JP2010129975A - Anti-fuse element and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-fuse element for specifying a short-circuit place, highly precisely controlling a short-circuit causing voltage, and being economically manufactured, and to provide a manufacturing method therefor. <P>SOLUTION: The anti-fuse element includes: (a) at least a pair of electrode films 15, 17 opposing each other; (b) an insulating film 16 disposed between the pair of electrode films 15, 17; and (c) a substrate 12 supporting the pair of electrode films 15, 17 and the insulating film 16. When transparently viewed from a film-thickness direction, at least one electrode film 17 is formed with an angular portion 17a having a sharp tip, while the angular portion 17a is superimposed on the other electrode film 15. When a voltage is applied to between the electrode films 15, 17, a magnetic field concentrates in the vicinity of the tip of the angular portion 17a of one electrode film 17, thus narrows a short-circuit place to the vicinity of the tip of the angular portion 17a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antifuse element and a manufacturing method thereof.

  A general fuse is blown when the voltage exceeds a predetermined level and cuts off the current. On the other hand, an antifuse element has been proposed that is short-circuited when a voltage exceeding a predetermined level is reached, and a current flows.

  For example, in the antifuse element shown in the cross-sectional view of FIG. 9, insulating layers 122 and 123 are sandwiched between conductive layers 121 and 125, and one conductive layer 121 has an acute corner portion 124. Since the electric field strength increases at the acute corner portion 124, the voltage for starting the current interruption operation, that is, the breakdown voltage (short circuit voltage) can be reduced without reducing the thickness of the insulating layer.

In such a structure, a conductive layer and an upper insulating layer are sequentially formed over the base insulating layer 120. Next, patterning is performed in an island shape, and the side wall of the patterned conductive layer 121 is thermally oxidized to form a thermally oxidized dielectric layer 123 on the side wall portion. At the same time, an acute corner portion 124 is formed on the edge portion of the conductive layer 121. Next, a second conductive layer 125 is formed so as to cover the upper insulating layer 122, the oxide dielectric layer 123, and the base insulating layer 120 (see, for example, Patent Document 1).
JP-A-11-135633

  The antifuse element shown in FIG. 9 has a problem that the manufacturing process is complicated and the manufacturing cost is high because the process of manufacturing the protrusion is complicated.

  Further, the acute corner portion 124 formed at the edge of the conductive layer 121 extends in the direction perpendicular to the paper surface in FIG. 9, and the portion leading to the short circuit cannot be specified. Therefore, there are the following problems.

  (A) The fact that the position at which the anti-fuse element is short-circuited cannot be specified means that the location where failure analysis should be performed cannot be specified, so that quality building based on failure analysis cannot be sufficiently performed, and the reliability of the anti-fuse element is increased. I can't. Further, if the portion to be short-circuited by the anti-fuse element can be identified, the non-defective product can be selected by observing the structure of the functional portion (the shape of the acute angle portion), but the non-defective product cannot be selected because the functioning portion cannot be identified.

  (B) The anti-fuse element must not be short-circuited by static electricity generated in the usage environment. In order to improve electrostatic resistance, it is desirable to increase the capacitance between electrodes, and it is desirable to increase the electrode area. When the electrode area is increased, the current path length after the short circuit varies unless the shorted part is specified. Therefore, the resistance value after a short circuit varies in each element.

  Furthermore, in the method of manufacturing the antifuse element shown in FIG. 9, the tip shape of the acute corner portion 124 cannot be sufficiently controlled. Therefore, there is a problem that the degree of electric field concentration at the corner cannot be sufficiently controlled and the short circuit voltage cannot be controlled with high accuracy.

  In view of such circumstances, the present invention intends to provide an antifuse element and a method for manufacturing the same, which can specify a short-circuited location and can control a short-circuit voltage with high accuracy.

  In order to solve the above-described problems, the present invention provides an antifuse element configured as follows.

  The antifuse element includes: (a) at least a pair of opposing electrode films; (b) an insulator film disposed between the pair of electrode films; and (c) the pair of electrode films and the insulator film. And a supporting substrate. When seen through from the film thickness direction, at least one of the pair of electrode films has a corner with a sharp tip, and the corner overlaps the other of the pair of electrode films.

  In the above configuration, one electrode film extends in a direction perpendicular to the film thickness direction, that is, in the plane direction, and has a corner. This corner faces the other electrode film.

  According to the above configuration, when a voltage is applied between the electrode films, the electric field concentrates in the vicinity of the tip of the corner of one electrode film, and the location leading to the short can be limited to the vicinity of the tip of the corner. Since the shape of the corner can be formed with high accuracy, the short-circuit voltage can be controlled with high accuracy. In addition, by forming the corner as a part of the entire shape of one electrode film, a special process only for forming the corner is not required, and the manufacturing cost can be reduced.

  Preferably, the corner portion is formed only at the one position of the pair of electrode films.

  In this case, by limiting the position of the corner to one location, the portion leading to the short is specified as one location. Therefore, failure analysis of a specific part leading to a short circuit ensures sufficient quality, and the reliability of the antifuse element can be improved. In addition, by observing the shape of this specific portion, it is possible to inspect a non-defective product and to provide an antifuse element with more stable quality. In addition, even when a large electrode area is required for countermeasures against static electricity or the like, the current path length after a short circuit can be controlled, so that it is possible to provide an antifuse element in which there is no variation in the resistance value after a short circuit.

  Preferably, the corner is disposed at an intermediate position of a line segment connecting the extraction electrodes respectively connected to the pair of electrode films when seen through from the film thickness direction.

  In this case, the resistance can be reduced by shortening the current path after the short circuit. Moreover, the resistance value after a short circuit can be set.

  The present invention also provides a method for manufacturing an antifuse element configured as follows.

  The method for manufacturing an antifuse element is a method for manufacturing any one antifuse element having the above-described configuration. Including the step of forming the one shape of the pair of electrode films, wherein the corners are formed simultaneously.

  According to the above method, by processing the corner portion simultaneously with the shape processing of one electrode film, it is possible to reduce the man-hours compared to the case where only the corner portion is formed in a separate process, and to manufacture the antifuse element at a low cost. be able to.

  Preferably, in the step of forming the shape when the one of the pair of electrode films is seen through from the film thickness direction, the one of the pair of electrode films is seen through from the film thickness direction using photolithography. The corners are formed simultaneously as part of the shape.

  In this case, a corner portion can be processed with high accuracy in one of the electrode films.

  The present invention also provides another antifuse element configured as follows to solve the above problems.

  The antifuse element includes: (a) at least a pair of opposing electrode films; (b) an insulator film disposed between the pair of electrode films; and (c) the pair of electrode films and the insulator film. And a supporting substrate. At least one of the pair of electrode films is formed with a protrusion with a pointed tip protruding to the other side of the pair of electrode films at a portion facing the other of the pair of electrode films via the insulator film Has been.

  In the above configuration, one electrode film is formed with a protrusion protruding in the film thickness direction toward the other electrode film.

  According to the above configuration, since the distance between the electrode film and the other electrode film is small, the electric field concentrates near the tip of the protrusion when a voltage is applied between the electrode films. The location leading to the short circuit can be limited to the protrusion. Since the shape of the protrusion can be formed with high accuracy, the short-circuit voltage can be controlled with high accuracy.

  Preferably, the protrusion is formed only at the one position of the pair of electrode films.

  In this case, by limiting the position of the protruding portion to one place, the portion leading to the short is specified as one place. Therefore, failure analysis of a specific part leading to a short circuit ensures sufficient quality, and the reliability of the antifuse element can be improved. In addition, by observing the shape of this specific portion, it is possible to inspect a non-defective product and to provide an antifuse element with more stable quality. In addition, even when a large electrode area is required for countermeasures against static electricity or the like, the current path length after a short circuit can be controlled, so that it is possible to provide an antifuse element in which there is no variation in the resistance value after a short circuit.

  The present invention also provides a method for manufacturing another antifuse element configured as follows.

  The method for manufacturing an antifuse element is a method for manufacturing an antifuse element having any one of the above-described configurations. The method for manufacturing an antifuse element includes: (a) forming a shape corresponding to the protrusion on the surface of the insulator film that is an interface between the one of the pair of electrode films and the insulator film; And (b) forming the one of the pair of electrode films on the surface to be the interface where the shape corresponding to the protrusion is formed.

  According to the above method, the tip shape of the protrusion can be controlled in the manufacturing process, and the electric field concentration can be controlled by controlling the tip shape of the protrusion. Therefore, the breakdown voltage (short circuit voltage) can be controlled.

  In one preferred aspect, (a) a step of forming a shape corresponding to the protrusion on the surface of the insulator film, which is an interface with the one of the pair of electrode films, using photolithography; and b) forming the one of the pair of electrode films on the surface to be the interface on which the shape corresponding to the protrusion is formed.

  In this case, the protrusion can be processed with high accuracy.

  In another preferred embodiment, (a) a step of forming a shape corresponding to the protruding portion on the surface of the insulator film with the one of the pair of electrode films by a nano-indent method; and b) forming the one of the pair of electrode films on the surface to be the interface on which the shape corresponding to the protrusion is formed.

  In this case, the protrusion can be processed with high accuracy.

  The present invention also provides another method of manufacturing an antifuse element configured as follows.

  The method for manufacturing an antifuse element is a method for manufacturing an antifuse element having any one of the above-described configurations. The method of manufacturing an antifuse element includes: (a) forming the protrusion on the surface of the one of the pair of electrode films on the interface between the one of the pair of electrode films and the insulator film; And (b) forming the insulator film on the surface to be the interface on which the protrusion is formed.

  According to the above method, the tip shape of the protrusion can be controlled in the manufacturing process, and the electric field concentration can be controlled by controlling the tip shape of the protrusion. Therefore, the breakdown voltage (short circuit voltage) can be controlled.

  A preferable aspect is that: (a) forming one of the protrusions on the surface of the one of the pair of electrode films on the surface of the insulator film using photolithography; and (b) the protrusion. Forming the insulator film on the surface that forms the interface.

  In this case, the protrusion can be processed with high accuracy.

  According to the present invention, it is possible to specify a short-circuit location, to control the short-circuit voltage with high accuracy, and to reduce manufacturing costs.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  Example 1 An antifuse element 10 of Example 1 will be described with reference to FIGS.

  FIG. 1A is a cross-sectional view of the antifuse element 10. FIG. 1B is a plan view of the antifuse element 10.

  As shown in FIG. 1, the antifuse element 10 generally includes an insulator film 14, a lower electrode film 15, an insulator film 16, and an upper electrode film 17 on a thermal oxide film 13 formed on the upper surface of the Si substrate 12. Are sequentially stacked and covered with insulating layers 20 and 22. External electrodes 30 and 32 for mounting the antifuse element 10 on a circuit board or the like are formed on the upper surface 10 s of the antifuse element 10. The electrode films 15 and 17 are electrically connected to the external electrodes 30 and 32 through via-hole conductors 31 and 33 that penetrate the insulating layers 20 and 22, respectively. The via-hole conductor 31 is a lead electrode connected to the upper electrode film 17, and the via-hole conductor 33 is a lead electrode connected to the lower electrode film 15.

  As shown in FIG. 1B, the upper electrode film 17 has a corner 17a with a sharp tip when seen through from the film thickness direction. The upper electrode film 17 is formed so as to overlap the inner side of the lower electrode film 15, and the corner portion 17 a of the upper electrode film 17 overlaps the lower electrode film 15. The via-hole conductor 33 connected to the lower electrode film 15 is formed so as to be closest to the tip of the corner portion 17 a of the upper electrode film 17.

  As shown in FIG. 1B, the corner 17a, which is a location where a short circuit occurs, is arranged at an intermediate position on a line segment connecting both via-hole conductors 31 and 33. In this way, when viewed from the film thickness direction, the corner portion 17a is arranged at an intermediate position on the line segment connecting the via-hole conductors 31 and 33 connected to the electrode films 17 and 15, respectively. The current path can be minimized and the resistance can be reduced. Further, since the location where the short circuit occurs is determined at the position of the corner portion 17a, the resistance value after the short circuit can be set.

  In the antifuse element 10, when a voltage is applied between the electrode films 15 and 17 via the external electrodes 30 and 32, the electric field concentrates near the tip of the corner portion 17 a. While the applied voltage is low, insulation between the electrode films 15 and 17 is maintained by the insulator film 16, and the external electrodes 30 and 32 are in an open (non-conducting) state. When a voltage higher than a predetermined voltage is applied, a short circuit occurs near the tip of the corner 17a, and the external electrodes 30 and 32 are in a closed (conductive) state.

  Next, a method for manufacturing the antifuse element 10 will be described with reference to the cross-sectional views of FIGS.

  As shown in FIG. 2A, a MOD raw material of Ba: Sr: Ti = 7: 3: 10 (molar ratio) is spin-coated on a Si substrate 12 (thickness of 525 μm) with a thermal oxide film 13 and dried. Thereafter, RTA (rapid temperature rise heat treatment) is performed in an oxygen atmosphere at 650 ° C. for 30 minutes to form a BST thin film 14 having a thickness of 100 nm. Next, a Pt electrode film 15 having a thickness of 200 nm is formed by sputtering. Next, spin coating of MOD raw material with Ba: Sr: Ti = 7: 3: 10 (molar ratio), after drying, RTA (rapid temperature rise heat treatment) is performed in an oxygen atmosphere at 650 ° C. for 60 minutes, A 100 nm thick BST thin film 16 is formed. Next, a Pt electrode film 17 having a thickness of 200 nm is formed by sputtering.

  Next, as shown in FIG. 2B, the upper Pt electrode film 17 is processed by photolithography and ion milling. As a result, the shape of the upper electrode film 17 having a corner portion 17a with a sharp tip is formed.

  Next, as shown in FIG. 2C, the BST thin film 16 is processed by photolithography and RIE (reactive ion etching). Thereby, the shape of the insulator film 16 sandwiched between the electrode films 15 and 17 is formed.

  Next, as shown in FIG. 3D, the underlying Pt electrode film 15 is processed using photolithography and ion milling, and the BST thin film 14 that is an adhesion layer is processed using RIE. Next, heat treatment is performed in an oxygen atmosphere at 850 ° C. for 30 minutes.

Next, as shown in FIG. 3E, a 500 nm thick SiN _X layer 20 is formed by sputtering. Next, photosensitive polyimide is applied, exposed, developed, and cured to form a pattern having through holes in the polyimide layer 22. Next, using the polyimide layer 22 as a mask, the SiN _X layer 20 is processed using the RIE method to form through holes 24 and 26 through which the electrode films 17 and 15 are exposed, respectively.

  Next, 100 nm-thick Ti, 2000 nm-thick Ni, and 100 nm-thick Au are deposited by sputtering, and the Au / Ni / Ti is processed using photolithography, ion milling, and RIE. As a result, as shown in FIG. 3F, the via-hole conductors 31 and 33 and the external electrodes 30 and 32 filled in the through holes 24 and 26 are formed, and the antifuse element 10 is completed.

  As described above, since the antifuse element 10 can form the corner portions 17a simultaneously with the patterning process of the upper electrode film 17, it can be manufactured at low cost.

  Further, since the corner portion 17a is formed by photolithography, the position of the corner portion 17a can be controlled, and the portion leading to the short is specified at one location near the tip of the corner portion 17a.

  (A) By analyzing the failure of this specific portion, quality can be built based on the failure analysis, and the reliability of the antifuse element can be improved. In addition, by observing the shape of this specific portion, it is possible to inspect a non-defective product and to provide an antifuse element with more stable quality.

  (B) Even when a large electrode area is required for countermeasures against static electricity or the like, the current path length after a short circuit can be controlled, so that it is possible to provide an element with no variation in resistance value after a short circuit.

  In addition, the corner portion 17a can be formed with high accuracy by photolithography, and the electric field concentration can be controlled by controlling the tip shape of the corner portion 17a. Therefore, the breakdown voltage (short circuit voltage) can be controlled with high accuracy.

  <Modification> As shown in FIG. 1B, when the corner portion 17a is an acute angle, the electric field is more concentrated. However, the present invention is not limited to this, and the corner portion may be a right angle or an obtuse angle.

  Further, the main part of the electrode film forming the corner is not limited to a circular shape, but may be a polygonal shape. In the case of a polygonal shape, it is preferable to form corner portions having angles smaller than the respective corners of the polygon of the main portion of the electrode film so that the electric field is more concentrated near the tip of the corner portion.

  Example 2 An antifuse element 10a of Example 2 will be described with reference to FIGS.

  The antifuse element 10a according to the second embodiment is configured in substantially the same manner as the antifuse element 10 according to the first embodiment. In the following description, the same reference numerals are used for the same components as those of the antifuse element 10 of the first embodiment, and differences from the antifuse element 10 of the first embodiment are mainly described.

  4 and 5 are cross-sectional views showing a manufacturing process of the antifuse element 10a of the second embodiment.

  As shown in FIG. 5I, the antifuse element 10a according to the second embodiment includes an insulator film 16 instead of the corner 17a of the upper electrode film 17 formed in the antifuse element 10 according to the first embodiment. A conical protrusion 17 b is formed at one location on the lower surface 17 s of the upper electrode film 17 facing the lower electrode 15. The distance between the upper electrode film 17 and the lower electrode film 15 is the smallest at the tip of the protrusion 17b. Therefore, when a voltage higher than a predetermined voltage is applied between the electrode films 15 and 17, a short circuit occurs near the tip of the protrusion 17b.

  Next, a method for manufacturing the antifuse element 10a according to the second embodiment will be described with reference to FIGS.

  As shown in FIG. 4A, a MOD raw material of Ba: Sr: Ti = 7: 3: 10 (molar ratio) is spin-coated on a Si substrate 12 (thickness of 525 μm) with a thermal oxide film 13 and dried. Thereafter, RTA (rapid temperature rise heat treatment) is performed in an oxygen atmosphere at 650 ° C. for 30 minutes to form a BST thin film 14 having a thickness of 100 nm. The BST thin film 14 functions as an adhesion layer.

  Next, as shown in FIG. 4B, a Pt electrode film 15 having a thickness of 200 nm is formed by sputtering.

  Next, as shown in FIG. 4C, a MOD raw material having Ba: Sr: Ti = 7: 3: 10 (molar ratio) is spin-coated, dried, and then in an oxygen atmosphere at 650 ° C. for 60 minutes. RTA (rapid temperature rise heat treatment) is performed to form a BST thin film 16 having a thickness of 150 nm.

  Next, as shown in FIG. 4D, a photosensitive resist is applied, exposed and developed on the upper surface 16s of the BST thin film 16 to form a fine resist pattern 16x on the resist 16k. The minute resist pattern 16x can be produced by a method using a gray mask capable of imparting a distribution to the irradiation intensity or by changing various photolithography conditions.

  Next, using the resist 16k on which the minute resist pattern 16x is formed as a mask, the BST thin film 16 is processed by a thickness of 30 nm by the RIE method, and then the resist 16k is removed by oxygen plasma ashing. As a result, as shown in FIG. 4E, a mortar-like minute concave shape 16a is formed on the upper surface 16s of the BST thin film 16 at a position corresponding to the minute resist pattern 16x.

  Next, as shown in FIG. 5F, a Pt electrode film 17 having a thickness of 200 nm is formed by sputtering. At this time, since the Pt electrode film 17 is formed along the upper surface 16s of the BST thin film 16, a protrusion 17b is formed on the lower surface 17s of the Pt electrode film 17 corresponding to the concave shape 16a of the BST thin film 16. The

  Next, as shown in FIG. 5G, the upper Pt electrode film 17 is processed by photolithography and ion milling. Next, the BST thin film 16 is processed using photolithography and RIE. Next, the lower Pt electrode film 15 is processed using photolithography and ion milling, and the BST thin film 14 of the adhesion layer is processed using RIE. Next, heat treatment is performed in an oxygen atmosphere at 850 for 30 minutes.

Next, as shown in FIG. 5H, a SiN _X layer 20 having a thickness of 500 nm is formed by sputtering. Next, photosensitive polyimide is applied, exposed, developed, and cured to form a pattern having through holes in the polyimide layer 22. Next, using the polyimide layer 22 as a mask, the SiN _X layer 22 is processed using the RIE method. As a result, through holes 24 and 26 through which the Pt electrode films 17 and 15 are exposed are formed in the SiN _X layer 20 and the polyimide layer 22.

  Next, 100 nm-thick Ti, 2000 nm-thick Ni, and 100 nm-thick Au are deposited by sputtering, and the Au / Ni / Ti is processed using photolithography, ion milling, and RIE. As a result, as shown in FIG. 5 (i), via-hole conductors 31 and 33 and external electrodes 30 and 32 filled in the through holes 24 and 26 are formed, and the antifuse element 10a is completed.

  Since the antifuse element 10a of the second embodiment described above forms the protrusion 17b with high precision using photolithography, the position of the protrusion 17b can be controlled, and the portion leading to the short is specified at one location.

  (A) By analyzing the failure of this specific portion, quality can be built based on the failure analysis, and the reliability of the antifuse element can be improved. In addition, by observing the shape of this specific portion, it is possible to inspect a non-defective product and to provide an antifuse element with more stable quality.

  (B) Even when a large electrode area is required for countermeasures against static electricity or the like, the current path length after a short circuit can be controlled, so that the resistance value can be lowered, and an antifuse element in which there is no variation in the resistance value after a short circuit is provided. It becomes possible.

  In addition, since the protrusion 17b is accurately formed using photolithography, the size and tip shape of the protrusion 17b can be controlled, and the electric field concentration can be easily controlled, so that the breakdown voltage (short circuit voltage) can be set with high accuracy. Can be controlled.

  Example 3 An antifuse element of Example 3 will be described.

  The configuration of the antifuse element of the third embodiment is the same as the configuration of the antifuse element of the second embodiment.

  The antifuse element of Example 3 differs from the antifuse element of Example 2 only in a part of the manufacturing method, that is, only the step of forming the concave shape 16a on the upper surface 16s of the BST thin film 16.

  Specifically, in the method of manufacturing the antifuse element of Example 3, the BST thin film 14, the Pt electrode film 15, and the BST thin film 16 are formed up to FIG. 4C, that is, on the Si substrate 12 with the thermal oxide film 13. The steps up to here are the same as those of the manufacturing method of the antifuse element of the second embodiment.

  Thereafter, in the second embodiment, the concave shape 16a is formed on the upper surface of the BST thin film 16 using the resist 16k, whereas in the antifuse element manufacturing method of the third embodiment, the concave portion is formed on the upper surface of the BST thin film 16 by the nano-indent method. The shape 16a is formed, and the state shown in FIG. The nano-indent method is a fine processing method for pushing a cantilever used in an AFM (Atomic Force Microscope) or the like. By changing the tip shape of the cantilever, the size and shape of the concave shape 16a formed on the upper surface 16s of the BST thin film 16 can be controlled.

  The process after forming the concave shape 16a in the BST thin film 16 is the same as the manufacturing method of the antifuse element 10a of the second embodiment.

  The manufacturing method of the antifuse element of Example 3 has the same operation and effect as the manufacturing method of the antifuse element of Example 2.

  That is, since the protrusion 17b can be formed with high accuracy by the nano-indent method, the position of the protrusion 17b can be controlled, and the portion leading to the short is specified at one place. Therefore, quality improvement by failure analysis and non-defective product inspection by shape observation are possible. In addition, it is possible to eliminate variations in resistance values after a short circuit.

  Further, since the size and the tip shape of the protrusion 17b can be controlled and the electric field concentration can be easily controlled, the breakdown voltage (short circuit voltage) can be controlled with high accuracy.

  Example 4 An antifuse element of Example 4 will be described with reference to FIGS. 6 and 7.

  6 and 7 are cross-sectional views showing manufacturing steps of the antifuse element 10b of the fourth embodiment.

  As shown in FIG. 7 (i), the antifuse element 10b of the fourth embodiment has an insulator film 16 instead of the corner portion 17a of the upper electrode film 17 formed in the antifuse element 10 of the first embodiment. The antifuse element 10 of the first embodiment is different from the antifuse element 10 of the first embodiment in that a conical protrusion 15a is formed at one location on the upper surface 15s of the lower electrode film 15 opposite to the upper electrode film 17. The distance between the lower electrode film 15 and the upper electrode film 17 is the smallest at the tip of the protrusion 15a. Therefore, when a voltage higher than a predetermined voltage is applied between the electrode films 15 and 17, a short circuit occurs near the tip of the protrusion 15a.

  Next, a method for manufacturing the antifuse element 10b of Example 4 will be described with reference to FIGS. In the method for manufacturing the antifuse element 10b of the fourth embodiment, the protrusion 15a is formed when the upper surface 15s of the lower electrode film 15 is processed. Details will be described below.

  As shown in FIG. 6A, a MOD raw material of Ba: Sr: Ti = 7: 3: 10 (molar ratio) is spin-coated on a Si substrate 12 (thickness of 525 μm) with a thermal oxide film 13 and dried. Thereafter, RTA (rapid temperature rise heat treatment) is performed in an oxygen atmosphere at 650 ° C. for 30 minutes to form a BST thin film 14 having a thickness of 100 nm. The BST thin film 14 functions as an adhesion layer.

  Next, as shown in FIG. 6B, a Pt electrode film 15 having a thickness of 200 nm is formed by sputtering.

  Next, as shown in FIG. 6C, a photosensitive resist is applied, exposed, and developed to form a fine resist pattern 15x. The minute resist pattern 15x can be manufactured by a method using a gray mask capable of giving a distribution to the irradiation intensity or by changing the photolithography conditions.

  Next, using the fine resist pattern 15x as a mask, the Pt electrode film 15 is processed to a thickness of 30 nm by ion milling, and then the remaining fine resist pattern 15x is removed by oxygen plasma ashing. As a result, as shown in FIG. 6 (d), a protrusion 15 a is formed on the upper surface 15 s of the Pt electrode film 15.

  Next, as shown in FIG. 6E, a MOD raw material having Ba: Sr: Ti = 7: 3: 10 (molar ratio) is spin-coated, dried, and then in an oxygen atmosphere at 650 ° C. for 60 minutes. RTA (rapid temperature rise heat treatment) is performed to form a BST thin film 16 having a thickness of 150 nm.

  Next, as shown in FIG. 7F, a Pt electrode film 17 having a thickness of 200 nm is formed by sputtering.

Next, as shown in FIG. 7G, the upper Pt electrode film 17 is processed using photolithography and ion milling. Next, the BST thin film 16 is processed using photolithography and RIE. Next, the lower Pt electrode film 15 is processed using photolithography and ion milling, and the BST thin film 14 of the adhesion layer is processed using RIE. Next, heat treatment is performed in an oxygen atmosphere at 850 ° C. for 30 minutes.

Next, as shown in FIG. 7H, a 500 nm thick SiN _X layer 20 is formed by sputtering. Next, photosensitive polyimide is applied, exposed, developed and cured to form a pattern having through holes in the polyimide layer 22. Next, using the polyimide layer 22 as a mask, the SiN _X layer is processed using the RIE method, and the SiN _X layer 20 and the polyimide layer 22 having the through holes 24 and 26 through which the Pt electrode films 17 and 15 are exposed are formed. Form.

Next, 100 nm-thick Ti, 2000 nm-thick Ni, and 100 nm-thick Au are deposited by sputtering, and the Au / Ni / Ti is processed using photolithography, ion milling, and RIE. As a result, as shown in FIG. 7 (i), via hole conductors 31 and 33 and external electrodes 30 and 32 filled in the through holes 24 and 26 formed in the SiN _X layer 20 and the polyimide layer 22 are formed. The antifuse element 10b is completed.

  The antifuse element 10b of the fourth embodiment described above has the same operations and effects as the antifuse element 10a of the second embodiment.

  That is, in order to form the protrusion 15a with high accuracy using photolithography, the position of the protrusion 15a can be controlled, and the portion leading to the short is specified at one place. Therefore, quality improvement by failure analysis and non-defective product inspection by shape observation are possible. In addition, it is possible to eliminate variations in resistance values after a short circuit.

  In addition, since the size and tip shape of the protrusion 15a can be controlled and the electric field concentration can be easily controlled, the breakdown voltage (short circuit voltage) can be controlled with high accuracy.

  <Comparative Example> A comparative example will be described with reference to FIG.

  FIG. 8 is a cross-sectional view of the antifuse element 10x of the comparative example. As shown in FIG. 8, the antifuse element 10x of the comparative example is configured in substantially the same manner as the antifuse elements of Examples 1 to 4. That is, an element structure in which the insulator film 16 is sandwiched between the electrode films 15 and 17 is formed on the substrate 12 and is covered with the insulating layer 28. The electrode films 17 and 15 are connected to the external electrodes 30 and 32 via via-hole conductors 31 and 33 that penetrate the insulating layer 28, respectively.

  Unlike the antifuse elements of Examples 1 to 4, the antifuse element 10x of the comparative example has no corners or protrusions on the electrode films 15 and 17. That is, there is no sharp point intentionally formed so that electric field concentration occurs.

  For this reason, the location where the short circuit occurs is not specified, and the current path after the occurrence of the short circuit becomes long as shown by the thick line 50 in FIG. 8B or as shown by the thick line 52 in FIG. 8C. The resistance value after a short circuit varies.

  Further, since the location where the short occurs cannot be identified, it is difficult to improve the quality by failure analysis and to inspect the non-defective product by observing the shape of the specific portion.

  <Summary> In the antifuse elements of Examples 1 to 4 described above, corners and protrusions where electric field concentration occurs are formed in the electrode film. For this reason, it is possible to identify a short-circuited location. Further, the short circuit voltage can be controlled with high accuracy by the shapes of the corners and the protrusions. Furthermore, the corners and the protrusions can be processed simultaneously with the shape processing of the electrode film or by adding a simple process, and the manufacturing cost can be reduced.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

  For example, as an embodiment of the present invention, an antifuse element having a function of short-circuiting by applying a high voltage has been described. However, by adjusting the thickness of the insulator film in the embodiment of the present invention, static electricity is grounded. It can also be used as an ESD suppressor element having a function of releasing. The ESD suppressor element is an element that releases static electricity (instantaneous high voltage) and, unlike an antifuse element, does not cause dielectric breakdown. Therefore, if the insulator film is thickened, it can be applied to an ESD suppressor element.

  The antifuse element of the present invention may be formed integrally with other circuit elements.

It is (a) sectional drawing and (b) top view of an antifuse element. (Example 1) It is sectional drawing which shows the manufacturing process of an antifuse element. (Example 1) It is sectional drawing which shows the manufacturing process of an antifuse element. (Example 1) It is sectional drawing which shows the manufacturing process of an antifuse element. (Example 2) It is sectional drawing which shows the manufacturing process of an antifuse element. (Example 2) It is sectional drawing which shows the manufacturing process of an antifuse element. Example 4 It is sectional drawing which shows the manufacturing process of an antifuse element. Example 4 It is sectional drawing of an antifuse element. (Comparative example) It is sectional drawing of an antifuse element. (Conventional example)

Explanation of symbols

10, 10a, 10b, 10x Antifuse element 12 Substrate 15 Lower electrode film 15a Protrusion 16 Insulator film (BST thin film)
17 Upper electrode film 17a Corner portion 17b Projection portion 22 Insulating layer 24 Insulating layer 30 External electrode 31 Via-hole conductor (leading electrode)
32 External electrode 33 Via-hole conductor (extraction electrode)

Claims (12)

At least a pair of opposing electrode films;
An insulator film disposed between the pair of electrode films;
A substrate supporting the pair of electrode films and the insulator film;
With
When seen through from the film thickness direction, at least one of the pair of electrode films is formed with a sharp corner, and the corner overlaps the other of the pair of electrode films, Antifuse element.   2. The antifuse element according to claim 1, wherein the corner portion is formed only at one position of the one of the pair of electrode films.   The said corner | angular part is arrange | positioned in the intermediate position of the line segment which connects the extraction electrode respectively connected to a pair of said electrode film when it sees through from the film thickness direction. Antifuse element. In the manufacturing method of the antifuse element which manufactures the antifuse element as described in any one of Claims 1 thru | or 3,
A method of manufacturing an antifuse element, including a step of forming the one shape of the pair of electrode films, wherein the corner portion is formed simultaneously in the step.   In the step of forming the shape when the one of the pair of electrode films is seen through from the film thickness direction, the shape when the one of the pair of electrode films is seen through from the film thickness direction using photolithography 5. The method of manufacturing an antifuse element according to claim 4, wherein the corners are simultaneously formed as a part of the antifuse element. At least a pair of opposing electrode films;
An insulator film disposed between the pair of electrode films;
A substrate supporting the pair of electrode films and the insulator film;
With
At least one of the pair of electrode films is formed with a protrusion with a pointed tip protruding to the other side of the pair of electrode films at a portion facing the other of the pair of electrode films via the insulator film An anti-fuse element characterized by being made.   The antifuse element according to claim 6, wherein the protrusion is formed only at the one position of the pair of electrode films. In the manufacturing method of the antifuse element which manufactures the antifuse element of Claim 6 or 7,
Forming a shape corresponding to the protrusion on the surface of the insulator film, which is an interface between the one of the pair of electrode films and the insulator film;
Forming the one of the pair of electrode films on a surface to be the interface where the shape corresponding to the protrusion is formed;
A method for manufacturing an antifuse element, comprising: In the manufacturing method of the antifuse element which manufactures the antifuse element of Claim 6 or 7,
Forming the protrusion on the surface of the one of the pair of electrode films on the interface between the one of the pair of electrode films and the insulator film;
Forming the insulator film on a surface to be the interface on which the protrusion is formed;
A method for manufacturing an antifuse element, comprising: Forming a shape corresponding to the protruding portion on the surface of the insulator film that is an interface with the one of the pair of electrode films using photolithography;
Forming the one of the pair of electrode films on a surface to be the interface where the shape corresponding to the protrusion is formed;
The method for manufacturing an antifuse element according to claim 8, comprising: A step of forming a shape corresponding to the protruding portion on the surface that becomes an interface with the one of the pair of electrode films by the nano-indent method with respect to the insulator film;
Forming the one of the pair of electrode films on a surface to be the interface where the shape corresponding to the protrusion is formed;
The method for manufacturing an antifuse element according to claim 8, comprising: Forming the protrusion using photolithography on the surface of the one of the pair of electrode films on the interface with the insulator film; and
Forming the insulator film on a surface to be the interface on which the protrusion is formed;
The method for manufacturing an antifuse element according to claim 9, comprising:

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