US20040017565A1 - Glow discharge emission spectroscopic analysis apparatus - Google Patents
Glow discharge emission spectroscopic analysis apparatus Download PDFInfo
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- US20040017565A1 US20040017565A1 US10/628,727 US62872703A US2004017565A1 US 20040017565 A1 US20040017565 A1 US 20040017565A1 US 62872703 A US62872703 A US 62872703A US 2004017565 A1 US2004017565 A1 US 2004017565A1
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- 238000004611 spectroscopical analysis Methods 0.000 title claims abstract description 26
- 239000004020 conductor Substances 0.000 claims abstract description 134
- 239000004065 semiconductor Substances 0.000 claims description 129
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- 238000004458 analytical method Methods 0.000 abstract description 9
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- -1 argon ions Chemical class 0.000 description 4
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 230000005283 ground state Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 2
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- 238000001336 glow discharge atomic emission spectroscopy Methods 0.000 description 1
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Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/66—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
- G01N21/67—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence using electric arcs or discharges
Definitions
- the present invention relates to a glow discharge emission spectroscopic analysis apparatus, wherein a sample is arranged so as to face an anode of a glow discharge tube, an inert gas is supplied to the sample surface under low pressure and a glow discharge is emitted by applying a high-frequency voltage or a DC voltage between the sample and the anode so that a discharge emission can be analyzed and more specifically to an improvement in mounting and applying a potential voltage to a sample, such as a large semiconductor wafer.
- a glow discharge emission spectroscopic analysis apparatus is a high-frequency glow discharge emission spectroscopic analysis apparatus which can be utilized for chemical analysis of conductor, non-conductor and a semiconductor materials. With such an apparatus, sputtering and atomic emissions are combined for analyzing bulk solids and depth profiling surfaces and coatings.
- the present invention provides a glow discharge emission spectroscopic analysis apparatus which is capable of making a desired chemical analysis with excellent reproducibility.
- a glow discharge emission spectroscopic analysis apparatus where a sample is arranged so as to face an anode of a glow discharge tube provided in a Faraday cage, and an inert gas is supplied to the sample surface under a low pressure, and a glow discharge is emitted by applying a high-frequency voltage or a DC voltage between the sample and anode so that the discharge emission can be analyzed, the sample is maintained at the same potential as that of a negative electrode of the high frequency voltage or DC voltage provided on one of a front surface and a back surface of the sample excluding the sputtered position.
- the sample can be held by a first electrical conductor provided on one side of the glow discharge tube and second electrical conductor which is capable of being close to or separated from the first electrical conductor, and both the electrical conductors are electrically connected with each other when the sample is mounted so that a negative electric potential is provided to both of the electrical conductors.
- the sample is sandwiched between the first electrical conductor and the second electrical conductors. As a result, a voltage is applied to the sample uniformly, and the intensity of the discharge emission becomes stable, and thus desired and stable analyzed results can be obtained.
- the first electrical conductor is provided to one end of the glow discharge tube, whereas the second electrical conductor is movable by a cylinder rod so that the sample can be held between both the electrical conductors.
- the sample can be held simply and securely in a predetermined posture.
- the present invention can be provided to measure the properties of semiconductor wafers of a large size and the first and second electrical conductors can be designed to carefully hold the semiconductor wafer without exerting undue stress, while also providing a uniform application of voltage to both sides of the semiconductor wafer.
- An electrical conducting wiper can be provided to interconnect the first and second electrical conductors when they are closed on the semiconductor wafer for positioning the semiconductor wafer in a sealing relationship as a cathode in the glow discharge apparatus.
- FIG. 1 is a drawing schematically showing a schematic structure of a glow discharge emission spectroscopic analysis apparatus of the present invention related to a first embodiment
- FIG. 2 is a cross-sectional view showing a main section of the above glow discharge emission spectroscopic analysis apparatus
- FIG. 3 is a perspective schematic view showing a the structure of a glow discharge emission spectroscopic analysis apparatus of the present invention related to the second embodiment for measuring semiconductor wafers, and more specifically a perspective view showing a Faraday cage;
- FIG. 4 is a cross-sectional schematic view showing a structure of a Faraday cage and the movable electrical conducting and holding members;
- FIG. 5 is a sectional view showing a structure of a vicinity of a glow discharge tube related to a second embodiment of the present invention
- FIG. 6 is an enlarged perspective view showing a main section of a mechanism for holding a sample for the glow discharge tube in the second embodiment.
- FIGS. 7A, 7B, and 7 C are schematic drawings for explaining the problem found by the present inventors
- the inventors of the present invention conceived of using a glow discharge emission spectroscope analysis to large size semiconductor wafers in a production environment and initially arranged for a sample of a semiconductor wafer to face an anode of a glow discharge tube.
- An inert gas was applied to the sample surface under a low pressure and a glow discharge was emitted by applying a high-frequency voltage between semiconductor wafer and the anode so as to analyze the discharge emission.
- scattering of analyzed data between a center portion and an outer peripheral portion of the semiconductor wafer surface surpassed the expected estimate of the inventors to create a problem.
- scattering of the analyzed data according to various forms of other semiconductor wafers was also found to surpass the expected result, thereby indicating that the glow discharge analysis may not be dependable.
- FIG. 7(A) shows a state wherein a voltage is applied to a semiconductor wafer, and more specifically shows a semiconductor wafer W adjacent to an anode A side of a glow discharge tube L provided in a Faraday cage F so that the center of the semiconductor wafer W coincides with the center of the anode A.
- a cathode K is brought into contact with the semiconductor wafer W so as to coincide with the center of the semiconductor wafer W, and a high-frequency power source HF is connected between the anode A and the cathode K.
- FIG. 7(B) is a drawing showing a planar relationship between the semiconductor wafer W and the cathode K in the state of FIG. 7(A).
- FIG. 7(C) is a drawing showing another planar relationship between the semiconductor wafer W and the cathode K, when K is off center.
- the semiconductor wafer W is composed of ring bands Z 1 , Z 2 and Z 3 , and the impedances of the ring bands are respectively Z 1 , Z 2 and Z 3 .
- the impedance Z t viewed from the cathode K is represented by the following equation (1).
- the semiconductor wafer W is composed of ring bands Z 1 ′, Z 2 ′Z 3 ′, Z 4 ′ and Z 5 ′.
- the impedance Z t ′ viewed from the cathode K is represented by the following equation (2).
- a i is a resistance component for generating a voltage due to an electric current in an emission direction in the ring band
- 1/jb i is a value relating to a capacitance coupling with the Faraday cage F of the ring band.
- the impedance of the semiconductor wafer W is represented by ⁇ Z 1 .
- FIGS. 1 and 2 show a first embodiment of the present invention to resolve the above problem.
- 1 is a metallic Faraday cage, and a glow discharge tube 2 is provided in the Faraday cage 1 .
- 3 is a lamp body, and a discharge emission chamber 4 which broadens towards it bottom opening is formed therein.
- Vacuum ports 5 and 6 are formed in the lamp body 3 , and they are connected with a vacuum pump, not shown.
- 7 is a port for introducing an inert gas, appropriate for a sputtering plasma, such as argon gas.
- An end on the broaden opening side of the discharge emission chamber 4 is sealed by a window 8 made of magnesium fluoride or the like, and light 9 which is generated due to a discharge, to be mentioned later, is introduced in a direction of a spectroscope.
- an anode 11 having a cylindrical open portion 10 at its center is attached to the other end of the lamp body 3 which faces the window 8 by an anode holder 12 and a supporting body 13 made of, for example, ceramics so as to render airtight the lamp body 3 .
- a through hole 14 into which the cylinder section 10 is inserted is formed in the anode holder 12 , and a cylinder section 15 where the through hole 14 is formed is slightly projected from an upper surface of the supporting body 13 so that its peripheral portion is held by the supporting body 13 .
- the discharge emission chamber 4 on the anode 11 side is opened, but this opening is sealed by a surface of the semiconductor wafer 18 to be sputtered.
- the two conductors 16 , 17 can mount and hold the wafer 18 .
- 19 , 20 and 21 are sealing members, such as O-rings.
- the conductors 16 , 17 comprising copper plates of proper thickness, are conductors (hereinafter first conductor 16 and second conductor 17 ) for grasping the semiconductors wafer 18 and have an outer size larger than the semiconductor wafer 18 .
- the first conductor 16 which is closer to the anode 11 has a hole 22 into which the anode holder or pressing member 12 can fit. As can be determined later, the first conductor 16 can be connected electrically with a second conductor 17 so that they become mutually the same in electrical potential.
- Reference number 23 is a pressing member such as piston block or the like, which presses the rear face of the second conductor 17 when it cooperates with the first conductor 16 and grasps the semiconductor wafer 18 .
- the pressing member 23 is connected with a negative pole if a high frequency power 24 is provided externally of the Faraday cage 1 through a conductor 25 .
- reference numeral 26 is, for example, a plane copper plate which acts as an earth conductor when positioned close to the semiconductor wafer 18 and is also positioned so as to be parallel to it.
- the wafer 18 is grasped by the two conductors 16 and 17 as shown in FIG. 1 and FIG. 2.
- the semiconductor wafer 18 is positioned to face the anode of the glow discharge tube 2 , by pressing the second conductor 17 in the glow discharge tube 2 direction with the pressing member 23 .
- a negative voltage is applied from a high-frequency power source 24 to the pressing member 23 in a state that the discharge emission chamber 4 provided in the glow discharge tube 2 is in an atmosphere of argon gas
- a predetermined voltage is applied to the entire face of the semiconductor wafer 18 via the first electrical conductor 16 and the second electrical conductor 17 .
- a discharge is generated, and argon ions are created based on the discharge, and the argon ions are accelerated by a high electric field so as to collide against the surface of the semiconductor wafer 18 which is the cathode, and is thereby subject to a predetermined sputtering process.
- the sputtered particles (atom, molecule and ion) are excited in the plasma, and when the particles return to a ground state, a light emission which is peculiar to the particular elements in the wafer is executed.
- This emitted light is introduced in the direction of the spectroscope as a light represented by a reference numeral 9 in FIG. 1 and FIG. 2.
- the semiconductor wafer 18 as the sample to be analyzed is held by the first electrical conductor 16 and the second electrical conductor 17 , the semiconductor wafer 18 can be held securely in a predetermined state.
- the first electrical conductor 16 and the second electrical conductor 17 have equal or almost equal voltages, and both the electrical conductors 16 and 17 come close to the entire surface of the semiconductor wafer 18 on both faces.
- a predetermined voltage can be applied to the whole surface of the semiconductor wafer 18 , and the applying of a voltage to the semiconductor wafer 18 can be executed very simply and stably.
- FIG. 3 31 is an apparatus main body containing a spectroscope, such as a polychrometer and monochrometer for analyzing a discharge emission generated in a glow discharge tube (mentioned later), and a power source section and the like.
- a spectroscope such as a polychrometer and monochrometer for analyzing a discharge emission generated in a glow discharge tube (mentioned later)
- This structure has been designed to accommodate thin flat discs, such as semiconductor wafers.
- a Faraday cage 32 is provided on the front side of the apparatus main body 31 .
- the Faraday cage 32 is made of a metallic cylinder fixed to a bracket member 33 connected with the apparatus main body 31 .
- the Faraday cage 32 is composed of a cylindrical first cage section 35 which is provided with a flange 34 and is made of metal, and a second cage section 37 , which is provided so as to contact with or be separate from the first cage section 35 , has a flange 36 at its one end, and is made of a metallic cylinder in which the other end is closed.
- 38 is an air cylinder whose one end is fixed to a side surface of the closed side of the second cage section 37 , and a forward end of a piston rod 39 is coupled to a stanchion 40 which stands in a vertical direction in FIG. 4.
- the second cage section 37 slides in the direction of an arrow U or V by expansion and contraction of the piston rod 39 so that the flange 23 of the first cage section 35 and the flange 36 of the second cage section 37 closely contact with each other or are separated from each other by a predetermined gap.
- 41 is a guide member. Accordingly, the housing structure of components 37 and 36 can be opened and closed to provide access for loading semiconductor wafers.
- a glow discharge tube 42 and a sample holding mechanism 44 , which holds a sample 43 to be analyzed (for example, semiconductor wafer) to one end of the glow discharge tube 42 and applies a predetermined voltage to the sample 43 , are provided.
- a sample 43 to be analyzed for example, semiconductor wafer
- FIG. 5 is a lamp body, and a discharge emission chamber 46 which broadens towards its bottom opening is formed therein.
- Vacuum ports 47 and 48 are formed in the lamp body 45 , and they are connected with a vacuum pump, not shown.
- 49 is a port for introducing an inert gas such as argon gas.
- an anode 53 having a cylindrical portion 52 at its center is attached to the other end which faces the window 50 by an anode holder 54 and a supporting body 55 made of, for example, ceramics so as to make airtight the lamp body 45 .
- a through hole 56 into which the cylinder section 57 , where the through hole 56 is formed, is slightly projected from an upper surface of the supporting body 55 so that its peripheral portion is held by the supporting body 55 .
- the discharge emission chamber 46 on the anode 53 is opened, but this opening is sealed by a surface of the semiconductor wafer 43 to be sputtered and held by the sample holding mechanism 44 , mentioned later.
- 58 , 59 and 60 are sealing members, such as O-rings.
- the sample holding mechanism 44 is provided to the anode 53 side of the glow discharge tube 42 .
- First, 61 is a first electrical conductor provided fixedly to the discharge tube 42 , and it will sandwich the semiconductor wafer 43 with the cooperation on a second electrical conductor 41 , mentioned later, so as to cover its whole surface, and it can apply a predetermined voltage to the semiconductor wafer 43 .
- the first electrical conductor 61 as well as the second electrical conductor 41 wil serve as a cathode for the discharge tube 42 .
- the first electrical conductor 61 is made of a copper plate having a thickness of about 3mm, for example, and is composed of a rectangular main body section 62 whose four corners are chamfered and two mounting sections 63 .
- the main body section 62 and the mounting sections 63 whose size is at least larger than a maximum size of the semiconductor wafer 43 are coupled to each other by an elastic connecting plate 64 so that their rear faces (glow discharge tube 42 side) are flush with each other (there is no stepped portion) and will have an elastic structure to accommodate variances in the dimensions of the wafer 43 .
- a hole 65 which can house the supporting body 55 on the glow discharge tube 42 side is formed in the main body section 62 , and an elastic and electrically conductive section 66 , such as a wiper member, is provided for setting the voltages of the second electrical conductor 71 and the first electrical conductor 61 to be equal with each other.
- the wiper member 66 is projected from a suitable position of one side surface (surface opposite to the second electrical conductor 71 , sandwich surface) 62 a of the main body section 62 , and a voltage apply section 68 , connected with the high-frequency power source (not shown) via a cable 67 , is provided on the other side surface.
- the mounting sections 63 are held by insulating holding sections 70 (see FIG. 4) provided in midways of stanchions 69 which are held to the bracket member 33 (see FIG. 4) in a horizontal direction, and thus the first electrical conductor 61 is fixedly provided to the anode 53 of the glow discharge tube 42 so that its plane, particularly a sandwich surface represented by a reference symbol 62 a (see FIGS. 4 and 6) is parallel with a vertical direction.
- edge portions of the main body section 62 and the mounting sections 63 are subject to a curve face process and chamfering process so that an edge portion, which could score the wafer 43 , is not generated.
- 71 is the second electrical conductor which is made of a copper plate of about 3 mm, for example, and it is provided so as to move linearly with respect to the fixed first electrical conductor 61 .
- the second electrical conductor 71 has the same form and size as those of the main body section 62 of the first electrical conductor 61 , but as shown in FIG. 5, it is composed of a small rectangular pressurizing section 72 which matches with the through hole 56 of the anode holder 54 (an area of the semiconductor wafer 43 to be analyzed is positioned here), and a main body section 73 of the pressurizing section 72 .
- the pressurizing section 72 is coupled to the main body section 73 by an elastic coupling plate 74 so that they are flush with each other (a stepped portion is not generated).
- the edge portion of the main body section 73 undergoes the curved face process and chamfering process so that an edge portion is not generated.
- 75 and 76 are air cylinders for moving the second electrical conductor 71 linearly, and their cylinder sections 75 a and 76 a are mounted to a mounting base 79 via spacers 78 which are held to a base member 77 mounted on the stanchions 69 .
- their piston rods 75 b and 76 b are constituted so as to be capable of expanding and contracting on the first electrical conductor 61 side through holes 80 opened in the base member 77 .
- connection blocks 81 and 82 provided on a side 71 b (mounted face side) of the second electrical conductor 71 opposite to a surface 71 a (see FIG. 4) for nipping or holding the pressurizing section 72 and the main body section 73 .
- 83 , 84 , and 85 are guide rods provided in the same direction as a direction where the air cylinders 75 and 76 are provided laterally.
- the guide rod 83 its base portion is fixed to the connection block 81 , which matches for the pressurizing section 72 of the second electrical conductor 71 , and is inserted through a guide section 86 provided to the mounting base 79 .
- the other two guide rods 84 and 85 their base portions are fixed to the main body section 72 of the second electrical conductor 71 , and are inserted through a guide section 87 and a guide section, not shown, provided to the mounting base 79 .
- the second electrical conductor 71 is held by the piston rods 75 b and 76 b of the two air cylinders 75 and 76 and the three guide rods 83 through 85 so as to be close to or separated from the first electrical conductor 61 , and the contacting face 71 a shield so as to be parallel with the contact face 62 a of the first electrical conductor 61 . Moreover, the second electrical conductor 71 holds the semiconductor wafer 43 in a vertical state by cooperation with the first electrical conductor 71 .
- a plate-shaped earth conductor 88 is provided in the Faraday cage 32 , and its voltage is maintained so as to be equal with the voltage of the Faraday cage 32 .
- the semiconductor wafer 43 to be analyzed is held between the electrical conductors 61 and 71 by a support loader or magic hand, not shown, in the state where the second electrical conductor 71 is separated from the first electrical conductor 61 .
- the piston rods 75 b and 76 b are extended in the direction of the arrow U.
- the semiconductor wafer 43 is pushed towards the direction of the first electrical conductor 61 so as to be nipped or securely held by the first electrical conductor 61 and the second electrical conductor 71 .
- the magic hand or loader positions the semiconductor wafer 43 so that the pressurizing section 72 in the second electrical conductor 71 matches with the through hole 56 where the anode 53 is provided.
- the semiconductor wafer 43 which is nipped by the first electrical conductor 61 and the second electrical conductor 71 is pressed against the anode holder 54 of the glow discharge tube 42 , and since the sealing member 60 is provided on the pressed face side of the anode holder 54 , the discharge emission chamber 46 of the glow discharge tube 42 is accordingly sealed by the surface of the semiconductor wafer 43 in an airtight manner.
- the area of the semiconductor wafer 43 to be analyzed faces the cylinder section 52 of the anode 53 which is positioned in the through hole 56 of the anode holder 54 .
- the main body section 73 of the second electrical conductor 71 contacts with the electrically conductive section 66 provided on the contact face 62 a side of the main body section 62 of the first electrical conductor 61 . Then, the voltage of the second electrical conductor 71 is made equal with the voltage of the first electrical conductor 61 so that the supporting contact area for the semiconductor wafer 43 is held at the same potential voltage.
- a high-frequency voltage is applied from a high-frequency power source (not shown) to the first electrical conductor 61 in a state that the discharge emission chamber 46 is in atmosphere of argon gas
- a predetermined voltage is applied to the entire front and back face of the semiconductor wafer 43 via the first electrical conductor 61 and the second electrical conductor 71 which will have an equal voltage level.
- a discharge is generated, and an argon ion is created based on the discharge, and the argon ion is accelerated by a high electric field so as to collide against the surface of the semiconductor wafer 43 which acts as the cathode, and is thereby subject to a predetermined sputtering process.
- the sputtered particles (atom, molecule and ion) that are released from the semiconductor wafer 43 are then excited in the plasma field, and when the particles again return to a ground state, their characteristic wavelength emission is peculiar to the elements in the wafer 43 .
- This emitted light is introduced in the direction of the spectroscope in the apparatus main body 31 as a light represented by a reference numeral 43 in FIG. 5.
- determining the depth of etch or sputtering a profile as the elements in the wafer can be determined for not only the surface, but for controlled distances into the body of the wafer.
- the semiconductor wafer 43 can be held securely in a predetermined state.
- the first electrical conductor 61 and the second electrical conductor 71 have equal voltages, and both the electrical conductors 61 and 71 come close to each surface of the semiconductor wafer 43 .
- a predetermined voltage can be applied to the entire surface of the semiconductor wafer 43 , and the applying of a voltage to the semiconductor wafer 43 can be executed very simply and stably.
- a voltage from the high-frequency power source is applied to the fixed first electrical conductor 61 , it is not necessary to install a power source cable, and thus installation of other components can be designed easily.
- the fixed first electrical conductor 61 is composed of the main body section 62 and the mounting sections 63 , they are coupled with each other by the elastic coupling plate 64 so as to be flush with each other (no stepped portion is obtained), and thus the first electrical conductor 61 has an elastic structure.
- the first electrical conductor 61 can absorb or adjust for the distortion and warpage, and can still hold the semiconductor wafer 43 in the desired position in cooperation with the second electrical conductor 71 .
- the movable second electrical conductor 71 is composed of the pressurizing section 72 for pressurizing the area of the semiconductor wafer 43 to be analyzed and the main body section 73 , has an elastic structure, and the pressing section 72 and the main body section 73 are pressurized respectively by individual piston rods 75 b and 76 b.
- a pressurizing force of the piston rods 75 b to the pressurizing section 72 is set to be larger than a pressurizing force of the piston rod 76 b to the main body section 73 , the portion of the semiconductor wafer 43 including the area to be analyzed can be pressed strongly against the anode holder 54 , and thus a predetermined airtightness can be maintained.
- the second electrical conductor 71 is driven by the two air cylinders 75 and 76 , but the present invention is not limited to this structure, and thus it may be driven by one air cylinder or by other hydraulic and electrical motive forces.
- the semiconductor wafer 43 is used as a sample, but the present invention is not limited to this, and thus, conductors such as metal, non-conductors and semiconductors such as various insulating material including ceramics can be used for analysis. Further, when the sample is a conductor, it is needless to say that a DC voltage may be applied thereto instead of a high-frequency voltage.
- the second embodiment of the glow discharge emission spectroscopic analysis apparatus is arranged so that the sample 43 is sandwiched between the first electrical conductor 61 s and the second electrical conductor 71 and a negative electric potential is given to one of them, a voltage is applied to the sample 43 uniformly, and the intensity of the discharge emission becomes stable. As a result, a desired and stable analyzed result can be obtained. Therefore, the desired chemical analysis may be made with excellent reproducibility.
Abstract
This invention provides a glow discharge emission spectroscopic analysis apparatus which is capable of making a desired chemical analysis with excellent reproducibility. A glow discharge emission spectroscopic analysis apparatus of this invention is constituted so that the sample is held by a first electrical conductor provided on one side of a glow discharge tube and a second electrical conductor is movable by a cylinder rod to secure the sample in contact with the first electrical conductor. The electrical conductors can be electrically connected with each other. when the sample is secured, and a negative electric potential is applied to the electrical conductors.
Description
- This is a divisional application of U.S. patent application Ser. No. 09/376,164 filed on Aug. 17, 1999.
- 1. Field of the Invention
- The present invention relates to a glow discharge emission spectroscopic analysis apparatus, wherein a sample is arranged so as to face an anode of a glow discharge tube, an inert gas is supplied to the sample surface under low pressure and a glow discharge is emitted by applying a high-frequency voltage or a DC voltage between the sample and the anode so that a discharge emission can be analyzed and more specifically to an improvement in mounting and applying a potential voltage to a sample, such as a large semiconductor wafer.
- 2. Description of Related Art
- One example of a glow discharge emission spectroscopic analysis apparatus is a high-frequency glow discharge emission spectroscopic analysis apparatus which can be utilized for chemical analysis of conductor, non-conductor and a semiconductor materials. With such an apparatus, sputtering and atomic emissions are combined for analyzing bulk solids and depth profiling surfaces and coatings.
- According to recent developments in semiconductor techniques, the diameter of a semiconductor wafers such as silicon wafers used in manufacturing semiconductor circuit chips have become larger and the spacing between circuit paths have decreased so that minute impurities can impair the production of such products.
- Thus, the prior art is seeking to find apparatus and procedures to precisely measure the properties of large semiconductor wafers.
- The present invention provides a glow discharge emission spectroscopic analysis apparatus which is capable of making a desired chemical analysis with excellent reproducibility.
- In order to achieve the above object, according to the present invention, in a glow discharge emission spectroscopic analysis apparatus, where a sample is arranged so as to face an anode of a glow discharge tube provided in a Faraday cage, and an inert gas is supplied to the sample surface under a low pressure, and a glow discharge is emitted by applying a high-frequency voltage or a DC voltage between the sample and anode so that the discharge emission can be analyzed, the sample is maintained at the same potential as that of a negative electrode of the high frequency voltage or DC voltage provided on one of a front surface and a back surface of the sample excluding the sputtered position.
- In the glow discharge emission spectroscopic analysis apparatus having the above structure, a voltage is applied to the sample uniformly, and intensity of the discharge emission becomes stable, and thus desired and stable analyzed results can be obtained.
- In one embodiment, the sample can be held by a first electrical conductor provided on one side of the glow discharge tube and second electrical conductor which is capable of being close to or separated from the first electrical conductor, and both the electrical conductors are electrically connected with each other when the sample is mounted so that a negative electric potential is provided to both of the electrical conductors.
- In the glow discharge emission spectroscopic analysis apparatus having the above structure, the sample is sandwiched between the first electrical conductor and the second electrical conductors. As a result, a voltage is applied to the sample uniformly, and the intensity of the discharge emission becomes stable, and thus desired and stable analyzed results can be obtained.
- Further, in the glow discharge emission spectroscopic analysis apparatus, the first electrical conductor is provided to one end of the glow discharge tube, whereas the second electrical conductor is movable by a cylinder rod so that the sample can be held between both the electrical conductors. As a result, the sample can be held simply and securely in a predetermined posture.
- The present invention can be provided to measure the properties of semiconductor wafers of a large size and the first and second electrical conductors can be designed to carefully hold the semiconductor wafer without exerting undue stress, while also providing a uniform application of voltage to both sides of the semiconductor wafer. An electrical conducting wiper can be provided to interconnect the first and second electrical conductors when they are closed on the semiconductor wafer for positioning the semiconductor wafer in a sealing relationship as a cathode in the glow discharge apparatus.
- The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings.
- FIG. 1 is a drawing schematically showing a schematic structure of a glow discharge emission spectroscopic analysis apparatus of the present invention related to a first embodiment;
- FIG. 2 is a cross-sectional view showing a main section of the above glow discharge emission spectroscopic analysis apparatus;
- FIG. 3 is a perspective schematic view showing a the structure of a glow discharge emission spectroscopic analysis apparatus of the present invention related to the second embodiment for measuring semiconductor wafers, and more specifically a perspective view showing a Faraday cage;
- FIG. 4 is a cross-sectional schematic view showing a structure of a Faraday cage and the movable electrical conducting and holding members;
- FIG. 5 is a sectional view showing a structure of a vicinity of a glow discharge tube related to a second embodiment of the present invention;
- FIG. 6 is an enlarged perspective view showing a main section of a mechanism for holding a sample for the glow discharge tube in the second embodiment; and
- FIGS. 7A, 7B, and7C are schematic drawings for explaining the problem found by the present inventors
- The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventors of carrying out their invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide a glow discharge emission spectroscopic analysis apparatus for measuring the properties of samples, such as semiconductor wafers.
- The inventors of the present invention conceived of using a glow discharge emission spectroscope analysis to large size semiconductor wafers in a production environment and initially arranged for a sample of a semiconductor wafer to face an anode of a glow discharge tube. An inert gas was applied to the sample surface under a low pressure and a glow discharge was emitted by applying a high-frequency voltage between semiconductor wafer and the anode so as to analyze the discharge emission. However, scattering of analyzed data between a center portion and an outer peripheral portion of the semiconductor wafer surface surpassed the expected estimate of the inventors to create a problem. Moreover, scattering of the analyzed data according to various forms of other semiconductor wafers was also found to surpass the expected result, thereby indicating that the glow discharge analysis may not be dependable.
- The inventors then examined their experimental results and came to a conclusion that the scattering was mainly caused by a state of coupling to a Faraday cage in portions other than the portion to which a high-frequency voltage was applied even if the same semiconductor wafer was used. This point will be described below with reference to FIG. 7.
- FIG. 7(A) shows a state wherein a voltage is applied to a semiconductor wafer, and more specifically shows a semiconductor wafer W adjacent to an anode A side of a glow discharge tube L provided in a Faraday cage F so that the center of the semiconductor wafer W coincides with the center of the anode A. A cathode K is brought into contact with the semiconductor wafer W so as to coincide with the center of the semiconductor wafer W, and a high-frequency power source HF is connected between the anode A and the cathode K. FIG. 7(B) is a drawing showing a planar relationship between the semiconductor wafer W and the cathode K in the state of FIG. 7(A). Moreover, FIG. 7(C) is a drawing showing another planar relationship between the semiconductor wafer W and the cathode K, when K is off center.
- As shown in FIG. 7(B), when the cathode K is brought into contact with the semiconductor wafer W so as to coincide with the center of the semiconductor wafer W, the semiconductor wafer W is composed of ring bands Z1, Z2 and Z3, and the impedances of the ring bands are respectively Z1, Z2 and Z3. In this case, the impedance Zt viewed from the cathode K is represented by the following equation (1).
- Zt=Z1, Z2 and Z3 (1)
- In addition, as shown in FIG. 7(C), when the cathode K is brought into contact with a peripheral portion of the semiconductor wafer W, the semiconductor wafer W is composed of ring bands Z1′, Z2′Z3′, Z4′ and Z5′. In this case, the impedance Zt′ viewed from the cathode K is represented by the following equation (2).
- Z t ′=Z 1 ′+Z 2 ′+Z 3 ′+Z 4 ′+Z 5′ (2)
- The impedance Zt of an arbitrary ring band is represented by the following equation (3).
- Z i =a i+1/jb i (3)
- Here, ai is a resistance component for generating a voltage due to an electric current in an emission direction in the ring band, and 1/jbi is a value relating to a capacitance coupling with the Faraday cage F of the ring band. In general, the impedance of the semiconductor wafer W is represented by ΣZ1.
- According to the above equations (1) through (3), it is clear that the Zt is different from Zt′, and even if equal electric power is supplied to the semiconductor wafer W via the cathode K, the intensity of the discharge emission generated at this time varies, and thus analyzed results are different from each other.
- The operation of a spectroscope, such as polychromator and monochromator systems, are known, see Glow Discharge Optical Emission Spectrometry by Payling et al., pages 20-23, pages 130-137, Wiley & Sons, Ltd. 1997.
- The inventors consider that the above-mentioned problem is caused not only in the semiconductor wafer but also in a conductor, non-conductor and the like.
- FIGS. 1 and 2 show a first embodiment of the present invention to resolve the above problem. At first, in FIG. 1, 1 is a metallic Faraday cage, and a
glow discharge tube 2 is provided in the Faradaycage 1. There will be described below the structure of theglow discharge tube 2 and its periphery with reference to FIG. 2. 3 is a lamp body, and adischarge emission chamber 4 which broadens towards it bottom opening is formed therein.Vacuum ports lamp body 3, and they are connected with a vacuum pump, not shown. Moreover, 7 is a port for introducing an inert gas, appropriate for a sputtering plasma, such as argon gas. - An end on the broaden opening side of the
discharge emission chamber 4 is sealed by awindow 8 made of magnesium fluoride or the like, and light 9 which is generated due to a discharge, to be mentioned later, is introduced in a direction of a spectroscope. Moreover, ananode 11 having a cylindricalopen portion 10 at its center is attached to the other end of thelamp body 3 which faces thewindow 8 by an anode holder 12 and a supportingbody 13 made of, for example, ceramics so as to render airtight thelamp body 3. A through hole 14 into which thecylinder section 10 is inserted is formed in the anode holder 12, and a cylinder section 15 where the through hole 14 is formed is slightly projected from an upper surface of the supportingbody 13 so that its peripheral portion is held by the supportingbody 13. As mentioned above, thedischarge emission chamber 4 on theanode 11 side is opened, but this opening is sealed by a surface of thesemiconductor wafer 18 to be sputtered. As will be described later, the twoconductors wafer 18. Here, 19, 20 and 21 are sealing members, such as O-rings. - The
conductors first conductor 16 and second conductor 17) for grasping thesemiconductors wafer 18 and have an outer size larger than thesemiconductor wafer 18. Thefirst conductor 16 which is closer to theanode 11 has ahole 22 into which the anode holder or pressing member 12 can fit. As can be determined later, thefirst conductor 16 can be connected electrically with asecond conductor 17 so that they become mutually the same in electrical potential. -
Reference number 23 is a pressing member such as piston block or the like, which presses the rear face of thesecond conductor 17 when it cooperates with thefirst conductor 16 and grasps thesemiconductor wafer 18. The pressingmember 23 is connected with a negative pole if ahigh frequency power 24 is provided externally of theFaraday cage 1 through aconductor 25. - Referring to FIG. 1,
reference numeral 26 is, for example, a plane copper plate which acts as an earth conductor when positioned close to thesemiconductor wafer 18 and is also positioned so as to be parallel to it. - In order to conduct a material analysis of the
semiconductor wafer 18 by using the glow discharge emission spectroscopic analysis apparatus, thewafer 18 is grasped by the twoconductors semiconductor wafer 18 is positioned to face the anode of theglow discharge tube 2, by pressing thesecond conductor 17 in theglow discharge tube 2 direction with the pressingmember 23. - When a negative voltage is applied from a high-
frequency power source 24 to the pressingmember 23 in a state that thedischarge emission chamber 4 provided in theglow discharge tube 2 is in an atmosphere of argon gas, a predetermined voltage is applied to the entire face of thesemiconductor wafer 18 via the firstelectrical conductor 16 and the secondelectrical conductor 17. As a result, a discharge is generated, and argon ions are created based on the discharge, and the argon ions are accelerated by a high electric field so as to collide against the surface of thesemiconductor wafer 18 which is the cathode, and is thereby subject to a predetermined sputtering process. The sputtered particles (atom, molecule and ion) are excited in the plasma, and when the particles return to a ground state, a light emission which is peculiar to the particular elements in the wafer is executed. This emitted light is introduced in the direction of the spectroscope as a light represented by areference numeral 9 in FIG. 1 and FIG. 2. - In the glow discharge emission spectroscopic analysis apparatus, since the
semiconductor wafer 18 as the sample to be analyzed is held by the firstelectrical conductor 16 and the secondelectrical conductor 17, thesemiconductor wafer 18 can be held securely in a predetermined state. In the held state, the firstelectrical conductor 16 and the secondelectrical conductor 17 have equal or almost equal voltages, and both theelectrical conductors semiconductor wafer 18 on both faces. As a result, only by applying a high-frequency voltage to the firstelectrical conductor 16, a predetermined voltage can be applied to the whole surface of thesemiconductor wafer 18, and the applying of a voltage to thesemiconductor wafer 18 can be executed very simply and stably. - When the
semiconductor wafer 18 was analyzed by using a glow discharge emission spectroscopic analysis apparatus, intensity of specified silicon wavelengths of 251 nm (secondary light), 288 nm (primary light) and 288 nm (secondary light) were examined. The results shown in the following TABLE 1 were obtained. In this measurement, a frequency of the high-frequency voltage was 13.56 MHz, an electric power was 50 W, and a pressure in theglow discharge tube 2 was maintained within 4 to 5 mhPa. - Changing parameters are:
- a. size of the semiconductor wafer18 (6 in or 8 in);
- b. position of the
semiconductor wafer 18; - c. existence/non-existence of the two
electrical conductors - d. distance from the
semiconductor 18 to theearth conductor 26.TABLE 1 Existence/ Dis- 251 288 288 Size non-existence of tance (2nd) (1st) (2nd) (inch) Position electrical conductors (cm) 1 806 800 33 6 Center Non-exist 21 2 578 570 28 8 Center Non-exist 21 3 234 232 11 8 Edge No- exist 21 4 1152 1130 45 8 Center Exist 21 5 1168 1157 46 8 Edge Exist 21 6 1154 1152 46 6 8 Edge 21 7 1089 1070 42 8 Edge Exist 11 8 851 835 33 8 Edge Exist 5 - The following is understood from TABLE 1. At first, in
measurement 1 throughmeasurement 3, a voltage was applied to thesemiconductor wafer 18 as shown in FIG. 7(A) without using the firstelectrical conductor 16 and the secondelectrical conductor 17. Inmeasurement semiconductor wafer 18 differed from each other, and as the size of thesemiconductor wafer 18 was smaller, the emission intensity was stronger. - In
measurement 2 andmeasurement 3, the sizes of thesemiconductor wafer 18 were equal to each other, but the center of thesemiconductor wafer 18 was measured inmeasurement 2, and a portion close to the edge of thesemiconductor wafer 18 was measured inmeasurement 3. The emission intensity was stronger in the center of thesemiconductor wafer 18. - Next, in
measurement 4 throughmeasurement 8, thesemiconductor wafer 18 was sandwiched between the firstelectrical conductor 16 and the secondelectrical conductor 17 and in this state a voltage was applied to thesemiconductor wafer 18.Measurement 4 andmeasurement 5 are different from each other only in that the measuring position of thesemiconductor wafer 18 is its center or edge, and the other conditions were not different from each other. A difference in the intensity between respective wavelengths was hardly recognized. - In
measurement 5 andmeasurement 6, the centers of thesemiconductor wafers 18 with different sizes were measured, and the other conditions were not different from each other. A difference in the intensity between respective wavelengths was also hardly recognized. - In
measurement semiconductor wafer 18 to theearth conductor 26 differed from each other. Even if the firstelectrical conductor 17 held thesemiconductor wafer 18 so as to cover it, as the distance between thesemiconductor wafer 18 and theearth conductor 26 becomes shorter, the emission intensity is reduced. It is considered that this result occurs because the earth condition of theearth conductor 26 is incomplete at a high frequency and an electric power loss occurs, and thus the loss depends on the distance between theearth conductor 26 and thesemiconductor wafer 18 so that the emission intensity changes. Moreover, it is also considered that when capacitive coupling between the firstelectrical conductor 16 and the secondelectrical conductor 17 and theearth conductor 26 exceeds a fixed amount, an energy for emission is reduced. - Although the same measurement was conducted in a condition where a conductor was adhered on either face of the
semiconductor wafer 18 continuous to the above described measurement, no difference was recognized between the measurement results in either case. Namely, when thefirst conductor 16 is adhered only on the sputter face side of thesemiconductor 18, and when the reverse face of thesemiconductor wafer 18 is covered with theconductor 17 in a condition that the sputtered front face is exposed the same result is obtained as when thesemiconductor wafer 18 is covered with the twoconductors semiconductor wafer 18 is retained at the same potential, the load is almost retained constant and it is not affected by the size of thesemiconductor wafer 18 and the location of the voltage application. - There will be described below a second embodiment of this invention with reference to FIGS. 3 through 6. At first, in FIG. 3, 31 is an apparatus main body containing a spectroscope, such as a polychrometer and monochrometer for analyzing a discharge emission generated in a glow discharge tube (mentioned later), and a power source section and the like. This structure has been designed to accommodate thin flat discs, such as semiconductor wafers. A
Faraday cage 32 is provided on the front side of the apparatusmain body 31. - As shown in FIG. 4, the
Faraday cage 32 is made of a metallic cylinder fixed to abracket member 33 connected with the apparatusmain body 31. TheFaraday cage 32 is composed of a cylindricalfirst cage section 35 which is provided with aflange 34 and is made of metal, and asecond cage section 37, which is provided so as to contact with or be separate from thefirst cage section 35, has aflange 36 at its one end, and is made of a metallic cylinder in which the other end is closed. 38 is an air cylinder whose one end is fixed to a side surface of the closed side of thesecond cage section 37, and a forward end of apiston rod 39 is coupled to astanchion 40 which stands in a vertical direction in FIG. 4. Thesecond cage section 37 slides in the direction of an arrow U or V by expansion and contraction of thepiston rod 39 so that theflange 23 of thefirst cage section 35 and theflange 36 of thesecond cage section 37 closely contact with each other or are separated from each other by a predetermined gap. Here, 41 is a guide member. Accordingly, the housing structure ofcomponents - In the
Faraday cage 32, aglow discharge tube 42, and asample holding mechanism 44, which holds asample 43 to be analyzed (for example, semiconductor wafer) to one end of theglow discharge tube 42 and applies a predetermined voltage to thesample 43, are provided. - At first, a description will be given as to the structure of the
glow discharge tube 42. In FIG. 5, 45 is a lamp body, and adischarge emission chamber 46 which broadens towards its bottom opening is formed therein.Vacuum ports lamp body 45, and they are connected with a vacuum pump, not shown. Moreover, 49 is a port for introducing an inert gas such as argon gas. - One end, on the broaden opening side of the
discharge emission chamber 46, is sealed by awindow 50 made of magnesium fluoride or the like, and any light 51 generated due to a discharge effect, mentioned later, is introduced in the direction of a spectroscope (not shown) in the apparatusmain body 31. Moreover, ananode 53 having acylindrical portion 52 at its center is attached to the other end which faces thewindow 50 by ananode holder 54 and a supportingbody 55 made of, for example, ceramics so as to make airtight thelamp body 45. A throughhole 56 into which thecylinder section 57, where the throughhole 56 is formed, is slightly projected from an upper surface of the supportingbody 55 so that its peripheral portion is held by the supportingbody 55. As mentioned above, thedischarge emission chamber 46 on theanode 53 is opened, but this opening is sealed by a surface of thesemiconductor wafer 43 to be sputtered and held by thesample holding mechanism 44, mentioned later. Here 58, 59 and 60 are sealing members, such as O-rings. - There will be described below the structure of the
mechanism 44 for holding thesemiconductor wafer 43 in a predetermined site also with reference to FIG. 6. Thesample holding mechanism 44 is provided to theanode 53 side of theglow discharge tube 42. First, 61 is a first electrical conductor provided fixedly to thedischarge tube 42, and it will sandwich thesemiconductor wafer 43 with the cooperation on a secondelectrical conductor 41, mentioned later, so as to cover its whole surface, and it can apply a predetermined voltage to thesemiconductor wafer 43. The firstelectrical conductor 61 as well as the secondelectrical conductor 41 wil serve as a cathode for thedischarge tube 42. The firstelectrical conductor 61 is made of a copper plate having a thickness of about 3mm, for example, and is composed of a rectangularmain body section 62 whose four corners are chamfered and two mountingsections 63. Themain body section 62 and the mountingsections 63 whose size is at least larger than a maximum size of thesemiconductor wafer 43 are coupled to each other by an elastic connectingplate 64 so that their rear faces (glow discharge tube 42 side) are flush with each other (there is no stepped portion) and will have an elastic structure to accommodate variances in the dimensions of thewafer 43. - A
hole 65 which can house the supportingbody 55 on theglow discharge tube 42 side is formed in themain body section 62, and an elastic and electricallyconductive section 66, such as a wiper member, is provided for setting the voltages of the secondelectrical conductor 71 and the firstelectrical conductor 61 to be equal with each other. Thewiper member 66 is projected from a suitable position of one side surface (surface opposite to the secondelectrical conductor 71, sandwich surface) 62 a of themain body section 62, and a voltage applysection 68, connected with the high-frequency power source (not shown) via acable 67, is provided on the other side surface. - In addition, the mounting
sections 63 are held by insulating holding sections 70 (see FIG. 4) provided in midways ofstanchions 69 which are held to the bracket member 33 (see FIG. 4) in a horizontal direction, and thus the firstelectrical conductor 61 is fixedly provided to theanode 53 of theglow discharge tube 42 so that its plane, particularly a sandwich surface represented by areference symbol 62 a (see FIGS. 4 and 6) is parallel with a vertical direction. - Here, the edge portions of the
main body section 62 and the mountingsections 63 are subject to a curve face process and chamfering process so that an edge portion, which could score thewafer 43, is not generated. -
electrical conductor 61. The secondelectrical conductor 71 has the same form and size as those of themain body section 62 of the firstelectrical conductor 61, but as shown in FIG. 5, it is composed of a smallrectangular pressurizing section 72 which matches with the throughhole 56 of the anode holder 54 (an area of thesemiconductor wafer 43 to be analyzed is positioned here), and amain body section 73 of the pressurizingsection 72. The pressurizingsection 72 is coupled to themain body section 73 by anelastic coupling plate 74 so that they are flush with each other (a stepped portion is not generated). Here, the edge portion of themain body section 73 undergoes the curved face process and chamfering process so that an edge portion is not generated. - There will be described below holding and moving mechanisms of the second
electrical conductor 71 with reference to FIGS. 4 and 6. In these drawings, 75 and 76 are air cylinders for moving the secondelectrical conductor 71 linearly, and theircylinder sections base 79 viaspacers 78 which are held to abase member 77 mounted on thestanchions 69. Moreover, theirpiston rods electrical conductor 61 side throughholes 80 opened in thebase member 77. The ends of thepiston rods side 71 b (mounted face side) of the secondelectrical conductor 71 opposite to asurface 71 a (see FIG. 4) for nipping or holding the pressurizingsection 72 and themain body section 73. -
air cylinders guide rod 83, its base portion is fixed to theconnection block 81, which matches for the pressurizingsection 72 of the secondelectrical conductor 71, and is inserted through aguide section 86 provided to the mountingbase 79. As for the other twoguide rods main body section 72 of the secondelectrical conductor 71, and are inserted through aguide section 87 and a guide section, not shown, provided to the mountingbase 79. - As mentioned above, the second
electrical conductor 71 is held by thepiston rods air cylinders guide rods 83 through 85 so as to be close to or separated from the firstelectrical conductor 61, and the contactingface 71 a shield so as to be parallel with thecontact face 62 a of the firstelectrical conductor 61. Moreover, the secondelectrical conductor 71 holds thesemiconductor wafer 43 in a vertical state by cooperation with the firstelectrical conductor 71. - Here, in FIG. 4, a plate-shaped
earth conductor 88 is provided in theFaraday cage 32, and its voltage is maintained so as to be equal with the voltage of theFaraday cage 32. - In the case where the material of the
semiconductor wafer 43 is to be analyzed by using the glow discharge emission spectroscopic analysis apparatus having the above structure, as shown in FIG. 4, thesemiconductor wafer 43 to be analyzed is held between theelectrical conductors electrical conductor 71 is separated from the firstelectrical conductor 61. When the twoair cylinders piston rods semiconductor wafer 43 is pushed towards the direction of the firstelectrical conductor 61 so as to be nipped or securely held by the firstelectrical conductor 61 and the secondelectrical conductor 71. In this case, since the desired position of thesemiconductor wafer 43 is previously known, the magic hand or loader positions thesemiconductor wafer 43 so that the pressurizingsection 72 in the secondelectrical conductor 71 matches with the throughhole 56 where theanode 53 is provided. - As mentioned above, the
semiconductor wafer 43 which is nipped by the firstelectrical conductor 61 and the secondelectrical conductor 71 is pressed against theanode holder 54 of theglow discharge tube 42, and since the sealingmember 60 is provided on the pressed face side of theanode holder 54, thedischarge emission chamber 46 of theglow discharge tube 42 is accordingly sealed by the surface of thesemiconductor wafer 43 in an airtight manner. The area of thesemiconductor wafer 43 to be analyzed (area to be sputtered) faces thecylinder section 52 of theanode 53 which is positioned in the throughhole 56 of theanode holder 54. - In the above state, the
main body section 73 of the secondelectrical conductor 71 contacts with the electricallyconductive section 66 provided on thecontact face 62 a side of themain body section 62 of the firstelectrical conductor 61. Then, the voltage of the secondelectrical conductor 71 is made equal with the voltage of the firstelectrical conductor 61 so that the supporting contact area for thesemiconductor wafer 43 is held at the same potential voltage. - When a high-frequency voltage is applied from a high-frequency power source (not shown) to the first
electrical conductor 61 in a state that thedischarge emission chamber 46 is in atmosphere of argon gas, a predetermined voltage is applied to the entire front and back face of thesemiconductor wafer 43 via the firstelectrical conductor 61 and the secondelectrical conductor 71 which will have an equal voltage level. As a result, a discharge is generated, and an argon ion is created based on the discharge, and the argon ion is accelerated by a high electric field so as to collide against the surface of thesemiconductor wafer 43 which acts as the cathode, and is thereby subject to a predetermined sputtering process. The sputtered particles (atom, molecule and ion) that are released from thesemiconductor wafer 43 are then excited in the plasma field, and when the particles again return to a ground state, their characteristic wavelength emission is peculiar to the elements in thewafer 43. This emitted light is introduced in the direction of the spectroscope in the apparatusmain body 31 as a light represented by areference numeral 43 in FIG. 5. - As can be appreciated by determining the depth of etch or sputtering a profile as the elements in the wafer can be determined for not only the surface, but for controlled distances into the body of the wafer.
- In the glow discharge emission spectroscopic analysis apparatus, since the
semiconductor wafer 43 is nipped by the firstelectrical conductor 61 and the secondelectrical conductor 71, thesemiconductor wafer 43 can be held securely in a predetermined state. In the nipped state, the firstelectrical conductor 61 and the secondelectrical conductor 71 have equal voltages, and both theelectrical conductors semiconductor wafer 43. As a result, only by applying a high-frequency voltage to the firstelectrical conductor 61, a predetermined voltage can be applied to the entire surface of thesemiconductor wafer 43, and the applying of a voltage to thesemiconductor wafer 43 can be executed very simply and stably. Particularly since a voltage from the high-frequency power source is applied to the fixed firstelectrical conductor 61, it is not necessary to install a power source cable, and thus installation of other components can be designed easily. - In addition, in the glow discharge emission spectroscopic analysis apparatus, the fixed first
electrical conductor 61 is composed of themain body section 62 and the mountingsections 63, they are coupled with each other by theelastic coupling plate 64 so as to be flush with each other (no stepped portion is obtained), and thus the firstelectrical conductor 61 has an elastic structure. As a result, even if thesemiconductor wafer 43 is slightly distorted or warped, the firstelectrical conductor 61 can absorb or adjust for the distortion and warpage, and can still hold thesemiconductor wafer 43 in the desired position in cooperation with the secondelectrical conductor 71. - Furthermore, the movable second
electrical conductor 71 is composed of the pressurizingsection 72 for pressurizing the area of thesemiconductor wafer 43 to be analyzed and themain body section 73, has an elastic structure, and thepressing section 72 and themain body section 73 are pressurized respectively byindividual piston rods piston rods 75 b to the pressurizingsection 72 is set to be larger than a pressurizing force of thepiston rod 76 b to themain body section 73, the portion of thesemiconductor wafer 43 including the area to be analyzed can be pressed strongly against theanode holder 54, and thus a predetermined airtightness can be maintained. - Even when an analysis of the
semiconductor wafer 43 was conducted by the use of the above described glow discharge emission spectroscopic analysis apparatus, the same result as that of the glow discharge emission spectroscopic analysis apparatus of the first embodiment has been obtained. - In the above embodiment, the second
electrical conductor 71 is driven by the twoair cylinders - In addition, in the above embodiment, the
semiconductor wafer 43 is used as a sample, but the present invention is not limited to this, and thus, conductors such as metal, non-conductors and semiconductors such as various insulating material including ceramics can be used for analysis. Further, when the sample is a conductor, it is needless to say that a DC voltage may be applied thereto instead of a high-frequency voltage. - Since the second embodiment of the glow discharge emission spectroscopic analysis apparatus is arranged so that the
sample 43 is sandwiched between the first electrical conductor 61 s and the secondelectrical conductor 71 and a negative electric potential is given to one of them, a voltage is applied to thesample 43 uniformly, and the intensity of the discharge emission becomes stable. As a result, a desired and stable analyzed result can be obtained. Therefore, the desired chemical analysis may be made with excellent reproducibility. - It is not intended to limit this invention to the particular embodiments disclosed but, on the contrary, the invention is to cover all modifications and alternative constructions all within the spirit and scope of the invention as expressed in the appended claims and as known by those skilled in the field as equivalents to the elements set forth in the claims.
Claims (4)
17. (New) An apparatus for determining the elements in a semiconductor wafer, comprising:
a conductor member having an aperture, the conductor member has a size to extend across the semiconductor wafer and contact one surface of the semiconductor wafer to enable an application of uniform potential to be applied to the entire surface of the semiconductor wafer to be sampled;
means for mounting the semiconductor wafer on the conductor member;
a glow discharge chamber unit having an anode and an opening adjacent the aperture of the conductor member;
means for exerting a force on the semiconductor wafer to seal at least a portion of the surface to be sampled to the glow discharge chamber unit opening when mounted on the conductor member;
means for providing a sputtering gas to the glow discharge chamber unit;
means for providing an electrical charge of sufficient power to the conductor member to uniformly charge the surface of the semiconductor wafer as a cathode to the anode, whereby a glow discharge emission is created as the semiconductor wafer is sputtered; and
means for providing a spectroscopic analysis of the light from the glow discharge emission to determine the elements in the semiconductor wafer.
18. (New) The apparatus of claim 17 wherein the conductor member is larger in size than the semiconductor wafer.
19. (New) The apparatus of claim 17 , wherein the conductor member is resiliently mounted to permit adjustable movement between the conductor member and the semiconductor wafer when the semiconductor wafer is mounted on the conductor member.
20. (New) A system for determining the elements in a semiconductor sample, comprising:
a semiconductor wafer;
a conductor member, the conductor member has a size to extend across a first surface of the semiconductor wafer to enable an application of uniform potential to be applied to a surface of the semiconductor wafer to be sampled;
means for mounting the first surface of the semiconductor wafer on the conductor member;
a glow discharge chamber unit having an anode and an opening adjacent the conductor member;
means for exerting a force on the semiconductor wafer to seal at least a portion of a second surface of the semiconductor wafer to be sampled to the glow discharge chamber unit opening when mounted on the conductor member;
means for providing a sputtering gas to the glow discharge chamber unit;
means for providing an electrical charge of sufficient power to the conductor member to uniformly change the first surface of the semiconductor wafer as a cathode to the anode, whereby a glow discharge emission is created as the semiconductor wafer is sputtered; and
means for providing a spectroscopic analysis of the light from the glow discharge emission to determine the elements in the semiconductor wafer.
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JP10365229A JP2000187002A (en) | 1998-12-22 | 1998-12-22 | Glow discharge light spectrum analyser |
US09/376,164 US6643013B1 (en) | 1998-12-22 | 1999-08-17 | Glow discharge emission spectroscopic analysis apparatus |
US10/628,727 US20040017565A1 (en) | 1998-12-22 | 2003-07-28 | Glow discharge emission spectroscopic analysis apparatus |
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US20140218729A1 (en) * | 2013-02-05 | 2014-08-07 | Clemson University | Means of Introducing an Analyte into Liquid Sampling Atmospheric Pressure Glow Discharge |
JP2015141177A (en) * | 2014-01-30 | 2015-08-03 | 株式会社堀場製作所 | Glow discharge spectroscopic analyzer, sample support and sample pressing electrode |
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DE10019257C2 (en) * | 2000-04-15 | 2003-11-06 | Leibniz Inst Fuer Festkoerper | Glow discharge source for elemental analysis |
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-
1999
- 1999-08-17 US US09/376,164 patent/US6643013B1/en not_active Expired - Fee Related
- 1999-11-16 EP EP99122782A patent/EP1014076B1/en not_active Expired - Lifetime
- 1999-11-16 DE DE69919669T patent/DE69919669T2/en not_active Expired - Fee Related
-
2003
- 2003-07-28 US US10/628,727 patent/US20040017565A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4733130A (en) * | 1984-02-27 | 1988-03-22 | Shimadzu Corporation | Insulating tube surrouding anode tube in analytical glow discharge tube |
US5028133A (en) * | 1989-12-14 | 1991-07-02 | Regie Nationale Des Usines Renault | Process and device for analysis of nonconductive surfaces |
US5184016A (en) * | 1990-01-10 | 1993-02-02 | Vg Instruments Group Limited | Glow discharge spectrometry |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110014482A1 (en) * | 2006-06-05 | 2011-01-20 | Dow Corning Corporation | Ductile multilayer silicone resin films |
US20140218729A1 (en) * | 2013-02-05 | 2014-08-07 | Clemson University | Means of Introducing an Analyte into Liquid Sampling Atmospheric Pressure Glow Discharge |
US9536725B2 (en) * | 2013-02-05 | 2017-01-03 | Clemson University | Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge |
US10269525B2 (en) | 2013-02-05 | 2019-04-23 | Clemson University Research Foundation | Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge |
JP2015141177A (en) * | 2014-01-30 | 2015-08-03 | 株式会社堀場製作所 | Glow discharge spectroscopic analyzer, sample support and sample pressing electrode |
Also Published As
Publication number | Publication date |
---|---|
EP1014076A3 (en) | 2002-07-03 |
DE69919669D1 (en) | 2004-09-30 |
JP2000187002A (en) | 2000-07-04 |
EP1014076B1 (en) | 2004-08-25 |
US6643013B1 (en) | 2003-11-04 |
EP1014076A2 (en) | 2000-06-28 |
DE69919669T2 (en) | 2005-08-18 |
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