Reflector plate for substrate processing

Abstract

A reflector plate assembly for processing a substrate includes a reflector plate having a first surface, the first surface being a bare polished surface; a reflector disk embedded within the reflector plate from the first surface; a coating layer on the reflector disk; and a pyrometer disposed through an opening in the reflector disk.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to apparatus for processing substrates, and more particularly to reflector plates for rapid thermal processing. [Background technology]

[0002] Rapid thermal processing (RTP) is a process for annealing substrates during semiconductor manufacturing. During this process, thermal radiation is used to rapidly heat wafers in a controlled environment above room temperature to a maximum temperature of over 900°C. Reflector plates used in RTP processing of substrates utilize pyrometers for wafer temperature measurement. State-of-the-art reflector plates are fabricated to maximize 100% reflectivity at pyrometer wavelengths (e.g., 700 nm to approximately 4000 nm), yet only 10% or less of the reflector plate's area is used for pyrometers. This mismatch unnecessarily increases costs. Furthermore, for purposes such as energy conservation and improved wafer heating performance, the reflector plate should reflect radiation at all pyrometer wavelengths across the entire wafer surface. However, achieving both energy savings and improved heating performance in a single, uniform reflector plate is costly because such a reflector plate requires a complex, multi-layer coating optical stack across the entire reflector plate, which can easily crack or delaminate at elevated temperatures.

[0003] There is a need for new and improved reflector plates for substrate processing. Summary of the Invention

[0004] An embodiment of the present disclosure provides a reflector plate assembly for processing a substrate, the reflector plate assembly including a reflector plate having a first surface, the first surface being a bare polished surface, a reflector disk embedded within the reflector plate from the first surface, a coating layer on the reflector disk, and a pyrometer disposed through an opening in the reflector disk.

[0005] An embodiment of the present disclosure provides a reflector plate assembly for processing a substrate, the reflector plate assembly including: a reflector plate having a first surface, the first surface being a bare polished surface; a reflector disk embedded within the reflector plate from the first surface; a coating layer on the reflector disk; a pyrometer disposed through an opening in the reflector disk; and an encapsulation layer on the coating layer.

[0006] An embodiment of the present disclosure provides a chamber for processing a substrate, the chamber including a chamber body and a chamber lid disposed on the chamber body, the chamber lid including a lid body and a reflector plate assembly. The reflector plate assembly includes a reflector plate having a first surface, the first surface being a bare polished surface, a plurality of reflector disks embedded in the reflector plate from the first surface, a coating layer on each of the plurality of reflector disks, a plurality of pyrometers disposed through an opening in a reflector disk of the plurality of reflector disks, and an encapsulation layer on the coating layer.

[0007] In order that the above-listed features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and are therefore not to be construed as limiting the scope of the present disclosure, and other embodiments having equivalent effect may also be recognized. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an exemplary RTP chamber in accordance with at least one embodiment of the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view of an exemplary RTP chamber in accordance with at least one embodiment of the present disclosure. [Figure 3A] FIG. 2 is a top view of an exemplary reflector plate assembly in accordance with at least one embodiment of the present disclosure. [Figure 3B] FIG. 3B is a cross-sectional view of the exemplary reflector plate assembly shown in FIG. 3A in accordance with at least one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] For ease of 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.

[0010] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to apparatus for processing substrates, and more particularly to reflector plates for rapid thermal processing.

[0011] A reflector plate assembly according to embodiments described herein includes a plurality of reflector disks having a coating thereon positioned within a reflector plate having a bare, mechanically polished surface with no coating thereon. The reflector disks are coated with gold (Au) or chromium (Cr) to improve the emissivity of the reflector disks. The coatings on the reflector disks are further encapsulated with silicon oxide (SiO2) or sapphire to reduce metal contamination.

[0012] Compared to conventional reflector plates, in which the entire surface is coated with quartz or other materials that can crack or peel when the temperature increases, in reflector plate assemblies according to embodiments described herein, only the reflector disk is coated, and the remaining surface of the reflector plate is not coated. Such selective coating of smaller areas around the reflector disk or pyrometer increases the reliability of the coating and also reduces manufacturing and replacement costs.

[0013] FIG. 1 is a cross-sectional view of an RTP chamber 100 in accordance with at least one embodiment of the present disclosure. The RTP chamber 100 is adapted to thermally process a substrate W positioned therein. The RTP chamber 100 includes a chamber body 102 and a chamber lid 104 disposed thereon. The chamber body 102 includes a fluid passage 106 formed therein for flowing a temperature-control fluid therethrough to cool the chamber body 102 during processing. Cooling the chamber body 102 reduces the likelihood of degradation of the chamber body 102 due to thermal stress during heating of the substrate W. A liner 108 formed from a thermal insulating material, such as aluminum nitride, is disposed around the inner surface of the chamber body 102 to facilitate heat containment within the chamber body and increase thermal processing efficiency.

[0014] A substrate support 110 is positioned within the chamber body 102. The substrate support 110 can be formed, for example, from 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 by wires disposed through a support shaft 116. The heating elements 112 provide heating of the substrate W by conduction and can heat the substrate W to a temperature of about 20°C to about 1000°C, such as about 25°C to about 500°C. Additionally or alternatively, other types of heating, such as radiation from a lamp bulb, can be provided to provide heat to the substrate.

[0015] A support shaft 116 is coupled to an underside of the substrate support 110 and supports the substrate support 110. The support shaft 116 is coupled to a lifter assembly 118, which includes an actuator 120, such as a stepper motor (not shown), to facilitate positioning the substrate W at a processing position adjacent the chamber lid 104. The lifter assembly 118 also facilitates removal of the substrate W from the chamber body 102 through an opening 122 (e.g., a slit valve). The lifter assembly 118 is adapted to vertically actuate the substrate support 110 to allow lift pins 124 to contact a lift plate 126 positioned within the chamber body 102. When the lift pins 124 contact the lift plate 126, the substrate W is lifted from the surface of the substrate support 110 as the substrate support 110 is lowered. The substrate W is maintained on the lift pins 124 in a position that allows removal of the substrate W from the chamber body 102 through the opening 122 by a robot (not shown).

[0016] The chamber lid 104 is positioned on the chamber body 102. The chamber lid 104 includes a lid body 128 and a reflector plate 130. The reflector plate 130 is circular and disposed within a circular opening 132 located within the lid body 128. The reflector plate 130 has an annular lip 134 whose diameter is larger than the circular opening 132 for supporting the reflector plate 130 on the upper surface of the lid body 128. The annular lip has a plurality of openings therethrough to accommodate fasteners 136, such as bolts, for securing the reflector plate 130 to the lid body 128. The reflector plate 130 is positioned within and extends through the circular opening 132. A surface 138 of the reflector plate 130 is positioned adjacent to the substrate W. A pyrometer 140 is disposed through the reflector plate 130 to measure the temperature of the substrate W. Generally, one pyrometer 140 is adapted to measure the temperature of the substrate W corresponding to a zone of the substrate support 110 having an individual heating element 112 therein (only three pyrometers 140 are shown in FIG. 1 ). However, it is contemplated that each zone of the substrate support 110 may have multiple corresponding pyrometers 140 to monitor the rise in temperature. Each pyrometer 140 is coupled to a controller 142, which in turn is coupled to the power supply 114. The controller 142 facilitates closed-loop control of each zone of the substrate support 110 by controlling the power applied by the power supply 114 to each of the heating elements 112.

[0017] FIG. 2 schematically illustrates an RTP chamber 200 according to at least one embodiment of the present disclosure. The RTP chamber 200 includes a processing portion 202 below a transparent quartz window 204. A substrate W, e.g., a semiconductor substrate such as a silicon wafer to be thermally processed, enters the processing portion 202 of the RTP chamber 200 through an access port 206. The substrate W is supported at its periphery by a substrate support, shown in this embodiment as an edge ring 208, which may have an annular sloped shelf 210 that contacts the corners of the substrate W. The substrate W is oriented relative to a downward gravitational field so that pre-processed features 212 formed on the front surface of the substrate W face upward, toward the processing portion 202. The transparent quartz window 204 may be positioned a short distance from the substrate W to minimize its effect on cooling of the substrate during processing. Typically, the distance between the substrate W and the transparent quartz window 204 is about 20 mm. Unlike the schematic illustration, most of the features 212 do not protrude significantly beyond the surface of the substrate W, constituting patterning in and near the plane of the surface. Lift pins 214 can be raised and lowered to support the backside of the substrate W as it is transferred between paddles or robot blades (not shown) to bring it onto the edge ring 208 within the RTP chamber 200. A radiant heating device 216 is positioned above the transparent quartz window 204 to direct radiant energy toward and heat the substrate W. In the RTP chamber 200, the radiant heating device includes multiple lamps 218 positioned in respective reflector tubes 220 arranged in a hexagonal close-packed array above the transparent quartz window 204, i.e., a sufficient number of lamps 218 (e.g., about 409 is an exemplary number) to provide uniform radiation to a substrate being heated in the chamber. In some embodiments, the lamps 218 are high-intensity tungsten-halogen lamps.

[0018] It is desirable to control the temperature across the substrate W to a precisely defined temperature so that it is uniform across the substrate W. In this regard, a reflector plate 222 extends parallel to and over an area larger than the substrate W and faces the backside of the substrate W. The reflector plate 222 reflects thermal radiation emitted from the substrate W back toward the substrate W. In some embodiments, the spacing between the substrate W and the reflector plate 222 is about 3 mm to about 9 mm, and the aspect ratio of the width to the thickness of the cavity is greater than about 20. The reflector plate 222 may be supported on a metallic, water-cooled base 224 for heat sinking excess radiation from the substrate W, particularly during cool-down. The processing portion 202 of the processing chamber has at least two substantially parallel walls, of which a first wall is a transparent quartz window 204 made of a material transparent to the radiation, such as quartz, and a second wall substantially parallel to the first wall is made of metal and is substantially opaque. In some embodiments, the second wall is the reflector plate 222. The edge ring 208 is supported on a rotatable cylinder 226 that is magnetically coupled to a rotatable flange 228 positioned outside the chamber. A rotor (not shown) rotates the rotatable flange 228, thereby rotating the substrate W about its central axis 230, which is also the centerline of the chamber of symmetry.

[0019] The lamps 218 are divided into zones arranged approximately annularly around a central axis 230. A control circuit varies the voltage supplied to the lamps 218 in different zones to match the radial distribution of radiant energy. Dynamic control of the zoned heating can be effected by one or more of a plurality of pyrometers 232 coupled through one or more optical light pipes 234 positioned facing the backside of the substrate W through apertures in the reflector plate 222 to measure the temperature over the radial range of the rotating substrate W. The pyrometers 232 are disposed through the reflector plate 222.

[0020] The optical light pipe 234 can be formed from a variety of structures, including sapphire, metal, and silica fiber. A computerized controller 236 receives the output of the pyrometer 232 and controls the voltage supplied to the different rings of the lamp 218 to dynamically control the intensity and pattern of radiant heating during processing. The pyrometer 232 typically measures light intensity over a narrow wavelength bandwidth, e.g., about 40 nm, ranging from about 700 nm to about 4000 nm. The controller 236 or other instrumentation converts the light intensity to temperature via the Planckian distribution of the spectral distribution of light intensity radiating from a blackbody held at that temperature.

[0021] The array of lamps 218 is sometimes referred to as a lamphead. However, other radiant heating devices may be substituted. These generally involve resistive heating to rapidly increase the temperature of the radiant source. Examples of suitable lamps include mercury lamps, which have a glass or silica envelope surrounding a filament, and flash lamps, which comprise a glass or silica envelope surrounding a gas, such as xenon, that provides a heat source when excited. As used herein, the term lamp is intended to include lamps that include an envelope surrounding a heat source. The "heat source" of a lamp refers to a material or element capable of raising the temperature of a substrate, for example, an energizable filament or an excitable gas.

[0022] 2 may allow the edge ring 208 to be levitated at different vertical positions within the RTP chamber 200 to control the thermal exposure of the substrate W. It should be understood that the configuration shown in FIG. 2 is 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 the substrate W and a pyrometer is directed toward the opposite side of the substrate W.

[0023] Certain processing chambers, such as the RTP Centura® or RTP Centura XE® manufactured by Applied Materials, Inc. of Santa Clara, Calif., can be used with the reflector plate assemblies described herein. Alternatively, RTP chambers from other manufacturers can be used with the reflector plate assemblies described herein.

[0024] Exemplary Reflector Plate Assembly FIG. 3A illustrates a top view of an exemplary reflector plate assembly 300 according to at least one embodiment of the present disclosure. FIG. 3B illustrates a cross-sectional view of the reflector plate assembly 300 shown in FIG. 3A, as indicated by “3B,” according to at least one embodiment of the present disclosure. The reflector plate assembly 300 is utilized as a reflector plate (e.g., in place of reflector plate 130 of FIG. 1 or reflector plate 222 of FIG. 2) in conjunction with the RTP chamber 100 or RTP chamber 200. In general, the reflector plate assembly 300 described herein has multiple functions, such as high reflectivity at the pyrometer wavelength, high reflectivity for the wafer radiation spectrum, and consistent reflectivity around the pyrometers embedded in each sub-reflector plate of the reflector plate assembly 300. Additionally, the reflector plate assembly 300 described herein protects the process space from contaminants, e.g., metals, and minimizes crosstalk between pyrometers.

[0025] The reflector plate assembly 300 includes a reflector plate 302. A plurality of reflector disks 304 are embedded within the reflector plate 302. A pyrometer 306 is disposed through an opening in each reflector disk 304. Although three reflector disks 304 are shown, more or fewer reflector disks 304 can be utilized. Similarly, although three pyrometers 306 are shown, more or fewer pyrometers can be utilized. A simple method for cutting out a portion of the reflector plate 302 and inserting a reflector disk 304 is feasible, for example, to replace a reflector disk 304 in a different substrate process. For example, a hole can be drilled from the surface of the reflector plate 302, and the reflector disk 304 can be inserted into the hole along with an O-ring for sealing.

[0026] The reflector plate 302 may be formed of bare aluminum, an aluminum alloy, or silver, and the surface of the reflector plate 302 may be mechanically polished to have a reflectivity of about 95% at a wavelength of about 2 μm. Each reflector disk 304 may be formed of aluminum, quartz, or stainless steel.

[0027] The reflector 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 of 50 nm to 5 μm. The coating layer 308 may increase the emissivity of the reflector disk 304 from about 0.85 to about 0.93 at the pyrometer wavelength, compared to a reflector disk without a coating layer. The remaining surface of the reflector plate 302 may be a bare, polished aluminum surface without any coating. Compared to conventional reflector plates in which the entire surface is coated with quartz or other materials, in the reflector plate assembly 300 according to the embodiments described herein, only the reflector disk 304 is coated, and the remaining surface of the reflector plate 302 is not coated. Such selective coating of smaller areas around the reflector disk 304 or pyrometer 306 increases the reliability of the coating and further reduces manufacturing and replacement costs.

[0028] The reflector disk 304 may be further encapsulated by an encapsulation layer 310. The encapsulation layer 310 may be formed of a heat-resistant and / or non-reactive (inert) material, such as silicon oxide (SiO2) or sapphire, and has a thickness of 50 nm to 1 μm. The encapsulation layer 310 is used, for example, to seal the reflector disk 304 from the reflector plate 302 to improve the accuracy of a pyrometer 306 disposed through the reflector disk 304 to measure temperature and to prevent outgassing of the material comprising the reflector disk 304.

[0029] 1 and the reflector plate assembly 300 of FIG. 3, each pyrometer 306 is adapted to measure the temperature of the substrate W corresponding to a zone of the substrate support 110 having an individual heating element 112 therein. Each pyrometer 306 is coupled to a controller (e.g., controller 142), which in turn is coupled to a power source (e.g., power source 114). The controller 142 facilitates closed-loop control of each zone of the substrate support 110 by controlling the power applied by the power source 114 to each of the heating elements 112.

[0030] Referring to the RTP chamber 200 of FIG. 2 and the reflector plate assembly 300 of FIG. 3, each pyrometer 306 is adapted to measure the temperature of the substrate W corresponding to a zone into which the lamps 218 are divided. In these embodiments, each reflector disk 304 can have an opening into which an optical light pipe 234 is attached. The temperature of each zone is adjusted in response to signals from the multiple pyrometers 306. Each pyrometer 306 is coupled to a controller (e.g., controller 236), which is in turn coupled to a power supply (not shown). The controller 236 receives the output of the pyrometers 232 and controls the voltage supplied to different rings of lamps 218 to dynamically control the intensity and pattern of radiant heating during processing.

[0031] In some embodiments, the reflector disk 304 is fabricated to further improve reflectivity at pyrometer wavelengths. For example, the reflector disk 304 can be sized to fill only the effective angle used to control, for example, adjacent lamp zones or substrate support zones. Such a size (diameter) can be from about 10 mm to about 30 mm, e.g., from about 15 mm to about 25 mm.

[0032] Additionally, the reflector disk 304 can be made small enough to minimize crosstalk between nearby or adjacent zones because the size of the reflector disk 304 and the low reflectivity ring around the outer edge of the reflector disk 304 reduce or eliminate radiation outside the useful angle.

[0033] The reflector plate 302 can generally have a diameter about equal to or slightly larger than the diameter of the substrate support 110, such as by about 1% or more. Each individual reflector disk 304 can have an area of ​​about 0.5% to about 3%, such as about 2% or less, about 1% or less, about 3% or less, e.g., about 1% to about 2%, about 1% to about 1.5%, relative to the area of ​​the reflector plate 302. In some embodiments, the combined area of ​​the reflector disks 304 can be about 15% or less, e.g., about 10% or less, about 1% to about 10%, about 2% to about 8%, about 4% to about 6%, or about 5% to about 10% relative to the area of ​​the reflector plate 302.

[0034] The reflector plate 302, one or more reflector disks 304, or a combination thereof, can have a reflectivity of less than about 2, less than about 1, or less than about 0.3 for radiation having wavelengths below about 700 nm, and less than about 2, less than about 1, or less than about 0.3 for radiation having wavelengths between 1200 nm and 10 μm. Other reflection and absorption levels across the spectrum of radiation wavelengths may also be utilized, for example, reflectivity for radiation having wavelengths 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.

[0035] As described herein, the reflector plate includes a plurality of reflector disks having a coating thereon positioned within a reflector plate having a bare, mechanically polished surface with no coating thereon. Coating the reflector disks with gold (Au) or chromium (Cr) increases the emissivity of the reflector disks. The coating on the reflector disks is further encapsulated with silicon oxide (SiO2) or sapphire to reduce metal contamination. The coating on the reflector disks is further encapsulated with silicon oxide (SiO2) or sapphire to reduce metal contamination. Selective coating of smaller areas around the reflector disk or pyrometer increases the reliability of the coating and reduces manufacturing and replacement costs.

[0036] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the following claims.

Claims

1. 1. A reflector plate assembly for processing a substrate, comprising: a reflector plate having a first surface, the first surface being a bare polished surface; a reflector disk embedded within the reflector plate from the first surface; a coating layer on the reflector disc; a pyrometer disposed through an opening in the reflector disk; and A reflector plate assembly comprising:

2. The reflector plate assembly of claim 1 , wherein the reflector plate comprises aluminum or an aluminum alloy.

3. The reflector plate assembly of claim 1 , wherein the reflector disk comprises aluminum, quartz, or stainless steel.

4. 10. The reflector plate assembly of claim 1, wherein the coating layer comprises gold (Au).

5. 10. The reflector plate assembly of claim 1, wherein the coating layer comprises chromium (Cr).

6. 10. The reflector plate assembly of claim 1, wherein the coating layer comprises silver (Ag).

7. The reflector plate assembly of claim 1 , further comprising an encapsulation layer on the cover layer.

8. The encapsulation layer is silicon oxide (SiO ２ 8. The reflector plate assembly of claim 7, comprising:

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

10. 1. A reflector plate assembly for processing a substrate, comprising: a reflector plate having a first surface, the first surface being a bare polished surface; a reflector disk embedded within the reflector plate from the first surface; a coating layer on the reflector disc; a pyrometer disposed through an opening in the reflector disk; an encapsulation layer on the coating layer; A reflector plate assembly comprising:

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

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

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

14. The encapsulation layer is silicon oxide (SiO ２ 11. The reflector plate assembly of claim 10, comprising:

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

16. 1. A chamber for processing a substrate, comprising: a chamber body; a chamber lid disposed on the chamber body, the chamber lid comprising: The lid body, and a reflector plate assembly, the reflector plate assembly comprising: a reflector plate having a first surface, the first surface being a bare polished surface; a plurality of reflector disks embedded within the reflector plate from the first surface; a coating layer on each of the plurality of reflector discs; a plurality of pyrometers, each pyrometer of the plurality of pyrometers disposed through an opening in a reflector disk of the plurality of reflector disks; an encapsulation layer on the coating layer; a chamber including:

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

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

19. 17. The chamber of claim 16, further comprising a substrate support, the substrate support including a plurality of zones for heating a substrate positioned on the substrate support, each pyrometer of the plurality of pyrometers corresponding to a respective zone of the plurality of zones.

20. 20. The chamber of claim 19, further comprising a plurality of resistive heating elements disposed within each zone, the plurality of resistive heating elements being controlled by the pyrometer in each zone.

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