Http:// Weir Reticle Haze Detection and Monitor What, Why and How to control reticle haze issues.

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Weir Reticle Haze Detection and Monitor

What, Why and How to control reticle haze issues

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Reticle Haze Concepts Base Method of Weir Haze Detection Weir PW Characterization Weir DM macro setup of Weir PW method Weir DMA automation of input & output data


Reticle Haze Detection with Weir PW & Weir DMA

Haze formation on reticle continues to be a significant problem for the semiconductor industry.

Haze can be formed on the outside pellicle and on the quartz back side of the reticle.

Major component of the haze is known to be aluminum sulfate that comes from the reticle cleaning process and Deep Ultra Violet interactions with residue.

The reticle materials, the exposure wavelength, roughness of photomask and this haze will affect the resolution and process latitude.


Reticle Haze Sources

Mask making materials Process residues Reticle container Fab or Scanner environment


Issues for reticle cleaning

- for DUV lithography Phase and transmittance change Surface contamination

- for VUV lithography Phase and transmittance change Surface contamination ESD

- for EUV lithography Reflectance change Affect of debris?


Mechanism for the formation of ammonium sulfate haze


Reticle Haze Influence Transmittance Reduction

• Transmittance reduction caused variations in the CD and DOF values.

• Aberrations will increase:• Since the reticle is an element of the scanner optical train

• Process Window size will decrease and shift center


Reticle Haze Influence Transmittance Reduction

CD Increase with transmittance loss for a 90nm A.P.S.M.


Reticle Haze Influences Dose Change

• Expose energy change with transmittance loss for different reticle.

• Backside glass haze can effect overall mask transmission and thus can cause a dose shift on the wafer . A dose shift can be serious because most of low k1 process run with a very small process window and cause serious yield issue.


Reticle Haze Influences Throughput

Throughput will decrease due to an increase dose required to make same line width. change with transmittance loss for different reticles.


Sources of CD variation across the wafer

Primary disturbances causing CD Uniformity (CDU) variations grouped upon their sources.

Reticle transmission loss directly influences the effective dose Indirectly increases aberrations in the optical train that result in ACLV CD

Variation increase

Reticle Scanner Track & Process

Effective Focus

Wafer flatness

Device topography

Substrate

BARC coat

Resist Film coat

PEB Temp & Time

Develop

Exposure Dose

Slit Uniformity

Focus SetUp

Chuck Flatness

Up-Down Scan

Flatness

CD’s

Transmission

CDUEffective Dose

Scan Linearity


Monitoring the process for Reticle Haze

Haze is formed around the pellicle, on the quartz side of the mask and on the chrome side of the mask.


Haze Appearance Haze influence on the image can be symmetric or anti-symmetric:

Radial Process induced Exposure enhanced

Across-Reticle Reticle Cleaning

Scattered and random Equipment sourced

Testing for Haze Requires multiple points on field Examine

relative CD uniformity DoF Optimum and IsoFocal Dose Dose Uniformity

Reticle Haze

Clean reticle

Process Induced

Cleaning Residue

Cleaning residue & process


Method of Reticle Haze Monitor

Weir PW Weir PW Characterize Dose Uniformity

Determine Normal Process Window levels for multiple points on the field

Setup Weir DMWeir DM Macro to duplicate Weir PW analysis

one-step processing for the wafer fab.

Setup online trend charts for variables

Automate data gathering with Weir DMAWeir DMA interface to factory control

Automatically output critical process variables to factory-control system


Weir PW Dose Uniformity Setup for Initial Characterization

Setup Focus-Dose or Dose Matrix Derive base-response of process


Bossung curve analysis anatomy A = Isofocal Dose

Dose at which feature size is independent of Focus

B = Locus of Best Focus “Best Focus” is located at the

maxima or minima of each dose curve

The greater the curvature, the greater will be the aberrations of the system

UCL/LCL Upper and Lower Control

Limits for the process EL

Exposure Latitude or the dose range over which the feature size lies between the UCL and LCL

DoF Depth of Focus or the focus

range over which the feature size lies between the UCL and LCL

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Focus

A

One curve for each dose

B

UCL

LCLDoF

EL

Curve “B” is highly sensitive to lens aberrations

Reticle haze directly influences the aberrations of the tool.


Weir Dose ReportIsoFocal Dose: Variable Site Dose (mj/cm^2)Feature

BCDv (nm) 1.0000 23.1900 73.8730BCDh (nm) 1.0000 23.8300 56.2230BCDv (nm) 2.0000 23.2200 75.8150BCDh (nm) 2.0000 22.8000 68.5990BCDv (nm) 3.0000 23.3000 75.0460BCDh (nm) 3.0000 23.0700 65.2500BCDv (nm) 4.0000 23.3200 75.0490BCDh (nm) 4.0000 23.8300 56.6960BCDv (nm) 5.0000 23.2300 78.0360BCDh (nm) 5.0000 23.0300 67.1220BCDv (nm) 6.0000 23.8600 70.4050BCDh (nm) 6.0000 23.3200 63.5040

Summary of Dose Response for Max Dose Latitude by SiteBest Best Dose Dose

Feature Site Dose Focus Latitude %LatitudeBCDv (nm) 1.0000 35.0000 -0.0270 1.9210 4.3000BCDh (nm) 1.0000 28.4000 -0.0290 1.9210 4.3000BCDv (nm) 2.0000 31.0000 -0.0310 1.9210 4.3000BCDh (nm) 2.0000 28.5000 -0.0510 1.9210 4.3000BCDv (nm) 3.0000 28.6000 -0.0470 1.9210 4.3000BCDh (nm) 3.0000 27.5000 -0.0480 1.9210 4.3000BCDv (nm) 4.0000 28.3000 -0.0530 1.9210 4.3000

SummaryVariable DoseMean DoseRangeFeatureMeanFeatureRangeBCDh (nm) 22.5000 3.4000 69.9360 35.2920BCDv (nm) 22.5000 22.7000 80.9910 210.6440

PROCESS 22.5000 22.7000

These variables will be gathered by Weir DM & Weir DMA


Dose curves calculated at best focus

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Upper Blue Curve

Linear Dose curve that reflects the resist’s true response.

Exposure Latitude (EL) can now be evaluated.

Point-spread at each dose is the result of reticle feature size variance.

Lower Red Curve

Plotted Best Focus for each site.

A discontinuity occurs with this data when the IsoFocal point is crossed.


Isofocal Analysis

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Isofocal Analysis: All-sites on field, BCD features Vertical (black) and Horizontal (red)

1) Calculate IsoFocal dose for each feature and site

Classic: IsoFocal point is found when the 2nd derivative of the process window = 0

Bossung: IsoFocal deviant = the magnitude of the 3rd Bossung curve coefficient

Isofocal point is at the minimum for the curve

2) Lower curves: Level of aberrations for the dose plotted as magnitude of 2nd Bossung curve coefficient

Isofocal deviant curves

Aberration level at each dose


Optimum Field Response thru Dose

BCD summarizes natural feature size response @ best Focus for each dose DoF computed when in control

Best Focus BCD4 (nm) DoF DoseMean: 0.0070 104.1780 18.0

Max: 0.0810 110.6640 18.0Min: -0.1570 100.6540 18.0IFD: 0.2380 10.0100 18.0

Mean: 0.0180 94.3450 0.0530 19.0Max: 0.0830 99.8950 0.0530 19.0Min: -0.1340 91.0560 0.0530 19.0IFD: 0.2170 8.8390 0.0000 19.0

Mean: 0.0330 84.4540 0.3560 20.0Max: 0.0940 88.9940 0.5970 20.0Min: -0.0740 81.4100 0.1710 20.0IFD: 0.1680 7.5840 0.4260 20.0

Mean: 0.1080 72.8100 0.6260 21.0Max: 0.9820 77.6260 0.6400 21.0Min: -0.1050 30.3330 0.5230 21.0IFD: 1.0870 47.2940 0.1170 21.0

Best Focus BCD4 (nm) DoF DoseMean: -0.0390 65.3970 0.0160 22.0

Max: 0.2880 70.2900 0.0210 22.0Min: -0.2800 61.7610 0.0110 22.0IFD: 0.5680 8.5290 0.0100 22.0

Mean: -0.0840 56.2490 23.0Max: -0.0320 59.1160 23.0Min: -0.1570 53.4410 23.0IFD: 0.1250 5.6740 23.0

Mean: -0.0570 46.2440 24.0Max: 0.0210 47.9520 24.0Min: -0.1340 43.7280 24.0IFD: 0.1550 4.2230 24.0

Best Focus BCD4 (nm) DoF DoseMean: -0.0390 65.3970 0.0160 22.0

Max: 0.2880 70.2900 0.0210 22.0Min: -0.2800 61.7610 0.0110 22.0IFD: 0.5680 8.5290 0.0100 22.0

Mean: -0.0840 56.2490 23.0Max: -0.0320 59.1160 23.0Min: -0.1570 53.4410 23.0IFD: 0.1250 5.6740 23.0

Mean: -0.0570 46.2440 24.0Max: 0.0210 47.9520 24.0Min: -0.1340 43.7280 24.0IFD: 0.1550 4.2230 24.0


Weir DM Daily Monitor Interface

Macro-Encapsulation of Weir PW Analysis

One-Step data selection and analysis.

User customized:

Graphics

Statistics setup

Variable Trend Tracking

Variable ouput


Weir DM Macro Types Weir PSFM focus reticle analyses

Focus/Expo Matrix Functionality

Best image analysis of lens aerial image Requirements

Benchmark PSFM reticle Initial dataset of a PSFM Focus matrix

Fixed-Focus Analysis Functionality

Analysis of wafer flatness, photoresist flatness, process focus and exposure tool autofocus/ auto-leveling stability.

Requirements Benchmark PSFM reticle Initial dataset of PSFM fixed-focus, full-wafer

Same layout and exposure as monitor wafers will be Same exposure as PSFM calibration tempalte

Weir PW analyses Raw Metrology Reticle Haze and Process Window Monitor

Raw metrology and tool Monitor are same Statistics and modeling on any metrology data set Requirements

Initial data set with same exposure and layout as future daily monitors


Weir Macro setup for Process Window Analysis

Weir PW Example data – Forms basis for template

Template


Selecting the Weir DM Analysis type


Focus Dose PW Dose @ BF

Select from 4 types of analysis

Reticle Haze is best analyzed with the “Dose @ Best Focus” analysis


Weir DM Target Values Setup

Variables are determined by user-data

Automated culling and modeling supported


Selecting statistics for analysis & trend


Optimum Dose Trend for mixed OPC - BCD

Dataset or date can be trended

on abscissa


Reports that appear during the analysis of each data set. Upper chart summarizes the focus and dose for each site. Lower graph

displays the final dose-plot for all five sites of one data set.

Reports & Graphics for current dataset


Call-Log for Weir DM

Can be used to track and perform analysis

diagnostics.


Raw “Range” data for the 12 data sets analyzed. One interactive point, text is “yellow-note”, has been highlighted by the user’s mouse.

Raw as well as modeled data trends


Reticle-Haze Sensitive Iso-Focal Dose


Reticle-Haze IsoFocal Dose Range


Feature-Size change with IsoFocal Dose


Isofocal Dose with Message added by user.


Summary Data Selection

For Full-Field for Process-Window detection of Reticle Haze


User selections for monitoring


Reticle Haze can also influence Best Focus Uniformity

Here Best Focus is calculated from the process-window Focus-Dose Matrix


Dose %Latitude for five and one site studies


Weir DMA - Daily Monitor Automation

Automation of Weir DM for calling by shop-flow and other control systems.

Includes input data specification, analysis logs, internal trends and data report outputs in text and html format.


Run-log format Default folder = %Weir DM home%

Default = Weir DM home folder To change use “Tools/Options” menu and the DMA tab

File Name RemoteCall.Log Format = ASCII

Contents Contains analysis summary plus any errors Sample:

____ Weir DMA: ver: 3.8.55 ‘ start of new analysis System ID: 1C2CE5A7 Analysis Start: Wednesday, July 28, 2004 2:36:50 PM ‘ next line is the input command line Cmd: -t "C:\Program Files\Weir Wavefront Engineering\Templates\DS1_FF_DMtemplate.XLT" -d 040525153141.txt -o

D:\TEMP -x D:\TEMP runDM Start: 2:36:50 PM cmdLineParse Start: 2:36:50 PM ‘ command line interpreted correctly DM Start: 2:36:50 PM runDMoutput Start: 2:36:59 PM ‘ actual analysis start Output: D:\Temp\040525153141_WeirDMA.csv ‘ output to ASCII file Output 56 statistics. OutputXLS: D:\Temp\040525153141_WeirDMA.xls ‘ optional output to excel workbook Output 56 statistics. run DM successful ‘ signifies completion without errors Analysis End: Wednesday, July 28, 2004 2:37:00 PM …____


Reticle Haze & Full-Field Process Window Monitor

Call DMA with Macro & Data

Import data &

save

Display current-

data graphic

Update Trend charts

Weir DMA output to ASCII (*.csv) and Excel

(*.xls) files

Weir DMA outputs status and any errors to RemoteCall.log

Optional: Model

wafer and field focus


Moving a Weir DM macro

When moving a Weir DM macro to another computer: Copy the macro (*.XLT) into the new computer’s template directory Make sure the directories in the macro correspond to those in the new

computer: Data directory Macro storage directory Reticle storage directory

Insure the “Tools/Options” interface in the new computer specifies the proper data import filter. Import Filter can also be called by Weir DMA


Weir DMA Example Analysis


Check Weir DMA Options

Options interface is located on the Weir DM “Tools/Options” menu. Here we’ve changed the location of the DMA analysis log file “RemoteCall.log”

to the “D:\Temp” folder. The Max/Min options will be used to limit the size of this log file.


Running Weir DMA – RemoteCall.log

This is the RemoteCall.log format

Switches used for the analysis are shown above-left

Screen shows the status output of two successful data runs

-t "C:\Program Files\Weir Wavefront Engineering\Templates\DS1_FF_DMtemplate.XLT"

-d 040615210805.txt -o D:\TEMP -x D:\TEMP


RemoteCall.log This file will also show any

errors encountered and should be monitored regularly.

Weir DMA: ver: 3.8.56 System ID: 1C2CE5A7 Analysis Start: Friday, July 30, 2004 4:00:34 PM Cmd: -t "C:\Program Files\Weir Wavefront Engineering\Templates\DS1_FF_DMtemplate.XLT" -d 040615210805.txt -o D:\TEMP -x D:\TEMP runDM Start: 4:00:34 PM cmdLineParse Start: 4:00:34 PM DM Start: 4:00:34 PM runDMoutput Start: 4:00:43 PM Output: D:\Temp\040615210805_WeirDMA.csv Output 55 statistics. OutputXLS: D:\Temp\040615210805_WeirDMA.xls Output 55 statistics. run DM successfulAnalysis End: Friday, July 30, 2004 4:00:45 PM


Files in output directory

• Consist of two sets of ASCII and XLS output data files along with the call log.


,FocusMin::,0,,[EndHeader],,,,,,[Results],,,,,,[Z (Mean)],,,Wafers:,1,,Sites/Die:,2,,#Dice:,5,,IFD:,0.199,,BF(Fitted):,0.000,,X Tilt(urad):,0.000,,Y Tilt(urad):,0.000,,Astigmatism:,0.135,,Curv(nm/cm2):,0.000,,IFDresid(um):,0.000,,StDEVresid(um):,0.000,,Count:,10,,Mean:,0.017,,Median:,0.036,,SEM:,0.018,,Maximum:,0.136,,Minimum:,-0.063,,Range:,0.199,,MinMax:,0.136,,StDev:,0.058,,Mean+3Sigma:,0.190,,[EndResults],,,[END],,

,FocusMin::,0,,[EndHeader],,,,,,[Results],,,,,,[Z (Mean)],,,Wafers:,1,,Sites/Die:,2,,#Dice:,5,,IFD:,0.199,,BF(Fitted):,0.000,,X Tilt(urad):,0.000,,Y Tilt(urad):,0.000,,Astigmatism:,0.135,,Curv(nm/cm2):,0.000,,IFDresid(um):,0.000,,StDEVresid(um):,0.000,,Count:,10,,Mean:,0.017,,Median:,0.036,,SEM:,0.018,,Maximum:,0.136,,Minimum:,-0.063,,Range:,0.199,,MinMax:,0.136,,StDev:,0.058,,Mean+3Sigma:,0.190,,[EndResults],,,[END],,

Output Data File Partial display of

output file Specifications

are in the manual.

Each section of the data is summarized by a header line in “[]” brackets

,[Data],,,Program:,Weir DMA,,,,,DataFile:,040525153141.txt,,DataFolder:,D:\Data\UMC\WeirDM Testing,,Template:,DS1_FF_DMtemplate.XLT,,TemplateFolder:,C:\Program Files\Weir Wavefront Engineering\Templates,,AnalysisDate:,7/28/2004,,AnalysisTime:,12:00:00 AM,,Tool:,,,Wafers:,1,,,,,[Header],,,DateTemplateSaved:,7/27/2004,,Analysis:,Fixed Focus,,FocusTemplate:,UMC DS5-Step2,,ConversionMethod:,All Sites,,ModelData:,True,,Statistics:,1,,Graphic:,1,,GraphicData:,0,,WaferFieldGraphic:,Wafer,,GraphicPlot:,Vector,,GraphicDataFormat:,All Points,,Comments:,,,Summary:,Analysis:Fixed Focus:All Sites (UMC DS5-Step2)

,[Data],,,Program:,Weir DMA,,,,,DataFile:,040525153141.txt,,DataFolder:,D:\Data\UMC\WeirDM Testing,,Template:,DS1_FF_DMtemplate.XLT,,TemplateFolder:,C:\Program Files\Weir Wavefront Engineering\Templates,,AnalysisDate:,7/28/2004,,AnalysisTime:,12:00:00 AM,,Tool:,,,Wafers:,1,,,,,[Header],,,DateTemplateSaved:,7/27/2004,,Analysis:,Fixed Focus,,FocusTemplate:,UMC DS5-Step2,,ConversionMethod:,All Sites,,ModelData:,True,,Statistics:,1,,Graphic:,1,,GraphicData:,0,,WaferFieldGraphic:,Wafer,,GraphicPlot:,Vector,,GraphicDataFormat:,All Points,,Comments:,,,Summary:,Analysis:Fixed Focus:All Sites (UMC DS5-Step2)


Trend summary• The modeled summary of the

8 data files can be found if we go back into Weir DM


Data contents

• Plots the # of sites per field.

• Only last two data sets correspond to the 63 sites per field of the calibration template


Weir DMA features

Features Ability to limit the size of the RemoteCall.log file Ability to select a window size and location in the trend plot for plots with

many data entries. DMA screen for status reporting of DMA calls

Interactive beyond RemoteCall.log file. Done Aug. 2004 along with ability to control the length of display time for

this screen. Data Import Format included in Weir DM Template Ability to select focus models Ability to select full-field, full wafer and slit/scan models for focus or any

metrology variable. Optional Email notifications of OOC and problem data sets.

Http:// Weir Reticle Haze Detection and Monitor What, Why and How to control reticle haze issues.

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Transcript of Http:// Weir Reticle Haze Detection and Monitor What, Why and How to control reticle haze issues.