Academic literature on the topic 'Wet chemical semiconductor etching processes'

Concerning the processes of the semiconductor industry, device integration is increasing and cell structure is becoming more complicated, which brings many new kinds of challenges. The basic requirements for a future integration device are minimum feature size reduction with device integration and high-speed operation with sufficient cell capacitance. Many kinds of conventional films including electrode and dielectric materials should be altered to meet device requirements. Moreover, as the allowance level for contaminants on substrate surfaces becomes more stringent, the importance of removing them becomes even greater. Because of this, the semiconductor process for high quality device fabrication will never be realized without perfect cleaning on all surfaces. It is reported that the conventional cleaning solutions such as a NH4OH/H2O2/H2O (SC-1) solution (1:4:20, 80 °C), H2SO4/H2O2 (SPM) solution (4:1, 90 to 120°C), and HCl/H2O2/H2O (HPM) solution (1:1:6, 80 to 90°C) are not compatible with metal film exposed surfaces with very tiny patterns, due to the fast etching rate of metal films [1] . In 1995, at the base of the mechanism of the removal of the adhered contaminants such as metallic impurities, particles and organics, T. Ohmi proposed a total room temperature wet cleaning process (so called “UCT cleaning”) [2]. As a result of the continuous research on developed cleaning, the five steps process was revised to a four step room temperature wet cleaning for real device cleaning. The cleaning consists of 1) CO2 added O3-UPW cleaning for removing organic and metallic impurities, 2) NH3 added H2-UPW+MS cleaning for removing of particles, 3) HF/H2O2(FPM) cleaning for removing metallic impurities, and 4) H2-UPW+MS rinse for the removal of chemical residues, prevention of particle re-adhesion, suppression of native oxide growth, and enhancement of H-termination.

A plasma, commonly referred to as the “fourth state of matter,” is an ensemble of randomly moving charged particles with a sufficient particle density to remain, on average, electrically neutral. While their scientific study dates from the 19th century, plasmas are ubiquitous, comprising more than 99% of the known material universe. The term “plasma” was first coined in the 1920s by Irving Langmuir at the General Electric Company after the vague resemblance of a filamented glow discharge to a biological plasma.Plasmas are studied for many reasons. Physicists analyze the collective dynamics of ions and electron ensembles, utilizing principals of classical electromagnetics, and fluid and statistical mechanics, to better understand astrophysical, solar, and ionospheric phenomenon, and in applied problems such as thermonuclear fusion. Electrical engineers use plasmas to develop efficient lighting, and high-power electrical switchgear, and for magneto-hydrodynamic (MHD) power conversion. Aerospace engineers apply plasmas for attitude adjustment and electric propulsion of satellites. Chemists, chemical engineers, and materials scientists routinely use plasmas in reactive ion etching and sputter deposition. These methods are commonplace in microelec tronics since they allow synthesis of complex material structures with submicron feature sizes. A substantial portion of the multi-billion-dollar market for tooling used to manufacture semiconductors employs some form of plasma process. When compared with traditional wet-chemistry techniques, these dry processes result in minimal waste generation. Plasmas are also useful in bulk processing—for example as thermal sprays for melting materials.While the quest for controlled thermonuclear fusion dominated much of plasma research in the 1960s and 1970s, in the last 20 years it has been the application of plasmas to materials processing that has provided new challenges for many plasma practitioners. It is not surprising that the guest editors and several of the authors for this issue of MRS Bulletin come from a fusion plasma-physics background.