Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
  • H01L21/3065—Plasma etching; Reactive-ion etching
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32458—Vessel
  • H01J37/32477—Vessel characterised by the means for protecting vessels or internal parts, e.g. coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/02—Details
  • H01J2237/022—Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10S156/914—Differential etching apparatus including particular materials of construction
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10S156/916—Differential etching apparatus including chamber cleaning means or shield for preventing deposits
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12347—Plural layers discontinuously bonded [e.g., spot-weld, mechanical fastener, etc.]

Definitions

• the present invention relates generally to the fabrication of semiconductor wafers, and, more particularly, to high density plasma etching chambers having lining materials that reduce particle and metallic contamination during processing, and associated chamber lining structures.
• the manufacturing of the integrated circuit devices includes the use of plasma etching chambers, which are capable of etching selected layers defined by a photoresist mask.
• the processing chambers are configured to receive processing gases (i.e., etch chemistries) while a radio frequency (RF) power is applied to one or more electrodes of the processing chamber.
• RF radio frequency
• the pressure inside the processing chamber is also controlled for the particular process.
• the process gases in the chamber are activated such that a plasma is created.
• the plasma is thus configured to perform the desired etching of the selected layers of the semiconductor wafer.
• a processing chamber that is used for etching materials such as silicon oxides requires relatively high energies to achieve the desired etch result, compared to other films etched during fabrication.
• silicon oxides include, for example, thermally grown silicon dioxide (SiO 2 ), TEOS, PSG, BPSG, USG (undoped spin-on-glass), LTO, etc.
• the need for high energies stems from the need to bombard and break the strong bonds of the silicon oxide films and drive chemical reactions to form volatile etch products.
• These chambers are therefore referred to as "high density oxide etch chambers," that are capable of producing high plasma densities in order to provide a high ion flux to the wafer and achieve high etch rates at low gas pressures.
• chambers are now designed to permit the use of simple lining parts, such as, disks, rings, and cylinders. Because these parts are configured to confine the plasma over the wafer being processed, these parts are continuously exposed and attacked by the processing plasma energies. Due to this exposure, these parts ultimately erode or accumulate polymer buildup, requiring replacement or thorough cleaning. Eventually, all parts wear out to the point that they are no longer usable. These parts are hence referred to as “consumables. " Therefore, if the part's lifetime is short, then the cost of the consumable is high (i.e., part cost/part lifetime).
• Some of this aluminum becomes embedded in an organic polymer that is deposited on the wafer during etching and on the surfaces of the consumable parts (i.e., chamber liners, covers, and the like). When this happens, the polymer on the surface of the consumable parts may not be able to be completely cleaned during a conventional in-situ plasma clean or "ash" step. Thus, a friable, flaking film or powdery coating that includes C, Al, O, and F is left behind after the in-situ plasma clean, and therefore results in high particle counts.
• the aluminum deposited in structures being etched and the films on the silicon wafer can cause degradation of devices subsequently formed, for example, by increasing leakage current in DRAM cells.
• quartz is also used as the material of the interior surfaces of the consumable parts.
• quartz surfaces have been found to be an unfortunate source of particles due to the low thermal conductivity of quartz and the high etch rates in high density plasmas used to etch oxides. Additionally, low thermal conductivity quartz makes surface temperature control of these parts very difficult. This results in large temperature cycling and flaking of the etch polymer deposited on the surface of the consumable parts, and therefore causes the unfortunate generation of contaminating particles.
• a further disadvantage of quartz consumable parts is that the high etch rate in high density oxide etchers tends to cause pitting in the quartz, which then results in spalling of quartz particles.
• the present invention fills these needs by providing temperature controlled, low contamination, high etch resistant, plasma confining parts (i.e., consumables) for use in plasma processing chambers. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device or a method. Several inventive embodiments of the present invention are described below.
• a plasma processing chamber including an electrostatic chuck for holding a wafer, and having consumable parts that are highly etch resistant, less susceptible to generating contamination and can be temperature controlled.
• the consumable parts include a chamber liner having a lower support section and a wall that is configured to surround the electrostatic chuck.
• the consumable parts also include a liner support structure having a lower extension, a flexible wall, and an upper extension.
• the flexible wall is configured to surround an external surface of the wall of the chamber liner, and the liner support flexible wall is spaced apart from the wall of the chamber liner.
• the lower extension of the liner support is however, configured to be in direct thermal contact with the lower support section of the chamber liner.
• a baffle ring is part of the consumable parts, and is configured to be assembled with and in thermal contact with the chamber liner and the liner support.
• the baffle ring defines a plasma screen around the electrostatic chuck.
• a heater is then capable of being thermally connected to the upper extension of the liner support for thermally conducting a temperature from the liner support to the chamber liner and the baffle ring.
• an outer support that is thermally connected to a cooling ring that is coupled to a top plate of the chamber. The outer support and the cooling ring are therefore capable of providing precision temperature control to the chamber liner, along with a cast heater.
• consumable parts including the chamber liner and the baffle ring are made completely from or coated with a material selected from silicon carbide (SiC), silicon nitride (Si 3 N 4 ), boron carbide (B 4 C) and/or boron nitride (BN) material.
• SiC silicon carbide
• Si 3 N 4 silicon nitride
• B 4 C boron carbide
• BN boron nitride
• a plasma etching chamber having consumable parts in another embodiment, includes a chamber liner having a lower support section and a cylindrical wall that surrounds a center of the plasma etching chamber.
• a liner support that is configured to surround the chamber liner.
• the liner support is thermally connected to the lower support section of the chamber liner.
• the liner support further includes a plurality of slots that divide the liner support into a plurality of fingers.
• the chamber liner is made from a material selected from one of a silicon carbide (SiC) material, a silicon nitride (Si 3 N 4 ) material, a boron carbide (B 4 C) material, and a boron nitride (BN) material, and the liner support is made from an aluminum material.
• SiC silicon carbide
• Si 3 N 4 silicon nitride
• B 4 C boron carbide
• BN boron nitride
• the method includes use of a chamber liner from a material selected from one of a silicon carbide (SiC) material, a silicon nitride (Si 3 N 4 ) material, a boron carbide (B 4 C) material, and a boron nitride (BN) material.
• the chamber liner can have a wall that surrounds a plasma region of the chamber and a lower support section.
• the method can include use of an aluminum liner support optionally having a lower extension, a flexible wall and an upper extension wherein a plurality of slots are provided in the flexible wall and the lower extension of the liner support to enable the liner support to expand at elevated temperatures.
• the method optionally includes use of a baffle ring of silicon carbide (SiC), silicon nitride (Si,N 4 ), boron carbide (B 4 C) and/or boron nitride (BN).
• a plurality of slots can be provided in the baffle ring to define a plasma screen.
• the method can include thermal control of the chamber liner via a thermal path through the liner support and the baffle ring.
• a plasma processing chamber includes a chamber liner and a liner support, the liner support including a flexible wall configured to surround an external surface of the chamber liner, the flexible wall being spaced apart from the wall of the chamber liner.
• a heater can be thermally connected to the liner support so as to thermally conduct heat from the liner support to the chamber liner.
• the liner support is preferably made from flexible aluminum material and the chamber liner preferably comprises a ceramic material.
• the liner support can have various features.
• the flexible wall can include slots which divide the liner support into a plurality of fingers which enable the flexible wall to absorb thermal stresses and/or a lower extension of the liner support can be fixed to a lower support section of the chamber liner.
• a baffle ring in thermal contact with the chamber liner and the liner support can be used to define a plasma screen around an electrostatic chuck located in a central portion of the chamber.
• the chamber liner and/or baffle ring are preferably made from one or more of silicon carbide (SiC), silicon nitride (Si,N 4 ), boron carbide (B 4 C), and boron nitride (BN).
• the plasma processing chamber can include various features.
• the chamber liner can have low electrical resistivity and be configured to provide an RF path to ground.
• a gas distribution plate having high electrical resistivity can be provided over an electrostatic chuck and/or a pedestal supporting a focus ring and the electrostatic chuck.
• the gas distribution plate, the focus ring and/or the pedestal are preferably made from one or more of the silicon carbide (SiC), silicon nitride (Si 3 N 4 ), boron carbide (B 4 C), and boron nitride (BN).
• the plasma can be generated in the chamber by an RF energy source which inductively couples RF energy through the gas distribution plate and generates a high density plasma in the chamber.
• the RF energy source preferably comprises a planar antenna.
• the chamber can be used for plasma processing semiconductor wafers.
• the chamber can be a plasma etching chamber.
• the liner can have various configurations.
• the liner support can include an outer support thermally connected to a lower extension of the liner support and the outer support can be in thermal contact with a water cooled top plate mounted on the chamber.
• the liner support can also include an upper extension, a flexible wall, and a lower extension, wherein the flexible wall and the lower extension have a plurality of slots that define a plurality of fingers in the liner support.
• a cast heater ring can be located in thermal contact with the liner support, the heater ring including a resistance heated element which heats the liner support so as to thermally control the temperature of the chamber liner.
• a semiconductor substrate is processed in a plasma processing chamber having a chamber liner and a liner support, the liner support including a flexible wall configured to surround an external surface of the chamber liner, the flexible wall being spaced apart from the wall of the chamber liner wherein a semiconductor wafer is transferred into the chamber and an exposed surface of the substrate is processed with a high density plasma.
• the chamber liner is preferably a ceramic material and the liner support preferably includes an outer support extending between the liner support and a temperature controlled part of the chamber, the outer support being dimensioned to minimize temperature drift of the chamber liner during sequential processing of a batch of semiconductor wafers.
• the ceramic liner is preferably removed from the chamber and replaced with another ceramic liner after processing a predetermined number of semiconductor wafers.
• the chamber liner can include a wafer entry port enabling passage of the wafer into the chamber.
• Figure 1 shows a high density plasma etching chamber in accordance with one embodiment of the present invention
• Figures 2A through 2C illustrate in more detail a baffle ring in accordance with one embodiment of the present invention
• Figure 3A shows a more detailed cross-sectional diagram of a liner support in accordance with one embodiment of the present invention
• Figure 3B shows a side view of the liner support from cross section A-A of Figure 3A, in accordance with one embodiment of the present invention
• Figure 3C illustrates the flexibility of the liner support when subjected to temperature stresses in accordance with one embodiment of the present invention
• Figure 4 illustrates how the chamber liner is assembled with the liner support in accordance with one embodiment of the present invention
• Figure 5A shows a partial cross-sectional view of the chamber liner, the liner support, and the baffle ring, assembled in accordance with one embodiment of the present invention
• Figure 5B shows a side view of an outer support in accordance with one embodiment of the present invention
• Figure 6 illustrates a three-dimensional assembled view of the chamber liner, the baffle ring, and the liner support, in accordance with one embodiment of the present invention
• Figure 7 shows another three-dimensional view of the assembled chamber liner, liner support, and the baffle ring, in accordance with one embodiment of the present invention.
• Figure 8 shows an exploded view of portions of the high-density plasma etching chamber of Figure 1 in accordance with one embodiment of the present invention.
• the invention provides one or more temperature controlled, low contamination, high etch resistant, plasma confining parts (i.e. , consumables) for use in plasma processing chambers.
• plasma confining parts i.e. , consumables
• numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be understood, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.
• the plasma confining parts of the present invention are preferably in the form of, for example, chamber liners, baffle rings, gas distribution plates, focus rings, liner supports, and other non-electrically driven parts. These parts are preferably configured to be substantially non-contaminating and etch resistant, and they are preferably temperature controlled without damaging the parts.
• the plasma confining parts are preferably made from materials that consist of elements that are innocuous to devices being fabricated on the wafer, such as silicon (Si), carbon (C), nitrogen (N), or oxygen (O). In this manner, when the plasma confining parts are bombarded by ions (i.e. , sputtered by the plasma), volatile products that combine with the process gases are produced.
• the plasma confining parts of the present invention are preferably made from one or more materials such as, for example, silicon carbide (SiC), silicon nitride (Si 3 N 4 ), boron carbide (B 4 C), and boron nitride (BN). These materials all have the desirable characteristics of having high etch resistance, non-contaminating elements, and volatile etch products.
• the plasma confining parts also referred to as consumable parts
• SiC solid silicon carbide
• the SiC used for the baffle ring 132 and liner 130 is preferably electrically conductive so that when it is in contact with the plasma it presents a good ground path for the RF current.
• SiC can be used for a gas distribution plate ("GDP") (i.e. , 120 of Fig. 1) in order to permit inductive coupling of RF power through it.
• GDP gas distribution plate
• the SiC also etches at a slow rate by the plasma making it a cost-effective consumable part.
• the SiC is of high purity, wafer contamination resulting from chemical sputtering of the SiC by the plasma can be minimized. Further, the grounded SiC can reduce sputtering of other surfaces in the chamber by causing a reduction in the plasma potential and hence ion bombardment energy to any non- silicon carbide surfaces.
• the SiC component also provides a very stable plasma potential so that etch results are more repeatable within an individual chamber and from chamber to chamber.
• FIG. 1 shows a high density plasma etching chamber 100 in accordance with one embodiment of the present invention.
• a chamber housing 102 is shown containing a semiconductor substrate such as a silicon wafer 104, that may be subjected to a plasma etching operation.
• the etching operating is preferably a high density plasma operation that is configured to etch materials such as silicon oxides, that may be formed on the surface of the wafer 104.
• the high density e.g.
• plasmas having a densities between about lC ⁇ -lO 12 ions/cm 3 ) plasma is established in the chamber by ensuring that the cr mber is held at a relatively low pressure of below about 80 mTorr, and most preferably between about 1 mTorr and about 40 mTorr.
• the pressure in the chamber is generally maintained by implementing a suitable vacuum pump at the bottom of the chamber.
• the wafer 104 is shown supported over an electrostatic chuck 106. Beneath the electrostatic chuck 106 is a lower electrode 108 which contains a backside cooling ring 110 for controlling the temperature of the electrostatic chuck 106.
• the electrostatic chuck 106 is confined by a pedestal 112 and a focus ring 114 that surrounds the wafer 104.
• the pedestal 112 and the focus ring 114 are preferably made from a material selected from a group including: (a) silicon carbide (SiC), (b) silicon nitride (S ⁇ N 4 ), (c) boron carbide (B 4 C), or (d) boron nitride (BN).
• Si 3 N 4 is selected as the material for the pedestal 112 and the focus ring 114.
• an insulating alumina ring 116 sits between an aluminum pedestal 118 and the lower electrode 108 and the silicon carbide pedestal 112.
• a chamber liner 130 is preferably a cylindrical liner which can be attached to a baffle ring 132.
• the baffle ring 132 generally includes an inner ring 132a that makes good electrical contact as well as good thermal contact with the chamber liner 130.
• the baffle ring 132 also has an integral array of teeth 132b which will be described in greater detail with reference to Figures 2A through 2C.
• GDP gas distribution plate
• Above the wafer 104 is a gas distribution plate (GDP) 120 which functions as a showerhead to release the etch gas chemicals into the processing chamber. Above the gas distribution plate 120 sits a ceramic window 122.
• an RF coil system 120 i.e., an RF antenna
• the RF coils 120 are preferably cooled via a cooling channel that is integrated at the center of the RF coils 120.
• a gas feed port 126 is used to feed processing gases into channels that are defined between the ceramic window 122 and the gas distribution plate 120.
• TCP 9100TM plasma etching reactor which is available from LAM Research Corporation, of Fremont, California.
• An RF impedance matching system 127 is configured to mount over the processing chamber and make suitable contact with the RF coils 122 in order to control the delivery of power as well as other reactor controlling parameters.
• the ceramic window 122 is designed to be in contact with the gas distribution plate that mounts within a top plate 124.
• the top plate 124 defines an interface between atmospheric pressure and a desired vacuum condition within the high density plasma etching chamber 100.
• the desired pressure interface is established by placing a suitable number of O-rings between interfaces of the chamber housing 102, the top plate 124, the GDP 120, the ceramic window 122, and the RF match system 127.
• a liner support 134 is also provided within the high density plasma etching chamber 100 to enable precision control and transfer of a desired temperature to the chamber liner 130 and the baffle ring 132.
• the liner support 134 is made of aluminum to facilitate its flexibility and improve its thermal conductivity.
• the liner support 134 includes an upper extension 134a, a flexible wall 134b, a lower extension 134c, and a liner support extension 134d.
• the lower extension 134c is shown assembled in direct thermal contact with the chamber liner 130, and the baffle ring 132.
• the flexible wall 134b is slightly separated from the chamber liner 130.
• a heater 140 is capable of being secured in direct thermal contact with the upper extension 134a of the liner support 134.
• a power connection 142 is used to couple to a heater power system 129.
• the liner support is therefore well suited to control a desired temperature that can be thermally transferred to the chamber liner 130 and the baffle ring 132 without causing damage to the (more brittle) chamber liner 130 or baffle ring 132.
• an outer support 131 which is thermally connected to the lower extension 134c of the liner support 134.
• the outer support is also thermally coupled to the top plate 124, which is designed to receive a cooling ring 121.
• the outer support 131 is used to achieve precision temperature control of the chamber liner 130 during wafer processing operations (e.g. , etching).
• the precision temperature control provided by the outer support 131 and cooling ring 121 will therefore advantageously assist in preventing the chamber liner temperature from gradually drifting upwards (due to the plasma energies) faster than the liner's ability to radiate the heat to its surroundings.
• the chamber liner 130 and the baffle ring 132 are preferably made of a pure silicon carbide material.
• the gas distribution plate 120, the focus ring 114 and the pedestal 112 are also made of a pure silicon nitride or carbide materials, or at least silicon carbide coated. In this manner, substantially all of the surfaces that confine the high density plasma will be pure silicon carbide, or coated silicon carbide.
• other materials that consist only of elements that are innocuous to devices on the wafer being processed, such as silicon (Si), carbon (C), nitrogen (N), or oxygen, which form volatile etch products with the etch gases, may be used.
• the volatile products produced when the internal surfaces that confine the plasma are bombarded will mix with the excess etch gases that are commonly removed from the chamber (using a vacuum pump or the like). Because the products produced when the plasma bombards the internal surfaces of the chamber (i.e., the consumable parts) are volatile, these products will not end up on the surface of the wafer causing contamination, nor end up embedded in the polymer deposited on the consumable parts.
• FIGs 2A through 2C illustrate in more detail the baffle ring 132 in accordance with one embodiment of the present invention.
• the baffle ring 132 functions as a plasma screen for the passage of gases and byproducts to a vacuum pump connected at the bottom of the chamber 102.
• the baffle ring 132 has an array of teeth 132b that assist in maintaining the plasma in the top half of the chamber 102, where the silicon carbide surfaces (of the consumables) confine the plasma substantially over the wafer 104.
• the baffle ring 132 also has an inner ring 132a which is used to make good thermal contact with the chamber liner 130.
• Figure 2B is a three-dimensional view of a pair of teeth 132b.
• the open areas provided by the spaces 132c are configured such that a percentage ranging between 50 and 70 percent open area is maintained to allow a sufficient passageway for the gases and by-products to be pumped out of the chamber 102.
• the solid silicon carbide material (or coated SiC material) must be machined such that a suitable aspect ratio that is at least 1.5 or greater, is maintained.
• the width of the spaces 132c are preferably set to about 0.13 inch, and the height is set to about 0.28 inch. These preferred dimensions therefore provide an aspect ratio of about 2.0.
• the inner diameter (ID) of the baffle ring 132 in this 200 mm wafer chamber embodiment, is set to about 10.75 inches, such that about 1/16 inch clearance is provided between the pedestal 112 shown in Figure 1.
• the inner diameter (ID) may of course be larger, depending upon the size of the wafer being processed. For example, for a 300 mm wafer, the inner diameter may be as large as about 14 inches.
• the baffle ring 132 may be manufactured such that the teeth 132b are replaced with an array of holes or slots. When an array of holes or slots are manufactured in place of the teeth 132b, it is still desired to maintain an open area (i.e. , pathway), that amounts to between about 50 percent and 70 percent.
• the baffle ring 132 is also shown having a plurality of screw holes 150 which are designed around the outer ring 132a. As shown in Figure 1, the screw holes 150 will be configured to receive a suitable screw that will help interconnect the baffle ring 132 to the chamber liner 130 and the liner support 134.
• FIG 3 A shows a more detailed cross-sectional diagram of the liner support 134 in accordance with one embodiment of the present invention.
• the liner support 134 has a flexible wall 134b which is configured to flex in response to heat deformation that may occur when the heater 140 applies the desired heat level.
• the flexible wall 134b is cylindrical and is slotted into a plurality of fingers.
• the liner support is preferably made of an aluminum material which will have good thermal conductivity and will also provide good flexibility when a desired temperature is applied by the heater 140.
• the lower extension 134c is bolted to the chamber liner 130 and the baffle ring 132, the lower extension 134c will remain in place while the upper extension 134a, which is coupled to the heater 140 at a heat- conductive interface 141, may be able to flex outwardly as illustrated in Figure 3C.
• the heater 140 is preferably secured to the upper extension 134a using a suitable number of screws 144 to ensure that the heat conductive interface 141 is maintained all the way around the upper extension 134a.
• the screws 144 will be capable of maintaining the heater 140 in contact with the upper extension 134a with a pressure of about 1,000 pounds per square inch.
• the liner support 134 may have an inner diameter of about 14 Vi inches.
• the thickness 170 of the flexible wall 134b may range between about 1/16 inch and about 3/32 inch.
• the 1/16 inch dimension is preferably used for processing temperatures ranging up to about 300° C, while the 3/32 dimension is reserved for chambers having processing temperatures up to about 1000° C.
• the separation 176 between the lower extension 134c and the upper extension 134a is preferably set to about 2 1 / 2 inches, depending upon the chamber height. However, the greater the separation 176 is, the greater the thermal resistance in the liner support 134. Therefore, the separation 176 is kept just short enough such that the aluminum material of the liner support will not become too stressed as temperatures reach 300° C and above.
• the exemplary thickness 172 for the upper extension 134a is preferably set to about 9/16 inch, while the exemplary thickness of the lower extension 134c is set to about 5/8 inch.
• FIG 3B shows a side view of the liner support 134 from cross section A-A of Figure 3A, in accordance with one embodiment of the present invention.
• slots 152 are defined into the sides of the liner support 134 defining a plurality of fingers.
• the slots 152 vertically extend through the flexible wall 134b and through the lower extension 134c.
• the separation between the slots 152 must be configured such that a suitable level of flexibility remains in the flexible wall 134b. Therefore, the separation between slots 152 is preferably set to about 15 degrees. However, the actual separation between the slots 152 may vary and also change depending upon the diameter of the liner support 134 and the degree of flexibility that is desired.
• the screw holes 150 which are defined in the lower extensions 134c.
• Figure 3C shows the liner support extending outwardly from a Y axis (relative to a horizontal X-axis) to achieve a separation 133.
• the separation may be as much as 1/16 inch, or more.
• the liner support 134 will advantageously be able to withstand the thermal stress placed on the aluminum material of the liner support 134, while insulating the less flexible chamber liner 130 and the baffle ring 132 from temperature deforming stresses.
• Figure 4 illustrates how the chamber liner 130 is assembled with the liner support 134 in accordance with one embodiment of the present invention.
• the chamber liner 130 when the chamber liner 130 is made of silicon carbide, it will provide a high integrity RF return path to ground for the powered electrode 108 (bottom electrode).
• the grounded SiC can reduce sputtering of other surfaces in the chamber by causing a reduction in the plasma potential and hence ion bombardment energy on any non-silicon carbide surfaces.
• the materials used for the chamber liner 130 can have their electrical resistivity modified over a wide range.
• the resistivity of SiC can be tailored for the specific application.
• the SiC is modified to provide a low resistivity that will facilitate the good conductive path to ground for the RF power.
• high resistivity is needed when the part must have RF power inductively coupled through it, in order to minimize power dissipation in the part.
• high resistivity SiC is preferably used for the gas distribution plate (GDP) 120.
• the screw holes 150 are configured to go through the chamber liner 130 at a lower support section and then go into the liner support 134.
• a suitable number of screws are used to interconnect the chamber liner 130 and the liner support 134 such that a good thermally conductive interface 156 is maintained. In this manner, the heat conducted through the liner support 134 may be thermally communicated to the chamber liner 130 and the baffle ring 132.
• the liner support 134 is preferably spaced apart from the chamber liner 130 by a space 154.
• the space 154 is preferably set to about 1/16 inch. This separation is generally desired because the liner support 134 is configured to flex as described with reference to Figure 3C.
• a diameter 179 of the chamber liner 130 is about 14 inches.
• the thickness of the chamber liner 130 is preferably set, in this embodiment, to be between about 0.1 inch and about 0.3 inch, and most preferably, to about 0.2 inch.
• the height 177 of this exemplary chamber liner may be between about 3 inches and about 12 inches, and most preferably about 5 inches.
• the outer support 131 which is thermally connected to the lower extension 134c of the liner support 134.
• the outer support is spaced apart from the flexible wall 134b so that it can flex without substantial obstruction.
• the outer side of the outer support 131 has an upper extending wall having a surface 123' , which is configured to make good thermal contact with the top plate 124.
• a cooling ring 121 shown in more detail in Figure 5A, can be used to control the temperature of the chamber liner 130 and the internal regions of the chamber. Accordingly, through the combined simultaneous control of both the heater 140 and cooling ring 121, the temperature of the chamber liner 130 can be maintained to within less than + 10 degrees C from a no plasma condition through a sustained plasma on condition.
• the first wafer etched can be etched with the same chamber liner 130 temperature as the last wafer etched, to within the ⁇ 10 degrees C variation.
• Figure 5 A shows a partial cross-sectional view of the chamber liner 130, the liner support 134, and the baffle ring 132 assembled in accordance with one embodiment of the present invention. As shown, the chamber liner 130 and the liner support 134 are assembled to achieve a good thermal conductive interface 156 as described above.
• the outer support 131 is thermally connected to the lower extension 134c through a plurality of screws 135.
• the outer support 131 in a most preferred embodiment, has a flexible wall 131a, which is shown to be thermally connected to the top plate 124.
• a side view of the outer support 131 is also provided in Figure 5B, to illustrate how a plurality of fingers 13 Id, separated by a plurality of slots 131c, assist in providing the necessary flexibility to the flexible wall 131a.
• the top plate 124 is further configured to receive the cooling ring 121 on a top lip of the top plate 124. Of course, other configurations for applying the cooling ring 121, or other type of cooling system, to the top plate 124 may be used.
• the combined use of the heater 140 and the cooling ring 121 will enable precision temperature control in narrow temperature ranges.
• the chamber liner 130 is typically run at high temperatures, such as 200 degrees C or more, while heat is lost to the surroundings primarily through radiation.
• the plasma dumps more heat into the chamber liner 130 by ion bombardment.
• the chamber liner 130 will slowly increase in temperature over time because it generally cannot transfer this heat to its surroundings by radiation as fast as it gains heat from the plasma.
• the outer support 131 which is thermally coupled to the cooling ring 121, is well suited to eliminate the chamber liner's temperature drift.
• the heat loss to the outer support 131 from the liner support 134 can be set by adjusting the cross-section and length of the outer support 131. This adjustment, can therefore be made to control the heat loss path from the liner support 134 to the temperature controlled top plate 124.
• the chamber liner 130 will also provide a good thermal conductive interface 157 with the baffle ring 132.
• the baffle ring 132, the chamber liner 130, and the liner support 134 are secured together using a plurality of screws 150' .
• the screws 150' are fitted through a spacer ring 131b which is in direct contact with the inner ring 132a of the baffle ring 132, a spacer 131a' , and the chamber liner 130.
• the spacer ring 131b and the spacer 131a' are preferably made of aluminum and provide a good surface for applying pressure to the screws 150' and the brittle surfaces of the baffle ring 132 and the chamber liner 130. That is, because the baffle ring 132 is preferably a ceramic, applying too greater of a force with screws directly to the baffle ring may cause a crack in the baffle ring or the chamber liner 130.
• these parts are referred to as consumable parts, however, when silicon carbide (or other alternative materials described herein) is used for the parts that confine the high density plasma, these parts will have a longer lifetime, and therefore, a lower cost of consumables.
• the liner support 134 When replacement is needed, these parts may be swiftly replaced with replacement parts (i.e., using a quick clean kit). Because the liner support 134 is not designed to be in contact with the high density plasma, it may not wear out as fast as the chamber liner 130 and the baffle ring 132. Thus, the liner support 134 may be removed from worn out consumable parts (that may be cleaned off-line and re-used or discarded), and then used with the replacement consumable parts. When the chamber is being used in fabrication where chamber down time translates into lower yields, the ability to quickly replace these consumables will have the benefit of reducing the mean time to clean the chamber.
• Figure 6 illustrates a three-dimensional assembled view of the chamber liner 130, the baffle ring 132, and the liner support 134, in accordance with one embodiment of the present invention.
• the top surface of the upper extension 134a of the liner support 134 is configured with a plurality of screw holes that will receive the heater 140.
• the plurality of slots 152 are configured to flex in response to temperature variations.
• a wafer entry port 160 is defined in the wall of the chamber liner 130 to enable the passage of a wafer into and out of the chamber 100.
• the wafer is preferably passed into the chamber using a robot arm which must partially fit into the port 160, and release the wafer once over the electrostatic chuck 106.
• the port 160 should be large enough to receive the wafer and robot arm, but also maintained small enough to not disrupt the plasma profile over the wafer.
• an insert with a slot in the shape of the port 160 is attached to the outside of the liner.
• the insert can be of SiC, Si 3 N 4 , B 4 C and/or BN.
• the liner support 134 typically also includes through holes 162 which are also defined in the chamber liner 130.
• the through holes 162 may include holes for probing the pressure within the chamber during processing, and for optically detecting the endpoint in a particular process.
• plurality of holes 161 which are used to receive the screws 144 for holding down the heater 140 to the upper extension 134a of the liner support 134.
• Figure 7 shows another three-dimensional view of the assembled chamber liner 130, liner support 134, and the baffle ring 132. From this view, the port hole 160 used for passing a wafer to the electrostatic chuck 106, is shown in greater detail. Also shown are the teeth 132b of the baffle ring 132. The teeth 132b therefore extend in close proximity to the pedestal 112 to screen the plasma from the lower part of the chamber as shown in Figure 1.
• Figure 8 shows an exploded view of portions of the high-density plasma etching chamber 100 of Figure 1 in accordance with one embodiment of the present invention. This view shows the spacer ring 131b that is used in the assembly of the baffle ring 132, the chamber liner 130, and the liner support 134.
• the heater 140 is applied over the top extension 134a of the liner support 134.
• the heater 140 is preferably a cast heater. Of course, other types of heating systems may also work. When the heater 104 is appropriately secured, a good thermal contact will be made with the liner support 134.
• the power connection 142 is also shown, which will be passed through a hole 124a in the top plate 124.
• the top plate 124 is shown capable of receiving the gas distribution plate 120.
• the gas distribution plate 120 has channels 120a which enable processing gases fed by gas feed ports 126 to be directed into the chamber 100.
• the ceramic window 122 may then be lowered over the gas distribution plate 120.
• the high density plasma etch chamber 100 is particularly well suited to etch silicon oxide materials, such as, for example, thermally grown silicon dioxide (SiO 2 ), TEOS, PSG, BPSG, USG (undoped spin-on-glass), LTO, etc., while reducing the introduction of unwanted contaminants.
• silicon oxide materials such as, for example, thermally grown silicon dioxide (SiO 2 ), TEOS, PSG, BPSG, USG (undoped spin-on-glass), LTO, etc.
• the pressure within the chamber is preferably maintained below about 80 mTorr, and the RF coil 128 (i.e., top electrode) is preferably set to between about 2500 watts and about 400 watts, and most preferably to about 1,500 watts.
• the bottom electrode 108 is preferably maintained between about 2500 watts and about 700 watts, and most preferably at about 1,000 watts.
• process gases such as, CHF 3 , C 2 HF 5 and/or C 2 F 6 are introduced into the chamber to generate the desired etching characteristics.
• the materials that can be used for the plasma confining parts are generally innocuous to layers being fabricated on the wafer 104. That is, volatile etch products that result from etching the surfaces of the wafer 104 will be similar to the volatile products produced when the consumables are bombarded (i.e., sputtered) with the plasma energies. As an advantageous result, these volatile products produced from ion bombardment of the consumables will join the normal volatile etch products.
• the material may also be a SiC coated material such as SiC coated graphite, or principally SiC with 10 to 20% Si added to fill porosity in reaction bonded SiC.
• the consumable parts may also be made from materials such as, silicon nitride (Si 3 N 4 ), boron carbide (B 4 C), and boron nitride (BN). These materials all have the desirable characteristics of having high etch resistance, non-contaminating elements, and volatile etch products.

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• 1998
  • 1998-09-25 US US09/161,074 patent/US6129808A/en not_active Expired - Lifetime
• 1999
  • 1999-09-24 CN CNB998112860A patent/CN1328755C/zh not_active Expired - Fee Related
  • 1999-09-24 AU AU14401/00A patent/AU1440100A/en not_active Abandoned
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• 2000
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