Probe Holes Research Articles

Novel optical probing and micromachining techniques for silicon debug of flip chip packaged microprocessors

Methods and techniques for micromachining and probing C4 packaged microprocessors from the silicon backside are described. The micromachining technique is based on using a combination of Laser Chemical Etching and Focused Ion Beam milling to open precision probe holes and perform circuit editing from the backside. A method to optically probe flip chip packaged CMOS microprocessors is also described. The optical probing technique utilizes an infrared laser to probe diffusions directly through the silicon backside without the need to mill probe holes.

Settlement over peat on the A5 at Pant Dedwydd near Cerrigydrudion, North Wales

The A5 London to Holyhead trunk road suffers from large and varied settlements at Pant Dedwydd where it crosses a geotrophic peat bog developed on the glacial drift that overlies bedrock of Silurian Denbigh Grits Group. Recent carriageway settlements have created an undulating profile over a 100 m stretch, restricting forward visibility and posing recurring and persistent difficulties for highway maintenance. The highly compressible peat underlies almost 400 m of highway, ranges up to 7 m deep and a typical profile consists of an upper sphagnum peat layer and a basal reedy, woody and sedge grass peat. The highway was originally constructed by Thomas Telford in 1819 as a low floating embankment over the organic terrain. Increases in traffic over the intervening period together with successive asphalt overlays have resulted in a history of major repairs and although records are incomplete it is likely that the carriageway is now over 2 m thick over parts of the bog. Comprehensive geological investigations carried out to characterize the peat deposit included dynamic probe holes, boreholes and a trial pit. No unusual subsurface conditions were identified. However, scrub willow or grey sallow ( Salix cinerea) was observed growing in spiraea thickets alongside the deepest hollows in the highway. The willows may contribute to the road subsidence by extraction of water from the peat beneath the carriageway. Accordingly, removal of the scrub willow and conventional re-grading of the carriageway have been recommended to correct the existing problem.

Nanoscale imaging of the electronic tunneling barrier at a metal surface

A photometric field-emission electron microscopy technique is described by which the spatial structure of the surface electronic tunneling barrier can be mapped with nanometer resolution. The technique involves performing a Fowler–Nordheim analysis on luminosity data extracted from a set of digitized field-emission images taken over a range of voltages. This approach is equivalent to older probe-hole methods, but with greatly improved spatial resolution and data accumulation rate. Virtual probe holes of arbitrary size and shape can be constructed by integrating over subregions in the field-emission images. Performance of a system utilizing this technique is demonstrated by measuring the work functions of the (111) and (100) crystallographic planes of a clean tungsten field emitter. Applications of this technique to adsorption phenomena and field-emission display technology are also discussed.

Charging dynamics of integrated circuit passivation layer probe holes in the electron beam tester

Numerical simulations show that the sidewall of a probe hole in the SiO2 passivation layer of an integrated circuit charges negatively when a 1 keV beam is probing a test point inside the probe hole. The negative charges on the sidewalls create a local electric field that suppresses the low-energy secondary electrons and at the same time focuses the higher-energy secondary electrons. These potential barrier and lens effects degrade the detected secondary electron signal and may have significant consequences for voltage contrast measurements.

Gas-assisted etching with focused ion beam technology

Abstract The role of focused ion beam (FIB) systems in device failure analysis has been well documented 1 . FIB etching is used to cross-section features and to prepare TEM samples with better than 0.1 micron (μm) accuracy 2 , to open probe holes for mechanical and electron beam probing of circuitry, and to rewire circuits by cutting or adding connections. FIB is used to image cross sections with either secondary ions or secondary electrons, to measure metal grain size distributions through channeling contrast, and to measure process control parameters. System limitations include a relatively slow removal rate by beam sputtering of large volumes of material. Also, redeposition of sputtered material on the sidewalls of holes limits the achievable sidewall angle, and thus limits the aspect ratios of holes to approximately 6:1. With decreasing geometry sizes and multiple planarized metal layers, device modifications require cuts and interconnect holes of up to 10:1 aspect ratio, which up to now have been difficult with FIB. We will discuss recent progress in using gas-assisted etching (GAE) to enhance the FIB etching, to sharpen the etch profile, and to etch high aspect ratio holes. The hardware and GAE process will be briefly described. We will discuss the relative etch rates and selectivity of GAE with typical device materials, such as aluminum (Al), tungsten (W), silicon dioxide (SiO 2 ) and silicon (Si), using two halogen-based etchant gases, xenon difluoride (XeF 2 ) and chlorine (Cl 2 ). Images of sidewall profiles with and without GAE will be compared, and we will demonstrate several applications of GAE for e-beam and optical analysis.

Surface self-diffusion studies on the W(112) plane by the field emission method

The surface self-diffusion anisotropy of tungsten on the W(112) plane has been measured along (∥) and across (⊥) the channels, which exists on this plane, by using the field emission fluctuation method with two forms of probe holes. For most measurements the slit probe-hole dimensions, 0.4 × 4 mm, correspond to 40 × 400 Å at the emitter and the round probe-hole dimension, 1 mm, corresponded to 100 Å. In the round probe hole the thermal activation energy is E = 13.0 kcal and the prefactor of the surface self-diffusion coefficient D 0 = 4.8 × 10 −7 cm 2 s −1; in the long narrow rectangular slit E(∥) = 13.2 kcal, D 0(∥) = 7.1 × 10 −7 cm 2 s −1 and E(⊥) = 6.2 kcal, D 0(⊥) = 1.8 × 10 −9 cm 2 s −1 at T = 500−700 K. The experimental data suggest that a W atom diffusing across channels should not climb over the channel wall, which would almost certainly require a much higher activation energy, but displace an atom in the wall. This process can require a much smaller activation energy, but since it involves concerted motion of at least two atoms it will also have a much smaller prefactor.

Alesund undersea tunnels : Smith, M World TunnlgV2, N1, Feb 1989, P4–8

This article describes the construction of three tunnels off the West coast of Norway, linking alesund to the neighbouring islands. Two tunnels, the 3483 m alesund to ellingsoya and the 4175 m ellingsoya to valderoya, were completed in 1987, and a third tunnel, between the islands of giske and godoy, has nearly been finished. The usual cross-sectional area of the tunnels is 68 sq m, to accommodate a 3-lane highway; however, the 500 m long mid section of one tunnel has cross-sectional area 47 sq M, accommodating 2 lanes only. The clear height of all tunnels is 4.6 m. All the tunnels have been driven by drill and blast techniques, using wheel loaders and diesel haul trucks to remove debris. Details are given of the tunnel driving cycle times, the workforce, drilling and charging, probe holes, and support. The article concludes that this is a high quality tunnelling project, in which a combination of good planning and management has reduced the construction period by over a year. The experience gained from these tunnels is likely to have a strong influence on similar projects in future, not only in Norway but throughout the world. (TRRL)

Effect of Charge Carriers on the Prebreakdown Current Flowing Through a Parallel-Plate Vacuum Gap

Electrical charges carried by ions and microparticles passing through probe holes of a cathode were measured by means of a collector electrode, positioned behind the cathode. The contribution of these carriers to the prebreakdown current was discussed. The characteristics of the observed charge increase on the collector electrode composed of two parts; one was the abruptly increasing part caused by the sporadic arrival of microparticles, while the other part linearly increased with time due to the continuous arrival of ions. The ion current estimated from the latter and the prebreakdown current were dependent on the roughness of the anode surface rather than that of the cathode. Consequently, it was assumed that, besides cathode protrusion, a space charge effect caused by ions from the anode region plays an important role in forming the potential distribution near the cathode region.

Rapid force-flux transitions in highly porous membranes

Rapid force-flux transitions in highly porous membranes

A Study of Adjustments of a Zinn-Type Ion Source

The ion current from a Zinn-type ion source has been determined for various values of three parameters of the source. These parameters are the diameters of the probe and plate holes and the spacing of the nose and plate. The ion current from the source was found to increase linearly with the diameter of the plate hole up to a certain value while above this value there was little further increase. The ion current likewise increased with probe hole diameter, but the increased gas flow prevented extensive increases in this parameter. A smaller gap between nose and plate gave the maximum ion current for a smaller current to the filament and therefore at a smaller power dissipation in the arc. Gas consumption was 10 cc per hour.