Hidefumi Matsui

Vacancy-Type Defects Introduced by Gas Cluster Ion-Implantation on Si Studied by Monoenergetic Positron Beams

Vacancy-type defects in Ar and B gas cluster ion-implanted Si were probed by monoenergetic positron beams. The acceleration energy of the clusters ranged between 20–60 keV, and the mean cluster size was 2×103 atoms. Doppler broadening spectra of the annihilation radiation were measured, and the vacancy-rich region was found to localize at a depth of 0–13 nm. Measurements of the lifetime spectra of positrons revealed that two different defect species coexisted in the damaged region introduced by Ar gas cluster implantation, and these were identified as divacancy-type defects and large vacancy clusters filled with Ar. The formation of the vacancy clusters was attributed to extremely high temperature and its rapid transients in impact regions of Ar cluster ions. For B gas cluster ion implanted Si, the detected momentum distribution of electrons in the damaged region was broader than that in the defect free Si, suggesting that the trapping of positrons by open spaces adjacent of B clusters.

Observation and Elimination of Recoil Particles From Turbo Molecular Pumps

The existence of recoil particles from the turbo molecular pump has been verified. The recoil particles may be the root cause of yield degradation for the vacuum processes such as the plasma etching processes. To eliminate the recoil particles, they must be trapped inside the turbo molecular pump or inside the manifold chamber. After experimenting with various materials and designs, we have built a novel recoil particle trap and verified its effectiveness in a semiconductor production line.

Using an Optical Motion Sensor for Visualization and Analysis of Maintenance Work on Semiconductor Manufacturing Equipment

We developed a motion capture technique to record a worker’s movements during preventive maintenance, especially wiping actions during wet cleaning. Time-series 3-D coordinate data of the worker’s hand was successfully obtained with a motion capture sensor, and four different possible movements were distinguished. This data was also correlated with changes in the number of particles on the surface of a chamber part before and after wiping. The results show that key indicators of high-quality maintenance work can be extracted from workers’ motions using this technique.

Airborne contamination control for 157-nm lithography: influence of ammonia contamination

The ammonia durability of the 157-nm lithography resists is still unclear due to the smaller target dimensions, thinner resist films, and variations in base polymer compared to those of 193-nm and 248-nm resists. It has not been determined what ammonia concentrations must be achieved in order to successfully process 157-nm resists. Until now, the ammonia durability of initial 157-nm resists during post exposure delay (PED) and during post coating delay (PCD) was compared to those of 193-nm and 248-nm resists. It was confirmed that all initial 157-nm resists had low ammonia durability. In this paper, the ammonia durability of newly developed 157-nm resists, that have improved transmittance and resolution, was evaluated during PED and PCD. Then, we found that the ammonia durability of these resists were not enough and that the ammonia concentration from exposure to development should be kept under 0.1 ppb. Thermal desorption spectroscopy results showed that resists with lower ammonia durability tended to have more amount of adsorbed ammonia than other resists. Furthermore, the ammonia durability of 157-nm resist couldn’t be improved to the level of that of 193- and 248-nm resist by the adjustment amount of resist additives. Due to the low ammonia durability, it will be necessary to control the ammonia concentration below 0.1 ppb in processing equipment used in 157-nm lithography.

Evaluation of resist-film property for CD control

In a photolithography process, it is vital to control Critical Dimension (CD) within wafer. In the current process, although parameters are controlled during post-exposure bake (PEB) and development, only film thickness is checked before exposure for the CD control. However, as the fine patterning by using chemically amplified resist (CAR) has progressed, CD control within wafer has been affected by very small changes of protecting groups; distribution of additives (PAG, quencher etc.) concentrations, and solvent concentrations, thus it has become more important to control film compositions = film properties before exposure. Following by CD variations within wafer caused by air flow in Post applied Bake (PAB) chamber, we examined evaluation methods of KrF resist film properties and made various evaluations of unexposed film after PAB. This paper describes correlation between CD and PAG, quencher, and solvent concentration; consideration of CD variations mechanism based on the correlation data; and problems when shifting to the next generation process.