Characterization of Flexible Low-k Dielectric SiCOH Films Prepared by Plasma-Enhanced Chemical Vapor Deposition of Tetrakis(trimethylsilyloxy)Silane Precursor.

SiCOH thin films were deposited on rigid silicon (Si) wafers and flexible ITO/PEN substrates via plasma-enhanced chemical vapor deposition at room temperature using a tetrakis(trimethylsilyloxy)silane (TTMSS) precursor. Different chemical compositions of hydrocarbon and Si-O bondings were obtained depending on substrate types and deposition conditions. The main chemical compositions of the as-deposited films were observed as C-Hx (x = 2, 3) stretching, Si-CH3 bending, Si-O-Si stretching, and H-Si-O bending/Si-CH3 stretching modes. With regard to the as-deposited films, the dielectric constant increased from 1.83 to 3.45 when the plasma power increased from 20 to 80 W and the lowest leakage current of 1.76×10-4 A/cm² was obtained at the plasma power of 80 W. After bending tests with 1000, 5000, and 10000 bending cycles, the dielectric constants of the SiCOH films increased and leakage currents decreased. The structures of the SiCOH films after the bending tests were highly complicated with a variety of chemical bonding combinations. Higher peak intensity and peak area of main chemical bonding were obtained with the increased bending cycles, resulting in the increase in dielectric constants. It should be noted that the film with small changes in peak area fractions of the bending and stretching modes showed good electrical and mechanical stabilities after bending tests.

Effects of He/H2 Plasma Treatment on Properties of SiCOH Films Deposited with the 1,1,1,3,5,7,7,7- Octamethyl-3,5-Bis(Trimethylsiloxy) Tetrasiloxane Precursor.

Low-dielectric-constant SiCOH films fabricated using plasma enhanced chemical vapor deposition (PECVD) are widely used as inter-metallic dielectric (IMD) layers in interconnects of semiconductor chips. In this work, SiCOH films were deposited with 1,1,1,3,5,7,7,7-octamethyl-3,5-bis(trimethylsiloxy)tetrasiloxane (OMBTSTS), and plasma treatment was performed by an inductively coupled plasma (ICP) system with mixture of He and H2. The values of relative dielectric constant (k) of the as-deposited SiCOH films ranged from 2.64 to 4.19. The He/H2 plasma treatment led to a reduction of the k values of the SiCOH films from 2.64-4.19 to 2.07-3.94. To investigate the impacts of the He/H2 plasma treatment on the SiCOH films, the chemical compositions and structures of the as-deposited and treated the SiCOH films were compared by Fourier transform infrared spectroscopy. The experimental results indicate that the k value of the SiCOH films was decreased, there was a proportional increase in pore-related Si-O-Si structure, which is commonly called the cage structure with lager angle than 144°, after He/H2 plasma treatment. The He/H2 plasma treatment was considered to have reduced the k value by forming pores that could be represented by the cage structure. On the other hand, the leakage current density of the SiCOH films was slightly degraded by He/H2 plasma treatment, however, this was tolerable for IMD application. Concludingly the He/H2 plasma treated SiCOH film has the lowest relative dielectric constant (k~2.08) when the most highly hydrocarbon removal and cage structure formation increased.

Low-k SiCOH Films Deposited with a Single Precursor 1,1,1,3,5,7,7,7 Octamethyl-3,5-Bis(trimethylsiloxy) Tetrasiloxane by Plasma Enhanced Chemical Vapor Deposition.

Low-dielectric-constant SiCOH films were deposited by plasma-enhanced chemical vapor deposition using 1,1,1,3,5,7,7,7-octamethyl-3,5-bis(trimethylsiloxy)tetrasiloxane (OMBTSTS) as a single precursor, and the characteristics were investigated. The relative dielectric constant (k) of the SiCOH films declined gradually from 3.57 to 1.90 with decreasing plasma power. The film with the lowest k, deposited at the lowest power of 10 W, showed the lowest leakage current density, with adequate mechanical strength (hardness: 0.98 GPa and elastic modulus: 8.56 GPa) for application in multilevel semiconductor interconnects. The chemistry of the OMBTSTS films was characterized by Fourier transform infrared spectroscopy to study the relation between the chemical and dielectric properties. The dielectric properties, such as the k value and leakage current density, could be explained by a quantitative relation between the Si-O stretching bond and hydrocarbon-related bonds, such as CH3 and Si-CH3 bonds, with lower polarizability in the SiCOH film. The refractive index, which is directly linked to the density of the film, was also investigated by ellipsometry. We consider OMBTSTS a promising candidate as a single precursor for fabricating low-k SiCOH films in the plasma-enhanced chemical vapor deposition system.

Relation of Dielectric Constants and Chemical Structures of Low Dielectric Constant SiCOH Films Deposited by Using Octamethylcyclotetrasiloxane and Tetraethylorthosilicate Precursors.

In case of the conventional SiCOH films, a post-deposition process was used to make pores by vaporization of porogen (e.g., hydrocarbon) for decreasing the dielectric constant. However, the authors intended the deposition of the SiCOH films, which does not need the post-deposition process to form the pores by using the dual precursors having different structures. The octamethylcy-clotetrasiloxane (OMCTS) and tetraethylorthosilicate (TEOS) have different structures which were of the ring shape and the linear shape, respectively. The OMCTS and TEOS were used to fabricate the plasma polymerized low dielectric constant SiCOH film by using the plasma enhanced chemical vapor deposition system in this work. A ratio of OMCTS and TEOS was adjusted by controlling flow rates of precursor carrier gases into the process chamber. The SiCOH films, which were deposited with dual precursors, showed the very low dielectric constants (relative dielectric constant k 2.06 and 2.09) at plasma power of 10 W. All the fabricated SiCOH films showed the proper leakage current densities below 10-6 A/cm-2 at 1 MV/cm as the intermetallic dielectric material. The SiCOH films were investigated to study the relations between dielectric constants and chemical structures by using Fourier transform infrared spectroscopy. The formation of pores inside the SiCOH films was studied through the relation between Si-O-Si peaks, including network, suboxide and cage peaks, and the dielectric constant.

Effects of Plasma Polymer Films and Their Deposition Powers on the Barrier Characteristics of the Multilayer Encapsulation for Organic Devices.

Organic electronic devices (OEDs) are quite suitable for use in flexible devices due to their ruggedness and flexibility. A number of researchers have studied the use of OEDs on flexible substrates in transparent, flexible devices in the near future. However, water and oxygen can permeate through the flexible substrates and can reduce the longevity of OEDs made from organic materials, which are weak to moisture and oxygen. In order to prevent the degradation of the OEDs, researchers have applied an encapsulation layer to the flexible substrates. In this study, Al2O3/plasma polymer film/Al2O3 multi-layers were deposited on polyethylene-naphthalate substrates through a combination of atomic layer deposition and plasma-enhanced chemical vapor deposition (PECVD). The plasma polymer film, which is located between the Al2O3 films, is deposited via PECVD with the use of a tetrakis(trimethylsilyloxy)silane precursor. The power of the plasma deposition varied from 10 to 50 W. The hydrophobicity of the plasma polymer film surfaces was investigated by measuring the water contact angle. The chemical structures of the plasma polymer films were measured via ex-situ Fourier transform infrared analysis. The permeation curves of the various films were analyzed by performing a calcium (Ca)-test.