Fabrication of microtips on planar specimens

Larson, David J.; Teng, Chen-Ming; Camus, Paula; Kelly, Tom

doi:10.1016/0169-4332(94)00504-4

Cited by 28 publications

(6 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Liddle et al noted that the polystyrene sputtered quickly relative to the semiconductors they were studying and suggested using particles with lower sputtering rates. Larson et al 83 employed diamond particles to effectively create microtips suitable for analysis in a local electrode atom probe ͓Fig. 3͑b͔͒.…”

Section: Broad Ion Beam Methodsmentioning

confidence: 99%

Atom probe tomography

Kelly¹,

Miller

2007

Review of Scientific Instruments

Self Cite

751

345

View full text Add to dashboard Cite

The technique of atom probe tomography ͑APT͒ is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution ͑sub-0.3-nm͒ three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.

show abstract

Section: Broad Ion Beam Methodsmentioning

confidence: 99%

Atom probe tomography

Kelly¹,

Miller

2007

Review of Scientific Instruments

Self Cite

751

345

View full text Add to dashboard Cite

show abstract

“…The electrode itself is mounted on a suitably fine movement XYZ stage, driven by piezoelectric motors, for example, allowing it to be aligned above a specific microtip with sub-micron accuracy. Moving the microelectrode across the surface allows individual microtips to be addressed and analysed in turn.Microtip specimens can in principle be fabricated from thin films or devices on a planar substrate, either by masking and ion-beam milling [3,4], or by lithography and focussed ionbeam milling [5] or by a combination of the two methods. Fig 2. shows an example of a microtip made in a silicon substrate though masking with a diamond particle and ion milling with argon ions.…”

mentioning

confidence: 99%

“…Microtip specimens can in principle be fabricated from thin films or devices on a planar substrate, either by masking and ion-beam milling [3,4], or by lithography and focussed ionbeam milling [5] or by a combination of the two methods. Fig 2. shows an example of a microtip made in a silicon substrate though masking with a diamond particle and ion milling with argon ions.…”

mentioning

confidence: 99%

Development of the Scanning Atom Probe

Cerezo

2003

Microsc Microanal

View full text Add to dashboard Cite

In 1994, Nishikawa proposed a new design of atom probe instrument, which he called the scanning atom probe (SAP) [1]. The aim of this instrument was to allow the use of specimens in the form of microtips on a planar substrate, and thus extend the applicability of atom probe microanalysis to surfaces and ultra-thin film materials. Fig. 1 shows a schematic of the design of the scanning atom probe. A microelectrode is used to raise the local electric field above one of the microtips to the level required for field evaporation of atoms at the specimen surface, and hence permit atomic-scale analysis of the apex region. Without the electrode, the presence of the flat substrate would limit the field at the apex and prevent removal of atoms. Since the presence of this microelectrode close to the specimen is a critical part of the design, the alternative naming of local electrode atom probe (LEAP) has been used by Kelly [2]. The electrode itself is mounted on a suitably fine movement XYZ stage, driven by piezoelectric motors, for example, allowing it to be aligned above a specific microtip with sub-micron accuracy. Moving the microelectrode across the surface allows individual microtips to be addressed and analysed in turn.Microtip specimens can in principle be fabricated from thin films or devices on a planar substrate, either by masking and ion-beam milling [3,4], or by lithography and focussed ionbeam milling [5] or by a combination of the two methods. Fig 2. shows an example of a microtip made in a silicon substrate though masking with a diamond particle and ion milling with argon ions. These methods would allow many hundreds of microtips to be made within a few mm 2 of specimen, all with the layers of interest at the apex, thus greatly increasing the volume of information accessible by the atom probe. In addition, the SAP could be used to chemically analyse protrusions on surfaces without any additional specimen preparation. Fig. 3. shows a mass spectrum from the surface of a diamond field emitter which has not undergone any special treatment before analysis in the SAP [6].Apart from extending the range of specimens that can be analysed in the atom probe, the use of a local electrode reduces by up to a factor of 3 the voltage needed to produce field evaporation [7]. This allows the analysis of specimens with a larger radius of curvature, which is useful where fabrication of specimens is difficult but also gives an increased field of view, as the magnification in the atom probe is inversely proportional to the apex radius. Reduction in the pulse voltage required allows an increase in the pulsing frequency, which in turn yield an increase in the data acquisition rate for the instrument. Currently the typical time for analysis of a volume 20 nm × 20 nm × 100 nm is many hours, so increasing the data acquisition rate is clearly necessary to permit larger volumes of material to be studied from a single specimen. The use of a local electrode has the additional advantage that it should be possible to increase the mass resolu...

show abstract

“…In a LEAP, a local extraction electrode is used to select a single tip from within an array of tips formed on a planar sample [5]. It also enables the evaporation of ions at low voltages [l-41 due to its proximity to the sample tip.…”

Section: Introductionmentioning

confidence: 99%

Mass Resolution Enhancement in Local-Electrode Atom Probes : A Preliminary Study Using Field Emitter Arrays

et al. 1996

View full text Add to dashboard Cite

Abstract. The use of post-evaporation acceleration as a means to enhance mass resolution in localelectrode atom probes (LEAP) is experimentally investigated in this study. Gated silicon field emitter arrays which have an extraction electrode-tip structure similar to a LEAP are used to evaporate ions at low voltages which are then accelerated to higher voltages. The study confirms the expected improvement in mass resolution. The mass resolution achieved using this gated field emitter array is however quite poor owing to capacitive coupling between the extraction electrode and the tip which leads to a broadened evaporation pulse. An improved model to relate time-of-flight to ion mass-to-charge ratio is found to be necessary in this atom probe configuration. These findings suggest important design considerations for extraction electrodes for a LEAP.

show abstract

Fabrication of microtips on planar specimens

Cited by 28 publications

References 11 publications

Atom probe tomography

Atom probe tomography

Development of the Scanning Atom Probe

Mass Resolution Enhancement in Local-Electrode Atom Probes : A Preliminary Study Using Field Emitter Arrays

Contact Info

Product

Resources

About