TWI777462B - Lower electrode assembly, installation method thereof, and plasma processing device - Google Patents

Abstract

The invention provides a lower electrode assembly, an installation method thereof, and a plasma processing device using the same. , and a protective ring is set between the dielectric ring and the base, and a protective layer is set on the outside of the base to prevent the plasma above the base and the focusing ring from leaking into the gap between the base and the edge ring assembly, preventing The plasma corrodes the base, reduces the possibility of arc discharge of the lower electrode assembly, and effectively ensures the safety of the use of the lower electrode assembly.

Description

Lower electrode assembly, installation method thereof, and plasma processing device

The invention relates to the technical field of plasma etching, and in particular, to a lower electrode assembly that can prevent arcing under high radio frequency power.

Micromachining of semiconductor substrates or substrates is a well-known technique that can be used to manufacture, 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 gases 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 during 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. It supports and fixes the substrate, and is further 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 insert ring surrounding the periphery of the base is usually a ceramic material. A certain space should be set between the ring and the base to accommodate the 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 a small space in the reaction chamber, which will damage the base and its peripheral components, and seriously threaten the stability and safety of the electrode assembly. Therefore, a solution is urgently needed to adapt Increasing 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, which is located in above the base; and an edge ring assembly disposed around the base and the electrostatic chuck, the edge ring assembly comprising: a focus ring disposed around the base and/or the electrostatic chuck, and a dielectric ring below the focus ring around the base, the dielectric ring includes a dielectric ring body and an extension part extending from the dielectric ring body to the base direction, a gap is set between the dielectric ring and the base, and the step part cooperates with the extension part of the dielectric ring The gap is divided into at least a first gap and a second gap.

Preferably, the outer side of the base is provided with a protective layer.

Preferably, the protective layer is an alumina polystyrene composite material.

Preferably, a protection ring is further surrounded between the edge ring assembly and the base and/or the electrostatic chuck, and at least a part of the protection ring abuts against the dielectric ring and the base.

Preferably, at least a part of the guard ring abuts against the base and the electrostatic chuck.

Preferably, the guard ring is a material resistant to plasma corrosion.

Preferably, the guard ring is a polymer material.

Preferably, the protection ring is of fluororubber or perfluororubber series.

Preferably, the protection ring is arranged above the step portion.

Preferably, the dielectric ring is made of high thermal conductivity ceramic material or alumina material.

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

Further, the present invention further discloses a method for installing a lower electrode assembly, comprising the following steps: providing a base with an electrostatic chuck, the base comprising a base body and a step portion extending outward from the base body, providing an intermediate The dielectric ring includes a dielectric ring body and an extension extending toward the base. The extension of the dielectric ring is placed on the stepped part of the base. There is a gap between the dielectric ring and the base. The part cooperates with the extension part of the dielectric ring to divide the gap into a first gap and a second gap; a focus ring is arranged above the dielectric ring.

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

Preferably, a protective ring is arranged around the periphery of the electrostatic chuck and the base, and the focusing ring at least partially covers the protective ring.

Preferably, the guard ring at least partially abuts against the base and the electrostatic chuck.

Preferably, the guard ring at least partially abuts against the dielectric ring.

The advantages of the present invention are: the present invention provides a plasma corrosion-resistant lower electrode assembly and an installation method thereof. The small gap prevents the plasma above the substrate and focus ring from leaking into the gap between the susceptor and the edge ring assembly, while reducing the size of a single gap and reducing the possibility of arcing that may occur in the lower electrode assembly It can effectively ensure the safety of the lower electrode assembly.

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the illustrated embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those with ordinary knowledge in the art without creative efforts shall fall within the protection scope of the present invention.

FIG. 1 shows a schematic diagram of a capacitively coupled plasma processing apparatus, including a vacuum-pumpable reaction chamber 100 surrounded by an outer wall 10 . The reaction chamber 100 is used for processing the substrate 103 . The interior of the reaction chamber 100 includes a lower electrode assembly, which is used to support the substrate 103 while controlling the temperature and electric field of the substrate 103 and other factors affecting the processing of the substrate 103 . The lower electrode assembly includes a base 101 for carrying the electrostatic chuck 102 , and a temperature control device is arranged in the base 101 for controlling the temperature of the upper substrate 103 . The electrostatic chuck 102 is used to carry the substrate 103. A DC electrode is arranged inside the electrostatic chuck 102, and a DC adsorption is generated between the back of the substrate 103 and the bearing surface of the electrostatic chuck 102 through the DC electrode to realize the fixation of the substrate 103. 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 103 . A plasma confinement ring 108 is disposed around the edge ring assembly 20, between the edge ring assembly 20 and the sidewall of the reaction chamber 100, for confining the plasma to the reaction area while allowing gas to pass through. A ground ring 109, located below the plasma confinement ring 108, is used to provide electric field shielding to avoid plasma leakage. The bias RF power supply usually applies a bias RF signal to the lower electrode assembly to control 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, an upper electrode assembly is further included, and the upper electrode assembly includes a gas shower head 30 for introducing the process gas in the gas supply device into the reaction chamber 100 . A high-frequency radio frequency power source is used to apply a high-frequency radio frequency signal to at least one of the upper electrode assembly and the lower electrode assembly, so as to form a radio frequency electric field between the upper electrode assembly and the lower electrode assembly, and excite the process gas in the reaction chamber 100 into a plasma, and further realizes the processing of the substrate 103 to be processed by the plasma.

FIG. 2 shows a schematic structural diagram of a partial lower electrode assembly. In the structure shown in FIG. 2, 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 The temperature and electric field distribution, etc. of the edge region of the substrate 103 are adjusted. A dielectric ring 202 is disposed below 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 adjust the temperature of the focus ring 201 . A protection ring 104 is sleeved between the base 101 and the dielectric ring 202 , and the protection ring 104 is made of plasma corrosion-resistant material, which is usually a polymer material such as fluororubber or perfluororubber series.

In the embodiment of 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 101 is usually a ceramic material, preferably a high thermal conductivity ceramic material, which can also be Al ₂ O ₃ material. Since the thermal expansion coefficients of the base 101 and the dielectric ring 202 are different, in order to avoid extrusion of the components when heated, a certain gap 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, which will damage the base 101 and its peripheral components, and seriously threaten the stability and safety of the electrode assembly.

In this embodiment, the base 101 includes a base body 1011 and a stepped portion 1012 extending outward from the base body 1011 , and the dielectric ring 202 includes a dielectric ring body 2021 and a base 101 extending from the dielectric ring body 2021 to the base 101 . The extension part 2022, the step part 1012 and the extension part 2022 cooperate, and the close contact between the extension part 2022 of the dielectric ring 202 and the step part 1012 of the base 101 can be achieved through the gravity of the dielectric ring 202 itself or the external pressure. , thereby dividing the gap between the base 101 and the dielectric ring 202 into a first gap 1051 and a second gap 1052 . The guard ring 104 is disposed in the first gap 1051 , the 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 . The guard ring 104 can prevent the plasma from bombarding the connection between the electrostatic chuck 102 and the base 101, and can further prevent the plasma from entering the second gap 1052, thereby reducing the possibility of arcing. According to the principle of arc discharge, under the premise of the same gas pressure and applied electric field, the larger the gas diffusion space, the easier it is to generate arc discharge. The space for gas diffusion can effectively reduce the probability of arc discharge and improve the safe voltage working range of the lower electrode assembly. Meanwhile, a part of the guard 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. Meanwhile, the protection ring 104 is used to prevent plasma from entering the first gap 1051 through the gap between the focus ring 201 and the base 101 or the electrostatic chuck 102 . Further, the outer side of the base 101 is provided with a protective layer 106, which is a material resistant to plasma corrosion, usually an alumina material, or a yttrium oxide material, which can prevent the leaked plasma from corroding the base 101, and further improves the Safe use of the lower electrode assembly.

The shape of the guard ring 104 can be changed in various ways. In the embodiment shown in FIG. 2 , the guard ring 104 extends along the direction of the first gap 1051 , and the extension portion 2022 of the dielectric ring 202 and a partial area of the guard ring 104 abut against each other. , which is used to prevent gas from entering the second gap 1052 , thereby preventing arc discharge from occurring in the second gap 1052 . In other embodiments, guard ring 104 and focus ring 201 and dielectric ring 202 may have other matching shapes.

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 will be described with the same reference numerals. In this embodiment, the base 101 includes at least two stepped portions 1013 and 1014 , and the extension portion 2022 of the dielectric ring 202 facing the base 101 is in close contact with the at least one stepped portion 1013 and 1014 , connecting the dielectric ring 202 to the base. The gaps between the seats 101 are divided into two or more to further prevent gas from entering the gaps below. In this embodiment, the extending portion 2022 of the focus ring 201 facing the base 101 at least partially abuts against the upper surface of the protection ring 104 , thereby achieving air path blocking of the gap between the focus ring 201 and the base 101 , to avoid arc discharge caused by gas entering the gap below.

Preferably, 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 may also be disposed above other supporting components capable of independent temperature control, so as to realize independent temperature control of the focus ring 201 which is different from that of the substrate 103 .

Preferably, the present invention further provides a method for installing a lower electrode assembly, comprising the following steps: providing a base 101 with an electrostatic chuck 102, the base 101 comprising a base body 1011 and extending outward from the base body 1011 A dielectric ring 202 is provided on the stepped portion 1012 of the If there is a gap, the extension portion 2022 of the dielectric ring 202 is placed on the stepped portion 1012 of the base 101, and a downward pressure can be selectively applied to the dielectric ring 202 to further improve the tightness between the extension portion 2022 and the stepped portion 1012. sex. The step portion 1012 cooperates with the extension portion 2022 to separate the gap into a first gap 1051 and a second gap 1052. A guard ring 104 is placed in the first gap 1051. The guard ring 104 is made of a material resistant to plasma corrosion, which is usually a polymer material such as For fluororubber or perfluororubber series, the protection ring 104 can also be arranged around the base 101 and the electrostatic chuck 102 before the dielectric ring 202 , and then the dielectric ring 202 can be arranged around the base 101 and the protection ring 104 . A focus ring 201 is disposed above the dielectric ring 202 and the guard ring 104 , and at least a part of the focus ring 201 covers the guard ring 104 to prevent gas from entering the gap between the dielectric ring 202 and the base 101 .

The above lower electrode assembly can be further used in the inductively coupled plasma processing apparatus as shown in FIG. 4 . In this embodiment, the lower electrode assembly has the structure as described above, which is not repeated here. In addition, an insulating window 130 is arranged above the reaction chamber, an induction coil 140 is arranged above the insulating window 130, a high-frequency radio frequency power supply 145 applies a radio frequency signal to the induction coil 140, and the induction coil 140 generates an alternating magnetic field, which induces induction in the reaction chamber. The alternating electric field is generated 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 sidewall of the reaction chamber, or a gas injection port can be provided on the insulating window 130 to accommodate the process gas to enter. Bias RF power is applied to the lower electrode assembly through bias RF matching to control the energy distribution of the plasma.

The invention divides the gap between the dielectric ring and the base into two smaller gaps through the cooperation of the dielectric ring and the base, and sets a protection ring between the dielectric ring and the base, and the outer side of the base A protective layer is provided to prevent the plasma above the substrate and the focus ring from leaking into the gap between the base and the edge ring assembly, preventing the plasma from corroding the base and reducing the possibility of arcing that may occur in the lower electrode assembly , effectively ensuring 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 invention has been described in detail with reference to the above preferred embodiments, it should be recognized that the above description should not be construed as limiting the present invention. Various modifications and alternatives to the present invention will be apparent to those of ordinary skill in the art upon reading the foregoing disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

10: outer wall 20: Edge Ring Assembly 30: Gas shower head 100: reaction chamber 101: Pedestal 102: Electrostatic chuck 103: Substrate 104: Protection Ring 106: Protective layer 108: Plasma Confinement Ring 109: Ground Ring 130: Insulation window 140: Inductor coil 145: High Frequency RF Power Supply 201: Focus Ring 202: Dielectric Ring 1011: base body 1012, 1013, 1014: Steps 1051: First Clearance 1052: Second gap 2021: Dielectric Ring Body 2022: Extensions

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required in the explanation of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained from these drawings without creative effort.

FIG. 1 shows a schematic structural diagram of a capacitively coupled plasma processing device; FIG. 2 shows a schematic structural diagram of a partial lower electrode assembly; FIG. 3 shows a schematic structural diagram of a local 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

Claims (18)

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; and An edge ring assembly disposed around the base and an electrostatic chuck, the edge ring assembly comprising: a focus ring disposed around the base and/or the electrostatic chuck, and a dielectric ring located under the focus ring and surrounding the base, the dielectric ring comprising a dielectric ring body and an extension part of the dielectric ring extending from the dielectric ring body toward the base, A gap is set between the dielectric ring and the base, and the stepped portion cooperates with the extension portion of the dielectric ring to divide the gap into at least a first gap and a second gap. The lower electrode assembly according to claim 1, wherein a protective layer is provided on the outer side of the base. The lower electrode 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 a protective ring is further surrounded between the edge ring assembly and the base and/or the electrostatic chuck. The lower electrode assembly of claim 4, wherein at least a portion of the guard ring abuts against the dielectric ring and the base. The lower electrode assembly of claim 4, wherein at least a portion of the guard ring abuts against the base and the electrostatic chuck. The lower electrode assembly of claim 4, wherein the guard ring is a material resistant to plasma corrosion. The electrode assembly according to claim 4, wherein the guard ring is a polymer material. The electrode assembly according to claim 4, wherein the protection ring is of fluororubber or perfluororubber series. The lower electrode assembly of claim 4, wherein the guard ring is disposed above the step portion. The lower electrode assembly of claim 4, wherein the focus ring includes an extension portion of the focus ring extending toward the electrostatic chuck, and the extension portion of the focus ring at least partially covers the guard ring. The electrode assembly according to claim 1, wherein the dielectric ring is a high thermal conductivity ceramic material or an alumina material. A plasma processing apparatus comprising a vacuum processing chamber, wherein the vacuum processing chamber comprises a lower electrode assembly as described in any one of claim 1 to claim 12. A method for installing a lower electrode assembly, comprising the following steps: A base with an electrostatic chuck is provided, the base includes a base body and a step portion extending outward from the base body, A dielectric ring is provided, the dielectric ring includes a dielectric ring body and an extension part extending toward the base, the extension part of the dielectric ring is placed on the step part of the base, and the dielectric ring is connected to the base. A gap is arranged between the bases, and the stepped portion cooperates with the extension portion of the dielectric ring to divide the gap into a first gap and a second gap; A focus ring is arranged above the dielectric ring. The installation method as claimed in claim 14, wherein a protective layer is provided on the outer side of the base. The installation method as described in claim 14, further comprising the following steps: A protection ring is arranged around the periphery of the electrostatic chuck and the base, and the focus ring at least partially covers the protection ring. The installation method of claim 16, wherein the protective ring at least partially abuts against the base and the electrostatic chuck. The installation method of claim 16, wherein at least a portion of the guard ring and the dielectric ring abut against each other.

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