Post on 26-Mar-2015
Innovative Chemical Solutionsfor MEMS and Microelectronics
Electrodeposited Photoresists for Wafer Applications
© 2011 MicroChem Corp
Nature of ED ResistsNature of ED Resists
• ED stands for electrodeposited
• ED paint used by Ford since 1960
• Emulsion of photoresist “Micelles” in water
-- 50 – 150 microns50 – 150 microns
-- Micelles contain the Micelles contain the resist componentsresist components
-- Micelles have a Micelles have a + or - charge + or - charge
Photoresist MicellePhotoresist Micelle
PolymerPolymer
Photo Active CompoundPhoto Active Compound
Solvents DyeSolvents Dye
© 2011 MicroChem Corp
Conformation on 3-D StructuresConformation on 3-D Structures
Deposits on all conductive surfaces
Intervia 3D-P over thick plated copper
© 2011 MicroChem Corp
Dow Electronic Materials ED ResistsDow Electronic Materials ED Resists
Intervia 3D-N•Negative tone image / cathodic wafer
(wafer has negative charge)
Intervia 3D-P•Positive-tone image / anodic wafer (wafer has positive charge)
© 2011 MicroChem Corp
Intervia 3D-N Coating ProcessIntervia 3D-N Coating ProcessC
ondu
ctiv
e W
afer
(C
atho
de)
Inert Anode
NR3+ -
NR3+
NR3+
NR3+
NR3+
NR3+
H2O
H2 O2
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
RCO2-
RCO2-
RCO2-
RCO2-
RCO2-
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
RCO2-
Micelles migrate to cathodic substrate
© 2011 MicroChem Corp
Self Limiting BehaviorSelf Limiting Behavior
resist
© 2011 MicroChem Corp
Deposition Current ProfileDeposition Current Profile
30s
Self Limiting Behavior
Near Zero Current
Deposition Current vs. Time
Time
Dep
ositi
on C
urre
nt
© 2011 MicroChem Corp
Intervia 3D-P Application Process Intervia 3D-P Application Process
• Resist Coating - Coating Cycle
. 100 - 300 V DC
. 10 ASF peak
. Potential applied for 10 - 20 seconds- Thickness Control
. Temperature
. Solvent
• Exposure 365 - 405 nm
© 2011 MicroChem Corp
Thickness vs. TemperatureThickness vs. Temperature
Thickness vs. Temperature
Temperature (ºC)
Thi
ckne
ss (
mic
rons
)
© 2011 MicroChem Corp
Deposit UniformityDeposit Uniformity
Thickness Uniformity
4
5
6
7
8
9
10
Edge
Cente
r
Edge
Position
Th
ick
ne
ss
(m
icro
ns
)
Thickness Uniformity
Position
Thi
ckne
ss (
mic
rons
)
© 2011 MicroChem Corp
ED Resist ComparisonED Resist Comparison
• Intervia 3D-NIntervia 3D-N– Negative working – 6 – 100 µm final thickness– 200-300 mJ/cm2 @365nm – Organic acid develop / strip– Acid and alkaline etches– Resistant to many plating
chemistries
© 2011 MicroChem Corp
ED Resist ComparisonED Resist Comparison
• Intervia 3D-N– Negative working – 6 - 100 µm final thickness– 200-300 mJ/cm2 @365nm – Organic acid develop / strip– Acid and alkaline etches– Resistant to many plating
chemistries
• Intervia 3D-P– Positive working– 6 µm target final
thickness– 250-400 mJ/cm2
@405nm– -CO3,
-OH or TMAH develop
– Plating and acid etching– Hydroxide or organic
solvents
© 2011 MicroChem Corp
ToolsTools
Semitool ED Cell
ED Resist Coater for R&D and Low Volume Production
© 2011 MicroChem Corp
Problems with Spin-on ResistsProblems with Spin-on Resists
100µm feature spin coated with 6.0 µm of photoresist.
•Little or no coverage on outside corners
•Very thick coverage in inside corners and at bottom of the feature
Image of 25µm lines patterned over the top of 45µm wide features
© 2011 MicroChem Corp
Coated Wafer StructuresCoated Wafer Structures
Source: Semitool
SEM image of 6µm of electrophoretic photoresist deposited over a series of 92µm tall features.
SEM image showing 5µm of electrophoretic photoresist deposited over a 300µm deep trench.
© 2011 MicroChem Corp 16
Examples of Wafer Processes Using Intervia ED Resists
© 2011 MicroChem Corp
source: Meco
Basic 3-D Test StructuresBasic 3-D Test Structures
Sketch of proposed technology for wafer-through hole interconnects
Set of 10, 20, 30 & 40 µm wide test slits reproduced at 150µm deep cavity
SEM Source: Meco
© 2011 MicroChem Corp
Ni Plated Structures on PolyimideNi Plated Structures on Polyimide
Source: Dow Electronic Materials
SEM photomicrographics of conformally electroplated Ni lines across polyimide grooves using Intervia 3D-P electrodeposition
© 2011 MicroChem Corp
Dow ED Products
•Negative ED photoresist
•Developer
•Remover
ShellCase ProcessShellCase Process
ShellOP for Image Sensors and Light Detection Devices
© 2011 MicroChem Corp
Etching Conductive Vias with ED ResistsEtching Conductive Vias with ED Resists
a) Photolithography on thick resist
b) Through-wafer etching (HDLP RIE)
c) Thermal oxidation and polysilicon deposition (LPCVD)
d) CVD metallization (W or Cu) and electro-plating (Cu only)
e) Electrodeposited resist deposition
f) Resist patterning by photo lithography
g) Metal and polysilicon etching
h) Photoresist removal
Source: Quate Group, Stanford University
a)
b)
c)
d)
e)
f)
g)
h)
© 2011 MicroChem Corp
Backside ContactsBackside Contacts
Source: Lindedre, Baltes, Gnaednger
SEM micrograph of final through-wafer vias
© 2011 MicroChem Corp
Backside ContactsBackside Contacts
Source: Lindedre, Baltes, Gnaednger
through-hole sidewall
SEM micrograph showing metallization on {111} sidewalls for elimination of uncontrolled light reflections.
© 2011 MicroChem Corp
Philips Thru Via ImagingPhilips Thru Via Imaging
© 2011 MicroChem Corp
Philips Thru Via ImagingPhilips Thru Via Imaging
Quadruple leads in a single through-wafer hole and a toroid structure
© 2011 MicroChem Corp
Exposure Using Phase Gratings Exposure Using Phase Gratings
Schematic view of 3-D exposure using phase gratings
Source: Philips
UV light
photomask
side viewsubstrate
phase grating
crosssection
top view
© 2011 MicroChem Corp
Plated CoilsPlated Coils
© 2011 MicroChem Corp
Infineon ELASTecInfineon ELASTec®® Wafer Level Bumping Wafer Level Bumping
Finished Bump
Intervia 3D-P Resist
© 2011 MicroChem Corp
ELASTecELASTec®® Process Steps Process Steps
3
• Resist Strip• Seedlayer Etch
2
• Reroute Plating (Cu, Ni, Au)
1
• Bump Print & Cure• Seedlayer Sputter (Ti/Cu)
© 2011 MicroChem Corp
ElasticElastic®®
© 2011 MicroChem Corp
Silicon Optical BenchSilicon Optical Bench
Source: Banerjee, Drayton
2-D Diagram of SiOB-I. Number 1, 2 & 3 indicate the regions where cross sections are taken for the fabrication diagrams.
Design II Interconnect: Partially shielded microstrip. (All dimensions are in microns)
2. Vias
© 2011 MicroChem Corp
Impact of Resist Tone on Printed DefectsImpact of Resist Tone on Printed Defects
© 2011 MicroChem Corp 32
Intervia 3D-N Typical Application Process
© 2011 MicroChem Corp
• Chemical Clean – Preposit Cleaner 742
• Sulfuric acid based soak cleaner• Removes fingerprints & soils• 50 - 55 degrees C• 2 - 3 minutes
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
• Chemical Clean – Preposit Etch 748
• Monopersulfate etchant• Micro roughens copper (0.5 - 1.0 µm)• 30°C • 2 - 3 minutes
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
• Resist Coating – Resist is sparged upon entry to fully wet the part– Vibration of parts may be used in some applications to
release air bubbles– Part to be coated is the cathode – Stainless steel anodes
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
Con
duct
ive
Waf
er (
Cat
hode
)Inert A
node
NR3+ -
NR3+
NR3+
NR3+
NR3+
NR3+
H2O
H2 O2
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
RCO2-
RCO2-
RCO2-
RCO2-
RCO2-
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
NR3+
RCO2-
Intervia 3D-N Coating CycleIntervia 3D-N Coating Cycle
© 2011 MicroChem Corp
Intervia 3D-N Coating CellIntervia 3D-N Coating Cell
SS Anode
Part to be Coated
Spargers
Vibrator
© 2011 MicroChem Corp
Intervia 3D-N Application Process Intervia 3D-N Application Process
• Resist Coating – Coating Cycle
• 100 - 300 V DC• 10 ASF peak• Potential applied for 10 - 20 seconds
– Thickness Control• Temperature• Coating Time• Voltage
© 2011 MicroChem Corp
Typical Tmin Curve for Intervia 3D-NTypical Tmin Curve for Intervia 3D-N
© 2011 MicroChem Corp
Intervia 3D-N Application Process Intervia 3D-N Application Process
• Conservation Rinse – Reclaims resist drag-out– Conservation resist is ultrafiltered to reclaim solids
• D.I. Final Rinse
© 2011 MicroChem Corp
Intervia 3D-N TopcoatIntervia 3D-N Topcoat
• Contains cellulose-based material in water– Reduces tack of coating– Reduces edge recession– Dissolves quickly during development step
© 2011 MicroChem Corp
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
• Air knives– Remove bulk moisture– Promotes uniform drying
• Convection Dry– 105°C– 10 minutes
© 2011 MicroChem Corp
• Exposure– 300 mJ/cm2 required at 5 micron resist thickness– 365 nm peak– Intensity affects required dose
• Subject to Low Intensity Reciprocity Law Failure (LIRLF)• 10 mW/cm2 minimum recommended
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
• Development– Intervia 3D-N Developer– 38 - 42°C– Clear time 30 - 120 seconds– 50% breakpoint
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
Intervia 3D-N Application Process Intervia 3D-N Application Process
• Plating– Cupronal BP (copper)– Auronal BP (gold)– Solderon BP ( tin lead, lead free, low alpha lead)– Nikal BP (nickel)
• Etching – Cupric Chloride – Ferric Chloride
© 2011 MicroChem Corp
• Stripping– Intervia 3D-N Remover
– 50 - 65°C
Intervia 3D-N Application ProcessIntervia 3D-N Application Process
© 2011 MicroChem Corp
Microfabrication CapabilitiesMicrofabrication Capabilities
• Etched features with 0.2 um tolerances
• Deep (through-wafer) etching
• Contoured plated features (photoresists and metals)
• Submicron multilayer feature-to-feature alignment
• Submicron die bonding
• Conformal AR coatings
© 2011 MicroChem Corp 48
MicroChem would like to thank Dow Electronic Materials for providing these materials…
…and thank you for your time and attention.