In this work, a novel low dielectric constant (low-k) pore sealing approach was engineered by depositing firstly a sub-2 nm SAMs and then a 3 nm TiN barrier film. The low-k film was pretreated by plasma to introduce hydroxyl groups onto the surface, followed by SAMs deposition. Then a TiN film was deposited from tetrakis(dimethylamino)titanium (TDMAT) via ALD as a dielectric barrier. Penetration of Ti atoms into low-k was measured and used to evaluate the sealing ability of SAMs. For the samples covered with SAMs, around 90% reduction of Ti atoms penetration was achieved. The pore radius was reduced to below 0.5 nm after the barrier deposition. The ∆k after pretreatment and after SAMs are 0.1 and 0.16, respectively.

The results of recent investigations show that after UV curing of CVD SiCOH low-k films deposited with organic material (porogen) some amount of the porogen remains in the cured films in the form of non-volatile graphitized phase, known as “porogen residue”. These residues could influence leakage current and reliability. The goal of the present work is investigation of the different parameters of UV curing that can influence amount of the porogen residue. In this work we focused generally on the study of the amount of porogen residues as function of the wavelength of curing light and the porosity of the material (amount of deposited porogen). To study the curing dependence on the wavelength, we compared optical properties (measured by spectroscopic ellipsometry) and IR adsorption (measured by FTIR) of samples cured by 172 nm monochromatic light (lamp A) with samples cured by broadband source with wavelength more than 200 nm (lamp B). To understand how the amount of porogen residue depends on the amount of deposited porogen (porosity), three films with different k-value were deposited: a film with k = 3 deposited without porogen and two porogen-based low-k with target k-value of 2.5 and 2.3. Furthermore, taking into account that He/H2 plasma effectively removes the porogen residues from porous films without any plasma damage of the matrix material, we exposed the films to that plasma. Then these films were cured by broadband lamp at different temperatures and amount of porogen residues was measured by ellipsometry. It was found that He/H2 plasma cannot fully remove the porogen and causes film shrinkage. The Subsequent UV curing does not produce significant changes.

A multiprocess CVD system with the following main features is designed and constructed: the wafer holder is made of a Si wafer with diameter larger than the process wafers. This larger holder produces a better temperature uniformity on the process wafer. A good thermal contact between holder and process wafer is obtained by an electrostatic clamp. The holder supports the process wafer facing down. A remote plasma is produced in a small chamber inside the process chamber. The 100 KHz RF frequency keeps the system very simple and cheap while still reasonable ionization is achieved. SiO2 films were deposited using SiH4 and O2 with and without remote plasma of O2. At low temperatures and 1.5 Torr, process activation energies of about 0.9 and 0.3 eV were obtained respectively.