Susceptor for semiconductor substrate processing

Abstract

A susceptor for semiconductor substrate processing is disclosed herein. In some embodiments, the susceptor can include an inner susceptor portion and an outer susceptor portion. The susceptor portions can be self-aligned via complementary features, such as tabs on the outer susceptor and recesses on the inner susceptor portion. The inner susceptor portion can include a number of contact pads with which a wafer is supported during semiconductor processing. In some embodiments, the contact pads are hemispherical to reduce the contact area with the wafer, thereby reducing the risk of backside damage. The inner susceptor portion can include a cavity for receiving a thermocouple. In some embodiments, the cavity has a diameter that is greater than the diameter of the thermocouple, such that the thermocouple does not contact the walls of the cavity during processing, thereby providing highly accurate temperature measurements.

Description

[0001] Cross Reference to Related Applications

[0002] Any and all applications identified in the Application Data Sheet as having a foreign or domestic priority filing date, including any priority document, are hereby incorporated by reference in their entirety under 37 CFR 1.57. This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 925,705, filed October 24, 2019, and entitled “SUSCEPTOR FOR SEMICONDUCTOR SUBSTRATE PROCESSING,” which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates generally to semiconductor processing, and more specifically, to susceptors for supporting semiconductor substrates in a processing chamber. BACKGROUND

[0004] Semiconductor substrates, such as semiconductor wafers, are often processed within a processing chamber under controlled processing conditions that include exposure to high temperatures. A base, often referred to as a “susceptor,” is often used to support the substrate during processing in the processing chamber (e.g., during deposition). To facilitate automated processing, a robotic arm can be used to place the substrate on the susceptor and subsequently remove it from the reactor after processing.

[0005] During processing, a number of quality control issues can arise related to the physical interaction between the substrate and the susceptor, and there is a continuing need to address these quality control issues. SUMMARY

[0006] Various examples of susceptors for supporting semiconductor substrates, and related processing systems and methods, are disclosed.

[0007] In some embodiments, an apparatus for processing a substrate is provided, the apparatus comprising: a processing chamber configured to house a substrate; and a susceptor disposed in the processing chamber and configured to support the substrate. The susceptor comprises an inner susceptor portion and an outer susceptor portion that surrounds the inner susceptor portion. The inner susceptor portion includes a plurality of recesses, and the outer susceptor portion includes a plurality of protrusions that extend below the inner susceptor portion to support the inner susceptor portion. Each of the protrusions has a generally triangular shape and is aligned within a corresponding one of the recesses. The triangular shape of the protrusions has a vertex that protrudes toward a center of the inner susceptor portion.

[0008] In some other embodiments, a pedestal for supporting a substrate is provided. The pedestal includes an inner pedestal portion including a plurality of recesses and an outer pedestal portion surrounding the inner pedestal portion. The outer pedestal portion includes a plurality of protrusions extending below the inner pedestal portion to support the inner pedestal portion. Each of the protrusions has a generally triangular shape and is aligned within a corresponding one of the recesses, with a vertex of the triangular shape of the protrusion projecting toward a center of the outer pedestal portion.

[0009] In yet some embodiments, an apparatus for processing a substrate is provided. The apparatus includes a processing chamber configured to house a substrate and a pedestal disposed in the processing chamber and configured to support the substrate. The pedestal includes an inner pedestal portion and an outer pedestal portion surrounding the inner pedestal portion. The inner pedestal portion includes a plurality of contact pads extending outwardly from a periphery of a surface of the inner pedestal portion and disposed proximate the periphery, the pads configured to support the substrate and prevent the substrate from contacting the surface during processing.

[0010] In yet some embodiments, a pedestal for supporting a substrate is provided. The pedestal includes an inner pedestal portion including a plurality of contact pads extending outwardly from a periphery of a surface of the inner pedestal portion and disposed proximate the periphery. The pads are configured to support the substrate and prevent the substrate from contacting the surface during processing. The pedestal further includes an outer pedestal portion surrounding the inner pedestal portion.

[0011] In yet some embodiments, an apparatus for processing a substrate is provided. The apparatus includes a processing chamber configured to house a substrate, a pedestal disposed in the processing chamber and configured to support the substrate, and a thermocouple configured to measure a temperature of the pedestal. The pedestal includes an inner pedestal portion and an outer pedestal portion surrounding the inner pedestal portion. The inner pedestal portion includes a cavity defining a volume for housing the thermocouple, the cavity formed through an underside of a middle portion of the inner pedestal portion. A width of the cavity is greater than a width of the thermocouple, and the thermocouple is spaced apart from a wall of the cavity by an air gap.

[0012] In yet some embodiments, a method for processing a substrate is provided. The method includes providing the substrate on a pedestal in a processing chamber. The pedestal includes an inner pedestal portion and an outer pedestal portion surrounding the inner pedestal portion. The inner pedestal portion includes a cavity defining a volume for housing a thermocouple, the cavity formed through an underside of a middle portion of the inner pedestal portion. The method further includes providing the thermocouple in the cavity. The thermocouple is spaced apart from a wall of the cavity by an air gap. The method further includes processing the substrate on the pedestal in the processing chamber. Processing the substrate includes heating the substrate and the pedestal, and maintaining the air gap during processing of the substrate.

[0013] Additional examples of embodiments are listed below.

[0014] Example 1. An apparatus for processing a substrate, the apparatus comprising:

[0015] a processing chamber configured to house a substrate; and

[0016] a susceptor disposed in the processing chamber and configured to support the substrate,

[0017] wherein the susceptor comprises an inner susceptor portion and an outer susceptor portion that surrounds the inner susceptor portion,

[0018] wherein the inner susceptor portion includes a plurality of recesses and the outer susceptor portion includes a plurality of protrusions that extend below the inner susceptor portion to support the inner susceptor portion,

[0019] wherein each of the protrusions has a generally triangular shape and is aligned within a corresponding one of the recesses, wherein an apex of the triangular shape of the protrusion protrudes toward a center of the inner susceptor portion.

[0020] Example 2. The apparatus of Example 1, wherein the inner susceptor portion is smaller than the substrate and the outer susceptor portion extends beyond the substrate.

[0021] Example 3. The apparatus of Example 1, wherein the inner susceptor portion has a shape in which a first disc and a second disc are concentrically overlapped with each other, a diameter of the first disc being smaller than a diameter of the second disc.

[0022] Example 4. The apparatus of Example 1, wherein the outer susceptor portion includes a plurality of concentric annular top surfaces, each of the annular top surfaces being disposed on a different vertical plane.

[0023] Example 5. The apparatus of Example 1, wherein each protrusion has a radial groove on an underside of the protrusion.

[0024] Example 6. The apparatus of Example 1, wherein edges of the protrusions are chamfered.

[0025] Example 7. The apparatus of Example 6, wherein the edges of the protrusions have a chamfer in a range of 60° to 80°.

[0026] Example 8. The apparatus of Example 1, wherein the inner susceptor has a concave shape corresponding to a concave surface of the substrate during processing of the substrate, wherein the concave shape has a depth in a range of 0.1 mm to 1 mm.

[0027] Example 9. The apparatus of Example 1, wherein the inner base portion includes a plurality of contact pads along a perimeter of the inner base portion, the pads protruding from a surface of the inner base portion to support the substrate and prevent the substrate from contacting the surface.

[0028] Example 10. The apparatus of Example 9, wherein the contact pads have a hemispherical shape.

[0029] Example 11. The apparatus of Example 9, wherein the pads have a height in a range of about 0.15 mm to 1 mm.

[0030] Example 12. A base for supporting a substrate, the base comprising:

[0031] an inner base portion, wherein the inner base portion includes a plurality of recesses; and an outer base portion that surrounds the inner base portion,

[0032] wherein the outer base portion includes a plurality of protrusions that extend below the inner base portion to support the inner base portion,

[0033] wherein each of the protrusions has a generally triangular shape and is aligned within a corresponding one of the recesses, wherein a vertex of the triangular shape of the protrusion protrudes toward a center of the outer base portion.

[0034] Example 13. The apparatus of Example 12, wherein the inner base portion is smaller than the substrate, and the outer base portion extends beyond the substrate.

[0035] Example 14. The apparatus of Example 12, wherein the inner base portion has a shape in which a first disc and a second disc are concentrically overlapped with each other, a diameter of the first disc being smaller than a diameter of the second disc.

[0036] Example 15. The apparatus of Example 12, wherein the outer base portion includes a plurality of concentric ring-shaped top surfaces, each of the ring-shaped top surfaces being disposed at a different vertical plane.

[0037] Example 16. The apparatus of Example 12, wherein the at least one protrusion has a groove on an underside, the groove being a generally triangular shape with a vertex facing outward in a radial direction from the center of the outer base portion.

[0038] Example 17. The apparatus of Example 12, wherein edges of the protrusions are chamfered.

[0039] Example 18. The apparatus of Example 17, wherein the edges of the protrusions have a chamfer in a range of 60° to 80°.

[0040] Example 19. The apparatus of Example 12, wherein the inner susceptor has a concave shape corresponding to a concave surface of the substrate during processing of the substrate, wherein the concave shape has a depth in a range of 0.1 mm to 1 mm.

[0041] Example 20. The apparatus of Example 12, wherein the inner susceptor portion includes a plurality of contact pads along a perimeter of the inner susceptor portion, the pads protruding from a surface of the inner susceptor portion to support the substrate and prevent the substrate from contacting the surface.

[0042] Example 21. An apparatus for processing a substrate, the apparatus comprising:

[0043] a processing chamber configured to house a substrate; and

[0044] a susceptor disposed in the processing chamber and configured to support the substrate,

[0045] wherein the susceptor includes an inner susceptor portion and an outer susceptor portion surrounding the inner susceptor portion,

[0046] wherein the inner susceptor portion includes a plurality of contact pads extending outwardly from a perimeter of a surface of the inner susceptor portion and disposed along the perimeter, the pads supporting the substrate and preventing the substrate from contacting the surface during processing.

[0047] Example 22. The apparatus of Example 21, wherein the pads are integrally formed with the inner susceptor portion.

[0048] Example 23. The apparatus of Example 22, wherein the pads have a hemispherical shape.

[0049] Example 24. The apparatus of Example 22, wherein the pads have a height in a range of about 0.15 mm to 1 mm.

[0050] Example 25. The apparatus of Example 22, wherein the pads have a diameter in a range of about 0.75 mm to 1.5 mm.

[0051] Example 26. The apparatus of Example 21, wherein the inner susceptor portion has a concave shape corresponding to a concave surface of the substrate during processing of the substrate, wherein the concave shape has a depth in a range of 0.1 mm to 1 mm.

[0052] Example 27. The apparatus of Example 21, wherein the inner susceptor portion includes a plurality of center contact pads located near a center of the inner susceptor portion.

[0053] Example 28. The apparatus of Example 27, wherein the center contact pad has a hemi-spherical shape.

[0054] Example 29. The apparatus of Example 27, wherein the center contact pad has a height in a range of about 0.05 mm to 1 mm.

[0055] Example 30. A pedestal for supporting a substrate, the pedestal comprising:

[0056] an inner pedestal portion, wherein the inner pedestal portion comprises:

[0057] a plurality of contact pads extending outwardly from and disposed proximate a periphery of a surface of the inner pedestal portion,

[0058] wherein the pads are configured to support the substrate and prevent the substrate from contacting the surface during processing; and

[0059] an outer pedestal portion surrounding the inner pedestal portion.

[0060] Example 31. The apparatus of Example 30, wherein the pads are integrally formed with the inner pedestal portion.

[0061] Example 32. The apparatus of Example 31, wherein the pads have a hemi-spherical shape.

[0062] Example 33. The apparatus of Example 31, wherein the pads have a height in a range of about 0.15 mm to 1 mm.

[0063] Example 34. The apparatus of Example 31, wherein the pads have a diameter in a range of about 0.75 mm to 1.5 mm.

[0064] Example 35. The apparatus of Example 31, wherein the inner pedestal portion has a concave shape corresponding to a concave surface of the substrate during processing of the substrate, wherein the concave shape has a depth in a range of 0.23 mm to 0.47 mm.

[0065] Example 36. The apparatus of Example 30, wherein the inner pedestal portion includes a plurality of center contact pads located proximate a center of the inner pedestal portion.

[0066] Example 37. The apparatus of Example 36, wherein the center contact pads have a hemi-spherical shape.

[0067] Example 38. The apparatus of Example 36, wherein the center contact pads have a height in a range of about 0.05 mm to 1 mm.

[0068] Example 39. An apparatus for processing a substrate, the apparatus comprising:

[0069] a processing chamber configured to house a substrate;

[0070] a pedestal disposed in the processing chamber and configured to support the substrate; and

[0071] a thermocouple configured to measure a temperature of the pedestal,

[0072] wherein the pedestal comprises an inner pedestal portion and an outer pedestal portion surrounding the inner pedestal portion,

[0073] wherein the inner pedestal portion includes a cavity defining a volume for housing the thermocouple, the cavity being formed through a lower side of a middle portion of the inner pedestal portion,

[0074] wherein a width of the cavity is greater than a width of the thermocouple, wherein the thermocouple is spaced apart from a wall of the cavity by an air gap.

[0075] Example 40. The apparatus of Example 39, wherein a tip of the thermocouple is in contact with an upper end of the cavity.

[0076] Example 41. The apparatus of Example 39, wherein a thickness of the inner pedestal portion above the thermocouple is about 1 mm or greater.

[0077] Example 42. The apparatus of Example 39, wherein a depth of the cavity is in a range of about 2.3 mm to 7.7 mm.

[0078] Example 43. The apparatus of Example 39, wherein a wall of the cavity defines a cylinder.

[0079] Example 44. The apparatus of Example 39, wherein an upper end of the cavity is flat.

[0080] Example 45. The apparatus of Example 39, wherein a tip of the thermocouple inside the cavity is hemispherical.

[0081] Example 46. A method for processing a substrate, the method comprising:

[0082] providing a substrate on a pedestal in a processing chamber, wherein the pedestal comprises an inner pedestal portion and an outer pedestal portion surrounding the inner pedestal portion, and wherein the inner pedestal portion includes a cavity defining a volume for housing a thermocouple, the cavity being formed through a lower side of a middle portion of the inner pedestal portion;

[0083] providing a thermocouple in the cavity, wherein the thermocouple is spaced apart from a wall of the cavity by an air gap; and

[0084] processing the substrate on the pedestal in the processing chamber,

[0085] wherein processing the substrate includes heating the substrate and the pedestal, wherein the air gap is maintained during substrate processing.

[0086] Example 47. The method of Example 46, wherein a tip of the thermocouple contacts an upper end of the cavity when processing the substrate.

[0087] Example 48. The method of Example 46, wherein a material forming the thermocouple has a higher coefficient of thermal expansion than a material forming the pedestal.

[0088] Example 49. The method of Example 46, wherein a thickness of the inner pedestal portion above the thermocouple is about 1 mm or greater.

[0089] Example 50. The method of Example 46, wherein a depth of the cavity is in a range of about 2.3 mm to 7.7 mm.

[0090] Example 51. The method of Example 46, wherein the walls of the cavity define a cylinder.

[0091] Example 52. The method of Example 46, wherein an upper end of the cavity is flat.

[0092] Example 53. The method of Example 46, wherein a tip of the thermocouple is hemispherical. BRIEF DESCRIPTION OF DRAWINGS

[0093] Figure 1A is a top perspective view of a pedestal including an inner pedestal portion and an outer pedestal portion according to some embodiments.

[0094] Figure 1B is an example of a contact pad of an inner pedestal portion according to some embodiments.

[0095] Figure 2 is a top perspective view of an inner pedestal portion according to some embodiments.

[0096] Figure 3 is a top perspective view of a pedestal including an inner pedestal portion and an outer pedestal portion according to some embodiments, wherein corresponding depth plots illustrate a pedestal concavity.

[0097] Figure 4A is a perspective view of an outer pedestal portion according to some embodiments.

[0098] Figure 4B is a cross-sectional side view of an outer pedestal portion according to some embodiments.

[0099] Figure 4C This is a perspective view of the lower side of the outer base portion according to some embodiments.

[0100] Figure 5 It is a comparison between two instances of the shape of the protrusion of the outer base according to some embodiments.

[0101] Figure 6 This is a perspective view of the lower side of the internal base portion according to some embodiments.

[0102] Figure 7A and 7B This is a cross-sectional side view of the internal base portion according to some embodiments.

[0103] Figure 8 A cross-sectional side view of a semiconductor processing system according to some embodiments is schematically shown.

[0104] Figure 9 This is an exploded perspective view of a base including an inner base portion and an outer base portion according to some embodiments. Detailed Implementation

[0105] As mentioned above, several quality control issues can arise during semiconductor processing, and many of these issues may be related to the physical interaction between the substrate and the pedestal. One problem that can occur when processing a substrate supported on a pedestal is backside damage; that is, damage to the side of the substrate facing the pedestal. In some cases, backside damage can undesirably cause optical artifacts that interfere with lithography and subsequent patterning of features on the substrate.

[0106] It should be understood that backside damage can be caused by differential expansion and / or warping between the substrate and the underlying pedestal. The pedestal is typically made of a different material than the one forming the semiconductor substrate. Different materials can have different coefficients of thermal expansion. Therefore, when the substrate and pedestal are heated, they can expand at different rates, causing wear when the different materials come into contact with each other. Since the pedestal is typically formed of a harder material than the substrate, the substrate is often scratched or damaged from contact with the pedestal.

[0107] Advantageously, some embodiments described herein provide for point contact between the substrate and the susceptor, and can provide high quality processing results with low levels of backside damage. For example, the susceptor can have a plurality of pads that contact the overlying substrate at discrete points along the periphery of the substrate. For example, 3 to 12 pads, including 6 to 12 pads, can be provided equidistantly on the top surface of the susceptor. Preferably, 6 or more pads are provided that prevent the substrate from contacting other portions of the susceptor due to non-uniform warping of the substrate during heating. The pads can limit contact between the susceptor and the substrate, thereby limiting the extent of backside damage. Additionally, in some embodiments, a plurality of pads (1 to 6 or 3 to 6 pads) can be provided in a central region of the susceptor to further limit susceptor-substrate contact in that region. In some embodiments, the contact pads in the central region can be approximately directly opposite cavities for accommodating thermocouples on the underside of the susceptor.

[0108] As also described above, semiconductor processing preferably occurs under tightly controlled conditions. One of these conditions is temperature. It will be appreciated that the susceptor can affect temperature uniformity across the substrate. Because many processing results vary with temperature (e.g., the amount of deposited material can vary depending on local temperature variations across the substrate), temperature non-uniformity across the substrate can affect uniformity of processing results across the substrate.

[0109] In some embodiments, a multi-component susceptor can be utilized to facilitate automated substrate processing. The susceptor can have an inner portion that is smaller than the substrate and an outer portion that extends beyond the substrate. During processing, both the inner portion and the outer portion can support the substrate. To allow substrate manipulation, the inner portion can be raised above the outer portion, and because the other portion is smaller than the substrate, a peripheral portion of the substrate is exposed, allowing the substrate to be contacted and manipulated by a robotic arm.

[0110] The outer base portion can have a plurality of protrusions that extend below the inner base portion to support the inner portion and be integral with the inner portion. Undesirably, the additional material of the protrusions can cause temperature non-uniformity in the overlying substrate. Additionally, the many protrusions put into the cavity on the bottom of the inner portion and can require precise alignment between the inner portion and the outer portion to allow seating of the inner portion. In some embodiments, the protrusions have a generally triangular shape defined by curved sides that extend toward a vertex pointing toward the interior of the base. The generally triangular shape facilitates self-alignment of the protrusions within recesses on the bottom of the inner portion, which advantageously provides low mass support that extends invisibly under the overlying substrate. For example, the triangular shape advantageously reduces the amount of material that extends under the substrate relative to a rectangular protrusion. In some embodiments, the protrusions interlock with or are put into recesses of similar shape on the bottom of the inner portion; thus, the protrusions and recesses can be considered to have similar and complementary shapes that mate with each other. The recesses can have angled sidewalls that provide a relatively large recess opening that narrows gradually inside the recess. In some embodiments, the underside of the protrusions can have dimples or notches to further reduce the mass of those protrusions, further reducing the impact of those protrusions on temperature.

[0111] It will be appreciated that another cause of deviation from ideal processing results can be inaccurate process temperature settings due to inaccurate thermocouple readings. In some embodiments, the base can include an opening that houses a thermocouple for measuring the surface temperature of the base (e.g., the temperature of the upper surface of the base that directly faces the overlying substrate when a substrate is held on the base). Preferably, the opening is sized to maintain an air gap between the opening and the sidewalls of the thermocouple such that the gap is maintained during processing and the higher coefficient of thermal expansion of the thermocouple relative to the base is accounted for. In some embodiments, only the top of the thermocouple that is closest to the upper surface of the base contacts the body of the base. In some other embodiments, an air gap is maintained between the sides of the thermocouple and the opening and the top of the opening. Those skilled in the art will appreciate that the air gap can include a gas, including an inert gas, and can be a partial vacuum under processing conditions. Preferably, the volume is free of solid material that can cause conductive heat transfer between the thermocouple and the base.

[0112] Reference will now be made to the drawings wherein like numerals refer to like components throughout the several figures. It should be understood that the figures do not necessarily show the components to scale.

[0113] As noted herein, to facilitate substrate handling, the base can take the form of an assembly that includes a plurality of separable segments, e.g., two segments that can include an inner base portion and an outer base portion. It will be appreciated that the multi-part bases disclosed herein can be used in a variety of semiconductor processing systems, examples of which are shown in Figure 8 .

[0114] Figure 8 A cross-sectional side view of a semiconductor processing system is schematically shown in accordance with some embodiments. As shown, the processing system can include a pedestal 150 having both an inner pedestal portion 152 and an outer pedestal portion 154. The inner pedestal portion 152 and the outer pedestal portion 154 can fit together during processing to support the semiconductor substrate 210 together.

[0115] Figure 8 The processing chamber 50 is shown in further detail. As can be seen from this cross-sectional view, the outer pedestal portion 154 can surround and provide vertical support for the inner pedestal portion 152. This vertical support can be composed of complementary protruding flanges 156, also referred to as bosses, as discussed further herein. The outer pedestal portion 154 can protrude radially inward along its inner side margin to provide the support bosses 156, which can fit into complementary recesses on the underside of the inner pedestal portion 152. The outer pedestal portion 154 can rest on a plurality of supports 160 when the pedestal unit is in its lowest position. The drive shaft 130 can enter the processing chamber through an opening 132 in the floor of the processing chamber, the walls of which are continuous with a sleeve 134 that surrounds the drive shaft 130. The upper end of the drive shaft 130 can be articulated with a support tripod 120 that is positioned below the pedestal unit within the processing chamber. The tripod 120 can have a plurality of support elements or arms 122 that radiate outward from a central hub 124. The distal ends of the arms 122 can terminate in support posts or pins 128 that can fit into recessed sockets 126 and 127 in the lower surfaces of the inner pedestal portion or the outer pedestal portion, respectively (in this illustration, the tripod is shown engaging the inner portion 152). The articulation between the tripod arms 122 and the recessed sockets 126 can provide a positive coupling member for effecting rotational movement of the pedestal 150 and maintaining concentricity of the tripod and pedestal during thermal expansion.

[0116] The pedestal 150 can be surrounded by a temperature-compensating ring 159 that is supported on legs 161 that extend upward from a support ring 140 that has feet 141 that rest on the bottom wall 20 of the chamber. A thermocouple 129 can be inserted through the ring 159 to sense the temperature of the ring and the pedestal in the region. The thermocouple 129 can be inserted into the pedestal near the center of the inner pedestal portion 152 via a cavity 125 on the bottom surface of the inner pedestal portion. The thermocouple 129 can be surrounded by an air gap such that at least the sides of the thermocouple 129 do not contact the pedestal 150, for example as depicted in Figure 7A and 7B .

[0117] Figure 8A robot 190 is also shown, having an end effector 200 disposed on its distal end and carrying a wafer 210. The robot can enter the processing chamber from the access port (to the left). The end effector 200 can have a forged end that secures the wafer on a support arm 202, leaving an open area between the arms large enough to accommodate the inner susceptor portion 152. Thus, the inner susceptor portion can be moved vertically between the open arms 202 of the end effector to pick up (load) an unprocessed wafer, and can perform the reverse sequence to unload a processed substrate 210. The robot 190 can then be retracted, and during processing the substrate 210 is on the inner susceptor portion 152, heated and gas flowed into the processing chamber 50. During processing, even at high processing temperatures, in some embodiments the cavity 125 is wide enough that the sides of the thermocouple 129 avoid contact with the susceptor 150; that is, an air gap is maintained between the sides of the thermocouple 129 and the susceptor 150 during processing. As discussed further herein, this arrangement can have the advantage of providing accurate temperature measurements and thus high quality processing results.

[0118] Reference is now made to Figure 9 , which shows a perspective exploded view of a susceptor containing an inner susceptor portion 102 and an outer susceptor 104, in accordance with some embodiments. Figure 9 The manner in which a susceptor having an inner portion and an outer portion can be separated for substrate loading and unloading is shown. It will be appreciated that the inner susceptor portion 102 has a smaller area than the substrate to be retained on the inner portion 102. The inner susceptor portion 102 can be raised from the outer susceptor portion 104 during substrate loading and unloading. For example, a robot (not shown) can be used to load a substrate onto the inner portion 102, the robot contacting the substrate extending beyond the inner susceptor portion 102. Thus, the robot can lower the substrate onto the inner susceptor portion 102 and then retract. The inner susceptor portion 102 can then be lowered onto the outer susceptor portion 104. Raising and lowering the inner susceptor portion 102 can be accomplished using, for example, lift pins that contact and move the inner susceptor portion 102 up and down without moving the outer susceptor portion 104. To enable access to the retained semiconductor substrate during unloading of the substrate, the inner susceptor portion 102 can be raised, and a robot extends under the substrate to contact and lift the substrate.

[0119] Figure 1A A top perspective view of a susceptor 100 containing an inner susceptor portion 102 and an outer susceptor portion 104 is shown. The inner susceptor portion 102 can be surrounded by the outer susceptor portion 104. It will be appreciated that the susceptor 100 can correspond to the susceptor 150 of Figure 8 and the susceptor 150 of Figure 9and the inner susceptor portion 102 and the outer susceptor portion 104 can correspond to the inner susceptor portion 152 and the outer susceptor portion 154, respectively Figure 8 In some embodiments, the susceptor 100 is generally formed by machining graphite into the desired shape and coating with a silicon carbide (SiC) coating. The susceptor 100 can be formed in different shapes, but is preferably matched to the shape of the substrate to be supported. For example, for a circular semiconductor substrate such as a semiconductor wafer, the susceptor 100 can be circular, and both the inner susceptor portion 102 and the outer susceptor portion 104 can be circular (e.g., the inner susceptor portion 102 can generally be in the shape of a circular plate, and the outer susceptor portion 104 can be in the shape of a flat ring that surrounds the inner susceptor portion 102).

[0120] The outer susceptor portion 104 can include a ledge portion 105a, which can include a rim that is sloped or angled upward toward an outer edge of the outer susceptor portion 104. Preferably, the rim is positioned to extend around the perimeter of the substrate when the substrate is held on the susceptor 100. In some embodiments, the ledge portion 105a can contact the substrate due to the upward angle of the ledge portion 105a when the substrate is supported by the inner susceptor portion 102. In some embodiments, the contact between the ledge portion 105a and the substrate can prevent movement of the substrate, which can help to reduce backside damage of the substrate.

[0121] The inner susceptor portion 102 can include a plurality of contact pads or bumps 106 along the perimeter of the inner susceptor portion 102. The contact pads 106 can be on the top surface of the inner susceptor portion 102. When the inner susceptor portion 102 holds the substrate, the plurality of contact pads 106 will contact the substrate. Advantageously, the plurality of contact pads 106 provide support for the substrate while contacting only a relatively small surface area of the substrate in aggregate, which can reduce the instances of backside damage that can occur during wafer processing.

[0122] In some embodiments, the plurality of contact pads 106 are equally spaced around the perimeter of the inner susceptor portion 102. In some embodiments, the contact pads 106 are disposed immediately adjacent to the edges of the inner susceptor portion 102. In some embodiments, the plurality of contact pads 106 are a total of three or more, three to twelve, or six to twelve contact pads. While it can only take three contact pads to define a plane and support the substrate, it has been found that six contact pads advantageously address the problem of uneven substrate warping during heating and processing, for example, during epitaxial silicon deposition. Even with such warping, it is believed that six contact pads provide sufficient contact with the warped portion to prevent contact between the substrate and the major surface of the inner susceptor portion 102.

[0123] With continued reference to Figure 1AIn some embodiments, multiple contact pads 106 may be integrally formed with the inner base portion 102, providing good thermal stability and integrity for the contact pads. For example, the contact pads 106 may be processed to be formed on the inner base portion 102. In some other embodiments, the contact pads 106 may be formed separately and attached to the body of the inner base portion 102. It should be understood that the contact pads 106 may have various shapes. For example, the contact pads 106 may be as follows: Figure 1B The hemispherical mounting element shown provides a relatively small surface area for contact with the substrate. In some other embodiments, the plurality of contact pads 106 may be cylindrical. In some embodiments, the diameter of the contact pads 106 may range from about 0.5 mm to 3 mm, 0.5 mm to 2 mm, or 0.75 mm to 1.50 mm, including about 1 mm. The contact pads 106 may have a symmetrical cross-sectional shape as seen in the top view (e.g., generally circular or polygonal, such as hexagonal, orthogonal, etc.). The shape of the contact pads 106 may be configured to provide good substrate stability with a small amount of contact area with the overlay substrate. In some embodiments, the plurality of contact pads 106 may be polished, which may provide a more uniform contact surface with the substrate, while other portions of the inner base portion may not be polished. Polishing may provide a roughness of less than 0.4 μm Ra, less than 0.3 μm Ra, or less than 0.2 μm Ra on at least the top surface of the contact pads 106 that is expected to contact the overlay substrate. In some other embodiments, the plurality of contact pads 106 may not be polished.

[0124] Preferably, the height of the contact pad is sufficient to allow air to escape between the inner base portion 102 and the substrate at a sufficiently high rate to prevent undesirable lateral substrate movement during substrate loading as the air pad is lowered onto the inner base portion 102. In some embodiments, radial grooves may be provided in the surface of the inner base portion 102 to form vents that facilitate the escape of gas from the inner base portion 102 during substrate loading. Furthermore, the height of the contact pad 106 may be selected to adequately separate the substrate and the inner base portion 102 to account for substrate warping during processing. In some embodiments, the height of the contact pad may range from about 0.10 mm to 1 mm, about 0.10 mm to 0.5 mm, or about 0.15 mm to 0.2 mm. In some embodiments, the height is about 0.18 mm. In some embodiments, there are no grooves, and the top surface of the inner base portion 102 is flat except for the contact pad 106.

[0125] Figure 2A top perspective view of the inner susceptor portion 102 is shown with additional plurality of center contact pads 108. The center contact pads 108 are located on the substrate in an inner region, facing the upper surface of the inner susceptor portion 102, inside the contact pads 106. For example, the center contact pads 108 can be located near the center of the inner susceptor portion 102, and can surround the center point of the inner susceptor portion 102. These center contact pads 108 allow the inner susceptor portion 102 to contact and support the center region of the overlying substrate, and prevent contact with the upper main susceptor surface in the event that the substrate deforms during processing (e.g., if the center region of the substrate sags during processing). In some embodiments, the plurality of center contact pads 108 can collectively have one to six, or three to six contact pads. In some embodiments, the inner susceptor portion 102 can include a total of three center contact pads 108.

[0126] It should be appreciated that the above-described composition and / or shape of the contact pads 106 is applicable to the center contact pads 108. For example, the center contact pads 108 can be hemispherical shaped mounts integrally formed with the main body of the inner susceptor portion 102. In some embodiments, the center contact pads 108 can be cylindrical in shape. The center contact pads 108 can have a symmetrical cross-section, as seen in a top view. In some embodiments, the height of the center contact pads 108 can be less than the height of the contact pads 106, which can help address substrate blow-up or deformation issues during processing. For example, in some embodiments, the height of each of the center contact pads 108 can be in a range from about 0.05 mm to 1 mm, from about 0.05 mm to 0.5 mm, or from about 0.05 mm to 0.2 mm. In some embodiments, the height can be about 0.1 mm. In some embodiments, the contact pads 106 and the center contact pads 108 can have similar shapes and heights. In some other embodiments, the contact pads 106 and the center contact pads 108 can have different shapes and / or heights.

[0127] Referring now to Figure 3 , a top perspective view of the susceptor 100 including the inner susceptor portion 102 and the outer susceptor portion 104 is shown. An example of a corresponding depth plot 110 of the inner susceptor portion 102 is also shown. During heating, it has been observed that the substrate can deform or bow due to various mechanisms including differential thermal expansion of the substrate. For example, the substrate can bow such that its innermost portion is at a maximum depth, and the substrate gradually decreases in depth as the distance from the edge of the substrate decreases; thus, the substrate can form a concave shape. In some embodiments, providing the susceptor 100 with a concave surface that corresponds to the wafer bow can reduce backside damage. To compensate for this deformation that results in the substrate having a concave surface, the susceptor assembly 100 can also include a substantially matching concave surface.

[0128] With continued reference to Figure 3, the depth plot 110 illustrates an example of the concave surface of the base 100. The central region is at the maximum depth, and various other patterns depict gradually decreasing depths from the interior to the exterior, until the shallowest depth along the perimeter. While the depth plot 110 depicts depths (from section to section) at rigid depth changes for ease of illustration, the depths actually vary gradually.

[0129] In some embodiments, as depicted in the depth plot 110, the maximum depth at the center of the base 100 can be in the range of about 0.1 mm to 1 mm, about 0.15 mm to 0.8 mm, or about 0.23 mm to 0.47 mm. In some embodiments, the depth at the center of the base can be about 0.35 mm.

[0130] In some other embodiments, as depicted in the depth plot 110, the maximum depth at the center of the base 100 can be in the range of about 0.4 mm to 1 mm. In some embodiments, the depth at the center of the base can be about 0.48 mm. Further, in some embodiments, the spherical radius of the base 100 can be 19000 mm to 25000 mm, or 21901.28 mm. To achieve the overall base depths described herein, the inner base portion 102 can have a depth in the range of about 0.1 mm to 0.4 mm, and in some embodiments, the outer base portion 104 can have a depth in the range of about 0.4 mm to 1 mm. In some embodiments, the depth at the center of the inner base portion 102 can be about 0.38 mm, and the depth at the center of the outer base portion 104 can be about 0.48 mm.

[0131] Referring now to Figure 4A, showing a perspective view of the outer susceptor portion 104. In some embodiments, the outer susceptor portion 104 can have a diameter in a range of about 330 mm to 370 mm, about 340 mm to 360 mm, or about 351.53 mm to 352.05 mm. In some embodiments, the outer susceptor portion can have a diameter of about 351.79 mm. The diameter of the outer susceptor portion 104 can depend on the size of the semiconductor being processed. Since the outer susceptor portion 104 preferably supports the inner susceptor portion 102, the diameter of the outer susceptor portion 104 can be derived from the wafer diameter. In some embodiments, the outer susceptor portion 104 can have a thickness in a range of about 4 mm to 8 mm, about 5 mm to 7 mm, or about 6.09 mm to 6.61 mm. In some embodiments, the outer susceptor portion can have a thickness of about 6.35 mm. Like the diameter, the thickness of the outer susceptor portion 104 can be influenced by the thickness of the semiconductor and the inner susceptor portion 102. Since the outer susceptor portion is formed from multiple layers of surfaces, including surfaces at different heights, the thickness of each layer can depend on the thickness of the inner susceptor portion 102 supported by the layer. The thickness of the inner susceptor portion 102, in turn, can depend on the thickness of the wafer. In some embodiments, a hole in the center of the outer susceptor portion 104 defined by an inner edge of the lowest top surface 104c (described below) can have a diameter in a range of about 200 mm to 250 mm, about 210 mm to 240 mm, or about 225.34 mm to 225.4 mm. In some embodiments, the inner diameter of the top surface 104b can be about 225.37 mm. The inner diameter of the outer susceptor portion 104 can also depend on the size of the semiconductor being processed. The inner edge of the outer susceptor portion 104 can support the inner susceptor portion 102 and, therefore, is sized to accommodate the inner susceptor portion 102. The inner susceptor portion 102 is sized to accommodate the wafer.

[0132] With continued reference to Figure 4A , the outer susceptor portion 104 can have multiple top surfaces 104a, 104b, 104c at different heights, each disposed on a different plane (at different vertical levels), as shown in Figure 4A . The top surfaces 104a, 104b, 104c can have a circular ring or annular shape. The top surfaces 104a, 104b, 104c can be aligned along a shared central axis, such that the top surfaces 104a, 104b, 104c are concentric with each other when viewed in a top view. The top surfaces 104a, 104b, 104c can be aligned with the disks of the inner susceptor portion 102, such that the outer susceptor portion and the inner susceptor portion interlock, thereby fixing the components in place relative to each other (e.g., as with respect to Figure 9The outer base portion 104 can include protruding portions 105a, 105b. The protruding portion 105a connects the top surfaces 104a, 104b, and the protruding portion 105b connects the top surfaces 104b and 104c. The protruding portions 105a, 105b can be inclined with respect to the top surfaces 104a, 104b, 104c (e.g., the protruding portions 105a, 105b can be inclined toward the top surfaces 104b and 104c, respectively). As described above, the outer base portion 104 supports the inner base portion 102, which in turn supports the substrate during processing. To securely hold the inner base portion 102 in place, the outer base portion 104 can include a plurality of tabs or protrusions 402 that contact and support the inner base portion 102. Figure 1A In some embodiments, the lowest top surface 104c can have tabs 402. In some other embodiments, the other top surfaces 104a, 104b can have tabs 402. In some embodiments, the number of tabs 402 can be three tabs. However, the number of tabs can be selected to facilitate manufacturing while still securely holding the inner base portion 102. Preferably, the outer base portion includes 3 or more tabs 402. In some embodiments, the length of the tabs 402 can be in a range from about 5 mm to about 9 mm, from about 6 mm to 8 mm, from about 6.87 mm to 7.13 mm. In some embodiments, the length of the tabs can be about 7 mm.

[0133] In embodiments where the tabs 402 are located on the same plane as the lowest top surface 104c, the lowest top surface 104c can form an inner slot on which the inner base portion can rest. The distance between the lowest top surface 104c and the next surface 104b can be the inner slot depth. In some embodiments, the inner slot can have a diameter in a range from about 200 mm to 300 mm, from about 230 mm to 270 mm, or from about 244.16 mm to 244.32 mm. In some embodiments, the diameter of the inner slot can be about 244.24 mm. The inner slot can have a depth in a range from about 2 mm to 3 mm, from about 2 mm to 2.5 mm, or from about 2.26 mm to 2.36 mm. In some embodiments, the inner slot depth can be about 2.31 mm.

[0134] Figure 4Bis a side cross-section of an outer susceptor portion according to some embodiments. The protruding portions 105a, 105b can be tilted upward at an angle in the range of about 2.9° to 3.1°, or about 2.95° to 3.05°, with respect to a horizontal axis of the susceptor (e.g., the horizontal plane on which the susceptor sits). In some embodiments, the angle can be about 3°. The protruding portions can be fully polished or can be polished only at the bevels. In some embodiments, the protruding portions can have an average roughness profile Ra of about 0.4 microns Ra or less, about 0.3 microns Ra or less, or about 0.2 microns or less.

[0135] Figure 4C is a perspective view of the underside of an outer susceptor portion according to some embodiments. Referring now to Figure 4C A recess 402a is formed on the underside of each tab 402. The recess 402a can be formed by an apex that is generally triangular in shape in the radial direction. The recess 402a can have a V-shaped cross-sectional shape as viewed in cross-section taken along a plane transverse to the radial axis. The recess 402a can reduce the thermal mass of the tab 402, which can reduce the impact of the tab 402 on the temperature of the entire inner susceptor portion 102, for example, by reducing the amount of heat absorbed by the tab 402. Thus, the inner susceptor portion 102 can maintain a more uniform temperature across its entire surface when the inner susceptor portion 102 is in contact with the tabs 402 during substrate processing. In turn, a more uniform temperature across the substrate can be maintained, which can reduce substrate temperature non-uniformity and associated processing non-uniformity. It will be appreciated that the shape and size of the recess 402a can be set to accommodate a susceptor support pin or other support structure. The shape of the tab 402 has been found to further determine the degree of temperature non-uniformity and can also easily align the inner susceptor portion 102 with the outer susceptor portion 104. Referring now to Figure 5 , a comparison between two example shapes of the tabs 402 is shown. The first tab shape 504 is generally rectangular, while the second tab shape 502 is generally triangular. In some embodiments, the second tab shape 502 can be understood to be generally triangular in the sense that the sides of the shape are angled at the main expansions of the sides, which converge at a common point if extended. In contrast, the main expansions of the sides of the generally rectangular first tab shape 504 are parallel and can extend to infinity without converging.

[0136] With continued reference to Figure 5The second tab shape 502 has a reduced perimeter length and a reduced contact area when compared to the first tab shape 504. The area of the second tab shape 502 can be equal to or less than half the area of the first tab shape 504. In some embodiments, the area of the second tab shape 502 is about 24% of the area of the first tab shape 504. Further, the perimeter length of the second tab shape 502 can also be equal to or less than half the area of the first tab shape 504. In some embodiments, the length of the perimeter of the second tab shape 502 is about 43% of the circumference of the first tab shape 504. The plurality of tabs are points of contact between the inner susceptor portion 102 and the outer susceptor portion 104, and thus tabs having a smaller surface area will provide a smaller contact surface area, which can reduce the area and / or reduce temperature non-uniformity across the substrate.

[0137] The substantially triangular shape of the tab design of the second tab shape 502 can provide self-centering when aligning the inner susceptor portion 102 with the outer susceptor portion 104, particularly when compared to the substantially rectangular shape of the first tab shape 504. In some embodiments, the edges of the first tab shape 504 and the second tab shape 502 can be chamfered to further facilitate self-centering. For example, where the tabs 502 and 504 are horizontally flatly oriented, the walls of the tab edges can be understood to be angled such that a lower portion of the tab occupies a greater area than an upper portion of the tab. In some embodiments, the edge chamfer (the angle formed by the edge in a horizontal plane on which the outer susceptor portion 104 is flatly positioned) can be in a range of about 60° to 80°, about 62° to 78°, about 64° to 76°, about 65° to 75°, about 66° to 74°, about 67° to 73°, about 68° to 72°, or about 69° to 71°. In some embodiments, the edge chamfer can be about 70°.

[0138] Figure 6 A perspective view of the underside of the inner susceptor portion 102 is shown. In some embodiments, the inner susceptor portion 102 can have a diameter in a range of about 245 mm to 265 mm, about 250 mm to 260 mm, or about 257.46 mm to 257.62 mm, which in some embodiments depends on the size of the substrate to be processed on the susceptor 150 of which the inner susceptor portion 102 is a part. In some embodiments, the diameter of the inner susceptor portion 102 can be about 257.54 mm. In some embodiments, the inner susceptor portion 102 can have a thickness in a range of about 4.5 mm to 6.5 mm, about 5 mm to 6 mm, or about 5.47 mm to 5.73 mm. In some embodiments, the thickness of the inner susceptor portion 102 can be about 5.6 mm.

[0139] In some embodiments, the inner base portion 102 can have a shape in which a first disc 102a and a second disc 102b each having different diameters when viewed from the underside are concentrically overlapped with each other. As shown, the second disc 102b can extend completely over and beyond the second disc 102a. When the inner base portion 102 and the outer base portion 104 are integral to form a single unit, the first disc 102a can fit just into the opening of the top surface 104c of the outer base portion, and the second disc 102b can fit just into the opening of the top surface 104b of the outer base. The top surface 104c of the outer base can support the perimeter of the second disc 102b. In some embodiments, the first disc 102a can have a diameter in the range of about 200 mm to 250 mm, about 210 mm to 240 mm, about 220 mm to 230 mm, or about 225.12 mm to 225.28 mm. In some embodiments, the first disc 102a can have a diameter of about 225.20 mm. In some embodiments, the second disc 102b can have a diameter in the range of about 220 mm to 270 mm, about 230 mm to 260 mm, about 240 mm to 250 mm, or about 244.11 mm to 244.37 mm. In some embodiments, the second disc 102b can have a diameter of about 244.24 mm.

[0140] The first disc 102a can have recessed seats 126 around the inner perimeter of the disc. The recessed seats 126 can take the form of circular indentations and can receive corresponding mechanical arms that support tripods 120, as described with respect to FIGS. 1A-1C. Figure 8 The first disc 102a can have one or more, three or more, or six or more recessed seats 126. In some embodiments, the first disc 102a can have three recessed seats 126, on which the inner base portion 102 can rest on the support tripods 120. The first disc 102a can also have a cavity 125, 604 near the center of the inner base portion 102 for receiving a thermocouple 606. Figure 7A and 7B

[0141] The underside of the inner base portion 102 includes recesses 404. For example, the disc 102a can have recesses 404. These recesses 404 are in addition to the recesses 404 of the outer base portion 104. Figure 4A ​The tabs 402 of the outer base portion 104 shown in FIG. 4 are opposite and correspond to the recesses 404. The shape, number, and location of the recesses 404 preferably correspond to the shape, number, and location of the tabs 402. When the inner base portion 102 is lowered onto the outer base portion 104, the recesses 404 and tabs 402 align and mate; the tabs 402 fit into the recesses 404. By having corresponding recesses 404 and tabs 402, the inner base portion 102 is held in a fixed position relative to the outer base portion 104, which keeps a retained substrate from being damaged by relative movement of the inner base portion 102 and the outer base portion 104 when a substrate is present on the inner base portion 102.

[0142] Preferably, the edges of the recesses 404 are chamfered. In some embodiments, the edges are chamfered such that they provide a relatively large recess opening that tapers to a smaller opening as the height increases.

[0143] Reference is now made to FIG. 6, Figure 7A and 7B showing a cross-sectional side view of the inner base portion 102. An enlarged view of the middle portion 602 of the inner base portion 102 has been provided. The middle portion 602 can include a cavity 604 in the inner base portion 102, within which a thermocouple 606 can be housed. It will be appreciated that the thermocouple 606 measures the temperature of the inner base portion 102. While close contact between the thermocouple 606 and the inner base portion 102 would be expected to provide the most accurate temperature measurement, it has been found that limited contact between the thermocouple 606 and the inner base portion 102 can improve the accuracy of the temperature measurement. Without being limited by theory, it is believed that the thermocouple 606 can act as a heat sink and inadvertently transfer heat from the inner base portion 102 as it measures the temperature of the inner base portion 102. It has been found that positioning the thermocouple 606 such that the thermocouple 606 does not touch the walls of the middle portion 602 of the inner base portion 102 can provide a more accurate temperature reading by reducing the heat transferred from the interior of the inner base portion 102. In some embodiments, the cavity 604 is larger than the tip of the thermocouple 606. For example, the cavity 604 can be wider than the width of the thermocouple 606. It will be appreciated that the cavity 604 can be similar to the cavity 125 described with respect to FIG. 5. Figure 8

[0144] ​Additionally, it should be understood that both the internal base portion 102 and the thermocouple 606 thermally expand upon heating, and therefore the diameter of the cavity 604 can be adjusted to account for thermal expansion, ensuring that the sidewalls of the internal base portion 102 do not touch the thermocouple 606. It has been found that materials typically used for the thermocouple and the base have different coefficients of thermal expansion, with the thermocouple typically expanding more than the base. In some embodiments, the cross-sectional area of ​​the cavity 604 is preferably larger than the corresponding cross-sectional area of ​​the thermocouple 606, such that a gap between the cavity 604 and the thermocouple 606 is maintained at high temperatures for semiconductor processing (e.g., at temperatures of 200 to 1300°C, 200 to 1000°C, or 250 to 500°C). In some embodiments, the gap between the thermocouple 606 and the wall of the cavity 604 can be maintained as a gas-containing gap (e.g., an inert gas), which in some embodiments may be under vacuum. In some other embodiments, the gap may be filled with a suitable material having low thermal conductivity. Thermocouple 606 may be generally cylindrical in shape, with a domed tip at the end inserted into cavity 604. Cavity 604 may be generally cylindrical, with a flat end in the inner base portion 102. Figure 7A As shown, in some embodiments, the air gap may extend around the sides and top of the tip of thermocouple 606, such that thermocouple 606 does not contact the inner base portion 102 at all. More preferably, and as shown... Figure 7B As shown, the upper portion of thermocouple 606 can contact the inner base portion 102 to provide measurement of the base temperature near the upper surface of the retained substrate, while providing only a low level of contact and thermal conduction between the inner base portion 102 and the thermocouple 606. Preferably, the thickness of the portion of the inner base portion 102 above the thermocouple 606 is sufficient to protect the thermocouple from direct infrared light (e.g., infrared light from a heating lamp used in a heat treatment chamber). In some embodiments, the thickness of the inner base portion 102 above the thermocouple 606 is about 1 mm or more, about 1.2 mm or more, or about 1.3 mm or more, including about 1.3 mm, and in some embodiments includes an upper limit of 1.5 mm. In some embodiments, the total thickness of the inner base portion 102 can range from about 3 mm to 8 mm, about 4 mm to 7 mm, or about 5 mm to 6 mm. In some embodiments, the depth of cavity 604 may be in the range of about 2.3 mm to 7.7 mm, about 4.3 mm to 6.7 mm, or about 4.22 mm to 4.38 mm. In some embodiments, the total thickness of the inner base portion 102 may be about 5.6 mm, the cavity 604 may be about 4.3 mm deep, and the thickness of the inner base portion 102 above the thermocouple 606 is about 1.3 mm.

[0145] It will be appreciated that the position of the upper portion of the thermocouple 606 relative to the inner susceptor portion 102 can affect the accuracy of the thermocouple temperature reading. In some embodiments, the thermocouple 606 can be in direct contact with the top portion of the cavity 604, such that the thermocouple 606 can measure the temperature of the susceptor at a particular point of contact, while maintaining a low level of thermal conduction between the thermocouple 606 and the susceptor, thereby reducing temperature non-uniformity across the substrate that can be caused by the thermocouple 606. In some other embodiments, the thermocouple 606 can be surrounded by an air gap, such that the thermocouple does not contact the susceptor at all. In such embodiments, the thermocouple 606 can be placed within a distance from the susceptor, such that the thermocouple 606 can still obtain an accurate temperature of the center of the susceptor. In embodiments with a fully surrounding air gap, the ratio of the air gap between the thermocouple 606 and the top of the cavity 604 to the air gap between the sides of the thermocouple and the walls of the cavity can be about 1 : 1 or lower, about 1 :2 or lower, about 1 :4 or lower, or about 1 :8 or lower. It will be further appreciated that the size of the cavity 604 can be small enough to maintain accurate thermal readings, while still preventing direct contact between the thermocouple 606 and at least the sides of the cavity 604. In some embodiments, the diameter of the cavity can be in the range of 3 mm to 8 mm, including 4 mm to 5 mm. In some embodiments, the diameter of the cavity can be 4.32 mm.

[0146] In some embodiments, the surface of the outer susceptor portion 104 can include a grid, which can be formed by flat planes or islands of susceptor material separated by grooves. In some other embodiments, the surface of the outer susceptor portion 104 can be smooth and omit the grid. Preferably, the surface of the outer susceptor portion 104 is smooth to reduce the risk of substrate damage due to contact with sharp grid groove edges.

[0147] While the application has been described in terms of certain embodiments, other embodiments apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are within the scope of the present disclosure. As one of ordinary skill in the art will appreciate, each of the various modifications described and illustrated herein has discrete components and features that can be readily separated from or combined with features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. For example, in some embodiments, a susceptor can have all of the various features disclosed herein (including the protruding portions, pads, concave surfaces, raised portions, and thermocouple arrangements described above). In some embodiments, a susceptor can include only one or less than all of the above features (e.g., only one or less than all of the above protruding portions, pads, concave surfaces, raised portions, and thermocouple arrangements). All such modifications are intended to be within the scope of the claims associated with the present disclosure.

Claims

1. An apparatus for processing a substrate, the apparatus comprising: Processing chamber, the processing chamber being configured to contain a substrate; as well as A base, disposed within the processing chamber and configured to support the substrate, The base includes an inner base portion and an outer base portion surrounding the inner base portion. The inner base portion includes a plurality of recesses, and the outer base portion includes a plurality of protrusions extending below the inner base portion to support the inner base portion. Each of the protrusions has a generally triangular shape and is aligned with a corresponding one in the recess, wherein the apex of the triangular shape of the protrusion protrudes toward the center of the inner base portion, and the edges of the protrusion are chamfered such that the lower portion of the protrusion occupies a larger area than the upper portion of the protrusion.

2. The device of claim 1, wherein the inner base portion is smaller than the substrate, and the outer base portion extends beyond the substrate.

3. The device according to claim 1, wherein the internal base portion has a shape in which a first disk and a second disk overlap concentrically, the diameter of the first disk being smaller than the diameter of the second disk.

4. The device according to claim 1, wherein the outer base portion comprises a plurality of concentric annular top surfaces, each of the annular top surfaces being disposed on a different vertical plane.

5. The device according to claim 1, wherein each protrusion has a radial groove on the lower side of the protrusion.

6. The device according to claim 1, wherein the edge of the protrusion has a chamfer in the range of 60° to 80°.

7. The apparatus of claim 1, wherein during processing of the substrate, the inner base has a concave shape corresponding to a concave surface of the substrate, wherein the concave shape has a depth in the range of 0.15 mm to 0.8 mm.

8. The device of claim 1, wherein the inner base portion includes a plurality of contact pads along the periphery of the inner base portion, the pads protruding from the surface of the inner base portion to support the substrate and prevent the substrate from contacting the surface.

9. The device of claim 8, wherein the contact pad has a hemispherical shape.

10. The device of claim 8, wherein the height of the pad is in the range of about 0.10 mm to 0.5 mm.

11. A base for supporting a substrate, the base comprising: An inner base portion, wherein the inner base portion includes a plurality of recesses; as well as An outer base portion that surrounds the inner base portion. The outer base portion includes a plurality of protrusions extending below the inner base portion to support the inner base portion. Each of the protrusions has a generally triangular shape and is aligned with a corresponding one in the recess, wherein the apex of the triangular shape of the protrusion protrudes toward the center of the outer base portion, and the edges of the protrusion are chamfered such that the lower portion of the protrusion occupies a larger area than the upper portion of the protrusion.

12. The base of claim 11, wherein the inner base portion is smaller than the substrate, and the outer base portion extends beyond the substrate.

13. The base according to claim 11, wherein the inner base portion has a shape in which a first disk and a second disk overlap concentrically, the diameter of the first disk being smaller than the diameter of the second disk.

14. The base according to claim 11, wherein the outer base portion comprises a plurality of concentric annular top surfaces, each of the annular top surfaces being disposed at a different vertical plane.

15. The base according to claim 11, wherein at least one protrusion has a groove on its underside, the groove being generally triangular in shape, the apex of which extends radially outward from the center face of the outer base portion.

16. The base according to claim 11, wherein the edge of the protrusion has a chamfer in the range of 60° to 80°.

17. The base of claim 11, wherein during processing of the substrate, the inner base has a concave shape corresponding to a concave surface of the substrate, wherein the concave shape has a depth in the range of 0.15 mm to 0.8 mm.

18. The base of claim 11, wherein the inner base portion includes a plurality of contact pads along the periphery of the inner base portion, the pads protruding from the surface of the inner base portion to support the substrate and prevent the substrate from contacting the surface.

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