Electron Beam Induced Decomposition of Palladium Acetate
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ELECTRON
BEAM
T.J.STARK*,
INDUCED
T.M.MAYER**,
DECOMPOSITION
OF
PALLADIUM
ACETATE
P.E.RUSSELL
Center for Advanced Electronic Materials Processing North Carolina State University, Raleigh, NC 27695 *Also at Department of Chemistry University of North Carolina, Chapel Hill, NC 27599 **Sandia National Laboratories, Albuquerque, NM 87185
Abstract, A focused electron beam has been used to selectively decompose sub micron thick films of palladium acetate, Pd(OOCCH3)2, resulting in the formation of 250 0 C. All irradiations at 4 key. by assuming that the C(is) signal remained constant through exposure, and that the annealed sample had no charging. The Pd(3d) peaks shown for the annealed sample- are nearly identical to a Pd standard, indicating the presence of metallic Pd in the 2 Metallic Pd is present at doses below lOOOgC/cm exposed Pd-Ac. and the oxidized Pd has been largely reduced at doses of 2 5000JC/cm . The C (is) feature (not shown) displays two bonding types, C-0 and C-H. The higher binding energy feature associated with C-0 bonding is preferentially depleted upon exposure.
0.8 -o
0.6 0
0.4 a 0.2 0
2
4
6
8 10 12 14 DOSE(10 3 pC/cm 2 )
16
18
-J 0 20
Figure 4. Changes in concentration of C (circle), 0 (triangle) and Pd metal (square) relative to total Pd as the Pd-Ac is exposed. Solid markers are for annealed sample.
169
The relative intensities of C, 0 and Pdo signal to the total The (4). Pd signal in the XPS analysis is represented in figure 0 fraction of the Pd that is in the metallic state, Pd2 , increases ratio The rapidly and then levels out at doses above 2000jC/cm . of C to Pd and 0 to Pd both decrease rapidly and slowly level off The C/Pd ratio of 4.5 and the O/Pd as the dose is increased. ratio of 3.5 for unexposed Pd-Ac may be different from their C buildup expected value of 4 due to impurities on the surface. on the surface is likely to persist throughout exposure and it is difficult to determine whether the XPS measurements are reflecting a surface buildup or are indicative of the bulk. Sputter cleaning the sample results in total decomposition of the However, a surface layers, making interpretation2 difficult. sample that was exposed to 2700oC/cm and annealed to 250°C was sputter cleaned without changing the Pd binding energy, Sputter cleaning indicating that it had been fully decomposed. the annealed sample did change the relative amount of C to Pd from close to 2 down to 0.4, indicating that residual C may be on The solid square and circle in figure 4 represent the surface. the relative amounts of Pd metal and C to total Pd after annealing and cleaning. Product evolution from Pd-Ac during exposure displayed three Immediately distinct time-varying features, shown in figure 5. upon turning on the electron beam the major product CO2 (m/e 44,16) appears. CO2 and CH3 (by inference) appear to be the primary decomposition products resulting from scission of the C-C This is bond and dissociation of the Pd-O ligand bonds. consistent with the immediate appearance of Pd metal and the
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