Test method, test circuit, controller, and semiconductor memory

Abstract

The present application provides a test method, a test circuit, a controller, and a semiconductor memory. A positive bias voltage is applied to the gate of a transistor at a preset temperature to control the mobile ionic charges in the gate oxide layer of the transistor to be away from the interface between the gate and the gate oxide layer of the transistor, and a first AC impedance spectrum of the transistor is tested when a disturbance signal is applied to the gate. A negative bias voltage is applied to the gate of the transistor at a preset temperature to control the mobile ionic charges in the gate oxide layer to move to the interface between the gate and the gate oxide layer, and a second AC impedance spectrum of the transistor is tested when a disturbance signal is applied to the gate. Compared with the equivalent circuit of the transistor under the positive bias voltage, the equivalent circuit of the transistor under the negative bias voltage has an additional series circuit of a capacitor for the mobile ionic charge and a resistor for the mobile ionic charge. Therefore, the difference between the second AC impedance spectrum and the first AC impedance spectrum lies in the influence of the mobile ionic charge, so that the characteristic frequency of the mobile ionic charge can be obtained.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a testing method, a testing circuit, a controller, and a semiconductor memory. Background Art

[0002] Mobile ionic charges exist in the gate oxide layer, mainly alkali metal ions such as Na and K, which carry positive charges. They can migrate in the gate oxide layer under certain temperature and bias, causing unstable threshold voltage and affecting device reliability. Therefore, it is particularly important to characterize various parameters of mobile ionic charges.

[0003] Since the characteristic frequency of the mobile ion charge reflects the response speed of the mobile ion charge to the excitation signal, the characteristic frequency of the mobile ion charge is currently mainly used as a reference to characterize various parameters of the mobile ion charge.

[0004] Therefore, how to determine the characteristic frequency of mobile ionic charges is a more important issue at present. Summary of the Invention

[0005] The present application provides a test method, a test circuit, a controller and a semiconductor memory for determining the characteristic frequency of mobile ion charges.

[0006] In a first aspect, the present application provides a testing method, comprising:

[0007] applying a positive bias voltage to a gate of a transistor at a preset temperature to control mobile ionic charges in a gate oxide layer of the transistor to be away from an interface between the gate of the transistor and the gate oxide layer, applying a disturbance signal to the gate, and measuring a first AC impedance spectrum of the transistor;

[0008] applying a negative bias voltage to the gate at the preset temperature to control the movable ionic charges to move to the interface between the gate and the gate oxide layer, applying the disturbance signal to the gate, and testing a second AC impedance spectrum of the transistor;

[0009] The characteristic frequency of the mobile ion charge is obtained according to the first AC impedance spectrum and the second AC impedance spectrum.

[0010] Optionally, obtaining the characteristic frequency of the mobile ion charge according to the first AC impedance spectrum and the second AC impedance spectrum specifically includes:

[0011] Comparing the first AC impedance spectrum with the second AC impedance spectrum to obtain an additional extreme point of argument or response arc in the second AC impedance spectrum relative to the first AC impedance spectrum;

[0012] The disturbance frequency corresponding to the extreme value point of the argument or the disturbance frequency corresponding to the maximum value of the imaginary part of the response arc is used as the characteristic frequency of the movable ion charge.

[0013] Optionally, applying a positive bias voltage to the gate of the transistor at the preset temperature specifically includes:

[0014] Acquiring a temperature of the movable ion charge movement and a semiconductor eigenstate temperature of the substrate of the transistor at a target doping concentration;

[0015] Selecting the highest temperature between the temperature at which the movable ion charges move and the semiconductor eigenstate temperature as the preset temperature;

[0016] A positive bias voltage is applied to the gate of the transistor at the preset temperature.

[0017] Optionally, applying a positive bias voltage to the gate of the transistor at the preset temperature specifically includes:

[0018] applying a positive bias voltage to the gate of the transistor for a preset time at a preset temperature;

[0019] The applying a negative bias voltage to the gate at the preset temperature specifically includes:

[0020] A negative bias voltage is applied to the gate at the preset temperature for the preset time.

[0021] Optionally, applying a disturbance signal to the gate specifically includes:

[0022] A disturbance voltage is applied to the gate.

[0023] Optionally, the highest frequency and the lowest frequency of the first AC impedance spectrum only reflect ohmic impedance.

[0024] Optionally, the mobile ionic charges respond to the lowest frequency of the second AC impedance spectrum.

[0025] In a second aspect, the present application provides a test circuit, comprising:

[0026] A test module, a first equivalent circuit and a second equivalent circuit, wherein the test module is connected to the first equivalent circuit and the second equivalent circuit;

[0027] The first equivalent circuit is equivalent to an equivalent circuit of a metal oxide semiconductor composed of the gate, gate oxide layer and substrate of the transistor when a positive bias voltage is applied to the gate of the transistor at a preset temperature;

[0028] The second equivalent circuit is equivalent to an equivalent circuit of the metal oxide semiconductor when a negative bias voltage is applied to the gate of the transistor at the preset temperature;

[0029] The testing module is used to test a first AC impedance spectrum of the first equivalent circuit under a disturbance signal and a second AC impedance spectrum of the second equivalent circuit under the disturbance signal, and obtain a characteristic frequency of the mobile ionic charge in the gate oxide layer according to the first AC impedance spectrum and the second AC impedance spectrum.

[0030] Optionally, the first equivalent circuit includes:

[0031] a first capacitor module and a first equivalent resistor, wherein a first end of the first capacitor module is connected to a first end of the first equivalent resistor, and a second end of the first capacitor module is connected to a second end of the first equivalent resistor;

[0032] The first capacitor module is equivalent to the capacitance of the metal oxide semiconductor when a positive bias voltage is applied to the gate at a preset temperature;

[0033] The first equivalent resistance is equivalent to the resistance of the gate oxide layer.

[0034] Optionally, the first capacitor module includes a first equivalent capacitor and a second equivalent capacitor;

[0035] The first end of the first equivalent capacitor serves as the first end of the first capacitor module and is connected to the first end of the first equivalent resistor. The second end of the first equivalent capacitor is connected to the first end of the second equivalent capacitor. The second end of the second equivalent capacitor serves as the second end of the first capacitor module and is connected to the second end of the second equivalent resistor.

[0036] The first equivalent capacitance is equivalent to the capacitance of the gate oxide layer when a positive bias voltage is applied to the gate at a preset temperature;

[0037] The second equivalent capacitance is equivalent to the depletion layer capacitance of the metal oxide semiconductor when a positive bias voltage is applied to the gate at the preset temperature.

[0038] Optionally, the second equivalent circuit includes: a third equivalent circuit and a fourth equivalent circuit;

[0039] The first end of the third equivalent circuit is connected to the first end of the fourth equivalent circuit, and the second end of the third equivalent circuit is connected to the second end of the fourth equivalent circuit;

[0040] The third equivalent circuit is equivalent to an equivalent circuit of the mobile ionic charges in the gate oxide layer when a negative bias voltage is applied to the gate at a preset temperature;

[0041] The fourth equivalent circuit is equivalent to the equivalent circuit of the metal oxide semiconductor when a negative bias voltage is applied to the gate of the transistor at a preset temperature.

[0042] Optionally, the third equivalent circuit includes: a third equivalent capacitor and a second equivalent resistor;

[0043] The first end of the third equivalent capacitor serves as the first end of the third equivalent circuit, the second end of the third equivalent capacitor is connected to the first end of the second equivalent resistor, and the second end of the second equivalent resistor serves as the second end of the third equivalent circuit;

[0044] The third equivalent capacitance is equivalent to the capacitance of the mobile ionic charges in the gate oxide layer;

[0045] The second equivalent resistance is equivalent to the resistance of the movable ionic charges.

[0046] Optionally, the fourth equivalent circuit includes: a fourth equivalent capacitor and a third equivalent resistor;

[0047] The first end of the fourth equivalent capacitor is connected to the first end of the third equivalent resistor to serve as the first end of the fourth equivalent circuit, and the second end of the fourth equivalent capacitor is connected to the second end of the third equivalent resistor to serve as the second end of the fourth equivalent circuit;

[0048] The fourth equivalent capacitance is equivalent to the capacitance of the gate oxide layer when a negative bias voltage is applied to the gate of the transistor at a preset temperature;

[0049] The third equivalent resistance is equivalent to the resistance of the gate oxide layer.

[0050] In a third aspect, the present application provides a controller for implementing the above-mentioned testing method.

[0051] In a fourth aspect, the present application provides a semiconductor memory comprising the above-mentioned test circuit.

[0052] The test method provided by the present application applies a positive bias voltage to the gate of a transistor at a preset temperature, controls the mobile ionic charge in the gate oxide layer of the transistor to move away from the interface between the gate and the gate oxide layer of the transistor, and moves to the interface between the substrate and the gate oxide layer, and tests the first AC impedance spectrum of the transistor when a disturbance signal is applied to the gate. And applies a negative bias voltage to the gate of the transistor at a preset temperature, controls the mobile ionic charge in the gate oxide layer to move to the interface between the gate and the gate oxide layer, and tests the second AC impedance spectrum of the transistor when a disturbance signal is applied to the gate. Since the semiconductor approaches the intrinsic state at the preset temperature, the depletion layer capacitance approaches infinity, resulting in a short circuit of the depletion layer capacitance, so that the capacitance characteristic of the metal oxide semiconductor composed of the gate, gate oxide layer and substrate of the transistor is only manifested as the gate oxide capacitance. Then, under the positive bias voltage, the equivalent circuit of the metal oxide semiconductor is a series circuit of the gate oxide capacitance and the gate oxide resistance. Under a negative bias voltage, the equivalent circuit of a metal oxide semiconductor is equivalent to a parallel circuit of a mobile ion charge circuit and a gate oxide circuit. The mobile ion charge circuit is a series circuit of the mobile ion charge capacitor and the mobile ion charge resistor, and the gate oxide circuit is a parallel circuit of the gate oxide capacitor and the gate oxide resistor. Therefore, compared to the equivalent circuit of a transistor under a positive bias voltage, the equivalent circuit of a transistor under a negative bias voltage has an additional mobile ion charge circuit, that is, an additional series circuit of the mobile ion charge capacitor and the mobile ion charge resistor. Therefore, the difference between the second AC impedance spectrum tested under a disturbance signal and the first AC impedance spectrum tested under a disturbance signal is the influence of the mobile ion charge. Therefore, the characteristic frequency of the mobile ion charge can be obtained based on the second AC impedance spectrum of the transistor under a negative bias voltage and the first AC impedance spectrum of the transistor under a positive bias voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 A flowchart of a testing method provided in one embodiment of the present application;

[0055] Figure 2 An interface diagram of a transistor provided in one embodiment of the present application;

[0056] Figure 3 An equivalent capacitance diagram of a metal oxide semiconductor of a transistor provided in one embodiment of the present application;

[0057] Figure 4An equivalent circuit diagram of a metal oxide semiconductor of a transistor provided in one embodiment of the present application;

[0058] Figure 5 An interface diagram of another transistor provided in one embodiment of the present application;

[0059] Figure 6 An equivalent circuit diagram of a metal oxide semiconductor of another transistor provided in an embodiment of the present application;

[0060] Figure 7 A circuit diagram of a test circuit provided in one embodiment of the present application. DETAILED DESCRIPTION

[0061] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0062] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered merely as exemplary, and the true scope and spirit of the present application are indicated by the claims above.

[0063] During the manufacturing process of semiconductor integrated circuits, some mobile ionic charges are inevitably mixed in. Mobile ionic charges exist in the gate oxide layer, mainly alkali metal ions such as Na and K. They can migrate in the gate oxide layer under certain temperature and bias, causing threshold voltage instability and affecting device reliability. Therefore, it is particularly important to characterize various parameters of mobile ionic charges.

[0064] Because the characteristic frequency of mobile ion charge reflects its response speed to an excitation signal, it is currently used as a reference to characterize various parameters of mobile ion charge. For example, TVS (Transient Voltage Suppressor) scanning speed is selected based on the characteristic frequency of mobile ion charge, and mobile ion density is measured based on the characteristic frequency of mobile ion charge. However, the characteristic frequency of mobile ion charge cannot be effectively obtained at present.

[0065] To this end, the present application provides a testing method, wherein a positive bias voltage is applied to the gate of a transistor at a preset temperature, and the mobile ionic charge in the gate oxide layer of the transistor is controlled to move away from the interface between the gate and the gate oxide layer of the transistor and move to the interface between the substrate and the gate oxide layer. Since the semiconductor approaches the intrinsic state at the preset temperature, the depletion layer capacitance approaches infinity, resulting in a short circuit of the depletion layer capacitance, so that the capacitance characteristic of the metal oxide semiconductor composed of the gate, gate oxide layer, and substrate of the transistor is only manifested as the gate oxide capacitance, and the equivalent circuit of the metal oxide semiconductor is a series circuit of the gate oxide capacitance and the gate oxide resistance. And at the preset temperature, a negative bias voltage is applied to the gate of the transistor to control the mobile ionic charge in the gate oxide layer to move to the interface between the gate and the gate oxide layer, and the equivalent circuit of the metal oxide semiconductor is equivalent to a parallel circuit of the mobile ionic charge circuit and the gate oxide circuit, the mobile ionic charge circuit is a series circuit of the capacitance of the mobile ionic charge and the resistance of the mobile ionic charge, and the gate oxide circuit is a parallel circuit of the gate oxide capacitance and the gate oxide resistance. Therefore, compared to the equivalent circuit of a transistor under positive bias voltage, the equivalent circuit of a transistor under negative bias voltage includes an additional mobile ion charge circuit, that is, an additional series circuit of a mobile ion charge capacitor and a mobile ion charge resistor. Therefore, the difference between the second AC impedance spectrum measured under a disturbance signal and the first AC impedance spectrum measured under a disturbance signal is the influence of the mobile ion charge. Therefore, the characteristic frequency of the mobile ion charge can be obtained based on the second AC impedance spectrum of the transistor under negative bias voltage and the first AC impedance spectrum of the transistor under positive bias voltage.

[0066] Figure 1 A flow chart of a test method provided in an embodiment of the present application. Figure 1 As shown, the test method provided in the embodiment of the present application includes:

[0067] S101, applying a positive bias voltage to the gate of the transistor at a preset temperature, controlling the mobile ionic charges in the gate oxide layer of the transistor to be away from the interface between the gate of the transistor and the gate oxide layer, applying a disturbance signal to the gate, and testing a first AC impedance spectrum of the transistor.

[0068] refer to Figure 2 As shown, the transistor includes a substrate 103, a gate oxide layer 102, and a gate 101 stacked in sequence. When a positive bias voltage is applied to the gate 101 of the transistor, mobile ionic charges in the gate oxide layer 102 of the transistor migrate toward the interface between the substrate 103 and the gate oxide layer 102 under the action of the positive bias voltage and accumulate at the interface between the substrate 103 and the gate oxide layer 102. It should be noted that the main source of mobile ionic charges is contamination during the process.

[0069] refer to Figure 3As shown, when mobile ionic charges accumulate at the interface between the substrate and gate oxide layer of a transistor, the equivalent capacitance of the metal oxide semiconductor composed of the gate-gate oxide layer-substrate includes the gate oxide layer capacitance Coxide and the depletion layer capacitance Cs, and the gate oxide layer capacitance Coxide is connected to the depletion layer capacitance Cs. Since the semiconductor tends to the intrinsic state at high temperature, the depletion layer capacitance Cs tends to infinity, and the capacitive reactance of the depletion layer capacitance Cs tends to 0, causing the depletion layer capacitance Cs to short-circuit. Moreover, since the mobile ionic charges accumulate at the interface between the substrate and gate oxide layer of the transistor, the mobile ionic charges can all be treated as interface traps. Since the interface state capacitance Cit is connected in parallel with the depletion layer capacitance Cs, the capacitive reactance of the depletion layer capacitance approaches 0, and the capacitance characteristic of the metal oxide semiconductor is only manifested as the gate oxide layer capacitance Coxide.

[0070] It should be noted that the metal oxide semiconductor of a transistor also includes interface trapped charge, fixed oxide charge, and oxide trapped charge. Interface trapped charge is generated by the rapid exchange of charge and holes between interface states and the conduction band or valence band of silicon. Interface states primarily originate from excess trivalent silicon, broken Si-H bonds, excess oxygen, impurities, and defects. Located at the interface between the gate oxide and the substrate, they serve as centers for the generation and recombination of minority carriers, rapidly exchanging charge and holes with the conduction band or valence band of silicon. Fixed oxide charge is caused by defects in the oxide layer, primarily excess silicon ions or oxygen vacancies. These charges remain fixed under bias-temperature stress and are distributed within approximately 25 angstroms of the interface between the gate oxide and the substrate. Oxide-trapped charge refers to the hole and electron trap states present within the gate oxide layer. These trap holes and electrons entering the gate oxide, imparting a positive and negative charge, respectively. Holes and electrons entering the gate oxide can be generated by ionizing radiation, avalanche injection, or excitation by ultraviolet photons with energies greater than the SiO2 bandgap. To facilitate comparison of the equivalent circuits of transistors under positive and negative bias voltages and to obtain the characteristic frequencies of mobile ionic charge, the effects of interface trapped charge, fixed oxide charge, and oxide-trapped charge can be neglected.

[0071] refer to Figure 4 As shown, Figure 4 The equivalent circuit diagram of the metal oxide semiconductor composed of the gate-gate oxide layer-substrate of the transistor when a positive bias voltage is applied is shown. The equivalent circuit of the metal oxide semiconductor when a bias voltage is applied includes the gate oxide layer capacitance Coxide and the gate oxide layer resistance Roxide. The gate oxide layer capacitance Coxide is connected to the gate oxide layer resistance Roxide. The gate oxide layer resistance Roxide is used to indicate the potential barrier formed by the gate oxide layer. The current ΔI flowing through the metal oxide semiconductor is exIncluding the gate oxide layer displacement current ΔI c and the gate oxide leakage current ΔI e , the gate oxide leakage current ΔI e Leakage current generated by crossing the potential barrier formed by the gate oxide layer.

[0072] In some embodiments, the temperature at which the mobile ion charges move, that is, the minimum temperature that promotes the movement of the mobile ion charges, can be obtained. The minimum temperature that promotes the movement of the mobile ion charges is, for example, 100°C. The semiconductor eigenstate temperature of the transistor substrate at a target doping concentration can also be obtained. The target doping concentration is the current doping concentration of the transistor substrate. Then, the temperature at which the mobile ion charges move is compared with the semiconductor eigenstate temperature of the substrate at the target doping concentration, and the highest temperature between the temperature of the mobile ion charges and the semiconductor eigenstate temperature is selected as the preset temperature, thereby ensuring that each ion charge in the mobile ion charge moves to the interface between the gate oxide layer and the substrate, and at the same time, the depletion layer capacitance Cs tends to infinity.

[0073] In some embodiments, a positive bias voltage can be applied to the gate of the transistor for a preset time at a preset temperature, so that the mobile ionic charge is accumulated as completely as possible at the interface between the substrate and the gate oxide layer of the transistor. The positive bias voltage is, for example, less than the breakdown voltage of the transistor. The breakdown voltage refers to the drain-source voltage when the current flowing through the drain-source is a specific value when the gate is grounded. It is the highest instantaneous voltage value that can be continuously applied to the drain-source before the transistor breaks down. The breakdown voltage is a key parameter for measuring the voltage resistance of the transistor. The larger the breakdown voltage, the better the voltage resistance performance of the transistor. The preset time can be, for example, 8 to 15 minutes, such as 10 minutes.

[0074] Then, based on the positive bias voltage, a disturbance signal is applied to the gate of the transistor, and a first AC impedance spectrum of the transistor is measured. The disturbance signal is an excitation signal applied to the gate of the transistor to measure the first AC impedance spectrum of the transistor under the positive bias voltage.

[0075] As an implementation, the perturbation signal, for example, a perturbation voltage, is applied to the gate of the transistor at a fixed frequency, resulting in a small sinusoidal voltage excitation signal. This generates an impedance at this fixed frequency. By varying the frequency, a series of corresponding impedances can be obtained, thereby obtaining a first AC impedance spectrum of the transistor under a positive bias voltage. The perturbation voltage can be, for example, 10mV to 30mV, for example, 20mV.

[0076] In some embodiments, both the highest frequency and the lowest frequency of the first AC impedance spectrum may reflect only ohmic impedance, and the frequency range of the first AC impedance spectrum may be, for example, 10 GHZ to 10 MHZ.

[0077] S102 , applying a negative bias voltage to the gate at a preset temperature to control the movement of mobile ionic charges to the interface between the gate and the gate oxide layer, applying a disturbance signal to the gate, and testing a second AC impedance spectrum of the transistor.

[0078] refer to Figure 5 As shown, when a negative bias voltage is applied to the gate 101 of the transistor, the mobile ionic charges in the gate oxide layer 102 of the transistor migrate toward the interface between the gate 101 and the gate oxide layer 102 of the transistor under the action of the negative bias voltage and accumulate at the interface between the gate 101 and the gate oxide layer 102.

[0079] When a negative bias voltage is applied to the gate, a large number of holes in the semiconductor layer are attracted to the semiconductor surface. Due to the blocking effect of the insulating layer, the holes in the semiconductor layer accumulate on the semiconductor surface. At this time, the metal oxide semiconductor is in an accumulation state (Accumulation), and the capacitance of the metal oxide semiconductor is equivalent to the gate oxide layer capacitance Coxide. At the same time, under the action of the negative bias voltage, the mobile ionic charges in the gate oxide layer move toward the interface between the gate and the gate oxide layer and accumulate at the interface between the gate and the gate oxide layer. Because the mobile ionic charges accumulate at the interface between the gate and the gate oxide layer and induce charges of opposite sign on the gate surface, that is, negative charges are induced on the gate surface, the mobile ionic charges and the induced charges of the gate constitute a mobile ionic charge capacitor. The insulating layer constitutes a mobile ionic charge resistance as a potential barrier to the movement of the mobile ionic charges. The mobile ionic charge capacitor and the mobile ionic charge resistance are in a series relationship.

[0080] Therefore, reference Figure 6 As shown, Figure 6 The equivalent circuit diagram of the metal oxide semiconductor structure composed of the gate-gate oxide layer-substrate of the transistor when a negative bias voltage is applied, the equivalent circuit of the metal oxide semiconductor composed of the gate-gate oxide layer-substrate includes a gate oxide layer equivalent circuit 202 and a movable ion charge equivalent circuit 201, the gate oxide layer equivalent circuit 202 includes a gate oxide layer capacitor Coxide and a gate oxide layer resistor Roxide, the movable ion charge equivalent circuit 201 includes a movable ion charge capacitor Cion and a movable ion charge resistor Rion, the gate oxide layer equivalent circuit 202 and the movable ion charge equivalent circuit 201 are connected in parallel, the gate oxide layer capacitor Roxide and the gate oxide layer resistor Roxide are connected in parallel, and the movable ion charge capacitor Cion and the movable ion charge resistor Rion are connected in series. Then the current ΔI flowing through the metal oxide semiconductor ex Including the gate oxide layer displacement current ΔI c and the gate oxide leakage current ΔI e , and the current ΔI flowing through the mobile ion charge capacitance Cion and the mobile ion charge resistance Rion p .

[0081] In some embodiments, a negative bias voltage may be applied to the gate of the transistor at a preset temperature and for a preset time, so that the mobile ionic charges are accumulated as completely as possible at the interface between the gate of the transistor and the gate oxide layer.

[0082] Then, based on the negative bias voltage, a disturbance signal is applied to the gate of the transistor, and a second AC impedance spectrum of the transistor is measured. For example, based on the negative bias voltage, a disturbance voltage can be applied to the gate of the transistor to obtain a second AC impedance spectrum of the transistor under the negative bias voltage. The lowest frequency of the second AC impedance spectrum needs to ensure a response of mobile ion charges in order to obtain the impedance corresponding to the characteristic frequency of the mobile ion charges.

[0083] S103 , obtaining characteristic frequencies of mobile ion charges according to the first AC impedance spectrum and the second AC impedance spectrum.

[0084] AC impedance refers to the combined resistance and reactance characteristics of an electronic component in response to an AC excitation signal. When measuring impedance, if the frequency of the AC excitation signal is continuously varied, a series of impedance data that varies with frequency can be measured. This collection of impedance data is called an AC impedance spectrum.

[0085] Since the equivalent circuit of the metal oxide semiconductor composed of the gate, gate oxide layer and substrate of the transistor under negative bias voltage has an additional mobile ion charge equivalent circuit compared to the equivalent circuit of the metal oxide semiconductor under positive bias voltage, that is, an additional mobile ion charge capacitor and mobile ion charge resistor, the difference between the second AC impedance spectrum and the first AC impedance spectrum lies in the influence of the mobile ion charge.

[0086] AC impedance spectra include Nyquist plots and Bode plots. A Nyquist plot, also called a complex plane plot, represents the real and imaginary parts of impedance, with the real part on the horizontal axis and the negative of the imaginary part on the vertical axis. The real part is called resistance, and the imaginary part is called reactance. Reactance is the resistance to AC current caused by capacitors and inductors in a circuit. Therefore, the imaginary part of the impedance in the first and second AC impedance spectra is the capacitive reactance of the capacitor, and each point in the plot corresponds to a different frequency. A Bode plot consists of two curves: the horizontal axis is the logarithm of the frequency, the vertical axis of one curve is the logarithm of the impedance modulus, and the vertical axis of the other curve is the phase angle of the impedance, which is also known as the angle of argument.

[0087] Therefore, the first AC impedance spectrum and the second AC impedance spectrum can be compared to obtain the extra extreme points of the argument or the response arc in the first AC impedance spectrum, and the disturbance frequency corresponding to the extreme points of the argument or the disturbance frequency corresponding to the maximum value of the imaginary part of the response arc can be used as the characteristic frequency of the mobile ion charge. The disturbance frequency here is the response frequency of the mobile ion charge, that is, the characteristic frequency of the mobile ion charge, so that the characteristic frequency of the mobile ion charge can be obtained based on the first AC impedance spectrum and the second AC impedance spectrum.

[0088] The test method provided in the present application is described in detail above. The difference between the equivalent circuit of the metal oxide semiconductor composed of the substrate-gate oxide layer and the substrate of the transistor under a positive bias voltage and the equivalent circuit under a negative bias voltage is only the influence of the mobile ion charge. Therefore, the characteristic frequency of the mobile ion charge can be obtained based on the difference between the first AC impedance spectrum and the second AC impedance spectrum of the transistor under a positive bias voltage.

[0089] Figure 7 A test circuit is provided in the embodiment of the present application, referring to Figure 7 As shown, the test circuit provided in the embodiment of the present application includes:

[0090] Testing module 303, first equivalent circuit 301, and second equivalent circuit 302, wherein testing module 303 is connected to first equivalent circuit 301 and second equivalent circuit 302. First equivalent circuit 301 is equivalent to the metal oxide semiconductor circuit consisting of the gate, gate oxide layer, and substrate of the transistor when a positive bias voltage is applied to the gate of the transistor at a preset temperature. Second equivalent circuit 302 is equivalent to the metal oxide semiconductor circuit consisting of the gate, gate oxide layer, and substrate of the transistor when a negative bias voltage is applied to the gate of the transistor at a preset temperature. Testing module 303 tests a first AC impedance spectrum of the first equivalent circuit 301 under a disturbance signal, and a second AC impedance spectrum of the second equivalent circuit 302 under a disturbance signal, and obtains the characteristic frequency of the mobile ionic charge in the gate oxide layer based on the first and second AC impedance spectra.

[0091] In some embodiments, the first equivalent circuit 301 includes a first capacitor module 311 and a first equivalent resistor R1. The first end of the first capacitor module 311 is connected to the first end of the first equivalent resistor R1, and the second end of the first capacitor module 311 is connected to the second end of the first equivalent resistor R1. The first capacitor module 311 is equivalent to the capacitance of the metal oxide semiconductor composed of the gate, gate oxide layer, and substrate of the transistor when a positive bias voltage is applied to the gate of the transistor at a preset temperature. The first equivalent resistor R1 is equivalent to the resistance of the gate oxide layer. The testing module 303 can test the first AC impedance spectrum of the first capacitor module 311 and the first equivalent resistor R1 under a disturbance signal as the first AC impedance spectrum of the first equivalent circuit 301.

[0092] The first capacitor module 311 includes a first equivalent capacitor C1 and a second equivalent capacitor C2. The first end of the first equivalent capacitor C1 serves as the first end of the first capacitor module 311, the second end of the first equivalent capacitor C1 is connected to the first end of the second equivalent capacitor C2, and the second end of the second equivalent capacitor C2 serves as the second end of the first capacitor module 311. The first end of the first equivalent resistor R1 is connected to the first end of the first equivalent capacitor C1, and the second end of the first equivalent resistor R1 is connected to the second end of the second equivalent capacitor C2. The first equivalent capacitor C1 is equivalent to the capacitance of the gate oxide layer when a positive bias voltage is applied to the gate of the transistor at a preset temperature. The second equivalent capacitor C2 is equivalent to the depletion layer capacitance of the metal oxide semiconductor composed of the gate, gate oxide layer, and substrate of the transistor when a positive bias voltage is applied to the gate of the transistor at a preset temperature. Since the depletion layer capacitance Cs of the metal oxide semiconductor tends to infinity at a preset temperature, the capacitive reactance of the depletion layer capacitance Cs tends to 0, and therefore the capacitive reactance of the second equivalent capacitance C2 tends to 0, the testing module 303 can test the first AC impedance spectrum of the first equivalent capacitance C1 and the first equivalent resistance R1 under the disturbance signal as the first AC impedance spectrum of the first equivalent circuit 301.

[0093] In some embodiments, the second equivalent circuit 302 includes a third equivalent circuit 321 and a fourth equivalent circuit 322. The first end of the third equivalent circuit 321 is connected to the first end of the fourth equivalent circuit 322, and the second end of the third equivalent circuit 321 is connected to the second end of the fourth equivalent circuit 322. The fourth equivalent circuit 322 is equivalent to the equivalent circuit of the metal oxide semiconductor composed of the gate, gate oxide layer, and substrate of the transistor when a negative bias voltage is applied to the gate of the transistor at a preset temperature. The third equivalent circuit 321 is equivalent to the equivalent circuit of the mobile ionic charges in the gate oxide layer of the transistor when a negative bias voltage is applied to the gate at a preset temperature. The testing module 303 can test the second AC impedance spectrum of the third equivalent circuit 321 and the fourth equivalent circuit 322 under the disturbance signal as the second AC impedance spectrum of the second equivalent resistor.

[0094] The third equivalent circuit 321 may include a third equivalent capacitor C3 and a second equivalent resistor R2. The first end of the third equivalent capacitor C3 serves as the first end of the third equivalent circuit 321, the second end of the third equivalent capacitor C3 is connected to the first end of the second equivalent resistor R2, and the second end of the second equivalent resistor R2 serves as the second end of the third equivalent circuit 321. The third equivalent capacitor C3 is equivalent to the capacitance of the mobile ionic charge in the gate oxide layer, and the second equivalent resistor R2 is equivalent to the resistance of the mobile ionic charge. The fourth equivalent circuit 322 may include a fourth equivalent capacitor C4 and a third equivalent resistor R3. The first end of the fourth equivalent capacitor C4 is connected to the first end of the third equivalent resistor R3, serving as the first end of the fourth equivalent circuit 322, and the second end of the fourth equivalent capacitor C4 is connected to the second end of the third equivalent resistor R3, serving as the second end of the fourth equivalent circuit 322. The fourth equivalent capacitor C4 is equivalent to the capacitance of the transistor's gate oxide layer when a negative bias voltage is applied to the transistor's gate at a preset temperature, and the third equivalent resistor R3 is equivalent to the resistance of the gate oxide layer.

[0095] Compared to the first equivalent circuit 301, the second equivalent circuit 302 has an additional third equivalent circuit 321, namely, an additional third equivalent capacitor C3 and a second equivalent resistor R2. Therefore, the second AC impedance spectrum of the second equivalent circuit 302 tested by the testing module 303 differs from the first AC impedance spectrum of the first equivalent circuit 301 in the influence of the capacitance and resistance of the mobile ionic charge. Furthermore, the AC impedance spectrum can reflect the relationship between the response frequency of capacitance and resistance and impedance. Therefore, the auxiliary angle or response arc corresponding to the mobile ionic charge can be obtained based on the first and second AC impedance spectra, and the characteristic frequency of the mobile ionic charge can be obtained based on the perturbation frequency corresponding to the extreme value of the auxiliary angle or the perturbation frequency corresponding to the maximum imaginary part of the response arc.

[0096] The embodiment of the present application also provides a controller for implementing the above-mentioned testing method.

[0097] An embodiment of the present application further provides a semiconductor memory including the above-mentioned test circuit.

[0098] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the aforementioned embodiments, those skilled in the art will appreciate that they may modify the technical solutions described in the aforementioned embodiments or replace some or all of the technical features therein with equivalents. However, such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the various embodiments of this application.

Claims

1. A testing method, characterized in that: The method comprises: applying a positive bias voltage to a gate of a transistor at a preset temperature to control mobile ionic charges in a gate oxide layer of the transistor to be away from an interface between the gate of the transistor and the gate oxide layer, applying a disturbance signal to the gate, and measuring a first AC impedance spectrum of the transistor; applying a negative bias voltage to the gate at the preset temperature to control the movable ionic charges to move to the interface between the gate and the gate oxide layer, applying the disturbance signal to the gate, and testing a second AC impedance spectrum of the transistor; The characteristic frequency of the mobile ion charge is obtained according to the first AC impedance spectrum and the second AC impedance spectrum.

2. The method according to claim 1, characterized in that The obtaining the characteristic frequency of the mobile ion charge according to the first AC impedance spectrum and the second AC impedance spectrum specifically includes: Comparing the first AC impedance spectrum with the second AC impedance spectrum to obtain an additional extreme point of argument or response arc in the second AC impedance spectrum relative to the first AC impedance spectrum; The disturbance frequency corresponding to the extreme value point of the argument or the disturbance frequency corresponding to the maximum value of the imaginary part of the response arc is used as the characteristic frequency of the movable ion charge.

3. The method according to claim 1, characterized in that Applying a positive bias voltage to the gate of the transistor at the preset temperature specifically includes: Acquiring a temperature of the movable ion charge movement and a semiconductor eigenstate temperature of the substrate of the transistor at a target doping concentration; Selecting the highest temperature between the temperature at which the movable ion charges move and the semiconductor eigenstate temperature as the preset temperature; A positive bias voltage is applied to the gate of the transistor at the preset temperature.

4. The method according to claim 1, wherein Applying a positive bias voltage to the gate of the transistor at the preset temperature specifically includes: applying a positive bias voltage to the gate of the transistor for a preset time at a preset temperature; The applying a negative bias voltage to the gate at the preset temperature specifically includes: A negative bias voltage is applied to the gate at the preset temperature for the preset time.

5. The method according to claim 1, wherein Applying a disturbance signal to the gate specifically includes: A disturbance voltage is applied to the gate.

6. The method according to any one of claims 1 to 5, characterized in that The highest frequency and the lowest frequency of the first AC impedance spectrum both reflect only ohmic impedance.

7. The method according to any one of claims 1 to 5, characterized in that The mobile ionic charges respond to the lowest frequency of the second AC impedance spectrum.

8. A test circuit, characterized in that: include: A test module, a first equivalent circuit and a second equivalent circuit, wherein the test module is connected to the first equivalent circuit and the second equivalent circuit; The first equivalent circuit is equivalent to an equivalent circuit of a metal oxide semiconductor composed of the gate, gate oxide layer and substrate of the transistor when a positive bias voltage is applied to the gate of the transistor at a preset temperature; The second equivalent circuit is equivalent to an equivalent circuit of the metal oxide semiconductor when a negative bias voltage is applied to the gate of the transistor at the preset temperature; The testing module is used to test a first AC impedance spectrum of the first equivalent circuit under a disturbance signal and a second AC impedance spectrum of the second equivalent circuit under the disturbance signal, and obtain a characteristic frequency of the mobile ionic charge in the gate oxide layer according to the first AC impedance spectrum and the second AC impedance spectrum.

9. The test circuit according to claim 8, characterized in that: The first equivalent circuit includes: a first capacitor module and a first equivalent resistor, wherein a first end of the first capacitor module is connected to a first end of the first equivalent resistor, and a second end of the first capacitor module is connected to a second end of the first equivalent resistor; The first capacitor module is equivalent to the capacitance of the metal oxide semiconductor when a positive bias voltage is applied to the gate at a preset temperature; The first equivalent resistance is equivalent to the resistance of the gate oxide layer.

10. The test circuit according to claim 9, characterized in that: The first capacitor module includes a first equivalent capacitor and a second equivalent capacitor; The first end of the first equivalent capacitor serves as the first end of the first capacitor module and is connected to the first end of the first equivalent resistor. The second end of the first equivalent capacitor is connected to the first end of the second equivalent capacitor. The second end of the second equivalent capacitor serves as the second end of the first capacitor module and is connected to the second end of the second equivalent resistor. The first equivalent capacitance is equivalent to the capacitance of the gate oxide layer when a positive bias voltage is applied to the gate at a preset temperature; The second equivalent capacitance is equivalent to the depletion layer capacitance of the metal oxide semiconductor when a positive bias voltage is applied to the gate at the preset temperature.

11. The test circuit according to claim 8, characterized in that: The second equivalent circuit includes: a third equivalent circuit and a fourth equivalent circuit; The first end of the third equivalent circuit is connected to the first end of the fourth equivalent circuit, and the second end of the third equivalent circuit is connected to the second end of the fourth equivalent circuit; The third equivalent circuit is equivalent to an equivalent circuit of the mobile ionic charges in the gate oxide layer when a negative bias voltage is applied to the gate at a preset temperature; The fourth equivalent circuit is equivalent to the equivalent circuit of the metal oxide semiconductor when a negative bias voltage is applied to the gate of the transistor at a preset temperature.

12. The test circuit according to claim 11, characterized in that: The third equivalent circuit includes: a third equivalent capacitor and a second equivalent resistor; The first end of the third equivalent capacitor serves as the first end of the third equivalent circuit, the second end of the third equivalent capacitor is connected to the first end of the second equivalent resistor, and the second end of the second equivalent resistor serves as the second end of the third equivalent circuit; The third equivalent capacitance is equivalent to the capacitance of the mobile ionic charges in the gate oxide layer; The second equivalent resistance is equivalent to the resistance of the movable ionic charges.

13. The test circuit according to claim 11, wherein: The fourth equivalent circuit includes: a fourth equivalent capacitor and a third equivalent resistor; The first end of the fourth equivalent capacitor is connected to the first end of the third equivalent resistor to serve as the first end of the fourth equivalent circuit, and the second end of the fourth equivalent capacitor is connected to the second end of the third equivalent resistor to serve as the second end of the fourth equivalent circuit; The fourth equivalent capacitance is equivalent to the capacitance of the gate oxide layer when a negative bias voltage is applied to the gate of the transistor at a preset temperature; The third equivalent resistance is equivalent to the resistance of the gate oxide layer.

14. A controller, characterized in that: Used to implement the testing method according to any one of claims 1 to 7.

15. A semiconductor memory, characterized in that: The test circuit comprises the test circuit according to any one of claims 8 to 13.

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