Numerical Simulation of N-well MOSFET Hall Element

 
Khafizov R.Z. (), Pavlyuk M.I. (Milandr), Timofeev A.E. (Zelenograd nanotechnology center)
 
Abstract - A significant advantage of Hall silicon sensors is the use of silicon microelectronics technology for their production, which ensures the compatibility of sensor elements with interface electronics, expanding the range of their performance and application possibilities due to signal processing. In addition, the use of modern CMOS technology makes it possible to implement MOSFET Hall sensors on the basis of metal-dielectric-semiconductor structures, both with an inversion surface channel and including a built-in conductivity channel, as well as the possibility of full dielectric isolation of the sensor from the substrate and adjacent circuit elements due to the formation of sensitive elements on silicon on the insulator structures (SOI) [1,2]. MOSFET Hall sensors belong to the class of semiconductor devices, the operation of which is significantly influenced by surface effects [3,4]. In silicon Hall elements based on MOSFET transistors with inversion channel, the influence of these effects on the Hall EMF and, accordingly, on the sensitivity is determined by the dependence of charge carrier mobility on their scattering at the Si-SiO2 interface [5]. When developing such kind of devices, the problem is solved by some ways. One of them is the development of technological processes for obtaining the Si – SiO2 interface, which contains a minimum number of scattering centers [6]. Another way is to select structures with an electronic type of conductivity, providing the maximum value of the charge carrier mobility, as well as the formation of a built-in (buried) channel with a potential relief near the Si-SiO2 interface, which prevents carriers to contact with the surface [7]. In this paper, the characteristics of the magnetic sensitivity of silicon Hall elements on the basis of the N-well MOSFET-transistor structures with a built-in channel are investigated by numerical modeling. The studies were carried out on model samples with axisymmetric topological design developed using design rules of 0.35 µm. The electrical power mode of the samples providing both inversion and enrichment of the semiconductor-dielectric interface was modeled. The aim of the work was to identify the ranges of field control of the functional characteristics of MOSFET Hall elements. At positive displacements of the gate electrode, which creates a strong enrichment of the Si-SiO2 interface, the conductivity channel is formed as a thin (less than 1 µm) surface semiconductor layer with a high electron concentration (n~5∙1017 cm-3), and under the strong inversion is in the form of a buried conductive layer with the electron concentration corresponding to the N-well doping level (Nd ~1015 cm-3). The variations of field potential in the range of ±5V provide the possibility of controllable changes of the Hall EMF in the range of ~200% at maximum values VH ~ 4,5 mV and current-related sensitivity at 2000 V/AT.

Keywords - Hall element, Hall voltage, magnetic induction, space charge region, metal-dielectric-semiconductor (MOS) structure, Hall field sensor, CMOS technology, silicon-on-insulator (SOI) structure, integrated circuit (IC).

Численное моделирование характеристик элемента Холла на основе МДП-транзистора со встроенным каналом

 
Хафизов Р.З. (ООО «ГрафИмпресс», г. Москва), Павлюк М.И. (АО ПКК Миландр, г. Москва), Тимофеев А.Е. (АО «Зеленоградский нанотехнологический центр», г. Зеленоград)
 
Аннотация - Методами приборно-технологического моделирования исследованы электрофизические параметры и характеристики магнитной чувствительности кремниевых полевых элементов Холла на основе МДП-структур со встроенным каналом в широком диапазоне управляющих потенциалов. Для модельной осесимметричной структуры, соответствующей КМОП технологии уровня 0,35 мкм, выявлена динамика пространственного распределения концентрации свободных носителей заряда и плотности тока в приповерхностном слое полупроводника, определяющая зависимость ЭДС Холла от степени взаимодействия носителей заряда с границей раздела полупроводник-диэлектрик. Показано, что за счет управления электростатическим состоянием канала проводимости МДП-элементов Холла можно в широких пределах регулировать чувствительность полевых магнитных датчиков (ПДХ), обеспечивая условия для реализации дополнительных интеллектуальных функций сенсорных магниточувствительных приборов.

Ключевые слова - элемент Холла (ЭХ), ЭДС Холла, магнитная индукция, область пространственного заряда (ОПЗ), структура металл-диэлектрик-полупроводник (МДП), полевой датчик Холла (ПДХ), КМОП технология, структура кремний на изоляторе (КНИ), интегральная схема (ИС).