Download Detailed RCAT flow - MonolithIC 3D Inc.

MonolithIC 3D ICs
RCAT Flow
MonolithIC 3D Inc. , Patents Pending
MonolithIC 3D Inc. , Patents Pending
1
Monolithic 3D ICs
Using SmartCut technology - the ion cutting process that
Soitec uses to make SOI wafers for AMD and IBM (million of
wafers had utilized the process over the last 20 years) - to stack
up consecutive layers of active silicon (bond first and then cut).
Soitec’s Smart Cut Patented* Flow (access the link for video).
*Soitec’s fundamental patent US 5,374,564 expired Sep. 15, 2012
MonolithIC 3D Inc. , Patents Pending
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Monolithic 3D ICs
Ion cutting: the key idea is that if you implant a thin layer
of H+ ions into a single crystal of silicon, the ions will weaken the
bonds between the neighboring silicon atoms, creating a fracture
plane (Figure 3). Judicious force will then precisely break the
wafer at the plane of the H+ implant, allowing you to in effect
peel off very thin layer. This technique is currently being used to
produce the most advanced transistors (Fully Depleted SOI,
UTBB transistors – Ultra Thin Body and BOX), forming
monocrystalline silicon layers that are less than 10nm thick.
MonolithIC 3D Inc. , Patents Pending
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Figure 3
Using ion-cutting to place a thin layer of monocrystalline silicon
above a processed (transistors and metallization) base wafer
Cleave using <400oC
Hydrogen implant
Oxide
anneal or sideways
Flip top layer and
of top layer
mechanical force. CMP.
bond to bottom layer
p- Si
Top layer
Oxide
p- Si
Oxide
H
p- Si
H
Oxide
Oxide
p- Si
Oxide
Oxide
Bottom layer
Similar process (bulk-to-bulk) used for manufacturing all SOI wafers today
MonolithIC 3D Inc. , Patents Pending
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MonolithIC 3D – The RCAT path
The Recessed Channel Array Transistor (RCAT) fits very
nicely into the hot-cold process flow partition
RCAT is the transistor used in commercial DRAM as its 3D
channel overcomes the short channel effect
Used in DRAM production @ 90nm, 60nm, 50nm nodes
Higher capacitance, but less leakage, same drive current
The following slides present the flow to process an RCAT
without exceeding the 400ºC temperature limit
MonolithIC 3D Inc. , Patents Pending
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RCAT – a monolithic process flow
Using a new wafer, construct dopant regions in top ~100nm
and activate at ~1000º C
Oxide
~100nm
Wafer, ~700µm
PN+
P-
MonolithIC 3D Inc. , Patents Pending
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Implant Hydrogen for Ion-Cut
H+
Oxide
P~100nm
N+
Wafer, ~700µm
P-
MonolithIC 3D Inc. Patents Pending
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Hydrogen cleave plane
for Ion-Cut formed in donor wafer
Oxide
P~100nm
N+
Wafer, ~700µm
H+
~10nm
P-
MonolithIC 3D Inc. Patents Pending
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Flip over and bond
the donor wafer to the base (acceptor) wafer
Donor Wafer,
~700µm
N+
POxide
H+
~100nm
1µ Top Portion of
Base Wafer
Base Wafer,
~700µm
MonolithIC 3D Inc. Patents Pending
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Perform Ion-Cut Cleave
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Complete Ion-Cut
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Etch Isolation regions as the first step to define
RCAT transistors
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Fill isolation regions (STI-Shallow Trench
Isolation) with Oxide, and CMP
~100nm
N+
P-
Oxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Etch RCAT Gate Regions
Gate region
~100nm
N+
P-
Oxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Form Gate Oxide
~100nm
N+
P-
Oxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Form Gate Electrode
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Add Dielectric and CMP
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Etch Thru-Layer-Via and
RCAT Transistor Contacts
~100nm
N+
POxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Fill in Copper
~100nm
N+
P-
Oxide
1µ Top Portion of
Base Wafer
MonolithIC 3D Inc. Patents Pending
Base Wafer
~700µm
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Add more layers monolithically
~100nm
~100nm
N+
P-
Oxide
N+
P-
Oxide
1µ Top Portion of
Base (acceptor) Wafer
Base Wafer
~700µm
MonolithIC 3D Inc. Patents Pending
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