Ferrara & LNL Crystal farm and Ferrara & LNL Crystal farm and validation procedurevalidation procedure

Geneva,9-10 March 2006Geneva,9-10 March 2006

Vincenzo GuidiVincenzo GuidiFerraraFerrara

Alberti AlbertoAlberti AlbertoAntonini AndreaAntonini AndreaBenvenuti ElenaBenvenuti ElenaButturi MariangelaButturi MariangelaCruciani GiuseppeCruciani GiuseppeDalpiaz Pietro Dalpiaz Pietro Fiorini MassimilianoFiorini MassimilianoGuidi VincenzoGuidi VincenzoMartinelli GiulianoMartinelli GiulianoMilan EmilianoMilan EmilianoRizzoni RaffaellaRizzoni RaffaellaRonzoni AlessandroRonzoni AlessandroTralli AntonioTralli Antonio

LegnaroLegnaro

Della Mea GianantonioDella Mea GianantonioMilan RiccardoMilan RiccardoQuaranta AlbertoQuaranta AlbertoVomiero AlbertoVomiero AlbertoCarturan SaraCarturan SaraNegro EnricoNegro EnricoPieri UgoPieri UgoCarnera AlbertoCarnera Alberto

OutlineOutline

• Crystal fabrication: dicing, lapping and Crystal fabrication: dicing, lapping and polishing techniquespolishing techniques

• Sample characterizationSample characterization• Film with internal stressFilm with internal stress• Zeolities: A novel materials for Zeolities: A novel materials for

channelingchanneling• Multilayered crystal mirrorMultilayered crystal mirror• ConclusionsConclusions

Crystal Dicing-1Crystal Dicing-1

Samples are achieved by dicing a Silicon wafer:Samples are achieved by dicing a Silicon wafer:

Dicing at various speed and with different grain size of Dicing at various speed and with different grain size of the diamond powders results in samples with diverse the diamond powders results in samples with diverse featuresfeatures

0.250 mm

#2000#2000

#320#320

Crystal Dicing: examples of CUCrystal Dicing: examples of CU

0.250 mm

New lapping-polishing facilityNew lapping-polishing facility

Logitech lapping-Logitech lapping-polishing machine PM5polishing machine PM5

Logitech six-Logitech six-inch bonding inch bonding

stationstation

Lapping-polishing machine (LOGITECH) Lapping-polishing machine (LOGITECH) at Sensors and Semiconductor Laboratory at Sensors and Semiconductor Laboratory

Sample fabrication: the crystals stackSample fabrication: the crystals stack

Wafer dicing.....Wafer dicing.........assembling........assembling....

....mechanical treatment... ....mechanical treatment...

glass

crystal

Paper filter

Wax

The stack bonder

It has been found the correct process parameters: It has been found the correct process parameters:

Plate type, speed plate, jig load, abrasive and Plate type, speed plate, jig load, abrasive and process time.process time.

Sample fabrication: the modified jigSample fabrication: the modified jig

Right pre-process crystals stack. Left, the Right pre-process crystals stack. Left, the crystals stack after lapping and polishing crystals stack after lapping and polishing processprocess

The modified pp5 jigThe modified pp5 jig

Stack clamping of pp5 jigStack clamping of pp5 jig

Sample fabrication: the resultsSample fabrication: the results

Pre Process: as cutPre Process: as cut Lapping processLapping process Polishing processPolishing process

A photo of an 2-crystals stack. A photo of an 2-crystals stack. The sample has been treated The sample has been treated with lapping-polishing machinewith lapping-polishing machine

• Defects are induced by the dicing saw (a surface Defects are induced by the dicing saw (a surface layer estimated to be as thick as 30layer estimated to be as thick as 30m is rich in m is rich in stratches, dislocations, line defects and anomalies).stratches, dislocations, line defects and anomalies).

•Removal of such layer by Removal of such layer by wet planar etchingwet planar etching(HF,HNO(HF,HNO33,CH,CH33COOH).COOH).

•Planar etching removes crystalline planes one by onePlanar etching removes crystalline planes one by one

Planar etchingPlanar etching

0 10 20 30 4010

100

1000

b)

sample M

R a

(nm

)

etching time (min)

Chemical polishing enhances the standard Chemical polishing enhances the standard roughness (roughness (RRaa), which tends to decrease for ), which tends to decrease for

longer etching times (right down).longer etching times (right down).

Planar etching: the resultsPlanar etching: the results

Measurements at IHEP-2: Measurements at IHEP-2: Surface Surface treatment proved to be useful to improve treatment proved to be useful to improve the quality of extracted beam the quality of extracted beam (measurements at 70 GeV). (measurements at 70 GeV). Left :mechanically polished and right Left :mechanically polished and right chemically polishedchemically polished

SEM and AFM- SEM and AFM- measurementsmeasurementsSample 2M 200xSample 2M 200x Sample 0.5/30C 1000xSample 0.5/30C 1000x

Chemical etching appears to be not suitable to remove the Chemical etching appears to be not suitable to remove the surface damagesurface damage

AS-cutAS-cut

AS-cut

Chemical Chemical etchingetching

Chemical etching

Morphological characterizationMorphological characterization

Chemical polishing enhances standard roughness (Chemical polishing enhances standard roughness (RRaa) )

As dicedAs diced

ChemicalChemicaletchingetching

As dicedAs diced

Chemical etchingChemical etching

Structural characterizationStructural characterization

As dicedAs diced

Rough and highly Rough and highly defected surfacedefected surface

Chemical etchingChemical etching

Inhomogeneous Inhomogeneous surface BUT high surface BUT high crystalline degreecrystalline degree

RBS channeling resultsRBS channeling results

• Successful correlation between Successful correlation between surface crystalline perfection and surface crystalline perfection and post-dicing surface treatmentspost-dicing surface treatments

• Precise tailoring of sample Precise tailoring of sample preparation for crystal channelingpreparation for crystal channeling

(Baricordi (Baricordi et alet al. APL 2005).. APL 2005).

243

C750~

322 H 6 + HCl 6 + NSi NH 4 + HSiCl 3

A method to control of bending is obtained by a thin layer (or strips) of A method to control of bending is obtained by a thin layer (or strips) of high stress intrinsic coating Sihigh stress intrinsic coating Si33NN4.4.

Our goal was to identify the optimal parameters of SiOur goal was to identify the optimal parameters of Si33NN44 film deposition film deposition

via low-pressure chemical vapour deposition (LPCVD).via low-pressure chemical vapour deposition (LPCVD).

Samples with internal stress: Samples with internal stress: deposition of tensile thin filmsdeposition of tensile thin films

NH3/SiCl2H2 = 1:5

HIGH STRESS

Uniformity

To obtain a high residual To obtain a high residual stress the NHstress the NH33/DCS ratio /DCS ratio

must be higher than the must be higher than the unity, but...unity, but...

a good film thickness a good film thickness uniformity requires a uniformity requires a NHNH33/DCS ratio lower than /DCS ratio lower than

the unity.the unity.

A trade-off is neededA trade-off is needed

• Pressure: 300 mTorrPressure: 300 mTorr

• Temperature: 825°CTemperature: 825°C

• NHNH33/SiCl/SiCl22HH22: 0.2: 0.2

• Film thickness: 187 nmFilm thickness: 187 nm

• Residual stress = 400 MPaResidual stress = 400 MPa

Our LPCVD ParametersOur LPCVD Parameters

LPCVD reactor (LP-Thermtech) LPCVD reactor (LP-Thermtech) at Sensors and Semiconductor at Sensors and Semiconductor Laboratory Laboratory

• Silicon nitride provides Silicon nitride provides a tensile film with a tensile film with adjustable stessadjustable stess

• It does not alter crystal quality It does not alter crystal quality like with like with microindentationsmicroindentations

Deposition of SiDeposition of Si33NN44 layers layers

Si3N4

4” (111) oriented silicon wafer with thickness 4” (111) oriented silicon wafer with thickness h=200h=200m is startedm is started

200-nm-thick Si200-nm-thick Si33NN44 coating is deposited by coating is deposited by

LPCVD on both sides of the waferLPCVD on both sides of the wafer

SiOSiO22 masking layer is subsequently masking layer is subsequently

deposited onto the Sideposited onto the Si33NN44 by LPCVD by LPCVD

SiO2

Selective etching of SiOSelective etching of SiO22 on the bottom by HF on the bottom by HF

using the polymer as a selective maskusing the polymer as a selective mask

removal of the photoresist in acetone and removal removal of the photoresist in acetone and removal of the Siof the Si33NN44 in H in H33POPO44

removal of SiOremoval of SiO22 on the top by HF. The tensile on the top by HF. The tensile

residual stress in silicon nitride (Siresidual stress in silicon nitride (Si33NN44) film ) film

induce a bending to the Si substrateinduce a bending to the Si substrate

Deposition of a photoresist on the topDeposition of a photoresist on the top

Optical characterizationOptical characterization

Laser

lens

screen

wafer slide

h

d

Image of the wafer holder

From Stoney equation:From Stoney equation:

Values of radius and residual stressValues of radius and residual stress::

ff

ssf dR

dE

61

2

 

Axes

wafer thickness (m)

h (mm)

(mm)

d (mm)

Radius R (m)

Young modulus Es (GPa)

Poisson

Film thickness (nm)

Residual stress (GPa)

x 200 5455 141 94 7,27 130 0,276 200 0,82

y 200 5455 133 80 6,56 130 0,276 200 0,91

mean value

0,87

x 300 5450 52 72 15,09 180 0,276 200 1,24

y 300 5450 54 69 13,93 180 0,276 200 1,34

mean value

1,29

Screen printing machine SMTECH 100 MV at S&SLScreen printing machine SMTECH 100 MV at S&SL

A technique based on: first deposition of allumina paste (70%), a drying process A technique based on: first deposition of allumina paste (70%), a drying process then a firing (950°C) process. then a firing (950°C) process.

It is possible to deposit a thick layer of alumina film (larger than ten microns).It is possible to deposit a thick layer of alumina film (larger than ten microns).

Samples with internal stress: Samples with internal stress: deposition of tensile thick filmsdeposition of tensile thick films

Crystal bending through screen printing Crystal bending through screen printing technique: preliminary samplestechnique: preliminary samples

Screen printing technique: Screen printing technique: preliminary resultspreliminary results

D (mm) d (mm) Radius of curvature (m) Young modulus Es (GPa) Poisson Sub film thickness df (nm) Residual Stress (GPa)262 18 0,82 180 0,276 20000 0,10272 15 0,66 180 0,276 20000 0,13279 17 0,73 180 0,276 20000 0,11240 14 0,69 180 0,276 20000 0,12221 15 0,81 180 0,276 20000 0,10183 14 0,91 180 0,276 20000 0,09

mean residual stress(Gpa)0,109160445

Film thickness permits to obtain a radius Film thickness permits to obtain a radius

of curvature even smaller than 1 mof curvature even smaller than 1 m

Characterization of samples from other labsCharacterization of samples from other labs

Labs• IHEP (Russia)• PNPI (Russia)

Samples• O-shaped

• Simple thin rod

• Thick rod

Example of RBS-channelingExample of RBS-channeling analysisanalysis

• Different degree of crystalline perfection between SIDE A (nearly amorphous) and SIDE B

• SIDE B presents a highly defected surface with respect to perfect reference crystal

0 100 200 300100

1000

10000

<112> axial directions

SIDE A

SIDE B

Random reference Aligned referenceY

ield

Channel

SIDE A

SIDE B

Example of RBS-channeling analysisExample of RBS-channeling analysis

• Investigation on 2D spatial defect distribution: nearly perfect overlap of the spectra indicates homogeneous spatial distribution of defects

• The minimum yield is slightly higher than reference silicon, indicating low defects concentration and high crystalline order

100 200 300100

1000

10000

<111> axial directions

right border left border center

random Si aligned Si

Yie

ld

Channel

Novel crystals for channeling: zeolitesNovel crystals for channeling: zeolites

High acceptance for channeling in natural and artificial zeolites

Simulation of potential candidates and characterization of samples

What a zeolite is?What a zeolite is?

Zeolite was the name Zeolite was the name given by the svedish given by the svedish mineralogist mineralogist Cronstedt in 1756 to Cronstedt in 1756 to identify a class of identify a class of natural minerals. natural minerals. Under heating, Under heating, desorption was so desorption was so strong as it appeared strong as it appeared as it were boiling as it were boiling ((zein zein = to boil, = to boil, lithoslithos = rock).= rock).

Zeolite is…Zeolite is…

Smith (1963): aluminosilicate with open three-Smith (1963): aluminosilicate with open three-dimensional tetraedric framework, containg dimensional tetraedric framework, containg cavities partly occupied by ions and water cavities partly occupied by ions and water moleculesmolecules

More technically speaking…More technically speaking…

The primary building unit is a The primary building unit is a coordination tetraedron coordination tetraedron

• Selection of candidates with rectilinear channels, availability in nature or in commerce as relatively wide crystals

• Simulation of efficiency for channeling with existing codes

• Tests for channeling with MeV protons

Zeolites for channeling?Zeolites for channeling?

Zeolites DicingZeolites Dicing

First samples are achieved by dicing a zeolite:First samples are achieved by dicing a zeolite:

The sample has been diced with a 30 The sample has been diced with a 30 microns high-performance NBC-Z microns high-performance NBC-Z blade. The speed was 2 mm/sblade. The speed was 2 mm/s

0.250 mm

2 mm2 mm

Zeolites: first sample Zeolites: first sample

SEM image of a zeolite sample treated: Left just cut from a rock, right SEM image of a zeolite sample treated: Left just cut from a rock, right after cutting process. In the microscope image shown below, particular after cutting process. In the microscope image shown below, particular of the sample after cutof the sample after cut

1 mm

Pre- processPre- process

After dicingAfter dicing

200 micron200 micron

500 micron500 micron

New proposal: Multilayered crystal mirrorNew proposal: Multilayered crystal mirror

Designed by Institute for High Energy Physics, Protvino, Russia

Multilayered crystal mirrorMultilayered crystal mirror

1.5 mm

1.5 mm

A photo of 8-fingers multilayered crystal A photo of 8-fingers multilayered crystal mirror.mirror.

Cross section of the sample

A microscope image of 2 fingers. The gap

between fingers is about 30 microns

ConclusionsConclusions

• Fabrication of silicon samplesFabrication of silicon samples• Morphological, structural and optical Morphological, structural and optical

characterizations characterizations • Search for novel materialsSearch for novel materials• First zeolite prototipe realizedFirst zeolite prototipe realized• Multilayered crystal mirrorMultilayered crystal mirror