`Process Analysis
`
`3-32
`
`Figure 3.3.9 shows a TEM view of a metal 3 line. The liner is about 7 nm thick
`along the trench sidewalls and trench bottom. The timed metal trench etch has
`produced a notched profile along the trench bottoms.
`
`Figure 3.3.9Metal 3 Liner – TEM
`Figure 3.3.9 Metal 3 Liner – TEM
`
`SiCNO
`
`M3 Cu
`
`~7 nm
`
`SiOC
`
`Ta-based liner
`
`8 nm
`
`~7 nm
`
`notch
`
`Figure 3.3.9 Metal 3 Liner – TEM
`
`Page 66 of 161
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`Process Analysis
`
`3-33
`
`Figure 3.3.10 shows the 0.14 µm minimum pitch metal 2 and metal 4 lines. The
`metal 4 lines are slightly thinner than the underlying metal 1 through metal 3 lines.
`
`Figure 3.3.10Minimum Pitch Metal 2 and 4
`Figure 3.3.10 Minimum Pitch Metal 2 and 4
`
`SiCNO
`
`SiOC
`
`0.14 µm
`
`M4
`Cu
`
`0.11 µm
`
`Ta-based liner
`
`0.14 µm
`
`M2
`Cu
`
`0.13 µm
`
`SiCNO
`
`SiOC
`
`Ta-based liner
`
`Figure 3.3.10 Minimum Pitch Metal 2 and 4
`
`Page 67 of 161
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`Process Analysis
`
`3-34
`
`Figure 3.3.11 shows a TEM view of a pair of metal 2 lines. The Ta-based liner is
`about 8 nm thick along the trench sidewalls and trench bottom. The metal trench
`etch has also produce a notched profile on the bottom of these lines.
`
`Figure 3.3.11Metal 2 Liner – TEM
`Figure 3.3.11 Metal 2 Liner – TEM
`
`SiCNO
`
`SiOC
`
`~8 nm
`
`M2 Cu
`
`Ta-based liner
`
`~8 nm
`
`notch
`
`Figure 3.3.11 Metal 2 Liner – TEM
`
`Page 68 of 161
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`Process Analysis
`
`3-35
`
`Figure 3.3.12 shows a series of 0.14 µm minimum pitch metal 1 lines. Metal 1
`uses the PMD 5 SiOC as the line dielectric, and is capped with SiCNO after the
`CMP polish. A timed etch was used for the dielectric trench etch ending in the
`oxide PMD 4.
`
`The Ta-based liners are very thin, and it is not entirely clear as to how effective a
`barrier they will be to Cu diffusion, so the long term reliability of the device may be
`in question. The liner thickness on this part is, however, consistent with the liner
`metal 1 liner thickness used on Intel’s 45 nm process.
`
`Figure 3.3.12Minimum Pitch Metal 1
`Figure 3.3.12 Minimum Pitch Metal 1
`
`SiCNO
`
`SiOC
`
`oxide
`
`0.13 µm
`
`0.14 µm
`
`M1
`Cu
`
`PMD 3 - oxide
`
`Ta-based liner
`
`Figure 3.3.12 Minimum Pitch Metal 1
`
`Page 69 of 161
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`Process Analysis
`
`3-36
`
`Figure 3.3.13 shows a TEM image of a pair of metal 1 lines. The Ta-based liner
`ranges from about 2 nm thick along the sidewalls to about 10 nm thick along the
`trench bottom.
`
`Figure 3.3.13Metal 1 Liner
`Figure 3.3.13 Metal 1 Liner
`
`SiCNO
`
`~2 nm
`
`M1 Cu
`
`SiOC
`
`Ta-based liner
`
`~10 nm
`
`Figure 3.3.13 Metal 1 Liner
`
`Page 70 of 161
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`Process Analysis
`
`3-37
`
`Figure 3.3.14 shows the TEM-EDS spectrum of the metal 9 Al body.
`
`Figure 3.3.14TEM-EDS Spectrum of Metal 9 Body
`Figure 3.3.14 TEM-EDS Spectrum of Metal 9 Body
`
`Al
`
`Metal 9 - Al
`
`1200
`
`1000
`
`800
`
`600
`
`400
`
`200
`
`Counts
`
`0
`
`0
`
`1
`
`3
`2
`Energy (keV)
`
`4
`
`5
`
`Figure 3.3.14 TEM-EDS Spectrum of Metal 9 Body
`
`Page 71 of 161
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`Process Analysis
`
`3-38
`
`Figure 3.3.15 shows the TEM-EDS spectra of the metal 9 TiN/Ti barrier metals.
`
`Figure 3.3.15TEM-EDS Spectra of Metal 9 Barrier Layers
`Figure 3.3.15 TEM-EDS Spectra of Metal 9 Barrier Layers
`
`M9 barrier (top) - TiN
`
`M9 barrier (bottom) - Ti
`
`Ti
`
`Ti
`
`5
`
`6
`
`N
`Ti
`
`Al
`
`1200
`
`1000
`
`800
`
`600
`
`400
`
`200
`
`Counts
`
`0
`
`0
`
`1
`
`2
`
`3
`Energy (keV)
`
`4
`
`Figure 3.3.15 TEM-EDS Spectra of Metal 9 Barrier Layers
`
`Page 72 of 161
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`Process Analysis
`
`3-39
`
`Figure 3.3.16 shows the TEM-EDS spectra of the metal 1 Ta-based liner, likely
`TaN. This spectrum is representative of the metal 1 through metal 8 liners.
`
`Figure 3.3.16TEM-EDS Spectrum of Metal 1 Barrier
`Figure 3.3.16 TEM-EDS Spectrum of Metal 1 Barrier
`
`M1 liner - Ta based
`
`Ta
`Cu
`
`Cu
`Ta
`
`Cu
`
`C
`
`O
`
`Ta
`
`1200
`
`1000
`
`800
`
`600
`
`400
`
`200
`
`Counts
`
`0
`
`0
`
`2
`
`4
`
`8
`6
`Energy (keV)
`
`10
`
`12
`
`Figure 3.3.16 TEM-EDS Spectrum of Metal 1 Barrier
`
`Page 73 of 161
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`Process Analysis
`
`3-40
`
`3.4 Vias and Contacts
`The XXXX uses conventional Al vias to interconnect metal 8 and 9. Cu vias are
`used for the via 1s through via 7s, using a via first process as part of the dual
`damascene Cu line formation. The contacts to poly and diffusion are comprised of
`TiN lined, W filled contact studs. Butted contacts are used in the 6T SRAM to
`reduce the unit cell size. Plan view images of these are presented in Section X.
`
`Table 3.4.1 lists the minimum width and pitch of the vias and contacts. These
`values were derived from measurements made at the via/contact interface with
`the underlying metal or diffusion.
`
`Table 3.4.1
`
`Via and Contact Horizontal Dimensions
`
`Layer
`Via 8
`Via 7
`Via 6
`Via 5
`Via 4
`Via 3
`Via 2
`Via 1
`Contacts
`
`Width (µm)
`6.0
`0.54
`0.51
`0.16
`0.08
`0.08
`0.08
`0.08
`0.07
`
`3.4.1 Via and Contact Horizontal Dimensions
`
`Space (µm)
`6.8
`1.29
`1.23
`0.18
`0.09
`0.07
`0.06
`0.06
`0.07
`
`Pitch (µm)
`12.8
`1.83
`1.74
`0.34
`0.17
`0.15
`0.14
`0.14
`0.14
`
`Table 3.4.1 Via and Contact Horizontal Dimensions
`
`Page 74 of 161
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`Process Analysis
`
`3-41
`
`Figure 3.4.1 shows the 6.0 µm wide, 12.8 µm minimum pitch via 8s.
`
`Figure 3.4.1Minimum Pitch Via 8s
`Figure 3.4.1 Minimum Pitch Via 8s
`
`M9 Al
`
`via 8
`
`6.2 µm
`
`12.8 µm
`
`M8 Cu
`
`Figure 3.4.1 Minimum Pitch Via 8s
`
`Page 75 of 161
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`Process Analysis
`
`3-42
`
`Figure 3.4.2 shows the 0.54 µm wide, 1.83 µm minimum pitch via 7s. While these
`are the minimum observed pitch, the lithography is capable of quite finer pitches,
`as small as perhaps 1 µm.
`
`Figure 3.4.2Minimum Pitch Via 7s
`Figure 3.4.2 Minimum Pitch Via 7s
`
`M8 Cu
`
`crown fence
`
`1.83 µm
`
`0.54 µm
`
`via 7
`
`M7 Cu
`
`Figure 3.4.2 Minimum Pitch Via 7s
`
`Page 76 of 161
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`Process Analysis
`
`3-43
`
`Figure 3.4.3 shows the 0.51 µm wide, 1.74 µm minimum pitch via 6s. Like the
`via 7s, the via 6 lithography is likely capable of finer pitches.
`
`Figure 3.4.3Minimum Pitch Via 6s
`Figure 3.4.3 Minimum Pitch Via 6s
`
`M7 Cu
`
`via 6
`
`1.74 µm
`
`0.51 µm
`
`M6 Cu
`
`Figure 3.4.3 Minimum Pitch Via 6s
`
`Page 77 of 161
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`Process Analysis
`
`3-44
`
`Figure 3.4.4 shows the 0.16 µm wide, 0.34 µm minimum pitch via 5s.
`
`Figure 3.4.4Minimum Pitch Via 5s
`Figure 3.4.4 Minimum Pitch Via 5s
`
`via 6
`
`M6 Cu
`
`0.34 µm
`
`0.16 µm
`
`M5 Cu
`
`via 5
`
`Figure 3.4.4 Minimum Pitch Via 5s
`
`Page 78 of 161
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`
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`Process Analysis
`
`3-45
`
`Figure 3.4.5 shows a TEM image of a single via 5. The via 5 etch has just
`penetrated the surface of the metal 5 line.
`
`Figure 3.4.5Via 5 – TEM
`Figure 3.4.5 Via 5 – TEM
`
`M6 Cu
`
`Ta-based liner
`
`via 5
`
`0.15 µm
`
`M5 Cu
`
`Figure 3.4.5 Via 5 – TEM
`
`Page 79 of 161
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`
`Structural Analysis – Sample Report
`Process Analysis
`
`3-46
`
`Figure 3.4.6 shows the 0.15 µm minimum pitch via 3s and 0.17 µm minimum pitch
`via 4s.
`
`Figure 3.4.6Minimum Pitch Via 3s and 4s
`Figure 3.4.6 Minimum Pitch Via 3s and 4s
`
`M6 Cu
`
`M5 Cu
`
`0.17 µm
`
`via 4
`
`M4 Cu
`
`via 3
`
`0.15 µm
`
`M3 Cu
`
`Figure 3.4.6 Minimum Pitch Via 3s and 4s
`
`Page 80 of 161
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`
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`Process Analysis
`
`3-47
`
`Figure 3.4.7 shows a TEM image of a single via 4. The via 4 etch has penetrated
`about 25 nm into the surface of metal 4.
`
`Figure 3.4.7Via 4 – TEM
`Figure 3.4.7 Via 4 – TEM
`
`M5 Cu
`
`via 4
`
`Ta-based liner
`
`~25 nm
`
`M4 Cu
`
`Figure 3.4.7 Via 4 – TEM
`
`Page 81 of 161
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`
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`Process Analysis
`
`3-48
`
`Figure 3.4.8 shows the 0.14 µm minimum pitch via 1s and 2s.
`
`Figure 3.4.8Minimum Pitch Via 1s and 2s
`Figure 3.4.8 Minimum Pitch Via 1s and 2s
`
`M3 Cu
`
`via 2
`
`0.14 µm
`
`M2 Cu
`
`via 1
`
`0.14 µm
`
`M1 Cu
`
`Figure 3.4.8 Minimum Pitch Via 1s and 2s
`
`Page 82 of 161
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`
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`Process Analysis
`
`3-49
`
`Figure 3.4.9 shows a TEM image of a pair of via 2s. The via 2 etch has penetrated
`about 25 nm into the surface of metal 2.
`
`Figure 3.4.9Via 2s – TEM
`Figure 3.4.9 Via 2s – TEM
`
`M3 Cu
`
`via 2
`
`M2 Cu
`
`Ta-based liner
`
`~25 nm
`
`Figure 3.4.9 Via 2s – TEM
`
`Page 83 of 161
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`
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`Process Analysis
`
`3-50
`
`Figure 3.4.10 shows the 0.07 µm wide, 0.14 µm minimum pitch contacts. NiSi is
`used on the source drain diffusions.
`
`Figure 3.4.10Minimum Pitch Contacts – TEM
`Figure 3.4.10 Minimum Pitch Contacts – TEM
`
`0.14 µm
`
`W
`contact
`
`NiSi
`
`0.07 µm
`
`poly
`
`STI
`
`0.14 µm
`
`Figure 3.4.10 Minimum Pitch Contacts – TEM
`
`Page 84 of 161
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`
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`Process Analysis
`
`3-51
`
`Figure 3.4.11 shows a 0.07 µm wide contact to poly. The contact etch has just
`penetrated the NiSi on top of the polysilicon.
`
`Figure 3.4.11Contact to Poly – TEM
`Figure 3.4.11 Contact to Poly – TEM
`
`M1 Cu
`
`Ta-based liner
`
`W contact
`
`TiN liner
`
`0.07 µm
`
`NiSi
`
`polysilicon
`
`Figure 3.4.11 Contact to Poly – TEM
`
`Page 85 of 161
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`Process Analysis
`
`3-52
`
`Figure 3.4.12 shows the top of a W contact. The TiN liner is about 4 nm thick at
`the top of the contact. The contacts were subjected to CMP, and sealed with the
`27 nm thick oxide PMD 4 and SiOC PMD 5 prior to the metal 1 trench etch.
`
`Figure 3.4.12Top of Contact – TEM
`Figure 3.4.12 Top of Contact – TEM
`
`M1 Cu
`
`PMD 5 - SiOC
`
`Ta-based liner
`
`27 nm
`
`PMD 4
`oxide
`
`~4 nm
`
`W contact
`
`TiN liner
`
`Figure 3.4.12 Top of Contact – TEM
`
`Page 86 of 161
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`Process Analysis
`
`3-53
`
`Figure 3.4.13 shows the bottom of a W stud, contacting the approximately 12 nm
`thick NiSi. The contact etch has just penetrated into the NiSi. The TiN liner is
`about 8 nm thick on the contact bottom.
`
`Figure 3.4.13Bottom of Contact – TEM
`Figure 3.4.13 Bottom of Contact – TEM
`
`W contact
`
`TiN liner
`
`~12 nm
`
`NiSi
`
`~8 nm
`
`~5 nm
`
`Si substrate
`
`Figure 3.4.13 Bottom of Contact – TEM
`
`Page 87 of 161
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`
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`Process Analysis
`
`3-54
`
`Figure 3.4.14 shows the TEM-EDS spectrum of the Ti-based contact liner, likely
`TiN.
`
`Figure 3.4.14TEM-EDS Spectrum of Contact Liner
`Figure 3.4.14 TEM-EDS Spectrum of Contact Liner
`
`Contact liner - Ti based
`
`Ti
`
`Ti
`
`W
`Cu
`
`WW
`
`4
`
`6
`Energy (keV)
`
`8
`
`10
`
`12
`
`W
`Si
`
`W
`
`2
`
`O
`C
`
`700
`
`600
`
`500
`
`400
`
`300
`
`200
`
`100
`
`Counts
`
`0
`
`0
`
`Figure 3.4.14 TEM-EDS Spectrum of Contact Liner
`
`Page 88 of 161
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`Process Analysis
`
`3-55
`
`Figure 3.4.15 shows the TEM-EDS spectrum of the NiSi used on the diffusions.
`
`Figure 3.4.15TEM-EDS Spectrum of Contact Silicide
`Figure 3.4.15 TEM-EDS Spectrum of Contact Silicide
`
`Si
`
`Substrate silicide - NiSi
`
`Ni
`
`C
`N
`O
`
`6000
`
`5000
`
`4000
`
`3000
`
`2000
`
`1000
`
`Counts
`
`Ni
`
`Ni
`
`8
`
`10
`
`0
`
`0
`
`2
`
`6
`4
`Energy (keV)
`
`Figure 3.4.15 TEM-EDS Spectrum of Contact Silicide
`
`Page 89 of 161
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`Process Analysis
`
`3-56
`
`3.5 Logic MOS Transistors
`The XXXX features 36 nm typical gate length MOS transistors, fabricated using
`a single level of Ni silicided polysilicon. The minimum gate length observed was
`32 nm. These transistors, fabricated using a 45 nm process, appear to have the
`identical structure to XXXX’s 65 nm transistors. A simple buffer oxide and silicon
`nitride sidewall spacer (SWS) continues to be used, along with Ni silicided poly
`gates. The 65 nm part did use Pt-doped Ni but, XXXX has used conventional Ni
`silicide with no Pt doping for this device. The 65 nm part also used a conventional
`gate oxide, while this 45 nm part uses a nitrided gate dielectric.
`
`Like XXXX’s 65 nm part, we do not see any evidence of strain engineering or
`memorized stress techniques employed on this 45 nm part. This 45 nm part is,
`however, manufactured using rotated wafers to improve the PMOS channel mobility.
`
`The dimensions of the minimum observed features are summarized in Table 3.5.1
`and Table 3.5.2.
`
`3.5.1 MOS Transistor Horizontal Dimensions
`
`Table 3.5.1
`
`MOS Transistor Horizontal Dimensions
`
`Feature
`Contacted gate pitch
`MOS minimum physical gate length
`MOS gate to contact space
`Transistor sidewall spacer width
`NiSi to gate edge space
`
`Size (nm)
`180
`32
`~30
`38
`22 - 33
`
`Table 3.5.1 MOS Transistor Horizontal Dimensions
`
`Table 3.5.2
`
`MOS Transistor Vertical Dimensions
`
`Feature
`MOS gate electrode thickness
`(NiSi/polysilicon)
`Gate dielectric thickness
`(oxide/nitride/oxide)
`N+ S/D depth
`P+ S/D depth
`
`3.5.2 MOS Transistor Vertical Dimensions
`
`Size (nm)
`108 (~16/92)
`
`2.0
`
`~0.06 µm (estimate)
`~0.06 µm (estimate)
`
`Table 3.5.2 MOS Transistor Vertical Dimensions
`
`Page 90 of 161
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`
`Structural Analysis – Sample Report
`Process Analysis
`
`3-57
`
`Figure 3.5.1 shows a SEM image of a cross section through a series of logic MOS
`transistors. The contacted gate pitch is 0.18 µm.
`
`Figure 3.5.1Minimum Contacted Gate Pitch
`Figure 3.5.1 Minimum Contacted Gate Pitch
`
`M1
`Cu
`
`W contacts
`
`0.18 µm
`
`STI
`
`poly gates
`
`Figure 3.5.1 Minimum Contacted Gate Pitch
`
`Page 91 of 161
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`Process Analysis
`
`3-58
`
`Figure 3.5.2 shows a SEM image of a series of NMOS transistors with a Si etch
`applied to delineate the approximately 0.06 µm deep N+ S/D diffusions.
`
`Figure 3.5.2NMOS Transistors – Si Etch
`Figure 3.5.2 NMOS Transistors – Si Etch
`
`0.18 µm
`
`N+
`
`N+
`
`~0.06 µm
`
`drain extension
`
`Figure 3.5.2 NMOS Transistors – Si Etch
`
`Page 92 of 161
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`
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`Process Analysis
`
`3-59
`
`Figure 3.5.3 shows a SEM image of a series of PMOS transistors, with a Si etch
`applied. The delineation etch has over-etched the P+ S/D diffusions. They are
`estimated to be about 0.06 µm deep.
`
`Figure 3.5.3PMOS Transistors – Si Etch
`Figure 3.5.3 PMOS Transistors – Si Etch
`
`0.18 µm
`
`~45 nm
`
`P+
`
`P+
`
`wide MOS gate
`
`Figure 3.5.3 PMOS Transistors – Si Etch
`
`Page 93 of 161
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`
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`Process Analysis
`
`3-60
`
`Figure 3.5.4 shows the 32 nm minimum gate length MOS transistor observed
`during this analysis.
`
`Figure 3.5.4Minimum Gate Length MOS Transistor
`Figure 3.5.4 Minimum Gate Length MOS Transistor
`
`buffer
`oxide
`
`NiSi
`
`polysilicon
`
`32 nm
`
`silicon
`nitride
`SWS
`
`Figure 3.5.4 Minimum Gate Length MOS Transistor
`
`Page 94 of 161
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`
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`Process Analysis
`
`3-61
`
`Figure 3.5.5 shows a TEM image of a pair of MOS gates. The gates have a
`notched profile just above the gate dielectric. This gate profile is reminiscent of
`some of XXXX’s notched gate transistors seen around the 0.18 µm node. The
`gate to contact spacing is variable, with a minimum spacing of about 30 nm. The
`Ni silicide to gate edge spacing also varies from about 22 nm to 33 nm. No
`discernable difference between the NMOS and PMOS gate structures was noted
`during the TEM analysis.
`
`Figure 3.5.5Minimum Gate Length MOS Transistor – TEM
`Figure 3.5.5 Minimum Gate Length MOS Transistor – TEM
`
`NiSi
`
`30 nm
`
`50 nm
`
`24 nm
`
`40 nm
`
`32 nm
`
`notch
`
`NiSi
`
`29 nm
`
`36 nm
`
`33 nm
`
`Figure 3.5.5 Minimum Gate Length MOS Transistor – TEM
`
`Page 95 of 161
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`
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`Process Analysis
`
`3-62
`
`Figure 3.5.6 shows the 2.0 nm thick oxide/nitride/oxide (ONO) logic gate dielectric.
`
`Figure 3.5.6Gate Dielectric – TEM
`Figure 3.5.6 Gate Dielectric – TEM
`
`polysilicon
`
`2.0 nm
`
`Si
`
`ONO
`
`Figure 3.5.6 Gate Dielectric – TEM
`
`Page 96 of 161
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`Process Analysis
`
`3-63
`
`Figure 3.5.7 shows a pair of narrow and wide gates. As mentioned, the ~12 nm
`thick SiON appears to be too thin to be used for applying tensile strain. However,
`stress memorization techniques may be used to boost the NMOS transistor drive
`current. Here, stress is transferred from a disposable dielectric layer to the silicon
`substrate. This strain is retained by the transistors after the disposable dielectric
`layer is removed.
`
`The bottom of the S/D contact is about 30 nm below the Si surface.
`
`Figure 3.5.7Wide and Narrow Gate Length Transistors – TEM
`Figure 3.5.7 Wide and Narrow Gate Length Transistors – TEM
`
`W contact
`
`SiON CESL
`
`NiSi
`
`~12 nm
`
`38 nm
`
`56 nm
`
`38 nm
`
`~30 nm
`
`36 nm
`
`78 nm
`
`Si substrate
`
`Figure 3.5.7 Wide and Narrow Gate Length Transistors – TEM
`
`Page 97 of 161
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`
`Structural Analysis – Sample Report
`Process Analysis
`
`3-64
`
`Figure 3.5.8 shows a detailed TEM view of the bottom of a transistor. The buffer
`oxide is 13 nm thick along the gate sidewall and 7 nm thick beneath the nitride
`SWS. The Ni silicide on the S/D diffusion is spaced 22 nm from the gate edge.
`
`Figure 3.5.8Gate Dielectric Overview – TEM
`Figure 3.5.8 Gate Dielectric Overview – TEM
`
`NiSi
`
`buffer
`oxide
`
`13 nm
`
`W
`contact
`
`27 nm
`
`polysilicon
`
`ONO gate dielectric
`
`22 nm
`
`38 nm
`
`NiSi
`
`SiON
`CESL
`
`silicon
`nitride
`SWS
`
`7 nm
`
`20 nm
`
`Si substrate
`
`Figure 3.5.8 Gate Dielectric Overview – TEM
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`Process Analysis
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`Figure 3.5.9 shows the edge of a gate in the gate width direction. The 108 nm
`gate thickness includes a 16 nm thick layer of NiSi.
`
`Figure 3.5.9Poly Thickness – TEM
`Figure 3.5.9 Poly Thickness – TEM
`
`16 nm
`
`108 nm
`
`NiSi
`
`polysilicon
`
`Si substrate
`
`11 nm
`
`STI
`
`Figure 3.5.9 Poly Thickness – TEM
`
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`Process Analysis
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`Figure 3.5.10 shows a detailed view of the transistor gate wrap. The Si corner has
`been rounded to provide smoother transition of the gate dielectric to STI. The
`radius of the Si corner is about 13 nm.
`
`Figure 3.5.10Poly Gate Wrap – TEM
`Figure 3.5.10 Poly Gate Wrap – TEM
`
`gate dielectric
`
`polysilicon
`
`13 nm
`
`Si substrate
`
`STI
`
`Figure 3.5.10 Poly Gate Wrap – TEM
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