The Study of Modified Layers in SiCOH Dielectrics using Spectroscopic Ellipsometry

2003 ◽  
Vol 766 ◽  
Author(s):  
Marcus A. Worsley ◽  
Stacey F. Bent ◽  
Stephen M. Gates ◽  
Kaushik Kumar ◽  
Timothy Dalton ◽  
...  
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Silicon Oxide ◽  
Layer Model ◽  
Plasma Etch ◽  
Carbon Doped ◽  
Organosilicate Glass ◽  
Modified Layer ◽  
Intermetal Dielectric ◽  
Low K ◽  
Processing Steps

AbstractThe current challenge in designing new low-k dielectrics is realizing sufficient mechanical and chemical stability such that the material can be integrated into current damascene schemes. The material of interest in this study is a nonporous SiCOH composite (carbon-doped silicon oxide, also known as organosilicate glass “OSG”) for use as an intermetal dielectric (IMD). During integration of this IMD, processing steps such as etch, resist strip and chemicalmechanical polishing for planarization may chemically alter the outer layer of the dielectric. Here, spectroscopic ellipsometry is used to characterize the modified layer of SiCOH films after exposure to different resist strip plasmas. The data are analyzed based on a 2-layer model, consisting of a carbon-deficient layer on the surface of the low-k SiCOH dielectric. This model is supported by XPS and FTIR data. The effects of two types of plasma etch chemistry on the formation of this modified layer were studied, and differences between the two chemistries were found. The 2-layer model accurately describes the modifications produced by the oxidizing plasma, but its description of the modified layer formed by the plasma involving nitrogen is not complete. A 3-layer model with an additional nitrogen-doped layer is suggested.

Spectroscopic Ellipsometry as a Potential In-Line Optical Metrology Tool For Relative Porosity Measurements of Low- K Dielectric Films

2001 ◽  
Vol 697 ◽  
Author(s):  
N.V. Edwards ◽  
J. Vella ◽  
Q. Xie ◽  
S. Zollner ◽  
D. Werho ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectral Range ◽  
Spectroscopic Ellipsometry ◽  
Optical Metrology ◽  
Dielectric Films ◽  
Electron Densities ◽  
Organosilicate Glass ◽  
Relative Porosity ◽  
Low K ◽  
Porosity Measurements

AbstractThe optical properties of organosilicate glass (OSG) samples were investigated with spectroscopic ellipsometry. We found that samples with dramatically higher hardness had higher indices of refraction (RI) and thus higher electron densities and lower relative porosities than films with lower hardnesses. The reverse was true for films with low hardnesses. As well, these films did not have the same optical properties as porous SiO2 across the spectral range measured, which we show has significant implications for the in-line optical metrology of these materials.

Moisture Adsorption in Plasma-Damaged Porous Low-k Dielectrics

2008 ◽  
Vol 1079 ◽  
Author(s):  
Ekaterina Vinogradova ◽  
Casey E Smith ◽  
DW Mueller ◽  
Andrew J McKerrow ◽  
Rick Reidy
Keyword(s):  
Moisture Absorption ◽  
Deuterium Oxide ◽  
Grazing Angle ◽  
Film Surface ◽  
Ambient Conditions ◽  
Exchange Reactions ◽  
Plasma Etch ◽  
Organosilicate Glass ◽  
Altered Surface ◽  
Low K

ABSTRACTPlasma etch/ash processes can induce changes in low-k film surface/bulk chemistries and topographies resulting in increased water absorption, surface roughness, and metal intrusion. After ashing, the altered surface character of the low-k can impact wetting, adhesion, and, consequently, the resistance of subsequently deposited barrier layers. In this work, we describe the use of deuterium oxide as means of measuring moisture penetration into low-k films. Film chemistries have been monitored using grazing angle attenuated total reflectance (GATR) and transmission Fourier transform infrared spectroscopy (FTIR). To study moisture absorption in porous spin-on and CVD low-k films, unashed and ashed films have been exposed to D2O liquid and vapor treatments under “dry” nitrogen. The extent of D2O uptake, removal and exchange reactions has been studied using transmission and GATR FTIR methods because the D2O and O-D adsorption peaks are distinct from water and O-H as well as other low-k adsorptions. This method can be used to study Si-OH species because deuterium can exchange with hydrogen within silanols under ambient conditions while methyl groups are much less likely to exchange. Three different low-k films, a porous spin-on MSQ (k=2.2), a porous CVD (k=2.3), and an organosilicate glass (OSG, k=2.85) have been used. In FTIR spectra, unashed low-k films show minimal D2O adsorption. In MSQ hydrogen-ashed films, the data suggest the presence of deuterium oxide and O-D peaks. Further, D2O adsorption appears to be considerably higher for ashed films as would be expected due to the hydrophobicity of these films. In the CVD films, there does not appear to be as marked a difference. This method permits the introduction of a chemical “marker” into low-k wet and ambient processes allowing one to distinguish among adsorptions from different aqueous sources.

Post Etch Residue Removal and Material Compatibility in BEOL Using Formulated Chemistries

2014 ◽  
Vol 219 ◽  
pp. 201-204 ◽  
Author(s):  
Els Kesters ◽  
Q.T. Le ◽  
D. Yu ◽  
M. Shen ◽  
S. Braun ◽  
...  
Keyword(s):  
Good Adhesion ◽  
Plasma Etch ◽  
Residue Removal ◽  
Fluorocarbon Plasma ◽  
Lift Off ◽  
Materials Used ◽  
Low K ◽  
Etch Residue ◽  
Processing Steps ◽  
Dielectric Degradation

A possible way to realize a 22.5 nm 1⁄2 pitch and beyond BEOL interconnect structures within the low-kmaterial is the partial-trench via first with self-aligned double patterning (SADP) integration approach. A scheme of this BEOL integration stack with the different materials used after patterning is described in Figure 1. In BEOL processing, fluorocarbon-containing plasma is commonly used to pattern silica-based dielectric layers. During the patterning of the low-kdielectric layer, a thin layer of fluoropolymer (CFx-type residues) is intentionally deposited on the dielectric sidewalls and TiN hardmask to ensure anisotropic etching and prevent/minimize dielectric degradation. This polymer layer must be removed from the sidewall and the via bottom prior to the subsequent processing steps to achieve good adhesion and coverage of materials deposited in the etched features. The compatibility requirement is even more stringent for advanced low-kdielectrics, i.e. materials with lowerk-value and higher porosity. The post etch residue (PER) amount and properties are specific and depend on the stack structure and the plasma that is used for patterning. The low-kmaterials and hardmasks that are used in this work are respectively an organo-silicate glass (OSG) type of low-kmaterial withk= 2.4 (~20 % open porosity) and low-stress TiN. Recent results clearly showed the presence of a highly fluorinated layer deposited on the trench sidewalls during the plasma etch based on a fluorocarbon plasma [1-3]. Commodity aqueous cleaning solutions, such as diluted HF, do not efficiently remove the sidewall polymers without etching the underlying layer (lift-off). Therefore, there is a need for commercially available chemicals that can be easily tuned to deal with the different requirements. This study focuses on the use of FOTOPUR® R 2300 mixed with H2O2 for polymer residue removal selectively to other materials (presented in the stack) such as MHM, metals (Cu, W), and porous low-k dielectrics. We will show that TiN etch can be easily tuned by changing the concentration of H2O2.

Newly Developed Low-K and Low-Stress Fluorinated Silicon Oxide Utilizing Temperature-Difference Liquid-Phase Deposition Technology

1998 ◽  
Vol 511 ◽  
Author(s):  
Ching-Fa Yeh ◽  
Yueh-Chuan Lee ◽  
Su-Chen Lee
Keyword(s):  
Liquid Phase ◽  
Temperature Difference ◽  
Moisture Absorption ◽  
Silicon Oxide ◽  
Liquid Phase Deposition ◽  
High Concentration ◽  
Real Process ◽  
Fluorinated Silicon Oxide ◽  
Intermetal Dielectric ◽  
Low K

ABSTRACTTo meet the requirements of low-K and low-stress intermetal dielectric (IMD) for future ULSI devices, a novel temperature-difference liquid-phase deposition (TD-LPD) method is proposed. The deposition solution of supersaturated silicic acid with high concentration of fluorine can be achieved by raising deposition temperature larger than 15 °C from dissolution temperature (0 °C). Because fluorine atoms can easily be incorporated with the technique, TDLPD fluorine-doped SiO2 (FSG) exhibits low-K (∼3.4) and low-stress (∼40MPa) property. In this paper, to study the interaction between TD-LPD FSG and moisture, the FSG is annealed and moisture stressed repeatedly as in a real process. Since K is sensitive to moisture absorption, and the stress is sensitive to the dehydration reaction between Si-OH's, the both are monitored as indices. A feasible mechanism is proposed to explain the variation in K/stress during annealing and boiling cycles.

Effect of Ash Chemistries on TDDB Lifetime of Cu/ULK Interconnects

2005 ◽  
Author(s):  
L. -C. Chen ◽  
J. B. Lai ◽  
J. L. Yang ◽  
Renee Huang ◽  
R. L. Huang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Dielectric Breakdown ◽  
Nitrided Layer ◽  
Plasma Damage ◽  
Ion Migration ◽  
Carbon Doped ◽  
Time Dependent Dielectric Breakdown ◽  
Protection Layer ◽  
Intermetal Dielectric ◽  
Low K

Abstract The effect of ash chemistries, N2/H2 and H2, on time-dependent dielectric breakdown (TDDB) lifetime has been investigated for Cu damascene structure with a carbon-doped CVD ultra low-k (ULK, k=2.5) intermetal dielectric. Two failure modes, interfacial Cu-ion-migration and Cu diffusion through the bulk intermetal ULK were attributed to the TDDB degradation for the H2 ash.The interfacial Cu-ion-migration was the only dominated failure mode for the N2/H2 ash. The nitrogen species in the N2/H2 plasma proved to be capable of forming a nitrided protection layer on the surface of the ULK. This nitrided layer suppressed further plasma damage during the ash process and thus lessened the TDDB degradation by preventing Cu diffusion through the bulk ULK.

Study of SiH4-based PECVD Low-k Carbon-doped Silicon Oxide

2000 ◽  
Vol 612 ◽  
Author(s):  
Hongning Yang ◽  
Douglas J. Tweet ◽  
Lisa H. Stecker ◽  
Wei Pan ◽  
David R. Evans ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Silicon Oxide ◽  
Additional Cost ◽  
Electrical Performance ◽  
Electrical Characteristics ◽  
Carbon Doped ◽  
Doped Silicon ◽  
Low K

AbstractIn previous studies, low-k carbon-doped silicon oxide (SiOC) films were deposited using organosilicon precursor: (CH3)xSiH4−x. In this paper, we present the properties of PECVD low-k SiOC films produced by using conventional SiH4 based gas precursors. The SiH4 based SiOC films have similar gross physical and electrical characteristics to those of (CH3)xSiH4−x based SiOC. Since the precursors are inexpensive, commercially available and convenient to operate for existing tools, the process should not require additional cost as compared with that of PECVD silicon dioxide. We demonstrate the feasibility of integrating Cu with SiOC on damascene interconnection. The evaluation on electrical performance of the Cu/SiOC based damascene structure will be discussed.

Expanding thermal plasma for low-k dielectrics deposition

2003 ◽  
Vol 766 ◽  
Author(s):  
M. Creatore ◽  
Y. Barrell ◽  
W.M.M. Kessels ◽  
M.C.M. van de Sanden
Keyword(s):  
Mechanical Properties ◽  
Electrical Properties ◽  
Silicon Dioxide ◽  
Thermal Plasma ◽  
Carbon Doped ◽  
Novel Materials ◽  
Subsequent Processing ◽  
Doped Silicon ◽  
Low K ◽  
Processing Steps

AbstractAs the need for low-k dielectrics in the ULSI technology becomes urgent, the research primarily focuses on the deposition of novel materials with appropriate electrical properties and on the challenges concerning their integration with subsequent processing steps. In this framework we introduce the expanding thermal plasma as a novel remote technique for the deposition of low-k carbon-doped silicon dioxide films from argon/hexamethyldisiloxane/oxygen mixtures. We have obtained k values in the range 2.9-3.4 for films characterized by acceptable mechanical properties (hardness of 1 GPa).

SiC-Like Phase and Room-Temperature Photoluminescence of Low-K SiOCH Films

2002 ◽  
Vol 737 ◽  
Author(s):  
V. Ligatchev ◽  
T.K.S. Wong Rusli ◽  
B. Liu ◽  
K. Ostrikov
Keyword(s):  
Silicon Oxide ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Rf Power ◽  
Defect States ◽  
Hydrogenated Silicon ◽  
Carbon Doped ◽  
Oxygen Gas ◽  
Power Densities ◽  
Low K

ABSTRACTCarbon-doped hydrogenated silicon oxide (SiOCH) low-k films have been prepared using 13.56 MHz discharge in trimethylsilane (3MS) - oxygen gas mixtures at 3, 4, and 5 Torr sustained with RF power densities 1.3 − 2.6 W/cm2. The atomic structure of the SiOCH films appears to be a mixture the amorphous SiO2-like and the partially polycrys-talline SiC-like phases. Results of the infra-red spectroscopy reflect the increment in the volume fraction of the SiC-like phase from 0.22 − 0.28 to 0.36 – 0.39 as the RF power increment.Steady-state near-UV laser-excited (364 nm wavelength, 40±2 mW) photoluminescence (PL) has been studied at room temperatures in the visible (1.8 eV – 3.1 eV) subrange of photon spectrum. Two main bands of the PL signal (at the photon energies of 2.5 – 2.6 eV and 2.8 − 2.9 eV) are observed. Intensities of the both bands are changed monotonically with RF power, whereas the bandwidth of ∼0.1 eV remains almost invariable. It is likely that the above lines are dumped by the non-radiative recombination involving E1-like centres in the amorphous-nanocrystalline SiC-like phases. Such explanation of the PL intensity dependences on the RF power density is supported by results of experimental studies of defect states spectrum in bandgap of the SiOCH films.

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