Long-term stability and electrical properties of compensation doped poly-Si IC-resistors

Rydberg, Matts; Smith, Ulf

doi:10.1109/16.822289

Cited by 32 publications

(34 citation statements)

References 24 publications

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“…[16][17] report the use of a commercial CMOS process for fabrication, with [16] using polysilicon as a heater material, and [17] using a single-crystal silicon heater with aluminium to form electrical connections between the heater and connections outside the membrane. However, polysilicon is known to suffer from long-term stability problems at high temperatures (over 300 ºC) [18]. Single-crystal silicon is more stable, but it has a relatively high sheet resistance that makes it difficult to design a micro-heater for low voltage operation (below 3 V).…”

Section: Introductionmentioning

confidence: 99%

A Low-Power, Low-Cost Infra-Red Emitter in CMOS Technology

et al. 2015

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Section: Introductionmentioning

confidence: 99%

A Low-Power, Low-Cost Infra-Red Emitter in CMOS Technology

et al. 2015

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“…For polysilicon, the measured grain size is 1300 Ϯ 200 Å. It has been shown previously 25 that the grain size in polysilicon is independent of doping type and concentration for the doping concentrations used in this work. Therefore, the grain size determined for the sample doped with 5 ϫ 10 14 cm Ϫ2 boron is taken as representative of all the polysilicon samples.…”

Section: Resultsmentioning

confidence: 85%

“…16,25,41 However, for a given process, the systematic variations in the f factor can provide information about the properties of the grain boundaries.…”

Section: On Nmentioning

confidence: 99%

Temperature Coefficient of Resistivity in Heavily Doped Oxygen-Rich Polysilicon

Rydberg

Smith

2001

J. Electrochem. Soc.

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Oxygen, boron, and phosphorus additions to polysilicon films were followed up to 23% oxygen. Above 500 ⍀/ᮀ, oxygen resulted in temperature coefficients of resistivity ͑TCR͒ magnitudes a factor of two smaller than without oxygen. For p-type films, the TCR saturated at ϳ0.05% for low resistivities. Surface energy considerations show that the oxygen atoms are likely to attach to the surface of the growing grains. This explains the dependence on oxygen concentration of grain size, boron segregation, and tunneling barrier. A model for polysilicon resistivity was used to study changes with added oxygen and dopants. The potential barrier was followed down to a saturation region. The latter was found to be independent of oxygen, but to depend on carrier concentration and type according to the U-shaped trap distribution in oxygen-free films. This is also responsible for the saturation in the TCR. The f factor showed temperature-independent tunneling to gradually outweigh the temperature-dependent contribution from the potential barrier. A dopant-dependent f factor showed that dopant scattering begins to dominate over tunneling. Boron segregation in oxygen-rich films was 30-35%. Boron gave rise to a slight increase in grain size and phosphorus gave rise to a large increase. There were significantly more charged traps in films containing oxygen, where they exceeded 10 13 cm Ϫ2 .The temperature coefficient of resistivity ͑TCR͒ in polysilicon is negative and quite large for resistivity values characteristic of, for example, bipolar circuits. This is not desirable since it puts an extra burden on the design work. In extreme situations, it can also cause thermal runway of the resistor. A zero TCR is possible, but only in the resistivity range of 100 to 300 ⍀/ᮀ. 1,2 The design of resistors in bipolar circuits is often based on resistivities around 1000 ⍀/ᮀ. For such resistors, a zero TCR can only be achieved with low resistivity polysilicon and an increased length of the resistor, which wastes valuable silicon area. Kim and Choi 3 investigated ways of overcoming this limitation by means of compensation doping. However, they found that compensation-doped resistors have the same TCR as single-doped resistors. Laser recrystallization has also been tried 4 based on the assumption that the large negative contribution to the TCR from the grain boundaries is reduced in films with larger grains. Unfortunately, this method does not lend itself easily to volume production.TCRs lower than those in polysilicon can be obtained by means of semi-insulating polycrystalline silicon ͑SIPOS͒ films. 5,6 These semi-insulating, or oxygen-rich, polysilicon films can be deposited in the same way as polysilicon simply by adding N 2 O to the SiH 4 gas flow. The amount of oxygen in the film is varied by using different N 2 O/SiH 4 ratios. Lai et al. 7 were able to show that in undoped, high resistivity films, the temperature sensitivity could be lowered by more than an order of magnitude compared to polysilicon. Ong et al. 8 studied the temperature depen...

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“…6). Much higher temperatures are attainable by the tungsten heaters, 13,14 but at these temperatures, the aluminum tends to be poor stability due to electro-migration and high temperature oxidation.…”

Section: A Thermal Characteristicsmentioning

confidence: 99%

“…[10][11][12] However, during operating at high temperature for a long time, the resistances drift of poly-Si cause long-term stability problems. 13,14 In the modern standard CMOS processes, tungsten, with excellent mechanical strength as well as high temperatures stability, is used as a plug material to form via between different metal layers and the silicon substrate. With nonconventional layout design, MHPs with the tungsten resistor as the heater and thermometer have been developed, 15,16 which is a better choice for CMOScompatible micro gas sensors.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication of a CMOS-compatible MHP gas sensor

et al. 2014

AIP Advances

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A novel micro-hotplate (MHP) gas sensor is designed and fabricated with a standard CMOS technology followed by post-CMOS processes. The tungsten plugging between the first and the second metal layer in the CMOS processes is designed as zigzag resistor heaters embedded in the membrane. In the post-CMOS processes, the membrane is released by front-side bulk silicon etching, and excellent adiabatic performance of the sensor is obtained. Pt/Ti electrode films are prepared on the MHP before the coating of the SnO2 film, which are promising to present better contact stability compared with Al electrodes. Measurements show that at room temperature in atmosphere, the device has a low power consumption of ∼19 mW and a rapid thermal response of 8 ms for heating up to 300 °C. The tungsten heater exhibits good high temperature stability with a slight fluctuation (<0.3%) in the resistance at an operation temperature of 300 °C under constant heating mode for 336 h, and a satisfactory temperature coefficient of resistance of about 1.9‰/°C.

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Long-term stability and electrical properties of compensation doped poly-Si IC-resistors

Cited by 32 publications

References 24 publications

A Low-Power, Low-Cost Infra-Red Emitter in CMOS Technology

A Low-Power, Low-Cost Infra-Red Emitter in CMOS Technology

Temperature Coefficient of Resistivity in Heavily Doped Oxygen-Rich Polysilicon

Design and fabrication of a CMOS-compatible MHP gas sensor

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