Behavior of Ultrafine Metallic Particles on Silicon Wafer Surface

Abstract

The diameter of particles which adversely affects the yield has been shrinking as ULSI devices are more and more miniaturized. Ultrafine particles with diameters of 0.1 ~m or less have become important recently. Ultrafine particles of this type are expected to be difficult to remove. This study has established a method to evaluate ultrafine particle removal efficiency. Ultrafine metallic particles with diameters of several to several hundreds of nanometers were deposited on the Si surface using a gas deposition method. The removal efficiency of the ultrafine particles using various cleaning solutions was investigated. APM (NH4OH-H202-H20) cleaning can remove 150 nm Au particles, but cannot remove ultrafine Au particles with a diameter less than several tens of nanometers. In addition, the Si surface becomes rougher when a DHF-H20~ cleaning is performed to remove Au ultrafine particles. This is believed to be because noble metals such as Au, Ag, and Cu, which feature a higher electronegativity than St, attract electrons from Si facilitating Si oxidation.

Photoresist Removal Using H Radicals Generated by Iridium Hot-Wire Catalyst

“…Photoresists have to be removed at the end of the process. In the removal of photoresist, there are some problems, such as the environmental impacts and the costs of the chemicals because hazardous chemicals are usually used for removal [1][2][3]. As one of the removal methods without the chemicals, the removal method by an ashing, in which photoresist was decomposed to oxide-carbon compounds by using the oxygen plasma [4][5][6][7], is used to remove photoresists in some cases.…”

Analysis of Resist Removal Phenomenon Using Laser Irradiation

“…Environmentally unfriendly chemicals are used in a large amount and cause environmental damage [3,4]. Also, oxygen plasma ashing may cause oxidation of substrates and metal wiring because this process requires high temperature (above 250°C) [5,6]. Therefore, several resist removal methods have been developed (e.g., atomic hydrogen [7][8][9][10], UV/ozone [11,12]).…”

Pressure Dependence of Photoresist Removal Rate Using Hydrogen Radicals

“…Moreover, photoresists must be removed after processing. Actually, photoresist removal presents several problems such as environmental impacts and costs of chemicals because large amounts of hazardous chemicals are usually necessary [1][2][3].…”