Effects of Surfactants on the Chemical Mechanical Polishing Performance of a-Plane Sapphire Substrates

Abstract

The effects of four different types of surfactants, cetyltrimethylammonium bromide (CTAB, cationic type), sodium dodecylbenzene sulfonate (SDBS, anion type), laurylamidoalkylglycine (NL, amphoteric type), and aliphatic alcohol polyoxyethylene ether (AEO, non-ionic type), on the chemical mechanical polishing (CMP) performance of a-plane sapphire substrates in the range of pH 6-12 using colloidal silica as abrasive particles were studied. The results demonstrated that cationic surfactants promoted the removal of sapphire chips at pH 9-12, while anionic, amphoteric and non-ionic surfactants inhibited the removal of sapphire chips at pH 6-10. The mechanism of material removal in sapphire CMP was discussed through atomic force microscope observation, zeta potential measurements, particle size distribution testing and friction behavior analysis.

Nanomaterials and Equipment for Chemical–Mechanical Polishing of Single-Crystal Sapphire Wafers

“…Therefore, the removal rate of sapphire is positively correlated with the downforce and speed of the equipment. Many researchers have also proved that polishing pressure and rotational speed have important effects on the performance of CMP [53,56,[60][61][62][63][64][65][66]. Table 1 lists the influence of polishing pressure and rotational speed on the polishing efficiency of sapphire in some of the literature [53,56,[60][61][62][63][64][65].…”

“…Many researchers have also proved that polishing pressure and rotational speed have important effects on the performance of CMP [53,56,[60][61][62][63][64][65][66]. Table 1 lists the influence of polishing pressure and rotational speed on the polishing efficiency of sapphire in some of the literature [53,56,[60][61][62][63][64][65]. The quality of the finished surface will be affected by altering the polishing parameters.…”

“…It is not only the type of abrasive that will affect the polishing effect of the polishing material, but the sapphire CMP efficiency will also be affected by altering particle size and concentration [68,[76][77][78][79][80][81][82][83][84]. Table 3 lists the influence of particle size and the concentration of the abrasive on the polishing efficiency of sapphire in some of the literature [68,[77][78][79][80][81][82][83][84].…”

“…It is not only the type of abrasive that will affect the polishing effect of the polishing material, but the sapphire CMP efficiency will also be affected by altering particle size and concentration [68,[76][77][78][79][80][81][82][83][84]. Table 3 lists the influence of particle size and the concentration of the abrasive on the polishing efficiency of sapphire in some of the literature [68,[77][78][79][80][81][82][83][84]. For instance, Wang et al used SiO 2 abrasive with particle sizes of 20, 50, 80, and 100 nm for CMP on sapphire, and found that the MRR of sapphire appeared as a linear relationship with silica diameter and increased steeply from 2.02 µm/h to 3.64 µm/h with particle size increasing from 20 nm to 100 nm (Figure 7A) [68].…”