High-performance CMP Slurry with Inorganic/Resin Abrasive for Al/Low k Damascene
- PDF / 576,099 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 97 Downloads / 205 Views
High-performance CMP Slurry with Inorganic/Resin Abrasive for Al/Low k Damascene Hiroyuki Yano, Yukiteru Matsui, Gaku Minamihaba, Nobuo Kawahashi1, Masayuki Hattori1, Semiconductor Company, Toshiba Corp., Yokohama, Japan 1 Fine Electronic Research Laboratories, JSR Corp., Yokkaichi, Japan ABSTRACT CMP slurry with inorganic/resin abrasive was investigated for the Al/low k damascene wiring. [1] The slurry showed less scratching, higher polishing rate and better planarity. These advantages are attributable to the elasticity of the resin. The soft resin particle behaves as a cushion and prevents the scratching caused by agglomerated inorganic particles and foreign material. The springy feature of the resin particle increases the selectivity of removal rate at convex portions and concave portions. Furthermore, the pressure is loaded to the Al film surface effectively through the resin particle and higher CMP rate can be achieved even without chemicals such as oxidizers and acids. [2] This chemical free polishing would be the advantageous for preventing the corrosion of Al. INTRODUCTION Damascene is an attractive wiring method for process simplification and yield enhancement. But CMP is subject to problems concerning scratching, planarity and corrosion. Meanwhile, low dielectric constant (low k) material is going to be introduced as the interlayer dielectrics (ILD) to improve device performance. However, the lack of the mechanical strength of low k material increases concerns regarding scratching and planarity. So, a novel CMP slurry abrasive is proposed. EXPERIMENT In Al/low k damascene wiring, 2-step CMP was employed as shown in Figure 1. In the first step, CMP removes aluminum and polishing stops on niobium liner. In the second step, niobium liner is removed. Slurry for the first step CMP consists of 200nm particle size resin and 20nm primary particle size alumina. Polishing pad was IC-1000/SUBA-400. In the second step CMP, silica/resin composite particle was used as abrasive and the pad was Politex. Polishing was carried out on an EBARA EPO-222. CMP removal rate was determined by 4-point probe resistance measurement using 8-inch wafer with blanket Al-Cu alloy film. For the patterned wafer tests, the test structure with the line width ranging from 0.2um to 100um was used. ILD was JSR-LKDTM and the metal stack
Al
LKDTM 1st-step CMP
2nd-step CMP
Fig.1
M2.4.1
Nb
2-step aluminum CMP process
consisted of 800nm-thick sputtered Al-Cu alloy and 15nm-thick sputtered niobium. Dishing and erosion was determined by profile meter and by optical interference measurement. Surface defects were measured by optical microscope, SEM and KLA. RESULTS AND DISCUSSION First-step CMP 1.CMP Rate Figure 2 shows the CMP removal rates for blanket aluminum for three types of slurry. The removal rate of aluminum is less than 20nm/min for the slurry only containing 3wt% alumina and almost zero for the slurry only containing 0.5wt% resin. But the mixture of 3wt% alumina and 0.5wt% resin (alumina/resin) showed a removal rate of more than 200nm
Data Loading...
