WO2016099437A1 - Method and apparatus for layer deposition on a substrate, and method for manufacturing a thin film transistor on a substrate - Google Patents
Method and apparatus for layer deposition on a substrate, and method for manufacturing a thin film transistor on a substrate Download PDFInfo
- Publication number
- WO2016099437A1 WO2016099437A1 PCT/US2014/070264 US2014070264W WO2016099437A1 WO 2016099437 A1 WO2016099437 A1 WO 2016099437A1 US 2014070264 W US2014070264 W US 2014070264W WO 2016099437 A1 WO2016099437 A1 WO 2016099437A1
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- WO
- WIPO (PCT)
- Prior art keywords
- substrate
- layer
- deposition
- metal oxynitride
- sputter target
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 273
- 239000000758 substrate Substances 0.000 title claims abstract description 154
- 230000008021 deposition Effects 0.000 title claims abstract description 100
- 239000010409 thin film Substances 0.000 title claims description 24
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 230000008569 process Effects 0.000 claims abstract description 210
- 238000000151 deposition Methods 0.000 claims abstract description 132
- 239000012298 atmosphere Substances 0.000 claims abstract description 123
- 229910052751 metal Inorganic materials 0.000 claims abstract description 100
- 239000002184 metal Substances 0.000 claims abstract description 100
- 230000003750 conditioning effect Effects 0.000 claims abstract description 49
- 238000005137 deposition process Methods 0.000 claims abstract description 34
- 239000013077 target material Substances 0.000 claims abstract description 14
- 239000007789 gas Substances 0.000 claims description 43
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims description 32
- 239000011261 inert gas Substances 0.000 claims description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 15
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 13
- 239000011701 zinc Substances 0.000 claims description 13
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 12
- 229910052725 zinc Inorganic materials 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 8
- 230000001143 conditioned effect Effects 0.000 claims description 8
- 229910000069 nitrogen hydride Inorganic materials 0.000 claims description 5
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- 239000001272 nitrous oxide Substances 0.000 claims description 4
- 230000007704 transition Effects 0.000 claims description 4
- 238000004544 sputter deposition Methods 0.000 description 21
- 239000002800 charge carrier Substances 0.000 description 18
- 239000000463 material Substances 0.000 description 18
- 239000000203 mixture Substances 0.000 description 11
- 230000003068 static effect Effects 0.000 description 10
- 238000000137 annealing Methods 0.000 description 8
- 238000000429 assembly Methods 0.000 description 8
- 230000000712 assembly Effects 0.000 description 8
- 238000005240 physical vapour deposition Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 6
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 230000005669 field effect Effects 0.000 description 4
- 239000012212 insulator Substances 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000001755 magnetron sputter deposition Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000002161 passivation Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 229910052814 silicon oxide Inorganic materials 0.000 description 3
- 229910004205 SiNX Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- -1 e.g. Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003574 free electron Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02172—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides
- H01L21/02175—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides characterised by the metal
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/0021—Reactive sputtering or evaporation
- C23C14/0036—Reactive sputtering
- C23C14/0042—Controlling partial pressure or flow rate of reactive or inert gases with feedback of measurements
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/0021—Reactive sputtering or evaporation
- C23C14/0036—Reactive sputtering
- C23C14/0057—Reactive sputtering using reactive gases other than O2, H2O, N2, NH3 or CH4
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/0676—Oxynitrides
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/08—Oxides
- C23C14/086—Oxides of zinc, germanium, cadmium, indium, tin, thallium or bismuth
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
- C23C14/352—Sputtering by application of a magnetic field, e.g. magnetron sputtering using more than one target
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
- H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
- H01L21/02266—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by physical ablation of a target, e.g. sputtering, reactive sputtering, physical vapour deposition or pulsed laser deposition
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66969—Multistep manufacturing processes of devices having semiconductor bodies not comprising group 14 or group 13/15 materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
- H01L29/7869—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
Definitions
- Embodiments of the present disclosure relate to a method and an apparatus for layer deposition on a substrate, and relate to a method for manufacturing a thin film transistor on a substrate and a thin film transistor manufactured therewith. Embodiments of the present disclosure particularly relate to a method and an apparatus for deposition of a metal oxynitride layer on a substrate.
- substrates may be coated by a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, or a plasma enhanced chemical vapor deposition (PECVD) process, etc.
- PVD physical vapor deposition
- CVD chemical vapor deposition
- PECVD plasma enhanced chemical vapor deposition
- the process can be performed in a process apparatus or process chamber in which the substrate to be coated is located.
- a deposition material is provided in the apparatus.
- a plurality of materials such as metals, also including oxides, nitrides or carbides thereof, may be used for deposition on a substrate.
- Coated materials may be used in several applications and in several technical fields.
- substrates for displays are often coated by a physical vapor deposition (PVD) process such as a sputtering process, e.g., to form thin film transistors (TFTs) on the substrate.
- PVD physical vapor deposition
- TFTs thin film transistors
- a method for layer deposition over a substrate includes conditioning a sputter target in metallic mode under a first process atmosphere, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere.
- an apparatus for layer deposition over a substrate includes a sputter target including a metal, wherein the sputter target is configured to be conditioned in metallic mode, and wherein the apparatus is configured to deposit a metal oxynitride layer over the substrate in a reactive deposition process.
- a method for manufacturing a thin film transistor on a substrate includes conditioning a sputter target in metallic mode, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer.
- a method for layer deposition over a process substrate utilizing a rotatable sputter target having a magnetron disposed with the rotatable target includes: conditioning the rotatable sputter target in an inert process atmosphere by positioning the magnetron away from a substrate deposition region; and depositing a metal oxynitride layer in an oxygen process atmosphere over the process substrate by positioning the magnetron towards the substrate deposition region.
- a thin film transistor includes a channel layer, wherein the channel layer includes a metal oxynitride layer deposited using the embodiments disclosed herein.
- Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. It includes method aspects for carrying out every function of the apparatus.
- FIG. 1 shows a flow chart of a method for layer deposition over a substrate according to embodiments described herein;
- FIG. 2 shows a schematic view of an apparatus for layer deposition over a substrate according to embodiments described herein;
- FIG. 3A shows a schematic view of an apparatus for layer deposition over a substrate according to further embodiments described herein;
- FIG. 3B shows a schematic view of the apparatus of FIG. 3 A with the deposition sources facing away from the substrate during conditioning in metallic mode;
- FIG. 4 shows a schematic view of a thin film transistor having a metal oxynitride layer as a channel layer according to the embodiments described herein;
- FIG. 5 shows a flow chart of a method for manufacturing a thin film transistor over a substrate according to embodiments described herein.
- Reactive deposition processes for example, deposition processes during which a metal is sputtered under an atmosphere condition including oxygen and nitrogen in order to deposit a metal oxynitride layer
- the deposited layers should have a high degree of purity and homogeneity, e.g., with respect to a composition or stoichiometry of the deposited material. This can be of particular interest when using the metal oxynitride layer as a channel layer of a thin film transistor (TFT).
- TFT thin film transistor
- impurities and/or an inhomogeneous or undetermined composition of the metal oxynitride layer may degrade electrical characteristics of the TFT, such as charge carrier mobility.
- Metal sputter targets such as zinc targets
- a surface of the metal sputter target can oxidize, resulting in reduced quality of the deposited layers, e.g., due to impurities and/or an inhomogeneous or undetermined composition of the deposited layers.
- the oxidizing zinc target can act as a carrier suppressor, leading to a degradation of a charge carrier mobility in the metal oxynitride layer, e.g., in the channel layer of the TFT.
- Embodiments described herein relate to a method and an apparatus for layer deposition on or over a substrate that can overcome or reduce the above shortcomings.
- Embodiments described herein relate in particular to a method and an apparatus for layer deposition on or over a substrate that provide an enhanced charge carrier mobility in a metal oxynitride layer, e.g., used as a channel layer in a TFT.
- FIG. 1 shows a flow chart of method 100 for layer deposition over a substrate according to embodiments described herein.
- the method 100 includes conditioning a sputter target in metallic mode under a first process atmosphere (block 110), wherein a target material of the sputter target includes a metal, and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere (block 120).
- a target material of the sputter target includes a metal
- depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere (block 120).
- the terms “conditioning” and "pre-sputtering” can be used synonymously.
- the term “conditioning” or “pre-sputtering” shall refer to processes which are conducted prior to depositing the metal oxynitride layer, and during which the substrate is not exposed to the sputter target.
- a conditioning can be provided after deposition has been paused.
- Deposition can be paused for maintenance but also for providing a further substrate in a deposition position.
- conditioning can be provided after maintenance.
- conditioning can be provided between deposition on or over a first substrate and a subsequent, second substrate.
- conditioning can be provided between deposition of a layer over a substrate and a subsequent deposition of a further layer over the substrate.
- an oxide layer such as a zinc oxide (ZnO) layer or a zinc oxynitride (ZnON) layer, can be removed from the sputter target before depositing the metal oxynitride layer over the substrate.
- the reactive deposition process can produce a metal oxynitride layer having improved electrical characteristics, such as enhanced charge carrier mobility.
- a comparably thin metal oxynitride layer can be deposited.
- the metal oxynitride layer can be deposited to have a layer thickness of less than 100 nm (nano meters), specifically less than 80 nm, and more specifically in the range of 40 to 60 nm.
- a reactive deposition process can have a hysteresis curve.
- the hysteresis curve can, for example, be a function of deposition parameters such as the voltage provided to the sputter target dependent on the flow of a process gas, such as oxygen and/or nitrogen.
- a process gas such as oxygen and/or nitrogen.
- a process gas such as oxygen and/or nitrogen.
- a process gas such as oxygen and/or nitrogen.
- a low process gas flow can be provided and a comparably high target voltage can be achieved.
- a high deposition rate can be provided.
- the deposition process turns into a poisoned mode, e.g., an oxygen mode.
- the deposition rate in oxygen mode can be lower than in metallic mode.
- a deposition process may also use a transition mode, where a layer can be deposited at the comparably high rate.
- the metallic mode is used for conditioning of the sputter target, i.e., before performing the deposition process for forming the metal oxynitride layer.
- the term "metallic mode” shall embrace modes where a sputter target including metal (also referred to as “metal sputter target”) is sputtered in a first process atmosphere that is different from a second process atmosphere in which the deposition of the metal oxynitride layer is conducted.
- the first process atmosphere can include an inert gas and a smaller amount of reactive gases such as oxygen and/or nitrogen as compared to the amount of reactive gases in the second process atmosphere.
- substrate as used herein shall embrace substrates which can be used for display manufacturing, such as glass or plastic substrates.
- substrates as described herein shall embrace substrates which can be used for an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an OLED (organic light emitting diode) display and the like.
- LCD Liquid Crystal Display
- PDP Plasma Display Panel
- OLED organic light emitting diode
- a large area substrate or carrier can be GEN 4.5, which corresponds to about 0.67 m 2 substrates (0.73x0.92m), GEN 5, which corresponds to about 1.4 m 2 substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m 2 substrates (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7m 2 substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m 2 substrates (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented.
- FIG. 2 shows a schematic view of an apparatus 200 for layer deposition on or over a substrate 220 according to embodiments described herein.
- the apparatus 200 includes a sputter target 210 including a metal, wherein the sputter target 210 is configured to be conditioned in metallic mode, and wherein the apparatus 200 is configured to deposit a metal oxynitride layer over the substrate 220 in a reactive deposition process.
- the deposition material can be present in the solid phase in the sputter target 210.
- atoms of the target material i.e. the material to be deposited
- the energetic particles for the sputtering process can be supplied by a plasma 230 formed between the sputter target 210 and the substrate 220.
- the atoms of the target material are deposited on or over the substrate 220 to be coated.
- the target material may be arranged in different ways.
- the sputter target 210 may be made from the target material or may have a backing element on which the target material is fixed.
- the sputter target 210 including the target material can be supported or fixed in a predefined position in a deposition chamber 240, such as a vacuum deposition chamber.
- a deposition chamber 240 such as a vacuum deposition chamber.
- the rotatable sputter target is connected to a rotating shaft or a connecting element connecting the shaft and the rotatable sputter target.
- Sputtering can be conducted as magnetron sputtering, wherein a magnet assembly is utilized to confine the plasma 230 for improved sputtering conditions.
- the plasma confinement can also be utilized for adjusting the particle distribution of the material to be deposited over the substrate 220.
- the apparatus 200 can have one or more gas inlets 250 and one or more gas outlets 260.
- the one or more gas inlets 250 can be configured for introducing one or more process gases into the deposition chamber 240.
- the one or more gas outlets 260 can be configured as exit ports for gases within the deposition chamber 240.
- the one or more gas inlets 250 and the one or more gas outlets 260 can provide a controlled process gas flow through the deposition chamber 240, and in particular through a deposition region.
- the one or more process gases can include at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N 2 ), ammonia (NH 3 ), oxygen (0 2 ), nitrous oxide (N 2 0), and any combination thereof.
- the metal is zinc.
- the target material or material to be deposited is zinc (“zinc target").
- the metal oxynitride layer can be a zinc oxynitride layer (ZnON layer).
- the metal can be doped with at least one dopant.
- the dopant can be selected from the group including Al, Ga, Sn and In.
- the apparatus 200 can be configured to implement the method for layer deposition according to the embodiments described herein. Conditioning the sputter target 210 in metallic mode is conducted in the first process atmosphere and depositing the metal oxynitride layer over the substrate 220 is conducted in the second process atmosphere.
- the first process atmosphere is different from the second process atmosphere.
- a composition of the first process atmosphere is different from a composition of the second process atmosphere.
- the first process atmosphere includes at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N 2 ), ammonia (NH 3 ), oxygen (0 2 ), nitrous oxide (N 2 0), and any combination thereof.
- an inert gas such as argon
- reactive gases such as nitrogen (N 2 ), ammonia (NH 3 ), oxygen (0 2 ), nitrous oxide (N 2 0), and any combination thereof.
- the first process atmosphere can be configured for the metallic mode.
- the first process atmosphere includes the inert gas.
- the inert gas is argon.
- a partial pressure of the inert gas in the first process atmosphere is in the range of 90% to 100% of a total pressure of the first process atmosphere, is in particular in the range of 98% to 100%, and more particularly about 100%.
- the first process atmosphere can include substantially only the inert gas.
- the first process atmosphere can be a substantially pure inert gas atmosphere.
- the term "substantially" may refer to cases where the first process atmosphere mainly contains the inert gas, and wherein trace elements e.g. of other gases or process gases such as oxygen and nitrogen can be present.
- the first process atmosphere including substantially only the inert gas can include some ppm (parts per million) of other gases, e.g., oxygen and/or nitrogen.
- the first process atmosphere can be generated using a gas flow of 50 to 150 seem (standard cubic centimeters per minute), and in particular about 100 seem, of one or more process gases, e.g., into the deposition chamber 240 and/or the deposition region.
- a process gas pressure of the first process atmosphere e.g. within the deposition chamber 240 or the deposition region can be in the range of 0.1 to 1 Pa, specifically in the range of 0.3 to 0.7 Pa, more specifically in the range of 0.5 to 0.6 Pa, and can for example be about 0.55 or about 0.56 Pa.
- a sputter target voltage during conditioning in metallic mode can be 100 to 1000 V, specifically 300 to 700 V, and more specifically about 500 V.
- a process power can be 100 to 1200 W, specifically 500 to 900 W, and more specifically about 700 W.
- the substrate 220 is not exposed to the sputter target 210 during conditioning of the sputter target 210 in metallic mode.
- the material deposition during conditioning or pre-sputtering is not conducted on the substrate 220 having a device, such as a thin film transistor, to be manufactured thereon.
- the apparatus for layer deposition can have one or more rotatable cathodes and optional magnet assemblies, as it is described below with reference to FIGs. 3A and 3B.
- the one or more cathodes or magnet assemblies can assume a first rotational position where the plasma is directed towards the substrate or a corresponding deposition area.
- the deposition of the metal oxynitride layer can be conducted with the one or more cathodes or magnet assemblies being in the first rotational position.
- the one or more cathodes or magnet assemblies can assume a second rotational position where the plasma is facing away from the substrate.
- the conditioning of the sputter target in metallic mode can be conducted with the one or more cathodes or magnet assemblies being in the second rotational position.
- the plasma In the second position, the plasma can, for example, be directed to a shield adapted for collecting material to be sputtered while the plasma is directed towards the shield.
- a dummy substrate or the like can be positioned between either the substrate to be coated or a susceptor heater and the sputter target during conditioning of the sputter target in metallic mode.
- the material deposition during conditioning or pre-sputtering is not conducted on the substrate having a device to be manufactured thereon, rather the dummy substrate.
- Providing one or more magnet assemblies of the rotatable cathode in a second rotational position, wherein the plasma is facing away from the substrate, as described above, has the advantage of not having a dummy substrate, e.g. for each conditioning procedure.
- having a dummy substrate prior to each process substrate would significantly reduce thorough-put.
- not having a dummy substrate greatly simplifies the routing of substrates in an inline or cluster deposition system.
- the substrate 220 can be provided within the vacuum chamber 302 while the sputter target is facing away from the substrate 220.
- the conditioning of the sputter target in metallic mode can be conducted with the one or more cathodes or magnet assemblies being in the second rotational position.
- not providing a dummy substrate for target conditioning e.g. according to embodiments including a magnetron position in a second rotation position, e.g. facing away from a substrate receiving area, may even reduce the tact time of a system.
- the substrates can be unloaded and loaded from the vacuum chamber while the one or more targets are condition. Accordingly, an overlap of a time period for routing of substrates into and out of the vacuum chamber and a time period of conditioning one or more targets can be realized.
- the second process atmosphere can be configured for a deposition mode.
- the deposition mode can be the transition mode.
- depositing the metal oxynitride layer on or over the substrate is conducted in transition mode.
- the second process atmosphere includes at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N 2 ), ammonia (NH 3 ), oxygen (0 2 ) and/or nitrous oxide (N 2 0).
- a composition of the second process atmosphere can be selected according to a composition or stoichiometry of the layer that is to be deposited over the substrate, such as a composition or stoichiometry of the metal oxynitride layer or a metal oxynitride sub-layer of the metal oxynitride layer.
- the first process atmosphere can include less reactive gases than those the second process atmosphere can include.
- a partial pressure of the one or more reactive gases in the first process atmosphere is less than a partial pressure of the one or more reactive gases in the second process atmosphere.
- the partial pressure of the one or more reactive gases in the first process atmosphere can be a total partial pressure of all reactive gases of the first process atmosphere.
- the partial pressure of the one or more reactive gases in the second process atmosphere can be a total partial pressure of all reactive gases of the second process atmosphere.
- the total partial pressure can correspond to a sum of the partial pressures of the reactive gases in the respective process atmosphere.
- the first process atmosphere can include the inert gas and a smaller amount of at least one of the one or more reactive gases compared to the second process atmosphere.
- the second process atmosphere can be an "actual recipe atmosphere".
- actual recipe atmosphere can refer to an atmosphere having a composition that is configured for depositing the metal oxynitride layer or a metal oxynitride layer sub-layer of the metal oxynitride layer over the substrate 220.
- the first process atmosphere can be provided within the deposition chamber 240, and the conditioning or pre-sputtering in metallic mode can be performed.
- the substrate 220 is not exposed to the sputter target 210 during conditioning or pre-sputtering in metallic mode. This can be achieved, for example, by a rotation of a cathode including the sputter target 210 or by a rotation of a magnet assembly provided at, or in, the cathode such that the plasma 230 is facing away from the substrate 220.
- an oxide layer e.g., a ZnO layer or a ZnON layer
- the second process atmosphere is provided, for example the first process atmosphere can be replaced by the second process atmosphere.
- the substrate 220 can be exposed to material deposited from the sputter target 210.
- a rotation of the cathode including the sputter target 210 or by a rotation of the magnet assembly such that the plasma 230 is facing towards the substrate 220 can be provided.
- Depositing of the metal oxynitride layer over the substrate 220 in a reactive deposition process can be performed in the second process atmosphere.
- the reactive deposition process is conducted to provide a stoichiometry, for example a predetermined stoichiometry, of the material to be deposited onto the substrate 220 until the end of the deposition. For example, this can be the correct stoichiometry for Zn x O y N z deposition.
- depositing the metal oxynitride layer over the substrate 220 includes depositing two or more metal oxynitride sub-layers to form the metal oxynitride layer.
- depositing the metal oxynitride layer over the substrate 220 can include depositing four metal oxynitride sub-layers to form the metal oxynitride layer.
- characteristics of the metal oxynitride layer such as charge carrier mobility, can be adjusted.
- different process powers, process times and/or second process atmospheres can be used for deposition of the two or more metal oxynitride sub-layers.
- the two or more metal oxynitride sub-layers can have different thicknesses. Examples are given with reference to FIGs. 4 and 5.
- the apparatus 200 can be configured for processing the substrate 220 in a substantially vertical orientation.
- substantially vertical is understood particularly when referring to the substrate orientation, to allow for a deviation from the vertical direction of 20° or below, e.g. of 10° or below. This deviation can be provided for example because a substrate support with some deviation from the vertical orientation might result in a more stable substrate position.
- the substrate orientation during layer deposition is considered substantially vertical, which is considered different from the horizontal substrate orientation.
- a method for layer deposition over a process substrate utilizing a rotatable sputter target having a magnetron disposed with the rotatable target includes: conditioning the rotatable sputter target in an inert process atmosphere by positioning the magnetron away from a substrate deposition region; and depositing a metal oxynitride layer in an oxygen process atmosphere over the process substrate by positioning the magnetron towards the substrate deposition region.
- the method can be combined with any one of the features or feature groups described herein with reference to FIGs. 1 to 5.
- FIG. 3A shows a schematic view of an apparatus 300 for layer deposition on or over a substrate 220 according to further embodiments described herein.
- FIG. 3B shows a schematic view of the apparatus of FIG. 3A with the one or more deposition sources, and in particular one or more cathodes 324 of the one or more deposition sources, facing away from the substrate 220 during conditioning in metallic mode.
- one vacuum chamber 302 for deposition of layers therein is shown.
- Further vacuum chambers 303 can be provided adjacent to the vacuum chamber 302.
- the vacuum chamber 302 can be separated from adjacent further vacuum chambers 303 by a valve having a valve housing 304 and a valve unit 305.
- the valve unit 305 can be closed.
- the atmosphere in the vacuum chambers 302, such as the first process atmosphere and/or the second process atmosphere can be individually controlled by generating a technical vacuum, for example, with vacuum pumps connected to the vacuum chamber 302, and/or by inserting one or more process gases in the deposition region in the vacuum chamber 302.
- the one or more process gases can include the gases for creating the first process atmosphere and the second process atmosphere according to the embodiments described herein.
- rollers 310 can be provided in order to transport the carrier 314, having the substrate 220 thereon, into and out of the vacuum chamber 302.
- a deposition source of the one or more deposition sources can include one or more cathodes 324 and one or more anodes 326.
- the one or more cathodes 324 can be rotatable cathodes having the sputter targets of the material to be deposited on the substrate 220.
- the one or more cathodes 324 can have a magnet assembly therein, and magnetron sputtering can be conducted for depositing of the layers.
- the one or more cathodes 324 and the one or more anodes 326 can be electrically connected to a DC power supply 328.
- the one or more cathodes 324 can be rotated simultaneously towards the substrate 220 for exposure thereof.
- Sputtering for forming the metal oxynitride layer can be conducted as DC sputtering.
- the one or more cathodes 324 are connected to the DC power supply 328 together with the one or more anodes 326 for collecting electrons during sputtering.
- at least one of the one or more cathodes 324 can have its corresponding, individual DC power supply.
- magnet sputtering refers to sputtering performed using a magnetron or magnet assembly, i.e., a unit capable of generating a magnetic field.
- a magnet assembly consists of one or more permanent magnets. These permanent magnets can be arranged within a rotatable sputter target or coupled to a planar sputter target in a manner such that the free electrons are trapped within the generated magnetic field generated below the rotatable target surface.
- Such a magnet assembly may also be arranged coupled to a planar cathode.
- sputtering can be conducted as DC (direct current) sputtering.
- other sputtering methods such as MF (middle frequency) sputtering, RF (radio frequency) sputtering, or pulse sputtering can also be applied.
- FIGs. 3A and 3B show a plurality of deposition sources, wherein a deposition source includes one cathode 324 and one anode 326. Particularly for applications for large area deposition, an array of deposition sources can be provided within the vacuum chamber 302.
- the one or more cathodes 324 (and/or the magnet assemblies or magnetrons arranged therein) can have the same or different rotational positions within the vacuum chamber 302.
- the one or more cathodes 324 can have essentially the same rotational positions or can at least all be directed towards the substrate 220 or a corresponding deposition area.
- the deposition area can be an area or region with a deposition system, which is provided and/or arranged for the deposition (the intended deposition) of the material on the substrate 220.
- the one or more cathodes 324 can assume a rotational position in which the plasma 2 is directed towards the substrate 220 or the corresponding deposition area (FIG. 3A).
- the one or more cathodes 324 can assume another rotational position in which the plasma 2 is facing away from the substrate 220 (FIG. 3B).
- the plasma 2 can, for example, be directed to a shield (not shown) adapted for collecting material to be sputtered while the plasma 2 is directed towards the shield.
- the methods provide a sputter deposition for a static deposition process or a dynamic deposition process.
- a static deposition process can be provided, e.g., for TFT processing, wherein conditioning the sputter target in metallic mode can be conducted prior to deposition of the metal oxynitride layer over the substrate 220.
- a static deposition process can include, for example, at least one of the following: a static substrate position during deposition; an oscillating substrate position during deposition; an average substrate position that is essentially constant during deposition; a dithering substrate position during deposition; a wobbling substrate position during deposition; a deposition process for which the cathodes are provided in one deposition chamber, i.e. a predetermined set of cathodes are provided in the deposition chamber; a substrate position wherein the deposition chamber has a sealed atmosphere with respect to neighboring chambers, e.g.
- a static deposition process can be understood as a deposition process with a static position, a deposition process with an essentially static position, or a deposition process with a partially static position of the substrate.
- a static deposition process in which the substrate position can in some cases be not fully without any movement during deposition, can still be distinguished from a dynamic deposition process.
- the metal oxynitride layer implemented in TFTs has four metal oxynitride sub-layers, i.e., a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer that are deposited on each other in this order.
- the first sub-layer was deposited with a first process power, a first process time, and under a first sub-layer process atmosphere.
- the second sub-layer was deposited with a second process power, a second process time, and under a second sub-layer process atmosphere.
- the third sub-layer was deposited with a third process power, a third process time, and under a third sub-layer process atmosphere.
- the fourth sub-layer was deposited with a fourth process power, a fourth process time, and under a fourth sub-layer process atmosphere.
- a ZnON layer of about 100 nm was deposited.
- the first sublayer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included at least in part different amounts of Ar (argon), N 2 and N 2 0.
- the fourth sub-layer was deposited to have a layer thickness of about 80 nm.
- the sputter target was conditioned in the actual recipe mode explained with reference to FIG. 2.
- the first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 300 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the ZnON layer of the first example was then annealed for about 1 hour at about 350°C and 60 to 160 Pa.
- I on refers to a source-drain current when the TFT is switched on
- I 0ff refers to a source-drain current when the TFT is switched off
- Mo refers to a field effect mobility in units of m 2 /(V*s)
- S refers to a sub threshold slope in units of mV/decade
- V on (10V) refers to a source-drain voltage when a potential of 10 V is applied to the gate electrode
- V on (0.1V) refers to a source-drain voltage when a potential of 0.1 V is applied to the gate electrode.
- Second example Thick ZnON (second comparative example)
- a ZnON layer of about 100 nm was deposited.
- the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sublayer process atmosphere included, at least in part, different amounts of Ar, N 2 and N 2 0, similar to those used in the first example.
- the first sub-layer process atmosphere included only Ar.
- the sputter target was conditioned in the actual recipe mode.
- the first sub-layer was deposited with a first process power of about 250 W, a first process time of about 12 s, and under a first sub-layer process atmosphere created by 100 seem of Ar.
- the second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the third sublayer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 300 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the ZnON layer of the second example was then annealed for about 1 hour at about 350°C and 60 to 160 Pa.
- a ZnON layer was deposited.
- the third example is similar to the first example with the difference being that a layer thickness of the fourth sub-layer was reduced to about 45 nm.
- the first sub-layer, the second sub-layer and the third sublayer of the third example were similar to the first sub-layer, the second sub-layer and the third sub-layer of the first example, respectively.
- the first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included, at least in part, different amounts of Ar, N 2 and N 2 0.
- the sputter target was conditioned in the actual recipe mode.
- the first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 138 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the ZnON layer of the third example was then annealed for about 1 hour at about 300°C and 60 to 160 Pa.
- the third example showed a lower S and a more positive V on (10V).
- the field effect mobility was significantly degraded. This may result from an oxidizing zinc target that acts as a carrier suppressor.
- charge carrier mobility decreases, a source resistance R s increases, and Nb (bulk charge carrier concentration) decreases.
- a ZnON layer was deposited using the method according to the present disclosure.
- the first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included, at least in part, different amounts of Ar (argon), N 2 and N 2 0.
- the fourth sub-layer was deposited to have a layer thickness of about 45 nm.
- the sputter target was conditioned in metallic mode.
- the first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere can each be understood as the second process atmosphere of the embodiments described herein.
- the target conditioning in metallic mode was performed under the first process atmosphere.
- the first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N 2 , and 5 seem of N 2 0.
- the fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 138 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N 2 , and 12 seem of N 2 0.
- the ZnON layer of the fourth example was then annealed for about 1 hour at about 300°C and 60 to 160 Pa.
- the ZnON layer according to the present disclosure has high charge carrier mobility. Further, also characteristics such as I on , I 0ff , S, and field effect mobility are improved. In other words, a lower quality of the (thinner) metallic mode ZnON layer has a better TFT performance than the TFTs of the comparative examples where the sputter target was conditioned in the actual recipe mode.
- the thick ZnON film is hard to improve.
- the tradeoffs are considerable.
- I 0 ff, S, and V on are deteriorated.
- the zinc target can become oxidized and can deteriorate the charge carrier mobility considerably.
- a ZnON layer deposited after conditioning in metallic mode can provide high field effect mobility with more positive V on , better S and l 0 s of the TFT, when compared with the actual recipe mode (non-metallic mode) conditioning.
- the conditioning in metallic mode as in the first process atmosphere only Ar can be used, or Ar with N 2 and NH 3 , or Ar with a low flow of N 2 0 or 0 2 gas.
- FIG. 4 shows a schematic view of a thin film transistor 400 manufactured according to the embodiments described herein.
- FIG. 5 shows a flow chart 500 of a method for manufacturing a thin film transistor (TFT) on a substrate according to embodiments described herein, and in particular the thin film transistor 400 of FIG. 4.
- TFT thin film transistor
- the TFT according to the embodiments described herein can for example be used in display devices, such as liquid crystal displays (LCDs) and/or organic light emitting diode (OLED) displays.
- LCDs liquid crystal displays
- OLED organic light emitting diode
- the method for manufacturing a thin film transistor (TFT) on (or over) a substrate includes conditioning a sputter target in metallic mode, wherein a target material of the sputter target includes a metal, and depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer.
- a target material of the sputter target includes a metal
- depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer.
- the terms “on” or “over” are used to define an order of layers, layer stacks, and/or films wherein the starting point can be the substrate. This is irrespective of whether the layer stack is depicted upside down or not.
- the term “over” should include embodiments where one or more additional layers are provided between the one layer and the other layer.
- the term “on” should include embodiments where no additional layers are provided between the one layer and the other layer, i.e., the one layer and the other layer are directly disposed on each other, or, in other words, are in contact with each other.
- a gate electrode 420 is formed on or over a TFT substrate 410.
- the TFT substrate 410 can be a glass substrate.
- the gate electrode 420 can be deposited using a PVD process.
- the gate electrode 420 can include a metal.
- the metal can be selected from the group including Cr, Cu, Mo, Ti, and any combination thereof.
- the metal can also be a metal stack including two or more of the metals selected from the group including Cr, Cu, Mo, Ti, and any combination thereof.
- the gate electrode can have a thickness of about 150 nm.
- a gate insulator 430 is formed at least over the gate electrode 420, e.g., by a PECVD process.
- the gate insulator can include at least one of SiN x and SiO y .
- the gate insulator can have at least two sub-layers, e.g., at least one SiN x layer (e.g., about 300 nm) and at least one SiO y layer (e.g., about 50 nm).
- a channel layer 440 is formed on or over the gate insulator 430.
- the methods and apparatuses for layer deposition described with reference to FIGs. 1 to 3 can be implemented to form the channel layer 440 of the TFT 400.
- the channel layer 440 can be a ZnON layer.
- the channel layer 440 has improved electrical characteristics, such as enhanced charge carrier mobility.
- 100 seem of Ar can be used for the first process atmosphere for conditioning in metallic mode.
- a process gas pressure of the first process atmosphere within the deposition chamber can be in the range of 0.5 to 0.6 Pa, and can for example be about 0.55 or about 0.56 Pa.
- a sputter target voltage during conditioning in metallic mode can be about 500 V.
- a process power can be about 700 W.
- a dummy substrate can be used during the conditioning.
- Deposition of the metal oxynitride layer, e.g., ZnON can be conducted at about 50°C.
- a first annealing process can be performed, e.g., under vacuum and/or a nitrogen (N 2 ) atmosphere.
- the first annealing process can change characteristics of the channel layer 440, e.g., at least one of a chemical composition, a crystallinity, and a charge carrier concentration.
- the first annealing process can for example be conducted under at least one of the following conditions: at about 300°C, for about 1 hour and under a nitrogen atmosphere (e.g., about 60 Pa to about 160 Pa).
- the conditions can for example be used for thin metal oxynitride layers, such as for metal oxynitride layers having a layer thickness of about 50 nm.
- a first etching process is performed, e.g., an island wet etching process.
- the first etching process can for example be conducted under at least one of the following conditions: with about 0.1 % HCL, for about 4 s to 12 s (e.g., for a layer thickness of about 80 nm), and at room temperature.
- a second annealing process can be performed, e.g., under ambient atmosphere (e.g., air).
- the second annealing process can change characteristics of the channel layer 440, e.g., at least one of a chemical composition, a crystallinity, and a charge carrier concentration.
- the second annealing process can for example be conducted in an oven under at least one of the following conditions: at a temperature in a range from about 200°C to about 300°C and for about 30 min.
- an etch stopper 450 e.g., of SiO x , is formed on the channel layer 440, e.g., by a PECVD process.
- the etch stopper 450 can be formed to have a thickness of about 100 nm.
- the PECVD process can for example be conducted under at least one of the following conditions: at about 200°C and under a process atmosphere pressure in a range of e.g., 50 to 300 Pa, specifically in a range of 80 to 250 Pa, and more specifically in a range of about 160 to about 170 Pa.
- a source electrode 460 and a drain electrode 470 are formed on the channel layer 440, e.g., by a PVD process.
- the source electrode 460 and the drain electrode 470 can be made of a metal, e.g., with a thickness of about 200 nm.
- the metal can be selected from the group including Cr, Cu, Mo, Ti, and any combination thereof.
- the metal can also be a metal stack including two or more of the metals selected from the group including Cr, Cu, Mo, Ti, and any combination thereof.
- a passivation process is performed to form a passivation layer 480 at least over the source electrode 460 and the drain electrode 470.
- the passivation layer 480 can for example be formed by a PECVD process.
- a third annealing process (TFT anneal) can be performed.
- the third annealing process can for example be conducted under at least one of the following conditions: at about 250°C, for about 30 min, under nitrogen atmosphere, and at a process atmosphere pressure of e.g., about 260 to about 270 Pa.
- the thin film transistor 400 includes the channel layer 440, wherein the channel layer 440 includes, or is, the metal oxynitride layer deposited using the embodiments disclosed herein.
- oxidized material e.g., an oxide layer such as a zinc oxide (ZnO) layer or a zinc oxynitride (ZnON) layer
- ZnO zinc oxide
- ZnON zinc oxynitride
- the reactive deposition process can produce a metal oxynitride layer having improved electrical characteristics, such as enhanced charge carrier mobility.
- the method for layer deposition on or over a substrate and the method for manufacturing a thin film transistor on or over a substrate can be conducted by means of computer programs, software, computer software products and the interrelated controllers, which can have a CPU, a memory, a user interface, and input and output means being in communication with the corresponding components of the apparatus for processing a large area substrate.
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Abstract
A method for layer deposition over a substrate is provided. The method includes conditioning a sputter target in metallic mode under a first process atmosphere, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere.
Description
METHOD AND APPARATUS FOR LAYER DEPOSITION ON A SUBSTRATE, AND METHOD FOR MANUFACTURING A THIN FILM TRANSISTOR ON A
SUBSTRATE
FIELD
[0001] Embodiments of the present disclosure relate to a method and an apparatus for layer deposition on a substrate, and relate to a method for manufacturing a thin film transistor on a substrate and a thin film transistor manufactured therewith. Embodiments of the present disclosure particularly relate to a method and an apparatus for deposition of a metal oxynitride layer on a substrate.
BACKGROUND
[0002] Several methods are known for depositing a material on a substrate. For instance, substrates may be coated by a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, or a plasma enhanced chemical vapor deposition (PECVD) process, etc. The process can be performed in a process apparatus or process chamber in which the substrate to be coated is located. A deposition material is provided in the apparatus. A plurality of materials such as metals, also including oxides, nitrides or carbides thereof, may be used for deposition on a substrate. Coated materials may be used in several applications and in several technical fields. For instance, substrates for displays are often coated by a physical vapor deposition (PVD) process such as a sputtering process, e.g., to form thin film transistors (TFTs) on the substrate.
[0003] With development of new display technologies and a tendency towards larger display sizes, there is an ongoing demand for layers or layer systems used in displays that provide an improved performance, e.g., with respect to electrical characteristics and/or optical characteristics. As an example, layers for manufacturing of thin film transistors having improved electrical characteristics, such as enhanced charge carrier mobility, are beneficial. In particular, channel layers for thin film transistors having high charge carrier mobility are beneficial.
[0004] In view of the above, it is beneficial to provide methods and apparatuses that allow for deposition of layers with improved electrical characteristics. It is in particular beneficial to provide methods and apparatuses that allow for manufacturing of layers having high charge carrier mobility.
SUMMARY
[0005] In light of the above, a method for layer deposition on a substrate, an apparatus for layer deposition on a substrate, a method for manufacturing a thin film transistor on a substrate, and a thin film transistor manufactured therewith are provided. Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings
[0006] According to an aspect of the present disclosure, a method for layer deposition over a substrate is provided. The method includes conditioning a sputter target in metallic mode under a first process atmosphere, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere.
[0007] According to another aspect of the present disclosure, an apparatus for layer deposition over a substrate is provided. The apparatus includes a sputter target including a metal, wherein the sputter target is configured to be conditioned in metallic mode, and wherein the apparatus is configured to deposit a metal oxynitride layer over the substrate in a reactive deposition process.
[0008] According to still another aspect of the present disclosure, a method for manufacturing a thin film transistor on a substrate is provided. The method includes conditioning a sputter target in metallic mode, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer.
[0009] According to another aspect of the present disclosure, a method for layer deposition over a process substrate utilizing a rotatable sputter target having a magnetron disposed with the rotatable target is provided. The method includes: conditioning the
rotatable sputter target in an inert process atmosphere by positioning the magnetron away from a substrate deposition region; and depositing a metal oxynitride layer in an oxygen process atmosphere over the process substrate by positioning the magnetron towards the substrate deposition region.
[0010] According to yet another aspect of the present disclosure, a thin film transistor is provided. The thin film transistor includes a channel layer, wherein the channel layer includes a metal oxynitride layer deposited using the embodiments disclosed herein.
[0011] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. It includes method aspects for carrying out every function of the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:
FIG. 1 shows a flow chart of a method for layer deposition over a substrate according to embodiments described herein;
FIG. 2 shows a schematic view of an apparatus for layer deposition over a substrate according to embodiments described herein;
FIG. 3A shows a schematic view of an apparatus for layer deposition over a substrate according to further embodiments described herein;
FIG. 3B shows a schematic view of the apparatus of FIG. 3 A with the deposition sources facing away from the substrate during conditioning in metallic mode;
FIG. 4 shows a schematic view of a thin film transistor having a metal oxynitride layer as a channel layer according to the embodiments described herein; and
FIG. 5 shows a flow chart of a method for manufacturing a thin film transistor over a substrate according to embodiments described herein.
DETAILED DESCRIPTION OF EMBODIMENTS
[0013] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.
[0014] Reactive deposition processes, for example, deposition processes during which a metal is sputtered under an atmosphere condition including oxygen and nitrogen in order to deposit a metal oxynitride layer, can in some cases be subject to some conditions. In particular, the deposited layers should have a high degree of purity and homogeneity, e.g., with respect to a composition or stoichiometry of the deposited material. This can be of particular interest when using the metal oxynitride layer as a channel layer of a thin film transistor (TFT). As an example, impurities and/or an inhomogeneous or undetermined composition of the metal oxynitride layer may degrade electrical characteristics of the TFT, such as charge carrier mobility.
[0015] Metal sputter targets, such as zinc targets, can be subject to an oxidation process. In other words, a surface of the metal sputter target can oxidize, resulting in reduced quality of the deposited layers, e.g., due to impurities and/or an inhomogeneous or undetermined composition of the deposited layers. As an example, the oxidizing zinc target can act as a carrier suppressor, leading to a degradation of a charge carrier mobility in the metal oxynitride layer, e.g., in the channel layer of the TFT.
[0016] Embodiments described herein relate to a method and an apparatus for layer deposition on or over a substrate that can overcome or reduce the above shortcomings. Embodiments described herein relate in particular to a method and an apparatus for layer deposition on or over a substrate that provide an enhanced charge carrier mobility in a metal oxynitride layer, e.g., used as a channel layer in a TFT.
[0017] FIG. 1 shows a flow chart of method 100 for layer deposition over a substrate according to embodiments described herein. The method 100 includes conditioning a sputter target in metallic mode under a first process atmosphere (block 110), wherein a target material of the sputter target includes a metal, and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere (block 120). In some implementations, the terms "conditioning" and "pre-sputtering" can be used synonymously. The term "conditioning" or "pre-sputtering" shall refer to processes which are conducted prior to depositing the metal oxynitride layer, and during which the substrate is not exposed to the sputter target. According to some embodiments, a conditioning can be provided after deposition has been paused. Deposition can be paused for maintenance but also for providing a further substrate in a deposition position. Accordingly, for example, conditioning can be provided after maintenance. Yet further, conditioning can be provided between deposition on or over a first substrate and a subsequent, second substrate. According to yet further examples, additionally or alternatively, conditioning can be provided between deposition of a layer over a substrate and a subsequent deposition of a further layer over the substrate.
[0018] By conditioning the sputter target in metallic mode, an oxide layer, such as a zinc oxide (ZnO) layer or a zinc oxynitride (ZnON) layer, can be removed from the sputter target before depositing the metal oxynitride layer over the substrate. The reactive deposition process can produce a metal oxynitride layer having improved electrical
characteristics, such as enhanced charge carrier mobility. In order to further improve electrical characteristics, e.g., charge carrier mobility, a comparably thin metal oxynitride layer can be deposited. As an example, the metal oxynitride layer can be deposited to have a layer thickness of less than 100 nm (nano meters), specifically less than 80 nm, and more specifically in the range of 40 to 60 nm.
[0019] A reactive deposition process can have a hysteresis curve. The hysteresis curve can, for example, be a function of deposition parameters such as the voltage provided to the sputter target dependent on the flow of a process gas, such as oxygen and/or nitrogen. In metallic mode, a low process gas flow can be provided and a comparably high target voltage can be achieved. For the metallic mode being used in a deposition process, a high deposition rate can be provided. For higher process gas flow rates, the deposition process turns into a poisoned mode, e.g., an oxygen mode. The deposition rate in oxygen mode can be lower than in metallic mode. A deposition process may also use a transition mode, where a layer can be deposited at the comparably high rate. According to the embodiments described herein, the metallic mode is used for conditioning of the sputter target, i.e., before performing the deposition process for forming the metal oxynitride layer.
[0020] According to some embodiments, which can be combined with other embodiments described herein, the term "metallic mode" shall embrace modes where a sputter target including metal (also referred to as "metal sputter target") is sputtered in a first process atmosphere that is different from a second process atmosphere in which the deposition of the metal oxynitride layer is conducted. As an example, the first process atmosphere can include an inert gas and a smaller amount of reactive gases such as oxygen and/or nitrogen as compared to the amount of reactive gases in the second process atmosphere.
[0021] The term "substrate" as used herein shall embrace substrates which can be used for display manufacturing, such as glass or plastic substrates. For example, substrates as described herein shall embrace substrates which can be used for an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an OLED (organic light emitting diode) display and the like.
[0022] The embodiments described herein can in particular be utilized for deposition on or over large area substrates. As an example, a large area substrate or carrier can be GEN 4.5, which corresponds to about 0.67 m2 substrates (0.73x0.92m), GEN 5, which corresponds to about 1.4 m2 substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m2 substrates (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7m2 substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m2 substrates (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented.
[0023] FIG. 2 shows a schematic view of an apparatus 200 for layer deposition on or over a substrate 220 according to embodiments described herein.
[0024] The apparatus 200 includes a sputter target 210 including a metal, wherein the sputter target 210 is configured to be conditioned in metallic mode, and wherein the apparatus 200 is configured to deposit a metal oxynitride layer over the substrate 220 in a reactive deposition process.
[0025] For a PVD process, the deposition material can be present in the solid phase in the sputter target 210. By bombarding the sputter target 210 with energetic particles, atoms of the target material, i.e. the material to be deposited, are ejected from the sputter target 210. The energetic particles for the sputtering process can be supplied by a plasma 230 formed between the sputter target 210 and the substrate 220. The atoms of the target material are deposited on or over the substrate 220 to be coated. In a PVD process, the target material may be arranged in different ways. For instance, the sputter target 210 may be made from the target material or may have a backing element on which the target material is fixed. The sputter target 210 including the target material can be supported or fixed in a predefined position in a deposition chamber 240, such as a vacuum deposition chamber. In the case where a rotatable sputter target is used, the rotatable sputter target is connected to a rotating shaft or a connecting element connecting the shaft and the rotatable sputter target. Sputtering can be conducted as magnetron sputtering, wherein a magnet assembly is utilized to confine the plasma 230 for improved sputtering conditions. The plasma confinement can also be utilized for adjusting the particle distribution of the material to be deposited over the substrate 220.
[0026] According to some embodiments, the apparatus 200 can have one or more gas inlets 250 and one or more gas outlets 260. The one or more gas inlets 250 can be configured for introducing one or more process gases into the deposition chamber 240. The one or more gas outlets 260 can be configured as exit ports for gases within the deposition chamber 240. The one or more gas inlets 250 and the one or more gas outlets 260 can provide a controlled process gas flow through the deposition chamber 240, and in particular through a deposition region. The one or more process gases can include at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N2), ammonia (NH3), oxygen (02), nitrous oxide (N20), and any combination thereof.
[0027] According to embodiments described herein, which can be combined with other embodiments described herein, the metal is zinc. In other words, the target material or material to be deposited is zinc ("zinc target"). The metal oxynitride layer can be a zinc oxynitride layer (ZnON layer). In some implementations, the metal can be doped with at least one dopant. The dopant can be selected from the group including Al, Ga, Sn and In.
[0028] The apparatus 200 can be configured to implement the method for layer deposition according to the embodiments described herein. Conditioning the sputter target 210 in metallic mode is conducted in the first process atmosphere and depositing the metal oxynitride layer over the substrate 220 is conducted in the second process atmosphere. In some implementations, the first process atmosphere is different from the second process atmosphere. As an example, a composition of the first process atmosphere is different from a composition of the second process atmosphere.
[0029] According to some embodiments, which can be combined with other embodiments described herein, the first process atmosphere includes at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N2), ammonia (NH3), oxygen (02), nitrous oxide (N20), and any combination thereof.
[0030] The first process atmosphere can be configured for the metallic mode. In some embodiments, the first process atmosphere includes the inert gas. As an example, the inert gas is argon. In some implementations, a partial pressure of the inert gas in the first process atmosphere is in the range of 90% to 100% of a total pressure of the first process atmosphere, is in particular in the range of 98% to 100%, and more particularly about
100%. As an example, the first process atmosphere can include substantially only the inert gas. In other words, the first process atmosphere can be a substantially pure inert gas atmosphere. The term "substantially" may refer to cases where the first process atmosphere mainly contains the inert gas, and wherein trace elements e.g. of other gases or process gases such as oxygen and nitrogen can be present. As an example, the first process atmosphere including substantially only the inert gas can include some ppm (parts per million) of other gases, e.g., oxygen and/or nitrogen.
[0031] In some implementations, the first process atmosphere can be generated using a gas flow of 50 to 150 seem (standard cubic centimeters per minute), and in particular about 100 seem, of one or more process gases, e.g., into the deposition chamber 240 and/or the deposition region. A process gas pressure of the first process atmosphere e.g. within the deposition chamber 240 or the deposition region can be in the range of 0.1 to 1 Pa, specifically in the range of 0.3 to 0.7 Pa, more specifically in the range of 0.5 to 0.6 Pa, and can for example be about 0.55 or about 0.56 Pa. A sputter target voltage during conditioning in metallic mode can be 100 to 1000 V, specifically 300 to 700 V, and more specifically about 500 V. A process power can be 100 to 1200 W, specifically 500 to 900 W, and more specifically about 700 W.
[0032] According to some embodiments, which can be combined with other embodiments described herein, the substrate 220 is not exposed to the sputter target 210 during conditioning of the sputter target 210 in metallic mode. In other words, the material deposition during conditioning or pre-sputtering is not conducted on the substrate 220 having a device, such as a thin film transistor, to be manufactured thereon.
[0033] As an example, the apparatus for layer deposition can have one or more rotatable cathodes and optional magnet assemblies, as it is described below with reference to FIGs. 3A and 3B. The one or more cathodes or magnet assemblies can assume a first rotational position where the plasma is directed towards the substrate or a corresponding deposition area. The deposition of the metal oxynitride layer can be conducted with the one or more cathodes or magnet assemblies being in the first rotational position. In some implementations, the one or more cathodes or magnet assemblies can assume a second rotational position where the plasma is facing away from the substrate. The conditioning of the sputter target in metallic mode can be conducted with the one or more cathodes or
magnet assemblies being in the second rotational position. In the second position, the plasma can, for example, be directed to a shield adapted for collecting material to be sputtered while the plasma is directed towards the shield.
[0034] In another example, a dummy substrate or the like can be positioned between either the substrate to be coated or a susceptor heater and the sputter target during conditioning of the sputter target in metallic mode. The material deposition during conditioning or pre-sputtering is not conducted on the substrate having a device to be manufactured thereon, rather the dummy substrate. Providing one or more magnet assemblies of the rotatable cathode in a second rotational position, wherein the plasma is facing away from the substrate, as described above, has the advantage of not having a dummy substrate, e.g. for each conditioning procedure. As an example, having a dummy substrate prior to each process substrate would significantly reduce thorough-put. As another example, not having a dummy substrate greatly simplifies the routing of substrates in an inline or cluster deposition system.
[0035] In some implementations, during conditioning of the sputter target in metallic mode, the substrate 220 can be provided within the vacuum chamber 302 while the sputter target is facing away from the substrate 220. As an example, the conditioning of the sputter target in metallic mode can be conducted with the one or more cathodes or magnet assemblies being in the second rotational position. According to yet further implementations, not providing a dummy substrate for target conditioning, e.g. according to embodiments including a magnetron position in a second rotation position, e.g. facing away from a substrate receiving area, may even reduce the tact time of a system. For example, the substrates can be unloaded and loaded from the vacuum chamber while the one or more targets are condition. Accordingly, an overlap of a time period for routing of substrates into and out of the vacuum chamber and a time period of conditioning one or more targets can be realized.
[0036] According to embodiments, which can be combined with other embodiments described herein, the second process atmosphere can be configured for a deposition mode. As an example, the deposition mode can be the transition mode. In particular, depositing the metal oxynitride layer on or over the substrate is conducted in transition mode.
[0037] In some implementations, the second process atmosphere includes at least one of an inert gas, such as argon, and one or more reactive gases, such as nitrogen (N2), ammonia (NH3), oxygen (02) and/or nitrous oxide (N20). A composition of the second process atmosphere can be selected according to a composition or stoichiometry of the layer that is to be deposited over the substrate, such as a composition or stoichiometry of the metal oxynitride layer or a metal oxynitride sub-layer of the metal oxynitride layer.
[0038] In some implementations, the first process atmosphere can include less reactive gases than those the second process atmosphere can include. As an example, a partial pressure of the one or more reactive gases in the first process atmosphere is less than a partial pressure of the one or more reactive gases in the second process atmosphere. The partial pressure of the one or more reactive gases in the first process atmosphere can be a total partial pressure of all reactive gases of the first process atmosphere. Likewise, the partial pressure of the one or more reactive gases in the second process atmosphere can be a total partial pressure of all reactive gases of the second process atmosphere. As an example, the total partial pressure can correspond to a sum of the partial pressures of the reactive gases in the respective process atmosphere.
[0039] According to embodiments described herein, the first process atmosphere can include the inert gas and a smaller amount of at least one of the one or more reactive gases compared to the second process atmosphere. As an example, the second process atmosphere can be an "actual recipe atmosphere". The term "actual recipe atmosphere" can refer to an atmosphere having a composition that is configured for depositing the metal oxynitride layer or a metal oxynitride layer sub-layer of the metal oxynitride layer over the substrate 220.
[0040] According to some embodiments, which can be combined with other embodiments described herein, the first process atmosphere can be provided within the deposition chamber 240, and the conditioning or pre-sputtering in metallic mode can be performed. As an example, the substrate 220 is not exposed to the sputter target 210 during conditioning or pre-sputtering in metallic mode. This can be achieved, for example, by a rotation of a cathode including the sputter target 210 or by a rotation of a magnet assembly provided at, or in, the cathode such that the plasma 230 is facing away from the substrate 220.
[0041] Through conditioning, an oxide layer, e.g., a ZnO layer or a ZnON layer, can be removed from the sputter target 210. After the conditioning, the second process atmosphere is provided, for example the first process atmosphere can be replaced by the second process atmosphere. The substrate 220 can be exposed to material deposited from the sputter target 210. A rotation of the cathode including the sputter target 210 or by a rotation of the magnet assembly such that the plasma 230 is facing towards the substrate 220 can be provided.
[0042] Depositing of the metal oxynitride layer over the substrate 220 in a reactive deposition process can be performed in the second process atmosphere. The reactive deposition process is conducted to provide a stoichiometry, for example a predetermined stoichiometry, of the material to be deposited onto the substrate 220 until the end of the deposition. For example, this can be the correct stoichiometry for ZnxOyNz deposition.
[0043] In some implementations, depositing the metal oxynitride layer over the substrate 220 includes depositing two or more metal oxynitride sub-layers to form the metal oxynitride layer. As an example, depositing the metal oxynitride layer over the substrate 220 can include depositing four metal oxynitride sub-layers to form the metal oxynitride layer. By depositing the metal oxynitride layer with two or more metal oxynitride sublayers, characteristics of the metal oxynitride layer, such as charge carrier mobility, can be adjusted. As an example, different process powers, process times and/or second process atmospheres can be used for deposition of the two or more metal oxynitride sub-layers. In particular the two or more metal oxynitride sub-layers can have different thicknesses. Examples are given with reference to FIGs. 4 and 5.
[0044] According to embodiments described herein, which can be combined with other embodiments described herein, the apparatus 200 can be configured for processing the substrate 220 in a substantially vertical orientation. The term "substantially vertical" is understood particularly when referring to the substrate orientation, to allow for a deviation from the vertical direction of 20° or below, e.g. of 10° or below. This deviation can be provided for example because a substrate support with some deviation from the vertical orientation might result in a more stable substrate position. Yet, the substrate orientation during layer deposition is considered substantially vertical, which is considered different from the horizontal substrate orientation.
[0045] According to an aspect of the present disclosure, a method for layer deposition over a process substrate utilizing a rotatable sputter target having a magnetron disposed with the rotatable target is provided. The method includes: conditioning the rotatable sputter target in an inert process atmosphere by positioning the magnetron away from a substrate deposition region; and depositing a metal oxynitride layer in an oxygen process atmosphere over the process substrate by positioning the magnetron towards the substrate deposition region. The method can be combined with any one of the features or feature groups described herein with reference to FIGs. 1 to 5.
[0046] FIG. 3A shows a schematic view of an apparatus 300 for layer deposition on or over a substrate 220 according to further embodiments described herein. FIG. 3B shows a schematic view of the apparatus of FIG. 3A with the one or more deposition sources, and in particular one or more cathodes 324 of the one or more deposition sources, facing away from the substrate 220 during conditioning in metallic mode. Exemplarily, one vacuum chamber 302 for deposition of layers therein is shown. Further vacuum chambers 303 can be provided adjacent to the vacuum chamber 302. The vacuum chamber 302 can be separated from adjacent further vacuum chambers 303 by a valve having a valve housing 304 and a valve unit 305. After a carrier 314 with the substrate 220 thereon is, as indicated by arrow 1, inserted in the vacuum chamber 302, the valve unit 305 can be closed. The atmosphere in the vacuum chambers 302, such as the first process atmosphere and/or the second process atmosphere, can be individually controlled by generating a technical vacuum, for example, with vacuum pumps connected to the vacuum chamber 302, and/or by inserting one or more process gases in the deposition region in the vacuum chamber 302. The one or more process gases can include the gases for creating the first process atmosphere and the second process atmosphere according to the embodiments described herein. Within the vacuum chamber 302, rollers 310 can be provided in order to transport the carrier 314, having the substrate 220 thereon, into and out of the vacuum chamber 302.
[0047] Within the vacuum chamber 302, one or more deposition sources are provided. A deposition source of the one or more deposition sources can include one or more cathodes 324 and one or more anodes 326. For example, the one or more cathodes 324 can be rotatable cathodes having the sputter targets of the material to be deposited on the substrate
220. The one or more cathodes 324 can have a magnet assembly therein, and magnetron sputtering can be conducted for depositing of the layers.
[0048] The one or more cathodes 324 and the one or more anodes 326 can be electrically connected to a DC power supply 328. In some implementations, the one or more cathodes 324 can be rotated simultaneously towards the substrate 220 for exposure thereof. Sputtering for forming the metal oxynitride layer can be conducted as DC sputtering. The one or more cathodes 324 are connected to the DC power supply 328 together with the one or more anodes 326 for collecting electrons during sputtering. According to yet further embodiments, which can be combined with other embodiments described herein, at least one of the one or more cathodes 324 can have its corresponding, individual DC power supply.
[0049] As used herein, "magnetron sputtering" refers to sputtering performed using a magnetron or magnet assembly, i.e., a unit capable of generating a magnetic field. Such a magnet assembly consists of one or more permanent magnets. These permanent magnets can be arranged within a rotatable sputter target or coupled to a planar sputter target in a manner such that the free electrons are trapped within the generated magnetic field generated below the rotatable target surface. Such a magnet assembly may also be arranged coupled to a planar cathode. According to some embodiments described herein, sputtering can be conducted as DC (direct current) sputtering. However, other sputtering methods such as MF (middle frequency) sputtering, RF (radio frequency) sputtering, or pulse sputtering can also be applied.
[0050] FIGs. 3A and 3B show a plurality of deposition sources, wherein a deposition source includes one cathode 324 and one anode 326. Particularly for applications for large area deposition, an array of deposition sources can be provided within the vacuum chamber 302.
[0051] The one or more cathodes 324 (and/or the magnet assemblies or magnetrons arranged therein) can have the same or different rotational positions within the vacuum chamber 302. The one or more cathodes 324 can have essentially the same rotational positions or can at least all be directed towards the substrate 220 or a corresponding deposition area. The deposition area can be an area or region with a deposition system,
which is provided and/or arranged for the deposition (the intended deposition) of the material on the substrate 220.
[0052] For deposition of the metal oxynitride layer over the substrate 220, the one or more cathodes 324 can assume a rotational position in which the plasma 2 is directed towards the substrate 220 or the corresponding deposition area (FIG. 3A). For conditioning the sputter targets of the one or more cathodes 324 in metallic mode, the one or more cathodes 324 can assume another rotational position in which the plasma 2 is facing away from the substrate 220 (FIG. 3B). In the second position, the plasma 2 can, for example, be directed to a shield (not shown) adapted for collecting material to be sputtered while the plasma 2 is directed towards the shield.
[0053] According to embodiments described herein, the methods provide a sputter deposition for a static deposition process or a dynamic deposition process. According to embodiments described herein a static deposition process can be provided, e.g., for TFT processing, wherein conditioning the sputter target in metallic mode can be conducted prior to deposition of the metal oxynitride layer over the substrate 220.
[0054] It should be noted that "static deposition processes", which differ from dynamic deposition processes, do not exclude any movement of the substrate as would be appreciated by a skilled person. A static deposition process can include, for example, at least one of the following: a static substrate position during deposition; an oscillating substrate position during deposition; an average substrate position that is essentially constant during deposition; a dithering substrate position during deposition; a wobbling substrate position during deposition; a deposition process for which the cathodes are provided in one deposition chamber, i.e. a predetermined set of cathodes are provided in the deposition chamber; a substrate position wherein the deposition chamber has a sealed atmosphere with respect to neighboring chambers, e.g. by closing valve units separating the chamber from an adjacent chamber during deposition of the layer; or a combination thereof. A static deposition process can be understood as a deposition process with a static position, a deposition process with an essentially static position, or a deposition process with a partially static position of the substrate. In view of this, a static deposition process, in which the substrate position can in some cases be not fully without any movement during deposition, can still be distinguished from a dynamic deposition process.
[0055] In the following, effects and benefits of the method and apparatus of the present disclosure are explained with reference to a first comparative example of a ZnON layer, a second comparative example of a ZnON layer, a third comparative example of a ZnON layer, and a fourth example of a ZnON layer, wherein only the fourth example of the ZnON layer was deposited using the method according to the present disclosure.
[0056] In the examples given, the metal oxynitride layer implemented in TFTs has four metal oxynitride sub-layers, i.e., a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer that are deposited on each other in this order.
[0057] The first sub-layer was deposited with a first process power, a first process time, and under a first sub-layer process atmosphere. The second sub-layer was deposited with a second process power, a second process time, and under a second sub-layer process atmosphere. The third sub-layer was deposited with a third process power, a third process time, and under a third sub-layer process atmosphere. The fourth sub-layer was deposited with a fourth process power, a fourth process time, and under a fourth sub-layer process atmosphere.
[0058] First example: Thick ZnON (first comparative example)
[0059] In the first example, a ZnON layer of about 100 nm was deposited. The first sublayer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included at least in part different amounts of Ar (argon), N2 and N20. The fourth sub-layer was deposited to have a layer thickness of about 80 nm. Prior to depositing the ZnON layer of the first example, the sputter target was conditioned in the actual recipe mode explained with reference to FIG. 2.
[0060] The first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere
created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 300 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The ZnON layer of the first example was then annealed for about 1 hour at about 350°C and 60 to 160 Pa.
[0061] The TFT having the first ZnON layer showed the following characteristics: Ion=4.5E-04 A, Ioff=6.18E-012 A, Mo=26.2, S=0.95, Von(10V)=-3.25V, and Von(0.1V)=- 1.25V.
[0062] Here, Ion refers to a source-drain current when the TFT is switched on, I0ff refers to a source-drain current when the TFT is switched off, Mo refers to a field effect mobility in units of m2/(V*s), S refers to a sub threshold slope in units of mV/decade, Von(10V) refers to a source-drain voltage when a potential of 10 V is applied to the gate electrode, and Von(0.1V) refers to a source-drain voltage when a potential of 0.1 V is applied to the gate electrode.
[0063] Second example: Thick ZnON (second comparative example)
[0064] In the second example, a ZnON layer of about 100 nm was deposited. The second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sublayer process atmosphere included, at least in part, different amounts of Ar, N2 and N20, similar to those used in the first example. However, the first sub-layer process atmosphere included only Ar. Prior to depositing the ZnON layer of the second example, the sputter target was conditioned in the actual recipe mode.
[0065] The first sub-layer was deposited with a first process power of about 250 W, a first process time of about 12 s, and under a first sub-layer process atmosphere created by 100 seem of Ar. The second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The third sublayer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The fourth sub-layer was deposited with a fourth process
power of about 450 W, a fourth process time of about 300 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The ZnON layer of the second example was then annealed for about 1 hour at about 350°C and 60 to 160 Pa.
[0066] The TFT having the second ZnON layer showed the following characteristics: Ion=6.76E-04 A, Ioff=5.26E-011 A, Mo=47.8, S=1.63, Von(10V)=-9.75V, and Von(0.1V)=- 5.75V.
[0067] Although the second example showed improved charge carrier mobility, S and Von were significantly deteriorated. Similar effects showed up when increasing a process power.
[0068] Third example: Thin ZnON (third comparative example)
[0069] In the third example, a ZnON layer was deposited. The third example is similar to the first example with the difference being that a layer thickness of the fourth sub-layer was reduced to about 45 nm. The first sub-layer, the second sub-layer and the third sublayer of the third example were similar to the first sub-layer, the second sub-layer and the third sub-layer of the first example, respectively.
[0070] The first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included, at least in part, different amounts of Ar, N2 and N20. Prior to depositing the ZnON layer of the third example, the sputter target was conditioned in the actual recipe mode.
[0071] The first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The fourth sub-layer was
deposited with a fourth process power of about 450 W, a fourth process time of about 138 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The ZnON layer of the third example was then annealed for about 1 hour at about 300°C and 60 to 160 Pa.
[0072] The TFT having the third ZnON layer showed the following characteristics: Ion=1.55E-04 A, Ioff=2.01E-012 A, Mo=10, S=0.81, Von(10V)=- 1.75V, and Von(0.1V)=- 1.25V.
[0073] Compared to the first example, the third example showed a lower S and a more positive Von(10V). However, the field effect mobility was significantly degraded. This may result from an oxidizing zinc target that acts as a carrier suppressor. As an example, charge carrier mobility decreases, a source resistance Rs increases, and Nb (bulk charge carrier concentration) decreases.
[0074] Fourth example
[0075] In the fourth example, a ZnON layer was deposited using the method according to the present disclosure. The first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere included, at least in part, different amounts of Ar (argon), N2 and N20. The fourth sub-layer was deposited to have a layer thickness of about 45 nm. Prior to depositing the ZnON layer of the fourth example, the sputter target was conditioned in metallic mode.
[0076] The first sub-layer process atmosphere, the second sub-layer process atmosphere, the third sub-layer process atmosphere, and the fourth sub-layer process atmosphere can each be understood as the second process atmosphere of the embodiments described herein. The target conditioning in metallic mode was performed under the first process atmosphere.
[0077] The first sub-layer was deposited with a first process power of about 400 W, a first process time of about 24 s, and under a first sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The second sub-layer was deposited with a second process power of about 1000 W, a second process time of about 18 s, and
under a second sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The third sub-layer was deposited with a third process power of about 350 W, a third process time of about 18 s, and under a third sub-layer process atmosphere created by 10 seem of Ar, 300 seem of N2, and 5 seem of N20. The fourth sub-layer was deposited with a fourth process power of about 450 W, a fourth process time of about 138 s, and under a fourth sub-layer process atmosphere created by 10 seem of Ar, 50 seem of N2, and 12 seem of N20. The ZnON layer of the fourth example was then annealed for about 1 hour at about 300°C and 60 to 160 Pa.
[0078] The TFT having the fourth ZnON layer according to the present disclosure showed the following characteristics: Ion=6.11E-04 A, Ioff=4.67E-012 A, Mo=41.1, S=0.93, Von(10V)=-4.85V, and Von(0.1V)=-3.2V.
[0079] The ZnON layer according to the present disclosure has high charge carrier mobility. Further, also characteristics such as Ion, I0ff, S, and field effect mobility are improved. In other words, a lower quality of the (thinner) metallic mode ZnON layer has a better TFT performance than the TFTs of the comparative examples where the sputter target was conditioned in the actual recipe mode.
[0080] Referring to the first example and the second example, when using the actual recipe mode for conditioning, the thick ZnON film is hard to improve. The tradeoffs are considerable. In particular, I0ff, S, and Von are deteriorated. Further, when using the actual recipe mode for conditioning, the zinc target can become oxidized and can deteriorate the charge carrier mobility considerably.
[0081] As in the present disclosure and the fourth example, a ZnON layer deposited after conditioning in metallic mode can provide high field effect mobility with more positive Von, better S and l0s of the TFT, when compared with the actual recipe mode (non-metallic mode) conditioning. For the conditioning in metallic mode, as in the first process atmosphere only Ar can be used, or Ar with N2 and NH3, or Ar with a low flow of N20 or 02 gas.
[0082] FIG. 4 shows a schematic view of a thin film transistor 400 manufactured according to the embodiments described herein. FIG. 5 shows a flow chart 500 of a method
for manufacturing a thin film transistor (TFT) on a substrate according to embodiments described herein, and in particular the thin film transistor 400 of FIG. 4. The TFT according to the embodiments described herein can for example be used in display devices, such as liquid crystal displays (LCDs) and/or organic light emitting diode (OLED) displays.
[0083] The method for manufacturing a thin film transistor (TFT) on (or over) a substrate includes conditioning a sputter target in metallic mode, wherein a target material of the sputter target includes a metal, and depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer. In the following, a more detailed description of a method for manufacturing the TFT is given.
[0084] When reference is made to the terms "on" or "over", i.e. one layer being on or over the other, it is understood that, e.g., starting from the substrate, the one layer is deposited on or over the substrate, and the other layer, deposited after the one layer, is thus on or over the one layer and over the substrate. In other words, the terms "on" or "over" are used to define an order of layers, layer stacks, and/or films wherein the starting point can be the substrate. This is irrespective of whether the layer stack is depicted upside down or not. Further, the term "over" should include embodiments where one or more additional layers are provided between the one layer and the other layer. The term "on" should include embodiments where no additional layers are provided between the one layer and the other layer, i.e., the one layer and the other layer are directly disposed on each other, or, in other words, are in contact with each other.
[0085] In block 505, a gate electrode 420 is formed on or over a TFT substrate 410. The TFT substrate 410 can be a glass substrate. The gate electrode 420 can be deposited using a PVD process. As an example, the gate electrode 420 can include a metal. The metal can be selected from the group including Cr, Cu, Mo, Ti, and any combination thereof. The metal can also be a metal stack including two or more of the metals selected from the group including Cr, Cu, Mo, Ti, and any combination thereof. The gate electrode can have a thickness of about 150 nm.
[0086] In block 510, a gate insulator 430 is formed at least over the gate electrode 420, e.g., by a PECVD process. As an example, the gate insulator can include at least one of
SiNx and SiOy. The gate insulator can have at least two sub-layers, e.g., at least one SiNx layer (e.g., about 300 nm) and at least one SiOy layer (e.g., about 50 nm).
[0087] In block 515, a channel layer 440 is formed on or over the gate insulator 430. The methods and apparatuses for layer deposition described with reference to FIGs. 1 to 3 can be implemented to form the channel layer 440 of the TFT 400. The channel layer 440 can be a ZnON layer. The channel layer 440 has improved electrical characteristics, such as enhanced charge carrier mobility.
[0088] In some implementations, 100 seem of Ar can be used for the first process atmosphere for conditioning in metallic mode. A process gas pressure of the first process atmosphere within the deposition chamber can be in the range of 0.5 to 0.6 Pa, and can for example be about 0.55 or about 0.56 Pa. A sputter target voltage during conditioning in metallic mode can be about 500 V. A process power can be about 700 W. Further, in some implementations, a dummy substrate can be used during the conditioning. Deposition of the metal oxynitride layer, e.g., ZnON, can be conducted at about 50°C.
[0089] In block 520, a first annealing process can be performed, e.g., under vacuum and/or a nitrogen (N2) atmosphere. The first annealing process can change characteristics of the channel layer 440, e.g., at least one of a chemical composition, a crystallinity, and a charge carrier concentration. The first annealing process can for example be conducted under at least one of the following conditions: at about 300°C, for about 1 hour and under a nitrogen atmosphere (e.g., about 60 Pa to about 160 Pa). The conditions can for example be used for thin metal oxynitride layers, such as for metal oxynitride layers having a layer thickness of about 50 nm.
[0090] In block 525, a first etching process is performed, e.g., an island wet etching process. The first etching process can for example be conducted under at least one of the following conditions: with about 0.1 % HCL, for about 4 s to 12 s (e.g., for a layer thickness of about 80 nm), and at room temperature.
[0091] In block 530, a second annealing process can be performed, e.g., under ambient atmosphere (e.g., air). The second annealing process can change characteristics of the channel layer 440, e.g., at least one of a chemical composition, a crystallinity, and a charge
carrier concentration. The second annealing process can for example be conducted in an oven under at least one of the following conditions: at a temperature in a range from about 200°C to about 300°C and for about 30 min.
[0092] In block 535, an etch stopper 450, e.g., of SiOx, is formed on the channel layer 440, e.g., by a PECVD process. The etch stopper 450 can be formed to have a thickness of about 100 nm. The PECVD process can for example be conducted under at least one of the following conditions: at about 200°C and under a process atmosphere pressure in a range of e.g., 50 to 300 Pa, specifically in a range of 80 to 250 Pa, and more specifically in a range of about 160 to about 170 Pa.
[0093] In block 540, a source electrode 460 and a drain electrode 470 are formed on the channel layer 440, e.g., by a PVD process. The source electrode 460 and the drain electrode 470 can be made of a metal, e.g., with a thickness of about 200 nm. The metal can be selected from the group including Cr, Cu, Mo, Ti, and any combination thereof. The metal can also be a metal stack including two or more of the metals selected from the group including Cr, Cu, Mo, Ti, and any combination thereof. In block 545, a passivation process is performed to form a passivation layer 480 at least over the source electrode 460 and the drain electrode 470. The passivation layer 480 can for example be formed by a PECVD process. In block 550, a third annealing process (TFT anneal) can be performed. The third annealing process can for example be conducted under at least one of the following conditions: at about 250°C, for about 30 min, under nitrogen atmosphere, and at a process atmosphere pressure of e.g., about 260 to about 270 Pa.
[0094] The thin film transistor 400 includes the channel layer 440, wherein the channel layer 440 includes, or is, the metal oxynitride layer deposited using the embodiments disclosed herein. By conditioning the sputter target in metallic mode, oxidized material, e.g., an oxide layer such as a zinc oxide (ZnO) layer or a zinc oxynitride (ZnON) layer, can be removed from the sputter target before depositing the metal oxynitride layer over the substrate. The reactive deposition process can produce a metal oxynitride layer having improved electrical characteristics, such as enhanced charge carrier mobility.
[0095] According to embodiments described herein, the method for layer deposition on or over a substrate and the method for manufacturing a thin film transistor on or over a
substrate can be conducted by means of computer programs, software, computer software products and the interrelated controllers, which can have a CPU, a memory, a user interface, and input and output means being in communication with the corresponding components of the apparatus for processing a large area substrate.
[0096] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims
1. A method for layer deposition over a substrate, comprising: conditioning a sputter target in metallic mode under a first process atmosphere, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process under a second process atmosphere.
2. The method of claim 1, wherein the first process atmosphere is different from the second process atmosphere.
3. The method of claim 1 or 2, wherein the first process atmosphere includes at least one of an inert gas and one or more reactive gases, in particular wherein the inert gas is argon.
4. The method of claim 3, wherein a partial pressure of the inert gas in the first process atmosphere is in a range of 90% to 100% of a total pressure of the first process atmosphere, is in particular in a range of 98% to 100%, and more particularly about 100%.
5. The method of one of claims 1 to 4, wherein the second process atmosphere includes at least one of an inert gas and one or more reactive gases, in particular wherein the inert gas is argon.
6. The method of one of claims 3 to 5, wherein the one or more reactive gases are selected from a group consisting of nitrogen (N2), ammonia (NH3), oxygen (02), nitrous oxide (N20), and any combination thereof.
7. The method of one of claims 3 to 6, wherein a partial pressure of the one or more reactive gases in the first process atmosphere is less than a partial pressure of the one or more reactive gases of the second process atmosphere.
8. The method of one of claims 1 to 7, wherein depositing the metal oxynitride layer over the substrate is conducted in transition mode.
9. The method of one of claims 1 to 8, wherein the metal is zinc, in particular wherein the metal oxynitride layer is a zinc oxynitride layer.
10. The method of one of claims 1 to 9, wherein the metal oxynitride layer is deposited to have a layer thickness of less than 100 nm, specifically less than 80 nm, and more specifically in the range of 40 to 60 nm.
11. The method of one of claims 1 to 10, wherein depositing the metal oxynitride layer over the substrate includes depositing two or more metal oxynitride sub-layers to form the metal oxynitride layer, in particular wherein depositing the metal oxynitride layer over the substrate includes depositing four metal oxynitride sub-layers to form the metal oxynitride layer.
12. The method of one of claims 1 to 11, wherein the substrate is not exposed to the sputter target during conditioning of the sputter target in metallic mode.
13. An apparatus for layer deposition over a substrate, comprising:
a sputter target including a metal, wherein the sputter target is configured to be conditioned in metallic mode, and wherein the apparatus is configured to deposit a metal oxynitride layer over the substrate in a reactive deposition process.
14. A method for manufacturing a thin film transistor on or over a substrate, the method comprising: conditioning a sputter target in metallic mode, wherein a target material of the sputter target includes a metal; and depositing a metal oxynitride layer over the substrate in a reactive deposition process to form a channel layer.
15. A method for layer deposition over a process substrate utilizing a rotatable sputter target having a magnetron disposed with the rotatable target, comprising: conditioning the rotatable sputter target in an inert process atmosphere by positioning the magnetron away from a substrate deposition region; and depositing a metal oxynitride layer in an oxygen process atmosphere over the process substrate by positioning the magnetron towards the substrate deposition region.
16. The method of claim 15, including any one of the features as recited in claims 2 to 12.
17. A thin film transistor comprising a channel layer, wherein the channel layer includes a metal oxynitride layer deposited using the method of one of claims 1 to 12.
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Non-Patent Citations (3)
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MYUNGKWAN RYU ET AL: "High mobility zinc oxynitride-TFT with operation stability under light-illuminated bias-stress conditions for large area and high resolution display applications", 2012 INTERNATIONAL ELECTRON DEVICES MEETING, 10 December 2012 (2012-12-10), (IEDM 2012) SAN FRANCISCO, CALIFORNIA, USA, pages 5.6.1 - 5.6.3, XP032341678, ISBN: 978-1-4673-4872-0, DOI: 10.1109/IEDM.2012.6478986 * |
TING WEN, NANKE JIANG, DANIEL G. GEORGIEV, AHALAPITIYA H. JAYATISSA: "Structural, surface, optical, and mechanical properties of Zn3N2 thin films prepared by sputtering deposition", PROC. SPIE 7683, vol. 7683, 768311, 28 April 2010 (2010-04-28), pages 768311-1 - 768311-8, XP002743596, ISSN: 0277-786X, Retrieved from the Internet <URL:http://dx.doi.org/10.1117/12.850844> [retrieved on 20150821] * |
YE YAN ET AL: "High mobility amorphous zinc oxynitride semiconductor material for thin film transistors", JOURNAL OF APPLIED PHYSICS, vol. 106, no. 7, 074512, 13 October 2009 (2009-10-13), AMERICAN INSTITUTE OF PHYSICS, US, pages 74512 - 74512-8, XP012127597, ISSN: 0021-8979, DOI: 10.1063/1.3236663 * |
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