EMISSIVITY INDEPENDENCE TUNING

Embodiments disclosed herein include a method of calibrating a processing tool. In an embodiment, the method comprises providing a first substrate with a first emissivity, a second substrate with a second emissivity, and a third substrate with a third emissivity. In an embodiment, the process may include running a recipe on each of the first substrate, the second substrate, and the third substrate, where the recipe includes a set of calibration attributes. In an embodiment, the method may further comprise measuring a layer thickness on each of the first substrate, the second substrate, and the third substrate. In an embodiment, the method further comprises determining if the layer thicknesses are uniform.

BACKGROUND

Embodiments relate to the field of semiconductor manufacturing and, in particular, processes and apparatuses for implementing emissivity independence tuning for a thermal oxidation process.

2) Description of Related Art

Thermal oxidation processes are typically used in semiconductor process flows. Thermal oxidation may be implemented in a chamber that includes one or more lamps in order to heat a substrate provided in the chamber. There may be one or more lamp zones in order to control the temperature across the surface of the substrate. One or more pyrometers may be used in order to provide feedback to a controller that controls the power of the lamps. The pyrometers may be on the opposite side of the substrate from the lamps or on the same side as the lamps.

The signal from the pyrometers is typically processed before being sent to the controller. For example calibration attributes or a mask may be applied to the signals before being used by the controller. The calibration attributes may include offsets that are used in order to account for different emissivities of the substrate. Ideally, the process is emissivity independent. That is, the control of the lamps does not depend on the emissivity of the substrate.

In order to provide emissivity independence a calibration process is implemented. The calibration process may be implemented after planned maintenance (PM) or hardware changes. The calibration process is typically done by manual intervention and data entry into the tool. This leads to the possibility of errors copying data from computer screen to keyboard and collecting metrology data to input. Accordingly, the existing process is prone to errors and requires skilled persons to implement the process.

SUMMARY

Embodiments disclosed herein include a method of calibrating a processing tool. In an embodiment, the method comprises providing a first substrate with a first emissivity, a second substrate with a second emissivity, and a third substrate with a third emissivity. In an embodiment, the process may include running a recipe on each of the first substrate, the second substrate, and the third substrate, where the recipe includes a set of calibration attributes. In an embodiment, the method may further comprise measuring a layer thickness on each of the first substrate, the second substrate, and the third substrate. In an embodiment, the method further comprises determining if the layer thicknesses are uniform.

Embodiments disclosed herein may also include a processing environment. In an embodiment, the processing environment may include a host computer, and a processing tool communicatively coupled to the host computer. In an embodiment, the host computer interfaces with software stored in a memory of the processing tool, wherein the software comprises a uniformity algorithm for setting offsets between a signal measured by a pyrometer that is used by a controller as feedback to control a recipe.

Embodiments disclosed herein may further comprise a method for calibrating a processing tool to be emissivity independent. In an embodiment, the method comprises providing a first substrate with a first emissivity film, a second substrate with a bare silicon surface, and a third substrate with a second emissivity film. In an embodiment, the method further comprises processing the first substrate, the second substrate, and the third substrate in the processing tool with a recipe to form an oxide film on the first substrate, the second substrate, and the third substrate. In an embodiment, the recipe includes calibration attributes to modify signals from a pyrometer that are sent to a controller as feedback information. In an embodiment, the method further comprises measuring the oxide film on each of the first substrate, the second substrate, and the third substrate, and modifying the calibration attributes when the oxide films are non-uniform.

DETAILED DESCRIPTION

Systems described herein include processes and apparatuses for implementing emissivity independence tuning for a thermal process. One example of a thermal process is oxidation. Another example is implant anneal. 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, thermal oxidation processes need calibration in order to be emissivity independent. Particularly, the pyrometers of the thermal oxidation chamber need to be calibrated in order to provide accurate feedback to the controller of the thermal oxidation chamber. This calibration may include the generation of calibration attributes. The calibration attributes may be offset values that increase or decrease the value of the signal detected by the pyrometers in order to account for emissivity differences between substrates.

Currently, the calibration process is implemented through the use of manual intervention. Manual calibration is prone to errors due to data entry errors, metrology analysis errors, or the like. Accordingly, embodiments disclosed herein include an automated process in order to provide the calibration of the pyrometers. The calibration process may be implemented by a host computer that is communicatively coupled to the thermal oxidation tool. The host computer may provide instructions for selecting substrates to be processed, processing the substrates with a given recipe, and running metrology on the substrates. The tool may include software stored in a memory that is able to find optimized calibration attributes. For example, physics based models and other algorithms may be used in order to find the optimized calibration attributes.

The benefits of an automated process may include the ability to perform the process without a specialist present. Additionally, there are fewer errors with data input. The green-to-green turnaround time may also be improved. Additionally, a record of past tuning for data analysis for tool health can be obtained. Furthermore, better chamber matching within a fleet is possible, as all chambers will follow the same procedure. Substrate waste is also improved.

Referring now toFIG.1A, a block diagram of a processing environment150is shown, in accordance with an embodiment. In an embodiment, the processing environment150may include a host computer105. The host computer105may be a fab automation system. For example, the host computer105may be communicatively coupled to two or more tools100in a fab environment. In the illustrated embodiment, the host computer105is shown as being coupled to a single tool100for simplicity. In an embodiment, the tool100may be any suitable tool for processing substrates in a fab environment. For example, the tool100may include a chamber that is used to perform thermal oxidation processes.

The host computer105may include instructions stored in a memory in order to execute a chamber calibration process on the tool100. The chamber calibration process will be described in greater detail below. In an embodiment, the host computer105may be communicatively coupled to software101stored in a memory on the tool100. The software101may include instructions for operating the tool100in accordance with a recipe provided by (or selected by) the host computer105.

The software101may also include an algorithm for determining calibration attributes after processing a set of substrates. The calibration attributes are offsets that are added to signals generated by one or more pyrometers in the tool before the signals are sent to a controller as feedback information in order to control the processing in the tool. The algorithm may be based on physics based models for the thermal heat sources and a replication of the algorithms that convert pyrometer sensor data into temperatures that provide feedback control to the controller.

Referring now toFIG.1B, a block diagram of the tool100is shown, in accordance with an embodiment. In a particular embodiment, the tool100may include a central chamber183. The central chamber183may include a robot184for handling substrate110and moving the substrates110throughout the tool100. In an embodiment, the central chamber183may be coupled to a front opening unified pod (FOUP)181through a load port182. The FOUP181may contain a plurality of substrate110that are to be processed by the tool100. In an embodiment, the substrates110may be any suitable substrate form factor. In a particular embodiment, the substrates110are silicon substrates. The diameter of the substrates110may be 300 mm, though smaller or larger form factor substrates110may be used. Additionally, materials other than silicon may be used as the substrates110.

In an embodiment, a processing chamber185may be coupled to the central chamber183. The processing chamber185may be a thermal oxidation chamber185in some embodiments. The details of the thermal oxidation chamber185are provided below. In the particular embodiment shown inFIG.1B, a pair of chambers185(e.g., chamber1and chamber2) are coupled to the central chamber183. Chamber1and chamber2may both be thermal oxidation chambers. In other embodiments, chamber1and chamber2may be different types of chambers (e.g., to provide different processing operations).

In an embodiment, the tool100may also comprise a metrology chamber186. The metrology chamber186may be used in order to provide thickness measurements of films formed on substrate110in the chambers185. For example, the metrology chamber186may include line scan capabilities in order to determine film thicknesses across the surface of the substrate110. In the illustrated embodiment, the metrology chamber186is coupled to the central chamber183. Though, it is to be appreciated that the metrology chamber186may be part of a different tool in some embodiments. In an embodiment, the metrology chamber186may also measure the emissivity of the substrate and use the measured emissivity as an input to the emissivity dependent algorithm.

In the illustrated embodiment, the chambers185and186are coupled together by the central chamber183. However, it is to be appreciated that the chambers185and186may be standalone chambers that are not coupled together by a central chamber183.

Referring now toFIG.2, a cross-sectional illustration of a processing chamber285is shown, in accordance with an embodiment. In an embodiment, the chamber285may comprise any type of semiconductor manufacturing chamber that may require precise substrate temperature control. In the illustrated embodiment, a chamber285without plasma capability is shown. However, it is to be appreciated that the chamber285may also comprise the capability to use a plasma in order to implement various processing regimes.

In an embodiment, the chamber285may comprise a chamber body220. The chamber body220may include any suitable material, such as stainless steel, or the like. In an embodiment, a coating (not shown) may be provided over an interior surface of the chamber body220. For example, the coating may be a chamber seasoning or protection layer. In an embodiment, gas221may enter the chamber285through a first portion of the chamber body220, and gas222may exit the tool through a second portion of the chamber body220. While the gas221and222are shown entering and exiting through the chamber body220, it is to be appreciated that the gas may enter or exit the chamber through any portion of the chamber285, depending on the type of chamber285that is being used.

In an embodiment, a substrate support215may be provided in the chamber285. The substrate support215may comprise three pins that touch and support the substrate210backside directly or there may be a susceptor217that is transparent for pyrometry. The substrate support215and the susceptor217are configured to hold and/or secure a substrate210. For example, the substrate210may be a semiconductor substrate, such as a silicon wafer. The substrate210may have any suitable form factor. For example, a diameter of the substrate210may be 300 mm, 450 mm, or any standard wafer form factor. Additionally, other substrates210may be used in the chamber285. For example, glass substrates, ceramic substrates, or the like may also be used in some embodiments. In an embodiment, the substrate support215and the susceptor217may be configured to rotate. The rotation allows for improved temperature uniformity across the substrate210.

The susceptor217may include any type of chucking architecture in order to secure the substrate210. In some embodiments, the susceptor217may include an electrostatic chucking (ESC) architecture. In such an embodiment, the substrate210is secured to the susceptor217by an electrostatic force. Other embodiments may include a vacuum chucking architecture for the susceptor217. In an embodiment, the susceptor217and the substrate support215may comprise a quartz material or another material that is at least substantially transparent to infrared radiation. As such, a temperature of the backside surface of the substrate210can obtained by pyrometers216.

In an embodiment, the chamber285may include a lid225. The lid225may sometimes be referred to as a chamber dome. While shaped as a dome, it is to be appreciated that lid225may have any architecture (e.g., a flat surface or the like). The lid225may be formed from a material that is at least substantially transparent to infrared radiation. For example, the lid225may comprise quartz or the like.

In an embodiment, the chamber285may also include a bottom lid227. The bottom lid227may cover a bottom surface of the chamber285. The bottom lid227may comprise a material that is at least substantially transparent to infrared radiation. As such, pyrometers on the bottom side of the chamber285can be used to measure a temperature of a bottom surface of the substrate210. In an embodiment, the bottom lid227may be coupled to the substrate support215. More particularly, the substrate support215may pass through the bottom lid227. The bottom lid227is coupled to the substrate support215in a configuration that allows for the substrate support215to freely rotate.

In an embodiment, a plurality of lamps230may be provided outside the internal volume of the chamber285. The internal volume of the tool may refer to the volume defined by the lid225, the chamber body220, and the bottom lid227. That is, the lamps230are not provided within the internal volume of the chamber285where the substrate processing is implemented. In the illustrated embodiment, three sets of lamps230A-230Care provided over a top surface of the lid225. Each of the lamps230A-230Crepresent different lamp regions. Lamps230Amay be for an outer zone of the substrate210, lamps230Bmay be for a middle zone of the substrate210, and lamp230Cmay be for a central zone of the substrate210. The lamps230A-230Cmay be focused on the different zones by a reflector (not shown) that is provided around the lamps230. While one or two lamps230are shown for each zone, it is to be appreciated that any number of lamps may be used to heat each zone of the substrate210. In the illustrated embodiment, the lines from the lamps230to the substrate210illustrate perfect focusing of the infrared light to a particular region of the substrate. However, it is to be appreciated that infrared light from the lamps230may overlap each other to some degree. In the illustrated embodiment, three front-side lamp zones are shown. However, it is to be appreciated that more than three lamp zones may be included in other embodiments. For example, the reflector structure may include four or more zones in order to provide even more enhanced control of the temperature across the surface of the substrate210.

In an embodiment, the plurality of pyrometers216A-216Cmay be provided through the bottom lid227. The pyrometers216may be focused onto the backside surface of the substrate210. In an embodiment, the number of pyrometers216may be equal to the number of heating zones on the substrate210. For example, three heating zones are shown inFIG.2, and three pyrometers216A-216Care provided. The pyrometer216Amay measure temperature at an outer region of the substrate210, the pyrometer216Bmay measure temperature at a middle region of the substrate210, and the pyrometer216Cmay measure temperature at a central region of the substrate210.

In an embodiment, a reflectometer218may be situated at the same side as the pyrometers216. The reflectometer218may be used to measure the emissivity of the substrate and provide that information to the algorithm.

Referring now toFIG.3, a block diagram of an algorithm for setting calibration attributes is shown, in accordance with an embodiment. In an embodiment, the algorithm may be implemented by software101in the tool100. Generally, the pyrometer315generates a signal that is processed by calibration attributes316before being passed to the controller317. The controller317may use the signal as a feedback input in order to control the power delivered to the lamps225of the chamber285. In an embodiment, the calibration attributes316are offset values that are added to the signal in order to account for various conditions, such as the emissivity of the substrate. That is, different emissivities will result in different readings by the pyrometer315. As such, the calibration attributes316work to nullify the impact of emissivity on the sensor reading in order to provide an emissivity independent feedback signal to the controller317.

In an embodiment, the calibration attributes316may be generated by a uniformity algorithm318. The uniformity algorithm318may be an algorithm that is stored in a memory of the tool100. Particularly, metrology data319is used to inform the uniformity algorithm318. The metrology data319may be generated by a metrology chamber386or the like. For example, metrology data (e.g., film thicknesses) from three or more substrates with different emissivities may be used in order to provide data for the uniformity algorithm318.

In an embodiment, the uniformity algorithm318may include a physics based model for the thermal heat sources and a replication of the algorithm that converts the pyrometer sensor data into temperature values for the controller. The physics based model may be a thermal model of the chamber285. That is, the heat sources, and the different components of the chamber285are modeled using physics based equations (e.g., heat transfer equations) in order to provide an accurate thermal model of the chamber285. The thermal model can then be used in order to calculate the backside temperatures of the substrate at different times during the recipe. The calculated temperatures can then be compared to the pyrometer readings in order to determine an offset that is used for the calibration attributes.

Referring now toFIG.4, a process flow diagram of a process490for calibrating a chamber285to be emissivity independent is shown, in accordance with an embodiment. The process490may be executed in the processing environment150using the host computer105and the software101of the tool100. In other embodiments, the entirety of the process490may be implemented by the software101of the tool100, or by the host computer105.

In an embodiment, process490may begin with operation491, which comprises loading a FOUP with three substrates with different emissivities. In an embodiment, more than three substrates may be provided in the FOUP as well. For example, six substrates may be provided in the FOUP, and the six substrates may have three different emissivities (i.e., each emissivity level may be implemented on two substrates). In an embodiment, the substrates may be fabricated in the fab environment. In other embodiments, the substrates may be obtained from an external source of substrates. It is to be appreciated that the substrates may also be recycled or refurbished after the process490so that substrate waste is minimized.

An example of such a FOUP581is shown inFIG.5A. As shown, the FOUP581may include at least three slots571for supporting substrates510. A first substrate510Amay have a layer541with a first emissivity, a second substrate510Bmay have a bottom surface542that is bare silicon with a second emissivity, and a third substrate510Cmay have a layer543with a third emissivity. In an embodiment, the first emissivity may be greater than the second emissivity, and the second emissivity may be greater than the third emissivity. In a particular embodiment, the layer541may comprise nitrogen (e.g., a nitride film), and the layer543may comprise oxygen (e.g., an oxide film). The top surfaces of the substrates510A-510Cmay be bare silicon surfaces in some embodiments. While three substrate510A-510Care shown inFIG.5A, it is to be appreciated that any number of substrates510may be included in the FOUP581.

Returning back to process490inFIG.4, process490may continue with operation492which comprises running a recipe on each of the three substrates with a set of calibration attributes. The calibration attributes may be set prior to running the recipes. Previously used calibration attributes (e.g., before a planned maintenance event, or before hardware changes) may be used to run the recipes. The calibration attributes provide an offset for pyrometer data in order to provide more accurate feedback signals to the controller.

Referring now toFIG.5B, a cross-sectional illustration of a chamber585for executing the process recipe is shown, in accordance with an embodiment. In an embodiment, the chamber585may comprise a chamber body520. The chamber body520may include any suitable material, such as stainless steel, or the like. In an embodiment, a coating (not shown) may be provided over an interior surface of the chamber body520. In an embodiment, gas521may enter the chamber585through a first portion of the chamber body520, and gas522may exit the tool through a second portion of the chamber body520.

In an embodiment, a substrate support515and a susceptor517are provided in the chamber. The substrate support515and the susceptor517are configured to hold and/or secure a substrate510. For example, a first substrate510Ais shown in the chamber585. In an embodiment, the substrate support515and the susceptor517may be configured to rotate. The rotation allows for improved temperature uniformity across the substrate510. In an embodiment, the susceptor517and the substrate support515may comprise a quartz material or another material that is at least substantially transparent to infrared radiation. As such, a temperature of the backside surface of the substrate510can obtained by pyrometers515.

In an embodiment, the chamber585may include a lid525. The lid525may sometimes be referred to as a chamber dome. The lid525may be formed from a material that is at least substantially transparent to infrared radiation. For example, the lid225may comprise quartz or the like. In an embodiment, the chamber285may also include a bottom lid227. The bottom lid227may cover a bottom surface of the chamber285. The bottom lid227may comprise a material that is at least substantially transparent to infrared radiation. As such, pyrometers516on the bottom side of the chamber585can be used to measure a temperature of a bottom surface of the substrate510A.

In an embodiment, a plurality of lamps530may be provided outside the internal volume of the chamber585. In the illustrated embodiment, three sets of lamps530A-530Care provided over a top surface of the lid525. Each of the lamps530A-530Crepresent different lamp regions. The lamps530A-530Cmay be focused on the different zones by a reflector (not shown) that is provided around the lamps530. While one or two lamps530are shown for each zone, it is to be appreciated that any number of lamps may be used to heat each zone of the substrate510A. In the illustrated embodiment, three front-side lamp zones are shown. However, it is to be appreciated that more than three lamp zones may be included in other embodiments. For example, the reflector structure may include four or more zones in order to provide even more enhanced control of the temperature across the surface of the substrate510A.

In an embodiment, the plurality of pyrometers516A-516Cmay be provided through the bottom lid527. The pyrometers516may be focused onto the backside surface of the substrate510A. In an embodiment, the number of pyrometers516may be equal to the number of heating zones on the substrate510A. For example, three heating zones are shown inFIG.5B, and three pyrometers516A-516Care provided.

In an embodiment, a reflectometer518may be situated at the same side as the pyrometers516. The reflectometer518may be used to measure the emissivity of the substrate and provide that information to the algorithm.

In an embodiment, the recipe may be a thermal oxidation recipe. That is, an oxygen source may be flown into the chamber585as the gas521, and the lamps530may be used to rapidly heat the surface of the substrate510A. In an embodiment, the thermal oxidation process may result in the growth of an oxide film545over the top surface of the substrate510A. The recipe may then be repeated for the remaining substrates510Band510C.

Referring back to process490, the process may continue with operation493, which comprises checking a thickness uniformity between the three substrates. In an embodiment, the thickness uniformity may be measured with a line scan tool in order to determine a thickness of the oxide film545across a diameter of the substrates510A-510C. For example, inFIGS.5C-5E, line scans (indicated by the dashed lines) are performed across the first substrate510A(FIG.5C), the third substrate510C(FIG.5D), and the second substrate510B(FIG.5E). The line scan may be done in a metrology chamber186that is coupled to the chamber585through a central chamber183. In other embodiments, the metrology chamber may be a separate tool from the chamber585.

Referring back to process490, the process continues with decision block494which determines if the thicknesses of the oxide layers on the three substrates are uniform. If the thicknesses are uniform, it is determined that the process is emissivity independent, and the process continues to an end block496. In such an embodiment, the calibration attributes are correct, and the tool is considered to be properly calibrated.

However, is the thicknesses are not uniform, the no path is taken and operation495is implemented. Operation495may include updating the set of calibration attributes. In an embodiment, the calibration attributes may be updated through the use of a uniformity algorithm. The uniformity algorithm may include a physics based model for the thermal heat sources and a replication of the algorithm that converts the pyrometer sensor data and reflectometer data into temperature values for the controller. The physics based model may be a thermal model of the chamber585. That is, the heat sources, and the different components of the chamber585are modeled using physics based equations (e.g., heat transfer equations) in order to provide an accurate thermal model of the chamber585. The thermal model can then be used in order to calculate the backside temperatures of the substrate at different times during the recipe. The calculated temperatures can then be compared to the pyrometer readings in order to determine an offset that is used for the updated calibration attributes. In an embodiment, the process490may then continue back to the beginning of the process490and operations491-495can be repeated until the thicknesses of the different substrates are uniform.

In an embodiment, the processing operations491-494may be implemented at the direction of the host computer105, and the updating of the calibration attributes can be implemented by the software101of the tool100. In other embodiments, the entire process490may be implemented by the host computer105, or the entire process490may be implemented by the tool100.

Referring now toFIG.6, a block diagram of an exemplary computer system600of a processing tool is illustrated in accordance with an embodiment. In an embodiment, computer system600is coupled to and controls processing in the processing tool. Computer system600may be connected (e.g., networked) to other machines in a Local Area Network (LAN), an intranet, an extranet, or the Internet. Computer system600may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system600may be a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated for computer system600, the term “machine” shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

In an embodiment, computer system600includes a system processor602, a main memory604(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 memory606(e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory618(e.g., a data storage device), which communicate with each other via a bus630.

System processor602represents 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 processor602may 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 processor602is configured to execute the processing logic626for performing the operations described herein.

The computer system600may further include a system network interface device608for communicating with other devices or machines. The computer system600may also include a video display unit610(e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device612(e.g., a keyboard), a cursor control device614(e.g., a mouse), and a signal generation device616(e.g., a speaker).

The secondary memory618may include a machine-accessible storage medium632(or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software622) embodying any one or more of the methodologies or functions described herein. The software622may also reside, completely or at least partially, within the main memory604and/or within the system processor602during execution thereof by the computer system600, the main memory604and the system processor602also constituting machine-readable storage media. The software622may further be transmitted or received over a network620via the system network interface device608. In an embodiment, the network interface device608may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

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.