Edge susceptor design to promote uniform film deposition

Abstract

The present disclosure relates to a processing chamber and methods using the same. A susceptor comprises a base material having a first surface and a second surface, a depression being formed on an edge of the first surface. One or more support blocks are disposed in the depression. A metal tile has a top surface and a bottom surface opposite the top surface, the metal tile disposed on the one or more support blocks. A gap is defined between the bottom surface of the metal tile, the one or more support blocks, and the base material.

Description

EDGE SUSCEPTOR DESIGN TO PROMOTE UNIFORM FILM DEPOSITIONBACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to processing chambers and methods using the same. More specifically, embodiments described herein relate to susceptors for plasma enhanced chemical vapor deposition chambers.Description of the Related Art

[0002] Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates, such as semiconductor substrates, solar panel substrates, organic light emitting diode (OLED) substrates and liquid crystal display (LCD) substrates. These substrates can be fairly large and may be substantially rectangular. PECVD is generally accomplished by introducing precursor gases into a vacuum chamber having the substrate disposed on a substrate support. The precursor gases are delivered to the substrate through a gas distribution assembly in the chamber.

[0003] During plasma enhanced chemical vapor deposition, the electricity needed to form the plasma may cause arcing near the edges of the substrate on the susceptor due to the design of the susceptor. Also, impedance deviations caused by the susceptor may cause deposition film thickness reduction in the processed substrate. Accordingly, what is needed in the art is improved susceptor designs.SUMMARY

[0004] In one embodiment, the present disclosure provides a susceptor. The susceptor comprises a base material having a first surface and a second surface, a depression being formed on an edge of the first surface. One or more support blocks are disposed in the depression. A metal tile has a top surface and a bottom surface opposite the top surface, the metal tile disposed on the one or more support blocks. A gap is defined between the bottom surface of the metal tile, the one or more support blocks, and the base material.

[0005] In another embodiment, the present disclosure provides a susceptor. The susceptor comprises a base material having a first surface and a second surface, a depression being formed on an edge of the first surface. The susceptor further comprises a ceramic shim disposed on the base material in the depression and a metal tile having a top surface and a bottom surface opposite the top surface. The metal tile is disposed on the ceramic shim.

[0006] In yet another embodiment, the present disclosure provides a method of processing a substrate. The method comprises placing a substrate on a susceptor in a processing chamber. The susceptor comprises a base material having a first surface and a second surface, a depression being formed on an edge of the first surface. One or more support blocks are disposed in the depression. The susceptor further comprises a metal tile having a top surface and a bottom surface opposite the top surface, the metal tile disposed on the one or more support blocks. The method further comprises producing a plasma above the substrate and depositing a material layer on the substrate with the plasma.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, may admit to other equally effective embodiments.

[0008] Figure 1 is a schematic cross sectional view of a processing chamber according to one or more embodiments.

[0009] Figure 2A is a cross-sectional view of an edge portion of the susceptor including a metal tile according to one or more embodiments.

[0010] Figure 2B is a cross-sectional view of an edge portion of the susceptor including a metal tile and a ceramic shim according to one or more embodiments.

[0011] Figure 3 is an isometric view of the susceptor according to one or more embodiments.

[0012] Figure 4 is a flow diagram of a method of performing a chemical vapor deposition (CVD) process on a substrate according to one or more embodiments.

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

[0014] Embodiments of the present disclosure generally relate to susceptors for processing deposition chambers and methods using the same. More specifically, embodiments described herein relate to susceptors for plasma enhanced chemical vapor deposition chambers having a different material on the surface of the edge of the susceptor. Conventional susceptors use a ceramic tile to prevent arcing. However, conventional susceptors may cause non-uniform plasma strength directly above the susceptors, leading to mura (e.g., uneven material distribution) on a substrate. The non-uniform plasma strength is caused by an impedance deviation around the edge of the susceptor. The impedance deviation is caused by the ceramic tile in conventional susceptors. Replacing the ceramic tile with a metal tile prevents arcing while not causing non-uniform plasma strength. The material of the metal tile and other design considerations removes the impedance deviation at the edge of the substrate, leading to uniform plasma strength and even material distribution.

[0015] Figure 1 is a schematic cross sectional view of a processing chamber 100, such as a plasma enhanced chemical vapor deposition (PECVD) chamber according to one or more embodiments. The processing chamber 100 may be used to deposit one or more films onto a substrate 140. The processing chamber 100 may be used to process one or more substrates 140, for example, semiconductor substrates, flat panel display substrates, and solar panel substrates, among others. Although the processing chamber 100 described herein is provided as an example of a chamber with which the susceptors can be implemented, in various embodiments, the susceptor can be implemented with other types of processing chambers.

[0016] The processing chamber 100 generally includes sidewalls 102, a bottom 104 and a showerhead 110 (e.g., diffuser) that define a processing volume 106. A susceptor 130 (e.g., substrate support, pedestal) is disposed in the processing volume 106. The susceptor 130 includes a substrate receiving surface 132 for supporting the substrate 140. The process volume 106 is accessed through an opening 108 formed through the sidewalls 102 such that the substrate 140 may be transferred in and out of the processing chamber 100 when the susceptor 130 is in the lowered position. One or more stems 134 may be coupled to a lift system 136 to raise and lower the susceptor 130. As shown in Figure 1 , the substrate 140 is in a lowered position where the substrate 140 can be transferring into and out of the processing chamber 100. The substrate 140 can be elevated to a processing position, not shown, for processing. The spacing between the top surface of the substrate 140 disposed on the substrate receiving surface 132 and the showerhead 110 may be between about 400 mil and about 1 ,200 mil when the susceptor 130 is raised to the processing position. In some embodiments, the spacing may be between about 400 mil and about 800 mil.

[0017] Lift pins 138 are moveably disposed through the susceptor 130 to space the substrate 140 from the substrate receiving surface 132 and facilitate robotic transfer of the substrate. The susceptor 130 may also include radio frequency (RF) return straps 131 to provide a RF return path at the periphery of the susceptor 130.

[0018] The showerhead 110 may be coupled to a backing plate 112 at a periphery thereof by a suspension 114. The showerhead 110 may also be coupled to the backing plate 112 by one or more coupling supports 160 to help mitigate sag and / or control the straightness / curvature of the showerhead 110. The sidewalls 102, the bottom 104, and the backing plate 112 define a chamber body.

[0019] A gas source 120 may be fluidly coupled to the backing plate 112 to provide processing gas through a gas outlet 142 in the backing plate 112 and through gas passages 111 in the showerhead 110 to the substrate 140 disposed on the substrate receiving surface 132. The gas may flow from the gas source 120 through the showerhead 110. A vacuum pump 109 may be coupled to the processing chamber 100 to control the pressure within the process volume 106. An RF power source 122 is coupled to the backing plate 112 and / or to the showerhead 110 to provide RF power to the showerhead 110. The RF power creates an electric field between theshowerhead 110 and the susceptor 130 so that a plasma may be generated from the gases between the showerhead 110 and the susceptor 130. Various frequencies may be used, such as a frequency between about 0.3 MHz and about 200 MHz. In one embodiment, the RF power source is provided at a frequency of about 12 MHz to about 15 MHz.

[0020] A frame 133 may be placed adjacent to the periphery region of the substrate 140, either in contact with or spaced from the substrate 140. In some embodiments, the frame 133 may be configured to be disposed under the substrate 140. In other embodiments, the frame 133 may be configured to be disposed over the substrate 140. The frame 133 may be a non-contact frame (e.g., the frame is not in contact with a substrate when positioned on the susceptor 130), a floating frame, a removable frame, a confinement ring, a flow control structure, or other suitable structure positionable adjacent the periphery of the substrate 140. The frame does not cover a surface of the substrate 140 to provide for full plasma coverage on the substrate 140, leading to a full surface deposition film on the substrate 140. The frame 133 confines the plasma in the process chamber 100.

[0021] The processing chamber 100 includes a remote plasma source 124. In some embodiments, multiple remote plasma sources are used, such as five or three. The remote plasma source 124, such as an inductively coupled remote plasma source, may also be coupled between the gas source 120 and the backing plate 112 at a central location of the backing plate. Between processing substrates, a cleaning gas may be provided to the remote plasma sources 124 so that a remote plasma is generated and provided into the processing volume 106 to clean chamber components. The cleaning gas may be further excited while in the processing volume 106 by power applied to the showerhead 110 from the RF power source 122. The gas source 120, remote plasma source 124, RF power source 122, and the showerhead 110 form a plasma system that develops the plasma described above.

[0022] Figure 2A is a cross-sectional view of an edge portion 200A of the susceptor 130 according to one or more embodiments. The edge portion 200A includes a base material 201 , a plurality of support blocks 203, a gap 205, a metal tile 207, and the frame 133. The base material 201 includes a large portion of the susceptor 130. The base material 201 has a first surface 211 and a second surface 213. The first surface211 is opposite the second surface 213. The second surface 213 is flat. The second surface 213 connects to the stem 134, as shown in Figure 1 . The first surface 211 is configured to support the substrate 140. The first surface 211 is a flat surface with a depression 215 along the edge portion 200A of the susceptor 130. The base material 201 includes a metal or a similar conductive material.

[0023] The plurality of support blocks 203 are disposed in the first surface 211 in the depression 215. The plurality of support blocks 203 are configured to support the metal tile 207 and the frame 133. In Figure 2A, three support blocks 203 are shown. A first support block 203A supports the frame 133. The metal tile 207 is disposed on a second support block 203B and a third support block 203C. The support blocks 203 include a ceramic material, such as aluminum oxide, aluminum nitride or a similar material. The metal tile 207 has a first surface 216 (e.g. top surface) and a second surface 217 (e.g. bottom surface). The first surface 216 is opposite the second surface 217. The second surface 217 of the metal tile 207, the first surface 211 in the depression 215, the second support block 203B, and the third support block 203C define the gap 205. In the edge portion 200A shown in Figure 2A, the gap 205 contains air. The gap 205 separates the metal tile 207 from the base material 201 . In various embodiments, the gap 205 has a thickness of less than about 40 mils, such as less than about 30 mils, such as less than about 20 mils, such as less than about 10 mils. The frame 133 extends from the endpoint of the susceptor 130 over a portion of the metal tile 207. A gap 206 exists between the frame 133 and the metal tile 207. The gap 206 is less than about 40 mils, such as less than about 30 mils, such as less than about 20 mils, such as less than about 10 mils. The frame 133 is spaced a distance 210 from the substrate 140. The distance 210 allows full surface deposition of a film to be performed on the substrate 140 when the substrate 140 is processed. The frame 133 includes a coated conductive material or a ceramic.

[0024] The first surface 216 of the metal tile 207 is substantially parallel to the first surface 211 of base material 201 , offset by a distance 218. In various embodiments, the distance 218 is less than about 10 mils. The distance 218 prevents the substrate 140 from contacting the metal tile 207 during processing. The distance 218 provides an air gap 220 between the substrate 140 and the metal tile 207. The metal tile 207 is positioned above and does not contact the base material 201 or the substrate 140.The first surface 216 of the metal tile 207 does not contact the substrate 140, and the second surface 217 of the metal tile 207 does not contact the base material 201. A side face 221 of the metal tile 207 is separated by a distance 225 from a sidewall 223 of the base material 201 that further defines the depression 215. In various embodiments, the distance 225 is less than about 10 mils. The metal tile 207 includes a coated conductive material. The coating is an insulating coating. The material of the metal tile 207 is selected to prevent arcing during forming the plasma with the RF. Conventional susceptors use a ceramic tile to prevent arcing. However, conventional susceptors may cause non-uniform plasma strength directly above the susceptors, leading to mura (e.g., uneven material distribution) on the substrate 140. The material of the metal tile 207 is also selected to promote uniform plasma strength across the substrate 140.

[0025] Figure 2B is a cross-sectional view of an edge portion 200B of the susceptor 130 according to one or more embodiments. The susceptor 130 depicted in Figure 2B is similar to the susceptor 130 depicted in Figure 2A. As shown, the gap 205 of the edge portion 200B is filled with a ceramic shim 219. The third support block 203C is not present, causing the ceramic shim 219 to extend from the first support block 203A to the second support block 203B.

[0026] The ceramic shim 219 includes a ceramic material, such as aluminum oxide, aluminum nitride or a similar material. In various embodiments, the ceramic shim 219 has a thickness of about 10 mils to about 100 mils, such as about 20 mils to about 80 mils, such as about 30 mils to about 50 mils, such as about 40 mils.

[0027] The edge portions 200A and 200B are designed to avoid arcing of the electrical currents used to form the plasma. The edge portions 200A and 200B have multiple parts (the metal tile 207, the support blocks 203, the air gap 220, and the gap 205) to avoid arcing issue. Arcing may occur if the base material 201 contacts the plasma. Around the center of the susceptor 130, the base material 201 is covered by the substrate 140. The substrate 140 does not extend the entire length of the susceptor 130. The edges of the susceptor 130 are exposed. At the edges of the susceptor 130 (e.g., as shown in Figures 2A and 2B), the depression 215 in the first surface 211 of the base material 201 is filled with the metal tile 207. The metal tile 207 is exposed to the plasma instead of the base material 201 . Because the metaltile 207 is anodized, the layer of oxide formed around the metal tile 207 reduces or eliminates the incidence of arcing during plasma generation. Additionally, in various embodiments, the plurality of support blocks are precisely machined to avoid direct contact between the metal tile 207 and the base material 201 , further reducing or eliminating the incidence of arcing.

[0028] By contrast, conventional susceptors may implement a ceramic tile at the edge of the susceptor to avoid arcing. However, the ceramic tile may cause film thickness reductions on the edge of the substrate 140. The film thickness reduction is caused by plasma non-uniformity above the ceramic tile which is present at the edges of the substrate 140. Since the plasma is formed by RF power, the impedance of the susceptor 130 may affect the plasma uniformity. The impedance at a point along the susceptor 130 is dependent on the capacitance of the susceptor 130 at that point. The ceramic tile causes an impedance deviation directly above the ceramic tile. Modifying the susceptor 130 by replacing the ceramic tile with the metal tile 207 improves the impedance deviation at the edges of the substrate 140. Therefore, the metal tile 207 improves the film thickness uniformity on the edges of the substrate 140.

[0029] The impedance is inversely related to the plasma power along the susceptor 130. As a result, reducing the impedance at a portion of the susceptor 130 increases the plasma power above that portion. The impedance of a particular portion of the susceptor 130 is inversely related to the capacitance in that portion of the susceptor 130. The materials, the thicknesses, and orientations of the metal tile 207, the support blocks 203, the gap 205, and the base material 201 described above are selected to prevent the arcing around the edge of the substrate 140. The materials and thicknesses relate to the capacitance of each layer. The metal tile 207 is selected over a ceramic tile due to better capacitance properties to lower the impedance at the edge of the susceptor leading to the beneficial film thickness properties at the edge of the substrate 140.

[0030] In Figure 2A, a total capacitance at the edge 200A is calculated based on the capacitance of each layer. As stated above, the capacitance is calculated by the properties including the material and thickness of layers in the edge 200A of the susceptor 130. These layers include the air gap 220, metal tile 207, the gap 205, the second support block 203B and the base material 201 . Also, the substrate 140 affectsthe capacitance of the edge 200A. The total capacitance at the edge 200A is increased by the orientation of the layers. The total capacitance may be increased by greater than about 75%, such as 90% to about 125%, such as about 114% compared to susceptors having the ceramic tile at the edge. The increase in the total capacitance reduces the impedance. The impedance may be reduced to by greater than about 30%, such as about 40% to about 65%, such as about 53%, as compared to susceptors having the ceramic tile at the edge.

[0031] In Figure 2B, a total capacitance at the edge 200B is calculated based on the capacitance of each layer. As stated above, the capacitance is calculated based on properties including the material and thickness of layers in the edge 200B of the susceptor 130. These layers include the air gap 220, metal tile 207, the ceramic shim 219, and the base material 201 . Also, the substrate 140 affects the capacitance of the edge 200B. The total capacitance at the edge 200B is increased by the orientation of the layers. The total capacitance may be increased by greater than about 40%, such as 50% to about 60%, such as about 61 %, as compared to susceptors having the ceramic tile at the edge. The increase in the total capacitance reduces the impedance. The impedance may be reduced to by greater than about 20%, such as about 30% to about 50%, such as about 38%, as compared to susceptors having the ceramic tile at the edge.

[0032] Returning to the impedance effect on the plasma strength, the plasma strength is caused by the strength of the electric field that creates the plasma. The strength of the electric field causes the beneficial uniformity of the deposited film on the substrate 140. The reduction in the impedance along the edges 200A and 200B of the susceptor 130 causes a stronger electric field at the edge of the substrate 140. The strength of electric field is increased at a top sheath and a bottom sheath of the plasma formed in the processing volume 106. The top sheath is near the showerhead 110 while the bottom sheath is near the surface of the substrate 140. For the top sheath, the strength of electric field may be increased at the top sheath of the edge 200A by about 30% to about 70%, such as about 50%, as compared to susceptors having the ceramic tile at the edge. The strength of electric field may be increased at the top sheath of the edge 200B by about 15% to about 50%, such as about 33%, as compared to susceptors having the ceramic tile at the edge. Turning to the bottomsheath, the strength of electric field may be increased at the bottom sheath of the edge 200A and 200B by about 20% to about 50%, such as about 37%, as compared to susceptors having the ceramic tile at the edge. Increasing the strength of electric field at the top and the bottom sheaths increases the power and process gas dissociation at the edges 200A and 200B of the susceptor 130 when forming the plasma. The higher power and process gas dissociation leads to an increase in the deposition rate at the edge 200A and 200B by the plasma. This increase in the deposition rate at the edge 200A and 200B leads to more uniform deposition across the substrate 140 reducing the mura on the edge of the substrate 140.

[0033] The material of the metal tile 207 provides uniform temperature with the first surface 211 of the base material 201 during the deposition process. The uniform temperature across the susceptor 130 leads to uniform deposition film thickness on the substrate 140. The material of the metal tile 207 also provides uniform RF coupling when forming the plasma.

[0034] Figure 3A is an isometric view of the susceptor 130 according to one or more embodiments. Figure 3A illustrates the susceptor 130 shown in Figure 2B. Therefore, Figure 3A illustrates a plurality of the metal tiles 207 disposed along edges of the susceptor 130. The metal tiles are connected together by a plurality of connectors 301. In various embodiments, the connectors 301 are substantially flush with the metal tiles 207. The distance 218 exists between the substrate 140 and a top surface of the connectors 301 . The connectors 301 include anodized aluminum or a similar anodized conductive material. The susceptor 130 is shown to have rectangular shape. The first surface 211 and second surface 213 of the susceptor have the rectangular shape. In other embodiments, the susceptor may have different shapes such as circular shape.

[0035] Figure 4 is a flow diagram of a method 400 of performing a chemical vapor deposition (CVD) process on the substrate 140 according to one or more embodiments. At operation 401 , the substrate 140 is placed on the susceptor 130. The substrate 140 is placed on the susceptor, as described in Figure 1. In some embodiments, the susceptor 130 includes the edge portion 200A described in Figure 2A. In other embodiments, the susceptor 130 includes the edge portion 200B described in Figure 2B. The substrate 140 is positioned such that an edge portion ofthe substrate extends from the substrate receiving surface 132 to the metal tile 207. The substrate 140 is separated by distance 218 from the first surface 216 of the metal tile 207.

[0036] At operation 403, a plasma is produced from a gas (e.g., disposed above the substrate 140). As described above, the RF power creates an electric field between the showerhead 110 and the susceptor 130 when forming the plasma from a gas flowed into the process volume 106. The metal tile 207 is positioned in the susceptor 130 to improve the uniformity with which the plasma is distributed along an edge of the substrate relative to, for example, a center of the substrate.

[0037] At operation 405, a material layer is deposited on the substrate 140. In various embodiments, the material is deposited at a constant rate such that a time during which the plasma is active in the chamber directly relates to the thickness of the material layer. Due to the uniformity of the plasma, the material layer has a uniform thickness across the substrate 140.

[0038] In summation, embodiments of the present disclosure generally relate to susceptors for chemical vapor deposition chambers and methods using the same. More specifically, embodiments described herein relate to susceptors for plasma enhanced chemical vapor deposition chambers having a different material on the surface of the edge of the susceptor. Benefits of the metal tile include uniform plasma distribution across the substrate, reducing or eliminating mura and increasing film thickness uniformity near the edges of the substrate. The metal tile also reduces the chance of arcing at the edge of the susceptor. By increasing the film thickness uniformity on the edges of the substrate, the effective area of the substrate is increased by the susceptor.

[0039] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:1 . A susceptor, comprising: a base material having a first surface and a second surface, a depression being formed on an edge of the first surface; one or more support blocks disposed in the depression; and a metal tile having a top surface and a bottom surface opposite the top surface, the metal tile disposed on the one or more support blocks, wherein a gap is defined between the bottom surface of the metal tile, the one or more support blocks, and the base material.

2. The susceptor of claim 1 , wherein the metal tile comprises a coated conductive material.

3. The susceptor of claim 1 , wherein the metal tile has a top surface offset a distance from the first surface of the base material.

4. The susceptor of claim 1 , wherein the gap contains air and has a thickness of less than about 10 mils.

5. The susceptor of claim 1 , wherein the one or more support blocks comprise aluminum oxide or aluminum nitride.

6. The susceptor of claim 1 , wherein the base material comprises a conductive material.

7. The susceptor of claim 1 , further comprising a frame disposed on the metal tile, the frame being disposed around an edge of the susceptor.

8. The susceptor of claim 1 , wherein the first surface has a rectangular shape.

9. A susceptor, comprising:a base material having a first surface and a second surface, a depression being formed on an edge of the first surface; a ceramic shim disposed on the base material in the depression; and a metal tile having a top surface and a bottom surface opposite the top surface, the metal tile disposed on the ceramic shim.

10. The susceptor of claim 9, wherein the metal tile comprises a coated conductive material.11 . The susceptor of claim 9, wherein the metal tile has a top surface offset a distance from the first surface of the base material.

12. The susceptor of claim 9, wherein the ceramic shim comprises aluminum oxide or aluminum nitride.

13. The susceptor of claim 9, wherein the base material comprises a conductive material.

14. The susceptor of claim 9, further comprising a frame disposed on the metal tile, the frame being disposed around an edge of the susceptor.

15. The susceptor of claim 9, wherein the first surface has a rectangular shape.

16. A method of processing a substrate, comprising: placing a substrate on a susceptor in a processing chamber, the susceptor, comprising: a base material having a first surface and a second surface, a depression being formed on an edge of the first surface; one or more support blocks disposed in the depression; and a metal tile having a top surface and a bottom surface opposite the top surface, the metal tile disposed on the one or more support blocks; producing a plasma above the substrate; and depositing a material layer on the substrate with the plasma.

17. The method of claim 16, wherein the one or more support blocks form a gap with the metal tile, the gap containing air and having a thickness of less than about 10 mils.

18. The method of claim 17, wherein a capacitance of the metal tile, the gap, the one or more support blocks, and the base material on the edge of the first surface causes a substantially uniform plasma strength to be formed along the edge of the substrate.

19. The method of claim 16, wherein the one or more support blocks comprises a ceramic shim.

20. The method of claim 19, wherein a capacitance of the metal tile, the ceramic shim, and the base material on the edge of the first surface causes a substantially uniform plasma strength to be formed along the edge of the substrate.

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