Classifications

• • H01L21/205—
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
  • C23C16/4404—Coatings or surface treatment on the inside of the reaction chamber or on parts thereof
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/22—Surface treatment of glass, not in the form of fibres or filaments, by coating with other inorganic material
  • C03C17/225—Nitrides
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2217/00—Coatings on glass
  • C03C2217/20—Materials for coating a single layer on glass
  • C03C2217/28—Other inorganic materials
  • C03C2217/281—Nitrides
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2217/00—Coatings on glass
  • C03C2217/20—Materials for coating a single layer on glass
  • C03C2217/28—Other inorganic materials
  • C03C2217/282—Carbides, silicides
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2218/00—Methods for coating glass
  • C03C2218/10—Deposition methods
  • C03C2218/15—Deposition methods from the vapour phase
  • C03C2218/152—Deposition methods from the vapour phase by cvd

Definitions

• This invention relates to the field of protective coatings, specifically the use of protective coatings to prevent damage to vitreous materials in corrosive environments. More particularly, this invention relates to the use of protective coatings to limit the devitrification of quartz components in a semiconductor reactor.
• High-temperature ovens which are typically called reactors, can be used to create structures of very fine dimensions, such as, for example, integrated circuits on semiconductor wafers or other substrates.
• the one or more substrates such as, for example silicon wafers, are placed on a wafer support inside a reaction chamber of the reactor. Inside the reaction chamber, both the wafer and the support (also called a susceptor) are heated to a desired temperature.
• Cold wall reaction chambers are a type of reaction chamber that are desirably made of quartz (vitreous silica) or other similar materials which are substantially transparent to the radiant energy used for heating the chamber. Quartz is also desirable because it can withstand very high temperatures, and because it is relatively inert ( i.e., it does not react with various processing gases typically used in semiconductor processing).
• Quartz is also typically used to build a number of other reactor components, comprising spiders, which are used to support the susceptors, and stands, which are used to support temperature compensation rings around the periphery of the susceptors. Due to its material characteristics, quartz components are also advantageous for other types of reactors that do not use radiant heating systems.
• the temperature of the reactor and the wafer during each treatment step of the processing is the temperature of the reactor and the wafer during each treatment step of the processing.
• the deposition gases react at particular temperatures and deposit on the wafer.
• deposition temperatures can affect the crystal structure of the resultant layers, from amorphous at low temperatures to polycrystalline at intermediate temperatures, to epitaxial (single crystal) at high temperatures. If the temperature varies across the surface of the wafer, uneven deposition rates can result at different points across the wafer, leading to non-uniform thicknesses. Accordingly, it is important that the wafer temperature be stable and uniform at the desired temperature both before the treatment begins and during deposition.
• temperature control can be critical include oxidation, nitridation, dopant diffusion, sputter depositions, photolithography, dry etching, plasma processes, and high temperature anneals.
• thermocouples are often used to monitor temperatures within the reactor.
• the thermocouple is typically surrounded by a protective sheath.
• the thermocouple is coaxially inserted into the protective sheath such that the heat-sensing junction of the thermocouple is placed adjacent to the bottom of the protective sheath. Accordingly, the thermocouple senses the temperature of the reactor through the protective sheath.
• sheaths should be made of a material that withstands high temperatures and thermal cycling as well as the corrosive processing environment.
• the sheath material should have good thermal conductivity, whereby the sheathed thermocouple will rapidly react to temperature fluctuations.
• the protective sheath is desirably chemically inert and of a suitable chemical purity to avoid contaminating the wafer during processing.
• the thermocouples used to measure temperature in CVD reactors are typically protected with quartz sheaths. The inventors have found that, while these quartz sheaths are useful in protecting the thermocouple during wafer processing, in corrosive environments frequent thermal cycling of the quartz sheath to temperatures in excess of 1000 °C can cause devitrification of the quartz sheath. Even in non-corrosive environments, frequent thermal cycling of the quartz sheath to temperatures in excess of approximately 1250°C can cause devitrification.
• Devitrification is a second order phase transition of amorphous quartz into cristobalite. Devitrification begins at naturally occurring nucleation sites in the amorphous quartz. This phase transition results in a twenty percent density change causing stresses to build up in the cristobalite. When the quartz sheath is allowed to cool down to approximately 275°C or below, the crystallographic inversion temperature range, the cristobalite cracks. This cracking ultimately causes the sheath to lose its protective function, leading to subsequent failure of the thermocouple, necessitating its replacement.
• thermocouples and various other chamber components subject to devitrification
• downtime for the reactor and significant costs for replacement components.
• time and expense in returning the reactor to the operating conditions necessary to produce the desired film properties on the wafers being coated.
• Replacing thermocouples and other components requires an intrusion into the chamber which can result in undesirable particle generation.
• the cristobalite transition, and resultant cracking, occurs most frequently at the tip of the thermocouple sheath where it contacts, or is in close proximity to, the hot susceptor.
• other quartz reactor components are potentially subject to the same problems of devitrification.
• any family of amorphous glass is subject to undesirable devitrification. Exposing quartz to acidic environments, in combination with high temperatures, exacerbates its devitrification. Although cristobalite can form at temperatures at or above 1150°C in the absence of an acidic environment, the rate of cristobalite formation in an acidic environment is much more rapid. Many CVD processes, e.g., etching, are performed in acidic environment. Reactor cleaning procedures also introduce acid into the chamber. Generally, in CVD reactors, the reactant material not only deposits on the substrate, as is desired, but some material is also deposited on the reactor walls and other components within the reactor.
• Reactor cleaning typically occurs by heating the wafer support, reactor walls and other reactor components to a suitably high temperature and admitting a flow of a halogen containing gas, for example HCI.
• a halogen containing gas for example HCI.
• Other typical cleaning gases include Cl 2 , NF 3 , CIF 3 , or mixtures thereof.
• the preferred embodiments of the invention provide for a chemical vapor deposition reactor for the processing of semiconductor substrates, wherein the lifetimes of some internal reactor components made of vitreous materials are extended by coating them with a barrier material layer selected for this purpose.
• a reaction chamber is in the form of a horizontally oriented quartz tube divided into an upper region and a lower region by a front divider plate, a susceptor surrounded by a temperature compensation or slip ring, and a rear divider plate.
• a susceptor mounted adjacent to the susceptor are one or more thermocouples each having a sheath made of a vitreous material which is coated with a barrier material layer which is more durable than vitreous material itself.
• the thermocouple sheath does not devitrify upon high temperature cycling and, thus, the life of the thermocouple sheath is greatly extended over that of previously used uncoated sheaths.
• the barrier material layer is especially useful in acidic environments.
• protective barrier layers are provided on various parts of the chamber to protect quartz reactor components from devitrification.
• a protective barrier is provided over a quartz sheath covering a thermocouple, thereby protecting the quartz from the processing gases.
• Protective barrier layers may also be used to cover, either partially or fully, other quartz components, such as the quartz spider supporting the susceptor or the quartz stand supporting the slip ring. It is expected that protecting quartz sheathed thermocouples and quartz components with barrier coatings will significantly increase their lifetime.
• a method for forming barrier material layers on vitreous materials.
• the method includes depositing a barrier material selected for this purpose in such a manner that the barrier layer is thin and has good adherence to the underlying vitreous material, resulting in a layer with reasonable thermal conductivity.
• Figure 1 is an exploded perspective view of an exemplary chamber containing components that may be protected with a barrier layer.
• Figure 2 is a cross-sectional view of the chamber of Figure 1.
• Figure 3 is an enlarged cross-sectional view of a thermocouples, constructed in accordance with a preferred embodiment of the invention.
• Figure 4 is a cross-sectional view showing a substrate having a plurality of thermocouples proximate a substrate support.
• FIG. 5 is a cross-sectional view of a central thermocouple with a barrier coating over a vitreous sheath.
• FIGS 1 and 2 illustrate an exemplary CVD reactor chamber 10, which provides an environment in which the preferred embodiments of the invention will be described.
• the illustrated CVD reaction chamber comprises an elongated generally flat rectangular chamber 10 made of quartz. Details of such a chamber are disclosed in pending U.S. Patent Application No. 09/184,490 of Wengert et al., filed November 2, 1998 and entitled "LONG LIFE HIGH TEMPERATURE PROCESS CHAMBER". The disclosure of the this application is herein incorporated by reference.
• the quartz chamber includes a flat upper wall 10a, a flat lower wall 10b joined by a pair of short vertical side walls 10c.
• a thickened quartz inlet flange 12 extends across the gas inlet end of the chamber attached to the chamber walls.
• a similar quartz gas outlet flange 14 is shown on the downstream end of the chamber attached to the chamber walls 10a-c.
• the illustrated chamber is divided into an upper section 15 and a lower section 17 by a quartz flat front or upstream divider plate 16 and a rear, quartz downstream plate 18 extending between the chamber side walls 10c, generally parallel to the upper and lower walls 10a, 10b.
• the divider plates 16 and 18 are supported by supports 19 (see Figure 2) formed on the side walls 10c, or by supports (not shown) extending upwardly from the chamber bottom wall.
• Such supports are typically fabricated of quartz.
• the rear chamber divider plate 18 is in approximately the same plane as the front plate 16.
• the chamber 10 is further divided by a generally flat circular susceptor 20 and a surrounding ring 22 (see Figure 1), sometimes referred to as a temperature compensation ring or a slip ring, which prevents crystallographic slip.
• the slip ring 22 will be described in more detail below with respect to Figure 4.
• the susceptor 20 is supported by a spider 24 has three arms extending radially outwardly from a central hub and has upwardly extending projections 25 on the ends of the arms engaging the susceptor.
• the spider 24 is mounted on a tubular shaft 26, which extends through the chamber lower wall 10b and also extends through a quartz tube 27 that is attached to and depends from the lower chamber wall 10b.
• the spider 24 and shaft 26 are preferably fabricated of quartz.
• the shaft 26 is adapted to be connected to a drive (not shown) for rotating the shaft 26, the spider 24 and the susceptor 20. Details such an arrangement together with a drive mechanism can be found in U.S. Patent No. 4,821,674, which is incorporated herein by reference.
• the ring 22 of the illustrated arrangement is supported by a quartz stand 23 resting on the lower chamber wall 10b.
• the ring 22 can be supported on quartz ledges extending inwardly from the chamber side walls 10c or on quartz ledges extending from the divider plates 16, 18.
• the chamber 10 may contain a number of other components which require support within the chamber 10.
• a getter plate 30 positioned downstream from the susceptor 20 and the ring 22.
• the illustrated getter plate 30 is supported on a plurality of pins 31 extending upwardly from the rear chamber divider plate 18.
• more than one getter plate 30 can be used.
• shields or heat absorbers 32 are also positioned downstream from the susceptor 20 and are preferably positioned on each side of the getter plate 30 and adjacent downstream portions of the side walls 10c.
• shields or heat absorbers 33 can also be employed on each side of the central area of the chamber adjacent the central portions of the side walls 10c. These elements 32 and 33 may be held in position by any suitable means.
• the elements 32 might be positioned by the pins 31, and spaced slightly from the chamber side walls 10c.
• the pins 31 can be fabricated of quartz.
• quartz projections can be mounted on the chamber side walls 10c and on the downstream plate 18 to position the elements 32 slightly spaced from the side walls 10c.
• the elements 33 can rest on quartz supports on the chamber lower wall 10b between the chamber side walls 10c and the quartz stand 23 positioned by suitable supports mounted on the side walls 10c to space the upper end of the element 33 slightly from the side walls 10c.
• two thermocouples 34 are supported beneath the ring by a tubular portion 22a of the ring 22, as best seen in Figure 4.
• the tubular portion 22a is configured such that it curves around the outer periphery of the ring 22. More specifically, the tubular portion 22a preferably extends along one side of the ring 22 and then extends along the front edge of the ring 22 and then to the other side of the ring 22. Preferably, one or both of the thermocouples 34 are configured to fit within the tubular portions so a tip end of thermocouples 34 can be located near the leading edge (i.e., inlet side) of the susceptor 20 at the center of the ring 22. In order to facilitate installation and removal of the curved thermocouples 34, the tubular portion 22a preferably is formed by two half sections, which are removably attached to each other.
• thermocouples may also be positioned at one side of the susceptor and/or at the trailing edge of the susceptor.
• the thermocouples may also be positioned in close proximity to the ring, depending on the allowable temperature reading error or offset.
• the reactor 10 can include additional thermocouples, as desired, in other locations within the chamber.
• a thermocouple can be provided at the trailing edge of the susceptor 20.
• the illustrated chamber 10 preferably also includes a central thermocouple 38, shown in Figures 1, 2, 4 and 5.
• the central thermocouple 38 extends upwardly through the tubular shaft 26 and spider 24, with its tip preferably located close to the center of the susceptor 20.
• each of the thermocouples 34 preferably includes a sheath 35 that surrounds a support 37, which is preferably made from a ceramic material.
• a pair of thermocouple wires 36 extend through the support 37 and form a junction 36a, which is preferably located at the forward end of the thermocouple 34 such that the junction 36a lies near the forward or upstream corners of the ring 22.
• the thermocouple 34 can include additional thermocouple junctions between additional pairs of wires within the sheath 35 . In such an arrangement, an additional junction can be located adjacent the rear or downstream corners of the ring 22 and/or between the upstream and downstream corners.
• the sheath 35 is typically made of quartz or other vitreous materials. As described in detail above, such quartz sheaths are useful in protecting the thermocouple 34 during wafer processing. However, frequent thermal cycling of the quartz sheath to temperatures in excess of 1000°C can cause devitrification of the quartz sheath. To prevent such devitrification, the thermocouple 34 includes a barrier coating 40 that is preferably formed over the sheath 35. The barrier coating 40 creates a barrier between the vitreous sheath 35 and the acidic environment within the chamber 10.
• the barrier coating 40 is very thin, extremely low in mass, has a reasonable thermal conductivity, and does not appreciably change the surface emissivity of the sheath 35.
• the barrier coating 40 preferably comprises a material that is more resistant to acids, high temperatures, and thermal cycling than the material of the underlying sheath 35.
• the following properties are desirable: capability of molecular deposition, ability to adhere to the material of the underlying sheath, resistance to spalling or flaking, non-insulating (i.e., somewhat thermally conductive), chemically stable and compatible with the environments and materials used in processing and cleaning, and not a source of metals or other contaminants.
• the barrier coating 40 is preferably between about 1 and 10,000 angstroms thick, more preferably between about 50 and 5000 angstroms thick, and most preferably between about 500 and 3000 angstroms thick.
• the barrier coating 40 comprises an approximately 800 angstrom thick layer of silicon nitride (SiN x _ which in its stoichiometric form is Si 3 N 4 ).
• the barrier coating 40 is preferably formed by CVD deposition over the corresponding vitreous component.
• CVD deposition is advantageous in that it produces a barrier layer that is both thin and that has good adhesion to the underlying component; improving the thermal conductivity of the layer.
• sputter or other known methods of material deposition may be used.
• the barrier coating 40 may comprise any high temperature acid resistant coating with similar material properties, including, for example, diamond, titanium nitride, or titanium carbon nitride.
• the barrier coating 40 preferably covers the entire vitreous component. However, in some arrangements the barrier layer can cover selected areas of the component that are more susceptible to devitrification. For example, in the illustrated arrangement, the barrier layer is deposited only over the tip of the thermocouple 34 (see Figure 3) because devitrification occurs most frequently at the tip of the thermocouple sheath 35 where it contacts, or is in close proximity to, the hot susceptor 20. Of course, in a modified arrangement, the barrier coating 40 can cover the entire thermocouple 34, a smaller/larger or different portion of the thermocouple 34. With reference to Figure 5, the barrier coating is shown with reference to another vitreous component, the central thermocouple 38.
• the illustrated central thermocouple 38 comprises thermocouple wires 50 surrounded by a quartz sheath 52.
• a barrier coating 54 is preferably provided over the quartz sheath 52 to protect the thermocouple 38 from processing gases that tend to deposit on the tip of thermocouple, and to prevent devitrification of the quartz sheath 52 as described above.
• the barrier coating 54 covers a portion of the central thermocouple 38. Specifically, in the illustrated arrangement, the barrier coating 54 covers a top portion of the thermocouple.
• vitreous components in the chamber 10 can also be wholly or partially covered with the barrier coating described above.
• the spider 24, the quartz tube 27, and the stand 23 are preferably manufactured using quartz.
• the upwardly extending projections of the spider 24, which contact and support the hot susceptor 20 can particularly benefit from a barrier coating, as described herein.
• these vitreous components can be covered wholly or partially with the barrier coating 40 so as to protect these components as described above.
• a barrier coating 40 can be provided wherever quartz is found in the chamber, so long as the barrier layer does not substantially interfere with the operation of the chamber.
• Other reactor components that may comprise quartz, and which may therefore benefit from a protective barrier layer include support pieces, pins, ledges, projections, etc. typically found within a chamber and used to support other reactor components.
• any amorphous material that is subject to devitrification may be protected with a barrier layer.
• the lifetime of vitreous components, when protected with barrier layers, may be significantly extended.
• Barrier layers are helpful in preventing devitrification in any vitreous material, including any family of glass subject to devitrification.
• life of quartz thermocouple sheaths, protected with a barrier later have been increased by approximately 300 percent. Preventing devitrification of the quartz sheath decreases calibration drift of the thermocouple.
• increasing the lifetime of vitreous components obviously results in lower consumable costs.
• extending the intervals between reactor preventive maintenance result in less down time and less reactor tuning. Less reactor tuning also results in lower use of monitor wafers.
• the use of barrier coatings to protect components comprising quartz, or other vitreous materials, in the reactor can provide very significant benefits.

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Chemical Vapour Deposition (AREA)
• Surface Treatment Of Glass (AREA)
• Glass Compositions (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=22721877

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (383)

Family Cites Families (43)

• 2001
  • 2001-04-06 KR KR1020027013453A patent/KR100752682B1/ko not_active Expired - Fee Related
  • 2001-04-06 WO PCT/US2001/011223 patent/WO2001078115A2/en not_active Ceased
  • 2001-04-06 AT AT01923194T patent/ATE342384T1/de not_active IP Right Cessation
  • 2001-04-06 US US09/828,550 patent/US7166165B2/en not_active Expired - Lifetime
  • 2001-04-06 JP JP2001575471A patent/JP2004507074A/ja not_active Withdrawn
  • 2001-04-06 DE DE60123813T patent/DE60123813T2/de not_active Expired - Fee Related
  • 2001-04-06 EP EP01923194A patent/EP1313890B1/en not_active Expired - Lifetime
• 2006
  • 2006-12-22 US US11/615,878 patent/US20070119377A1/en not_active Abandoned

Also Published As

Similar Documents

Legal Events