CN112214952B - Circuit simulation method for coupling total dose effect and process fluctuation - Google Patents

Abstract

The invention relates to a circuit simulation method for coupling total dose effect and process fluctuation. The method includes the determination of process parameters associated with the total dose effect, the irradiation test of the total dose of the transistor, the extraction of parameters from the degradation equation of the electrical parameters of the transistor, and the total dose effect of the transistor at different process angles. Model generation, circuit simulation at different process angles. The theoretical basis of this method is that the total dose radiation damage of the crystal is related to the process fluctuation parameters, and there is a coupling effect between the total dose radiation effect and the process fluctuation. The advantage of this method is that the coupling of the total dose effect and the process fluctuation is considered, and the characteristics of the integrated circuit working in the radiation environment are accurately simulated.

Description

A Circuit Simulation Method Coupling Total Dose Effect and Process Fluctuation

technical field

The invention belongs to the technical field of radiation-resistant integrated circuit design, and in particular relates to a circuit simulation method for coupling total dose effect and process fluctuation.

Background technique

There are process fluctuations in the production process of integrated circuits. Process parameters such as doping concentration, oxide thickness, and diffusion depth fluctuate between different wafers and different positions on the same wafer. Fluctuations in process parameters lead to fluctuations in electrical parameters of devices, such as threshold voltage, carrier mobility, etc., which affect the performance of integrated circuits. In order to analyze the influence of process fluctuations on circuit performance, the simulation of multiple process corners (FF, SF, SS, FS, TT) is set up in the circuit simulation, and the circuit characteristic parameters are required to meet the design requirements at the same time under multiple process corners.

Integrated circuits working in a radiation environment are affected by high-energy particles and cause radiation damage, which affects the reliability of integrated circuits. The total dose radiation effect is one of the important radiation damage effects. It is the permanent cumulative damage caused by the ionization of protons and electrons, which determines the longest period of use of the device in space, and is an important issue for high-orbit and long-life satellites. question. The total dose radiation effect produces oxide trap charges and interface trap charges in the oxide of the integrated circuit, which increases the power consumption and current of the integrated circuit, reduces the operating frequency, and even fails.

The total dose effect is also closely related to process parameters such as doping concentration and oxide thickness, which further aggravates the fluctuation of electrical parameters of the device caused by the fluctuation of process parameters. There is a coupling effect between the total dose effect and process fluctuation. Therefore, it is necessary to study the total dose effect and process fluctuation. Coupling Simulation Module. The total dose radiation makes the electrical parameters of the device drift (threshold voltage drift, etc.), and the difference in the process parameters of the device at different process angles leads to different amounts of drift of the electrical parameters, thereby broadening the statistical distribution of the electrical parameter fluctuations of the device, and the total dose effect is carried out separately. And the simulation of process fluctuation is difficult to cover the broadening effect of the statistical distribution of the electrical parameters of the above devices.

The invention provides a circuit simulation method of coupling total dose effect and process fluctuation, realizes the co-simulation of the influence of total dose effect and process fluctuation on circuit characteristics, and accurately simulates the characteristics of integrated circuits working in radiation environment.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a circuit simulation method for coupling the total dose effect and process fluctuations, the method includes the determination of the process parameters associated with the total dose effect, the irradiation test of the total dose of the transistor, the extraction of the parameters of the electrical parameter degradation equation of the transistor, and the transistors with different process angles. Total dose effect model generation, circuit simulation at different process angles. The theoretical basis of this method is that the total dose radiation damage of the crystal is related to the process fluctuation parameters, and there is a coupling effect between the total dose radiation effect and the process fluctuation. The advantage of this method is that the coupling of the total dose effect and the process fluctuation is considered, and the characteristics of the integrated circuit working in the radiation environment are accurately simulated.

A kind of circuit simulation method of coupling total dose effect and process fluctuation according to the present invention is carried out according to the following steps:

Determination of total dose effect related process parameters:

a. Determine the doping concentration of the transistor channel as the process parameter associated with the total dose effect;

Transistor total dose irradiation test:

b. Select 6-36 transistors with the same layout structure and threshold voltage type, test the transfer characteristic curves and output characteristic curves of the transistors, and then conduct a total dose irradiation test with the same dose rate and irradiation bias conditions for all transistors. Transfer characteristic curve and output characteristic curve of the post-test transistor;

Parameter extraction of transistor electrical parameter degradation equation:

c. The degradation equation of transistor electrical parameters is △Parameter=f(D, Nch), where △Parameter represents the drift of transistor electrical parameters caused by total dose radiation, D is the radiation dose, Nch is the channel doping concentration, and the function f( The expression of D, Nch) is related to the specific electrical parameters of the transistor and the corresponding radiation damage mechanism. The function f(D, Nch) contains fitting parameters, which need to be extracted according to the experimental data. According to the test results of the transistor transfer characteristic curve before irradiation , extract the transistor threshold voltage, and further calculate the transistor channel doping concentration, the specific calculation formula:

为本征费米能级与费米能级的电势差，ε_si为硅材料的电容率，C_ox为氧化物电容，q为电子电荷量。工艺波动导致版图结构、阈值电压类型相同晶体管阈值电压不同，进而沟道掺杂浓度不同，根据辐射剂量D后的晶体管转移特性曲线、输出特性曲线的测试结果，提取不同晶体管电参数退化△Parameter，获得△Parameter随Nch变化数据。依据△Parameter随Nch变化数据，提取函数f(D,Nch)中的拟合参数；where V _th is the threshold voltage, V _FB is the flat band voltage,

is the potential difference between the intrinsic Fermi level and the Fermi level, ε _si is the permittivity of the silicon material, C _ox is the oxide capacitance, and q is the amount of electron charge. Process fluctuations lead to different threshold voltages of transistors of the same layout structure and threshold voltage type, and thus different channel doping concentrations. According to the test results of the transistor transfer characteristic curve and output characteristic curve after radiation dose D, the electrical parameter degradation △Parameter of different transistors is extracted, Obtain ΔParameter variation data with Nch. According to the data that △Parameter changes with Nch, extract the fitting parameters in the function f(D, Nch);

Generation of the total dose effect model for transistors at different process angles:

d. Call the SPICE model of the device provided by the process manufacturer, simulate the transfer characteristic curves of the transistors in step c at FF, SF, SS, FS, TT process corners, extract the transistor threshold voltage, and calculate the transistors at different process corners according to the threshold voltage value. Nch, the calculation formula is consistent with step c, update the calculated value of Nch to the function f(D, Nch), add the transistor electrical parameter degradation equation to the SPICE model of the device provided by the process manufacturer, and generate the total dose effect SPICE of the transistor at different process angles Model;

Circuit simulation of different process corners:

e. Take the total dose effect model of different process angles generated in step d as a SPICE model, perform DC, transient, noise and stability simulations on the circuit to be studied respectively, and output the simulation results.

Compared with the prior art, the circuit simulation method for coupling total dose effect and process fluctuation according to the present invention has the following advantages:

1. Consider the influence of the total dose radiation effect and the coupling of process fluctuations on the characteristics of the integrated circuit.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

Description of drawings

Fig. 1 is the flow chart of the present invention;

Fig. 2 is 130nm SOI process IO NMOSFET Nch extraction result of the present invention;

FIG. 3 is the extraction result of fitting parameters of the electrical parameter degradation equation of the 130nm SOI process IO NMOSFET of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Example

A circuit simulation method for coupling total dose effect and process fluctuation according to the present invention, the specific operation is carried out according to the steps listed in Fig. 1:

Determination of total dose effect related process parameters:

a. Determine the transistor channel doping concentration (Nch) as the process parameter associated with the total dose effect;

Transistor total dose irradiation test:

b. Select 6-36 transistors with the same layout structure and threshold voltage type, test the transfer characteristic curve and output characteristic curve of the transistor, and then conduct a dose rate and total dose irradiation test for all transistors with the same irradiation bias conditions. Transfer characteristic curve and output characteristic curve of the post-test transistor;

Parameter extraction of transistor electrical parameter degradation equation:

c. The degradation equation of transistor electrical parameters is △Parameter=f(D, Nch), △Parameter represents the drift of transistor electrical parameters caused by total dose radiation, D is the radiation dose, Nch is the channel doping concentration, and the function f(D ,Nch) expression is related to the specific transistor electrical parameters and the corresponding radiation damage mechanism. The function f(D,Nch) contains fitting parameters, which need to be extracted according to the experimental data. According to the test results of the transistor transfer characteristic curve before irradiation, The threshold voltage of the transistor is extracted, and the doping concentration of the transistor channel is further calculated. The specific calculation formula is as follows:

为本征费米能级与费米能级的电势差，ε_si为硅材料的电容率，C_ox为氧化物电容，q为电子电荷量。工艺波动导致版图结构、阈值电压类型相同晶体管阈值电压不同，进而沟道掺杂浓度不同。根据辐射剂量D后的晶体管转移特性曲线、输出特性曲线的测试结果，提取不同晶体管电参数退化△Parameter，获得△Parameter随Nch变化数据，依据△Parameter随Nch变化数据，提取函数f(D,Nch)中的拟合参数；where V _th is the threshold voltage, V _FB is the flat band voltage,

is the potential difference between the intrinsic Fermi level and the Fermi level, ε _si is the permittivity of the silicon material, C _ox is the oxide capacitance, and q is the amount of electron charge. Process fluctuations lead to different threshold voltages of transistors with the same layout structure and threshold voltage type, and thus different channel doping concentrations. According to the test results of the transistor transfer characteristic curve and output characteristic curve after the radiation dose D, the electrical parameter degradation △Parameter of different transistors is extracted, and the change data of △Parameter with Nch is obtained. According to the change data of △Parameter with Nch, the function f(D,Nch is extracted ) in the fitting parameters;

Figure 2 shows the extraction results of 130nm SOI process IO NMOSFET Nch. The total dose irradiation leads to an increase in off-state leakage current (I_off) of 130nm process IO NMOSFET, and △Ioff=f(D,Nch)=a-b*Nch, where a, b is the fitting parameter; Figure 3 shows the extraction result of the fitting parameter of the electrical parameter degradation equation of the 130nm SOI process IO NMOSFET;

Generation of the total dose effect model for transistors at different process angles:

d. Call the SPICE model of the device provided by the process manufacturer, simulate the transfer characteristic curves of the transistors in step c at FF, SF, SS, FS, TT process corners, extract the transistor threshold voltage, and calculate the transistors at different process corners according to the threshold voltage value. Nch, the calculation formula is consistent with step c, update the calculated value of Nch to the function f(D, Nch), add the transistor electrical parameter degradation equation to the SPICE model of the device provided by the process manufacturer, and generate the total dose effect SPICE of the transistor at different process angles Model;

Circuit simulation of different process corners:

e. Taking the total dose effect model of different process angles generated in step d as a SPICE model, and performing DC, transient, noise, and stability simulations on the circuit to be studied respectively, and outputting the simulation results.

The circuit simulation method for coupling the total dose effect and the process fluctuation according to the present invention has the effect of accurately simulating the radiation response characteristics of the circuit total dose under different process angle conditions.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone familiar with the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (1)

1. a circuit simulation method of total dose effect and process fluctuation coupling is characterized in that carrying out by the following steps: Determination of total dose effect related process parameters: a. Determine the doping concentration of the transistor channel as the process parameter associated with the total dose effect; Transistor total dose irradiation test: b. Select 6-36 transistors with the same layout structure and threshold voltage type, test the transfer characteristic curves and output characteristic curves of the transistors, and then conduct a total dose irradiation test with the same dose rate and irradiation bias conditions for all transistors. Transfer characteristic curve and output characteristic curve of the post-test transistor; Parameter extraction of transistor electrical parameter degradation equation: c. The degradation equation of the electrical parameters of the transistor is ΔParameter=f(D, Nch), where ΔParameter represents the drift of the electrical parameters of the transistor caused by the total dose of radiation, D is the radiation dose, Nch is the channel doping concentration, and the function f(D, The expression of Nch) is related to the specific electrical parameters of the transistor and the corresponding radiation damage mechanism. The function f(D, Nch) contains fitting parameters, which need to be extracted according to the experimental data. According to the test results of the transistor transfer characteristic curve before irradiation, extract Transistor threshold voltage, and further calculate the transistor channel doping concentration, the specific calculation formula:

where V _th is the threshold voltage, V _FB is the flat band voltage,

is the potential difference between the intrinsic Fermi level and the Fermi level, ε _si is the permittivity of the silicon material, C _ox is the oxide capacitance, q is the amount of electron charge, and process fluctuations lead to the same transistor threshold voltage of layout structure and threshold voltage type According to the test results of the transistor transfer characteristic curve and the output characteristic curve after the D irradiation dose, the electrical parameter degradation ΔParameter of different transistors is extracted, and the data of the change of ΔParameter with Nch is obtained, and the data of the change of ΔParameter with Nch is obtained. , extract the fitting parameters in the function f(D, Nch); Generation of the total dose effect model for transistors at different process angles: d. Call the device SPICE model provided by the process manufacturer, simulate the transfer characteristic curves of the transistors in step c at FF, SF, SS, FS, TT process corners, extract the transistor threshold voltage, and calculate the transistors at different process corners according to the threshold voltage value. Nch, the calculation formula is consistent with step c, update the calculated value of Nch to the function f(D, Nch), and add the transistor electrical parameter degradation equation to the device SPICE model provided by the process manufacturer to generate the total dose of transistors at different process angles Effect SPICE model; Circuit simulation of different process corners: e. Perform DC, transient, noise and stability simulations on the circuit to be studied with the SPICE models of total dose effects at different process angles generated in step d, and output the simulation results.

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