Recovery Of Implantation Damage Research Articles

Impact of post-ion implantation annealing on Se-hyperdoped Ge

Hyperdoped germanium (Ge) has demonstrated increased sub-bandgap absorption, offering potential applications in the short-wavelength-infrared spectrum (1.0–3.0 μm). This study employs ion implantation to introduce a high concentration of selenium (Se) into Ge and investigates the effects of post-implantation annealing techniques on the recovery of implantation damage and alterations in optical properties. We identify optimal conditions for two distinct annealing techniques: rapid thermal annealing (RTA) at a temperature of 650 °C and ultrafast laser heating (ULH) at a fluence of 6 mJ/cm2. The optimized ULH process outperforms the RTA method in preserving high doping profiles and achieving a fourfold increase in sub-bandgap absorption. However, RTA leads to regrowth of single crystalline Ge, while ULH most likely leads to polycrystalline Ge. The study offers valuable insights into the hyperdoping processes in Ge for the development of advanced optoelectronic devices.

Optical activation of implanted lanthanoid ions in aluminum nitride semiconductors by high temperature annealing

Lanthanoid (Ln)-doped aluminum nitride (AlN) semiconductors are one candidate for optoelectric devices and single photon sources, although their optical properties are less understood. We clarify the room temperature optical properties of Ln ion implanted single crystal AlN semiconductors and their changes upon thermal annealing by up to 1700 °C. Photoluminescence (PL), cathodoluminescence (CL), and time-resolved PL for praseodymium (Pr), europium (Eu), and neodymium (Nd) ion implanted AlN are analyzed. Recovery of implantation induced damages and thermal diffusion of implanted Ln ions by thermal annealing are also investigated. Our systematic studies reveal that there is a trade-off between optical activation of implanted Ln ions due to recovery of implantation damage and deactivation (quenching) due to complex formation and aggregation of Ln ions. The PL intensity of implanted Pr ions increases with increasing annealing temperature in the case of high-dose implantation (above 1020 cm-3), whereas it rather decreases in the case of low-dose implantation (below 4 × 1019 cm-3). However, the PL intensity is significantly reduced after annealing at 1700 °C in both cases, indicating that the quenching factor is dominant in this temperature range.

Electronic Structure and Optical Absorption in Gd‐Implanted Silica Glasses

The electronic structure and optical properties of silica glass implanted with Gd‐ions by the pulsed implantation technique are studied. Experimental XPS data combined with the theoretical density functional theory (DFT)‐modeling establish the most probable scenarios for Gd‐embedding at the interstitial and substitutional positions in silica before and after thermal annealing. The optical absorption spectra are analyzed within two spectral regions of direct interband transitions and exponential Urbach tails. The influence of both radiation and thermal treatment on the overall structural disorder of host‐matrix is determined using fundamental optical parameters (band gap, phonon energy). The local atomic displacements caused by the implantation damage and thermal recovery of host‐structure for as‐implanted and annealed samples are quantitatively estimated.

Comprehensive Characterization of Dual Implanted Silicon after Electrical Activation Annealing

Phosphorous (P+ 1.0 MeV, 4.0 x 1013 cm-2) and boron (B+ 10 keV, 3.0 x 1014cm-2) implanted p--Si(100) wafers were prepared to study electrical activation and dopant diffusion properties during thermal annealing. Dual implanted Si wafers were annealed for a wide range of annealing conditions (350-800oC, 60-150s) in a commercially available hot wall-based, rapid thermal annealing (RTA) system. Systematic change of sheet resistance was measured in the dual implanted wafers annealed under different RTA conditions. P and B depth profiles measured by secondary ion mass spectroscopy (SIMS) did not show significant change in all RTA conditions. Room temperature photoluminescence (RTPL) spectra and Raman spectra were measured from all wafers under various excitation wavelengths (650 and 785 nm for RTPL and 363.8, 441.6, 457.9, 488.0 and 514.5 nm for Raman). RTPL spectra showed large variations in intensity and wavelength distribution corresponding to the resulting sheet resistance and RTA conditions. Raman spectra showed gradual increase of intensity and change of Raman peak positions and FWHM at the RTA temperatures for implant damage recovery and electrical activation of dual implanted Si wafers.

Comprehensive Characterization of Dual Implanted Silicon after Electrical Activation Annealing

Formation of low resistivity junctions is essential for fabricating high performance devices with advanced device modes. Significant effort has been expended, industry wide, to develop low resistivity junctions, over the years. However, the understanding of implant activation and implant damage recovery process is not sufficient. Development of noncontact implant residual damage monitoring techniques would be beneficial in process development for advanced node devices. In this study, we have investigated the effect of annealing temperature and time on the sheet resistance (Rs) of dual (P+ 1.0MeV, 4.0 x 1013 cm-2 + B+ 10keV, 3.0 x 1014cm-2) implanted p--Si(100) wafers using a single wafer furnace-based (hot wall) rapid thermal annealing (RTA) system over a wide range of annealing conditions (350-800oC, 60-150s). Room temperature photoluminescence (RTPL) spectra were measured from all wafers under two different excitation wavelengths (650 and 785 nm) for additional clues on electrical properties of pn junctions, which cannot be obtained from the Rs measurements. Multiwavelength (457.9, 488.0 and 514.5 nm) Raman characterization was done on all wafers for additional insights on the degree of residual lattice damage, after RTA, under different conditions. After all on wafer measurements were completed, secondary ion mass spectroscopy (SIMS) dopant (P and B) depth profiling was done to assess dopant diffusion during the annealing process.Rs values showed strong and systematic change with RTA temperature and time, as expected. RTPL spectra also showed large variations in intensity and wavelength distribution corresponding to the RTA temperature and time. Multiwavelength Raman characterization results showed gradual increase of intensity with the RTA temperature. Three regions of different Raman shift values, corresponding to the Si lattice stress and possibly the degree of residual implant damage, were also noted. SIMS P and B depth profiles did not show significant changes. Correlation among characterization results from various techniques and RTA conditions will be presented.

Paper] Investigation of Implantation Damage Recovery using Microwave Annealing for High Performance Image Sensing Devices

We propose a novel annealing technique in order to improve the dark characteristics for CMOS image sensor without deteriorating the transistor characteristics. Microwave annealing (MWA) has been studied as an alternative annealing technique for diffusion-less dopant activation and implantation damage recovery in advanced CMOS technology. We employed MWA technique in order to recover crystalline defects in CMOS image sensor (CIS) process. We demonstrate that MWA can be implemented a low thermal budget to obtain the effect of repairing the ion-implantation damage equivalent to conventional furnace annealing (FA). MWA can repair the process damage without transistor performance degradation by additional thermal treatment. MWA is promising technique for repairing crystalline defects in high performance image sensing devices with high frame rate, low power and excellent dark characteristics..

Surface Heat Treatment of Silicon Wafer Using a Xenon Arc Lamp and Its Implant Activation Applications

A surface heat-treatment method for semiconductor wafers using a xenon arc lamp is described. High absorption coefficients of silicon wafers in ultra violet (UV) region and short process time made selective surface heating possible. The surface melting of entire 150 mm diameter Si wafers was demonstrated in less than 2 s at a lamp power of 15 kW. By focusing UV light into a limited area on Si wafer surface, surface melting of a selectively exposed area was demonstrated at a much lower lamp power. The surface temperature ramp rate is estimated to be on the order of 1000°C/s. Si wafers, with various implanted species (P+, As+, B+ and BF2+) and energies (1 keV–70 keV), were annealed for implant damage recovery and electrical activation using the Xe lamp under different scanning speeds. Sheet resistance and secondary ion mass spectroscopy (SIMS) depth profiling measurement results from the scanning rapid thermal annealing (RTA) successfully demonstrated the feasibility of the technique in semiconductor RTA processing applications. Electrical activation with desired levels of dopant diffusion can be achieved by optimizing process variables such as lamp power, distance between the lamp and Si wafer, area of light exposure and scanning speed.

Liquid Phase Epitaxy (LPE) Formation of Localized High Quality and Mobility Ge & SiGe by High Dose Ge-Implantation with Laser Melt Annealing for 10nm and 7nm Node CMOS Technology

We investigated using high dose (5E16/cm2) Ge beam-line ion implantation in combination with laser melt annealing as an alternative to Ge-epi by CVD to form high quality single crystal Ge-epilayer by LPE (liquid phase epitaxy) that is very uniform, thin 10-25nm and localized for high mobility Ge-channels. The implant resulted in 7nm amorphous Ge deposition by a method called dose controlled deposition (DCD). A 515nm laser was used to vary the melt depth from 9nm to 500nm based on laser anneal pulse duration and power level. Ellipsometer was used to measure the surface amorphous layer thickness while therma-wave (TW) analysis was used to monitor Ge implant damage recovery after LPE. SIMS depth profiles showed Ge surface concentration varied from 100% down to 2% based on the laser melt depth. X-TEM analysis showed the transformation of deposited amorphous Ge surface layer to single crystal Ge after laser melt and LPE. Sb implantation at two dose levels of 3E15/cm2 and 3E13/cm2 was used to examine laser melt annealing effects on n-type dopant activation and electron mobility in Ge. Special Hx-probe tips on the 4PP system was required to measure sheet resistance and CAOT/DHE method was used for Differential Hall Effect measurements.

Ion dose and anneal temperature dependent studies of silicon implanted Al xGa 1−xN

Electrical and optical activation studies of Al xGa 1−xN ( x = 0.11 and 0.21) implanted with silicon were made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1 × 10 14 to 1 × 10 15 cm −2 at room temperature. The implanted samples were subsequently annealed from 1100 to 1300 °C for 20 min in a nitrogen environment. A maximum electrical activation efficiency of 91% was obtained for the Al 0.11Ga 0.89N implanted with the highest dose of 1 × 10 15 cm −2 even after annealing at 1150 °C. 100% activation efficiencies were successfully obtained for the Al 0.21Ga 0.79N samples after annealing at 1300 °C for both doses of 5 × 10 14 and 1 × 10 15 cm −2. The mobility of the Si-implanted Al xGa 1−xN increases with annealing temperature, and the highest mobilities are 109 and 98 cm 2/V·s for Al 0.11Ga 0.89N and Al 0.21Ga 0.79N, respectively. The cathodoluminescence (CL) spectra for all the samples exhibited a sharp neutral-donor-bound exciton peak, and the CL intensity increases with annealing temperature, indicating successive improved implantation damage recovery as the annealing temperature is increased. These results provide the optimum annealing conditions for activation of implanted Si ions in Al xGa 1−xN.

Ion implantation damage recovery in GaN

We present a method of ion implantation doping of GaN, which permits reduced residual damage. The method consists of performing implantation in several steps with annealing between each step. Residual damage was analyzed by RBS/channeling and compared to a traditional implantation and annealing procedure. Better lattice recovery is clearly achieved using the alternating implantation and annealing approach. We attribute the efficient recovery to smaller damage amounts introduced during each implantation step, as well as to suppression of secondary defect formation.

Structural and optical characterization of Si-implanted Al 0.18Ga 0.82N

Both structural and optical activation studies of Si-implanted Al 0.18Ga 0.82N have been made as a function of anneal temperature by using the x-ray rocking curve measurements and photoluminescence (PL) and time-resolved PL (TRPL) measurements. The full width at half maximum values of both (002) and (102) direction ω -rocking curves for the Si-implanted Al 0.18Ga 0.82N samples decrease as the anneal temperature increases from 1150 to 1250 ∘C. The peak widths of the rocking curves for the as-implanted sample are much broader than those for the Si-implanted and annealed samples, indicating the implantation damage recovery after high temperature anneal. With increasing anneal temperature, the PL peak intensity increases and the PL decay becomes slower. The increase of PL intensity and recombination rate is attributed to both an increase of Si-donor activation and lattice damage recovery. These PL and x-ray results are very consistent with the results of anneal temperature-dependent electrical activation study.

The evolution of the ion implantation damage in device processing

In this article the phenomenology related to the mechanisms of defect generation in Shallow Trench Isolation (STI) processes is discussed, and the role of the structure pattern is investigated. Defect formation is studied by plan and cross TEM analyses of wafers with different boron doses and after annealing at various temperatures. In addition, to obtain a wider statistics our analysis was extended by electrical measurements of defect-sensitive structures. It is shown that a modification of the STI flow suppresses the main mechanism of mechanical stress accumulation, hence stress-induced defects are eliminated. However, this approach is found to be critical from the point of view of the implantation damage recovery, specifically for what concerns the implantations carried out before the trench etch. This result can be explained by the role of the silicon surface in reducing the point defect excess generated in the implantation. As a consequence, in this example the presence of the STI structure is beneficial, in that it assists in annealing implantation-related defects. An attempt is also presented to model the evolution of implantation-induced defects by a Kinetic Monte Carlo code. The calculation results are promising, though the capabilities of the model are limited by the computation time.

Implantation damage recovery and carrier activation studies of Si‐implanted Al 0.18 Ga 0.82 N by temperature dependent Hall‐effect measurements

N-type activation studies of Si-implanted Al0.18Ga0.82N have been made as a function of anneal temperature and ion dose to obtain maximum possible activation efficiency. Nearly 100 and 95% electrical activation efficiencies were obtained for Si-implanted Al0.18Ga0.82N with doses of 5x1014 and 1x1015 cm–2 and annealing at 1250 and 1200 oC for 25 min, respectively. The room temperature sheet resistivity decreases from 528 to 196 Ω/square with increasing anneal temperature from 1150 to 1250 oC for a dose of 5x1014 cm–2. Both sheet carrier concentration (activation efficiency) and mobility increase with anneal temperature, indicating an improved implantation damage recovery with anneal temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrical and optical activation studies of high dose Si-implanted Al 0.18Ga 0.82N

Both electrical and optical activation studies of Si-implanted Al 0.18Ga 0.82N have been made as a function of anneal time and anneal temperature to obtain maximum possible electrical activation efficiency. Silicon ions were implanted at 200 keV with doses of 5×10 14 and 1×10 15 cm −2, and the samples were annealed from 1100 to 1250 ∘C for 5–25 min with a 500 Å thick AlN cap in a nitrogen environment. The electrical activation efficiency and Hall mobility increase with anneal time and anneal temperature. Nearly 100 and 95% electrical activation efficiencies were obtained for Si-implanted Al 0.18Ga 0.82N with doses of 5×10 14 and 1×10 15 cm −2 and annealing at 1250 and 1200 ∘C for 25 min, respectively. The photoluminescence measurements show an excellent implantation damage recovery after annealing at these optimum anneal conditions, showing a strong near band emission. These optical results correlate well with the electrical results.

Optical activation of Eu ions in nanoporous GaN films

A systematic optical activation study of Eu-implanted nanoporous GaN films has been carried out as a function of ion dose and annealing temperature. The nanoporous GaN films are prepared by photoelectrochemical etching of n-type GaN films in HF-based electrolyte. Eu ions are implanted in both n-type GaN and n-type porous GaN films at 200keV with doses ranging from 5×1014to5×1015cm−2. For the implantation damage recovery and optical activation of Eu3+ ions, rapid thermal annealing is performed in the temperature range of 900–1200°C under nitrogen ambient. The surface morphology of implanted porous GaN after different processing steps is characterized by scanning electron microscopy and the results show that porous morphology remains uniform even after ion implantation and high temperature processing. Microphotoluminescence and micro-Raman techniques have been used to investigate the optical properties of these Eu-implanted nanoporous films. Postimplantation annealing of both as-grown GaN and porous GaN films leads to the observation of strong photoluminescence (PL) peak around 622nm, which is associated with the D05–F27 intraionic transition of Eu3+ ions. We have observed that PL intensity of Eu-related luminescence peaks increases with annealing temperature up to 1100°C. In addition, due to efficient light extraction by surface nanostructuring, Eu-implanted porous GaN films show much stronger luminescence when compared to Eu-implanted as-grown GaN. Raman spectral analyses also indicate the optimum annealing condition for the implantation damage recovery and the compressive stress state in the Eu-implanted films.

Electrical characterization of Si-ion implanted AlxGa1-xN annealed at lower temperatures

Electrical activation studies of Si-implanted Al x Ga 1-x N (x = 0.1 and 0.18) grown on sapphire substrate have been made as a function of anneal time, anneal temperature, and ion dose. Silicon implantation was done at room temperature with a dose ranging from 5 x 10 13 to 5 x 10 15 cm -2 at 200 keV. The samples were proximity cap annealed from 1100 to 1250 °C for 5-40 min with a 500 A-thick AlN cap in a nitrogen environment. The electrical activation efficiencies of 84% and 75% were obtained for the Al 0.1 Ga 0.9 N after annealing at 1200 °C for 40 min for a dose of 5 × 10 13 and 1 × 10 14 cm -2 , respectively. For the Al 0.18 Ga 0.82 N, nearly 100% activation for a dose of 5 × 10 14 cm -2 and 94% for a dose of 1 x 10 15 cm -2 were achieved after annealing at 1250 °C and 1200 °C for 20 min, respectively. Both the activation efficiency and mobility increase with anneal time and anneal temperature, indicating an improved implantation damage recovery. The highest mobility obtained at room temperature is 89 cm 2 /Vs for the Al 0.1 Ga 0.9 N samples having doses of 5 × 10 13 and 1 x 10 14 cm -2 and annealed at either 1200 °C for 40 min or 1250 °C for 20 min.

Electrical and optical characterization studies of lower dose Si-implanted AlxGa1−xN

Electrical and optical activation studies of lower dose Si-implanted AlxGa1−xN (x=0.14 and 0.24) have been made systematically as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1×1013 cm−2 to 1×1014 cm−2 at room temperature. The samples were proximity cap annealed from 1,100°C to 1,350°C with a 500-A-thick AlN cap in a nitrogen environment. Nearly 100% electrical activation efficiency was obtained for Al0.24Ga0.76N implanted with a dose of 1 × 1014 cm−2 after annealing at an optimum temperature around 1,300°C, whereas for lower dose (≤5×1013 cm−2) implanted Al0.24Ga0.76N samples, the electrical activation efficiencies continue to increase with anneal temperature up through 1,350°C. Seventy-six percent electrical activation efficiency was obtained for Al0.14Ga0.86N implanted with a dose of 1 × 1014 cm−2 at an optimum anneal temperature of around 1,250°C. The highest mobilities obtained were 89 cm2/Vs and 76 cm2/Vs for the Al0.14Ga0.86N and Al0.24Ga0.76N, respectively. Consistent with the electrical results, the photoluminescence (PL) intensity of the donor-bound exciton peak increases as the anneal temperature increases from 1,100°C to 1,250°C, indicating an increased implantation damage recovery with anneal temperature.

Characterization of BF 2+ ion-implanted layers in strained-silicon/SiGe heterostructures

BF 2 + implanted strained silicon/SiGe was characterized with the aim of maximizing the performance of strained-silicon pMOSFETs. Recovery of implantation damage in the strained-silicon layer was achieved by annealing at 900 °C or higher, but end-of-range defects remained in the SiGe layer after annealing. Germanium recoil and vacancy-enhanced redistribution of germanium caused by BF 2 + implantation are not negligible issues in strained-silicon MOSFET fabrication. Boron diffusion during annealing was retarded in SiGe compared to that in silicon, and as a result, a higher-concentration and shallower boron-doped region than that in silicon can be formed in strained silicon/SiGe. Hole mobility in boron-doped strained silicon is about 30% higher than in silicon. These results suggest that lower source and drain resistance can be achieved in the strained-silicon pMOSFET than in the silicon pMOSFET.

Electrical and optical activation studies of Si-implanted GaN

Comprehensive and systematic electrical and optical activation studies of Si-implanted GaN were made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1×1013 cm−2 to 5×1015 cm−2 at room temperature. The samples were proximity-cap annealed from 1050°C to 1350°C with a 500-A-thick AlN cap in a nitrogen environment. The optimum anneal temperature for high dose implanted samples is approximately 1350°C, exhibiting nearly 100% electrical activation efficiency. For low dose (≤5×1014 cm−2) samples, the electrical activation efficiencies continue to increase with an anneal temperature through 1350°C. Consistent with the electrical results, the photoluminescence (PL) measurements show excellent implantation damage recovery after annealing the samples at 1350°C for 20 sec, exhibiting a sharp neutral-donor-bound exciton peak along with a sharp donor-acceptor pair peak. The mobilities increase with anneal temperature, and the highest mobility obtained is 250 cm2/Vs. The results also indicate that the AlN cap protected the implanted GaN layer during high-temperature annealing without creating significant anneal-induced damage.

Dopant activation and ultralow resistance ohmic contacts to Si-ion-implanted GaN using pressurized rapid thermal annealing

Activation annealing of Si implants in metalorganic-chemical-vapor-deposition-grown GaN has been studied for use in ohmic contacts. Si was implanted in semi-insulating GaN at 100keV with doses from 5×1014to1.5×1016cm−2. Rapid thermal annealing at ∼1500°C with 100bar N2 overpressure was used for dopant activation, resulting in a minimum sheet resistance of 13.9Ω∕square for a dose of 7×1015cm−2. Secondary-ion-mass-spectroscopy measurements showed a post-activation broadening of the dopant concentration peak by 20nm (at half the maximum), while x-ray triple-axis ω–2θ scans indicated nearly complete implant damage recovery. Transfer-length-method measurements of the resistance of Ti∕Al∕Ni∕Au contacts to activated GaN:Si (5×1015cm−2 at 100keV) indicated contact resistances of 0.07 and 0.02Ωmm for as-deposited and subsequently annealed contacts, respectively.