Insulating device

Abstract

Provided is an insulating device capable of improving reliability. The insulating device includes a first electrode, a second electrode, and an insulating film provided between the first electrode and the second electrode. The insulating film has a positively charged region. The positively charged region is disposed in a portion of the insulating film in a direction from the first electrode toward the second electrode.

Description

TECHNICAL FIELD

[0001] The present embodiment relates to an insulating device. BACKGROUND

[0002] In an insulating device such as a digital isolator, in order to ensure high electric field resistance, a pair of electrodes are insulated from each other with a thick insulating film. In such an insulating device, there is a problem that the reliability is reduced because the electric field is concentrated on the end portions of the electrodes.

[0003] [Patent Literature 1] Japanese Patent Application Publication No. 2020-129657 SUMMARY

[0004] An object of the embodiment is to provide an insulating device capable of improving reliability.

[0005] The insulating device of the embodiment includes a first electrode, a second electrode, and an insulating film provided between the first electrode and the second electrode. The insulating film has a positive charge region. The positive charge region is disposed in a portion of the insulating film in a direction from the first electrode toward the second electrode. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is a cross-sectional view showing an insulating device of a first embodiment.

[0007] Figure 2 (a) of FIG. 1 is a partial cross-sectional view showing an insulating device of a first embodiment. Figure 1 (b) is a graph showing a potential distribution in the insulating film, (c) is a graph showing an electric field intensity distribution in the insulating film, and (d) is a graph showing a relationship between the potential and the electric field intensity in the insulating film. Figure 1 (e) is a graph showing a potential distribution in the insulating film, and (f) is a graph showing an electric field intensity distribution in the insulating film.

[0008] Figure 3 (a) of FIG. 3 is a partial cross-sectional view showing an insulating device of a second embodiment, (b) is a graph showing a potential distribution in the insulating film, and (c) is a graph showing an electric field intensity distribution in the insulating film.

[0009] Figure 4 (a) of FIG. 4 is a partial cross-sectional view showing an insulating device of a second embodiment, (b) is a graph showing a potential distribution in the insulating film, and (c) is a graph showing an electric field intensity distribution in the insulating film. Figure 4(c) is a graph in which the horizontal axis takes the density of positive charges in a positively charged region, and the vertical axis takes the electric field reduction rate (E / E0), and shows the influence of positive charges on the electric field intensity distribution.

[0010] Figure 5 (a) and (b) are graphs showing the molecular structure of silicon oxide, (a) shows a state in which there is no oxygen vacancy, and (b) shows a state in which there is an oxygen vacancy.

[0011] Figure 6 (a) and (b) are graphs in which the horizontal axis takes the binding energy, and the vertical axis takes the intensity, and show the peak corresponding to the 2p inner shell level of silicon in the XPS analysis result of silicon oxide, (a) shows a case in which the concentration of oxygen vacancy is low, and (b) shows a case in which the concentration of oxygen vacancy is high.

[0012] Figure 7 is a graph in which the horizontal axis takes the concentration of oxygen vacancy, and the vertical axis takes the peak shift amount, and shows the influence of oxygen vacancy on the peak shift amount.

[0013] Figure 8 (a) of is a partial cross-sectional view showing the insulating device of the third embodiment, (b) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric potential, and shows the electric potential distribution in the insulating film, and (c) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric field intensity, and shows the electric field intensity distribution in the insulating film.

[0014] Figure 9 (a) of is a partial cross-sectional view showing the insulating device of the fourth embodiment, (b) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric potential, and shows the electric potential distribution in the insulating film, and (c) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric field intensity, and shows the electric field intensity distribution in the insulating film.

[0015] Figure 10 (a) of is a partial cross-sectional view showing the insulating device of the fifth embodiment, (b) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric potential, and shows the electric potential distribution in the insulating film, and (c) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric field intensity, and shows the electric field intensity distribution in the insulating film.

[0016] Figure 11 (a) of is a partial cross-sectional view showing the insulating device of the reference example, (b) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric potential, and shows the electric potential distribution along the Figure 11 (a) is a graph showing the electric potential distribution along the single-dot line B shown in (a) of, (c) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric field intensity, and shows the electric field intensity distribution along the Figure 11 (a) is a graph showing the electric field intensity distribution along the single-dot line B shown in (a) of, (d) is a partial cross-sectional view showing the insulating device of the sixth embodiment, and (e) is a graph in which the vertical axis takes the position, and the horizontal axis takes the electric potential, and shows the electric potential distribution along the Figure 11The graph (d) shows the potential distribution along the single-dotted line B. (f) shows the position on the vertical axis and the electric field intensity on the horizontal axis, while the graph represents the potential distribution along the line B. Figure 11 The curve of electric field intensity distribution of the single-dotted line B is shown in (d).

[0017] Figure 12 (a) is a partial cross-sectional view of the insulating device according to the seventh embodiment, (b) is a graph showing the potential distribution in the insulating film with position on the vertical axis and potential on the horizontal axis, and (c) is a graph showing the electric field intensity distribution in the insulating film with position on the vertical axis and electric field intensity on the horizontal axis.

[0018] Figure 13 (a) is a partial cross-sectional view of the insulating device of the first modified example of the seventh embodiment, (b) is a graph showing the potential distribution in the insulating film with position on the vertical axis and potential on the horizontal axis, and (c) is a graph showing the electric field intensity distribution in the insulating film with position on the vertical axis and electric field intensity on the horizontal axis.

[0019] Figure 14 (a) is a partial cross-sectional view of the insulating device of the second modified example of the seventh embodiment, (b) is a graph showing the potential distribution in the insulating film with position on the vertical axis and potential on the horizontal axis, and (c) is a graph showing the electric field intensity distribution in the insulating film with position on the vertical axis and electric field intensity on the horizontal axis.

[0020] Figure 15 This is a partial cross-sectional view showing the insulating device according to the eighth embodiment. Detailed Implementation

[0021] <First Implementation Method>

[0022] Figure 1 This is a cross-sectional view showing the insulating device of this embodiment.

[0023] The insulating device 1 in this embodiment is, for example, a digital isolator with magnetic insulation or capacitive insulation.

[0024] like Figure 1 As shown, in the insulating device 1, a lower electrode 11 is provided, and an upper electrode 12, separate from the lower electrode 11, is provided on the lower electrode 11. The lower electrode 11 and the upper electrode 12 are, for example, coils. An insulating film 10 is provided between the lower electrode 11 and the upper electrode 12. Furthermore, all the accompanying drawings are schematic diagrams and are not intended to strictly correspond to actual products. For example, in... Figure 1 In the middle, five lower electrodes 11 and five upper electrodes 12 are depicted, but the number of each electrode can be more than six or less than four, and can be an even number or an odd number.

[0025] The insulating film 10 comprises, for example, silicon (Si) and oxygen (O), such as silicon oxide. Positively charged regions 21 are formed within the insulating film 10. These positively charged regions 21 contain positive charges and are positively charged. The charge density of the positively charged regions is preferably 1 × 10⁻⁶. 16 cm -3 The above. As will be described later, positive charges are formed, for example, by oxygen vacancies in silicon oxide, corona discharge, or hafnium oxide.

[0026] When the positively charged region 21 is generated due to oxygen vacancies, the oxygen concentration in the positively charged region 21 is lower than the oxygen concentration in the region outside the positively charged region 21 of the insulating film 10. For example, the positively charged region 21 is made of SiO2. x (x is less than 2) is formed, and the region outside the positively charged region 21 in the insulating film 10 is composed of SiO2.

[0027] The direction from the lower electrode 11 toward the upper electrode 12 is defined as the "vertical direction D". A positively charged region 21 is disposed in a portion of the insulating film 10 in the vertical direction D. The thickness of the insulating film 10 in the vertical direction D is, for example, a few μm to tens of μm.

[0028] A grounding electrode 13 is provided around the lower electrode 11. Multiple through holes 15 are provided around the portion 14 of the insulating film 10 located between the lower electrode 11 and the upper electrode 12. The through holes 15 are connected to the grounding electrode 13. The through holes 15 function as magnetic shielding elements. Alternatively, the grounding electrode 13 and the through holes 15 may not be provided.

[0029] Figure 2 (a) means Figure 1 (a) is a partial cross-sectional view of region A, (b) is a graph showing the potential distribution in the insulating film with the vertical axis representing position and the horizontal axis representing potential, (c) is a graph showing the electric field intensity distribution in the insulating film with the vertical axis representing position and the horizontal axis representing electric field intensity, and (d) is a graph showing... Figure 1 A partial cross-sectional view of region A, (e) is a graph showing the potential distribution in the insulating film with the vertical axis representing position and the horizontal axis representing potential, and (f) is a graph showing the electric field intensity distribution in the insulating film with the vertical axis representing position and the horizontal axis representing electric field intensity.

[0030] Figure 2 (a) to (c) are used as reference examples to represent the case where a positive charged region 21 is not set. Figure 2 (d) to (f) in this embodiment represent the case where a positive charged region 21 is provided. Figure 2 The positions represented by the vertical axis in (b) and (c) are... Figure 2 (a) corresponds to. Figure 2 The positions represented by the vertical axes of (e) and (f) are related toFigure 2 The (d) corresponds to. In Figure 2 In (d), a positive charge is represented by a circle surrounding the symbol "+". The same applies to the same diagram described later. Figure 2 In (e) and (f), dashed lines are used to represent... Figure 2 The curves shown in (b) and (c) are as follows.

[0031] When the insulating device 1 operates, a signal with a higher potential than that of the lower electrode 11 is input to the upper electrode 12. Additionally, a ground potential is applied to the ground electrode 13. As a result, as... Figure 2 As shown in (a), when no positive charged region 21 is provided in the insulating film 10, as Figure 2 As shown in (b), the potential distribution becomes linear, as... Figure 2 As shown in (c), the electric field strength is constant. However, in Figure 1 The electric field is concentrated near the corner 16 of the upper electrode 12 shown, therefore, as Figure 2 As shown by the double-dotted line in (c), the electric field strength is increased compared to other parts. Therefore, impact ionization occurs near the corner 16 of the insulating film 10, potentially leading to avalanche breakdown.

[0032] In contrast, such as Figure 2 As shown in (d), in the insulating device 1 of this embodiment, a positively charged region 21 is provided in the insulating film 10. Therefore, as Figure 2 As shown in (e), the potential of the positively charged region 21 in the insulating film 10 increases. As a result, as... Figure 2 As shown in (f), the electric field intensity distribution is not linear. In the portion of the positively charged region 21 near the lower electrode 11 in the insulating film 10, the electric field intensity increases, but in the portion near the upper electrode 12, the electric field intensity decreases. This suppresses the increase in electric field intensity near the corner 16. As a result, avalanche breakdown is less likely to occur, and the reliability of the insulating device 1 is improved.

[0033] Thus, according to this embodiment, by providing a positively charged region 21 in the insulating film 10, the electric field concentration near the corner 16 of the upper electrode 12 can be suppressed, improving the reliability of the insulating device 1. Furthermore, in the lower electrode 11, the electric field concentration at the corner is mitigated by the grounding electrode 13 arranged around the lower electrode 11.

[0034] The method for forming a positive charge in the insulating film 10 will be described below.

[0035] First, the method of forming a positive charge through oxygen vacancies will be explained.

[0036] The insulating film 10 is formed, for example, by depositing silicon oxide using plasma CVD (Chemical Vapor Deposition). As a source for the plasma CVD, a mixed gas composed of silane (SiH4), dinitrogen monoxide (N2O), and oxygen (O2) is used. Also, at the time of forming the positive charge region 21, the composition of the source is changed to be rich in nitrogen (N) and poor in oxygen (O). After the formation of the positive charge region 21 is completed, the composition of the source is restored. Thus, the insulating film 10 including the positive charge region 21 is formed.

[0037] Next, a method of forming a positive charge by corona discharge will be described.

[0038] The insulating film 10 is formed to an intermediate stage by depositing silicon oxide using plasma CVD. Next, at the time of forming the positive charge region 21, the intermediate structure is taken out from the plasma CVD apparatus, and corona discharge is applied. Thus, a positive charge is accumulated on the exposed surface of the insulating film 10 in the intermediate structure. Next, the intermediate structure is put back into the plasma CVD apparatus, and silicon oxide is deposited by plasma CVD. Thus, the insulating film 10 including the positive charge region 21 is formed.

[0039] Next, a method of forming a positive charge by hafnium oxide will be described.

[0040] The insulating film 10 is formed to an intermediate stage by depositing silicon oxide using plasma CVD. Next, at the time of forming the positive charge region 21, the intermediate structure is taken out from the plasma CVD apparatus, and hafnium oxide (HfO2) is deposited by the ALD (Atomic Layer Deposition) method. The layer composed of this hafnium oxide becomes the positive charge region 21. Next, the intermediate structure is put back into the plasma CVD apparatus, and silicon oxide is deposited by plasma CVD. Thus, the insulating film 10 including the positive charge region 21 is formed.

[0041] <Second Embodiment>

[0042] Figure 3 (a) is a partial cross-sectional view of the insulating device of the present embodiment, (b) is a graph showing the potential distribution in the insulating film with the longitudinal axis representing the position and the lateral axis representing the potential, and (c) is a graph showing the electric field intensity distribution in the insulating film with the longitudinal axis representing the position and the lateral axis representing the electric field intensity.

[0043] Figure 3 The region shown in (a) of FIG. 10 corresponds to the region A of FIG. 1. Figure 1 Figure 3 The positions represented by the longitudinal axes of (b) and (c) of FIG. 10 correspond to the positions represented by the longitudinal axis of (a) of FIG. 1. In (b) and (c) of FIG. 10, the potential and the electric field intensity are shown in the vicinity of the positive charge region 21. Figure 3 (a) of FIG. 10. In (b) and (c) of FIG. 10, the potential and the electric field intensity are shown in the vicinity of the positive charge region 21.​Figure 3 In (b) and (c), dashed lines are used to represent... Figure 2 The curves shown in (b) and (c) are as follows.

[0044] like Figure 3 As shown in (a), in the insulating device 2 of this embodiment, the thickness t of the positively charged region 21 in the vertical direction D is thicker than that of the insulating device 1 of the first embodiment. Therefore, as Figure 3 As shown in (b), the portion of the insulating film 10 with increased potential has a thicker thickness. As a result, as... Figure 3 As shown in (c), the electric field strength changes slowly. Furthermore, by increasing the thickness t, the amount of charge contained in the positively charged region 21 increases. The thickness t, i.e., the length of the positively charged region 21 along the vertical direction D, is preferably 500 nm or more.

[0045] Figure 4 (a) is a partial cross-sectional view of the insulating device of this embodiment, and (b) is a graph showing the potential distribution in the insulating film with the vertical axis representing position and the horizontal axis representing electric field strength.

[0046] like Figure 4 As shown in (a) and (b), when the positive charged region 21 is not provided, the electric field strength at the interface between the insulating film 10 and the upper electrode 12 is set to E0; when the positive charged region 21 is provided, the electric field strength at the interface between the insulating film 10 and the upper electrode 12 is set to E. Furthermore, a value (E / E0) is defined as the rate of decrease in electric field caused by the positive charged region 21.

[0047] Figure 4 (c) is the density of positive charges in the charged region with the horizontal axis positive and the electric field reduction rate (E / E0) on the vertical axis, which is a curve representing the effect of positive charges on the electric field intensity distribution.

[0048] like Figure 4 As shown in (c), the electric field reduction rate (E / E0) decreases as the density of positive charge in the positively charged region 21 increases. Figure 4 In the example shown in (c), if the density of positive charge is 1 × 10⁻⁶ 16 cm -3 The above shows a decrease in the rate of decrease in electric field (E / E0). If the density of positive charge is 1 × 10⁻⁶... 17 cm -3 In this case, the electric field reduction rate (E / E0) is 0.8 or less. The electric field reduction rate is preferably sufficient to offset the electric field concentration at the corner 16.

[0049] The structures, actions, and effects in this embodiment other than those described above are the same as in the first embodiment.

[0050] The following describes an example of a method for evaluating the density of positive charge in a positively charged region 21.

[0051] Figure 5 (a) and (b) are diagrams representing the molecular structure of silicon oxide, where (a) represents the state without oxygen vacancies and (b) represents the state with oxygen vacancies.

[0052] like Figure 5 As shown in (a), in the absence of oxygen vacancies, one silicon atom bonds with four oxygen atoms. In contrast, as... Figure 5 As shown in (b), in the presence of an oxygen vacancy, one silicon atom combines with three oxygen atoms, and one of the silicon atom's bonds becomes unbonded.

[0053] Figure 6 (a) and (b) are graphs with the binding energy on the horizontal axis and the detection intensity on the vertical axis, representing the peaks corresponding to the 2p inner shell energy level (Si2p) of silicon oxide in the XPS (X-ray Photographron Spectroscopy) analysis results. (a) represents the case with low oxygen vacancy concentration, and (b) represents the case with high oxygen vacancy concentration.

[0054] Figure 6 The oxygen vacancy concentration of the sample shown in (b) is Figure 6 The oxygen vacancy concentration of the sample shown in (a) is about 5 times that of the sample in (a).

[0055] like Figure 6 As shown in (a) and (b), if the concentration of oxygen vacancies in silicon oxide increases, the peak corresponding to the 2p inner shell energy level of silicon shifts to the higher potential side.

[0056] Figure 7 It is a graph that shows the effect of oxygen vacancies on peak shift, with the horizontal axis representing the concentration of oxygen vacancies and the vertical axis representing peak shift.

[0057] Figure 7 The horizontal axis represents the relative intensity of the peak near 2250 eV in XPS analysis, and the intensity of this peak is positively correlated with the concentration of oxygen vacancies.

[0058] like Figure 7 As shown, the higher the oxygen vacancy concentration in silicon oxide, the greater the peak shift. Therefore, if XPS analysis is performed on the positively charged region 21 in the insulating film 10, the oxygen vacancy concentration can be estimated based on the peak shift, and the amount of positive charge can be estimated.

[0059] <Third Implementation Method>

[0060] Figure 8(a) is a partial cross-sectional view of the insulating device of this embodiment, (b) is a graph showing the potential distribution in the insulating film with position on the vertical axis and potential on the horizontal axis, and (c) is a graph showing the electric field intensity distribution in the insulating film with position on the vertical axis and electric field intensity on the horizontal axis.

[0061] Figure 8 The area shown in (a) is equivalent to Figure 1 Region A. Figure 8 The positions represented by the vertical axis in (b) and (c) are... Figure 8 (a) corresponds to. In Figure 8 In (b) and (c), dashed lines are used to represent... Figure 2 The curves shown in (b) and (c) are the same. The same applies to the same graphs described later.

[0062] like Figure 8 As shown in (a), in the insulating device 3 of this embodiment, the positively charged region 21 is located on the side of the upper electrode 12. More specifically, the positively charged region 21 is located between the midpoint 17 of the lower electrode 11 and the upper electrode 12 and the upper electrode 12. The positively charged region 21 may be in contact with the upper electrode 12 or may be separated from it.

[0063] like Figure 8 As shown in (b) and (c), according to this embodiment, the electric field strength near the upper electrode 12 in the insulating film 10 can be effectively reduced. Therefore, electric field concentration near the corner 16 of the upper electrode 12 can be more effectively suppressed. The structure, operation, and effects in this embodiment other than those described above are the same as in the first embodiment.

[0064] <Fourth Implementation Method>

[0065] Figure 9 (a) is a partial cross-sectional view of the insulating device of this embodiment, (b) is a graph showing the potential distribution in the insulating film with position on the vertical axis and potential on the horizontal axis, and (c) is a graph showing the electric field intensity distribution in the insulating film with position on the vertical axis and electric field intensity on the horizontal axis.

[0066] like Figure 9 As shown in (a), in the insulating device 4 of this embodiment, the positively charged region 21 is located on the side of the lower electrode 11. More specifically, the positively charged region 21 is located between the midpoint 17 of the lower electrode 11 and the upper electrode 12 and the lower electrode 11. The positively charged region 21 may be in contact with the lower electrode 11 or may be separated from it.

[0067] like Figure 9(b) and (c) shown, according to the present embodiment, it is possible to reduce the electric field intensity throughout a wide region between the positive charge region 21 and the upper electrode 12 in the insulating film 10. The structure, operation and effects other than the above in the present embodiment are the same as those of the first embodiment.

[0068] <the fifth embodiment>

[0069] Figure 10 (a) is a partial sectional view showing an insulating device of the present embodiment, (b) is a graph showing the potential distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the potential, and (c) is a graph showing the electric field intensity distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the electric field intensity.

[0070] As shown in (a) of FIG. 10, in the insulating device 5 of the present embodiment, in the insulating film 10, in addition to the positive charge region 21, a negative charge region 22 is provided. In the negative charge region 22, negative charges are accumulated. In the negative charge region 22, the potential is lower than that in the positive charge region 21. Figure 10 In (a) of FIG. 10, the negative charges are represented by a figure in which the symbol "-" is surrounded by a circle. The same is true in the same figures described later. The negative charges are accumulated, for example, by corona discharge. Figure 10

[0071] In the present embodiment, the negative charge region 22 is disposed at a position closer to the lower electrode 11 than the positive charge region 21. That is, the negative charge region 22 is located between the lower electrode 11 and the positive charge region 21. The negative charge region 22 can be in contact with the positive charge region 21 or can be separated therefrom.

[0072] As shown in (b) of FIG. 10, in the insulating device 5, in the positive charge region 21, the potential rises, and in the negative charge region 22, the potential falls. Thus, as shown in (c) of FIG. 10, in addition to the vicinity of the upper electrode 12, it is possible to reduce the electric field intensity in the vicinity of the lower electrode 11. As a result, the reliability of the insulating device 5 is further improved. Figure 10 Figure 10

[0073] Thus, according to the present embodiment, by providing the negative charge region 22 and the positive charge region 21 in the insulating film 10, it is possible to suppress the electric field concentration in the vicinity of the lower electrode 11 and the upper electrode 12, and to improve the reliability of the insulating device 5. The structure, operation and effects other than the above in the present embodiment are the same as those of the first embodiment.

[0074] <the sixth embodiment>

[0075] Figure 11 (a) is a partial sectional view showing an insulating device of the present embodiment, (b) is a graph showing the potential distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the potential, and (c) is a graph showing the electric field intensity distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the electric field intensity. Figure 11 ​​​(a) shows the potential distribution curve of the single-dotted line B. (c) shows the position on the vertical axis and the electric field intensity on the horizontal axis, while the curve represents the potential distribution along the line B. Figure 11 (a) is a graph showing the electric field intensity distribution along the single-dotted line B; (d) is a partial cross-sectional view showing the insulating device of this embodiment; (e) shows the position on the vertical axis and the potential on the horizontal axis, while the graph shows the electric field intensity distribution along the line B. Figure 11 The graph (d) shows the potential distribution along the single-dotted line B. (f) shows the position on the vertical axis and the electric field intensity on the horizontal axis, while the graph represents the potential distribution along the line B. Figure 11 The curve of electric field intensity distribution of the single-dotted line B is shown in (d).

[0076] Figure 11 Examples (a) to (c) are provided for reference, indicating cases where no positive charged region 21 and negative charged region 22 are provided. Figure 11 In this embodiment, (d) to (f) represent the case where a positive charged region 21 and a negative charged region 22 are provided. Figure 11 The positions represented by the vertical axis in (b) and (c) are... Figure 11 (a) corresponds to. Figure 11 The positions represented by the vertical axes of (e) and (f) are related to Figure 11 The (d) corresponds to. In Figure 11 In (e) and (f), dashed lines are used to represent... Figure 11 The curves shown in (b) and (c) are also shown. Additionally, in Figure 11 In (b) and (e), the influence of the corners of the lower electrode 11 and the upper electrode 12 was not considered, but... Figure 11 In (c) and (f), the effect of the corners is considered. The same applies to the same diagrams described later.

[0077] like Figure 11 As shown in (a) to (c), assuming that the positive charged region 21 and the negative charged region 22 are not provided, the electric field is concentrated near the end of the lower electrode 11 and the end of the upper electrode 12 in the insulating film 10, and the electric field strength increases. As a result, avalanche breakdown is prone to occur in these regions.

[0078] In contrast, such as Figure 11As shown in (d), in the insulating device 6 of the present embodiment, in the insulating film 10, the negatively charged region 22 is arranged in the vicinity of the lower electrode 11, and the positively charged region 21 is arranged in the vicinity of the upper electrode 12. More specifically, the negatively charged region 22 is located between the lower electrode 11 and the midpoint 17 of the upper electrode 12. The negatively charged region 22 can be in contact with the lower electrode 11 or can be separated. On the other hand, the positively charged region 21 is located between the midpoint 17 and the upper electrode 12. The positively charged region 21 can be in contact with the upper electrode 12 or can be separated. The positively charged region 21 is separated from the negatively charged region 22.

[0079] Therefore, as shown in (e), in the insulating film 10, the potential is decreased in the vicinity of the lower electrode 11, and the potential is increased in the vicinity of the upper electrode 12. As a result, as shown in (f), the electric field intensity in the vicinity of the lower electrode 11 and in the vicinity of the upper electrode 12 in the insulating film 10 is decreased, and the concentration of the electric field at the end portion is mitigated. As a result, it is difficult for avalanche breakdown to occur, and the reliability of the insulating device 6 is improved. The structures, operations, and effects other than the above in the present embodiment are the same as those of the first embodiment. Figure 12 Figure 12 Therefore, as shown in (e), in the insulating film 10, the potential is decreased in the vicinity of the lower electrode 11, and the potential is increased in the vicinity of the upper electrode 12. As a result, as shown in (f), the electric field intensity in the vicinity of the lower electrode 11 and in the vicinity of the upper electrode 12 in the insulating film 10 is decreased, and the concentration of the electric field at the end portion is mitigated. As a result, it is difficult for avalanche breakdown to occur, and the reliability of the insulating device 6 is improved. The structures, operations, and effects other than the above in the present embodiment are the same as those of the first embodiment.

[0080] <Seventh Embodiment>

[0081] Figure 12 (a) is a partial cross-sectional view showing the insulating device of the present embodiment, (b) is a graph showing the potential distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the potential, and (c) is a graph showing the electric field intensity distribution in the insulating film, with the vertical axis representing the position and the horizontal axis representing the electric field intensity.

[0082] As shown in (a), in the insulating device 7 of the present embodiment, in the insulating film 10, a plurality of positively charged regions 21 and a plurality of negatively charged regions 22 are alternately arranged along the up-down direction D. In the laminate composed of the plurality of positively charged regions 21 and the plurality of negatively charged regions 22, a negatively charged region 22a is arranged at the position closest to the lower electrode 11, and a positively charged region 21a is arranged at the position closest to the upper electrode 12. Figure 12 Thus, as shown in (b), the potential distribution along the up-down direction D becomes wavy, and as shown in (c), the electric field intensity distribution along the up-down direction D also becomes wavy. As a result, compared to the sixth embodiment shown in (f), the electric field in the portion between the positively charged region 21a and the negatively charged region 22a in the insulating film 10 can be mitigated. The structures, operations, and effects other than the above in the present embodiment are the same as those of the first embodiment.

[0083] Figure 11 Thus, as shown in (b), the potential distribution along the up-down direction D becomes wavy, and as shown in (c), the electric field intensity distribution along the up-down direction D also becomes wavy. As a result, compared to the sixth embodiment shown in (f), the electric field in the portion between the positively charged region 21a and the negatively charged region 22a in the insulating film 10 can be mitigated. The structures, operations, and effects other than the above in the present embodiment are the same as those of the first embodiment. Figure 13 Figure 13 Thus, as shown in (b), the potential distribution along the up-down direction D becomes wavy, and as shown in (c), the electric field intensity distribution along the up-down direction D also becomes wavy. As a result, compared to the sixth embodiment shown in (f), the electric field in the portion between the positively charged region 21a and the negatively charged region 22a in the insulating film 10 can be mitigated. The structures, operations, and effects other than the above in the present embodiment are the same as those of the first embodiment.​​​

[0084] <First Variation of the Seventh Embodiment>

[0085] Figure 12 (a) is a partial cross-sectional view of the insulating device of this modified example, (b) is a graph showing the potential distribution in the insulating film with the vertical axis representing position and the horizontal axis representing potential, and (c) is a graph showing the electric field intensity distribution in the insulating film with the vertical axis representing position and the horizontal axis representing electric field intensity.

[0086] like Figure 14 As shown in (a), in the insulating device 7a of this modified example, compared with the insulating device 7 of the seventh embodiment (refer to...), Figure 14 Compared to (a), the distribution of charge is different. More specifically, the positive charge of the charged regions 21 other than the charged region 21a closest to the upper electrode 12 is less than the positive charge of the positive charged region 21a closest to the upper electrode 12. Similarly, the negative charge of the charged regions 22 other than the charged region 22a closest to the lower electrode 11 is less than the negative charge of the negative charged region 22a closest to the lower electrode 11.

[0087] Therefore, the amplitude of the electric field strength can be reduced in the portion between the positively charged region 21a and the negatively charged region 22a in the insulating film 10. Depending on the usage of the insulating device, as in this modified example, adjusting the charge distribution according to position is effective. The structure, operation, and effects other than those described above in this modified example are the same as in the seventh embodiment.

[0088] <Second variation of the seventh embodiment>

[0089] Figure 12 (a) is a partial cross-sectional view of the insulating device of this modified example, (b) is a graph showing the potential distribution in the insulating film with the vertical axis representing position and the horizontal axis representing potential, and (c) is a graph showing the electric field intensity distribution in the insulating film with the vertical axis representing position and the horizontal axis representing electric field intensity.

[0090] like Figure 15 As shown in (a), in the insulating device 7b of this modified example, compared with the insulating device 7 of the seventh embodiment (refer to...), Figure 15 Compared to (a), the arrangement period of the positive charged region 21 and the negative charged region 22 in the vertical direction D is shorter. Therefore, the amplitude of the electric field strength can be reduced in the portion between the positive charged region 21a and the negative charged region 22a in the insulating film 10. Depending on the usage of the insulating device, adjusting the arrangement period of the charged regions is effective, as in this modified example. The structure, operation, and effects other than those described above in this modified example are the same as in the seventh embodiment.

[0091] <eighth embodiment>

[0092] ​ is a partial cross-sectional view of an insulating device of the present embodiment.

[0093] In the present embodiment, an example in which the positive charge region 23 is formed of hafnium oxide instead of oxygen vacancies of silicon oxide.

[0094] As ​ indicated, in the insulating device 8 of the present embodiment, the positive charge region 23 is provided in the insulating film 10. The positive charge region 23 contains hafnium (Hf) and oxygen (O), for example, contains hafnium oxide (Hf02). The portion other than the positive charge region 23 in the insulating film 10 contains silicon (Si) and oxygen (O), for example, contains silicon oxide (Si02). Thereby, the positive charge region can also be realized in the insulating film 10, obtaining the same effect as the first embodiment. The above-described structure, operation, and effect in the present embodiment are the same as those of the first embodiment.

[0095] According to the above-described embodiments, an insulating device capable of improving reliability can be realized.

[0096] The above-described several embodiments of the present application have been described, but these embodiments are presented as examples and are not intended to limit the scope of the application. These new embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made within the scope of the gist of the application. These embodiments and modifications thereof are included in the scope or gist of the application, and are included in the scope of the application and equivalents thereof recited in the claims. In addition, the above-described embodiments and modifications thereof can also be implemented in combination with each other.

[0097] [Explanation of reference numerals]

[0098] 1, 2, 3, 4, 5, 6, 7, 7a, 7b, 8: insulating device

[0099] 10: insulating film

[0100] 11: lower electrode

[0101] 12: upper electrode

[0102] 13: ground electrode

[0103] 14: portion

[0104] 15: via hole

[0105] 16: corner

[0106] 17: midpoint

[0107] 21, 21a: positively charged region

[0108] 22, 22a: negatively charged region

[0109] 23: positively charged region

[0110] D: up-down direction

[0111] t: thickness

Claims

1. An insulating device comprising: First electrode; The second electrode; and An insulating film is disposed between the first electrode and the second electrode, and has a positively charged region, which is located on a portion of the direction from the first electrode toward the second electrode. The charge density of the positive charged region is 1×10⁻⁶. 16 cm -3 above.

2. The insulating device according to claim 1, wherein, The positive charged region is located between the midpoint between the first electrode and the second electrode and the second electrode.

3. The insulating device according to claim 1, wherein, The insulating film also has a negatively charged region, which is disposed in other portions in the said direction.

4. The insulating device according to claim 3, wherein, The negative charged region is located between the first electrode and the positive charged region.

5. The insulating device according to claim 3, wherein, The plurality of positively charged regions and the plurality of negatively charged regions are arranged alternately along the direction.

6. The insulating device according to claim 1, wherein, The length of the positive charged region along the direction is 500 nm or more.

7. The insulating device according to claim 1, wherein, The positive charged region is composed of SiO x The composition is given by the expression, where x is less than 2.

8. The insulating device according to claim 1, wherein, The insulating film contains silicon and oxygen, and the oxygen concentration in the positively charged region is lower than the oxygen concentration in regions outside the positively charged region of the insulating film.

9. The insulating device according to claim 1, wherein, The insulating film comprises silicon and oxygen, and the positively charged region comprises hafnium and oxygen.

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