An overview of Hiden Analytical’s end point detector ... · An overview of Hiden Analytical’s end point detector system for ion beam etch applications. ... For out of warranty

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IMP – End Point Detector

An overview of Hiden Analytical’s end point detector system for ion

beam etch applications


What is the Hiden IMP? The Hiden IMP is a differentially pumped, ruggedized secondary ion mass spectrometer for the analysis of secondary ions and neutrals from the ion mill process.

The IMP system comprises:• Stainless Steel Shroud with Sampling Orifice• Ion Optics with Energy Analyser and integral ioniser• Triple filter Quadrupole mass analyser• Pulse Ion Counting Detector• Differentially Pumped Manifold With Mounting Flange to Process Chamber• Data System with integration to the process tool


End Point Detection

Substrate Mat. B

Mat.A

Mask

Substrate Mat. B

Material A

Mask

Primary Ion Beam

Secondary Ions Mat. A

Secondary Ions Mat B


Signal Collection


Data Output


Ion Milling Probe 30°°°°

Ion Milling Chamber

Parallel plate energy filter

Channeltron detector

Quadrupolemass filter Ion

Source

Primary Beam

Substrate50 L/sTurbo pump

Mounting flangeType DN-63-CF

Electron ImpactIon source

30° acceptance angle


IMP Schematics


IMP – probe schematics

Front End Detail

30°

3.0

7.5

∅4.

0


Angle of Acceptance

EPD

ab


Variables affecting angle of acceptance:

• Wafer tilt – The IMP end point detector probe operates over a wide range of wafer tilt angles

• Surface roughness• Primary ion beam energy

-100 -80 -60 -40 -20 0 20 40 60 80 100

Relative angular acceptance

±5° ~ 50%


Example Data:Ta / NiFe /Ta

Tantulum

Nickel

SE

M :

c/s

Time MM:SS

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

00:00 03:20 06:40 10:00 13:20 16:40 20:00


Example Data 2:• Etch profile for a Cu / NiFe layered material, with the objective

to stop on the NiFe layer. Sample was 99% masked.

Det

ecto

r cur

rent

/ A

mps

Scan number0 10 20

1e-017

1e-016

1e-015

Cu (m/z 63)

Fe (m/z 56)

Ni (m/z 58)


Example Data 3:Multilayered Sample: FeMn/NiFe/Co/Cu/Co/NiFe/Ta

Iron

Copper

Manganese

Cobalt

Nickel

Tantalum

SE

M :

c/s

Time MM:SS

10

100000

100

1000

10000

00:00 01:40 03:20 05:00 06:40 08:20 10:00 11:40 13:20 15:00

Data Zoom


Data Zoom - variation due to sample rotationMultilayered Sample: FeMn/NiFe/Co/Cu/Co/NiFe/Ta

Iron

Copper

Manganese

Cobalt

Nickel

Tantalum

SEM

: c/

s

Time MM:SS

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

15000

16000

04:50 05:10 05:30 05:50 06:10 06:30 06:50 07:10 07:30 07:50 08:10


Process Comparison / Evaluation:• 4 wafers run sequentially – wafer 3 has an imperfection recorded


IMP Materials GuideINTERFACE APPLICATION EXAMPLE

Si/Ga Identification of SiO2 interface on III-Vsemiconductor.

Au/Cr/Al Au/Cr track identification on aluminiumsubstrates.

Au/Ti/Ga Precise definition of Au/Ti electricalcontacts in GaAs.

Mo/Ge Precise definition of Mo/Ge interfaces inmultifilm Mo/Ge structures.

Al/In Identification of the interface betweentwo semiconductors Al In As/InP.

Al/Ga To etch down to the interface betweentwo layers of AlGaAs separated by a79 Å GaAs well. The Al signal clearlyidentified the sandwich.

Y/Ba/Cu/MgO Identification of separate layers inmultilayersuperconductor materials.

NiCr/Cu/NiFe/SiO2 Magnetic disc sensor head manufacture.


Mass Channels.Layer Mass to monitor Mass numberAlTiC Ti 48

CoFe Co 59

Al2O3 Al / AlO 27 / 43

Ta Ta 181

NiFe Ni 58

Cu Cu 63

FeMn Mn 55

Co Co 59

Ca Ca 40

Ti Ti 48

Cr Cr 52

Ag Ag 107

Au Au 197

Pt Pt 195

Si Si / SiO 28 / 44


The IMP – Front End Detail.


Software Integration – Parallel digital I/O.• Programmable DDE• Parallel Digital I / O• RS 232 Scripting communication

PC

Ethernet

MSIURS485twisted

pair

StartPause

Recipe

ReadyRunningEndpoint

Spare

I/O

Mains power PSU

10 - 30 V d.c.

Initialised

4.7k - 27 k

5 - 30 V

see text

Network


End point Control:• The end point control signal is sent via digital I / O• The end point is controlled with the following criteria:• Rising edge or Falling edge with variables:

• Mass channel

• Percentage over etch

• Timed over etch

• Time out over etch


End point Control Parameters.A_limit : The limit, in c/s, above which the signal intensity must be in order for the program to detect an endpoint. Can be useful to remove the effect of background signal.

Delay_A: The time after which the event sequence starts looking for an end point. During this time no endpoint indicated. Useful for setting to stop system end pointing on the signal burst caused by opening the shutter or to allow endpointing on a layer other than the first.

GetA- and GetANow: Set the comparison data points to see if the signal is rising / falling. GetA-registers the number of prevision cycles that the current data will be compared with and calculates the difference. These settings influence the determination of the slope and also the effect of S / N levels.

Is_A_50% : The events program is set to output the endpoint signal when the signal intensity is reduced to 50% of maximum. This can be changes by simply entering a different percentage value.

A_Rising: The rate at which the signal must be rising to be detected as a peak. Used to avoid noise generating a spurious endpoint in low S/N signals. Generated by the difference in GetA- / GetANow.

A_Falling: Similar to A_rising, but for a falling signal.

Percentage_OE: An over etch period can be added after endpoint detection as a % of the total milling time. Although the endpoint has been detected the no signal until over etch complete. If the % over etch is > maximum over etch the events log advises the maximum permitted time used instead.

Timed_OE: If the overetch period required is simply a know time, it should be entered here. There are basically three choices for the overetch - percentage, timed or none.

MaxOveretch:This is the maximum permitted over etch time.


End point Control:

Signal Intensity

Time

A-limit

t = Delay_A

GetA-

GetANow

DeltaA>A rising

ENDPOINTis A 50%


Ion Milling Probe – Field Service.The IMP replacement modules described below are available for immediate despatch by courier service world-wide.

For warranty repair, modules will be shipped free of charge with only shipping and clearance charges payable, if you have a courier service account number which is authorised for shipping the replacement module please forward to Hiden Analytical Inc. This will expedite the shipping procedure.

If you want Hiden to use its own courier service please send a purchase order to cover the freight and importation charges.

For out of warranty requirements a purchase order to the value of the new replacement module is required before shipment can occur. If the faulty module is returned in exchange Hiden will issue a credit note for you to ensure that you only pay the exchange module price.

Exchange is at Hiden’s discretion, if the returned part is damaged beyond repair, exchange refund may be declined.


What else does the IMP do ?• Target Impurity Determination

At the start of the etch the ion milling probe provides high sensitivity SIMS spectra for the identification of impurities from surface and primary ion source contamination.

• Residual Gas AnalysisThe integral electron impact ioniser of the IMP allows for operation as a conventional differentially pumped RGA, with software control for leak detection and gas analysis included

Documents

An overview of Hiden Analytical’s end point detector ... · An overview of Hiden Analytical’s end point detector system for ion beam etch applications. ... For out of warranty