Spray head with adjustable gas outlet

Abstract

A deposition tool includes: a process chamber; a deposition susceptor for supporting a substrate within the processing chamber and for depositing a material layer on a first surface of the substrate; and a showerhead assembly having a panel opposite the second surface of the substrate, the panel of the showerhead having a plurality of adjustable gas outlets arranged to distribute a purge gas proximate the second surface of the substrate when the material layer is being deposited on the first surface of the substrate through the deposition susceptor.

Description

This application is a divisional application of the application with application number 202080012187.0, application date January 15, 2020, and invention name “Nozzle with adjustable gas outlet”. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Patent Application No. 62 / 799,188, filed on January 31, 2019, which is incorporated herein by reference for all purposes. Background Art

[0002] The present invention relates to deposition tools, and more particularly to showerheads having adjustable gas outlets for controlling the flow rate of a sweep gas to prevent concomitant deposition on an opposing surface of a substrate during deposition on one surface of the substrate.

[0003] Deposition tools are commonly used to deposit various thin films onto substrate surfaces, such as semiconductor wafers, flat panel displays, and / or photovoltaic devices, which are collectively referred to as "substrates" hereinafter.

[0004] In the semiconductor industry, thin films commonly deposited on substrates include, but are not limited to, polysilicon, silicon nitride, silicon dioxide, certain metals such as tungsten, nickel, aluminum, etc. These layers are typically formed on the device surface of the substrate and then patterned to form integrated circuits.

[0005] The deposition of one or more layers usually causes mechanical stresses to act on the substrate. These mechanical stresses generally lead to warping, which means that the substrate is no longer flat. Warped substrates are problematic. For non-flat substrates, misalignment may occur during patterning of the layers, which in turn may lead to defects and lower processing yields.

[0006] To counteract warping, it is known to deposit one or more layers of material on the backside surface opposite the device side of the substrate. These backside layers provide tensile and / or compressive strength and stiffness to the substrate at least at temperatures of about 400°C or below. However, during certain processing steps, such as annealing or high temperature deposition, the substrate is exposed to very high temperatures, typically in the range of 800°C or higher. At these higher temperatures, the backside layers tend to "relax" and lose their tensile and / or compressive strength and stiffness. As a result, the substrate will often experience warping at high temperatures, which primarily results in the backside layers not being able to play a role in preventing warping.

[0007] A known solution to the warpage problem at high temperatures is to perform the backside deposition at an elevated temperature, for example in the range of 500° C. to 600° C. When the backside deposition is performed in this elevated temperature range, the mechanical properties of the backside layer remain largely unchanged. In other words, the extent of substrate warpage is significantly reduced even at elevated temperatures.

[0008] Regardless of the temperature, a byproduct of backside deposition is that the deposited material may wrap around and concomitantly deposit on the device side of the substrate. This concomitant deposition is problematic because it may adversely affect the integrated circuits fabricated on the device side of the substrate. Summary of the invention

[0009] A deposition tool is disclosed that includes a showerhead having an adjustable gas outlet for controlling the flow rate of a sweep gas to prevent concomitant deposition on an opposing surface of a substrate during deposition on one surface of the substrate.

[0010] The deposition tool includes: a processing chamber; a deposition base, which is used to support the substrate in the processing chamber and to deposit a material film on the first surface of the substrate. The deposition tool also includes a showerhead assembly, which has a panel relative to the second surface of the substrate. The panel has a plurality of adjustable gas outlets, which are arranged to distribute a purge gas near the second surface of the substrate when the material film is being deposited on the first surface of the substrate. Any backside deposition material surrounding the substrate and concomitantly entering the space above the device side of the substrate is removed by the flow of the purge gas. Therefore, concomitant film deposition on the device surface of the substrate is reduced or completely eliminated.

[0011] The adjustable gas outlets are each arranged to accommodate a removable plug-in. The gas outlets can each be configured using a different plug-in. For example, plug-ins with different numbers of holes, different hole patterns, different hole diameters, or even plug-ins with no holes can be used. By selecting different plug-ins, the flow of the purge gas can be controlled to meet tool specifications and operating conditions. In addition, the plug-ins used for a given showerhead assembly do not have to be all the same. For example, each plug-in can have more or fewer holes, different hole patterns, holes with different diameters, etc. Therefore, the local flow of the purge gas can be controlled separately at each plug-in position directly above the first surface of the substrate. Because the plug-in is removable, it can be changed when needed, including when the deposition tool is on site. Therefore, customers and end users can configure the showerhead assembly according to needs or as operating parameters change. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present application and its advantages may be best understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a perspective cross-sectional view of a deposition tool including a showerhead with adjustable gas outlets according to a non-exclusive embodiment of the present invention.

[0014] Figure 2 is a cross-sectional view of a showerhead assembly with an adjustable gas outlet according to a non-exclusive embodiment of the present invention.

[0015] Figure 3A-3B is a diagram of a faceplate and adjustable gas outlet of a showerhead assembly according to a non-exclusive embodiment of the present invention.

[0016] Figures 4A-4B is a diagram of an insert for use in an adjustable gas outlet of a showerhead assembly according to a non-exclusive embodiment of the present invention.

[0017] Figure 5 is a cross-sectional view of a showerhead assembly and a deposition pedestal according to a non-exclusive embodiment of the present invention.

[0018] In the drawings, similar component symbols may sometimes be used to designate similar structural elements. It should also be understood that the depictions in the drawings are schematic and not necessarily drawn to scale. DETAILED DESCRIPTION

[0019] The present application will now be described in detail with reference to some non-exclusive embodiments as shown in the accompanying drawings. In the following description, many specific details are set forth to provide a thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention may be implemented without some or all of these specific details. In other cases, known process steps and / or structures are no longer described in detail to avoid making the present invention unnecessarily difficult to understand.

[0020] refer to Figure 1 , which shows a perspective cutaway view of a deposition tool 10 of a non-exclusive embodiment of the present invention. As described in detail below, the tool 10 is capable of (1) performing backside substrate deposition and (2) simultaneously preventing concomitant deposition of backside deposited material on the device side of the substrate by using a purge gas. In various embodiments, the deposition tool 10 can be a plasma enhanced (PECVD), low pressure (LPCVD), ultra-high vacuum (UHVCVD), atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), or any other type of deposition tool.

[0021] The tool 10 includes a process chamber 12 defined by a process chamber sidewall 14 and a top plate 16. Located within the process chamber 12 is a deposition pedestal 20. The deposition pedestal 20 can be any device that performs the following functions: (a) supports the substrate in the process chamber 12, and (b) is capable of depositing a thin film on the back side of the substrate. In a non-exclusive embodiment, the deposition pedestal is a deposition reactant dispersion pedestal. The showerhead assembly 18 hangs down from the top plate 16 in a "chandelier"-like manner, and the deposition pedestal 20 provides a platform for supporting the substrate directly below the showerhead assembly 18.

[0022] The deposition pedestal 20 supports a substrate (not shown) on a substrate ring 22. The deposition pedestal 20 also supplies deposition gas received through a supply tube 24 disposed in a rod 26 of the deposition pedestal 20 to the back side of the substrate. The deposition pedestal 20 is used to distribute the deposition gas into a gap 28 across the back side of the substrate. The deposition pedestal 20 also includes a heating assembly 30, which is responsible for heating the deposition reactants to about 400° C. or higher during backside deposition.

[0023] When radio frequency (RF) is applied, a plasma is generated in the processing chamber. Thus, a thin film is deposited on the back side of the substrate at an elevated temperature. As described above, the purpose of this back side deposition is to prevent or reduce warping of the substrate during subsequent processing steps (including steps performed at high temperatures, such as annealing).

[0024] The showerhead assembly 18 includes a cylindrical body 32, a top purge plate 34, and an adapter plug 36 at least partially inserted into the cylindrical body 32. The adapter plug 36 includes a purge gas supply inlet 38 for supplying purge gas to a plenum 40 disposed within the cylindrical body 32. The purge gas in the plenum 40 is then distributed laterally through another plenum 41 below the top purge plate 34 and behind the face plate 42 (relative to the top surface of the substrate). With this arrangement, the purge gas supplied by the gas supply inlet 38 flows through the two plenums 40, 41, out of the plurality of adjustable gas outlets 44 on the face plate 42, and into the area directly above the device side of the substrate. A vacuum (not shown) draws or sucks the purge gas out of the area directly above the device side of the substrate. Thus, the flow of the upper purge gas serves to remove any deposition material (which concomitantly enters the area above the device side of the substrate). Thus, any concomitant device side deposition is reduced or completely eliminated.

[0025] In various embodiments, the one or more purge gases used are inert gases such as nitrogen, argon, helium, or combinations thereof.

[0026] refer to Figure 2 , which only shows a perspective cutaway view of the spray head assembly 18. As shown in the figure, the spray head assembly 18 includes a cylindrical body 32, a top purge plate 34, an adapter plug 36, a purge gas supply inlet 38, a plenum 40 contained in the cylindrical body 32, a gas chamber 41 formed between the top purge plate 34 and a face plate 42, and a plurality of adjustable gas outlets 44.

[0027] In addition, the showerhead assembly 18 includes a compression ring 46 and a fixture 47 for holding the compression ring 46 and the adapter plug 36 together within the cylindrical body 32. The adapter plug 36 is also arranged to accommodate several "utilities" required within the processing chamber 12. These utilities include (but are not limited to) a radio frequency (RF) rod 48, a power supply conduit 50, and a thermocouple or "TC" 52.

[0028] refer to Figure 3A-3B , which shows a diagram of the spray head assembly 18 including a faceplate 42 and an adjustable outlet 44.

[0029] like Figure 3A As shown, the panel 42 includes a plurality of adjustable gas outlets 44. In the particular embodiment shown, a total of eighteen (18) adjustable gas outlets 44 are disposed on the surface of the panel 42.

[0030] like Figure 3B As shown, each adjustable gas outlet 44 includes a hole 54 formed through the thickness of the panel 42. Within each hole 54, an insert 56 is inserted. In the particular embodiment shown, the insert 56 includes seven (7) smaller holes 58. Thus, this particular showerhead assembly 18 has a total of eighteen (18) adjustable gas outlets 44, and (b) seven (7) holes 58 per adjustable gas outlet 44, or a total of one hundred and twenty-six (126) holes 56 disposed throughout the panel 42.

[0031] refer to Figures 4A-4B , which shows a diagram of an exemplary insert 56 . Figure 4A A perspective view of the insert 56 is shown, and Figure 4B A cross-sectional view is shown.

[0032] As shown in both figures, the insert 56 includes a hollow cylindrical body 60 having a purge gas inlet end 62 and a purge gas outlet end 64. An aperture 58 is provided at the gas purge outlet end.

[0033] Insert 56 is configured to be selectively inserted into hole 54 provided in face plate 42. When inserted, purge gas inlet 62 is in fluid communication with plenum 41 formed between top purge plate 34 and face plate 42. Thus, purge gas flows from plenum 41 downwardly to hollow cylinder 60 and out of hole 58 just above the device side of the substrate.

[0034] It should be noted that Figure 3A-3B The specific embodiments of the panel 42, adjustable gas outlets 44, and plug-in 56 shown in and 4A-4B are merely examples and should not be construed as limiting in any respect. Instead, the panel 42 may assume any desired shape, although typically it will be assumed to have the same or similar shape as the substrate. In addition, the number and arrangement of the adjustable gas outlets 44 may also vary widely. The number of adjustable gas outlets 44 may be more or less than eighteen (18), and they may be arranged in any pattern on the panel 42. In addition, the plug-in 56 may also be modified as needed or desired. For example, the number of holes 58 at the purge gas outlet end 64 of the plug-in 56 may be changed to increase or decrease the total number of holes, depending on demand, flow rate, or other specifications.

[0035] In a specific but non-exclusive embodiment, the diameter of the hole 56 is about 0.04 inches or 1.0 mm. In other embodiments, the diameter of the hole can be larger or smaller, such as in the range of 0.001 to 0.06 inches. The size or diameter of the hole 56 can also be varied as needed to meet the flow rate or other specifications of the purge gas.

[0036] The frequency of the RF used in the processing chamber 12 may also affect the diameter of the hole 56 that can be used. For example, with an RF of 27.112 MHz, a smaller diameter of the hole 56 is required compared to using 13.56 MHz. At higher RF frequencies, a smaller diameter is required to prevent hollow cathode discharge or arcing, which can damage equipment on the substrate.

[0037] By using the insert 56, the flow rate of the purge gas may be selectively adjusted or controlled in several ways. First, the number of adjustable gas outlets 44 may be varied. Second, if a particular showerhead assembly 18 has more adjustable gas outlets 44 than may be desired, a plug 56 without holes 58 may be inserted for use as a "plug." Third, when using an insert 56 with holes 58, the number, spacing, and diameter of the holes 58 may be varied to match the desired or required flow rate. The use of the insert 56 provides the advantage that the showerhead assembly 18 may be configured in the field even after the deposition tool 10 has been installed at the customer's location. By disassembling the showerhead assembly 18, such as during routine maintenance, the insert 56 may be changed as needed to match changing operating conditions. Similarly, if the RF used by the tool changes, a new insert with appropriately sized holes 58 may be easily substituted in the field for that reason.

[0038] In addition, the inserts 56 for a given showerhead assembly need not all be identical. For example, some inserts 56 may have a different number of holes 58 or a different pattern of holes 58 than other inserts 56, or some inserts 56 may have holes 58 while other inserts 56 do not. Thus, the local flow of purge gas produced by each insert 56 may be highly adjustable relative to the device side of the substrate. For example, in some cases, it is understandable that there is a higher purge gas flow rate near the center of the substrate and a lower flow rate at the periphery. In this case, the insert 56 for facing the center of the faceplate 42 is configured to have a higher flow rate, while the inserts 56 toward the periphery have a lower flow rate. This is just one example of how the adjustable gas outlet 44 of the showerhead assembly 18 can be configured to control the local flow of purge gas over different areas of the device side of the substrate as needed or desired. By using inserts 56 having different numbers of holes 58, arrangements or patterns of holes 58, diameters of holes 58, and strategically placing different inserts 56 at different locations on the panel 42, the localized purge gas flow pattern over the device side of the substrate can be controlled or adjusted in nearly countless ways.

[0039] In a non-exclusive embodiment, the showerhead assembly 18 is made of ceramic. Using ceramic provides several benefits, including thermal and geometric stability, higher tolerance at elevated temperatures up to 600° C. or even higher, low particle generation, and resistance to process gases such as nitrogen trifluoride (NF3) and / or other gases that may be used during remote plasma cleaning (RPC). Ceramics also have the advantages of long service life and reasonable manufacturing costs. Although ceramics are suitable materials, other materials, such as ceramic-coated metals, may also be used.

[0040] The showerhead assembly 18 is also responsible for heating the substrate during backside deposition. In various embodiments, the showerhead assembly includes a single zone heating assembly or a multi-zone heating assembly (both not shown) in addition to other provided utilities as described above. The showerhead assembly 18 typically heats the substrate in the range of 510°C to 520°C.

[0041] The showerhead assembly 18 may also be used to deliver an in-situ cleaning gas during a routine cleaning cycle of the process chamber 12. Such a cleaning gas may include, for example, fluorine. In addition to cleaning exposed surfaces within the process chamber 12, the cleaning gas will also clean exposed portions of the showerhead assembly 18, including the faceplate 42 and the various holes 58 of the insert 56.

[0042] refer to Figure 5 , which shows a cross-sectional view of the showerhead assembly 18 and the deposition pedestal 20 during backside deposition and tool side purge.

[0043] The substrate 70 is supported around its periphery by the substrate ring 22 of the deposition pedestal 20. With this arrangement, a large portion of the back side of the substrate is exposed within the gap 28 below.

[0044] During backside deposition, the deposition gas flows upward through the supply tube 24 in the rod 26, is heated by the heating assembly 30, and is then distributed laterally into the plenum 72. Once distributed into the plenum 72, the deposition gas flows upward into the gap 28 through an array of through holes 74 formed through the top surface of the deposition pedestal 20. Arrows 76 depict the path of the deposition gas flowing through the deposition pedestal 20 and into the gap 28. Thus, the back side of the substrate 70 is exposed to the deposition gas. When RF is applied, a plasma is generated in the process chamber 12 and the gap 28, thereby forming a thin film on the back side of the substrate 70.

[0045] By controlling the temperature of the deposition gas, so-called high or low backside deposition can be performed. As previously mentioned, when deposition is performed at higher temperatures, the resulting layer better retains its tensile and compressive strength during subsequent high temperature processing steps. Thus, the substrate remains substantially flat even when faced with elevated temperatures, such as those experienced during annealing or high temperature deposition.

[0046] In various embodiments, the deposition gas is generally silicon-containing, such as a gas containing nitride, carbon dioxide, carbon monoxide, silane, or a combination thereof. In other embodiments, vaporized precursors such as tetraethylsiloxane (TEOS) may also be used.

[0047] During backside deposition, the showerhead assembly 18 heats the substrate 70 in the range of 510°C to 520°C and supplies a continuous flow of sweep gas over the device surface of the substrate 70. The path of travel of the sweep gas includes the supply inlet 38, the plenums 40 and 41, and the hole 58 through the insert 56 disposed in the adjustable gas outlet 44 of the faceplate 42. The vacuum 80 (fluidically coupled to the space above the substrate through the valve 82) applies vacuum pressure to remove the sweep gas above the substrate. Any backside deposition material that incidentally enters the space above the device side of the substrate is swept away by the flow of the sweep gas. Thus, incidental film deposition on the device surface of the substrate is reduced or completely eliminated.

[0048] It should be understood that the embodiments provided herein are only examples and should not be interpreted as limiting in any respect. Although only some embodiments are described in detail, it should be understood that the application can be implemented in many other forms without departing from the spirit or scope of the disclosure provided herein. Therefore, the present embodiment should be regarded as illustrative rather than restrictive, and is not limited to the details given herein, and can be modified in the scope and equivalents of the appended claims.

Claims

1. A deposition tool comprising: Processing room; a deposition susceptor for supporting a substrate in the processing chamber and for depositing a material film on a first surface of the substrate; as well as A showerhead assembly having a faceplate relative to a second surface of the substrate, the faceplate of the showerhead having a plurality of adjustable gas outlets arranged to distribute a purge gas near the second surface of the substrate when the material film is being deposited on the first surface of the substrate. 2 . The deposition tool of claim 1 , further comprising a plurality of inserts, each of the inserts being arranged to be inserted into a respective one of the adjustable gas outlets, respectively.

3. The deposition tool of claim 2, wherein each of the inserts is removable and replaceable with another insert of a different configuration to reconfigure the corresponding adjustable gas outlet.

4. The deposition tool of claim 2, wherein each of the inserts has one or more holes for distributing the sweep gas near the second surface of the substrate.

5. The deposition tool of claim 3, wherein each of the one or more holes has a diameter in the range of 0.001 to 0.06 inches.

6. The deposition tool of claim 2, wherein two or more of the plurality of inserts are different and define different localized flow patterns of the sweep gas relative to the second surface of the substrate.

7. A deposition tool according to claim 3, wherein the diameter of the one or more holes depends on the frequency of a radio frequency (RF) source applied to the processing chamber, wherein the higher the frequency of the RF source, the smaller the diameter, and the lower the frequency, the larger the diameter.

8. The deposition tool of claim 2, wherein at least one of the inserts functions as a plug for blocking the flow of the sweep gas through the corresponding adjustable gas outlet.

9. The deposition tool of claim 1, wherein the showerhead assembly is at least partially made of a material capable of withstanding temperatures of about 400°C or higher.

10. The deposition tool of claim 1, wherein the showerhead assembly is at least partially made of ceramic.

11. The deposition tool of claim 2, wherein the plurality of inserts are made of ceramic.

12. The deposition tool of claim 1, wherein the showerhead assembly further comprises: Cylinder; A plenum, contained within the cylindrical body, is configured to supply the purge gas to the faceplate of the showerhead assembly.

13. The deposition tool of claim 1, wherein the showerhead assembly further comprises a transfer plug arranged to be at least partially inserted into the cylinder, the transfer plug comprising a supply inlet to supply the purge gas to the gas chamber contained within the cylinder.

14. The deposition tool of claim 1, wherein the showerhead assembly further comprises: Cylinder; an adapter plug arranged to be at least partially inserted into the cylindrical body; as well as One or more clamps for at least partially retaining the adapter plug in the cylinder.

15. The deposition tool of claim 14, further comprising a compression ring disposed between the adapter plug and the cylindrical body.

16. The deposition tool of claim 1, wherein the showerhead assembly further comprises: Cylinder; an adapter plug arranged to be at least partially inserted into the cylinder, the adapter plug being configured to accommodate one or more of: (a) RF power supply rod; (b) a power supply conduit; or (c) Thermocouple.

17. The deposition tool of claim 1, wherein the purge gas is an inert gas.

18. The deposition tool of claim 1, wherein the purge gas system is selected from one of the following: (a) Nitrogen; (b) Argon; (c) helium; or (d) Any combination of (a) to (c).

19. The deposition tool of claim 1 further comprising a vacuum and a valve for removing the sweep gas from a space near the second surface of the substrate.

20. The deposition tool of claim 1, wherein the showerhead assembly further comprises a plenum disposed adjacent to the faceplate to supply the purge gas to the adjustable gas outlet.

21. A plug-in arranged to be inserted into an adjustable gas outlet of a nozzle of a deposition tool, wherein the plug-in is configured to configure a flow of a purge gas out of the adjustable gas outlet and near a first surface of a substrate when inserted into the adjustable gas outlet, wherein the flow of the purge gas is to prevent or reduce the deposition of the material on the first surface when the material is being deposited on the second surface of the substrate.

22. The insert of claim 21, wherein the insert is removable from the adjustable gas outlet and selectively replaceable with another insert in the event that the purge gas has different flow characteristics.

23. The insert of claim 21, wherein the insert is a hollow cylinder comprising an inlet for receiving the purge gas and an outlet for dispensing the purge gas, in, When the insert is inserted into the adjustable gas outlet, the inlet is arranged to receive the sweep gas from a supply plenum disposed within the showerhead, and the outlet is arranged to distribute the sweep gas proximate the first surface of the substrate.

24. The insert of claim 21, wherein the insert comprises an outlet for distributing the sweep gas proximate the first surface of the substrate, the outlet comprising one or more holes for distributing the sweep gas.

25. The insert of claim 24, wherein each of the one or more holes has a diameter in the range of 0.001 to 0.06 inches.

26. The insert of claim 24, wherein a diameter of the one or more holes is dependent on a frequency of a radio frequency (RF) source used by the deposition tool.

27. The insert of claim 21, wherein the insert acts as a plug for blocking the flow of the purge gas through the adjustable gas outlet.

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