Improvement of the correlative AFM and ToF-SIMS approach using an empirical sputter model for 3D chemical characterization

Transcription

1 Improvement of the correlative AFM and ToF-SIMS approach using an empirical sputter model for 3D chemical characterization T. Terlier 1, J. Lee 1, K. Lee 2, and Y. Lee 1 * 1 Advanced Analysis Center, Korea Institute of Science & Technology, Seoul 02792, Korea. 2 Green City Technology Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea Additional text * yhlee@kist.re.kr Supporting Information Fifteen figures, and three tables describing the crucial aspects of the 3D correction, comparing 3D classical correction methods with our suggested method for the reconstruction of simulated structures, and application of our 3D correction method on a metallic multilayer sample and on a diblock copolymer film organized in lamellar structure. Table of Contents A. Theory of 3D correction S1. Description of the influence of the topography in surface characterization (Figure S1) S2. Depth profile obtained for a half-bead structure on substrate (Figure S2) S3. Description of the 3D render effects on ion image and mass spectrum (Figure S3) S4. Diagrams of the cross-sectional view for 3D render surface correction (Figure S4) S5. Segmentation of the 3D render using PCA combining the sputtering information of each phase and the AFM surface topography (Figure S5) B. Simulation of 3D correction S6. Cross-sectional view of the simulated half-bead structures on substrate (Figure S6) S7. 3D topography of half bead structure during the successive sputtering (Figure S7) T1. Parameters of the materials for the simulation of the sputtering (Table S1) S8. Depth profiles of the half-bead structures (Figure S8) C. 3D correction of metallic multilayer sample S9. Correlative images showing the surface of the metallic multilayer sample (Figure S9) S10. ToF-SIMS results of the original data of the metallic multilayer sample (Figure S10) T2. Parameters of the multilayered materials for the simulation of the sputtering (Table S2) D. 3D correction of dps-b-pmma diblock copolymer S11. ToF-SIMS results of the original data of diblock copolymer film (Figure S11) S12. Correlative images showing the surface of the block copolymer film (Figure S12) S13. Topography of diblock copolymer film for the alignment of the image stack (Figure S13) S14. Z-profile of diblock copolymer film (Figure S14) S15. 3D segmentation of the signals using a discriminant method with PCA (Figure S15) T3. Parameters of the diblock copolymer film for the simulation of the sputtering (Table S3) S-1

2 A. Theory of 3D correction Figure S1. Description of the influence of the topography in surface characterization. (a) Show the beam configuration and the object evolution after the successive cycles of sputtering. (b) Display the 2D projections obtained after each analysis time. (c) 2D projection are combined in a 3D stack of slices. (d) The stack render gives an inverted topography of the original object. Figure S1 describes the beam configuration during the surface analysis and the 3D image acquisition. The surface mapping depends to the nature of the interactions (electrons matter, ions matter, ), the type of emitted signals (secondary/backscattered electrons/ions, X-rays, other photons, ) and the properties of the probed materials. Thus, the 3D structuration of an object or the high surface topography can affect the detected signal and can alter the investigations. The analysis beams such as electron beam, ion beam and X-ray beam, are mainly used to probe the extreme surface. For ToF-SIMS analysis in dual beam configuration, the analysis beam is a pulsed ion beam with low current density (around few pa). The sputter gun is composed to a high current density ion beam (few na to few tens na) and permits to erode the top surface of the region of interest. After each surface scan, a 2D mapping projection of the surface is acquired. The combination of all 2D projection gives a virtual stack that provide a 3D volume render of the dataset. Figure S2. Depth profile obtained for a half-bead structure on substrate, (a) when the 3D image corresponds to the reality and (b) when the 3D render presents an inverted topography of the original object. S-2

3 As shown in Figure S2.a, the depth profile obtained for the ideal 3D volume render of a half-bead, describes an increase of the bead signal due to the curve of the object and a sharp interface with the substrate around 25 nm. However, Figure S2.b depicts a divergent depth profile from a simulation of the 3D surface analysis for the previous described sample. The trend of the signals is reversed to the ideal depth profile and the substrate appears to increase from the surface to the end of the depth profile. Then, the interface position is greatly under evaluated, here, around 10 nm. Figure S3. Description of the 3D render effects on ion image and mass spectrum: (a) inverted 3D render generates a higher probability of mass interferences and a complex ion image. Accurate 3D image permits to deconvolute mass spectrum and ion image as function of the region of interest such as (b) the top, (c) the middle and (d) the background of the analyzed object. The accurate correction of the 3D render could permit to minimize the complexity of the mass spectra for each Z-depth position and could permit also a better interpretation of the data, as shown at Figure S3. Figure S4. Diagrams of the cross-sectional view, respectively, (a) for AFM surface topography, (b) for a 3D render obtained by surface analysis where the contour of the interface is marked using Z=0 before and after to have push-up the pixel position, and (c) for adjustment of the 3D render surface using AFM surface topography S-3

4 Figure S5. (a) Identification of the 3D render configuration using Principal Component Analysis to segment the phases inside the 3D volume. (b) Adjustment of the voxel position combining the sputtering information of each phase and the AFM surface topography of the first surface. B. Simulation of 3D correction Figure S6. Cross-sectional view of the simulated half-bead structures on substrate. The structure are respectively, (a) bulk, (b) multilayer, (c) core-shell and (d) bulk with interfacial layer. Materials in red and in blue presents different sputter yields and beam-induced roughness under ion beam bombardment. Figure S7. 3D topography of half bead structure on substrate, respectively, (a) before and (b) after the successive cycles of sputtering simulated to obtain a 3D analysis of the object. The topography after sputtering illustrates the memory effect of the original topography under ion beam bombardment. S-4

5 Material Table S1. Parameters of the materials for the simulation of the sputtering Sputter rate Beam-induced roughness Material A Material B Substrate Figure S8. Depth profiles of the half-bead structures on substrate obtained after simulation of 3D ToF-SIMS analysis, (a) multilayer, (b) core-shell and (c) bulk with interfacial layer. C. 3D correction of metallic multilayer sample Figure S9. (a) Chemical mapping obtained by ToF-SIMS, (b) Topography obtained by AFM and (c) Correlative image showing the surface of the metallic multilayer sample before 3D ToF-SIMS analysis. S-5

6 Figure S10. ToF-SIMS results of the original data, corresponding to, (a) the 3D render, (b) the cross-sectional view and (c) the depth profile of the metallic multilayer sample. Table S2. Parameters of the multilayered materials for the simulation of the sputtering Material Sputter rate Beam-induced roughness Platinum Gold Silicon D. 3D correction of dps-b-pmma diblock copolymer Figure S11. ToF-SIMS results of the original data, corresponding to, (a) the 3D render, (b) the cross-sectional view and (c) the depth profile of dps-b-pmma diblock copolymer film organized in lamellar structure. S-6

7 Figure S12. (a) Topography obtained by AFM and (b) Chemical mapping obtained by ToF-SIMS showing the surface of the dps-b-pmma diblock copolymer film before 3D ToF-SIMS analysis. (c) Correlative image of ToF-SIMS mapping with AFM topography. The dashed-line circles display the regions of double hole asperity present on the film surface. Figure S13. 2D topography of dps-b-pmma diblock copolymer film organized in lamellar structure with hole asperities, respectively, (a) before alignment of the image stack, (b) after alignment of the image stack and (c) from Atomic Force Microscopy. S-7

8 Figure S14. (a) Z-profile of dps-b-pmma diblock copolymer film organized in lamellar structure with hole asperities, corresponding to the extracted profiles from AFM measurements, respectively, (b) of the original surface (red line) and (c) of the sputtered surface after 3D ToF-SIMS analysis (blue line) Figure S15. 3D renders, respectively, (a) for PMMA, (b) for dps and (c) for silicon substrate after segmentation of the signals using a discriminant method with Principal Component Analysis. Table S3. Parameters of the diblock copolymer film for the simulation of the sputtering Material Sputter rate Beam-induced roughness PS PMMA Silicon S-8