Method for characterizing fluctuation induced by single particle irradiation in a device and application thereof

Abstract

A method for characterizing a fluctuation induced by single particle irradiation in a device. A plurality of devices varying in size are tested respectively before and after irradiation to obtain threshold voltage distribution, such that a threshold voltage fluctuation induced by irradiation is obtained and used to correct a process fluctuation model, so as to correct a design margin of the devices working under the irradiation.

Claims

1. A method for characterizing a fluctuation induced by single particle irradiation in a device, comprising: 1) estimating a total radiation flux over a life cycle of a plurality of devices to be evaluated and a particle type according to an application requirement; wherein the plurality of devices to be evaluated vary in size; 2) testing the plurality of devices to be evaluated to plot a pre-irradiation transfer characteristic curve (I.sub.D-V.sub.G).sub.pre of the plurality of devices to be evaluated; 3) subjecting the plurality of devices to be evaluated to single particle irradiation; and testing the plurality of devices to be evaluated to obtain a post-irradiation transfer characteristic curve (I.sub.D-V.sub.G).sub.post of the plurality of devices to be evaluated; 4) extracting a threshold voltage V.sub.Tpre of each of the plurality of devices to be evaluated before irradiation; calculating a standard deviation σ.sub.ΔVT of a threshold voltage deviation of each of the plurality of devices to be evaluated before irradiation; extracting a threshold voltage V.sub.Tpost of each of the plurality of devices to be evaluated after irradiation; and calculating a standard deviation σ.sub.ΔVT of a threshold voltage deviation of each of the plurality of devices to be evaluated after irradiation; 5) plotting a Pelgrom diagram ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$ of a threshold voltage fluctuation of the plurality of devices to be evaluated before irradiation; and plotting a Pelgrom diagram ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$ of a threshold voltage fluctuation of the plurality of devices to be evaluated after irradiation, wherein W is an equivalent gate width of a corresponding device; and L is an equivalent gate length of the corresponding device; and 6) calculating a fluctuation σ.sub.SEE (WL) induced by irradiation in each of the plurality of devices to be evaluated according to the Pelgrom diagram of the threshold voltage fluctuation of the plurality of devices to be evaluated before irradiation and the Pelgrom diagram of the threshold voltage fluctuation of the plurality of devices to be evaluated after irradiation.

2. The method of claim 1, wherein the single particle irradiation is performed using a source selected from the group consisting of a heavy ion, a proton, a neutron, an electron, a pion, a muon, an alpha particle and a combination thereof.

3. The method of claim 1, wherein the number of the plurality of devices to be evaluated is greater than 30.

4. The method of claim 1, wherein a total radiation flux and a particle type of the single particle radiation in step (3) are determined by the total radiation flux over the life cycle and the particle type estimated in step (1).

5. The method of claim 1, wherein in step (4), the threshold voltage V.sub.Tpre and the threshold voltage V.sub.Tpost of each of the plurality of devices to be evaluated are extracted using a maximum transconductance change method or a constant current method.

6. A method for improving a reliability of a microelectronic device and a microelectronic circuit working under the irradiation, the method comprising: obtaining a fluctuation σ.sub.SEE (WL) induced by irradiation in a microelectronic device to be evaluated according to the method of claim 1; correcting a process fluctuation model of the microelectronic device to be evaluated using the obtained fluctuation σ.sub.SEE (WL); and obtaining a total fluctuation σ.sub.total of the microelectronic device to be evaluated as follows:
σ.sub.total=σ.sub.SEE+σ.sub.PV; wherein σ.sub.PV is an initial process fluctuation of the microelectronic device to be evaluated; and substituting the total fluctuation σ.sub.total into simulation to correct a design margin of the microelectronic device to be evaluated under the irradiation, so as to improve reliability of the microelectronic device to be evaluated.

7. The method of claim 6, wherein the simulation is performed using Monte Carlo simulation or Hspice simulation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart of correcting a design margin of a circuit under the irradiation using a method for characterizing a fluctuation induced by single particle irradiation according to an embodiment of this disclosure; and

(2) FIG. 2 is a Pelgrom diagram illustrating a threshold voltage fluctuation of the N-type metal oxide semiconductor (nMOS) before and after irradiation according to an embodiment of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

(3) This application provides a method for characterizing a fluctuation induced by single particle irradiation in a device, which is performed as follows. A plurality of devices varying in size are tested respectively before and after irradiation to obtain threshold voltage distribution, such that a threshold voltage fluctuation induced by single particle irradiation is obtained and used to correct a process fluctuation model, so as to correct a design margin of the devices working under the irradiation. This application will be described in detail below with reference to the accompanying drawings and embodiments.

Embodiment

(4) In this embodiment, a plurality of samples of the N-type metal oxide semiconductor (nMOS) to be evaluated that vary in size are selected. The single particle is heavy ion. FIG. 1 shows a flow chart of a test and experiment adopted in the method provided herein. The test and experiment are performed at a room temperature, and the specific steps are as follows.

(5) 1) The samples are tested to plot a pre-irradiation transfer characteristic curve of the samples.

(6) 2) The samples are subjected to heavy ion irradiation. The heavy ion is 260 MeV iodine ion, and a total radiation flux of the heavy ion is 1.39×10.sup.10 ions/cm.sup.2.

(7) 3) The samples are tested to obtain a post-irradiation transfer characteristic curve of the samples.

(8) 4) A threshold voltage of each of the samples before the heavy ion irradiation and a threshold voltage of each of the samples after the heavy ion irradiation are extracted using a constant current method.

(9) 5) A standard deviation σ.sub.ΔVT of a threshold voltage deviation of each of the samples before the heavy ion irradiation and a standard deviation σ.sub.ΔVT of a threshold voltage deviation of each of the samples after the heavy ion irradiation are calculated.

(10) 6) A Pelgrom diagram

(11) ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$
of a threshold voltage fluctuation of the samples before the heavy ion irradiation and a Pelgrom diagram

(12) ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$
of a threshold voltage fluctuation of the samples after the heavy ion irradiation are plotted followed by linear fitting. The Pelgrom diagrams are shown in FIG. 2, and A.sub.ΔVT marked in FIG. 2 is a slope obtained by linear fitting.

(13) 7) A fluctuation σ.sub.SEE induced by the heavy ion irradiation in the N-type metal oxide semiconductor to be evaluated is calculated as follows:

(14) ${\sigma }_{\mathrm{SEE}}={\sigma }_{\mathrm{post}}-{\sigma }_{\mathrm{pre}}=\frac{3.2}{\sqrt{WL}}-\frac{2.9}{\sqrt{WL}}=\frac{0.3}{\sqrt{WL}}\mathrm{mV};$

(15) where σ.sub.post is a function between the threshold voltage deviation of the samples after the heavy ion irradiation and the size of the samples; σ.sub.pre is function between the threshold voltage deviation of the samples before the heavy ion irradiation and the size of the samples; 3.2 is a slope obtained by subjecting the Pelgrom diagram

(16) ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$
of the threshold voltage fluctuation of the samples after the heavy ion irradiation to linear fitting (shown in FIG. 2); and 2.9 is a slope obtained by subjecting the Pelgrom diagram

(17) ${\sigma }_{\Delta VT}\sim \frac{1}{\sqrt{WL}}$
of the threshold voltage fluctuation of the samples before the heavy ion irradiation to linear fitting (shown in FIG. 2).

(18) 8) A total fluctuation σ.sub.total of the N-type metal oxide semiconductor to be evaluated is as follow:
σ.sub.total=σ.sub.SEE+σ.sub.PV;

(19) where σ.sub.PV is an initial process fluctuation of the N-type metal oxide semiconductor to be evaluated.

(20) 9) The total fluctuation σ.sub.total is substituted into Monte Carlo simulation to obtain a corrected design margin of a circuit that works under the irradiation.

(21) The fluctuation induced by SEE is obtained and adopted to correct a process fluctuation model, so as to obtain a corrected design margin of a circuit that works under the irradiation. The method has simple calculation and broad application, and improves the working reliability of the nano-integrated circuits that work under the irradiation.

(22) Described above are merely illustrative and are not intended to limit the present application. It should be understood that various replacements and modifications made by those skilled in the art without departing from the spirit of the application shall fall within the scope of this application defined by the appended claims.