The document discusses the manufacturing and process control challenges of 3D integrated circuit structures. It describes how 3D architectures are being implemented in vertical NAND flash memory and FinFET transistors. The key challenges for 3D manufacturing include precise control of thin film deposition, etch profiles, and detection of defects embedded deep within complex multi-layer stacks. Semiconductor metrology and inspection tools will need to advance to allow 3D imaging and measurement of features located in the third dimension.

1. The Shift to 3D IC Structures -
Manufacturing and
Process Control Challenges
Ehud Tzuri
Chief Marketing Officer
ChipEx-2012, May 2012
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2. 300mmNOR  NAND PVD  Metal CVD
Single-wafer E-beam New materials:
III-V, Ge
inspection
MORE Processing CVD: hidden films
INFLECTIONS DRAM 8F2  6F2 Atomic precision CMP Deposited
resist
IN
NEXT Bumping Flowable films Advanced
5 YEARS THAN
Wafer-level interconnect
packaging Dry chemical
Advanced patterning
cleans
350nm 250nm 180nm 130nm 90nm 65nm 45nm 32nm 22nm 14nm 10nm
Double Patterning LAST
Deep-UV Laser
Lithography Epi
Cu damascene
15 YEARS
High aspect ratio Etch
Laser-based
processing
Patterning Films Low-k dielectric 450mm
Lamp-based Interface 3D
Hi-K ALD Processing CMP
Sacrificial
films management NAND
DPN SiON gate Advanced Universal ALD
Reflow  HPD transistor
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3. Moore’s Law
The number of transistors on integrated circuits doubles every two years
“In 1965, Gordon Moore sketched out his prediction
of the pace of silicon technology. Decades later,
Moore’s Law remains true, driven largely by Intel’s
unparalleled silicon expertise.”
(Source: Intel; Copyright © 2005 Intel Corporation)
How to maintain cost-performance ?
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4. Complying with Moore’s Law
Maintaining Cost-Performance
 Shrink the feature size: ArF  Immersion  EUV
 Increase wafer size: 200mm  300mm  450mm
 Build vertically: 2D  3D
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5. Where is 3D Architecture Implemented?
3D
Wafer level
Memory Transistor
packaging
V-NAND FinFET TSV
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6. Where is 3D Architecture Implemented?
3D
Wafer level
Memory Transistor
packaging
V-NAND FinFET TSV
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7. Flash Roadmap*
* The future is coming sooner than we thought
Source: J.Choi, Samsung, The 2nd International Memory Workshop, May.16, 2010
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8. From 2D to 3D Flash NAND
Sourceline
Wordlines
Select gate
 A folded, vertically stacked NAND string
 Cells are generated inside a high-aspect-ratio (HAR) contact hole
 Benefits:
– Memory density is less dependent on patterning
– Reduced coupling between memory cells
– Cost scalability
Image Sources:
Left:IMFT 25-nm MLC NAND: technology scaling barriers broken, DONG YI Technology Group, Published Date:2010-3-23
Right: Pipe-shaped BiCS Flash Memory with 16 Stacked Layers…/Ryota Katsumata - 2009 Symposium on VLSI Technology
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9. 3D NAND Process Challenges
TEM Image of 69-Layer Oxide/Nitride Stack
 Surface / interface roughness
Top
 Film stress control for low wafer bow
 Fastest cycle time
Bottom
 Excellent stacked particle
performance
 Etch profile - ability to open HAR SEM X-section of double etched stack
stacks
Complex multi-stack requires
precise process monitoring –
thickness, RI, etch profile and defects Source:
Pipe-shaped BiCS Flash Memory with 16 Stacked Layers…/Ryota
Katsumata - 2009 Symposium on VLSI Technology
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10. 3D NAND Metrology & Inspection Challenges
Imaging of HAR
contact hole
Slit & plate etch
along its depth
inspection &
imaging
Charge Trap Embedded defects:
material thickness Deep in the stack
& uniformity along
contact depth
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11. Where is 3D Architecture Implemented?
3D
Wafer level
Memory Transistor
packaging
V-NAND FinFET TSV
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12. Planar vs. Trigate (FinFET) Transistor
 Benefits
– Gate surrounds Si from 3 directions, thus,
increasing control of over channel 
reduced leakage
– Can operate at lower voltage with good
performance, reducing active power by
>50%
Source: Intel 22nm Trigate announcement , 4/19/2011
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13. FinFet – Process Challenges
Spacer Gate Stack (high-k & metal gate)
• Complete spacer removal from fin area • Material selectivity
• Material deposition thickness
uniformity on vertical walls
• Metal gate composition uniformity/stability
Fin
Fin Formation:
• Precision etch
STI
• Structural integrity (collapse, Oxide
erosion, thermal shock)
• Precise Recess to control fin Fin Junctions:
height • Conformal doping
• Channel materials to increase on sidewalls
mobility
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14. FinFET – Process Control Challenges
Lg
Measurement of
Lg gate CD across the
Fin height
Lg
Detection & Review of
defects on Fin sidewalls after
gate etch
Measurement of Fin
sidewall angle to
control the 3D
transistor width
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15. Transistor Roadmap: Applied Materials View
Planar CMOS FinFET III-V FinFET
New Fin
Gate Material
Fin
STI STI
Oxide
Oxide
No end in sight for Moore’s Law – for the next decade
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16. Where is 3D Architecture Implemented?
3D
Wafer level
Memory Transistor
packaging
V-NAND FinFET TSV
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17. 3D Integration & TSV
 TSV is a process in which wafers are: thinned, stacked & interconnected
 All flows include creation of deep holes and filling them with Cu
interconnect
Source: DAC, 2½D Integrated Circuits, Wednesday, January 26, 2011 , Paul McLellan / Source: “Through-Silicon Via (TSV)””, Vol. 97, 0018-9219/$25.00 2009
IEEE No. 1, January 2009 | Proceedings of the IEEE
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18. TSV – Process Control Challenges
Ta/TaN/Au CVD-SiO2 Wafer inspection for surface
defects on TSV sidewalls and
bottom
Si substrate
Interlayer
Passivation layer
Bonding pad
Adhesive
Handle wafer
HAR SEM-based defect review for
sidewall and bottom defects;
including over-etch
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19. Common Challenges
 Defects of importance are located in the 3rd dimension;
they need to be found & imaged
 Measurements of the 3rd dimension (HAR, SWA) need to
be performed
 Current state of the art M&I tools have limitations to do so
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20. Possible Solutions
SEM-based imaging
Optical metrology
X-ray
Destructive technologies
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21. Possible Solutions – The Leading Candidate
SEM-based imaging
3D imaging E-beam inspection
techniques with SEM (Voltage Contrast)
(Resolution)
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22. Summary
 The future is here… 3D transistors and TSV are already a
reality, VNAND is just around the corner
 3D Key challenges are related (mainly) to process
integration and process control
 Traditional process control solutions might not be sufficient
 E-Beam based techniques have the potential to become the
process control enablers
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23. Thank You
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