WO1991019325A1 - Optical emission spectroscopy to determine etch completion of indium tin oxide - Google Patents
Optical emission spectroscopy to determine etch completion of indium tin oxide Download PDFInfo
- Publication number
- WO1991019325A1 WO1991019325A1 PCT/US1991/003664 US9103664W WO9119325A1 WO 1991019325 A1 WO1991019325 A1 WO 1991019325A1 US 9103664 W US9103664 W US 9103664W WO 9119325 A1 WO9119325 A1 WO 9119325A1
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- WIPO (PCT)
- Prior art keywords
- plasma
- ito
- tin oxide
- indium tin
- etching
- Prior art date
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- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 title claims description 13
- 238000001636 atomic emission spectroscopy Methods 0.000 title description 3
- 230000003287 optical effect Effects 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 20
- 238000005530 etching Methods 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 239000007795 chemical reaction product Substances 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 229920002120 photoresistant polymer Polymers 0.000 description 10
- 239000007789 gas Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000000376 reactant Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 5
- 229920005591 polysilicon Polymers 0.000 description 5
- 241000894007 species Species 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- -1 methyl radicals Chemical class 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 229910009201 Sn(CH3)4 Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 229940071870 hydroiodic acid Drugs 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- WCYWZMWISLQXQU-UHFFFAOYSA-N methyl Chemical compound [CH3] WCYWZMWISLQXQU-UHFFFAOYSA-N 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000001552 radio frequency sputter deposition Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/53—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone involving the removal of at least part of the materials of the treated article, e.g. etching, drying of hardened concrete
- C04B41/5338—Etching
- C04B41/5346—Dry etching
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/91—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics involving the removal of part of the materials of the treated articles, e.g. etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
Definitions
- the present invention relates to the plasma etching of indium tin oxide.
- Solid state CCD image sensors often employ a double pclysilicon gate structure to form the sensor electrodes.
- Such a structure has the first polysilicon electrode (poly-1) separated from the second polysilicon electrode (poly-2) by a thin insulating layer of silicon dioxide.
- Poly—1 is slightly overlapped by poly-2.
- the systematic variation of the potential applied to these electrodes referred to as clocking, permits the device to function.
- clocking permits the device to function.
- light passes through the polysilicon electrodes and creates electron hole pairs in the underlying silicon. ' These electrons are accumulated prior to clocking the polysilicon electrodes to remove the accumulated charge.
- the polysilicon electrodes, through which light must pass, are not entirely transparent. This lack of transparency results in the reduction of sensitivity "and spectral response of the image sensor.
- indium tin oxide would be an effective electrode for such a device.
- the use of an indium tin oxide electrode enhances the blue response —£.— and overall sensitivity of a frame transfer image sensor.
- the effective ASA of the device could be increased by as much as a factor of two.
- ITO has not been used on such devices is " because it is difficult to pattern such material.
- the only practical method for etching indium tin oxide has been by immersion in a hot hydroiodic acid solution. Such an acid etches the material isotropically and is not selective to photoresist.
- a plasma containing methyl radicals (CH *) can effectively etch indium tin oxide anisotropically and with high selectivity to photoresist and silicon dioxide.
- the emission lines from the CH ⁇ » containing plasma have been found to provide strong intensity changes at completion of the etching of an ITO layer, thereby indicating when to terminate the process.
- a method of etching indium tin oxide comprising the steps of: forming a plasma containing CH--; etching the ITO by volatilizing the ITO by a reaction with the plasma of CH--; and monitoring the intensity characteristic of at least one optical emission line of the plasma to determine etch completion and then terminate the etching process.
- FIG. la is a schematic, in partial cross—section, of a conventional plasma etcher which uses radio frequency energy to ignite and sustain the plasma.
- FIG. 2a is a plot of emission wavelength versus emission intensity for a CH, , H ⁇ plasma
- FIG. 2b is a typical plot of intensity versus time for an emission line associated with the etch reactant CEr * - ;
- FIG. 2c is a typical plot of intensity versus time for an emission line associated with an etch product; and FIG. 3 shows various steps in patterning an
- a plasma is a state of matter in which the gases in a vessel with a total pressure less than atmospheric pressure are partially ionized .by an electric field.
- an electric field can be from a radio frequency generator, microwave frequency generator or DC voltage field.
- the emission of light from the excited gases in a plasma is a well known phenomenon.
- the wavelength of the light emitted is specific to the excited species that compose the plasma.
- Such excited species will include the reactants and products of any reactions occurring in the plasma.
- the intensity of the characteristic light emissions of the reactants will be low during etching and then increase as ' the layer of material being etched is cleared away.
- the intensity will be high during the etch and will drop as the layer of material being etched is cleared away.
- a plasma ignited by the action of a suitable electric field on a mixture of CH, gas and H ⁇ gas, will contain methyl radicals (CH.,*) as well as other species generated from the cracking of the molecules of CH, and H ⁇ .
- CH, and B. * mixtures are not the only means of producing methyl radicals (CH *) and that mixtures of ethane and hydrogen, propane and hydrogen, or other organic compounds will result in methyl radical creation in plasma and will, in so doing, etch ITO.
- a wafer 18 is placed on a lower electrode 15 which is connected to an RF radiation source 28.
- Vacuum is achieved in the chamber by the use of an oil diffusion pump and rotary vacuum pump, not shown.
- the lower electrode 15 is heated by resistive heaters 16 located on the back of the electrode.
- the H objection and CH, gases are admitted into the chamber through a diffuser 26.
- the flows of the gases are regulated by mass flow controllers 22 and 24.
- Process pressure in the vessel is controlled by a vacuum throttle valve 21.
- a plasma of CH, and H 2 is ignited in a space 30a between the lower electrode 15, on which the wafer 18 sits, and an upper electrode 12.
- the resultant CH-- generated in region 30 will react with the ITO on the wafer 18 volatilizing the ITO off the ' wafer to be pumped away by the vacuum pump.
- the emission of light from the CH, and H ⁇ plasma is monitored by an optical emission spectrometer (40) which detects light from the plasma through a window (41) in the side of the etcher.
- the spectrometer 30 monitors the intensity of specific lines associated with the reactants and products of the etch and displays the intensity versus time plot on a recorder 42, CRT or pen recorder.
- a control unit 44 which is coupled to the spectrometer 40 and shuts-off the RF radiation source 28.
- FIG. 2a we see a plot of intensity in counts versus the intensity output of spectrometer 40 and displayed by recorder 42. Each count refers to a specific amount of energy received by the spectrometer.
- the light emission lines labelled (B) at about 345 nm and 375 nm are both caused by reactant CH-- in the plasma. These lines are present whether or not CH 3 * is etching ITO.
- the light emission line at about 353 nm is caused by a product produced by etching ITO with CH--.
- FIG. 2b we see a plot of one of the emission lines labelled (B) in FIG. 2a.
- FIG. 2c is a plot of an etch product produced when ITO is etched by CH-* •
- the etching process begins at time 0.
- the ITO is beginning to clear (become exhausted).
- the etching process is completed. It is desirable to run the process " a short duration after the process levels off to insure that all the ITO has been etched.
- the RF radiation source 28 is then shut-off at the termination point (TP) .
- the process can be monitored by viewing either a reaction product or a reactant emission line.
- FIGS. 3a-c show the process of pattern transfer for the definition of ITO where the etched ITO is to be used as a poly-1 electrode.
- microlithographic photoresist mask 34 has been deposited and patterned in a conventional manner on the surface of an ITO layer 32 which has been deposited on an SiO- layer 30 on a silicon substrate 36.
- ITO is most usually deposited by RF sputter deposition.
- the ITO layer 32 has been etched anisotropically by the plasma of CH-- thereby transferring the photoresist pattern into the ITO and stopping on the SiO- layer 30. Measurements have shown that the plasma of CH.,- that etches the ITO has a high selectivity to both the photoresist and the underlying SiO- layer.
- the photoresist 34 has been stripped off of the ITO 32 and the device may proceed to further processing.
- the photoresist is most usually removed by 0- plasma stripping.
- the mechanism of etching of ITO is believed to be caused by methyl radicals reacting with indium and tin to create volatile organometallic compounds as shown by the following reaction: plasma CH 4 +H 2 > CH 3 -+In+Sn+0- En(CH 3 ) 3 t+Sn(CH 3 ) 4 t+COt
- An etcher similar to the one represented by FIG. 1 was used to etch ITO.
- the radio frequency used to ignite and sustain the plasma was 13.56 megahertz at 85 watts forward power.
- the wafer was heated to a temperature of 70°C.
- the chamber was evacuated to a base pressure of 1 x 10- prior to the admission of the CH ⁇ and H 2 gases.
- the flow rate for the CH was 25 seem and the flow rate the the H- was 150 seem.
- a process pressure of 150 Mtorr was maintained during the etch.
- the sputter deposited ITO etched at a rate of 275 angstroms per minute and showed very high selectivity to the photoresist and the underlying silicon dioxide.
Abstract
ITO is etched by a plasma containing CH3. gas. The intensity characteristic of at least one optical emission line is monitored to determine etch completion.
Description
OPTICAL EMISSION SPECTROSCOPY TO DETERMINE ETCH
COMPLETION OF INDIUM TIN OXIDE.
Reference to Co-pending Patent Applications
Reference is made to commonly assigned U.S. Patent Application Serial No. 533.232, filed June 4, 1990 to Paul Roselle, and to commonly assigned U.S. Patent Application Serial No. 520,486, filed May 7, 1990 to Paul Roselle, Gustavo Paz-Pujalt and Ronald Wexler . Technical Field
The present invention relates to the plasma etching of indium tin oxide. Background Art
Solid state CCD image sensors often employ a double pclysilicon gate structure to form the sensor electrodes. Such a structure has the first polysilicon electrode (poly-1) separated from the second polysilicon electrode (poly-2) by a thin insulating layer of silicon dioxide. Poly—1 is slightly overlapped by poly-2. The systematic variation of the potential applied to these electrodes, referred to as clocking, permits the device to function. In the case of frame transfer CCD image sensors, light passes through the polysilicon electrodes and creates electron hole pairs in the underlying silicon.' These electrons are accumulated prior to clocking the polysilicon electrodes to remove the accumulated charge. The polysilicon electrodes, through which light must pass, are not entirely transparent. This lack of transparency results in the reduction of sensitivity "and spectral response of the image sensor.
Due to its transparency, it has been recognized that indium tin oxide would be an effective electrode for such a device. The use of an indium tin oxide electrode enhances the blue response
—£.— and overall sensitivity of a frame transfer image sensor. In fact, it has been recognized that if indium tin oxide were to be used in such a device the effective ASA of the device could be increased by as much as a factor of two. One reason that ITO has not been used on such devices is"because it is difficult to pattern such material. Heretofore, the only practical method for etching indium tin oxide has been by immersion in a hot hydroiodic acid solution. Such an acid etches the material isotropically and is not selective to photoresist. These two reasons alone show the difficulties involved in using ITO for microelectronic applications where small features are defined by photoresist lithography. It has also been recognized that ITO can be used as an antistatic coating on materials such as webs used in the manufacture of photosensitive materials. There again, it is difficult to use such a material because it is not practical to pattern it. Disclosure of the Invention
It is the object of this invention to provide a new method for the etching of indium tin oxide employing optical emission spectroscopy to determine etch completion and provide process termination.
A plasma containing methyl radicals (CH *) can effectively etch indium tin oxide anisotropically and with high selectivity to photoresist and silicon dioxide. The emission lines from the CH~» containing plasma have been found to provide strong intensity changes at completion of the etching of an ITO layer, thereby indicating when to terminate the process.
The above object is achieved in a method of etching indium tin oxide, comprising the steps of: forming a plasma containing CH--;
etching the ITO by volatilizing the ITO by a reaction with the plasma of CH--; and monitoring the intensity characteristic of at least one optical emission line of the plasma to determine etch completion and then terminate the etching process. Brief Description of the Drawings
FIG. la is a schematic, in partial cross—section, of a conventional plasma etcher which uses radio frequency energy to ignite and sustain the plasma.
FIG. 2a is a plot of emission wavelength versus emission intensity for a CH, , H~ plasma; FIG. 2b is a typical plot of intensity versus time for an emission line associated with the etch reactant CEr* - ;
FIG. 2c is a typical plot of intensity versus time for an emission line associated with an etch product; and FIG. 3 shows various steps in patterning an
ITO layer formed on an Si02 insulating layer provided on a silicon substrate. Mode of Carrying Out the Invention
With reference to FIGS. 1, 2 and 3a-3c, a process for the plasma etching of indium tin oxide is described.
A plasma is a state of matter in which the gases in a vessel with a total pressure less than atmospheric pressure are partially ionized .by an electric field. As is well understood, such an electric field can be from a radio frequency generator, microwave frequency generator or DC voltage field.
The emission of light from the excited gases in a plasma is a well known phenomenon. The wavelength of the light emitted is specific to the excited species that compose the plasma. Such
excited species will include the reactants and products of any reactions occurring in the plasma. For the case where a plasma is used to etch a layer of some material, the intensity of the characteristic light emissions of the reactants will be low during etching and then increase as' the layer of material being etched is cleared away. Conversely, for the emission from the product of the etch, the intensity will be high during the etch and will drop as the layer of material being etched is cleared away. A plasma, ignited by the action of a suitable electric field on a mixture of CH, gas and H~ gas, will contain methyl radicals (CH.,*) as well as other species generated from the cracking of the molecules of CH, and H~. As in any plasma, the concentrations of the various species in the plasma depend upon the power and frequency of the electric field applied, the pressure of the plasma, and the concentrations of the gases used. It should be understood that CH, and B.* mixtures are not the only means of producing methyl radicals (CH *) and that mixtures of ethane and hydrogen, propane and hydrogen, or other organic compounds will result in methyl radical creation in plasma and will, in so doing, etch ITO.
For an etcher as represented in FIG. 1, a wafer 18 is placed on a lower electrode 15 which is connected to an RF radiation source 28. Vacuum is achieved in the chamber by the use of an oil diffusion pump and rotary vacuum pump, not shown.
The lower electrode 15 is heated by resistive heaters 16 located on the back of the electrode. The H„ and CH, gases are admitted into the chamber through a diffuser 26. The flows of the gases are regulated by mass flow controllers 22 and 24. Process pressure in the vessel is controlled by a vacuum throttle valve 21. When the desired flow rates, pressure and
temperature are achieved, a plasma of CH, and H2 is ignited in a space 30a between the lower electrode 15, on which the wafer 18 sits, and an upper electrode 12. The resultant CH-- generated in region 30 will react with the ITO on the wafer 18 volatilizing the ITO off the'wafer to be pumped away by the vacuum pump. The emission of light from the CH, and H~ plasma is monitored by an optical emission spectrometer (40) which detects light from the plasma through a window (41) in the side of the etcher. The spectrometer 30 monitors the intensity of specific lines associated with the reactants and products of the etch and displays the intensity versus time plot on a recorder 42, CRT or pen recorder. When the intensity of the monitored reactant emission lines goes up and levels off and, simultaneously, the intensity of the monitored product emission lines goes down and levels off, the ITO layer has been fully etched away. The process is automatically terminated by a control unit 44 which is coupled to the spectrometer 40 and shuts-off the RF radiation source 28. Alternatively, an operator can view the* output of the recorder 42 and shut—off the RF radiation source 28. Turning now to FIG. 2a, we see a plot of intensity in counts versus the intensity output of spectrometer 40 and displayed by recorder 42. Each count refers to a specific amount of energy received by the spectrometer. The light emission lines labelled (B) at about 345 nm and 375 nm are both caused by reactant CH-- in the plasma. These lines are present whether or not CH3* is etching ITO. The light emission line at about 353 nm is caused by a product produced by etching ITO with CH--. In FIG. 2b we see a plot of one of the emission lines labelled (B) in FIG. 2a. Also, FIG. 2c .is a plot of an etch product produced when ITO is etched by CH-* •
With reference to both FIGS. 2a and 2b, the etching process begins at time 0. At an inflection point (ep) in both plots, the ITO is beginning to clear (become exhausted). When both plots level off (cp) the etching process is completed. It is desirable to run the process" a short duration after the process levels off to insure that all the ITO has been etched. The RF radiation source 28 is then shut-off at the termination point (TP) . The process can be monitored by viewing either a reaction product or a reactant emission line. However, those skilled in the art will recognize that it is desirable to simultaneously monitor both a reaction product line and the CH-- emission line. The pressure of the plasma of CH, and H~ must be maintained below the polymerization point of the plasma. Likewise, the ratio of CH, to H- should be less than 20% to prevent excessive polymerization of the species in the plasma. Such excessive polymerization produced by too high of a pressure and/or too high of a concentration of CH, in H- will prevent ITO from etching uniformly if at all.
FIGS. 3a-c show the process of pattern transfer for the definition of ITO where the etched ITO is to be used as a poly-1 electrode. In FIG. 3a it is seen that microlithographic photoresist mask 34 has been deposited and patterned in a conventional manner on the surface of an ITO layer 32 which has been deposited on an SiO- layer 30 on a silicon substrate 36. ITO is most usually deposited by RF sputter deposition.
In FIG. 3b the ITO layer 32 has been etched anisotropically by the plasma of CH-- thereby transferring the photoresist pattern into the ITO and stopping on the SiO- layer 30. Measurements have shown that the plasma of CH.,- that etches the ITO
has a high selectivity to both the photoresist and the underlying SiO- layer.
In FIG. 3c the photoresist 34 has been stripped off of the ITO 32 and the device may proceed to further processing. The photoresist is most usually removed by 0- plasma stripping. Example
Without limiting the generality of this invention,, the mechanism of etching of ITO is believed to be caused by methyl radicals reacting with indium and tin to create volatile organometallic compounds as shown by the following reaction: plasma CH4+H2 > CH3-+In+Sn+0- En(CH3)3t+Sn(CH3)4t+COt
ITO
Other starting gases can be used provided they form a plasma having CH--.
An etcher similar to the one represented by FIG. 1 was used to etch ITO. The radio frequency used to ignite and sustain the plasma was 13.56 megahertz at 85 watts forward power. The wafer was heated to a temperature of 70°C. The chamber was evacuated to a base pressure of 1 x 10- prior to the admission of the CH^ and H2 gases. The flow rate for the CH, was 25 seem and the flow rate the the H- was 150 seem. A process pressure of 150 Mtorr was maintained during the etch. The sputter deposited ITO etched at a rate of 275 angstroms per minute and showed very high selectivity to the photoresist and the underlying silicon dioxide. The .emission lines attributed to etch reactants and one emission line attributed to etch product were monitored and showed strong endpoint responses . Cross—sectional scanning electron micrographs of the etched ITO showed the etch to be highly anisotropic with no evidence of undercutting the photoresist.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
Claims
1. In a method of etching indium tin oxide, comprising the steps of: forming a plasma containing CH--; etching the ITO by volatilizing the ITO by a reaction with the plasma of CH--; and monitoring the intensity characteristic of at least one optical emission line of the plasma to determine etch completion and then terminate the etching process.
2. In a method of etching indium tin oxide, comprising the steps of: forming a plasma containing CH--; etching the ITO by volatilizing the ITO by a reaction with the plasma of CH--; and monitoring the intensity characteristic of the CH-*-* optical emission line and a reaction product emission line of the plasma to determine etch completion and then terminate the etching process .
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US53321790A | 1990-06-04 | 1990-06-04 | |
US533,217 | 1990-06-04 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1991019325A1 true WO1991019325A1 (en) | 1991-12-12 |
Family
ID=24125004
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1991/003664 WO1991019325A1 (en) | 1990-06-04 | 1991-06-03 | Optical emission spectroscopy to determine etch completion of indium tin oxide |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0485590A1 (en) |
JP (1) | JPH05500887A (en) |
WO (1) | WO1991019325A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5607602A (en) * | 1995-06-07 | 1997-03-04 | Applied Komatsu Technology, Inc. | High-rate dry-etch of indium and tin oxides by hydrogen and halogen radicals such as derived from HCl gas |
US5843277A (en) * | 1995-12-22 | 1998-12-01 | Applied Komatsu Technology, Inc. | Dry-etch of indium and tin oxides with C2H5I gas |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE8303449L (en) * | 1983-06-16 | 1984-12-17 | Alfa Laval Thermal | PACKAGING ARRANGEMENTS FOR PLATE HEAT EXCHANGERS |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4528438A (en) * | 1976-09-16 | 1985-07-09 | Northern Telecom Limited | End point control in plasma etching |
EP0377365A1 (en) * | 1988-12-19 | 1990-07-11 | ETAT FRANCAIS représenté par le Ministre des Postes, Télécommunications et de l'Espace | Process for etching a metal oxide layer with simultaneous deposition of a polymer film, use of this process in the production of a transistor |
-
1991
- 1991-06-03 JP JP3511208A patent/JPH05500887A/en active Pending
- 1991-06-03 WO PCT/US1991/003664 patent/WO1991019325A1/en not_active Application Discontinuation
- 1991-06-03 EP EP91911969A patent/EP0485590A1/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4528438A (en) * | 1976-09-16 | 1985-07-09 | Northern Telecom Limited | End point control in plasma etching |
EP0377365A1 (en) * | 1988-12-19 | 1990-07-11 | ETAT FRANCAIS représenté par le Ministre des Postes, Télécommunications et de l'Espace | Process for etching a metal oxide layer with simultaneous deposition of a polymer film, use of this process in the production of a transistor |
Non-Patent Citations (3)
Title |
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5émé Colloque International sur les Plasmas et la Pulverisation Cathodique, Antibes, Fr, 10-14 June 1985, Société Francaise du Vide Publishers, J.F. Boulineau et al.: "Etude et réalisation de couches d'oxydes d'indium et d'etain obtenues par ion plating", pages 67-71 * |
Japanese Journal of Applied Physics, vol. 27, no. 9, September 1988, T. Minami et al.: "Reactive ion etching of transparent conducting tin oxide films using electron cyclotron resonance hydrogen plasma", pages L1753-L1756 * |
Solid State Technology, vol. 24, no. 4, April 1981, (Washington, US) P.J. Marcoux et al.: "Methods of end point detection for plasma etching", pages 115-122 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5607602A (en) * | 1995-06-07 | 1997-03-04 | Applied Komatsu Technology, Inc. | High-rate dry-etch of indium and tin oxides by hydrogen and halogen radicals such as derived from HCl gas |
US5843277A (en) * | 1995-12-22 | 1998-12-01 | Applied Komatsu Technology, Inc. | Dry-etch of indium and tin oxides with C2H5I gas |
Also Published As
Publication number | Publication date |
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JPH05500887A (en) | 1993-02-18 |
EP0485590A1 (en) | 1992-05-20 |
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