US20120138229A1 - Plasma processing apparatus - Google Patents
Plasma processing apparatus Download PDFInfo
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- US20120138229A1 US20120138229A1 US13/020,929 US201113020929A US2012138229A1 US 20120138229 A1 US20120138229 A1 US 20120138229A1 US 201113020929 A US201113020929 A US 201113020929A US 2012138229 A1 US2012138229 A1 US 2012138229A1
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- plasma
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- processing chamber
- vacuum processing
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- 238000012545 processing Methods 0.000 title claims abstract description 52
- 230000006698 induction Effects 0.000 claims abstract description 40
- 238000012937 correction Methods 0.000 claims abstract description 10
- 238000007789 sealing Methods 0.000 claims abstract description 4
- 239000004020 conductor Substances 0.000 claims description 32
- 239000000523 sample Substances 0.000 description 40
- 238000005530 etching Methods 0.000 description 24
- 239000007789 gas Substances 0.000 description 12
- 238000005259 measurement Methods 0.000 description 6
- 230000001939 inductive effect Effects 0.000 description 5
- 238000009616 inductively coupled plasma Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910015844 BCl3 Inorganic materials 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000005389 semiconductor device fabrication Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical compound ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 description 1
Images
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
- H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
-
- 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
- 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
- H01J37/32642—Focus rings
Definitions
- the present invention relates to plasma processing apparatuses, and more specifically, relates to inductively coupled plasma processing apparatuses.
- inductively coupled plasma processing apparatuses are used to perform etching and surface treatments.
- this type of plasma processing apparatus a few turns of induction coils are arranged on the outer side of a vacuum chamber of the apparatus and radio frequency current is supplied to the coils so as to feed power to generate plasma.
- stray capacitance occurs between the induction coils and plasma, causing local damages of the vacuum chamber.
- Japanese patent application laid-open publication No. 2007-158373 discloses an apparatus capable of preventing this problem by disposing a Faraday shield composed of a conductor between the induction coils and plasma.
- the present inventors have also confirmed via experiment that eccentricity of distribution of plasma diffused above the wafer occurs by the influence of magnetic fields.
- plasma processing was performed by disposing an approximately 0.4 mT magnet to the outer circumference of the plasma processing chamber 1 .
- a minute magnetic field as small as 0.4 mT created by the magnet caused the plasma distribution diffused above the wafer to be varied greatly.
- plasma is possibly influenced by even a minute magnetic field as small as geomagnetism.
- the above-mentioned phenomenon may also be caused by the magnetic field created via a vacuum pressure gauge or a motor disposed on the processing apparatus.
- the eccentricity of plasma diffused above the wafer influenced by the magnetic field is caused by the generated plasma being diffused obliquely toward the wafer by the influence of the magnetic field.
- etching is performed while the plasma diffused above the wafer has eccentricity, the uniformity and verticalness of the etching process is deteriorated.
- Demands are increasing for higher accuracy and higher speed of etching processes, and the influence of magnetic fields cannot be ignored in order to realize stable etching processes.
- the following three problems occur when the art disclosed in patent document 2 is adopted to solve the influence of magnetic fields.
- the first problem is the problem of performance. Plasma processing chambers must have openings for transferring samples to be processed or for evacuating processing gases, so that it is actually impossible to shield magnetic fields.
- the eccentricity of plasma caused by the oblique diffusion of plasma mentioned above may also occur due to the eccentricity of vacuum within the plasma processing chamber 1 .
- the present invention aims at solving the three problems mentioned above and the influence of vacuum eccentricity, not by shielding magnetic fields but by providing a plasma processing apparatus having a means for generating plasma capable of correcting the eccentricity of plasma diffused above the wafer caused by magnetic fields and vacuum eccentricity.
- the present invention provides a plasma processing apparatus comprising a vacuum processing chamber in which a sample is processed via plasma, a gas supply means for supplying gas into the vacuum processing chamber, a sample stage disposed within the vacuum processing chamber on which the sample is placed, an induction coil disposed outside the vacuum processing chamber, a radio frequency power supply for supplying radio frequency power to the induction coil, a Faraday shield being capacitively coupled with the plasma, and an eccentricity correction means disposed between the induction coil and a dielectric sealing window constituting an upper surface of the vacuum processing chamber, wherein the eccentricity correction means generates a plasma capable of correcting the eccentricity of the plasma.
- the arrangement of the present invention enables to correct the eccentricity of plasma diffused above the wafer and to achieve the desired etching performance.
- FIG. 1 is a cross-sectional view of the plasma processing apparatus according to the present invention.
- FIG. 2 is a view showing the position for arranging a conductor ring
- FIG. 3 is a view showing the diffusion of plasma in a state where no magnetic field exists
- FIG. 4 is a view showing the diffusion of plasma when a magnetic field is applied from outside the plasma processing chamber
- FIG. 5 is a view showing the correction of eccentricity of plasma when the conductor ring is applied
- FIG. 6 is a view showing the concept of operation of the conductor ring
- FIG. 7 is a view showing the shape of the conductor ring.
- FIG. 8 is a view showing the verification result of the effect according to the present invention.
- FIG. 1 shows a cross-sectional view of a plasma processing apparatus according to the present invention.
- a plasma processing chamber 1 is composed of a window 1 a which is a parallel plate dielectric sealing window formed of an insulating material (a nonconductive material such as alumina (Al 2 O 3 ) ceramics) having a plasma generating section formed therein, and a chamber 1 b having arranged therein a sample stage 3 for mounting a sample 2 which is a wafer.
- An induction coil 4 is arranged on the outer side of the window 1 a .
- the induction coil 4 is divided into two lines, an inner circumference coil 4 a and an outer circumference coil 4 b each having two turns, through which current flows in the direction shown by the arrows in the drawing.
- a plate-shaped Faraday shield 6 capacitively coupled with plasma 5 is disposed between the window 1 a and the induction coils 4 , wherein the induction coils 4 and the Faraday shield 6 are series-connected via a matching box 7 to a first radio frequency power supply 8 .
- a variable capacitor and a coil are disposed within the matching box 7 . Therefore, current can be flown independently to two branched lines of the inner circumference coil 4 a and the outer circumference coil 4 b , and this current and the voltage applied to the Faraday shield 6 can be controlled.
- a capacitor is disposed in the matching box for suppressing the reflection of radio frequency power of 13.56 MHz or 27.12 MHz generated from the first radio frequency power supply 8 , for example.
- the Faraday shield 6 is composed of a metallic conductor having vertical striped slits and arranged to be superposed to the window 1 a .
- the present apparatus realizes a function to prevent local damages of the window 1 a caused by the stray capacitance between the induction coils 4 and plasma 5 , and a function to maintain the inner wall of the plasma processing chamber 1 to a most suitable condition by applying uniformly-sized capacitive coupling actively controlled via the matching box 7 to the plasma.
- the conductor ring 12 is disposed between the induction coils 4 and the Faraday shield 6 , and further arranged to be in conduction with the Faraday shield 6 .
- the conductor ring 12 is disposed between the induction coils 4 and the Faraday shield 6 according to the present embodiment, but equivalent functions can be realized by arranging the conductor ring 12 between the induction coils 4 and the window 1 a.
- the plasma processing apparatus of the present invention as described above enables to generate plasma capable of correcting the eccentricity of plasma diffused above the sample 2 caused by the influence of the magnetic field other than the induction magnetic field generated by the induction coils 4 . This is due to the following operation of the present invention. As shown in FIG. 3 , when there are no influences by magnetic fields other than the induction magnetic field created via the induction coils 4 , the generated plasma 5 a is diffused straight toward the sample 2 , so that the plasma does not have any eccentricity. Next, as shown in FIG.
- the plasma processing apparatus enables to generate plasma 5 b capable of correcting the eccentricity of plasma diffused above the sample 2 , so that the eccentricity of plasma diffused above the sample 2 can be improved.
- Plasma correcting the eccentricity of plasma diffused above the sample 2 refers to a plasma capable of correcting the eccentricity in advance so that the plasma diffused obliquely above the sample 2 does not have eccentricity.
- inductive current 13 a flows along the circumference of the conductor ring 12 in the direction to cancel out the induction magnetic field generated from the induction coils. Further, since the conductor ring 12 is in conduction with the Faraday shield 6 , an inductive current 13 b is also flown therethrough.
- the conductor ring 12 on the Faraday shield 6 at an eccentric position displaced from the center axis of the induction coils 4 so that the inductive current 13 a and the inductive current 13 b flow in the position where the plasma density must be decreased or where the plasma diffused above the sample 2 is positioned eccentrically, the mutual inductance between the induction coils 4 and the plasma can be varied, according to which a plasma capable of correcting the eccentricity of plasma diffused above the sample 2 can be generated.
- the eccentricity of the plasma diffused above the sample 2 is improved, so that the eccentricity of plasma diffused above the sample 2 caused by the influence of vacuum eccentricity can also be improved similarly as the eccentricity of plasma diffused above the sample 2 caused by the above-described influence of magnetic fields.
- the conductor ring 12 is in conduction with the Faraday shield 6 according to the present embodiment, but the conductor ring 12 can be in conduction with anything capable of creating a closed loop through which inductive current flows, so that the conductor ring 12 can be in conduction with the chamber 1 b or the cover of the matching box 7 , for example.
- FIG. 7 an example of the shape of the conductor ring 12 is shown in FIG. 7 .
- the conductor ring 12 according to the present invention is a ring-shaped member as shown in FIG. 7( a ) formed for example of a conductor such as aluminum or stainless steel. Further, the ring-like shape is not restricted to the shape illustrated in FIG. 7( a ), and the conductor ring can also be a comb-shaped conductor ring as shown in FIG. 7( b ). Further, since the conductor ring 12 according to the present invention is in conduction with the Faraday shield 6 , it does not have to be ring-shaped. Thus, the conductor ring 12 can be in a divided form as shown in FIG. 7( c ). Moreover, a plurality of or multiple varieties of conductor rings can be used simultaneously. The conductor ring 12 is to be disposed independently so that it can cope with any eccentric position of plasma distribution. Since the conductor ring can be installed independently, it becomes possible to perform adjustment in response to inter-instrument differences.
- FIG. 8 is a drawing showing the result of verification, wherein the illustrated etching rate measurement is the in-plane distribution of etching rate of the sample when a sample having an alumina (Al 2 O 3 ) thin film is etched using a chlorine-based gas (mixed gas of Cl 2 gas and BCl 3 gas) in an inductively coupled plasma etching apparatus designed to etch a ⁇ 200 mm sample in which the plasma eccentricity is especially significant.
- the graph showing the in-plane distribution of etching rate of samples illustrates in contour the in-plane distribution of etching rate of samples at designated points on the sample measured before and after processing using a film thickness measurement device.
- the contour lines show that the areas having lighter colors have high etching rates and the areas having darker colors have low etching rates.
- the effect of the present invention was verified by computing the average of the in-plane etching rate at respective points, the in-plane uniformity of the etching rate and the eccentricity ratio.
- the eccentricity ratio is an index showing the level of eccentricity of plasma diffused above the sample 2 , wherein smaller values of eccentricity ratio indicate smaller eccentricity.
- the etching rate at the lower right side of the drawing is high in the in-plane distribution of the sample. This is caused by the eccentricity of the plasma at the lower right side due to the influence of magnetic fields.
- the in-plane distribution of etching rate of the sample when a magnet is disposed on the outer circumference of the prior art plasma processing apparatus is shown in FIG. 8( b ).
- etching rate measurement performed by disposing a north pole and a south pole of a magnet (0.4 mT) at areas shown in FIG. 8( b ) the portion where etching rate was high has moved to the upper right side of the sample.
- the position of eccentricity of plasma diffused above the sample 2 can be estimated based on the result of in-plane etching rate distribution of the sample when magnetic fields are generated at various locations.
- the eccentricity of plasma diffused on the sample 2 can be improved.
- FIG. 8( c ) according to the in-plane distribution of etching rate of the sample to which the present invention is applied, the eccentricity ratio of the plasma has been improved from 8.6% to 2.7%, and along therewith, the in-plane uniformity of etching rate of the sample has been improved from 8.3% to 5.8%.
- the present embodiment has been illustrated based on an example in which the location of eccentricity of the plasma diffused above the sample has been estimated based on the measurement of in-plane distribution of etching rate of the sample, but the estimation of location of eccentricity of the plasma diffused above the sample can also be performed based for example on ion current flux measurement or plasma density distribution measurement using probes.
- the plasma processing apparatus provides an eccentricity correction means for generating a plasma capable of correcting the eccentricity of plasma diffused above the sample, thereby improving the eccentricity of plasma diffused above the sample caused by the influence of magnetic fields or by the eccentricity of vacuum within the plasma processing chamber.
Abstract
The invention provides a plasma processing apparatus having a means for generating a plasma capable of correcting the eccentricity of the plasma diffused above the wafer caused by magnetic field or by vacuum eccentricity, comprising a vacuum processing chamber in which a sample is processed via plasma, a gas supply means for supplying gas into the vacuum processing chamber, a sample stage disposed within the vacuum processing chamber on which the sample is placed, an induction coil disposed outside the vacuum processing chamber, a radio frequency power supply for supplying radio frequency power to the induction coil, a Faraday shield being capacitively coupled with the plasma, and an eccentricity correction means disposed between the induction coil and a dielectric sealing window constituting an upper surface of the vacuum processing chamber, wherein the eccentricity correction means generates a plasma capable of correcting the eccentricity of the plasma.
Description
- The present application is based on and claims priority of Japanese patent application No. 2010-269875 filed on Dec. 3, 2010, the entire contents of which are hereby incorporated by reference.
- 1. Field of the Invention
- The present invention relates to plasma processing apparatuses, and more specifically, relates to inductively coupled plasma processing apparatuses.
- 2. Description of the Related Art
- In the field of semiconductor device fabrication, inductively coupled plasma processing apparatuses are used to perform etching and surface treatments. In this type of plasma processing apparatus, a few turns of induction coils are arranged on the outer side of a vacuum chamber of the apparatus and radio frequency current is supplied to the coils so as to feed power to generate plasma. At this time, stray capacitance occurs between the induction coils and plasma, causing local damages of the vacuum chamber. Japanese patent application laid-open publication No. 2007-158373 (patent document 1) discloses an apparatus capable of preventing this problem by disposing a Faraday shield composed of a conductor between the induction coils and plasma.
- It is known that regardless of the type of inductively coupled plasma source being applied, the generated plasma becomes uneven along the circumferential direction of the induction coils, since uneven current distribution along the induction coils is unavoidable. This phenomenon causes the eccentricity of plasma in which the center axis of plasma diffused above the wafer is displaced from the center axis of the induction coils. Plasma eccentricity is also considered to be caused by the influence of magnetic fields, wherein Japanese patent application laid-open publication No. 2004-22988 (patent document 2) discloses an apparatus for covering the whole body of the plasma processing chamber with a magnetic member to shield the magnetic fields, thereby solving the above-mentioned problem of influence of magnetic fields.
- The present inventors have also confirmed via experiment that eccentricity of distribution of plasma diffused above the wafer occurs by the influence of magnetic fields. In the experiment, plasma processing was performed by disposing an approximately 0.4 mT magnet to the outer circumference of the
plasma processing chamber 1. As a result, it was discovered that a minute magnetic field as small as 0.4 mT created by the magnet caused the plasma distribution diffused above the wafer to be varied greatly. It has been recognized that plasma is possibly influenced by even a minute magnetic field as small as geomagnetism. The above-mentioned phenomenon may also be caused by the magnetic field created via a vacuum pressure gauge or a motor disposed on the processing apparatus. The eccentricity of plasma diffused above the wafer influenced by the magnetic field is caused by the generated plasma being diffused obliquely toward the wafer by the influence of the magnetic field. When etching is performed while the plasma diffused above the wafer has eccentricity, the uniformity and verticalness of the etching process is deteriorated. Demands are increasing for higher accuracy and higher speed of etching processes, and the influence of magnetic fields cannot be ignored in order to realize stable etching processes. The following three problems occur when the art disclosed inpatent document 2 is adopted to solve the influence of magnetic fields. The first problem is the problem of performance. Plasma processing chambers must have openings for transferring samples to be processed or for evacuating processing gases, so that it is actually impossible to shield magnetic fields. Moreover, when the chamber is covered by a magnetic member, induction loss occurs within the magnetic member due to the induction magnetic field generated by the induction coils, according to which the plasma generating ability is deteriorated. The second problem is related to the mounting process. A significant change of design is required to cover the whole chamber with the magnetic member, and dangers during operation increase along with the increased chances of handling heavy loads during assembly. The third problem relates to costs. According to the art disclosed inpatent document 2, a large amount of magnetic materials capable of covering the plasma processing chamber must be used, which requires a large amount of costs. These three problems are extremely serious in manufacturing mass production apparatuses. Other than the above-mentioned influence of magnetic fields, the eccentricity of plasma caused by the oblique diffusion of plasma mentioned above may also occur due to the eccentricity of vacuum within theplasma processing chamber 1. Thus, the present invention aims at solving the three problems mentioned above and the influence of vacuum eccentricity, not by shielding magnetic fields but by providing a plasma processing apparatus having a means for generating plasma capable of correcting the eccentricity of plasma diffused above the wafer caused by magnetic fields and vacuum eccentricity. - The present invention provides a plasma processing apparatus comprising a vacuum processing chamber in which a sample is processed via plasma, a gas supply means for supplying gas into the vacuum processing chamber, a sample stage disposed within the vacuum processing chamber on which the sample is placed, an induction coil disposed outside the vacuum processing chamber, a radio frequency power supply for supplying radio frequency power to the induction coil, a Faraday shield being capacitively coupled with the plasma, and an eccentricity correction means disposed between the induction coil and a dielectric sealing window constituting an upper surface of the vacuum processing chamber, wherein the eccentricity correction means generates a plasma capable of correcting the eccentricity of the plasma.
- The arrangement of the present invention enables to correct the eccentricity of plasma diffused above the wafer and to achieve the desired etching performance.
-
FIG. 1 is a cross-sectional view of the plasma processing apparatus according to the present invention; -
FIG. 2 is a view showing the position for arranging a conductor ring; -
FIG. 3 is a view showing the diffusion of plasma in a state where no magnetic field exists; -
FIG. 4 is a view showing the diffusion of plasma when a magnetic field is applied from outside the plasma processing chamber; -
FIG. 5 is a view showing the correction of eccentricity of plasma when the conductor ring is applied; -
FIG. 6 is a view showing the concept of operation of the conductor ring; -
FIG. 7 is a view showing the shape of the conductor ring; and -
FIG. 8 is a view showing the verification result of the effect according to the present invention. - Now, a preferred embodiment of the present invention will be described in detail with reference to the drawings.
-
FIG. 1 shows a cross-sectional view of a plasma processing apparatus according to the present invention. Aplasma processing chamber 1 is composed of awindow 1 a which is a parallel plate dielectric sealing window formed of an insulating material (a nonconductive material such as alumina (Al2O3) ceramics) having a plasma generating section formed therein, and achamber 1 b having arranged therein asample stage 3 for mounting asample 2 which is a wafer. Aninduction coil 4 is arranged on the outer side of thewindow 1 a. Theinduction coil 4 is divided into two lines, aninner circumference coil 4 a and anouter circumference coil 4 b each having two turns, through which current flows in the direction shown by the arrows in the drawing. Further, a plate-shaped Faradayshield 6 capacitively coupled withplasma 5 is disposed between thewindow 1 a and theinduction coils 4, wherein theinduction coils 4 and the Faradayshield 6 are series-connected via amatching box 7 to a first radio frequency power supply 8. A variable capacitor and a coil are disposed within the matchingbox 7. Therefore, current can be flown independently to two branched lines of theinner circumference coil 4 a and theouter circumference coil 4 b, and this current and the voltage applied to the Faradayshield 6 can be controlled. Furthermore, a capacitor is disposed in the matching box for suppressing the reflection of radio frequency power of 13.56 MHz or 27.12 MHz generated from the first radio frequency power supply 8, for example. - While feeding processing gas from a
gas supply device 9 into theplasma processing chamber 1, the pressure within theplasma processing chamber 1 is decompressed to a predetermined pressure via avacuum device 10. Processing gas is fed from thegas supply device 9 to theplasma processing chamber 1, and plasma is generated by the processing gas via the action of an electric field created via the Faradayshield 6 and the induction magnetic field created via theinduction coils 4. A second radiofrequency power supply 11 is connected to thesample stage 3. A bias power is applied from the second radiofrequency power supply 11 to thesample stage 3 so as to draw ions existing within theplasma 5 toward thesample 2. The Faradayshield 6 is composed of a metallic conductor having vertical striped slits and arranged to be superposed to thewindow 1 a. Thus, the present apparatus realizes a function to prevent local damages of thewindow 1 a caused by the stray capacitance between theinduction coils 4 andplasma 5, and a function to maintain the inner wall of theplasma processing chamber 1 to a most suitable condition by applying uniformly-sized capacitive coupling actively controlled via the matchingbox 7 to the plasma. - As shown in
FIG. 2 , theconductor ring 12 according to the present invention is disposed between theinduction coils 4 and the Faradayshield 6, and further arranged to be in conduction with the Faradayshield 6. Theconductor ring 12 is disposed between theinduction coils 4 and the Faradayshield 6 according to the present embodiment, but equivalent functions can be realized by arranging theconductor ring 12 between theinduction coils 4 and thewindow 1 a. - The plasma processing apparatus of the present invention as described above enables to generate plasma capable of correcting the eccentricity of plasma diffused above the
sample 2 caused by the influence of the magnetic field other than the induction magnetic field generated by theinduction coils 4. This is due to the following operation of the present invention. As shown inFIG. 3 , when there are no influences by magnetic fields other than the induction magnetic field created via the induction coils 4, the generatedplasma 5 a is diffused straight toward thesample 2, so that the plasma does not have any eccentricity. Next, as shown inFIG. 4 , if there are influences caused by magnetic fields other than the induction magnetic field created via the induction coils 4, the generatedplasma 5 a will be diffused obliquely, so that the plasma diffused above the sample has eccentricity. Therefore, as shown inFIG. 5 , the plasma processing apparatus according to the present invention enables to generateplasma 5 b capable of correcting the eccentricity of plasma diffused above thesample 2, so that the eccentricity of plasma diffused above thesample 2 can be improved. Plasma correcting the eccentricity of plasma diffused above thesample 2 refers to a plasma capable of correcting the eccentricity in advance so that the plasma diffused obliquely above thesample 2 does not have eccentricity. Next, a means for generating the plasma capable of correcting the eccentricity of plasma diffused above thesample 2 mentioned above will be described. As shown inFIG. 6 , since aconductor ring 12 which is a ring-shaped conductor is disposed between theinduction coils 4 and theFaraday shield 6, inductive current 13 a flows along the circumference of theconductor ring 12 in the direction to cancel out the induction magnetic field generated from the induction coils. Further, since theconductor ring 12 is in conduction with theFaraday shield 6, an inductive current 13 b is also flown therethrough. Therefore, by arranging theconductor ring 12 on theFaraday shield 6 at an eccentric position displaced from the center axis of theinduction coils 4 so that the inductive current 13 a and the inductive current 13 b flow in the position where the plasma density must be decreased or where the plasma diffused above thesample 2 is positioned eccentrically, the mutual inductance between theinduction coils 4 and the plasma can be varied, according to which a plasma capable of correcting the eccentricity of plasma diffused above thesample 2 can be generated. Furthermore, according to the operation of the present invention mentioned above, the eccentricity of the plasma diffused above thesample 2 is improved, so that the eccentricity of plasma diffused above thesample 2 caused by the influence of vacuum eccentricity can also be improved similarly as the eccentricity of plasma diffused above thesample 2 caused by the above-described influence of magnetic fields. Furthermore, theconductor ring 12 is in conduction with theFaraday shield 6 according to the present embodiment, but theconductor ring 12 can be in conduction with anything capable of creating a closed loop through which inductive current flows, so that theconductor ring 12 can be in conduction with thechamber 1 b or the cover of thematching box 7, for example. Next, an example of the shape of theconductor ring 12 is shown inFIG. 7 . Theconductor ring 12 according to the present invention is a ring-shaped member as shown inFIG. 7( a) formed for example of a conductor such as aluminum or stainless steel. Further, the ring-like shape is not restricted to the shape illustrated inFIG. 7( a), and the conductor ring can also be a comb-shaped conductor ring as shown inFIG. 7( b). Further, since theconductor ring 12 according to the present invention is in conduction with theFaraday shield 6, it does not have to be ring-shaped. Thus, theconductor ring 12 can be in a divided form as shown inFIG. 7( c). Moreover, a plurality of or multiple varieties of conductor rings can be used simultaneously. Theconductor ring 12 is to be disposed independently so that it can cope with any eccentric position of plasma distribution. Since the conductor ring can be installed independently, it becomes possible to perform adjustment in response to inter-instrument differences. - Next, the result of verification of the effect of the present invention via the etching rate will be described.
FIG. 8 is a drawing showing the result of verification, wherein the illustrated etching rate measurement is the in-plane distribution of etching rate of the sample when a sample having an alumina (Al2O3) thin film is etched using a chlorine-based gas (mixed gas of Cl2 gas and BCl3 gas) in an inductively coupled plasma etching apparatus designed to etch a Ø 200 mm sample in which the plasma eccentricity is especially significant. Further, the graph showing the in-plane distribution of etching rate of samples illustrates in contour the in-plane distribution of etching rate of samples at designated points on the sample measured before and after processing using a film thickness measurement device. The contour lines show that the areas having lighter colors have high etching rates and the areas having darker colors have low etching rates. The effect of the present invention was verified by computing the average of the in-plane etching rate at respective points, the in-plane uniformity of the etching rate and the eccentricity ratio. The eccentricity ratio is an index showing the level of eccentricity of plasma diffused above thesample 2, wherein smaller values of eccentricity ratio indicate smaller eccentricity. - First, according to the prior art plasma processing apparatus as shown in
FIG. 8( a), the etching rate at the lower right side of the drawing is high in the in-plane distribution of the sample. This is caused by the eccentricity of the plasma at the lower right side due to the influence of magnetic fields. Next, the in-plane distribution of etching rate of the sample when a magnet is disposed on the outer circumference of the prior art plasma processing apparatus is shown inFIG. 8( b). As a result of etching rate measurement performed by disposing a north pole and a south pole of a magnet (0.4 mT) at areas shown inFIG. 8( b), the portion where etching rate was high has moved to the upper right side of the sample. This is caused by the distribution of the induction magnetic field being varied by disposing the magnet. Further, as mentioned above, the position of eccentricity of plasma diffused above thesample 2 can be estimated based on the result of in-plane etching rate distribution of the sample when magnetic fields are generated at various locations. By disposing theconductor ring 12 to correspond to the estimated result of eccentricity position, the eccentricity of plasma diffused on thesample 2 can be improved. Next, as shown inFIG. 8( c), according to the in-plane distribution of etching rate of the sample to which the present invention is applied, the eccentricity ratio of the plasma has been improved from 8.6% to 2.7%, and along therewith, the in-plane uniformity of etching rate of the sample has been improved from 8.3% to 5.8%. - The present embodiment has been illustrated based on an example in which the location of eccentricity of the plasma diffused above the sample has been estimated based on the measurement of in-plane distribution of etching rate of the sample, but the estimation of location of eccentricity of the plasma diffused above the sample can also be performed based for example on ion current flux measurement or plasma density distribution measurement using probes.
- As described above, the plasma processing apparatus according to the present invention provides an eccentricity correction means for generating a plasma capable of correcting the eccentricity of plasma diffused above the sample, thereby improving the eccentricity of plasma diffused above the sample caused by the influence of magnetic fields or by the eccentricity of vacuum within the plasma processing chamber.
Claims (3)
1. A plasma processing apparatus comprising:
a vacuum processing chamber in which a sample is processed via plasma;
a gas supply means for supplying gas into the vacuum processing chamber;
a sample stage disposed within the vacuum processing chamber on which the sample is placed;
an induction coil disposed outside the vacuum processing chamber;
a radio frequency power supply for supplying radio frequency power to the induction coil;
a Faraday shield being capacitively coupled with the plasma; and
an eccentricity correction means disposed between the induction coil and a dielectric sealing window constituting an upper surface of the vacuum processing chamber, wherein the eccentricity correction means generates a plasma capable of correcting the eccentricity of the plasma.
2. The plasma processing apparatus according to claim 1 , wherein
the eccentricity correction means comprises a conductor plate, wherein the conductor plate is in conduction with the Faraday shield.
3. The plasma processing apparatus according to claim 1 , wherein
the eccentricity correction means comprises a ring-shaped conductor, wherein the ring-shaped conductor is in conduction with the Faraday shield.
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JP2010269875A JP5639866B2 (en) | 2010-12-03 | 2010-12-03 | Plasma processing equipment |
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Cited By (3)
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US20120322270A1 (en) * | 2011-06-15 | 2012-12-20 | Lam Research Corporation | Powered grid for plasma chamber |
US20170330769A1 (en) * | 2014-11-26 | 2017-11-16 | Beijing Naura Microelectronics Equipment Co., Ltd. | Precleaning chamber and plasma processing apparatus |
TWI655882B (en) * | 2016-12-30 | 2019-04-01 | 中微半導體設備(上海)有限公司 | Inductively coupled plasma processing device |
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JP2016082180A (en) * | 2014-10-22 | 2016-05-16 | 株式会社日立ハイテクノロジーズ | Plasma processing apparatus |
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US5234529A (en) * | 1991-10-10 | 1993-08-10 | Johnson Wayne L | Plasma generating apparatus employing capacitive shielding and process for using such apparatus |
US20040163595A1 (en) * | 2003-02-26 | 2004-08-26 | Manabu Edamura | Plasma processing apparatus |
US6842147B2 (en) * | 2002-07-22 | 2005-01-11 | Lam Research Corporation | Method and apparatus for producing uniform processing rates |
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JP2002151481A (en) * | 2000-08-30 | 2002-05-24 | Samco International Inc | Plasma processing apparatus and plasma processing method |
JP2004134495A (en) * | 2002-10-09 | 2004-04-30 | Fasl Japan Ltd | Plasma processing apparatus |
JP5072066B2 (en) * | 2006-10-16 | 2012-11-14 | 株式会社アルバック | Plasma forming method |
-
2010
- 2010-12-03 JP JP2010269875A patent/JP5639866B2/en active Active
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US5234529A (en) * | 1991-10-10 | 1993-08-10 | Johnson Wayne L | Plasma generating apparatus employing capacitive shielding and process for using such apparatus |
US6842147B2 (en) * | 2002-07-22 | 2005-01-11 | Lam Research Corporation | Method and apparatus for producing uniform processing rates |
US20040163595A1 (en) * | 2003-02-26 | 2004-08-26 | Manabu Edamura | Plasma processing apparatus |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120322270A1 (en) * | 2011-06-15 | 2012-12-20 | Lam Research Corporation | Powered grid for plasma chamber |
US9966236B2 (en) * | 2011-06-15 | 2018-05-08 | Lam Research Corporation | Powered grid for plasma chamber |
US20170330769A1 (en) * | 2014-11-26 | 2017-11-16 | Beijing Naura Microelectronics Equipment Co., Ltd. | Precleaning chamber and plasma processing apparatus |
US10622224B2 (en) * | 2014-11-26 | 2020-04-14 | Beijing Naura Microelectronics Equipment Co., Ltd. | Precleaning chamber and plasma processing apparatus |
TWI655882B (en) * | 2016-12-30 | 2019-04-01 | 中微半導體設備(上海)有限公司 | Inductively coupled plasma processing device |
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JP5639866B2 (en) | 2014-12-10 |
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