HIIIIIIIIIIII|||||||l||||||||||l||||Illll|||i||||l||l||||l||||||||||||i|||
`
`USOOS761064A
`
`Ulllted States Patent
`
`[19]
`
`[11] Patent Number:
`
`9
`a
`5 761 064
`
`La et a].
`[45] Date of Patent:
`Jun. 2, 1998
`
`
`[54] DEFECT MANAGEMENT SYSTEM FOR
`PRODUCTIVITY AND YIELD
`[IMPROVEMENT
`
`[75]
`
`Inventors: Th0 Le La; Y'mg Shin“. both of San
`Jose. Calif.
`
`4/1993 Ekstedt et a],
`5,206,582
`......................... 324/73.1
`
`
`5,355,320 10/1994 Erjavic et a1. .......... 364/488
`
`2/1995 Rhodes ................ 3641480
`5,390,129
`
`5,511,005
`4/1996 Abbe et al.
`..... 364/552
`5,598,341
`1/1997 Ling 8131 .............................. 364/468
`FOREIGN PATENT DOCUMENTS
`
`[73] Assignee: Advanced Micro Devices, Inc..
`SunnyValC~ Callf-
`
`A—0 654 739
`A1
`
`11/1994 European Pat. on.
`
`GOGF 11/26
`
`[21] Appl. No.: 539,913
`_
`[22] Flledi
`
`OCt- 6; 1995
`
`Int. (21.6 .............................................. G06F 19/00
`[51]
`
`..................
`. 364/468.l7; 364/552
`[52] US. Cl.
`[58] Field of Search ......................... 364/463.17, 468.28.
`364/488—491. 551.01. 552. 554. 480. 481
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`Primary Examiner—James P. Trammell
`Attorney, Agent, or Finn—H. Donald Nelson
`
`[57]
`
`ABSTRACT
`
`An automated wafer defect mnagemem System in which
`wafer defect data are collected from wafer inspection
`instruments. converted into a standard data format and made
`available through a central database system to workstations
`for review. analysis, and evaluation.
`
`4,878,179 10/1989 Larsen et a].
`
`........................... 364/490
`
`40 Claims, 11 Drawing Sheets
`
`U“ an; “26
`
`ANALYSIS
`
`5mm 32
`51
`
`ANALYSIS
`
`STATION
`#2
`
`ANALYSIS
`PC
`WSTAHON
`
`34 -
`
`-
`
`-
`
`ANALYSIS
`PC
`WORKSTATION
`
`ANALYSIS
`
`STATION
`kn
`
`35
`
`ANALYSIS
`PC
`WORKSTATION
`
`42
`
`
`
`USER
`
`#2
`
`WORK—
`STATION
`
`52
`
`WORK STREAM
`DATABASE
`
`ELECTRICAL
`TEST
`
`DATABASE
`
`Linear Exhibit 1025
`
`

`

`IIII
`bl
`
`ANALYSIS
`STATION
`#1
`
`32
`
`
`
`ANALYSIS
`STATION
`#2
`
`34
`
`' ' '
`
`ANALYSIS
`STATION
`if“
`
`35
`
`ANALYSIS
`
`PC
`
`ANALYSIS
`
`PC
`
`ANALYSIS
`
`PC
`
`WORKSTATION
`
`WORKSTATION
`
`WORKSTATION
`
`38
`
`40
`
`42
`
`28
`
`30
`
`SERVER
`
`2Q
`
`E:
`{/1
`bu
`a
`(b
`5H.
`
`a
`g
`
`.N
`
`:3
`g
`
`U)
`{5'
`£3.
`3H:
`
`I790‘I9L‘S
`
`ELECTRICAL
`
`TEST
`
`DATABASE
`
`WORKSTREAM
`
`DATABASE
`
`44
`
`46
`
`USER
`
`USER
`
`USER
`
`INTERFACE
`
`INTERFACE
`
`INTERFACE
`
`WORK‘
`
`STATION
`
`WORK»
`
`STATION
`
`WORK-
`
`STATION
`
`

`

`22
`
`24
`
`26
`
`ANALYSIS
`
`STATION
`#1
`
`32
`
`ANALYSIS
`
`STATION
`#2
`
`34
`
`ANALYSIS
`
`-
`
`STATION
`{"1
`
`35
`
`38
`
`ANALYSIS
`
`PC
`
`ANALYSIS
`
`PC
`
`WORKSTATION
`
`WORKSTATION
`
`40“
`
`60
`
`62
`
`64
`
`ANALYSIS
`
`PC
`
`WORKSTATION
`
`42
`
`
`
`INTERFACE
`WORK-
`
`STATION
`
`ELECTRICAL
`
`WORKSTREAM
`
`DATABASE
`
`TEST
`
`DATABASE
`
`
`
`mama'S'n
`
`866T‘Z"Inf
`
`IIJ0Zmus
`
`1790‘I9L‘S
`
`

`

`1;;
`
`130
`
`HP
`APPOLLO
`735
`SERVER
`
`DISK
`STORAGE
`
`82
`
`—-—- 0—— I—I- —
`
`PC
`INTERFACE
`WORKSTATION
`
`124:—I
`|
`
`|
`
`125 |
`
`1119184ST]
`
`E“
`:3
`
`§co
`
`Ch
`
`g
`3
`c,
`3
`
`I790‘I9L‘S
`
`___T23"—_‘I
`|
`I
`I
`
`PC
`WORKSTATION
`
`PC
`WORKSTATION
`
`118
`
`I 22
`
`BIT MAP
`STAGE
`CONTROLLER
`
`116
`
`MICRO SCOP
`
`I I |
`
`__._..__
`ss—I
`
`72
`
`r——_
`
`I l l | | 1
`
`PC
`I
`INTERFACE
`I
`WORKSTATION
`5116111131112 _ _
`AK... _|
`
`74
`
`mfi”*7
`IggEETR
`I
`TEST
`I
`I
`I
`I
`.1
`
`L...‘
`
`-_68—
`
`75
`
`73
`
`66
`
`ANALYSIS
`STATION
`
`114
`
`102
`
`I H
`|
`I
`I
`|
`110
`I W
`L _____
`
`I— _ —34— -94 _ :34- _ —
`ESTEK
`ANALYSIS
`8500
`STATION
`
`913
`
`86
`95
`INSPEX fl
`8510
`
`108
`
`102
`
`

`

`140
`
`
`
`nmm
`Illfllllll
`
`llllllllllll
`IISIHIMIZII
`
`III!|II|IIII'III
`IIH‘IIHHHII
`
`Illlllllllllllléll
`
`IIIIIIHHHIIIIII
`
`IIIIIIIIHIIIIIHI
`V
`. ,.
`Ilfllllflilaliuinll
`
`"'35'!!!“!'!‘i=!.”
`Hmiiifli’éfiiii
`
`IIIIEIIIHIiIhiif
`ll!l:!!:l.il|!l|
`
`"IHEIIMIHI
`
`II'IMiIHlH
`IIEIIISHIII
`
`IEIIIIIIII
`
`llllllll
`
`
`133
`
`140
`
`138
`
`\ I:!IIII§1:"'"""
`IIIIIIIIIIIIIIIII
`,
`IIIIIIIII »
`9. nu
`‘45 mum". .Illlll
`lllllllllll ‘
`~ * llllll
`IIIIIIIIIIIII
`,
`IIIIIIIIIIIIIIIIIIIII
`
`
`
`
`134
`
`
`
`mama'90
`
`8661“Z1111f
`
`IIJO17Walls
`
`I790‘I9L‘s
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 5 of 11
`
`5,761,064
`
`
`
`
`IIIIIIII
`
`
`mama:
`llilllllll
`
`
`suaaaauanm:
`JIIIIIIIIIII
`
`Illlllllll ‘ O b»: Illlllllll
`\
`iillllililgl"
`
`*
`:
`IlllllllillIEEll
`
`IIIISIIIIIIIEIII
`lllllilllllilllill
`
`
`154
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 4
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 6 of 11
`
`5,761,064
`
`Layer Trend Chart for Percent Bod Dies
`
`MM‘U
`
`m<-40m~1mo
`
`W
`K
`1
`2
`
`W
`K
`1
`I5
`
`#uxi
`
`maxi
`
`maxi
`
`u-axi
`
`maxi
`
`odxfi
`
`omxs
`
`amxi
`
`MM‘xi
`
`umxi
`
`+Mx£
`
`FIG. 5
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 7 0f 11
`
`5,761,064
`
`BOX CHART for Percent Bud Dies
`
`100
`
`ZDEFECTWESDIES
`
`1MECD
`
`SDFI
`
`2MECD SMECD ZGFI
`
`2TTNE
`
`LAYERS
`
`FIG. 6
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 8 of 11
`
`5,761,064
`
`BOX CHART for Percent Bod Dies
`
`100
`
`ZDEFECTIVESDIES
`
`90
`
`80
`
`7O
`
`60
`
`1D
`
`50
`
`4O
`
`30
`
`20
`
`WK17 WK1B WK19 WK20 WK21 WK22
`
`FIG. 7
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 9 0f 11
`
`5,761,064
`
`LAYER COMPARISION CHART for Percent Bad Dies
`
`%DEFECTIVEDIES
`
`Calendar Week
`
`WK25
`
`I 1BMD I 2BMD
`
`I 38MB
`
`El BOX2
`
`EIPD2
`
`FIG. 8
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 10 of 11
`
`5,761,064
`
`LAYER BAR CHART for Defect Count
`
`300
`
`200
`
`100
`
`
`
`zDEFECTCOUNT
`
`269.5
`
`
`
`111.5
`
`175.7
`
`166.4
`
`
`
`11.6
`
`7.0
`
`0
`
`PD2
`
`1BMD
`
`ZBMD
`
`PWF!
`
`JBMD
`
`ZLFI
`
`NWFI
`
`FIG. 9
`
`

`

`US. Patent
`
`Jun. 2, 1998
`
`Sheet 11 of 11
`
`5,761,064
`
`LAYER BAR CHART for Percent Bod Dies
`
`7.DEFECTIVEDIES
`
`FIG. 10
`
`

`

`1
`DEFECT MANAGEMENT SYSTEM FOR
`PRODUCTIVITY AND YIELD
`IMPROVEMENT
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates generally to semiconductor wafer
`manufacturing. and. more particularly.
`to an automated
`semiconductor wafer defect management system for pro-
`ductivity and yield improvement.
`2.’ Discussion of the Related Art
`
`Growing technological requirements and the worldwide
`acceptance of sophisticated electronic devices have created
`an unprecedented demand for large—scale. complex. inte-
`grated circuits. Meeting these demands has required tech—
`nological advances in materials and processing equipment.
`significant increases in the number of individuals involved
`in integrated circuit design. and an increased emphasis on
`eifectively utilizing the computer and other highly sophis-
`ticated equipment to aid. not only in the design. but in the
`analysis of the manufacturing process.
`The microscopic dimensions capabilities of current semi-
`conductor manufacturing equipment make possible the
`design of digital circuits which may be very complex and yet
`extremely economical in space. power requirements and
`cost. and which are potentially very fast. At the same time.
`however. the microscopic dimensions of current semicon-
`ductor manufacturing also make it possible for microscopic
`particles to contaminate and ruin an extended run of wafers
`before the contamination is discovered causing major eco-
`nomic loss. It is therefore critical that there is a method to
`discover. not only that there are defects in the wafer manu-
`facturing process. but to determine exactly what is causing
`those defects. To avoid extensive economic loss it is man-
`datory to discover these defects as quickly as possible and as
`close to real time as possible.
`The character of the semiconductor industry is such that
`competition requires that products are designed.
`manufactured. and marketed in the most efficient manner
`possible. This has required that improvements in fabrication
`technology keep pace with the rapid improvements in the
`electronics industry.
`As advances in semiconductor wafer manufacturing tech-
`nology lead to more sophisticated instruments with
`improved imaging and analysis capabilities. the volume of
`data associated with these instruments has grown faster than
`the ability of standard methods of analysis making wafer
`defect management on a timely basis problematic.
`. Present wafer inspection and failure analysis tools provide
`detailed qualitative and quantitative information about pro-
`cessing defects and the failures caused by them. However.
`each wafer inspection tool produces information not easily
`accessible to the production process engineering commu—
`nity. In a well equipped semiconductor wafer manufacturing
`fab. analytical instruments produce data faster than can be
`manually analyzed by engineers.
`Making semiconductor wafer defect and contamination
`data available on a timely basis throughout the corporate
`engineering community has become just as important. if not
`more important than obtaining the data in the first place.
`The problem is exacerbated by the fact that the intelli-
`gence (the controls. user interface. and data management
`capabilities) integrated into each instrument is dedicated to
`that instrument. Vendors have developed proprietary meth-
`ods for collecting. processing. storing. and outputting data.
`
`5 .761.064
`
`2
`
`and have not established a single set of standards for
`combining data from multiple vendor equipment. Because
`of this. engineers have had to use one stand~alone tool at a
`time making it virtually impossible to efficiently correlate
`wafer defect information concerning the same wafer.
`Because there was no method to correlate wafer defect
`information. another significant problem was that analytical
`results was invariably reduced to the form of paper output—
`even through converted into compact representations such as
`charts. graphs. or high—resolution images. This reduction to
`paper was necessary because there was not a method to
`correlate all
`the information in one format for efficient
`presentation. In addition. not only is paper an inefiicient
`medium for distributing information. it is also a serious
`source of contamination in ultraclean manufacturing envi-
`ronments. Paper fiber. or dust. can contaminate wafers
`during manufacturing.
`Because of the problems associated with wafer defect
`management the inventors were tasked to obtain an auto-
`mated system that would network all wafer defect analysis
`instruments and enable any engineer to access wafer defect
`data on-line from the engineer’s desk without handling
`paper. After an intensive search the inventors were unable to
`find an existing solution. The inventors were then tasked to
`undertake a study to determine the feasibility of developing
`an automated system.
`The first step in the developmental process was to define
`the functional specifications desired in the system. The final
`requirements included detailed specifications for every fea-
`ture and operation of a fully-automated. on-line system.
`The first functional specification concerned connectivity.
`It was determined that an automated system must:
`(1)
`provide for the inter-operability of multiple vendor
`equipment. including the ability to integrate all data and to
`provide access to the integrated data back to any vendor’s
`review station in its native format; (2) provide a data
`translation facility to accommodate native data formats.
`changes. and new tools; and (3) provide total data access
`time from user workstation or from any vendor’s instrument
`review station of not more than three seconds with multiple
`users on—line simultaneously.
`The second functional requirement concerned data
`manipulation. charting. and reporting capabilities. The auto—
`mated system must: (1) allow any combination of data
`identifier parameters drawn from the workstream (including
`such parameters as which wafer is being examined. which
`process technology was used to make the wafer. which
`inspection device is being used. which layer in the wafer is
`being examined. and which lot the wafer was from) to be
`displayed in multiple trend charts and sub-charts simulta-
`neously; (2) allow x—axis and y-axis to be user configurable;
`and (3) perform statistical calculations automatically for any
`data combination.
`
`The third functional requirement concerned user interface
`characteristics. The automated system must: (1) provide a
`simple. graphical user interface with point—and—click menu
`options and minimal text entries; (2) allow wafer maps. die
`maps. and layer images to be overlaid at any magnification
`(e.g.. composite wafer maps of in-line and bitmap data); (3)
`support filtering options by defect type. defect size. intensity
`or other user~specified data type; and (4) display multiple
`bitmap images and electrical
`failure “bin” data
`simultaneously. allowing access to defect images and analy-
`sis data through wafer maps.
`The final functional requirement concerned system
`security. safety. and maintenance. It was determined that the
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`4o
`
`45
`
`50
`
`55
`
`65
`
`

`

`3
`
`4
`
`5.761.064
`
`system must: (1) provide for password security access by
`type of user. such as technician. engineer. or systems admin-
`istrator; (2) provide automatic back-up data integrity in case
`of system (computer or storage) failure. power outage. or
`network crash; and (3) support remote system and network
`administration.
`
`ing out the invention. As will be realized. the invention is
`capable of other and different embodiments. and its several
`details are capable of modifications in various obvious
`respects. all without departing from the invention.
`Accordingly. the drawings and description are to be regarded
`as illustrative in nature. and not as restrictive.
`
`The development and installation of an automated system
`would be beneficial in many ways. including the following
`examples.
`it would save the time and cost expended by
`technicians gathering information for the engineers and.
`most importantly. increase product yields due to a faster
`determination that defects were occurring allowing a faster
`determination of the defect causes and thus a faster correc-
`tion of the defect causes.
`
`In addition. by improving the flow of meaningful
`information. learning is accelerated within the production
`cycle. Corrective action can be taken more quickly in
`resolving the causes of defects and failures. accelerating the
`time it takes to reach optimum yield in a new facility or with
`a new process technology.
`
`SUMMARY OF THE INVENTION
`
`According to the present invention. the foregoing advan—
`tages are attained by an automated wafer defect management
`system in which wafer defect data are collected from wafer
`inspection instruments. converted into a standard data
`format. and transferred to a central database system.
`In accordance with another aspect of the invention user
`interface workstations are provided such that users can
`select information and have it transferred to the workstation
`for review. The user at each workstation can have the
`workstation create statistical and graphical representations
`of the selected data for review at the workstation. The user
`can select a single or multiple overlaid statistical and graphi-
`cal representations by pointing-and—clicking on a data point
`in a displayed chart. The format for display can be selected
`by the user and can be a trend chart. an optical image. a
`secondary electron microscope image. a wafer map. a tool
`comparison chart or a Pareto chart or a combination of any
`of the above shown in a Windowsm display.
`In accordance with a further aspect of the invention wafer
`defect data are transferred to data analysis stations which
`perform detailed analysis of the wafer defect data and return
`the analyzed data to the central database system. The data
`analysis stations include the capability for defect
`classification. image capture. surface/cross-section analysis.
`and spectral analysis. The detailed analysis generated by the
`data analysis stations is also available for review. study. and
`evaluation at each workstation.
`
`The central database system is made up of a relational
`database installed on a server with memory to store the
`wafer defect data. The relational database organizes the
`wafer defect data in tables where it is tagged according to
`preselected criteria. The preselected criteria includes process
`technology.
`layer.
`lot. wafer. device. process equipment
`idenn'fication. and scan tool identification. The central data-
`base system can access databases containing electrical test
`results and in-line process monitor and equipment monitor
`information which is correlated to the pertinent wafer defect
`data. This correlated data is available for review at the user
`interface workstations.
`
`Still other aspects of the present invention will become
`readily apparent to those skilled in the art from the following
`detailed description. wherein only the preferred embodi-
`ments of the invention are shown and described. simply by
`way of illustration of the best mode contemplated of carry-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`54]
`
`55
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The accompanying drawings incorporated in and forming
`a part of the specification. illustrate the present invention.
`and together with the description serve to explain the
`principles of the invention. In the drawings:
`FIG. 1A shows a first embodiment of the automated wafer
`defect management system of the present invention.
`FIG. 13 shows a second embodiment of the automated
`
`wafer defect management system of the present invention.
`FIG. 2 shows an embodiment of the automated wafer
`defect management system showing representative compo-
`nents in accordance with the present invention.
`FIG. 3 shows selected display attributes provided by the
`present invention.
`FIG. 4 illustrates the point-and—click capabilities of the
`present invention.
`FIG. 5 shows a layer trend Chart for percent bad dies per
`week.
`
`FIG. 6 shows a box chart for percent bad dies per layer in
`the wafer.
`
`FIG. 7 shows a box chart for percent bad dies per week.
`FIG. 8 shows a layer comparison chart for percent had
`dies per week.
`FIG. 9 shows a layer bar chart for defect count per layer.
`FIG. 10 shows a layer bar chart for percent bad dies per
`layer.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`One embodiment of the present invention is illustrated in
`FIG. 1A. In this embodiment there is shown a wafer defect
`management system 20. In this embodiment there is shown
`wafer inspection instrument (W11 #1) 22. wafer inspection
`instrument (WII#2) 24. and wafer inspection instrument
`(W11 #1) 26 representing that multiple wafer inspection
`instruments may be connected to the system. The wafer
`inspection instruments 22.24.26 are connected to a conver-
`sion box (CB) 28 which is shown connected to server 30.
`This embodiment also shows analysis station (#1) 32. analy-
`sis station (#2) 34. and analysis station (#m) 36 representing
`that multiple analysis stations may be connected to the
`system. Each analysis station may have associated with it an
`analysis PC workstation as shown at 38. 40 and 42. This
`embodiment also shows user interface workstation (#1) 44.
`user interface workstation (#2) 46. and user interface work-
`station (#n) 48 representing that multiple user interface
`workstations may be connected to the system. An electrical
`test database 50 and a workstream database 52 are also
`shown connected to the server 30.
`
`FIG. 1B shows another embodiment of the present inven-
`tion similar to the embodiment shown in FIG. 1A and
`
`wherein like component have the same numerical designa-
`tions. In the embodiment shown in FIG. 113 there are shown
`
`65
`
`conversion boxes 54.56.58 associated with wafer inspection
`instruments 22.24.26 respectively and conversion boxes
`60.62.64 associated with analysis stations 32.34.36 respec-
`tively. The conversion boxes 64 are desktop computers
`
`

`

`5
`
`6
`
`5.761.064
`
`equipped with specialized hardware and software to trans—
`late all the information provided by each attached instrument
`into a standard format. In addition. the conversion boxes
`54—64 handle video data digitizing. file transfer and com—
`munications between each attached instrument and the
`server 30. Software in the respective conversion boxes
`54—64 converts data from the attached instrument’s native
`format
`into a standard Transmission Control Program/
`Internet Protocol (TCP/IP) format. The respective conver-
`sion box 54—64 then transfers the data using TCP/IP’s File
`Transfer Protocol (FTP) to the server 30. The specialized
`software for the various aspects and components of the data
`management system is available from INSPEX.
`Inc..
`Billerica. Mass.
`
`Referring now to FIG. 2 there is shown a representative
`defect wafer management system 65 utilizing the teaching of
`the present invention and is considered by the inventors as
`the best mode of the invention as of the filing date. This
`embodiment utilizes an ethernet backbone 66 to network a
`sort station 68. a fab 70. an analysis lab 72. and engineering
`74. A wafer sort test station 76 sorts and tests wafers and
`sends data via conversion box 78 and Ethernet 66 to server
`
`80. Server 80 in the representative system 65 is a Hewlett
`Packard (HP) Apollo 735 server running Oracle Version 7.0
`database. Oracle Version 7.0 was chosen for representative
`system 65 because of its powerful relational database. As
`can be appreciated other equivalent servers could be used as
`well as other equivalent database software programs. Disk
`storage 82 consists of ten gigabytes and provides data record
`access time of less than 15 ms.
`
`The wafer inspection instruments in the Fab 70 comprise
`an Estek 8500 shown at 84. an Inspex 8510 shown at 86. a
`Seiko SEM/EDX (scanned electron microscopy/energy dis-
`persive x-ray) shown at 88. a KLA 2131 shown at 90. and
`a KLA 2550 shown at 92. The Estek instrument 84 and the
`Inspex 86 instrument each have a conversion box 94.96
`respectively. each connected to Ethernet 66. The Seiko 88
`instrument has an analysis station 98 which is connected to
`Ethernet 66 via a conversion box 104. The KLA 2131
`instrument 90 and the KLA 2550 instrument 92 share a
`review station 102 which is connected to Ethernet 66 via
`conversion box 108. The KLA 2131 instrument 90. the
`Inspex 8610 instrument 86. and the Estek 8500 instrument
`84 are wafer scanning tools which detect defects and anoma-
`lies in the wafers. KLA 2550 review station 92 is an optical
`microscopic review tool
`to review and capture optical
`images of defects on a wafer after the wafer has been
`scanned by an inspection station. The analysis stations
`102.98 are analytical tools to perform surface analyses and
`cross—section analyses (by ion-milling) and can provide
`electron and ion micrographs of defects and can perform
`compositional analysis of defects.
`Analysis lab 72 shows a Seiko FIB 110 with an analysis
`station 112 and a conversion box 114 connected to Ethernet
`
`66 and a microscope & stage unit 116 connected to a bitmap
`stage controller 118 which is connected to Ethernet 66.
`Analysis lab 72 also shows PC workstations 120 and 122
`connected to Ethernet 66.
`
`Engineering 74 show two PC user interface workstations
`124 and 126 connected to Ethernet 66. As discussed above
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`Engineering 74 can support multiple user interface work-
`stations which can be distributed throughout the corporation
`limited only by the availability of an Ethernet 66 connection.
`The operation of representative system 68 is as follows.
`The central database system installed on server 80 acquires
`information in real time from every inspection and analysis
`
`65
`
`tool in use throughout system 68. Data is stored in tables
`organized according to how it is called up by the user
`interface and tagged according to: process technology. layer.
`lot. wafer. device. process equipment identification. and
`scan tool identification. Data is automatically backed-up and
`archived by the Oracle software installed on server 80. A
`partial archive is taken daily and a full archive tape is
`removed from the system once each month.
`The PC user interface workstations 124.126 are 486-
`based workstations running Windows”. These workstation
`are configured with 8 Mb of memory. at least a 120 Mb hard
`drive. an Ethernet card running TCP/IP and FTP software.
`and SQL*NET.
`Unformalted data move across the network efliciently in
`TCP/IP packets to and from the Oracle database. and to the
`workstations 120.122.124.126 where custom software cre-
`ated by Inspex creates graphic representations and statistical
`calculations independently of both the network and the
`central database. Off-loading the graphical processing from
`the server onto the respective workstation provides for the
`fastest user response time while at the same time conserving
`network resources.
`
`Workstations 120.122.124.126 receive user selected
`wafer data from the central database server 80. Then. using
`a point—and—click graphical interface. the user can view the
`selected data as trend charts.
`images. wafer maps.
`tool
`comparisons and Pareto charts. The data retrieval operations
`and graphical presentations are generated on workstations
`120.122.124.126 in less than three seconds. The complex
`processing operation of accessing wafer maps from a trend
`chart. which is handled entirely by the workstation. executes
`in under five seconds. This performance is obtained by
`sharing database functions between the server 80 and work-
`stations 120.122.124.126. and by performing all graphics
`imaging and data manipulation on the respective worksta—
`tion.
`
`Because each workstation has the capability of displaying
`multiple graphical representations there is no need to create
`a paper record. The only need for a paper report is for
`management reporting purposes and a paper report can be
`printed‘outside the clean room environment. Trend charts
`and other graphical representations of the data can be
`selected on the desktop workstations by mouse-driven or
`menu options commands. Text data fields are also provided.
`with textual data becoming part of the wafer defect database.
`Referring now to FIG. 3. there is shown a representation
`of the information that is obtainable by a user at a user
`interface workstation. The user can select specific wafer
`defect data that needs to be examined. The user can chose a
`
`box plot 128 which compares defect level of any inspected
`layer between different lots or for diflerent workweeks. a
`stacked bar chart 130 which shows defect level distribution
`of inspected layers. a yield to defect density correlation chart
`132 which is an x-y scatter plot of wafer sort yield versus
`defect density. a defect Pareto chart 134 which shows defect
`type distribution of inspected layers in a given time frame.
`or a statistical process control chart (SPC) 136 where x-axis
`represents lot ID’s and the y-axis represents percent bad die.
`CL 138 is the center line which is equal to the average of all
`data points in the chart. UCL 140 is the upper control limit
`which is equal to CL+3*standard deviation. The SPC 136 is
`monitored closely for indications of problem lots which are
`indicated by any data point above UCL 140. Once a problem
`is detected on the SPC 136 the user double clicks on the data
`point on the chart. for example. data point 139 on SPC 136.
`This generates the pertinent defect wafer map 140. The
`
`

`

`7
`
`8
`
`5.761.064
`
`the defect wafer map 140 is
`arrows 142 indicate that
`generated by double-clicking on data point 139. The defect
`wafer map shows each individual die and a dot on each die
`in which there is a defect. The user can select any defect on
`any die for further examination by double-clicking on that
`defect. For example. defect wafer map 140 shows a repre-
`sentative defect 144 which has been double-clicked
`(indicated by arrows 146) for further examination. The next
`chart generated is a defect optical image chart 148 of the
`defect in the selected die. The next chart generated is a
`scanning electron microscope (SEM) image 150. The user
`can then select a spectral analysis chart 152 of the wafer
`defect selected.
`
`From any defect trend chart. the user at a user interface
`workstation can click on the chart to request wafer defect
`maps from the processing lot being analyzed From the
`defect map. any analysis performed on the subject defect.
`i.e.. SEM (scanning electron microscopy) or FIB (focused
`ion beam) images. EDX (energy dispersive x-ray) elemental»
`analysis or FIB milling results. are available within seconds.
`The user merely clicks on the desired choice to move from
`screen to screen. as shown in FIG. 3.
`
`FIG. 4 is a larger scale illustration of the wafer defect map
`shown in FIG. 3 and the possible graphical representations
`that can be selected by the user. From defect wafer map 154.
`the user can select any defect for further examination. For
`example. the defect shown at 156 is selected for further
`examination by double—clicking on the defect represented by
`arrows 158. This generates defect optical image 160. By
`double-clicking on the optical image defect shown at 162
`represented by arrows 164 a scanning electron microscope
`(SEM) image 165 is generated. By double-clicking on the
`SEM image defect. represented by arrows 166 a spectral
`analysis of the defect 168 is generated.
`FIG. 5 shows a layer trend chart for percent had dies 170.
`The x-axis shows weeks and the y-axis show percent defec-
`tive dies. The layer trend chart 170 can be generated for
`various parameters such as which scan tools were utilized.
`which process technology was used. and for layer. In
`addition. a moving average is indicated at 172.
`FIG. 6 is a box chart for percent bad dies with the x—axis
`indicating layers and the y—axis indicating percent defective
`dies. The box chart can be generated for specific parameters.
`such as which scan tools. which process technology. device.
`and which layers.
`FIG. 7 is a box chart similar to the box chart of FIG. 6.
`however. the box chart in FIG. 7 has the x-axis showing
`weeks and the y-axis showing percent defective dies. The
`parameters are the same except that the chart is generated
`using a specific layer.
`FIG. 8 shows a layer comparison chart for percent bad
`dies with the x-axis showing weeks and the y-axis showing
`percent defective dies. Again the chart can be generated with
`specified parameters such as which scan tools. which pro-
`cess technology. and which devices were utilized
`FIG. 9 shows a layer bar chart for defect count per layer.
`The x-axis shows layers and the y-axis shows number of
`defect count. The parameters for the chart can be selected by
`the user and include which scan tools. which process
`technology. and which devices.
`FIG. 10 shows a layer bar chart for percent bad dies with
`the x-axis showing layers and the y-axis showing percent
`defective dies. The parameters for this chart can be selected
`and in this chart include which scan tools. which process
`technology. and which devices.
`The foregoing description of the preferred embodiments
`of the invention has been presented for purposes of illusv
`
`tration and description. It is not intended to be exhaustive or
`to limit the invention to the precise form disclosed. Obvious
`modifications or variations are possible in light of the above
`teachings. The embodiments were chosen and described to
`provide the best illustration of the principles of the invention
`and its practical application to thereby enable one of ordi-
`nary skill in the art
`to utilize the invention in various
`embodiments and with various modifications as are suited to
`the particular use contemplated. All such modifications and
`variations are within the scope of the invention as deter-
`mined by the appended claims when interpreted in accor-
`dance with the breadth to which they are fairly. legally. and
`equitably entitled.
`What we claim is:
`1. An automated wafer defect data management system.
`comprising:
`multiple wafer inspection instruments;
`multiple wafer analysis tools;
`means for collecting wafer defect data from multiple
`defects on wafers from each of said multiple wafer
`inspection instruments and said multiple wafer analysis
`tools;
`conversion means associated with each of the multiple
`wafer inspection instruments and each of the multiple
`wafer analysis tools for converting the collected wafer
`defect data from each of said multiple wafer inspection
`instruments and said multiple wafer analysis tools from
`an instrument and too] specific format to a standard
`format;
`a central database system with means for storing con—
`verted wafer defect data wherein the stored converted
`wafer defect data is retrievable based on selected
`criteria;
`least one user interface workstation wherein user
`selected converted wafer defect data can be analyzed in
`real time; and
`means for transferring user selected converted wafer
`defect data from the central database system to the at
`least one user interface workstation.
`
`at
`
`2. The system as in claim 1. wherein said central database
`system comprises:
`a server;
`
`a relational database installed on said server for organiz-
`ing said converted wafer defect data in tables wherein
`aid converted wafer defect data is tagged according to
`preselected criteria; and
`wherein said means for storing converted wafer defect
`data comprises a memory associated with said server to
`store said converted wafer defect data and said tables.
`
`3. The system as in claim 2. wherein said at least one
`interface workstation includes:
`
`means for creating statistical and graphical representa-
`tions from said user selected converted wafer defect
`data; and
`means for displaying said representations.
`4. The system as in claim 3. further comprising:
`at least