JP2008192972A - Trimming fuse structure and method for forming the same, and trimming fuse trimming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a trimming fuse structure which excels in humidity resistance, its formation method, and a trimming method, without causing complication of a manufacturing process or the increase of manufacturing cost to be generated. <P>SOLUTION: This trimming fuse structure is provided with a first wiring layer 4 that includes fuse sections 11a and 11b formed via a first insulating film 3 on a substrate 1 and a second insulating film 5 covering the first wiring layer 4. A common conductive film deposited on the second insulating film 5 is worked so that a second wiring layer 6 that includes an electrode pattern 6a to be used for electric connection with the outside and the coating pattern 6b, arranged directly above the fuse sections 11a and 11b, can be formed on the second insulating film 5. A protective film 7, covering the second wiring layer 6 and having openings 8a and 8b on the electrode pattern 6a and a coating pattern 6b, is formed on the second wiring layer 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a trimming fuse, and more particularly, to a trimming fuse structure including a fuse portion provided for repairing a defective portion of a semiconductor device or the like and improving a manufacturing yield, a method for forming the trimming fuse, and a trimming fuse trimming method.

  In order to operate a semiconductor device under a certain electrical condition, the semiconductor device is provided with a predetermined standard regarding electrical characteristics. In order to determine whether or not a manufactured semiconductor device satisfies such a standard, the function and performance of the semiconductor device are inspected when the manufacturing process is nearing completion.

  By the way, in general, as the degree of integration increases, many semiconductor devices deviate from a predetermined standard, and the manufacturing yield decreases. However, if all the semiconductor devices that deviate from the predetermined standard are excluded from the highly integrated semiconductor device, the manufacturing cost of the semiconductor device is extremely increased. Many semiconductor devices that deviate from a predetermined standard have defects only in some limited portions. Therefore, in the manufacturing process of the semiconductor device, a repair process is applied in which such defects occurring in some limited places are deleted or adjusted to appropriate values so that the semiconductor device satisfies a predetermined standard. ing. In order to enable such repair processing, fuse technology is generally used.

  As a fuse used in such a fuse technique, there is a trimming fuse. The trimming fuse includes a fuse portion made of wiring or the like constituting a circuit of the semiconductor device. The fuse portion is trimmed by irradiation with an energy beam such as a laser beam. In this case, trimming is fusing (sublimation).

  A trimming fuse mounted on a semiconductor device generally has a structure in which an opening is provided in a protective film deposited as the uppermost layer of the semiconductor device, and a fuse is disposed below the opening. An interlayer insulating film that covers the fuse portion is exposed in the opening. Since the interlayer insulating film is a film that is in direct contact with the wiring, characteristics such as step coverage and dielectric constant are emphasized. For this reason, the interlayer insulating film has lower outside air blocking capability such as moisture resistance than the protective film. Therefore, in the trimming fuse structure described above, the occurrence frequency of corrosion due to the chemical reaction of the ambient atmosphere that has penetrated the interlayer insulating film with the metal wiring around the fuse portion increases. This means that when a trimming fuse is provided, a defect due to the provision of the trimming fuse may occur.

  In recent years, with the increase in integration of semiconductor devices, in particular, the increase in capacity of memory devices, the wiring structure of semiconductor devices has been increasing in number. In a semiconductor device having such a multilayer structure wiring, the total film thickness of an interlayer insulating film or the like deposited on a semiconductor substrate is also increasing. Such an increase in the thickness of the interlayer insulating film suppresses sublimation of the fuse portion when the energy beam is irradiated to the fuse portion arranged in the lower layer, thereby inhibiting the fuse portion from fusing. For this reason, in a semiconductor device having a multilayer wiring, not a wiring mainly composed of polysilicon formed as a wiring layer on a relatively lower layer side of the semiconductor device, but a wiring of a higher layer, that is, aluminum, copper or the like as a main component. Metal wiring is used more as a fuse part.

  The above-described corrosion of the metal wiring through the interlayer insulating film may occur in the fuse part itself that does not need to be trimmed under the situation where the fuse part is configured by metal wiring. If a current is supplied to the fuse portion where such corrosion has occurred, the fuse portion may be disconnected. This is a particularly serious problem because the electrical characteristics of a semiconductor device determined to be non-defective at the end of the manufacturing process fluctuate after shipment.

In order to solve this problem, in Patent Document 1, as shown in FIG. 8, the protective film 107 provided on the uppermost layer of the semiconductor device has a multilayer structure including a lower layer film 107a and an upper layer film 107b. In the opening 108b of the protective film 107, a method is disclosed in which at least the lowermost film 107a is left without being removed. According to this technique, since the fuse part 111 is covered with at least the interlayer insulating film 105 and the lowermost layer film 107a, it is said that moisture resistance can be improved.
JP-A-6-21229

  However, in the semiconductor device, it is necessary to provide an opening 108a through which the electrode pattern 106 is exposed at the bottom in the protective film 107 on the electrode pattern 106 that is electrically connected to the outside. Therefore, in the method disclosed in Patent Document 1, it is necessary to form the opening 108 a and the opening 108 b having different structures in the protective film 107. For this reason, the technique disclosed in Patent Document 1 requires a dedicated mask for leaving the lowermost layer film 107 a of the protective film 107 only in the opening 108 b on the fuse portion 111. Further, a photolithography process and an etching process using the mask are also necessary. In addition, a process of forming the protective film 107 having a multilayer structure is also necessary. That is, the technique disclosed in Patent Document 1 has a problem that the manufacturing process is complicated and a problem that the manufacturing cost increases.

  In view of the above problems, an object of the present invention is to provide a trimming fuse structure excellent in moisture resistance, a method for forming the trimming method, and a trimming method without causing a complicated manufacturing process and an increase in manufacturing cost.

  In order to solve the above-described problems, the present invention employs the following technical means. The trimming fuse structure according to the present invention is a trimming fuse structure including a fuse portion that is blown by an energy beam. The trimming fuse structure includes a first wiring layer including a fuse portion, which is formed on a substrate via a first insulating film, and a second insulating film that covers the first wiring layer. On the second insulating film, a common conductive film deposited on the second insulating film is processed, so that an electrode pattern used for electrical connection to the outside and a position directly above the fuse portion are arranged. A second wiring layer including the provided covering pattern is formed. A protective film that covers the second wiring layer and has an opening on the electrode pattern and the covering pattern is formed on the second wiring layer.

  In this structure, a covering pattern that covers the fuse portion is disposed above the fuse portion. For this reason, the formation of the opening in the protective film on the fuse portion can be simultaneously performed in the step of forming the opening in the protective film on the electrode pattern. In this structure, since the covering pattern is formed, the interlayer insulating film covering the fuse portion is not exposed to the outside air. For this reason, generation | occurrence | production of the corrosion resulting from the external air atmosphere which osmose | permeated the interlayer insulation film can be suppressed.

  In the above configuration, the coating pattern can be made electrically floating. Further, the covering pattern may be configured to be electrically connected to one end of the fuse portion. Furthermore, the coating pattern can be fixed at a specific potential.

  Further, the covering pattern may have a configuration in which one pattern is formed over a plurality of fuse portions, or a configuration in which one covering pattern is formed for each of the plurality of fuse portions.

  The opening of the protective film on the covering pattern is preferably configured to be included in the covering pattern in plan view. Moreover, it is preferable that the opening part on an electrode and the opening part on a coating pattern are formed in the same etching process. The main component of the coating pattern may be a substance that is melted by irradiation with an energy beam such as a laser beam.

  On the other hand, in another aspect, the present invention can provide a method for forming a trimming fuse structure including a fuse portion that is blown by an energy beam. That is, in the method for forming a trimming fuse structure according to the present invention, first, a first insulating film is formed on a substrate. Next, a first wiring layer including a fuse portion is formed on the first insulating film. A second insulating film that covers the first wiring layer is formed on the first wiring layer, and a conductive film is formed on the second insulating film. Then, by processing the conductive film, a second wiring layer including an electrode used for electrical connection with the outside and a covering pattern disposed immediately above the fuse portion is formed. A protective film that covers the second insulating film is formed on the second wiring layer, and an opening is formed in the protective film on the electrode and the covering pattern.

  Furthermore, in another aspect, the present invention is a trimming fuse applied to a trimming fuse structure in which a covering pattern made of a conductor is disposed via an insulating film immediately above a fuse portion blown by an energy beam. A trimming method can be provided. That is, in the trimming method of the trimming fuse according to the present invention, first, the fuse portion and the energy beam irradiation position are aligned. Next, with the alignment, an energy beam such as a laser beam is continuously irradiated a plurality of times. By the energy beam irradiation, the covering pattern and the fuse part are melted, and the fuse part is disconnected. For example, the coating pattern is blown by the first irradiation, and the fuse portion is blown by the second irradiation.

  In this trimming method, multiple times of energy beam irradiation can be performed under the same irradiation conditions. Alternatively, multiple times of energy beam irradiation can be performed with different beam diameters or different energy intensities.

  According to this trimming method, even when a covering pattern is formed on the fuse portion, the fuse portion can be trimmed in substantially the same time as the conventional method.

  According to the present invention, the opening in the protective film on the fuse portion can be formed in the step of forming the protective film on the electrode pattern. That is, a dedicated process or a dedicated mask is not required to form the opening in the protective film on the fuse portion. Therefore, a trimming fuse structure can be realized at low cost. Further, according to the present invention, since the interlayer insulating film covering the fuse portion is not directly exposed to the outside air, the occurrence of corrosion on the fuse portion and the wiring around the fuse portion can be suppressed. Therefore, it is possible to realize a trimming fuse structure having excellent reliability.

  Further, by applying the trimming method of the present invention to the trimming fuse structure, the trimming fuse can be trimmed in the same trimming time as in the prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, the present invention is embodied by an example in which a trimming fuse structure including a fuse portion blown by a laser beam is applied to a semiconductor device.

(First embodiment)
FIG. 1 is a plan view showing a trimming fuse structure and a laser trimming process in the first embodiment of the present invention. 2 is a cross-sectional view taken along line XX in FIG. In FIG. 1 and FIG. 2, an electrode portion used for electrical connection with the outside and a trimming fuse structure are shown side by side. 1 and 2, the right side is the trimming fuse structure 11, and the left side is the electrode portion 12.

  As shown in FIGS. 1A and 2A, the trimming fuse structure 11 of the present embodiment is formed on a semiconductor substrate 1 made of silicon or the like on a region where a semiconductor element such as a transistor is not formed. ing. In addition, two metal wiring layers are formed on the semiconductor substrate 1 via an interlayer insulating film. That is, the first interlayer insulating film 3, the first wiring layer 4, the second interlayer insulating film 5, the second wiring layer 6, and the protective film 7 are sequentially formed from the lower layer. The first wiring layer 4 and the second wiring layer 6 are made of a conductor whose main component is a material that can be melted (sublimated) by laser beam irradiation such as aluminum, copper, gold, platinum, and tungsten. . The material of the first wiring layer 4 and the second wiring layer 6 may be an alloy, and is not limited to a metal, and a conductor such as polysilicon doped with impurities can also be used. An opening 8b is formed at a position immediately above the fuse portion of the protective film 7 in order to facilitate the fusing of the fuse portion as in the prior art.

  In the trimming fuse structure 11 of this embodiment, the fuse portions 11 a and 11 b are configured by wirings 4 a and 4 b belonging to the first wiring layer 4. In FIG. 1A, wirings 4a and 4b located in the opening 8b are fuse portions 11a and 11b. A covering pattern 6b that covers the fuse portions 11a and 11b via the interlayer insulating film 5 is disposed immediately above the fuse portions 11a and 11b. The covering pattern 6 b is made of a conductor that constitutes the second wiring layer 6. Moreover, as shown to Fig.1 (a), the opening part 8b is formed in the state enclosed by the coating pattern 6b in planar view.

  The electrode unit 12 includes an electrode pattern 6 a made of a conductor that constitutes the second wiring layer 6. The upper surface of the electrode pattern 6 a is exposed at the bottom of the opening 8 a provided in the protective film 7. For example, electrical connection between a semiconductor circuit configured on the semiconductor substrate 1 and the outside is realized through the exposed electrode pattern 6a.

The trimming fuse structure 11 as described above is formed as follows.
First, a field oxide film 2 is formed on a semiconductor substrate 1 by a thermal oxidation method or the like. After a semiconductor element such as a transistor is formed in a region of the surface of the semiconductor substrate 1 not shown in FIGS. 1 and 2, a first interlayer insulating film 3 is formed on the entire surface of the semiconductor substrate 1. Here, a BPSG (Boro-Phospho Silicate Glass) film having a thickness of about 700 nm is formed as the first interlayer insulating film 3 by a CVD (Chemical Vapor Deposition) method. On the first interlayer insulating film 3, a first wiring layer 4 whose main component is a conductor such as aluminum is formed. The first wiring layer 4 is formed by applying a well-known photolithography technique and etching technique to the conductor film deposited on the first interlayer insulating film 3 by, for example, sputtering vapor deposition or the like. be able to. Here, the film thickness of the first wiring layer 4 is about 700 nm. The wirings 4a and 4b are formed in this process.

  On the silicon substrate 1 on which the first wiring layer 4 is formed, a second interlayer insulating film 5 that covers the first wiring layer 4 is formed. Here, a TEOS (Tetra Ethyl Ortho Silicate) film having a film thickness of about 1 μm is formed as the second interlayer insulating film 5 by the CVD method. On the second interlayer insulating film 5, a second wiring layer 6 whose main component is a conductor such as aluminum is formed. Similar to the first wiring layer 4, the second wiring layer 6 is well-known with respect to a conductor film made of aluminum or the like deposited on the second interlayer insulating film 5 by, for example, sputtering vapor deposition or the like. The photolithographic technique and the etching technique can be applied. Here, the film thickness of the second wiring layer 6 is about 800 nm. Moreover, the above-mentioned coating pattern 6b and the electrode pattern 6a are formed in the said process.

  A protective film 7 that covers the second wiring layer 6 is formed on the silicon substrate 1 on which the second wiring layer 6 is formed. Here, a silicon nitride film having a thickness of about 1 μm is formed as the protective film 7 by plasma CVD. Then, openings 8a and 8b are formed on the electrode pattern 6a and the covering pattern 6b by applying a known photolithography technique and etching technique. As a result, the upper surface of the electrode pattern 6a is exposed at the bottom of the opening 8a, and the upper surface of the coating pattern 6b is exposed at the bottom of the opening 8b. As shown to Fig.1 (a), the opening part 8a is included in the electrode pattern 6a in planar view. Similarly, the opening 8b is included in the covering pattern 6b in a plan view. Further, as shown in FIG. 2A, the trimming fuse structure 11 of the present embodiment includes the covering pattern 6b, so that the upper layer structure of the second interlayer insulating film 5 is the same as that of the electrode portion 12. Yes. For this reason, the opening 8b on the covering pattern 6b can be formed under the same conditions as those for forming the opening 8a on the electrode pattern 6a. That is, the formation of the opening 8a and the formation of the opening 8b can be simultaneously performed in the same process.

  The first interlayer insulating film 3 is provided with a contact structure for electrically connecting the above-described semiconductor element and the first wiring layer 4, but is not directly related to the present invention. The detailed description here is omitted. Similarly, a contact structure for electrically connecting the first wiring layer 4 and the second wiring layer 6 is formed in the second interlayer insulating film 5, but detailed description thereof is omitted here. ing.

  As described above, in this embodiment, in order to remove the protective film 7 immediately above the fuse portions 11a and 11b, a dedicated process and a dedicated mask are not required, and the opening 8a is formed in the protective film 7 on the electrode pattern 6a. In the step of forming the protective film 7, the protective film 7 immediately above the fuse portions 11a and 11b can be removed. Further, only the covering pattern 6b is exposed in the opening 8b immediately above the fuse portions 11a and 11b, and the interlayer insulating film 5 covering the fuse portions 11a and 11b is not exposed. For this reason, generation | occurrence | production of the corrosion resulting from the external air which permeate | transmitted the interlayer insulation film 5 can be suppressed. Therefore, according to the present embodiment, it is possible to realize a trimming fuse structure having excellent reliability at low cost.

  Next, a trimming method for the trimming fuse structure 11 described above will be described. Here, an example of trimming the fuse portion 11a among the fuse portions 11a and 11b will be described. Note that the laser trimming apparatus that performs the trimming is the same as a known laser trimming apparatus, and thus description thereof is omitted here.

  When trimming the trimming fuse structure 11, first, as shown in FIGS. 1B and 2B, based on the coordinates P1 indicating the fuse portion 11a, the laser beam irradiation position (laser beam position of the laser trimming apparatus). Center) and the fuse portion 11a are aligned. When the alignment is completed, as a first irradiation step, a laser beam having a laser beam diameter d (d is a laser beam diameter) and energy intensity E around the coordinate P1 is irradiated. For example, when the wiring width of the fuse portion 11a (wiring 4a) is 1.0 μm, the laser beam diameter d is about 4.0 μm. In this case, the energy intensity E, which is the total energy irradiation amount of the laser beam having the diameter, can be about 1.4 μJ. As a result, as shown in FIGS. 1C and 2C, the covering pattern 6b in the region corresponding to the laser beam diameter d with the coordinate P1 as the center is melted and removed. At this time, the second interlayer insulating film 5 is exposed at the laser beam irradiation position.

  Next, as shown in FIGS. 1D and 2D, the second irradiation step is performed under the same conditions as the first irradiation step without changing the laser beam irradiation position. That is, the laser beam is irradiated with the laser beam diameter d = 4.0 μm and the energy intensity E = 1.4 μJ around the same coordinate P1. Thereby, as shown in FIGS. 1E and 2E, the second interlayer insulating film 5 and the fuse portion 11a (wiring 4a) in the region corresponding to the laser beam diameter d centered on the coordinate P1. Is removed by fusing, and the first interlayer insulating film 3 is exposed. Thereby, the fuse part 11a will be in a disconnection state.

  In this embodiment, trimming of the fuse portion is performed by irradiating the laser beam twice with the same coordinates. In this case, the labor and man-hours for the laser trimming process do not increase, and the processing time required for trimming is almost the same as in the case of the conventional single irradiation. This is because, in general, in the laser trimming process, most of the processing time is occupied by transport of the semiconductor substrate to be trimmed and alignment for each chip on the semiconductor substrate. That is, the number of times of laser beam irradiation hardly affects the processing time. For example, in the case of a semiconductor substrate having the same diameter and the same number of chips, a semiconductor substrate having a large number of trimming points (a semiconductor substrate having a large distribution of fuse portions to be cut) and a semiconductor substrate having few trimming points (most fuses to be cut) Even when compared with the processing time of a non-semiconductor substrate), each processing time is almost the same. Therefore, as in this embodiment, when performing multiple laser beam irradiations with the same coordinates, trimming can be performed in substantially the same processing time as when the number of laser beam irradiations is one, As a result, there is no cost increase. The number of times of laser beam irradiation at the time of trimming is not limited to two times, and may be three or more times.

  As described above, according to this embodiment, in the step of forming the opening 8a in the protective film 7 on the electrode pattern 6a, the protective film 7 immediately above the fuse portions 11a and 11b can be removed at the same time. Therefore, in order to remove the protective film 7 immediately above the fuse portions 11a and 11b, a trimming fuse structure can be realized without requiring a dedicated process or a dedicated mask. Further, unlike the conventional method, the protective film 7 does not need to have a multilayer structure. Furthermore, only the covering pattern 6b is exposed in the opening 8b immediately above the fuse portions 11a and 11b, and the interlayer insulating film 5 covering the fuse portions 11a and 11b is not exposed. For this reason, generation | occurrence | production of the corrosion resulting from the external air which permeate | transmitted the interlayer insulation film 5 can be suppressed. As a result, a trimming fuse structure having excellent reliability at low cost can be realized.

  In addition, trimming of the fuse portion can be performed in substantially the same processing time as in the prior art, so that the cost does not increase in the trimming process of the trimming fuse structure.

  In the above description, the opening 8b on the covering pattern 6b is formed over the plurality of fuse portions 11a and 11b. However, the shape and number of the openings are not particularly limited as long as the openings are formed on the wirings 4a and 4b constituting the fuse portions 11a and 11b. For example, as shown in FIG. 3A, in a plan view, the cover pattern 6b may be formed only at the center of the cover pattern 6b as long as it is included in the cover pattern 6b. As shown in FIG. 3B, openings 8d and 8e may be formed on the fuse portions 11a and 11b, respectively. In any configuration, the same effect as described above can be obtained.

  In the above description, the case where the covering pattern 6b is in an electrically floating state that is not connected to another conductor pattern has been described. However, the covering pattern 6b can be electrically connected to another conductor pattern. For example, the covering pattern 6b may be connected to one end of the fuse portion 11a or one end of the fuse portion 11b. Further, it may be connected to another conductor pattern to which a ground potential or a power supply potential is applied. Further, the covering pattern 6b may be a pattern integrated with the electrode pattern 6a. In any configuration, since the fuse portions 11a and 11b are covered with the second interlayer insulating film 5 and the covering pattern 6b, corrosion of the fuse portion and the like due to intrusion of moisture or the like from the outside is prevented. . This configuration is effective when, for example, an electrically floating coating pattern cannot be provided due to a change in electrical characteristics of a circuit including a trimming fuse structure.

(Second Embodiment)
In the first embodiment, an example in which one covering pattern is disposed over a plurality of fuse portions has been described. However, a covering pattern may be disposed for each view portion. FIG. 4 is a plan view showing a trimming fuse structure and a laser trimming process in the second embodiment of the present invention. FIG. 5 is a cross-sectional view taken along line YY in FIG. 4 and 5, the electrode portion used for electrical connection with the outside and the trimming fuse structure are shown side by side. 4 and 5, the right side is the trimming fuse structure 21, and the left side is the electrode portion 12. 4 and 5, the same reference numerals are given to the same elements as those of the trimming fuse structure 11 described in the first embodiment.

  As shown in FIGS. 4A and 5A, the trimming fuse structure 21 of the present embodiment has a covering pattern on the fuse portions 11a and 11b, respectively, instead of the covering pattern 6b of the first embodiment. 16a and 16b are disposed. The protective film 7 has openings 18a and 18b included in the covering patterns 16a and 16b, respectively, in plan view.

  This configuration is different only in the pattern on the mask used in the photolithography process for patterning the second wiring layer in the first embodiment and the photolithography process for forming the opening in the protective film 7. Yes, it can be formed in the same process as in the first embodiment. Therefore, in the process of forming the opening 8a on the electrode pattern 6a, the openings 18a and 18b can be formed simultaneously. Further, only the covering patterns 16a and 16b are exposed in the opening 18a immediately above the fuse portion 11a and the opening 18b immediately above the fuse portion 11b, respectively, and the interlayer insulating film 5 covering the fuse portions 11a and 11b is exposed. Not done. For this reason, generation | occurrence | production of the corrosion resulting from the external air which permeate | transmitted the interlayer insulation film 5 can be suppressed. Therefore, also according to this embodiment, a trimming fuse structure having excellent reliability can be realized at low cost.

  Subsequently, a trimming method of the trimming fuse structure 21 described above will be described. Here, an example of trimming the fuse portion 11a among the fuse portions 11a and 11b will be described. Note that, as in the first embodiment, description of the laser trimming apparatus that performs the trimming is omitted.

  When trimming the trimming fuse structure 21, first, in the same manner as in the first embodiment, the laser trimming is performed based on the coordinates P1 indicating the fuse portion 11a as shown in FIGS. 4 (b) and 5 (b). Positioning of the laser beam irradiation position of the apparatus and the fuse portion 11a is performed. When the alignment is completed, as a first irradiation step, a laser beam having a laser beam diameter d and energy intensity E around the coordinate P1 is irradiated. For example, when the wiring width of the fuse portion 11a (wiring 4a) is 1.0 μm, the laser beam diameter d is about 4.0 μm. In this case, the energy intensity E, which is the total energy irradiation amount of the laser beam having the diameter, can be about 1.4 μJ. As a result, as shown in FIGS. 4C and 5C, the coating pattern 16a in the region corresponding to the laser beam diameter d with the coordinate P1 as the center is melted and removed. At this time, the second interlayer insulating film 5 is exposed at the laser beam irradiation position.

  Next, as shown in FIGS. 4D and 5D, the second irradiation step is performed under the same conditions as the first irradiation step without changing the laser beam irradiation position. That is, the laser beam is irradiated with the laser beam diameter d = 4.0 μm and the energy intensity E = 1.4 μJ around the same coordinate P1. As a result, as shown in FIGS. 4E and 5E, the second interlayer insulating film 5 and the fuse portion 11a (wiring 4a) in the region corresponding to the laser beam diameter d centered on the coordinate P1. Is removed by fusing, and the first interlayer insulating film 3 is exposed. Thereby, the fuse part 11a will be in a disconnection state.

  In the present embodiment, the covering patterns 16a and 16b are respectively disposed immediately above the fuse portion 11a and directly above the fuse portion 11b. That is, the covering pattern 16a and the covering pattern 16b are electrically separated. For example, when unintentional fluctuations occur in the laser beam irradiation conditions, a situation may occur in which the covering pattern 16a and the fuse portion 11a are short-circuited with the melted wiring material after the second irradiation step. If such a short circuit occurs when both the fuse part 11a and the fuse part 11b are melted, in the covering pattern 6b of the first embodiment, the fuse part 11a and the fuse part 11b are short-circuited through the covering pattern 6b. become. However, in this embodiment, since the covering pattern 16a and the covering pattern 16b are electrically separated, a short circuit between the covering pattern 16a and the fuse part 11a and between the covering pattern 16b and the fuse part 11b are performed. Even when the short-circuit occurs at the same time, it is possible to prevent the occurrence of a problem that the fuse portion 11a and the fuse portion 11b are short-circuited. As a result, the yield of laser trimming can be further improved as compared with the first embodiment.

  Also in this embodiment, trimming of the fuse portion is performed by irradiating the laser beam twice with the same coordinates. However, as described in the first embodiment, the processing is performed in substantially the same processing time. Therefore, the cost does not increase in the trimming process of the trimming fuse structure. Further, the number of times of laser beam irradiation at the time of trimming is not limited to two, and may be three or more.

  As described above, according to this embodiment, in addition to the effect of the first embodiment, it is possible to obtain an effect that the yield of laser trimming can be further improved.

  In the above description, the case where the covering patterns 16a and 16b are in an electrically floating state that is not connected to other conductor patterns has been described. However, the covering patterns 16a and 16b can be electrically connected to other conductor patterns. For example, the covering pattern 16a may be connected to one end of the fuse portion 11a. Similarly, the covering pattern 16b may be connected to one end of the fuse portion 11b. Further, it may be connected to another conductor pattern to which a ground potential or a power supply potential is applied. Thereby, the effect similar to 1st Embodiment can be acquired.

(Third embodiment)
In the first and second embodiments, the case has been described in which trimming of the trimming fuse structure is performed by laser beam irradiation a plurality of times under the same conditions. However, trimming may be performed by performing laser beam irradiation under different irradiation conditions a plurality of times. FIG. 6 is a plan view showing a process of laser trimming in the third embodiment of the present invention. FIG. 7 is a sectional view taken along line ZZ in FIG. 6 and 7, the trimming for the trimming fuse structure 11 described in the first embodiment will be described. However, the trimming fuse structure 21 described in the second embodiment can also be applied to the trimming. In FIGS. 6 and 7, the same elements as those in the trimming fuse structure 11 described in the first embodiment are denoted by the same reference numerals.

  In the trimming method of the present embodiment, the laser of the laser trimming apparatus has the same capacity as that of the first embodiment and is based on the coordinates P1 indicating the fuse portion 11a as shown in FIGS. 6 (a) and 7 (a). The beam irradiation position is aligned with the fuse portion 11a. When the alignment is completed, a laser beam having a laser beam diameter d and energy intensity E is irradiated 9 around the coordinate P1 as a first irradiation step. For example, when the wiring width of the fuse portion 11a (wiring 4a) is 1.0 μm, the laser beam diameter d is about 6.0 μm. In this case, the energy intensity E can be about 1.4 μJ. As a result, as shown in FIGS. 6B and 7B, the covering pattern 6b in the region corresponding to the laser beam diameter d with the coordinate P1 as the center is melted and removed. At this time, the second interlayer insulating film 5 is exposed at the laser beam irradiation position.

  Next, as shown in FIGS. 6C and 7C, the second irradiation step is performed without changing the laser beam irradiation position. In the present embodiment, the second irradiation step is performed with a laser beam diameter d smaller in diameter than the first irradiation step. That is, the laser beam is irradiated with the laser beam diameter d = 4.0 μm and the energy intensity E = 1.4 μJ around the same coordinate P1. As a result, as shown in FIGS. 6D and 7D, the second interlayer insulating film 5 and the fuse portion 11a (wiring 4a) in the region corresponding to the laser beam diameter d centered on the coordinate P1. Is removed by fusing, and the first interlayer insulating film 3 is exposed. Thereby, the fuse part 11a will be in a disconnection state.

  In the present embodiment, the first irradiation step and the second irradiation step are performed under different conditions. That is, the energy intensity is the same, and only the laser beam diameter is changed so that the laser beam diameter is larger in the first irradiation step than in the second irradiation step. Thus, by setting the laser beam diameter in the first irradiation step to be large, the area of the second interlayer insulating film 5 exposed after the first irradiation step is increased. As a result, when the second irradiation step is performed at the same coordinate P1, the laser beam can reach the fuse portion 11a even if a slight misalignment of the laser irradiation position occurs due to the accuracy of the laser trimming apparatus. Can do. Therefore, according to this embodiment, the yield of laser trimming can be further improved as compared with the trimming methods described in the first and second embodiments.

  In the present embodiment, the trimming of the fuse portion is performed by irradiating the laser beam twice with the same coordinates. However, as described above, the trimming can be performed in substantially the same processing time as the conventional one. In the trimming process of the fuse structure, the cost does not increase.

  As described above, according to the present embodiment, in addition to the effects described in the first or second embodiment, an effect that the yield of laser trimming can be further improved can be obtained.

  In the present embodiment, only the laser beam diameter is changed in the first irradiation step and the second irradiation step. However, any irradiation condition can be adopted as long as the first laser beam irradiation is an irradiation condition that provides a larger opening than the second laser irradiation, that is, the laser beam irradiation to the fuse wiring. For example, the same effect can be obtained by making the energy intensity of the first irradiation step larger than the energy intensity of the second irradiation step. Further, the number of times of laser beam irradiation at the time of trimming is not limited to two, and may be three or more.

  As described above, according to the present invention, the opening in the protective film on the fuse portion can be formed in the step of forming the protective film on the electrode pattern. That is, a dedicated process or a dedicated mask is not required to form the opening in the protective film on the fuse portion. Therefore, a trimming fuse structure can be realized at low cost. Further, according to the present invention, since the interlayer insulating film covering the fuse portion is not directly exposed to the outside air, the occurrence of corrosion on the fuse portion and the wiring around the fuse portion can be suppressed. Therefore, it is possible to realize a trimming fuse structure having excellent reliability.

  Further, by applying the trimming method of the present invention to the trimming fuse structure, the trimming fuse can be trimmed in the same trimming time as in the prior art.

  In addition, this invention is not limited to each embodiment demonstrated above, A various deformation | transformation and application are possible in the range with the effect of this invention. For example, in each embodiment, a laser beam is used as an energy beam for fusing the fuse part. However, any energy beam can be used as long as the fuse part is capable of fusing. For example, an ion beam can be used instead of the laser beam.

  In the above description, the protective film has a single layer structure. However, for example, the protective film may have a multilayer structure such as a silicon oxide film in the lower layer and a silicon nitride film in the upper layer. Also in this case, the opening on the covering pattern can be formed at the same time in the step of forming the opening in the protective film on the electrode pattern. In addition, in the process of forming an opening in the protective film on the electrode pattern, even if the type, material, film thickness, etc. of the protective film are different from the above-mentioned configuration as well as the number of protective film layers, the covering pattern Obviously, the openings can be formed simultaneously.

  INDUSTRIAL APPLICABILITY The present invention can provide a trimming fuse structure having excellent reliability at low cost, and is useful for a device that requires a trimming fuse structure such as a semiconductor integrated circuit device.

The top view which shows the process of trimming fuse structure and trimming in 1st Embodiment of this invention Sectional drawing which shows the process of trimming fuse structure and trimming in 1st Embodiment of this invention The top view which shows the modification of the trimming fuse structure in 1st Embodiment of this invention The top view which shows the trimming fuse structure in 2nd Embodiment of this invention, and the process of trimming Sectional drawing which shows the process of trimming fuse structure and trimming in 2nd Embodiment of this invention The top view which shows the process of the trimming in 3rd Embodiment of this invention. Sectional drawing which shows the process of the trimming in 3rd Embodiment of this invention. Sectional view showing conventional trimming fuse structure and trimming process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Field oxide film 3 1st interlayer insulation film (1st insulation film)
4 1st wiring layer 4a, 4b wiring 5 2nd interlayer insulation film (2nd insulation film)
6 Second wiring layer 6b, 16a, 16b Cover pattern 7 Protective film 8a, 8b, 8c, 8d, 8e, 18a, 18b Opening 9 Laser beam (energy beam)
11, 21 Trimming fuse structure 11a, 11b Fuse part

Claims (13)

A trimming fuse structure including a fuse portion blown by an energy beam,
A first wiring layer including a fuse portion formed on a substrate via a first insulating film;
A second insulating film covering the first wiring layer;
An electrode pattern used for electrical connection to the outside, formed by processing a common conductive film deposited on the second insulating film, and a covering pattern disposed immediately above the fuse portion A second wiring layer including:
A protective film covering the second wiring layer and having an opening on the electrode pattern and the covering pattern;
A trimming fuse structure characterized by comprising:   The trimming fuse structure according to claim 1, wherein the covering pattern is electrically floating.   The trimming fuse structure according to claim 1, wherein the covering pattern is electrically connected to one end of the fuse portion.   The trimming fuse structure according to claim 1, wherein the covering pattern is fixed to a specific potential.   The trimming fuse structure according to claim 1, wherein the opening of the protective film on the covering pattern is included in the covering pattern in a plan view.   The trimming fuse structure according to claim 1, wherein a plurality of the fuse portions are covered with one of the covering patterns.   The trimming fuse structure according to claim 1, wherein each of the plurality of fuse portions is covered with one covering pattern.   The trimming fuse structure according to claim 1, wherein the opening on the electrode pattern and the opening on the covering pattern are formed in the same etching process.   The trimming fuse structure according to claim 1, wherein a main component of the covering pattern is a material that is melted by irradiation with an energy beam. A method for forming a trimming fuse structure including a fuse portion blown by an energy beam,
Forming a first insulating film on the substrate;
Forming a first wiring layer including a fuse portion on the first insulating film;
Forming a second insulating film covering the first wiring layer;
Forming a conductive film on the second insulating film;
Processing the conductive film to form a second wiring layer including an electrode pattern used for electrical connection to the outside and a covering pattern disposed immediately above the fuse portion;
Forming a protective film covering the second wiring layer;
Forming an opening in the protective film on the electrode pattern and the covering pattern;
A method for forming a trimming fuse structure, comprising: A trimming fuse trimming method applied to a trimming fuse structure in which a covering pattern made of a conductor is disposed via an insulating film directly above a fuse portion to be blown by an energy beam,
Aligning the fuse portion and the energy beam irradiation position;
In the state where the alignment has been made, irradiating an energy beam continuously multiple times, fusing the covering pattern and the fuse part, and making the fuse part a disconnected state,
A trimming method for trimming fuses, comprising:   12. The trimming fuse trimming method according to claim 11, wherein the plurality of energy beam irradiations are performed under the same irradiation conditions.   The trimming fuse trimming method according to claim 11, wherein the plurality of energy beam irradiations are performed with different beam diameters or different energy intensities.

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