MOS, It is an abbreviation for MOSFET. The full name is Metal Oxide Semiconductor Field Effect Transistor (MOSFET). The most basic and commonly used function of MOSFET is to control the on and off between S and D by applying voltage to the G level, and it is commonly used as an electronic switch.
Basic structure of MOS transistor
MOS mainly has the following characteristics:
1. High input impedance for the gate voltage, and the MOS transistor gate has an insulating film oxide, but the gate is easily broken down by static electricity and high voltage, then causing irreversible damage.
2. Low on resistance, capable of achieving milliohm level and low loss.
3. Fast switching speed and low switching loss.
Main electrical characteristic parameters and actual test results of MOS
Main electrical parameter characteristics of MOS
According to the characteristics of MOS, the most commonly concerned electrical characteristic parameters in the use of MOS are as follows:
• BVDSS (source drain breakdown voltage)
Used to evaluate the voltage resistance between DS. For high-power MOS, the withstand voltage between DS is usually required to be at the kilovolt level. When using PROBE for wafer level testing, insulation fluorine oil protection is usually used to prevent damage caused by air breakdown on the chip surface.
• IDSS (Source Leakage Current)
The leakage current when the DS channel is closed and the DS loss of MOS in non working state are usually at the uA level.
• IGSS (Gate Leakage Current)
The leakage current flowing through the gate under a certain gate voltage.
• Vth (Threshold voltage)
The gate voltage at which the drain begins to have current.
• RDS (on) (on resistance)
The conduction resistance between DS is related to the transmission loss of MOS when it is turned on. The larger the RDS (on), the higher the loss of MOS. RDS (on) is usually at the m Ω level. When using PROBE for wafer testing, a four wire test environment is used between DS to eliminate the influence of the metal probe's own resistance. For the testing of high-power MOS, high-power probes are used, and the instantaneous current can reach the hundred ampere level.
Generally used to conduct reverse current from inductive loads.
• Ciss (input capacitor)
Ciss is composed of parallel connection of gate drain capacitance Cgd and gate source capacitance Cgs. The driving circuit and Ciss have a direct impact on the turn-on and turn off delay of the device.
• Coss (output capacitor)
Coss is composed of a drain source capacitor Cds and a gate drain capacitor Cgd connected in parallel, which may cause resonance in the circuit.
• Crss (reverse transfer capacitor)
The reverse transfer capacitance is equivalent to the gate drain capacitance Cgd, also known as Miller capacitance, and is one of the important parameters for the rise and fall time of the switch, affecting the turn off delay time. The capacitance of MOS transistor decreases with the increase of drain source voltage, especially the output capacitance and reverse transmission capacitance.
Qgs, Qgd, Qg- gate charges
The gate charge value reflects the charge stored on the capacitance between the terminals. At the moment of switching, the stored charge in the gate changes with the voltage, and the influence of gate charge is often considered when designing gate drive circuits.
Output characteristic curve
The relationship ID-VDS between the current flowing through the drain and the applied voltage between the drain and source under different VGS.
Transfer Characteristic Curve
The relationship between the drain current and gate source voltage (ID-VGS) in the saturation region of a MOS transistor under a certain VDS.
GRGTEST MOS electrical characteristic parameter testing capability
GRGTEST is equipped with a high-power graphical instrument and probe testing platform, which can perform electrical characteristic parameter testing on MOS transistors at the package level and wafer level (before packaging and after opening).
The MOS dedicated testing environment equipped in GRGTEST which can achieve a maximum source drain voltage of 3kV (HVSMU, high voltage module), a maximum current of 1.5kA (UHCU, high current module), a maximum gate voltage of 100V, a current accuracy of 10fA, and a voltage accuracy of 25 μ V. For dynamic parameter testing, the frequency range can reach 1kHz~1MHz, and the MOS characteristic capacitance testing range can reach 100fF~1 μ F.
Probe testing platform