A method for establishing an equivalent circuit model of a lateral high-voltage device and a simulation method

Abstract

The present application belongs to the technical field of power integrated circuit, and particularly relates to a method for establishing and simulating a lateral high-voltage device equivalent circuit model. The circuit model comprises: a field effect transistor; a drain resistance, one end of which is connected to the drain of the field effect transistor and the second end of which is used as the drain of a high-voltage device; a source resistance, one end of which is connected to the source of the field effect transistor and the second end of which is used as the source of a high-voltage transistor; a body diode, which is connected in series with a diode cathode through a parallel network of a cathode resistance and an inductor, the anode of which is connected to the source of the high-voltage transistor, and the other end of the cathode resistance is connected to the drain of the high-voltage device; a first current source, one end of which is connected to the drain of the high-voltage device and the other end of which is connected to the source of the high-voltage device; and a simulation model, which uses a voltage control resistance value relationship to correct the resistance value of an external resistance. Compared with a traditional model, the resistance expression of the present application has a clear physical meaning, effectively improves the simulation accuracy of the lateral high-voltage device model, and has better convergence.

Description

Technical Field

[0001] This invention belongs to the field of power integrated circuit technology, specifically relating to a method for establishing and simulating an equivalent circuit model of a transverse high-voltage device. Background Technology

[0002] With the rapid popularization of electric vehicles and portable electronic devices, high-voltage power devices are increasingly being integrated into integrated circuit chips. For example, high-voltage power devices and their driving circuits can be integrated on a single chip on the same substrate to maximize system efficiency and minimize losses. As high-voltage integrated circuits and discrete high-voltage devices rapidly develop and are widely used, the accuracy requirements for device simulation models in circuit design are becoming increasingly stringent, especially for lateral high-voltage transistors. Lateral high-voltage transistors are widely used due to their easier compatibility with CMOS processes; however, they exhibit many difficult-to-characterize effects. These include the dynamic resistance of the transistor's drift region, reverse recovery characteristics, and self-heating effects at high power densities. These characteristics are often difficult to characterize using widely used BISM3 and BSIM4 models, and traditional high-voltage integrated circuit device simulation models are costly, inaccurate, and inefficient. Therefore, there is an urgent need for high-efficiency and high-accuracy lateral high-voltage transistor models and modeling methods. Summary of the Invention

[0003] To address the above requirements, this invention proposes a method for establishing an equivalent circuit model of a transverse high-voltage device and a simulation method thereon.

[0004] The technical solution of this invention is:

[0005] A method for establishing an equivalent circuit model of a transverse high-voltage device includes:

[0006] A core field-effect transistor is established, and the gate of the core field-effect transistor is used as the gate of a lateral high-voltage device.

[0007] Establish a first resistor, with one end connected to the drain of the core field-effect transistor (FET), and the other end serving as the drain of the lateral high-voltage device. Set the functional relationship between the resistance value of the first resistor and the drain-source voltage, gate-source voltage, temperature, transistor width, and cell number on the core FET as follows:

[0008] R drift =max(rconst,((rd0+rd1*V)) ds +(rd2*V ds / rd2_satur)*V ds / rd2_satur) / (rd0_satur+rd1_satur*V gs

[0009] ))) / (1+k1*V gs )))*(1+rd1_tem*ΔT+rd2_tem*ΔT 2 +rd3_tem*ΔT 3 ) / w / multi

[0010] Where rconst is the fixed resistance when the voltage difference between the drain and source of the transverse high-voltage device is small, rd0 is the first resistance value when the drain voltage is zero, and V ds V is the absolute value of the voltage difference between the drain and source of the core field-effect transistor. gs The absolute value of the gate-source voltage applied to the core field-effect transistor is given by rd1, rd2, rd2_satur, rd0_satur, rd1_satur, and k1, which are fitting parameters. rd1_tem, rd2_tem, and rd3_tem are the temperature coefficients of the first, second, and third order exponents of the first resistor, respectively. T is the system temperature, W is the width of the transistor, and multi is the number of transistor cells.

[0011] A second resistor is established, with one end connected to the source of the core field-effect transistor (FET), and the other end serving as the source of the lateral high-voltage device. The functional relationship between the resistance value of the second resistor and the drain-source voltage, gate-source voltage, temperature, transistor width, and cell number on the core FET is set as follows:

[0012] Rs=(rs1+rs2*nf*(V gs -V gs _ref)*V ds )*(1+rsh1_tem*ΔT+rsh2_tem*ΔT 2 +rsh3_tem*ΔT 3 ) / w / multi

[0013] Where rs1 is the fixed resistance when the voltage difference between the drain and source of the lateral high-voltage device is small, rs2 is the primary voltage coefficient when the drain-source voltage difference of the core field-effect transistor is large, nf is the primary voltage fitting parameter, and V gs _ref is the gate-source voltage correction term, and rsh1_tem, rsh2_tem, and rsh3_tem are the temperature coefficients of the first, second, and third order exponent terms of the second resistor, respectively.

[0014] A forward model of a solid diode is established, including the diode, cathode resistor, and cathode inductor. The cathode resistor and inductor are connected in parallel and then in series with the cathode of the diode. The anode of the diode is connected to the source of the lateral high-voltage device, and the other end of the cathode resistor is connected to the drain of the lateral high-voltage device.

[0015] Establish a reverse recovery model for a solid diode, connecting the positive terminal of the current source to the source of the high-voltage transistor and the other end to the drain of the high-voltage transistor;

[0016] Set the current source value I r With the voltage V across the cathode resistor R The relationship is:

[0017] I r =K*V R

[0018] Where K is the fitting coefficient.

[0019] Simulation methods include:

[0020] The source of the transverse high voltage device is grounded, the drain is fixed at 0.1V or 40V, the gate voltage is increased from 0-15V, and the circuit operating temperature is set to 25℃, thus obtaining the transfer characteristic curve of the transverse high voltage device.

[0021] With the gate fixed bias voltage at 3V, 6V, 9V, 12V or 15V, the source grounded, and the drain voltage increasing from 0-120V, and the circuit operating temperature set at 25℃, the output characteristic fitting curve of the transverse high voltage device is obtained.

[0022] The beneficial effects of this invention are as follows: by using the relationship between the corrected resistance value and the controlled voltage, resistance, temperature, device width and cell number to correct the resistance value of the external voltage-controlled resistor of the model, the accuracy of the device model is improved, and the parasitic effects of the device are reflected more accurately. At the same time, the mathematical expression of resistance used has good convergence and fast calculation speed, which makes the simulation model have high accuracy. Attached Figure Description

[0023] Figure 1 A schematic diagram of a lateral high-voltage transistor structure according to an embodiment of the present invention is shown. Figure 1 In the attached diagram, the labels are as follows: 10 is polysilicon, 11 is field oxide, 12 is collector metal, 13 is P+ region, 14 is N+ region; 15 is N-type drift region, 16 is buried oxide layer, 17 is P-type substrate, 18 is P-type base region, 19 is emitter metal, and 20 is gate oxide.

[0024] Figure 2 A circuit diagram of an equivalent circuit model of a lateral high-voltage transistor device according to an embodiment of the present invention is shown.

[0025] Figure 3 A flowchart illustrating a modeling method for a simulation model of a lateral high-voltage transistor device according to an embodiment of the present invention is shown.

[0026] Figure 4The diagram shows the transfer characteristic fitting curves of a lateral high-voltage transistor at an example Vds = 0.1V, based on an equivalent circuit model of the lateral high-voltage transistor device according to an embodiment of the present invention.

[0027] Figure 5 The diagram shows the transfer characteristic fitting curves of a lateral high-voltage transistor at an example Vds = 40V, based on an equivalent circuit model of the lateral high-voltage transistor device according to an embodiment of the present invention.

[0028] Figure 6 The diagram shows a fitting curve of the device output characteristics of an example lateral high-voltage transistor at a temperature of 25°C, based on an equivalent circuit model of the lateral high-voltage transistor device according to an embodiment of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be described below with reference to the accompanying drawings:

[0030] The lateral high-voltage transistor simulation model and modeling method described in this invention are applicable to Hspice simulation, Spectre simulation, etc., and their equivalent circuit is as follows: Figure 2 As shown, the structure of the lateral high-voltage transistor is as follows: Figure 1 As shown. Figure 2 It is based on the traditional BSIM4 model, with the addition of components that characterize some special structural characteristics of lateral high-voltage devices. The connection relationship of the external components in the traditional BSIM4 model is as follows:

[0031] The core field-effect transistor (FET) has a first drain resistor 102, the first end of which is connected to the drain of the core FET 101, and the second end of which serves as the drain of the high-voltage transistor. The core FET source resistor 103 has its first end connected to the source of the core FET 101, and its second end serves as the source of the high-voltage transistor. A cathode resistor 104 and a cathode inductor 105 are connected in parallel and then in series with the cathode of a diode 106, connecting the anode of the diode 106 to the source of the high-voltage transistor. The other end of the cathode resistor is connected to the drain of the high-voltage transistor. The positive terminal of the first current source is connected to the source of the high-voltage transistor, and the other end is connected to the drain of the high-voltage transistor.

[0032] The first drain resistor 102 is the parasitic series resistance of the core field-effect transistor's drain. Both the first drain resistor 102 and the first drain resistor 103 of the core field-effect transistor adopt the form of a voltage-controlled resistor. The isomorphic Max function of the first drain resistor 102 unifies the low drain voltage case and the high drain voltage case. Through this function, the operating drain-source voltage of the device can be distinguished more easily and accurately and controlled separately.

[0033] The functional relationship between the resistance value of the first drain resistor 102 and the drain-source voltage applied to the core field-effect transistor 101, the gate-source voltage of the core field-effect transistor 101, the temperature, and the width and cell number of the high-voltage transistor is as follows:

[0034] R drift =max(rconst,((rd0+rd1*V)) ds +(rd2*V ds / rd2_satur)*V ds / rd2_satur) / (rd0_satur+rd1_satur*V gs ))) /

[0035] (1+k1*V gs )))*(1+rd1_tem*ΔT+rd2_tem*ΔT 2 +rd3_tem*ΔT 3 ) / w / multi;

[0036] The functional relationship between the resistance value of the source resistor (103) of the core transistor and the drain-source voltage of the core field-effect transistor, the gate-source voltage of the core field-effect transistor 101, the temperature, and the width and cell number of the high-voltage device is: Rs=(rs1+rs2*nf*(V gs -V gs _ref)*V ds )*(1+rsh1_tem*ΔT+rsh2_tem*ΔT 2 +rsh3_tem*ΔT 3 ) / w / multi;

[0037] The body diode model includes a diode, a cathode resistor, a cathode inductor, and a first current source. The cathode resistor and inductor are connected in parallel and then in series with the diode's cathode. The diode anode is connected to the source of the lateral high-voltage device, and the other end of the cathode resistor is connected to the drain of the lateral high-voltage device. The positive terminal of the current source is connected to the source of the high-voltage transistor, and the other end is connected to the drain of the high-voltage transistor. The value I of the current source is set. r With the voltage V across the cathode resistor R The relationship is

[0038] I r =K*V R

[0039] When the body diode is forward-biased, it charges the cathode inductor, but this does not affect the diode's forward characteristic. When the diode is off, the cathode inductor discharges through a closed loop formed by itself and the cathode resistor. The discharge voltage curve of the inductor shows an exponentially decreasing curve. Therefore, this voltage is assigned to the first current source. The value of the first current source is 0 when the body diode is forward-biased, and the current during reverse recovery matches the voltage drop curve of the inductor. The current magnitude is adjusted using a factor K.

[0040] rconst is a fixed resistance when the voltage difference between the drain and source of the high-voltage transistor is small, rd0 is the resistance value of the first drain terminal 102 when the voltage is zero, V ds This refers to the absolute value of the drain-source voltage applied to the core field-effect transistor, V. gs The absolute value of the gate-source voltage applied to the core field-effect transistor is rd1, rd2, rd2_satur, rd0_satur, rd1_satur, and k1 are fitting parameters, and rd1_tem, rd2_tem, and rd3_tem are the temperature coefficients of the first, second, and third order exponential terms of the first drain resistance 102, respectively.

[0041] rs1 is a fixed resistor when the voltage difference between the drain and source of the high-voltage transistor is small, V ds rs2 is the absolute value of the voltage difference between the drain and source of the high-voltage transistor, rs2 is the primary voltage coefficient when the voltage difference between the collector and emitter of the high-voltage transistor is large, nf is the primary voltage fitting parameter, and V gs _ref represents the gate-source voltage correction term, and rsh1_tem, rsh2_tem, and rsh3_tem are the temperature coefficients of the first, second, and third order exponent terms of the source resistor 103, respectively. T is the system temperature, W is the width of the high-voltage transistor, and multi is the number of cells in the high-voltage transistor.

[0042] The source resistor 103 of this invention is designed to simulate the performance degradation phenomenon—self-heating effect—of a high-voltage transistor caused by heat accumulation due to high power density under a large drain bias. The formula for the source resistor 103 cleverly separates the cases for small and large collector bias. Under a small collector bias, the device power density is low and the self-heating effect is small, so the value of the emitter resistance expression is the previously mentioned threshold, which is a constant. The second term of the Rs function is a function related to the collector bias. When the collector bias is large, the second term is significantly larger than the fixed value of the first term of the Rs function. Therefore, the resistance value is equal to the value of the second term of the Rs function. Under a large collector bias, the resistance of 103 increases, leading to a decrease in the saturation current due to negative feedback, but this does not affect the characteristics under a small collector bias. Therefore, the self-heating effect of the device under high power density can be simulated effectively.

[0043] Temperature coefficients of at least third-order exponent terms have been added to the first drain resistor 102 and source resistor 103 mentioned above. These terms can be deleted or added as needed during use. This is because the resistance changes linearly within a certain temperature range, but the increase or decrease in resistance tends to saturate when the range is exceeded. Therefore, the higher-order term coefficients are used to fit the relationship between resistance and temperature under extreme temperature conditions such as -40℃, 125℃, 150℃, and 180℃.

[0044] Preferably, the first drain resistance 102 of the core field-effect transistor is a function of the number of cells and the width of the high-voltage transistor.

[0045] Preferably, the first drain resistance 102 of the core field-effect transistor is a function of the gate-source voltage of the core field-effect transistor 101.

[0046] Preferably, the first drain resistance 102 of the core field-effect transistor is a function of the drain-source voltage of the core field-effect transistor 101.

[0047] Preferably, the source resistance 103 of the core field-effect transistor is a function of the number and width of the source cells of the high-voltage transistor.

[0048] Preferably, the source resistance 103 of the core field-effect transistor is a function of the gate-source voltage of the core field-effect transistor 101.

[0049] Preferably, the source resistance 103 of the core field-effect transistor is a function of the drain-source voltage of the core field-effect transistor 101.

[0050] Preferably, the forward and reverse recovery characteristics of the body diode of the device are obtained by iterative calculation of the sub-circuit network composed of cathode resistor 104, cathode inductor 105, diode 106, and first current source 107.

[0051] Preferably, the modeling method further includes: the source resistance is a function of the source-drain bias voltage, and a threshold is set. When the function value is lower than the threshold, the emitter resistance is selected as the threshold value; otherwise, the function value is selected as the resistance value, thereby better simulating the characteristic that the high-voltage transistor has no self-heating effect at a small collector bias voltage but has a strong self-heating effect at a large collector bias voltage.

[0052] Preferably, the present invention also provides a modeling method for a simulation model of a lateral high-voltage transistor, such as... Figure 3 As shown, the following will be combined with Figure 1 and Figure 2 Explanation:

[0053] Those skilled in the art should understand that this modeling method can be rearranged, added, deleted, or replaced as needed.

[0054] In step 201, a model of the core field-effect transistor 101 is established; in step 202, a model of the first drain resistor 102 of the core field-effect transistor is established; in step 203, the establishment of the first drain resistor model of the core field-effect transistor is achieved by controlling the value of the first drain resistor using the voltage applied to the drain and the gate voltage of the core field-effect transistor; in step 204, the first terminal of the first drain resistor of the core field-effect transistor is electrically connected to the drain of the core field-effect transistor, and the second terminal of the second drain resistor is used as the drain of the high-voltage transistor; in step 205, a model of the source resistor of the core field-effect transistor is established. The model is established by using the voltage applied to the drain of the core field-effect transistor and the gate voltage to control the source resistance of the core field-effect transistor, and using the second end of the source resistor as the source of the high-voltage transistor; in step 206, the forward model of the body diode is established by connecting the cathode resistor and the inductor in parallel and then connecting them in series with the cathode of the diode, and connecting the anode of the diode to the source of the high-voltage transistor, and connecting the other end of the cathode resistor to the drain of the high-voltage transistor; in step 207, the reverse recovery model of the body diode is established by connecting the positive terminal of the first current source to the source of the high-voltage transistor, and connecting the other end to the drain of the high-voltage transistor.

[0055] The above description of the simulation model of the high-voltage transistor has described the components involved in the device simulation model and modeling method. Those skilled in the art can refer to this description. Figure 1 , Figure 2 ,and Figure 3 By combining the above familiar elements, one can understand its structure and operation.

[0056] The following is an example simulation model created according to the modeling method provided by the present invention, based on an embodiment of the present invention:

[0057]

[0058]

[0059]

[0060] The meanings of each parameter in the above simulation model example are as follows:

[0061] W: represents the width of the high-voltage transistor; l: represents the channel length of the core transistor; multi: represents the number of source cells of the high-voltage transistor; rd: represents the first drain resistance (102); m1: represents the core field-effect transistor (101); rsh: represents the source resistance (103); d1: represents the body diode (106); G1: represents the first current source of the core field-effect transistor (107); Rq: represents the resistor (104); Lq: represents the charge storage element (105).

[0062] rd1_tem_fir, rd2_tem_sec, and rd3_tem_thr are the temperature coefficients of the first, second, and third order exponential terms of the second drain resistance, respectively.

[0063] rconst is the fixed resistance when the voltage difference between the drain and source of the high-voltage transistor is small, rd0 is the resistance value of the first drain terminal resistor 102 when the voltage is zero, rs1 is the fixed resistance when the voltage difference between the drain and source of the high-voltage transistor is small, Vds is the absolute value of the voltage difference between the drain and source of the high-voltage transistor, rs2 is the primary voltage coefficient when the voltage difference between the collector and emitter of the high-voltage transistor is large, nf is the primary voltage fitting parameter, and Vgs_ref is the gate-source voltage correction term.

[0064] rsh1_tem_fir, rsh2_tem_sec, and rsh3_tem_thr are the temperature coefficients of the first, second, and third order exponential terms of the source resistance, respectively.

[0065] .subckt: indicates a sub-circuit;

[0066] ldmos: Indicates the name of the sub-circuit is ldmos; d: The node of the sub-circuit is also the drain of the device; g: Sub-circuit node - device gate; s: Sub-circuit node - device source; .model msub nmos: Indicates the type and name of the core field-effect transistor model, and the same applies to the diode model;

[0067] The above are merely preferred embodiments of the present invention and are not limited to the present invention. Those skilled in the art can make modifications according to their own needs.

[0068] By applying the above simulation model to a circuit, setting the transistor source to ground, the drain to a fixed 0.1V and 40V, and the high-voltage transistor gate voltage to increase from 0-15V, and then setting the circuit operating temperature to 25℃, the following can be obtained: Figure 4 , Figure 5 The transfer characteristic curves shown in the figure represent the model simulation results (solid line) and the actual test data of the embodiment structure (dots). We can see that the model fits very well under various temperature conditions. The model has high accuracy.

[0069] By fixing the gate bias of the model to 3V, 6V, 9V, 12V, and 15V, grounding the source, and increasing the drain voltage from 0-120V, and setting the circuit operating temperature to 25℃ for each, the following can be obtained: Figure 6 The output characteristic fitting curves are shown. The solid line represents the model simulation data, and the dots represent the actual test data of the embodiment structure. The results show that the present invention achieves excellent fitting results in all regions. The model exhibits high accuracy.

Claims

1. A method for establishing an equivalent circuit model of a transverse high-voltage device, characterized in that, include: A core field-effect transistor is established, and the gate of the core field-effect transistor is used as the gate of a lateral high-voltage device. Establish a first resistor, with one end connected to the drain of the core field-effect transistor (FET), and the other end serving as the drain of the lateral high-voltage device. Set the functional relationship between the resistance value of the first resistor and the drain-source voltage, gate-source voltage, temperature, transistor width, and cell number on the core FET as follows: R drift =max(rconst,((rd0+rd1*V ds +(rd2*V ds / rd2_satur)*V ds / rd2_satur) / (rd0_satur+rd1_satur*V gs ))) / (1+k1*V gs ) ))*(1+rd1_tem*∆T+rd2_tem*∆T 2 +rd3_tem*∆T 3 ) / w / multi, Where rconst is the fixed resistance when the voltage difference between the drain and source of the transverse high-voltage device is small, rd0 is the first resistance value when the drain voltage is zero, and V ds V is the absolute value of the voltage difference between the drain and source of the core field-effect transistor. gs The absolute value of the gate-source voltage applied to the core field-effect transistor is given by rd1, rd2, rd2_satur, rd0_satur, rd1_satur, and k1, which are fitting parameters. rd1_tem, rd2_tem, and rd3_tem are the temperature coefficients of the first, second, and third order exponents of the first resistor, respectively. ∆T is the system temperature, w is the width of the transistor, and multi is the number of transistor cells. A second resistor is established, with one end connected to the source of the core field-effect transistor (FET), and the other end serving as the source of the lateral high-voltage device. The functional relationship between the value of the second resistor and the drain-source voltage, gate-source voltage, temperature, transistor width, and cell number on the core FET is set as follows: Rs=(rs1+rs2*nf*(V gs -V gs _ref)*V ds )*(1+rsh1_tem*∆T+rsh2_tem*∆T 2 +rsh3_tem*∆T 3 ) / w / multi, Where rs1 is the fixed resistance when the voltage difference between the drain and source of the lateral high-voltage device is small, rs2 is the primary voltage coefficient when the drain-source voltage difference of the core field-effect transistor is large, nf is the primary voltage fitting parameter, and V gs _ref is the gate-source voltage correction term, and rsh1_tem, rsh2_tem, and rsh3_tem are the temperature coefficients of the first, second, and third order exponent terms of the second resistor, respectively. A forward model of a three-dimensional diode is established, including a diode, a cathode resistor, and a cathode inductor. The cathode resistor and inductor are connected in parallel and then in series with the cathode of the diode. The anode of the diode is connected to the source of the lateral high-voltage device, and the other end of the cathode resistor is connected to the drain of the lateral high-voltage device. Establish a reverse recovery model for a solid diode, connecting the positive terminal of the current source to the source of the high-voltage transistor and the other end to the drain of the high-voltage transistor; Set the current source value I r With the voltage V across the cathode resistor R The relationship is: I r = K*V R , Where K is the fitting coefficient.

2. A simulation method for an equivalent circuit model of a transverse high-voltage device as described in claim 1, characterized in that, The source of the transverse high voltage device is grounded, the drain is fixed at 0.1V or 40V, the gate voltage is increased from 0-15V, and the circuit operating temperature is set to 25℃, thus obtaining the transfer characteristic curve of the transverse high voltage device.

3. A simulation method for an equivalent circuit model of a transverse high-voltage device as described in claim 1, characterized in that, The gate fixed bias voltage is set to 3V, 6V, 9V, 12V or 15V respectively, the source is grounded, the drain voltage is increased from 0-120V, and the circuit operating temperature is set to 25℃, so as to obtain the output characteristic fitting curve of the transverse high voltage device.

Images