TWI797498B - Bottom electrode element, its mounting method and plasma processing device - Google Patents

Abstract

The invention provides a lower electrode element, its installation method and the plasma processing device where it is located, by setting a dielectric sleeve between the focus ring and the dielectric ring and the base, and between the dielectric sleeve and the base An elastic material layer is arranged in the gap between the substrate and the focus ring to prevent the plasma above the substrate and the focus ring from leaking into the gap between the base and the edge ring component, reducing the possibility of arc discharge that may occur on the lower electrode component. Limited by the size of the base and the edge rings, the invention installs the dielectric sleeve first, so that the difficulty of installing the elastic material layer in the gap between the base and the edge ring elements is greatly reduced, effectively ensuring Ensure the safety of the lower electrode components.

Description

Bottom electrode element, its mounting method and plasma processing device

The present invention relates to the technical field of plasma etching, in particular to the technical field of plasma processing for preventing arcing of lower electrode components 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 micromachining manufacturing is the plasma treatment process step, which is performed inside a reaction chamber into which process gases are fed. An RF source is inductively and/or capacitively coupled to the interior of the reaction chamber to excite the process gas to form and maintain a plasma. Inside the reaction chamber, the exposed substrate is supported by the lower electrode element 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 component not only includes an electrostatic chuck for fixing the substrate and a base for supporting the electrostatic chuck, but also includes an edge ring element surrounding the base. Fixing the substrate is also used to control the temperature and electric field distribution of the substrate.

In the known technology, the commonly used material of the base is aluminum, and the material of the insert ring around the base is usually ceramic material. Since the thermal expansion coefficients of the two are quite different, in order to ensure that the base works in a relatively large temperature range, A certain space should be provided between the insert 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 radio frequency power applied to the reaction chamber becomes larger and larger. High RF power can easily generate discharge in the narrow space of the reaction chamber, damage the base and its surrounding components, and seriously threaten the stability and safety of the electrode components. Therefore, a solution is extremely needed to adapt to the ever-increasing RF application Power and substrate processing uniformity requirements.

In order to solve the above technical problems, the present invention provides a lower electrode element for carrying the substrate to be processed, including a base, an electrostatic chuck positioned above the base, and an edge ring element surrounding the base and the electrostatic chuck, The edge ring element includes: a focus ring disposed around the substrate and the electrostatic chuck; a dielectric sleeve disposed around the base, with a gap between the dielectric sleeve and the base; A dielectric ring is located below the focus ring and is arranged around the dielectric sleeve; a protection ring is located between the focus ring and the electrostatic chuck, and the protection ring is made of plasma corrosion resistant material.

Preferably, an elastic material layer is provided in the gap.

Preferably, an annular concave groove is arranged around the connecting surface of the base and the electrostatic chuck, and the protection ring is located in the concave groove.

Preferably, the radial width of the protection ring is greater than the depth of the annular concave groove, so as to fill the gap between the focus ring and the electrostatic chuck.

Preferably, the protective ring is a polymer material.

Preferably, the protective ring is hard rubber or epoxy resin.

Preferably, a lower protective ring is provided under the protective ring, and the material of the lower protective ring is the same as that of the elastic material layer.

Preferably, the material of the lower protection ring and the elastic material layer is silicon rubber.

Preferably, a first step is provided on the dielectric sleeve, and the first step is used to carry the lower protection ring.

Preferably, a second step is provided on the dielectric sleeve, and the second step is used to carry the dielectric ring.

Preferably, a portion of said focus ring surrounds said dielectric sleeve.

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

Preferably, the vacuum reaction chamber further includes an upper electrode component, and the upper electrode component includes a gas shower head for delivering process gas into the vacuum reaction chamber.

Preferably, an insulating window is arranged above the vacuum reaction chamber, and an inductance coil is arranged above the insulating window.

Further, the present invention also discloses a method for installing the lower electrode element, which includes the following steps: providing a base with an electrostatic chuck; placing a dielectric sleeve on the periphery of the base, and the dielectric sleeve A gap is set between the base and the base; an elastic material layer is injected into the gap, and the elastic material layer realizes filling of the gap; the base and the dielectric sleeve are put into the reaction chamber; A protective ring is provided at one end of the gap close to the electrostatic chuck, and the protective ring is used to cover the gap between the focus ring and the electrostatic chuck; and the dielectric ring and the focus ring are sequentially sleeved on the dielectric Perimeter of electric sleeve.

The advantages of the present invention are: the present invention provides a plasma corrosion-resistant lower electrode element and its installation method, by arranging a dielectric sleeve between the focus ring and the dielectric ring and the base, and between the dielectric sleeve An elastic material layer is set in the gap between the base and the base to prevent the plasma above the substrate and the focus ring from leaking into the gap between the base and the edge ring components, reducing the possibility of arc discharge that may occur in the lower electrode components sex. Limited by the size of the base and the edge rings, the invention installs the dielectric sleeve first, so that the difficulty of installing the elastic material layer in the gap between the base and the edge ring elements is greatly reduced, solving the problem of conventional In the known technology, after the insertion ring and the focus ring are installed around the base, the gap between the focus ring and the electrostatic chuck is too small to provide an elastic material layer. Effectively guarantee the use safety of the lower electrode components.

10: Outer wall

100: reaction chamber

101: base

102: Electrostatic Chuck

103: Substrate

104:Focus ring

105: Dielectric ring

106,107: heat conduction layer

108: Plasma confinement ring

109: Grounding ring

111: Protection ring

112: Lower protective ring

113: elastic material layer

120: Dielectric sleeve

121: The first step

122: The second step

130: insulation window

140: Inductance coil

145: High frequency radio frequency power supply

50:Edge ring element

60: Gas sprinkler head

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 that need to be 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 invention. For those skilled in the art, other drawings can also be obtained based on these drawings without any progressive effort.

Fig. 1 shows a schematic structural view of a capacitively coupled plasma processing device; Fig. 2 shows a schematic structural view of a partial lower electrode element; and Fig. 3 shows a schematic structural view of an inductively coupled plasma processing device.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons with ordinary knowledge in the technical field without making progressive efforts belong to the protection scope of the present invention.

FIG. 1 shows a schematic diagram of a capacitively coupled plasma processing device, which includes a vacuumable 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 100 includes a lower electrode element, which is used to support the substrate 103 and realize the control of the processing factors affecting the substrate 103 such as the temperature and electric field of the substrate 103 . The lower electrode element includes a base 101 for carrying an electrostatic chuck 102. A temperature control device is provided in the base 101 for controlling the temperature of the upper substrate 103. The electrostatic chuck 102 is used for carrying the substrate 103. A DC electrode is arranged inside the chuck 102 , through which a DC adsorption is generated between the back of the substrate 103 and the bearing surface of the electrostatic chuck 102 to fix the substrate 103 . An edge ring element 50 is arranged around the susceptor 101 and the electrostatic chuck 102 to adjust the temperature and electric field distribution of the edge region of the substrate 103 . A plasma confinement ring 108 is arranged around the edge ring element 50, located between the edge ring element 50 and the side wall of the reaction chamber 100, for confining the plasma in the reaction area while allowing the gas to pass through; a grounding ring 109, located in the plasma confinement The function below the ring 108 is to provide an electric field shield to avoid plasma leakage. The bias radio frequency power supply usually applies a bias radio frequency signal to the lower electrode element to control the bombardment direction of the plasma. The lower electrode element disclosed in the present invention can be used in a capacitively coupled plasma processing device as shown in FIG. 1 .

In the capacitively coupled plasma processing apparatus shown in FIG. 1, in addition to the lower electrode element, an upper electrode element is also included, and the upper electrode element includes a gas shower head 60 for introducing process gas in the gas supply device into the reaction chamber. 100. A high-frequency radio-frequency power source applies a high-frequency radio-frequency signal to at least one of the upper electrode element or the lower electrode element to form a radio-frequency electric field between the upper electrode element and the lower electrode element, and the reaction chamber 100 The process gas is excited into plasma to realize the treatment of the substrate to be treated by the plasma.

FIG. 2 shows a schematic structural view of a partial lower electrode component. In the structure shown in this figure, the lower electrode component includes: a focus ring 104, which is arranged around the substrate 103 and the electrostatic chuck 102, and is used to focus on the edge region of the substrate 102. The temperature and electric field distribution are adjusted; a dielectric ring 105 is set under the focus ring 104, and the dielectric ring is used to maintain the potential difference between the focus ring and the base, and at the same time adjust the temperature of the focus ring. A dielectric sleeve 120 is arranged between the dielectric ring 105 and the base 101. The material of the dielectric sleeve 120 is the same as that of the dielectric ring 105 or has a similar coefficient of thermal expansion. Therefore, when the lower electrode element is heated, the dielectric sleeve 120 The electrical sleeve 120 and the dielectric ring 105 have similar thermal expansion magnitudes. In an embodiment of the present invention, the dielectric sleeve 120 is at least partially located between the focus ring 104 and the base 101 to ensure electrical isolation between the conductive base 101 and the focus ring 104 .

In the present invention, the material of the base 101 is usually conductive metal material, such as aluminum, and the dielectric ring 105 surrounding the base 101 is usually a ceramic material. Since the thermal expansion coefficients of the base 101 and the dielectric ring 105 are different, in order to avoid The components are extruded due to heat, so a certain gap needs to be set between the dielectric ring 105 and the base 101 during installation. As the processing precision of the substrate 103 becomes higher and higher, the radio frequency power applied to the reaction chamber 100 becomes larger and larger. The high radio frequency power can easily generate discharge in the narrow space of the reaction chamber 100, damage the base 101 and its surrounding components, and seriously threaten the working stability and safety of the lower electrode components.

The dielectric sleeve 120 described in this embodiment is arranged between the dielectric ring 105 and the base 101, and the material is preferably a ceramic material, since the dielectric sleeve 120 and the dielectric ring 105 have the same or similar coefficient of thermal expansion, so a very small gap or no gap can be set between the two parts, and because the dielectric sleeve 120 and the dielectric ring 105 belong to two independent parts, the stress generated by heat can be better released, so , the gap between the dielectric sleeve 120 and the base 101 can also be reduced accordingly. According to the principle of arc discharge, under the premise of the same pressure and applied electric field, the larger the gas diffusion space, the easier it is to generate arc discharge. Therefore, by reducing the gap between the dielectric sleeve 120 and the base 101, the arc discharge can be effectively reduced. The probability of generation improves the safe voltage working range of the lower electrode element.

The dielectric sleeve 120 is usually sleeved around the base 101 after the base 101 is manufactured. In order to ensure that the dielectric sleeve 120 is smoothly sleeved around the base 101, it is also the A certain space is reserved for thermal expansion and contraction, and a certain gap needs to be set between the dielectric sleeve 120 and the base 101 . The focus ring 104 is arranged around the periphery of the substrate 103 and the electrostatic chuck 102. Considering the accuracy of installation and the difference in thermal expansion between the focus ring 104 and the electrostatic chuck 102, it is also necessary to set the focus ring 104 and the electrostatic chuck 102 Certain gaps. The gas or plasma in the reaction chamber 100 diffuses downward along the gap. When the RF voltage applied to the base 101 is too large, arc discharge will occur in the gap between the base 101 and the edge ring element 50, resulting in Damage to the electrode elements, so it needs to be dealt with.

In the present invention, a plasma corrosion-resistant protective ring 111 is set between the electrostatic chuck 102 and the focus ring 104. The protective ring 111 can be made of plasma corrosion-resistant rubber and other materials. The edge area of the electrostatic chuck 102 or the electrostatic chuck An annular receiving groove is provided in the edge area of the interface between the disc 102 and the base 101 to accommodate and position the protection ring 111. Preferably, the protection ring 111 is The width in the radial direction is greater than the radial depth of the annular receiving groove, so as to fill the gap between the focus ring 104 and the electrostatic chuck 102 .

In addition, in order to further reduce the probability of arcing between the edge ring element 50 and the base 101, after the dielectric sleeve 120 is sleeved around the base 101, the dielectric sleeve 120 and the base An elastic material layer 113 is arranged in the gap between the seats 101 . The elastic material layer 113 can be made of the same material as the protective ring 111 and made integrally. Considering that the texture of the elastic material layer 113 is soft and the ability to resist plasma corrosion is slightly weak, in order to improve the service life of the protective ring 111, the elastic material layer 113 and the protective ring 111 can be selected from different materials, and the protective ring 111 and the elastic material layer The material of 113 is preferably a polymer material, and the protective ring 111 is preferably made of hard rubber or the like. Or, as shown in Figure 2, a lower protective ring 112 is arranged below the protective ring 111. Preferably, the lower protective ring 112 has the same material as the elastic material layer 113, and can be made integrally or separately and then packed in sequence The gap between the dielectric sleeve 120 and the base 101 and the gap between the focus ring 104 and the base 101 .

The guard ring 111 can effectively fill the gap between the focus ring 104 and the electrostatic chuck 102 and the base 101, preventing the plasma above it from affecting the bonding layer between the electrostatic chuck 102 and the base 101 (not shown in the figure). shown) causes corrosion while preventing the plasma from entering the underlying crevice and reducing the generation of arcing.

The elastic material layer 113 provided between the dielectric sleeve 120 and the base 101 can relieve the compression caused by the different thermal expansion ranges between different materials, and at the same time avoid the gap between the base 101 and the edge ring element 50 that may cause arcing To solve the discharge problem, increase the working range of the RF voltage applied to the base 101 . And then adapt to higher precision substrate processing.

The dielectric sleeve 120 can be arranged on another protrusion on the side of the base 101, or on the top of other supporting devices, which is not described in the present invention. The dielectric sleeve 120 is respectively provided Set a first step 121 and a second step 122, the first step 121 is used to support the lower protective ring 112, the second step 122 is used to carry the dielectric ring 105, when the dielectric ring 105 is seated on the second step 122, through The gravity of the dielectric ring 105 itself or the pressure applied from the outside can realize the close contact between the dielectric ring 105 and the second step 122, so as to prevent the gas entering the gap between the focus ring 104 and the dielectric sleeve 120 from diffusing downward, thereby preventing Possible arcing problems.

Preferably, a heat conduction layer 106 is provided between the focus ring 104 and the dielectric ring 105 , and/or a heat conduction layer 107 is provided between the dielectric ring 105 and the base 101 , so as to improve the ability to conduct temperature of the focus ring 104 . In other embodiments, the dielectric ring 105 may also be disposed above other supporting components capable of independent temperature control, so as to achieve independent control of the temperature of the focus ring 104 and that of the substrate 103 .

Preferably, the present invention also provides a method for installing the lower electrode element, comprising the following steps: providing a base 101 with an electrostatic chuck 102; setting a dielectric sleeve 120 on the periphery of the base 101; There is a certain gap between the sleeve 120 and the base 101; the elastic material layer 113 is injected into the gap, and the elastic material layer 113 realizes the filling of the gap; the base 101 and the dielectric sleeve 120 are placed into the reaction chamber 100; a protective ring 111 is set at the end of the gap close to the electrostatic chuck 102, and the protective ring 111 is used to block the gap between the focus ring 104 and the electrostatic chuck 102; and the dielectric The ring 105 and the focus ring 104 are sequentially sleeved around the periphery of the dielectric sleeve 120 .

The lower electrode element described above can also be used in an inductively coupled plasma plasma processing device as shown in Figure 3, in this embodiment, the lower electrode element has the above described The structure will not be described in detail here. In addition, an insulating window 130 is arranged above the reaction chamber, and an inductance coil 140 is arranged above the insulating window. A high-frequency radio frequency power supply 145 applies a radio frequency signal to the inductance coil 140, and the inductance coil 140 generates an alternating current. The magnetic field induces an alternating electric field in the reaction chamber to realize the plasma dissociation of the process gas entering the reaction chamber. In this embodiment, the process gas may be injected into the reaction chamber from the sidewall of the reaction chamber, or a gas injection port may be provided on the insulating window 130 to accommodate the entry of the process gas. Bias RF power is applied to the lower electrode element through a bias RF match for controlling the energy distribution of the plasma.

In the present invention, a dielectric sleeve is arranged between the focus ring and the dielectric ring and the base, and an elastic material layer is arranged in the gap between the dielectric sleeve and the base, thereby avoiding the friction above the substrate and the focus ring. Plasma leaks into the gap between the susceptor and the edge ring element, reducing the possibility of arcing that could occur on the lower electrode element. Limited by the size of the base and the edge rings, the invention installs the dielectric sleeve first, so that the difficulty of installing the elastic material layer in the gap between the base and the edge ring elements is greatly reduced, solving the problem of conventional In the known technology, after the insertion ring and the focus ring are installed around the base, the gap between the focus ring and the electrostatic chuck is too small to provide an elastic material layer. Effectively guarantee the use safety of the lower electrode components.

The lower electrode element 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 in other plasma processing apparatuses, which will not be repeated here.

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. After reading the above content, those with ordinary knowledge in the technical field will make various modifications and substitutions of the present invention will all be obvious. Therefore, the protection scope of the present invention should be limited by the scope of the appended patent application.

101: base

102: Electrostatic Chuck

103: Substrate

108: Plasma confinement ring

109: Grounding ring

130: insulation window

140: Inductance coil

145: High frequency radio frequency power supply

50:Edge ring element

Claims (15)

A lower electrode element for carrying a substrate to be processed, comprising a base, an electrostatic chuck positioned above the base, and an edge ring element surrounding the base and the electrostatic chuck, wherein the edge ring The components include: a focusing ring arranged around the substrate and the electrostatic chuck; a dielectric sleeve arranged around the base with a gap between the dielectric sleeve and the base; a dielectric ring located below the focus ring, disposed around the dielectric sleeve, the dielectric sleeve located between the dielectric ring and the base; and a guard ring located between the focus ring and the electrostatic chuck, the guard The ring is a plasma corrosion resistant material. The lower electrode element as claimed in claim 1, wherein: an elastic material layer is disposed in the gap. The lower electrode component as claimed in claim 1, wherein: a ring-shaped concave groove is arranged around the connection surface of the base and the electrostatic chuck, and the guard ring is located in the concave groove. The lower electrode element as claimed in claim 3, wherein: the radial width of the guard ring is larger than the recess depth of the annular recessed groove, so as to fill the gap between the focus ring and the electrostatic chuck. The lower electrode element as claimed in claim 1, wherein: the guard ring is made of polymer material. The lower electrode element as claimed in item 1, wherein: the protective ring is made of hard rubber or epoxy resin. The lower electrode element as described in claim 2, wherein: a The lower protective ring is made of the same material as the elastic material layer. The lower electrode element as claimed in item 7, wherein: the lower protective ring and the elastic material layer are made of silicon rubber. The lower electrode element as claimed in item 7, wherein: a first step is provided on the dielectric sleeve, and the first step is used to support the lower protective ring. The lower electrode element as claimed in claim 1, wherein: a second step is provided on the dielectric sleeve, and the second step is used to support the dielectric ring. The lower electrode element of claim 1, wherein a portion of the focus ring surrounds the dielectric sleeve. A plasma processing device, comprising a vacuum reaction chamber, wherein: a lower electrode element is arranged in the vacuum reaction chamber, and the lower electrode element includes the features described in any one of claims 1-11. The plasma processing device as claimed in claim 12, wherein: the vacuum reaction chamber further includes an upper electrode element, and the upper electrode element includes a gas shower head for delivering process gas into the vacuum reaction chamber. The plasma processing device as claimed in claim 12, wherein: an insulating window is arranged above the vacuum reaction chamber, and an inductance coil is arranged above the insulating window. A method for installing a lower electrode element, comprising the following steps: providing a base with an electrostatic chuck; placing a dielectric sleeve on the periphery of the base, between the dielectric sleeve and the base setting a certain gap; injecting an elastic material layer into the gap, and the elastic material layer realizes the filling of the gap; putting the base and the dielectric sleeve into a reaction chamber; A protective ring is arranged at the end of the gap close to the electrostatic chuck; a dielectric ring and a focusing ring are sequentially set around the periphery of the dielectric sleeve, and the dielectric sleeve is located between the dielectric ring and the base between; and the protection ring is used to cover the gap between the focus ring and the electrostatic chuck.

Images