JP2012510727A - Adjusting the RF feedback strap for uniformity control - Google Patents

Abstract

  Embodiments of the present invention generally relate to a method and apparatus for processing a substrate using a plasma. More particularly, embodiments of the present invention provide a plasma processing chamber having an electrode coupled to a plurality of RF return straps such that the impedance of the RF return strap adjusts the plasma distribution during processing. Set and / or adjusted. In one embodiment, the impedance of the RF feedback strap may change the spacing of the RF feedback straps, either by changing the length of the RF feedback strap or by changing the width of the RF feedback strap. Or by changing the location of the RF feedback strap, adding a capacitor to the RF feedback strap, or a combination thereof.

Description

  Embodiments of the present invention generally relate to a method and apparatus for processing a substrate, such as a solar panel substrate, a flat panel substrate, or a semiconductor substrate, using plasma. More particularly, embodiments of the present invention relate to radio frequency (RF) current feedback paths for plasma processing chambers.

  Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates such as semiconductor substrates, solar panel substrates, and liquid crystal display (LCD) substrates. Plasma enhanced chemical vapor deposition is generally achieved by introducing a precursor gas into a vacuum chamber having a substrate disposed on a substrate support. The precursor gas is typically guided through a distribution plate placed near the top of the vacuum chamber. The precursor gas in the vacuum chamber is activated (eg, excited) into a plasma by applying RF power to the chamber from one or more RF sources coupled to the chamber. The excited gas reacts to form a layer of material on the surface of the substrate placed on the temperature controlled substrate support. The distribution plate is generally connected to an RF power source and the substrate support is typically connected to the chamber body to provide a path for RF current feedback.

  For thin films deposited using a PECVD process, uniformity is generally required. For example, an amorphous silicon film or a polycrystalline silicon film such as a microcrystalline silicon film or a microcrystalline silicon film is usually formed on a flat panel for forming a pn junction necessary for a transistor or a solar cell. Deposit using PECVD. The quality and uniformity of the amorphous silicon film or the polycrystalline silicon film is important for commercial use. Therefore, there is a need for a PECVD chamber with improved uniformity.

  Embodiments of the present invention generally relate to a method and apparatus for plasma processing a substrate. More particularly, embodiments of the present invention provide a plasma processing chamber having an RF return strap configured to improve uniformity.

  One embodiment of the present invention includes providing a processing chamber that defines a processing volume, wherein a substrate support is disposed within the processing volume and a gas distribution plate connected to a radio frequency (RF) power source includes a substrate support. One or more types of processing steps disposed through the distribution plate and into the processing volume, wherein the peripheral portion of the substrate support is connected to the RF power source via a plurality of RF feedback straps. One or more RF feedback steps comprising flowing a gas and applying high frequency power to the gas distribution plate to generate plasma from one or more processing gases within the processing volume. One for processing substrates using plasma, where the impedance of the strap has been modified to adjust the local plasma distribution between the gas distribution plate and the substrate To provide.

  Another embodiment of the present invention is a chamber body defining a processing volume, the chamber body having a slit valve opening configured to allow passage of a substrate, and disposed within the processing volume. A substrate support configured to receive a substrate on a support surface and to support the substrate during processing, and is disposed above the substrate support in the processing volume A gas distribution plate configured to deliver one or more types of processing gases, a high frequency power source connected to the gas distribution plate, a peripheral portion of the substrate support portion, and a high frequency power source A plurality of RF feedback straps connected to each other, wherein the impedance between the substrate support portion and the high-frequency power source is arranged to change along the peripheral portion of the substrate support portion. strap Equipped with, it provides an apparatus for processing a substrate.

  In yet another embodiment of the present invention, a chamber body defining a processing volume, a first electrode disposed within the processing volume, and a second electrode disposed within the processing volume comprising: A first electrode and a second electrode that form a plasma volume between the first electrode and the second electrode, a high-frequency power source connected to the first electrode, and a predetermined potential A plurality of RF feedback straps connected between the second electrode and the body, wherein the straps are connected to the periphery of the second electrode, and the impedances of the plurality of RF feedback straps are connected to the periphery of the second electrode; An apparatus for processing a substrate is provided that includes a plurality of RF return straps that vary along the line.

  Accordingly, a more detailed description of the invention, briefly summarized above, taken in part in the accompanying drawings, in a manner that provides a thorough understanding of the features described above. By referring to certain embodiments. It should be noted, however, that the attached drawings only illustrate exemplary embodiments of the invention and therefore should not be considered as limiting the scope of the invention. This is because the present invention can tolerate other equally effective embodiments.

1 is a schematic diagram of an RF return strap for a plasma processing system for PECVD according to one embodiment of the invention. FIG. 1B is a schematic top view of the plasma processing system of FIG. 1A. FIG. 1 is a schematic side view of a cross-section of a plasma processing chamber according to an embodiment of the present invention. FIG. 5 is a schematic diagram of an RF feedback strap connection according to an embodiment of the present invention. 1 is a schematic view of an RF feedback strap according to an embodiment of the present invention. FIG. FIG. 6 is a schematic diagram of an RF feedback strap arrangement according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an RF feedback strap arrangement according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an RF feedback strap arrangement according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an RF feedback strap arrangement according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an RF feedback strap arrangement according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an RF feedback strap arrangement for compensating for chamber asymmetry according to an embodiment of the present invention. 1 is a cross-sectional view of an exemplary silicon-based thin film photovoltaic (PV) solar cell.

  To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is anticipated that elements and / or process steps of one embodiment may be incorporated to benefit other embodiments without additional description.

  Embodiments of the present invention generally relate to a method and apparatus for processing a substrate using a plasma. More particularly, embodiments of the present invention provide a plasma processing chamber having an electrode coupled to a plurality of RF feedback straps, and the impedance of the RF feedback strap is adjusted to adjust the plasma distribution during processing. Set and / or adjust. In one embodiment, either by changing the length of the RF feedback strap, by changing the width of the RF feedback strap, or by changing the spacing of the RF feedback straps, The impedance of the RF feedback strap is changed by changing location, by adding a variable capacitor to the RF feedback strap, or by combining them.

Embodiments of the present invention are generally utilized when processing rectangular substrates such as substrates for liquid crystal display panels or flat panels and substrates for solar panels. Other suitable substrates can be circular, such as a semiconductor substrate. The present invention can be utilized to process substrates of any size or shape. However, the present invention is preferably larger than 15K (about 15,600 cm ² ), 25K (about 27,750 cm ² ), or more, because of the increased RF feedback required for large susceptors. Provides exceptional advantages over 40K (about 41,140 cm ² ) or more, for example, 50K, 55K, or 60K.

  The present invention is illustratively described, shown, and implemented in a large area substrate processing system, but one or more RF return paths function at a level that facilitates processing accepted in the system. The present invention may find utility in other plasma processing systems, including plasma processing systems from other manufacturers, where it is desirable to ensure maintenance. Other exemplary processing systems in which the present invention may be implemented include the CENTURA ULTIMA HDP-CVD ™ system, the PRODUCER APF PECVD ™ system, the PRODUCER BLACK DIAMOND ™ system, the PRODUCER BLOK PECVD (TM) system, PRODUCER DARC PECVD (TM) system, PRODUCER HARP (TM) system, PRODUCER PECVD (TM) system, PROCUCER STRESS NITRIDE PECVD (TM) system, PRODUCER TEOS FSG PECVD (TM) system All of which include Santa Clara, CA's Applied Materials, Inc. Is available from

  To form a number of different types of films that can be used to form a thin film solar cell, such as a cross-sectional view of an embodiment of the silicon based thin film photovoltaic (PV) solar cell 900 shown in FIG. Embodiments of the invention can be used. A silicon-based thin film PV solar cell 900 generally includes a transparent conductive oxide (TCO) layer 902 formed on a substrate 940, a photoelectric conversion unit 914 formed on the transparent conductive oxide layer 902, and a photoelectric conversion. A back electrode 916 formed on the unit 914 is provided. The back electrode 916 can be formed using a stacked film including the transparent conductive oxide (TCO) layer 910 and the conductive layer 912.

  In operation, incident light 922 provided by the environment, eg, sunlight or other photons, is supplied to the PV solar cell 900. The photoelectric conversion unit 914 in the PV solar cell 900 absorbs light energy and converts the light energy into electrical energy in the pin junction (s) formed in the photoelectric conversion unit 914. This generates electricity or energy. Alternatively, the PV solar cell 900 can be manufactured or deposited in the reverse order, or can comprise two or more photoelectric conversion units stacked together and separated by a transparent conductive oxide layer.

The substrate 940 can be a thin sheet of metal, plastic, organic material, silicon, glass, quartz, or polymer, among other suitable materials. The substrate 940 can have a surface area greater than about 1 square meter, such as greater than about 2 square meters. An optional dielectric layer (not shown) can be disposed between the substrate 940 and the transparent conductive oxide (TCO) layer 902. In one embodiment, the optional dielectric layer can be a SiON layer or a silicon oxide (SiO ₂ ) layer.

The transparent conductive oxide (TCO) layers 902 and 910 are at least one selected from the group consisting of tin oxide (SnO ₂ ), indium tin oxide (ITO), zinc oxide (ZnO), or a combination thereof. One oxide layer can be included, but is not limited thereto. The TOC layer 902 can be deposited by a CVD process, a PVD process, or other suitable deposition process.

  The conductive layer 912 can include a metal layer selected from the group consisting of Ti, Cr, Al, Ag, Au, Cu, Pt, or a combination of these, It is not limited to.

  The photoelectric conversion unit 914 includes a p-type semiconductor layer 904, an n-type semiconductor layer 908, and an intrinsic (i-type) semiconductor layer 906. The i-type semiconductor layer 906 is also known as a bulk layer that functions as a photoelectric conversion layer that generates electron-hole pairs from incident light energy. Intrinsic semiconductors are distinguished from extrinsic semiconductors by the addition of dopant atoms in the extrinsic semiconductor. In order to collect electrons or holes generated by the intrinsic semiconductor in the solar cell, extrinsic semiconductor layers such as p-type semiconductor layer 904 and n-type semiconductor layer 908 are used.

  An intrinsic semiconductor layer can be formed by supplying a mixed gas containing a raw material of a semiconductor material to be formed. For example, an intrinsic silicon layer can be formed by supplying a gas containing silane and hydrogen gas to the processing chamber. Silicon and other semiconductors formed from mixed gases may have varying degrees of crystallinity depending on processing parameters.

  A substance in which atoms are not arranged in an essentially determined pattern or has no crystallinity is called amorphous. A completely crystalline substance is referred to as a crystalline material, a polycrystalline material or a single crystalline material. A polycrystalline material is a crystalline material formed into a number of crystal grains separated by grain boundaries. The single crystal material is a single crystal material.

  A semiconductor solid having a partial crystallinity that is between about 5% and about 95% in crystallinity generally refers to the size of a crystal grain suspended in an amorphous phase, and is nanocrystalline or microcrystalline. Call it.

  Nanocrystalline silicon, often called microcrystalline silicon, is a quasicrystal with short-range or medium-range order, composed of a mixture of two phases-small crystalline grains embedded in an amorphous matrix . Nanocrystalline and microcrystalline are sometimes distinguished by grain size (or crystallinity). However, most quasicrystalline silicon with grains extending to the micrometer range is actually fine-grained polycrystalline silicon with no amorphous substrate between the crystals, hence the term “nanocrystals”. Some believe that “quality” is a better term choice than “microcrystalline” when referring to two-phase quasicrystalline silicon.

  Another approach from the late 1990s was again to define microcrystalline silicon as having grains in two phases, an amorphous matrix, but the grain features Size was limited to <20 nm. In contrast, polycrystalline silicon was defined as a single phase crystalline material with no amorphous substrate between the crystals, with a minimum crystal size> 20 nm.

  It should be noted that the term “crystalline silicon / semiconductor” can refer to any form of silicon / semiconductor having a crystalline phase including microcrystalline silicon / semiconductor and nanocrystalline silicon / semiconductor.

  The crystallinity of the intrinsic semiconductor layer affects the light absorption characteristics of the intrinsic semiconductor layer. For example, an amorphous semiconductor layer generally absorbs light at a different wavelength than an intrinsic layer having a different degree of crystallinity, such as microcrystalline silicon. For this reason, most solar cells use both amorphous and microcrystalline / nanocrystalline layers to provide the widest possible light absorption properties. Intrinsic semiconductor layers are formed by depositing multiple microcrystalline semiconductor layers, films with graded crystal ratios, or crystalline ratios that vary throughout the layers to achieve the desired nominal crystal ratio be able to.

  The p-type semiconductor layer 904 and the n-type semiconductor layer 908 can be silicon-based materials doped with an element selected from either Group III or Group V. A silicon film doped with a group III element (eg, boron (B)) is called a p-type silicon film, while a silicon film doped with a group V element (eg, phosphorus (P)) is n-type silicon. Called a membrane. In one embodiment, the n-type semiconductor layer 908 can be a phosphorus-doped silicon film and the p-type semiconductor layer 904 can be a boron-doped silicon film.

  The doped silicon film is typically an amorphous silicon film (a-Si), a polycrystalline film (poly-Si), or a microcrystalline film (μc) having a thickness between about 5 nm and about 50 nm. -Si). Alternatively, the elements that are doped into the semiconductor layers 904, 908 can be selected to satisfy the device requirements of the PV solar cell 900. An n-type semiconductor layer 908 and a p-type semiconductor layer 904 can be deposited using a processing chamber according to embodiments of the present invention.

  FIG. 1A schematically illustrates an RF return strap for a plasma processing system 100 for PECVD according to one embodiment of the present invention. The plasma processing system 100 is on a large area substrate 101 for use in the manufacture of a liquid crystal display (LCD), a flat panel display, an organic light emitting diode (OLED), or a photovoltaic cell for a solar cell array. It is configured to process the large area substrate 101 using plasma in forming structures and devices. The structure can be a plurality of back channel etch inverted staggered (bottom gate) thin film transistors that can include a plurality of sequential deposition and masking steps. Other structures can include pn junctions to form diodes for photovoltaic cells.

The plasma processing system 100 can be formed on a large area substrate 101 with a dielectric material (eg, SiO ₂ , SiO _x N _y , derivatives thereof, or combinations thereof), or a semiconductor material (eg, Si and its). Various materials including, but not limited to, dopants), barrier materials (eg, SiN _x , SiO _x N _y , or derivatives thereof) can be configured. Specific examples of dielectric and semiconductor materials formed or deposited by the plasma processing system 100 onto a large area substrate include epitaxial silicon, polycrystalline silicon, amorphous silicon, microcrystals Silicon, silicon germanium, germanium, silicon dioxide, silicon oxynitride, silicon nitride, their dopants (eg, B, P, or As), their derivatives, or combinations thereof Can be included. The plasma processing system 100 is also suitable for use as a purge gas, such as argon, hydrogen, nitrogen, helium, or combinations thereof, or a carrier gas (eg, Ar, H ₂ , N ₂ , He, derivatives thereof, or combinations thereof). An example of depositing a silicon thin film on a large area substrate 101 using the present system 100 can be realized by using silane as a precursor gas in a hydrogen carrier gas.

  Examples of various devices and methods for depositing thin films on large area substrates using system 100 are named “Method Of Controlling The Film Properties Of PECVD-Deposited Thin Films” filed on November 17, 2005. United States Patent Application Publication No. 11 / 021,416, published as United States Patent Application Publication No. 2005/0255257, and “Plasma Uniform Control By Gas Diffuser Curve” filed on July 1, 2005. U.S. Patent Application No. 11 / 173,210, and U.S. Patent Application Published as U.S. Patent Application Publication No. 2006/0228496 It can be found, these applications the extent not inconsistent with the present specification and are also incorporated with both by reference herein. Other examples of various devices that can be formed using system 100 are described in US patent application Ser. No. 10/889, entitled “Plasma Uniformity Control By Gas Diffuser Hole Design,” filed July 12, 2004, US Patent Application Publication No. 683, which was published as US Patent Application Publication No. 2005/0251990, and “Controlling the Properties and Uniform of the Florida Night Control” issued on October 24, 2006. Can be found in US Pat. No. 7,125,758, entitled “Precursors”. Both of which are incorporated by reference herein to the extent not inconsistent herewith.

  As shown in FIG. 1A, the plasma processing system 100 generally includes a chamber body 102 that defines a processing volume 110. The substrate support unit 104 is disposed in the processing volume 110. The substrate support unit 104 is configured to support the substrate 101 on the upper surface 104a during processing. In order to adjust the distance between the substrate 101 and the showerhead assembly 103 configured to supply processing gas from the processing gas source 107 to the processing volume 110, the substrate support 104 is also in process. Configured to move vertically. The plasma processing system 100 again comprises an exhaust system 111 configured to evacuate the processing volume 110. The shower head assembly 103 is generally disposed to face the substrate support unit 104 in a parallel manner.

  In one embodiment, the showerhead assembly 103 includes a gas distribution plate 131 and a blocker plate 132. A gas volume 133 is formed between the gas distribution plate 131 and the blocker plate 132. A gas source 107 is connected to the gas volume 133 via a gas supply conduit 134.

  The gas distribution plate 131, the blocker plate 132, and the gas supply conduit 134 are generally formed of an electrically conductive material and are in electrical communication with each other. The chamber body 102 is also formed from an electrically conductive material. The chamber body 102 is generally electrically isolated from the showerhead assembly 103. In one embodiment, the showerhead assembly 103 is mounted on the chamber body 102 via an insulator 135.

  In one embodiment, the substrate support 104 is also electrically conductive, and the substrate support 104 and the showerhead assembly 103 are configured to be opposing electrodes for generating a plasma therebetween. The

  An RF power source 105 is typically used to generate plasma between the showerhead assembly 103 and the substrate support 104. In one embodiment, the RF power source 105 is coupled to the showerhead assembly 103 via the first output 106 a of the impedance matching circuit 106. The second output part 106 b of the impedance matching circuit 106 is electrically connected to the chamber body 102.

  In one embodiment, a plurality of RF return straps 109 are electrically connected between the substrate support 104 and the chamber body 102. A plurality of RF feedback straps 109 are configured to short circuit the RF current path during processing to adjust the plasma uniformity near the edge region of the substrate support 104.

  The path of the RF current is schematically illustrated by arrows in FIG. 1A. The RF current generally travels from the first output 105a of the RF power source 105 to the first output 106a of the impedance matching circuit 106, and then along the outer surface of the gas supply conduit 134, the back surface of the blocker plate 132. To the surface of the gas distribution plate 131. From the surface of the gas distribution plate 131, RF current passes through the plasma 108 and reaches the upper surface of the substrate 101 or substrate support 104, and then passes through a plurality of RF return straps 109 to the inner surface 102 a of the chamber body 102. Proceed with From the inner surface 102a, the RF current returns to the second output 105b of the RF power source 105 via the second output 106b of the impedance matching circuit 106.

  FIG. 1B is a schematic top view of the plasma processing system 100. FIG. 1B schematically illustrates an arrangement of a plurality of RF return straps 109 in connection with the substrate support 104. A plurality of RF feedback straps 109 are distributed along the edge of the substrate support 104. Each RF return strap 109 can include a wide bend having one end electrically connected to the surface of the substrate support 104 and the other end electrically connected to the chamber body 102. A plurality of RF return straps 109 allow relative movement between the substrate support 104 and the chamber body 102. Each RF return strap 109 may have different electrical characteristics adjusted to the location of the RF return strap 109. In one embodiment, the impedance of the RF feedback strap 109 is adjusted to adjust the local plasma distribution.

  Referring again to FIG. 1A, during processing, one or more processing gases are flowed from the gas source 107 through the showerhead 103 to the processing volume 110. RF power is applied between the shower head 103 and the substrate support 104 to generate plasma 108 for processing the substrate 101. The uniformity of the plasma distribution is generally required during processing. However, the distribution of the plasma 108 is determined by various factors such as the distribution of the processing gas, the geometry of the processing volume 110, the distance between the electrodes, and the electrical characteristics of the RF return strap 109. .

  In one embodiment of the present invention, the plasma distribution within the processing volume 110 can be adjusted by adjusting one or more characteristics for one or more of the plurality of RF feedback straps 109. In one embodiment, by adjusting the location of the RF feedback strap 109, by adjusting the width of the RF feedback strap 109, or by adjusting the length of the RF feedback strap 109, adjacent to each other. The characteristics of the RF feedback strap 109 can be adjusted by adjusting the spacing between the RF feedback straps 109, by adding variable or fixed capacitors, or a combination thereof.

  FIG. 2A schematically illustrates a cross-sectional side view of a plasma processing chamber 200 according to one embodiment of the invention.

  The plasma processing chamber 200 includes a chamber bottom 201, a side wall 202, and a lid assembly 203. The chamber bottom 201, the side wall 202, and the lid assembly 203 define a processing volume 206. A substrate support assembly 204 is disposed within the processing volume 206. An opening 207 is formed through one side of the side wall 202. The opening 207 is configured to allow the substrate 208 to pass through. A slit valve 205 is connected to the side wall 202 and configured to close the opening 207 during processing.

  The lid assembly 203 is supported by the side wall 202 and can be removed to inspect the interior of the plasma processing chamber 200. The lid assembly 203 includes an outer lid 242, a lid cover plate 243, a blocker plate 209, a distribution plate 210, a gas conduit 241, and an insulator 213.

  The blocker plate 209 and the distribution plate 210 are arranged substantially parallel to each other and form a gas distribution volume 214 therebetween. Blocker plate 209 and distribution plate 210 are configured to distribute processing gas to processing volume 206. Blocker plate 209 and distribution plate 210 are typically made from aluminum. An insulator 213 is disposed on the sidewall 202 and is configured to electrically insulate the sidewall 202 from the distribution plate 210 and the blocker plate 209. The lid cover plate 243 is supported by the outer lid 242 and is electrically connected to the side wall 202.

  An opening 212 is formed through the blocker plate 209 and is configured to connect the gas distribution volume 214 via a gas conduit 241 to a gas source (not shown). Distribution plate 210 has a perforated area near the central area. A plurality of holes 211 are formed through the distribution plate 210 to provide fluid communication between the gas distribution volume 214 and the processing volume 206. The perforated region of distribution plate 210 is configured to provide a uniform distribution of gas passing through distribution plate 210 to processing volume 206.

  The substrate support assembly 204 is centrally located within the processing volume 206 and supports the substrate 208 during processing. The substrate support assembly 204 generally comprises an electrically conductive support body 217 supported by a shaft 218 that extends through the chamber bottom 201. The support portion main body 217 is generally polygonal in shape, and is covered with an electrically insulating coating that covers at least a part of the support portion main body 217 that supports the substrate 208 from the outside. The insulating coating can also cover other parts of the support body 217. In one embodiment, the substrate support assembly 204 is typically coupled to ground potential at least during processing.

  The support body 217 can be made of metal or other similarly electrically conductive material, such as aluminum. The insulating coating can be, among other things, an oxide, silicon nitride, silicon dioxide, aluminum dioxide, tantalum pentoxide, silicon carbide, or a dielectric material such as polyimide. Can be applied by various deposition processes or coating processes including but not limited to flame spraying, plasma spraying, high energy coating, chemical vapor deposition, spraying, adhesive film, sputtering, and encapsulation it can.

  In one embodiment, the support body 217 encloses at least one embedded heating element 219 configured to heat the substrate 208 during processing. In one embodiment, the support body 217 again includes a thermocouple for temperature control. In one embodiment, the support body 217 may include one or more reinforcing members made of metal, ceramic, or other reinforcing material embedded within itself.

  A heating element 219 such as an electrode or a resistance element is connected to the power source 220, and the support assembly 204 and the substrate 208 disposed thereon are controlled to be heated to a predetermined temperature. Typically, the heating element 219 maintains the substrate 208 at a uniform temperature from about 150 degrees Celsius to at least about 460 degrees Celsius during processing. The heating element 219 is electrically floating with respect to the support body 217.

  A shaft 218 extends from the support body 217 through the chamber bottom 201 and couples the substrate support assembly 204 to the lifting system 221. The lift system 221 moves the substrate support assembly 204 between a raised processing position (as shown in FIG. 2) and a lowered position that facilitates substrate transport.

  In one embodiment, the substrate support assembly 204 comprises a shadow frame 222 that surrounds the periphery. The surrounding shadow frame 222 is configured to prevent deposition or other processing on the ends of the substrate 208 and support body 217 during processing. As shown in FIG. 2, when the substrate support assembly 204 is in the raised processing position, the surrounding shadow frame 222 remains on the substrate 208 and the support body 217. When the substrate support assembly 204 is in a lowered position for substrate transport, the surrounding shadow frame 222 remains on the step 223 formed on the sidewall 202 above the substrate support assembly 204.

  In one embodiment, the support body 217 is configured to guide a plurality of lifting pins 224 and includes a plurality of pin holders 225 disposed through the support body. Each pin holder 225 has a through hole 226 formed therein. The through hole 226 is opened on the upper surface of the support body 217. Each pin holder 225 is configured to receive one lifting pin 224 from the lower opening of the through hole 226. Each lifting pin 224 extends upward from a recess 227 formed in the chamber bottom 201. Since the support body 217 is lowered together with the plurality of pin holders 225, the plurality of lifting pins 224 protrude through the through holes 226 and lift the substrate 208. The substrate 208 is then released from the support body 217 to allow the substrate handler to transport the substrate 208 out of the plasma processing chamber 200.

  The plurality of lifting pins 224 are made of ceramic or anodized aluminum. In one embodiment, the plurality of lift pins 224 can have various lengths such that the plurality of lift pins contact the substrate 208 at different times. For example, lift pins 224 spaced around the outer edge of the substrate 208 are more lifted than lift pins 224 spaced inward from the outer edge toward the center of the substrate 208. It is tall and allows the substrate 208 to be lifted first from the outer edge relative to the center of the substrate 208.

  An RF power source 215 is used to generate plasma within the processing volume 206. In one embodiment, impedance matching circuit 216 is coupled to RF power source 215. The first output 216a of the impedance matching circuit 216 is connected to the gas distribution plate 210 and the second output 216b of the impedance matching circuit 216 is connected to the substrate support assembly 204, and thus the gas distribution plate 210 and the substrate support assembly. RF power is applied to the processing gas disposed between and 204 to generate and maintain a plasma for processing the substrate 208 on the substrate support assembly 204.

  In one embodiment, the first output 216 a of the impedance matching circuit 216 is connected to the distribution plate 210 via the gas conduit 241 and the blocker plate 209. In one embodiment, the second output 216b is coupled to a chamber body, such as the sidewall 202 or lid cover plate 243.

  In one embodiment, a plurality of RF feedback straps 228 are connected from the support body 217 of the substrate support assembly 204 to the chamber bottom 201 connected to the second output 216b of the impedance matching circuit 216. The plurality of RF feedback straps 228 provide an RF current feedback path between the support body 217 and the chamber bottom 201.

  In one embodiment, a plurality of RF return straps 228 are unevenly distributed along each end of the support body 217 at different intervals between adjacent RF return straps 228. In one embodiment, the plurality of RF return straps 228 are distributed asymmetrically, reflecting asymmetric features of the chamber geometry and / or asymmetrical features of the gas flow distribution. In one embodiment, no RF return strap 228 is placed near the corner of the support body 217.

  In another embodiment, each of the plurality of RF return straps 228 has different electrical characteristics depending on the location of each RF return strap 228. In one embodiment, at least one of the plurality of RF return straps 228 has adjustable electrical characteristics. In one embodiment, the adjustable electrical characteristic is the impedance of the RF feedback strap 228.

  FIG. 2C schematically illustrates one embodiment of an RF return strap 228. The RF return strap 228 is generally a flat, soft conductive band that is flexible and does not exert significant resilience when bent. In one embodiment, the RF return strap 228 includes a flexible, low impedance conductive material that is resistant to processing and cleaning chemistries. In one embodiment, the RF return strap 228 is made of aluminum. Alternatively, the RF return strap 228 can include a flexible material coated with titanium, stainless steel, beryllium copper, or a conductive metal coating.

  In one embodiment, the RF return strap 228 has a first end 238 and a second end 239. The first end 238 has a mounting slot 233 and the second end 239 has a mounting slot 234. In one embodiment, the RF return strap 228 has a central slot 237 configured to increase the flexibility of the RF return strap 228.

  FIG. 2B schematically illustrates an RF return strap connection for use within the plasma processing chamber 200. The first end 238 of the RF return strap 228 is electrically coupled to the support body 217 via the connection assembly 230. In one embodiment, the connection assembly 230 is connected to the lower side 240 of the support body 217. Second end 239 is electrically coupled to chamber bottom 201 by connection assembly 229. The RF return strap 228 may be, for example, a fastener, clamp, or other method that maintains an electrical connection between the support body 217, the RF return strap 228, and the chamber bottom 201. The support portion main body 217 and the chamber bottom portion 201 can be connected to each other through these means. As shown in FIG. 2B, the connection assembly 230 includes a molded clamp 232 and one or more screws 235. The connection assembly 229 includes a molded clamp 231 and one or more screws 236.

  Connection assemblies 229, 230 include low impedance conductive materials that are resistant to processing and cleaning chemistries, respectively. In one embodiment, connection assemblies 229, 230 include aluminum. Alternatively, the material can include any material coated with titanium, stainless steel, beryllium copper, or a conductive metal coating. In another embodiment, connection assembly 229 includes a first conductive material, connection assembly 230 includes a second conductive material, and the first conductive material and the second conductive material are different. Material.

  Another RF feedback strap embodiment is US patent application Ser. No. 11 / 775,359 (Attorney document number 12004) entitled “Asymmetric Grounding of Rectangular Susceptor” filed on July 10, 2007. It can be found in the published US patent application published as US 2008/0274297, which is incorporated herein by reference.

  In one embodiment, the electrical characteristics of the RF feedback strap 228 are adjusted to adjust the local plasma distribution. In one embodiment, the electrical characteristics of the RF return strap 228 can be adjusted to improve the uniformity of the plasma formed between the distribution plate 210 and the support body 204.

  In one embodiment, the impedance of each RF return strap 228 can be adjusted to adjust the local plasma distribution. In one embodiment, reducing the impedance of the RF feedback strap 228 can increase the local plasma distribution near the RF feedback strap 228 and increase the impedance of the RF feedback strap 228. Can reduce the local plasma distribution near the RF feedback strap 228.

  In another embodiment, the plasma distribution within the plasma processing chamber 200 can be adjusted by adjusting the location and / or spacing of the plurality of RF return straps 228.

  By changing the length of the RF feedback strap 228, by changing the width of the RF feedback strap 228, or by connecting a variable capacitor in series or in parallel to the RF feedback strap 228, the adjacent RF The electrical characteristics of each RF return strap 228 can be adjusted by adjusting the spacing of the return straps, or a combination thereof.

  3-7 schematically illustrate an RF feedback strap arrangement for improving plasma uniformity, according to an embodiment of the present invention.

  FIG. 3 schematically illustrates an array of RF return straps 328 along one side of a rectangular substrate support body 317, similar to the support body 217 of FIG. 2A. A plurality of RF feedback straps 328 are evenly distributed along one side of the support body 317. This arrangement increases the uniformity of the plasma along that side of the substrate support body 317. The spacing 341 between adjacent RF return straps is substantially the same, the width of each RF return strap 328 is substantially the same, and the length of each RF return strap 328 is at its side. Change along. In one embodiment, the length of the RF return strap 328 is long near the end of the side and gradually decreases toward the center of the side. Although only one side of the substrate support body 317 is shown, the remaining sides of the substrate support body 317 are also connected to a plurality of RF feedback straps. A similar RF feedback strap arrangement or a different RF feedback strap arrangement can be applied to the remaining sides not shown.

  FIG. 4 schematically illustrates an array of RF return straps 428 along one side of a rectangular substrate support body 417, similar to the support body 217 of FIG. 2A. A plurality of RF return straps 428 are distributed along a side of the support body 417. This arrangement increases the uniformity of the plasma along that side of the substrate support body 417. The width of each RF return strap 428 is substantially the same, and the length of each RF return strap 428 is also substantially the same, but the spacing 441 between adjacent RF return straps 428 is Change along. In one embodiment, the spacing 441 between adjacent RF return straps 428 is large near the end of the side and gradually decreases toward the center of the side. Although only one side of the substrate support body 417 is shown, the remaining sides of the substrate support body 417 are also connected to a plurality of RF feedback straps. A similar RF feedback strap arrangement or a different RF feedback strap arrangement can be applied to the remaining sides not shown.

  FIG. 5 schematically illustrates an array of RF return straps 528 along one side of a rectangular substrate support body 517, similar to the support body 217 of FIG. 2A. A plurality of RF return straps 528 are distributed along a side of the support body 517. This arrangement increases the uniformity of the plasma along that side of the substrate support body 517. The length of each RF feedback strap 528 is again substantially the same, and the spacing 541 between adjacent RF feedback straps 528 is substantially the same, but the width of each RF feedback strap 528 is It changes along the side. In one embodiment, the width of the RF feedback strap 528 is small near the end of the side and increases toward the center of the side. Although only one side of the substrate support body 517 is shown, the remaining sides of the substrate support body 517 are also connected to a plurality of RF feedback straps. A similar RF feedback strap arrangement or a different RF feedback strap arrangement can be applied to the remaining sides not shown.

  FIG. 6 schematically illustrates an array of RF return straps 628 along one side of a rectangular substrate support body 617, similar to the support body 217 of FIG. 2A. A plurality of RF return straps 628 are evenly distributed along a side of the support body 617. Each RF feedback strap 628 includes a variable capacitor 642 connected therein in series. The length, width, and interval of each RF feedback strap 628 are substantially the same. The variable capacitor 642 of each RF feedback strap 628 can be individually adjusted. Therefore, the impedance of each RF feedback strap 628 can be adjusted according to the location of the RF feedback strap 628 to improve uniformity along the side. Although only one side of the substrate support body 617 is shown, the remaining sides of the substrate support body 617 are also connected to a plurality of RF feedback straps. A similar RF feedback strap arrangement or a different RF feedback strap arrangement can be applied to the remaining sides not shown.

  The sequences of FIGS. 3-6 can be used alone or in combination. In one embodiment, the same arrangement can be used on all sides of the substrate support. In another embodiment, a different arrangement can be used on each side of the substrate support. In another embodiment, different arrangements can be used in combination along one side of the substrate support.

  As shown in FIG. 7, the RF feedback straps along one side of the substrate support 717 can be arranged by changing the length and changing the capacitor. A plurality of RF return straps 728 are evenly distributed along a side of the substrate support 717. The spacing 741 between adjacent RF return straps is substantially the same, the width of each RF return strap 728 is substantially the same, and the length of each RF return strap 728 is along the side. Change. In one embodiment, the length of the RF feedback strap 728 is long near the end of the side and gradually decreases toward the center of the side. However, one or more RF feedback straps 743 with variable capacitors 742 are placed near the center of the side. The variable capacitor 742 allows the RF feedback strap 743 to be equivalent to a short length RF feedback strap. This arrangement is particularly useful when reducing the length of the RF return strap limits the range of movement of the substrate support 717. Although only one side of the substrate support 717 is shown, the remaining sides of the substrate support 717 are also connected to a plurality of RF feedback straps. A similar RF feedback strap arrangement or a different RF feedback strap arrangement can be applied to the remaining sides not shown.

  FIG. 8 schematically illustrates an RF feedback strap arrangement for compensating for chamber asymmetry according to one embodiment of the present invention. As shown in FIG. 8, a plurality of RF feedback straps 828 are distributed along four sides of a rectangular substrate support body 817 similar to the support body 217 of FIG. 2A. The arrangement of the RF feedback straps 828 is asymmetric. In particular, the RF feedback strap connected to side 844 is different from the RF feedback strap connected to side 845 opposite side 844. This arrangement may be useful for correcting asymmetric chamber geometry caused by a slit valve located near side 845.

  While the above is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. Is determined by the following claims.

Claims (15)

A method for processing a substrate using a plasma, comprising:
Providing a processing chamber defining a processing volume, wherein a substrate support is disposed within the processing volume, and a gas distribution plate connected to a radio frequency (RF) power source is disposed over the substrate support. A peripheral portion of the substrate support portion is connected to the high-frequency power source via a plurality of RF feedback straps;
Flowing one or more processing gases through the distribution plate and into the processing volume;
Applying high frequency power to the gas distribution plate to generate plasma from the one or more processing gases within the processing volume;
The method wherein the impedance of one or more RF return straps is altered to adjust the local plasma distribution between the gas distribution plate and the substrate.   The impedance of the one or more RF feedback straps may be adjusted by adjusting the location of the RF feedback strap, by adjusting the length of the RF feedback strap, or between the RF feedback straps. 2. Modified by adjusting the spacing, by adjusting the width of the RF feedback strap, by adding a variable capacitor to the RF feedback strap, or a combination thereof. The method described in 1.   The method of claim 2, wherein impedance is changed by moving the RF return strap away from any corner of the substrate support.   The method of claim 2, wherein the impedance is changed by lengthening the RF feedback strap disposed near a corner of the substrate support.   The method of claim 2, wherein adjusting impedance comprises widening the RF return strap disposed far from a corner of the substrate support.   The method of claim 2, wherein impedance is altered by increasing the spacing between the RF feedback straps located near corners of the substrate support. An apparatus for processing a substrate,
A chamber body defining a processing volume, the chamber body having a slit valve opening configured to allow passage of a substrate;
A substrate support disposed within the processing volume, the substrate support configured to receive a substrate on a support surface and support the substrate during processing;
A gas distribution plate disposed above the substrate support in the processing volume, the gas distribution plate configured to deliver one or more processing gases;
A high-frequency power source connected to the gas distribution plate;
A plurality of RF feedback straps connected between a peripheral portion of the substrate support portion and the high-frequency power source, wherein impedance between the substrate support portion and the high-frequency power source is the peripheral portion of the substrate support portion And a plurality of RF return straps arranged to vary along.   8. The apparatus of claim 7, wherein the substrate support is polygonal and no RF return strap is connected to a corner of the substrate support.   The impedance between the substrate support and the high-frequency power source may be caused by changing the length of the RF feedback strap or by changing the width of the RF feedback strap. 9. The device of claim 8, wherein the device is varied by changing the spacing of, by adding a variable capacitor to the RF feedback strap, or a combination thereof.   The apparatus of claim 9, wherein the RF return straps along the side of the substrate support differ in length, width, or spacing. An apparatus for processing a substrate,
A chamber body defining a processing volume;
A first electrode disposed within the processing volume;
A second electrode disposed in the processing volume, facing the first electrode, wherein the first electrode and the second electrode form a plasma volume therebetween; Electrodes,
A high frequency power source coupled to the first electrode;
A plurality of RF feedback straps connected between the second electrode and the body at a predetermined potential, connected to the periphery of the second electrode, and the impedances of the plurality of RF feedback straps are An apparatus comprising a plurality of RF return straps that vary along the periphery of the second electrode.   The apparatus of claim 11, wherein the plurality of RF return straps differ in length, width, spacing, or a combination thereof.   The apparatus of claim 12, wherein at least one of the plurality of RF feedback straps comprises a capacitor.   The apparatus of claim 12, wherein the plurality of RF return straps are disposed far from any corner of the second electrode.   The apparatus of claim 14, wherein the RF feedback strap disposed near the slit valve opening has a smaller impedance than the RF feedback strap far from the slit valve opening.

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