SIMS backside depth profiling of ultrashallow implants using silicon‐on‐insulator substrates

Abstract

The scaling of the junction depth, which can help to suppress the short channel effect, has become essential for the emerging nanoscale IC technology. The 2000 National Roadmap for semiconductors indicates that for complementary metal-oxide semiconductors with 0.13 µm and 0.09 µm gate lengths, junction depths of 43 nm and 35 nm are required, respectively. It will be of utmost importance to obtain accurate dopant profiles of the electrically activated junctions. In SIMS depth profiling, dopant profiles are broadened by sputter-induced roughening and a primary-energy-dependent ion mixing effect; shallow profiles are obscured by surface transient effects. Crater bottom roughening usually can be removed by oxygen flooding 1,2 or sample rotation 3,4 techniques; ion mixing can be minimized by lowering the primary ion energy and optimizing the incidence angle. For implanted profiles, the knock-on effects when sputtering from a high concentration to lower concentration region will significantly degrade the depth resolution.Backside SIMS depth profiling using primary ion energies >3 keV has been shown to improve the implanted trailing edge profile and avoid surface transient effects.5 -8 However, sample thinning from the backside, either by etching or polishing, requires that the surface be kept flat and smooth in order to achieve high depth resolution. We have developed an ultrashallow backside profiling technique

Accurate analysis of shallowly implanted solar wind ions by SIMS backside depth profiling

“…This technique has been previously applied in the semiconductor industry for analysis of ultrashallow ion implants or impurities (e.g., Jackman et al, 1990;Yeo et al, 2002;Yeo et al, 2003;Fujiyama et al, 2011). We developed this technique further in our laboratory for the application to solar wind analysis.…”

Dopant profiling in ultrathin silicon-on-insulator layers

“…[3][4][5] The BOX was left intact for most samples. Under 650 eV O 2 ϩ bombardment with a O 2 backfill pressure of ϳ5ϫ10 Ϫ7 Torr, the sputter rates in the Si and SiO 2 layers are quite different.…”

Investigation of boron penetration through decoupled plasma nitrided gate oxide using backside secondary ion mass spectrometry depth profiling

“…Details of sample preparation have been published. 9 SIMS measurements were performed in a Cameca IMS-6f SIMS instrument with 0.5 keV O 2 ϩ beams at 56°incidence and 2 keV Cs ϩ beam at 44°incidence. 12,13 O 2 ϩ beams with source and sample potential fixed at 1.5 and 1 keV, respectively, were used, giving a net impact energy of 0.5 keV and an incidence angle of 56°with respect to surface normal.…”

“…Backside SIMS depth profiling using SOI wafers has been shown to improve depth resolution by measuring the leading edge profile rather than the trailing edge profile. 9,10 In this article we will demonstrate the application of backside SIMS technique in studying boron penetration through different nitrided thin gate oxides.…”