Usage of Hercules inside

commercial FDC System MaestriaDennis Föh

Advanced Process Control

Micronas

Freiburg

2

Why are Plasma Parameters ideal for FDC in Etch ?

Electron Density and Collision Rate are sensitive to

Process parameters (e.g. gas flow, pressure, power)

Process / chamber drift (conditioning, clean, WAC)

Product differences (e.g. open area)

Tool failure (e.g. baratron, rf, MFC)

Plasma Parameters provided by HERCULES® help to

optimize conditioning, WAC, MTBC, cleaning procedures

understand process / tool issues

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Influence of Electron Density on Etch Process

Source : Plasmetrex

n+ion

density

ji+ion energy

current density

ne νcollision per volume element

productionof

etch species

etch rate

selectivity

homogeneity

neelectron density

electron energy distribution

physical influence

chemical impact

RF peak voltage

chemical etching

desorptionof etch

products

physical sputtering

4

Influence of Tool / Process Parameters on Collision Rate

Source : Plasmetrex

Collisionrate ν

Gas temperature

Wall temperature Wafer temperature

Relative concentration of gases

Wafer

Crosssection

Arcing

Gas flow

PressureBaratron

MFCsThrottle valve

B field

Density of neutrals

RF power in plasma

Generator

MatchboxRF feedthrough

chuck

8th European AEC/APC Conference 2007

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Basic Setup of Hercules®

01020304050

1 14 27 40 53 66 79 92 105118131144

Etch Time [s]

Collision Rate [106 s-1]Plasmachamber

Plasma parameterse.g., electron collision rate.

Measurementsignal

-0,6

-0,4

-0,2

0

0,2

0,4

0,6

0,8

1

1,2

0 5 10 15 20

ACI

Time

13,56 MHz

1

bias / peak voltage

Hercules® APC xM

Matchbox

Generator

Source : Plasmetrex

SensorTCP 9400/9600

8th European AEC/APC Conference 2007

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Influence of Poly TCP Process Parameters on Collision Rate

Std Std StdHBr+10% HBr-10%

p +10% p -10% Std StdStd

Ptop +10% Ptop -10% Std StdStd

±10% TCP-Power = ca. 15-25% change in collision-rate

±10% HBr = ca. ±3% change in collision-rate ±10% pressure = ca. ±11% change in collision-rate

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Gate-Poly MSPH 0.45µ - VPCD 0.5µ (Poly-OE-Step)

2 Lots MSPH 0.45µ (61% OA)

2 Lots VPCD 0.5µ (74% OA)

Plasma parameters are very sensitive

to the etched open area (OA)

Collision Rate vs. Open Area & Endpoint Sensitivity

Collision Rate

Electron Density

8th European AEC/APC Conference 2007

Possibility of EOP detection.

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Plasma Clean Cycles before Wet Clean

Large change inside chamber during 1st cycle only. 3-5 cycles are sufficient forstable chamber before chamber opening. Already implemented in production

without any negative impact on cleaning efficiency. (time saving : 1 hr.)

Collision Rate

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Effect of Nitride to Poly Switch w/o Seasoning

Switching between fluorine-based chemistry and chlorine-based chemistry could cause

yield loss due to particles fallingfrom top plate !

1st PLRAEZ after FLDAEZ

707580859095

100

1 5 9 13 17 21 25

Wafer #

Norm

aliz

ed

Yie

ld [%

]

2nd PLRAEZ after FLDAEZ

707580859095

100

1 5 9 13 17 21 25

Wafer #

Norm

aliz

edY

ield

[%]

10

Comparison Continuous / Random Switchrandom switch continuous switch

Poly-WAC Poly-WAC

Nitride-WAC Nitride-WAC

Electron density WAC

Collision RateEtch Processes

Poly Poly

Nitride

Nitride

Poly

Collision Rate WAC

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FDC-Software Maestria (PDF Solutions / Si Automation)

8th European AEC/APC Conference 2007

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Maestria Deployment Status @ MicronasEtch : Lam Alliance + Lam Rainbow + FSI Mercury + Mattson Aspen IIDiffusion : ASM 400 Implant : Varian EHP 500Litho : Canon I5+ StepperThinfilm : AMAT Endura

32 Tools incl. 65 modules / chambers850 strategies active, 130 with OCAPs, 420 with limitsPCA (Process Control Analyzer) training for process & maintenance (30 engineers)PCA implemented in daily work

but : sometimes internal tool data is not enough, additional sensors are necessary...

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Source : PDF Solutions modified for Hercules

Hercules & Maestria Deployment

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Source : PDF Solutions modified for Hercules

8th European AEC/APC Conference 2007

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DC Plan : Integration of Hercules Variables

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Definition of Indicators

17

18

19

Easy Correlation Tool Parameters - Sensor Data

Implementation of external sensor data into Maestria system allowseasy comparison / correlation of tool and sensor data

Collision Rate Bottom-Temp

8th European AEC/APC Conference 2007

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FDC Example : Defect Baratron (1)

Because of sensitivity to process / tool parameters, collision rate and electron densityare ideal for detecting tool failures resulting in process parameter drifts. In this examplea baratron had a defect causing a shift in real pressure. The process was not aborted

by the tool because the defect baratron fooled the tool with the "correct" pressure. Additional parameters like plasma parameters are helpful for FDC.

Col

lisio

nR

ate

different pressure caused bydefect baratron !

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FDC Example : Defect Baratron (2)

8th European AEC/APC Conference 2007

Problem is indicated only by collision rate & VATvalve angle. Collision rate is a convenient in situ parameter for the real process status inside the chamber !

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Process Control by Wafer-to-Wafer-Difference

Wafer-to-wafer-difference of plasma parameters is an easy recipe independent process/tool control ;

easy identification of excursions, tool & process problems !

Collision Rate Electron Density

8th European AEC/APC Conference 2007

Dennis Föh

Section Head APC

Micronas

Hans-Bunte-Str. 19

79108 Freiburg

Germany

foeh@micronas.com

www.micronas.com