Surface Modified Alumina Particles and Their Chemical Mechanical Polishing (CMP) Behavior on C-plane (0001) Sapphire Substrate

doi:10.15541/jim20170036

Abstract

Abstract:

To improve the Chemical Mechanical Polishing (CMP) performance of alumina particles in aqueous solution, a suitable modification method was explored. Meanwhile, in order to improve their chemical mechanical performance, alumina particles were surface modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane through silanization chemical reaction with their surface hydroxyl groups and complexation with Al and secondary amine. This work gives a detailed and thorough chemical reaction mechanism that N-(2-aminoethyl)-3-aminopropyltrimethoxysilane grafted onto the surface of alumina. The compositions and structures of the modified alumina particles were characterized by Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results supported that the N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was perfectly grafted onto the surface of alumina particles, which led to the modified alumina particles with better surface chemical and mechanical properties than unmodified alumina particles. Then, CMP performance of the unmodified and modified alumina particles on the sapphire substrate was tested. The results showed that the modified alumina particles exhibited higher material removal rate (MRR) and better surface quality than unmodified alumina particle. The focus is that the modified alumina particles manifested higher MRR at pH 10.00 than the unmodified alumina particles at PH 13.00, which may open a way to reduce corrosion of equipment.

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Key words: modification method, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, chemical mechanical polishing, Chemical Mechanical Polishing (CMP), alumina slurry

CLC Number:

TQ174

WANG Wei-Lei, LIU Wei-Li, BAI Lin-Sen, SONG Zhi-Tang, HUO Jun-Chao. Surface Modified Alumina Particles and Their Chemical Mechanical Polishing (CMP) Behavior on C-plane (0001) Sapphire Substrate[J]. Journal of Inorganic Materials, 2017, 32(10): 1109-1114.

Figures/Tables 11

Fig. 1 FTIR spectra of alumina particles before and after modification

Fig. 2 XPS survey spectra of alumina particles before and after modification

Table 1 Binding energy of abrasives containing before and after modified alumina particles

Elements in sample	Al2p	O1s
Binding energy/eV	74.03 73.08	531.06 530.87

Table 2 Cmposition of elements on the surface of alumina particles before and after modification

Atomic%	Al	O	C	N	Si
Unmodified alumina	30.67	52.44	16.89	0	0
Modified alumina	27.35	46.41	21.19	2.77	2.28

Fig. 3 XPS narrow scan spectra results of element Al2p (a), O1s (b) in modified alumina

Table 3 Binding energy of Al2p

Chemical state	Band energy/eV
(-Si(OCH₃)₂O-)_xAl_y	73.8
AlN	73.1

Table 4 Binding energy of O1s

Chemical state	Band energy/eV
(-Si(OCH₃)₂O-)_xAl_y	531.10
Al₂O₃	530.30

Fig. 4 Chemical reaction schemes for modification process

Fig. 5 COF as a function of polishing time for sapphire substrates polished by unmodified alumina particles and modified alumina particles

Table 5 Surface roughness (Rq) and material removal rate（MRR）by applying before and after modified alumina particles in different pH

pH	Type of particles	MRR (0.0001 g/30 min)	Before polishing R_q Roughness/nm	After polishing R_q Roughness/nm
10.00	Pure alumina	46	0.968	0.610
10.00	Modified alumina	127	0.610	0.329
10.00	Modified alumina	139	0.981	0.315
13.00	Pure alumina	93	0.916	0.552
13.00	Modified alumina	122	0.552	0.311

Fig. 6 (a, b, f) AFM morphologies of sapphire substrate before polishing; (c) polished by pure alumina particles at pH 10.00; (d) polished by modified alumina particle (using sapphire substrate polished by pure alumina particles (c)) at pH 10.00; (e) polished by modified alumina particle at pH 10.00; (g) polished by modified alumina particle at pH 13.00; (h) polished by pure alumina particles (using sapphire substrate polished by pure alumina particles (g)) at pH 13.00

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