JP3907444B2 - Plasma processing apparatus and structure manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus that performs processing by generating plasma using a microwave and a method for manufacturing a structure.
[0002]
[Prior art]
Plasma processing equipment that uses microwaves as an excitation source for plasma generation includes CVD equipment, etching equipment, ashing equipment, etc. used in manufacturing processes for optical parts, LSIs, flat panel displays, micromechanics, and other structures. It has been known.
[0003]
For example, CVD using such a so-called microwave plasma CVD apparatus is performed as follows. That is, a gas for plasma generation is introduced into the plasma generation chamber and the film formation chamber of the microwave plasma CVD apparatus, and at the same time, microwave energy is introduced to generate plasma in the plasma generation chamber to excite and decompose the gas. A deposited film is formed on the object to be processed disposed in the film chamber.
[0004]
Moreover, the etching process of the to-be-processed object which uses what is called a microwave plasma etching apparatus is performed as follows, for example. That is, an etchant gas is introduced into the processing chamber of the apparatus, and at the same time, microwave energy is injected to excite and decompose the etchant gas to generate plasma in the processing chamber. The surface of the treatment body is etched.
[0005]
Moreover, the ashing process of the to-be-processed object which uses what is called a microwave plasma ashing apparatus is performed as follows, for example. That is, an ashing gas is introduced into the processing chamber of the apparatus, and at the same time, microwave energy is injected to excite and decompose the ashing gas to generate plasma in the processing chamber, thereby causing the object to be disposed in the processing chamber. Ashing the surface of the treated body.
[0006]
In plasma processing equipment that generates plasma using microwaves, microwaves are used as a gas excitation source, so electrons can be accelerated by an electric field with a high frequency, and gas molecules can be efficiently ionized and excited. Can do. Therefore, the plasma processing apparatus using microwaves has the advantages of high gas ionization efficiency, excitation efficiency and decomposition efficiency, can form a high-density plasma relatively easily, and can perform high-quality processing at low temperature and high speed. Have.
[0007]
In addition, since the microwave has a property of transmitting through the dielectric, the plasma processing apparatus can be configured as an electrodeless discharge type, and there is also an advantage that highly clean plasma processing can be performed.
[0008]
In order to further increase the speed of such a microwave plasma processing apparatus, a plasma processing apparatus using electron cyclotron resonance (ECR) has been put into practical use. In the ECR, when the magnetic flux density is 87.5 mT, the electron cyclotron frequency at which the electrons rotate around the magnetic field lines matches the general microwave frequency of 2.45 GHz, and the electrons absorb the microwaves resonantly. This is a phenomenon in which high-density plasma is generated by acceleration.
[0009]
Apart from this, as an example of a microwave plasma processing apparatus, an apparatus using an endless annular waveguide in which a plurality of slots are formed has recently been proposed as an apparatus for uniformly and efficiently introducing microwaves. (Unexamined-Japanese-Patent No. 5-345882, Unexamined-Japanese-Patent No. 10-233295). FIG. 5A shows this microwave plasma processing apparatus, and FIG. 5B shows the plasma generation mechanism. 901 is a plasma processing chamber, 902 is an object to be processed, 903 is a support for the object to be processed 902, 904 is a substrate temperature adjusting means, 905 is a gas introduction means for plasma processing provided around the plasma processing chamber 901, and 906 is Exhaust, 907 is a flat dielectric window that separates the plasma processing chamber 901 from the atmosphere side, 908 is a slotless endless annular waveguide for introducing microwaves into the plasma processing chamber 901 through the dielectric window 907, and 911 E branch for distributing microwaves to the left and right, 912 is a standing wave generated inside the endless annular waveguide 908, 913 is a slot, 914 is a surface wave propagating on the surface of the dielectric window 907, and 915 is introduced from an adjacent slot Surface standing wave generated by interference between the generated surface waves, 916 is a surface plasma generated by the surface standing wave 915, and 917 is a surface plasma 916. A bulk plasma generated by diffusion.
[0010]
The plasma treatment using the above apparatus is performed as follows. The plasma processing chamber 901 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 901 at a predetermined flow rate through a gas introduction means 905 provided around the plasma processing chamber 901. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to maintain the plasma processing chamber 901 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 901 through an endless annular waveguide 908. At this time, the microwaves introduced into the endless annular waveguide 908 are distributed into the left and right by the E branch 911 and propagate with a longer in-tube wavelength than the free space. The distributed microwaves interfere with each other, and a standing wave “antinode” occurs every half of the guide wavelength.
[0011]
An initial high-density plasma is generated in the vicinity of the slot 913 by the microwave introduced through the dielectric window 907 through the slot 913 provided so as to cross the surface current and introduced into the plasma processing chamber 901. In this state, the microwave incident on the interface between the dielectric window 907 and the initial high-density plasma cannot propagate through the initial high-density plasma, and propagates as the surface wave 914 through the interface between the dielectric window 907 and the initial high-density plasma. To do.
[0012]
Surface waves 914 introduced from adjacent slots interfere with each other to generate a surface standing wave 915 having an “antinode” for every half of the wavelength of the surface wave 914. A surface plasma 916 is generated by the surface standing wave 915. Further, bulk plasma 917 is generated by the diffusion of the surface plasma 916. The processing gas is excited by the generated surface wave interference plasma and processes the surface of the object to be processed 902 fixed and placed on the support 903.
[0013]
By using such a microwave plasma processing apparatus, an electron density of 10% with a uniformity of within ± 3% in a large-diameter space having a diameter of about 300 mm with a microwave power of 1 kW or more. ¹² cm ^-3 As described above, since a high-density low-potential plasma having an electron temperature of 3 eV or less and a plasma potential of 15 V or less can be generated, the gas can be sufficiently reacted and supplied to the object to be processed, and the substrate surface damage due to incident ions can be reduced. High quality, uniform and high speed processing is possible even at low temperatures.
[0014]
[Problems to be solved by the invention]
However, when the plasma processing is performed using the microwave plasma processing apparatus as described above, if the plasma having a cutoff density or higher is generated, the propagation of the microwave toward the object to be processed is suppressed. When the initial non-occurrence and low density, the microwave propagates to the object to be processed, and damage due to the microwave irradiation may occur.
[0015]
The present invention has been made in view of the above points, and an object of the present invention is to provide a plasma processing apparatus capable of reducing microwave irradiation to a substrate and suppressing irradiation damage even in the initial stage of discharge.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a plasma processing apparatus for performing plasma processing by introducing a microwave into a plasma processing chamber via a microwave waveguide and generating plasma in the plasma processing chamber. The microwave conversion distance between the surface of the object to be processed and the microwave waveguide is an odd multiple of about a quarter of the natural wavelength.
[0017]
Further, the present invention provides a plasma processing apparatus that exhausts a substantially cylindrical plasma processing chamber by an exhaust means, introduces microwaves into the plasma processing chamber via a microwave introduction tube, and generates plasma in the plasma processing chamber. And a microwave reflecting means for reflecting the microwave reflected by the surface of the object to be processed at a position which is an odd multiple of the natural wavelength of the microwave at a microwave conversion distance from the surface of the object to be processed. It is characterized by providing.
[0018]
Furthermore, the present invention provides a high frequency emission slot formed in the high frequency supply device in a plasma processing apparatus for introducing a high frequency into the plasma processing chamber via a high frequency supply device and generating plasma in the plasma processing chamber. And a plasma detection element for detecting plasma. The slot is preferably provided in a slot plate arranged in parallel with the surface to be processed of the object to be processed, and the control for stopping the supply of microwaves based on the detection result of the plasma detection element. It is good to further have an apparatus.
[0019]
In addition, the present invention is characterized in that in the structure manufacturing method including the step of plasma processing the surface of the substrate on which the structure is to be formed, the plasma processing is performed using the plasma processing apparatus described above.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the basic concept of the present invention will be described with reference to FIG. 101 is a plasma processing chamber whose inner wall is substantially cylindrical, 102 is an object to be processed, 103 is a support for the object to be processed 102, 104 is a substrate temperature adjusting means, and 105 is for plasma processing provided around the plasma processing chamber 101. Gas introduction means 106, exhaust, 107 a dielectric window that separates the plasma processing chamber 101 from the atmosphere side, 108 a high frequency supply device for introducing microwaves as high frequency into the plasma processing chamber 101 through the dielectric window 107 , A slotless endless annular waveguide, 109 a microwave reflecting member serving as a microwave reflecting means, 111 an E branch for distributing the microwave to the left and right, and 112 a standing wave generated inside the endless annular waveguide. 113 is a slot, 114 is a surface wave that propagates through the surface of the dielectric window 107 through the slot 113, and 115 is guided from the adjacent slot 113. Surface waves 114 surface standing wave produced by interference between, 116 surface plasma caused by the surface standing waves 115, 117 is a bulk plasma caused by the diffusion of the surface plasma. Reference numeral 121 denotes a plasma detecting element including a light receiving element provided above an arbitrary slot 113, and a conductive upper wall constituting the detection light transmitting dielectric window 107, the slot 113, and the endless annular waveguide 108. The plasma light is monitored through the through-hole formed in. The detection element 121 is connected to a control device (not shown), and the processing state can be controlled by observing the plasma in situ. For example, the detection element 121 can be used as a malfunction detection monitor that detects malfunction such as non-plasma generation or an endpoint monitor for properly terminating the plasma processing. The microwave reflection member 109 has a microwave conversion interval between the upper surface of the workpiece support 103 and the lower surface of the endless annular waveguide 108 (that is, the lower surface of the conductive slot plate 120 in which the slot 113 is formed). If it is an odd multiple of a quarter of the wavelength, it need not be used.
[0021]
The plasma treatment is performed as follows. The plasma processing chamber 101 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 101 at a predetermined flow rate through a gas introduction means 105 provided around the plasma processing chamber 101. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to maintain the plasma processing chamber 101 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 101 through the endless annular waveguide 108. At this time, the microwave introduced into the endless annular waveguide 108 is distributed to the left and right by the E branch 111 and propagates with an in-tube wavelength longer than the free space. The distributed microwaves interfere with each other to generate a standing wave 112 having an “antinode” for every half of the guide wavelength. A microwave is introduced into the plasma processing chamber 101 through the dielectric window 107 through the slot 113 provided so as to cross the surface current.
[0022]
At this time, the microwave propagates in the direction of the object to be processed 102 until plasma having a cutoff density or higher is generated, but the microwave conversion interval between the upper surface of the object to be processed 103 and the lower surface of the endless annular waveguide 108. Is set to an odd multiple of about 4 times the natural wavelength of the microwave, or the microwave is reflected from the surface 103 of the object to be processed toward the target object support 103 at an odd multiple of the natural wavelength of about 4 minutes. If the microwave reflecting means 109 is formed, the object that is directed toward the object to be processed 102 and the object that is reflected by the object to be processed 102 interfere with each other and weaken each other. Wave excitation can be suppressed. Thereby, the microwave irradiation to the to-be-processed object 102 can be reduced.
[0023]
An initial high-density plasma is generated near the slot 113 by the microwave introduced into the plasma processing chamber 101. In this state, the microwave incident on the interface between the dielectric window 107 and the initial high-density plasma cannot propagate in the initial high-density plasma, and propagates as the surface wave 114 through the interface between the dielectric window 107 and the initial high-density plasma. To do.
[0024]
The surface waves 114 introduced from adjacent slots interfere with each other to generate a surface standing wave 115 having an “antinode” about every half of the wavelength of the surface wave 114. A surface plasma 116 is generated by the surface standing wave 115. Further, the bulk plasma 117 is generated by the diffusion of the surface plasma 116. The processing gas is excited by the generated surface wave interference plasma and processes the surface of the target object 102 placed on the support 103 in a fixed manner.
[0025]
Since the plasma state can be monitored by the detection element 121, if a desired plasma is not generated even after a predetermined time has elapsed after the microwave supply is started, the supply of the microwave is stopped based on the monitoring result. Thus, the processing operation can be interrupted. Even in such a case, microwave damage to the object to be processed can be prevented. In particular, when the detection element is arranged at the above-described position, plasma in the vicinity of the slot 113, which is a source of microwaves supplied into the processing chamber, can be observed, so that more accurate plasma observation can be performed. Since there are a plurality of slots, the detection elements 121 may be provided at the positions of two or more slots.
[0026]
In addition, when performing processing such as etching and ashing, depending on the atoms constituting the surface to be processed, the light emission state of the plasma may change around the end of the desired processing. Thus, the processing can be terminated by stopping the supply of the microwave.
[0027]
The microwave conversion distance from the upper surface of the workpiece support 103 to the lower surface of the endless annular waveguide 108 is an equivalent thickness obtained by multiplying the actual thickness by the square root of the relative dielectric constant of each material with respect to the frequency of the introduced microwave. Are totaled for each material. The frequency of the microwave is usually about 300 MHz to about 3 THz, but the frequency used in the embodiment is particularly effective about 1 to 10 GHz where the wavelength is about the same as the reactor size.
[0028]
The microwave reflection means can be applied as long as it has a reflection structure toward the workpiece support 103 having an area of about 5% or more of the cross-sectional area of the plasma processing chamber 101, and even a simple reflection surface protrudes like a bowl. It may be a structure having a hole diameter of about 1/8 or less of the natural wavelength of the microwave.
[0029]
The material of the dielectric window 109 can be applied as long as it has sufficient mechanical strength and has a small dielectric defect so that the microwave transmittance is sufficiently high. For example, quartz, alumina, sapphire, aluminum nitride, fluoride Carbon polymer and the like are applicable.
[0030]
The material of the slotted endless annular waveguide 108 and the slot plate 120 constituting the high-frequency feeder can be used as long as it is a conductor, but in order to suppress the microwave propagation loss as much as possible, Al having high conductivity, Cu, Ag / Cu plated SUS, etc. are optimal. The direction of the inlet of the slotted endless annular waveguide 108 is parallel to the H plane as long as the microwave can be efficiently introduced into the microwave propagation space in the slotted endless annular waveguide 108. Even in the tangential direction of the space, it may be distributed in the horizontal direction of the propagation space at the introduction portion in the direction perpendicular to the H plane.
[0031]
The slot shape of the slotted endless annular waveguide 108 may be rectangular, elliptical, or arrayed as long as the length in the direction perpendicular to the microwave propagation direction is about ¼ of the guide wavelength. The slot spacing of the slotted endless annular waveguide 108 used in the embodiment is optimally ½ of the guide wavelength so that the electric field across the slot is strengthened by interference.
[0032]
Further, a magnetic field generating means may be used to perform processing under a lower pressure. As the magnetic field used, any magnetic field that is perpendicular to the electric field generated in the width direction of the slot is applicable. As the magnetic field generating means, a permanent magnet can be used in addition to the coil. When using a coil, other cooling means such as a water cooling mechanism or air cooling may be used to prevent overheating.
[0033]
Moreover, you may irradiate the to-be-processed object surface for the quality improvement of a process. As the light source, any light source that emits light absorbed by the object to be processed or the gas attached to the object to be processed is applicable, and an excimer laser, an excimer lamp, a rare gas resonance line lamp, a low-pressure mercury lamp, etc. are suitable. .
[0034]
The pressure in the plasma processing chamber is 1.33 × 10 ^-2 From about Pa to 13.3 × 10 ² The range of about Pa, more preferably about 1.33 Pa to 6.65 × 10 ² A range of about Pa is appropriate.
[0035]
The formation of the deposited film can be achieved by appropriately selecting the gas to be used. _Three N _Four , SiO ₂ , SiOF, Ta ₂ O _Five TiO ₂ TiN, Al ₂ O _Three , AlN, MgF ₂ It is possible to efficiently form various deposited films such as an insulating film such as a semiconductor film such as a-Si, poly-Si, SiC, and GaAs, and a metal film such as Al, W, Mo, Ti, and Ta. .
[0036]
The object to be processed 102 for manufacturing the structure may be a semiconductor, a conductive material, or an electrically insulating material.
[0037]
Examples of the conductive object include metals such as Fe, Ni, Cr, Al, Mo, Au, Nb, Ta, V, Ti, Pt, and Pb, or alloys thereof, such as brass and stainless steel.
[0038]
As an insulating object, SiO ₂ Quartz, glass, Si _Three N _Four , NaCl, KCl, LiF, CaF ₂ , BaF ₂ , Al ₂ O _Three Inorganic films such as AlN, MgO, polyethylene, polyester, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, and other organic films and sheets.
[0039]
The direction of the gas introduction means 105 is such that the gas flows through the plasma region generated in the vicinity of the dielectric window 108 and then sufficiently supplied to the vicinity of the center, and then flows on the substrate surface from the center toward the periphery. It is optimal to have a structure in which gas can be blown toward the surface.
[0040]
As a gas used when forming a thin film on a substrate by a CVD method, a known gas can be used.
[0041]
A source gas containing Si atoms introduced into the plasma processing chamber 101 via the processing gas introducing means 105 when forming a Si-based semiconductor thin film such as a-Si, poly-Si, SiC, etc. is SiH. _Four , Si ₂ H ₆ Inorganic silanes such as tetraethylsilane (TES), tetramethylsilane (TMS), dimethylsilane (DMS), dimethyldifluorosilane (DMDFS), dimethyldichlorosilane (DMDCS), etc., SiF _Four , Si ₂ F ₆ , Si _Three F ₈ , SiHF _Three , SiH ₂ F ₂ , SiCl _Four , Si ₂ Cl ₆ , SiHCl _Three , SiH ₂ Cl ₂ , SiH _Three Cl, SiCl ₂ F ₂ And halogenated silanes such as those that are in a gas state at normal temperature and pressure, or those that can be easily gasified. In addition, as an additive gas or carrier gas that may be introduced by mixing with the Si source gas in this case, H ₂ , He, Ne, Ar, Kr, Xe, and Rn.
[0042]
Si _Three N _Four , SiO ₂ As a raw material containing Si atoms introduced through the processing gas introduction means 105 when forming a Si compound-based thin film such as SiH, SiH _Four , Si ₂ H ₆ Inorganic silanes such as tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), octamethylcyclotetrasilane (OMCTS), dimethyldifluorosilane (DMDFS), dimethyldichlorosilane (DMDCS), etc., SiF _Four , Si ₂ F ₆ , Si _Three F ₈ , SiHF _Three , SiH ₂ F ₂ , SiCl _Four , Si ₂ Cl ₆ , SiHCl _Three , SiH ₂ Cl ₂ , SiH _Three Cl, SiCl ₂ F ₂ And halogenated silanes such as those that are in a gas state at normal temperature and pressure, or those that can be easily gasified. In this case, the nitrogen source gas or oxygen source gas introduced at the same time is N ₂ , NH _Three , N ₂ H _Four , Hexamethyldisilazane (HMDS), O ₂ , O _Three , H ₂ O, NO, N ₂ O, NO ₂ Etc.
[0043]
As raw materials containing metal atoms introduced through the processing gas introduction means 105 when forming a metal thin film such as Al, W, Mo, Ti, Ta, etc., trimethylaluminum (TMAl), triethylaluminum (TEAl), Triisobutylaluminum (TIBAl), dimethylaluminum hydride (DMAlH), tungsten carbonyl (W (CO) ₆ ), Molybdenum carbonyl (Mo (CO) ₆ ), Organic metals such as trimethylgallium (TMGa), triethylgallium (TEGa), tetraisopropoxytitanium (TIPOTi), pentaethoxytantalum (PEOTa), AlCl _Three , WF ₆ TiCl _Three , TaCl _Five And metal halides. In addition, as an additive gas or carrier gas that may be introduced by mixing with the Si source gas in this case, H ₂ , He, Ne, Ar, Kr, Xe, and Rn.
[0044]
Al ₂ O _Three , AlN, Ta ₂ O _Five TiO ₂ , TiN, WO _Three Examples of raw materials containing metal atoms introduced through the processing gas introduction means 105 when forming a metal compound thin film such as trimethylaluminum (TMAl), triethylaluminum (TEAl), triisobutylaluminum (TIBAl), dimethyl Aluminum hydride (DMAlH), tungsten carbonyl (W (CO) 6), molybdenum carbonyl (Mo (CO) ₆ ), Organic metals such as trimethylgallium (TMGa), triethylgallium (TEGa), tetraisopropoxytitanium (TIPOTi), pentaethoxytantalum (PEOTa), AlCl _Three , WF ₆ TiCl _Three , TaCl _Five And metal halides. In this case, the oxygen source gas or the nitrogen source gas introduced simultaneously is O ₂ , O _Three , H ₂ O, NO, N ₂ O, NO ₂ , N ₂ , NH _Three , N ₂ H _Four , Hexamethyldisilazane (HMDS) and the like.
[0045]
The etching gas introduced from the processing gas inlet 105 when etching the surface of the object to be processed is F ₂ , CF _Four , CH ₂ F ₂ , C ₂ F ₆ , C _Three F ₈ , C _Four F ₈ , CF ₂ Cl ₂ , SF ₆ , NF _Three , Cl ₂ , CCl _Four , CH ₂ Cl ₂ , C ₂ Cl ₆ Etc.
[0046]
As an ashing gas introduced from the processing gas inlet 105 when ashing and removing organic components on the surface of the object to be processed such as a photoresist, ₂ , O _Three , H ₂ O, NO, N ₂ O, NO ₂ , H ₂ Etc.
[0047]
When surface modification is performed, by appropriately selecting the gas to be used, for example, Si, Al, Ti, Zn, Ta, etc. are used as the object to be processed or the surface layer. Treatment or nitridation treatment, doping treatment of B, As, P, etc. can be performed. Furthermore, the film forming technique employed can be applied to a cleaning method. In that case, it can also be used for cleaning oxides, organic substances, heavy metals, and the like.
[0048]
As an oxidizing gas introduced through the processing gas inlet 105 when an object to be processed is subjected to an oxidation surface treatment, an oxidizing gas is used. ₂ , O _Three , H ₂ O, NO, N ₂ O, NO ₂ Etc. Further, as the nitriding gas introduced through the processing gas inlet 115 when the object to be treated is nitrided, N.sub. ₂ , NH _Three , N ₂ H _Four , Hexamethyldisilazane (HMDS) and the like.
[0049]
The cleaning / ashing gas introduced from the gas inlet 105 when the organic substance on the surface of the object to be processed is cleaned or the organic component on the surface of the object to be processed, such as a photoresist, is removed by ashing. ₂ , O _Three , H ₂ O, NO, N ₂ O, NO ₂ , H ₂ Etc. Further, as a cleaning gas introduced from the plasma generating gas inlet when cleaning the inorganic substance on the surface of the object to be processed, F ₂ , CF _Four , CH ₂ F ₂ , C ₂ F ₆ , C _Four F ₈ , CF ₂ Cl ₂ , SF ₆ , NF _Three Etc.
[0050]
Hereinafter, although the plasma processing apparatus concerning this invention is described by embodiment, this invention is not limited to the following embodiment.
[0051]
(Embodiment 1)
An example in which a reflecting structure is not used and a quartz window is used will be described with reference to FIG. 1 as Embodiment 1 of the present invention. 101 is a substantially cylindrical plasma processing chamber, 102 is an object to be processed, 103 is a support for the object to be processed 102, 104 is a substrate temperature adjusting means, and 105 is a gas for plasma processing provided around the plasma processing chamber 101. Means 106 is exhaust, 107 is a dielectric window for separating the plasma processing chamber 101 from the atmosphere side, and 108 is a slotted endless annular waveguide for introducing microwaves into the plasma processing chamber 101 through the dielectric window 107. Yes, here it is an assembly having a slot plate 120.
[0052]
The dielectric window 107 is made of anhydrous synthetic quartz, has a thickness of about 16 mm, and has a relative dielectric constant of 3.8 at an introduced microwave frequency of 2.45 GHz. The slotted endless annular waveguide 108 has an inner wall cross-sectional dimension of approximately 27 mm × 96 mm, and the center diameter of the waveguide is approximately 202 mm (circumferential length 4λg). Al is used as the material for the slotted endless annular waveguide 108 in order to suppress microwave propagation loss. A slot for introducing a microwave into the plasma processing chamber 101 is formed on the H surface of the slotted endless annular waveguide 108. The slot has a rectangular shape having a length of about 40 mm and a width of about 4 mm, and is formed discontinuously on two straight lines and radially at intervals of about ½ of the guide wavelength. The guide wavelength depends on the frequency of the introduced microwave and the size of the cross section of the waveguide, but when a microwave having a frequency of about 2.45 GHz and a waveguide having the above dimensions are used. About 159 mm. In the slotted endless annular waveguide 108 used, eight sets of 16 slots are formed at intervals of about 45 degrees. To the slotted endless annular waveguide 108, a 4E tuner, a directional coupler, an isolator, and a microwave power source (not shown) that generates a microwave having a frequency of about 2.45 GHz are sequentially connected.
[0053]
Here, the microwave conversion interval from the lower surface of the endless annular waveguide 108 to the upper surface of the workpiece support 103 is:
(1) Air gap from the bottom surface of endless annular waveguide 108 to the top surface of quartz window 107
Actual thickness of about 1 mm x square root of relative dielectric constant 1 = equivalent thickness of about 1 mm
(2) Quartz window 107
Actual thickness of about 16 mm x square root of relative dielectric constant 1.95 = equivalent thickness of about 31.2 mm
(3) Vacuum from the lower surface of the quartz window 107 to the upper surface of the workpiece support 103
Actual thickness about 120.8mm x square root of relative dielectric constant 1 = equivalent thickness about 120.8mm
Is about 153 mm, that is, about 5/4 times the natural wavelength 122.4 mm of the microwave of 2.45 GHz.
[0054]
The plasma treatment is performed as follows. The plasma processing chamber 101 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 101 at a predetermined flow rate through a gas introduction means 105 provided around the plasma processing chamber 101. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to maintain the plasma processing chamber 101 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 101 through the endless annular waveguide 108. The microwave propagates in the direction of the substrate until plasma having a cutoff density or higher is generated. The microwave conversion distance between the lower surface of the endless annular waveguide 108 and the upper surface of the workpiece support 103 is a microwave natural wavelength. Since it is an odd multiple of four, the microwave substrate irradiation is suppressed, and damage caused by the irradiation is reduced. At this time, the processing gas introduced from the periphery is activated by being excited, ionized, and reacted by the generated high-density plasma, and processes the surface of the target object 102 placed on the support 103 in a fixed manner.
[0055]
(Embodiment 2)
An example in which a lower reflective surface is used as Embodiment 2 of the present invention will be described with reference to FIG. 201 is a cylindrical plasma processing chamber, 202 is an object to be processed, 203 is a support for the object to be processed 202, 204 is a substrate temperature adjusting means, and 205 is a gas introduction means for plasma processing provided around the plasma processing chamber 201. , 206 is exhaust, 207 is a dielectric window that separates the plasma processing chamber 201 from the atmosphere side, and 208 is a slotted flat plate type endless annular waveguide for introducing microwaves into the plasma processing chamber 201 through the dielectric window 207. , 209 are lower surface reflecting surfaces.
[0056]
The dielectric window 207 is made of anhydrous synthetic quartz and has a thickness of about 16 mm. The slotted endless annular waveguide 208 has an inner wall cross-sectional dimension of about 27 mm × 96 mm, and the center diameter of the waveguide is about 202 mm (around 4λg circumference). Al is used for the material of the slotted endless annular waveguide 208 in order to suppress microwave propagation loss. A slot 213 for introducing a microwave into the plasma processing chamber 201 is formed in the H surface of the slotted endless annular waveguide 208, that is, the conductive slot plate 220. The slot has a rectangular shape with a length of about 40 mm and a width of about 4 mm, and is formed discontinuously on two straight lines and radially at ½ intervals of the guide wavelength. The guide wavelength depends on the frequency of the microwave to be used and the size of the cross section of the waveguide. However, when a microwave having a frequency of about 2.45 GHz and a waveguide having the above dimensions are used, the guide wavelength is about 159 mm. In the slotted endless annular waveguide 208 used, 16 sets of 8 slots are formed at intervals of about 45 degrees. To the slotted endless annular waveguide 208, a 4E tuner, a directional coupler, an isolator, and a microwave power source (not shown) having a frequency of 2.45 GHz are sequentially connected. Reference numeral 221 denotes a plasma detection element.
[0057]
Here, the distance from the lower surface reflecting surface 209 to the upper surface of the workpiece support 203 is set to about 30.6 mm, that is, about 1/4 of the natural wavelength 122.4 mm of the microwave of 2.45 GHz. is there.
[0058]
The plasma treatment is performed as follows. The plasma processing chamber 201 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 201 at a predetermined flow rate through a gas introduction unit 205 provided around the plasma processing chamber 201. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to keep the inside of the plasma processing chamber 201 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 201 via the endless annular waveguide 208. Microwaves propagate in the direction of the substrate until plasma having a cutoff density or higher is generated. However, since the distance from the lower surface reflecting surface 209 to the upper surface of the workpiece support 203 is about 1/4 of the microwave natural wavelength, Wave substrate irradiation is suppressed and damage caused by the irradiation is reduced. At this time, the processing gas introduced from the periphery is activated by excitation, ionization, and reaction by the generated high-density plasma, and processes the surface of the target object 202 placed on the support 203 in a fixed manner.
[0059]
(Embodiment 3)
An example in which a bowl-shaped reflecting surface is used as Embodiment 3 of the present invention will be described with reference to FIG. 301 is a cylindrical plasma processing chamber, 302 is an object to be processed, 303 is a support for the object to be processed 302, 304 is a substrate temperature adjusting means, 305 is a gas introducing means for plasma processing provided around the plasma processing chamber 301 , 306 is an exhaust, 307 is a dielectric window that separates the plasma processing chamber 301 from the atmosphere side, and 308 is a slotted flat plate type endless annular waveguide for introducing microwaves into the plasma processing chamber 301 through the dielectric window 307. , 309 are bowl-shaped reflecting surfaces.
[0060]
The dielectric window 307 is made of anhydrous synthetic quartz and has a thickness of about 16 mm. The slotted endless annular waveguide 308 has an inner wall cross-sectional dimension of about 27 mm × 96 mm, and the center diameter of the waveguide is about 302 mm (around 4λg circumference). Al is used for the material of the slotted endless annular waveguide 308 in order to suppress the propagation loss of microwaves. A slot 313 for introducing a microwave into the plasma processing chamber 301 is formed on the H surface of the slotted endless annular waveguide 308, that is, the conductive slot plate 320. The slot has a rectangular shape having a length of about 40 mm and a width of about 4 mm, and is formed discontinuously on two straight lines and radially at intervals of about ½ of the guide wavelength. The in-tube wavelength depends on the frequency of the microwave used and the cross-sectional dimension of the waveguide. However, when a microwave having a frequency of about 2.45 GHz and a waveguide having the above dimensions are used, 159 mm. In the slotted endless annular waveguide 308 used, 16 sets of 8 slots are formed at intervals of about 45 degrees. The slotted endless annular waveguide 308 is connected in turn with a 4E tuner, a directional coupler, an isolator, and a microwave power source (not shown) having a frequency of 2.45 GHz. Reference numeral 321 denotes a plasma detection element.
[0061]
Here, the distance from the bowl-shaped reflecting surface 309 to the upper surface of the workpiece support 303 is set to about 30.6 mm, that is, about 1/4 of the natural wavelength 122.4 mm of the microwave of 2.45 GHz. It is.
[0062]
The plasma treatment is performed as follows. The inside of the plasma processing chamber 301 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 301 at a predetermined flow rate through a gas introduction unit 305 provided around the plasma processing chamber 301. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to maintain the plasma processing chamber 301 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 301 via the endless annular waveguide 308. The microwave propagates in the direction of the substrate until plasma having a cutoff density or higher is generated, but the distance from the bowl-shaped reflecting surface 309 to the upper surface of the workpiece support 303 is set to about ¼ of the natural wavelength of the microwave. Therefore, the substrate irradiation with microwaves is suppressed, and damage due to the irradiation is reduced. At this time, the processing gas introduced from the periphery is activated by excitation, ionization, and reaction by the generated high-density plasma, and processes the surface of the target object 302 placed fixedly on the support 303.
[0063]
(Embodiment 4)
An example in which a groove-like reflecting surface is used as Embodiment 4 of the present invention will be described with reference to FIG. 401 is a cylindrical plasma processing chamber, 402 is an object to be processed, 403 is a support for the object to be processed 402, 404 is a substrate temperature adjusting means, 405 is a gas inlet for plasma processing provided around the plasma processing chamber 401 , 406 is exhaust, 407 is a dielectric window that separates the plasma processing chamber 401 from the atmosphere side, and 408 is a slotted flat plate type endless annular waveguide for introducing microwaves into the plasma processing chamber 401 through the dielectric window 407. , 409 are groove-like reflecting surfaces.
[0064]
The dielectric window 407 is made of anhydrous synthetic quartz and has a thickness of about 16 mm. The slotted endless annular waveguide 408 has an inner wall cross-sectional dimension of approximately 27 mm × 96 mm, and the center diameter of the waveguide is approximately 402 mm (circumferential length 4λg). Al is used for the material of the slotted endless annular waveguide 408 in order to suppress microwave propagation loss. A slot 413 for introducing a microwave into the plasma processing chamber 401 is formed on the H surface of the slotted endless annular waveguide 408, that is, the conductive slot plate 420. The slot has a rectangular shape having a length of about 40 mm and a width of about 4 mm, and is formed discontinuously on two straight lines and radially at intervals of about ½ of the guide wavelength. The in-tube wavelength depends on the frequency of the microwave used and the cross-sectional dimension of the waveguide. However, when a microwave having a frequency of about 2.45 GHz and a waveguide having the above dimensions are used, 159 mm. In the slotted endless annular waveguide 408 used, 16 sets of 8 slots are formed at intervals of about 45 degrees. To the slotted endless annular waveguide 408, a 4E tuner, a directional coupler, an isolator, and a microwave power source (not shown) having a frequency of about 2.45 GHz are sequentially connected. Reference numeral 421 denotes a plasma detection element.
[0065]
Here, the distance from the groove-like reflection surface 409 to the upper surface of the workpiece support 403 is set to about 30.6 mm, that is, about 1/4 of the natural wavelength 122.4 mm of the microwave of 2.45 GHz. It is.
[0066]
The plasma treatment is performed as follows. The plasma processing chamber 401 is evacuated through an exhaust system (not shown). Subsequently, a processing gas is introduced into the plasma processing chamber 401 at a predetermined flow rate through a gas introduction means 405 provided around the plasma processing chamber 401. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to maintain the inside of the plasma processing chamber 401 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) into the plasma processing chamber 401 via the endless annular waveguide 408. The microwave propagates in the direction of the substrate until plasma having a cutoff density or higher is generated, but the interval from the groove-like reflective surface 409 to the upper surface of the object support 403 is set to about 1/4 of the natural wavelength of the microwave. Therefore, the substrate irradiation with microwaves is suppressed, and damage due to the irradiation is reduced. At this time, the processing gas introduced from the periphery is activated by being excited, ionized, and reacted by the generated high-density plasma, and processes the surface of the target object 402 placed on the support 403.
[0067]
(Example of plasma treatment)
Hereinafter, although the plasma processing performed using said embodiment is demonstrated concretely, the surface treatment method of this invention is not limited to these examples.
[0068]
(Processing example 1)
Using the microwave plasma processing apparatus shown in FIG. 1, ashing of the photoresist was performed.
[0069]
As the object to be processed 102, interlayer SiO ₂ A silicon (Si) substrate (φ about 300 mm) immediately after forming the via hole by etching the film was used. First, after the Si substrate 102 is placed on the workpiece support 103, it is heated to about 250 ° C. using the heater 104, and the plasma processing chamber 101 is evacuated through an exhaust system (not shown). .33 × 10 ^-2 The pressure was reduced to about Pa.
[0070]
Oxygen gas was introduced into the plasma processing chamber 101 through the plasma processing gas inlet 105 at a flow rate of about 2 slm. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to set the inside of the processing chamber 101 to 1.995 × 10. ² It was kept at about Pa.
[0071]
Into the plasma processing chamber 101, power of about 2.5 kW was supplied from a 2.45 GHz microwave power source via a slotted endless annular waveguide 108. In this way, plasma was generated in the plasma processing chamber 101. At this time, processing was performed using the plasma detection element 121 while monitoring the plasma state, and the supply of microwaves was stopped when the light emission at a wavelength due to carbon that is a constituent atom of the photoresist became somewhat weak. During the processing, the oxygen gas introduced through the plasma processing gas inlet 105 is excited, decomposed, and reacted in the plasma processing chamber 101 to become oxygen atoms, move in the direction of the silicon substrate 102, and move to the photo on the substrate 102. The resist was oxidized, vaporized and removed. After ashing, gate dielectric breakdown evaluation, ashing speed and substrate surface charge density were evaluated.
[0072]
The uniformity of the obtained ashing speed is as very large as about ± 3.7% (about 6.7 μm / min), and the surface charge density is also about 0.4 × 10. ¹¹ cm ^-2 The gate dielectric breakdown was not observed.
[0073]
(Processing example 2)
Photoresist ashing was performed using the microwave plasma processing apparatus shown in FIG.
[0074]
The object 202 is an interlayer SiO. ₂ A silicon (Si) substrate (about φ12 inches) immediately after etching the film and forming a via hole was used. First, after the Si substrate 202 is placed on the workpiece support 203, it is heated to about 250 ° C. using the heater 204, and the plasma processing chamber 201 is evacuated through an exhaust system (not shown). .33 × 10 ^-3 The pressure was reduced to about Pa. Oxygen gas was introduced into the plasma processing chamber 201 through the plasma processing gas inlet 205 at a flow rate of about 2 slm.
[0075]
Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to adjust the inside of the processing chamber 201 to 2.66 × 10. ² It was kept at about Pa. The plasma processing chamber 201 was supplied with power of about 2.5 kW from a microwave power source of 2.45 GHz through a slotted endless annular waveguide 208. In this way, plasma was generated in the plasma processing chamber 201. At this time, processing was performed using the plasma detection element 221 while monitoring the plasma state, and the supply of microwaves was stopped when light emission at a wavelength due to carbon that is a constituent atom of the photoresist weakened to some extent. During the processing, the oxygen gas introduced through the plasma processing gas inlet 205 is excited, decomposed, and reacted in the plasma processing chamber 201 to become oxygen atoms, move in the direction of the silicon substrate 202, and the photo on the substrate 202. The resist was oxidized, vaporized and removed. After ashing, gate insulation evaluation, ashing speed and substrate surface charge density were evaluated.
[0076]
The obtained ashing speed uniformity is as extremely large as about ± 4.8% (about 8.6 μm / min), and the surface charge density is also about 1.2 × 10. ¹¹ cm ^-2 The gate dielectric breakdown was not observed.
[0077]
(Processing example 3)
Using the microwave plasma processing apparatus shown in FIG. 1, a silicon nitride film for protecting a semiconductor element was formed.
[0078]
The object to be processed 102 is an interlayer SiO on which an Al wiring pattern (line and space of about 0.5 μm) is formed. ₂ A p-type single crystal silicon substrate with a film of about φ300 mm (plane orientation <100>, resistivity of about 10 Ωcm) was used. First, after the silicon substrate 102 is placed on the workpiece support base 103, the inside of the plasma processing chamber 101 is evacuated through an exhaust system (not shown) to obtain 1.33 × 10 6. ^-Five The pressure was reduced to a value of about Pa. Subsequently, the heater 104 was energized, the silicon substrate 102 was heated to about 300 ° C., and the substrate was kept at this temperature. Nitrogen gas was introduced into the processing chamber 101 through the plasma processing gas inlet 105 at a flow rate of about 600 sccm and monosilane gas at a flow rate of 200 sccm. Next, a conductance valve (not shown) provided in the exhaust system (not shown) was adjusted to maintain the inside of the processing chamber 101 at about 2.66 Pa.
[0079]
Next, a power of about 3.0 kW was supplied from a 2.45 GHz microwave power source (not shown) through a slotted endless annular waveguide 108. In this way, plasma was generated in the plasma processing chamber 101. At this time, processing was performed using the plasma detection element 121 while monitoring the plasma state. During processing, the nitrogen gas introduced through the plasma processing gas inlet 105 is excited and decomposed in the plasma processing chamber 101 to become nitrogen atoms, move toward the silicon substrate 102, react with the monosilane gas, and react with silicon nitride. A film was formed on the silicon substrate 102 with a thickness of about 1.0 μm. After film formation, gate dielectric breakdown evaluation, film formation speed, and film quality such as stress were evaluated. The stress was determined by measuring the change in the amount of warpage of the substrate before and after film formation with a laser interferometer Zygo (trade name).
[0080]
The uniformity of the film formation rate of the obtained silicon nitride film is as extremely large as about ± 2.6% (about 560 nm / min), and the film quality is stress 0.8 × 10 ⁹ dyne · cm ^-2 Degree (compression), leakage current 1.2 × 10 ^-Ten A ・ cm ^-2 As a result, it was confirmed that the film had a very high quality with a dielectric breakdown voltage of about 10.3 MV / cm, and no gate dielectric breakdown was observed.
[0081]
(Processing example 4)
The microwave plasma processing apparatus shown in FIG. 2 was used to form a plastic lens antireflection silicon oxide film and silicon nitride film.
[0082]
As the workpiece 202, a plastic convex lens having a diameter of about 50 mm was used. After the lens 202 is placed on the workpiece support table 203, the inside of the plasma processing chamber 201 is evacuated through an exhaust system (not shown) to obtain 1.33 × 10 6. ^-Five The pressure was reduced to a value of about Pa. Nitrogen gas was introduced into the processing chamber 201 through the plasma processing gas inlet 205 at a flow rate of about 150 sccm and monosilane gas at a flow rate of about 70 sccm. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to make the inside of the processing chamber 201 6.55 × 10 6. ^-1 It was kept at about Pa.
[0083]
Next, power of about 3.0 kW was supplied from a 2.45 GHz microwave power source (not shown) into the plasma processing chamber 201 through the slotted endless annular waveguide 203. In this way, plasma was generated in the plasma processing chamber 201. At this time, the nitrogen gas introduced through the plasma processing gas inlet 205 is excited and decomposed in the plasma processing chamber 201 to become active species such as nitrogen atoms, move toward the lens 202, and react with the monosilane gas. Then, a silicon nitride film was formed on the lens 202 with a thickness of about 20 nm.
[0084]
Next, oxygen gas was introduced into the processing chamber 201 through the plasma processing gas inlet 205 at a flow rate of about 200 sccm and monosilane gas at a flow rate of about 100 sccm. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to adjust the inside of the processing chamber 201 to 2.66 × 10. ^-1 It was kept at about Pa. Next, 2.0 kW of electric power was supplied into the plasma generation chamber 201 through a slotted endless annular waveguide 208 from a 2.45 GHz microwave power source (not shown). In this way, plasma was generated in the plasma processing chamber 201. At this time, the oxygen gas introduced through the plasma processing gas inlet 205 is excited and decomposed in the plasma processing chamber 201 to become active species such as oxygen atoms, move toward the glass substrate 202, and the monosilane gas. As a result, a silicon oxide film was formed on the glass substrate 202 with a thickness of about 85 nm. After film formation, gate dielectric breakdown evaluation, film formation speed, and reflection characteristics were evaluated.
[0085]
The film formation rate uniformity of the obtained silicon nitride film and silicon oxide film is as good as about ± 2.7% (about 370 nm / min) and about ± 2.8% (about 410 nm / min), respectively, and the film quality is also It was confirmed that the reflectivity in the vicinity of 500 nm was about 0.17%, which was very good optical characteristics, and no gate dielectric breakdown was observed.
[0086]
(Processing example 5)
The microwave plasma processing apparatus shown in FIG. 1 was used to form a silicon oxide film for semiconductor element interlayer insulation.
[0087]
As the object to be processed 102, a p-type single crystal silicon substrate (plane orientation <100>, resistivity of about 10 Ωcm) having an Al pattern (line and space of about 0.5 μm) formed on the uppermost portion and having a diameter of about 300 mm was used. First, the silicon substrate 102 was placed on the workpiece support 103. The inside of the plasma processing chamber 101 is evacuated through an exhaust system (not shown) to obtain 1.33 × 10 ^-Five The pressure was reduced to a value of about Pa. Subsequently, the heater 104 was energized, the silicon substrate 102 was heated to 300 ° C., and the substrate was kept at this temperature. Oxygen gas was introduced into the processing chamber 101 through the plasma processing gas inlet 105 at a flow rate of about 400 sccm and monosilane gas at a flow rate of about 200 sccm.
[0088]
Next, a conductance valve (not shown) provided in the exhaust system (not shown) was adjusted to maintain the plasma processing chamber 101 at about 2.66 Pa. Next, a power of about 300 W is applied to the substrate support 102 via a high frequency applying means of about 2 MHz, and a power of about 2.5 kW is applied from the 2.45 GHz microwave power source to the slotted endless annular waveguide 103. And supplied into the plasma processing chamber 101.
[0089]
In this way, plasma was generated in the plasma processing chamber 101. The oxygen gas introduced through the plasma processing gas inlet 105 is excited and decomposed in the plasma processing chamber 101 to become active species, move toward the silicon substrate 102, react with the monosilane gas, and the silicon oxide film becomes silicon. A thickness of about 0.8 μm was formed on the substrate 102. At this time, the ion species is accelerated by the RF bias and incident on the substrate, and the film on the pattern is shaved to improve the flatness. After the treatment, the film forming speed, uniformity, withstand voltage, and step coverage were evaluated. The step coverage was evaluated by observing a cross section of the silicon oxide film formed on the Al wiring pattern with a scanning electron microscope (SEM) and observing voids.
[0090]
The resulting silicon oxide film has a uniform film formation rate uniformity of about ± 2.8% (about 310 nm / min), and a film quality of about 9.1 MV / cm, which is a void-free and high-quality film. It was confirmed that no gate breakdown was observed.
[0091]
(Processing example 6)
Using the microwave plasma processing apparatus shown in FIG. ₂ The film was etched.
[0092]
As an object 202 to be processed, an interlayer SiO having a thickness of about 1 μm on an Al pattern (line and space of about 0.35 μm) is used. ₂ A p-type single crystal silicon substrate (plane orientation <100>, resistivity of about 10 Ωcm) having a film of about φ300 mm was used. First, after the silicon substrate 202 is placed on the workpiece support base 203, the etching chamber 201 is evacuated through an exhaust system (not shown) to obtain 1.33 × 10 6. ^-Five The pressure was reduced to a value of about Pa. C through the gas inlet 205 for plasma processing _Four F ₈ About 80 sccm, Ar about 120 sccm, O ₂ Was introduced into the plasma processing chamber 201 at a flow rate of about 40 sccm. Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to make 6.65 × 10 6 in the plasma processing chamber 201. ^-1 The pressure was maintained at Pa.
[0093]
Next, a power of about 280 W is applied to the substrate support 202 through a high-frequency applying means of about 2 MHz, and a slotted endless annular waveguide 203 is supplied with a power of about 3.0 kW from a 2.45 GHz microwave power source. And supplied into the plasma processing chamber 201. In this way, plasma was generated in the plasma processing chamber 201. At this time, processing was performed using the plasma detection element 221 while monitoring the plasma state, the change in light emission due to the constituent atoms of silicon oxide was detected, and the supply of microwaves was stopped. C introduced through the gas inlet 205 for plasma processing _Four F ₈ The gas is excited and decomposed in the plasma processing chamber 201 to become active species, moves in the direction of the silicon substrate 202, and is interlayer SiO by ions accelerated by self-bias. ₂ The film was etched. The substrate temperature increased only to about 30 ° C. by the cooler 207 with the electrostatic chuck. After etching, gate dielectric breakdown evaluation, etching rate, selectivity, and etching shape were evaluated. The etched shape was evaluated by observing a cross section of the etched silicon oxide film with a scanning electron microscope (SEM).
[0094]
The uniformity of etching rate and the selectivity to polysilicon is about ± 2.4% (about 720 nm / min), good at 20, the etching shape is almost vertical, the microloading effect is small, and the gate dielectric breakdown is also Not observed.
[0095]
(Processing example 7)
Using the microwave plasma processing apparatus shown in FIG. 1, the polysilicon film between the gate electrodes of the semiconductor element was etched.
[0096]
As the object 102 to be processed, a p-type single crystal silicon substrate (plane orientation <100>, resistivity of about 10 Ωcm) having a polysilicon film formed on the uppermost portion and having a diameter of about 300 mm was used. First, after the silicon substrate 102 is placed on the workpiece support base 103, the inside of the plasma processing chamber 101 is evacuated through an exhaust system (not shown) to obtain 1.33 × 10 6. ^-Five The pressure was reduced to a value of about Pa. CF through the gas inlet 105 for plasma processing _Four A gas was introduced into the plasma processing chamber 101 at a flow rate of about 300 sccm and oxygen at a flow rate of about 20 sccm.
[0097]
Next, a conductance valve (not shown) provided in the exhaust system (not shown) is adjusted to adjust the inside of the plasma processing chamber 101 to 2.66 × 10. ^-1 The pressure was maintained at about Pa. Next, about 300 W of high frequency power from a 2 MHz high frequency power source (not shown) is applied to the substrate support 103 and about 2.0 kW of power is supplied from the 2.45 GHz microwave power source to the slotted endless annular waveguide 103. Was supplied into the plasma processing chamber 101.
[0098]
In this way, plasma was generated in the plasma processing chamber 101. At this time, processing was performed using the plasma detection element 121 while monitoring the plasma state, the change in light emission due to silicon was detected, and the supply of microwaves was stopped. CF introduced through the gas inlet 105 for plasma processing _Four The gas and oxygen were excited and decomposed in the plasma processing chamber 101 to become active species, moved toward the silicon substrate 102, and the polysilicon film was etched by ions accelerated by self-bias. The substrate temperature rose only to about 30 ° C. by the cooler 104 with the electrostatic chuck. After etching, gate dielectric breakdown evaluation, etching rate, selectivity, and etching shape were evaluated. The etched shape was evaluated by observing a cross section of the etched polysilicon film with a scanning electron microscope (SEM).
[0099]
Etch rate uniformity vs. SiO ₂ It was confirmed that the selectivity was about ± 2.9% (about 820 nm / min) and 22 respectively, the etching shape was vertical, the microloading effect was small, and no gate dielectric breakdown was observed.
[0100]
【The invention's effect】
As described above, according to the present invention, the distance between the surface of the object to be processed and the surface of the microwave waveguide on the plasma processing chamber side is set to an odd multiple of 4 times the microwave conversion wavelength and introduced into the plasma processing chamber. Since the microwave that is reflected and the microwave that is reflected by the surface to be processed are weakened, the irradiation of the microwave on the surface of the object to be processed is reduced even during the initial discharge, and damage caused by the irradiation is reduced. Can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a plasma processing apparatus of the present invention.
FIG. 2 is a schematic diagram showing an example using a lower reflective surface according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing an example using a bowl-shaped reflecting surface according to an embodiment of the present invention.
FIG. 4 is a schematic diagram showing an example using a grooved reflecting surface according to an embodiment of the present invention.
FIG. 5 is a schematic diagram showing a conventional example.
[Explanation of symbols]
101, 201, 301, 401, 901 Plasma processing chamber
102, 202, 302, 402, 902 Object to be processed
103, 203, 303, 403, 903 Workpiece support
104, 204, 304, 404, 904 Substrate temperature adjusting means
105, 205, 305, 405, 905 Processing gas introduction means
106, 206, 306, 406, 906 Exhaust
107, 207, 307, 407, 907 Dielectric window
108, 208, 308, 408, 908 Slotted endless annular waveguide
109, 209, 309, 409 Reflecting means
111,911 E branch
112,912 In-pipe standing wave
113, 913 slots
114, 914 Surface wave
115, 915 Surface standing wave
116,916 Surface plasma
117, 917 Bulk plasma
120, 220, 320, 420 Slot plate
121, 221, 321, 421 Plasma detection element

Claims (7)

  In a plasma processing apparatus for performing plasma processing by introducing a microwave into a plasma processing chamber through a microwave supplier and generating plasma in the plasma processing chamber, the surface of the object to be processed and the microwave supply A plasma processing apparatus, characterized in that a microwave conversion distance to the vessel is an odd multiple of about a quarter of a natural wavelength.   A dielectric window is provided between the microwave supply device and the plasma processing chamber, and the value of the microwave equivalent thickness of the dielectric window is the material of the dielectric window with respect to the frequency of the introduced microwave. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus has a value obtained by multiplying an actual thickness by a square root of a relative dielectric constant.   The plasma processing apparatus according to claim 1, wherein the microwave supplier is a flat multi-slot antenna using an endless annular waveguide. The high frequency is introduced into flop plasma processing chamber via a high-frequency supply unit, in the plasma processing apparatus for generating a plasma in the plasma processing chamber, for detecting the plasma through the slots for high-frequency supply unit which is formed on the high-frequency discharge A plasma processing apparatus having a plasma detection element. The plasma processing apparatus according to claim 4 , wherein the slot is provided in a slot plate disposed at a position facing a surface to be processed of the object to be processed. The plasma processing apparatus according to claim 4 , wherein the plasma detection element is connected to a control device that stops the supply of microwaves based on a detection result of the plasma detection element. In the manufacturing method of a structure which has the process of plasma-processing the surface of the board | substrate in which a structure is formed, the said plasma processing is performed using the plasma processing apparatus of any one of Claim 1 to 6. A method for manufacturing the structure.

Images