JPH0793289B2 - Vapor phase etching method for metal surface - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an effective amount of a .beta.-diketone or .beta.-ketoimine ligand dispersed in an oxidizing atmosphere and a method for etching a metal thin film used for manufacturing integrated circuits.

[0002]

BACKGROUND OF THE INVENTION Thin film integrated circuits are manufactured by a number of processes which form successive layers of conductors, semiconductors and insulating materials to create an integrated device of transistors. In the device, in order to create an appropriate structure of each material, various metal patterns are deposited on a substrate, and then necessary portions are selectively etched to form a circuit. The term "etching" used in the processing technology of microelectronics refers to an operation of removing a metal material from a substrate or a thin film deposited on the substrate surface.

The conventional etching method has been carried out by using a "wet etching" technique in which a metal surface to be etched is immersed in a liquid etching agent solution. However, when the liquid etching agent is used, there are various problems such as etching rate, contamination of the integrated circuit board, and management of complicated liquid waste treatment.

The most advanced integrated circuit devices currently manufactured have a strict precision of less than 1 micron. Liquid etching agents are not suitable for controlling such fine dimensions. Therefore, a "dry" etching technique in which an etching agent is applied and etching is performed in a vapor state has received a great deal of attention. Such dry etching methods require that the etching products be sufficiently volatile to effect complete removal from the surface to be etched.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and eliminates the use of environmentally harmful agents.
It is an object of the present invention to provide an etching method capable of manufacturing a high quality integrated circuit device.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a novel vapor phase etching method for a metal thin film in the production of an integrated circuit or a printed wiring board for achieving the above-mentioned object. , An effective amount of a ligand in which the metal surface is dispersed in an oxidizable atmosphere, and a volatile metal-
It is a vapor phase etching method for a metal surface, which comprises contacting under a condition such that a ligand complex can be formed and volatilizing the metal-ligand complex to etch the metal surface. The volatile metal-ligand complex is easily removed from the metal thin film surface by sublimation which etches the metal thin film.
The vapor phase etching method of the present invention eliminates the formation of metal-containing contaminants that interfere with the subsequent formation of conductive metals and other manufacturing processes, and thus eliminates the various types of wet etching solutions associated with conventional wet etching solutions. Can overcome problems.

The etchant used to carry out the method of the present invention comprises a β-diketone or β-ketoimine ligand represented by Formula 6 below.

[0008]

[Chemical 6] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to about 8 carbon atoms. R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated 1 to 1 group, an alkenyl group, or an allyl group. Is an alkyl or alkenyl group having about 8 carbon atoms, Y is an oxygen atom, alkyl having 1 to about 10 carbon atoms in which R ₄ is non-fluorinated, partially fluorinated, or fully fluorinated. Group, an aralkyl group or a hydroxyalkyl group, selected from N—R ₄ or represented by the following chemical formula 7.

[0009]

[Chemical 7] However, in the formula, R ₅ , R ₆ and R ₇ are each independently a hydrogen atom, a fluorine atom, a fluorinated atom, or a linear or branched non-fluorinated, partially fluorinated, or completely fluorinated. An alkyl group or an alkenyl group having 1 to about 8 carbon atoms, represented by R
₈ is a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated alkylene group having 1 to about 8 carbon atoms, an alkenylene group, a phenylene group, an alkylphenylene group, or hydroxy. It is an alkylene group.

The above chemical formula 6 shows three kinds of ligands having different properties, each of which is suitable for the etching method of the present invention. The difference between the three types of ligands is characterized by the aforementioned Y component. When Y is an oxygen atom, the ligand is β-diketone and Y
In ligand β- ketoimine When There is _{N-R 3,} Y
Is represented by the structure according to Chemical Formula 7, the ligand consists of two β-ketoimines bridged by an organic functional group.

The method of the present invention offers numerous advantages over conventional wet etching methods. One is that the etching process can be implemented immediately on the spot. The implication is that there is no risk of contamination due to exposure to contaminants that would cause the circuit device to be moved elsewhere, such as in the case of wet etching, where there is equipment for performing etching operations. It is not necessary to go through a clean room. Furthermore, the etching method of the present invention does not leave a residue on the surface of the electronic circuit device, which may interfere with the subsequent processing steps by the etching agent used.

[0012]

The present invention is a vapor phase etching method used for etching a metal thin film or the like when processing an electronic device such as an integrated circuit device or a printed wiring board. As described above, the vapor phase etching method of the present invention has various excellent advantages as compared with the conventional wet etching method.

In the metal etching method described in the present specification, a part of a metal thin film to be etched is dispersed in an oxidizing atmosphere under a temperature condition sufficient to form a volatile metal-ligand complex. And an effective amount of β-diketone or β-ketoimine is brought into contact with the etching agent. The volatile metal-ligand complex can be removed by sublimation from the surface of the metal thin film, and the continuous layer of the metal thin film can be easily removed by etching. When the etching method according to the present invention is used, there is no possibility of forming metal-containing contaminants that may interfere with the subsequent processing of a circuit board device such as a printed wiring board.

In the process according to the invention, the metal to be etched is continuously oxidized in situ and then immediately formed with a volatile metal-ligand complex, or these steps are carried out. Do in stages. In the stepwise method, the metal to be etched is kept in contact with the oxidizing atmosphere at the oxidation surface for a predetermined time for etching the metal, and when a predetermined etching time is reached, an effective amount of ligand is added. Dispersed oxidizing atmosphere or nitrogen,
Etching is performed by exposing the metal to helium or other inert gas.

The metal thin film which can be etched by the method of the present invention is MO, MO ₂ , MO ₃ , M ₂ O and M ₂ O when exposed to an oxidizing atmosphere at the working temperatures indicated above.
A metal oxide represented by a chemical formula containing ₃ or M ^{+ n} X
^-N [wherein n is 1, 2 or 3 and X is a halogen selected from Ci, Br or I], and any metal can be used as long as it can form a metal halide. Suitable metals for etching include gold, copper, iron, indium and tin. The method of the present invention is suitable for etching metal thin films deposited on substrates in the electronic device industry as well as etching for patterning bulky metal objects.

A wide variety of substrates are suitable for practicing the present invention,
Any suitable substrate may be used as long as it has a metal layer deposited on its surface. Typical methods of depositing thin films on such substrates include chemical vapor deposition techniques. Representative substrates include, but are not limited to, silicon, silicon oxide, borophosphosilicate glass, phosphosilicate glass and strontium titanate.

A suitable etching agent for etching the exposed portion of the metal thin film is β-diketone or β-ketoimine represented by the following chemical formula 8.

[0018]

[Chemical 8] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to about 8 carbon atoms. R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated 1 to 1 group, an alkenyl group, or an allyl group. Is an alkyl or alkenyl group having about 8 carbon atoms, Y is an oxygen atom, alkyl having 1 to about 10 carbon atoms in which R ₄ is non-fluorinated, partially fluorinated, or fully fluorinated. Group, an aralkyl group, or a hydroxyalkyl group, selected from N—R ₄ , or the following chemical formula 9.

[0019]

[Chemical 9] However, in the formula, R ₅ , R ₆ and R ₇ are each independently a hydrogen atom, a fluorine atom, a fluorinated atom, or a linear or branched non-fluorinated, partially fluorinated, or completely fluorinated. An alkyl group or an alkenyl group having 1 to about 8 carbon atoms, represented by R
₈ is a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated alkylene group having 1 to about 8 carbon atoms, an alkenylene group, a phenylene group, an alkylphenylene group, or hydroxy. It is an alkylene group.

In this case, the ligand is malleable to oxidize the metal surface to form a volatile metal ligand complex, or react with the ligand to form the complex. Disperse in atmosphere.

The above chemical formula 8 shows three kinds of ligands having different properties, each of which is suitable for the etching method of the present invention. The difference between the three types of ligands is characterized by the aforementioned Y component. When Y is an oxygen atom, the ligand is β-diketone and Y
In ligand β- ketoimine When There is _{N-R 3,} Y
Is represented by the structure according to Chemical Formula 9 above, the ligand consists of two β-ketoimines bridged with an organic functional group. The volatility of these materials depends on the degree of fluorination. Therefore, the volatility of partially fluorinated or fully fluorinated ligands is generally higher than that of non-fluorinated ligands.

Non-fluorinated, partially fluorinated and fully fluorinated β-diketone ligands suitable for use in the present method are represented by Formula 10 below:

[0023]

[Chemical 10] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to about 8 carbon atoms. R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated 1 to 1 group, an alkenyl group, or an allyl group. An alkyl or alkenyl group having about 8 carbon atoms.

In a preferred embodiment according to formula 10,
R ₂ is a hydrogen atom or a fluorine atom, and R ₁ and R ₃ are
Each independently selected from straight chain, fully fluorinated alkyl groups having 1 to 4 carbon atoms. Suitable alkyl groups to be fluorinated include such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl groups.

The non-fluorinated, partially fluorinated and fully fluorinated β-ketoimine ligands according to the present invention are represented by the following chemical formula 1.
Indicated by 1:

[0026]

[Chemical 11] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to about 8 carbon atoms. R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated 1 to 1 group, an alkenyl group, or an allyl group. Is an alkyl or alkenyl group having about 8 carbon atoms, R ₄ is a non-fluorinated, partially fluorinated, or fully fluorinated alkyl group having 1 to 10 carbon atoms, an aralkyl group, or It is selected from hydroxyalkyl groups. A preferable method for preparing the β-ketoimine ligand represented by the above chemical formula 11, more specifically, the partially fluorinated or fully fluorinated β-ketoimine ligand, is disclosed in US Pat. No. 4,950,790. ing. In a preferred embodiment R ₁
And R ₂ are each independently selected from perfluorinated straight-chain or branched alkyl groups having 1 to 4 carbon atoms. Suitable alkyl groups to be fluorinated include methyl, ethyl, propyl, isopropyl, butyl, isobutyl and t-butyl groups.

The preparation of the .beta.-ketoimines is carried out by treating the analogous .beta.-diketone with potassium hydride under conditions sufficient to produce the potassium salt of the diketone, followed by salification of the resulting potassium salt of the diketone. Reaction with a silyl, for example t-butyldimethylsilyl chloride, to produce a silylene ether having the following Formula 12:

[0028]

[Chemical 12] R ₉ in the formula is a linear or branched alkyl group having 1 to 4 carbon atoms. Silinol ale,
A given β-ketoimine can be prepared by treatment with a primary monoamine, R ₃ NH ₂ , where R ₃ is as defined above.

The non-fluorinated, partially fluorinated and fully fluorinated bridged β-ketoimine ligands of the present invention are represented by Formula 13 below:

[0030]

[Chemical 13] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to about 8 carbon atoms. R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched, non-fluorinated, partially fluorinated, or fully fluorinated 1 to 1 group, an alkenyl group, or an allyl group. It is an alkyl group or an alkenyl group having about 8 carbon atoms, and R ₅ , R ₆ and R ₇ are each independently a hydrogen atom, a fluorine atom, a fluorinated atom, or a linear or branched non-chain. Fluorinated, partially fluorinated or fully fluorinated, selected from alkyl or alkenyl groups having 1 to about 8 carbon atoms, R ₈ is linear or branched. Non-fluorinated, partially fluorinated, Is an alkylene group, an alkenylene group, a phenylene group, alkylphenylene group or a hydroxyalkylene group having fully fluorinated 1 to about 8 carbon atoms.

In a preferred embodiment, R ₁ and R ₃ are each independently selected from perfluorinated straight-chain or branched alkyl groups having 1 to 4 carbon atoms, R ₂ Is a hydrogen atom or a fluorine atom. Suitable alkyl groups for fluorination use include methyl, ethyl, propyl, isopropyl, butyl, isobutyl and t-butyl groups.

A preferred method for preparing the crosslinked β-ketoimine compound according to Formula 13 is US Pat. No. 4,950,790.
No. 6,096,096, the specification of which is incorporated herein by reference. These ligands are treated with analogous β-diketones under conditions sufficient to form potassium hydride and potassium salts of the diketones, followed by reaction with the resulting t-butyldimethylsilyl chloride to produce the silicic acid of formula 12. Produces Renol ether. The silylenol ether is then treated with a primary diamine, NH ₂ R ₃ NH ₂ [wherein
R ₃ is reacted with one equivalent of the above as defined] to produce a predetermined cross β- ketimine.

The ligand of the present invention can exist as two tautomers of keto and enol, and the structure of the enol form can be easily confirmed by those skilled in the art. Descriptions of the keto forms of the above ligands of the present invention are also included in similar enol forms.

As described above, the present etching method is carried out in an atmosphere capable of oxidizing the metal to be etched. And as such an oxidizing atmosphere,
Oxygen gas, steam Zero grade air (about 19.5 to 2
Consisting of 3.5 mol% oxygen, 0.5 mol% hydrocarbons and the balance nitrogen, sold by Air Products and Chemicals, Inc., Allentown, PA), HC
1, such as HF, Cl ₂ , Br ₂ . Moreover, the oxidizing atmosphere is argon, nitrogen, helium and perfluorinated hydrocarbons such as "Multifluo" commercially available from Air Products and Chemicals, Inc. of Allentown, PA.
r ^R ) "APF-200 can be dispersed in a carrier gas such as perfluoroisopropyldecalin.

In the etching method of the present invention, the etching agent can be applied to the object to be etched, mechanically or manually, using well-known methods including etching methods by foaming, wave dipping, spraying and brushing. Foam,
The method of applying the etching agent by wave and dipping is suitable as a working method for a circuit board having a board hole because the hole can be immersed in a capillary tube. The etching agent and oxidizing atmosphere used in the method of the present invention, the type and amount of the inert gas used as a carrier gas, the type and amount of the metal thin film to be etched, the sensitivity of the material to be etched to the etching agent, It depends on many factors such as the amount of time that the etching process is exposed.

The vapor phase etching method of the present invention will be described below with reference to a concrete embodiment. The metal substance or substrate on which the metal thin film is deposited is placed in an infrared furnace, a vapor phase generation furnace or other well-known etching or deposition apparatus,
To heat. A given β-diketone or β-ketoimine and an oxidizing atmosphere (eg oxygen gas for the production of electronic components) are passed through the heating zone of the furnace by known techniques. An oxidizing atmosphere saturated with a ligand is continuously or intermittently fed into the furnace.
The ligand reacts with the metal oxide or metal halide present on the thin film to form a volatile metal-ligand complex in situ. The surface of the metal layer reacts with the oxygen-containing atmosphere at high temperature to form a continuous layer of continuously oxidized metal oxide, which then reacts with the ligand. Then, the generated volatile metal-ligand complex is conveniently evaporated from the surface of the metal thin film to form an etching surface. At this time, a desired etching pattern can be obtained by covering the non-etched portion with a known masking technique.

The β-diketone ligand of the present invention is a conventional oxide (CuO, Cu) produced in a metal thin film deposited on a substrate.
₂ O, PbO, SuO). The products obtained as a result of the reaction are Cu (HFa)
c) ₂ , Pb (HFac) ₂ and Sn (HFac) ₂ . And these substances can be completely evaporated in the next evaporation step without leaving a residue on the substrate. The etchant should be used in an amount that provides maximum etching activity. The appropriate concentration depends on the ligand used and the metal-containing compound to be etched, but is dispersed in the desired oxidizing atmosphere.

The embodiments described above represent a significant advance in gas phase etching processes. The conventional gas phase etching method for the present invention is a typical heating temperature of 190 to 23 required for manufacturing a printed wiring board.
It was said that the use at 0 ° C was inappropriate. In the gas phase etching method of the present invention, the above-mentioned ligands are easily saturated in an oxidizing atmosphere and preferentially react with metal oxides without a catalyst to leave a residue on the material to be etched. Since it forms a reaction product which can be completely volatilized without any action, it has many advantages over conventional methods. The etching method of the present invention can be carried out at 200 to 230 ° C., which is almost the same temperature as that used in the conventional method. or,
The optimum reaction time and temperature for carrying out the present invention vary depending on the selected ligand and the type of metal used for etching, but the time is usually 5 to 50 minutes. The pressure in the furnace is not critical to the practice of the etching process of the present invention, but is usually performed at about 0-1.5 psig.

[0039]

EXAMPLE Copper with hexafluoroacetylacetone
Thin Film Etching A copper thin film (about 5,000 Å) is deposited on a slide glass substrate by a general vapor deposition method, about half of the substrate is shielded with a polyimide tape, and the shield slide glass is cut at an angle of 30 degrees to a Pyrex sample. I put it in a container. The filtered zero grade air is 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (usual name: hexafluoroacetylacetone, also referred to as HFac in this document, Storm Chemicals, Inc. of Newport). 20 sccm or 12.0% HFa in the process stream
Bubbling was carried out at a ratio of cf. After about 1 minute, a pale green precipitate was formed on the wall of the reaction vessel downstream along the cooling section. This indicates the production of volatile Cu (HFac). After completion, the non-interrupted part of the copper thin film was etched down to the glass substrate, although traces of metal residue due to the non-laminated flow pattern in the reactor remained. As a result, it was found that the metal thin film was etched under the polyimide mask and was uniformly etched.

Representative ligands suitable for use in the present invention are disclosed below and show both the chemical formula and IUPAC as well as the abbreviation for the ligand: 4- (2,2,2-trifluoroethyl) -Imino-
1,1,1,5,5,5-hexafluoro-2-pentanone (H) NONA-F [TFEA]

[0041]

[Chemical 14] 5- (2,2,2-trifluoroethyl) imino-1,
1,1,2,2,6,6,6-octafluoro-3-hexanone (H) UNDECA-F [TFEA]

[0042]

[Chemical 15] 6- (2,2,2-trifluoroethyl) imino-1,
1,1,2,2,3,3,7,7,7-decafluoro-
4-heptanone (H) TRIDECA-F [TFEA]

[0043]

[Chemical 16] 4- (phenyl) imino-1,1,1,5,5,5-
Hexafluoro-2-pentanone (H) HEXA-F [AN]

[0044]

[Chemical 17] 4- (2-hydroxyethyl) imino-1,1,1,
5,5,5-Hexafluoro-2-pentanone (H) HEXA-F [EDA]

[0045]

[Chemical 18] 1,2-di [4-imino-1,1,1,5,5,5-hexafluoro-2-pentanone] ethane (H ₂ ) DODECA-F [EDA]

[0046]

[Chemical 19] 1,2-di- [5-imino-1,1,1,2,2,6,
6,6-octafluoro-3-hexanone] ethane _{(H 2) HEXADECA-F [} EDA]

[0047]

[Chemical 20] 1,2-di [6-imino-1,1,1,2,2,3,
3,7,7,7- deca fluoro-4-heptanone] ethane _{(H 2) EiCOSA-F [} EDA]

[0048]

[Chemical 21] Bis [4- (methylene) imino-1,1,1,5,5,
5-hexafluoro-2-pentanone] methane _{(H 2) DODECA-F [} PDA]

[0049]

[Chemical formula 22] Bis [4- (methylene) imino-1,1,1,5,5,
5-hexafluoro-2-pentanone] methanol (H ₂ ) DODECA-F [PDA]

[0050]

[Chemical formula 23]

[0051]

As described above, the vapor phase etching method of the present invention for etching a metal substrate used in the electronic device industry or the like or a metal thin film deposited on the substrate is
It has many advantages over the known wet etching methods. Since the etching method of the present invention is carried out in the vapor phase, it is possible to carry out the etching operation directly without the need to pass the substrate through the clean room during the movement between the devices, and thus the exposure method is exposed to other contaminants. In addition, according to the etching agent of the present invention, there is no residue on the substrate after the etching that interferes with the subsequent steps. is there.

Continued Front Page (72) Inventor John. Christopher. Ivankovitz USA. 18102. Pennsylvania. Allentown. South. Thirteen. Street. 238 (72) Inventor David. Arthur. Bowling United States. 18049. Pennsylvania. Emmaus. Mountain. View. Circle. 2690 (72) Inventor John. Anthony. Thomas. Norman United States. 92024. California. Encinia. Via. Virena. 242 (56) Reference JP-A-62-83482 (JP, A)

Claims (8)

[Claims] 1. A volatile metal-ligand complex is formed with an effective amount of a ligand represented by the following chemical formula 1 in which a metal surface is dispersed in an atmosphere capable of oxidizing the metal surface. A vapor phase etching method for a metal surface, which comprises contacting under various conditions to volatilize the metal-ligand complex to etch the metal surface. [Chemical 1] However, in the formula, R ₁ and R ₃ are each independently linear or branched non-fluorinated, partially fluorinated, or fully fluorinated alkyl having 1 to 8 carbon atoms. group, an alkenyl group has been selected from an allyl group, R ₂ is a hydrogen atom, a fluorine atom, or a linear or branched non-fluorinated, partially fluorinated, 1 was completely fluorinated An alkyl group or an alkenyl group having 8 carbon atoms, Y is an oxygen atom, an alkyl group having 1 to 10 carbon atoms in which R ₄ is non-fluorinated, partially fluorinated, or fully fluorinated; Selected from N—R ₄ selected from an aralkyl group or a hydroxyalkyl group, or represented by the following chemical formula 2
Is. [Chemical 2] However, in the formula, R ₅ , R _6, and R ₇ are each independently a hydrogen atom, a fluorine atom, a fluorinated atom, or a linear or branched non-fluorinated, partially fluorinated, or completely fluorinated. The 1
Selected from an alkyl group having 8 to 8 carbon atoms or an alkenyl group, R ₈ is a straight chain or branched chain non-fluorinated, partially fluorinated, or fully fluorinated 1 An alkylene group having 8 to 8 carbon atoms, an alkenylene group, a phenylene group, an alkylphenylene group or a hydroxyalkylene group. 2. The oxidizable atmosphere is oxygen gas, steam,
Gaseous mixture of 19.5 to 23.5 mol% oxygen and less than 0.5 mol% hydrocarbons, balance nitrogen, HC
The vapor phase etching method for a metal surface according to claim 1, wherein the vapor phase etching is 1, HF, Cl ₂ or Br ₂ . 3. R ₁ and R ₃ are each independently a linear or branched perfluorinated alkyl group having 1 to 4 carbon atoms, R ₂ is a hydrogen atom, or The vapor phase etching method for a metal surface according to claim 1, which is a fluorine atom. 4. The ligand is 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, 1,1,1-
Trifluoro-2,4-pentanedione, 2,2,6,
6-tetramethyl-3,5-heptanedione, and 1,
1,1,5,5,6,6,7,7,7-decafluoro-
A compound selected from 2,4-heptadione.
A vapor phase etching method for a metal surface as described. 5. A ligand is 4- (2,2,2-trifluoroethyl) imino -1,1,1,5,5,5- hexafluoro-2-pentanone, 5- (2,2 , 2-trifluoroethyl) imino-1,1,1,2,2,6,6,
6-octafluoro-3-hexanone, 6- (2,2,
2-trifluoroethyl) imino-1,1,1,2,
2,3,3,7,7,7-decafluoro-4-heptanone, 4- (phenyl) imino-1,1,1,5,5,
A compound selected from 5-hexafluoro-2-pentanone and 1,2-di [4-imino-1,1,1,5,5,5-hexafluoro-2-pentanone] ethane. A vapor phase etching method for a metal surface as described. 6. The ligand is 1,2-di [5-imino-
1,1,1,2,2,6,6,6-octafluoro-3
-Hexanone] ethane, 1,2-di [6-imino-1,
1,1,2,2,3,3,7,7,7-decafluoro-
4-heptanone] ethane, and bis [(4-methylene)]
Imino-1,1,1,5,5,5-hexafluoro-2
-Pentanone] methane.
A vapor phase etching method for a metal surface as described. 7. The metal to be etched is gold, tin, copper,
The vapor phase etching method for a metal surface according to claim 1, which is selected from iron and indium. 8. The metal surface of claim 1, wherein the ligand is 1,1,1,5,5,5-hexafluoro-2,2-pentanedione and the metal to be etched is copper. Vapor phase etching method.