Reflector plate for substrate processing

Abstract

A reflective plate assembly for processing a substrate includes a reflective plate having a first surface, wherein the first surface is a bare polished surface; the reflecting disc is embedded in the reflecting plate from the first surface; a coating layer on the reflective disc; and a pyrometer disposed through the opening of the reflective disc.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to apparatus for processing substrates, and more particularly to reflective plates for rapid thermal processing. Background Art

[0002] Rapid thermal processing (RTP) is a process used to anneal substrates during semiconductor manufacturing. During this process, thermal radiation is used to rapidly heat the wafer to a maximum temperature of more than 900 degrees above room temperature in a controlled environment. The reflector used for the RTP process of the substrate uses a pyrometer to measure the wafer temperature. The reflector of the current technology is manufactured to optimize 100% reflectivity at the pyrometer wavelength (e.g., between 700nm and about 4000nm), although only 10% or less of the reflector area is used for the pyrometer. This mismatch causes unnecessary high costs. Furthermore, for purposes such as energy saving and improved wafer heating performance, the reflector should reflect radiation of the entire pyrometer wavelength at the entire surface of the wafer. However, it is expensive to combine energy saving and improved heating performance in a uniform reflector because the reflector requires an optical stack of complex multilayer coatings covering the entire reflector, which can easily crack or peel off at elevated temperatures.

[0003] There is a need for new and improved reflective plates for use in substrate processing. Summary of the invention

[0004] Embodiments of the present disclosure provide a reflective plate assembly for processing a substrate. The reflective plate assembly includes a reflective plate having a first surface, wherein the first surface is a bare polished surface; a reflective disk embedded in the reflective plate from the first surface; a coating layer on the reflective disk; and a pyrometer disposed through an opening of the reflective disk.

[0005] Embodiments of the present disclosure provide a reflective plate assembly for processing a substrate. The reflective plate assembly includes a reflective plate having a first surface, wherein the first surface is a bare polished surface; a reflective disk embedded in the reflective plate from the first surface; a coating layer on the reflective disk; a pyrometer disposed through an opening of the reflective disk; and an encapsulation layer on the coating layer.

[0006] Embodiments of the present disclosure provide a chamber for processing a substrate. The chamber includes a chamber body, a chamber cover disposed on the chamber body, and the chamber cover includes: a cover body, and a reflective plate assembly. The reflective plate assembly includes a reflective plate having a first surface, wherein the first surface is a bare polished surface; a plurality of reflective disks embedded in the reflective plate from the first surface; a coating layer on each of the plurality of reflective disks; a plurality of pyrometers, wherein each of the plurality of pyrometers is disposed through an opening of a reflective disk among the plurality of reflective disks; and an encapsulation layer on the coating layer.

[0007] BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more particular description of the present disclosure briefly outlined above may be obtained by reference to the embodiments, in which the above-mentioned features of the present disclosure may be understood in detail, some of which are illustrated in the accompanying drawings. However, it will be noted that the drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and other equally effective embodiments may be allowed.

[0009] Figure 1 is a cross-sectional view of an example RTP chamber in accordance with at least one embodiment of the present disclosure.

[0010] Figure 2 is a cross-sectional view of an example RTP chamber in accordance with at least one embodiment of the present disclosure.

[0011] Figure 3A is a top view of an example reflective panel assembly in accordance with at least one embodiment of the present disclosure.

[0012] Figure 3B is a display according to at least one embodiment of the present disclosure Figure 3A A cross-sectional view of an example reflector assembly in FIG.

[0013] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0014] Embodiments of the present disclosure relate generally to apparatus for processing substrates, and more particularly to reflective plates for rapid thermal processing.

[0015] A reflective plate assembly according to embodiments described herein includes a plurality of reflective disks having a coating thereon, the plurality of reflective disks being positioned within a reflective plate having a bare mechanically polished surface and no coating thereon. The coating of the reflective disks with gold (Au) or chromium (Cr) enhances the emissivity of the reflective disks. The coating on the reflective disks is further encapsulated by silicon oxide (SiO2) or sapphire to reduce metal contamination.

[0016] Compared to conventional reflective plates that have their entire surface coated with quartz or other materials, which can crack or peel off at elevated temperatures, in reflective plate assemblies according to embodiments described herein, only the reflective disk is coated and the remaining surface of the reflective plate is uncoated. Such selective coating of the reflective disk or a smaller area surrounding the pyrometer increases the reliability of the coating and further reduces manufacturing and replacement costs.

[0017] Figure 11 is a cross-sectional view of an RTP chamber 100 according to at least one embodiment of the present disclosure. The RTP chamber 100 is suitable for thermally processing a substrate W positioned therein. The RTP chamber 100 includes a chamber body

[0018] 102 and a chamber lid 104 disposed on the chamber body 102. The chamber body 102 includes a fluid channel 106 formed therein to flow a temperature control fluid through the fluid channel 106 to cool the chamber body 102 during processing. Cooling of the chamber body 102 reduces the possibility of degradation of the chamber body 102 due to thermal stress during heating of the substrate W. A liner 108 formed of a thermal insulation material such as aluminum nitride is disposed around the inner surface of the chamber body 102 to promote thermal isolation within the chamber body and increase thermal processing efficiency.

[0019] A substrate support 110 is positioned within the chamber body 102. The substrate support 110 may be formed of, for example, sintered aluminum nitride. The substrate support 110 includes a plurality of heating elements 112, such as resistive heating elements embedded therein, to facilitate heating of the substrate W during processing. The heating elements 112 are coupled to a power source 114 via lines disposed through a support shaft 116. The heating elements 112 provide heating of the substrate W via conduction, and may heat the substrate W to a temperature of about 20° C. to about 1000° C., such as from about 25° C. to about 500° C. Additionally, or alternatively, other types of heating, such as radiation from a bulb, may be installed to provide heat to the substrate.

[0020] The support shaft 116 is coupled to the underside of the substrate support 110 and supports the substrate support 110. The support shaft 116 is coupled to an elevator assembly 118 to facilitate positioning the substrate W in a processing position adjacent the chamber lid 104, the elevator assembly 118 including an actuator 120, such as a stepper motor (not shown). The elevator assembly 118 also facilitates removal of the substrate W from the chamber body 102 through an opening 122 (e.g., a slit valve). The elevator assembly 118 is adapted to actuate the substrate support 110 in a vertical direction to allow lift pins 124 to contact a lift plate 126 positioned within the chamber body 102. When the substrate support 110 is lowered, the contact of the lift pins 124 with the lift plate 126 lifts the substrate W from the surface of the substrate support 110. The substrate W is maintained on the lift pins 124 in a position that allows the substrate W to be removed from the chamber body 102 through the opening 122 by a robot (not shown).

[0021] The chamber lid 104 is positioned on the chamber body 102. The chamber lid 104 includes a lid body 128 and a reflective plate 130. The reflective plate 130 has a circular shape and is disposed in a circular opening 132 located in the lid body 128. The reflective plate 130 has an annular lip 134 having a diameter greater than the circular opening 132 to support the reflective plate 130 on the top surface of the lid body 128. The annular lip has a plurality of openings therethrough to accommodate fasteners 136, such as bolts, to secure the reflective plate 130 to the lid body 128. The reflective plate 130 is positioned in and extends through the circular opening 132. A surface 138 of the reflective plate 130 is positioned adjacent to the substrate W. A pyrometer 140 is disposed through the reflective plate 130 to measure the temperature of the substrate W. Typically, one pyrometer 140 is adapted to measure the temperature of a substrate W corresponding to a region of the substrate support 110 in which a respective heating element 112 is located (at Figure 1 Only three pyrometers 140 are depicted in FIG. 1 ). However, it is contemplated that each zone of the substrate support 110 may have more than one corresponding pyrometer 140 for increased temperature monitoring. Each pyrometer 140 is coupled to a controller 142, which is likewise coupled to the power source 114. By controlling the power applied by the power source 114 to each of the heating elements 112, the controller 142 facilitates closed-loop control of each zone of the substrate support 110.

[0022] Figure 2Schematically illustrates an RTP chamber 200 in accordance with at least one embodiment of the present disclosure. The RTP chamber 200 includes a processing region 202 below a transparent quartz window 204. A substrate W to be thermally processed (e.g., a semiconductor substrate such as a silicon wafer) is passed through an inlet and outlet 206 into the processing region 202 of the RTP chamber 200. The periphery of the substrate W is supported by a substrate support, which in this embodiment is shown as an edge ring 208, which may have an annular inclined plate shelf 210 that contacts the corners of the substrate W. The substrate W is oriented so that processing features 212 that have been formed in the front surface of the substrate W face upwardly toward the processing region 202 with reference to the downward gravitational field. The transparent quartz window 204 may be positioned at a distance from the substrate W so that the transparent quartz window 204 has minimal effect on cooling of the substrate during processing. Typically, the distance between the substrate W and the transparent quartz window 204 is in the order of 20 mm. Contrary to the schematic illustration, the features 212 in most cases do not protrude a substantial distance above the surface of the substrate W, but form a pattern in and near the plane of the surface. The lift pins 214 can be raised and lowered to support the back side of the substrate W as the substrate is transferred between a paddle or robotic blade (not shown) bringing the substrate into the RTP chamber 200 and onto the edge ring 208. The radiant heating device 216 is positioned above the transparent quartz window 204 to direct radiant energy toward the substrate W and heat the substrate W. In the RTP chamber 200, the radiant heating device includes a large number (i.e., sufficient to provide uniform radiation to the substrate being heated in the chamber) (e.g., about 409 as an exemplary number) of lamps 218, which are positioned in corresponding reflective tubes 220, which are arranged in a hexagonal close-packed array above the transparent quartz window 204. In some embodiments, the lamps 218 are high-intensity tungsten halogen lamps.

[0023] It is desirable to control the temperature throughout the substrate W to a well-defined temperature that is uniform throughout the substrate W. In this regard, the reflective plate 222 is parallel to the substrate W and extends over an area greater than the substrate W, and faces the back side of the substrate W. The reflective plate 222 reflects thermal radiation emitted from the substrate W back to the substrate W. In some embodiments, the spacing between the substrate W and the reflective plate 222 is about 3 mm to about 9 mm, and the width-to-thickness ratio of the cavity width to thickness is greater than about 20. The reflective plate 222 can be supported on a water-cooled base 224 made of metal to dissipate excess radiation from the substrate W, especially during cooling. The processing area 202 of the processing chamber has at least two substantially parallel walls, wherein the first wall is a transparent quartz window 204, made of a material that is transparent to radiation, such as quartz, and the second wall is substantially parallel to the first wall, the second wall is made of metal and is significantly opaque. In some embodiments, the second wall is the reflective plate 222. The edge ring 208 is supported on a rotatable cylinder 226 that is magnetically coupled to a rotatable flange 228 that is positioned outside the chamber. A motor (not shown) rotates the rotatable flange 228 and thereby the substrate W about its central axis 230, which is also the centerline of the substantially symmetrical chamber.

[0024] The lamps 218 are divided into generally annular zones arranged about a central axis 230. The control circuit varies the voltage delivered to the lamps 218 in different zones to modify the radial distribution of the radiant energy. Dynamic control of the zone heating may be induced by one or more of a plurality of pyrometers 232 coupled through one or more optical light pipes 234 positioned to face the back side of the substrate W and through holes in the reflective plate 222 to measure the temperature across the radius of the rotating substrate W. The pyrometers 232 are disposed through the reflective plate 222.

[0025] The optical light pipe 234 can be formed into various structures including sapphire, metal, and silica optical fibers. A computerized controller 236 receives the output of the pyrometer 232 and controls the voltage supplied to the lamps 218 of the different rings to dynamically control the radiant heating intensity and pattern during processing. The pyrometer 232 typically measures the light intensity in a narrow wavelength bandwidth, such as about 40 nm and in the range of about 700 nm to about 4000 nm, for example. The controller 236 or other instrument converts the light intensity into temperature through the Planck distribution of the spectral distribution of the light intensity radiated by a black body maintained at its temperature.

[0026] The array of lamps 218 is sometimes referred to as a lamp head. However, other radiant heating devices may be substituted. Typically, these involve resistive heating to rapidly raise the temperature of the radiation source. Examples of suitable lamps include mercury lamps having an outer shell of glass or silica surrounding a filament, and flash lamps comprising an outer shell of glass or silica surrounding a gas, such as xenon, which provides a heat source when the gas is energized. As used herein, the term lamp is intended to encompass a lamp that includes an outer shell surrounding a heat source. The "heat source" of a lamp refers to a material or element that can increase the temperature of the substrate, for example, a filament or a gas that can be energized.

[0027] Figure 2 The RTP chamber 200 shown in FIG. 1 enables the edge ring 208 to be floated at different vertical positions within the RTP chamber 200 to allow for control of thermal exposure of the substrate W. It will be appreciated that in FIG. Figure 2 The configurations shown in are not intended to be limiting. For example, the present disclosure is not limited to configurations in which a heat source or lamp is directed toward one side or surface of a substrate and a pyrometer is directed toward an opposite side of the substrate W.

[0028] Some processing chambers manufactured by Applied Materials, Inc. in Santa Clara, California, such as the RTP Centura TM Or RTP Centura XE TM ) can be used with the reflective plate assemblies described herein. Alternatively, RTP chambers from other manufacturers can be used with the reflective plate assemblies described herein.

[0029] Example reflector assembly

[0030] Figure 3A A top view of an example reflective plate assembly 300 is shown in accordance with at least one embodiment of the present disclosure. Figure 3B Showing at least one embodiment of the present disclosure Figure 3A The reflective plate assembly 300 is shown as a cross-sectional view as indicated by "3B". The reflective plate assembly 300 is utilized as a reflective plate of the RTP chamber 100 or the RTP chamber 200 (e.g., in place of a reflective plate). Figure 1 The reflector 130 or Figure 2 In general, the reflector assembly 300 described herein has multiple functions, such as high reflectivity at the pyrometer wavelength, high reflectivity for the wafer radiation spectrum, and reflectivity consistency around the pyrometer in each sub-reflector embedded in the reflector assembly 300. Furthermore, the reflector assembly 300 described herein protects the processing space from contaminants, such as metal, and minimizes cross-talk between pyrometers.

[0031] The reflective plate assembly 300 includes a reflective plate 302. A plurality of reflective disks 304 are embedded within the reflective plate 302. A pyrometer 306 is disposed through an opening of each reflective disk 304. Although three reflective disks 304 are shown, more or fewer reflective disks 304 may be utilized. Similarly, although three pyrometers 306 are shown, more or fewer pyrometers may be utilized. A simple method for cutting away portions of the reflective plate 302 and inserting the reflective disks 304 may be performed to replace the reflective disks 304 for, for example, different substrate processing. For example, holes may be drilled from the surface of the reflective plate 302, and the reflective disks 304 may be inserted into the holes with an O-ring for sealing.

[0032] The reflective plate 302 may be formed of bare aluminum, aluminum alloy, or silver, and the surface of the reflective plate 302 may be mechanically polished to have a reflectivity of about 95% at a wavelength of about 2 μm. Each reflective disk 304 may be formed of aluminum, quartz, or stainless steel.

[0033] The reflective disk 304 may be coated with a coating layer 308. The coating layer 308 may be formed of gold (Au), chromium (Cr), or silver (Ag) and have a thickness between 50 nm and 5 μm. The coating layer 308 may enhance the emissivity of the reflective disk 304 from about 0.85 to about 0.93 at the pyrometer wavelength compared to a reflective disk without a coating layer. The remaining surface of the reflective plate 302 may be a bare polished surface of aluminum without any coating. Compared to conventional reflective plates whose entire surfaces are coated with quartz or other materials, in the reflective plate assembly 300 according to the embodiments described herein, only the reflective disk 304 is coated and the remaining surface of the reflective plate 302 is not coated. Such selective coating of the reflective disk 304 or a smaller area around the pyrometer 306 increases the reliability of the coating and further reduces the manufacturing cost and replacement cost.

[0034] The reflective disk 304 may be further encapsulated by an encapsulation layer 310. The encapsulation layer 310 may be formed of a heat resistant material and / or a non-reactive (inert) material, such as silicon oxide (SiO2) or sapphire, and have a thickness between 50 nm and 1 μm. The encapsulation layer 310 is used to seal the reflective disk 304 from the reflective plate 302, for example, to increase the accuracy of a pyrometer 306 disposed through the reflective disk 304 to measure temperature, and to prevent outgassing of the material that makes up the reflective disk 304.

[0035] Reference Figure 13, each pyrometer 306 is adapted to measure the temperature of a substrate W corresponding to a region of a substrate support 110 having a respective heating element 112 therein. Each pyrometer 306 may be coupled to a controller (e.g., controller 142), which is similarly coupled to a power source (e.g., power source 114). By controlling the power applied by the power source 114 to each of the heating elements 112, the controller 142 facilitates closed-loop control of each region of the substrate support 110.

[0036] Reference Figure 2 3, each pyrometer 306 is adapted to measure the temperature of the substrate W corresponding to the area where the lamp 218 is divided. In these embodiments, each reflective disk 304 may have an opening, and the optical light pipe 234 is installed in the opening. The temperature of each area is adjusted in response to the signal from the plurality of pyrometers 306. Each pyrometer 306 may be coupled to a controller (e.g., controller 236), which is also coupled to a power supply (not shown). The controller 236 receives the output of the pyrometer 232 and controls the voltage supplied to the lamps 218 of different rings to dynamically control the intensity and pattern of radiant heating during processing.

[0037] In some embodiments, the reflective disk 304 is made to further improve reflectivity for the pyrometer wavelength. For example, the reflective disk 304 can be sized to fill only the effective angle for controlling, for example, the adjacent lamp area or the substrate support area. This size (expressed in diameter) can be from about 10 mm to about 30 mm, such as from about 15 mm to about 25 mm.

[0038] Furthermore, since radiation from outside the effective angle is reduced or eliminated by the size of the reflective dish 304 and the ring of low reflectivity around the outer edge of the reflective dish 304, the reflective dish 304 can be small enough to minimize crosstalk between close or adjacent areas.

[0039] The diameter of the reflective plate 302 may generally be about equal to or slightly larger than the diameter of the substrate support 110, such as about 1% or more. Each individual reflective disk 304 may have an area of ​​about 3% or less, such as about 2% or less, such as about 1% or less, for example between about 0.5% and about 3%, such as from about 1% to about 2%, such as from about 1% to about 1.5%, relative to the area of ​​the reflective plate 302. In some embodiments, the total collective area of ​​the reflective disks 304 may be about 15% or less, such as about 10% or less, such as from about 1% to about 10%, such as from about 2% to about 8%, such as from about 4% to about 6% or about 5% to about 10%, relative to the reflective plate 302.

[0040] The reflective plate 302, one or more reflective disks 304, or a combination may have a reflectivity of less than about 2, less than about 1, or less than about 0.3 for radiation having a wavelength below about 700 nm, and a reflectivity of less than about 2, less than about 1, or less than about 0.3 for radiation having a wavelength between 1200 nm and 10 μm. Other degrees of reflection and absorption across the radiation wavelength spectrum may also be utilized, for example, reflectivity for radiation having a wavelength between about 1000 nm and about 1200 nm, between about 1200 nm and about 2100 nm, and between about 2100 nm and about 2400 nm.

[0041] As described herein, a reflective plate includes a plurality of reflective disks having a coating thereon, the reflective disks being positioned within the reflective plate, the reflective plate having a bare mechanically polished surface and no coating thereon. The coating of the reflective disks with gold (Au) or chromium (Au) enhances the emissivity of the reflective disks. The coating on the reflective disks is further encapsulated with silicon oxide (SiO2) or sapphire to reduce metal contamination. The coating on the reflective disks is further encapsulated with silicon oxide (SiO2) or sapphire to reduce metal contamination. Due to the selective coating of the reflective disks or a smaller area around the pyrometer, the reliability of the coating is increased and the manufacturing cost and replacement cost are reduced.

[0042] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, the scope of which is determined by the claims which follow.

Claims

1. A reflector assembly for processing a substrate, comprising: a reflective plate having a first surface, wherein the first surface is a bare polished surface; a reflective disk, embedded in the reflective plate from the first surface; a coating layer on the reflective disk; and A pyrometer is disposed through the opening of the reflective disk. 2 . The reflective plate assembly of claim 1 , wherein the reflective plate comprises aluminum or an aluminum alloy.

3. The reflective plate assembly of claim 1, wherein the reflective disk comprises aluminum, quartz, or stainless steel. The reflection plate assembly of claim 1 , wherein the coating layer comprises gold (Au). The reflective plate assembly of claim 1 , wherein the coating layer comprises chromium (Cr). The reflection plate assembly of claim 1 , wherein the coating layer comprises silver (Ag).

7. The reflective plate assembly according to claim 1, further comprising: An encapsulating layer is on the coating layer.

8. The reflective plate assembly of claim 7, wherein the encapsulation layer comprises silicon oxide (SiO2).

9. The reflective plate assembly of claim 7, wherein the encapsulation layer comprises sapphire.

10. A reflector assembly for processing a substrate, comprising: a reflective plate having a first surface, wherein the first surface is a bare polished surface; a reflective disk, embedded in the reflective plate from the first surface; a coating layer on the reflective disk; a pyrometer disposed through the opening of the reflective disk; and An encapsulating layer is on the coating layer.

11. The reflective plate assembly of claim 10, wherein the reflective plate comprises aluminum.

12. The reflective plate assembly of claim 10, wherein the reflective disk comprises aluminum or quartz.

13. The reflection plate assembly of claim 10, wherein the coating layer comprises gold (Au), chromium (Cr), or silver (Ag).

14. The reflective plate assembly of claim 10, wherein the encapsulation layer comprises silicon oxide (SiO2).

15. The reflective plate assembly of claim 10, wherein the encapsulation layer comprises sapphire.

16. A chamber for processing a substrate, comprising: Chamber body; A chamber cover is disposed on the chamber body, and the chamber cover comprises: Cover body; and A reflector assembly, the reflector assembly comprising: a reflective plate having a first surface, wherein the first surface is a bare polished surface; a plurality of reflective disks embedded in the reflective plate from the first surface; a coating layer on each of the plurality of reflective disks; a plurality of pyrometers, wherein each pyrometer of the plurality of pyrometers is disposed through an opening of a reflective disk of the plurality of reflective disks; and An encapsulating layer is on the coating layer.

17. The chamber of claim 16, further comprising a plurality of zones into which the plurality of lamps are divided, wherein each pyrometer of the plurality of pyrometers corresponds to each zone of the plurality of zones.

18. The chamber of claim 17, further comprising a controller configured to receive outputs from the plurality of pyrometers and control a voltage supplied to the plurality of lamps.

19. The chamber of claim 16, further comprising a substrate support comprising a plurality of zones to heat a substrate positioned on the substrate support, wherein each pyrometer of the plurality of pyrometers corresponds to each zone of the plurality of zones.

20. The chamber of claim 19, further comprising a plurality of resistive heating elements, wherein one resistive heating element is disposed in each zone and the plurality of resistive heating elements are controlled by the pyrometer in each zone.

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