Embodiments relate to the field of semiconductor manufacturing and, in particular, a process for estimating thermal uniformity across a substrate in a modeled tool.
In semiconductor processing environments, rapid thermal processing (RTP) tools are used, for example, in order to execute thermal treatments (e.g., anneals) and grow material layers (e.g., oxidation growth), to name a couple applications. In an RTP tool, an array of lamps are used in order to heat a substrate that is positioned below the lamps. A reflector may also be provided below the substrate in some instances. Temperature control across the surface of the substrate is a critical parameter of RTP tools. Often the temperature is desired to be substantially uniform across the diameter of the substrate.
In order to control the temperature, RTP tools often include lamps that are grouped into a plurality of zones. The lamps in a single zone may be supplied with the same amount of power, and the different zones may have different power levels. For example, the power of a zone near the center of the substrate may be different than the power of a zone towards the edge of the substrate.
Control of the temperature across the substrate is a complex engineering obstacle. While positioned above a certain region of the substrate, the lamp irradiation may also heat up neighboring regions of the substrate. Thermal modeling also needs to take into account chamber wall temperatures, edge ring temperatures, reflector material, substrate material, among many other parameters.
Accordingly, it is exceedingly difficult to model RTP tools. Additionally, models that are made are computationally intensive, and require long periods of time in order to generate the thermal behavior within a system. Due to the complexity of forming such models, it is difficult to model new RTP tool designs. For example, it may be desirable to reduce the number of lamps in an RTP tool (e.g., for decreased manufacturing cost, reductions in consumed power, etc.). However, existing solutions limit the ability to test new designs before they are implemented in a physical form.
Embodiments disclosed herein include a method of modeling a rapid thermal processing (RTP) tool. In an embodiment, the method comprises developing a lamp model of an RTP tool, wherein the lamp model comprises a plurality of lamp zones, calculating an irradiance graph for the plurality of lamp zones, multiplying irradiance values of the plurality of lamp zones in the irradiance graph by a power of an existing RTP tool at a given time during a process recipe, summing the multiplied irradiance values for the plurality of lamp zones to form an irradiation graph of the lamp model, using the irradiation graph as an input to a machine learning algorithm, and outputting the temperature across a hypothetical substrate from the machine learning algorithm.
Embodiments may also include a non-transitory computer readable medium containing program instructions for causing a computer to perform a method. In an embodiment, the method comprises developing a lamp model of an RTP tool, wherein the lamp model comprises a plurality of lamp zones, calculating an irradiance graph for the plurality of lamp zones, multiplying irradiance values of the plurality of lamp zones in the irradiance graph by a power of an existing RTP tool at a given time during a process recipe, summing the multiplied irradiance values for the plurality of lamp zones to form an irradiation graph of the lamp model, using the irradiation graph as an input to a machine learning algorithm, and outputting the temperature across a hypothetical substrate from the machine learning algorithm.
Embodiments may also include a method of modeling a rapid thermal processing (RTP) tool. In an embodiment, the method comprises training a machine learning algorithm with training data that includes real temperature data from an existing RTP tool, developing a lamp model of an RTP tool, wherein the lamp model comprises a plurality of lamp zones, and wherein a number of lamps in the lamp model is different than a number of lamps in the existing RTP tool, calculating an irradiance graph for the plurality of lamp zones, multiplying irradiance values of the plurality of lamp zones in the irradiance graph by a power of the existing RTP tool at a given time during a process recipe, summing the multiplied irradiance values for the plurality of lamp zones to form an irradiation graph of the lamp model, using the irradiation graph as an input to the machine learning algorithm, and outputting the temperature across a hypothetical substrate from the machine learning algorithm.
Systems described herein include a process for estimating thermal uniformity across a substrate in a modeled tool. 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, it is currently difficult to model rapid thermal processing (RTP) tools that are being developed. Accordingly, it is not currently feasible to determine the substrate temperature profile on a design without using an overly complex model or actually building the RTP tool. This leads to excess waste of resources and time. This is particularly problematic when redesigns of the RTP tool are needed. For example, it may be desirable to reduce the number of lamps in the lamp array in order to reduce costs and/or reduce power consumption.
Therefore, embodiments disclosed herein include methods in order to generate the temperature profile using machine learning (ML) algorithms. Generally, a new lamp design is created. The irradiance of the lamps on the substrate is calculated. This provides a graph of the irradiance supplied by a plurality of lamp zones. The irradiance can then be multiplied by a power in a recipe that is supplied to the individual zones. The resulting values of each zone can then be summed together in order to provide a graph of the irradiation across the surface of the substrate. In an embodiment, the irradiation values may then be inputted into a ML algorithm. The ML algorithm may output a temperature profile for the RTP tool being investigated. As such, there is no need to extensively model or build an RTP tool in order to determine temperature profiles.
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In an embodiment, the lamps 155 may be separated into a plurality of groups (also referred to as zones). The zones may be substantially concentric zones. In a simple case, a first zone may be a central zone, and a second zone may be the group of lamps 155 outside of the first zone. However, it is to be appreciated that in more complex tools, the number of zones may be significantly higher. For example, there may be up to 15 (or more) zones in a given lamp array.
For purposes of convenience, the lamp array 150 may be considered herein as a physical lamp array 150. That is, the lamp array 150 may be an existing array that has already been designed and assembled. The lamp array 150 may be used for training purposes in order to teach machine learning (ML) algorithms in order to aid in the development of new RTP architectures.
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As will be described in greater detail below, the lamp array 160 may be a theoretical or hypothetical lamp array 160. That is, the lamp array 160 may not be physically built. However, as a result of analysis methods, such as those described in greater detail below, the lamp array 160 can be analyzed in order to determine the temperature profile that will be implemented on a substrate. As such, the output of the RTP tool can be characterized and compared to existing solutions in order to determine if the design should be built out into an actual product. This saves design time and costs, since underperforming lamp arrays 160 can be dismissed from consideration.
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The graph in
In the illustrated embodiment, group 1 (G1) may be at a center of the substrate and group 7 (G7) may be at an edge of the substrate. As shown, group 7 may have the highest power during the thermal soak, and group 1 may have the lowest power during the thermal soak. The remaining groups (G2-G6) may have powers between group 1 and group 7.
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In a particular embodiment, the moment in time that the graph in
In an embodiment, the temperature snapshot in
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In an embodiment, the ML algorithm takes irradiation values as an input (e.g., similar to the graph shown in
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In an embodiment, the process 690 may continue with operation 692, which comprises developing a lamp model of an RTP tool. In an embodiment, the lamp model of the RTP tool may have a different configuration than the lamp array of the existing RTP tool used for the ML algorithm training process. For example, the lamp model may have a lamp array with a different layout of the individual lamps and/or a different number of lamps in the lamp array. In a particular embodiment, the RTP tools being investigated are desired to have the same or similar performance as the existing RTP tool while including fewer lamps in order to enable cost and power reductions.
In an embodiment, the process 690 may continue with operation 693, which comprises calculating an irradiance graph for a plurality of zones for the lamp model. In an embodiment, the irradiance graph may be similar to the graph shown in
In an embodiment, the process 690 may continue with operation 694, which comprises multiplying irradiance values of the plurality of lamp zones in the irradiance graph by a power of the existing RTP tool at a given time during a process recipe. For example, the power values may be provided by a graph, such as the graph shown in
In an embodiment, the process 690 may continue with operation 695, which comprises summing the multiplied irradiance values for the plurality of lamp zones to form an irradiation graph of the lamp model. The irradiation graph of the lamp model may be similar to the graph shown in
In an embodiment, the process 690 may continue with operation 696, which comprises using the irradiation graph (or graphs) as an input to the ML algorithm. The irradiation graph (or graphs) may be inputted in the ML algorithm that was trained in operation 691. In an embodiment, the process 690 may continue with operation 697, which comprises outputting the temperature across a hypothetical substrate from the machine learning algorithm. As such, the performance of the RTP tool can be determined without the need to build the model of the RTP tool. Accordingly, many different models may be easily investigated using a similar process in order to select the best candidates for further consideration with minimal cost and development time.
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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.