FY13 Experimental Physics - Auger ElectronSpectroscopy

Scanning Auger MicroscopySupervisor: Per Morgen <per@fysik.sdu.dk>

SDU, Institute of PhysicsCampusvej 55

DK - 5250 Odense S

Ulrik Robenhagen, 136989 Irvin Wadzanayi Mangwiza, 121272

Jakob Kjelstrup-Hansen, 131513

May 23, 2002

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Contents

1 Auger Electron Spectroscopy 41.1 Different Auger Processes . . . . . . . . . . . . . . . . . . . . . . 41.2 Auger Electron Spectra . . . . . . . . . . . . . . . . . . . . . . . 5

2 The SDU Auger Facility 62.1 Overview of the SAM Hardware . . . . . . . . . . . . . . . . . . . 62.2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . 62.3 Differential Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 The Lock-In Amplifier 83.1 What is a Lock-in Amplifier? . . . . . . . . . . . . . . . . . . . . 83.2 Overview of Hardware . . . . . . . . . . . . . . . . . . . . . . . . 83.3 What is phase-sensitive detection? . . . . . . . . . . . . . . . . . 93.4 Narrow Band Detection . . . . . . . . . . . . . . . . . . . . . . . 103.5 The Lock-In Reference . . . . . . . . . . . . . . . . . . . . . . . . 103.6 Lock-In Amplifier Measurements . . . . . . . . . . . . . . . . . . 10

4 Experimental Procedures 124.1 Setting up the Equipment . . . . . . . . . . . . . . . . . . . . . . 12

4.1.1 The UHV . . . . . . . . . . . . . . . . . . . . . . . . . . . 124.1.2 Preparation and Transfer of Sample . . . . . . . . . . . . 124.1.3 Manual Set-up of the Auger System . . . . . . . . . . . . 13

4.2 Recording of Spectra . . . . . . . . . . . . . . . . . . . . . . . . . 134.3 Recording of SAM-images . . . . . . . . . . . . . . . . . . . . . . 13

5 Measurements 155.1 Auger spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.1.1 Identification of elements and Auger transitions . . . . . . 155.1.2 Quantification of elements . . . . . . . . . . . . . . . . . . 17

5.2 SAM-images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6 Conclusion 20

Appendix A 21

Appendix B 22

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List of Figures

1.1 Auger types, [2] p. 56 . . . . . . . . . . . . . . . . . . . . . . . . 41.2 Energy of emitted electrons, [2] p. 116 . . . . . . . . . . . . . . . 5

2.1 The Auger system in the SDU Physics Instiute . . . . . . . . . . 62.2 Comparison of non-differentiated spectrum and differentiated spec-

trum, [2] p. 61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 The different Lock-in Amplifier signals . . . . . . . . . . . . . . . 9

5.1 SEM image showing the five measuring points . . . . . . . . . . . 165.2 The SAM Image of Aluminium at electron energy of 5 kV and

relative magnification of 100 . . . . . . . . . . . . . . . . . . . . . 185.3 The SAM Image of Carbon at electron energy of 5 kV and relative

magnification of 100 . . . . . . . . . . . . . . . . . . . . . . . . . 185.4 The SAM Image of Nickel at electron energy of 5 kV and relative

magnification of 100 . . . . . . . . . . . . . . . . . . . . . . . . . 19

1 The SDU Auger System Building Blocks . . . . . . . . . . . . . . 212 The Auger spectrum measured in pos 0 . . . . . . . . . . . . . . 223 The Auger spectrum measured in pos 1 . . . . . . . . . . . . . . 234 The Auger spectrum measured in pos 2 . . . . . . . . . . . . . . 245 The Auger spectrum measured in pos 3 . . . . . . . . . . . . . . 256 The Auger spectrum measured in pos 4 . . . . . . . . . . . . . . 26

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Chapter 1

Auger ElectronSpectroscopy

The Auger spectrum of each element in the periodic table is unique and consistsof a few or more Auger electron lines. The process of creating an Auger electronstarts when a primary electron from an electron beam produces a hole in aninner shell of an atom in the sample. When an electron from a higher shell fillsthe hole in the inner shell, energy is released. The energy may be enough toallow an electron in an outer shell to leave the atom, and hereby become anAuger electron.

1.1 Different Auger Processes

Figure 1.1: Auger types, [2] p. 56

Four different types of Auger emission are shown on fig. 1.1. When anelectron from the L shell (L1 level) fill the primary hole in the K shell andan Auger electron is emitted from the L shell (L2 level), it is called a KL1L2

process (fig. 1.1 (a)).If the primary hole is in the L1 shell and the electron which fills the hole and

the Auger electron are both in the M1 shell, the process is known as a L1M1M1

process (fig. 1.1 (b)).

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Fig. 1.1 (c) shows the initial hole being filled by an electron from the sameshell, this process is called a Coster-Kronig transition. On the figure it is dis-played by a L1L2M1 process.

The valence band may be involved in the Auger process in a solid. If theprimary hole is in the L3 shell and both the electron which fills the hole andthe Auger electron are from the valence band it is called a L3V V process (fig.1.1 (d)).

1.2 Auger Electron Spectra

The AES (Auger Electron Spectroscopy) method finds the Auger electrons emit-ted from a specific point of the sample with respect to their energy.

The energy of the detected Auger electrons have been found to be in re-gion III on fig. 1.2. Regions I, II and IV shows the energy of secondary- andbackscattered electrons.

Figure 1.2: Energy of emitted electrons, [2] p. 116

As can be seen in Appendix B the Auger spectra are displayed using dN(E)dE

on the y-axis rather than N(E). This is done in order to suppress the largebackground of secondary electrons. The differentiation is done using a lock-inamplifier to detect the in-phase signal (elaborated in chapter 2).

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Chapter 2

The SDU Auger Facility

2.1 Overview of the SAM Hardware

Figure 2.1: The Auger system in the SDU Physics Instiute

The picture in fig. 2.1 shows the Auger System in the Physics Insitute at theUniversity of Southern Denmark. The system installed is the PHI Model 560and its instrumentation block diagram is shown in Appendix A. It can be seenthat the system consists of: x-ray generator, the electronic optics and controls,data processing, ultra high vacuum system, specimen handling, display systemand ion etching components. These are explained in greater detail in the PHI560 Manual (available in the laboratory and on the internet).

2.2 Functional Description

With the PHI560, a sample is excited with a focussed electron beam and theAuger electrons emitted from from the surface are energy analyzed to deter-mine Auger peak line positions and intensities. Auger Electronic Spectroscopy(AES) permits high sensitivity analysis of surface constituents. Spatial resolu-tion is excellent since the primary excitation beam can be focussed to a spotless than 1 µ m in diameter. Scanning Auger microscopy (SAM) combines AESwith a scanning electron beam to provide spatially resolved surface chemistry

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information. It also combines high speed and surface sensitivity with ability tosupply ”elemental maps” of the top monolayers of surface constituents.

The electron gun is mounted coaxially inside the electron energy analyzerto permit efficient signal collection. The coaxial geometry makes it possible toanalyze the same area of the sample with both ESCA (electron spectroscopyfor chemical analysis, also known as XPS, or x-ray photoelectron spectroscopy)and SAM so data obtained from both techniques can be correlated. The largediameter cylindrical-mirror analyzer (CMA) can be used to image a relativelywide sample area, so multiple-point Auger analysis of several separated smallfeatures is possible without moving the sample.

Before the Auger electrons are measured, they pass through an electronmultiplier to obtain a large enough signal for detection. The electron multi-plier works by ”amplifying” the number of electrons through the emission ofsecondary electrons in the multiplier.

2.3 Differential Spectrum

Because of the small Auger signals AES is usually carried out in the derivativemode to supress the large background of the true secondary electrons. Thedifferentiation is performed by superimposing a small alternating voltage v =v0sinωt on the outer cylinder voltage V and synchronously detecting the in-phase signal from the electron multiplier with a lock-in amplifier. In this modethe detector current

I(V0sinωt) ' I0 +dI

dVv0sinωt + . . .

contains the first derivative dI/dV as the prefactor of the phase-sensitively de-tected AC signal with angular frequency ω. Auger line energies are usually givenin reference works as the position of the minimum of the derivative spectrumdN/dE as shown in fig. 2.2 Note that the AES peak with a maximum at E0

generates a ”resonance”-like structure in dN/dE, whose most negative excursionat EA corresponds to the steepest slope of N(E).

Figure 2.2: Comparison of non-differentiated spectrum and differentiated spec-trum, [2] p. 61

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Chapter 3

The Lock-In Amplifier

3.1 What is a Lock-in Amplifier?

Lock-in amplifiers are used to measure the amplitude and phase of signals buriedin noise. They achieve this by acting as a narrow bandpass filter which removesmuch of the unwanted noise while allowing through the signal which is to bemeasured.

Lock-in amplifiers are used to detect and measure very small AC signals - allthe way down to a few nanovolts! Accurate measurements may be made evenwhen the signal is obscure by noise sources many thousands of times larger.

A technique known as phase-sensitive detection is used to single out thecomponent of the signal at a specific reference frequency AND phase. Thefrequency of the signal to be measured and hence the passband region of thefilter is set by a reference signal, which has to be supplied to the lock-in amplifieralong with the unknown signal. The reference signal must be at the samefrequency as the modulation of the signal to be measured. Noise signals atfrequencies other than the reference frequency are rejected and do not affect themeasurement.

3.2 Overview of Hardware

A basic lock-in amplifier can be split into 4 stages: an input gain stage, thereference circuit, a demodulator and a low pass filter.

• Input Gain Stage: The variable gain input stage pre-processes the signalby amplifying it to a level suitable for the demodulator. Nothing compli-cated here, but high performance amplifiers are required.

• Reference Circuit: The reference circuit allows the reference signal to bephase shifted.

• Demodulator: The demodulator is a multiplier. It takes the input signaland the reference and multiplies them together. When you multiply twowaveforms together you get the sum and difference frequencies as the re-sult. As the input signal to be measured and the reference signal are of thesame frequency, the difference frequency is zero and you get a DC output

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which is proportional to the amplitude of the input signal and the cosineof the phase difference between the signals. By adjusting the phase of thereference signal using the reference circuit, the phase difference betweenthe input signal and the reference can be brought to zero and hence theDC output level from the multiplier is proportional to the input signal.The noise signals will still be present at the output of the demodulatorand may have amplitudes 1000x larger than the DC offset.

• Low Pass Filter: As the various noise components on the input signalare at different frequencies to the reference signal, the sum and differencefrequencies will be non zero and will not contribute to the DC level of theoutput signal. This DC level (which is proportional to the input signal)can now be recovered by passing the output from the demodulator througha low pass filter.

The above gives an idea of how a basic lock-in amplifier works. Actual lock-in amplifiers are more complicated, as there are instrument offsets that need tobe removed, but the basic principle of operation is the same.

3.3 What is phase-sensitive detection?

Lock-in measurements require a frequency reference. Typically an experimentis excited at a fixed frequency (from an oscillator or function generator) and thelock-in detects the response from the experiment at the reference frequency. Inthe diagram below, the reference signal is a square wave at frequency ωr. Thismight be the sync output from a function generator. If the sine output fromthe function generator is used to excite the experiment, the the response mightbe the signal waveform shown in the figure. The signal is VLsin(ωLt + θref ).

Figure 3.1: The different Lock-in Amplifier signals

The lock-in amplifier amplifies the signal and then multiplies it by the lock-in reference using a phase-sensitive detector or multiplier. The output of the

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PSD is simply the product of the two sine waves.

Vpsd = VsigVLsin(ωrt + θsig)sin(ωL + θref )

=12VsigVLcos([ωr − ωL]t + θsig − θref ) − 1

2VsigVLcos([ωr + ωL]t + θsig + θref )

The PSD output is two AC signals, one at the difference frequency (ωr − ωL)and the other at the sum frequency (ωr + ωL).

If the PSD output is passed through a low pass filter, the AC signals areremoved. In general nothing is left, however, if ωr equals ωL, the differencefrequency component will be a DC signal. In this case, the filtered PSD outputwill be

Vpsd = VsigVLcos(θsig − θref )

This is a very nice signal-it is a DC signal proportional to the signal amplitude.

3.4 Narrow Band Detection

Now suppose the input is made up of signal plus noise. The PSD and low passfilter(LPF) only detect signals whose frequencies are very close to the lock-infrequency. Noise signals at frequencies far from the reference are attenuatedat the PSD output by the low pass filter (neither ωnoise − ωref nor ωnoise +ωref are close to DC.) Noise at frequencies close to the reference frequencywill result in very low frequency AC output from the PSD because |ωnoise −ωref | is small. Their attenuation depends upon the low pass filter bandwidthand roll-off. A narrower bandwidth will remove noise sources very close to thereference frequency, a wide bandwidth will allow these signals to pass. TheLPF bandwidth determines the bandwidth of detection. Only the signal at thereference frequency will result in a true DC output and be unaffected by theLPF. This is the signal that needs to be measured.

3.5 The Lock-In Reference

The Lock-in reference must be made the same as the signal frequency (ωr−ωL).Not only do the frequencies have to be the same, the phase between the signalscan not change with time, otherwise cos(θsig − θref ) will change and Vpsd willnot be a DC signal. In other words, the lock-in reference needs to be locked tothe signal reference.

Lock-in amplifiers use a phase locked loop (PLL) to generate the referencesignal. An external reference signal (in this case the reference square wave) isprovided to the lock-in. The PLL in the lock-in locks the internal referenceoscillator to this external reference, resulting in a reference sine wave at ωr witha fixed phase shift θref . Since the PLL actively tracks the external reference,changes in the external reference frequency do not affect the measurement.

3.6 Lock-In Amplifier Measurements

The lock-in amplifier multiplies the signal by a pure sine wave at the referencefrequency. All components of the input signal are multiplied by the reference

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simultaneously. Mathematically speaking, sine waves of differing frequencies areorthogonal, i.e the average of the product of two sine waves is zero unless thefrequencies are EXACTLY the same. In this lock-in amplifier, the product ofthis multiplication yields a DC output signal whose frequency is exactly locked tothe reference frequency. The low pass filter which follows the multiplier providesthe averaging which removes the products of the reference with components atall other frequencies.

Because the amplifier multiplies the signal with a pure sine wave, it measuresthe single Fourier (sine) component of the signal at the reference frequency.

Suppose the input signal is a simple square wave at frequency f . The squarewave is actually composed of many sine waves at multiples of f with carefullyrelated amplitudes and phases. A 2 V pk-pk square wave can be expressed as

S[t] = 1.273 · sin(ωt) + 0.4244 · sin(3ωt) + 0.254 · sin(5ωt) + . . .

where ω = 2π · f . The amplifier locked to f will single out the first com-ponent. The measured signal will be 1.273 · sin(ωt), not 2 V pk-pk that wouldmeasured on a scope. As a general rule, the lock-in amplifiers display the inputsignal in Volts RMS.

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Chapter 4

Experimental Procedures

The objective of the exercise was to investigate a harddisk platter using Augerelectron spectroscopy (AES). This involved sample preparation, insertion ofthe sample into the vacuum chamber, setting up the equipment, recording ofspectra (both from the immediate accessible surface and with sputtering) as wellas making Scanning Auger Microscopy (SAM) and finally data interpretation.

The first part of the exercise involved getting to know the Auger spectro-meter and UHV system. For this part a silver sample was used as the objectof investigation. The second part of the experiment involved the investigationof the harddisk platter. The preparation of the sample had already been per-formed during a previous experiment (with the scanning electron microscope).The piece of the harddisk platter had already been mounted, so the measure-ments could be performed as soon as the equipment had been set up.

4.1 Setting up the Equipment

The tasks can be divided into: preparation and checking of the UHV system,sample preparation, sample transfer and adjustment, manual set-up of the Augersystem, Lock-in amplifier set-up, and set-up of communications with the com-puter. All these steps are described in the JEOL manual, the lock-in amplifiermanual and in the computer program documentation.

4.1.1 The UHV

A mass spectrometer is used to monitor the UHV system and also to check forleaks. The target pressure is 10−10 Torr in the experiment, one could see peaksfor H, hydrocarbons; CH, CH2, CH3 and Ar in ionized form. When there isa leak one can see O2 and N . Pressure is monitored and the spectra checkeduntil the desired condition is achieved.

4.1.2 Preparation and Transfer of Sample

Just like in the SEM experiment, it is a good practice to have gloves on whilehandling the sample. The sample is inserted via a transfer chamber. This isdone to avoid breaking the vacuum. Nitrogen is used in the little chamber tokeep humidity out. The electronics have to be switched on before the transfer

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but the electron multiplier has to be off. The sample is centered with the helpof the CRT. The sample has to be placed at the focal point of the spectrometer.

4.1.3 Manual Set-up of the Auger System

The sample is shifted until a known energy is in focus. This energy is usedfor calibration. The equipment is then switch from the bottom up. The beamvoltage is set to the desired level and the filament voltage adjusted. The magni-fication is adjusted by use of the ’Emission’ and ’Relative Magnification’ knobs.The point of interest is chosen on the sample. After this control is given to thecomputer, via the lock-in amplifier.

4.2 Recording of Spectra

The spectra were recorded using a computer connected to the Auger system. Inthis way, the measuring procedure is automated, so that only an initial calibra-tion procedure is necessary whereafter the computer controls the rest.

The program used for this part is called ”PHI-Sem-Lock”. Using this pro-gram, the energies of the recording system is first calibrated using two points(approx. 0 eV and 1500 eV ).

Next a SEM image was obtained. Based on this image, the points, where thespectra are to be measured, were chosen. Five different spectra were measuredin a single step. The settings for these different spectra was set independently.For these recordings, the following settings were used:

• Time constant (duration of scan at each particular energy): 200 ms

• Amplitude of the oscillating voltage: 0, 4 V rms

• Sensivity: 5mV

• Number of scans: 3

• Minimum measuring energy: 50 eV

• Maximum measuring energy: 1000 eV

Next the recording procedure was started and after completion the spectrawere stored.

4.3 Recording of SAM-images

Based on the spectra showing the constituents in the harddisk platter, SAM-images of some of the elements were recorded. The precedure is to choose anenergy level, which corresponds to an Auger energy level of one of the con-stituents. Then the spectrometer was set to exactly this energy, and a scan overa section of the harddisk was made.

It was chosen to make scans of Nickel, Carbon and Aluminium. The sectioninvestigated was the very top of the filed wedge, so that both the coating andthe top of the aluminium layer was present.

The program used for this part was the ”Fast-Sem-Sam”. Again a few pa-rameters were set before the measurements was performed. These were:

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• Delay (recording time at each point): 10 ms

• Resolution: 256 by 256 points

Afterwards, the automated recording procedure was started and the imagesstored on the computer.

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Chapter 5

Measurements

In this part, the measurements from the sample will be presented. Differentkinds of measurements were made. First several spectra were recorded on dif-ferent locations on the sample, each of them showing the local element composi-tion. Based on these recordings, some elements were chosen to investigate moreextensively. This was done by scanning a larger area of the disk and collectingthe Auger electrons from this particular element, therby obtaining an Augerimage.

5.1 Auger spectra

The initial SEM-image is shown in fig. 5.1. This image was recorded using anaccelerating voltage of 5 kV and a relative magnification of 100 (correspondingto an actual magnification of 500 times).

Also shown are the five points chosen to be investigated. The first point ison the top of the harddisk platter, while the others are placed of the wedge closeto the top of the platter. These points were chosen in order to determine thecomposition of the sample near the top. The obtained spectra are included asappendices.

5.1.1 Identification of elements and Auger transitions

When interpreting these spectra, one must consult an Auger-table giving thecharacteristic Auger-energies of all of the different elements [3]. This has beendone, and in the following, the spectrum shown in fig. 4 is used as an example.This spectrum is recorded on the wegde of the platter very near the top, soit is expected to show some magnetizable elements along with the basis of theplatter which is Al.

The first peak is located near 70 eV , which must be the aluminium, sincethis element has an Auger-transistion of 68 eV . The next peak appears aroundmidways between 100 eV and 150 eV , which must be due to phosphorus. Thiselement has a strong peak in its Auger-spectrum at 120 eV .

A little above 200 eV , a small peak can be observed, which stems from Argon(215 eV ). This is probably due to the Argon, which is present in the diamondcoating layer.

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Figure 5.1: SEM image showing the five measuring points

A strong peak is seen midways between 250 eV and 300 eV . This mustbe carbon, since it has an Auger-transistion giving of an electron of 272 eV .It seems reasonable that carbon should also be present, since the platter mostlikely is coated with some diamondfilm or equivalent to harden the surface.This peak is also seen in the spectra measured on the top (fig. 2) but here itis much stronger. Another explanation of the presence of carbon could be, thatthe sample was contaminated with carbon before it was placed in the vacuumchamber.

Around 500 eV some peaks are seen, which corresponds to oxygen (490 eVand 510 eV ). The rest of the strong peaks are in the region between approx.650 eV and 850 eV . The large peak around 850 eV comes from nickel, whichhas a distinct Auger energy of 848 eV . Nickel however has quite a few peaksand these are probably the ones seen in the region of the spectrum. These are716 eV , 775 eV , 783 eV and 865 eV . Also it is possible, that cobalt is present.This element shows some peaks very close to the peaks in the Ni-spectrum, andit might then be present also, but this is a little difficult to insure from thesespectra.

On fig. 4 these elements have been marked. The other spectra are seen tocontain all or some of the same elements in other quantities.

The transitions of the different elements have been identified using the figurefound at www.eaglabs.com/cai/augtheo/energies.htm. These can be seen ontable 5.1:

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Aluminium LMMPhosphorus LMM

Argon LMMCarbon KLLOxygen KLLNickel LMMCobalt LMM

Table 5.1: Transitions of elements

5.1.2 Quantification of elements

AES can also be used for a more quantitative analysis, where the concentrationof the different constituents can be found from the obtained spectra. The basicidea involves comparing the height of the peaks in the spectrum to the peakheight of Ag in a pure silver sample. The concentration of all of the constituentscan then be found using an approiate sensitivity factor (found in tables of AES).To determine the concentration of element X, the following formula can beemployed:

CX =IX

SX,AgIAg

,where IX and IAg are the peak heights of element X and silver respectivelyand SX,Ag is a sensitivity factor.

The height of the silver peak was not measured, however the equipmentwas calibrated in a manner so that the silver peak height corresponds to a fullscale read-out. Also the sensitivity factors are needed, which can be found athttp://www.eaglabs.com/cai/augtheo/emission.htm.

It is chosen only to make this quantitative analysis in one of the five points(point 2). The following table gives the ratio between the peak height of theindividual peaks as well as their sensitivity factor:

X Al P Ar C O Ni CoSX,Ag 0,19 0,43 1,1 0,13 0,4 0,27 0,23IX/IAg 0,50 0,17 0,066 0,48 0,14 0,80 ???

Table 5.2: Ratio of peak heights of elements

A few things should be pointed out: The sensitivity factors given in table 5.2is taken from the source given above. Here several factors are presented, eachof them for a different transistion. In table 5.2 the given numbers are thosecorresponding to the actual transistions as identified previously. The secondthing to observe is the problem of determining the concentration of cobalt. Thepeaks in the spectrum does not allow for this, since the Ni-peaks are too closefor a certain identification of the Co-peaks. Therefore cobalt is not includedis this analysis, which then will give a small error on the figures of the otherelements. By using the above formula the following concentrations are foundand presented in table 5.3.

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Element Al P Ar C O Ni CoConcentration [%] 9,5 7,4 7,2 6,2 5,6 21,7 ???

Table 5.3: Concentration of elements

This does unfortunately not sum up to 100 % as expected. One of thepossible explanations is, that Co is not included, however this can not explain therather large deviation. The explanation then must be, that the measurements /the method does not yield a very accurate result. But at least the ratio betweenthe different constituents are observable from the data given in the table above.

5.2 SAM-images

In order to acquire SAM images one takes a look at the prevously recordedAuger Spectrum, finds the interesting peaks, for example carbon at 277 eV .The spectrometer is then adjsted to this energy level, while checking the qualityof the image on the CRT. The lock-in amplifier is then set to, say 10 ms timeconstant, and the image is acquired by use of a computer program.

Figure 5.2: The SAM Image of Aluminium at electron energy of 5 kV andrelative magnification of 100

Figure 5.3: The SAM Image of Carbon at electron energy of 5 kV and relativemagnification of 100

A slow scan is desirable in order to capture maximum information. Bylooking at the picture and using experience one see that there exists some sort

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Figure 5.4: The SAM Image of Nickel at electron energy of 5 kV and relativemagnification of 100

of structure (composition).These images show where some of the different constituents in the sample

are located. A darker area corresponds to a higher concentration. The imageof aluminium shows an area on the middle, where the concentration seems tobe high. This is rather surprising, since it was expected, that the aluminiumconcentration would be higher in the lower part of the platter (the left side ofthe image). The SAM-image of carbon shows, that most of the carbon is foundon top of the platter, which seems likely because of the diamond film. The finalSAM-image shows the concentration of nickel, which is seen to be found justbelow the surface. This is also expected, since nickel is a part of the magneticstructure of the harddisk.

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Chapter 6

Conclusion

In this exercise a piece of harddisk platter was investigated by Auger ElectronSpectroscopy (AES) and Scanning Auger Microscopy (SAM). Applications ofAES and SAM investigated in this exercise include an elemental analysis, wherethe composition at different points of the sample was determined from Augerspectra. This showed, that the following elements were present in the sample:aluminium, phosphorus, argon, carbon, oxygen, nickel and cobalt. The transi-tions in the individual elements corresponding to the observed Auger lines werealso identified.

The measured spectra were also used for a quantitative analysis of the sur-face. This technique did unfortunately not prove to be very accurate, but it wasable to give some insight into the concentrations of the different elements in asingle point on the surface. Finally SAM was used to determine the location ofsome of the elements.

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Appendix A

Figure 1: The SDU Auger System Building Blocks[1]

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Appendix B

Figure 2: The Auger spectrum measured in pos 0

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Figure 3: The Auger spectrum measured in pos 1

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Figure 4: The Auger spectrum measured in pos 2

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Figure 5: The Auger spectrum measured in pos 3

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Figure 6: The Auger spectrum measured in pos 4

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Bibliography

[1] JEOL Manual for JEOL JSM-35CF

[2] Luth Surfaces and Interfaces of Solid Materials

[3] Physical Electronics Industries Handbook of Auger Electron Spectroscopy

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