Sputter Crater Research Articles

Laser-assisted plasma formation and ablation of Cu in a controlled environment

In this paper, we explore the surface and mechanical alterations of Cu, as well as the parameters of laser-assisted plasma and ablation. The irradiation source is a Nd: YAG laser with a constant irradiance of 1.0 GW/cm2 (1064 nm, 55 mJ, 10 ns, 10 Hz). Physical parameters such as electron temperature (Te) and electron number density (ne), sputtering yield (yield), ablation depth (depth), surface morphology (morphology), and hardness (Vickers) of laser irradiated Cu are evaluated using instruments such as a Laser Induced Breakdown Spectrometer (LIBS), Quartz Crystal Microbalance (QCM), Optical Emission Microscope (OEM), Scanning Electron Microscope (SEM), and Vicker's hardness tester. These physical characteristics have been studied in relation to changes in pressure (from 10 torr to 100 torr) and the composition of two inert ambient gases (Argon and Neon). Pressures of Ar and Ne are found to enhance the emission intensities of spectral lines of Cu, Te, and ne, as well as the sputtering yield, crater depth, and hardness of laser ablated Cu, to a maximum at 60 torr, after which they decrease with subsequent increases in pressure up to 100 torr. Increases in pressure up to 60 torr are connected with plasma confinement effects and increased collisional frequency, whereas decreases in pressure between 60 and 100 torr are ascribed to shielding effects by the plasma plume. All numbers are also found to be greater in Ar compared to Ne. In Ar, laser-ablated Cu reaches a maximum of 15218 K, 1.83 × 1018 cm−3, 8.59 × 1015 atoms/pulse, 231 m, and 147 HV, whereas in Ne, it reaches a maximum of 12000 K, 1.75 × 1018 cm−3, 7.70 × 1015 atoms/pulse, 200 m, and 116 HV. Ar is more likely than Ne to develop surface features such as craters, distinct melting pools with elevating edges, flakes, cones, etc. It is also shown that there is a significant association between the outcomes, with an increase in Te and ne being responsible for a rise in sputtering yield, ablation depth, surface morphology, and surface hardness. These findings have potential uses in plasma spectroscopy for materials science and in industrial applications of Cu.

Insights into the effect of hollow cathode with external injection of fast ions in a sputter-type negative ion source

In sputter-type negative ion sources, the negative ion currents and ionization efficiencies are very dependent upon the creation of a sputter crater and formation of an intense plasma glow. This effect has many similarities with the well-known phenomena of hollow cathode discharges (HCDs). This paper discusses the phenomenological model related to conventional HCDs, including modes with injection of external energetic particles. We propose that HCDs play a major role in sputter-type negative ion sources. In this study, we evaluate the phenomenology of a discharge with a hollow cathode and derive an analytical formula that defines the neutral particle density inside the cathode cavity and substantiates how the classic HCD occurs in sputter-type negative ion sources. The cathode pit geometry was revealed by optical microscopy. Volt–ampere characteristics were investigated in order to compare it to typical discharges with hollow cathodes. In sputter-type negative ion sources, known as SNICS, discharge characteristics and observed light glow inside the cathode pit after its formation were very similar to data published on HCDs. The HCD phenomenon explains how the cathode current increases by orders of magnitude after creation of the cathode pit. The HCD effect in SNICS and similar sputter sources compliments existing mechanisms of negative ion production, especially ion pair production close to the cathode surface due to low energy ionization based on the collision–radiation model. The wealth of information accumulated over the last century on HCDs can be used to describe and explain the phenomenology of physics and operation of sputter negative ion sources.

Influence of temperature and sputter source on Cu(In,Ga)Se2 SIMS depth profiles

The thin‐film photovoltaic technology based on Cu(In,Ga)Se2 (CIGS) has reached high conversion efficiencies exceeding 23%. The gallium gradient in the bulk and the amount of alkali metals in and between CIGS grains strongly affect the cell performance and therefore need to be accurately measured and quantified. ToF‐SIMS is well suited for this task, but the spatial resolution is strongly influenced by the measurement parameters, especially at the required micrometer and nanometer scales. Such highly resolved measurements on CIGS surfaces are challenging. For instance, small copper aggregations occur in SEM images recorded after a focused ion beam (FIB) cut and change the energy‐dispersive spectroscopy (EDS) results. SIMS systems that use an argon ion source generate Cu lamellas, which also influence the measurement. Both effects result from preferential sputtering. Cooling with liquid nitrogen can minimize this negative effect for both techniques. Recent developments in SIMS systems provide more options to avoid these effects. New sources, like the Bi liquid metal gun and cluster guns, are available. However, a systematic investigation on the effect of the ion sources on the sputter craters and the resulting measurement of CIGS absorber is necessary to choose an adequate setup. Thus, we performed a comparison of four different ion sources (argon ion gun, oxygen gun, cesium metal gun, and oxygen cluster gun) and measured CIGS depth profiles at three temperatures [−120°C, −50°C, and room temperature (RT)]. We investigate the influence of these conditions not only on the resulting SIMS depth profile and quantification but also on the morphology of the sputter crater.

Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

Electronic sputtering of solid N[formula omitted] by swift ions

Most sputtering yield measurements for solid N2 are reported for stopping powers lower than 10−13eV cm2/molecule. We measured the sputtering yield for solid N2 at stopping powers, in the electronic regime, above 10−12eV cm2/molecule, extending the range of such measurements by more than an order of magnitude, using a 33 MeV 58Ni9+ swift heavy ions beam. The evolution of the thin N2 ice films was monitored in-situ by mid-infrared spectroscopy (FTIR) during irradiation. As N2 is only weakly infrared active, and can be hardly monitored directly via an infrared absorption mode in such experiments, we use the Fabry–Perot interference fringes of the ice film to evaluate, via an optical model, the erosion of the N2 film as a function of ion fluence. A sputtering model including several sputtering crater shapes is developed and tested against experimental data. We derive the sputtering yield for a semi-infinite N2 ice film and its dependence with the ice thickness for thin film conditions, monitoring the N2 ice sputtering depth. We combine the results with previous measurements at lower stopping powers to derive the electronic sputtering of solid N2 over a large stopping power range.

Effects of ion sputtering on plutonium surfaces

Scanning tunneling microscopy has been performed on an electro-polished gallium-stabilized delta-phase plutonium sample under ultra-high vacuum conditions. The images obtained were used to measure surface roughness as ion sputtering and annealing was applied to the plutonium sample. It was demonstrated that sputter/anneal cycles progressively increased the surface roughness of the plutonium. Additionally, Auger and scanning tunneling spectroscopy measurements revealed an initially unstable and dynamically changing surface that became increasingly stable as sputter/anneal cycles were applied. The stabilized surface region contained within the sputter crater was observed to be unchanged for up to 17 months after the final sputter anneal cycle.

Is Nickel Hydroxide Charging Only Skin-Deep?

The depth of charging in Ni(OH)2-coated electrodes treated with paraffin wax to remove porosity has been investigated using time-of-flight secondary-ion mass spectrometry after charging and discharging in deuterated solvent at pH 14. The proportion of deuterium uptake was found to be dependent on the number of charge/discharge cycles, showing that the measured deuterium signal was indeed dependent on the electrochemical redox activity of the sample. Sputter craters were characterized using atomic force microscopy to find the sputter rate. This then allowed the maximum depth of charging to be found to be approximately 20 nm. This confirmed a surface “skin” in which charging occurs with the rest of the bulk inactive.

Fluence-dependent sputtering yield measurement, surface morphology, crater depth, and hardness of laser-irradiated Zr in N2 and Ne environments

Fluence-dependent sputtering yield measurements, surface morphology, crater depth, and hardness of laser-irradiated Zr in N2 and Ne environments have been investigated by employing an Nd:YAG laser (532 nm, 6 ns, 10 Hz). The targets were exposed to laser pulses at various fluences ranging from 16 J cm−2 to 60.8 J cm−2 under the N2 and Ne environments at a pressure of 10 Torr. Various features of irradiated targets, such as sputtering yield measurement, surface morphology, crater depth, chemical composition, and microhardness, are analyzed by quartz crystal microbalance (QCM), scanning electron microscope (SEM), optical microscope, energy dispersive x-ray spectroscopy (EDX), and Vicker microhardness tester techniques, respectively. QCM measurements reveal that the sputtering yield increases with increasing the fluence in both N2 and Ne environments. However, the values of sputtering yield are slightly higher in the case of N2 as compared to Ne. SEM analysis reveals the formation of cones, cavities, periodic ridges, and droplets at the central ablated areas, whereas the periodic ridges, cones, droplets, clusters, and agglomerates are formed at the inner boundaries of laser ablated Zr in both N2 and Ne. Distinct grain growth is observed at the outer boundaries in both environments. The characteristic features which are only present on Zr-irradiated surfaces in the case of N2 are cavities and in the case of Ne are droplets, clusters, and agglomerates. It is revealed that the surface structural growth is strongly dependent upon the laser fluence and nature of the ambient environment. The crater depth of laser-irradiated Zr is measured by using depth profilometry of an optical microscope. The higher observed values of sputtering yield and crater depth of laser ablated Zr in the case of N2 as compared to Ne are well correlated with distinct surface structures. EDX spectroscopy analysis reveals the nitride formation in the case of laser irradiation of Zr in a N2 environment. The Vicker microhardness tester reveals that the microhardness increases with increasing fluence under both environments; however, it is higher in Ne as compared to a N2 environment. Microstructured/nanostructured Zr can be highly useful in various advanced technological applications, e.g., in electronic, mechanical, fluidic, and optical devices. ZrN can be used as a hard and protective coating on mechanical tools as well as decorative coatings and diffusion barrier in p+/n junctions. The Zr plasma can be used as a source of thin film deposition as well as ion/electron implantation.

Laser sputtering of Zr under Ar and O2 environments explored by quartz crystal microbalance and SEM analysis

AbstractThe effect of laser fluence and nature of ambient environments on the sputtering yield, surface modifications, crater depth, UV-visible absorption spectra, chemical composition, and micro hardness of Zr has been investigated. Nd: YAG laser (532 nm, 10 Hz, 6 ns) at different fluences varying from 16 to 60.8 Jcm−2was employed as an irradiation source. All measurements are performed under two ambient environments of Ar and O2at a constant pressure of 10 Torr. Quartz crystal microbalance has been employed for the measurement of sputtering yield of laser irradiated Zr. It is revealed that sputtering yield increases monotonically with increasing fluence under both environments however, it is higher in Ar as compared to O2environment. Scanning electron microscope (SEM) has been used to explore the surface morphology. SEM analysis exhibits the formation of cones, ridges, and cracks at the central ablated areas whereas, laser-induced periodic surface structures, periodic ridges and sharp cones are observed at inner boundaries in both environments of Ar and O2. Sharp spikes are observed in both environments, however, their height and distinctness are more pronounced in Ar as compared to O2. Cones are characteristic features in Ar, whereas, cavities and channels are dominant features in O2environment at outer boundaries. The formation and growth of surface structures are dependent upon laser fluence and ambient gas nature. The depth profilometry has been used to measure the crater depth of irradiated Zr target by using an optical microscope. UV visible spectroscopy and energy-dispersive X-ray analyses reveal the oxide formation in the case of Zr irradiation in O2environment. The Vicker Micro-hardness tester has been employed to measure the hardness. The higher observed values of sputtering yield, crater depth and hardness of laser ablated Zr in Ar as compared to O2are well correlated with distinct surface structures.

Effect of energy per atom (E/n) on the Ar gas cluster ion beam (Ar-GCIB) and O2+ cosputter process.

Gas cluster ion beam (GCIB) is a promising technique for preserving molecular structures during ion sputtering and successfully profiling biological and soft materials. However, although GCIB yields lower damage accumulation compared with C60+ and monoatomic ion beams, the inevitable alteration of the chemical structure can introduce artifacts into the resulting depth profile. To enhance the ionization yield and further mask damage, a low-energy O2+ (200-500 V) cosputter can be applied. While the energy per atom (E/n) of GCIB is known to be an important factor influencing the sputter process, the manner through which E/n affects the GCIB-O2+ cosputter process remains unclear. In this study, poly(ethylene terephthalate) (PET) was used as a model material to investigate the sputter process of 10-20 kV Ar1000-4000+ (E/n = 2.5-20 eV per atom) with and without O2+ cosputter at different energies and currents. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) with Bi32+ as the primary ion was used to examine surfaces sputtered at different fluences. The sputter craters were also measured by alpha-step and atomic force microscopy in quantitative imaging mode. The SIMS results showed that the steady-state cannot be obtained with E/n values of less than 5 eV per atom due to damage accumulation using single GCIB sputtering. With a moderate E/n value of 5-15 eV per atom, the steady-state can be obtained, but the ∼50% decay in intensity indicated that damage cannot be masked completely despite the higher sputter yield. Furthermore, the surface Young's modulus decreased with increasing E/n, suggesting that depolymerization occurred. At an E/n value of 20 eV per atom, a failed profile was obtained with rapidly decreased sputter rate and secondary ion intensity due to the ion-induced crosslink. With O2+ cosputtering and a moderate E/n value, the oxidized species generated by O2+ enhanced the ionization yield, which led to a higher ion intensity at steady-state in general. Because higher kinetic energy or current density of O2+ led to a larger interaction volume and more structural damage that suppressed molecular ion intensity, the enhancement from O2+ was most apparent with low-energy-high-current (200 V, 80 μA cm-2) or high-energy-low-current (500 V, 5 μA cm-2) O2+ cosputtering with 0.5 μA cm-2 GCIBs. In these cases, little or no intensity drop was observed at the steady-state.

Secondary ion mass spectrometry depth profiling of ultrathick films using an argon gas cluster source: Crater shape implications on the analysis area as a function of depth

Argon cluster ions have enabled molecular depth profiling to unprecedented depths, with minimal loss of chemical information or changes in sputter rate. However, depth profiling of ultrathick films (>100 μm) using a commercial ion source oriented at 45° to the surface causes the crater bottom to shrink in size because of a combination of the crater wall angle, sputter rate differences along the trailing‐edge crater wall, and undercutting on the leading‐edge. The shrinking of the crater bottom has 2 immediate effects on dual‐beam depth profiling: first is that the centering of the analysis beam inside the sputter crater will no longer ensure the best quality depth profile because the location of the flat crater bottom progressively shifts toward the leading‐edge and second, the shifting of the crater bottom enforces a maximum thickness of the film that could be depth profiled. Experiments demonstrate that a time‐of‐flight secondary ion mass spectrometry instrument equipped with a 20 keV argon cluster source is limited to depth profiling a 180 μm‐thick film when a 500 μm sputter raster is used and a 100 μm square crater bottom is to be left for analysis. In addition, depth profiling of a multilayer film revealed that the depth resolution degrades on trailing‐edge side of the crater bottom presumably because of the redeposition of the sputtered flux from the crater wall onto the crater bottom.

Experimental study of atmospheric-pressure micro-plasmas for the ambient sampling of conductive materials

Conductive solid material sampling by micro-plasma under ambient atmosphere was studied experimentally. A high-voltage pulse generator was utilized to drive discharge between a tungsten needle and metal samples. The effects of pulse width on discharge, micro-plasma and sampling were investigated. The electrical results show that two discharge current pulses can be formed in one voltage pulse. The duration of the first current pulse is of the order of 100 ns. The duration of the second current pulse depends on the width of the voltage pulse. The electrical results also show that arc micro-plasma was generated during both current pulses. The results of the emission spectra of different sampled materials indicate that the relative emission intensity of elemental metal ions will increase with pulse width. The excitation temperature and electron density of the arc micro-plasmas increase with the voltage pulse width, which contributes to the increase of relative emission intensity of metal ions. The optical images and energy dispersive spectroscopy results of the sampling spots on metal surfaces indicate that discharge with a short voltage pulse can generate a small sputtering crater.

Extreme isotopologue disequilibrium in molecular SIMS species during SHRIMP geochronology

Abstract. The current limitation in the accuracy and precision of inter-element analysis in secondary ion mass spectrometry (SIMS) is the ability to find measurable quantities that allow relative differences in ionization and transmission efficiency of secondary ions to be normalized. In uranium–thorium–lead geochronology, the ability to make these corrections, or "calibrate" the data, results in an accuracy limit of approximately 1 %. This study looks at the ionization of uranium and thorium oxide species, which are traditionally used in U–Pb calibration, to explore the conditions under which isotopologues, or molecular species whose composition differs only in the isotopic composition of one or more atoms in the molecule, remain in or deviate from equilibrium. Isotopologue deficits of up to 0.2 (200 ‰) below ideal mixing are observed in UO2+ species during SIMS gechronological analyses using the SHRIMP IIe SIMS instrument. These are identified by bombarding natural U-bearing minerals with an 18O2− primary beam. The large anomalies are associated with repeat analyses down a single SIMS sputtering crater (Compston et al., 1984), analysis of high-uranium, radiation-damaged zircon, and analysis of baddeleyite. Analysis of zircon under routine conditions yield UO2+ isotopologue anomalies generally within a few percent of equilibrium. The conditions under which the isotopologue anomalies are observed are also conditions in which the UOx-based corrections, or calibration, for relative U vs. Pb ionization efficiencies fail. The existence of these isotopologue anomalies suggest that failure of the various UOx species to equilibrate with each other is the reason that none of them will successfully correct the U / Pb ratio. No simple isotopologue-based correction is apparent. However, isotopologue disequilibrium appears to be a more sensitive tool for detecting high-U calibration breakdowns than Raman spectroscopy, which showed sharper peaks for ∼ 37 Ma high-uranium zircons than for reference zircons OG1 and Temora. U–Th–Sm / He ages were determined for aliquots of reference zircons OG1 (755±71 Ma) and Temora (323±43 Ma), suggesting that the broader Raman lines for the Temora reference zircons may be due to something other than accumulated radiation damage. Isotopologue abundances for UO+ and ThO+ and their energy spectra are consistent with most or all molecular species being the product of atomic recombination when the primary beam impact energy is greater than 5.7 keV. This, in addition to the large UO2+ instrumentally generated isotopologue disequilibria, suggests that any attempts to use SIMS to detect naturally occurring isotopologue deviations could be tricky.

Chemical stability of polymers under argon gas cluster ion beam and x-ray irradiation

In this work, the authors examine chemical stability of polymers under x-ray photoemission spectroscopy (XPS) depth profiling coupled with argon gas cluster ion sputtering. The depth profiles measured for polystyrene, poly(3-dodecylthiophene), and poly(methyl methacrylate) thin films do not reveal changes in the XPS spectra due to cluster bombardment. Nevertheless, x-ray irradiation influences the shape of the sputter craters. The observed features are attributed to cross-linking or chain scission occurring in the polymers.

3D ToF-SIMS Analysis of Peptide Incorporation into MALDI Matrix Crystals with Sub-micrometer Resolution.

The analytical sensitivity in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is largely affected by the specific analyte-matrix interaction, in particular by the possible incorporation of the analytes into crystalline MALDI matrices. Here we used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to visualize the incorporation of three peptides with different hydrophobicities, bradykinin, Substance P, and vasopressin, into two classic MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA). For depth profiling, an Ar cluster ion beam was used to gradually sputter through the matrix crystals without causing significant degradation of matrix or biomolecules. A pulsed Bi3 ion cluster beam was used to image the lateral analyte distribution in the center of the sputter crater. Using this dual beam technique, the 3D distribution of the analytes and spatial segregation effects within the matrix crystals were imaged with sub-μm resolution. The technique could in the future enable matrix-enhanced (ME)-ToF-SIMS imaging of peptides in tissue slices at ultra-high resolution. Graphical Abstract ᅟ.

A new approach to express ToF SIMS depth profiling

We propose a new approach to express SIMS depth profiling on a TOF.SIMS‐5 time‐of‐flight mass spectrometer. The approach is based on the instrument capability to independently perform raster scans of sputter and probe ion beams. The probed area can be much smaller than the diameter of a sputter ion beam, like in the AES depth profiling method. This circumstance alleviates limitations on the sputter beam–raster size relation, which are critical in other types of SIMS, and enables analysis on a curved‐bottomed sputter crater. By considerably reducing the raster size, it is possible to increase the depth profiling speed by an order of magnitude without radically degrading the depth resolution. A technique is proposed for successive improvement of depth resolution through profile recovery with account for the developing curvature of the sputtered crater bottom in the probed area. Experimental study of the crater bottom form resulted in implementing a method to include contribution of the instrumental artifacts in a nonstationary depth resolution function within the Hofmann's mixing–roughness–information depth model. The real‐structure experiment has shown that the analysis technique combining reduction of a raster size with a successive nonstationary recovery ensures high speed of profiling at ~100 µm/h while maintaining the depth resolution of about 30 nm at a 5 µm depth. Copyright © 2015 John Wiley & Sons, Ltd.

Comparability and accuracy of nitrogen depth profiling in nitrided austenitic stainless steel

A comparative study of nitrogen depth profiles in low energy ion implantation nitrided austenitic stainless steel 1.4301 by glow discharge optical emission spectroscopy (GDOES), secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) is presented. All methods require calibration either from reference samples or known scattering or reaction cross sections for the nitrogen concentration, while the methods producing a sputter crater – SIMS and GDOES – need additional conversion from sputter time to depth. NRA requires an assumption of material density for a correct conversion from the ‘natural’ units inherent to all ion beam analysis methods into ‘conventional’ depth units. It is shown that a reasonable agreement of the absolute concentrations and very good agreement of the layer thickness is obtained. The observed differences in broadening between the nitrogen distribution near the surface and the deeper region of the nitrided layer–steel interface are discussed on the basis of surface contaminations, surface roughening and energy straggling effects.

Validating mass spectrometry measurements of nuclear materials via a non-contact volume analysis method of ion sputter craters

A combination of secondary ion mass spectrometry, optical profilometry and a statistically-driven algorithm was used to develop a non-contact volume analysis method to validate the useful yields of nuclear materials. The volume analysis methodology was applied to ion sputter craters created in silicon and uranium substrates sputtered by 18.5 keV O− and 6.0 keV Ar+ ions. Sputter yield measurements were determined from the volume calculations and were shown to be comparable to Monte Carlo calculations and previously reported experimental observations. Additionally, the volume calculations were used to determine the useful yields of Si+, SiO+ and SiO2 + ions from the silicon substrate and U+, UO+ and UO2 + ions from the uranium substrate under 18.5 keV O− and 6.0 keV Ar+ ion bombardment. This work represents the first steps toward validating the interlaboratory and cross-platform performance of mass spectrometry for the analysis of nuclear materials.

X-ray enhanced sputter rates in argon cluster ion sputter-depth profiling of polymers

The authors have observed for the first time that x-ray exposure of certain polymers of “degrading” type can greatly enhance the sputter rate of these polymers by gas cluster ion beam (GCIB) profiling. They have observed craters of similar dimensions to the x-ray spot well within the perimeter of sputter craters, indicating that x-rays can assist GCIB sputtering very significantly. This can be a major source of the loss of depth-resolution in sputter depth profiles of polymers. The authors have measured experimentally sputter craters in 14 different polymers by white-light interferometry. The results show that x-ray exposure can introduce much more topography than might previously have been expected, through both thermal and direct x-ray degradation and cross-linking. Within the region exposed to x-rays, the response of the polymer surface depends on its chemistry, with degrading (also known as type II) polymers being susceptible to large increases in sputter rate in some cases. For example, this leads to a sputter rate increase of a factor of 3 in poly-L-lactic acid (PLLA) compared to cluster-ion sputtering in the absence of x rays under typical experimental conditions. By comparison, crosslinking (also known as type I) polymers show either the same sputter rate or a reduced sputter rate due to crosslinking. The authors model this behavior using the bond scission parameter (GS) and crosslinking parameter (GX) used to model radiation damage in polymers. Agreement is good, allowing us to provide guidelines to assist in planning XPS depth-profiling experiments, in particular, for polymers such as PMMA and PLLA, where any requirement for uniform sputter rate is a more stringent limit to x-ray exposure than the requirement for the XPS spectra to represent chemical states quantitatively without damage.

Observations on X‐ray enhanced sputter rates in argon cluster ion sputter depth profiling of polymers

Traditionally polymer depth profiling by X‐ray photoelectron spectroscopy (XPS) has been dominated by the damage introduced by the ion beam rather than the X‐rays. With the introduction of polyatomic and especially argon gas cluster ion‐beam (GCIB) sources for XPS instruments, this is no longer the case, and either source of damage may be important (or dominate) under particular conditions. Importantly, while ion‐beam damage is a near‐surface effect, X‐ray damage may extend micrometres into the bulk of the sample, so that the accumulation of X‐ray damage during long depth profiles may be very significant. We have observed craters of similar dimensions to the X‐ray spot well within the perimeter of sputter craters, indicating that X‐rays can assist GCIB sputtering very significantly. We have measured experimentally sputter craters in 13 different polymers. The results show that X‐ray exposure can introduce much more topography than might previously have been expected, through both thermal and direct X‐ray degradation. This can increase the depth of a crater by a remarkable factor, up to three in the case of poly‐L‐lactic acid and polychlorotrifluorothylene under reasonably normal XPS conditions. This may be a major source of the loss of depth resolution in sputter depth profiles of polymers. Copyright © 2012 John Wiley & Sons, Ltd.