Energy threshold based scr esd protection device thermal failure temperature prediction method

Abstract

This invention discloses a method for predicting the thermal failure temperature of SCR ESD protection devices based on energy thresholds, specifically including the following steps: Step 1, determining the thermal failure judgment conditions of the SCR ESD protection device; Step 2, calculating the estimated failure temperature T of the SCR ESD protection device. c Obtain the estimated failure temperature T c The corresponding TLP current pulse amplitude is then defined as the estimated failure current I. f Step 3: Calculate the failure energy threshold E of the SCR ESD protection device. F Step 4: Calculate the actual energy E that the SCR ESD protection device can withstand; Step 5: Based on Step 3, obtain the failure energy threshold E of the SCR ESD protection device. F The actual energy E that the SCR ESD protection device withstands, obtained in step 4, is used to determine failure. This invention solves the problem of excessively large prediction errors in existing prediction methods for thermal failure temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microelectronics and solid-state electronics, and relates to a method for predicting the thermal failure temperature of an SCR ESD protection device based on an energy threshold. BACKGROUND

[0002] ESD (electrostatic discharge) seriously affects the reliability and service life of electronic devices. With the reduction of semiconductor process size and the increase of working frequency, the importance of ESD protection technology is increasingly prominent. As a commonly used ESD protection device, SCR (silicon controlled rectifier) has high current carrying capacity and fast response characteristics, but its thermal management problem is prominent and is prone to thermal failure due to high temperature. At present, the research on SCR ESD protection devices mainly focuses on optimizing their trigger voltage, holding voltage and other electrical performance indicators, and the research on their thermal failure is relatively weak. Traditional thermal failure analysis methods are usually based on two boundary conditions: one is that when the peak temperature of the device reaches the melting temperature of silicon (about 1414℃), the device is considered to fail at this time; in fact, the device often fails due to thermal runaway at much lower temperature than the material melting temperature. The second is that when the thermal generated carrier concentration of the device is equal to the background doping concentration, the peak temperature of the device is defined as the thermal failure temperature. This method only defines the thermal failure temperature of the device based on the static equilibrium concentration of the carrier, without fully considering the dynamic changes of the thermal generated carrier and the actual bearing capacity of the device, resulting in deviation of the results. In addition, experimental measurement is intuitive, but it has a lag, increasing the research and development cost and cycle. Therefore, it is urgent to study the thermal failure mechanism of SCR ESD protection devices, so as to establish a method to predict the thermal failure temperature of the device and improve the device development efficiency. SUMMARY

[0003] The purpose of the present application is to provide a method for predicting the thermal failure temperature of an SCR ESD protection device based on an energy threshold, which solves the problem of excessive prediction error of the thermal failure temperature of the device in the existing prediction method.

[0004] The technical solution adopted by the present application is a method for predicting the thermal failure temperature of an SCR ESD protection device based on an energy threshold, which specifically comprises the following steps:

[0005] Step 1, determining the thermal failure judgment condition of the SCR ESD protection device;

[0006] Step 2, calculating the estimated failure temperature T of the SCR ESD protection device based on the thermal failure judgment condition determined in step 1 c , obtaining the corresponding TLP current pulse amplitude of the estimated failure temperature T c by Sentaurus simulation, and defining the TLP current pulse amplitude as the estimated failure current I f ;

[0007] Step 3, based on the estimated failure temperature T c Calculate the failure energy threshold E of the SCR ESD protection device F ;

[0008] Step 4, calculate the actual energy E of the SCR ESD protection device

[0009] Step 5, based on the failure energy threshold E of the SCR ESD protection device obtained in step 3 F and the actual energy E of the SCR ESD protection device obtained in step 4, make a failure judgment.

[0010] The present application is also characterized in that:

[0011] In step 1, the thermal failure judgment condition of the SCR ESD protection device is:

[0012] When the heat generation carrier concentration of the thermal concentration area of the SCR ESD protection device is equal to the background doping concentration of the SCR ESD protection device, the actual energy of the device thermal concentration area is greater than or equal to the failure energy threshold E of the device at that temperature F .

[0013] The specific process of step 2 is:

[0014] Based on the thermal failure judgment condition of the SCR ESD protection device determined in step 1, let the heat generation carrier concentration n d of the thermal concentration area of the SCR ESD protection device be equal to the background doping concentration of the SCR ESD protection device, and the heat generation carrier concentration n d of the SCR ESD protection device satisfies the formula (1) in relation to the estimated failure temperature T c .

[0015] (1)

[0016] Since n d is known, the estimated failure temperature T c of the SCR ESD protection device is obtained by formula (1), and the corresponding TLP current pulse amplitude at the estimated failure temperature T c is obtained in Sentaurus simulation, and the TLP current pulse amplitude is defined as the estimated failure current I f .

[0017] The specific process of step 3 is:

[0018] When the applied TLP pulse width t is in the range of 100ns to 20 , the failure power P fThe relationship between t and T satisfies equation (2):

[0019] (2)

[0020] where A is the area of the heat concentration region of the SCR ESD protection device, K is the thermal conductivity of the material of the SCR ESD protection device, p is the density of the material of the SCR ESD protection device, C p is the specific heat capacity of the material of the SCR ESD protection device, and T0 is the ambient temperature.

[0021] The failure power P f of the SCR ESD protection device is integrated on t to obtain the expression of the failure energy threshold E F of the SCR ESD protection device, as shown in equation (3):

[0022] (3)

[0023] where t is the pulse width of the TLP.

[0024] The specific process of step 4 is as follows:

[0025] For the thermal runaway of the SCR ESD protection device, a rectangular black box heat source model is used for analysis, assuming that all the power of the SCR ESD protection device is concentrated in the rectangular black box heat source, and the peak temperature T max of the SCR ESD protection device is represented as:

[0026] (4)

[0027] where is the temperature rise, and the relationship between the power P t satisfies the following piecewise function:

[0028] (5)

[0029] (6)

[0030] (7)

[0031] (8)

[0032] where D is the thermal diffusivity of the material of the SCR ESD protection device, p is the density of the material of the SCR ESD protection device, t a , t b , and t c are three time constants, respectively, and are defined as follows:

[0033] (9)

[0034] (10)

[0035] (11)

[0036] (12)

[0037] Wherein, a, b, c are length, width, height of the rectangular black-box heat source respectively;

[0038] Equations (5)-(8) reflect the power actually borne by the heat concentration area of the SCR ESD protection device at different times, and the power P t is integrated at t to obtain the energy E actually borne by the SCR ESD protection device, and the expression is as follows:

[0039] (13).

[0040] The specific process of step 5 is as follows:

[0041] Compare the estimated failure current I f with the failure energy threshold E F of the SCR ESD protection device, and determine whether the SCR ESD protection device fails according to the comparison result.

[0042] In step 5, there are three comparison results as follows:

[0043] 1) If the estimated failure current I f is equal to the failure energy threshold E F of the SCR ESD protection device, it is determined that the SCR ESD protection device fails at this time, and the estimated failure temperature T c of the SCR ESD protection device at this time is the actual thermal failure temperature T;

[0044] 2) If the estimated failure current I f is lower than the failure energy threshold E F of the SCR ESD protection device, it is determined that the SCR ESD protection device does not fail at this time;

[0045] 3) If the estimated failure current I f is higher than the failure energy threshold E F of the SCR ESD protection device, it is determined that the SCR ESD protection device fails.

[0046] In step 5, when the comparison result 2) occurs, the TLP current pulse amplitude is increased, the peak temperature of the SCR ESD protection device changes after the current pulse amplitude is increased, and the actual power borne at the same time changes, thus, the actual energy E borne by the device needs to be recalculated and compared with the failure energy threshold E F Comparison is performed until the SCR ESD protection device fails;

[0047] When the comparison result 3) occurs, the TLP current pulse amplitude is reduced, the peak temperature of the device changes after the current pulse amplitude is reduced, and the actual power borne at the same time changes, thus, the actual energy E borne by the device needs to be recalculated and compared with the failure energy threshold E F Comparison is performed until the SCR ESD protection device does not fail;

[0048] Through processing of the comparison result 2) and the comparison result 3), the TLP current pulse amplitude interval in which the SCR ESD protection device fails and does not fail is determined;

[0049] In the TLP current pulse amplitude interval in which the SCR ESD protection device fails and does not fail, the interval is gradually reduced by using the dichotomy, and the processing process of the comparison result 2) and the comparison result 3) is repeated in the reduced interval, until the error between the actual energy E borne and the failure energy threshold E F reaches the expected precision, and finally the failure current pulse amplitude I of the SCR ESD protection device when thermal failure occurs is obtained; using the Sentaurus software, the SCR ESD protection device temperature amplitude T corresponding to the SCR ESD protection device when the applied TLP current pulse amplitude reaches the failure current pulse amplitude I is obtained, and at this time, the peak temperature T of the SCR ESD protection device is the temperature at which the SCR ESD protection device actually thermally fails.

[0050] The beneficial effects of the present application are that the present application comprehensively considers the thermal distribution and carrier behavior of the device, and combines the heat generation and heat dissipation mechanism, and proposes a new method for predicting the thermal failure temperature of the SCR ESD protection device from the energy threshold. Different from the traditional method which only depends on the static temperature or carrier concentration, the present method breaks through these limitations and further considers the energy accumulation effect of the device with the TLP pulse width under stress, rather than only relying on the instantaneous power to measure the bearing capacity of the device. Therefore, the method can more comprehensively and accurately reflect the thermal load and actual bearing capacity of the device, conforms to the physical mechanism of device failure, and thus provides more accurate thermal failure prediction. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1Fig. 1 is a structural schematic diagram of an SCR ESD protection device;

[0052] Fig. 2(a) is a lattice temperature distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.0001 A / cm2; Fig. 2(b) is a lattice temperature distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.01 A / cm2;

[0053] Fig. 3(a) is a potential distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.0001 A / cm2;

[0054] Fig. 3(b) is a potential distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.01 A / cm2;

[0055] Fig. 3(c) is a current density distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.0001 A / cm2;

[0056] Fig. 3(d) is a current density distribution diagram of the SCR ESD protection device under a TLP current pulse amplitude of 0.01 A / cm2;

[0057] Figure 4 Fig. 4 is a flow chart of the SCR ESD protection device thermal failure temperature prediction method based on an energy threshold value of the present application;

[0058] Figure 5 Fig. 5 is a hot spot distribution schematic diagram of the SCR ESD device in the SCR ESD protection device thermal failure temperature prediction method based on an energy threshold value of the present application;

[0059] Figure 6 Fig. 6 is a device temperature change curve under different TLP current pulse amplitudes in the SCR ESD protection device thermal failure temperature prediction method based on an energy threshold value of the present application;

[0060] Figure 7 Fig. 7 is a device power-TLP pulse width curve under a failure current pulse I f of the SCR ESD protection device thermal failure temperature prediction method based on an energy threshold value of the present application. DETAILED DESCRIPTION

[0061] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0062] The SCR ESD protection device thermal failure temperature prediction method based on an energy threshold value of the present application, as shown in Fig. 1, is a structure of an SCR ESD protection device. Figure 1 ​​​​​As shown, the SCR ESD protection device is taken as the research object, the device is provided with parallelly arranged N-type well region and P-type well region in the P-type substrate, and is provided with N+ region and P+ region on the surface of the N-type well region and the P-type well region, and is connected with the anode and the cathode respectively. The active regions are separated by shallow trench isolation. When the anode of the device is subjected to ESD stress, the PNP transistor structure composed of the anode P+ region, the N-type well region and the cathode P+ region (P+ of the N-type well region) is taken as the main trigger path, and the device is triggered to work. Subsequently, the PNPN structure composed of the anode P+ region, the N-type well region, the P-type well region and the cathode N+ region is taken as the main path of current discharge.

[0063] In order to explore the thermal failure mechanism of the device, the heat distribution characteristics of the device are simulated and analyzed based on the Sentaurus software. First, the heat distribution characteristics of the device under the action of different TLP (transmission line pulse) current pulse amplitudes are simulated. FIG. 2 (a) (the legend Lattice Temperature in the figure refers to the device lattice temperature) and FIG. 2 (b) (the legend Lattice Temperature in the figure refers to the device lattice temperature) respectively show the lattice temperature distribution of the SCR ESD protection device under the action of 0.0001A / and 0.01A / TLP current pulse. As can be seen from the figures, under the action of smaller TLP current pulse, the high temperature risk point is located at J1 junction (the PN junction composed of the cathode P+ region and the N-type well region), and under the action of larger TLP current pulse, the high temperature risk point is transferred to J2 junction (the PN junction composed of the N-type well region and the P-type well region). The J1 junction (the PN junction composed of the cathode P+ region and the N-type well region) will experience higher temperature in the triggering process, but this phenomenon only appears near the triggering state, and has little effect on the overall device. In contrast, the temperature distribution of the J2 junction (the PN junction composed of the N-type well region and the P-type well region) is the key factor determining the thermal characteristics of the device.

[0064] Further simulation shows that the device under study has a thermal breakdown at 0.0001A / , 0.01A / The potential distribution and the current density distribution under the action of TLP current pulse are shown in Figures 3(a) (the legend Electrostatic Potential in the figure refers to the potential of the device), 3(b) (the legend Electrostatic Potential in the figure refers to the potential of the device), 3(c) (the legend Abs (Total Current Density) in the figure refers to the current density of the device) and 3(d) (the legend Abs (Total Current Density) in the figure refers to the current density of the device), respectively. By comparing and analyzing the potential and the current density of J1 junction (the PN junction formed by the cathode P+ region and the N-type well region) and J2 junction (the PN junction formed by the N-type well region and the P-type well region) under the action of different TLP pulses (transmission line pulse), it can be concluded that the reason for the failure of the device is the current concentration, and the fundamental reason for the current concentration is the local aggregation of carriers.

[0065] Embodiment 1

[0066] The energy threshold-based SCR ESD protection device thermal failure temperature prediction method of the present application specifically comprises the following steps:

[0067] Step 1, determining the SCR ESD protection device thermal failure determination condition;

[0068] Step 2, calculating the estimated failure temperature T of the SCR ESD protection device c , obtaining the corresponding TLP current pulse amplitude of the estimated failure temperature T c by Sentaurus simulation, and defining the TLP current pulse amplitude as the estimated failure current I f ;

[0069] Step 3, calculating the failure energy threshold E of the SCR ESD protection device F ;

[0070] Step 4, calculating the energy E actually borne by the SCR ESD protection device;

[0071] Step 5, failure determination.

[0072] Embodiment 2

[0073] The specific process of step 1 is as follows: based on the above analysis of the thermal failure reason of the studied SCR ESD protection device, it can be concluded that the root cause of the thermal failure of the SCR ESD protection device is the carrier aggregation inside the SCR ESD protection device. Combined with the thermal failure mechanism of the SCR ESD protection device and its actual bearing capacity, the judgment condition of the thermal failure of the SCR ESD protection device is: when the SCR ESD protection device occurs thermal failure, the thermal generated carrier concentration of the SCR ESD protection device in the thermal concentration area is equal to the background doping concentration level of the SCR ESD protection device, so that the actual bearing energy E of the SCR ESD protection device is equal to or exceeds the failure energy threshold E F , thereby causing the thermal failure of the device. Based on the thermal failure judgment condition defined in the present application, the thermal failure temperature of the device is further predicted through theoretical derivation.

[0074] Embodiment 3

[0075] The specific process of step 2 is as follows: based on the thermal failure judgment condition of the SCR ESD protection device proposed in the present application (given by step 1), combined with the specific doping concentration of the SCR ESD protection device, the thermal generated carrier concentration n d of the SCR ESD protection device in the thermal concentration area is equal to the background doping concentration (the specific doping concentration of the research object), and the peak temperature T c of the SCR ESD protection device at this time is calculated. c And T d is defined as the estimated failure temperature. At this temperature, the relationship between the thermal generated carrier concentration n c of the SCR ESD protection device and the temperature satisfies formula (1):

[0076] (1)

[0077] According to formula (1), combined with the doping concentration of the selected SCR ESD protection device in the thermal concentration area, the estimated failure temperature T f of the SCR ESD protection device (i.e. the peak temperature inside the device at this time) can be calculated. In the Sentaurus software simulation, the temperature of the SCR ESD protection device has a one-to-one corresponding relationship with the applied TLP current pulse amplitude. Therefore, the corresponding TLP current pulse amplitude at this temperature can be obtained through the Sentaurus simulation software, and it is defined as the estimated failure current I c .

[0078] After obtaining the estimated failure temperature T f of the SCR ESD protection device and the estimated failure current I F(Step 3) and the energy E (Step 4) actually borne by the device, and compare the two to determine whether the device has failed.

[0079] Embodiment 4

[0080] The specific process of Step 3 is that the thermal breakdown characteristics of the SCR ESD protection device are closely related to the applied TLP pulse width, and when the applied pulse width is 100 ns to 20 μs, the SCR ESD protection device fails at a power P f in the range, and the relationship between the TLP pulse width t and the power P

[0081] (2)

[0082] where A is the area of the thermal concentration region of the SCR ESD protection device (the device area factor is 1 by default in simulation), K is the thermal conductivity of the material (silicon) of the SCR ESD protection device, p is the density of the material (silicon) of the SCR ESD protection device, C p is the specific heat capacity of the material (silicon) of the SCR ESD protection device. T c is the failure temperature of the SCR ESD protection device, and T0 is the ambient temperature.

[0083] The power as the failure judgment basis mainly focuses on the size of the instantaneous thermal power, which can reflect the power load of the device at a certain moment, but ignores the cumulative effect of the power of the SCR ESD protection device on the TLP pulse width. In contrast, the failure judgment method based on energy directly quantifies the total energy absorbed by the device during the entire SCR ESD protection device pulse by integrating the power with respect to the TLP pulse width, thereby more comprehensively and accurately reflecting the thermal load and actual bearing capacity of the SCR ESD protection device, and more in line with the physical mechanism of the failure of the SCR ESD protection device. Therefore, the integral of the power with respect to the TLP pulse width gives the expression of the device failure energy threshold E F , as shown in equation (3):

[0084] (3)

[0085] where t is the TLP pulse width. Using the Matlab tool to calculate equations (2) and (3), the device failure energy threshold E F can be obtained, which is used as a standard for subsequent comparison.

[0086] Embodiment 5

[0087] The specific process of Step 4 is:

[0088] For thermal runaway of SCR ESD protection device, a rectangular black-box heat source model can be used for analysis. The model assumes that all the power is concentrated in a rectangular black-box heat source, and the peak temperature T max may be expressed as:

[0089] (4)

[0090] where T0 is the initial temperature (i.e. ambient temperature) of the SCR ESD protection device, is the temperature rise, which is related to the power P t by the following piecewise function:

[0091] (5)

[0092] (6)

[0093] (7)

[0094] (8)

[0095] where K is the thermal conductivity of the SCR ESD protection device material (silicon), C p is the specific heat capacity of the SCR ESD protection device material (silicon), D is the thermal diffusivity of the SCR ESD protection device material (silicon), p is the density of the SCR ESD protection device material (silicon), t a , t b , t c are the three time constants, respectively, defined as follows:

[0096] (9)

[0097] (10)

[0098] (11)

[0099] (12)

[0100] where a, b, c are the length, width and height of the rectangular black-box heat source. The rectangular black-box heat source is a idealized model for describing these hotspot concentrated areas, which can effectively characterize the thermal effect characteristics of local heat source. The rectangular black-box heat source refers to a regular shape, uniform power density distribution of the heat source area, which aims to simulate the actual hotspot area inside the device in ESD events. Through the model, the complex thermal distribution problem can be simplified. Among them, the length and height (a, c) of the rectangular black-box heat source can be determined by the distribution range of the device hotspot area obtained by Sentaurus software, and the width (b) of the rectangular black-box heat source generally refers to the area factor of the device during simulation (in order to keep consistent with the area of the device heat concentrated area in formula (1), the area factor is usually taken as 1).

[0101] Formulas (5)-(8) reflect the actual power actually borne by the device heat concentrated area at different times. Similarly, the power P t The integral of the TLP pulse width is obtained, and the actual energy E borne by the device is obtained. The expression is as follows:

[0102] (13)

[0103] The temperature rise involved in formulas (5)-(8) is a parameter that changes with time, and the specific value can be obtained by Sentaurus software. The specific method is as follows: first, use Sentaurus software to obtain the highest temperature T max of the device under the corresponding TLP current pulse amplitude, and export the data to Excel. Then, subtract the ambient temperature T0 from it to obtain the temperature rise T at different time points, and save the temperature rise data as a file. Then, import the temperature rise file using Matlab tool, and calculate according to formulas (5)-(13) to obtain the actual energy E borne by the device.

[0104] Example 6

[0105] The specific process of step 5 is as follows: through steps 3 and 5, the device failure energy threshold E f of the SCR ESD protection device under the estimated failure current I F and the actual energy E borne by the device can be obtained, and then the device failure can be determined.

[0106] 1) Compare the actual energy borne by the SCR ESD protection device (calculated by step 4) and the failure energy threshold of the SCR ESD protection device (calculated by step 3) under the estimated failure current I f .

[0107] 2) If the actual energy borne by the SCR ESD protection device is less than the failure energy threshold of the SCR ESD protection device under the estimated failure current I fThe actual energy E borne by the SCR ESD protection device is equal to the failure energy threshold E of the SCR ESD protection device F If the actual energy E borne by the SCR ESD protection device is equal to the failure energy threshold E of the SCR ESD protection device, it is determined that the SCR ESD protection device has just failed at this time, and the estimated failure temperature T of the SCR ESD protection device at this time is c That is, the temperature T at which the SCR ESD protection device actually fails thermally.

[0108] 3) If the estimated failure current I f The actual energy E borne by the SCR ESD protection device is lower than the failure energy threshold E of the device F If the actual energy E borne by the SCR ESD protection device is lower than the failure energy threshold E of the device, it is determined that the SCR ESD protection device has not failed at this time. In this case, the TLP current pulse amplitude is increased, and the peak temperature of the SCR ESD protection device also changes after the current pulse amplitude is increased, and the actual power borne at the same time also changes, so the actual energy E borne by the device needs to be recalculated and compared with the failure energy threshold E F until the SCR ESD protection device fails.

[0109] 4) If the estimated failure current I f The actual energy E borne by the SCR ESD protection device exceeds the failure energy threshold E of the SCR ESD protection device F If the actual energy E borne by the SCR ESD protection device exceeds the failure energy threshold E of the SCR ESD protection device, it is determined that the SCR ESD protection device has failed. At this time, the TLP current pulse amplitude can be reduced, and the peak temperature of the device also changes after the current pulse amplitude is reduced, and the actual power borne at the same time also changes, so the actual energy E borne by the device needs to be recalculated and compared with the failure energy threshold E F until the SCR ESD protection device fails.

[0110] 5) Through steps 3) or 4), the TLP current pulse amplitude interval in which the SCR ESD protection device fails and does not fail can be determined.

[0111] 6) Within the TLP current pulse amplitude interval in which the SCR ESD protection device fails and does not fail, the interval is gradually reduced by using the bisection method, and steps 3) to 5) are repeated in the reduced interval. This process can be repeated until the desired accuracy is reached (the actual energy borne and the failure energy threshold error are required to be less than 0.5% in the present application). Finally, the failure current pulse amplitude I at which the SCR ESD protection device fails thermally can be obtained.

[0112] 7) Using Sentaurus software, obtain the temperature amplitude T of the SCR ESD protection device when the amplitude of the applied TLP current pulse reaches the amplitude of the failure current pulse I. The peak temperature T of the SCR ESD protection device at this time is the actual temperature at which the SCR ESD protection device experiences thermal failure.

[0113] Example 7

[0114] The characteristic parameters of the SCR ESD protection device (silicon material) required for the prediction method proposed in this invention are as follows: K = 1.5 (W / cm·K) (thermal conductivity of semiconductor device material (silicon)), ρ = 2.34 g / cm 3 (Density of semiconductor device material (silicon)), C p =700 J / (kg·K) (Specific heat capacity of semiconductor device material (silicon)). According to Figure 5 The hotspot distribution diagram of the selected SCR ESD protection device shown indicates that the area of ​​the heat concentration region of the device is A = 0.72. .

[0115] Based on equation (1), the estimated failure temperature T of the device can be calculated. c =1000K. Since there is a one-to-one correspondence between device temperature and TLP current pulse amplitude in Sentaurus simulation software, the temperature change of the device under different TLP current pulse amplitudes can be derived, such as... Figure 6 As shown. Combined with the estimated failure temperature T of the SCR ESD protection device. c The specific value can determine the estimated failure temperature T. C Corresponding failure prediction current I f =0.05A / .

[0116] Subsequently, the failure energy threshold E of the device is obtained through equations (2)-(3). F = 4.31×10 -9 J. Based on the definition of the black box heat source model, the length, width, and height (a, b, c) of the rectangular black box heat source are 0.8. 、 1.0 、 0.9 (The area factor used in this simulation is 1, therefore the width of the rectangular black box heat source is 1.0.) Length and height are determined by Figure 5 (The range of the heat concentration area shown is determined by...)

[0117] Further, based on equations (9) to (12), the relevant variable D can be calculated as 9.16 × 10⁻⁶. -5 m2 / s thermal diffusivity of semiconductor device material (silicon), t a =8.687×10 -10 s, t b =5.560×10 -10 s, t c =4.257×10 -10 s(t) a ,t b , t c These are three time constants. Combining equations (5) to (12), the actual power borne by the device changes with time, and power-time curves are generated using Matlab software (e.g., Figure 7 (As shown). This only shows the device at the estimated failure current I. f The power-time curves under different current pulse amplitudes are generated in the same way.

[0118] Further integration of the power-time curve using Matlab tools yields the device's predicted failure current I. f The actual energy absorbed by the device is E = 4.7505 × 10⁻⁶. -9 J. Comparing the device's failure energy threshold with the actual energy it absorbed, it was found that the device had already failed. To further refine the failure current range, the TLP current pulse amplitude was gradually reduced. When the TLP current pulse amplitude decreased to 0.048A / At this time, combining equations (5) to (13), the actual energy E that the device withstands can be calculated as E = 4.2586 × 10⁻⁶. -9 J, the device fails. Therefore, the TLP current pulse amplitude range between device failure and non-failure is determined to be [0.048, 0.05]. Within this range, a bisection method is used to further narrow down the failure current range. This calculation is repeated until the target accuracy is achieved (in this example, the error between the actual energy received and the failure energy threshold must not exceed 0.5%), at which point the repetition process can be stopped. Finally, the TLP current amplitude corresponding to the failure current can be determined to be 0.04825 A / At this point, the thermal failure temperature T of the device is 941 K.

[0119] Although the actual unit area energy of the device deviates from the theoretical unit area failure energy threshold by about 0.3%, the error is acceptable in engineering applications. Compared with the traditional method based on the silicon melting temperature (1414℃) as the failure boundary, the accuracy of the thermal failure temperature calculated by the method is improved by 33.45%. At the same time, compared with the traditional method which only considers the static device heat generation carrier concentration equal to the background doping concentration (T=1000K), the accuracy is improved by 5.9%. This improvement makes the method more accurate in characterizing the thermal failure characteristics of the device, thereby more accurately evaluating the reliability of the device.

[0120] The energy threshold-based prediction method provided by the application is used to more accurately predict the thermal failure temperature of SCR ESD protection devices. Unlike traditional methods that rely on silicon melting temperature or static equilibrium concentration as boundary conditions, this method breaks through these limitations from the perspective of energy threshold. The thermal failure temperature of the device can be more accurately predicted, thereby improving the accuracy of the reliability evaluation of the device. The boundary conditions of two traditional thermal failure analysis methods are: one is that when the peak temperature of the device reaches the melting temperature of silicon (about 1414℃), the device is considered to fail; in fact, the device often fails due to thermal runaway far below the material melting temperature, and this method underestimates the risk of device failure. Two is to define the peak temperature of the device when the thermal generation carrier concentration of the device reaches the background doping concentration level as the thermal failure temperature of the device. This method only defines the thermal failure temperature of the device based on the static equilibrium concentration, and does not fully consider the dynamic changes of the thermal generation carrier and the actual bearing capacity of the device, resulting in deviation of the results. The application is used to more accurately predict the thermal failure temperature of SCR ESD protection devices. Unlike traditional methods that rely on silicon melting temperature or static equilibrium concentration as boundary conditions, this method breaks through these limitations from the perspective of energy threshold. The thermal failure temperature of the device can be more accurately predicted, thereby improving the accuracy of the reliability evaluation of the device.

Claims

1. A method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold, characterized in that: Specifically, the steps include the following: Step 1, determine the thermal failure judgment condition of the SCR ESD protection device; in Step 1, the thermal failure judgment condition of the SCR ESD protection device is: after the thermally generated carrier concentration in the thermal concentration region of the SCR ESD protection device is equal to the background doping concentration of the SCR ESD protection device, the actual energy that the device withstands is greater than or equal to the failure energy threshold of the device. Step 2: Calculate the estimated failure temperature T of the SCR ESD protection device based on the thermal failure criteria determined in Step 1. c The predicted failure temperature T was obtained through Sentaurus simulation. c The corresponding TLP current pulse amplitude is then defined as the estimated failure current I. f ; Step 3, based on the estimated failure temperature T obtained in Step 2 c Calculate the failure energy threshold E of the SCR ESD protection device. F ; Step 4: Calculate the actual energy E that the SCR ESD protection device can withstand; Step 5: Based on Step 3, obtain the failure energy threshold E of the SCR ESD protection device. F The failure determination is based on the actual energy E that the SCR ESD protection device can withstand, obtained in step 4.

2. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 1, characterized in that: The specific process of step 2 is as follows: Based on the thermal failure criteria for the SCR ESD protection device determined in step 1, let the thermally generated carrier concentration n in the thermal concentration region of the SCR ESD protection device be... d Equal to the background doping concentration of the SCR ESD protection device, and the thermally generated carrier concentration n of the SCR ESD protection device. d Compared with the estimated failure temperature T c The relation satisfies equation (1): （1） Because n d Given this, the estimated failure temperature T of the SCR ESD protection device can be obtained using formula (1). c The predicted failure temperature T was obtained in the Sentaurus simulation. c The corresponding TLP current pulse amplitude is then defined as the estimated failure current I. f .

3. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 2, characterized in that: The specific process of step 3 is as follows: When the applied TLP pulse width t is 100ns to 20ns Within the range, the failure power P of the SCR ESD protection device f The relationship between t and t satisfies equation (2): （2） Where A is the area of ​​the heat concentration region of the SCR ESD protection device, K is the thermal conductivity of the SCR ESD protection device material, ρ is the density of the SCR ESD protection device material, and C is the thermal conductivity of the SCR ESD protection device material. p T0 represents the specific heat capacity of the SCR ESD protection device material, and T0 represents the ambient temperature. Failure power P of SCR ESD protection device f Integrating over t yields the failure energy threshold E of the SCR ESD protection device. F The expression for is shown in equation (3): （3） Where t is the TLP pulse width.

4. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 3, characterized in that: The specific process of step 4 is as follows: To analyze the thermal runaway of SCR ESD protection devices, a rectangular black box heat source model is used. It is assumed that all the power of the SCR ESD protection device is concentrated in the rectangular black box heat source, and the peak temperature T of the SCR ESD protection device is... max Represented as: （4） in, For the temperature rise, With power P t The relationship satisfies the following piecewise function: （5） （6） （7） （8） Where D is the thermal diffusivity of the SCR ESD protection device material, ρ is the density of the SCR ESD protection device material, and t a t b t c These are three time constants, defined as follows: （9） （10） （11） （12） Where a, b, and c are the length, width, and height of the rectangular black box heat source, respectively; Equations (5)-(8) reflect the actual power borne by the heat concentration area of ​​the SCR ESD protection device at different times. The power P in equations (5)-(8) is... t Integrating over time, we obtain the actual energy E that the SCR ESD protection device withstands, as shown in the following expression: （13） Where t is the TLP pulse width.

5. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 4, characterized in that: The specific process of step 5 is as follows: Comparison with the estimated failure current I f Under these conditions, the actual energy E that the SCR ESD protection device withstands and the failure energy threshold E F The size of the SCR ESD protection device is used to determine whether it has failed, based on the comparison results.

6. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 5, characterized in that: In step 5, there are three possible comparison results: 1) If the estimated failure current I f Under these conditions, the actual energy E that the SCR ESD protection device withstands is equal to the failure energy threshold E of the SCR ESD protection device. F If the SCR ESD protection device fails at this point, the estimated failure temperature T of the SCR ESD protection device at this time is determined. c That is, the actual temperature at which thermal failure occurs, T; 2) If the estimated failure current I f Under these conditions, the actual energy E that the SCR ESD protection device withstands is lower than the failure energy threshold E of the SCR ESD protection device. F If so, it is determined that the SCR ESD protection device has not failed at this time; 3) If the estimated failure current I f Under these conditions, the actual energy E that the SCR ESD protection device withstands exceeds the failure energy threshold E of the SCR ESD protection device. F If so, it is determined that the SCR ESD protection device has failed.

7. The method for predicting the thermal failure temperature of SCR ESD protection devices based on energy threshold according to claim 6, characterized in that: In step 5, when comparison result 2) occurs, the TLP current pulse amplitude is increased. As the current pulse amplitude increases, the peak temperature of the SCR ESD protection device will also change, and the actual power it carries at the same time will also change. Therefore, it is necessary to recalculate the actual energy E that the device bears and compare it with the failure energy threshold E. F Compare the results until the SCRESD protection device fails. When comparison result 3) occurs, reducing the TLP current pulse amplitude will change the peak temperature of the device, and the actual power carried at the same time will also change. Therefore, it is necessary to recalculate the actual energy E that the device bears and compare it with the failure energy threshold E. F The comparison was conducted until the SCR ESD protection device did not fail. By processing comparison results 2) and 3), the amplitude range of TLP current pulses for SCR ESD protection devices that have failed and those that have not failed is determined; Within the TLP current pulse amplitude range between the failure and non-failure of the SCR ESD protection device, a bisection method is used to gradually narrow this range. The processing of comparison results 2) and 3) is repeated within the narrowed range until the actual energy E and the failure energy threshold E are equal. F The error between them reached the expected accuracy, and finally the failure current pulse amplitude I when the SCR ESD protection device thermally failed was obtained; Using Sentaurus software, the temperature amplitude T of the SCR ESD protection device is obtained when the amplitude of the applied TLP current pulse reaches the amplitude of the failure current pulse I. The peak temperature T of the SCR ESD protection device at this time is the actual temperature at which the SCR ESD protection device experiences thermal failure.

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