IMP-TiCVD TiN

● Problems with conventional PVD technology:
■ Overhangs at contact openings ■ Thin deposition on sidewall ■ Discontinuous at the contact bottom
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COH-Ti Deposition
Major issue and CIP(Continues Improvement Program) Summary
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Applications of Ti & TiN
0.5um Contact ● BOE 200:1 20sec ● Ti 400A / TiN 1000A Metal-1 ● AlCu 4K / TiN 1.4K 0.35um ● Ar+ sputter 100A ● C-Ti 200A / TiN 1000A ● AlCu 4K / TiN 1.4K 0.25um ● Ar+ sputter 100A ● C-Ti 300A / CVD TiN 2x50 ● TiN 250A / AlCu 4K / TiN 700A VIA-(n-1) ● TiN 1000A ● TiN 1000A ● Ar+ Sputter 180A ● C-Ti 300A / CVD TiN 1x70 Metal-n ● AlCu 4K / TiN 1.4K ● AlCu 4K / TiN 1.4K ● TiN 250A / AlCu 4K / TiN 700A 0.18um ● Ar+ sputter ● C-Ti 200A / CVD TiN 1x50 ● N2 off 4’’ / TiN 250A AlCu 4K / N2 off 2’’ / TiN 250A ● Ar+ Sputter 180A ● C-Ti 300A / CVD TiN 1x50 ● N2 off 4’’ / TiN 250A AlCu 4K / N2 off 2’’ ●TiN for ARC ●TiN: stop layer for VIA etch ●Ti ●TiN: avoid W diffuse to Si ●TiN: ARC Purpose
RF ● Inductive coupling More efficient power transfer from RF generator to the plasma
● Plasma density: 10E11/cm3 < n < 10E12/cm3 ( Medium density plasma ) ● Ion neutral ratio: Metal 70~90% , Ar 0.1~1%
● HP-PVD TiN :
HP-PVD TiN is reactive ion sputtered (RIS)
■ Reactive begin with Ti target ■ Flow Ar & N2 to plasma chamber ■ 2Ti + N2 = 2 (TiN) achieved during process
Conformal Coverage through Re-sputtering
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Theory of TiN
● What is TiN?
TiN is a “ refractory metal compound ”.
■ Refractory ■ Metal ■ Compound high melting temperature good conductor (better than Ti) 2Ti + N2 = 2 (TiN)
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Plasma Density
Medium density
Low density
Space plasmas, Ionosphere, Solar corona Processing plasmas,e.g. Reactive ion etch,PECVD,PVD,etc
High density
Fusion plasmas, Solar atmosphere
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Theory of Ti Deposition
PVD Technology Trend
Collimator
Conventional Long-throw Standard PVD
Cost-Effective Downwards Extendible PVD solution
Vectra / Electra IMP (Ionized Metal Plasma) IMP
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Electra IMP uses Wafer Bias and Pressure to Optimize Coverage
Profile W/O Bias
Ion Flux
Profile with Bias
Coverage can be Tailored by Wafer Biasing
Ion Energy = DC Bias + Vp ( Vp : Plasma Potential)
/ TiN 250A
Top VIA ● TiN 1000A ● TiN 1000A ● Ar+ Sputter 180A ● C-Ti 300A / CVD TiN 1x70 Top Metal ● AlCu 8K / TiN 250A ● AlCu 8K / TiN 250A ● TiN 500A (vent) / AlCu 8K / TiN 250A ● Ar+ Sputter 180A ● C-Ti 300A / CVD TiN 2x50 ● TiN 500A (vent) / AlCu 8K / TiN 250A ●TiN for ARC ●TiN: stop layer for VIA etch
´ ¡ £ Y
0.35um
Y £ ´ ¡ X ¡ ´ ¡ ´ ¡
Meets Requirement Does Not Meet Requirement
0.25um
Y £ ´ ¡ ´ ¡ Y £ ´ ¡
0.18um
Y £ ´ ¡ ´ ¡ Y £ ´ ¡
● As the geometries decrease the PVD applications are challenged to achieve the necessary step coverage and conformality. ● PVD TiN step coverage is poor which results in a requirement for increased film thickness,this results in an overhang at the top of the contact.
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Fundamentals of Reactive Ion Sputter Deposition
● Simple chemical reactions can be performed during sputtering. ● Target material can be reacted to deposit a compound of the target material and a gaseous species.
Introduction of IMP Ti & CVD TiN
by G.F.Tung
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Presentation Subject
Why IMP-Ti & CVD TiN Theories of IMP-Ti & CVD TiN Machine configuration
Process
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Bottom Coverage
Plasma Parallel energy Sheath Bias energy Resultant ion energy Wafer
● DC/RF power ratio: ■ Suitable DC/RF ratio: better edge thick film ■ High DC/RF ratio: poor bottom coverage ● Bias power: Good bottom coverage can be achieved even with no bias.
10E7/cm3
10E8/cm3
10E9/cm3
10E10/cm3
10E11/cm3
10E12/cm3
10E13/cm3
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IMP Ti Deposition
Target
Magnetron Plasma Target Sputtering DC
IMP Plasma
RF
coil sputtering
Wafer
Target
Collimator
DC
Wafer
L/W: 1:1 or 2/1
● Advantage : Increased the bottom coverage ● Disvantages of COH-Ti : ■ Low deposition rate
■ Short PM cycle time
● The reaction is controlled by the flow of reacting gas.
● The reaction can occur on the target face,on the wafer surface,and even in the vacuum between the target and the wafer.
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Characters of IMP (Ion Metal Plasma)
● RF and DC inputs create a medium density plasma. ● Metal atoms are thermalized and ionized. ● Ions are diffused to the substrate and accelerated through theVD TiN
● Poisoned mode :
If the gas flow ratio,N2/Ar is greater than 1,the process is in poisoned mode. In this mode,the target surface is totally poisoned by N2 and then the TiN is bombarded by Ar ion to the wafer. The advantage of this mode is the well controlled film composition.
● Ti/TiN for Contact / VIA : Barrier Layer
■ To avoid W diffuse to Si ----- Contact ■ Stop layer for VIA etch ----- VIA
● TiN for Metal : ARC ( Anit-Reflection Coatings ) for better lithography
● External wafer bias is used to obtain conformal coverage by re-sputtering.
● Ions are directional. ● Process enhances film coverage for Ta,TaN and Cu.
■ Potential particle issue on the end of collimator parts life
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Longthrow Ti Deposition
Target
DC
Wafer
● The spacing between the target and pedestal is 30cm.
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Why IMP-Ti & CVD TiN
Plug Liner Options for PVD and CVD Applications
Line Width Standard PVD Ti COH-Ti IMP-Ti Standard PVD TiN CVD TiN 0.5um
´ ¡ X ¡ X ¡ ´ ¡ X ¡