AFM Measurements of Adhesion between Actual CMP Slurry Particles and Various Substrates
- PDF / 719,424 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 16 Downloads / 221 Views
W2.5.1
AFM Measurements of Adhesion between Actual CMP Slurry Particles and Various Substrates Yong Liu, Bogdan Zdyrko, Alex Tregub1, Mansour Moinpour1, Mark Buehler2 and Igor Luzinov School of Materials Science and Engineering, Clemson University, SC 29634, U.S.A. 1 Intel Corporation, CMO/FMO, Santa Clara, CA, U.S.A. 2 Intel Corporation, PTD, Hillsboro, OR, U.S.A. ABSTRACT One of the critical parameters in chemical mechanical polishing (CMP) technology is adhesion between abrasive particles and surfaces being polished. Accumulated up to date theoretical and experimental facts insist that development of advanced material removal and cleaning methods requires understanding and evaluation of particle adhesion in these processes. To this end, our research focuses on AFM studies of interaction between the slurry particles and different substrates treated by CMP processes. To conduct adhesion measurements, the particles present in a CMP system and model latex particle were first attached to the surface of silicon wafer covered with monolayer of polymer(s) having high affinity to particles and the silicon wafer. Glass/quartz sphere (10-60 microns) was attached to AFM cantilever with appropriate spring constant. (The sphere represented the surface of material being polished and might be covered with various materials during future investigations.) Next, AFM force volume mode, which utilizes the collection of the force-distance curves over selected surface areas, was used for the adhesion measurements. INTRODUCTION Chemical mechanical polishing (CMP) has been widely accepted for use in planarization of oxide dielectric and metal layers. The technique is vital tool for advanced integrated circuit (IC) manufacturing [1-4]. One of the critical parameters in CMP technology is adhesion between abrasive particles and surfaces being polished. In certain circumstances during CMP, the adhesion forces can be of the same magnitude as or lager than the external force exerted by the polishing pressure [5]. Recently, Zhang and Busnaina [1] proposed new removal rate model incorporating the important contribution of particle adhesion forces. The model prediction was in good agreement with experimental removal rate data. Consequently, the adhesion forces play an important role in the CMP process. When adhesive particle/surface interactions are not optimized in CMP process, formation of surface defects and low or excessive removal rate may be observed. In addition, inter-abrasive particle adhesion causes particle agglomeration that can have detrimental effect on CMP quality [6]. On the other hand, following CMP, slurry particles are not completely detached from the wafers surface. As such, optimization of post-CMP techniques for removal of submicron particles is extremely important. Typically CMP leaves tens of thousand of submicron and micron-size particles on the polished substrate, which must be removed before further processing, or they will adversely impact yield for finished IC [7]. It is clear that particle/wafer adhesion plays a key
Data Loading...
