Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
  • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
  • G05B19/41865—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by job scheduling, process planning, material flow

Definitions

• This invention relates generally to an industrial process, and, more particularly, to various methods and systems for dynamically adjusting metrology sampling based upon available metrology capacity
• One technique for improving the operation of a semiconductor processing line includes using a factory wide control system to automatically control the operation of the va ⁇ ous process tools
• the manufacturing tools communicate with a manufacturing framework or a network of processing modules
• Each manufacturing tool is generally connected to an equipment interface
• the equipment interface is connected to a machine interface that facilitates communications between the manufacturing tool and the manufacturing framework
• the machine interface can generally be part of an advanced process control (APC) system
• APC advanced process control
• the APC system initiates a control script based upon a manufacturing model, which can be a software program that automatically retrieves the data needed to execute a manufacturing process
• semiconductor devices are staged through multiple manufacturing tools for multiple processes, generating data relating to the quality of the processed semiconductor devices
• va ⁇ ous events may take place that affect the performance of the devices being fabricated That is, variations in the fabrication process steps may result in variations of the features that comprise the device as well as device performance variations Factors, such as feature critical dimensions, doping levels, contact resistance, particle contamination, etc , all may potentially affect the end performance of the device
• Various tools in the processing line are controlled in accordance with performance models to reduce processmg va ⁇ ation
• Commonly controlled tools include photolithography steppers, polishing tools, etching tools, and deposition tools
• Pre-processing and/or post-processing metrology data is supplied to process controllers for the tools
• Operating recipe parameters, such as processing time are calculated by the process controllers based on the performance model and the metrology information to attempt to achieve post ⁇ processing results as close to a target value as possible Reducing variation in this manner leads to increased throughput, reduced cost, higher device performance, etc , all of which equate with increased profitability
• Target values for the various processes performed are generally based on design values for the devices being fabricated
• a particular process layer may have a target thickness
• Operating recipes for deposition tools and/or polishing tools may be automatically controlled to reduce va ⁇ ation about the target thickness
• the c ⁇ tical dimensions of a transistor gate electrode may have an associated target value
• the operating recipes of photolithography tools and/or etch tools may be automatically controlled to achieve the target critical dimensions
• a control model is used to generate control actions for changing the operating recipe settings for a process tool being controlled based on feedback or feedforward metrology data collected related to the processing by the process tool
• a control model must be provided with metrology data in a timely manner and at a quantity sufficient to maintain its ability to predict the future operation of the process tool it controls
• a typical semiconductor manufacturing facility may devote a great deal of resources to obtaining such metrology data
• a modern semiconductor manufacturing facility will have many metrology tools or stations where a variety of metrology operations are performed
• Illustrative metrology data may include the thickness of a process layer, a critical dimension of a feature formed above a substrate, a plana ⁇ ty of a surface, etc
• Some metrology tools are dedicated to performing only one type of metrology operations, e g , critical dimension measurements, whereas other metrology tools are capable of performing multiple metrology operations
• a typical semiconductor manufacturing facility may have multiple tools capable of performing the same metrology operation
• metrology sampling rates are established for va ⁇ ous process operations
• the sampling rates may vary depending upon a variety of factors, such as the c ⁇ ticahty of the particular process, eg , gate etch processes, and/or how stable the process operations are in terms of controllability
• metrology sampling rates are typically set below a level where the aggregate of all of the products selected for sampling would completely utilize all available metrology capacity This may generally be referred to as baseline sampling rates
• the baseline sampling rates are set at less than maximum levels to allow the metrology tools to "catch-up" to accumulated work-in-progress (WIP) after one or more of the metrology tools have been taken out of service for a variety of reasons, e g , routine maintenance, an unscheduled problem with one of the metrology tools, etc For example, if one out of four available metrology tools is taken out of service, the work-m-progress (WIP) would slowly accumulate in the metrology queues until the out-of-service metrology tool is returned to service At that time
• An alternative method of addressing changes in metrology capacity is to maintain sampling rates at very high levels that result in nearly full utilization of all metrology tools under normal production
• the sampling rates may be manually lowered to reduce the amount of work-in-progress (WIP) accumulating in the metrology queues
• WIP work-in-progress
• the present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above
• the present invention is generally directed to various methods and systems for dynamically adjusting metrology sampling based upon available metrology capacity
• the method comp ⁇ ses providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, and providing the determined available metrology capacity to the metrology control unit wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity.
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comprises determining a number of metrology tools that are currently available as compared to a total number of metrology tools that are generally available, wherein all of the metrology tools are assumed to be completely interchangeable, providmg the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, and performing additional metrology operations in accordance with the new metrology sampling rate
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comp ⁇ ses determining a number of metrology tools that are currently available for performing a specific metrology operation as compared to a total number of metrology tools that are generally available for performing the specific metrology operation, wherein all of the metrology tools are adapted to perform at least the specific metrology operation, providing the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, and performing additional metrology operations in accordance with the new metrology sampling rate
• the method comp ⁇ ses providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comp ⁇ ses determining metrology tools that are available for performing the at least one metrology operation and at least a second metrology operation that is different from the at least one metrology operation, providing the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, wherein, in determining the new metrology sampling rate, a sampling rate for the second metrology operation is reduced to thereby free up additional metrology capacity for performing the at least one metrology operation, and performing additional metrology operations in accordance with the new metrology sampling rate
• FIG. 1 is a simplified block diagram of a manufacturing system in accordance with one illustrative embodiment of the present invention
• FIG. 2 is a simplified block diagram of a more detailed depiction of a system in accordance with one illustrative embodiment of the present invention.
• Figure 3 is a simplified flow diagram of a method of controlling metrology sampling m accordance with one illustrative embodiment of the present invention
• FIG. 1 a simplified block diagram of an illustrative manufacturing system 10 is provided
• the manufacturing system 10 is adapted to fabricate semiconductor devices
• the invention is desc ⁇ bed as it may be implemented in a semiconductor fabrication facility, the invention is not so limited and may be applied to other manufacturing environments
• the techniques described herein may be applied to a variety of workpieces or manufactured items
• the present invention may be employed in connection with the manufacture of a variety of integrated circuit devices, including, but not limited to, microprocessors, memory devices, digital signal processors, application specific integrated circuits (ASICs), or other devices
• the techniques may also be applied to workpieces or manufactured items other than integrated circuit devices
• a network 20 interconnects various components of the manufacturing system 10, allowing them to exchange information
• the illustrative manufacturing system 10 includes a plurality of tools 30-80 Each of the tools 30-80 may be coupled to a computer (not shown) for interfacing with the network 20
• the tools 30-80 are grouped into sets of like tools, as denoted by lettered suffixes
• the set of tools 30A-30C represent tools of a certain type, such as a chemical mechanical plana ⁇ zation tool
• a particular wafer or lot of wafers progresses through the tools 30-80 as it is being manufactured, with each tool 30-80 performing a specific function in the process flow
• Exemplary processing tools for a semiconductor device fabrication environment include metrology tools, photolithography steppers, etch tools, deposition tools, polishing tools, rapid thermal anneal tools, implantation tools, etc
• the tools 30-80 are illustrated in a rank and file grouping for illustrative purposes only In an actual manufacturing facility, the tools 30-80 may be arranged in any physical order or grouping Additionally
• a manufacturing execution system (MES) server or controller 90 directs high level operation of the manufacturing system 10
• the MES server 90 may monitor the status of the various entities in the manufacturing system 10 ( ⁇ e , lots, tools 30-80) and control the flow of articles of manufacture (e g , lots of semiconductor wafers) through the process flow
• a database server 100 is provided for storing data related to the status of the various entities and articles of manufacture m the process flow
• the database server 100 may store information in one or more data stores 1 10
• the data may include pre-process and post-process metrology data, tool states, lot priorities, operating recipes, etc
• the controller 90 may also provide operating recipes to one or more of the tools depicted in Figure 1 or command that various operating recipes be performed in one or more of the tools Of course, the controller 90 need not perform all of these functions.
• the functions described for the controller 90 may be performed by one or more computers spread throughout the system 10.
• calculating or “determining” or “displaying” or the like refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities withm the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices
• the manufacturing system 10 also includes a metrology control unit 12 executing on an illustrative workstation 150
• the metrology control unit 12 may be used to control various metrology tools employed in connection with manufacturing operations performed in the manufacturing system 10.
• the metrology control unit 12 may communicate with the controller 90 and/or with one or more process controllers 145 associated with the individual tools 30-80 for purposes to be described later herein
• the particular control models used by the process controllers 145 depend on the type of tool 30-80 being controlled
• the control models may be developed empirically using commonly known linear or non-linear techniques
• the control models may be relatively simple equation-based models (e g , linear, exponential, weighted average, etc ) or a more complex model, such as a neural network model, principal component analysis (PCA) model, partial least squares projection to latent structures (PLS) model
• PCA principal component analysis
• PLS partial least squares projection to latent structures
• An exemplary information exchange and process control framework suitable for use in the manufacturing system 10 is an Advanced Process Control (APC) framework, such as may be implemented using the Catalyst system formerly offered by KLA-Tencor, Inc
• the Catalyst system uses Semiconductor Equipment and Mate ⁇ als International (SEMI) Computer Integrated Manufacturing (CIM) Framework compliant system technologies and is based the Advanced Process Control (APC) Framework CIM (SEMI E81-0699 - Provisional Specification for CIM Framework Domain Architecture) and APC (SEMI E93-0999 - Provisional Specification for CIM Framework Advanced Process Control Component) specifications are ' publicly available from SEMI, which is headquartered in Mountain View, CA
• FIG. 2 is a more specific, simplified block diagram of a metrology system 50 in accordance with one illustrative embodiment of the present invention
• the metrology control unit 12 is operatively coupled to a plurality of metrology tools 14
• the illustrative metrology tools 14 may perform one or more of a variety of metrology operations
• the metrology tools 14 may perform metrology operations such as measuring the thickness of a process layer, measuring a critical dimension of a feature, measuring the plana ⁇ ty of a surface, film resistivity, film optical properties (e g , n and k), defectivity, overlay alignment, etc
• the metrology system 50 may be employed to automatically adjust or control metrology sampling rates based on available metrology tool capacity
• the metrology tools 14 perform generally the same type of metrology operation, e g , measuring the thickness of a layer, measuring the critical dimension of a feature, etc
• the metrology tools 14 are not necessarily completely interchangeable for all metrology
• the metrology control unit 12 also has the ability to implement some constraints on the resulting sampling rate plans For example, a constraint may be applied that the sampling rate for a given process operation will not be allowed to fall below a preselected limit, e g , a minimum sampling rate of 75% may be established for a critical process
• the metrology control unit 12 may employ various control algorithms to control metrology operations performed by the metrology tools 14 within the 35 metrology system 50
• a first control algo ⁇ thm is employed wherein all of the metrology tools 14 of a given type are assumed to be completely interchangeable In that case, when one or more of the metrology tools 14 are not in service (for whatever reason), a new or adjusted metrology sampling rate for each operation may be determined as follows
• Rate, new Rate, base ⁇ (1)
• Rate, nev/ represents the new metrology sampling rate at operation ⁇
• Rate, oase represents the baseline metrology sampling rate at operation ⁇
• N Total represents the total number of metrology tools 14 that are normally available to perform metrology operations
• a second algorithm may be employed by the metrology system 50
• the metrology control unit 12 only considers or counts metrology tools 14 that can be used for a specific metrology operation
• the metrology control unit 12 may only consider metrology tools 14 that can perform critical dimension measurements
• the new or adjusted metrology sampling rate may be determined as follows r % i n ⁇ N ' Available
• Rate, new Rate, base — (2)
• Equation 1 Rate ⁇ new and Rate, ⁇ , ase are defined as above
• N l Am , ⁇ a ⁇ , ⁇ e represents the number of metrology tools 14 currently available for metrology operation ⁇
• N, Tolal represents the total number of tools 14 that are normally available for metrology operation i
• the first algorithm (Equation 1) is a subset of the second algorithm (Equation 2) for the special case where all metrology tools 14 are available for all metrology operations
• One benefit of the second algorithm is that it is computationally simple
• One potential drawback with respect to the second algorithm is that it does not allow the reduction of metrology sampling rates at operations other than those that are run on the metrology tool 14 that is down For example, if metrology operation y is not run by a down metrology tool, the second algorithm would not allow the sampling rate at metrology operation j to be reduced in order to free up capacity to run metrology operation ;
• a third control algorithm may be employed by the metrology system 50 Using the third algorithm, the metrology control unit 12 may modify sampling rates at metrology operations other than those that are performed by a metrology tool 14 that has been taken out of service This methodology allows maintenance of metrology sampling rates that are (on average) relatively close to the baseline metrology sampling rates for all metrology operations when all metrology tools 14 are available In this methodology, the first step is to generate an aggregate sampling rate This is the sum of all individual metrology sampling rates across all metrology operations
• Rate To ⁇ i is the aggregate rate
• N is the total number of metrology operations allowable for metrology tools 14 of that type (e g , thickness measurement, critical dimension measurement)
• Rate is the baseline sampling rate at the operation /
• Rate ⁇ o ⁇ i is defined as above, Rate A v a i lab l e 1S the new available capacity, N Avmlab ⁇ e is the number of available metrology tools 14, and N Tola ⁇ is the total number of metrology tools 14 that could potentially be available for that metrology type
• type refers to a group of metrology tools that can be used to perform the same metrology operations For example, irrespective of the manufacturer of the metrology tools, if several tools can perform the same metrology operation, e g , film thickness, then all of those tools would be considered to be of the same type
• the final step is to solve the following equation
• the third algorithm minimize the square of the deviation of the new metrology sampling rates ⁇ Rate, new ) from the baseline metrology sampling rates (Rate, hase ) subject to the constraint of available metrology capacity (Rate Ava , ⁇ ab ⁇ e )
• the benefit of this third methodology is that it allows for small reductions in metrology sampling rates across multiple operations to address reductions in metrology capacity
• solving this third algorithm is much more computationally complex than the other two algorithms discussed above
• the aggregate rate (Rater ota i) was used as a surrogate for total metrology capacity This is usually a good estimate if the time to measure a lot of wafers does not vary greatly from one operation to another In cases where measurement time does vary greatly, a modified equation may be used that incorporates those time differences As one illustrative example, the modified equation could be
• Time represents the cycle time of a lot at operation i and all other variables are defined as above
• the present invention is generally directed to various methods and systems for dynamically adjusting metrology sampling based upon available metrology capacity
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, and providing the determined available metrology capacity to the metrology control unit wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comprises determining a number of metrology tools that are currently available as compared to a total number of metrology tools that are generally available, wherein all of the metrology tools are assumed to be completely mterchangeable, providing the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, and performing additional metrology operations in accordance with the new metrology sampling rate
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comprises determining a number of metrology tools that are currently available for performing a specific metrology operation as compared to a total number of metrology tools that are generally available for performing the specific metrology operation, wherein all of the metrology tools are adapted to perform at least the specific metrology operation, providing the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, and performing additional metrology operations in accordance with the new metrology sampling rate
• the method comprises providing a metrology control unit that is adapted to determine a baseline metrology sampling rate for at least one metrology operation, determining available metrology capacity, wherein the step of determining available metrology capacity comprises determining metrology tools that are available for performing the at least one metrology operation and at least a second metrology operation that is different from the at least one metrology operation, providing the determined available metrology capacity to the metrology control unit, wherein the metrology control unit determines a new metrology sampling rate based upon the determined available metrology capacity, wherein, in determining the new metrology sampling rate, a sampling rate for the second metrology operation is reduced to thereby free up additional metrology capacity for performing the at least one metrology operation, and performing additional metrology operations in accordance with the new metrology sampling rate

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
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• Quality & Reliability (AREA)
• Automation & Control Theory (AREA)
• General Physics & Mathematics (AREA)
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• General Engineering & Computer Science (AREA)
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