Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

Abstract

Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si 3 N 4 /SiO 2 /Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about −2 %/°C in the temperature interval from 25 to 50 °C.

Metal silicide/Si thin-film Schottky-diode bolometers

“…2 b (layer g). 7 Taking into the account the presence of intense peaks of Pt, Si and O in the XPS spectra we can conclude that this layer is formed by a non-uniform film composed by Pt, SiO 2 and some compounds of Pt, Si and O having a complex structure. A thickness of this film exceeds the depth of sensitivity of XPS that is about 10 nm.…”

“…Their total thickness determined from the numerical simulation (15.8 nm) is very close to the thickness of the granular layer determined from STEM (15 nm). 7 According the numerical simulation, 7 there are additional two layers, also rough, beneath the first tow granular layers; their total thickness is 7.5 nm; they consist of platinum silicides, silicon and maybe also of platinum (their estimated chemical composition-Pt 60 Si 40 and Pt 64 Si 36 -is rather close to that of Pt 2 Si and they resemble a Pt 2 Si layer with some additional amount of Si). The total thickness of these layers and the PtSi layer situated under them is 59.5 nm that is close to the mean total thickness of the Pt silicide determined using STEM.…”

“…The total thickness of these layers and the PtSi layer situated under them is 59.5 nm that is close to the mean total thickness of the Pt silicide determined using STEM. 7 The XPS analysis of the PtSi/poly-Si structure allowed us to explore in more details the chemical composition of the uppermost layers of this structure and especially the composition of the granular layer depicted in Fig. 2 b (layer g).…”

“…3 Alternatively, we have tested the PtSi/poly-Si:P Schottky diodes as candidates to the same role. [4][5][6][7] We have come to conclusion that this kind of the Schottky diodes is even more suitable for production of bolometer detector arrays than the Ni silicide/poly-Si ones due to their better compatibility with the CMOS process, in analogy with the well developed manufacturing process of the cooled PtSi/Si infrared detector arrays. [8][9][10][11][12][13][14][15][16] To test this solution we have produced by a CMOS-compatible process the Pt-silicide/poly-Si:P Schottkydiode structures simulating the topology of the prospective sensitive cells of bolometers and examined them using the scanning transmission electron microscopy, the two-wavelength X-ray structural phase analysis (diffractometry and reflectometry) and the X-ray photoelectron spectroscopy.…”

“…[8][9][10][11][12][13][14][15][16] To test this solution we have produced by a CMOS-compatible process the Pt-silicide/poly-Si:P Schottkydiode structures simulating the topology of the prospective sensitive cells of bolometers and examined them using the scanning transmission electron microscopy, the two-wavelength X-ray structural phase analysis (diffractometry and reflectometry) and the X-ray photoelectron spectroscopy. 7 We have also studied the I-V characteristics of the Schottky junctions and investigated their temperature sensitivity (temperature coefficients of voltage T CU = U −1 dU/dT ) for different values of the stabilized constant current and at different temperatures.…”