The demonstration of D-SMT stressor on Si and Ge n-FinFETs M.-H. Liao*, P. G. Chens, S. C. Huangs, S. C. Kaos, C. X. Hungs, K. H. Lius , C. Liens, and C. Y. Lius National Taiwan University *E-mail: mhliaoa@ntu.edu.tw

Outline Introduction Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Key messages-I The ~20% Id,sat improvement is demonstrated successfully on the Si and Ge n-FinFETs with the implement of D-SMT stressor for the first time, based on the optimization of dislocation angle and the understanding of crystal re-growth velocities along different surface planes and directions. The mobility enhancement ratio with D-SMT stressor in Ge n-FinFET (37%) is found to be larger than Si n-FinFET (30%). Ultra-high capping stress film (>3 GPa) is needed and is the must to modify the crystal re-growth velocities along the [100] and [110] directions for the dislocation angle optimization.

Key messages-II The larger channel stress and mobility enhancement ratio are observed in the narrower gate width device, due to the effect of triple crystal re-growth directions on the FinFET structure. The mobility enhancement ratio with the stress on the Si (100)/[110], Si (110)/[110], Ge (100)/[110] and Ge (110)/[110] is calculated theoretically and agree well with the experimental data.

Outline Introduction Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Outline Introduction Module work on crystal re-growth velocity study D-SMT Ge FinFET Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Outline Introduction Module work on crystal re-growth velocity study D-SMT Ge FinFET Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Introduction: D-SMT stressor process and mechanism Ref: Samsung in IEDM 2010. Ref: TSMC in IEDM 2012. D-SMT process: IMP+ Capping film+ Anneal+ Capping film RM. Crystal re-growth velocities along different directions [100]/[110] influence the formation of dislocation line a lot. S/D dislocation line leads to the tensile stress in the channel.

Introduction: D-SMT stressor demonstration in the Si planer device Ref: Samsung in IEDM 2010. Ref: TSMC in IEDM 2012. Ref: GF in VLSI 2013. D-SMT has been investigated widely and is demonstrated to be the effective stressor in the Si planer device to boost the device mobility and modulate the metal work function. (tensile stress in the channel)

Introduction: D-SMT stressor demonstration in the Si planer device Ref: Samsung in IEDM 2010. Ref: TSMC in IEDM 2012. Ref: GF in VLSI 2013. D-SMT has been investigated widely and is demonstrated to be the effective stressor in the Si planer device to boost the device mobility and modulate the metal work function. (tensile stress in the channel)  This work we focus on Ge !!

Introduction: Simulation and modeling for D-SMT stressor in the Si planer device Ref: Intel in IEDM 2011. Ref: NTU in JAP 2012. Ref: NTU in EDL 2013. Simulation and modeling of the D-SMT on Si were built up. The optimized dislocation angle for D-SMT stressor, which is influenced by the different crystal re-growth velocities along different directions, has also been investigated on Si.

Introduction: Simulation and modeling for D-SMT stressor in the Si planer device Ref: Intel in IEDM 2011. Ref: NTU in JAP 2012. Ref: NTU in EDL 2013. Simulation and modeling of the D-SMT on Si were built up. The optimized dislocation angle for D-SMT stressor, which is influenced by the different crystal re-growth velocities along different directions, has also been investigated on Si.  This work we focus on the study on the FinFET structure !!

Outline Introduction Module work on crystal re-growth velocity study D-SMT Ge FinFET Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Introduction: High mobility Ge FinFET device Ref: NCTU in IEDM 2013. Ge n-FinFET device has been demonstrated previously. Gate stack and stressor development are key issues for Ge. (Ge gate stack formation can refer to our another work in T9-2, presented on Wednesday, June 11, 10:50 a.m.).

Could D-SMT stressor be used in the high mobility Ge FET Could D-SMT stressor be used in the high mobility Ge FET ? Could D-SMT stress be effective in the FinFET structure ? Need to investigate the crystal re-growth velocities along different directions/surface plans in Si and Ge. Strained Si and strained Ge theory is also needed to be studied.

Could D-SMT stressor be used in the high mobility Ge FET Could D-SMT stressor be used in the high mobility Ge FET ? Could D-SMT stressor be further effective in the FinFET structure ? Need to investigate the crystal re-growth velocities along different directions/surface plans in Si and Ge. Strained Si and strained Ge theory is also needed to be studied.

Could D-SMT stressor be used in the high mobility Ge FET Could D-SMT stressor be used in the high mobility Ge FET ? Could D-SMT stressor be further effective in the FinFET structure ? Need to investigate the crystal re-growth velocities along different directions/surface plans in Si and Ge. Strained Si and strained Ge theory is also needed to be studied.

Could D-SMT stressor be used in the high mobility Ge FET Could D-SMT stressor be used in the high mobility Ge FET ? Could D-SMT stressor be further effective in the FinFET structure ? Need to investigate the crystal re-growth velocities along different directions/surface plans in Si and Ge. Strained Si and strained Ge theory is also needed to be studied.

Could D-SMT stressor be used in the high mobility Ge FET Could D-SMT stressor be used in the high mobility Ge FET ? Could D-SMT stressor be further effective in the FinFET structure ? Need to investigate the crystal re-growth velocities along different directions/surface plans in Si and Ge. Strained Si and strained Ge theory are also needed to be studied.

Outline Introduction Module work on crystal re-growth velocity study Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

The procedure for the crystal re-growth velocity extraction and study Wafer posted on the polishing stubs with different angle (q) q q IMP/Capping film/Anneal Capping film RM and CMP q q TEM check q q The standard procedure for the crystal re-growth velocity extraction is used. Crystal re-growth velocity on different substrate orientation/Re-growth directions/material/stress can be extracted experimentally.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Module work on crystal re-growth velocity study: Re-growth directions (q)-I [011]: 2 α-atoms [111]: 3 α-atoms [001]: 1 α-atom Ref: Uni. of Florida, 2012. The different α-atoms along [001], [011], and [111] directions influence the crystal re-growth velocities a lot. The polishing stubs with different angle (q) was used to study the influence of q on the crystal re-growth velocities.

Module work on crystal re-growth velocity study: Re-growth directions (q)-II [011]: 2 α-atoms q3 q2 [111]: 3 α-atoms Sample q1 [001]: 1 α-atom Ref: Uni. of Florida, 2012. The different α-atoms along [001], [011], and [111] directions influence the crystal re-growth velocities a lot. The polishing stubs with different angle (q) was used to study the influence of q on the crystal re-growth velocities.

Module work on crystal re-growth velocity study: Re-growth directions (q)-III [100] [110] [100] [110] The crystal re-growth velocity along [100] is 1.78 times than [110] on Si. Based on the understanding of crystal re-growth velocity along different directions, the angle of dislocation line can be controlled and further influence the device performance.

Module work on crystal re-growth velocity study: Re-growth directions (q)-IV [100] [110] Q Dislocation line Pinched The crystal re-growth velocity along [100] is 1.78 times than [110] on Si. Based on the understanding of crystal re-growth velocities along different directions, the angle of dislocation line can be formed and further influence the device performance.

Module work on crystal re-growth velocity study: Re-growth directions (q)-V [100] [110] Q Dislocation line Pinched If the crystal re-growth velocity can be controlled, the dislocation angle Q and stress distribution can be optimized. 𝑣(q)= 𝑣 0 x f(q), 𝑣 0 is the temperature independent factor, f(q) is the direction-related parameters.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Module work on crystal re-growth velocity study: Sub Module work on crystal re-growth velocity study: Sub. orientations (100) and (110)-I q3 q2 q1 Ref: Uni. of Florida, 2012. Because the FinFET structure has two (110) side-wall surface-plans, the study for crystal re-growth velocity on (110) surface is very important. The (110) Si wafer is posted on the polishing stubs for the study.

Module work on crystal re-growth velocity study: Sub Module work on crystal re-growth velocity study: Sub. orientations (100) and (110)-II q3 q2 (110) sample q1 Ref: Uni. of Florida, 2012. Because the FinFET structure has two (110) side-wall surface-plans, the study for crystal re-growth velocity on (110) surface is very important. The (110) Si wafer is posted on the polishing stubs for the study.

Module work on crystal re-growth velocity study: Sub Module work on crystal re-growth velocity study: Sub. orientations (100) and (110)-III The crystal re-growth velocity along different directions on Si (100) and Si (110) surface plans are provided and modelled. The different behavior can be explained by Arrhenius-type relationship and activation energies.

Module work on crystal re-growth velocity study: Sub Module work on crystal re-growth velocity study: Sub. orientations (100) and (110)-IV The different behavior can be explained by Arrhenius-type relationship and activation energies.

Module work on crystal re-growth velocity study: Sub Module work on crystal re-growth velocity study: Sub. orientations (100) and (110)-V The different behavior can be explained by Arrhenius-type relationship and activation energies. 𝑣= 𝑣 0 x f q x exp −∆𝐺 𝑘𝑇 , ∆𝐺 is the activation energy. *∆𝐺 (100): 2.17eV, (110): 1.32eV.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Module work on crystal re-growth velocity study: Material Si and Ge The crystal re-growth velocity along different directions on Si/Ge and (100)/(110) surface plans are both provided. Ge has the larger crystal re-growth velocity than Si, due to the smaller activation energy (∆𝐺).

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement

Module work on crystal re-growth velocity study: w and w/o stress application tensile Comp. The tensile/compressive stress capping SiN film enhances/decreases the re-growth velocity. Modeling: 𝑣(q, e)= 𝑣 0 x f(q) x exp −∆𝐺 𝑘𝑇 x 1+𝐴(e)𝜅 where 𝐴(e) is the curvature factor and κ=1/𝑟 where 𝑟 is the radius of curvature at the mask edge. *Ref: Uni. of Florida, 2013.

Module work on crystal re-growth velocity study: w and w/o stress application Ref: Uni. of Florida, 2013. Based on the module study, the capping stressed SiN film influence the crystal re-growth velocity a lot. Ultra-high stressed SiN film (>3GPa) plays the important role for the D-SMT formation on the Ge FinFET.

The optimization of Q by capping stress film [100] [110] Pinched Dislocation line Q < 45o Capping stressed SiN film influence the crystal re-growth velocity a lot. The re-growth velocity along [100] is faster than [110] “intrinsically” and it results in the dislocation angle Q < 45o . (has the small stress level/distribution in the channel)

The formation of D-SMT in Si and Ge [100] [110] Pinched Dislocation line Q = 45o With the implement of ultra-high stressed SiN film (>3GPa), the re-growth velocity along [100] and [110] directions can be modulated to be the same and result in dislocation Q =45o. (has the high stress level/distribution in the channel) The formation of D-SMT on Ge is more easy than it on Si.

The formation of D-SMT in Si and Ge [100] [110] Pinched Dislocation line Q = 45o With the implement of ultra-high stressed SiN film (>3GPa), the re-growth velocity along [100] and [110] directions can be modulated to be the same and result in dislocation Q =45o. (has the high stress level in the channel) The formation of D-SMT on Ge is more easy than it on Si.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement 2: 09 pm

Module work on stress measurement Accurate channel stress with the application of D-SMT in Si and Ge is extracted by AFM-Raman experimentally. The large channel stress is observed in the narrow gate width device. With D-SMT, there have 2.5/1.6Gpa tensile stress in Ge/Si.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement 2: 10 pm

Device demonstration and theoretical analysis-I With the implement of D-SMT on the FinFET structure, there have +30% and +37% mobility improvement in Si and Ge devices. Based on the AFM-Raman stress measurement, there have 1.6/2.5 Gpa tensile stress in our Si/Ge devices.

Device demonstration and theoretical analysis-II The higher channel stress and m improvement are observed on the narrower W FinFET devices. Based on the strained Si theory, stress can improve the m on the planer Si (100)/[110] devices. <Tensile/Comp. for n/p FET>

Device demonstration and theoretical analysis-III x 2 x 2 The higher channel stress and m improvement are observed on the narrower W FinFET devices. For the Si FinFET, having another two (110)/[110] transport cases, the stressor will become more effective to the m booster, even the intrinsic m will lose.

Device demonstration and theoretical analysis-IV The higher channel stress and m improvement are observed on the narrower W FinFET devices. Ge (100)/[110] planer device has the higher intrinsic mGe, and the stressor is still valid to boost the mGe.

Device demonstration and theoretical analysis-V The higher channel stress and m improvement are observed on the narrower W FinFET devices. For the Ge FinFET, having another two (110)/[110] transport cases, the intrinsic mGe becomes higher, but it seems to be saturated under the high stress application.

Device demonstration and theoretical analysis-V The higher channel stress and m improvement are observed on the narrower W FinFET devices. For the Ge FinFET, having another two (110)/[110] transport cases, the intrinsic mGe becomes higher, but seems to be saturated under the high stress application. Need more s !

Device demonstration and theoretical analysis-VI The higher channel stress and m improvement are observed on the narrower W FinFET devices. The theoretical calculation agree well with our experimental data well.

Device demonstration and theoretical analysis-VI With the implement of D-SMT on the FinFET structure, there have +21% and +25% Id,sat improvement in Si and Ge devices. *(There have 1.6/2.5Gpa tensile stress in our Si/Ge devices)* Ge gate stack formation can refer to our another work in T9-2, presented on Wednesday, June 11, 10:50 a.m.).

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement 2: 13 pm

Summary and comparisons The D-SMT stressor is demonstrated for the first time to boost the Ge devices and FinFET structure, based on (a) the optimization of dislocation angle, (b) the understanding of crystal re-growth velocities along different directions and planes in Si and Ge, and (c) the application of the ultra-high capping stress film (>3 GPa).

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement 2: 14 pm

Conclusions The D-SMT stressor is successfully demonstrated to boost the device performance (+20% Id,sat and +30% mobility) on the Si and Ge n-FinFETs, for the first time, based on the (a) optimization of dislocation angle ; (b) the understanding of crystal re-growth velocities along different directions and planes in Si and Ge ; (c) the application of the ultra-high capping stress film (>3 GPa). Different mobility enhancement ratio with stress on (100)/(110) surface planes in Si/Ge materials are also investigated theoretically and agree well with experimental data.

Outline Introduction Module work on crystal re-growth velocity study Re-growth directions: q Substrate orientations: (100) and (110) Material: Si and Ge Stress: w and w/o stress application Module work on stress measurement Device demonstration and theoretical analysis Summary and comparisons Conclusions Acknowledgement 2: 15 pm

Acknowledgement This work is supported by: National Taiwan University, Taiwan, under the grant 103R7734. Ministry of Science and Technology, Taiwan, under the grants 102-2218-E-002-003- and 101-2628-E-002-018-MY3. Ministry of Economic Affairs (MEA), Taiwan, under the grant 101-EC-17-A-01-S1-219. TSMC, Taiwan, JDP and Big League program, under the grant 102-2622-E-002-014-.

Q and A Thank a lot ! 2: 15 pm

Back-Up

The optimization of q by capping stress film [100] [110] Pinched Dislocation line q The re-growth velocity along [100] is faster than [110] intrinsically and it results in the dislocation q < 45o. With the implement of ultra-high stressed SiN film (>3GPa), the re-growth velocity along [100] and [110] directions can be modulated to the same and result in dislocation q =45o.

The formation of D-SMT in Si and Ge [100] [110] Pinched Dislocation line q With the implement of ultra-high stressed SiN film (>3GPa), the re-growth velocity along [100] and [110] directions can be modulated to the same and result in dislocation q =45o. The formation on Ge is more easy than it on Si.

Idsat improvement ratio is consistent with mobility ? The Idsat and mobility improvement ratio in Si/Ge n-FinFETs are similar. The Vt position in Si and Ge n-FinFETs are different. Note that the value of tensile stress in Si and Ge is different.

Vt positions With the implement of D-SMT, there has the Vt drop on the Si FinFET devices. With the implement of D-SMT, the Vt position on Ge FinFET is almost the same. The difference is due to the band structure change under stress in Si and Ge.

The difference between planer and FinFET devices with D-SMT The higher channel stress is observed in the FinFET structure, due to the triple-directions crystal re-growth effect. The higher channel stress and mobility improvement ratio can be observed in the FinFET devices than it in the planer device.