(12) Patent (19)GB(11>2
`
`(13) B
`
`Title of Invention
`
`(54)
`
`Methods of forming metal interconnects in
`semiconductor-devices
`
`(51)
`
`(NT CL‘; 0230 16/56 16/34 // H01L 21/768
`
`
`
`lnventor(s)
`
`Application No
`96046143
`Gyung-Su Cho
`
`
`
`
`
`(22)
`
`Date of filing
`04.03.1996
`
`(30)
`
`Priority Data
`
`(31 )
`
`(32)
`
`(33)
`
`95004447
`
`04.03.1995
`
`KB
`
`(43)
`
`Application published
`11.09.1996
`
`(45)
`
`
`
`Patent published
`30.09.1 998
`
`
`
`(73)
`
`Proprietor(s)
`Hyundai Electronics
`Industries 00., Ltd.
`
`(Incorporated in the
`Republic of Korea)
`
`San 136-1, Ami-ri
`Bubal—eub
`lchon-kun Kyoungki-do
`Republic of Korea
`
`Agent and/or
`Address for Service
`A A Thornton & Co
`Northumberland House
`303-306 High Holborn
`London
`WC1V 7LE
`United Kingdom
`
`74
`
`)
`
`(
`
`Domestic classification
`(Edition P)
`07F FHE FP810 F0841 F0851
`F0861 F0916 FR861 FR864
`F802 F809
`H1K KHAAB K4C3G K4C8
`K4F16 K4F26 K4G3Y
`U1S 81421 $2061
`
`(56)
`
`Documents cited
`EP0525637 A1
`EP0514103 A1
`EP0209654 A2
`US5494860 A
`US5136362 A
`
`
`
`(58)
`
`Field of search
`
`As for published application
`2298657 A viz:
`UK CL(Edition 0) C7F FACE
`FACX FAHE FAHX FAXE
`FAXX FHB FHE FHX, H1K
`KHAAB KHAAX KHABX
`KHAD
`lNT CL6 0230 14/06 14/58
`16/34 16/56. H01L 21/285
`Online: WPI, CLAIMS
`updated as appropriate
`
`Page 1 0f 13
`
`TSMC Exhibi 1025
`TSMC V. 1P B '
`1PR2016—01249 & IPR2016—01264
`
`Page 1 of 13
`
`

`

`1/3
`
`PRIOR ART
`
`\
`
`I II[
`
`I’ll\\\\\\\
`
`\\\\\\\\\\\\\\\\\\\\\\\\c
`‘ VIII/[IIIIIIIIIIIIIIIIII
`
`\\\\\
`
`§k
`\\\\\\\\\
`III/IIIIIII A
`
`FIG.
`
`1
`
`FIG. 8A
`
`Page 2 0f 13
`
`Page 2 of 13
`
`

`

`2/3
`
`
`\\\\\\\\\\\\\\\\\\\\\\\\\V
`I IIIIIIIIIIIIIIIIIIIIIIA
`
`
`.\\\\\\\\\\\\\\\{\\\\\\\\\‘
`'lllllllllrlllllllllllll \
`\\\\\\\////
`
`
`
`
`
`
`
`
`‘\
`lllllllllllt .\
`§§\\\\\\\\
`
`FIG. 8B
`
`\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\“
`
`
`
`
`
`l
`\\\\\\\\\\\\\\\\\\\\\\\\'
`aVIIIIIIIIIIIIIIIIIIIIIII
`
`a\ a
`
`?
`\ I
`
`n
`I
`llllllll’llit
`
`
`
`
`7
`
`5
`
`
`
`
`
`
`*1
`
`
`
`3
`
`Page 3 0f 13
`
`Page 3 of 13
`
`

`

`pn
`
`3/3
`
`
`
`
`
`aBEUh!$§Uflifld38§fi§fl§i§§fit§fli§§
`
`IIIIIIIIIIIII
`Illllllllllpl
`
`'IIIIIIIIIII’ ‘
`I y’lllllllll‘
`‘\\\\\\\\\V I ’
`I ’ §\\\\\\\\\\
`I
`I I
`viii/IIII‘: 5 I
`g I : 7,111,111;
`Isl;
`’1‘;
`I\’/
`’p\t
`I
`I \
`
`
`5:4
`I56
`I § I It’ll/l \ I
`I \ I’ll/III 4 N l
`I \\\\\\\\\\\\ I
`’IIIIIIIIIIII’
`
`
`
`
`
`. Page 4 0f 13
`
`Page 4 of 13
`
`

`

`
`
`l
`
`METHQ 2DS QF FQRMINQ METAL INTERQS 2NNEQTS
`
`IN EMI ND
`
`T RDEVI ES
`
`FIELD OF THE INVENTION
`
`The present invention relates to a method of forming a semiconductor
`
`device, and more particularly to a method of forming a metal interconnect in a
`
`semiconductor device including a diffusion barrier metal layer.
`
`DE CRIPTI N F
`
`EPRI RART
`
`As the integration of semiconductor device is increased, many methods
`
`10
`
`have beenstudied to make the interconnect design free and easy, and to make the
`
`designation of resistance and current capacitance variable.
`
`In general, aluminum is widely used as the material for metal
`
`interconnect of semiconductor device, As the integration is increased, the width
`
`of the interconnect is fine, so the current density is increased. The increase of the
`
`15
`
`current density, however, generates failure due to electromigration, anti-reflection
`
`and movement of stress, which results in a drop in the reliability. To solve the
`
`above problems, a method that deposits copper(Cu) or titanium(Ti) on the
`
`interconnect of a1uminum(Al) has been provided, but it leads to serious problems
`
`such as the failure of insulator and a short of interconnects due to phenomena such
`
`20
`
`as hillock and whisker.
`
`Fig. l is a sectional view of semiconductor device forming the metal
`
`interconnect after the formation of the diffusion barrier layer according to an
`
`embodiment of the conventional art. In the conventional method, an insulating
`
`layer 2 is first formed on a semiconductor substrate '1. Afterwards, contact holes
`
`25
`
`are formed at the predetermined portions of the insulating layer 2 on the
`
`semiconductor substrate 1 by etching some portions of the insulating layer till the
`
`surface ofthe substrate 1 is exposed. Next, diffusion barrier layers of titanium(Ti)
`3 and titanium nitride(TiN) 4 are orderly formed by Physical Vapor Deposition.
`
`Lastly, metal interconnect 8 using aluminum metal or aluminum alloy is formed
`
`Page 5 of 13
`
`Page 5 of 13
`
`

`

`on the Titanium Nitride layer 4.
`
`Currently however, as high integration of device proceeds, the size of
`
`the contact hole is more and more decreased. In proportion to the decrease of the
`
`contact hole size, the aspect ratio of the contact hole is increased. Accordingly, in
`
`a case where the diffusion barrier layers are formed by Physical Vapor Deposition
`
`as above, the step coverage is decreased resulting in the diffusion barrier layer
`being deposited unevenly. Moreover, in a case Where the thickness of the barrier
`
`layer is increased, a shadow effect is generated at the corner of the upper portion
`
`of the contact hole, making it impossible for the succeeding process to proceed.
`
`-In addition, in a case where the Plasma Enhanced Chemical Vapor Deposition
`
`method, in which TiCl4 reacts with NH3 for TiN, is used to enhance the step
`
`coverage, there is a problem in the excess generation of particles owing to the
`
`plasma. Therefore, the result is a drop in the yield and reliability of the devices.
`
`Furthermore, in this case, there is a problem in reducing the speed of the device
`
`because the inner resistance of it is increased by the phase transformation to the
`
`amorphous phase during the deposition of TiN.
`
`SUMMARY OF THE INVENTION
`
`The present
`
`invention provides a method of forming a metal
`
`interconnect for a semiconductor device, comprising the steps of:
`
`forming a contact hole in an insulating layer formed on a semiconductor
`
`substrate;
`
`depositing titanium layer and then titanium nitride layer on said
`
`insulating layer and in said contact hole by chemical vapor deposition, said
`
`titanium nitride layer being in amorphous state
`
`thermally annealing said substrate in an atmosphere of nitrogen whereby
`
`a portion of said amorphous titanium nitride layer is transformed to crystalline
`
`titanium nitride layer;
`
`depositing a metal layer on the annealed titanium nitride layer; and
`
`_ patterning the titanium layer, the annealed titanium nitride layer and the
`
`10
`
`15
`
`20
`
`25
`
`Page 6 of 13
`
`Page 6 of 13
`
`

`

`
`
`3
`
`metal layer formed on the contact hole and insulating layer.
`
`In a preferred embodiment the invention further comprises a step of
`
`depositing an arc-thin film which prevents the reflection of light on the metal layer
`
`before the patterning of the formed layers.
`
`Preferably in the above arrangement the amorphous titanium nitride
`
`layer is formed by thermal decomposition of either tetradimethylaminotitanium or
`tetradiethylaminotitanium.
`i
`
`That thermal decomposition may be performed at a temperature of 300
`
`to 500°C at a pressure of 5 to 10 mtorr, while the thermal annealing of the
`
`amorphous titanium nitride may be performed in a nitrogen atmosphere at a
`
`temperature of 400 to 600°C or alternatively may be performed in a nitrogen
`
`atmosphere at a temperature of 700 to 900°C for 10 to 30 seconds by rapid thermal
`
`annealing.
`
`The present invention further provides a method of forming a metal
`
`interconnect for a semiconductor device, comprising the steps of;
`forming a contact hole in an insulating layer formed on a semiconductor
`‘
`
`substrate;
`
`'
`
`forming a titanium layer on the said insulating layer and in said contact
`
`hole by chemical vapor deposition; and
`
`forming a titanium nitride layer on said titanium layer, titanium nitride
`
`component of said titanium nitride layer being thermally decomposed from
`
`tetradimethylaminotitanium or tetradiethylaminotitanium
`
`'
`
`In this method, the annealing is preferably performed at a temperature
`
`of 300 to 500°C and a pressure of 5 to 10 mtorr.
`
`This invention thus provides advantages in terms of yield and reliability
`
`of semiconductor devices by suppressing excess particles generated at the CVD
`the position of the diffusion barrier layer. Another advantage is the increase in
`operation speed of a semiconductor device by the decrease in the internal
`
`resistance of the diffusion barrier layer in the present invention.
`
`10
`
`15
`
`20
`
`25
`
`Page 7 of 13
`
`Page 7 of 13
`
`

`

`4
`
`Accordingly, the object of the present invention is to provide a method
`
`of forming the metal interconnect of semiconductor device, which can enhance the
`
`yield and reliability of a semiconductor device by increasing the step coverage of
`
`the diffusion barrier layer and decreasing the inner resistance and the particle
`
`generation thereof.
`
`BRIEF DESCRIPTION QF THE DRAWINGS
`
`Fig. l is a sectional view for illustrating a method of forming the metal
`
`interconnect according to the conventional embodiment.
`
`Figs 2A to 2D are sectional views, showing sequential processes of
`
`forming the metal interconnect, according to an embodiment of the present
`
`invention, respectively.
`
`DETAILED DESQ QRIPTIQN QF THE PRESENT INVENTIQN
`
`Hereinbelow, a preferred embodiment of the present invention is
`
`illustrated refening to Figs. 2A to 2D.
`
`Figs. 2A To 2D are sectional views showing sequential processes for
`
`forming a metal interconnect according to an embodiment of the present invention.
`
`First, refening to Fig. 2A, an insulating layer 2 is deposited on a
`
`semiconductor substrate 1 including active regions. A contact hole is then formed
`
`10
`
`15
`
`at the predetermined portion of the insulating layer 2 by photolithographic method
`which etches the exposed the exposed insulating layer till the surface of the
`
`20
`
`semiconductor substrate 1 is exposed. Then, as shown in Fig. 2B, a Titanium layer
`
`3 is deposited on the inner portion of the contact hole and the whole surface of the
`
`insulating layer 2. The Titanium layer 3 is very thinly formed to a degree capable
`
`of maintaining the shape of the contact hole 2 by Chemical Vapor Deposition
`
`25
`
`which react TiCl4 with NH3 or NF3. The Chemical Vapor Deposition method is to
`
`enhance the step coverage of the inside of the contact hole. Then, a Titanium
`
`Nitride layer 4 is formed on the Titanium layer 3. The Titanium Nitride layer 4 is
`formed by Chemical Vapor Deposition (Low Pressure ACVD) to depress the
`
`generation of the particles. In other words, the method uses the raw material of
`
`Page 8.0f 13 .
`
`Page 8 of 13
`
`

`

`
`
`5
`
`only tetradimethylarninotitanium [Ti{N(CH3)2},] or tetradiethylaminotitanium
`
`[Ti{N(C2H,)4}], and decomposes titanium Nitride from one of said two
`
`compounds by thermal annealing wherein, the supplied gas is Nitrogen and/or
`
`Helium. The deposition temperature of the TiN ranges from 300 to 500 °C and the
`
`pressure of the furnace is controlled to the range from 5 to 10 mTorr. What is
`
`formed is an amorphous layer. Afterwards, the semiconductor substrate which the
`above layers were formed on, is thermally annealed in
`atmosphere of nitrogen
`
`for the temperature range of 400 to 600°C. Through the annealing process, the
`
`titanium nitride layer 4 is transformed to three titanium nitride layers 5, 6, 7 whose
`
`physical properties are different from one another. The lower or first layer is
`
`composed of titanium nitride 5 that exists as an amorphous layer, the middle or
`
`second layer is composed of titanium nitride 6 that exists as a crystalline layer, and
`
`the upper or third layer is composed of titanium nitride 7 that exists as a
`
`nitrogen-rich crystalline layer. Here, the Rapid Thermal Armealing (RTA) method
`
`can also be used conventional
`
`thermal annealing. It
`
`is performed at the
`
`temperature range of 700 to 900°C and in the time range of 10 to 30 seconds.
`
`Titanium nitride 4 of single layer has very high resistance because it is in an
`
`amorphous state, but the triple layer of titanium nitride 5,6,7 has a low resistance
`
`compared with the single layer titanium nitride 4 because its physical properties
`
`are different from one another. The titanium layer 3 and titanium nitride layers 5,
`
`6, 7 act as diffusion barrier metal for preventing the diffusion of metal atoms
`
`which would occur without the existence of the barrier. Afterwards, as shown in
`
`Fig. 2C, a interconnecting metal such as aluminum, copper, or alloy of aluminum
`
`and copper etc.,
`
`is formed on the diffusion barrier layer, wherein the
`
`interconnecting metal
`
`is connected to the active regions of the substrate.
`
`Afterwards, an arc-metal layer 9 is formed on the metal layer 8 by Chemical
`Vapor Deposition. Here, the arc-metal layer is to prevent the light from reflecting
`on the interconnecting metal when light is exposed performed to form a pattern of
`
`the metal
`
`interconnect.
`
`The
`
`arc-thin
`
`film is
`
`composed
`
`of
`
`10
`
`15
`
`20
`
`25
`
`"Page 9 of 13
`
`Page 9 of 13
`
`

`

`6
`
`tetradimethylaminotitanium or tetradiethylaminotitanimn, and the range of the
`
`deposition temperature is from 300 to 450°C. The step for forming the arc-thin
`
`film 9 can be deleted according to each case.
`
`Lastly, as shown in Fig. 2D, the metal interconnect is formed by
`
`5
`
`patterning said metal layers 3, 5, 6, 7,. 8, 9. The metal layer 8 can be substituted
`
`for a metal having high conductivity such as Tungsten.
`As previously described in detail, the present invention can reduce the
`
`resistance of titanium nitride and the generation of particles, and enhance the step
`
`coverage by transforming titanium nitride of a single layer to titanium nitIide of
`
`10
`
`three layers having individual properties. The three layers are formed through a
`
`method that consists or forming titanium nitride by thermal decomposition of the
`
`raw material including nitrogen and titanium, and annealing the deposited titanium
`
`nitride in an atmosphere of nitrogen. Accordingly, it provides efi'ects enhancing
`
`not only the reliability and yield but also the speed of the signal transfer.
`
`-. Page 10 of 13
`
`Page 10 of 13
`
`

`

`
`
`g :laims
`
`l.
`
`A method of forming a metal interconnect for a semiconductor device,
`
`comprising the steps of:
`
`forming a contact hole in an insulating layer formed on a semiconductor
`
`substrate;
`
`depositing titanium layer and then titanium nitride layer on said
`
`insulating layer and in said contact hole by chemical vapor deposition, said
`
`titanium nitride layer being in amorphous state
`
`thermally annealing said substrate in an atmosphere ofnitrogen whereby
`
`a portion of said amorphous titanium nitride layer is transformed to crystalline
`
`titanium nitride layer;
`
`depositing a metal layer on the armealed titanium nitride layer; and
`
`patterning the titanium layer, the annealed titanium nitride layer and the
`
`metal layer formed on the contact hole and insulating layer.
`
`2.
`
`The method in accordance with claim 1, wherein said titanium layer is
`
`formed by chemical vapor deposition which reacts TiCl4 with NH3.
`
`3.
`
`The method in accordance with claim 1, wherein said amorphous
`
`titanium nitride
`
`layer
`
`is
`
`formed
`
`by
`
`thermal
`
`decomposition
`
`of
`
`tetradirnethylaminotitanium.
`
`4.
`
`The method in accordance with claim 1, wherein said amorphous
`
`titanium nitride is formed by thermal decomposition of tetradiethylaminotitanium.
`
`5.
`
`i
`
`The method in accordance with claim 3 or 4, wherein said thermal
`
`decomposition is performed at a condition of temperature of 300 to 500°C,
`
`pressure of 5 to 10 mtorr.
`
`10
`
`15
`
`20
`
`25
`
`Page 11 of 13
`
`Page 11 of 13
`
`

`

`6.
`
`The method in accordance with claim 1, wherein said thermal annealing
`
`of the amorphous titanium ninide is performed in the atmosphere of nitrogen, at
`
`a temperature of 400 to 600°C.
`
`7.
`
`The method in accordance With claim 1, wherein said thermal annealing
`
`of the amorphous titanium nitride is performed in the atmosphere of nitrogen, at
`
`a temperature of 700 to 900°C for 10 to 30 seconds by rapid thermal annealing.
`
`10
`
`8.
`
`The method in accordance with claim 1, 3 or 4, wherein said metal layer
`
`is one selected from a group consisting of aluminum, copper and aluminum alloy
`
`and copper alloy.
`
`9.
`
`The method in accordance with claim 8, wherein said method further
`
`15
`
`comprises a step of forming a thin antireflective coating (arc) film on said metal
`
`layer for preventing reflection of light fiom said metal layer before said patterning
`
`step.
`
`10.
`
`The method in accordance with claim 9, wherein said arc-thin film is
`
`'20
`
`made of titanium.
`
`11.
`
`A method of forming a metal interconnect for a semiconductor device,
`
`comprising the steps of;
`
`forming a contact hole in an insulating layer formed on a semiconductor
`
`25
`
`substrate;
`
`I
`
`forming a titanium layer on the said insulating layer and in said contact
`
`hole by chemical vapor deposition; and
`
`forming a titanium nitride layer on said titanium layer, titanium nitride
`
`component of said titanium nitride layer being thermally decomposed from
`
`Page 12 of 13
`
`Page 12 of 13
`
`

`

`
`
`tetradimethylaminotitanimn.
`
`12.
`
`A method of forming a metal interconnect for a semiconductor device,
`
`comprising the steps of;
`
`forming a contact hole in an insulating layer formed on a semiconductor
`
`substrate;
`
`forming a titanium layer on the said insulating layer and in said contact
`
`hole by chemical vapor deposition; and
`
`forming a titanium nitride layer on said titanium layer, titanium nitride
`
`component of said titanium nitride layer being thermally decomposed from
`
`tetradiethylaminotitanium.
`
`13.
`
`The method in accordance with claim 11 or 12, wherein said annealing
`
`of the decomposition for the titanium nitride is performed at a temperature of 300
`
`to 500°C and a pressure of 5 to 10 mtorr.
`
`i
`
`10
`
`15
`
`14.
`
`The method in accordance with claims 11, 12 or 13, wherein said
`
`titanium nitride layer is in amorphous state, and further comprising the steps of:
`
`thermally annealing said substrate. in an atmosphere ofnitrogen whereby
`
`20
`
`a portion of said amorphous titanium nitride layer is transformed to crystalline
`
`titanium nitride layer;
`
`depositing a metal layer on the annealed titanium nitride layer; and
`
`patterning the titanium layer, the annealed titanium nitride layer and the
`
`metal layer formed on the contact hole and insulating layer.
`
`Page 13mof 13 ”
`
`
`Page 13 of 13
`
`