Flat pocket susceptor design for improved heat transfer.

Abstract

The embodiments of the present disclosure generally relate to a susceptor for thermal processing of a semiconductor substrate. In one embodiment, the susceptor includes an inner region having a pattern formed on a top surface thereof, the pattern including a plurality of substrate support features separated by a plurality of ventilation channels. The susceptor includes a rim surrounding the inner region and coupled to the inner region, the inner region being recessed relative to the rim to form a recessed pocket configured to receive a substrate. The susceptor includes a plurality of bumps extending radially inward from an inner diameter of the rim, the plurality of bumps configured to contact an outer edge of a substrate supported by the plurality of substrate support features to position the substrate within the recessed pocket.

Description

[Technical Field]

[0001] TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to susceptors for use in thermal processing chambers. [Background technology]

[0002]

[0002] Semiconductor substrates are processed for a variety of applications, including the fabrication of integrated devices and microdevices. During processing, the substrate is positioned on a susceptor within a process chamber. The susceptor often has a disk- or dish-shaped upper surface that is used to support the substrate from below. The susceptor is supported by a support shaft that is rotatable about a central axis. By precisely controlling a heat source, such as multiple heat lamps, positioned below the susceptor, the susceptor can be heated within very tight tolerances. The heated susceptor can transfer heat to the substrate primarily through radiation emitted by the susceptor.

[0003]

[0003] Despite precise control of susceptor heating, it has been observed that susceptors can cause temperature non-uniformities across a substrate due to uneven heat transfer between areas of the substrate in contact with the susceptor and areas of the substrate not in contact with the susceptor. The temperature non-uniformities often persist across the top surface of the substrate and degrade the quality of layers deposited on the substrate. Unfavorable temperature profiles have been observed near the edge of the substrate and in areas near the center of the substrate. Therefore, a need exists for an improved susceptor for supporting and heating substrates in semiconductor processing. Summary of the Invention

[0004]

[0004] Embodiments of the present disclosure generally relate to a susceptor for thermal processing of semiconductor substrates. In one embodiment, the susceptor includes an inner region having a pattern formed on an upper surface thereof, the pattern including a plurality of substrate support features separated by a plurality of ventilation channels. The susceptor includes a rim surrounding the inner region and coupled to the inner region, the inner region being recessed relative to the rim to form a recessed pocket configured to receive the substrate. The susceptor includes a plurality of bumps extending radially inward from an inner diameter of the rim, the plurality of bumps configured to contact an outer edge of a substrate supported by the plurality of substrate support features to position the substrate within the recessed pocket.

[0005] In another embodiment, a method for manufacturing a susceptor includes forming a plurality of channels in a top surface of a recessed pocket of the susceptor, the plurality of channels having a plurality of support features formed therebetween. Forming the plurality of channels and the plurality of support features includes forming a first plurality of cuts in a first direction with a cutting tool, rotating the susceptor by a first angle relative to the cutting tool, and forming a second plurality of cuts in a second direction with the cutting tool, the second direction being spaced apart from the first direction by the first angle. The method includes recessing the top surface of the recessed pocket.

[0006] In yet another embodiment, a susceptor includes an inner region having a pattern formed on an upper surface thereof, the pattern including a plurality of substrate support features separated by a plurality of ventilation channels. Each substrate support feature includes a substrate contact surface along an upper surface of the inner region, the substrate contact surface being substantially planar with respect to a lateral plane of the susceptor. The susceptor includes a rim surrounding and coupled to the inner region, the inner region being recessed relative to the rim to form a recessed pocket configured to receive a substrate.

[0007]

[0007] In order that the above-described features of the present disclosure may be understood in detail, the above-summarized disclosure will be more particularly described by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure, which may also admit of other equally effective embodiments. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a process chamber having an exemplary flat pocket susceptor according to one or more embodiments. [Figure 2] 2A is an isometric view of the exemplary susceptor of FIG. 1 according to one or more embodiments, and FIG. 2B is a partial cross-sectional view of the susceptor of FIG. 2A according to one or more embodiments. [Figure 3] 3A is an enlarged partial cross-sectional view of an exemplary susceptor of FIG. 1 according to one or more embodiments; FIG. 3B is a top view of a portion of the susceptor of FIG. 3A according to one or more embodiments; and FIG. 3C is an enlarged cross-sectional view of a portion of the susceptor of FIG. 3A according to one or more embodiments. [Figure 4] 2 is a partial cross-sectional view of another exemplary susceptor that may be used in the process chamber of FIG. 1 according to one or more embodiments. [Figure 5] 5A is a partial cross-sectional view of yet another exemplary susceptor that may be used in the process chamber of FIG. 1 according to one or more embodiments, and FIG. 5B is a top view of a portion of the susceptor of FIG. 5A according to one or more embodiments. [Figure 6] 1A-1D illustrate a method for manufacturing a susceptor according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0009]

[0018] To facilitate understanding, wherever possible, the same reference numerals have been used to designate identical elements common to the figures. It is believed that elements disclosed in one embodiment may be beneficially employed on other embodiments without specific recitation.

[0010]

[0019] Embodiments of the present disclosure generally relate to susceptors for thermal processing of semiconductor substrates. The disclosed embodiments can improve thermal uniformity across the surface of a substrate during processing by reducing the contact surface area between the susceptor and the substrate. Reducing the contact surface area between the susceptor and the substrate reduces the amount of heat transferred from the susceptor to the substrate by conduction during processing. In some embodiments, an inner region of the susceptor includes a pattern formed on its upper surface, the pattern including a plurality of substrate support features separated by a plurality of ventilation channels. In some embodiments, each substrate support feature includes a substrate contact surface along the upper surface of the inner region, the substrate contact surface being substantially flat. In some embodiments, the size of each substrate contact surface is reduced to increase the number of contact points between the susceptor and the substrate while minimizing the contact surface area. In some embodiments, the susceptor may further include a plurality of bumps that help radially position and / or center the substrate on the susceptor while reducing the contact surface area between the substrate and the susceptor. Reducing the contact surface area between the substrate and the susceptor can reduce the hot spot effect caused by higher than average heat transfer to the substrate at its outer edges. Details of susceptor embodiments are described below.

[0011] Exemplary Chamber Hardware

[0020] 1 is a schematic cross-sectional view of an exemplary process chamber 100 including a flat pocket susceptor 106, which is described further below. While a process chamber for epitaxial processing is illustrated and described, it is contemplated that the susceptors of the present disclosure may also be used in other types of process chambers capable of providing controlled thermal cycles to heat a substrate for processes such as, for example, thermal annealing, thermal cleaning, thermal chemical vapor deposition, thermal oxidation, and thermal nitridation, regardless of whether heating elements are provided on the top, bottom, or both of the process chamber.

[0012]

[0021] The process chamber 100 and associated hardware may be formed from one or more process-compatible materials, such as, for example, stainless steel, quartz (e.g., fused silica glass), SiC, CVD-coated SiC (30-200 microns) on graphite, and combinations and alloys thereof. The process chamber 100 can be used to process one or more substrates, including depositing materials on the top surface of a substrate 108. The process chamber 100 includes, among other components, an array of radiant heat lamps 102 for heating the backside 104 of a susceptor 106 disposed within the process chamber 100. The susceptor 106 may be located within the process chamber 100 between an upper dome 128 and a lower dome 114. In some embodiments, an array of radiant heat lamps may be disposed above the upper dome 128 in addition to the array shown below the lower dome 114. The susceptor 106 may be a disk-shaped susceptor or may be a ring-shaped susceptor support with a central opening that supports the substrate from its edge and facilitates exposure of the substrate to the thermal radiation of the lamps 102. According to one embodiment, the susceptor 106 is supported by a central shaft 132, which may support the susceptor 106 directly or indirectly, as shown in FIG.

[0013]

[0022] The upper dome 128, the lower dome 114, and the base ring 136 disposed between the upper dome 128 and the lower dome 114 define an interior region of the process chamber 100. Central portions of the upper dome 128 and the lower dome 114 may be formed from an optically transparent material such as quartz. The interior region of the process chamber 100 is generally divided into a process region 156 and a purge region 158. A substrate 108 (not to scale) may be loaded into the process chamber 100 through a loading port (not shown, obscured by the susceptor 106) and positioned on the front side 110 of the susceptor 106.

[0014]

[0023] According to one embodiment, the process chamber 100 also includes a lamp head 145 that supports the array of lamps 102 and cools the lamps 102 during and / or after processing. Each lamp 102 is coupled to a power distribution board (not shown) that provides electricity to each lamp 102.

[0015]

[0024] An optional preheat ring 167 may be disposed around the susceptor 106 and surrounded by the liner assembly 163. The preheat ring 167 prevents or reduces the leakage of thermal and / or optical noise from the lamps 102 to the device side 116 of the substrate 108 while providing a preheat zone for the process gases. The preheat ring 167 may be made of chemical vapor deposited (CVD) SiC, SiC-coated sintered graphite, grown SiC, opaque quartz, coated quartz, or any similar suitable material that is resistant to chemical attack by the process and purge gases.

[0016]

[0025] The liner assembly 163 is sized to nest within or be surrounded by the inner periphery of the base ring 136. The liner assembly 163 shields the metal walls of the process chamber 100 from the process gases used for processing, which may react with and damage the metal walls or introduce contamination into the process chamber 100. While the liner assembly 163 is illustrated as a single unit, in embodiments of the present disclosure, the liner assembly 163 may include one or more liners and other components.

[0017]

[0026] In one embodiment, the process chamber 100 may also include one or more optical pyrometers 118 that measure the temperature within the process chamber 100 and on the surface of the substrate 108. A controller (not shown) controls the distribution of power from a power panel to the lamps 102 and the flow of coolant within the process chamber 100. The controller controls the temperature within the process chamber 100 by varying the voltage from the power panel to the lamps 102 and varying the flow of coolant.

[0018]

[0027] A reflector 122 can optionally be disposed on the outside of the upper dome 128 to reflect infrared light emitted from the substrate 108 and the upper dome 128 into the process chamber 100. The reflector 122 can be secured to the upper dome 128 using a clamp ring 130. The reflector 122 can have one or more connection ports 126 connected to a coolant source (not shown). The connection ports 126 can be connected to one or more passages (not shown) in the reflector 122 so that a coolant (e.g., water) can circulate within the reflector 122.

[0019]

[0028] In one embodiment, the process chamber 100 includes a process gas inlet 174 connected to a process gas source 172. The process gas inlet 174 may be configured to direct process gas across approximately the entire surface of the substrate 108, across the device side 116. The process chamber 100 may also include a process gas outlet 178 located on an opposite side of the process chamber 100 from the process gas inlet 174. The process gas outlet 178 is coupled to a vacuum pump 180.

[0020]

[0029] In one embodiment, the process chamber 100 includes a purge gas inlet 164 formed in a sidewall of the base ring 136. A purge gas source 162 supplies purge gas to the purge gas inlet 164. If the process chamber 100 includes a preheat ring 167, the preheat ring 167 is disposed between the process gas inlet 174 and the purge gas inlet 164. The process gas inlet 174, the purge gas inlet 164, and the process gas outlet 178 are shown for illustrative purposes; the location, size, number, etc. of the gas inlets and outlets can be adjusted to facilitate uniform deposition of material on the substrate 108.

[0021]

[0030] The susceptor 106 is shown in a position that allows for processing of a substrate in the process chamber. The central shaft 132 and susceptor 106 can be raised and lowered 134 by an actuator (not shown). A number of lift pins 105 extend through the susceptor 106. When the susceptor 106 is lowered to a loading position below the processing position, the lift pins 105 contact the lower dome 114 and pass through holes in the susceptor 106, allowing the substrate 108 to be lifted from the susceptor 106. A robot (not shown) then enters the process chamber 100 and engages and removes the substrate 108 from a loading port (not shown). This robot or another robot enters the process chamber through the loading port and places an unprocessed substrate on the susceptor 106. The actuator then raises the susceptor 106 to the processing position, and the unprocessed substrate is placed in the processing position.

[0022]

[0031] In one embodiment, processing a substrate 108 in the process chamber 100 includes inserting the substrate 108 through a loading port, placing the substrate 108 on the susceptor 106, raising the susceptor 106 and substrate 108 to a processing position, heating the substrate 108 with lamps 102, flowing process gas 173 over the substrate 108, and rotating the substrate 108. In some cases, the substrate may also be raised and lowered 134 during processing.

[0023]

[0032] In some aspects of the present disclosure, epitaxial processing in the process chamber 100 includes controlling the pressure in the process chamber 100 to be below atmospheric pressure. In some embodiments, the pressure in the process chamber 100 is reduced to be between about 10 Torr and 80 Torr. In some embodiments, the pressure in the process chamber 100 is reduced to be between about 80 Torr and 300 Torr. A vacuum pump 180 is activated to reduce the pressure in the process chamber 100 before and / or during processing.

[0024]

[0033] Process gases 173 are introduced into the process chamber 100 through one or more process gas inlets 174 and exhausted from the process chamber 100 through one or more process gas outlets 178. The process gases 173 deposit one or more materials onto the substrate 108, for example, through pyrolysis or other reactions. After depositing the materials on the substrate 108, waste products 175 (i.e., waste gases) are formed from the reaction. The waste products 175 are exhausted from the process chamber 100 through the process gas outlets 178.

[0025]

[0034] Once processing of the substrate 108 is complete, the process chamber is purged of process gas 173 and waste products 175 by introducing a purge gas 165 (e.g., hydrogen or nitrogen) through a purge gas inlet 164. The purge gas 165 can be introduced through the process gas inlet 174 instead of or in addition to the purge gas inlet 164. The purge gas 165 is exhausted from the process chamber 100 through a process gas outlet 178.

[0026] Exemplary Susceptors

[0035] FIG. 2A is an isometric view of an exemplary susceptor 106 that may be used in process chamber 100 ( FIG. 1 ) or other suitable process chamber. The susceptor 106 is a substantially circular plate divided into an inner region 204 and a rim 206 that surrounds and is connected to the inner region 204. In certain embodiments, the inner region 204 is substantially parallel to the rim 206. The inner region 204 may be slightly lower than an upper surface 210 of the rim 206, forming a recessed pocket 212 sized to receive a substrate. Susceptors, such as the susceptor 106, are generally sized so that a substrate to be processed on the susceptor fits snugly within a rim, such as the rim 206 of the susceptor 106. For example, for a 300 mm substrate, the diameter of the inner region 204 may be approximately just larger than the diameter of the substrate. The recessed pocket 212 prevents the substrate from slipping off during processing. A step 308 (shown in FIG. 3A ) is formed at the interface between the inner region 204 and the rim 206. In one embodiment, the top surface 216 of the recessed pocket 212 may be about 0.5 mm to about 2.0 mm lower than the top surface 210 of the rim 206. The height of the recessed pocket 212 is variable and is determined by the thickness of the substrate supported by the susceptor 106. As shown in FIG. 2A , the top surface 216 of the recessed pocket 212 is substantially flat relative to the lateral plane (xy plane) of the susceptor 106. Alternatively, it is contemplated that the recessed pocket 212 may be slightly recessed.

[0027]

[0036] The susceptor 106 includes a plurality of bumps 214, e.g., three bumps, extending radially inward from the inner diameter 208 of the rim 206. The bumps 214 help radially position and / or center a substrate (not shown) within the recessed pocket 212 while also reducing the contact surface area between the substrate and the susceptor 106 when the substrate is supported by the susceptor 106. Minimizing and / or reducing the contact surface area between the substrate and the susceptor 106 may be desirable to reduce hot spot effects caused by higher-than-average heat transfer to the substrate at the outer edge. In certain embodiments, the bumps 214 may be shaped and / or aligned to reduce and / or minimize the contact surface area with the outer edge of the substrate. As shown in FIG. 2A, the bumps 214 are rounded when viewed from above. However, it is contemplated that the bumps 214 may have any suitable shape when viewed from above, such as arched, rectangular, square, V-shaped, U-shaped, C-shaped, or a combination thereof. The bumps 214 may be formed of the same material as the susceptor 106 or a different material, such as silicon carbide or graphite coated with silicon carbide or glassy carbon. It is contemplated that the substrate may contact one or more bumps 214 during processing without contacting the inner diameter 208 of the rim 206. In one embodiment, for a 300 mm substrate (150 mm radius), the radius of the recessed pocket 212, measured from the central axis of the susceptor 106 to the inner edge of each bump 214, is slightly larger than the radius of the substrate. Thus, the substrate may move slightly (in the x-y plane) between the bumps 214 relative to the inner diameter 208 of the rim 206. However, precise positioning of the substrate is less important with susceptor embodiments disclosed herein because the effect of substrate position on heat transfer is reduced compared to susceptor designs that have a larger hot spot effect. In other words, substrate position sensitivity is reduced with susceptor embodiments disclosed herein.

[0028]

[0037] The inner region 204 is provided with through holes 202, for example, three through holes, the number of which corresponds to the arrangement of the lift pins 105 (as shown in FIG. 1 ). The through holes 202 allow the lift pins 105 to penetrate the susceptor 106 and raise or lower the substrate from the susceptor 106. The through holes 202 may be arranged at 120 degree intervals in the circumferential direction.

[0029]

[0038] 2B is a partial cross-sectional view of the susceptor 106 taken along section line 2B-2B of FIG. 2A according to one or more embodiments. The cross-sectional view shows one of the bumps 214 extending radially inward from the inner diameter 208 of the rim 206 toward the inner region 204. The lateral dimension of each bump 214, measured radially in the lateral plane (xy-plane) of the susceptor 106, is about 2 mm to about 4 mm, e.g., about 3 mm. The cross-sectional view also shows one of the through-holes 202 oriented perpendicular to the lateral plane (xy-plane) of the susceptor 106 and extending from the backside of the susceptor 106 to the top surface 216 of the recessed pocket 212.

[0030]

[0039] 3A is an enlarged, partial cross-sectional view of the exemplary susceptor 106 of FIG. 1 according to one or more embodiments that can be combined with other embodiments disclosed herein. The susceptor 106 has a pattern 302 formed on the top surface 216 of a recessed pocket 212. While FIG. 3A only shows the profile of the pattern 302 along the x-axis, it is contemplated that the pattern features are arranged in a uniform grid across the entire top surface 216 (shown in the top view of FIG. 3B). In certain embodiments, the pattern 302 has a grid layout including multiple support features, such as truncated pyramidal supports 304, separated by multiple channels, such as V-shaped channels 306. Each support feature has a substrate contact surface 310 defined on the top surface 216. The substrate contact surfaces 310 are substantially flat and parallel to the lateral plane (xy plane) of the susceptor 106. The substrate contact surfaces 310 are coplanar with one another for collectively contacting and supporting the substrate 108. As shown in FIG. 3B, the supports 304 are pyramidal in shape, so that each substrate support 304 has four sidewalls and V-shaped channels oriented 90° apart.

[0031]

[0040] Generally, the pattern is designed to improve the uniformity of heat transfer from the susceptor to the substrate while facilitating the evacuation of exhaust gases, e.g., air, from below the substrate. In certain embodiments, the support features are evenly distributed and the substrate contact surfaces are evenly spaced to provide uniform direct contact between the susceptor and the substrate, resulting in more uniform conductive heat transfer therebetween. In certain embodiments, it may be desirable to increase the number of contact points between the susceptor and the substrate while minimizing the contact surface area. This may be achieved by reducing the size of each substrate contact surface, as described in more detail below.

[0032]

[0041] The number of channels and / or the spacing between the channels can be selected to provide rapid gas evacuation from the recessed pockets. In certain embodiments, uniform channel spacing reduces the overall resistance to gas flow and improves ventilation. Without channels, gas can become trapped, for example, when a substrate is initially positioned on the susceptor, such as during processing. If gas remains trapped, for example, during a sudden reduction in chamber pressure, the trapped gas can expand against the reduced chamber pressure, causing the substrate to lift, shift, or move from its position on the susceptor.

[0033]

[0042] A cross-sectional view of pattern 302 is shown in more detail in FIG. 3C. The particular dimensions of pattern 302 are selected to provide the advantages outlined above. For example, the lateral distance 312 (e.g., pitch) between adjacent support features, such as pyramidal supports 304 of susceptor 106, may be about 0.5 mm to about 3 mm, such as about 1 mm to about 2 mm, such as about 1 mm, for example, about 2 mm. The lateral distance 312 corresponds to the grid size of the pattern measured along the x-axis from center to center of adjacent support features (e.g., a 1 mm grid or a 2 mm grid). The lateral distance 312 along the y-axis may be the same as or different from the lateral distance 312 along the x-axis. In the example illustrated in FIGS. 3B-3C, the lateral distance 312 is the same along both the x-axis and the y-axis. In certain embodiments, the vertical height 314 of a support feature, such as the pyramidal support 304 of the susceptor 106, may be from about 0.25 mm to about 2 mm, for example, about 0.5 mm. The vertical height 314 is measured along the z-axis from the top surface 216 to the bottom surface 316 of the channel. In certain embodiments, it may be desirable to keep the height of the support feature to a minimum to prevent the formation of cold spots between the susceptor and the substrate, while at the same time increasing the height of the support feature to improve gas flow.

[0034]

[0043] In certain embodiments, the lateral width 318 of a channel, such as the V-shaped channel 306 of the susceptor 106, may be from about 0.5 mm to about 10 mm. The lateral width 318 corresponds to the width of the bottom surface 316 of each channel measured along the x-axis or y-axis between adjacent support features. In certain embodiments, the angle 320 of a channel, such as the V-shaped channel 306 of the susceptor 106, measured between the sidewalls 322 of adjacent support features may be from about 5° to about 60°. The angle 320 may be selected to balance the reflection of radiant heat from the lamps 102 for better temperature uniformity. In other words, because the distribution of radiation reflected and / or emitted from the inner region 204 of the susceptor 106 is directional, the angle 320 may be determined so that the radiative heat transfer from the susceptor 106 to the substrate 108 becomes increasingly isotropic (i.e., has the same value when measured in different directions). It will be appreciated that the above dimensions also define the size of each substrate contact surface 310 along the top surface 216. It may be desirable to reduce the contact surface area between the substrate contact surfaces 310 and the substrate 108 so that a higher proportion of heat transfer is radiative, resulting in improved temperature control and improved thermal processing and / or deposition on the substrate. In certain embodiments, the ratio of the combined surface area of ​​all of the substrate contact surfaces 310 to the total surface area of ​​the recessed pockets 212 inside the inner diameter 208 of the rim 206, as measured in the x-y plane, is between about 0.5% and about 5%, e.g., between about 0.5% and about 3%, e.g., between about 1% and about 2%. Beneficially, the ultra-low surface area ratio of the substrate contact surfaces 310, e.g., about 5% or less, reduces the proportion of conductive to radiative heat transfer from the susceptor 106 to the substrate 108, improving temperature uniformity and resulting in better processing results. Because the ratio of conductive to radiative heat transfer is positively correlated with the surface area ratio described above, further reducing the surface area ratio to further reduce the portion of conductive heat transfer can positively impact processing results. Furthermore, susceptor embodiments designed with ultra-low surface area ratios are beneficial for providing adequate mechanical support to the substrate 108 to prevent warping, while also increasing randomly oriented radiative heat dissipation and reducing temperature variations between adjacent support features based on a precisely determined pitch between adjacent support features.

[0035]

[0044] FIG. 4 is a partial cross-sectional view of a susceptor 400 that can be used in place of the susceptor 106 of the process chamber 100 of FIG. 1 according to one or more embodiments that can be combined with other embodiments disclosed herein. In FIG. 4, the supports 404 and channels 406 of the pattern 402 are rounded or curved. In some other embodiments (not shown), it is contemplated that the supports 404 may be any curved shape, such as a frustoconical, truncated sphere, or elliptical shape, or a combination thereof. The curved supports 404 have smooth sidewalls 422, which result in more randomly oriented heat radiation compared to sidewalls with flat surfaces. Therefore, the curved supports 404 can further improve heat transfer uniformity beyond what has been discussed thus far. The curved substrate contact surface 410 of the pattern 402 reduces the total contact surface area between the substrate contact surface 410 and the substrate 108 compared to the flat substrate contact surface 310 of the pattern 302. The reduced contact surface area of ​​the susceptor 400 compared to other susceptor embodiments disclosed herein may reduce conductive heat transfer and further improve thermal uniformity during substrate processing. In certain embodiments, the total contact surface area between the substrate contact surface 410 and the substrate 108 (measured as a percentage of the surface area in the xy plane of the recessed pocket 212 inside the inner diameter 208 of the rim 206) is from about 0.1% to about 5%, such as from about 0.1% to about 3%, e.g., from about 0.5% to about 2%.

[0036]

[0045] FIG. 5A is a partial cross-sectional view of a susceptor 500 that can be used in place of the susceptor 106 in the process chamber 100 of FIG. 1 according to one or more embodiments that can be combined with other embodiments disclosed herein. FIG. 5B is a top view of a portion of the susceptor 500. In FIGS. 5A-5B, the supports 504 and channels 506 of the pattern 502 are hexagonal when viewed from above. The substrate contact surfaces 510 of the pattern 502, like the substrate contact surfaces 310 of the pattern 302, are substantially flat and parallel to the lateral plane (xy plane) of the susceptor 500 and substantially parallel to the bottom surfaces 516 of the channels 506. The substrate contact surfaces 510 are also coplanar with one another to collectively contact and support the substrate 108. However, in contrast to the pattern 302, each support 504 of the pattern 502 has six sidewalls 522 instead of four, increasing the associated radiative surface area. The increased radiative surface area of ​​the hexagonal supports 504 can improve heat transfer uniformity compared to pyramidal supports 304 having the same contact surface area. In contrast to pattern 302, the channels 506 are oriented at 60° intervals rather than 90° intervals. In certain embodiments, the total contact surface area between the substrate contact surface 410 and the substrate 108 (measured as a percentage of the surface area in the x-y plane of the recessed pocket 212 inside the inner diameter 208 of the rim 206) is about 0.1% to about 5%, e.g., about 0.1% to about 3%, e.g., about 0.5% to about 2%. In some other embodiments (not shown), it is contemplated that the support features may be any suitable shape when viewed from above, such as rectangular, diamond, square, triangular, rounded, hexagonal, other shapes, or combinations thereof. In certain embodiments that can be combined with other embodiments, the support features may be tetrahedral pyramids, hemispheres, other rounded shapes, other three-dimensional shapes, or combinations thereof. Any of the support features described above may have truncated ends to form flat and parallel support surfaces across the support feature.

[0037]

[0046] The susceptor embodiments described herein enable more uniform temperature control of a substrate during thermal processes such as epitaxy. Temperature control is improved near the outer edge of the substrate by reducing the surface area of ​​the outer edge that contacts the susceptor, thereby reducing outer edge thermal peaks and the amount of conductive heat transferred from the susceptor to the substrate at the outer edge. The embodiments disclosed herein reduce and / or minimize the contact surface area between the susceptor and the outer edge of the substrate by providing a very small number of centering bumps, e.g., three bumps, around the circumference of the susceptor.

[0038]

[0047] Generally, flat pocket susceptors increase heat transfer by conduction compared to susceptors that support the substrate only near the outer edges. Because conductive heat transfer between the susceptor and the substrate is more difficult to control than radiative heat transfer, it is desirable to reduce and / or minimize direct contact between the susceptor and the backside of the substrate. Susceptor embodiments disclosed herein reduce direct contact between the susceptor and the backside of the substrate by providing a patterned surface with a plurality of support features. Direct contact can be reduced based on the design of the pattern, including the layout and dimensions of the support features. By reducing the surface area of ​​the substrate in contact with the susceptor, a higher proportion of heat transfer is radiative, resulting in improved temperature control and improved thermal processing and / or deposition on the substrate. Susceptor embodiments disclosed herein also improve gas evacuation by including regularly spaced ventilation channels within the recessed pocket of the susceptor.

[0039] Exemplary Method for Manufacturing a Susceptor

[0048] 6 illustrates a method 600 for manufacturing a susceptor according to one or more embodiments that may be combined with other embodiments disclosed herein. In step 602, a susceptor including a recessed pocket is provided, such as susceptor 106 having recessed pocket 212 shown in FIGS. 2A-2B, or any other suitable susceptor.

[0040]

[0049] In step 604, a plurality of channels are formed in the upper surface of the recessed pocket, the plurality of channels having a plurality of support features formed therebetween. For example, in the embodiment shown in FIGS. 3A-3C , a cutting tool (e.g., a V-shaped tool) can be used to form a first plurality of cuts spaced apart by a lateral distance 312 (e.g., a lateral width) in the x-direction. The susceptor 106 can then be rotated 90° relative to the cutting tool, and the cutting tool can be used to form a second plurality of cuts spaced apart by the lateral distance 312, substantially perpendicular to the first plurality of cuts (i.e., in the y-direction). In the embodiment shown in FIG. 4 , other tools or more complex machining methods can be used to form the pattern 402 having the curved supports 404. In the embodiment shown in FIGS. 5A-5B , the susceptor 500 can be rotated 60° before forming the second plurality of cuts, and another 60° before forming the third plurality of cuts.

[0041]

[0050] In step 606, the top surface of the recessed pocket is recessed to reduce the height of the support features to match the final design height minus the coating thickness. In step 608, the support features around the outer edges of the recessed pocket can optionally be removed. In certain embodiments, the support features are machined using a flat mill bit. In step 610, a coating is applied to the top surface of the recessed pocket. In certain embodiments, the coating comprises SiC deposited by chemical vapor deposition (CVD). The susceptor is fabricated by applying the coating so that the pattern dimensions match the final design dimensions, such as those outlined above with respect to FIG. 3C.

[0042]

[0051] Although the above embodiments have been described using circular geometries (e.g., circular plates, rims, etc.) used on semiconductor "substrates," the disclosed embodiments can be adapted to conform to different geometries.

[0043]

[0052] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof as determined by the following claims.

Claims

1. A method for manufacturing a susceptor, comprising: forming a plurality of channels in a top surface of the recessed pocket of the susceptor, the plurality of channels having a plurality of support features formed therebetween, and forming the plurality of channels and the plurality of support features includes: forming a first plurality of cuts in a first direction with a cutting tool; rotating the susceptor relative to the cutting tool by a first angle; forming a second plurality of cuts in a second direction with the cutting tool, the second direction being spaced apart from the first direction by the first angle; and forming a plurality of channels in a top surface of the recessed pocket of the susceptor, recessing an upper surface of the recessed pocket; A method comprising:

2. The method of claim 1 , wherein the first angle is approximately 90° and the support feature is pyramidal.

3. after forming the second plurality of cuts, rotating the susceptor relative to the cutting tool through a second angle substantially equal to the first angle; forming a third plurality of cuts in a third direction spaced apart from the second direction by the second angle using the cutting tool; The method of claim 1 further comprising:

4. The method of claim 3 , wherein the first and second angles are approximately 60° and the support feature is hexagonal in top view.

5. The method of claim 1 , further comprising removing the support features around an outer edge of the recessed pocket.

6. The method of claim 1 further comprising applying a coating to a top surface of the recessed pocket.

7. 2. The method of claim 1, wherein each of the first plurality of cuts in the first direction and each of the second plurality of cuts in the second direction are spaced apart by a distance of about 0.5 mm to about 3 mm.

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