Effects of Properties and Growth Parameters of Doped and Undoped Silicon Oxide Films on Wear Behavior During Chemical Mechanical Planarization Process

Abstract

Understanding the tribological, mechanical, and structural properties of an inorganic and organic dielectric layer in the chemical mechanical planarization (CMP) process is crucial for successful evaluation and implementation of these materials with copper metallization. Polishing behaviors of different carbon- and fluorine-doped silicon dioxide (SiO2) low dielectric constant materials in CMP process are discussed in this paper. Films were deposited using both chemical vapor deposition and spin-on method. Carbon and fluorine incorporation in the Si–O network weaken the mechanical integrity of the structure and behave differently in slurry selective to SiO2 films. Mechanical properties of the films were measured using depth-sensing nanoindentation technique, and it was found that undoped SiO2 film has the highest and spin-on carbon-doped oxide films have the lowest hardness and modulus values. Wear behavior of the doped SiO2 is studied in a typical SiO2 CMP environment, and results are analyzed and compared with those of the undoped SiO2 films. Coefficient of friction and acoustic emission signals have significant effect on the polishing behavior. Surface of the films are investigated before and after polishing using atomic force microscopy. Roughness and section analysis of the films after polishing show the variation in wear mechanism. Validation of Preston’s equation is discussed in this study. Additionally, different wear mechanisms are presented, and a two body abrasion model is proposed for the softer films.

Model of Particle Contact Area for Friction in Oxide Chemical Mechanical Polishing

“…The average low speed (.001 m/s) coefficient of friction for many data points of typical PU pad material was 0.29. This is virtually the same as the 0.30 to 0.40 reported by Levert(2) 14 and close to the .43 -.45 reported by Sikder 8 for CMP with typical PU pads at typical speeds (∼0.5 m/s). Although the pad asperity to substrate contact is under boundary lubrication, the activity of the particles must be considered further.…”

Study of nanoimprint pattern transfer on hydrogen silsesquioxane

“…After vacuuming the chamber, the pre-press pressure was set as 0.8 MPa by introducing Ar into the chamber during heating. This creep phenomenon under hold periods at maximum load is a characteristic of time-dependent materials, which was also observed by Sikder et al 5,6 The time-dependent characteristics are caused by a viscous response of materials as discussed for the VEP model. A Hitachi S-4000 scanning electron microscopy ͑SEM͒ was used to examine the pattern replication of the imprinted HSQ.…”

“…Sikder et al 5,6 used a nanoindentation technique with a continuous-stiffness-measurement ͑CSM͒ method to test the mechanical properties of low dielectric constant materials. They suggested that the weak mechanical integrity of spin-on siloxane polymers could be regarded as soft polymerlike materials that have time-dependent behaviors.…”

Porous Dielectrics in Microelectronic Wiring Applications

“…FSG films as typically employed have dielectric constants in the K = 3.6–3.8 range. These films are not porous, although density [ 20 ] and modulus [ 20 , 21 ] are reduced compared to SiO 2 .…”