Kazuhiro Oka

Direct Observation of Crystal-Originated Particles on Czochralski-Grown Silicon Wafer Surface and Effect on Gate Oxide Reliability

We found that crystal-originated particles (COP) on a Czochralski-grown Si wafer surface consist of single pits and pair pits, using a pattern-defect inspection machine and SEM. The influence of these pits on the gate oxide reliability was studied by means of a time dependent dielectric breakdown (TDDB) test under constant voltage stress (8 MV/cm). It was clearly demonstrated that when the gate oxide thickness was around 10 nm, in the active region pair pits caused gate oxide failure, while single pits did not. It was also found that broad pair pits, formed by preferential oxidation/etching treatment, did not degrade the gate oxide reliability even when situated in the active region.

Solution of in-line inspection problem for grainy metal layers by "saturation effect" of grayscale

We demonstrate a solution, which enhances the practical sensitivity of in-line pattern matching inspectors for grainy metal layers by reducing the nuisance counts without additional investment. We confirmed that most nuisance defects are caused by the grain boundaries on the Hot-AlCu wirings. Then we proposed a new solution called saturation effect to decrease the defect signals from the grain boundaries. The experimental results prove that the saturation effect with illumination brightness optimization successfully cancels the defect signal from grain boundaries. As a result, we can efficiently detect real defects without detecting the grain boundaries. The observed practical sensitivity limit is enhanced from 0.8 /spl mu/m to 0.4 /spl mu/m. We believe this solution may accelerate the yield enhancement counter measurements based on in-line inspection results.

Capture rate enhancement method of 0.1 /spl mu/m-level defects by pattern matching inspectors

In this paper, a method of enhancing the capture rate of 0.1 /spl mu/m-level defects by pattern matching inspectors is studied from the viewpoint of image variances. The inspection sensitivities are experimentally evaluated by using the detection rate of the defects on an actual device and also on the TEG. The image noise and the defect signal of the captured CCD images of the same defect are quantitatively analyzed. The observed image noise and the defect signal obey a normal distribution. The capture rate calculated by our model, based on a normal distribution, almost agrees with the experimental data. In addition, as an example of capture rate enhancing, a unique TEG called TWICE is demonstrated. By our method, defect inspection engineers can obtain the key factors for enhancing the capture rate of 0.1 pm-level defects on both actual devices and TEGs.

VACUUM VAPOR DEPOSITION PROCESS FOR CERAMICS DEVELOPMENT OF THE VACUUM VAPOR DEPOSITION PROCESS FOR CERAMICS BY CO2 LASER

Abstract The vacuum vapor deposition process using a CO2lase; has been studied (or producing high adhesion ceramic films on various materials. Deposition of aluminum oxide and silicon oxide films with adhesion strengths above 50 MPa on stainless steel was achieved at high deposition rates with substrate heating, For silicon oxide films, addition of a moderate oxygen supply allowed deposition of highly adherent films at lower substrate temperatures. Adhesion strengths above 50 MPa were estimated at a substrate temperature of 470°K and an oxygen flow rate of 1.9 x 10-7 m3/s, in spitof the high deposition rate of 30 nm/s

Formation of alumina film by laser PVD

Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension and much higher compression.Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension an...

Basic study on laser physical vapour deposition of ceramics

Abstract A basic study on the laser physical vapour deposition (PVD) of ceramics was conducted using a continuous wave (CW) Nd:YAG laser. Aluminaceramic and nickel plates were used as target and substrate materials respectively. The experiment was carried out over a wide range of PVD conditions, i.e. substrate temperature up to 1100 K and pressures up to 6.5 × 10 -4 Pa. A Knoop hardness (HK) tester and a scratch tester were used to evaluate the deposited film. Phase content, microstructure and chemical composition were examined by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Results showed that a crystallized film with a hardness HK of 30 GPa or greater could be obtained by providing a suitable combination of PVD conditions, i.e. pressure and substrate temperature.