Hyun Soh

Low temperature remote plasma cleaning of the fluorocarbon and polymerized residues formed during contact hole dry etching

We investigated the remote oxygen and hydrogen plasma cleaning to remove reactive ion etching (RIE) induced fluorocarbon and polymerized residues formed during the dry etching of the contact hole. After the RIE process, RIE induced fluorinated surface and/or fluorocarbon formation with a very homogeneous spatial distribution at several tens of A depth from the surface was observed. The photoresist films before and after the RIE process showed a similar ashing behavior. Ashing rate generally increased with increasing the process temperature and plasma power. X-ray photoelectron spectroscopy and Auger electron spectroscopy analysis showed that the carbon and fluorine associated contamination can be effectively removed by oxygen plasma but it left a small amount of carbon residue and sacrificial silicon oxide. Hydrogen plasma cleaning was necessarily required to remove the residual carbon contaminants formed on the silicon surface after oxygen plasma ashing. Two step cleaning, oxygen plasma ashing with an intentionally left very thin photoresist layer and subsequent hydrogen plasma cleaning, is a very effective cleaning process to remove residual carbon and polymer without forming a SiO2 layer. This article presents the systematic evaluation of the remote oxygen and hydrogen plasma cleaning of RIE induced polymer residues.We investigated the remote oxygen and hydrogen plasma cleaning to remove reactive ion etching (RIE) induced fluorocarbon and polymerized residues formed during the dry etching of the contact hole. After the RIE process, RIE induced fluorinated surface and/or fluorocarbon formation with a very homogeneous spatial distribution at several tens of A depth from the surface was observed. The photoresist films before and after the RIE process showed a similar ashing behavior. Ashing rate generally increased with increasing the process temperature and plasma power. X-ray photoelectron spectroscopy and Auger electron spectroscopy analysis showed that the carbon and fluorine associated contamination can be effectively removed by oxygen plasma but it left a small amount of carbon residue and sacrificial silicon oxide. Hydrogen plasma cleaning was necessarily required to remove the residual carbon contaminants formed on the silicon surface after oxygen plasma ashing. Two step cleaning, oxygen plasma ashing with an in...

Characteristics of Polymer Residues Formed at the Via Hole and Photoresist Ashing Properties of Remote Oxygen/Nitrogen Plasma.

The low-temperature remote oxygen/nitrogen plasma ashing process that removes both the photoresist and polymer residues containing carbon and fluorine after reactive ion etching (RIE) process was investigated. The fluorocarbon residue was distributed with a depth of several tens of angstroms from the surface with a relatively homogeneous spatial distribution after the RIE process. X-ray photoelectron spectroscopy (XPS) analysis also showed the formation of fluorocarbon films during RIE with mainly C–C, C–CFx (x=1,2,3), CF, and CF2 bonds. The ashing rate increased with increasing amount of nitrogen addition to oxygen gas and showed saturation at approximately 10% of nitrogen addition. Mass spectrometry measurement revealed that the amount of atomic oxygen increased with the addition of nitrogen to oxygen gas. This study revealed that atomic oxygen is the primary reactive species responsible for removal of photoresist in the remote oxygen/nitrogen ashing process.

Remote RF plasma cleaning for the removal of organic impurity

Summary form only given, as follows. The trends in modern silicon-based microelectronics are pointing in the direction of in-situ processing at low temperature to achieve reliable profiles and to make use of compatible processes. Low energy plasma process, called the plasma cleaning, can be used to clean silicon surfaces from the carbon contaminants and native oxide without any pretreatment of the wafers. In the integrated circuit (IC) fabrication, the photoresist (PR) ashing and PR stripping processes are generally followed the silicon etching process to remove the PR and polymerized residues. However, it was founded no tendency on surface but a benefit of the plasma treatment by means of cleaning the surface. In this work, we investigate the surface reaction of plasma generated in inductively coupled remote plasma with connection of mass spectroscopy.

Atom recombination on SiO/sub 2/ and Si(100) surfaces

Summary form only given, as follows. The probability of recombination was measured for recombination of hydrogen and oxygen atoms on SiO/sub 2/ and Si(100) surfaces at 298 K, 500 K, 700 K, 900 K and 1100 K in the range of 0.1 torr with hydrogen and oxygen gas. The probability of recombination was a first order reaction with respect to the atom concentration from 298 K to 1100 K. The Arrhenius plots were very complex. All observations were explained by assuming a surface with a small fraction of active sites that irreversibly bind chemisorbed atoms. We have proposed a process of atom recombination at the surface active sites.

Formation of hydrophobic thin films on metal surfaces

Summary form only given, as follows. One of the surface properties, water-repellency or hydrophobicity, has been attracted attention in various industrial fields. Hydrophobic surface treatment of materials and preparation of water-repellent films have been performed by using plasma deposition techniques. In this work, the plasma enhanced chemical vapor deposition (PECVD) method has been employed to coat thin fluorocarbon film on metal surface.

Observation of surface change by plasma in plasma display panel (PDP)

Summary form only given, as follows. Inside a working PDP, there exist highly reactive conditions in the gap between the two glass panels Accordingly, reactive species generated by the plasma collide with each other and the walls of the plates. Inside surfaces of the panel start to change after turning on the PDP and applying the plasma in each cell. In order to achieve a stable discharge condition, a period of time is necessary. This final step of manufacturing is called an aging process. For reducing the process time, it is important to understand the physical and chemical changes of the inner surface of the panel and the composition change of the inside gas during the aging process. We have designed an in-situ analysis system for 7-inch test panels prepared by each fabrication process. Test panels with various aging times (0.5, 1, 2, 4 and 24h) were also introduced into the UHV system. The panels were disassembled by wobble sticks and transferred to the analysis chambers to investigate the changes. We examined the surfaces mainly by using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).

Methane activation of plasma and catalytic reaction

Summary form only given, as follows. Conversion of methane to higher hydrocarbon products was investigated through the microwave and RF plasma catalytic reaction. In this study, various experiments have been conducted to find out the effects of parameters on the high frequency region, that was a microwave of 2.45GHz and radio frequency of 13.56 MHz. Manufacturing of C2 products and higher hydrocarbons was carried out by two kinds of discharge equipment and nonoxidative and oxidative coupling of methane. In the microwave plasma catalytic reaction, C2+ products have been obtained much more due to many free radicals produced at low plasma power. Also natural gas containing a little amount of ethane and propane is more active reactant, producing more C2+ products such as ethane, ethylene and acetylene than methane.

Surface change by plasma discharge in plasma display panel

Summary form only given. Inside of working PDPs, there exist highly reactive conditions in the gap between two glass panels. Accordingly, reactive species generated by plasma collide each other and the wall of the plates. In fabricating process, front and rear panel are sealed with a glass frit, followed by baking and charging with gas. The inside surface of panel starts to change after turning on the PDP and applying plasma in each cell. In order to achieve a stable discharge condition, a period of time is necessary. This final step of manufacturing is called an aging process. For reducing the time of process, it is important to understand the physical and chemical changes of inner surface of the panel and composition change of inside gas during the aging process. We designed an in-situ analysis system for 7-inch test panel prepared by each fabrication process. Test panels with various aging time are also introduce to the UHV system. The panels are disassembled by wobble sticks and transferred analysis chambers to investigate the changes. We examine the surfaces mainly by using x-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM).