Friction anisotropy of violet phosphorene and its surface structure direction identification

Violet phosphorene, a recently determined semiconducting two-dimensional elemental structure, is a promising electronic and optoelectronic material. The nano-tribological properties of violet phosphorene nanoflakes are essential for their micro device applications. A friction anisotropy has been demonstrated for the violet phosphorene nanoflakes by lateral force microscope due to the sub-nanorod components of violet phosphorus. The friction forces of the violet phosphorene nanoflakes have been demonstrated to be valley along sub-nano rod direction and peak across the sub-nanorod direction with a period of 180°, resulting in a fast identification of the surface structure direction of violet phosphorene. The friction of violet phosphorene nanoflakes has also been shown to increase with increasing scanning pressure. However, it is not sensitive to scanning speed or layers. The friction of the violet phosphorene nanoflakes have also been demonstrated to increase when exposure to air for hours. The friction and adhesion features of violet phosphorene nanoflakes provide valuable foundation for violet phosphorene based devices.

Pattern Collapse and Particle Removal Forces of Interest to Semiconductor Fabrication Process

The removal of particles from silicon wafers without pattern damage during fabrication process is extremely important for increasing the yield. Various physically assisted cleaning techniques such as megasonic cleaning, jet spray cleaning, and laser shock wave cleaning (LSC) have been introduced. However, most of tools show pattern damage [1]. One of the main challenges in next generation cleaning process is the particle removal without the pattern damage. As the feature size continues to decrease, the patterns are so fragile that it is hard to remove particles less than 50 nm without pattern damages. To accomplish the effective cleaning performance without the damage, the collapse force of pattern and removal force of particle should be known quantitatively. In this paper, pattern collapse forces were measured for different gate stack patterns by lateral force microscope (LFM) [2]. The particle removal mechanism of LSC was studied to find the relationship between measured collapse forces and particle removal force by LSC which has a known applied force. Finally, particle contaminated pattern wafers were cleaned by LSC with optimized process parameters to verify the relationship and to achieve the best particle removal performance without the pattern damage.

Nanolubrication: Patterned Lubricating Films Using Ultraviolet (UV) Irradiation on Hard Disks

Nanolubrication is emerging to be the key technical barrier in many devices. One of the key attributes for successful device lubrication is self-sustainability using only several molecular layers. For single molecular species lubrication, one desires bonding strength and molecular mobility to repair the contact by diffusing back to the contact. One way to achieve this is the use of mask to shield the surface with a patterned surface texture, put a monolayer on the surface and induce bonding. Then re-deposit mobile molecules on the surface to bring the thickness back to the desired thickness. This paper describes the use of long wavelength UVirradiation (320–390 nm) to induce bonding of a perfluoropolyether (PFPE) on CNx disks for magnetic hard disk application. This allows the use of irradiation to control the degree of bonding on CNx coatings. The effect of induced bonding based on this wavelength was studied by comparing 100% mobile PFPE, 100% bonded PFPE, and a mixture of mobile and bonded PFPE in a series of laboratory tests. Using a lateral force microscope, a diamond-tipped atomic force microscope, and a ball-on-inclined plane apparatus, the friction and wear characteristics of these three cases were obtained. Results suggested that the mixed PFPE has the highest shear rupture strength.