Development of a Pad Conditioning Process for Interlayer Dielectric CMP Using High-Pressure Micro Jet Technology

Abstract

Diamond conditioning was compared to an alternative method, namely high-pressure micro jet ͑HPMJ͒ conditioning, through a series of interlayer dielectric chemical mechanical planarization ͑ILD CMP͒ marathon tests. The two systems were compared individually and in combination on the basis of ILD removal rate ͑RR͒, coefficient of friction ͑COF͒, and the physical appearance of the pad surface ͑both on the top areas as well as inside the grooves͒. Results indicated that diamond conditioning alone was effective in causing RR and COF stability during extended runs, but it could not clean the slurry residues and other by-products from the surface of the pad ͑especially inside the grooves͒. Results also showed that HPMJ conditioning was able to effectively clean the pad surface, despite not providing enough energy to abrade the surface of the pad and maintain constant RR and COF during extended polishing. Based on these findings, a new pad conditioning method based on a combination of diamond and HPMJ conditioning was proposed. Results showed that this new method allowed for stable polish results in terms of RR and COF during extended marathon runs, and also yielded substantially residue-free surfaces, which could extend pad life and reduce wafer-level defect.

Generation of Pad Debris during Oxide CMP Process and Its Role in Scratch Formation

“…Figures 3a-3c show the SEM images of pad debris at magnifications of  300,  500, and  20,000, respectively. 1,22,32,33 The normalization of the removal rate can be observed in Fig. The agglomeration of pad debris can be seen very clearly in Figs.…”

“…It can be observed that a wide range of particles were present starting from 0.2 to 300 lm. 1,22,29,32 This could be attributed to the filling of pad pores with the polishing residue to make the pad surface smooth, which is generally termed "pad glazing." To understand this ambiguity, SEM images of collected pad debris were taken.…”

“…5,25,26,28,30,32 During in situ conditioning, the pad is conditioned simultaneously with the wafer polishing, whereas in the case of ex situ conditioning, the pad is conditioned only after polishing the wafer. 5,25,26,28,30,32 During in situ conditioning, the pad is conditioned simultaneously with the wafer polishing, whereas in the case of ex situ conditioning, the pad is conditioned only after polishing the wafer.…”

Characterization of Slurry Residues in Pad Grooves for Diamond Disc and High Pressure Micro Jet Pad Conditioning Processes

“…Details of the HPMJ pad conditioning technique can be found elsewhere. 5,6) During conditioning, the HPMJ system sprays high-pressure water droplets ranging from 3 to 30 MPa onto a pad to rinse off slurry residue and remove embedded slurry particles. Results show that slurry residue inside pad grooves that are unable to be removed with diamond disc pad conditioning can be cleaned off by HPMJ pad conditioning.…”

“…Results show that slurry residue inside pad grooves that are unable to be removed with diamond disc pad conditioning can be cleaned off by HPMJ pad conditioning. 6) In this study, the effectiveness of slurry residue and by-product removal inside pad grooves is characterized using UV-enhanced fluorescence (UVEF) technique. Previously, dual emission UVEF (DEUVEF) technique has been used to measure fluid film thickness, pH, and temperature utilizing the fluorescence properties of two dyes to minimize errors caused by fluctuations of factors such as excitation source intensity, surface reflectivity, and background noise.…”