Multi'fing MULTILING CORPORATION
`
`180 NORTH UNIVERSITY AVE.
`Suite 600
`PROVO, UT 84601 -4474
`
`VOICE (801) 377-2000
`FAX (801) 377-7085
`
`TRANSLATOR’S CERTIFICATE OF TRANSLATION
`
`Translation from Japanese to English
`MultiLing Project Number: GBPLC1710001HQ-S
`Client: Greenblum & Bernstein, P.L.C.
`
`MultiLing Corporation, a Delaware corporation, which has its principal office at 180 North
`University Avenue, Suite 600, Provo, UT 84601-4474, USA, certifies that
`
`(a) it is a professional translation company of multiple languages including Japanese and
`English;
`(b) it has translated from the original document to the translated document identified below,
`and t0 the best of its knowledge, information, and belief the translation of that document is
`accurate as a publication quality translation; and further,
`(0) these statements were made with the knowledge that willful false statements and the like
`so made are punishable by fine or imprisonment, or both, under Section 1001 of Title 18
`of the United States Code.
`
`Original Document Identifier: Awaya (1998) (03005811); JPH08250596A (03005939);
`JPH09293690A (03002312); JPH10125627A (03005938); JPH10256256A (03002313).
`Translated Document
`Identifier: Awaya (1998)
`(O3005811)_en-US; JPH08250596A
`(03 00593 9)_en—US; JPH09293 690A (03002312)_en-US; JPHI 0 1 25 627A (0300593 8)_en-
`US; JPH10256256A (03002313)_en-US.
`
`Signed this 10th day of February 2017.
`
`kg;
`
`Michael Degn, VP at es
`
`eting
`
`ACKNOWLEDGMENT BEFORE NOTARY
`
`State of Utah
`
`County of Utah
`
`}ss.
`
`On this 10th day of February, 2017 before me, the undersigned Notary Public, personally appeared Michael Degn, who
`proved on the basis of satisfactory evidence to be the person whose name is subscribed to this Translator’s Certificate
`of Translation and who acknowledged that he or she executed the same for the purposes stated therein.
`IN WITNESS WHEREOF, I hereunto set my hand and official seal.
`f
`
`‘I‘1.J._
`
`
`otary b ic, resiing at
`DIXIE CALKINS
`-. Notary Public. State of Utah
`
`Commission #671163
`My Commission Expires
`October 09, 2017
`
`
`
`
`
`
`e l, UT
`
`Page 1 01:24
`
`IP Bridge Exhibit 2025
`
`TSMC v. IP Bridge
`
`|PR2016-01249
`
`Page 1 of 24
`
`IP Bridge Exhibit 2025
`TSMC v. IP Bridge
`IPR2016-01249
`
`

`

`(19) Japan Patent Office (JP) (12) JAPANESE UNEXAMINED
`PATENT APPLICATION
`PUBLICATION (A)
`
`(11) Patent Application Disclosure No.
`JPA H10-125627
`
`(43) Publication Date: May 15, 1998 (Heisei 10)
`
`(51) Int. Cl.6
`H01L
`21/285
`
`
`C23C
`14/06
`
`14/34
`H01L
`
`
`Ident. Code
`301
`
`
`
`
`
`
`
`
`
`
`
`
`FI
`H01L
`
`C23C
`
`H01L
`
`
`
`
`21/285
`
`14/06
`14/34
`21/203
`
`
`301R
`S
`A
`S
`S
`
`
`
`(21) Application No.
`
`JPA H8-282211
`
`(22) Date of Filing:
`
`October 24, 1996 (Heisei 8)
`
`(71) Applicant: 000005223
`Fujitsu Limited
`Kamikodanaka 4-1-1, Nakahara-ku,
`Kawasaki-shi, Kanagawa-ken
`
`Examination Request: Not Yet No. of Claims: 23 OL (Total 14 pages)
`
`(71) Applicant: 000237617
`Fujitsu VLSI Limited
`Kouzouji-cho 2-1844-2, Kasugai-shi,
`Aichi-ken
`Tatsuya Inoue
`Kouzouji-cho 2-1844-2, Kasugai-shi,
`Aichi-ken
`Fujitsu VLSI Limited
`Tadahiko Itou
`
`(72) Inventor:
`
`(74) Agent:
`
`Diagram describing the principles of the present invention
`schematically illustrating the hysteresis in FIG. 2.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`(54) [Title of Invention] METHOD FOR FABRICATING
`SEMICONDUCTOR DEVICE AND METHOD FOR
`FORMING HIGH MELTING POINT NITROGEN FILM
`
`(57) Abstract
`[Problem] To provide a method for fabricating a semiconductor
`wherein a fine, low resistance TiN diffusion barrier layer can be
`formed with high through-put by Ti reactive sputtering.
`[Resolution Means] After depositing a TiN film under first
`conditions wherein TiN can be surely sputtered using a Ti target,
`continually perform TiN sputtering under second condition
`wherein Ti is generally sputtered using the same Ti target.
`
`
`
`
`
`
`Page 2 of 24
`
`

`

`(2)
`
`Specification
`Title of the Invention: METHOD FOR FABRICATING SEMICONDUCTOR DEVICE
`AND METHOD FOR FORMING HIGH MELTING POINT NITROGEN FILM
`
`[DETAILED DESCRIPTION OF THE INVENTION]
`[0001]
`[Technical Field of the Invention] The present invention relates to the general
`
`fabrication of a semiconductor device, and more particularly relates to a method for
`fabricating a semiconductor device including a metalization step.
`
`In regards to the fabrication of semiconductors, a metalization step is necessary in
`which wiring made up of Al or an Al alloy is connected to a semiconductor device
`formed in a semiconductor substrate.
`
`Generally, this metalization step is performed using a sputtering method.
`[0002]
`[Conventional Art] In a general fabrication process of a Si semiconductor device,
`
`a diffusion barrier layer such as TiW, TiC, TiN or the like is provided between a wiring
`pattern made up of Al or Al alloy and a connection region formed in a Si substrate that
`connects this wiring pattern prior to the metalization step of this wiring pattern, the Al in
`the Al wiring diffuses in the Si substrate in the connection region, preventing, for
`example, the formation of an alloy spike breaking through a thin diffusion region.
`[0003]
`Generally, when forming a diffusion barrier layer with TiN, a Ti target is used,
`
`and a TiN film is formed by carrying out sputtering in an N2 atmosphere, or in other
`words, a so-called reactive sputtering method is used.
`
`It is possible to form the TiN film by sputtering directly using a TiN target, but
`there are the problems of the thickness of the TiN film formed on the substrate
`becoming too thick, and being easy to strip off when a TiN target is used, so sputtering
`using a TiN target is generally not used.
`
`Because the diffusion barrier layer is formed on a connection region that connects the
`semiconductor device to the wiring pattern, it is desirable for it to have low electric
`resistance, and have high density to act as an effective diffusion barrier layer.
`[0004]
`Furthermore, the TiN film is widely used as a so-called glue layer when causing
`
`a W layer to grow, or as an antireflection film on the Al wiring, and it is requested that
`corrosion due to WF6 supplied as a W layer vapor raw material is small particularly
`when using as a glue layer of the W layer.
`
`For this same reason, it is also requested that the TiN film has high density.
`[0005]
`[Problem to be Solved by the Invention] However, in a reactive sputtering
`
`method using a conventional Ti target, conditions for the TiN film to be stably formed
`are extremely limited, and it was difficult to quickly form a desirable TiN film with low
`resistance and high density as a diffusion barrier.
`[0006]
`Generally, when forming a TiN diffusion barrier layer with a sputtering method,
`
`sputtering is first performed on a dummy substrate, and impurities on the Ti target are
`removed to clean the Ti target prior to sputtering.
`
`Page 3 of 24
`
`

`

`(3)
`
`However, the phenomenon of reactive sputtering is not yet sufficiently explained,
`
`and for example, when conventionally using a pure Ti target that has been cleaned in this
`manner for sputtering the TiN diffusion barrier layer, there were problems such as the
`conditions for TiN being formed on the substrate being substantially limited.
`[0007] More specifically, reactive sputtering of TiN is generally carried out in a mixed
`gas plasma of Ar and N2, but TiN is not formed when the amount of Ar in the plasma is
`large, and the ratio of N2 is small.
`
`In comparison, TiN is easily formed when the ratio of N2 in the mixed gas
`atmosphere is increased, but characteristics demanded in a diffusion barrier layer are
`often not met, such as having low density and high resistance, and the scope of optimal
`sputtering conditions (mixed gas composition, sputtering power and the like), wherein a
`TiN layer suitable for a diffusion barrier layer can be obtained, is limited.
`
`TiN is a non‐stoichiometric compound expressed by TiNx, but when there is a
`lot of N2 in the plasma, a low density, rough-textured TiN film is formed made up of
`TiN crystals in which the large particles have been <111> oriented.
`
`In comparison to this, when N2 in the plasma is reduced, and the ratio of Ti in
`the TiN structure is increased, a fine-textured TiN film made up of uniform TiN
`crystals in which the small particles have been <200> oriented.
`
`Additionally, the fine-textured TiN film obtained in this manner has a surface
`with favorable flatness.
`
`However, as described earlier, when the plasma composition is set so that the
`ratio of N2 is less, there is a possibility of TiN not forming.
`[0008]
`Furthermore, it is known that a high density TiN film suitable for a diffusion
`
`barrier can be obtained by making the plasma power larger when plasma sputtering on
`TiN, but TiN cannot be obtained when the plasma power is made larger unless the ratio
`of N2 in the plasma is increased.
`
`However, as described earlier, a TiN film formed in these conditions has the
`problems of having low density and high electric resistance.
`[0009] In light of the above, a general object of the present invention is to provide a
`method for fabricating a new and useful semiconductor device.
`
`A more specific object of the present invention is to provide a method for
`fabricating a semiconductor device including a reactive sputtering step of a TiN
`diffusion barrier layer, with a larger scope of optimal sputtering conditions wherein a
`TiN film having exceptional film properties as a diffusion barrier film can be obtained.
`[0010]
`[Means for Solving the Problem] In light of the above, the present invention solves
`
`the above problems by, as described in claim 1, a method for fabricating a semiconductor
`device including a step for forming a high melting point metal nitride film by reactive
`sputtering, wherein the reactive sputtering step is made up of (A) a first step that has a high
`melting point metal nitride film sputtered on a substrate using a high melting point metal
`target under a first sputtering condition wherein reactive sputtering of high melting point
`metal nitride occurs even if a high melting point metal target is used, and (B) a second step
`after the step (A) that has a high melting point metal nitride film sputtered on the high
`melting point metal nitride film using the high melting point metal target under a second
`sputtering condition wherein reactive sputtering of high melting point metal nitride does not
`
`Page 4 of 24
`
`

`

`(4)
`
`occur even if a high melting point metal target is used, or as described in claim 2, by the
`method for fabricating a semiconductor device according to claim 1, wherein the high
`melting point metal target used in the step (A) is made up of pure Ti, or as described in claim
`3, by the method for fabricating a semiconductor device according to claim 1 or 2, including
`a cleaning step for cleaning the high melting point metal target by performing sputtering
`under a condition wherein high melting point metal is sputtered in a same reaction room
`wherein the steps (A) and (B) are executed, prior to the step (A), or as described in claim 4,
`by the method for fabricating a semiconductor device according to any one of claims 1 to 3,
`wherein the step (B) follows the step (A), and is executed in the same reaction room without
`breaking the decompression environment, or as described in claim 5, by the method for
`fabricating a semiconductor device according to any one of claims 1 to 3, wherein after the
`step (A), the reactive sputtering step is suspended until the step (B) is started, or as described
`in claim 6, by the method for fabricating a semiconductor device according to any one of
`claims 1 to 5, wherein in the first sputtering condition, a first plasma power is charged
`wherein reactive sputtering of high melting point metal nitride occurs even if a high melting
`point metal target is used, and in the second sputtering condition, a higher second plasma
`power is charged wherein reactive sputtering of high melting point metal nitride does not
`occur when a high melting point metal target is used, or as described in claim 7, by the
`method for fabricating a semiconductor device according to any one of claims 1 to 6, wherein
`in the first sputtering condition, N2 partial pressure of the reaction room wherein reactive
`sputtering is executed is set to a first value wherein reactive sputtering of high melting point
`metal nitride occurs even if a high melting point metal target is used, and in the second
`sputtering condition, is set to a lower second value wherein reactive sputtering of high
`melting point metal nitride does not occur when a high melting point metal target is used, or
`as described in claim 8, by the method for fabricating a semiconductor device according to
`any one of claims 1 to 7, wherein in the step (B), high melting point metal nitride is formed
`on the surface of the high melting point metal target, or as described in claim 9, by the
`method for fabricating a semiconductor device according to any one of claims 1 to 8, wherein
`the step (A) includes a step for depositing an insulation film on the substrate, and a step for
`forming a contact hole in the insulation film so that an active region in the substrate is
`exposed, and the deposition of high melting point metal nitride in the step (A) is executed so
`that the high melting point metal nitride film electrically contacts the active region in the
`contact hole on the insulation film, or as described in claim 10, by the method for fabricating
`a semiconductor device according to claim 9, wherein the step (A) further includes a step for
`depositing a high melting point metal film on the insulation film prior to the deposition of the
`high melting point metal nitride film on the insulation film so that the high melting point
`metal film contacts the active region, and the step for depositing the high melting point metal
`nitride film in the step (A) follows the step for depositing the high melting point metal film,
`and is executed in the same reaction room without breaking a decompression environment, or
`as described in claim 11, by the method for fabricating a semiconductor device according to
`claim 10, wherein the step for depositing the high melting point metal film is executed under
`a different deposition condition than the deposition step of the high melting point metal
`nitride film in the step (A), or as described in claim 12, by the method for fabricating a
`semiconductor device according to claim 11, wherein the step for depositing the high melting
`point metal film is executed in a same composition of plasma gas with the deposition step of
`the high melting point metal nitride film in the step (A), but with a different plasma power, or
`
`Page 5 of 24
`
`

`

`(5)
`
`as described in claim 13, by a method for forming a high melting point metal nitride film
`forming a high melting point metal nitride film by a reactive sputtering step, wherein the
`reactive sputtering step is made up of (A) a first step that has a high melting point metal
`nitride film sputtered on a substrate using a high melting point metal target under a first
`sputtering condition wherein reactive sputtering of high melting point metal nitride occurs
`even if a high melting point metal target is used, and (B) a second step after the first step (A)
`that has a high melting point metal nitride film sputtered on the high melting point metal
`nitride film using the high melting point metal target under a second sputtering condition
`wherein reactive sputtering of high melting point metal nitride does not occur when a high
`melting point metal target is used, or as described in claim 14, by the method for producing a
`high melting point metal nitride film according to claim 13, wherein the high melting point
`metal target used in the step (A) is made up of pure Ti, or as described in claim 15, by the
`method for producing a high melting point metal nitride film according to claim 13 or 14,
`comprising a cleaning step for cleaning the high melting point metal target by performing
`sputtering under a condition wherein high melting point metal is sputtered in a same reaction
`room wherein the steps (A) and (B) are executed, prior to the step (A), or as described in
`claim 16, by the method for producing a high melting point metal nitride film according to
`any one of claims 13 to 15, wherein the step (B) follows the step (A), and is executed in the
`same reaction room without breaking the decompression environment, or as described in
`claim 17, by the method for producing a high melting point metal nitride film according to
`any one of claims 13 to 15, wherein after the step (A), the reactive sputtering step is
`suspended until the step (B) is started, or as described in claim 18, by the method for forming
`a TiN film according to any one of claims 13 to 17, wherein in the first sputtering condition,
`a first plasma power is charged wherein reactive sputtering of high melting point metal
`nitride occurs even if a high melting point metal target is used, and in the second sputtering
`condition, a higher second plasma power is charged wherein reactive sputtering of high
`melting point metal nitride does not occur when a high melting point metal target is used, or
`as described in claim 19, by the method for producing a high melting point metal nitride film
`according to any one of claims 13 to 18, wherein in the first sputtering condition, N2 partial
`pressure of the reaction room wherein reactive sputtering is executed is set to a first value
`wherein reactive sputtering of high melting point metal nitride occurs even if a high melting
`point metal target is used, and in the second sputtering condition, is set to a lower second
`value wherein reactive sputtering of high melting point metal nitride does not occur when a
`pure high melting point metal target is used, or as described in claim 20, by the method for
`producing a high melting point metal nitride film according to any one of claims 13 to 19,
`wherein in the step (B), high melting point metal nitride is formed on the surface of the high
`melting point metal target, or as described in claim 21, by a semiconductor device including a
`first high melting point metal nitride film formed on a substrate, a second high melting point
`metal nitride film formed on the first high melting point metal nitride film, and a conductor
`film formed on the second high melting point metal nitride film, wherein the second high
`melting point metal nitride film has lower electrical resistance than the first high melting
`point metal nitride film, or as described in claim 22, by the semiconductor device according
`to claim 21, wherein the high melting point metal nitride film has a specific resistance of
`approximately 85 Ωcm or more, and the second high melting point metal nitride film has a
`specific resistance of approximately 85 Ωcm or less, or as described in claim 23, by the
`semiconductor device according to claim 21 wherein the first high melting point metal nitride
`
`Page 6 of 24
`
`

`

`(6)
`
`film contacts a diffusion region on the substrate, and the first and second high melting point
`metal nitride films form a diffusion barrier layer.
`[0011]
`Below, the principles of the present invention will be described with reference to
`
`FIG. 1 and FIG. 2.
`
`As illustrated in FIG. 1, in a reactive sputtering test of a TiN film using a Ti target,
`the inventors of the present invention discovered that in a diagram expressing a sputtering
`atmosphere, or in other words, plasma composition plotting N2 flow amount on the vertical
`axis and Ar flow amount on the horizontal axis, the boundary of a plasma composition
`region wherein a TiN film is deposited is different when using as the target a Ti target
`directly after cleaning, or in other words, directly after having performed Ti sputtering, and
`when using a Ti target after a TiN film is temporarily deposited on a dummy substrate.
`[0012]
`That is to say, referring to FIG. 1, it was found that when a cleaned Ti target is
`
`used, the deposition of TiN occurs only in region A where N2 flow amount, and
`therefore, nitrogen plasma concentration is most high, and when a Ti target is used after
`having temporarily undergone TiN sputtering, the deposition of TiN also occurs in a
`region B with a lower nitrogen plasma concentration.
`
`In comparison, the deposition of TiN does not occur in a region C, and only a Ti
`film is deposited.
`
`In the region B between region A and region C, a TiN film is deposited, or a Ti
`film is deposited depending on the state of the Ti target used.
`
`However, in FIG. 1, the plasma power charged for exciting plasma in a reaction
`room of a sputtering device is set to a constant amount.
`[0013]
`The results of FIG. 1 show that with reactive sputtering of TiN using a Ti target,
`
`while the particles emitted from the target are Ti when using a pure, or in other words,
`cleaned Ti target, and that a proper, high concentration nitrogen plasma atmosphere is
`necessary for these to be deposited in the form of TiN on a substrate, a thin TiN film is
`already formed on the Ti target surface when using a Ti target that has temporarily
`undergone TiN sputtering, and there is therefore no need to have high nitrogen
`concentration in the plasma, and TiN is deposited even with low nitrogen concentration.
`
`Furthermore, when using this kind of target with a TiN film already formed, it is
`thought that even when the activation energy for nitridization necessary for new TiN
`formation is reduced, and the target surface corrodes along with the progression of the
`sputtering as a result, a new TiN film is always being quickly formed.
`[0014]
`FIG. 2 illustrates the boundary between a plasma composition region wherein
`
`TiN is deposited with the plasma power changed and a plasma composition region
`wherein Ti is deposited.
`
`However, the black circles in FIG. 2 indicate the boundary wherein an obtained
`deposited film changes from TiN to Ti when the plasma power is gradually increased
`starting from a low power state, and the black squares express the boundary wherein an
`obtained deposited film changes from Ti to TiN when the plasma power is gradually
`reduced starting from a high power state.
`[0015]
`
`Page 7 of 24
`
`

`

`(7)
`
`As understood from FIG. 2, when, for example, the total pressure of the plasma
`
`gas in a reactor vessel wherein plasma sputtering is performed is set to 0.6Pa, and the
`plasma power is gradually increased from a low power state, the deposition of the
`originally generated TiN film changes to the deposition of a Ti film where the plasma
`power exceeds approximately 16 kW.
`
`Conversely, when the plasma power is gradually decreased from a high power
`state, the originally generated Ti deposition film changes to a deposition of a TiN film
`when the plasma power reaches around 11~12 kW.
`
`In other words, in FIG. 2, when TiN is deposited by a reactive sputtering
`method, this means that a hysteresis occurs wherein the necessary plasma power is
`different when increasing power and when decreasing power.
`
`As described earlier, this hysteresis shows that while TiN is formed on the target
`surface, and a TiN deposition preferentially occurs when moving from a low power
`state to a high power state, TiN is not formed on the target surface when moving from a
`high power state to a low power state, and it is difficult for a TiN deposition to occur.
`[0016]
`FIG. 3 schematically illustrates the hysteresis of FIG. 2.
`
`As understood from FIG. 3, the hysteresis in the drawings is prescribed by a
`
`critical point 1 wherein hysteresis dissipates at a lower plasma power, and a critical point
`C2 wherein hysteresis dissipates at a higher plasma power, but as understood from the
`test results in FIG. 2, the critical points C1 and C2 can both be very plainly observed.
`
`With the test results of FIG. 2, it is understood that the critical point C1 is
`approximately 11 kW, and the critical point C2 is approximately 16 kW.
`
`Using this hysteresis, by first depositing a TiN film at a low plasma power at the
`critical point C1 or lower, and a low plasma density, and then increasing the plasma power to
`a point where it will not exceed the critical point C2 while holding the plasma gas pressure
`low, it becomes possible to obtain a high density TiN film having a fine texture, which was
`impossible conventionally under low plasma gas pressure and high pressure power.
`[0017]
`Furthermore, as illustrated in FIG. 2 and FIG. 3, it is observed that the internal
`
`pressure in the reaction room rises when the deposition of a TiN film begins.
`
`The reason for this is not sufficiently clear at the current time, but it is thought
`that it occurs because of the difference in sputtering speed between Ti and TiN (the
`sputtering speed of Ti is approximately four times the sputtering speed of TiN).
`[0018]
`FIG. 4 illustrates the relationship of the plasma power and specific resistance
`
`during TiN reactive sputtering.
`
`As understood from FIG. 4, the specific resistance of the obtained TiN film
`reduces along with the plasma power during sputtering.
`
`In other words, when forming a low resistance diffusion barrier layer, it is
`desirable to supply a plasma power as large as possible.
`
`In the present invention, by using the hysteresis in FIG. 3, it is possible to
`execute a TiN deposition with high plasma power without any problems by increasing
`the plasma power to the critical point C2, after setting the plasma power for the initial
`deposition to the critical point C1 or lower and forming TiN on the Ti target surface.
`
`As a result, it is possible to obtain a high density TiN film with small specific
`
`Page 8 of 24
`
`

`

`(8)
`
`resistance that excels as a diffusion barrier.
`
`In comparison, because a TiN reactive sputtering is directly performed using a Ti
`target wherein cleaning has been performed in the conventional method, a Ti film is
`deposited when the power is large, and a TiN film is not obtained.
`[0019]
`FIG. 5 illustrates the relationship between deposition speed and plasma power
`
`during TiN reactive sputtering.
`
`As clear from FIG. 5, the deposition speed increases along with the plasma power,
`and this means that when a TiN film is deposited with a large plasma power by the
`present invention, the deposition speed is also improved, and the throughput during
`fabrication of a semiconductor device is improved.
`[0020]
`FIG. 6 illustrates the hysteresis loop of observed Ti/TiN deposition when the Ar
`
`flow amount in is held stable and the N2 flow amount is changed in FIG. 1.
`
`Referring to FIG. 6, when the N2 flow amount is gradually increased from region
`C to region B in FIG. 1, Y1 is given as the boundary between conditions wherein a Ti
`deposition occurs and conditions wherein a TiN deposition occurs, and after entering
`region A, a TiN deposition occurs even on an extended line of the boundary Y1.
`
`Along with the starting of TiN deposition, the internal pressure of the reaction
`room also increases, and the boundary between conditions wherein a Ti deposition
`occurs and conditions wherein a TiN deposition occurs changes to Y2 in region A.
`[0021]
`Conversely, when the N2 flow amount is gradually reduced from region A to
`
`region B, Y2 is given as the boundary between conditions wherein a Ti deposition
`occurs and conditions wherein a TiN deposition occurs, and after entering region B, a
`Ti deposition occurs even on an extended line of the boundary Y1.
`
`Along with the starting of Ti deposition, the internal pressure of the reaction room
`reduces, and the boundary between conditions wherein a Ti deposition occurs and
`conditions wherein a TiN deposition occurs changes to the earlier boundary Y1 in region C.
`[0022]
`[Embodiments of the Invention] FIG. 7 illustrates the method for fabricating a
`
`semiconductor device according to the first embodiment of the present invention.
`
`Referring to FIG. 7(A), in this step, for example, an insulating layer 2 such as
`SiO2, PSG, or BPSG is deposited on an Si substrate 1 by, for example, a CVD method.
`
`However, a semiconductor device such as an MOS transistor is formed on a
`region 3 in the vicinity of the surface of the Si substrate 1.
`
`For example, the region 3 may be a source region or a drain region of the MOS
`transistor.
`[0023]
`Next, a contact hole 4 is formed in the insulation layer 2 so that the region 3 on
`
`the substrate 1 is exposed, and in the step in FIG. 7(C), a diffusion barrier layer 5 made
`up of TiN is formed on the structure in FIG. 7(B) with a thickness of 10~20 nm by a
`reactive sputtering step in mixed gas plasma of N2 using a Ti target and Ar.
`[0024]
`In the step in FIG. 7(C), after sputtering the TiN film on the substrate 1 using a
`
`Ti target with a first plasma power such that a TiN reactive sputtering occurs even if a
`
`Page 9 of 24
`
`

`

`(9)
`
`target made up of pure Ti is used, by continuing to sputter the TiN film on the TiN 5
`film with a second plasma power wherein TiN reactive sputtering does not occur when
`using a pure Ti target, the diffusion barrier layer 5 is formed.
`[0025]
`FIG. 8 illustrates the configuration of a sputtering device 10 that executes the
`
`step in FIG. 7(C).
`
`Referring to FIG. 8, the sputtering device 10 has a grounded reaction room 11 , and
`an anode 12 that supports the substrate 1 in FIG. 7(B) and a cathode 14 that is disposed
`opposing the anode 12, and supports a Ti target 13 are provided in the reaction room 11.
`
`The reaction room 11 vents to a high vacuum state via an exhaust port 11A, and
`a mixed gas of Ar and N2 is introduced into the reaction room 11 via a valve 11B.
`
`By direct current and/or high-frequency power being supplied to the cathode 14 via a
`power source 15 in this state, plasma 16 is formed between the anode 12 and the cathode 13,
`and Ti atoms expelled from the target 13 by the plasma 16 react with N particles in the
`plasma and are deposited in the form of TiN on the substrate 11 on the anode 12.
`[0026]
`FIG. 9 illustrates the change in plasma power in the reactive sputtering step in
`
`FIG. 7(C).
`
`Referring to FIG. 9, first, by performing a Ti sputtering on a dummy substrate in
`plasma of an inert gas such as pure Ar plasma in the preparatory step (O), the surface of
`the Ti target 13 is cleaned.
`
`In the preparatory step (O) in FIG. 9, the plasma power is set to the critical value
`C2 or more, but when performing cleaning in an inert gas plasma such as Ar plasma, the
`plasma power may be set between the critical value C1 and the critical value C2, or to
`the critical value C2 or lower.
`[0027]
`Next, in stage (1) in FIG. 9, the first power is set to the previously described
`
`critical value C1 in FIG. 3 or lower, and TiN sputtering is executed after setting the
`composition of plasma gas to a range wherein the hysteresis in FIG. 2 or FIG. 3 occurs,
`for example, a range of 0.58~0.63Pa.
`
`Referring to FIG. 2, for example, this first power is set to 11 kW or lower, and
`as a result, a TiN layer configuring a lowest portion of the diffusion barrier layer 5 is
`formed on the surface of the substrate 1.
`
`Furthermore, TiN is formed on the surface of the Ti target along with the
`deposition of the TiN layer.
`[0028]
`Stage (1) continues for, for example, 5~30 seconds, and while continuing the
`
`sputtering, the plasma power is increased from the first power in stage (2) illustrated in
`FIG. 9 to a second larger power that is at the critical value C2 in FIG. 3 or lower, and in
`stage (3), TiN sputtering is continued for a necessary time period at this second power.
`
`As a result, the diffusion barrier layer 5 in FIG. 7(C) is formed with a thickness
`of 10~20 nm.
`[0029]
`Additionally in the present embodiment, in the step in FIG. 7(D) after the step in
`
`FIG. 7(C), a wiring layer 6 made up of Al or Al alloy is deposited on the structure in FIG.
`7(C) to contact a diffusion region 3 in the substrate 1 in the contact hole 4.
`
`Page 10 of 24
`
`

`

`(10)
`
`In the present embodiment, because TiN is formed on the surface of the Ti target
`
`13 after temporarily performing TiN sputtering, it is possible to repeatedly perform
`deposition by reactive sputtering of a TiN film at a low nitrogen plasma concentration
`and high plasma power as long as the cleaning step or the step for depositing Ti have
`not been entered into therebetween.
`[0030]
`FIG. 10 is a diagram illustrating the TiN reactive sputtering step according to
`
`one modified example of the present embodiment.
`
`Referring to FIG. 10, after first performing target cleaning in step CL, plasma
`power is supplied in a sim