CONDITION BY PLASMA SPECTRUM

BACKGROUND

Field

[0001] Embodiments of the present invention generally relate to statistical process controls (SPC) for a PECVD system and process, and more particularly to use of dynamic plasma intensity data for use in SPC.

Description of the Related Art

[0002] Dynamic plasma lifting, known in a PECVD process as powerlift (“PL”), is a process for the elimination of electrostatic charge on a substrate during plasma deposition. In this process, a plasma is ignited and then the gap between two electrodes (e.g., a first electrode and a bottom or chucking electrode) are moved relative to each other. At the end of the PL process, the substrate is lifted up and apart from the second electrode.

[0003] When measuring the plasma intensity across multiple wavelengths associated a PL process with, for example a spectrum analyzer, plasma intensity typically decreases as the gap between electrodes grows wider. Generally, the plasma spectrum will follow this same pattern, namely, the spectrum will show a decrease in intensity as electrodes separate.

[0004] However, because of the dynamic nature of the plasma spectrum during the PL process (or other process in which at least two electrodes are changing their position relative to each other), there is no method to utilize the dynamic data provided during this process to improve processes controlling a PECVD process.

[0005] For detection of contaminates in a given process, plasma intensity isn’t typically used. There are typically no changes in plasma intensity if a small amount of external gas contaminates a process. Moreover, as described above, due to the dynamic nature of plasma intensity during a PL process, rapidly changing intensity data is typically considered to be unstable, and unreliable for contamination detection. [0006] Therefore, what is needed are methods and systems to utilize dynamic plasma intensity data generated when two electrodes are moving relative to each other, such as in a PL process, deposition process, chamber cleaning process, or other process in which two electrodes are moving relative to each other.

SUMMARY

[0007] Disclosed embodiments generally relate to a method for detecting abnormalities in a PECVD process including changing a plasma intensity in a chamber by moving a second electrode relative to a first electrode, providing a wavelength range over which to measure a changing plasma intensity, defining a function that describes the changing plasma intensity over the wavelength range, and displaying an SPC reference based on the function, the SPC reference comprising one of a maximum, a minimum, an average, a median, a mode, and a mean value of one of the function, a derivative of the function, and an integral of the function.

[0008] Alternate embodiments generally relate to A system for detecting an abnormality in a PECVD process, including a PECVD chamber, and a spectrum analyzer configured to measure plasma intensity coupled to the PECVD chamber, the spectrum analyzer configured to perform a method for detecting an abnormality, the method including changing a plasma intensity in a chamber by moving a second electrode relative to a first electrode, providing a first wavelength range over which to measure a changing plasma intensity, defining a function that describes the changing plasma intensity over the first wavelength range, and extract at least one value from the function, the at least one value comprising one of a maximum, a minimum, an average, a median, a mode, and a mean of one of the function, a derivative of the function, and an integral of the function.

[0009] Further embodiments generally relate to A non-transitory computer readable medium containing computer readable instructions for detecting abnormalities in a PECVD process, the method including changing a plasma intensity in a chamber by moving a second electrode relative to a first electrode, providing a first wavelength range over which to measure a changing plasma intensity, defining a function that describes the changing plasma intensity over the first wavelength range, extract at least one value from the function, the at least one value comprising one of a maximum, a minimum, an average, a median, a mode, and a mean of one of the function, a derivative of the function, and an integral of the function.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

[0011] FIG. 1 depicts a deposition system according to disclosed embodiments.

[0012] FIG. 2 depicts multiple plasma intensity measurements taken during a PL process, according to disclosed embodiments.

[0013] FIG. 3 depicts group of plots representing sample traces of plasma intensity measurements and SPC plots of sample trace data, according to disclosed embodiments.

[0014] FIG. 4 depicts a group of plots, of multiple sample curves representing a region of changing plasma intensity, and a plot of a statistical value representing each sample curve in an SPC graph, according to disclosed embodiments.

[0015] FIG. 5 depicts a method of process control and monitoring in a dynamic plasma condition, according to disclosed embodiments.

[0016] FIG. 6 depicts a computer system for process control and monitoring in a dynamic plasma-lifting condition, according to disclosed embodiments. [0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0018] In the following, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the disclosure. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

[0019] The present disclosure generally relates to methods and systems for using dynamic plasma intensity data for the detection of abnormalities such as external gasses, contaminates, particles, chamber anomalies, process anomalies, or other conditions that may cause a change in plasma spectral intensity, in a PECVD process. The disclosure generally describes a process control and chamber monitoring method in which plasma intensity spectrum data obtained during a dynamic plasma condition such as a PL process, chamber cleaning, deposition, or other process in which the upper and lower electrode move relative to each other, is used to design one or more functions that fits one or more runs of a grouping of intensity values over one or more wavelength ranges. From these functions, discrete values representing statistical data derived from the function (e.g., average, mean, median, mode, maximum, minimum, of data values, data derivatives, and/or data integrals, etc.) are developed for each run, with the statistical data used to populate a statistical process control chart, to develop a reference statistical trace. In one or more subsequent processing runs, additional functions are designed and statistical data is derived for each run, comparing these to the reference trace. Differences seen, if any, in the subsequent runs may indicate the presence of one or more abnormalities in the processing runs.

[0020] Figure 1 depicts a deposition system 100 according to disclosed embodiments. The deposition system 100 includes a first electrode 110, a second electrode 120, a spectrum analyzer 130, and a statistical process control (SPC) computer 140. Although FIG. 1 depicts the first electrode as a top electrode and the second electrode 120 as the bottom electrode, in some embodiments the first electrode 110 may be the bottom electrode while the second electrode 120 is the top electrode. The SPC computer 140 and spectrum analyzer may be part of the same physical computer system in some embodiments, while in others, the SPC computer maybe a separate computer system. The SPC computer 140 may be a physical or virtual computer system, or a combination of physical and virtual components.

[0021] The deposition system 100 may be any type of deposition system capable of striking a plasma, and capable of providing relative movement between the first electrode 110 and second electrode 120. The first electrode 110 and second electrode 120 may move relative to each other to create a dynamic plasma condition, such as for example during a plasma-lifting condition, sometimes known as a powerlift (“PL”) process, which may be performed to eliminate electrostatic charge on a substrate during a plasma deposition process. Additional dynamic plasma conditions may include any processes in which the first and second electrode move relative to each other. During this process, a plasma is ignited between the electrodes, and the gap between the electrodes is gradually increased until the substrate is lifted up from, and apart from, the second electrode 120. There may be other plasma-deposition processes that cause the first electrode 110 and second electrode 120 to move relative to one another, such as for example plasma-cleaning and chamber plasma-seasoning processes, which may utilize the techniques disclosed herein. For simplicity, any such process will be referenced as a PL process herein. In some embodiments, only the first electrode 110 may move, only the second electrode 129 may move, and in other embodiments, both electrodes may move.

[0022] Although a spectrum analyzer 130 is specifically mentioned here, any type of measurement device or sensor capable of measuring changing plasma intensity values over time during a PL process may be utilized in embodiments of the techniques disclosed herein.

[0023] Figure 2 depicts multiple plasma intensity measurements 200 taken during a PL process, according to disclosed embodiments.

[0024] During a PL process, the spectrum analyzer 130 will measure multiple plasma intensity traces over time as the first electrode 110 and second electrode 120 move relative to each other. In a given set of traces, there may be one or more regions exhibiting a localized increase (or decrease) in plasma intensity, measured in wavelength or relative intensities, typically measured in intensity counts, in some embodiments, when the electrodes move relative to each other. A first region 210, for example, has a first step 215, a second step 220, and a third step 225, that are measured at different points in time as the electrodes separate, causing a reduction in plasma intensity in the first region 210. Concomitantly, as the first electrode 110 and second electrode 120 move towards each other, the plasma intensity in the first region 210 may in some embodiments increase. In this increasing example, the thirst step 225 may represent a measurement at a first point in time, the second step 220 a second point in time, while the first step 215 would be the measurement taken at a third point in time. Although three measurements are shown here, it will be appreciated that any number of measurements of plasma intensity over time in local regions of a spectrum may be taken and utilized according to embodiments described herein.

[0025] Figure 3 depicts group of plots 300 representing sample traces of plasma intensity measurements and SPC plots of the sample traces, according to disclosed embodiments. A first spectral plot 305 of multiple plots representing changing plasma intensity over time for multiple runs in a given chamber, for a region of region of interest of a spectral reading of a region, such as first region 210 of FIG. 2. The plots are constructed from a PN function:

[0026] Rl is the relative intensity measured from a selected wavelength range which in some embodiments could be plasma intensity of a wavelength region, or multiple regions, combined using a mathematical relation such as multiplication or division, while each exponential n coefficient parameter is assigned a “power tuning” value based upon the desired sensitivity of the function, based on gasses present in the process and potential abnormalities that may be present in the process. For example, a sample PN function plotting for obtaining 22 spectral measurement samples from 64Xnm (e.g., 640nm) to 72Xnm (e.g., 720nm), with no assignment of an exponential n coefficient:

[0027] From each plot of the first spectral plot 305, a range of values will be present, indicating the plasma intensity over the period defined by the plot. A sample of a range of values is shown in a circle 307. A statistical value may be derived from the range of values of each plot, such as for example, an average, a median, a mode, a mean, a max value, a min value, or other value capable of reflecting the range of represented values, and/or derivatives or integrals of such values.

[0028] Once the statistical values for each plot of the first spectral plot 305 is determined, the sample range of these values indicated by circle 307 are represented in a first SPC plot 310 by a first SPC reference 312. In the representation shown, a first SPC average 315 is shown, however, this may be any statistical value such as an average, a median, a mode, a mean, a max value, a min value, or other value capable of reflecting the relative value of the represented values, and/or derivatives or integrals of such values. In addition, a first SPC boundary 320 may be utilized to show, for example one or more standard deviations from the first SPC average 315, chosen as appropriate for a chamber and process under evaluation, such as that represented in FIG. 1.

[0029] Once the first SPC reference 312 is provided as above, this data may be used in future runs as a comparison to later-developed data.

[0030] When the chamber is used for processing in a subsequent run, e.g., PECVD process for the production of a semiconductor device or display, additional data from the subsequent run is collected in a manner similar to the above, and shown in a second spectral plot 330. New spectral plot data samples are indicated by open circles at the measurement points, collected for example in a sample region 331. Similar to the discussion above, the statistical values representing the new spectral plot data samples are developed, and second SPC data 333 from sample region 331 is added to the first SPC reference 312 in the first SPC plot 310, to result in a second SPC plot 335, with the statistical values for the new spectral data indicated by open circles on the second SPC plot 335. As can be seen in the second SPC plot 335, at least one value is outside of a second SPC boundary 340, which could indicate abnormalities occurred under the desired SPC boundary condition. The second SPC boundary may be the same as the first SPC boundary 320, and in some embodiments may be a different value. By fixing the SPC boundaries, future data derived from chamber and process spectral data may be measured relative to the first SPC reference 312

[0031] Figure 4 depicts a group of plots 400, of multiple sample curves representing a region of changing plasma intensity which may be combined by specific or designed numerical functions of a particular exponential power, and a plot of a statistical value representing each sample curve in an SPC graph, according to disclosed embodiments.

[0032] The group of plots 400 are developed from a similar PN function as described above, with power tuning applied to the exponential coefficient values. For example, the PN function describing the group of plots 400, with power tuning coefficient values:

[0033] By modifying the power tuning applied to the exponential coefficient values, the PN function may be made more, or less, sensitive to desired chamber and process conditions. As can be seen in in FIG. 3D, only one data point appears to be outside of the first SPC boundary 320. However, by modifying the exponential coefficients of the PN function while using the same sample data values, additional sensitivity is provided in the example data, causing two data points to exceed a second SPC boundary 420. Values chosen for modification of exponential coefficient values of the PN function is chosen for a particular process, chamber, gasses and other materials present within a chamber, etc., so as to provide the desired level of function sensitivity to enable indication of the presence of abnormalities.

[0034] Figure 5 depicts a method 500 of process control and monitoring in a dynamic plasma condition, according to disclosed embodiments.

[0035] At 505 the method changes a plasma intensity in a chamber by moving a second electrode relative to a first electrode, while at 510 the method 500 provides a wavelength range over which to measure the changing plasma intensity.

[0036] At 515 defines a function that describes the changing plasma intensity over the wavelength range. In some embodiments, this is defined by providing a product/ration of a relative intensity having a numerical component defined by the numerical value of the function at a time t, from the first wavelength range, and assigning a first exponential coefficient to the numerical component. In some embodiments, the exponential components may be adjusted such that a second value falls outside of a single standard deviation of the SPC reference.

[0037] At 520 the method displays an SPC reference from the function, the SPC reference comprising one of a maximum, a minimum, an average, a median, a mode, and a mean value of the function, and/or a derivative or integral of the function. [0038] In embodiments, method 500 may further comprise changing a second plasma intensity in the chamber by moving the second electrode relative to the first electrode (or moving the first electrode relative to the second electrode), defining a second function that describes the changing second plasma intensity over the first wavelength range, and displaying at least one second value from the second function, the at least one second value of the function, and/or a derivative or integral of the function, comprising one of a maximum, a minimum, an average, a median, a mode, and a mean of the second function, and/or its derivative or integral. A further embodiment includes comparing the SPC reference to the at least one second value wherein the difference of the SPC reference to the at least one second value indicates the presence of an abnormality, and updating a user display to indicate the presence of the abnormality. These embodiments may include changing the plasma intensity is performed multiple times, to define multiple functions describing changing plasma intensity over the first wavelength range, and extracting at least one value from each respective one of the multiple functions, each at least one value comprising one of a maximum, a minimum, an average, a median, a mode, and a mean of each respective one of the multiple functions, and/or their derivatives or integrals. Embodiments may further include plotting each at least one value from each respective one of the multiple functions to further comprise the SPC reference, wherein the second value is at least one standard deviation from at least one of the at least one value from each respective one of the multiple functions.

[0039] Figure 6 depicts a computer system 600 for process control and monitoring in a dynamic plasma-lifting condition, according to disclosed embodiments, such as embodiments of the method described with respect to FIGs. 1 -5. In some embodiments, SPC computer 140 comprises one or more components of computer system 600.

[0040] Computer system 600 includes a central processing unit (CPU) 602 connected to a data bus 616. CPU 602 is configured to process computer-executable instructions, e.g., stored in memory 608 or storage 610, and to cause the server 601 to perform methods described herein, for example with respect to FIGs. 1-5. CPU 602 is included to be representative of a single CPU, multiple CPUs, a single CPU having multiple processing cores, and other forms of processing architecture capable of executing computer-executable instructions.

[0041] Computer system 600 further includes input/output (I/O) device(s) 612 and interfaces 604, which allows server 601 to interface with input/output devices 612, such as, for example, keyboards, displays, mouse devices, pen input, and other devices that allow for interaction with server 601. Note that server 601 may connect with external I/O devices through physical and wireless connections (e.g., an external display device).

[0042] Computer system 600 further includes a network interface 606, which provides server 601 with access to external network 614 and thereby external computing devices.

[0043] Computer system 600 further includes memory 608, which in this example includes a changing module 618, providing module 620, defining module 622, displaying module 624, comparing module 626, and updating module 628 for performing operations described in FIGs. 1-5.

[0044] Note that while shown as a single memory 608 in FIG. 6 for simplicity, the various aspects stored in memory 608 may be stored in different physical memories, including memories remote from computer system 600, but all accessible by CPU 602 via internal data connections such as bus 616.

[0045] Storage 610 further includes plasma intensity data 630, which may be like the plasma intensity measured, as described in FIGs. 1-5.

[0046] Storage 610 further includes wavelength data 632, which may be like the wavelength range as described in FIGs. 1-5.

[0047] Storage 610 further includes function data 634, which may be like the PN function as described in FIGs. 1-5.

[0048] Storage 610 further includes SPC reference data 636, which may be like the SPC reference as described in FIGs. 1-5. [0049] Storage 610 further includes abnormality data 638, which may be like the abnormalities as described above.

[0050] While not depicted in FIG. 6, other aspects may be included in storage 610.

[0051] As with memory 608, a single storage 610 is depicted in FIG. 6 for simplicity, but various aspects stored in storage 610 may be stored in different physical storages, but all accessible to CPU 602 via internal data connections, such as bus 616, or external connection, such as network interfaces 606. One of skill in the art will appreciate that one or more elements of server 601 may be located remotely and accessed via a network 614.

[0052] The preceding description is provided to enable any person skilled in the art to practice the various embodiments described herein. The examples discussed herein are not limiting of the scope, applicability, or embodiments set forth in the claims. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented, or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0053] As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

[0054] As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

[0055] The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

[0056] The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general- purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0057] A processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and input/output devices, among others. A user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and other circuit elements that are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general- purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

[0058] If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer-readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media, such as any medium that facilitates the transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the computer-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the computer-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the computer-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

[0059] A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During the execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

[0060] The following claims are not intended to be limited to the embodiments shown herein but are to be accorded the full scope consistent with the language of the claims. Within a claim, a reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. §112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.