focused-ion-beam material removal rates · in this program, we studied various materials used in...

AD-A270 852SIll II 111111111 lillI I

ARMY RESEARCH LABORATORY

Focused-Ion-Beam MaterialRemoval Rates

by Bruce GeOl

ARL-MR-1 14 September 1993

93-25165

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4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Focused-Ion-Beam Material Removal Rates PE: 91A

6. AUTHOR(S)

Bruce Geil

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION

U.S. Army Research Laboratory REPORT NUMBER

Attn: AMSRL-WT-NG ARL-MR-1 14

2800 Powder Mill RoadAdelphi, MD 20783-1197

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1. ABSTRACT (Maixditll20 words)

Focused-ion-beam milling is a tool used in failure analysis and production of integrated circuits.This technique uses a focused gallium beam to mill away materials on a surface. Each material millsat a different rate, which must be experimentally determined. The data presented here for severalmaterials used in standard integrated circuit processes will allow the user to determine the dose levelneeded to mill a certain amount of a given material.

14. SUBJECT TERMS 15. NUMBER OF PAGES

20Focused ion beam, material removal rates 16. PRICE CODE

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Pr-escted by ANSI Sid Z39-18298-102

Contents

Page

1. Introduction ........... .............................................................................................................................. 5

2. M ethod .................................................................................................................................................. 5

3. Results ................................................................................................................................................... 7

4. Conclusions ........................................................................................................................................ 16

A cknow ledgm ents ................................................................................................................................. 17

D istribution ............................................................................................................................................ 19

Figures

1. Profile of com pleted m ill .............................................................................................................. 62. SEM m icr-araph of m illed regions ............................................................................................. 73. D epth versus dose for gallium arsenide ................................................................................... 104. Depth versus dose for 28-percent aluminum gallium arsenide ............................................ 105. D epth versus dose for polysilicon ............................................................................................. 106. D epth versus dose for silicon dioxide ....................................................................................... 117. D epth versus dose for silicon carbide ........................................................................................ 118. D epth versus dose for barium titanate ..................................................................................... 119. D epth versus dose for alum inum ................................................................................................ 12

10. D epth versus dose for silicon nitride ........................................................................................ 1211. D epth versus dose for gold ......................................................................................................... 1212. Rate versus dose for gallium arsenide ...................................................................................... 1313. Rate versus dose for 28-percent aluminum gallium arsenide ................................................ 1314. Rate versus dose for polysilicon ............................................................................................... 1315. Rate versus dose for silicon dioxide ........................................................................................... 1416. Rate versus dose for silicon carbide .......................................................................................... 1417. Rate versus dose for barium titanate ........................................................................................ 1418. Rate versus dose for evaporated alum inum ........................................................................... 1519. Rate versus dose for e-beam deposited alum inum ................................................................. 1520. Rate versus dose for silicon nitride .......................................................................................... 1521. Rate versus dose for sputtered gold .......................................................................................... 1622. Rate versus dose for evaporated gold ....................................................................................... 16

Tables

1. M ill rate data ......................................................................................................................................... 82. D ata analysis ......................................................................................................................................... 9

Alccession For

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A at "I.t r/' 3,Dist ý3Peal.1

1. IntroductionFocused-ion-beam (FIB) systems have been used for several years in fail-ure analysis of integrated circuits and the repair of photomasks. Forintegrated-circuit failure analysis, the FIB is used for the selective removalof materials (known as "milling") in areas of the circuit, so that the circuitcross sections can be examined. The problem with milling through an inte-grated circuit is that the mill rates vary for the many different kinds ofmaterials used in semiconductor processing. If the rate at which a materialmills is unknown, one cannot accurately calculate mill depths. We per-formed the work described here to study the material removal rates of dif-ferent microelectronic device materials.

An FIB system is composed of three major components: a vacuum system,electronics systems, and an ion-beam column. The ion column has twomajor components. The first component is the gallium source, which is asmall Y-shaped wire. The gallium is stored at the center of the Y and theions are pulled off of the base of the Y. Once the ions are pulled off thesource, they are accelerated to 25 keV, focused, and stigmated through theremainder of the column. The second major component of the column isthe electronics required to steer the ion beam over the sample. When theions hit the sample, the kinetic energy of the impact knocks ions off thesample, thus forming a cavit in the sample. This cavity can be as small as0.5 [Am 2 or as large as 80 •mZ.

The data obtained in milling these materials have been used for variousprograms. We used the FIB to study the etch profile of silicon dioxide forproduction of quantum wires. These wires were used by the University ofMaryland to study quantum effects in stressed gallium arsenide. In a U.S.Army project to develop optical integrated circuits, we used these data todetermine the proper depth and time for milling waveguide facets. Wealso used these data in a Navy program to develop a semiconductorignitor, 1 to determine the etch profile of a silicon dioxide layer buriedunder two other levels of material. For this program it was very importantthat the circuit levels underneath the silicon dioxide not be damaged dur-ing the milling.

2. MethodIn this study, the FIB system used was a Micrion 808 mask repair system.This fully automated system uses gallium ions as described above to millthe material. The system has a beam spot size of 200 nm at 25 keV ofextraction voltage. The extraction voltage determines the power of thebeam: if the voltage is increased, the ions will strike the surface with higherkinetic energy. This can cause problems when one is trying to mill mate-rial, since the higher energy causes the ions to tunnel into the materialinstead of removing it. The beam current varies between 366 pA, when anew aperture is being used, and approximately 450 pA as the aperture in

1J. McCullen, J. Terrell, and R. Reams, Electrical Characterization of a Semiconductor Primer Ignitor Chip forAmmunition, Harry Diamond Laboratories, HDL-TM-92-13 (July 1992).

the system ages. The aperture increases in size as the beam passes throughit, which increases the beam size and the amount of current that passesthrough the aperture. The system monitors this current during the millingprocess so changes in the current do not affect the dose being applied to agiven area. The increase in current reduces the time required to apply thedose to the area, thus increasing the milling rate. The beam is scanned overthe dcesignated area using a dwell time of 300 us per pixel with an overlapof 160 nm for every pixel. The largest area that can be milled is an 80- x 80-ýLrm field. Areas any larger than this cause a decrease in the overlap of thepixels, thus changing the mill rate and resulting in a more ragged cavity.Both the dwell time and the pixel overlap are adjustable to compensate formachine variations. Adjustment of the dwell time can also reduce theamount of gallium implanted into the substrate during the milling process.

In this program, we studied various materials used in semiconductor proc-essing, specifically, gallium arsenide, single crystalline polysilicon,28-percent aluminum gallium arsenide, thermally grown silicon dioxide,both evaporated and e-beam deposited aluminum, barium titanate, sput-tered and evaporated gold, silicon carbide, and silicon nitride. We appliedthese materials to a silicon substrate except for the samples of gallium ar-senide and aluminum gallium arsenide, which we milled in solid form.After we deposited each material, we etched away a small area usingeither wet or plasma etch techniques. We then used a profilometer todetermine the initial depth of the material. In all cases, we left at least1000 A of material after the FIB mill to prevent any sublayers from affect-ing the milling rate. We performed all mills in the center of the sample toprevent any edge effects. Once the samples were in position, we milledfour 10- x 60-um boxes into each sample. Figure 1 shows the plot obtainedfrom the profilometer and figure 2 shows how the actual milled areasappear. We milled each one of these boxes using a different dose of ionsper square micron. When we completed the milling, we measured thedepth of the etched areas using a Tencor Alpha Step 200 profilometer. Thisprofilometer has a resolution of 5 nm in the vertical and 40 nm in the hori-zontal range. All the measurements on the profilometer were done usingthe 80-lm scan field at 25 samples per micrometer.

Figure 1. Profile ofcompleted mill. I

0 .......... ..•

.. 1i L"................... ................................t•~~~.. -2...............".

-3

-4

0 20 40 60 80Width (urm)

6

Figure 2. SEMmicrograph of milledregions.

3. ResultsTable 1 shows the raw data which demonstrate the degree of mill rate lin-earity of various doses of the materials studied. The first column is the areadose in nC/ pm 2 that was entered into the FIB system. The second columnis the dose converted to ions per square centimeter. The depth in ang-stroms is the average depth the profilometer calculates using a line-averaging method to average out minor height variations. The next twocolumns are the calculated values of the mill rate in pim 3/s. This value wascalculated using the equation

Rate = amps/dose - depth.

Two different values for the current were used to give a range of usefulrates for the system dependent on the functional beam current. The currentvalues chosen to calculate this rate are 366 and 450 pA. To check the degreeof linearity, a least-squares-fit approximation was applied to each set ofdose versus depth data and is shown in table 2. In all cases the returnedcoefficient of determination was greater than 0.950, which indicates a highdegree of linearity. Since a curve fit was done, the values for the slope andy-intercept are also indicated next to the degree of linearity. Figures 3through 11 show the depth and area dose data plotted with the dose innC/ gm 2 on the x axis and the depth in angstroms on the y axis. Figures 12through 22 show the area dose and mill rate plotted with the dose in nC/pm 2 on the x axis and the mill rate in pm3 /s on the y axis. The repeatabilityof these values is within five percent. The repeatability of these data isaffected by several parameters including the focus and stigmation of thesystem during the mill, the ion sputtering rate of the material, and the ageof the aperture in the system.

7

Table 1. Mill rate Dose Dose Depth Rate 0.366 pA Rate 0.450 pAdata. (nC / um 2) (ion/cm2 ) (A) (Jm 3 / s) (gIm 3 /s)

Gallium arsenide

0.250 1.56 x 1017 2445.000 0.35795 0.440100.500 3.13 x 1017 4260.000 0.31183 0.383401.000 6.25 x 1017 8550.000 0.31293 0.384751.500 9.38 x 1017 13270.000 0.32379 0.398102.000 1.25 x 1018 17440.000 0.31915 0.39240

28% aluminum gallium arse,-ide

0.250 1.56 x 1017 1920.000 0.28109 0.345600.500 3.13 x 1017 3560.000 0.26059 0.320400.750 4.69 x 1017 5620.000 0.27426 0.337201.000 6.25 x 1017 7475.000 0.27359 0.336381.500 9.38 x 1017 11440.000 0.27914 0.34320

Polycrystalsilico:,

0.250 1.56 x 1017 775.000 0.11346 0.139500.375 2.34 x 1017 1135.000 0.11078 0.136200.500 3.13 x 1017 1735.000 0.12700 0.156150.750 4.69 x 1017 2720.000 0.13274 0.163201.000 6.25 x 1017 3385.000 0.12389 0.15233

Silicon dioxide

0.010 6.25 x 1015 30.000 0.10980 0.135000.020 1.25 x 1016 60.000 0.10980 0.135000.040 2.50 x 1016 80.000 0.07320 0.090000.080 5.00 x 1016 175.000 0.08006 0.098440.125 7.81 x 1016 375.000 0.10980 0.135000.160 1.00 x 1017 400.000 0.09150 0.112500.250 1.56 x 1017 880.000 0.12883 0.158400.375 2.34 x 1017 1430.000 0.13957 0.171600.500 3.13 x 1017 1840.000 0.13469 0.16560

Silicon carbide

0.250 1.56 x 1017 425.000 0.06222 0.076500.500 3.13 x 1017 715.000 0.05234 0.064350.750 4.69 x 1017 1090.000 0.05319 0.065401.000 6.25 x 1017 1510.000 0.05527 0.06795

Barium titanate

0.500 3.13 x 1017 500.000 0.03660 0.045001.000 6.25 x 1017 2100.000 0.07686 0.094501.500 9.38 x 1017 3500.000 0.08540 0.10500

Evaporated aluminum

0.250 1.56 x 1017 740.000 0.10834 0.133200.500 3.13 x 1017 1190.000 0.08711 0.107100.750 4.69 x 1017 1940.000 0.09467 0.116401.000 6.25 x 1017 2480.000 0.09077 0.11160

Electron-beam deposited aluminum

0.500 3.13 x 1317 1070.000 0.07832 0.096300.750 4.69 x 1017 1580.000 0.07710 0.094801.000 6.25 x 1017 2095.000 0.07668 0.09428

8

Table 1. Mill rate Dose Dose D. th Rate 0.366 pA Rate 0.450 pAdata (cont'd). (nC/um 2) (ion/ cm 2) (A) (tm 3 /s) (ILm3 / s)

Silicon nitride

0.250 1.56 x 1017 385.000 0.05636 0.069300.500 3.13 x 1017 900.000 0.06588 0.081000.750 4.69 x 1017 1455.000 0.07100 0.087301.000 6.25 x 1017 2100.000 0.07686 0.09450

Sputtered gold

0.020 1.25 x 1016 600.000 1.09800 1.350000.040 2.50 x 1016 1200.000 1.09800 1.350000.080 5.00 x 1016 2100.000 0.96075 1.181250.100 6.25 x 1016 2240.000 0.81984 1.008000.125 7.81 x 1016 2850.000 0.83448 1.026000.160 1.00 x 1017 3500.000 0.80063 0.984380.200 1.25 x 1017 5075.000 0.92873 1.141880.300 1.88 x 1017 7740.000 0.94428 1.16100

Evaporated gold

0.050 3.13 x 1016 875.000 0.64050 0.787500.075 4.69 x 1016 950.000 0.46360 0.570000.100 6.25 x 1016 1275.000 0.46665 0.573750.150 9.38 x 1016 1720.000 0.41968 0.51600

Table 2. Data analysis.

Linear-fit Zero dose Average mill rate Average mill ratedose mill rate depth intercept Coefficient 366 pA 450 pA

Material (ptm 2 .A/nC) (A) of determination (pam3/s) (ptm 3 /s)

Gallium arsenide 8689.27 69.27 0.999 0.325 0.400

28% aluminium 7673.51 -135.81 1.000 0.274 0.337gallium arsenide

Polycrystalsilicon 3601.72 -120.99 0.996 0.122 0.149

Silicon dioxide 3838.93 -79.86 0.995 0.109 0.134

Silicon carbide 1452.00 27.50 0.997 0.056 0.069

Barium titanate 3000.00 -966.67 0.999 0.066 0.082

Evaporated aluminum 2388.00 95.00 0.999 0.095 0.117

Electron-beam deposited 2050.00 44.17 1.000 0.077 0.095aluminum

Silicon nitride 2280.00 -215.00 0.999 0.068 0.083

Sputtered gold 25096.49 -52.36 0.986 0.936 1.150

Evaporated gold 8891.43 371.43 0.974 0.498 0.612

9

Figure 3. Depth 20000

versus dose for I8o00gallium arsenide.

14000-

<12000-

~10000-

00-

0 I I t I I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 20

Dose (nC/ýpm 2 )


versus dose for 28- 18000percent aluminumgallium arsenide.

14000

12000

.C10000.

0 8000

6000-

4000

2000-

o~ I I I I I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/Rm2)

Figure 5. Depth 20000-

versus dose for 180-0polysilicon. 10-

14000-

.12000.. 10000-

6000-

4000-

20000 I I I I I I I I I I

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/hm 2)

10

Figure 6. Depth 200

versus dose for 18O1silicon dioxide.

14W,~

1221,10

S10000-0.

dose or siicon 8000.

6000

4000-

2000.

0

0 0.2 0.4 0.6 0.8 1.0 1.2 14 1.6 1i 20

Dose (nC/hm 2)

Figure 7. Depth versus 20000

dose for siliconcarbide.

16000

14000

12000

10000-

Q* 8000

6000-

4000

2000-

0. I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/4m 2 )


dose for barium100titanate.

16000-

14000-

12000-

~1000C)o8000-

6000-

4000

2000-

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/pIm 2)


dose for aluminum. 1800 --- e~ctron beam depos

16000- alumir um

---evaporated ajurmnumn

140 0 0

S10000

0 8000

6000

4000

2000-

0 I i i I I I I i I i0 02 0.4 0.6 0.8 1.0 1.2 14 16 1.8 2.0

Dose (nC/bm 2 )


versus dose for silicon 1io00nitride.

16000

14000

z12000

~10000o 8000

6000

4000

2000-

0 I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/Rm2)


versus dose for gold. 1so0o

16000 ----evaporated gold

sputtered gold

14000

- 12000

10000O0.

o8000-6000/-

4000./

2000

0- I I I I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nCIpm 2 )

12

Figure 12. Rate versus 0.50

dose for gallium 045arsenide.

0.40

0.35-

C- 0.30E5 0.25-

S0.20-cc . 0.450 pA

0.15 - 0.366 pA

0.10-

0.05-

0 I I I I I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/[m2)

Figure 13. Rate versus 0.50 -

dose for 28-percent 0.45

aluminum galliumarsenide. 0.43

S0.35

S0.30

0.25

CO 0.20C 0.450 pA

0.1505 0.366 pA

0.10

0.05

0 I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/Im2)


dose for polysilicon. 0.18

0.16

0.14

S0.12

0.10

cc 0.08

0.06 - 0.450 pA

0.04-- 0.366 pA

0.02

0I I I I I I I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/p M2 )

13


dose for silicondioxide.

0.20

( 0 .1

E

0 .1 -010-- 0.- O0. PA

-- 0366 pA0.05-

0 j I 1 I t I I I I I

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/p.m2)


dose for silicon - 0. 450 pA

carbide. --- 0.30.20

E o.15

0o.10

0.05

0 i I i i I

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/Rm 2)


dose for barium 0.450 PA

titanate. 0.366 pA

'. 0.15

0.10

0.05

0 0.2 0.4 0.6 O.8 1.0 1.2 1.4 1.6 1.8 2.0

Dose (nC/pm2 )

14


dose for evaporated -.- 045opAaluminum. -- 0.366 PA

0.20

c• 0.15E

M0.10-

0.05

0* I I I I I I I I

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/hm 2)

Figure 19. Rate versus 0.10dose for e-beam 0 'deposited aluminum.

0.08

0.07

e" 0.06E; 0.050

¢ 0.04o- 0.450 pA

0.03 -- 0.366 pA

0.02

0.01

I I I I I I I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/[Im 2 )

Figure 20. Rate versus 0.10dose for siliconnitride.0.o8 -

0.070.0

S0.06-

EC,D"- 0.05

0.04M 0.03- 0.450 pA

00-- 0.366 pA

0.02

0.01

0 I I I I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Dose (nC/1m 2)

15

Figure 21. Rate versusdose for sputtered 1.4

gold. 1.2

1.0

E 0.8

S0.60.6-0.450 pA

0.4 0.366 pA

0.2

0 I I I I I I i I I

0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0,40 0.45 0.50

Dose (nC/LM2 )

Figure 22. Rate versus 1.0dose for evaporated 0.9gold.

0.8

-~0.7-

E 0.6

a, 0.5

- 0.4- 0.450 pA

0.3 --- 0.366 pA

0.2

0.1

0.I I I I

0 0.05 0.10 0.15 0.20 0.25

Dose (nC/gm2)

4. ConclusionsThe data obtained from this research show that each material has a specificmaterial removal rate. Of the materials tested, gold milled the fastest; thisindicates that the atomic weight of the material does not play a significantrole in the removal process. Gold, which has an atomic weight of 196.9665,is milled at a rate of 0.8891 tLm 3/nC, while silicon carbide, which has anatomic weight of 32.0855, mills at a rate of 0.1452 tm 3/nC. The milling rateof the test material correlates with the sputter etch characteristics of thematerial. When a material is impacted by the gallium ion, the kineticenergy of the ion breaks apart the bonds of the material if the energy of theion is greater than the binding energy of the material. The energy neces-sary to break the bonds of the material, or threshold energy, is between 5and 40 eV. The other factor affecting the sputter rate of the material is theangle of incidence of the ion beam. For most materials, the highest sputteretch rate occurs when the angle of incidence is 450 from the normal. For the

16

data presented here, all milling was done at normal incidence. For gold,the highest sputter etch rate occurs at 0' angle of incidence and decreasesas the angle increases. 2 This explains why the gold, with the highestatomic weight, still etches the fastest of all the materials tested.

For most of the materials tested, the depth-to-dose data we obtained corre-lated very well with a straight line. This correlation allows linear approxi-mation for dose values at a given depth. For some of the materials wetested, the calculated y intercept was more than 100 A above or below thezero point. This effect could be caused by several factors. At low dose lev-els, the ions are being implanted into the surface rather than removing anymaterial. This low-dose effect is more pronounced with a material such asbarium titanate, which has a very slow mill rate. The other possible causeof this non-linearity is the profilometer accuracy for very small stepheights. In the case of the evaporated gold, the mill rates are so high thatsmall depths cannot be easily milled into the surface. This causes a lack ofdata at the smaller doses. The slope and y values of the linear approxima-tion are given in table 2. Table 2 also shows the average mill rate for amaterial at a given beam current. The data in this table will help in the cal-culation of dose or depth values and milling time for a given material.

For those wishing to use the FIB milling capability available at the semi-conductor electronics materials technology facility, these data will allowthem to determine the time and dose required to mill their samples.

AcknowledgmentsI wish to thank Tim Mermagen and Mark DiManna for doing the prelimi-nary studies on the milling rates of materials, Scott Merritt at the Univer-sity of Maryland for supplying the gallium arsenide samples, and GeorgeSimonis for technical information and support. I especially want to thankJon Terrell and Judy McCullen for depositing several of the materials tothe silicon substrates.

2David J. Elliott, Integrated Circuit Fabrication Technology, McGraw-Hill, Inc. (1982).

17

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SafetyNaval Surface Warfare CenterAttn: Dep Under Sec /Res & Advanced Tech NvlSraeWraeCneAttn: Dep Under Sec/Test & Edvaluationc Attn: Code WR, Research & Technology DeptAttn: Dep Under Sec/Test & EvaluationAtnDX2LiryDv

Department of Defense Attn: DX-21 Library DivWashington, DC 20301 Dahlgren LaboratoryDahlgren, VA 22448

Commander Booz-Allen & Hamilton, IncUS Army Materiel Command Attn: J. TerrellAttn: AMCDE, Dir for Dev & Engr 8283 Greerre rvAttn: AMCDE-R, Sys Eval & Testing 83Gens DriveAttn: AMCNC, Nuclear-Chemical Ofc McLean, VA 221025001 Eisenhower Ave Micrion CorporationAlexandria, VA 22333-0001 Attn: D. Stewart

Commander One Corporation Way, Centennial Park

CECOM R&D Tech Library Peabody, MA 01960-7990

Attn: ASQNC-ELC-IS-L-R U.S. Army Research LaboratoryFT Monmouth, NJ 07703-5018 Attn: AMSRL-D-C, Legal Office

Director Attn: AMSRL-OP-CI-AD, Library (3 copies)Attn: AMSRL-OP-CI-AD, Mail & Records

US Army Electronic Warfare Laboratory, Ma RLABCOM Mgmt

LABCOMAttn: AMSRL-OP-CI-AD Tech PubAttn: ASQNC-ELC-IS, Information Services Attn: AMSRL-EP-EE. G c i un

Div Attn: AMSRL-EP-EE, G. SimonisAttn: AMSRL-EP-EE, M. SteadAttn: AMSRL-SL-NC, J. McCullen

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Distribution (cont'd)

US Army Research Laboratory (cont'd) US Army Research Laboratory (cont'd)Attn: AMSRL-SS-F, R. B. J. Goodman Attn: AMSRL-WT-NG, ChiefAttn: AMSRL-SS-IA, T. Tayag Attn: AMSRL-WT-NG, H. BoeschAttn: AMSRL-SS-IA, N. Gupta Attn: AMSRL-WT-NG, Harvey EisenAttn: AMSRL-WT-CS, Chief Attn: AMSRL-WT-NG, J. BenedettoAttn: AMSRL-WT-E, Chief Attn: AMSRL-WT-NG, K. W. BennettAttn: AMSRL-WT-EH, Chief Attn: AMSRL-WT-NG, M. DeLanceyAttn: AMSRL-WT-EP, Chief Attn: AMSRL-WT-NG, R. B. ReamsAttn: AMSRL-WT-ES, Chief Attn: AMSRL-WT-NG, R. MooreAttn: AMSRL-WT-L, R. Gilbert Attn: AMSRL-WT-NG, T. GriffinAttn: AMSRL-WT-N, J. M. McGarrity Attn: AMSRL-WT-NG, T. MermagenAttn: AMSRL-WT-NB, D. Davis Attn: AMSRL-WT-NG, T. OldhamAttn: AMSRL-WT-ND, J. R. Miletta Attn: AMSRL-WT-NG, T. TaylorAttn: AMSRL-WT-NG, A. J. Lelis Attn: AMSRL-WT-NH, H. BrandtAttn: AMSRL-WT-NG, B. Geil (15 copies) Attn: AMSRL-WT-P, ChiefAttn: AMSRL-WT-NG, B. J. Rod Attn: AMSRL-WT-RS, ChiefAttn: AMSRL-WT-NG, B. McLean Attn: AMSRL-WT-TN, ChiefAttn: AMSRL-WT-NG, C. Pennise Attn: AMSRL-WT-TS, Chief

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focused-ion-beam material removal rates · in this program, we studied various materials used in...

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