Fabrikation af lav temperatur kulstof nanorør Lodrette Interconnect Kompatibel med Semiconductor Technology
Summary
A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.
Abstract
We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.
Introduction
Kobber og wolfram, metaller, som i øjeblikket anvendes til interconnects i state-of-the-art meget-stor skala integration (VLSI) teknologi, nærmer deres fysiske grænser med hensyn til pålidelighed og elektrisk ledningsevne 1. Mens ned-skalering transistorer generelt forbedrer deres præstationer, er det faktisk øger modstand og strømtæthed af forbindelsesledninger. Dette resulterede i interconnects dominerer det integrerede kredsløb (IC) resultater med hensyn til forsinkelser og strømforbrug 2.
Kulstof-nanorør (CNT) er blevet foreslået som alternativ til Cu og W metallisering, især for lodrette interconnects (vias) som CNT let kan været dyrket lodret 3. CNT har vist sig at have fremragende elektrisk pålidelighed, tillader en op til 1.000 gange højere strømtæthed end Cu 4. Hertil kommer, at CNT ikke lider overflade og korngrænseferritfilm spredning, hvilket øger resistivity af Cu på nanometer skala 5. Endelig har CNT vist sig at være fremragende termiske ledere 6, der kan hjælpe til termisk styring i VLSI chips.
For en vellykket integration af CNT i VLSI teknologi er det vigtigt, at processerne for CNT vækst er forenelig med halvleder opspind. Det kræver den lave vækst i CNT (<400 ° C) ved hjælp af materialer og udstyr, der betragtes som forenelige og skalerbar til stor skala produktion temperatur. Selv om der er påvist mange eksempler på CNT test vias i litteraturen 7,8,9,10,11,12,13,14, de fleste af disse bruger Fe som katalysator, der betragtes som en kontaminant i IC fremstilling 15. Desuden, væksttemperaturen bruges i mange af disse værker er meget højere end den øvre grænse på 400 ° C. Fortrinsvis CNT bør også dyrkes under 350 ° C, for at tillade integration med moderne lav K dielektrika eller fleksiblesubstrater.
Her præsenterer vi en skalerbar fremgangsmåde til dyrkning CNT ved temperaturer så lave som 350 ° C under anvendelse af Co som katalysator 16. Denne metode er af interesse for opdigte forskellige elektriske strukturer bestående af lodret linie CNT i integrerede kredsløb, der spænder fra interconnect og elektroder til super kondensatorer og felt gasinstallationer. Co katalysatormetallet bruges ofte i IC fremstilling til fremstilling af silicidbelægning s 17, mens TiN er en ofte anvendt barrieremateriale 7. Desuden har vi demonstrere en proces til fremstilling af CNT test vias mens kun bruge teknikker fra standard halvleder fremstillingsindustrien. Med denne, er CNT test vias fremstilles, kontrolleres ved scanning elektronmikroskopi (SEM) og Raman spektroskopi, og elektrisk karakteriseret.
Protocol
Representative Results
Discussion
Figur 1 viser en skematisk oversigt over strukturen fremstillet i dette arbejde, og som blev anvendt til 4-punkts probe målinger. Da potentialet måles gennem sonder bærer ingen strøm, kan måles nøjagtigt spændingsfald (VH-VL) i den centrale CNT bundt og dets kontakter til metallet. Større diameter CNT bundter anvendes til at kontakte bunden TiN lag fra kontaktfladerne, med henblik på at mindske den samlede modstand for den aktuelle tvinger prober og maksimere potentialet fald på den…
Disclosures
The authors have nothing to disclose.
Acknowledgements
Part of the work has been performed in the project JEMSiP_3D, which is funded by the Public Authorities in France, Germany, Hungary, The Netherlands, Norway and Sweden, as well as by the ENIAC Joint Undertaking. The authors would like to thank the Dimes Technology Centre staff for processing support.
Materials
| Materials | Company | Catalog Number | Comments/Description |
| Si (100) wafer 4" | International Wafer Service | Resisitivity: 2-5 mΩ-cm, thickness: 525 µm | |
| Ti-sputtertarget (99.995 % purity) | Praxair | ||
| Al (1% Si)-sputtertarget (99.999 % purity) | Praxair | ||
| Co (99.95 % purity) | Kurt J. Lesker | ||
| Chemicals | Company | Catalog Number | Comments/Description |
| SPR3012 positive photoresist | Dow Electronic Materials | ||
| MF-322 developer | Dow Electronic Materials | ||
| HNO3 (99.9 %) | KMG Ultra Pure Chemicals | ||
| HNO3 (69.5%) | KMG Ultra Pure Chemicals | ||
| HF 0.55% | Honeywell | ||
| Tetrahydrofuran | JT Baker | ||
| Acetone | Sigma-Aldrich | ||
| ECI3027 positive photoresist | AZ | ||
| Tetraethyl orthosilicate (TEOS) | Praxair | ||
| Gasses | Company | Catalog Number | Comments/Description |
| N2 (99.9990%) | Praxair | ||
| O2 (99.9999%) | Praxair | ||
| CF4 (99.9970%) | Praxair | ||
| CL2 (99.9900%) | Praxair | ||
| HBr (99.9950%) | Praxair | ||
| Ar (99.9990%) | Praxair | ||
| C2F6 (99.9990%) | Praxair | ||
| CHF3 (99.9950%) | Praxair | ||
| H2 (99.9950%) | Praxair | ||
| C2H2 (99.6000%) | Praxair | ||
| Equipment | Company | Catalog Number | Comments/Description |
| EVG 120 coater/developer | EVG | ||
| ASML PAS5500/80 waferstepper | ASML | ||
| SPTS Ωmega 201 plasma etcher | SPTS | Used for Si and metal etching | |
| SPTS Σigma sputter coater | SPTS | ||
| Novellus Concept One PECVD | LAM | ||
| Drytek 384T plasma etcher | LAM | Used for oxide etching | |
| CHA Solution e-beam evaporator | CHA | ||
| AIXTRON BlackMagic Pro CVD tool | AIXTRON | Carbon nanotube growth | |
| Philips XL50 scanning electron microscope | FEI | ||
| Tepla 300 | PVA TePla | Resist plasma stripper | |
| Avenger rinser dryer | Microporcess Technologies | ||
| Leitz MPV-SP reflecometer | Leitz | ||
| Renishaw inVia Raman spectroscope | Renishaw | ||
| Agilent 4156C parameter spectrum analyzer | Agilent | ||
| Cascade Microtech probe station | Cascade Microtech |
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