Papers by Keyword: Low-K

Abstract: The performance of a new cryogenic aerosol process was evaluated for cleaning nanoparticles and providing damage-free processing. Particle Removal Efficiency (PRE) tests conducted with wet deposited 40 nm, 30 nm and 18 nm silica particles on 300 mm wafers demonstrated cleaning efficiencies above 80%. Damage-free capability of the cryogenic aerosol process was evaluated with poly-silicon lines with an aspect ratio of approximately 9:1. These results highlight the potential of this new cryogenic aerosol to provide semiconductor device yield benefits by reducing small particulate contamination without causing pattern damage.

Abstract: Pattern collapse has long been known in photoresist patterning where the resist patterns merge or collapse during rinsing and drying steps [. The forces responsible for this collapse were identified as capillary forces during the drying process. Structures such as titanium nitride DRAM cylinders [ and silicon Flash shallow trench isolation (STI) lines have also been observed to be pattern collapse sensitive due to increase in aspect ratio of the features. Micro-electromechanical systems (MEMS) devices also show a similar phenomenon, but on a larger length scale, and is referred to as stiction [. For the technology nodes <14 nm, back-end-of-line (BEOL) low-k structures are also on the verge to show pattern collapse behavior. Whether a structure is sensitive to pattern collapse or not depends on several parameters, which will be analyzed in this paper.

Abstract: Plasma dry etching processes are commonly used to fabricate sidewalls of trenches and vias for copper / low-k dual damascene devices. Typically, some polymers remain in the trench and at the via top and sidewall. Other particulate etch residues are may remained in the bottom and on the sidewalls of vias. Generally, the particulate consists of mixtures of copper oxide with polymers. The polymers on the sidewalls and the particulate residues at the bottom of vias must be removed prior to the next process step. Small amounts of polymer are intentionally left on the sidewalls of trenches and vias during the etching in order to achieve a vertical profile and to protect the low-k materials under the etching mask. Until now, the industry has relied mainly on organic solvent containing mixtures to clean etch / ash residues from such devices. The effectiveness of available residue removers varies with the specific process and also depends on which new integration materials are used. New materials typically include Cu, TaN, low-k dielectrics and others [1-. Solvent content is thought to aid the removal of polymer residues and particulates produced during plasma dry etching processes. Therefore, in the past we have used a residue remover which contains DMAC (dimethylacetamide). But the use of DMAC is banned in microelectronic fabrication facilities in Europe because of its toxicity. Thus we wanted to find and evaluate a DMAC-free residue remover for removing polymer residues while maintaining high selectivity to the copper and ILD films.

Abstract: Atomic force microscope (AFM) with inclined sample measurement and hydrophobic functionalized AFM probe was used to visualize the sidewall of low-k pattern and allowed to characterize the hydrophobic characteristics on the sidewall after low-k etch. To functionalized the AFM probe, 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS) as a hydrophobic film was coated on an AFM probe. Because of the magnitude of the phobic-phobic interaction force and the tip forced to make a phase shift. Using this technique the visualization and characterization of the etch residue on the low-k sidewall can be successfully performed. It is shown that the investigation toward an effective chemical clean for the etch residue removal could be applicable.

Abstract: A new class of low-k materials thin films, deposited from a DiPhenyleMethylSilane (DPMS) vapors was prepared using PECVD technique. These films are elaborated in microwave excited DECR plasma reactor (Distributed Electron Cyclotron Resonance) from pure DiPhenylMethylSilane (DPMS) using various plasma discharge power (100-400 W) or mixed with 50% of oxygen (O2).The improvements of film properties were investigated by capacitance–frequency (C–f), current–voltage (I–V) techniques and Fourier transform infrared spectroscopy (FTIR). The obtained results show that an increase in plasma discharges power from 100 to 400 watts leads to the decrease in dielectric constant value from 4.4 to 3.7 (measured at 10 kHz). The incorporation of oxygen improves the dielectric properties of the films; the dielectric constant value was reduced to 2.9.

Abstract: Various annealing conditions after film deposition have a great effect on electrical and structural properties of low-k films. In this work, we studied hydrogen atmosphere heat treatment effect on low-k films. After the room temperature deposition of a-SiOC:H low-k films following post-deposition-annealing (PDA) for 30 min. at 450°C in an N2 ambient, final annealing was performed for 30 min. at 400°C in an N2, a forming gas 1 (5% H2 + 95% N2), and a forming gas 2 (10% H2 + 90% N2) ambient. The flat band voltage was shifted toward the ideal value of 0.61V after two forming gas anneals, but it increased k values of the films. It was ascribed that hydrogen effectively substitutes defect sites or structural imperfections of low-k films and makes the film more hydrophilic. The FT-IR, XPS analyses and the contact angle measurement supported our conclusion.

Abstract: Low dielectric constant SiOC(-H) films were deposited on p-type Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES; C7H18O3Si) and oxygen gas as precursors. The SiOC(-H) films were deposited at room temperature and then annealed. Nanoindentation studies were carried out in order to determine the mechanical properties of the SiOC(-H) films. The elastic modulus and hardness of SiOC(-H) films were measured to be in the range of 2.14 – 5.02 and 0.12 – 0.74 GPa, respectively. It was observed that the values of elastic modulus and hardness decreases with increase of flow rate ratio of the precursors. In the SiOC(-H) film, -CH3 group as an end group was introduced into -O-Si-O- chain network, thereby reducing the film density to decrease the values of the mechanical properties.

Abstract: The porous SSQ (silsesquioxane) films were prepared by using alkoxy silyl substituted cyclodextrin (sCD) and methyl substituted cyclodextrin (tCD) based porogen. The mechanical and electrical properties of these deposited films were investigated for the applications as low dielectric materials. The mechanical properties of porous film by using sCD are worse than those by using tCD due to its high pore interconnection length. sCD templated porous films show almost constant pore diameter as a function of porogen concentration due to strong linear polymerization of the sCD molecules through polycondensation.

Abstract: This paper presents study on porous Hydrogen Silsesquioxane (HSQ) of dielectric constant near 2. Porous HSQ solution was spin-on coated and then treated by wet ammonia. During the treatment, HSQ film went through a sol-gel process. Pores were uniformly formed in HSQ film after a baking process to remove solvent. A solid network structure of porous HSQ was then formed after a high-temperature curing process. In this work, we compared the properties of porous HSQ with varying process time of wet ammonia treatment and curing temperature. Change of chemical structure was analyzed by Fourier transform infrared (FTIR) spectrometry. We found that the cage structure of porous HSQ was reduced but the network structure was enhanced as treatment time of wet ammonia increased. Hardness and Young’s modulus were measured by nano-indentation technique. The adhesion strength of porous HSQ with silicon carbide was measured. Surface properties and electrical characterization of porous HSQ with varying process conditions have also been examined.