CN116047251B

CN116047251B - Method for representing trap parameters of GaNHEMT device by microsecond transient curve

Info

Publication number: CN116047251B
Application number: CN202310000307.0A
Authority: CN
Inventors: 潘世杰; 冯士维; 李轩; 白昆; 鲁晓庄
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2025-08-15
Anticipated expiration: 2043-01-03
Also published as: CN116047251A

Abstract

The present invention discloses a method for characterizing the trap parameters of a GaN HEMT device using a microsecond transient curve, and relates to the field of semiconductor device reliability. The microsecond transient voltage curve of the GaN HEMT device under a constant electrical bias is collected through circuit design, and the relevant trap information is obtained by further analysis and processing using a structure function method. The method mainly comprises: placing the device under test on a constant temperature platform and connecting it to a trap test circuit; applying a bias voltage to the device through the circuit during the trap filling process; shortening the switching time to the microsecond level through a fast switch during the trap release process, and simultaneously collecting the changes in the transient voltage curve and analyzing and processing it through software to obtain information related to the internal traps of the device. The present invention improves the collection of transient voltage curves to the microsecond level through circuit design, and can be used for trap testing of GaN HEMT devices produced by different manufacturers, with good versatility.

Description

Method for representing trap parameters of GaNHEMT device by microsecond transient curve

Technical field:

The invention relates to the field of semiconductor device reliability, and is mainly applied to measurement and characterization of trap parameters in GaNHEMT (Gallium Nitride Based High-electron-mobility Transistor) devices.

The background technology is as follows:

The development of wide bandgap semiconductor devices, typified by GaNHEMT devices, has become an important impetus for the continued development of the power electronics field. The GaNHEMT device has the characteristics of high electron mobility, high breakdown electric field and the like, and has wide development prospect in high-frequency and high-power application scenes. Compared with Si and GaAs-based devices, the GaN-based devices have degradation and failure phenomena with unclear mechanisms, the phenomena are closely related to traps in the devices, and the instability of electrical parameters caused by the phenomena brings potential hidden hazards to the reliability of system application.

At present, the trap effect of the GaNHEMT device is mainly shown by the phenomena of gate delay, drain delay, current collapse and the like, wherein the phenomenon of time degradation of drain-source current or drain-source voltage of the device directly shows the influence of the trap on the electrical performance of the device. Under the bias of larger gate-source voltage and drain-source voltage, the trap in the device is filled with electrons, and then the device is switched to the bias of constant drain-source current, the electrons are released from the trap, so that the two-dimensional electron gas concentration is increased, and the transient drain-source voltage is reduced. However, when the semiconductor parameter analyzer is used for testing, the change of the transient curve is usually collected by taking millisecond time as a starting point, and the test and collection of microsecond transient response cannot be realized by achieving a faster switching speed. The GaNHEMT device has wide application in the high-frequency field, transient curve change caused by trap filling in the device meets the e index relation, and transient curve change under microsecond level time contains a large amount of trap information, so that acquisition of microsecond level trap information has important significance for further exploring a trap action mechanism.

The invention provides a method for representing trap parameters of a GaNHEMT device by collecting microsecond transient curves. The technology can be applied to parameter extraction of traps in GaNHEMT devices, and achieves faster switching speed of switches, so that microsecond transient curve collection in the trap release process is achieved, more complete trap information is obtained, and the action mechanism of the trap information is further studied. The method has better universality and can be used for trap tests of GaNHEMT devices of different types.

The invention comprises the following steps:

The invention discloses a method for representing trap parameters of a GaNHEMT device by adopting microsecond transient curves, which is used for realizing acquisition of microsecond transient voltage curves of the GaNHEMT device under constant electrical bias through circuit design and further analyzing and processing through a structural function method to obtain relevant trap information. The invention has the main advantages that a rapid switch switching circuit for trap test is designed, microsecond transient curve test and corresponding trap information acquisition can be realized, meanwhile, the stable application of 48V drain-source voltage and-10V gate-source voltage bias in a trap filling stage is realized, and the requirement of a GaNHEMT device trap filling stage on voltage bias can be met.

A method for characterizing trap parameters of GaNHEMT devices by microsecond transient curves is characterized in that:

1. The device 109 to be tested is fixed on a constant temperature platform 110 with the temperature of T1 and is connected with a constant current source circuit 106, a drain voltage control circuit 107, a grid voltage control circuit 108 and an amplifying circuit 105, wherein the drain voltage control circuit 107 is connected with the device 109 to be tested through a diode load 111, and the grid voltage control circuit 108 is connected with the device to be tested through a bipolar transistor 112. The computer 101 realizes real-time acquisition of transient voltage signals through the AD acquisition circuit 103, and realizes amplification and noise reduction treatment of the voltage signals through the amplifying circuit 105 and the signal-to-noise ratio enhancing circuit 104, wherein the amplifying circuit 105 can amplify the acquired voltage signals by 10 times, and the sampling speed of the AD acquisition circuit is 1MHz. The computer 101 sets the gate-source voltage V _GF, the drain-source voltage V _DF and the filling time t ₁ in the filling stage, and the drain-source current I _DM and the testing time t ₂ in the testing stage through the FPGA control module 102, and the computer 101 controls the starting of the trap filling and testing process.

2. In the trap filling stage, the computer 101 controls the drain voltage control circuit 107 and the gate voltage control circuit 108 through the FPGA control module 102, and applies a negative gate source voltage V _GF and a positive drain source voltage V _DF with constant pulse width to the device to fill the trap in the device, wherein the negative gate source voltage V _GF ranges from-10V to 0V, the positive drain source voltage V _DF ranges from 0V to 48V, and the filling time t ₁ ranges from 1ms to 30s.

3. After the filling time t ₁ is over, the computer 101 controls the bipolar transistor 112 through the FPGA control module 102 to realize the rapid switching of the gate voltage control circuit 108 on the negative gate source voltage, wherein the switching range of the gate source voltage can reach-10V to 0V, and meanwhile, the diode load 111 reduces the set-up time of the constant current source in the switching process to realize the switching of the drain voltage control circuit 107 and the constant current source circuit 106, wherein the switching time can be controlled within 10 mu s, so that microsecond level transient curve change conditions are obtained. After the circuit is switched, the trap releasing process is tested, constant drain-source current is applied to the device through the constant current source circuit 106 under the voltage of 0V gate source, and the drain-source voltage change curve of the tested device along with time is obtained through the AD acquisition circuit 103, wherein the test time is t ₂. In the test process, the 0V gate source voltage can ensure that the device to be tested is in a conducting state (the threshold voltage of the depletion type device is smaller than 0V), the electric potential between the gate sources of the device is the same so as to avoid the influence of an externally applied gate source electric field, the drain source current I _DM applied to the device ranges from 0mA to 300mA, the sampling precision of a transient curve can reach 1 mu s, and the test time t ₂ ranges from 10 mu s to 300s.

4. Amplifying and denoising the transient voltage data obtained in the step 3 through an amplifying circuit 105 and a signal-to-noise ratio enhancing circuit 104 respectively to obtain transient voltage curves with microsecond-level to second-level changes, and returning the data to the computer 101 for processing by a structural function method to obtain corresponding time constant spectrums, wherein the abscissa of the time constant spectrums is the time constant corresponding to the trap. The horizontal axis of the time constant spectrum TCS corresponds to the test time t ₂ of the transient voltage response curve, and is expressed in a logarithmic form, and the vertical axis is the relative amplitude obtained after the processing of the structural function method. The number of peaks obtained from the time constant spectrum TCS is the number of traps, and the corresponding abscissa of the peaks is the time constant of the traps.

The invention provides the method for realizing the characterization of the trap parameters of the GaNHEMT device by utilizing the microsecond transient curve for the first time, and the method can acquire the transient response curve from microsecond to second and extract more complete trap information from the transient response curve, thereby effectively characterizing the trap distribution condition in the device.

Description of the drawings:

FIG. 1 is a schematic diagram of a trap test circuit;

The device comprises a computer 101, an FPGA control module 102, an AD acquisition circuit 103, a signal-to-noise ratio enhancing circuit 104, an amplifying circuit 105, a constant current source circuit 106, a drain voltage control circuit 107, a grid voltage control circuit 108, a tested device 109, a constant temperature platform 110, a diode load 111 and a bipolar transistor 112;

FIG. 2 is a timing diagram of a microsecond level transient voltage curve test;

Fig. 3 is a transient voltage change curve and time constant spectrum.

The specific embodiment is as follows:

an example of characterizing the trapping parameters of a ganemt device using microsecond level transient curves is given below, with the commercial ganemt device CGH40010 manufactured by CREE corporation being selected as the device under test 109.

1. The device 109 to be tested is fixed on a constant temperature platform 110 with the temperature of 298K and is connected with a constant current source circuit 106, a drain voltage control circuit 107, a grid voltage control circuit 108 and an amplifying circuit 105, wherein the drain voltage control circuit 107 is connected with the device 109 to be tested through a diode load 111, and the grid voltage control circuit 108 is connected with the device to be tested through a bipolar transistor 112. The computer 101 realizes real-time acquisition of transient voltage signals through the AD acquisition circuit 103, and realizes amplification and noise reduction treatment of the voltage signals through the amplifying circuit 105 and the signal-to-noise ratio enhancing circuit 104. The computer 101 sets the gate-source voltage V _GF, the drain-source voltage V _DF and the filling time t ₁ in the filling stage, and the drain-source current I _DM and the testing time t ₂ in the testing stage through the FPGA control module 102, and the computer 101 controls the starting of the trap filling and testing process, and the schematic diagram of the testing circuit is shown in fig. 1.

2. In the trap filling stage, the computer 101 controls the drain voltage control circuit 107 and the gate voltage control circuit 108 through the FPGA control module 102, and the gate source voltage V _GF of-10V and the drain source voltage V _DF of 10V are applied to the device, and the filling time t ₁ is 30s.

3. After the filling process is finished, the computer 101 controls the bipolar transistor 112 through the FPGA control module 102 to realize the rapid switching of the grid voltage control circuit 108 between-10V and 0V, and meanwhile, the diode load 111 reduces the establishment time of the constant current source in the switching process to realize the switching of the drain voltage control circuit 107 and the constant current source circuit 106, and the switching time can be controlled within 10 mu s. After the circuit is switched, the trap release process is tested, a constant 200mA drain-source current I _DM is applied to the device through a constant current source circuit 106 under the gate-source voltage of 0V, the drain-source voltage change curve of the tested device along with time is obtained through an AD acquisition circuit 103, and the test time t ₂ is 120s. The test timing diagram is shown in fig. 2.

4. The transient voltage data obtained in the step 3 are amplified and noise reduced respectively by an amplifying circuit 105 and a signal-to-noise ratio enhancing circuit 104, and finally the obtained transient voltage curve is shown in fig. 3 (a), and the transient voltage change curve within the time range of 10 mu s to 120s is obtained. The transient curve data is returned to the computer 101 for processing by a structural function method to obtain a corresponding time constant spectrum as shown in fig. 3 (b). The horizontal axis of the time constant spectrum TCS corresponds to the test time 120s of the transient curve and is expressed in a logarithmic coordinate form, and the vertical axis corresponds to the relative amplitude processed by the structural function method. In fig. 3 (b), there are two peaks, which indicate that there are two traps in the voltage curve to affect the transient variation, and the abscissa corresponding to the two peaks is the time constant of the two traps, and the time constants are named as DP1 and DP2 in sequence from small to large.

Claims

1. A method for characterizing the trap parameters of a GaN HEMT device using microsecond transient curves, characterized by:

1) The device under test is placed on a constant temperature platform at a temperature of T1 and connected to a constant current source circuit, a drain voltage control circuit, a gate voltage control circuit, and an amplifier circuit. The drain voltage control circuit is connected to the device under test through a diode load, and the gate voltage control circuit is connected to the device under test through a bipolar transistor. A computer acquires transient voltage signals in real time through an AD acquisition circuit, and amplifies and reduces the voltage signals through an amplifier circuit and a signal-to-noise ratio enhancement circuit, respectively. The computer sets the gate-source voltage _VGF , drain-source voltage _VDF , and fill time _t1 during the filling phase, as well as the drain-source current _IDM and test time _t2 during the test phase, and the computer controls the start of the trap filling and testing process.

2) During the filling phase, the computer controls the drain voltage control circuit and the gate voltage control circuit to apply a negative gate-source voltage _VGF and a positive drain-source voltage _VDF with a constant pulse width _t1 to the device to fill the internal traps of the device;

3) After the filling time _t1 , a fast switching circuit constructed from bipolar transistors is controlled by a computer to achieve rapid switching of the gate voltage control circuit. A diode is used as a load to reduce the establishment time of the constant current source during the switching process. After the circuit is switched, the trap release process is tested. During the test phase, a 0V gate-source voltage is applied to the device to ensure that the device under test is in the on state. The threshold voltage of the depletion-type device is less than 0V, and the potential between the device gate and source is the same to avoid the influence of the external gate-source electric field. At the same time, a constant drain-source current _IDM is applied, and the drain-source voltage of the device under test is collected over time through the AD acquisition circuit. The test time is _t2 .

4) The transient voltage data obtained in step 3) is amplified and denoised by an amplifier circuit and a signal-to-noise ratio enhancement circuit, respectively, to obtain a transient voltage response curve; the data is returned to a computer for structure function processing to obtain a corresponding time constant spectrum TCS; the horizontal axis of the time constant spectrum TCS corresponds to the test time _t2 of the transient voltage response curve and is expressed on a logarithmic scale; the vertical axis is the relative amplitude of the trap obtained after structure function processing; the number of peaks obtained from the time constant spectrum TCS is the number of traps, and the horizontal axis corresponding to the peak is the time constant of the trap.

2. The method for characterizing the trap parameters of a GaN HEMT device according to claim 1, wherein:

In the trap filling stage, the positive drain-source voltage V _DF applied to the device under test ranges from 0 V to 48 V, the negative gate-source voltage V _GF ranges from -10 V to 0 V, and the filling time _t1 ranges from 1 ms to 30 s.

3. The method for characterizing the trap parameters of a GaN HEMT device according to claim 1, wherein:

The switching time between the trap filling phase and the test phase is controlled within 10 μs, and the gate voltage control circuit realizes the switching of the voltage from -10 V to 0 V.

4. The method for characterizing the trap parameters of a GaN HEMT device according to claim 1, wherein:

The switching between the trap filling phase and the test phase is achieved by a fast switching circuit constructed by bipolar transistors and diodes, which provides a constant drain-source current while changing the gate-source voltage and starts to collect changes in transient drain-source voltage.

5. The method for characterizing the trap parameters of a GaN HEMT device according to claim 1, wherein:

During the test phase, the drain-source current I _DM applied to the device ranges from 0 to 300 mA, the transient curve sampling accuracy can reach 1 μs, and the test time t ₂ ranges from 10 μs to 300 s.

6. The method for characterizing trap parameters of a GaN HEMT device according to claim 1, wherein:

The trap parameter to be characterized is the time constant of the trap, and the characterization method is to collect the transient drain-source voltage curve of the device during the trap test phase.