CA1281439C - Plasma reactor and method for removing photoresist - Google Patents
Plasma reactor and method for removing photoresistInfo
- Publication number
- CA1281439C CA1281439C CA000500981A CA500981A CA1281439C CA 1281439 C CA1281439 C CA 1281439C CA 000500981 A CA000500981 A CA 000500981A CA 500981 A CA500981 A CA 500981A CA 1281439 C CA1281439 C CA 1281439C
- Authority
- CA
- Canada
- Prior art keywords
- plasma
- working
- article
- chamber
- barrel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
- H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled to the plasma
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/26—Processing photosensitive materials; Apparatus therefor
- G03F7/42—Stripping or agents therefor
- G03F7/427—Stripping or agents therefor using plasma means only
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32357—Generation remote from the workpiece, e.g. down-stream
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/32623—Mechanical discharge control means
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Drying Of Semiconductors (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
Abstract
Abstract PLASMA REACTOR AND METHOD FOR REMOVING PHOTORESIST
A plasma reactor comprises a working chamber that has at least one entry port. The working chamber is adapted to receive at least one article. The entry port is adapted to receive a working gas into the working chamber. An elec-trical energy generator is provided. The plasma reactor includes at least one pair of electrodes which are posi-tioned adjacent the working chamber entry port. The elec-trodes, which are connected to the generator, create an electric field adjacent the entry port that converts the working gas into a working plasma for interacting with a material of the article. The article to be processed is placed in a part of the working chamber which is free from electric fields. An electric field-free region downstream of the plasma generating region is provided in which the article is positioned.
A plasma reactor comprises a working chamber that has at least one entry port. The working chamber is adapted to receive at least one article. The entry port is adapted to receive a working gas into the working chamber. An elec-trical energy generator is provided. The plasma reactor includes at least one pair of electrodes which are posi-tioned adjacent the working chamber entry port. The elec-trodes, which are connected to the generator, create an electric field adjacent the entry port that converts the working gas into a working plasma for interacting with a material of the article. The article to be processed is placed in a part of the working chamber which is free from electric fields. An electric field-free region downstream of the plasma generating region is provided in which the article is positioned.
Description
Description PLASMA REACTOR AND METHO~ ~OR REMOVING PHOTORESIST
Technical Field This invention relates to plasma reactors, and more particularly, to plasma barrel reactors for removing the photoresist from semiconductor wafers or etching thin films such as aluminum, silicon dioxide or polysilicon on silicon wafers patterned with photoresist for etching.
Background Art The use of gas plasma for processing semiconductor wafers is common in the art. For example, various techniques are described in J. Hollahan and A. Bell, Techniques and Applications of Plasma Chemistry, Ch. 9 (1974).
Semiconductor components are fabricated on a semicon-ductive substrate or wafer. The material of the wafer is generally silicon. In manufacturing semiconductor devicesl a photosensitive polymer, generally referred to as a photo-resist, is used. After selective exposure to optical radi-ation and subsequent chemical development, the photoresist hardens where it has not been removed and protects the un-derlying wafer from other chemicals. One method of re-moving photoresist from wafers after it has served its protective function is by using a gas plasma.
In general, the gas plasma used ;n removing photore-sist is oxygen. More particularly, diatomic oxygen is first exposed to an electric field which transforms some of the diatomic oxygen into an oxygen plasma that contains some monoatomic oxygen, generally referred to as atomic oxygen. Atomic oxygen is capable of reacting with the photoresist by breaking its polymer chains such that the photoresist is removed from the semiconductor wafer by the combined action of the atomic oxygen and the molecular oxy-3~'3 gen. The resultant by-products are gases such as H2O, CO
and CO2.
Prior art oxygen plasma reactors for removing photore-sist, an example of which is shown in Figure 2A, consist of a cylindrical quartz reactor. A plurality of semiconductor wafers, each of which has a layer of photoresist on its surfaces, are positioned within the reactor. Metal alec-trodes are positioned around the reactor, one of which is connected to a radio-frequency (RF) generator operating at 13.56 MHz or some harmonic of that frequency and the other is connected to the ground. The quartz reactor also includes a gas input manifold and an exhaust manifold.
Other prior art plasma reactors, not shown, include single-chamber reactor that has an electrode within the chamber, as best exemplified in U.S. Patent No. 4,230,515.
In addition, prior art reactors include double-chamber re-actor in which the plasma is generated in one chamber and the work such as photoresist removal is performed in a second chamber. The plasma may be transported between the two chambers either through a narrow channel or through narrow tubes. The primary disadvantage of the double-chamber reactor is the likelihood of plasma degeneration before it could perform the removal of the photoresist, that is, atomic oxygen tends to recombine to diatomic oxygen on the walls of t~le channel or tubes~
In prior single chamber reactors with external elec-trodes, the electrodes are wrapped around the entire sides of the cylindrical reactor so that the electric field fills the whole volume of the reactor. ~owever, due to the elec-trical skin effect of the RF discharge, the electric cur-rent produced tends to "hug'l the reactor wall. This effect is analogous to the phenomena of high frequency current flowing near the surface or sXin of a metal conductor.
Thus, most of the atomic oxyqen is produced near the walls of the reactor and is pumped out of the reactor without getting near the wafers. The only atomic oxygen that is ~81~
involved with the removal process is that which diffused into the center of the reactor where the wafers are placed and then diffusing between the wafers.
Disclosure of the Invention In view of such deficiencies in the prior art, it is a major object of the present invention to provide a plasma reactor that is capable of maximizing the use of the prod-ucts of the plasma in performing the desired chemistry. In the instance of photoresist removal, maximizing the reac-tion of the atomic oxygen with the photoresist.
In order to accomplish the above and still further objects, the present invention provides a plasma reactor that has a working chamber with at least one entry port, the entry port is adapted to receive a working gas into the working chamber. In addition, the working chamber is adapted to receive at least one article. An electrical energy generator is provided. At least one pair of elec-trodes are positioned adjacent the working chamber entry port. The electrodes, which are connected to the genera-tor, create an electric field adjacent the entry port thatconverts the working gas into a working plasma for interacting with a material of the article. The position of the electric field adjacent the entry port leaves a substantially electric f'~eld-free region in the barrel chamber adjacent the article.
In addition, the plasma reactor of the present inven-tion includes a plasma Elow constraint member which is po-sitioned within the working chamber. The constraint member permits the flow of the gas only through itself so as to enhance the interaction oE the gas with the material of the article. ~ore particularly, the constraint member includes at least one opening that is adapted to receive the article and to permit the passage of the gas.
It should be noted that as long as the material being processed is placed in the center of the electric field used to create the plasma, the species of interest will be generated and will flow around the sides of the material being processed without reacting with it to an appreciable extent. By generating the plasma upstream of the material being process, it is easy to force the species of interest to flow adjacent the material being processed. This must be done without passing the flow through narrow constric-tions which will exterminate the species of interest.
In the preferred embodiment of the present invention, the material of the article that is removed by the working plasma is photoresist~ In addition, the article is a semi-conductor wafer. Last, the working plasma consists of oxygen.
In its method aspect, the invention relates to a method of interacting a working plasma with an article which is positioned within a working chamber comprising the steps of: positioning the article in a working position within the chamber; introducing a working gas into the chamber remote from the working position; establishing an electric field for converting the working gas into the working plasma for inter-acting with a material of the article; and confining the electric field to a region immediately adjacent where the work-ing gas is introduced into the working chamber, whereby the working plasma interacts with the material of the article in the working position that is substantially electric field-free.
Other objects3 features, and advantages of the present invention will appear from the following detailed description of the best mode of a preferred embodiment, taken together with the accompanying drawings.
Pg/ ~ - 4 -,,~
Brief Description of the Drawin_ Figure 1 is a perspective view of the plasma barrel reactor of the present invention;
Figure 2 is a partial, cross-sectional~ and diagram-matical view of a prior art plasma reactor;
Figure 3 is a partial, cross-sectional, and diagram-matical view of the plasma barrel reactor of Figure l; and Figure 4 is a partial, cross-sectional, and diagram-matical view of the plasma flow constraint member of the plasma LO barrel reactor of Figures 1 and 3.
Best Mode For Carrying Out the Invention Referring to Figure l, there is shown a plasma barrel reactor, generally designated 12. Reactor 12 includes a generally barrel-like, cylindrical working chamber 14. Barrel chamber 14 may have a diameter from six to 12 inches; the diameter of chamber 14 is 12 inches in the pre-Pgl - 4A -~a~4~39 ferred embodiment. The axial length of chamber 14 is ap-proximately 21 inches. Chamber 1~ has a plura]ity of entry ports 16 for receiving a working gas and a plurality of ex-haust ports 18 for venting various gases and by-products of chamber 14. There are four entry ports 16 and five exhaust ports 18 in the preferred embodiment. Moreover, entry ports 16, as best illustrated in Figure 3, are positioned diametrically opposite exhaust ports 18. Chamber 14, in the preferred embodiment~ is made from a conventional inert material such as quartz9 Chamber 14 is adapted to receive a plurality of arti-cles 20. Articles 20, as shown, are semiconductor wafers each of which has a layer of photoresist material on it when the wafers are placed in chamber 14.
Reactor 12 further includes an entry gas manifold 22 that is positioned adjacent chamber 14. Entry gas manifold 22 is a tube, also made of ~uartz that has a plurality of ports 24 each of which is in communication with one of the barrel chamber entry ports 16. Entry gas manifold 22 in the preferred embodiment has four ports 24. Entry gas manifold 22 is capable of transporting the working gas to barrel chamber 14.
A radio-frequency (RF) electrical energy generator, not shown, is provided. In the preferred embodiment, the frequency o the RF ener~y is 13.56 MHz.
In addition, reactor 12 includes a pair of entry port electrodes 28e and 30e which are positioned adjacent barrel chamber entry ports 16, as best shown in Figure 3. Each of the electrodes 28e and 30e, which are manufactured from a conductive metal such as copper, contains a slight curva-ture in its design such that it follows the curvature of chamber 14. Electrodes 28e and 30e are capable of creating an electric field in barrel chamber 14 adjacent entry ports 16. This entry port electric field Ee then converts the working ~as to a working plasma. Moreover, the position of entry port electric field Ee delineates a substantially .
electric field-free region FR in chamber 14 ad~acent arti cles 20.
A pair of manifold electrodes 28rn and 3nm, which are positioned adjacent entry gas manifold 22, is also pro-vided. Each of the manifold electrodes 28m and 30m is agenerally vertically-extending plate that is positioned at either side of manifold 22, as best shown in Figure 3.
Electrodes 28m and 30m are also manufactured from a conduc-tive metal such as copper. Manifold electrodes 28m and 30m are capable of creating an electric field in manifold 22.
~he manifold electric field Em converts a portion of the working gas to the working plasma before the working gas enters chamber 14. The combined effort of the manifold electric field Em and the entry port electric field Ee efficaciously convert the working gas to the desired work-ing plasma.
Although electrodes 28e and 28m and electrodes 30e and 30m are claimed and described as separate and discrete electrodes, electrodes 28e and 28m could be manufactured as a single electrode and electrodes 30e and 30m as a single electrode. In addition, manifold electrodes 28m and 30m need not be required in all instances. Although the mani-fold electric field Em generated by electrodes 28m and 30m does contribute to the efficacious conversion of the work-ing gas to the working plasma, its elimination does notdetract the overall conversion of the working gas to the working plasma made by the entry port electric field Ee alone.
Reactor 12 also includes a plasma flow constraint mem-ber 40 that is positioned within barrel chamber 14. Con-straint member 40 is a planar, board-like platform which has a plurality of openings 42. Openings 42 perform two functions the first of which is to receive wafers 20.
Wafers 20 are first placed into a conventional wafer recep-tacle 44, which is generally referred to as a wafer boat.Each ~afer boat 44 is capable of receiving a plurality of ~ ~314~
wafers, as best shown in Figure 4~ The wafers in boat 44 are spaced apart sufficiently so as to permit the atomic oxygen to flow among them and react with the photoresist which are on the wafers. Boat 44, which is manufactured from an inert material such as quartz, is then received in opening 42.
The next, and more important, function of platform 40 is to restrict the flow of the working gas, and direct it only to wafers 20. The working gas ceases to be a plasma when it leaves the electric field. In prior art reactor such as that shown in Figure 2, a substantially amount of the working gas or in this instance, plasma, may never come in contact with wafers 120. This is due to the fact there is sufficient space in chamber 114 to permit the free drift of plasma. In contrast, platform 40 is configured such that it divides chamber 14 into two regions, a working region 46 and an exhaust region 48. The only communication between these two regions is through openings 42. This design forces the working gas to pass only through openings 42, which are positioned immediately below wafers 20. This causes all of the plasma to flow through wafers 20 and react with the photoresist. Platform 42, which has dimensions of approximately 21 inches X 9 inches X 1/8 inch, is manufactured from a non-reactive material such as hard anodized aluminum. Platform 42 may also be manufactured from quartz.
Reactor 12 further includes an exhaust manifold 50 that is positioned adjacent chamber 140 Exhaust manifold 50 is a tube, also made of quartz, that has a plurality of ports 52 each of which is in communication with one of the barrel chamber exhaust ports 18. Exhaust manifold 50 of the preferred embodiment has five ports 52. Exhaust manifold 50 is capable of transporting away from chamber 1~
any r0maining working plasma along with gaseous by-products of the plasma-photoresist reaction.
:.
3~
In use, wafer boats 44 each of which that has a plu-rality of wafers 20 are first placed in openings 42 of platform 40. Chamber 14 is then evacuated to a moderate vacuum, approximately 1/1000 of an atomosphere. The evac-uation is accomplished by a conventional pump, not shown,that is connected to exhaust manifold 50. Diatomic oxygen, the working gas, is admitted to chamber 14 via entry gas manifold 22. ~ source of diatomic oxygen, not shown, is connected to entry gas manifold 22~
The RF generator is then activated, causing electrodes 28e/ 28m, 30e and 30m to generate electric fields in both entry gas manifold 22 and chamber 14. The electric fields produced, Ee and Em, decompose diatomic oxygen to mono-atomic oxygen, the working gasu The electric field in man-ifold 22 converts a small portion of the working gas into plasma before the gas enters ports 16 of chamber 14. The remaining portion of the working gas is converted to plasma by the electric field that is adjacent entry chamber ports 16. The position of the entry port electric field Ee forces all of the working gas to pass through the field, enhancing the conversion of gas to plasma.
As the working gas travels through chamber 14, its route oE travel is dictated by constraint platform 40.
Instead of meandering around in chamber 14, which is the case ~or plasma in prior art chambers, it can only exit by passing through openings 42. Since wafers 20 are posi-tioned irnmediately above openings 42, all of the plasma must pass through wafers 20. Since this enhances the number of oxygen-photoresist interactions, the time for completing the entire photoresist removal process is re-duced.
It will be apparent to those skilled in the art that various modifications may be made within the spirit of the invention and the scope of the appended claims.
Technical Field This invention relates to plasma reactors, and more particularly, to plasma barrel reactors for removing the photoresist from semiconductor wafers or etching thin films such as aluminum, silicon dioxide or polysilicon on silicon wafers patterned with photoresist for etching.
Background Art The use of gas plasma for processing semiconductor wafers is common in the art. For example, various techniques are described in J. Hollahan and A. Bell, Techniques and Applications of Plasma Chemistry, Ch. 9 (1974).
Semiconductor components are fabricated on a semicon-ductive substrate or wafer. The material of the wafer is generally silicon. In manufacturing semiconductor devicesl a photosensitive polymer, generally referred to as a photo-resist, is used. After selective exposure to optical radi-ation and subsequent chemical development, the photoresist hardens where it has not been removed and protects the un-derlying wafer from other chemicals. One method of re-moving photoresist from wafers after it has served its protective function is by using a gas plasma.
In general, the gas plasma used ;n removing photore-sist is oxygen. More particularly, diatomic oxygen is first exposed to an electric field which transforms some of the diatomic oxygen into an oxygen plasma that contains some monoatomic oxygen, generally referred to as atomic oxygen. Atomic oxygen is capable of reacting with the photoresist by breaking its polymer chains such that the photoresist is removed from the semiconductor wafer by the combined action of the atomic oxygen and the molecular oxy-3~'3 gen. The resultant by-products are gases such as H2O, CO
and CO2.
Prior art oxygen plasma reactors for removing photore-sist, an example of which is shown in Figure 2A, consist of a cylindrical quartz reactor. A plurality of semiconductor wafers, each of which has a layer of photoresist on its surfaces, are positioned within the reactor. Metal alec-trodes are positioned around the reactor, one of which is connected to a radio-frequency (RF) generator operating at 13.56 MHz or some harmonic of that frequency and the other is connected to the ground. The quartz reactor also includes a gas input manifold and an exhaust manifold.
Other prior art plasma reactors, not shown, include single-chamber reactor that has an electrode within the chamber, as best exemplified in U.S. Patent No. 4,230,515.
In addition, prior art reactors include double-chamber re-actor in which the plasma is generated in one chamber and the work such as photoresist removal is performed in a second chamber. The plasma may be transported between the two chambers either through a narrow channel or through narrow tubes. The primary disadvantage of the double-chamber reactor is the likelihood of plasma degeneration before it could perform the removal of the photoresist, that is, atomic oxygen tends to recombine to diatomic oxygen on the walls of t~le channel or tubes~
In prior single chamber reactors with external elec-trodes, the electrodes are wrapped around the entire sides of the cylindrical reactor so that the electric field fills the whole volume of the reactor. ~owever, due to the elec-trical skin effect of the RF discharge, the electric cur-rent produced tends to "hug'l the reactor wall. This effect is analogous to the phenomena of high frequency current flowing near the surface or sXin of a metal conductor.
Thus, most of the atomic oxyqen is produced near the walls of the reactor and is pumped out of the reactor without getting near the wafers. The only atomic oxygen that is ~81~
involved with the removal process is that which diffused into the center of the reactor where the wafers are placed and then diffusing between the wafers.
Disclosure of the Invention In view of such deficiencies in the prior art, it is a major object of the present invention to provide a plasma reactor that is capable of maximizing the use of the prod-ucts of the plasma in performing the desired chemistry. In the instance of photoresist removal, maximizing the reac-tion of the atomic oxygen with the photoresist.
In order to accomplish the above and still further objects, the present invention provides a plasma reactor that has a working chamber with at least one entry port, the entry port is adapted to receive a working gas into the working chamber. In addition, the working chamber is adapted to receive at least one article. An electrical energy generator is provided. At least one pair of elec-trodes are positioned adjacent the working chamber entry port. The electrodes, which are connected to the genera-tor, create an electric field adjacent the entry port thatconverts the working gas into a working plasma for interacting with a material of the article. The position of the electric field adjacent the entry port leaves a substantially electric f'~eld-free region in the barrel chamber adjacent the article.
In addition, the plasma reactor of the present inven-tion includes a plasma Elow constraint member which is po-sitioned within the working chamber. The constraint member permits the flow of the gas only through itself so as to enhance the interaction oE the gas with the material of the article. ~ore particularly, the constraint member includes at least one opening that is adapted to receive the article and to permit the passage of the gas.
It should be noted that as long as the material being processed is placed in the center of the electric field used to create the plasma, the species of interest will be generated and will flow around the sides of the material being processed without reacting with it to an appreciable extent. By generating the plasma upstream of the material being process, it is easy to force the species of interest to flow adjacent the material being processed. This must be done without passing the flow through narrow constric-tions which will exterminate the species of interest.
In the preferred embodiment of the present invention, the material of the article that is removed by the working plasma is photoresist~ In addition, the article is a semi-conductor wafer. Last, the working plasma consists of oxygen.
In its method aspect, the invention relates to a method of interacting a working plasma with an article which is positioned within a working chamber comprising the steps of: positioning the article in a working position within the chamber; introducing a working gas into the chamber remote from the working position; establishing an electric field for converting the working gas into the working plasma for inter-acting with a material of the article; and confining the electric field to a region immediately adjacent where the work-ing gas is introduced into the working chamber, whereby the working plasma interacts with the material of the article in the working position that is substantially electric field-free.
Other objects3 features, and advantages of the present invention will appear from the following detailed description of the best mode of a preferred embodiment, taken together with the accompanying drawings.
Pg/ ~ - 4 -,,~
Brief Description of the Drawin_ Figure 1 is a perspective view of the plasma barrel reactor of the present invention;
Figure 2 is a partial, cross-sectional~ and diagram-matical view of a prior art plasma reactor;
Figure 3 is a partial, cross-sectional, and diagram-matical view of the plasma barrel reactor of Figure l; and Figure 4 is a partial, cross-sectional, and diagram-matical view of the plasma flow constraint member of the plasma LO barrel reactor of Figures 1 and 3.
Best Mode For Carrying Out the Invention Referring to Figure l, there is shown a plasma barrel reactor, generally designated 12. Reactor 12 includes a generally barrel-like, cylindrical working chamber 14. Barrel chamber 14 may have a diameter from six to 12 inches; the diameter of chamber 14 is 12 inches in the pre-Pgl - 4A -~a~4~39 ferred embodiment. The axial length of chamber 14 is ap-proximately 21 inches. Chamber 1~ has a plura]ity of entry ports 16 for receiving a working gas and a plurality of ex-haust ports 18 for venting various gases and by-products of chamber 14. There are four entry ports 16 and five exhaust ports 18 in the preferred embodiment. Moreover, entry ports 16, as best illustrated in Figure 3, are positioned diametrically opposite exhaust ports 18. Chamber 14, in the preferred embodiment~ is made from a conventional inert material such as quartz9 Chamber 14 is adapted to receive a plurality of arti-cles 20. Articles 20, as shown, are semiconductor wafers each of which has a layer of photoresist material on it when the wafers are placed in chamber 14.
Reactor 12 further includes an entry gas manifold 22 that is positioned adjacent chamber 14. Entry gas manifold 22 is a tube, also made of ~uartz that has a plurality of ports 24 each of which is in communication with one of the barrel chamber entry ports 16. Entry gas manifold 22 in the preferred embodiment has four ports 24. Entry gas manifold 22 is capable of transporting the working gas to barrel chamber 14.
A radio-frequency (RF) electrical energy generator, not shown, is provided. In the preferred embodiment, the frequency o the RF ener~y is 13.56 MHz.
In addition, reactor 12 includes a pair of entry port electrodes 28e and 30e which are positioned adjacent barrel chamber entry ports 16, as best shown in Figure 3. Each of the electrodes 28e and 30e, which are manufactured from a conductive metal such as copper, contains a slight curva-ture in its design such that it follows the curvature of chamber 14. Electrodes 28e and 30e are capable of creating an electric field in barrel chamber 14 adjacent entry ports 16. This entry port electric field Ee then converts the working ~as to a working plasma. Moreover, the position of entry port electric field Ee delineates a substantially .
electric field-free region FR in chamber 14 ad~acent arti cles 20.
A pair of manifold electrodes 28rn and 3nm, which are positioned adjacent entry gas manifold 22, is also pro-vided. Each of the manifold electrodes 28m and 30m is agenerally vertically-extending plate that is positioned at either side of manifold 22, as best shown in Figure 3.
Electrodes 28m and 30m are also manufactured from a conduc-tive metal such as copper. Manifold electrodes 28m and 30m are capable of creating an electric field in manifold 22.
~he manifold electric field Em converts a portion of the working gas to the working plasma before the working gas enters chamber 14. The combined effort of the manifold electric field Em and the entry port electric field Ee efficaciously convert the working gas to the desired work-ing plasma.
Although electrodes 28e and 28m and electrodes 30e and 30m are claimed and described as separate and discrete electrodes, electrodes 28e and 28m could be manufactured as a single electrode and electrodes 30e and 30m as a single electrode. In addition, manifold electrodes 28m and 30m need not be required in all instances. Although the mani-fold electric field Em generated by electrodes 28m and 30m does contribute to the efficacious conversion of the work-ing gas to the working plasma, its elimination does notdetract the overall conversion of the working gas to the working plasma made by the entry port electric field Ee alone.
Reactor 12 also includes a plasma flow constraint mem-ber 40 that is positioned within barrel chamber 14. Con-straint member 40 is a planar, board-like platform which has a plurality of openings 42. Openings 42 perform two functions the first of which is to receive wafers 20.
Wafers 20 are first placed into a conventional wafer recep-tacle 44, which is generally referred to as a wafer boat.Each ~afer boat 44 is capable of receiving a plurality of ~ ~314~
wafers, as best shown in Figure 4~ The wafers in boat 44 are spaced apart sufficiently so as to permit the atomic oxygen to flow among them and react with the photoresist which are on the wafers. Boat 44, which is manufactured from an inert material such as quartz, is then received in opening 42.
The next, and more important, function of platform 40 is to restrict the flow of the working gas, and direct it only to wafers 20. The working gas ceases to be a plasma when it leaves the electric field. In prior art reactor such as that shown in Figure 2, a substantially amount of the working gas or in this instance, plasma, may never come in contact with wafers 120. This is due to the fact there is sufficient space in chamber 114 to permit the free drift of plasma. In contrast, platform 40 is configured such that it divides chamber 14 into two regions, a working region 46 and an exhaust region 48. The only communication between these two regions is through openings 42. This design forces the working gas to pass only through openings 42, which are positioned immediately below wafers 20. This causes all of the plasma to flow through wafers 20 and react with the photoresist. Platform 42, which has dimensions of approximately 21 inches X 9 inches X 1/8 inch, is manufactured from a non-reactive material such as hard anodized aluminum. Platform 42 may also be manufactured from quartz.
Reactor 12 further includes an exhaust manifold 50 that is positioned adjacent chamber 140 Exhaust manifold 50 is a tube, also made of quartz, that has a plurality of ports 52 each of which is in communication with one of the barrel chamber exhaust ports 18. Exhaust manifold 50 of the preferred embodiment has five ports 52. Exhaust manifold 50 is capable of transporting away from chamber 1~
any r0maining working plasma along with gaseous by-products of the plasma-photoresist reaction.
:.
3~
In use, wafer boats 44 each of which that has a plu-rality of wafers 20 are first placed in openings 42 of platform 40. Chamber 14 is then evacuated to a moderate vacuum, approximately 1/1000 of an atomosphere. The evac-uation is accomplished by a conventional pump, not shown,that is connected to exhaust manifold 50. Diatomic oxygen, the working gas, is admitted to chamber 14 via entry gas manifold 22. ~ source of diatomic oxygen, not shown, is connected to entry gas manifold 22~
The RF generator is then activated, causing electrodes 28e/ 28m, 30e and 30m to generate electric fields in both entry gas manifold 22 and chamber 14. The electric fields produced, Ee and Em, decompose diatomic oxygen to mono-atomic oxygen, the working gasu The electric field in man-ifold 22 converts a small portion of the working gas into plasma before the gas enters ports 16 of chamber 14. The remaining portion of the working gas is converted to plasma by the electric field that is adjacent entry chamber ports 16. The position of the entry port electric field Ee forces all of the working gas to pass through the field, enhancing the conversion of gas to plasma.
As the working gas travels through chamber 14, its route oE travel is dictated by constraint platform 40.
Instead of meandering around in chamber 14, which is the case ~or plasma in prior art chambers, it can only exit by passing through openings 42. Since wafers 20 are posi-tioned irnmediately above openings 42, all of the plasma must pass through wafers 20. Since this enhances the number of oxygen-photoresist interactions, the time for completing the entire photoresist removal process is re-duced.
It will be apparent to those skilled in the art that various modifications may be made within the spirit of the invention and the scope of the appended claims.
Claims (18)
1. A plasma reactor, comprising a working chamber having at least one entry port for receiving a working gas into said working chamber, said working chamber is adapted to receive at least one article;
an electrical energy generator;
at least one pair of electrodes positioned about said working chamber, said electrodes, which are connected to said generator, create an electric field that converts said working gas into a working plasma;
a plasma flow constraint member positioned within said working chamber for restricting the flow of said working plasma, whereby said constraint member permits the flow of said working plasma only through itself so as to enhance the interaction of said working plasma with a material of said article.
an electrical energy generator;
at least one pair of electrodes positioned about said working chamber, said electrodes, which are connected to said generator, create an electric field that converts said working gas into a working plasma;
a plasma flow constraint member positioned within said working chamber for restricting the flow of said working plasma, whereby said constraint member permits the flow of said working plasma only through itself so as to enhance the interaction of said working plasma with a material of said article.
2. The plasma reactor as claimed in claim 1, wherein said plasma flow constraint member includes at least one opening which is adapted to receive said article and to permit the passage of said working plasma.
3. The plasma reactor as claimed in claim 1, wherein said material of said article is photoresist.
4. The plasma reactor as claimed in claim 3, wherein said article is a semiconductor wafer.
5. The plasma reactor as claimed in claim 4, wherein said working plasma consists of oxygen.
6. The plasma barrel reactor as claimed in claim 1 or 2, wherein the material of said article is a thin film of aluminum, silicon dioxide, or polysilicon on silicon wafers patterned with photoresist ready for etching.
7. A plasma barrel reactor, comprising a generally barrel-like working chamber having at least one entry port, said barrel chamber is adapted to receive at least one article;
an entry gas manifold positioned adjacent said barrel chamber, said entry gas manifold having at least one port that communicates with said barrel chamber entry port, said entry gas manifold is adapted to transport a working gas to said barrel chamber;
a radio-frequency electrical energy generator;
at least one pair of entry port electrodes positioned adjacent said barrel chamber entry port, said electrodes, which are connected to said generator, create an electric field in said barrel chamber adjacent said entry port that converts said working gas into a working plasma;
at least one pair of manifold electrodes positioned adjacent said entry gas manifold, said manifold electrodes, which are also connected to said generator, create an electric field in said manifold that converts a portion of said working gas into a working plasma before said working gas enters said barrel chamber, whereby said manifold electric field and said entry port electric field efficaciously convert said working gas to said working plasma; and a plasma flow constraint member positioned within said barrel chamber for restricting the flow of said working plasma, whereby said constraint member permits the flow of said working plasma only through itself so as to enhance the interaction of said working plasma with a material of said article.
an entry gas manifold positioned adjacent said barrel chamber, said entry gas manifold having at least one port that communicates with said barrel chamber entry port, said entry gas manifold is adapted to transport a working gas to said barrel chamber;
a radio-frequency electrical energy generator;
at least one pair of entry port electrodes positioned adjacent said barrel chamber entry port, said electrodes, which are connected to said generator, create an electric field in said barrel chamber adjacent said entry port that converts said working gas into a working plasma;
at least one pair of manifold electrodes positioned adjacent said entry gas manifold, said manifold electrodes, which are also connected to said generator, create an electric field in said manifold that converts a portion of said working gas into a working plasma before said working gas enters said barrel chamber, whereby said manifold electric field and said entry port electric field efficaciously convert said working gas to said working plasma; and a plasma flow constraint member positioned within said barrel chamber for restricting the flow of said working plasma, whereby said constraint member permits the flow of said working plasma only through itself so as to enhance the interaction of said working plasma with a material of said article.
8. The plasma barrel reactor as claimed in claim 7, wherein the position of said electric field adjacent said entry port delineates a substantially electric field-free region in said barrel chamber adjacent said article, downstream of the plasma generating region.
9. The plasma barrel reactor as claimed in claim 8, wherein said plasma flow constraint member is a generally planar, board-like platform that includes at least one opening that is adapted to receive said article and to permit the passage of said working plasma.
10. The plasma barrel reactor as claimed in claim 7, wherein said material of said article is photoresist.
11. The plasma barrel reactor as claimed in claim 10, wherein said article is a semiconductor wafer.
12. The plasma barrel reactor as claimed in claim 11, wherein said working plasma consists of oxygen.
13. The plasma barrel reactor as claimed in claim 7 or 8, wherein the material of said article is a thin film of aluminum, silicon dioxide, or polysilicon on silicon wafers patterned with photoresist ready for etching.
14. A method of interacting a working plasma with an article which is positioned within a working chamber comprising the steps of positioning said article in a working position within said chamber;
introducing a working gas into said chamber remote from said working position;
establishing an electric field for converting said working gas into said working plasma for interacting with a material of said article;
confining said electric field to a region immediately adjacent where said working gas is introduced into said working chamber, whereby said working plasma interacts with said material of said article in said working position that is substantially electric field-free; and restricting the flow of said working plasma so as to enhance the interaction of said working plasma with said material of said article.
introducing a working gas into said chamber remote from said working position;
establishing an electric field for converting said working gas into said working plasma for interacting with a material of said article;
confining said electric field to a region immediately adjacent where said working gas is introduced into said working chamber, whereby said working plasma interacts with said material of said article in said working position that is substantially electric field-free; and restricting the flow of said working plasma so as to enhance the interaction of said working plasma with said material of said article.
15. The method of interacting a working plasma with an article as claimed in claim 14, wherein said material of said article is photoresist.
16. The method of interacting a working plasma with an article as claimed in claim 15, wherein said article is a semiconductor wafer.
17. The method of interacting a working plasma with an article as claimed in claim 16, wherein said working plasma consists of oxygen.
18. The method of interacting a working plasma with an article as claimed in claim 14, wherein the material of said article is a thin film of aluminum, silicon dioxide, or polysilicon on silicon wafers patterned with photoresist ready for etching.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US69835785A | 1985-02-05 | 1985-02-05 | |
| US698,357 | 1985-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1281439C true CA1281439C (en) | 1991-03-12 |
Family
ID=24804903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000500981A Expired - Lifetime CA1281439C (en) | 1985-02-05 | 1986-02-03 | Plasma reactor and method for removing photoresist |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS61191033A (en) |
| CA (1) | CA1281439C (en) |
| DE (1) | DE3603355A1 (en) |
| FR (1) | FR2579059A1 (en) |
| GB (1) | GB2175131B (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3847652A (en) * | 1972-12-08 | 1974-11-12 | Nasa | Method of preparing water purification membranes |
| US4362632A (en) * | 1974-08-02 | 1982-12-07 | Lfe Corporation | Gas discharge apparatus |
| US4192706A (en) * | 1975-01-22 | 1980-03-11 | Tokyo Shibaura Electric Co., Ltd. | Gas-etching device |
| US4230515A (en) * | 1978-07-27 | 1980-10-28 | Davis & Wilder, Inc. | Plasma etching apparatus |
| JPS5531154A (en) * | 1978-08-28 | 1980-03-05 | Hitachi Ltd | Plasma etching apparatus |
| US4342901A (en) * | 1980-08-11 | 1982-08-03 | Eaton Corporation | Plasma etching electrode |
| EP0090067B2 (en) * | 1982-03-31 | 1991-03-20 | Ibm Deutschland Gmbh | Reactor for reactive ion etching, and etching process |
-
1986
- 1986-02-03 CA CA000500981A patent/CA1281439C/en not_active Expired - Lifetime
- 1986-02-04 DE DE19863603355 patent/DE3603355A1/en not_active Withdrawn
- 1986-02-04 FR FR8601507A patent/FR2579059A1/en not_active Withdrawn
- 1986-02-04 JP JP2135786A patent/JPS61191033A/en active Pending
- 1986-02-04 GB GB08602734A patent/GB2175131B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2175131B (en) | 1988-12-29 |
| JPS61191033A (en) | 1986-08-25 |
| GB8602734D0 (en) | 1986-03-12 |
| DE3603355A1 (en) | 1986-08-07 |
| FR2579059A1 (en) | 1986-09-19 |
| GB2175131A (en) | 1986-11-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |