

In one embodiment, the upper surface of the electrostatic chuck 400 also includes a terrace structure protruding upward. The surface of the electrostatic chuck 400 may have hundreds or thousands of terraces formed thereon. In some embodiments, the height of the terrace is between 2 microns and 200 microns and its size (such as diameter) is between 0.5 mm and 5 mm. The side walls of the terrace may be vertical or inclined. In one embodiment, each terrace has a rounded edge, that is, the edge of the terrace is rounded, and the substrate is in arc contact with the edge of the terrace, which can minimize the fragmentation of the terrace and reduce particle contamination on the back of the substrate. The rounded edge can also reduce or eliminate scratches on the back of the substrate caused by clamping. The terrace may also have a chamfered edge.

The inner and outer regions are separated by a sealing tape 411, the side of the sealing tape 411 is in close contact with the inner and outer regions, and the upper surface is flush with the upper surface of the platform of the electrostatic chuck 400, thereby separating the helium region between the substrate and the electrostatic chuck into two unconnected regions. The sealing tape is made of an insulating material, such as silicone. In another embodiment, the upper surface of the outer ring sealing tape 421 is flush with the upper surface of the platform of the electrostatic chuck 400.

The upper surface of the platform can be set into various shapes according to actual needs. Figures 5a and 5b show schematic diagrams of two forms of the upper surface of the electrostatic suction cup protruding from the platform. The upper surface of the platform can be circular (Figure 5a) or hexagonal (Figure 5b). In one embodiment, the upper surface of the platform 501 is dot-shaped, and its diameter is 0.5mm-3mm. The area of the upper surface of the platform 501 accounts for 5%-30% of the area of the upper surface of the entire electrostatic suction cup. In another embodiment, the upper surface of the platform 502 is hexagonal, and the area of its upper surface accounts for 20%-80% of the area of the upper surface of the entire electrostatic suction cup. The upper surface of the table is in direct contact with the substrate, and its contact area is a solid-solid heat transfer area. Therefore, the larger the area ratio of its upper surface, the better the heat transfer effect on the substrate. When the temperature of the edge area of the substrate needs to be lowered, a table as shown in FIG. 5b can be set in the outer area 420 of the electrostatic chuck 400, and a table as shown in FIG. 5a can be set in the inner area 410 of the electrostatic chuck 400. In other embodiments, the shape of the upper surface of the table is a rectangle, a triangle, an octagon, etc. According to different process requirements, the table in the inner and outer areas can be set with different upper surface area ratios to change the heat transfer coefficient of the substrate to the electrostatic chuck to control the temperature of the substrate.

The height of the platform can be set accordingly according to actual needs. In one embodiment, the height of the platform of the outer region 420 is lower than the height of the platform of the inner region 410. When the substrate is adsorbed on the electrostatic chuck, the back of the substrate is in close contact with the platform of the electrostatic chuck. When the substrate is processed, heat is transferred from the substrate to the lower electrode element. When the platform height is large, the heat transfer distance is large, and the temperature drop is also slow, so that the temperature drop in the inner region of the substrate is smaller than the temperature drop in the outer region of the substrate.

The upper surface roughness of the platform can also be set accordingly according to actual needs. In one embodiment, the upper surface roughness of the platform of the outer region 420 is less than the upper surface roughness of the platform of the inner region 410. Because the heat conduction between the substrate and the electrostatic chuck depends on the surface roughness Ra, the higher the surface roughness, the worse the heat transfer effect, so the surface roughness of the inner and outer regions can be selected according to the different thermal conductivity coefficients of the desired inner and outer regions. For example, in order to reduce the temperature of the edge area of the substrate, the upper surface roughness of the outer region 420 of the electrostatic chuck is set to be less than 3 micro inches, and the upper surface roughness of the inner region 410 of the electrostatic chuck is 4-8 micro inches.

FIG6 shows a top view of an exemplary pattern of the upper surface of an electrostatic suction cup according to another embodiment. In this embodiment, the electrostatic suction cup 600 includes three regions: a central region 610, a middle region 620, and an outer region 630. The outer region 630 includes an annular region and a protrusion 650 protruding toward the center O of the electrostatic suction cup 600. In this embodiment, the protrusion 650 is semicircular. In other embodiments, the protrusion may also be a regular or irregular shape such as a triangle, a trapezoid, a rectangle, etc. A gas channel 625 is provided in the protrusion 650. This makes the gas channel 425 in the outer region 630 farther from the edge of the electrostatic chuck 400, so that the bonding layer 103 has a sufficient width to provide a sealing effect to prevent gas leakage. In this way, the helium in the gas channel 625 will not leak from the bonding layer 103 to the edge of the electrostatic chuck 400 and the chamber. In this embodiment, the distance from the gas channel 635 in the outer region 630 to the center O is greater than the distance from the gas channel 625 in the middle region 620 to the center O. In other embodiments, the distance from the gas channel 635 in the outer region 630 to the center O is less than or equal to the distance from the gas channel 625 in the middle region 620 to the center O. In other embodiments, a gas channel is provided in the central region 610.

In one embodiment, the upper surface of the electrostatic suction cup 600 also includes a platform structure protruding upward. The surface of the electrostatic suction cup 600 may have hundreds or thousands of platforms formed thereon. The upper surface of the platform can be set to various shapes according to actual needs. The upper surface of the platform can be circular or hexagonal, or it can be other shapes such as rectangular, triangular, octagonal, etc. In one embodiment, the upper surface of the platform in the middle area 620 is dot-shaped, and its diameter is 0.5mm-3mm. The area of the upper surface of the platform accounts for 5%-30% of the upper surface area of the entire electrostatic suction cup. The upper surfaces of the platforms in the outer area 630 and the central area 610 are hexagonal, and the area of their upper surfaces accounts for 20%-80% of the upper surface area of the entire electrostatic suction cup. Such a setting can effectively improve the uniformity of silicon wafer temperature as shown in Figure 2.

In one embodiment, the roughness of the upper surface of the terrace of the outer region 630 is less than the roughness of the upper surface of the terrace of the middle region 620, and the roughness of the upper surface of the terrace of the central region 610 is less than the roughness of the upper surface of the terrace of the middle region 620.

The height of the platform can be set accordingly according to actual needs. In one embodiment, the height of the platform in the outer area 630 is lower than the height of the platform in the middle area 620, and the height of the platform in the central area 610 is lower than the height of the platform in the middle area 620.

It should be noted that the sub-areas of the electrostatic chuck can not only be used to control the temperature uniformity of the substrate, but also can be used to adjust the temperature of each area of the substrate according to the needs of a specific process through the independent setting of the characteristics of each area. For example, according to the process requirements, the temperature of the outer area of the substrate can be greater than, equal to, or less than the middle area of the substrate, or the temperature of the central area of the substrate can be greater than, equal to, or less than the middle area of the substrate.

FIG7 shows a schematic diagram of the structure of a capacitively coupled plasma (CCP) etching device, which is a device for etching by generating plasma in a reaction chamber by capacitive coupling using a radio frequency power source applied to a plate. The device includes a vacuum reaction chamber 700, which includes a substantially cylindrical reaction chamber side wall 701 made of a metal material, and an opening 702 is provided on the reaction chamber side wall for accommodating the entry and exit of a substrate. A gas shower head 720 and a base 710 disposed opposite to the gas shower head 720 are disposed in the vacuum reaction chamber 700. The gas shower head 720 is connected to a gas supply device 725 for delivering reaction gas to the vacuum reaction chamber 700 and serving as an upper electrode of the vacuum reaction chamber 700. An electrostatic chuck 712 is disposed above the base 710 and serves as a lower electrode of the vacuum reaction chamber 700. A reaction area is formed between the upper electrode and the lower electrode. At least one RF power source 750 is applied to one of the upper electrode or the lower electrode through a matching network 752, generating a RF electric field between the upper electrode and the lower electrode to dissociate the reaction gas into plasma. The plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above active particles can undergo a variety of physical and chemical reactions with the surface of the substrate to be processed, so that the morphology of the substrate surface changes, that is, the etching process is completed. An exhaust pump 740 is also provided below the vacuum reaction chamber 700 to discharge the reaction byproducts from the vacuum reaction chamber 700 and maintain the vacuum environment of the vacuum reaction chamber 700.

An electrostatic electrode 713 is disposed inside the electrostatic suction cup 712 to generate electrostatic suction force to support and fix the substrate W to be processed during the manufacturing process. In one or more embodiments, the electrostatic suction cup 712 is the electrostatic suction cup 400 or the electrostatic suction cup 600 in FIG. 4 or FIG. 6.

A heating device 714 is provided below the electrostatic chuck 712 to control the temperature of the substrate during the manufacturing process. A focusing ring 732 and an edge ring 734 are provided around the base, and the focusing ring 732 and the edge ring 734 are used to adjust the electric field or temperature distribution around the substrate W to improve the uniformity of the substrate W processing. A plasma confinement ring 735 is arranged around the edge ring 734. An exhaust channel is arranged on the plasma confinement ring 735. By reasonably setting the depth-width ratio of the exhaust channel, the plasma is confined in the reaction area between the upper and lower electrodes while the reaction gas is exhausted, so as to prevent the plasma from leaking to the non-reaction area and causing damage to the components in the non-reaction area. A middle ground ring 736 is provided below the plasma confinement ring 735, and the middle ground ring 736 is used to provide an electric field shield for the plasma confinement ring 735; a lower ground ring 737 is provided below the middle ground ring 736, and the middle ground ring 736 and the lower ground ring 737 are electrically connected to form an RF ground loop in the vacuum reaction chamber 700. A shield ring 738 is provided between the lower ground ring 737 and the base, and is used to shield the RF signal applied to the base in the base, so as to achieve electrical isolation between the base and the lower ground ring 737.

In other embodiments, other types of plasma etching devices may also be used, such as inductively coupled plasma etching devices, electron cyclotron resonance plasma etching devices, etc.

Although the present invention has been disclosed as above with preferred embodiments, the embodiments described are only for the purpose of illustration and are not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make some modifications and improvements without departing from the spirit and scope of the present invention. The scope of protection claimed by the present invention shall be subject to the scope of the patent application.

400: Electrostatic suction cup

410: Inner area

411: Sealing tape

420: External area

421: Outer ring sealing belt

415,425: Gas channel

450: protrusion

O: Center of circle

Claims (18)

An electrostatic chuck for a plasma processing device, the electrostatic chuck comprising: a plurality of regions, a first region of the plurality of regions comprising a protrusion, the protrusion protruding toward the center of the electrostatic chuck; and a first vent hole, the first vent hole being disposed in the protrusion. According to the electrostatic suction cup described in claim 1, the electrostatic suction cup further includes a sealing tape, which divides the electrostatic suction cup into the multiple areas. According to the electrostatic suction cup described in claim 2, the electrostatic suction cup further includes an outer ring sealing belt arranged on the outer periphery of the electrostatic suction cup. According to the electrostatic suction cup described in claim 2, the sealing tape divides the electrostatic suction cup into two regions: an outer region and an inner region, the outer region includes the outer annular portion of the electrostatic suction cup and the protrusion protruding toward the center of the electrostatic suction cup, and the inner region is the region of the electrostatic suction cup other than the outer region; the first vent is provided in the protrusion, and the electrostatic suction cup further includes a second vent, which is provided in the inner region of the electrostatic suction cup. The electrostatic chuck according to claim 4, wherein the gas pressure in the first vent hole is greater than the gas pressure in the second vent hole. An electrostatic chuck according to claim 4, wherein the area of the outer region is smaller than the area of the inner region. According to the electrostatic suction cup described in claim 4, the upper surface of the electrostatic suction cup has a platform protruding upward, and the ratio of the upper surface area of the platform in the outer region to the entire area of the outer region is greater than the ratio of the upper surface area of the platform in the inner region to the entire area of the inner region. The electrostatic chuck according to claim 7, wherein the sealing tape is flush with the upper surface of the platform of the electrostatic chuck. The electrostatic chuck according to claim 7, wherein the roughness of the upper surface of the platform in the outer region is less than the roughness of the upper surface of the platform in the inner region. According to the electrostatic chuck described in claim 7, the shape of the upper surface of the platform is any one of the following: circular, hexagonal, rectangular, and triangular. The electrostatic chuck according to claim 7, wherein the upper surface of the platform in the outer region is hexagonal and the upper surface of the platform in the inner region is circular. The electrostatic chuck according to claim 7, wherein the height of the platform in the outer region is lower than the height of the platform in the inner region. According to the electrostatic suction cup described in claim 2, the sealing belt divides the electrostatic suction cup into three areas: an outer area, a middle area and a central area, wherein the outer area includes the outer annular portion of the electrostatic suction cup and the protrusion protruding toward the center of the electrostatic suction cup, and the first vent is arranged in the protrusion; the electrostatic suction cup also includes a third vent, and the third vent is arranged in the middle area of the electrostatic suction cup. The electrostatic suction cup according to claim 13, wherein the upper surface of the electrostatic suction cup has a platform protruding upward, the ratio of the upper surface area of the platform in the outer region to the entire area of the outer region is greater than the ratio of the upper surface area of the platform in the middle region to the entire area of the middle region, and the ratio of the upper surface area of the platform in the central region to the entire area of the central region is greater than the ratio of the upper surface area of the platform in the middle region to the entire area of the middle region. The electrostatic chuck according to claim 14, wherein the roughness of the upper surface of the terrace in the outer region is less than the roughness of the upper surface of the terrace in the middle region, and the roughness of the upper surface of the terrace in the central region is less than the roughness of the upper surface of the terrace in the middle region. The electrostatic chuck according to claim 14, wherein the height of the terrace in the outer region is lower than the height of the terrace in the middle region, and the height of the terrace in the central region is lower than the height of the terrace in the middle region. A lower electrode element for a plasma processing device, comprising: an electrostatic chuck according to any one of claims 1 to 16, used to carry a substrate placed thereon; a base, disposed below the electrostatic chuck; and a bonding layer, disposed between the electrostatic chuck and the base, to bond the electrostatic chuck and the base. A plasma processing device comprises: a reaction chamber; a lower electrode element according to claim 17, the lower electrode element is arranged in the reaction chamber, and a substrate to be processed is carried on the lower electrode element; and a gas supply device, which provides reaction gas to the reaction chamber to generate plasma to process the substrate.