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`
`(19) Japanese Patent Office (JP)
`(12) Kokai Unexamined Patent Application Bulletin (A)
`(11) Laid Open Patent Application No.
`
`8-213465
`(43) Publication Date
`
`August 20, 1996
`Number of Claims
`
`6 OL
`
`Number of Pages
`
`6
`
`Examination Request
`
`not yet made
`
`
`(51)
`
`
`Int. Cl.6
`H01L 21/82
`H01S 3/00
`
`Identification Code
`
`
`B
`
`
`Internal File No.
`
`
`(21) Application No.:
`
`7-19144
`
`
`
`(71)
`
`Applicant:
`
`(22) Application Date:
`
`February 7, 1995
`
`(72)
`
`Inventor:
`
`
`
`
`
`(74)
`
`Agent:
`
`
`
`
`
`
`(54) [Title of the Invention] SEMICONDUCTOR
`
`
`
`DEVICE
`
`
`
`
`
`
`(57) [Abstract]
`[Object] The present
`to a
`invention relates
`technology for forming a fuse member that is used
`in a semiconductor device, and an object is to
`allow a fuse member to be broken, fully and easily,
`by a laser beam with a relatively small energy,
`without adding special manufacturing processes.
`[Constitution] In a semiconductor device having a
`fuse member 1 that is breakable by a laser beam
`5, the configuration is such that the fuse member is
`provided so that the length L of the fuse member 1
`is, at a maximum, the same size as the diameter D
`of the irradiation spot of the laser beam 5.
`
`Tech. Indic.
`
`
`
` F
`
`FI
`
`
`
`H01L 21/82
`
`000005223
`Fujitsu Ltd.
`4-1-1 Kamiodanaka,
`Nakahara-ku, Kawasaki-shi,
`Kanagawa-ken
`KOYOU, Kazuto
`Fujitsu Ltd.
`4-1-1 Kamiodanaka,
`Nakahara-ku, Kawasaki-shi,
`Kanagawa-ken
`Patent attorney ISHIDA,
`Takashi (and 3 other people)
`
`
`
`
`
`
`
`
`
`
`Fundamental block diagram of the semiconductor
`device according to the present invention
`
`Translation by Patent Translations Inc. 206-357-8508 mail@PatentTranslations.com
`
`7
`
`

`
`JP-08-213465-A (2)
`in a conventional example, where (a) is a plan view and (b)
`is a sectional view along the section B-B' in (a). In the
`figure, 61 is a fuse member that can be broken by a laser
`beam; 62a and 62b are contact holes for electrically
`connecting to the underlying wiring layers at both ends of
`the fuse member 61; 63a and 63b are wiring layers that are
`connected to the fuse member 61 via the respective contact
`holes 62a and 62b; 64 is an insulating layer that is formed
`so as to contain the fuse member 61 and each of the wiring
`layers 63a and 63b; and 65 is a laser beam for breaking the
`fuse member 61.
`[0004] In the configuration that is illustrated, the length L0 of
`the fuse member 61 is much larger than the irradiation spot
`diameter D of the laser beam 65, and the thermal capacity
`is high because of the relatively large volume of the fuse
`member 61. Consequently, when the irradiation energy of
`the laser beam 65 is low, the fuse member 61 will not be
`fully broken, and because of this, some of the broken
`portion of the fuse member 61 will remain, causing a
`problems in so much as leaks occur between the wiring
`layers 63a and 63b, via that portion.
`[0005] While of the irradiation energy of the laser beam 65
`may be increased in order to remediate such problems, this
`gives rise to other problems. That is, when the irradiation
`energy of the laser beam is high, the insulating layer
`underlying the fuse member 61 will fail (insulation failure),
`or the substrate will fail, so that leaks occur between the
`fuse member 61 and other conductors, and thus problems
`may occur such as malfunctions occurring in the ROM
`circuits or the like that use this fuse member, and reduced
`operational reliability of the device as a whole.
`[0006] As a means for solving this type of problem,
`technology is known wherein, for example, an insulating
`layer is provided with a protruding portion directly under the
`fuse breaking part (see FIG. 1 in JP-03-019255-A, for
`example). With this technology there is an advantage in so
`much as the volume of the insulating layer in the portion
`directly under the fuse breaking part is relatively large as
`compared to portions other than the portion directly below,
`such that failure of the insulating layer can be prevented,
`even if the fuse breaking part is irradiated with a relatively
`high energy laser beam.
`[0007]
`
`[Claims]
`[Claim 1] In a semiconductor device having a fuse member
`(1) that is breakable by a laser beam (5), the semiconductor
`device characterized in that the fuse member is provided so
`that the length (L) of the fuse member (1) is, at a maximum,
`the same size as the diameter (D) of the irradiation spot of
`the laser beam 5.
`[Claim 2] A semiconductor device as set forth in Claim 1,
`characterized by further having an insulating layer (4)
`formed so as to contain the fuse member, wherein the fuse
`member is electrically connected, at both ends of the fuse
`member, to underlying wiring layers (3a and 3b) via contact
`holes (2a and 2b) provided in the insulating layer.
`[Claim 3] A semiconductor device as set forth in Claim 2,
`characterized in that a fuse member is provided such that
`the area of a plane section of conductive material (10a,
`10b) in the contact holes that connect the fuse member (10)
`with the underlying wiring layers (11a and 11b) is smaller
`than the area of the breaking section of the fuse member.
`[Claim 4] A semiconductor device as set forth in Claim 2,
`characterized in that, in the case of a buried contact
`structure (21a and 21b) for the contact holes at both ends
`of the fuse member (20), the thermal resistance (RTH2) of
`the conductive material in the contact hole is selected so as
`to be higher than the thermal resistance (RTH1) of the fuse
`member.
`[Claim 5] A semiconductor device as set forth in Claim 2,
`characterized in that the underlying wiring layer of the fuse
`member (30) has a multilayer wiring structure (32a, 32b,
`34a, 34b, 36a, 36b), and the contact holes that connect the
`fuse member with the underlying wiring layers have a
`buried contact structure (31a, 31b, 33a, 33b, 35a, 35b).
`[Claim 6] A semiconductor device as set forth in Claim 2,
`characterized in that the underlying wiring layer of the fuse
`member (40) has a multilayer wiring structure (42a, 42b,
`44a, 44b, 46a, 46b), and the contact holes that connect the
`fuse member with underlying wiring layers have a buried
`contact structure (41a, 41b, 43a, 43b, 45a, 45b), and are
`provided in a positionally overlapping manner.
`[Detailed Description of the Invention]
`[0001]
`[Field of Use in Industry] The present invention relates to
`semiconductor devices, and in particular, relates to a
`technology for forming fuse members suitable for easily
`breaking fuse materials used, for example, in redundant
`circuit parts in semiconductor devices. In recent years, with
`increasing integration, the circuit scale of semiconductor
`hardware, as serving as devices, is increasingly large,
`resulting in an increased likelihood that faults will be
`present in the circuits. Thus, a remedy for faulty parts, using
`redundancy techniques, is an important problem to be
`solved.
`[0002] In this case, as means for storing data for
`redundancy, ROM circuits are generally used that use fuse
`elements. Among such fuse elements, laser fuses (fuse
`members that can be broken using a laser beam), which
`are particularly useful for increasing integration, are often
`used. In this case, the ratio at which the laser fuses can be
`successfully broken (that is, the break yield) has a large
`impact on the product yield, and there is a demand for laser
`fuses that have excellent break yields.
`[0003]
`[Prior Art] FIG. 6 illustrates the configuration of a laser fuse
`
`Translation by Patent Translations Inc. 206-357-8508 mail@PatentTranslations.com
`
`8
`
`

`
`[Problem to Be Solved by the Present Invention]
`However, even with technology such as described above,
`wherein the insulating layer was provided with a protruding
`portion in the portion directly under the fuse breaking part,
`the volume of the fuse member itself was still large, and
`thus still had a large thermal capacity. Consequently, the
`problem was that the fuse could not be broken with
`sufficient ease, without using a laser beam with a high
`irradiation energy.
`[0008] Furthermore, there was a drawback in that a special
`manufacturing process was needed in order to form the
`protruding portion in the insulating layer. The present
`invention was created as a reflection of such problems in
`the prior art, and an object thereof is to provide a
`semiconductor device having a fuse member that can be
`fully and easily broken by a laser beam with a relatively
`small energy, without adding a special manufacturing
`process.
`[0009]
`[MEANS FOR SOLVING THE PROBLEM] FIG. 1 illustrates
`the fundamental configuration of a semiconductor device
`according to the present invention, where (a) is a plan view
`illustrating the configuration of the key elements (the fuse
`member and the wiring layer) in the present device; and (b)
`is a sectional view along the section of A-A' in (a). In the
`figure, 1 indicates a fuse member (length L) that can be
`broken by a laser beam; 2a and 2b indicate contact holes
`for electrically connecting to the underlying wiring layers at
`both ends of the fuse member 1; 3a and 3b indicate wiring
`layers that are connected to the fuse member 1 via the
`respective contact holes 2a and 2b; 4 indicates an
`insulating layer that is formed so as to contain the fuse
`member 1 and the wiring layers 3a and 3b; and 5 indicates
`a laser beam (irradiation spot diameter D) for breaking the
`fuse member 1.
`[0010] Note that while, for simplicity in the illustration, the
`insulating layer 4 is shown as one element, but in the actual
`manufacturing process, in the stages surrounding the
`formation processing for the wiring layers, and in the stages
`surrounding the formation processing for the fuse member,
`these are, on each occasion, formed so as to be "laminar"
`and thus these actually comprise a plurality of laminar
`elements. In the semiconductor device according to the
`present invention, as illustrated in FIG. 1(a), the fuse
`member 1 is provided such that the length L thereof will be
`of a size equal to or less than the diameter D of the laser
`beam 5 of the irradiation spot (L (cid:148) D).
`[0011] Furthermore, the fuse member 1 is electrically
`connected to the underlying wiring layers 3a and 3b via the
`contact holes 2a and 2b, provided in the insulating layer 4
`at both ends of the fuse member 1.
`[0012]
`[Action] With the configuration of the semiconductor device
`according to the present invention, the fuse member 1 is
`configured so as to be, at a maximum, a size equal to the
`irradiation spot diameter D of the laser beam 5, making it
`possible to minimize the thermal capacity by minimizing the
`volume of the fuse member 1.
`[0013] Accordingly, without adding special added
`manufacturing processes, as was seen conventionally,
`the fuse member 1 can be broken fully and easily, even if
`using a laser beam with a relatively low energy is used.
`Furthermore, because the fuse member 1 is electrically
`
`JP-08-213465-A (3)
`connected to the underlying wiring layers 3a and 3b via the
`contact holes 2a and 2b, at both ends thereof, an apparent
`protruding portion (portion indicated by P in FIG. 1 (b)) can
`be formed in the insulating layer under the portion of the
`fuse member 1 that is to be broken.
`[0014] This makes
`the
`to eliminate
`it possible
`disadvantages seen conventionally (that is, the problem of
`circuit malfunctions, and hence
`lowered operational
`reliability, due to failure of the insulating layer under the
`fuse breaking part when a laser beam with a relatively high
`energy is used on this breaking part).
`[0015]
`[Embodiments] Preferred embodiments of the present
`invention will be described below while referring to FIG. 1 to
`FIG. 5. FIG. 2 schematically illustrates the key parts of a
`semiconductor device according to a first embodiment of
`the present invention, which is to say the configuration of
`the laser fuse in the form of a sectional view. In the figure,
`10 indicates a fuse member; 11a and 11b indicate wiring
`layers underlying the fuse member 10; and 12 indicates an
`insulating layer that is formed so as to contain the fuse
`member 10 and the wiring layers 11a and 11b, wherein, as
`with the insulating layer 4 shown in FIG. 1 (b), this
`insulating layer 12 actually comprises a plurality of laminar
`elements.
`[0016] The fuse member 10 is made from, for example,
`titanium (Ti), aluminum (Al), titanium nitride (TiN), or
`polysilicon. In the present embodiment, the irradiation spot
`diameter D of the of the laser beam for breaking the fuse is
`selected to be approximately 5 µm, and this must be
`formed so that the length L of the fuse member 10 is at
`most 5 µm. Furthermore, 10a, 10b indicate portions that are
`formed from conductive material, and are features of the
`present embodiment; as illustrated in FIG. 2, the sectional
`areas of the portions 10a, 10b are selected to be smaller
`than the area of the breaking section of the fuse member
`10. That is to say, by reducing the coverage rate of the
`conductive member portions 10a, 10b,
`the
`thermal
`resistance of the contact part is increased relative to that of
`the fuse member 10.
`[0017] Note that these portions 10a, 10b are formed from
`the same material as the fuse member 10 in the present
`embodiment but other materials may be used so long as
`they are electrically conductive materials. In this case,
`electrically conductive materials are preferably selected that
`have thermal resistances that are as great as possible.
`Furthermore,
`in
`the actual process,
`the electrically
`conductive material portions 10a, 10b are formed on the
`inner peripheral faces of the contact holes that are formed
`for making contact with the respective underlying wiring
`layers 11a and 11b (not shown in FIG. 2). After these
`electrically conductive material portions have been formed,
`the insulating layer 12 is formed covering the contact holes,
`as illustrated.
`[0018] In addition to the actions and effects set forth in
`relation to FIG. 1 (a) and (b), the configuration according to
`the first embodiment achieves the following advantages.
`That is to say, in the present embodiment, the sectional
`areas of the electrically conductive material portions 10a,
`10b in the contact holes at both ends of the fuse member
`10
`
`Translation by Patent Translations Inc. 206-357-8508 mail@PatentTranslations.com
`
`9
`
`

`
`are smaller than the sectional breaking area of the fuse
`member 10, causing the thermal resistance of the contact
`part to be relatively large, thus making it difficult for the heat
`that is produced in the fuse member 10 by the laser beam
`that irradiates the fuse breaking part to propagate to the
`wiring layers 11 a and 11b.
`[0019] The result is that it is possible for the irradiation
`energy of the laser beam to be effectively concentrated only
`in the fuse member 10 portion. This makes it possible to
`break the fuse member 10, fully and easily, using a laser
`beam of a lower energy. FIG. 3 schematically illustrates, in
`the form of a sectional view, the configuration of a laser
`fuse in a second embodiment of the present invention.
`[0020] In the figure; 20 indicates a fuse member, 21a and
`21b indicate contact holes; 22a and 22b indicate wiring
`layers; and 23 indicates an insulating layer comprising a
`plurality of laminar elements. A feature of the present
`embodiment resides in the contact holes 21a and 21b that
`connect the fuse member 20 with the underlying wiring
`layers 22a and 22b having a so-called "buried contact
`structure." With a buried contact structure it is possible to
`select different material properties for
`the electrically
`conductive material that fills the contact holes than for the
`material properties of the fuse member 20.
`[0021] In the present embodiment, the thermal resistance
`RTH2 of the material for filling the contact holes 21a and 21b
`is selected so as to be higher than the thermal resistance
`RTH1 of the fuse member 20. For example, tungsten (W),
`titanium (Ti), titanium nitride (TiN), or the like, may be used
`for the filling material. In addition to the actions and effects
`set forth in relation to FIG. 1 (a) and (b), the configuration
`according to the second embodiment achieves the following
`advantages.
`[0022] That is to say, because the thermal resistance RTH2
`of the material for filling the contact holes 21a and 21b is
`higher than the thermal resistance RTH1 of the fuse member
`20, the thermal resistance of the contact part is relatively
`large, making it possible to achieve an effect equivalent to
`that in the first embodiment as illustrated in FIG. 2.
`Furthermore, using materials having higher boiling points
`as the filling materials for the contact holes 21a, 21b makes
`it possible to minimize damage to the underlying layer
`portions when breaking the fuse.
`[0023] FIG. 4 schematically illustrates, in the form of a
`sectional view, the structure of a laser fuse in a third
`embodiment of the present invention. In the figure, 30 is a
`fuse member; 31a, 31b, 33a, 33b, 35a and 35b are
`contact holes; 32a, 32b, 34a, 34b, 36a, and 36b are wiring
`layers; and 37 is an insulating layer comprising a plurality of
`laminar elements.
`[0024] A feature of the present embodiment resides in the
`"buried contact structure" for the contact holes, similar to
`that in the second embodiment, illustrated in FIG. 3, and
`employing a multilayer wiring layer (three layers in the
`present embodiment). In this case, only the lowest of the
`wiring layers 36a and 36b are connected to respective
`circuit blocks (not shown) via the fuse member 30, and the
`other wiring layers (wiring materials) 32a, 32b, 34a and 34b
`are provided in order to facilitate breaking of the fuse
`member 30.
`[0025] In addition to the actions and effects described in
`relation to FIG. 1 (a) and (b), the configuration according to
`the third embodiment achieves the following advantages.
`
`JP-08-213465-A (4)
`That is to say, in the present embodiment, the thermal
`resistance of the materials that fill the contact holes is
`higher than the thermal resistance of the fuse member 30,
`making it possible to achieve the same effect as in the
`second embodiment, illustrated in FIG. 3.
`[0026] Furthermore, because the actual wiring layers 36a
`and 36b are disposed at as low a layer as possible (in the
`present embodiment, the lowest layer), it is possible to
`further reduce the damage that is done to the wiring layers
`36a and 36b when breaking the fuse with the laser beam.
`FIG. 5 schematically illustrates, in the form of a sectional
`view,
`the configuration of a laser
`fuse
`in a fourth
`embodiment of the present invention.
`[0027] In the figure; 40 indicates a fuse member; 41a, 41b,
`43a, 43b, 45a and 45b indicate contact holes; 42a,42b,
`44a,44b, 46a, and 46b indicate wiring layers; and 47 is an
`insulating layer comprising a plurality of laminar elements. A
`feature of the present embodiment resides in a so called
`"stacked contact" structure, wherein the contact holes
`positionally overlap, when using the multilayer wiring layer
`(three layers in the present embodiment) for the buried
`contact structure, similar to that in the third embodiment,
`illustrated in FIG. 4.
`[0028] In addition to the actions and effects set forth in
`relation to FIG. 1 (a) and (b), the configuration