Chemical mechanical polishing (CMP) has become one of the most important technologies for producing nanoscale semiconductor devices because it meets the stringent requirements for ever increasing integrated intensities and yields. CMP process has been widely used to obtain the global planarization of inter-metal dielectric (IMD) layers, inter-layer dielectric layers (ILD) and pre-metal dielectric (PMD) layers. In general, chemical compositions and abrasives of the slurry play a very important role in the removal rate and within-wafer non-uniformity for global planarization ability of CMP process. The conventional slurry consists of abrasive particles of the solid state
suspended in a liquid state chemical solution. The abrasive in the slurry transfers
mechanical energy to the surface being polished and plays a key role in its material
removal. In the manufacturing process for ULSI chip, the abrasive of widely used slurry
is silica (SiO2) and alumina (Al2O3). Ceria (CeO2) has been more commonly used for
glass polishing, and recently for oxide films for shallow trench isolation (STI) structure.
Through chemical reaction and mechanical action, the abrasive-liquid interaction plays
an important role in determining the optimum abrasives type and size, their shape and
concentration. The slurry was designed for optimal performance which produced
reasonable removal rates, acceptable polishing selectivity with respect to underlying
layer, low surface defects after polishing, and good slurry stability. One of the most
critical problems is the higher cost of consumables (COC) such as pad, slurry, backing
film, and pad conditioner which accounts for over 70% of cost of ownership (COO).
Since a sufficient amount of slurry is required to get a higher removal rate (RR) and
lower within-wafer non-uniformity (WIWNU), there have recently been lots of studies
on the reduction of slurry consumption since the cost of the slurry is about 40% of COC.
Total slurry revenues will grow at a CAGR of 8.2% between 2008 and 2014. Factored
into the changing landscape between low cost ILD slurry, which is on the decline in
relation to high-priced metal and ceria-based STI slurry. Revenues generated will from
$874 million in 2008 to $1,402 million in 2014. Volume of slurry will grow at a CAGR
of 16.8%, from 1.4 million 55 gallon drums in 2008 to 3.6 million in 2014. In this paper, we have studied the CMP characteristics of mixed abrasive slurry (MAS) retreated by
adding of Ceria (CeO2) abrasives within 1:10 diluted silica slurry (DSS). We focused on
how these mixed ceria abrasives affect the material removal in order to determine the
optimal recipe conditions through the correlation between the mixed contents of ceria
abrasives and CMP performances in our self-developed. As a result, the oxide CMP
process using diluted mixed abrasive slurry has problems of higher material removal rate
at wafer center. But, we solved the questions in consecutive order by pH control and
slurry dispersion time. Finally, our proposed ceria-MAS can be useful to save a slurry
consumption of high cost since we used 1:10 diluted silica slurry. Although, under the
situation of present CMP technology, our self-developed slurry cannot apply in the chip
fabrication process of semiconductor industries, the saving of high-cost slurry is still
fascinated by R&D institute and experimental laboratory of university.