Jason Reyes

The Application of the Continuous Anodic Oxidation Technique for the Evaluation of State‐of‐the‐Art Front‐End Structures

The differential Hall effect CAOT permits rapid accurate measurement of mobility, resistivity, and carrier concentration. For single crystal structures with carrier concentrations less than 1E20 B cm−3 the resistivity‐carrier concentration tracks the A.S.T.M. F‐723 algorithm relationship. Above ∼1E20 B cm−3, a scattering defect mobility component is added to the phononic and coulombic components. This component is significantly greater for beamline implantation than for plasma doping for both single crystal junctions and polysilicon films.

Study of Carrier Mobility of Low-Energy High-Dose Ion Implantations

New carrier drift mobility data for boron-, phosphorus-, and arsenic-doped Si in a low-energy high-dose implant regime are measured and studied using a continuous anodic oxidation technique/differential Hall effect technique. The data show that, when the doping concentration is >; 1020/cm3, both the hole and electron mobility values are lower than the conventional model predictions, and the electron mobility of the As-doped Si is lower than that of the P-doped ones. The data also show that, when the doping concentration is >; 1021/cm3 the hole mobility in the B-doped Si and the electron mobility in the P-doped Si are almost equal and reach as low as ~40 cm2/V · s, and the electron mobility of the As-doped Si is the lowest and reaches ~30 cm2/V · s. These mobility data are much lower than the conventional model predictions and are also lower than the previously published data. For the ULSI device and circuit analyses, simulations, and designs, these new mobility data need to be taken into consideration.

Optimization of diffusion, activation and damage annealing in millisecond annealing

Advances in CMOS technology require continuous reductions in the thermal budget employed for activating ion implanted dopants. However, low thermal budget annealing approaches, such as millisecond annealing, must also remove implant damage to minimize junction leakage. This paper explores the trade-offs between dopant diffusion, electrical activation and damage annealing for ultra-shallow junctions (USJ) formed by low energy B implants into both crystalline and pre-amorphized silicon. The study also addressed how low-thermal budget annealing affects the use of strong halo-style doping from As implants. Several annealing methods were studied, with the main focus on flash-assisted RTP™ (fRTP™) at temperatures between 1250°C and 1350°C. Activation was assessed with RsL™ non-contact measurements and Hg-probe four point-probe sheet resistance measurements, as well as a continuous anodic oxidation technique for depth profiling of carrier concentrations and mobility. Residual damage was assessed by photoluminescence, thermal wave studies, optical reflectance and RsL junction leakage current measurements. fRTP effectively activates high-dose, low-energy B implants, while limiting the diffusion to a few nm of profile movement. The limited thermal budget of millisecond annealing reduces, but does not fully eliminate, implant damage from heavy ions implanted at high energy, although very high process temperatures, e.g. ∼1300°C, are more effective in this regard. Strong halo doping greatly increases the junction leakage and for future device nodes it will be important to reduce implantation damage from both USJ and halo implants. Non-invasive damage metrology can help rapid optimization of implantation and annealing conditions. Such measurements will be even more useful when quantitative models can accurately link them to doping and damage profiles.

Scatter Defects and Hall Scattering Factor For The Mobility of Boron In Silicon

The mobility‐carrier concentration relation for concentrations greater than 1E20 cm−3 B is shown to depend upon the concentration of scattering defects generated near the surface as a function of the doping and annealing process. This contradicts the Masetti model which assigns a fixed relation for each dopant species, without regard for the doping or annealing process used.

Carrier activation in cluster boron implanted Si

Boron retained dose and carrier activation after spike RTA in Cluster B<inf>18</inf>⁺ (Octadecaborane : B<inf>18</inf>H<inf>11</inf>⁺) implanted Si have been investigated comparing with BF<inf>2</inf> beamline implanted Si. The retained dose estimated by SIMS depth profile integration is higher in B<inf>18</inf> samples. In the same implant set dose, carrier concentrations in B<inf>18</inf> samples show almost twice compared with BF<inf>2</inf> samples although mobilities are almost the same in both samples. This means that activation ratio of B<inf>18</inf> sample is much higher compared with that of BF<inf>2</inf> sample. This is one of the advantages of cluster ion implantation.

Study of Damage Engineering—Quantitative Scatter Defect Measurements of Ultralow Energy Implantation Doping Using the Continuous Anodic Oxidation Technique/Differential Hall Effect

The continuous anodic oxidation technique/differential Hall effect technique is used to study damage engineering of ultralow energy doping. It has been found that the scattering defect concentrations of the beam-line (BL) implants strongly correlate to the implant ion specie atomic mass unit and energy. Plasma doping (PLAD) seems to show a different mechanism for scatter defects. PLAD processes can have an in situ B-deposited film during implant and have less direct ion bombardment on the Si surface. The low scattering defect concentrations of PLAD implants (B2H6 and BF3) indicate that PLAD implants show an intrinsic advantage over BL counterparts in the current process regime.

A Comparative Study Of Dopant Activation And Deactivation In Arsenic and Phosphorus Implanted Silicon

Comparative As and P beamline implantations were subjected to a series of low, high, low, high anneals and evaluated after each step. Following high temperature anneals, there is an increase in carrier concentration, a decrease in mobility, and an increase in the concentration of mobility scattering defects.

Effects of cluster carbon implantation at low temperature on damage recovery after rapid thermal annealing

Cluster C implantation at low temperature has been studied in terms of amorphous Si (a-Si) formation and elimination of B implanted induced end of range defects (EORDs). Thickness of a-Si can be controlled by C equivalent energy and dose. Monomer C never creates a-Si layer at less than 1E15/ cm² at 25°C implant. Dose increase and temperature decrease starts to create a-Si layer. On the other hand, cluster C7 implant creates a-Si layer at less than 5E14/cm² dose even at 25°C, and −30°C implant increases the a-Si thickness by around 7∼8nm in each C dose. A large amount of EORDs remain in cluster B10 25°C implant sample after RTA at 950°C. The situation does not change a lot with B10 −30°C implant. On the other hand, cluster C7 co-implant with B10 at 25°C, however, greatly reduces EORD density. EORD free can be realized in C7 co-implant with B10 at −30°C. Cluster C7 co-implant at −30°C assists the EORD elimination. Sheet resistance of cluster C and B10 co-implanted at −30°C sample is remarkably low compared with only B10 implanted sample. It can be concluded that cluster C implantation at −30°C is very effective for eliminating EORDs and obtaining high carrier activation.

Optimization of implant and anneal processes

A method of choosing a coupled pair of a doping process and an annealing process that is optimized on the basis of the R<inf>s</inf>·x<inf>j</inf> figure of merit. Differential Hall effect evaluations are used to measure 1/µ<inf>def</inf>, the defect scatter contribution to the mobility. Supressing 1/µ<inf>def</inf> leads to optimization of the doping process-annealing process couple.

A Comparative Study Of Dopant Activation And Deactivation In Boron Implanted Silicon

BF2 beamline and B2H6 PLAD implants were evaluated after a series of low, high, low, high anneals. Following a high anneal, we find an increase in mobility and a decrease in concentration of mobility scattering defects.