WO2011009764A1 - Etchant composition and etching process for titanium-aluminum complex metal layer - Google Patents

Etchant composition and etching process for titanium-aluminum complex metal layer Download PDF

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Publication number
WO2011009764A1
WO2011009764A1 PCT/EP2010/060042 EP2010060042W WO2011009764A1 WO 2011009764 A1 WO2011009764 A1 WO 2011009764A1 EP 2010060042 W EP2010060042 W EP 2010060042W WO 2011009764 A1 WO2011009764 A1 WO 2011009764A1
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WIPO (PCT)
Prior art keywords
metal layer
titanium
etchant composition
aluminum
composition according
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PCT/EP2010/060042
Other languages
French (fr)
Inventor
Yung I Yang
Mohsun Tsai
Sheng-Hung Tu
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Basf Se
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Publication of WO2011009764A1 publication Critical patent/WO2011009764A1/en

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    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/02—Local etching
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K13/00—Etching, surface-brightening or pickling compositions
    • C09K13/04—Etching, surface-brightening or pickling compositions containing an inorganic acid
    • C09K13/08—Etching, surface-brightening or pickling compositions containing an inorganic acid containing a fluorine compound
    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
    • C23F1/14—Aqueous compositions
    • C23F1/16—Acidic compositions
    • 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
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
    • H01L21/32134—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by liquid etching only
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
    • H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
    • H05K3/067—Etchants
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03—Conductive materials
    • H05K2201/0302—Properties and characteristics in general
    • H05K2201/0317—Thin film conductor layer; Thin film passive component
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09209—Shape and layout details of conductors
    • H05K2201/09654—Shape and layout details of conductors covering at least two types of conductors provided for in H05K2201/09218 - H05K2201/095
    • H05K2201/098—Special shape of the cross-section of conductors, e.g. very thick plated conductors

Definitions

  • the present invention relates to an etchant composition, and more particularly, an etchant composition for titanium- aluminum complex metal layer, which can effectively control a taper angle of an etched metal layer to be in a range of about 20 degrees to about 60 degrees without damaging a surface of the substrate.
  • the etchant composition of the present invention is suitable for use in an etching process in various applications, such as a flat panel display, an integrated circuit, a flip chip, a printed circuit board (PCB), or a micro-electromechanical system comprising a titanium-aluminum complex metal layer.
  • Aluminum is a richly available resource in the earth's crust. It has low metal conductor resistivity and good patterning capability. However, due to the differing expansion coefficients of aluminum and silicon or glass substrates, bulges are generated in the process when conducted at high temperatures. The bulges are likely to cause shorts between two conductor wires of the gate and the source/drain.
  • the problem can be solved by coating the aluminum film with molybdenum or molybdenum-aluminum alloy or adding neodymium into the aluminum to form an alloy serving as electrode material in the manner of a complex metal layer.
  • the molybdenum-aluminum or aluminum-neodymium complex metal layer can be etched by an etchant with phosphoric acid as the main ingredient.
  • titanium or titanium alloy can serve as the wetting layer of aluminum wire to improve step coverage of the aluminum atom, and can reduce contact resistance between the metal and silicon or glass as well.
  • the etchant used for etching the complex metal layer composed of molybdenum or molybdenum alloy and aluminum alloy cannot be used to etch titanium or titanium alloy.
  • hydrofluoric-acid-based etchant is commonly used to etch titanium or titanium alloy in the semiconductor or flat panel display process, the hydrofluoric acid damages the surface of the silicon or glass substrate.
  • one object of the present invention is to provide an etchant composition that can effectively etch a titanium-aluminum complex metal layer without damaging the surface of the substrate.
  • the etchant composition comprises, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium.
  • Another object of the present invention is to provide an etching process for the titanium-aluminum complex metal layer by using the etchant composition of the present invention, which can effectively control a taper angle of an etched metal layer to be in a range of about 20 degrees and about 60 degrees without damaging the surface of the substrate.
  • a substantially neutral quaternary ammonium compound containing fluorine is used to replace conventional hydrofluoric acid or an ammonium salt thereof.
  • the quaternary ammonium compound has bigger steric hinderance than common ammonium salts (NH 4 + ). Compared with ammonium fluoride, which is of small molecular size, the quaternary ammonium compound will not easily damage the surface of the silicon or glass substrate.
  • a certain amount of fluorine ions that are partly dissociated can be stably and continuously provided by adding an acidic compound, which can form an acidic fluorine ion buffer solution with the quaternary ammonium compound containing fluorine, so as to maintain a fluorine ion concentration within a fixed range, thereby alleviating the problem of slowing etching speed due to decrease of the fluorine ion concentration during the etching process.
  • FIG. 1 shows side views of a titanium-aluminum complex metal layer and a patterned photoresist layer formed on a glass substrate before etching (a) and after etching (b).
  • FIG. 2 shows a photo of the shape of the etched titanium-aluminum complex metal layer observed with a scanning electron microscope in Example 1.
  • FIG. 3 shows a photo of the shape of the etched titanium-aluminum complex metal layer observed with a scanning electron microscope in Example 7.
  • An etchant composition for titanium-aluminum complex metal layer of the present invention comprises, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium.
  • the titanium-aluminum complex metal layer suitable for use in the etchant composition of the present invention comprises at least one titanium or titanium alloy metal layer and at least one aluminum or aluminum alloy metal layer.
  • a hydrogen fluoride buffer solution formed by the quaternary ammonium compound containing fluorine and the acidic compound is mainly used to perform the etching process and to dissolve aluminum oxide and titanium oxide in the titanium-aluminum complex metal layer.
  • Aluminum oxide and titanium oxide are formed by oxidization of the aluminum alloy and the titanium alloy in the titanium- aluminum complex metal layer with the oxidizing agent contained in the etchant composition.
  • the quaternary ammonium compound containing fluorine suitable for use in the etchant composition of the present invention has a general formula Of RiR 2 RsR 4 N + F " , wherein R 1 , R 2 , R 3 , and R 4 can be identical or different and are independently straight or branched Ci-C ⁇ -alkyl (preferably d-Gt-alkyl), straight or branched C 2 -C6-alkenyl (preferably d-C 4 -alkenyl), or C3-C 8 -cycloalkyl, wherein alkyl, alkenyl or cycloalkyl can be optionally substituted with at least one hydroxyl.
  • R 1 , R 2 , R 3 , and R 4 can be identical or different and are independently straight or branched Ci-C 4 -alkyl.
  • the quaternary ammonium compound containing fluorine can be tetramethyl ammonium fluoride, tetraethyl ammonium fluoride, tetrapropyl ammonium fluoride, or tetrabutyl ammonium fluoride, and most preferably is tetramethyl ammonium fluoride.
  • the content of the quaternary ammonium compound containing fluorine used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.1 wt% to about 5 wt%, preferably from about 0.2 wt% to about 3 wt%.
  • the oxidizing agent used in the present invention serves as an initiator before etching, to oxidize aluminum, titanium or aluminum-titanium alloy in the titanium- aluminum complex metal layer, and can be selected from various oxidizing agents suitable for oxidizing titanium-aluminum complex metal that are known in the art, including but not limited to those consisting of nitric acid, perchloric acid, peroxide, salts thereof, and mixtures thereof, and preferably selected from the group consisting of nitric acid, ammonium nitrate, cerium ammonium nitrate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, ammonium peroxydisulfate, potassium peroxydisulfate, hydrogen peroxide, and mixtures thereof.
  • the content of the oxidizing agent used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.5 wt% to about 20 wt%, preferably from about 1.0 wt% to about 10 wt%.
  • the acidic compound used in the present invention can form the hydrogen fluoride buffer solution with the quaternary ammonium compound containing fluorine, to dissolve aluminum oxide and titanium oxide in the titanium-aluminum complex metal layer, and can be an acidic compound capable of dissociating the quaternary ammonium compound containing fluorine that is known in the art, including but not limited to those consisting of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, and mixtures thereof.
  • the content of the acidic compound used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.2 wt% to about 20 wt%, preferably from about 0.5 wt% to about 10 wt%.
  • the aqueous medium used in the present invention is well known by persons having ordinary skill in the art, and includes, for example, water, distilled water, ultrapure water, and deionized water; preferably ultrapure water or deionized water.
  • the etchant composition of the present invention can be used to form titanium- aluminum electronic wire patterns, and has advantages of high etching speed and being capable of controlling a taper angle of the etched titanium-aluminum complex metal layer to be in a range of about 20 degrees to about 60 degrees.
  • the etchant composition is applicable in the etching process of flat panel display, integrated circuit, flip chip, printed circuit board (PCB) or micro-electromechanical system having a titanium- aluminum complex metal layer.
  • the present invention further provides a process for etching titanium-aluminum complex metal layer, comprising the steps of:
  • a patterned photoresist layer on the second titanium metal layer; and etching the first titanium metal layer, the aluminum metal layer, and the second titanium metal layer with the etchant composition having the components and proportions described above through the patterned photoresist layer as a mask.
  • the first titanium metal layer and the second titanium metal layer comprise titanium or titanium alloy
  • the aluminum metal layer comprises aluminum or aluminum alloy
  • the first titanium metal layer, the aluminum metal layer, and the second titanium metal layer are formed by using a general method known in this technical field; for example but not limited to physical vapor deposition, chemical vapor deposition or electroplating.
  • the substrate comprising the titanium-aluminum complex metal layer to be etched in the etching process of the present invention is not limited.
  • the substrate includes but is not limited to a silicone substrate or a glass substrate such as silica polymorphs or a silicon dioxide glass substrate.
  • the process for etching titanium-aluminum complex metal layer of the present invention can be performed under typical operation conditions known in the art.
  • the temperature of the etching process is in a range of about 15°C to about 50 0 C, preferably about 25°C to about 40 0 C, and the etching time is about 0.5 minutes to about 10 minutes.
  • the etching process of the present invention can effectively etch the titanium- aluminum complex metal layer without damaging the surface of the silicon or glass substrate, and can control the taper angle of the etched titanium-aluminum complex metal layer to be in a range of about 20 degrees to about 60 degrees.
  • FIG. 1 shows side views of a titanium-aluminum complex metal layer and a patterned photoresist layer formed on a glass substrate before etching (a) and after etching (b).
  • a glass substrate (1) is provided, and a complex metal layer of 7O ⁇ A titanium metal (2) / 2100A aluminum metal (3) / 2O ⁇ A titanium metal (2) is formed on the substrate.
  • a patterned photoresist layer (4) is formed on the titanium-aluminum complex metal layer, and then the substrate is immersed in the etchant compositions of Examples 1 to 14 in Table 1 at a temperature of about 35 0 C. After etching, the glass substrate is washed with ultrapure water, and dried with nitrogen gas, to obtain the substrate comprising the etched titanium-aluminum complex metal layer, as shown in FIG. l(b). Table 1
  • Etchant compositions (wt%), the remaining is etching time taper angle substrate
  • nitric acid 0.6 : 1.0 : 3.0 no tetramethyl ammonium fluoride : sulfuric acid :
  • nitric acid 1.0 : 1.0 : 3.0 no tetramethyl ammonium fluoride : sulfuric acid :
  • nitric acid 1.0 : 2.0 : 15.0 0.6 20 slightly tetramethyl ammonium fluoride : acetic acid :
  • nitric acid 1.0 : 15.0 : 3.0 1.1 22 slightly tetramethyl ammonium fluoride : sulfuric acid :
  • the shape of the etched titanium-aluminum complex metal layer is observed with a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • the SEM photo of Example 1 is shown in FIG. 2, and the SEM photo of Example 7 is shown in FIG. 3.
  • the etchant composition of the present invention when the content of the quaternary ammonium compound containing fluorine is lower than about 5 wt%, no damage to the silicon or glass substrate is caused. When the content of the quaternary ammonium compound containing fluorine is higher than about 0.1 wt%, etching capability on titanium or titanium alloy is improved and the shape after etching is good.
  • the oxidizing agent When the content of the oxidizing agent is higher than about 0.5 wt%, the etching speed on titanium or titanium alloy is higher and the effect is good; when the content of the oxidizing agent is lower than about 20 wt%, no damage to the photoresist is caused.
  • the oxidizing agent can be used alone or together with other oxidizing agents to change the taper angle of the etched complex metal layer.
  • the etchant composition and the etching process of the present invention can effectively etch the titanium-aluminum complex metal layer on the substrate without damaging the surface of the substrate and the photoresist, are applicable in forming titanium- aluminum electronic wire patterns, and have advantages of high etching speed and capability of controlling the taper angle of the etched titanium-aluminum complex metal layer to a range of about 20 degrees to about 60 degrees.

Abstract

Disclosed is an etchant composition for titanium-aluminum complex metal layer comprising, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium. A process for etching titanium-aluminum complex metal layer by using the above-mentioned etchant composition is also disclosed.

Description

ETCHANT COMPOSITION AND ETCHING PROCESS FOR TITANIUM- ALUMINUM COMPLEX METAL LAYER
Field of the Invention
The present invention relates to an etchant composition, and more particularly, an etchant composition for titanium- aluminum complex metal layer, which can effectively control a taper angle of an etched metal layer to be in a range of about 20 degrees to about 60 degrees without damaging a surface of the substrate. The etchant composition of the present invention is suitable for use in an etching process in various applications, such as a flat panel display, an integrated circuit, a flip chip, a printed circuit board (PCB), or a micro-electromechanical system comprising a titanium-aluminum complex metal layer.
Description of the Prior Art
In the past, the wires and electrodes (gate, source, and drain) used in semiconductor and flat panel display processes were mainly composed of chromium. But with increasing awareness of environmental issues, use of chromium has gradually become prohibited.
Aluminum is a richly available resource in the earth's crust. It has low metal conductor resistivity and good patterning capability. However, due to the differing expansion coefficients of aluminum and silicon or glass substrates, bulges are generated in the process when conducted at high temperatures. The bulges are likely to cause shorts between two conductor wires of the gate and the source/drain. The problem can be solved by coating the aluminum film with molybdenum or molybdenum-aluminum alloy or adding neodymium into the aluminum to form an alloy serving as electrode material in the manner of a complex metal layer. The molybdenum-aluminum or aluminum-neodymium complex metal layer can be etched by an etchant with phosphoric acid as the main ingredient. However, as molybdenum and neodymium are expensive and easily oxidized, they have been replaced in recent years by titanium or titanium alloy. Titanium metal can serve as the wetting layer of aluminum wire to improve step coverage of the aluminum atom, and can reduce contact resistance between the metal and silicon or glass as well. However, the etchant used for etching the complex metal layer composed of molybdenum or molybdenum alloy and aluminum alloy cannot be used to etch titanium or titanium alloy.
Although a hydrofluoric-acid-based etchant is commonly used to etch titanium or titanium alloy in the semiconductor or flat panel display process, the hydrofluoric acid damages the surface of the silicon or glass substrate.
Summary of the Invention
Accordingly, one object of the present invention is to provide an etchant composition that can effectively etch a titanium-aluminum complex metal layer without damaging the surface of the substrate.
The etchant composition comprises, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium.
Another object of the present invention is to provide an etching process for the titanium-aluminum complex metal layer by using the etchant composition of the present invention, which can effectively control a taper angle of an etched metal layer to be in a range of about 20 degrees and about 60 degrees without damaging the surface of the substrate.
According to the present invention, a substantially neutral quaternary ammonium compound containing fluorine is used to replace conventional hydrofluoric acid or an ammonium salt thereof. The quaternary ammonium compound has bigger steric hinderance than common ammonium salts (NH4 +). Compared with ammonium fluoride, which is of small molecular size, the quaternary ammonium compound will not easily damage the surface of the silicon or glass substrate. Additionally, a certain amount of fluorine ions that are partly dissociated can be stably and continuously provided by adding an acidic compound, which can form an acidic fluorine ion buffer solution with the quaternary ammonium compound containing fluorine, so as to maintain a fluorine ion concentration within a fixed range, thereby alleviating the problem of slowing etching speed due to decrease of the fluorine ion concentration during the etching process. Brief description of the drawings
FIG. 1 shows side views of a titanium-aluminum complex metal layer and a patterned photoresist layer formed on a glass substrate before etching (a) and after etching (b).
FIG. 2 shows a photo of the shape of the etched titanium-aluminum complex metal layer observed with a scanning electron microscope in Example 1.
FIG. 3 shows a photo of the shape of the etched titanium-aluminum complex metal layer observed with a scanning electron microscope in Example 7.
Detailed Description
An etchant composition for titanium-aluminum complex metal layer of the present invention comprises, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium.
The titanium-aluminum complex metal layer suitable for use in the etchant composition of the present invention comprises at least one titanium or titanium alloy metal layer and at least one aluminum or aluminum alloy metal layer.
In the present invention, a hydrogen fluoride buffer solution formed by the quaternary ammonium compound containing fluorine and the acidic compound is mainly used to perform the etching process and to dissolve aluminum oxide and titanium oxide in the titanium-aluminum complex metal layer. Aluminum oxide and titanium oxide are formed by oxidization of the aluminum alloy and the titanium alloy in the titanium- aluminum complex metal layer with the oxidizing agent contained in the etchant composition.
The quaternary ammonium compound containing fluorine suitable for use in the etchant composition of the present invention has a general formula Of RiR2RsR4N+F", wherein R1, R2, R3, and R4 can be identical or different and are independently straight or branched Ci-Cβ-alkyl (preferably d-Gt-alkyl), straight or branched C2-C6-alkenyl (preferably d-C4-alkenyl), or C3-C8-cycloalkyl, wherein alkyl, alkenyl or cycloalkyl can be optionally substituted with at least one hydroxyl. In an embodiment of the present invention, R1, R2, R3, and R4 can be identical or different and are independently straight or branched Ci-C4-alkyl. In an embodiment of the present invention, the quaternary ammonium compound containing fluorine can be tetramethyl ammonium fluoride, tetraethyl ammonium fluoride, tetrapropyl ammonium fluoride, or tetrabutyl ammonium fluoride, and most preferably is tetramethyl ammonium fluoride.
The content of the quaternary ammonium compound containing fluorine used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.1 wt% to about 5 wt%, preferably from about 0.2 wt% to about 3 wt%.
The oxidizing agent used in the present invention serves as an initiator before etching, to oxidize aluminum, titanium or aluminum-titanium alloy in the titanium- aluminum complex metal layer, and can be selected from various oxidizing agents suitable for oxidizing titanium-aluminum complex metal that are known in the art, including but not limited to those consisting of nitric acid, perchloric acid, peroxide, salts thereof, and mixtures thereof, and preferably selected from the group consisting of nitric acid, ammonium nitrate, cerium ammonium nitrate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, ammonium peroxydisulfate, potassium peroxydisulfate, hydrogen peroxide, and mixtures thereof.
The content of the oxidizing agent used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.5 wt% to about 20 wt%, preferably from about 1.0 wt% to about 10 wt%.
The acidic compound used in the present invention can form the hydrogen fluoride buffer solution with the quaternary ammonium compound containing fluorine, to dissolve aluminum oxide and titanium oxide in the titanium-aluminum complex metal layer, and can be an acidic compound capable of dissociating the quaternary ammonium compound containing fluorine that is known in the art, including but not limited to those consisting of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, and mixtures thereof.
The content of the acidic compound used in the present invention is, on the basis of the total weight of the etchant composition, from about 0.2 wt% to about 20 wt%, preferably from about 0.5 wt% to about 10 wt%. The aqueous medium used in the present invention is well known by persons having ordinary skill in the art, and includes, for example, water, distilled water, ultrapure water, and deionized water; preferably ultrapure water or deionized water.
The etchant composition of the present invention can be used to form titanium- aluminum electronic wire patterns, and has advantages of high etching speed and being capable of controlling a taper angle of the etched titanium-aluminum complex metal layer to be in a range of about 20 degrees to about 60 degrees. In a preferred embodiment of the present invention, the etchant composition is applicable in the etching process of flat panel display, integrated circuit, flip chip, printed circuit board (PCB) or micro-electromechanical system having a titanium- aluminum complex metal layer.
Accordingly, the present invention further provides a process for etching titanium-aluminum complex metal layer, comprising the steps of:
providing a substrate;
forming a first titanium metal layer on the substrate;
forming an aluminum metal layer on the first titanium metal layer;
forming a second titanium metal layer on the aluminum metal layer;
forming a patterned photoresist layer on the second titanium metal layer; and etching the first titanium metal layer, the aluminum metal layer, and the second titanium metal layer with the etchant composition having the components and proportions described above through the patterned photoresist layer as a mask.
In an embodiment of the present invention, in the process for etching titanium- aluminum complex metal layer, the first titanium metal layer and the second titanium metal layer comprise titanium or titanium alloy, and the aluminum metal layer comprises aluminum or aluminum alloy; and the first titanium metal layer, the aluminum metal layer, and the second titanium metal layer are formed by using a general method known in this technical field; for example but not limited to physical vapor deposition, chemical vapor deposition or electroplating.
The substrate comprising the titanium-aluminum complex metal layer to be etched in the etching process of the present invention is not limited. The substrate includes but is not limited to a silicone substrate or a glass substrate such as silica polymorphs or a silicon dioxide glass substrate.
The process for etching titanium-aluminum complex metal layer of the present invention can be performed under typical operation conditions known in the art. In a preferred embodiment of the present invention, the temperature of the etching process is in a range of about 15°C to about 500C, preferably about 25°C to about 400C, and the etching time is about 0.5 minutes to about 10 minutes.
The etching process of the present invention can effectively etch the titanium- aluminum complex metal layer without damaging the surface of the silicon or glass substrate, and can control the taper angle of the etched titanium-aluminum complex metal layer to be in a range of about 20 degrees to about 60 degrees.
The following examples are intended to further illustrate the present invention without limiting its scope. Modifications and variations that can easily be achieved by those skilled in the art are included in the scope of the disclosure of the specification and appended claims.
Examples
FIG. 1 shows side views of a titanium-aluminum complex metal layer and a patterned photoresist layer formed on a glass substrate before etching (a) and after etching (b).
As shown in FIG. l(a), a glass substrate (1) is provided, and a complex metal layer of 7OθA titanium metal (2) / 2100A aluminum metal (3) / 2OθA titanium metal (2) is formed on the substrate. A patterned photoresist layer (4) is formed on the titanium-aluminum complex metal layer, and then the substrate is immersed in the etchant compositions of Examples 1 to 14 in Table 1 at a temperature of about 350C. After etching, the glass substrate is washed with ultrapure water, and dried with nitrogen gas, to obtain the substrate comprising the etched titanium-aluminum complex metal layer, as shown in FIG. l(b). Table 1
Etchant compositions (wt%), the remaining is etching time taper angle substrate
Examples
water (min) of wires damaging tetramethyl ammonium fluoride : sulfuric acid :
1 2.0 25
nitric acid = 0.6 : 1.0 : 3.0 no tetramethyl ammonium fluoride : sulfuric acid :
2 1.4 22
nitric acid = 1.0 : 1.0 : 3.0 no tetramethyl ammonium fluoride : sulfuric acid :
3 2.5 20 slightly nitric acid = 1.0 : 10.0 : 3.0
tetramethyl ammonium fluoride : sulfuric acid :
4 0.5 20 slightly nitric acid = 3.0 : 1.0 : 3.0
5 tetramethyl ammonium fluoride : hydrochloric 2.1 30 no acid : nitric acid = 1.0 : 1.0 : 3.0
tetramethyl ammonium fluoride : acetic acid :
6 3.5 25 no nitric acid = 1.0 : 2.0 : 3.0
tetramethyl ammonium fluoride : acetic acid :
7
nitric acid = 1.0 : 2.0 : 15.0 0.6 20 slightly tetramethyl ammonium fluoride : acetic acid :
nitric acid = 1.0 : 15.0 : 3.0 1.1 22 slightly tetramethyl ammonium fluoride : sulfuric acid :
nitric acid : ammonium peroxydisulfate = 1.0 : 1.5 35 no
1.0 : 3.0 : 1.0
tetramethyl ammonium fluoride : sulfuric acid :
10 nitric acid : ammonium peroxydisulfate = 1.0 : 1.6 63 no
1.0 : 3.0 : 2.0
tetramethyl ammonium fluoride : sulfuric acid :
11 1.2 60 no hydrogen peroxide = 1.0 : 1.0 : 5.0
tetramethyl ammonium fluoride : sulfuric acid :
12 1.4 48 no hydrogen peroxide = 1.0 : 3.0 : 5.0
tetramethyl ammonium fluoride : sulfuric acid :
13 1.5 70 no hydrogen peroxide = 1.0 : 3.0 : 10.0
tetramethyl ammonium fluoride : sulfuric acid :
14 1.3 45 no nitric acid : hydrogen peroxide = 1.0 : 1.0 : 3.0 :3.0
The shape of the etched titanium-aluminum complex metal layer is observed with a scanning electron microscope (SEM). The SEM photo of Example 1 is shown in FIG. 2, and the SEM photo of Example 7 is shown in FIG. 3. In the etchant composition of the present invention, when the content of the quaternary ammonium compound containing fluorine is lower than about 5 wt%, no damage to the silicon or glass substrate is caused. When the content of the quaternary ammonium compound containing fluorine is higher than about 0.1 wt%, etching capability on titanium or titanium alloy is improved and the shape after etching is good.
When the content of the oxidizing agent is higher than about 0.5 wt%, the etching speed on titanium or titanium alloy is higher and the effect is good; when the content of the oxidizing agent is lower than about 20 wt%, no damage to the photoresist is caused. Moreover, the oxidizing agent can be used alone or together with other oxidizing agents to change the taper angle of the etched complex metal layer.
In view of the above, the etchant composition and the etching process of the present invention can effectively etch the titanium-aluminum complex metal layer on the substrate without damaging the surface of the substrate and the photoresist, are applicable in forming titanium- aluminum electronic wire patterns, and have advantages of high etching speed and capability of controlling the taper angle of the etched titanium-aluminum complex metal layer to a range of about 20 degrees to about 60 degrees.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the present invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

We Claim:
1. An etchant composition for titanium-aluminum complex metal layer comprising, on the basis of the total weight of the etchant composition, about 0.1 wt% to about 5 wt% of at least one quaternary ammonium compound containing fluorine, about 0.5 wt% to about 20 wt% of at least one oxidizing agent, about 0.2 wt% to about 20 wt% of at least one acidic compound, and an aqueous medium.
2. The etchant composition according to Claim 1, wherein the titanium-aluminum complex metal layer comprises at least one titanium or titanium alloy metal layer and at least one aluminum or aluminum alloy metal layer.
3. The etchant composition according to Claim 1, wherein a taper angle of an etched titanium-aluminum complex metal layer is in a range of about 20 degrees to about 60 degrees.
4. The etchant composition according to Claim 1, wherein the quaternary ammonium compound containing fluorine has a general formula of R1R2R3R4N F, wherein Ri, R2, R3, and R4 can be identical or different and are independently straight or branched Ci- Cβ-alkyl, straight or branched C2-C6-alkenyl, or C3-Cs-cycloalkyl, wherein alkyl, alkenyl or cycloalkyl can be optionally substituted with at least one hydroxyl.
5. The etchant composition according to Claim 4, wherein Ri, R2, R3, and R4 can be identical or different and are independently straight or branched Ci-C4-alkyl.
6. The etchant composition according to Claim 5, wherein the quaternary ammonium compound containing fluorine comprises tetramethyl ammonium fluoride, tetraethyl ammonium fluoride, tetrapropyl ammonium fluoride, or tetrabutyl ammonium fluoride.
7. The etchant composition according to Claim 1, 4, 5 or 6, wherein on the basis of the total weight of the etchant composition, the content of the quaternary ammonium compound containing fluorine is from about 0.2 wt% to about 3 wt%.
8. The etchant composition according to Claim 1, wherein the oxidizing agent is selected from the group consisting of nitric acid, ammonium nitrate, cerium ammonium nitrate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, ammonium peroxydisulfate, potassium peroxydisulfate, hydrogen peroxide, and mixtures thereof.
9. The etchant composition according to Claim 1 or 8, wherein on the basis of the total weight of the etchant composition, the content of the oxidizing agent is from about 0.5 wt% to about 10 wt%.
10. The etchant composition according to Claim 1, wherein the acidic compound is selected from the group consisting of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, and mixtures thereof.
11. The etchant composition according to Claim 1 or 10, wherein on the basis of the total weight of the etchant composition, the content of the acidic compound is from about 0.5 wt% to about 5 wt%.
12. The etchant composition according to any one of Claims 1, 2, 3, 4, 5, 6, 8, and 10, wherein the aqueous medium is ultrapure water or deionized water.
13. A process for etching a titanium-aluminum complex metal layer, comprising the steps of:
providing a substrate;
forming a first titanium metal layer on the substrate;
forming an aluminum metal layer on the first titanium metal layer; forming a second titanium metal layer on the aluminum metal layer;
forming a patterned photoresist layer on the second titanium metal layer; and etching the first titanium metal layer, the aluminum metal layer, and the second titanium metal layer with the etchant composition according to any one of Claims 1 to 12 through the patterned photoresist layer as a mask.
14. The process according to Claim 13, wherein the first titanium metal layer and the second titanium metal layer comprises titanium or titanium alloy, and the aluminum metal layer comprises aluminum or aluminum alloy.
15. The process according to Claim 13, wherein the first titanium metal layer and the second titanium metal layer are formed by using a physical vapor deposition, a chemical vapor deposition or an electroplating process.
16. The process according to Claim 13, wherein the substrate is a silicon substrate or a glass substrate.
17. The process according to any one of Claims 13 to 16, wherein a taper angle of an etched titanium- aluminum complex metal layer is in a range of about 20 degrees and about 60 degrees.
18. The process according to any one of Claims 13 to 16, wherein the etching step is performed at a temperature of about 15°C to about 500C.
19. The process according to any one of Claims 13 to 16, wherein an etching time is about 0.5 minutes to about 10 minutes.
PCT/EP2010/060042 2009-07-22 2010-07-13 Etchant composition and etching process for titanium-aluminum complex metal layer WO2011009764A1 (en)

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