Embodiments relate to the field of semiconductor manufacturing and, in particular, to semiconductor processing tools for deposition of films on the backside of substrates for wafer bow management.
In semiconductor processing applications, one or more layers are deposited over a top surface of the substrate. The one or more layers may be stressed. The stress in the layers may be transferred into the substrate itself. This stress can result in warpage or bowing of the substrate. When the substrate is warped or bowed, the features on the substrate (e.g., pillars, lines, etc.) may be displaced. For example, pillars may be tilted towards each other or spread apart from each other, depending on the warpage. Additionally, chucking the substrate is made more difficult.
Accordingly, in some architectures a stress compensating film may be provided on the backside of the substrate. Ideally, the stress inherent in the stress compensating film is opposite from the stress provided by the layers on the top of the substrate. As such, the bowing or warpage is compensated in order to provide a substantially flat substrate for additional processing.
Providing backside layers over the substrate is not without issue. Particularly, the backside deposition process cannot cause particles or deposition on the front side of the substrate. Additionally, it is typically not desirable to flip the orientation of the substrate (i.e., flip the substrate upside down). As such existing deposition tools are generally not suitable for backside deposition processes.
Embodiments disclosed herein include a semiconductor processing tool. In an embodiment, the semiconductor processing tool comprises a chamber, a pedestal in the chamber, and a first gas feed system on a first side of the pedestal. In an embodiment, the first gas feed system comprises a first exhaust line with a first valve to open and close the first exhaust line, and a first source gas feed line with a second valve to open and close the first source gas feed line. In an embodiment, the semiconductor processing tool further comprises a second gas feed system on a second side of the pedestal. In an embodiment, the second gas feed system comprises a second exhaust line with a third valve to open and close the second exhaust line, and a second source gas feed line with a fourth valve to open and close the second source gas feed line.
Embodiments may also include a semiconductor processing tool that comprises a pedestal, a showerhead over the pedestal where the showerhead comprises a first plate with first holes and a second plate with second holes over the first plate, and lift pins configured to lift a substrate over the pedestal and the showerhead.
Embodiments may also include a semiconductor processing tool that comprises a chamber, a pedestal in the chamber, where the pedestal is coupled to an RF source, and a plate over the pedestal, where the plate is coupled to an electrical ground. In an embodiment, the semiconductor processing tool further comprises a gas distribution assembly between the pedestal and the plate. In an embodiment, the gas distribution assembly is configured to supply a process gas to a backside of a substrate.
Systems described herein include semiconductor processing tools for deposition of films on the backside of substrates for wafer bow management. In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail in order to not unnecessarily obscure embodiments. Furthermore, it is to be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.
As noted above, depositing films on the backside of substrates can be useful for correction of bowed or warped substrates. However, the existing processing tools are typically designed to process the top side of substrates. That is, in order to form a backside film, the substrate needs to be flipped. This can damage the front side of the substrate, and is not desirable. Accordingly, embodiments disclosed herein include semiconductor processing tools that are configured to form a plasma below the substrate in order to deposit the backside film. In some embodiments, the processing gas is flown into the chamber from the sides. In other embodiments, a showerhead below the substrate faces the backside of the substrate in order to flow the processing gas into the chamber.
Additionally, it is to be appreciated that different types of warpage may need non-uniform backside film deposition. As such, embodiments disclosed herein include different methods and architectures in order to control the flow of processing gasses, control plasma parameters, or the like. In other embodiments, architectures may be particularly beneficial for providing uniform film deposition.
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In an embodiment, the semiconductor processing tool 100 includes a chamber 130. The chamber 130 may be any suitable material configured to support vacuum conditions within the chamber 130. The bottom portion of the chamber 130 is shown in
In an embodiment, the semiconductor processing tool 100 may further comprise a first gas feed system 110A and a second gas feed system 110B. In an embodiment, the first gas feed system 110A and the second gas feed system 110B may be substantially similar to each other and provided on opposite sides of the semiconductor processing tool 100. In an embodiment, the gas feed systems 110A and 1108 may include exhaust lines 112 and process gas feed lines 114. Additionally, a set of valves may be provided on each gas feed system 110A and 1108. For example, in the first gas feed system 110A a first valve 101 may control gas flow into the exhaust line 112, and a second valve 102 may control gas flow into the chamber 130 from the gas feed line 114. Similarly, in the second gas feed system 1106, a third valve 103 may control gas flow into the exhaust line 112, and a fourth valve 104 may control gas flow into the chamber 130 from the gas feed line 114. In an embodiment, each of the gas feed systems 110A and 1108 may also include a showerhead 116 for distributing gasses into the chamber 130. In some embodiments, one or both of the showerheads 116 may be omitted.
In an embodiment, the semiconductor processing chamber 100 may include a pedestal 120. The pedestal 120 may be coupled to an RF source in order to strike the plasma between the substrate 125 and the top of the pedestal 120. The substrate 125 may be lifted up from the top of the pedestal 120 by lift pins 122. In some embodiments, the pedestal 120 may be a stationary pedestal 120. In other embodiments, the pedestal 120 may be rotatable. A rotating pedestal 120 may further improve film deposition uniformity in some instances. In a particular instance the inclusion of a rotating pedestal 120 may allow for a single sided gas feed system (e.g., a semiconductor processing tool 100 with a single gas feed line 110A) to be used while still enabling uniform film deposition.
In an embodiment, the substrate 125 may be any type of substrate typically processed in semiconductor manufacturing equipment. In a particular embodiment, the substrate 125 may be a wafer (e.g., a silicon wafer or any other semiconductor wafer). The substrate 125 may have any form factor (e.g., 150 mm, 200 mm, 300 mm, 450 mm, or the like). Other materials and form factors may also be used for the substrate 125 (e.g., glass substrates, sapphire substrates, or the like). That is, the substrate 125 may be any substrate that may benefit from the inclusion of a backside film deposition.
In an embodiment, the backside film that is deposited may be a film that can induce a high level of stress into the substrate 125. In a particular embodiment, the backside film may include silicon and nitrogen (e.g., silicon nitride). The silicon nitride film may be a high temperature film. For example, the backside film may be deposited at a temperature of 500° C. or greater, or 700° C. or greater. The high temperature may be implemented in part by using a pedestal 120 that can be heated. Alternatively (or in addition to a heated pedestal), an array of lamps 142 may be provided above the substrate 125 in order to heat the substrate 125.
In an embodiment, a grounded plate 141 may be provided over the substrate 125. The grounded plate 141 may be coupled to an electrical ground in order to enable the formation of a plasma in the chamber 130. The grounded plate 141 may also be a showerhead in some embodiments. For example, an inert process gas may be flown into the chamber through the grounded plate 141 in some embodiments. The grounded plate 141 may be relatively close to the top surface of the substrate 125. The minimal spacing between the grounded plate 141 and the substrate 125 (and the flow of the inert gas) may assist in preventing the formation of a plasma between the grounded plate 141 and the top surface of the substrate 125. For example, the grounded plate 141 may be approximately 10 mm or less, approximately 5 mm or less, or approximately 1 mm or less away from the top surface of the substrate 125. Preventing the formation of a plasma above the substrate 125 keeps the top surface of the substrate pristine and undamaged during the backside film deposition process.
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In an embodiment, the semiconductor processing tool 100 may switch between the first tool configuration and the second tool configuration in order to uniformly deposit a backside film onto the substrate 125. In a particular embodiment, the semiconductor processing tool 100 may be in the first tool configuration for a first duration, and the semiconductor processing tool 100 may be switched to the second tool configuration for a second duration. The first duration and the second duration may be substantially similar to each other. In other embodiments, the semiconductor processing tool 100 may be switched back and forth between the first tool configuration and the second tool configuration. In yet another embodiment, either the first tool configuration or the second tool configuration may be selected, and the substrate 125 may be rotated. In an embodiment, the rotation may be at a constant angular speed while varying gas flows in order produce a uniform backside film or an intentional non-uniform backside film.
While embodiments with a uniform backside film are possible, it is also possible to form non-uniform backside films. For example, the first duration may be greater than the second duration in order to form a thicker backside film on one side of the substrate. Alternatively, only one of the first tool configuration or the second tool configuration may be selected without rotating the substrate 125. In other embodiments, the rotation may be at a varying angular speed and constant (or varying) process gas flows may be used to produce intentional non-uniform backside film deposition.
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In an embodiment, the semiconductor processing tool may comprise a pedestal 220. The pedestal 220 may be coupled to an RF source in order to strike a plasma between the substrate 225 and the pedestal 220. In an embodiment, the pedestal 220 may further comprise a heater in order to provide high temperature backside films. The grounded plate for completion of the circuit is omitted for simplicity. But it is to be appreciated that an electrically grounded plate (e.g., showerhead) may be provided above the substrate 225. Lift pins 222 may be provided to support the substrate 225 in a raised position relative to the pedestal 220.
In an embodiment, a showerhead 250 may be provided between the substrate 225 and the pedestal 220. In an embodiment, the showerhead 250 may include a pair of plates 251 and 252. Though, it is to be appreciated that a showerhead with a single plate configuration may also be used in some embodiments. In an embodiment, the processing gas (as indicated by the arrows) may flow between the pedestal 220 and the first plate 251. The gas may flow up through holes 253 in the first plate 251. A gap may be provided between the first plate 251 and the second plate 252 in order to allow for further distribution of the processing gas. In an embodiment, the processing gas then flows through holes 254 in the second plate 252 in order to enter the chamber.
In an embodiment, the number of holes 253 may be different than the number of holes 254. For example, there may be fewer holes 253 than there are holes 254. Additionally, a diameter of the holes 253 may be larger than a diameter of the holes 254. The positioning of the holes 253 relative to the holes 354 may also be offset in order to enhance the spreading of the processing gas before it enters the chamber below the substrate 225.
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In an embodiment, the showerhead 350 may be any suitable material. In a particular embodiment, the showerhead 350 may be a ceramic showerhead 350. In other embodiments, the showerhead 350 may include a conductive material such as aluminum or the like. Additionally, while a showerhead 350 with a single plate is shown, it is to be appreciated that multi-plate showerheads 350 (similar to the embodiment described above) may be used in accordance with an embodiment. Additionally, while described as a showerhead, the component 350 may be any suitable process kit that allows gas to flow into the processing region of the chamber 330.
In an embodiment, the substrate 325 may be supported up above the showerhead 350 by lift pins 322. The substrate 325 may be raised up to the height of a process ring 337. The process ring 337 may surround a perimeter of the substrate 325 when the substrate is in a raised position. In an embodiment, an overhead showerhead 339 may be provided over a top surface of the substrate 325. The overhead showerhead 339 may be electrically grounded in order to complete the circuit for forming the plasma 360. The overhead showerhead 339 may be fed an inert gas 338. The inert gas flows through the overhead showerhead 339 in order to provide an inert environment over the top surface of the substrate 325 during processing. Additionally, in order to prevent plasma striking above the substrate 325, a distance between the top of the substrate 325 and a bottom of the overhead showerhead 339 may be approximately 10 mm or less, approximately 5 mm or less, or approximately 1 mm or less. As such, damage to the front side of the substrate 325 is minimized. The overhead showerhead 339 may be heated in order to provide high temperature deposition of the film on the backside of the substrate 325.
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In an embodiment, a substrate 325 is supported by lift pins 322 in a raised position to provide room for the plasma 360 between the substrate 325 and the showerhead 350. In an embodiment, the substrate 325 may be surrounded by a process ring 337. An overhead showerhead 339 may be provided over the substrate 325. The overhead showerhead 339 may be fed with an inert gas 338. The overhead showerhead 339 may be electrically grounded in some embodiments. Additionally, the showerhead 339 may be heated in order to provide high temperature film deposition on the backside surface of the substrate 325.
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In the embodiments described above, processing conditions may be maintained in order to deposit a backside film that is substantially uniform over the backside surface of the substrate. However, in some embodiments the stress needs to be applied in a non-uniform manner in order to correct certain types of bowing (e.g., a saddle shaped bow). In such embodiments, modifications to the semiconductor processing tool may be provided in order to control the flow of gas into the chamber in order to deposit a non-uniform backside film.
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Additionally, the process kit 650 (e.g., showerhead) may be coupled to an RF source 692. Instead of being raised and lowered in a planar manner, the process kit may be tilted. The tilt may be accommodated by the bellows 631 of the chamber 630. In an embodiment, the tilted isolator 662 and process kit 650 may result in one side of the process kit 650 being closer to the ground plate 633. As such, the substrate 625 (that is supported by the lift pins 622 and within the process ring 637) will experience a non-uniform plasma 660 across the surface of the substrate. The non-uniform plasma 660 will result in a non-uniform deposition of the backside film.
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Computer system 700 may include a computer program product, or software 722, having a non-transitory machine-readable medium having stored thereon instructions, which may be used to program computer system 700 (or other electronic devices) to perform a process according to embodiments. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium (e.g., read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustical or other form of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.
In an embodiment, computer system 700 includes a system processor 702, a main memory 704 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 706 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 718 (e.g., a data storage device), which communicate with each other via a bus 730.
System processor 702 represents one or more general-purpose processing devices such as a microsystem processor, central processing unit, or the like. More particularly, the system processor may be a complex instruction set computing (CISC) microsystem processor, reduced instruction set computing (RISC) microsystem processor, very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or system processors implementing a combination of instruction sets. System processor 702 may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), network system processor, or the like. System processor 702 is configured to execute the processing logic 726 for performing the operations described herein.
The computer system 700 may further include a system network interface device 708 for communicating with other devices or machines. The computer system 700 may also include a video display unit 710 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), a cursor control device 714 (e.g., a mouse), and a signal generation device 716 (e.g., a speaker).
The secondary memory 718 may include a machine-accessible storage medium 732 (or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 722) embodying any one or more of the methodologies or functions described herein. The software 722 may also reside, completely or at least partially, within the main memory 704 and/or within the system processor 702 during execution thereof by the computer system 700, the main memory 704 and the system processor 702 also constituting machine-readable storage media. The software 722 may further be transmitted or received over a network 720 via the system network interface device 708. In an embodiment, the network interface device 708 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.
While the machine-accessible storage medium 732 is shown in an exemplary embodiment to be a single medium, the term “machine-readable storage medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable storage medium” shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies. The term “machine-readable storage medium” shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media.
In the foregoing specification, specific exemplary embodiments have been described. It will be evident that various modifications may be made thereto without departing from the scope of the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.