Joost Waeterloos

Surface characterization of a low dielectric constant polymer-SiLK* polymer, and investigation of its interface with Cu

The integration of copper and new low dielectric constant materials is a fundamental challenge to be met for further miniaturization of high speed integrated circuits. In this preliminary work, core level x-ray photoelectron spectroscopy (XPS) has been used for the first characterization of the surface composition of Dow Chemicals SiLK* semiconductor dielectric (*trademark of the Dow Chemical Company), its behavior during annealing in vacuo, and its interface formation with thermally evaporated copper in situ. The fully conjugated SiLK* resin shows a C is spectrum with intense shake-up structures, quite similar to those of polystyrene; a small amount of oxygen is detected. Upon annealing in ultrahigh vacuum (7.10(-9) Pa) no significant outgassing is observed; no noticeable change in intensity, width, position of the C 1 s and O 1 s core level peaks or satellite structures is measured. After annealing, the interface formation between SiLK* dielectric and copper has been characterized as a function of incremental coverages from 0.5 to 10 Angstrom of Cu. While the XPS C is spectrum shows only a normal intensity decrease, the Cu 2p(3/2) levels shift from a high binding energy to a purely metallic value: this is interpreted as the formation of small Cu clusters, evolving to a more continuous layer for higher Cu coverage. Annealing in vacuo of the as-prepared Cu(10 Angstrom)-SiLK* interface at 400 degrees C for 1 h does induce an increase of the carbon signal, attributed to further coalescence of copper in metallic clusters

Post patterning meso porosity creation: a potential solution for pore sealing

The creation of meso porosity in single damascene structures after patterning has been investigated to facilitate the sealing of the sidewalls by iPVD barriers. The dielectric stack consists of developmental porous SILK (v7) resin (SiLK is a trademark of The Dow Chemical Company) and a chemical vapor deposited hard mask. Porous SILK (v7) resin was selected since the temperature of vitrification of the material is lower than the temperature of porogen burn out. Creation of meso porosity after patterning results in smooth trench sidewalls, leading to an improved iPVD barrier integrity, as opposed to the conventional process sequence, which gives rise to large, exposed pores at the sidewall.

Integration feasibility of porous SiLK* semiconductor dielectric

The feasibility of integrating a SiLK* Semiconductor Dielectric film (*trademark of The Dow Chemical Company) that contains closed pores was studied using a single damascene test vehicle. The study focussed on tool qualification, process set-up and single damascene feasibility to demonstrate technology extendibility. The results indicate that only minor changes have to be made to the process conditions when transitioning from a dense to a porous SiLK* film.

Process integration induced thermodesorption from SiO2/SiLK resin dielectric based interconnects

The thermodesorption from SiO2/SiLK resin dielectric assemblies at various stages of interconnect fabrication are studied by mass spectrometry. Species desorption from such an assembly is governed by the intrinsic material properties and the process step history, such as patterning chemistry and by environmental contamination. The thermodesorption of an as-cured SiLK resin film is compared to the desorption of species after different process steps. It is shown that as cured SiLK films contain very low amounts of moisture and volatile organic compounds. The plasma-enhanced chemical vapor deposition SiO2 hardmask is the main source of moisture in the SiO2/SiLK resin dielectric stack. Annealing at T⩾350 °C in both vacuum and nitrogen ambient conditions drastically reduces the species desorption. The origin and the kinetics of the desorbed species are described.

Integration of a low permittivity spin-on embedded hardmask for Cu/SiLK resin dual damascene

The feasibility of integrating a low permittivity spin-on hardmask (SoHM) into a Cu dual damascene structure using SiLK* Semiconductor Resin (*trademark of The Dow Chemical Company) has been investigated. The study focussed on the replacement of the embedded etch stop deposited by chemical vapor deposition (CVD) by a low permittivity inorganic film deposited by traditional spin coating. The evaluation was performed using an existing damascene test vehicle. The etch selectivity was evaluated by applying different SoHM thicknesses and etch times. The patterning chemistry used was O/sub 2//N/sub 2/ based, in a high density TCP etch tool. The electrical data collected indicated no significant yield difference when using an embedded SoHM. The integrated k value of the SoHM film is 3.2, as compared to /spl sim/4.0 for SiO/sub 2/ films.

Etch process development for FLARE/sup TM/ for dual damascene architecture using a N/sub 2//O/sub 2/ plasma

In this article, the feasibility of via and trench etch of FLARE/sup TM/, a low-k organic material product from AlliedSignal Inc. in dual damascene architectures for 0.25 /spl mu/m applications is described. The effects of O/sub 2/ concentration and flow rate on the etch rate and the etch profile of FLARE/sup TM/ during etching in oxygen reactive ion etch plasmas have been studied. Best via and trench profiles are obtained for a 25/5 nitrogen-to-oxygen ratio; no undercut of the hard mask is observed at a good etch rate. The feasibility of via filling with a low temperature W process and Cu fill of the trenches in a damascene structure has been demonstrated.