| 1. |
- Chen, Xi, et al.
(författare)
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Aged hydrogen silsesquioxane for sub-10 nm line patterns
- 2016
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 163, s. 105-109
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen silsesquioxane (HSQ) has been used as a negative tone resist in electron beam lithography to define sub-10 nm patterns. The spontaneous polymerization in HSQ usually called aging in this context, sets a restricted period of time for a vendor-warranted use in patterning such small features with satisfactory line-edge roughness (LER). Here, we study the effect of HSQ aging on sensitivity and LER by focusing on exposing line patterns of 10 nm width in various structures. The results show that the 10 nm lines are easily achievable and the LER of the patterned lines remains unaltered even with HSQ that is stored 10 months beyond the vendor-specified expiration date. However, an increasingly pronounced decrease with time of the threshold electron dose (D-th), below which the line width would become less than 10 nm, is observed. After the HSQ expiration for 10 months, the 10 nm lines can be manufactured by reducing D-th to a level that is technically manageable with safe margins. In addition, the inclusion of a prebaldng step at 220 degrees C to accelerate the aging process results in a further reduced D-th for the 10 nm lines and thereby leads to a shortened writing time. The time variation of D-th with respect to the vendor-specified production date of HSQ is found to follow an exponential function of time and can be associated to the classical nucleation-growth polymerization process in HSQ.
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| 2. |
- Collaert, N., et al.
(författare)
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Ultimate nano-electronics : New materials and device concepts for scaling nano-electronics beyond the Si roadmap
- 2015
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 132, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In this work, we will give an overview of the innovations in materials and new device concepts that will be needed to continue Moore’s law to the sub-10 nm technology nodes. To meet the power and performance requirements high mobility materials in combination with new device concepts like tunnel FETs and gate-all-around devices will need to be introduced. As the density is further increased and it becomes increasingly difficult to put contacts, spacers and gate in the available gate pitch, disruptive integration schemes such as vertical transistors and monolithic 3D integration might lead the way to the ultimate scaling of CMOS.
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| 3. |
- Jayakumar, Ganesh, et al.
(författare)
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Utilizing the superior etch stop quality of HfO 2 in the front end of line wafer scale integration of silicon nanowire biosensors
- 2019
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Ingår i: Microelectronic Engineering. - : Elsevier B.V.. - 0167-9317 .- 1873-5568. ; 212, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- Silicon nanowire (SiNW) biosensors have received a special attention from the research community due to its ability to detect a range of species. The nano feature size of the SiNW has been exploited to fabricate small, low-cost, robust, portable, real-time read-out biosensors. These sensors are manufactured by two methods – top-down or bottom-up. Instead of the bottom-up method, the top-down approach is widely used due to its compatibility with complementary metal-oxide semiconductor (CMOS) process and scope of mass production. However, in the top-down method, the post fabrication microfluidic channel integration to access the SiNW test site remains complex and challenging. Since the nanosensor is expected to operate in a bio environment, it is essential to passivate the metal electrodes while pathways have to be made to access the test site. In this paper, we present a relatively easier method to access the SiNW test site without employing complex microfluidic channels while achieving leakage free passivation of metal electrodes and preserving the integrity of the nanosensor. This is accomplished in the last step of the manufacturing process by employing a lithography mask and reactive ion etching (RIE). HfO 2 integrated crystalline silicon nanosensors are manufactured using novel top-down front end of line (FEOL) sidewall transfer lithography (STL) process. HfO 2 acts as an etch stop layer while performing RIE in the last step to access the sensor test site. The 100 mm wafer scale results of 20 nm × 60 nm × 6 μm (H x W x L) p-type nanosensors shows an average I on /I off ≥ 10 5 with maximum turn-on voltage of −4 V and uniform subthreshold slope of 70 mV/dec. In comparison with sensors encapsulated with SiO 2 , the HfO 2 integrated nanosensors were found to improve the threshold voltage variation by 50%. Based on this work, the HfO 2 integrated SiNW demonstrates good stability for biosensing application.
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| 4. |
- Liu, Qingbo, et al.
(författare)
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Effects of carbon pre-germanidation implant into Ge on the thermal stability of NiGe films
- 2015
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 133, s. 6-10
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effects of carbon pre-germanidation implant into Ge on the properties of NiGe films were systematically investigated. NiGe films with carbon pre-germanidation implant to doses varying from 0 to 6 x 10(15) cm(-2) were characterized by means of sheet resistance measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), cross-sectional transmission electron microscope (X-TEM) and secondary ion mass spectroscopy (SIMS). The presence of C atoms is proved to significantly enhance the thermal stability of NiGe by about 100 degrees C as well as to change the preferred orientations of polycrystalline NiGe. The homogenous redistribution of C atoms within NiGe films and the segregation of C atoms at the NiGe/Ge interface is responsible for the improved thermal stability of NiGe films.
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| 5. |
- Mardani, Shabnam, et al.
(författare)
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Influence of tantalum/tantalum nitride barriers and caps on the high-temperature properties of copper metallization for wide-band gap applications
- 2015
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 137, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- Electronic devices and circuits based on wide-band gap (WBG) semiconductors and intended for operation at temperatures significantly exceeding 300 degrees C are currently being developed. It is important that the adjunct metallization matches the high-temperature properties of the devices. In the case of the technologically important Cu metallization, the most frequently used cap and barrier layer materials are Ta, TaN and combinations of these. They stabilize the interconnects and prevent Cu from diffusing into the surrounding material. In this study, different combinations of Ta and TaN layers are evaluated electrically and morphologically after high-temperature treatments. The cap/Cu/barrier stack shows an appreciable increase in sheet resistance above 600 degrees C for the asymmetric combinations Ta/Cu/TaN and TaN/Cu/Ta. This degradation is shown to be closely related to a substantial diffusion of Ta across the Cu film and on to the TaN layer, where Ta1+xN forms. The symmetrical combinations Ta/Cu/Ta and TaN/Cu/TaN show only small changes in sheet resistance on even after anneals at 800 degrees C. A less pronounced Ta diffusion into the Cu film is found for the Ta/Cu/Ta combination. The experimental observations are interpreted in terms of Cu grain growth, Ta segregation in the Cu grain boundaries and morphological degradation of the Cu film.
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| 6. |
- Parfeniukas, Karolis, et al.
(författare)
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Improved tungsten nanofabrication for hard X-ray zone plates
- 2016
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 152, s. 6-9
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Tidskriftsartikel (refereegranskat)abstract
- We present an improved nanofabrication method of high aspect ratio tungsten structures for use in high efficiency nanofocusing hard X-ray zone plates. A ZEP 7000 electron beam resist layer used for patterning is cured by a second, much larger electron dose after development. The curing step improves pattern transfer fidelity into a chromium hard mask by reactive ion etching using Cl2/O2 chemistry. The pattern can then be transferred into an underlying tungsten layer by another reactive ion etching step using SF6/O2. A 630 nm-thick tungsten zone plate with smallest line width of 30 nm was fabricated using this method and characterized. At 8.2 keV photon energy the device showed an efficiency of 2.2% with a focal spot size at the diffraction limit, measured at Diamond Light Source I-13-1 beamline.
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| 7. |
- Qin, C., et al.
(författare)
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Study of sigma-shaped source/drain recesses for embedded-SiGe pMOSFETs
- 2017
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Ingår i: Microelectronic Engineering. - : Elsevier. - 0167-9317 .- 1873-5568. ; 181, s. 22-28
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the manufacturing process and formation mechanism study of sigma-shaped source/drain (S/D) recess in 28 nm node pMOSFETs and beyond have been presented. The mechanism of forming sigma-shaped recesses included a detailed analysis how to apply the dry and wet etching to shape the recess in a controlled way. The key factors in etching parameters were identified and optimized. Simulations of strain distributions in the channel region of the devices with selectively grown Si0.65Ge0.35 on different S/D recess shapes were carried out and the results were used as feedback to find out a trade-off between maximum strain in the channel region of the transistors and low short channel effect. Finally, guidelines for designing the shape of recess and for tuning the etching parameters for high mobility transistors have been proposed.
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| 8. |
- von Ahnen, Inga, et al.
(författare)
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Transfer of vertical nanowire arrays on polycaprolactone substrates for biological applications
- 2015
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 135, s. 52-56
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Tidskriftsartikel (refereegranskat)abstract
- We used two methods, namely stamping and printing, to transfer arrays of epitaxial gallium phosphide (Gap) nanowires from their growth substrate to a soft, biodegradable layer of polycaprolactone (PCL). Using the stamping method resulted in a very inhomogeneous surface topography with a wide distribution of transferred nanowire lengths, whereas using the printing method resulted in an homogeneous substrate topography over several mm(2). PC12 cells were cultured on the hybrid nanowire-PCL substrates realized using the printing method and exhibited an increased attachment on these substrates, compared to the original nanowire-semiconductor substrate. Transferring nanowires on PCL substrates is promising for implanting nanowires in-vivo with a possible reduced inflammation compared to when hard semi-conductor substrates are implanted together with the nanowires. The nanowire-PCL hybrid substrates could also be used as biocompatible cell culture substrates. Finally, using nanowires on PCL substrates would enable to recycle the expensive GaP substrate and repeatedly grow nanowires on the same substrate. (C) 2015 The Authors. Published by Elsevier B.V.
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| 9. |
- Wagner, S., et al.
(författare)
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Graphene transfer methods for the fabrication of membrane-based NEMS devices
- 2016
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Ingår i: Microelectronic Engineering. - : Elsevier. - 0167-9317 .- 1873-5568. ; 159, s. 108-113
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Tidskriftsartikel (refereegranskat)abstract
- Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane based nanoelectromechanical systems (NEMS). Here, three methods for direct transfer of chemical vapor deposited graphene onto pre-fabricated micro cavity substrates were investigated and analyzed with respect to yield and quality of the free-standing membranes on a large-scale. An effective transfer method for layer-by-layer stacking of graphene was developed to improve the membrane stability and thereby increase the yield of completely covered and sealed cavities. The transfer method with the highest yield was used to fabricate graphene NEMS devices. Electrical measurements were carried out to successfully demonstrate pressure sensing as a possible application for these graphene membranes.
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| 10. |
- Wang, Guilei, et al.
(författare)
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Study of SiGe selective epitaxial process integration with high-k and metal gate for 16/14 nm nodes FinFET technology
- 2016
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Ingår i: Microelectronic Engineering. - : Elsevier. - 0167-9317 .- 1873-5568. ; 163, s. 49-54
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the process integration of SiGe selective epitaxy on source/drain regions, for 16/14 nm nodes FinFET with high-k & metal gate has been presented. Selectively grown Si1-xGex (0.35 <= x <= 0.40) with boron concentration of 1 x 10(20) cm(-3) was used to elevate the source/drain of the transistors. The epi-quality, layer profile and strain amount of the selectively grown SiGe layers were also investigated by means of various characterizations. A series of prebaking experiments were performed for temperatures ranging from 740 to 825 degrees C in order to in situ clean the Si fins prior to the epitaxy. The results showed that the thermal budget needs to be limited to 780-800 degrees C in order to avoid any damages to the shape of Si fins but to remove the native oxide effectively which is essential for high epitaxial quality. The Ge content in SiGe layers on Si fins was determined from the strain measured directly by reciprocal space mappings using synchrotron radiation. Atomic layer deposition technique was applied to fill the gate trench with W using WF6 and B2H6 precursors. By such an AID approach, decent growth rate, low resistivity and excellent gap filling capability of W in pretty high aspect-ratio gate trench was realized. The as-fabricated FinFETs demonstrated decent electrical characteristics.
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