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US20070117304A1 - Method for patterning hfo2-containing dielectric - Google Patents

Method for patterning hfo2-containing dielectric Download PDF

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Publication number
US20070117304A1
US20070117304A1 US11/624,703 US62470307A US2007117304A1 US 20070117304 A1 US20070117304 A1 US 20070117304A1 US 62470307 A US62470307 A US 62470307A US 2007117304 A1 US2007117304 A1 US 2007117304A1
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hfo2
layer
dielectric
wafer
gate dielectric
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US11/624,703
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Jeng-Huey Hwang
Wei-Tsun Shiau
Chien-Ting Lin
Jiunn-Ren Hwang
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United Microelectronics Corp
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    • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
    • H01L21/31116—Etching inorganic layers by chemical means by dry-etching
    • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
    • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
    • H01L21/31116—Etching inorganic layers by chemical means by dry-etching
    • H01L21/31122—Etching inorganic layers by chemical means by dry-etching of layers not containing Si, e.g. PZT, Al2O3
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D64/00—Electrodes of devices having potential barriers
    • H10D64/60—Electrodes characterised by their materials
    • H10D64/66—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes
    • H10D64/68—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator
    • H10D64/691—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator comprising metallic compounds, e.g. metal oxides or metal silicates 
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
    • H10D84/01—Manufacture or treatment
    • H10D84/0123—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs
    • H10D84/0126—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs
    • H10D84/0144—Manufacturing their gate insulating layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
    • H10D84/01—Manufacture or treatment
    • H10D84/0123—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs
    • H10D84/0126—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs
    • H10D84/0151—Manufacturing their isolation regions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
    • H10D84/01—Manufacture or treatment
    • H10D84/02—Manufacture or treatment characterised by using material-based technologies
    • H10D84/03—Manufacture or treatment characterised by using material-based technologies using Group IV technology, e.g. silicon technology or silicon-carbide [SiC] technology
    • H10D84/038—Manufacture or treatment characterised by using material-based technologies using Group IV technology, e.g. silicon technology or silicon-carbide [SiC] technology using silicon technology, e.g. SiGe
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D30/00—Field-effect transistors [FET]
    • H10D30/60—Insulated-gate field-effect transistors [IGFET]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00—Semiconductor device manufacturing: process
    • Y10S438/906—Cleaning of wafer as interim step

Definitions

  • the invention relates to a method for patterning an HfO2-containing dielectric, and more particularly, to a method for patterning an HfO2-containing gate dielectric without damaging STI positioned on the same wafer.
  • Hf hafnium
  • HfO2-containing dielectric including HfO2, HfSiO, HfSiON, HfAIO, and so on
  • the conventional method of etching the HfO2-containing dielectric involves using a strong acid, such as 49% HF solution.
  • a SiO2 layer such as a shallow trench isolation (STI) layer, will be also removed.
  • the etching rate of the SiO2 layer is much higher than that of the HfO2-containing dielectric, and the SiO2 layer will be seriously damaged while patterning the HfO2-containing dielectric.
  • Another conventional method of etching the HfO2-containing dielectric is using a high insert gas plasma with more than 60% Ar.
  • the insert gas plasma has no selectivity while etching, and may also result in the SiO2 layer being damaged during over-etch.
  • FIGS. 1 and 2 show a conventional etching process of the HfO2-containing dielectric.
  • An STI layer 18 is formed on a wafer 10 , and an HfO2-containing gate dielectric 12 covers the wafer 10 and the STI layer 18 .
  • a gate electrode 16 is formed on the HfO2-containing gate dielectric 12 , and two spacers 14 are formed beside the gate electrode 16 .
  • the conventional etching process such as using the strong acid or the insert gas plasma is performed to remove portions of the HfO2-containing gate dielectric 12 .
  • the etching selectively between the HfO2-containing gate dielectric 12 and the STI layer 18 is too low to bring serious damages atop the STI layer 18 . As a result, the isolation effect of the STI layer 18 is reduced.
  • a method for patterning an HfO2-containing gate dielectric comprises providing a wafer having a trench, a STI layer formed in the trench, the HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode. Following that, the wafer is preheated and a bromine-rich gas plasma is provided to remove portions of the HfO2-containing gate dielectric.
  • a method for patterning an HfO2-containing gate dielectric comprises providing a wafer having a trench, a STI layer formed in the trench, the HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode.
  • an ion bombardment utilizing Ar, He, O2, CHF3, or mixture thereof is used to convert the exposed HfO2-containing gate dielectric to an intergraded layer.
  • a wet chemical is used to remove the intergraded layer.
  • the bromine-rich gas plasma has a high selectivity between the HfO2-containing dielectric and the SiO2layer, so that the HfO2-containing dielectric can be etched without damaging the SiO2layer.
  • the nitrogen ion bombardment can convert the HfO2-containing dielectric to the Hf3N4 layer and the wet chemical has a high selectivity between the Hf3N4 and SiO2layers, so that the HfO2-containing dielectric can be etched without damaging the SiO2layers.
  • FIG. 1 is a schematic diagram of a wafer before performing a gate dielectric patterning process thereon according to the prior art
  • FIG. 2 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to the prior art
  • FIG. 3 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to the present invention.
  • FIG. 4 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to a second embodiment of the present invention.
  • FIG. 3 shows a result of performing a patterning process according to a first embodiment of the present invention.
  • a bromine-rich gas plasma is utilized to accomplish the requirement of etching the HfO2-containing dielectric with a high selectivity.
  • a MOS transistor fabrication is used to explain the present invention.
  • the half-manufactured wafer is similar to that of the prior art as shown in FIG. 1 .
  • the STI layer 18 is formed on the wafer 10
  • the HfO2-containing gate dielectric 12 covers the wafer 10 and the STI layer 18 .
  • the gate electrode 16 is formed on the HfO2-containing gate dielectric 12 , and two spacers 14 are formed beside the gate electrode 16 .
  • the STI layer 18 and the spacer 14 may be formed of SiO2, and the gate electrode 16 may be formed of TaN or TiN.
  • the reactor can be any type of plasma reactors, such as the parallel plate, the reactive ion etcher (RIE), the inductively coupled plasma (ICP), or the electron cyclotron resonance etcher (ECR), and the preheating procedure can utilize a lamp tray or a non-reactive gas plasma to preheat the wafer 10 .
  • RIE reactive ion etcher
  • ICP inductively coupled plasma
  • ECR electron cyclotron resonance etcher
  • the bromine-rich gas plasma is supplied into the reactor to remove portions of the HfO2-containing gate dielectric 12 .
  • the bromine-rich gas plasma can be a Br2 plasma, a HBr plasma, or a mixture of a Br2 plasma and a HBr plasma, and concentration of the bromine-rich gas plasma is higher than 30%.
  • the bromine-rich gas plasma will react with the HfO2-containing gate dielectric 12 and produce a volatile product HfBr4.
  • HfBr4 is volatile and can be taken out by the pumping system.
  • the STI layer 18 After removing portions of the HfO2-containing gate dielectric 12 , the STI layer 18 is exposed. Since the bromine-rich gas plasma etches the SiO2material of the STI layer 18 much slower than the HfO2-containing gate dielectric 12 , the STI layer 18 will be almost undamaged.
  • a sacrifice layer (not shown) can be further formed on the gate electrode 16 before performing the patterning process to protect the gate electrode 16 .
  • the sacrifice layer may be formed of SiO2.
  • additive gases such as Ar, N2, He, O2, CHF3, etc.
  • additive gases can be introduced into the reactor to assist uniform etching of the HfO2-containing gate dielectric 12 .
  • the present invention is not limited to pattern the HfO2-containing gate dielectric.
  • the present invention is also applicable in any etching process relating to pattern HfO2-containing dielectric. For example, a wafer having an HfO2-containing dielectric is provided, and the wafer is preheated to a predetermined temperature. Following that, a bromine-rich gas plasma is provided to remove portions of the HfO2-containing dielectric, thus providing a high etching selectivity in etching HfO2.
  • Another embodiment of the present invention is utilizing a nitrogen ion bombardment to convert the exposed HfO2-containing dielectric to an Hf3N4 (Hafnium Nitride) layer and then utilizing a wet chemical, such as phosphoric acid, to remove the Hf3N4 layer.
  • a nitrogen ion bombardment is performed on the half-manufactured wafer 10 , and the exposed HfO2-containing gate dielectric 12 is converted to an Hf3N4 layer 20 .
  • a nitrogen gas or a nitrogen-contained gas can be used to produce the nitrogen ions.
  • the regions covered by the gate electrode 16 and the spacers 14 are protected and retain the HfO2-containing material.
  • a sacrifice layer (not shown) can be also formed on the gate electrode 1 6 before performing the nitrogen ion bombardment to protect the gate electrode 16 .
  • the Hf3N4 layers 20 are formed beside the portion of HfO2-containing gate dielectrics 12 under the gate electrode 16 and the spacers 14 .
  • the Hf3N4 layers 20 are easily etched by the phosphoric acid.
  • a H3PO4 solution is utilized to remove the Hf3N4 layers 20 , but the H3PO4 solution etches neither the SiO2layer nor the Si layer.
  • the STI layers 18 will be almost undamaged after the Hf3N4 layers 20 is removed.
  • the H3PO4 solution can be maintained at the temperature 50° C.-300° C. It is also worthy of notice that the present invention is not limited to pattern the HfO2-containing gate dielectric.
  • the present invention is also applicable in any etching process relating to pattern HfO2-containing dielectric.
  • a wafer having an HfO2-containing dielectric is provided, and a nitrogen ion bombardment is used to convert portions of the HfO2-containing dielectric to an Hf3N4 layer.
  • a wet chemical such as phosphoric acid is used to remove the Hf3N4 layer, thus providing a high etching selectivity in etching HfO2.
  • the present invention has a high etching selectivity between the HfO2-containing material and the SiO2material, so that the STI layer can be retained complete after the gate dielectric is removed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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Abstract

A wafer has a trench, a STI layer formed in the trench, an HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode. An ion bombardment utilizing Ar, He, O2, CHF3 or mixture thereof is performed to convert the exposed HfO2-containing gate dielectric to an intergraded layer, and a wet chemical is utilized to remove the intergraded layer.

Description

    CROSS REFERENCE TO RELATED APPLICATIONS
  • This is a continuation application of U.S. patent application Ser. No. 11/160,629, filed Jun. 30, 2005, which itself is a divisional of application Ser. No. 10/710,581 filed Jul. 22, 2004.
    • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The invention relates to a method for patterning an HfO2-containing dielectric, and more particularly, to a method for patterning an HfO2-containing gate dielectric without damaging STI positioned on the same wafer.
  • 2. Description of the Prior Art
  • For realizing the low power MOS transistor at the 65 nm node and beyond, it is necessary to reduce the gate leakage current for thinner gate dielectrics. The introduction of high-k gate material would be advantageous for extending current MOS technology. After several years of work, many research groups are now focusing on hafnium (Hf) based material and are evaluating the natural of these materials extensively. Among the considerable Hf-based materials, HfO2 is often evaluated to be combined into a metal gate structure.
  • However, HfO2-containing dielectric (including HfO2, HfSiO, HfSiON, HfAIO, and so on) is known for more difficult to be pattern etched comparing to SiO2 based dielectric. The conventional method of etching the HfO2-containing dielectric involves using a strong acid, such as 49% HF solution. When using the 49% HF solution to etch the HfO2-containing dielectric, a SiO2 layer, such as a shallow trench isolation (STI) layer, will be also removed. Furthermore, the etching rate of the SiO2 layer is much higher than that of the HfO2-containing dielectric, and the SiO2 layer will be seriously damaged while patterning the HfO2-containing dielectric.
  • Another conventional method of etching the HfO2-containing dielectric is using a high insert gas plasma with more than 60% Ar. The insert gas plasma has no selectivity while etching, and may also result in the SiO2 layer being damaged during over-etch.
  • Please refer to FIGS. 1 and 2, which show a conventional etching process of the HfO2-containing dielectric. An STI layer 18 is formed on a wafer 10, and an HfO2-containing gate dielectric 12 covers the wafer 10 and the STI layer 18. A gate electrode 16 is formed on the HfO2-containing gate dielectric 12, and two spacers 14 are formed beside the gate electrode 16. As shown in FIG. 2, the conventional etching process such as using the strong acid or the insert gas plasma is performed to remove portions of the HfO2-containing gate dielectric 12. The etching selectively between the HfO2-containing gate dielectric 12 and the STI layer 18 is too low to bring serious damages atop the STI layer 18. As a result, the isolation effect of the STI layer 18 is reduced.
    • SUMMARY OF THE INVENTION
  • It is therefore a primary objective of the claimed invention to provide a method for patterning the HfO2-containing gate dielectric without damaging the SiO2 layer to solve the above-mentioned problem.
  • According to the claimed invention, a method for patterning an HfO2-containing gate dielectric comprises providing a wafer having a trench, a STI layer formed in the trench, the HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode. Following that, the wafer is preheated and a bromine-rich gas plasma is provided to remove portions of the HfO2-containing gate dielectric.
  • According to the claimed invention, a method for patterning an HfO2-containing gate dielectric comprises providing a wafer having a trench, a STI layer formed in the trench, the HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode. Following that, an ion bombardment utilizing Ar, He, O2, CHF3, or mixture thereof is used to convert the exposed HfO2-containing gate dielectric to an intergraded layer. A wet chemical is used to remove the intergraded layer.
  • It is an advantage of the claimed invention that the bromine-rich gas plasma has a high selectivity between the HfO2-containing dielectric and the SiO2layer, so that the HfO2-containing dielectric can be etched without damaging the SiO2layer.
  • It is another advantage of the claimed invention that the nitrogen ion bombardment can convert the HfO2-containing dielectric to the Hf3N4 layer and the wet chemical has a high selectivity between the Hf3N4 and SiO2layers, so that the HfO2-containing dielectric can be etched without damaging the SiO2layers.
  • These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic diagram of a wafer before performing a gate dielectric patterning process thereon according to the prior art;
  • FIG. 2 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to the prior art;
  • FIG. 3 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to the present invention; and
  • FIG. 4 is a schematic diagram of a wafer after performing a gate dielectric patterning process thereon according to a second embodiment of the present invention.
    • DETAILED DESCRIPTION
  • Please refer to FIG. 3, which shows a result of performing a patterning process according to a first embodiment of the present invention. In the first embodiment of the present invention, a bromine-rich gas plasma is utilized to accomplish the requirement of etching the HfO2-containing dielectric with a high selectivity. In this embodiment, a MOS transistor fabrication is used to explain the present invention. Before the etching process, the half-manufactured wafer is similar to that of the prior art as shown in FIG. 1. For example, the STI layer 18 is formed on the wafer 10, and the HfO2-containing gate dielectric 12 covers the wafer 10 and the STI layer 18. The gate electrode 16 is formed on the HfO2-containing gate dielectric 12, and two spacers 14 are formed beside the gate electrode 16. The STI layer 18 and the spacer 14 may be formed of SiO2, and the gate electrode 16 may be formed of TaN or TiN.
  • Then, the wafer 10 is placed into a reactor and is preheated to 200° C. or over 200° C. The reactor can be any type of plasma reactors, such as the parallel plate, the reactive ion etcher (RIE), the inductively coupled plasma (ICP), or the electron cyclotron resonance etcher (ECR), and the preheating procedure can utilize a lamp tray or a non-reactive gas plasma to preheat the wafer 10.
  • After the wafer 10 is preheated to 200° C. or over 200° C., the bromine-rich gas plasma is supplied into the reactor to remove portions of the HfO2-containing gate dielectric 12. The bromine-rich gas plasma can be a Br2 plasma, a HBr plasma, or a mixture of a Br2 plasma and a HBr plasma, and concentration of the bromine-rich gas plasma is higher than 30%. On the wafer surface, the bromine-rich gas plasma will react with the HfO2-containing gate dielectric 12 and produce a volatile product HfBr4. At the elevated temperature (≧200° C.), HfBr4 is volatile and can be taken out by the pumping system. After removing portions of the HfO2-containing gate dielectric 12, the STI layer 18 is exposed. Since the bromine-rich gas plasma etches the SiO2material of the STI layer 18 much slower than the HfO2-containing gate dielectric 12, the STI layer 18 will be almost undamaged. In addition, a sacrifice layer (not shown) can be further formed on the gate electrode 16 before performing the patterning process to protect the gate electrode 16. The sacrifice layer may be formed of SiO2.
  • Furthermore, in other embodiments of the present invention, additive gases, such as Ar, N2, He, O2, CHF3, etc., can be introduced into the reactor to assist uniform etching of the HfO2-containing gate dielectric 12. It is also worthy of notice that the present invention is not limited to pattern the HfO2-containing gate dielectric. The present invention is also applicable in any etching process relating to pattern HfO2-containing dielectric. For example, a wafer having an HfO2-containing dielectric is provided, and the wafer is preheated to a predetermined temperature. Following that, a bromine-rich gas plasma is provided to remove portions of the HfO2-containing dielectric, thus providing a high etching selectivity in etching HfO2.
  • Another embodiment of the present invention is utilizing a nitrogen ion bombardment to convert the exposed HfO2-containing dielectric to an Hf3N4 (Hafnium Nitride) layer and then utilizing a wet chemical, such as phosphoric acid, to remove the Hf3N4 layer. Please refer to FIG. 4, which shows the patterning process of the second embodiment. A nitrogen ion bombardment is performed on the half-manufactured wafer 10, and the exposed HfO2-containing gate dielectric 12 is converted to an Hf3N4 layer 20. While performing the nitrogen ion bombardment, a nitrogen gas or a nitrogen-contained gas can be used to produce the nitrogen ions. The regions covered by the gate electrode 16 and the spacers 14 are protected and retain the HfO2-containing material. Selectively, a sacrifice layer (not shown) can be also formed on the gate electrode 1 6 before performing the nitrogen ion bombardment to protect the gate electrode 16.
  • After the nitrogen ion bombardment, the Hf3N4 layers 20 are formed beside the portion of HfO2-containing gate dielectrics 12 under the gate electrode 16 and the spacers 14. The Hf3N4 layers 20 are easily etched by the phosphoric acid. In this embodiment, a H3PO4 solution is utilized to remove the Hf3N4 layers 20, but the H3PO4 solution etches neither the SiO2layer nor the Si layer. The STI layers 18 will be almost undamaged after the Hf3N4 layers 20 is removed. In addition, for speeding the removing process, the H3PO4 solution can be maintained at the temperature 50° C.-300° C. It is also worthy of notice that the present invention is not limited to pattern the HfO2-containing gate dielectric. The present invention is also applicable in any etching process relating to pattern HfO2-containing dielectric. For example, a wafer having an HfO2-containing dielectric is provided, and a nitrogen ion bombardment is used to convert portions of the HfO2-containing dielectric to an Hf3N4 layer. Following that, a wet chemical such as phosphoric acid is used to remove the Hf3N4 layer, thus providing a high etching selectivity in etching HfO2.
  • In contrast to the prior art, the present invention has a high etching selectivity between the HfO2-containing material and the SiO2material, so that the STI layer can be retained complete after the gate dielectric is removed.
  • Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims (9)

1. A method for patterning an HfO2-containing gate dielectric, the method comprising:
providing a wafer having a trench, a STI layer formed in the trench, the HfO2-containing gate dielectric covering the wafer and the STI layer, a gate electrode formed on the HfO2-containing gate dielectric, and at least a spacer formed beside the gate electrode;
performing an ion bombardment with Ar, He, O2, CHF3or mixture thereof to convert the exposed HfO2-containing gate dielectric to an intergraded layer having a higher etching selectivity than HfO2; and
utilizing a wet chemical to remove the intergraded layer.
2. The method of claim 1 wherein the STI layer comprises SiO2.
3. The method of claim 1 wherein the spacer comprises SiO2.
4. The method of claim 1 wherein the gate electrode comprises TaN or TiN.
5. The method of claim 1 wherein the method comprises utilizing a nitrogen gas or a nitrogen-contained gas to perform the ion bombardment.
6. The method of claim 1 wherein the intergraded layer is removed at temperature between 50° C. and 300° C.
7. A method for etching an HfO2-containing dielectric, the method comprising:
providing a wafer having the HfO2-containing dielectric;
performing an ion bombardment with Ar, He, O2, CHF3or mixture thereof to convert portions of the HfO2-containing dielectric to an intergraded layer; and
utilizing a wet chemical to remove the intergraded layer.
8. The method of claim 7 wherein the method comprises utilizing a nitrogen gas or a nitrogen-contained gas to perform the ion bombardment.
9. The method of claim 7 wherein the intergraded layer is removed at temperature between 50° C. and 300° C.
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