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 of 10
`
`IP Bridge Exhibit 2023
`
`TSMC v. IP Bridge
`|PR2016-01249
`
`Page 1 of 10
`
`IP Bridge Exhibit 2023
`TSMC v. IP Bridge
`IPR2016-01249
`
`

`

`
`
`(19) Japan Patent Office
`(JP)
`
`(12) Japanese Unexamined
`Patent Application
`Publication (A)
`
`(11) Patent Application Publication No.
`Japanese Unexamined Patent
`Application Publication No.
`H09-293690
`(43) Date of Disclosure: November 11, 1997 (Heisei 9)
`
`(51) Int. Cl.6
`H01L
`21/28
`
`21/203
`
`21/768
`
`
`
`
`
`Ident. Code
`301
`
`
`
`
`
`
`
`Inter. Ref. No.
`
`
`
`
`
`
`
`
`
`
`
`
`FI
`H01L 21/28
`21/203
`21/903
`
`
`
`Location of Tech. Indication
`301R
`S
`C
`
`
`
`Examination Request Status: Yes
`
`No. of Claims: 4
`
`OL
`
`(6 pages total)
`
`(71) Applicant: 000004237
`NEC (Nippon Electric Company)
`5-7-1 Shiba, Minato-ku, Tokyo
`(72) Inventor: Yoshinao MIURA
`C/o NEC (Nippon Electric Company),
`5-7-1 Shiba, Minato-ku, Tokyo
`Akio SUZUKI, attorney
`
`(74) Agent:
`
`
`
`(21) Filing Number:
`
`Patent Application No.
`H08-106539
`
`(22) Date of Application: April 26, 1996 (Heisei 8)
`
`
`
`
`
`
`
`(54) [Name of Invention] METHOD FOR
`MANUFACTURING SEMICONDUCTOR DEVICE
`
`(57) Abstract
`[Problem] Use of an amorphous film as a barrier film
`between a silicon (Si) substrate and a contact metal has
`been proposed, however, an amorphous film is difficult
`to form only in a contact hole area because said film
`must be formed using a sputtering method.
`[Resolution Means] Forming an insulating film 12 of
`silicon oxide, and the like, on a surface of a silicon
`substrate, opening a contact hole 13 in the insulating film
`locally, uniformly depositing a thin Ti film 14 on a front
`surface that includes the contact hole to a thickness of 10
`nm, then, heating a base to 450 to 550°C to form an
`amorphous TiSix film 15 only on an exposed Si part inside
`the contact hole, which thus becomes a thin barrier film.
`Forming an Al film 16 thereupon to create a pad.
`
`
`
`
`
`
`
`Page 2 of 10
`
`

`

`Specification
`
`(2)
`
`Title of the Invention: METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
`
`
`[DETAILED DESCRIPTION OF THE INVENTION]
`[0001]
`
`[Technical Field of the Invention] The present invention relates to an improvement in a
`method for forming contact structures using metal nitride barrier layers in a method for
`manufacturing semiconductor devices.
`[0002]
`
`[Conventional Technology] The importance of wiring techniques for making connections
`between elements has become more and more important as devices have become more integrated
`in recent years. It is especially critical to reduce resistance in wiring contacts while maintaining
`reliability. While it is common for Al, W, and the like, to be used as main constituent metals in
`conventional contact structures, when these metals and silicon substrates are brought into close
`contact and joined, heat treatments cause interfacial interdiffusion and silicide reactions, and form
`a high resistance layer at the interface, while current leaks are generated due to the piercing of the
`shallow junction of the reaction layer. Barrier layers with high reaction suppressing force and low
`resistance are needed to prevent this, and thus barrier layers made of high melting point metals
`such as Ti, W, or the like, or compounds thereof, have been used.
`[0003]
`
`In particular, a variety of techniques have been proposed that use a metal nitride film
`accompanied by a thin silicidation layer near the interface as a barrier by thermally nitriding a high
`melting point metal on Si. Examples include Japanese Unexamined Patent Application Publication
`No. H02-235372 and Japanese Unexamined Patent Application Publication No. H04-112529. FIG.
`4 is a cross sectional view illustrating one of these examples, where an SiO2 film 42 is formed on
`an Si substrate 41 as an insulating film, a barrier film 45 made of a metal nitride of a high melting
`point metal such as Ti, W, or the like, is formed in a contact hole 43 opened in the insulating film
`42, and a metal 45 of mainly Al, W, or the like, is formed on the insulating film.
`[0004]
`
`However, barrier properties are insufficient because these constituent barrier films are
`generally polycrystalline structures, and because there are grain boundaries that become high
`speed diffusion paths. Thus, film thickness that is sufficiently thicker than grain crystal size is
`required to achieve adequate barrier properties, which increases contact resistance. Furthermore,
`when barrier properties are enhanced by filling these grain boundaries using oxidation (Applied
`Physics Letters Vol. 47, p. 471 (September 1985), Japanese Unexamined Patent Application
`Publication No. H05-267211), the specific resistance of the material itself increases through the
`introduction of impurities such as oxygen, and the like, which also increases contact resistance.
`Moreover, to prevent damage to Si substrate surfaces in conjunction with the formation of barrier
`films in polycrystalline barrier films, barrier films cannot be formed directly onto Si substrates,
`and thus good electrical properties cannot be achieved.
`[0005]
`
`From this point of view, techniques have been proposed where it is preferable to make the
`crystal grains small and that use amorphous films or microcrystalline films obtained through
`sputtering in nitrogen atmospheres as barrier films (Applied Surface Science, Vol. 41 and 42, p.
`207 (1989)).
`[0006]
`
`[Problem to be Solved by the Invention] However, when such amorphous films and
`microcrystal granular films are formed using sputtering methods, there is a problem in that it is
`impossible to employ a self aligning process to selectively form barrier films on contact openings,
`or, in particular, to form barrier films in contact holes, and thus that it is difficult to apply such
`films to fine, highly integrated semiconductor devices.
`
`Page 3 of 10
`
`

`

`(3)
`
`[0007]
`
`An object of the present invention is to provide a manufacturing process that makes it
`possible to use a self aligning process to selectively deposit an amorphous film in a contact hole,
`realizes a contact structure having low contact resistance and high barrier properties, and
`manufactures a semiconductor device having high speed operating characteristics and a simple
`structure.
`[0008]
`
`[Means for Solving the Problem] The manufacturing method according to the present
`invention is characterized in that the method exposes a barrier film formed between a silicon
`substrate and a contact metal to a reactive gas containing nitrogen after evenly depositing a thin
`high melting point metal film on the silicon substrate while keeping a substrate temperature at 450
`to 550°C to form the barrier film as a thin amorphous or microcrystalline barrier film made of a
`high melting point metal, silicon, and nitrogen. For example, a preferred embodiment of the
`present invention forms an insulating film of silicon oxide, and the like, on a surface of a silicon
`substrate; opens a contact hole locally in the insulating film, uniformly deposits a thin high
`melting point metal film on an entire surface that includes the contact hole, heats the substrate to
`450 to 550°C to thus form an amorphous layer made of the high melting point metal and silicon
`only on an exposed silicon part inside the contact hole, removes unreacted metal on the insulating
`film by chemical etching, and then exposes the film to a reactive gas containing nitrogen to form a
`thin amorphous or microcrystalline barrier layer.
`[0009]
`
`Here, it is preferable that the thin high melting point metal film is made of Ti, Zr, and Hf
`and is formed to a thickness of 10 nm or less. Furthermore, the process for exposing to a reactive
`gas containing nitrogen is radical nitrogen beam irradiation, or highly reactive nitrogen compound
`gas irradiation using hydrazine, ammonia, or the like.
`[0010]
`
`[Description of the Preferred Embodiments] A first embodiment of the present invention
`will be described next with reference to FIG. 1. First, as illustrated in FIG. 1 (a), an insulating film
`12 made of SiO2 is formed on a surface of a (100) surface Si substrate 11, and then, the insulating
`film 12 is selectively etched to open a contact hole 13 in a required location. Furthermore, an
`electron beam gun is used in a high vacuum to deposit a 4 nm thick polycrystalline Ti film 14.
`[0011]
`
`Next, as illustrated in FIG. 1 (b), the deposited polycrystalline Ti film 14 is heated for five
`minutes at 500°C to reform the area of the polycrystalline Ti film 14 touching the Si substrate 11
`into a Ti amorphous film 15. It can be confirmed, from the fact that the Reflection High Energy
`Electron Diffraction (RHEED) pattern is hollow and the Si peak strength according to X-ray
`Photoelectron Spectroscopy (XPS) has increased significantly, that a surface layer of this film has
`become a TiSix amorphous layer. It was discovered that a heating temperature in the range of 450
`to 550°C is preferable because, at 600°C or above, silicide begins to crystallize rapidly making it
`impossible to obtain an amorphous film, and because, at 400°C or below, it takes too much time to
`mutually diffuse metal and silicon.
`[0012]
`
`Next, as illustrated in FIG. 1 (c), a radical nitrogen beam with a flux of approximately 1 X
`10-5 Torr was supplied to the substrate surface for five minutes using a radical nitrogen source
`while the temperature of the Si substrate was maintained. Based on an XPS surface analysis of the
`Ti amorphous film 15, this resulted in the surface being reformed into an even film containing
`approximately equal amounts of Ti, Si, and N, and thus being configured as a barrier film. This
`barrier film 15, observed using cross sectional Transmission Electron Microscope (TEM), was
`found to be a film with a uniform thickness of 5 nm having an extremely steep interface with an
`amorphous structure made of extremely fine grains with diameters of 1 nm or less. Furthermore,
`because the RHEED pattern is still hollow even after the substrate temperature is raised to 800°C,
`the amorphous structure of this film is very stable, which is in stark contrast to the fact that
`
`Page 4 of 10
`
`

`

`(4)
`
`amorphous TiSix readily undergoes a phase transition to a polycrystalline structure at around
`650°C.
`[0013]
`
`Therefore, as illustrated in FIG. 1 (d), a 50 nm thick Al film 16 is deposited on the Ti
`amorphous film 15, and this Al film 16 is etched along with the crystalline Ti film 14 to form a
`contact wire. With this wire structure, the barrier film 15 maintains flatness despite undergoing a
`slight decrease in film thickness even when heat treated (550°C for 60 minutes) in a nitrogen
`atmosphere, and is thus suppressed to a level of thickness equal to or less than that of an interface
`interdiffusion barrier film.
`[0014]
`
`In this way, a metastable amorphous silicide state is achieved at a temperature lower than a
`crystallization temperature when the Ti reacts with the silicon. If nitriding is carried out at this
`stage, the amorphous state stabilizes, which thus enables the formation of a precisely uniform
`barrier film. This film enhances barrier properties, and is able to reduce film thickness and
`decrease contact resistance significantly when compared to conventional methods. Furthermore,
`because a damage layer caused by sputtering, and the like, is not left behind, good bonding can be
`realized.
`[0015]
`
`A second embodiment according to the present invention will be described with reference
`to FIG. 2. First, as illustrated in FIG. 2 (a), an insulating film 22 made of SiO2 is formed on a
`surface of a (100) surface n-Si substrate 21, and then, a 10 µm diameter contact hole 23 is opened
`in a portion of the film. Furthermore, a polycrystalline Ti film 24 10 nm thick is deposited over an
`entire surface using a sputtering method, and then, only the Ti film 24 in the contact hole 23 is
`heated to 500°C for five minutes, and is thus reformed into an amorphous TiSix 25.
`[0016]
`
`Next, as illustrated in FIG. 2 (b), the substrate is taken out of a high vacuum tank and
`immersed in an etching solution containing hydrochloric acid as a main component for 1 minute to
`remove the unreacted Ti film 24. The substrate is re-introduced into the high vacuum and
`irradiated with a radical nitrogen beam. Line analysis of this sample surface using Auger Electron
`Spectroscopy (AES) revealed that while the elements Ti, Si, N, and O were observed in the bottom
`of the contact hole 23, only Si, N, and O were observed on the surface of the insulating film 22,
`and thus it was successfully confirmed that, as is illustrated in FIG. 2 (c), a conductive amorphous
`TiSiN film 26 was formed only in the bottom of the contact hole 23, while an SiN film 27 was
`formed on the surface of the insulating film 22. Therefore, as illustrated in FIG. 2 (d), a 200 nm
`thick Al film 28 is formed to form an Al pad inside the contact hole using a lithography process.
`[0017]
`
`Using an I-V method to evaluate the diode properties of a Schottky junction produced in
`this way revealed that a nearly ideal curve having a barrier wall height of 0.55 eV was achieved.
`This indicates that a substrate surface damage layer, introduced by the sputtering process, was
`consumed by silicidation, and that an interface with few defects was obtained. Thus, it is expected
`that the barrier wall height will be half an Si band gap (1.1 eV), and that, in terms of ohmic contact,
`contact resistance that is sufficiently low with respect to both n and p- substrates was obtained,
`which is probably also effective for forming C-MOS (Complementary-MOS) elements.
`[0018]
`
`An amorphous TiSix 25 was formed only on an exposed part of the substrate by the
`deposition and subsequent heating of the Ti film 24 according to the present embodiment, and an
`unreacted Ti film 24 was left behind because an interface reaction with Ti in a coated part of the
`insulating film 22 was slow. Because the unreacted metal Ti dissolves at a much faster rate than
`amorphous TiSix when an etching solution having hydrochloric acid as a major component is used,
`performing the nitriding process after chemically removing only the unreacted Ti film 24 makes it
`possible to selectively form a barrier film 26 of TiSiN only on an exposed part of the Si substrate
`21, which thus makes it possible to form a barrier film only inside the contact hole.
`
`Page 5 of 10
`
`

`

`(5)
`
`[0019]
`
`[Embodiments] FIG. 3 is a diagram illustrating an embodiment performed to evaluate a
`contact structure produced using the method according to the present invention. At this time, a
`Kelvin method test pattern was formed to measure contact resistance. First, as illustrated in FIG. 3
`(a), a 0.5 µm field oxide film 32 was formed on a (100) surface p- Si substrate (resistivity: 10 to 20
`Ω cm, 4 inch φ) 31, and then, a contact region of the field oxide film 32 was removed using a
`standard photolithography technique to open a contact hole 33. Furthermore, although not shown
`in the figure, a 20 nm protective thermal oxide film was grown in the contact hole 33, and then As
`ions were implanted into the Si substrate 31. The implanting conditions were a dosage of 5 x 1015
`cm-2 and energy of 80Kev. Activation annealing was performed for 30 minutes at 900°C in a
`nitrogen atmosphere, and then, the protective thermal oxide film inside the contact hole 33 was
`removed by placing the substrate in buffered hydrofluoric acid (pH up to 4).
`[0020]
`
`Next, as illustrated in FIG. 3 (b), the Si substrate 31 was immediately introduced into a
`vacuum layer, and a 10 nm thick thin Ti film was deposited on the entire surface of the Si
`substrate 31 using a sputtering method. After giving the vacuum layer where the sputtering was
`performed an Ar atmosphere of 1 x 10-5 Torr or less and heating the substrate at 500°C for five
`minutes, the substrate was then irradiated with a radical nitrogen beam having a flux strength of 1
`x 10-4 Torr. At this stage, an amorphous TiSiN film 34 is formed on a substrate 31 surface part of
`the contact hole 33, and a TiN film 35 is formed on a surface part of the field oxide film 32.
`[0021]
`
`After that, as illustrated in FIG. 3 (c), the Si substrate temperature was reduced to 150 or
`lower, and a 6 µm Al film 36 was deposited in the same vacuum. Next, with respect to this
`substrate, the Al film 36 and the foundational TiN film 35 were etched by a lithography process
`using Cl2 as a reaction gas to thus form a contact pad having a desired shape.
`[0022]
`
`The electrical characteristics of the contact structure produced in this way were evaluated
`with respect to a contact size of 1 X 1 µm2 using an I-V method. An average resistance value of 1
`X 10-7 Ω cm2 or less, which is a sufficiently low value, was obtained for 100 contacts. Moreover,
`when the same sample was heated at 500°C for 60 minutes in a hydrogen atmosphere and the same
`contact resistance measurement was performed, there was next to no rise in the average resistance
`value, no current leaks were observed, and the good product rate was nearly 100%.
`[0023]
`
`Note that, in addition to the Ti described above, other high melting point metals having
`amorphous structures prior to silicide crystallization, such as Zr, Hf, and the like, may also be used
`in the present invention as the metal for configuring the barrier film. Furthermore, the same effect
`can be obtained even if the contact metal is another metal other than Al, such as Cu, Ag, W, Mo,
`and the like, an alloy thereof, or even if the contact metal contains traces of other elements. Finally,
`in addition to radical nitrogen beam irradiation, the same effect can be obtained even if the
`nitriding process irradiates a highly reactive nitrogen compound gas such as hydrazine (N2H4),
`ammonia (NH3), and the like.
`[0024]
`
`[Effect of the Invention] As was described above, the following effects can be achieved
`with the manufacturing method according to the present invention. A first effect is an expected
`acceleration of semiconductor element operation through the use of the contact structure according
`to the present invention. This is because the film thickness for securing barrier properties can be
`thin due to the fact that a thin amorphous film where the particle diameter is 1 nm or less can be
`obtained, and because impurities that raise the resistance of oxygen, carbon, and the like, are not
`readily mixed in, such that low contact resistance can be achieved. A second effect is that a device
`configuration can be simplified. This is because a damage layer added to the substrate by
`sputtering, and the like, is not left behind, which gives the interface bond with the substrate
`superior electrical characteristics, thus making it possible to form a barrier directly on an exposed
`
`Page 6 of 10
`
`

`

`(6)
`
`Si part in an opening using the present process, such that a process for foundational silicide layer
`formation, and the like, is no longer required. A third effect is that elements can be highly
`integrated. This is because a silicidation reaction is used during the process such that a self
`alignment process is made possible through selective deposition in a contact opening.
`
`[BRIEF DESCRIPTION OF THE DRAWINGS]
`FIG. 1 is a cross sectional view illustrating a first embodiment according to the present invention
`in a processing sequence.
`FIG. 2 is a cross sectional view illustrating a second embodiment according to the present
`invention in a processing sequence.
`FIG. 3 is a cross sectional view illustrating an embodiment according to the present invention in a
`processing sequence.
`FIG. 4 is a cross sectional view for describing a conventional contact structure.
`
`[REFERENCE NUMERALS]
`11, 12, 31
`Si substrate
`12, 22, 23
`Insulating film
`13, 23, 33
`Contact hole
`14, 24
`Ti film
`15, 25
`Amorphous TiSix film
`16, 28, 36
`Al film
`26, 34
`Amorphous TiSiN film
`27
`SiN film
`35
`TiN film
`
`Page 7 of 10
`
`

`

`[SCOPE OF CLAIMS]
`
`(7)
`
`
`A method for manufacturing a semiconductor device having a barrier film between a silicon
`1.
`substrate and a contact metal, comprising: uniformly depositing a thin high melting point metal film on
`a the silicon substrate, and; exposing the barrier film to a reactive gas containing nitrogen while the
`substrate is kept at a temperature of 450 to 550°C, thus forming the barrier film as a thin amorphous or
`microcrystalline barrier layer made of the high melting point metal, silicon, and nitrogen.
`
`A method for manufacturing a semiconductor device, comprising: forming an insulating film
`2.
`of silicon oxide, and the like, on a surface of a silicon substrate; opening a contact hole locally in the
`insulating film; uniformly depositing a thin high melting point metal film on an entire surface that
`includes the contact hole; heating the substrate to 450 to 550°C to thus form an amorphous layer
`made of the high melting point metal and silicon only on an exposed silicon part inside the contact
`hole; removing unreacted metal on the insulating film by chemical etching; and then exposing the
`film to a reactive gas containing nitrogen to form a thin amorphous or microcrystalline barrier layer.
`
`The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the
`3.
`thin high melting point metal film is of Ti, Zr, and Hf and is formed to a thickness of 10 nm or less.
`
`The method for manufacturing a semiconductor device according to any one of claims 1 to 3,
`4.
`wherein the process for exposing to a reactive gas containing nitrogen is radical nitrogen beam
`irradiation, or highly reactive nitrogen compound gas irradiation using hydrazine, ammonia, or the like.
`
`Page 8 of 10
`
`

`

`(8)
`(8)
`
`
`
`FIG. 1
`
`FIG. 2
`
`13 Contact hole
`23 Contact hole
`‘14 Ti film
`
`
`
`12 Insulating film
`
`11 Si substrate
`
`Si substrate
`4 1
`Insulating film
`4 2
`4 3 Contact hole
`4 4 Barrier film
`4 5
`AI electrode
`
`Page 9 of 10
`
`Page 9 of 10
`
`

`

`(9)
`(9)
`
`
`
`
`
`
`
`Page10of1O
`
`Page 10 of 10
`
`