TWM622433U - Lower electrode component and plasma processing device - Google Patents

Abstract

The present invention provides a lower electrode assembly and a plasma processing device where it is located. The present invention divides the gap between the edge ring assembly and the base into several parts by arranging a plurality of protection rings between the base and the edge ring assembly. A smaller gap and a protective layer outside the susceptor prevent the plasma above the substrate and the focus ring from leaking into the gap between the susceptor and the edge ring assembly, preventing the plasma from corroding the susceptor and reducing the The possibility of arc discharge that may occur in the lower electrode assembly, and the upward extension after arc discharge occurs under the blocking gap, effectively ensures the safety of the use of the lower electrode assembly.

Description

Lower electrode assembly and plasma processing device

The present invention relates to the technical field of plasma etching, and in particular, to the technical field of plasma processing for preventing arcs in the lower electrode assembly under high radio frequency power.

Micromachining of semiconductor substrates or substrates is a well-known technique that can be used to fabricate, for example, semiconductors, flat panel displays, light emitting diodes (LEDs), solar cells, and the like. An important step in microfabrication is the plasma treatment process step, which is performed inside a reaction chamber into which process gases are fed. A radio frequency source is inductively and/or capacitively coupled into the interior of the reaction chamber to excite the process gas to form and maintain the plasma. Inside the reaction chamber, the exposed substrate is supported by the lower electrode assembly and fixed in a fixed position by a certain clamping force, so as to ensure the safety of the substrate in the process and the high yield of processing.

The lower electrode assembly includes not only an electrostatic chuck for fixing the substrate and a base for supporting the electrostatic chuck, but also an edge ring assembly surrounding the base. During the process of the substrate, the lower electrode assembly is used for supporting The fixed substrate is also used to control the temperature and electric field distribution of the substrate.

In the prior art, the commonly used material of the base is aluminum, and the material of the dielectric ring surrounding the periphery of the base is usually a ceramic material. A certain space should be set between the dielectric ring and the base to accommodate thermal expansion and contraction of the base.

As the processing precision of the substrate becomes higher and higher, the RF power applied to the reaction chamber becomes larger and larger. High RF power can easily generate arc discharge in the small space in the reaction chamber, damage the base and its peripheral components, and seriously threaten the stability and safety of the electrode assembly. RF applied power and substrate processing uniformity requirements.

In order to solve the above technical problems, the present invention provides a lower electrode assembly for carrying the substrate to be processed, including:

a base, the base includes a base body and a step portion extending outward from the base body;

an electrostatic chuck located above the base;

an edge ring assembly, which is arranged around the base and/or the electrostatic chuck, and is provided with a gap with the base and/or the electrostatic chuck;

The gap is provided with a first protection ring, the first protection ring is arranged around the junction of the base and the electrostatic chuck, the gap is provided with a second protection ring, and the second protection ring is located in the first protection ring. Below a guard ring.

Optionally, a protective layer is provided on the outer side of the base.

Optionally, the protective layer is an alumina polystyrene composite material or a yttrium oxide material.

Optionally, the second protection ring is located at a corner of the step portion.

Optionally, at least a part of the second protection ring abuts against the base body and the edge ring assembly.

Optionally, the gap is provided with a third protection ring, the third protection ring is located between the first protection ring and the second protection ring, and at least a part of the third protection ring is connected to the base The body and the edge ring assembly abut against each other.

Optionally, a groove is provided at the contact between the second protection ring and/or the third protection ring and the base body and/or the edge ring assembly, and the cross-section of the groove is an arc or a frame. shape.

Optionally, the first guard ring, the second guard ring and the third guard ring are made of plasma corrosion resistant materials.

Optionally, the first protection ring, the second protection ring and the third protection ring are polymer materials.

Optionally, the first protection ring, the second protection ring and the third protection ring are fluororubber or perfluororubber series.

Further, the present invention also discloses a plasma processing apparatus, which includes a vacuum reaction chamber, and a lower electrode assembly is arranged in the vacuum reaction chamber, and the lower electrode assembly includes the above-mentioned features.

The advantages of the present invention are: the present invention provides a plasma corrosion-resistant lower electrode assembly and a plasma processing device. By arranging a plurality of protection rings between the base and the edge ring assembly, the connection between the base and the edge ring assembly is formed. The gap between them is divided into a plurality of smaller gaps, which prevents the plasma above the substrate and the focus ring from leaking into the gap between the susceptor and the edge ring assembly, prevents the plasma from corroding the susceptor, and reduces the possibility of the lower electrode assembly. The possibility of arc discharge occurs, and the upward extension after arc discharge occurs under the blocking gap effectively ensures the safety of the lower electrode assembly.

In order to make the purpose, technical solutions and advantages of this creative embodiment more clear, the technical solutions in this creative embodiment will be clearly and completely described below with reference to the accompanying drawings in this creative embodiment. Obviously, the described embodiment It is a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments in this creation, all other embodiments obtained by persons with ordinary knowledge in the technical field to which this case belongs without creative work, fall within the scope of protection of this creation.

FIG. 1 shows a schematic diagram of a capacitively coupled plasma processing apparatus, which includes a vacuum-pumpable reaction chamber 100 surrounded by an outer wall 10 . The reaction chamber 100 is used for processing the substrate 103 . The inside of the reaction chamber includes a lower electrode assembly, which is used for supporting the substrate and controlling factors affecting the processing of the substrate, such as the temperature of the substrate and the electric field. The lower electrode assembly includes a base 101 for carrying the electrostatic chuck 102, the base 101 is provided with a temperature control device, which is used to realize the temperature control of the upper substrate, the electrostatic chuck 102 is used for carrying the substrate 103, and the electrostatic clamp A DC electrode is arranged inside the disk, and a DC adsorption is generated between the backside of the substrate and the bearing surface of the electrostatic chuck by the DC electrode to realize the fixation of the substrate. An edge ring assembly 20 is arranged around the periphery of the base and the electrostatic chuck for adjusting the temperature and electric field distribution in the edge region of the substrate. A plasma confinement ring 108 is provided around the edge ring assembly 20, between the edge ring assembly 20 and the sidewall of the reaction chamber, for confining the plasma to the reaction area while allowing gas to pass through; a grounding ring 109, located in the plasma confinement ring Below, the role is to provide electric field shielding to avoid plasma leakage. The bias RF power source 125 usually applies a bias RF signal to the lower electrode assembly for controlling the bombardment direction of the plasma. The lower electrode assembly disclosed in the present invention can be used in a capacitively coupled plasma processing apparatus as shown in FIG. 1 .

In the capacitively coupled plasma processing apparatus shown in FIG. 1, in addition to the lower electrode assembly, it also includes an upper electrode assembly, and the upper electrode assembly includes a gas shower head 30 for introducing the process gas from the gas supply device 110 into the reaction chamber. A high-frequency radio frequency power supply 145 applies a high-frequency radio frequency signal to at least one of the upper electrode assembly or the lower electrode assembly through the high-frequency radio frequency matching 146 to form a radio frequency between the upper electrode assembly and the lower electrode assembly The electric field excites the process gas in the reaction chamber into plasma, and realizes the treatment of the substrate to be treated by the plasma.

Figure 2 shows a schematic structural diagram of a partial lower electrode assembly. In the structure shown in the figure, the lower electrode assembly includes: a focus ring 201, which is arranged around the base 101 and/or the electrostatic chuck 102 and the substrate 103, and is used for Adjust the temperature and electric field distribution of the edge area of the substrate 103; a dielectric ring 202 is arranged under the focus ring 201, and the dielectric ring 202 is used to maintain the potential difference between the focus ring 201 and the base 101, and at the same time adjust the temperature of the focus ring 201 . A first protection ring 104 is sleeved between the base 101 and the dielectric ring 202 , and the first protection ring 104 is made of plasma corrosion resistant material, which is usually a polymer material such as fluororubber or perfluororubber 25 series.

In the present invention, the material of the base 101 is usually a conductive metal material, such as aluminum, and the dielectric ring 202 surrounding the base is usually a ceramic material, preferably a high thermal conductivity ceramic material, which can also be an Al2O3 material. The thermal expansion coefficients of the base 101 and the dielectric ring 202 are different. To avoid extrusion of the components due to heat, a certain gap 105 needs to be set between the dielectric ring 202 and the base 101 during installation. As the processing precision of the substrate becomes higher and higher, the RF power applied to the reaction chamber becomes larger and larger. High RF power can easily generate arc discharge in a small space in the reaction chamber, damage the pedestal and its peripheral components, and seriously threaten the stability and safety of the electrode assembly, especially at the bottom of the pedestal, as shown in the dotted line in Figure 1. As shown, there is usually a screw hole 1013 for cooperating with the screw to play a fixing role, and it is easier to collect electric charges at the edge of the screw hole 1013, resulting in a high arc discharge location.

In this embodiment, the base 101 includes a base body 1011 and a stepped portion 1012 extending outward from the base body 1011 . The dielectric ring 202 can be assembled by its own gravity or external pressure. The 202 is arranged on the step portion 1012 of the base 101, and further forms a gap 105 with the base body 1011 to accommodate the thermal expansion and contraction of the components. The first guard ring 104 is disposed in the gap 105 , the first guard ring 104 surrounds the base 101 and the periphery of the electrostatic chuck 102 , and at least partially abuts against the dielectric ring 202 . It can prevent the plasma from bombarding the connection layer between the electrostatic chuck and the base 101, and can further prevent the plasma from entering the gap 105, thereby reducing the possibility of arc discharge. The second guard ring 1041 is disposed below the first guard ring 104 in the gap 105 . According to the principle of arc discharge, under the premise of the same air pressure and applied electric field, the larger the gas diffusion space, the easier it is to generate arc discharge. It can effectively reduce the probability of arc discharge and improve the safe voltage working range of the lower electrode assembly. In the preferred embodiment, the second protection ring 1041 is arranged at the corner of the stepped portion 1012, which further compresses the vicinity of the screw hole 1013 on the stepped portion 1012. The space of the gap can significantly reduce the probability of arc discharge near the screw hole 1013 at the high arc occurrence position. Even if arc discharge occurs there, the second protection ring 1041 can also become a barrier for the arc to extend upward, preventing the arc from rising along the gap 105 and damage. Substrate 103 . At the same time, the first protection ring 104 is located between the base 101 and the focus ring 201, so that the base 101 and the focus ring 201 are electrically isolated. At the same time, the first protection ring 104 is used to prevent the plasma from passing through the focus ring and the base Or the gap between the electrostatic chucks enters the gap 105 . Further, the outer side of the base 101 is provided with a protective layer 106, which is a plasma corrosion-resistant material, usually an alumina material, or a yttrium oxide material, which can prevent the leaked plasma from corroding the base 101 , which further improves the use safety of the lower electrode assembly. Due to the limitation of the process, when the protective layer 106 is formed at the edge of the screw hole 1013 of the step portion 1012, the thickness and uniformity are lower than those of the other parts of the base 101. The metal part of the seat 101 is more easily exposed, which also makes arcing more likely to occur there.

FIG. 3 shows a schematic diagram of a lower electrode assembly of another embodiment. For the sake of clarity and conciseness, the same components as above are described with the same reference numerals. In the present embodiment, a third guard ring 1042 is set in the gap 105, between the first guard ring 104 and the second guard ring 1041, and the gap between the dielectric ring and the base is divided into three, so as to further It prevents the gas from entering the gap below, and at the same time becomes a second barrier to prevent the arc discharge from occurring near the screw hole 1013 of the stepped portion and extending upward. In a preferred embodiment, the part of the base body 1011 in contact with the second protection ring 1041 and/or the third protection ring 1042 is provided with a groove for fixing the position of the protection ring. The contact area of the base body has a better isolation effect. In a more preferred embodiment, grooves are also provided at positions corresponding to the dielectric ring 202 and the second guard ring 1041 and/or the third guard ring 1042 , and the cross-section of the groove may be arc-shaped or frame-shaped. The second guard ring 1041 and the third guard ring 1042 may or may not be in contact with the dielectric ring 202, but when they are in contact with the dielectric ring 202 or are in contact with the dielectric ring 202 due to thermal expansion during operation, the Better effect of preventing arc discharge.

Optionally, a heat conduction layer is arranged between the focus ring 201 and the dielectric ring 202 , and/or a heat conduction layer is arranged between the dielectric ring 202 and the base 101 , so as to improve the temperature conduction capability of the focus ring 201 . In other embodiments, the dielectric ring 202 can also be disposed above other supporting components capable of independent temperature control, so as to realize independent control of the temperature of the focus ring 201 different from that of the substrate 103 .

The lower electrode assembly described above can also be used in the inductively coupled plasma plasma processing apparatus as shown in FIG. 4. In this embodiment, the lower electrode assembly has the structure as described above, which will not be repeated here. , in addition, an insulating window 130 is arranged above the reaction chamber, an inductive coil 140 is arranged above the insulating window, a high-frequency radio frequency power supply 145 applies a radio frequency signal to the inductive coil 140, and the inductive coil 140 generates an alternating magnetic field, inside the reaction chamber An alternating electric field is induced to realize the plasma dissociation of the process gas entering the reaction chamber. In this embodiment, the process gas can be injected into the reaction chamber from the side wall of the reaction chamber, or a gas injection port can be provided on the insulating window to accommodate the process gas to enter. Bias RF power 125 is applied to the lower electrode assembly via a bias RF match 126 for controlling the energy distribution of the plasma.

In this invention, by arranging a plurality of protective rings between the base and the edge ring assembly, the gap between the edge ring assembly and the base is divided into several smaller gaps, and a protective layer is arranged on the outside of the base to avoid the Plasma above the substrate and focus ring leaks into the gap between the susceptor and the edge ring assembly, preventing the plasma from corroding the susceptor, reducing the likelihood of arcing that could occur in the lower electrode assembly, and blocking the occurrence below the gap The upward extension after arc discharge effectively ensures the safety of the lower electrode assembly.

The lower electrode assembly disclosed in the present invention is not limited to be applied to the plasma processing apparatuses of the above two embodiments, and can also be applied to other plasma processing apparatuses, which will not be repeated here.

Although the content of the present creation has been described in detail by the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present creation. Various modifications and substitutions to the present invention will be apparent to those skilled in the art upon reading the foregoing. Therefore, the protection scope of this creation should be limited by the scope of the appended patent application.

10: outer wall 20: Edge Ring Assembly 30: Gas shower head 100: reaction chamber 101: Pedestal 102: Electrostatic chuck 103: Substrate 104: The first guard ring 105: Clearance 106: Protective layer 108: Plasma Confinement Ring 109: Ground Ring 110: Gas supply device 125: Bias RF power supply 126: Bias RF Matching 130: Insulation window 140: Inductor coil 145: High Frequency RF Power Supply 146: High Frequency RF Matching 201: Focus Ring 202: Dielectric Ring 1011: base body 1012: Steps 1013: Screw holes 1041: Second guard ring 1042: Third Protection Ring

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the accompanying drawings used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present creation. For those with ordinary knowledge in the technical field to which this case belongs, other drawings can also be obtained based on these drawings without any creative effort.

Figure 1 shows a schematic structural diagram of a capacitively coupled plasma processing device; Figure 2 shows a schematic structural diagram of a partial lower electrode assembly; FIG. 3 shows a schematic structural diagram of a partial lower electrode assembly according to another embodiment; FIG. 4 shows a schematic structural diagram of an inductively coupled plasma processing apparatus.

10: outer wall

20: Edge Ring Assembly

30: Gas shower head

100: reaction chamber

101: Pedestal

102: Electrostatic chuck

103: Substrate

108: Plasma Confinement Ring

109: Ground Ring

110: Gas supply device

125: Bias RF power supply

126: Bias RF Matching

145: High Frequency RF Power Supply

146: High Frequency RF Matching

Claims (11)

A lower electrode assembly for carrying a substrate to be processed, comprising: a base, the base includes a base body and a step portion extending outward from the base body; an electrostatic chuck located above the base; an edge ring assembly, which is arranged around the base and/or the electrostatic chuck, and is provided with a gap between the base and/or the electrostatic chuck; The gap is provided with a first protection ring, the first protection ring is arranged around the junction of the base and the electrostatic chuck, and the gap is provided with a second protection ring, and the second protection ring is located below the first protection ring. The lower electrode assembly according to claim 1, wherein: the outer side of the base is provided with a protective layer. The lower power level assembly according to claim 2, wherein: the protective layer is an aluminum oxide and/or yttrium oxide material layer. The lower electrode assembly according to claim 1, wherein: the second guard ring is located at the corner of the step portion. The lower electrode assembly according to claim 1, wherein at least a part of the second protection ring abuts against the base body and the edge ring assembly. The lower electrode assembly of claim 1, wherein: the gap is provided with a third guard ring, the third guard ring is located between the first guard ring and the second guard ring, and at least a part of the third guard ring is connected to the The base body and the edge ring assembly abut against each other. The lower electrode assembly according to claim 6, wherein: a groove is provided at the contact of the second guard ring and/or the third guard ring with the base body and/or the edge ring assembly, and the groove has a cross section of Arc or frame. The lower electrode assembly according to claim 6, wherein: the first guard ring, the second guard ring and the third guard ring are made of plasma corrosion resistant materials. The lower electrode assembly according to claim 6, wherein: the first guard ring, the second guard ring and the third guard ring are made of polymer materials. The lower electrode assembly according to claim 6, wherein: the first protection ring, the second protection ring and the third protection ring are fluororubber or perfluororubber series. A plasma processing apparatus includes a vacuum processing chamber, wherein: the vacuum processing chamber includes the lower electrode assembly as claimed in claims 1 to 10.

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