Advanced Plasma Technology 

High precision film thickness trimming for the TFH industry

Roth & Rau AGSeptember 2009

2

Product Overview

IonScan Equipment for ultra-precise Surface Processing

IonScan 800

Wafer based processing in semiconductor industry

Applied for localized ion beam trimming and figuring

Basically described in this presentation

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Principle of IonScan

Equipment Principle

Ion beam based surface processing capable for all thin film materials

Focused ion beam for locally controlled processing

Velocity controlled meander scan for local removal control

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Principle of IonScan

Process Flow for Ion Beam Trimming

Required input data:

Wafer specific thickness or frequency error file (Supplied by customer metrology)

Etch profile function from system calibration (Sheet film calibration data)

Material specific recipe data (beam settings, cooling, gas flow, …)

Film thickness error after ion beam processing

Frequency / Film thickness error of BAW wafer

Etch profile and focus of ion beam (Material dependent)

Calculation of residence time data

20 nm 20 nm/s 40 ms

1 nmWafer specific control data for axis system

Velocity modulated wafer scan

Process recipe data (Ion beam parameters, Cooling, Handling)

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Components & System Layout

System Layout

Process module 1 Cassette load-lock 1Robot platform

Process module 2 Cassette load-lock 2Ion source

Cluster Platform

Configurable cluster tool design with4 port handling unit

Process Chamber

Process chamber with high performance axis

Separate ion source housing for easy source access

Large front door for easy system access

System Control

Cluster and process module controller (Windows XP)

SECS/GEM host interface

Recipe and protocol database(MS SQL Server)

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Components & System Layout

Process Chamber

yy‐‐ AxisAxis

Wafer Wafer ChuckChuck

Ion SourceIon Source

xx‐‐AxisAxis

Faraday Faraday ArrayArray

zz‐‐AxisAxis Tilt AxisTilt Axis

Handling Handling PortPort

Rectangular chamber of 800 x 800 x 550 mm3

Chamber and port dimensions capable for processing of up to 200 mm wafers

Chamber completely covered by sputter shields for maintenance

Separately accessible ion source housing for size and maintenance optimization

Turbo pumped (2400 l/s) viton sealed system (doors double sealed, differently pumped) with base pressure < 10-6 mbar

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Trimming Performance

Challenge in Post CMP – Step Height Reduction

IonScan 800 allows to overcome problems in CMP

Up-scaling for larger wafer areas causes homogeneity problems for CMP

IonScan has no scaling problems

Polishing of different materials causes arbitrarily distributed step heights at interface to be created

IonScan is able to remove step functionsby adjusted process selectivity

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35

0 10 20 30 40 50 60 70

Incidence Angle [ deg ]

Rat

e [ n

m/s

]

InsulatorMetal

Selectivity control by ion incident angle

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Trimming Performance

Step Height Reduction by using High Selectivity

0

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10

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30

35

0 10 20 30 40 50 60 70

Incidence Angle [ deg ]

Rat

e [ n

m/s

]

InsulatorMetal

NiFe

Al2O3

thickness variation over wafer

NiFeAl2O3

localized trimming

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Trimming Performance

Step Height Reduction

Top: Step heights reduction across of the wafer before (pre) and after (post) ion beam trimming

Bottom left: Histogram graph of step height distribution

Bottom right: Trimming function of actual removal versus target removal

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Trimming Performance

Smoothing by using Low Selectivity

0

5

10

15

20

25

30

35

0 10 20 30 40 50 60 70

Incidence Angle [ deg ]

Rat

e [ n

m/s

]

InsulatorMetal

thickness variation over wafer

NiFeAl2O3NiFeAl2O3

localized trimming

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Trimming Performance

Al2O3 Trimming Demo

Top: Thickness across the wafer before (pre) and after (post) ion beam trimming

Bottom left: Histogram graph of thickness distribution

Bottom right: Trimming function of actual removal versus target removal

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Trimming Performance

Etching to define Steps

Mask Al2O3

thickness variation over wafer

Mask

Substrate

defined step high

localized trimmingSubstrate

Etching through different materials in one process step

Roth & Rau AGJuli 2006www.roth-rau.de

Thank you very much for your attention!

Roth & Rau AGGewerbering 3OT Wüstenbrand09337 Hohenstein-ErnstthalGermany