RTA Temperature Research Articles

Microstructure evolution of the Ir-inserted Ni silicides with additional annealing

Thermally-evaporated 10 nm-Ni/1 nm-Ir/(poly)Si structures were fabricated in order to investigate the thermal stability of Ir-inserted nickel silicide after additional annealing. The silicide samples underwent rapid thermal annealing at 300 ° C to 1200 ° C for 40 s, followed by 30 min annealing at the given RTA temperatures. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates, mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution x-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope were used to determine the cross-section structure and surface roughness. The silicide, which formed on single crystal silicon substrate with surface agglomeration after additional annealing, could defer the transformation of Ni(Ir)Si to Ni(Ir)Si2 and was stable at temperatures up to 1200 °C. Moreover, the silicide thickness doubled. There were no outstanding changes in the silicide thickness on polycrystalline silicon. However, after additional annealing, the silicon-silicide mixing became serious and showed high resistance at temperatures >700 °C. Auger depth profiling confirmed the increased thickness of the silicide layers after additional annealing without a change in composition. For a single crystal silicon substrate, the sheet resistance increased slightly due to the significant increases in surface roughness caused by surface agglomeration after additional annealing. Otherwise, there were almost no changes in surface roughness on the polycrystalline silicon substrate. The Ir-inserted nickel monosilicide was able to maintain a low resistance in a wide temperature range and is considered suitable for the nano-thick silicide process.

Microstructure evolution with RTA temperature in nano-thick (Ru or Au)-inserted nickel silicides

A 10 nm Ni/1 nm (Ru or Au)/30 nm poly-Si structure was fabricated on a gate-mimicking polycrystalline silicon substrate using a thermal evaporator and the thermal stability was examined. The silicide samples underwent rapid thermal annealing at temperatures ranging from 300 to 1100 °C for 40 s. The sheet resistance, phase, cross-sectional microstructure, chemical composition, and surface roughness of the silicide layers were measured using a four-point probe, high-resolution X-ray diffraction (HRXRD), transmission electron microscopy (TEM), auger electron spectroscopy (AES), and scanning probe microscopy (SPM), respectively. In the case of Ru-inserted nickel silicide, Ru inhibited the phase transformation of NiSi to NiSi 2, and extended the stable region to 1000 °C. TEM showed that a uniform and flat silicide had formed at 700 °C. However, as the temperature increased, silicide microstructures, which were interconnected to each other with a maze-like appearance, were observed due to NiSi grain agglomeration. On the other hand, AFM showed almost no changes in surface roughness. In the case of Au-inserted nickel silicide, the Au could defer the phase transformation (from NiSi) to NiSi 2, thereby extending the stable region to 900 °C. TEM revealed self-aligned agglomeration, in which the periodicity was controlled by the annealing temperature. A nano-thick, Ru-inserted nickel monosilicide thin film with a flat and uniform structure, and an extended stable region was suitable for use as a nano-thick gate. Moreover, it was possible to fabricate nickel silicide with self-aligned nano-thick microstructures by inserting a nano-thick Au layer.

Characteristics of Cobalt Films Deposited by Metal Organic Chemical Vapor Deposition Method Using Dicobalt Hexacarbonyl tert-Butylacetylene

Cobalt films were deposited by metal organic chemical vapor deposition (MOCVD) using C12H10O6(Co)2 (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) as the Co precursor and H2 reactant gas. The impurity content of the Co films was monitored as a function of the partial pressure of H2 reactant gas. The carbon and oxygen content of as-deposited Co films greatly decrease with the increase of H2 partial pressure, and at H2 partial pressure of 10 Torr and a substrate temperature of 150 °C were 2.8 at. % and less than 1 at. %, respectively. As the H2 partial pressure increased, carbon and oxygen content decreased markedly. Excellent conformality of Co film over 80% was achieved on a patterned wafer with aspect ratio of 15:1, 0.12 µm wide and 1.8 µm deep. The phase transition was analyzed with X-ray diffraction (XRD) depending on RTA temperature. CoSi was observed at 500 °C annealing, and was transformed to CoSi2 at 600 °C annealing. In addition, Auger electron spectroscopy (AES) data showed a 1:2 atomic ratio of Co:Si in the CoSi2 layer.

Challenges in Nickel Platinum Silicide Wet Etching for Sub-65nm Device Technology

The wet stripping of unreacted Ni(Pt) and TiN using Aqua Regia, after Ni(Pt) silicidation, was evaluated in this study. It was observed that Aqua Regia attacked Ni(Pt) silicide formed at low annealing temperatures. Resultant degradation of silicided sheet resistance of narrow linewidth structures would outweigh the benefits of improved reverse linewidth effect and junction leakages. By using an optimum RTA temperature and Aqua Regia duration, an operating window could be established for low temperature Ni(Pt) silicidation process.

Properties of nickel-cobalt composite silicides by thermal annealing of Ni1−xCox (x=0.2, 0.5, and 0.8) alloy thin films on silicon and polysilicon substrates

10 nm-Ni1−xCox (x=0.2, 0.5, and 0.8)/p-Si(100)(or poly crystalline Si) was thermally annealed using rapid thermal annealing for 40 s at 600–1100°C. The annealed film structures developed into NiCoSix, and the resulting changes in sheet resistance, microstructure, and composition were investigated using a four-point probe, a scanning electron microscope, a field ion beam, an X-ray diffractometer, and an Auger electron spectroscope. The final thickness of NiCoSix formed on single-crystal silicon was approximately 12.64nm, and it maintained its sheet resistance below 20 Ω/sq. during the silicidation annealing at 1100°C. The NiCoSix formed on polysilicon had a thickness of 35.04nm, and its low resistance was maintained up to 900°C. Additional annealing of silicides at the given RTA temperature for 30 min resulted in a drastic increase in sheet resistance. We identified Ni3Si2 and a NiSi phase at 700°C and 1000°C for single-crystal silicon substrates. Moreover, Ni3Si2, NiSi, and CoSi2 phases were stable at 700°C, and then NiSi2 and Ni3Si2 became stable for polycrystalline silicon substrates at 1000°C. When the amount of Co was 80%, only a Ni3Si2 phase was confirmed at 700°C and 1000°C in both the single and polycrystalline substrates. With less Co (Co=0.2, 0.5), Ni3Si2, NiSi, and CoSi2 phases were observed at 700, and Ni3Si2 and NiSi2 phases were observed at 1000°C. Cobalt also improved thermal stability of the silicides formed on the polysilicon gate, but this enhancement was lessened due to the silicon mixing during high temperature diffusion. In conclusion, the proposed nickel cobalt composite silicides formed from the nano-thick alloy films may be superior to conventional nickel monosilicides due to improved thermal stability.

Correlation between structural changes and luminescent properties of ZnMgS:Mn thin film phosphor with annealing temperature

With varying rapid thermal annealing temperature, luminescent properties of Zn 0.75 Mg 0.25 S :Mn thin film deposited by RF-magnetron sputtering technique were investigated. Although all samples were deposited from identical source composition, it was found that a main peak wavelength of photoluminescence of Zn 0.75 Mg 0.25 S :Mn depended on RTA temperatures and it shifted toward shorter wavelength upon the increase of RTA temperature. The same dependence of wavelength on RTA temperature was also observed in cathodoluminescence as well as electroluminescence measurements. It is noticeable that Zn 0.75 Mg 0.25 S :Mn thin film phosphor in this study showed more reddish emission than those of the previous studies. It was revealed that changes of the luminescent properties were originated from structural changes in Zn 0.75 Mg 0.25 S :Mn thin film phosphor from cubic to hexagonal phases using X-ray pole figure mapping, and the growing up of hexagonal phase mainly caused cracks and porous morphology on the surface of thin films. It is suggested that the phase transition would be the origin of luminescent property changes with respect to rapid thermal annealing temperature.

Analytical Modeling of the Interaction of Vacancies and Oxygen for Oxide Precipitation in RTA Treated Wafers

We have investigated the impact of RTA induced vacancy supersaturation on oxide precipitation based on as much as possible experimental and theoretical values. Oxygen precipitation after RTA processing was found to be controlled by the initial concentration of interstitial oxygen in a sixth power dependency and frozen vacancies just in a cubic dependency. The formation of tensile strained nVO2 clusters seems to be the favored process for coherent nucleation of oxide precipitates. The reduction of interstitial oxygen can be accurately modeled for the temperature range from 1150 {degree sign}C to 1250 {degree sign}C using Ham's theory for precipitate growth and an empirical relation based on nucleation of oxide precipitates by agglomeration of VO2 complexes. During RTA treatments at temperatures {greater than or equal to} 1300 {degree sign}C vacancies seem to be consumed by other processes. Below RTA temperatures of 1150 {degree sign}C, oxide precipitation is dominated by shrunken as-grown precipitate nuclei because as-grown nuclei can be dissolved only at RTA temperatures {greater than or equal to} 1150 {degree sign}C.

Electrochemical Characteristics of Silicon-Doped Tin Oxide Thin Films for Application of Lithium Secondary Micro-Battery Anode

The SnO2 thin films doped with traces of silicon were deposited on the p-type (100) Si substrate by the r.f. magnetron sputtering method from Sn0.94Si0.06O2 target for the application of lithium secondary micro-battery anode. The crystal orientation of tin oxide thin films was changed from (110) to (101) or (211) with the increase of the substrate temperature. Contrarily, the crystallization of tin oxide thin films, which were heat-treated in the RTA furnace from 450°C to 650 °C under the O2 ambient, did not show significant difference. As a result of the electrochemical analysis, we could see that the irreversible capacity was reduced during the first discharge/charge cycle. Capacity increased with the increase of substrate temperature, but decreased with the increase of RTA temperatures. In particular, the maximum value of reversible capacity was 700mAh/g under the deposition condition of the substrate temperature of 300°C and the Ar:O2 ratio of 7:3.

InGaAsN on GaAs (1 1 1)B for telecommunication laser application

In this work we present the GaAs (1 1 1)B as a candidate to develop laser devices working on the second and third fiber optic windows. We show that the ions coming from the radiofrequency plasma cell reduce the optical emission dramatically. This damage can be reduced if a magnetic field is used during the growth of the InGaAsN quantum wells, reducing the ion density impinging on the surface and improving therefore the optical quality. In addition, a lower optimum RTA temperature was found for samples with a lower ion concentration, implying a better structural quality. Finally, a lower blueshift after annealing was also found. The higher optical and structural quality of the samples grown with the magnetic field, the lower optimum RTA temperature and the reduced blueshift after anneling offer interesting perspectives to the development of long-wavelength devices using misoriented GaAs (1 1 1)B substrates.

TSUPREM-4 based modeling of boron and carbon diffusion in SiGeC base layers under rapid thermal annealing conditions

Boron diffusion in SiGeC layers is studied under different actual process conditions, with RTA temperatures in the range 1020–1100 °C. Model parameters for the process simulator TSUPREM-4 (Tsuprem-4 computer code from Avant! Corporation) have been derived for equilibrium and transient enhanced diffusion conditions. The model and model parameters have been validated for a 0.13 μm BiCMOS process.

Investigation of GaN LED with Be-implanted Mg-doped GaN layer

We report the electrical and optical characteristics of GaN light emitting diode (LED) with beryllium (Be) implanted Mg-doped GaN layer. The p-type layer of Be-implanted GaN LED showed a higher hole carrier concentration of 2.3 × 10 18 cm −3 and low specific contact resistance value of 2.0 × 10 −4 Ωcm 2 than as-grown p-GaN LED samples without Be-implantation. The Be-implanted GaN LEDs with InGaN/GaN MQW show slightly lower light output (about 10%) than the as-grown GaN LEDs, caused by the high RTA temperature annealing process.

Diffusion barrier cladding in Si/SiGe resonant interband tunneling diodes and their patterned growth on PMOS source/drain regions

Si/SiGe resonant interband tunnel diodes (RITDs) employing /spl delta/-doping spikes that demonstrate negative differential resistance (NDR) at room temperature are presented. Efforts have focused on improving the tunnel diode peak-to-valley current ratio (PVCR) figure-of-merit, as well as addressing issues of manufacturability and CMOS integration. Thin SiGe layers sandwiching the B /spl delta/-doping spike used to suppress B out-diffusion are discussed. A room-temperature PVCR of 3.6 was measured with a peak current density of 0.3 kA/cm/sup 2/. Results clearly show that by introducing SiGe layers to clad the B /spl delta/-doping layer, B diffusion is suppressed during post-growth annealing, which raises the thermal budget. A higher RTA temperature appears to be more effective in reducing defects and results in a lower valley current and higher PVCR. RITDs grown by selective area molecular beam epitaxy (MBE) have been realized inside of low-temperature oxide openings, with performance comparable with RITDs grown on bulk substrates.

Low temperature deposition of srbi2ta2o9 by using modified sol-gel solution

Sol-gel solutions were synthesized by using various alkoxides of polyhydric alcohol, carboxylate and stabilizer. Stability of modified sol-gel solution was good enough to keep its properties after at least three months although that of ordinary sol-gel solution is not good. SBT films were fabricated on Pt(200nm)/Ti(20nm)SiO2(500nm)/Si substrate at under 700°C by using modified sol-gel solution. Range of drying temperature was 200 to 400°C and that of RTA was 550 to 700°C. At high drying temperature, decrease of crystallinity for SBT films was observed accompanied by nucleation of Sr carbonate. On the other hand, SBT film dried at under 250°C and crystallized at 700°C shows high crystallinity of layer perovskite. SBT film derived from conventional sol-gel solution used to show strong crystal orientation of c-axis. In case of modified sol-gel solution, RTA temperature and amount of added stabilizer influenced crystal orientation of film. So it was possible that to control crystal orientation of SBT films by adjust RTA condition and amount of stabilizer. Stability of sol-gel solution and property of SBT films were influenced by component of solvent, electric properties of SBT films especially I-V property were improved. Using low temperature deposition process at 650°C, SBT films derived from modified sol-gel solution show superior ferroelectric properties to SBT thin films derived from conventional MOD solution.

Electrical properties of hafnium oxide gate dielectric deposited by plasma enhanced chemical vapor deposition

Hafnium oxide thin films were deposited at 300°Con p-Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD). The gate dielectric formed by PECVD was HfO2/SiO2/Si structure. The thickness of the HfO2 thin films decreases with increasing. RTA temperature because of its high density. The Pt/HfO2/SiO2/Si structure showed accumulation, depletion and inversion. After the RTA treatment, the capacitances of the Pt/HfO2/SiO2/Si structures were increased because, the thickness of HfO2 thin film decreased. The counterclockwise hysteresis of the C-V curve is believed to be due to charge trapping at the negative gate bias. Hysteresis of as-deposited gate dielectric is quite large, but rapidly decreases with increasing RTA temperature. The increase in leakage current density by the O2 anneal seems to be related to the grain growth of the HfO2 thin film. After forming gas annealing, the electrical properties did not largely improve.

Doping process issues for Sub-0.1 μm generation MOSFETs

ABSTRACTTo meet the market demands for higher performance LSIs, traditional scaling has been aggressively pursued and has enjoyed great success over the 0.1-μm generations. To maintain continued growth of CMOS performance beyond the 0.1-μm generation, key issues originating from traditional scaling are addressed from the viewpoint of the doping processes (channel engineering, high-activation, and gate- electrode structure) in this paper.To meet the acceleration in gate-length miniaturization, short-channel effects must be suppressed at a low threshold voltage by using aggressive channel engineering. A channel-impurity profile must be optimized two-dimensionally, not uniformly or one-dimensionally. Channel engineering using tilted-channel implantation (TCI) with Indium is demonstrated.Traditional scaling results in large variations of threshold voltage due to the statistical-impurity variation in a channel region. We studied the effect of the above channel engineering on threshold voltage fluctuation caused by a statistical- dopant variation by measurement and simulation. It is reported that the two-dimensionally optimized channel profile enhances threshold-voltage fluctuation even if the implantation process variation is negligible.As CMOS device scales, reduction of parasitic resistance becomes very important for a high performance operation. Resistance at extension egde and contact resistance at silicide-Si interface are dominant factors.The traditional approach is to use a higher RTA temperature and a shorter RTA time. The ultimate RTA is laser annealing. We will demonstrate the laser annealing process with an ultra-low contact resistance of 4 × 10−8 Ω-cm2.By integrating the above technologies, ultra-thin gate insulators, and reduction in gate to source/drain overlap length, we can establish front-end process for sub-0.1 μm generations.

Interface quality study of ECR-deposited and rapid thermal annealed silicon nitride Al/SiNx:H/InP and Al/SiNx:H/In0.53Ga0.47As structures by DLTS and conductance transient techniques

In this article, we study the influences of the rapid thermal annealing temperature and dielectric composition on the electrical characteristics of ECR-deposited silicon nitride SiNx:H–InP and SiNx:H–InGaAs interfaces. C–V, deep level transient spectroscopy (DLTS) and conductance transient analysis have been applied. As for InP cases, DLTS results reveal that rapid thermal annealing application increases interfacial state density. In contrast, transient conductance measurements show that disorder induced gap-state (DIGS) damage density diminishes when RTA is applied. So, we can conclude that RTA treatments take out the insulator damage to the interface. In the InGaAs-n cases, we have observed that DIGS damage evolution with RTA temperature is opposite to the interfacial state density. This behaviour seems to suggest some temperature activated defect exchange between the insulator and the interface. Finally, as for the insulator composition influence on the interface quality of the InGaAs-n samples, DLTS results suggest that the intermediate x values (1.43 and 1.50) provide better interfaces than extreme x values. Conductance transient measurements add complementary information: insulator damage increases when x increases. Hence, x=1.43 seems to be the best choice to improve the overall interface quality.

Factors affecting Ge nanocrystal size in co-sputtered Ge+SiO2films

AbstractThe high resolution transmission electron microscopy and Raman spectroscopy results of germanium nanocrystals embedded in SiO2 synthesized by rapid thermal processing (RTA) have been presented. From the results of samples with different Ge concentrations, it was concluded that there is a narrow window in the Ge concentration that can produce nanocrystals. We also showed that it is possible to vary RTA duration or temperature to produce Ge nanocrystals with varying sizes. Our results therefore suggest that it is possible to utilize (i) annealing duration and; (ii) temperature to tune crystal sizes for optoelectronic applications.

Effect of Nitrogen Implants on Boron Transient Enhanced Diffusion

AbstractThe effect of nitrogen implants on boron transient enhanced diffusion was studied for nitrogen-only, boron-only, and boron plus nitrogen implants. A boron buried layer was used as a detector for interstitial supersaturation in the samples. Boron dose ranged from 1×1014 to 1×1015 cm−2 and N2+ dose from 5×1013 and 5×1014 cm−2. The energies were chosen such that the location of the nitrogen and boron peaks matched. After the implants, RTA and low temperature furnace anneals were carried out. The diffusivity enhancements were extracted from the buried layer profiles by simulation. Nitrogen-only implants were found to cause significant enhanced diffusion on the buried boron layer. For lower doses, the enhancement of the nitrogen implant is about half as that of boron whereas the enhancements are equal at higher doses. Nitrogen coimplant with boron increases the transient enhanced diffusion of boron at low boron doses, which implies that nitrogen does not act as a strong sink for excess interstitials unlike carbon. At high boron doses, nitrogen co-implant does not significantly change boron diffusion. Sheet resistance measurements indicate that low nitrogen doses do not affect the activation of boron whereas high nitrogen doses either reduce the activation of boron or the mobility of the holes.

The influence of post annealing on oxide charge-to-breakdown in tungsten polycide gate technology

The dependence of Q BD on the combined post annealing conditions of RTA and FA in the tungsten polycide gate technology has been experimentally investigated. In the case of RTA to be processed after FA, Q BD is controlled by the amount of fluorine diffused into the oxide, and then it is decreasing as increasing RTA temperature and time. However, in the vice-versa case, Q BD shows the poor characteristics because of the effect of lightly activated polysilicon. Based on these experimental results, the combined post annealing with FA/RTA sequence is useful to obtain the high Q BD performance.

Characterization of Ni- and Ni(Pt)-Silicide Formation on Narrow Polycrystalline Si Lines by Raman Spectroscopy

ABSTRACTThe formation and thermal stability of Ni- and Ni(Pt) silicide on narrow polycrystalline Si (poly-Si) lines have been investigated using the non-destructive micro-Raman technique. The presence of Ni or Ni(Pt)Si on poly-Si lines with linewidths ranging from 0.5 gtm to 0.25 μm has been monitored by a distinct Raman peak at around 215 cm−1. Ni(Pt)Si was clearly identified to be present up to a RTA temperature of 900°C on narrow poly-Si lines as compared to pure NiSi which was found only up to 750°C. Raman scattering from the 100×100 μm2 poly-Si pads showed the formation of NiSi2 at 750°C for pure Ni-salicidation and 900°C for Ni(Pt)-salicidation respectively. The difference in the stability of NiSi on the poly-Si pads and lines is discussed in terms of agglomeration, inversion and/or nucleation of NiSi2that could be due to difference in nucleation sites and/or stress. In addition, a correlation between the line sheet resistance and the presence of Ni silicide was found using micro-Raman mapping along single poly-Si lines.