ELENA19 Dr. Satinder Kumar Sharma (Coordinator & Associate - PowerPoint PPT Presentation

Advancement Towards Sub-15 nm Resists Patterning for High Volume Manufacturing of Semiconductor Industry ELENA’19 Dr. Satinder Kumar Sharma (Coordinator & Associate Professor) Centre for Design & Fabrication of Electronic Devices (C4DFED) School of Computing and Electrical Engineering (SCEE), Indian Institute of Technology (IIT)-Mandi (Himachal Pradesh)-175005 ( India ) E-mail:satinder@iitmandi.ac.in Contribution and Funding

ELENA’19 Brief Outline of the Presentation ……. ❖ Semico icond nduct uctor or Techn hnol olog ogy y Adva vance ncemen ment ❖ Next xt Gener eratio ation n Litho thograp graphy hy Road admap map for or HVM VM ELENA’19 ❖ Resi sists sts Techn hnol olog ogy y Challenges allenges ❖ Various rious Designed signed & Develop veloped ed Resi sists sts For ormulati mulations ns for r NGL; L; EBL, L, HIBL, BL, EUV ❖ High gh Resolutio solution n Vario ious us L/S S Patteri tering ng on Designed signed & Deve velo loped ped Resis sists ts Formul rmulations ations ❖ Summar mary

ELENA’19 Semiconductor Technology Advancement & Next Generation Lithography Roadmap (HVM) Looking for Future ~ 10nm Node or Beyond ❖ Double Exposure (~ 193nm Immersion) lithography (DEL) ❖ Electron Beam projection Lithography (EBL) ( Throughput typically 50x lower than optical lithography) ❖ Ion Beam projection Lithography (IBL) ( I ons scatter much less than electron (higher resolution and throughput)) ❖ NIL & DSA related lithography (Large area concerns) Since EUV sources are still being under development phase, thus the limited access ✓ Extreme Ultraviolet Lithography (EUVL) for resists developer to run the experiments, ( λ ~13.5 nm for higher resolution, no need RET, 15 to 50% cost reduction needed to develop materials ……… ??? compared to multi-patterning schemes ) No consensus exists about the winner for HVM. Most likely will be EUVL !!!

ELENA’19 NGL - He + (HIBL) & e - (EBL) Prelude to HVM EUVL Technology (with resists) ▪ One of the key metrics for EUV resist is the sensitivity towards EUV radiation. ▪ However, it is absorbed that the exposure energy within the resist film that is mainly responsible for the resists chemistry. This applies to both high KeV electrons, He + ion and EUV photons. ▪ 1.23  De Broglie = nm √ V Surface suffers from large interaction volume at the surface in Next Generation Lithography Prelude to EUVL case of e-beam (spot size 0.8 nm) and generated SE with ~ 50eV He + ion (0.35 nm) e-beam (0.8 nm) Beam is well collimated beyond the SE depth. Recoil EUV (  =13.5 nm) contribution is negligible (spot size 0.35 nm) A 92eV (13.5 nm) photon is absorbed, creates photoelectron with K.E. (~80 eV) that loses energy and liberate SE’s (10 to 60 eV) in resist that leads to further chemistry Technology SE’s Post Exposure Affected Area Reference : M. Kotera, et. al , "Photoelectron trajectory simulation in a resist for EUV lithography," 2007 Kyoto, 2007, pp. 94-95. Gregor Hlawacek et al. November JVST B 32(2):020801 We are developing organic, inorganic, hybrid & , containing elements having high EUV absorption capacity resists for

ELENA’19 EUV Photo Resists Technology Challenges ❖ EUV λ ~13.5 nm interaction with the resist. ❖ The photon energy of EUV (13.5 nm, 92.5 eV) is much higher than ionization potential of resist materials (~10 eV). Reaction mechanisms change from photochemistry to radiation chemistry. (A review paper : Kozawa and Tagawa, 2010) Dramatic enhancement ❖ Acid diffusion is key problem in conventional resists . of resist sensitivity is Adaptation of NGL for mass very difficult due to ❖ Patterning-collapse, blurriness, and overlay issues. RLS trade-off ❖ Resolution (R), line edge and width roughness & sensitivity (RLS). Production: Challenges ❖ Photon absorbance in EUVL is 14X less than established ArF Lithography Trade-off between Resolution (R), LER & LWR So, There is a need to design a totally new chemistry for EUV photo-resist materials to support less than 16 nm technology Ref: Garner, C Michael, “Lithography for enabling advances in integrated circuits and devices.” Phil. Trans. R. Soc. A (2012) 370, 4015. and Sensitivity (S) [RLS) for NG resists Technology High Sensitivity (so allowing weak sources); High resolution (for small feature sizes); Low LER How to Improve RLS Trade-off for EUVL (line edge roughness); Post exposure instability; Minimal out-gassing (contaminate optics) EUV Exposure Tool Organic Inorganic Resists Resists EUV Interaction with Resists (Accomulated Energy Profie ) Resists Development (Acid Generation ) Hybrid Resists Organo-Metallic (Blending) Resists Other Treatments: Vapor; Pre Bake, Hard bake, Recently, organometallics have emerged as promising NGL resists applications. Wet/Dry Etching

ELENA’19 IIT Mandi Developed Indigenous Resists Technology Cu-Core Ni-Core MOC IIT Mandi Design & Developed MOC He+ & EBL Resists for NGL Active RESIST Advanced sub-15 nm EUVL patterning Sn ZnO based MOC CAR

ELENA’19 Evolution of Resists Technology Formulations at IIT Mandi (H.P), India Chemical Structures of HR Resists for NGL Node

ELENA’19 Polyarylene Sulfonium Salt – Universal Photo-Resist ❖ Polyarylene sulfonium salts were synthesized through free Lithography Parameters radical polymerization process. Universal HR Resists for NGL Node Substrate : 4ʺ inch p -type silicon ❖ Molecular weight ~ 5,675 g/mol -1 ; Poly Disparity Index = 1.3 Resist formulations: 2 wt % PAS in Acetonitrile ❖ Polyarylene sulfonium salts were successfully explored as a new Spinning parameters: 4500 RPM for 60 S organic n-CAR for higher to lower node lithographic Film Thickness: ~ 33 nm applications. Pre exposure bake: 100ºC for 60 S Post exposure bake: 50 ºC for 60 S ❖ PAS act as a dual tone resist . Both the positive and negative EUVL exposure: 37.7 mJ cm -2 tone features can be patterned while changing the developer. Developer : 0.05N TMAH/35 sec/DIW/30 S Synthesis (a) (b) R z = ~ 0.349 nm Figure: PAS thin films; a) Optical image; b) AFM image . 9 Ref: ACS Appl. Mater. Interfaces., 2017, 9, 17 − 21

ELENA’19 Polyarylene Sulfonium Salt based Resists – EUVL HR Patterning at LBNL Berkeley, USA Line Patterns Complex Patterns (a) (b) 20 25 30 35 40 45 50 60 70 High Resolution EUV Resists Patterning L/5S 20 25 30 L/5S for NGL Node (d) (C) (d) L/5S L/4S L/3S L/2S L/4S L/3S 20 nm 20 nm (d) (C) Ref: ACS Appl. Mater. Interfaces., 2017, 9, 17 − 21

ELENA’19 MAPDST-Phenyl Tin Hybrid Copolymer for Higher Resolution Patterning Applications High Resolution EBL Resists Patterns for NGL Node 20 nm L/2S patterns 30 nm L/2S patterns MAPDST-triphenyl tin copolymer ❖ MAPDST-Triphenyl tin copolymer was synthesized through free radical polymerization process. ❖ Molecular weight 6933 g/mol -1 ; Poly Disparity Index = 2.0 ❖ Calculated x and y composition from NMR analysis is 97.3: 2.7 ❖ Resolution got improved 20 nm to 15 nm nodes compared to the poly-MAPDST ❖ Calculated thin film thickness ~ 45 nm ❖ 30 & 20 nm patterns @ 450 uC/cm 2 and 18 & 15 nm @ 700 uC/cm 2 ❖ e-beam exposure dose used 200- 700 uC/cm 2 ❖ Due to incorporation of tin monomer poly-MAPDST resolution got improved from 20 nm to 15 nm nodes. 18 nm L/10S patterns 15 nm L/10S patterns

ELENA’19 High-resolution XPS spectra for the S 2p Untreated 70 SO 3 XPS sulfur functionalities relative concentration SO 4 S=O S-C 60 15s Intensity signal (a.u.) S-C 50 S=O SO 3 40 XPS Spectra for Resists 30s SO 4 30 120s 20 10 300s 0 174 172 170 168 166 164 162 160 0 50 100 150 200 250 300 Binding Energy (eV) Irradiation time (s) High-resolution XPS spectra for the S 2p region of Dependence of the sulfur functionalities relative the pristine and irradiated films at 103.5 eV. concentration on the irradiation time The loss of SOx like SO 4 , SO 3 , S=O are functional groups with the increase of irradiation time (decomposition of the triflate moeity)

ELENA’19 HR-XPS spectrum 2k Untreated Untreated Sn 3d 5/2 O-S Sn 3d 3/2 1k Intensity signal (a.u.) 15 s SnO 15s O-Sn/O-C SnO 1k 2k 30 s O=C 30s XPS Spectra for Resists CPS 3k 120s 120 s 2k 6k 300s 300 s 4k 536 534 532 530 528 498 496 494 492 490 488 486 484 482 Binding Energy (eV) Binding Energy (eV) HR-XPS spectrum of untreated film shows mainly a low oxidized HR-XPS spectra of O 1s signal Tin (Ph4-Sn-O/ Ph3-Sn-O) [Ref] ➢ A new signal appearing at higher binding energy can be ➢ Overlapping of the XPS signals corresponding to correlated with SnO/SnO 2 oxidation states of Tin. O-Sn and O-C ➢ Results finally are confirming that the Tin linked [1] Moulder, J. F. (1992). Handbook of X-ray Photoelectron Spectroscopy: A Reference Book of Standard Spectra for Identification and Interpretation of XPS Data. USA, Physical Electronics Division, Perkin-Elmer Corporation. to the polymer backbone and 3 aromatic rings is [2] Willemen, H., D. F. Vandevondel, et al. (1979). "Esca Study of Tin-Compounds." Inorganica Chimica Acta 34(2): 175-180. [3] Sharma, A.; Singh, A. P.; Thakur, P.; Brookes, N. B.; Kumar, S.; Lee, C. G.; Choudhary, R. J.; Verma, K. D.; Kumar, R., Structural, oxidizing when irradiated at 103.5 eV electronic, and magnetic properties of Co doped SnO(2) nanoparticles. J.Appl.Phys. 2010, 107 (9).