Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67011—Apparatus for manufacture or treatment
  • H01L21/67017—Apparatus for fluid treatment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/3244—Gas supply means

Definitions

• the present invention relates to an apparatus and method for the plasma treatment of wafers suitable for generating a plasma between wafers.
• wafers often become both single-treatment processes and batch processes, i. Processes in which multiple wafers are treated simultaneously suspended. Both for individual processes and batch processes, the wafers must each be brought to a desired treatment position. In batch processes, this is usually done by using the wafers in so-called boats, which have recordings for a large number of wafers. In the boats, the wafers are usually arranged parallel to each other. Such boats can be constructed differently, and often they only provide for receiving the lower edges of the respective wafers in such a way that the wafers are exposed upwards. Such boats may, for example, have chamfers to facilitate insertion of the respective lower edges of the wafers into the boats. Such boats are usually passive, meaning that in addition to a holding function, they have no further function during the processing of the wafer.
• the wafer boat is formed by a plurality of electrically conductive plates, which are usually made of graphite.
• the plates are in
• Substantially arranged parallel to each other, and between adjacent plates receiving slots are formed for receiving wafers.
• the mutually facing sides of the plates each have corresponding receiving elements for wafers, so that wafers can be accommodated on each of these sides.
• As receiving elements pins are usually provided on each side of the plate facing another plate, which receive the wafer.
• Adjacent plates of the wafer boat are electrically insulated from one another by means of spacing elements, and an AC voltage, usually in the kHz range or also in the MHz range, is applied between directly adjacent plates during the process.
• a plasma is to be formed between the plates and in particular between the wafers held on the respective plates, in order to provide a plasma treatment, for example a deposition from the plasma or a plasma nitriding of layers.
• a wafer boat which is constructed from plates and spacers, is described in DE 10 201 1 109 444 A1.
• the wafer boat with wafers accommodated therein is usually accommodated in an elongate process tube which can be heated via a heating device and thus can heat the wafers and the process boat.
• a process pipe usually has at least a gas inlet and a gas outlet suitably connected to a gas supply and a gas extraction, respectively. These are usually arranged at the opposite ends of the process tube.
• Such an arrangement of the gas inlet and the gas outlet requires relatively high Gas flows to ensure a substantially constant gas atmosphere over the length of a wafer boat received in the process pipe, in particular to provide sufficiently reactive species for a plasma treatment between all wafers.
• the present invention is therefore based on the object, a plasma treatment apparatus and a method for plasma treatment of
• this object is achieved by a plasma treatment apparatus according to claim 1 and a method according to claim 14.
• the plasma treatment device is for substrates, in particular
• the plasma treatment apparatus further comprises at least one gas guide tube extending in the longitudinal direction in the process space, which is arranged on one side of the receiving area, and at least one longitudinally in the process space extending gas guide tube, which is arranged on the opposite side of the receiving area, wherein the Gas guide tubes each having a plurality of at least in the longitudinal direction of the gas guide tubes spaced passage openings for the passage of gas, wherein the passage openings are formed in the receiving area facing the side of the gas guide tubes.
• At least one gas supply unit and at least one gas discharge unit are provided, wherein the at least one gas supply unit with the at least one gas guide tube and the at least one Gasabriosiki with the at least one other gas guide tube is connectable.
• Such an arrangement of the gas guide tubes allows for a short gas guide path between an insertion and an application and above
• a uniform distribution of a gas or gas mixture within the process space is possible, so that even at lower gas flows sufficiently reactive species can be provided between the wafers.
• the process space may have both a horizontal and a vertical orientation, wherein the gas guide tubes are arranged in a vertical arrangement of the process space corresponding laterally with respect to the receiving space.
• the at least one gas supply unit is connectable to the at least one gas guide tube located below the receiving region and the at least one gas discharge unit can be connected to the at least one gas guide tube located above the receiving region.
• the passage openings in the respective gas guide tubes are provided in an area with a length that is at least equal to or greater than the length of the receiving area.
• the passage openings can be arranged in rows extending transversely to the longitudinal extent of the gas guide tubes.
• the distance between adjacent rows is less than 5 cm, preferably less than 2 cm and in particular less than 1 cm.
• At least one of the gas guide tubes has a circular cross-section that is easy to manufacture.
• at least one of the gas guide tubes has an oval or elliptical cross section.
• At least two gas guide tubes are provided on one side (in particular below) of the receiving region, which can be acted upon by the at least one gas supply unit with different gases, so that they mix only after an exit from the gas guide tubes.
• three gas guide tubes are provided in an embodiment, which are spaced in the transverse direction of the process space, wherein the outer gas guide tubes with a first gas and the inner gas guide tube can be acted upon with a second gas.
• the at least one gas supply unit is configured to introduce a single gas and / or different gases into the process space via the at least one gas guide tube.
• the at least one gas discharge unit may be configured to pump and maintain the process space to a predetermined pressure.
• the plasma treatment device has at least one voltage source which is suitably connectable to the wafer boat for applying an electrical voltage to generate a plasma between wafers housed in the wafer boat.
• the plasma treatment device has at least one movable deflecting element below or adjacent to
• Receiving area of the wafer boat which in a first position at least partially blocked from the bottom to the top or vice versa gas flow laterally of the receiving area of the wafer boat and releases in a second position.
• gas can be directed to the wafer boat in a specific process phase while convective gas flows laterally of the wafer boat are possible in a heating phase become.
• the movable deflecting element can be moved via an actuator that responds to negative pressure and is located in the process chamber.
• a plurality of substrates are accommodated in a wafer boat in the process space of a plasma treatment apparatus of the above type and a desired gas atmosphere is set in the process chamber by introducing at least one Gas over at least one of the gas guide tubes over the entire length of the wafer boat, and during a process phase, a plasma is generated between the recorded wafers in the wafer boat by a high-frequency AC voltage is applied to the wafer boat.
• a desired gas atmosphere is set in the process chamber by introducing at least one Gas over at least one of the gas guide tubes over the entire length of the wafer boat, and during a process phase, a plasma is generated between the recorded wafers in the wafer boat by a high-frequency AC voltage is applied to the wafer boat.
• gas is preferably drawn off from the process chamber via at least one gas guide tube, which is opposite to the at least one gas guide tube through which gas is introduced.
• a desired negative pressure can be set via a corresponding suction.
• the suction can first set a desired negative pressure before the actual process gas is introduced.
• gas is introduced via at least one gas flow pipe at the bottom and gas is drawn off via at least one overhead gas guide pipe.
• the desired gas atmosphere in the process chamber is controlled or completely exchanged between a warm-up phase in which no plasma is generated and a process phase in which the plasma is generated.
• a gas atmosphere of an inert gas having a first pressure may be provided, and in the process phase, a gas atmosphere of a reactive gas and a second pressure smaller than the first pressure.
• the inert gas at elevated pressure promotes heating of the wafer boat and wafers while avoiding undesirable reactions while the reactive gas promotes plasma formation at a lower pressure.
• the movable deflecting element should preferably release a gas flow directed from bottom to top or vice versa laterally of the wafer boat in order to facilitate convective gas flows.
• Fig. 1 is a schematic side view of a wafer boat
• FIG. 2 is a schematic plan view of the wafer boat according to FIG. 1;
• FIG. 2 is a schematic plan view of the wafer boat according to FIG. 1;
• FIG. 3 is a schematic front view of the wafer boat according to FIG. 1;
• FIG. 3 is a schematic front view of the wafer boat according to FIG. 1;
• FIG. 4 shows a schematic view of a plasma treatment apparatus with wafer boat according to FIG. 1 accommodated therein;
• FIG. 5 is a schematic front view of a process chamber of the plasma treatment apparatus according to FIG. 4;
• FIG. 5 is a schematic front view of a process chamber of the plasma treatment apparatus according to FIG. 4;
• FIG. 6 shows a schematic top view of a part of a gas feed of the process chamber according to FIG. 5;
• FIG. 7 is a schematic front view of an alternative process chamber of the plasma processing apparatus of FIG. 4; FIG.
• Fig. 8 is a schematic front view of another ' alternative
• Process chamber of the plasma treatment apparatus according to FIG. 4; 10 is a schematic side view of an alternative Waferbootes, for
• FIG. 1 1 a to c schematic side views of parts of the alternative
• FIG. 12 is a schematic plan view of a portion of the wafer boat of FIG. 9; FIG. ,
• Fig. 13 is a schematic side view of another alternative
• Wafer boats for use in a plasma treatment device
• Fig. 14 is a schematic side view of a part of the alternative
• FIG. 15 is a schematic plan view of another alternative wafer boat;
• FIG. 16 is a schematic side view of a portion of the wafer boat of FIG. 15;
• FIG. 16 is a schematic side view of a portion of the wafer boat of FIG. 15;
• Fig. 17 (a) and (b) are schematic cross-sectional views through a
• Fig. 18 is a schematic plan view of another wafer boat
• FIG. 19 is a schematic side view of a portion of the wafer boat of FIG. 19; FIG. and
• FIG. 20 (a) and (b) are schematic cross-sectional views taken through a process chamber of a plasma processing apparatus according to FIG. 4 with a wafer boat according to FIG. 18 therein.
• Terms used in the specification such as top, bottom, left and right, refer to the illustration in the drawings and are not intended to be limiting. But you can describe preferred versions.
• the formulation essentially based on parallel, perpendicular or angle specifications should include deviations of ⁇ 3 °, preferably ⁇ 2 °.
• wafer is used for disc-shaped substrates, which are preferably semiconductor wafers for semiconductor or photovoltaic applications, but also substrates of other materials can be provided and processed.
• FIG. 1 shows a schematic side view of a wafer boat 1
• FIGS. 2 and 3 show a plan view and a front view, respectively.
• the same reference numbers are used in the figures as far as the same or similar elements are described.
• the wafer boat 1 is formed by a plurality of plates 6, contacting units and clamping units.
• the illustrated wafer boat 1 is specifically for a layer deposition of a plasma, for example of Si 3 N 4 , SiN x , a-Si, Al 2 O 3, AIO x , doped and undoped poly-silicon or amorphous silicon, etc, and in particular a plasma nitridation of
• the plates 6 each consist of an electrically conductive material, and are in particular formed as graphite plates, wherein depending on the process, a coating or surface treatment of the plate base material may be provided.
• the plates 6 each have six recesses 10, which are covered in the process of the wafers, as will be explained in more detail below. Although six Aussparrungen per plate 6 are provided in the illustrated form, it should be noted that a greater or lesser number may be provided.
• the plates 6 each have parallel upper and lower edges, wherein in the upper edge, for example, a plurality of notches can be formed seirv to allow a position detection of the plates, as described in DE 10 2010 025 483.
• a total of twenty-three plates 6 are provided, which are arranged via the corresponding contacting units and clamping units substantially parallel to each other
• receiving slots 1 1 Between receiving slots 1 1 to form. Twenty-three plates 6 thus twenty-two of the receiving slots 1 1 are formed. In practice however, 19 or 21 plates are often used, and the invention is not limited to a certain number of plates.
• the plates 6 each have at least on their side facing an adjacent plate 6 groups of three receiving elements 12, which are arranged so that they can receive a wafer in between.
• the groups of the receiving elements 12 are each arranged around each recesses 10 around, as schematically indicated in Fig. 1.
• the wafers can be received in such a way that the receiving elements each contact different side edges of the wafer.
• the plates 6 each have a projecting contact lug 13, which serves for electrical contacting of the plates 6, as will be explained in more detail below.
• two embodiments of plates 6 are provided which differ with regard to the position of the contact lugs 13.
• the contact lugs 13 are each made in direct connection to the lower edge, while they are spaced from the lower edge in the other embodiment, wherein the distance to the lower edge is greater than the height of the contact lugs 3 of the plates of the other embodiment.
• the two embodiments of plates 6 are alternately arranged in the wafer boat 1.
• the contact lugs 13 are located directly adjacent plates 6 in the arrangement of the wafer boat 1 on different - levels.
• the contact lugs 13 are in the same plane.
• two spaced contact planes are formed by the contact lugs 13.
• This arrangement allows directly adjacent plates 6 can be applied to different potential, while each second plate can be applied to the same potential.
• the lying in a respective contact plane contact tabs 1 3 are electrically connected via contact blocks 15 of a highly electrically conductive material, in particular graphite, and arranged with a predetermined distance from each other. In the region of the contact tabs 13 and in each of the contact blocks 15, at least one passage opening is provided in each case.
• the plates 6 can then be fixed to one another.
• the plates are fixed in two different groups to each other in such a way that the plates of the different groups are arranged alternately.
• the clamping element 16 may consist of electrically conductive material which is not necessary.
• the contact blocks 15 each preferably have the same length (in the direction that defines the distance between contact tabs 3 of the plates 6) corresponding to the width of two receiving slots 1 plus the width of a plate 6.
• the contact blocks 15 are preferably formed so that they have a low thermal mass and in particular the sum of the contact blocks should have a lower thermal mass than the sum of the plates 6.
• the combined thermal mass of the sum of the contact blocks and the sum of contact projections 13 of the plates should be smaller than the thermal mass of the sum the plates 6 less the thermal mass of the respective contact lugs 13th
• the shank parts of the tensioning element 19 are each dimensioned such that they can extend through corresponding openings of all the plates 6 and respective spacer elements 22 located between them.
• the clamping elements 19 are preferably made of an electrically insulating material.
• the spacer elements 22 are preferably made of an electrically conductive material.
• the spacer elements 22 are preferably made of a high-resistance material, such that the spacer elements with the application of a DC or low-frequency voltage with
• a frequency range of 50 Hz to 10 KHz and for the high frequency voltage is an area
• each spacer element should have a resistance of greater than 3 kü, in particular greater than 20 kü or even greater than 40 kQ.
• the spacers can be made of doped silicon, polysilicon or another suitable material that on the one hand is not affected by the process and on the other hand does not affect the process, in particular does not introduce impurities into the process. While the plates 6 of a group (upper contact nose 13 / lower contact nose 1 3) are electrically connected and fixed to one another via the contact elements 1 5, all plates are electrically connected and fixed to one another via the spacer elements 22.
• FIG. 4 being a schematic side view of the treatment device 30
• FIG. 5 shows a schematic front view of a process chamber structure
• FIG. 6 shows a plan view of a gas supply line.
• the treatment device 30 consists of a process chamber part 32 and a control part 34.
• the process chamber part 32 consists of a tube element 36 which is sealed on one side and forms a process chamber 38 in the interior.
• the open end of the tubular element 36 serves to load the
• Process chamber 38 and it can be closed and hermetically sealed via a locking mechanism, not shown, as is known in the art.
• the tube element is made of a suitable material that does not introduce impurities into the process, is electrically insulated and can withstand the process conditions of temperature and pressure (vacuum), such as quartz.
• the tube member 36 has at its closed end gas-tight passages for the supply and discharge of gases and electricity, which may be formed in a known manner. However, corresponding inlets and outlets could also be provided at the other end or else laterally at a suitable location between the ends,
• the tube member 36 is surrounded by a sheath 40, which is the
• Tube member 38 thermally insulated from the environment.
• a heating device such as a resistance heater, which is suitable to heat the tube member 36.
• a heating device can also be provided, for example, in the interior of the tubular element 36, or the tubular element 36 itself could be designed as a heating device.
• an external heating device is preferred and in particular one which has different, individually controllable
• receiving elements not shown are provided, which form a receiving plane for receiving a wafer boat 1 (which is only partially shown in Fig. 4), which may be, for example, of the above type form.
• the wafer boat can also be inserted into the tubular element 36 so that it rests on the wall of the tubular element 36.
• the wafer boat is held substantially above the receiving plane and is arranged approximately centrally in the tubular element, as can be seen for example in the front view of FIG.
• the wafer boat may Jdgs' via a suitable n, handling mechanism shown traded as a whole when loaded into the process chamber 38 into and out of.
• a suitable n, handling mechanism shown traded as a whole when loaded into the process chamber 38 into and out of.
• an electrical contact with in each case at least one contact block 15 of each of the groups of plates 6 is automatically produced, as will be explained in more detail below.
• a lower gas guide tube 44 and an upper gas guide tube 46 are further provided which are made of a suitable material such as quartz.
• the gas guide tubes 44, 46 extend in the longitudinal direction of the tube member 36 and indeed at least ⁇ over the length of the wafer boat 1.
• the gas guide tubes 44, 46 each have a round cross section and are each arranged in the transverse direction approximately centrally below or above the wafer boat 1.
• the gas guide tubes 44, 46 are at their closer to the closed end of the Rohrele- element 36 lying end with a gas supply unit or a Gasabrioshim in combination, as will be explained in more detail below.
• the respective opposite end of the gas guide tubes 44, 46 is closed.
• a short gas guide is also conceivable in which, for example, gas is admitted only at one end of the tubular element and is distributed by diffusion and / or pumped via a vacuum connection (preferably at the opposite end of the tubular element 36).
• the lower gas guide tube 44 has a plurality of openings 48 through which gas can escape from the gas guide tube.
• the openings are all located in an upper half of the gas guide tube, so that a gas emerging therefrom has an upward component.
• the openings should be formed in an area in the longitudinal direction of the gas guide tube 44, which has at least a length corresponding to the length of the wafer boat.
• the region has a greater length than the wafer boat and is arranged so that the region extends beyond the ends of the wafer boat.
• the sum of the area of the openings 48 is smaller than the cross-sectional area of the gas guide tube 44.
• Gas supply pipe 44 between 30 and 70% and in particular between 40 and 60%, When pressurized with a gas then sets a constant pressure in the gas supply pipe 44 and it can be achieved a uniform gas distribution over the apertured area.
• a distance of the rows of openings 48 from approximately 5 mm at an opening diameter of about 1.5 mm. In this case, the distance between the centers of the respective openings of the different rows is measured. The distance can also be chosen differently and especially at lower
• the distance could be larger.
• the distance should be less than 5 cm, preferably less than 2 cm and in particular less than 1 cm.
• the upper gas guide tube 46 has a similar construction with openings, in which case the openings are formed in the lower half.
• the gas guide tubes 44, 46 may be identical, but arranged in a different orientation, respectively, so that the openings point to the wafer boat 1, respectively.
• both the openings in the lower gas guide tube 44 and in the upper gas guide tube 46 to the receiving cavities ie the area in which a properly inserted wafer boat is placed.
• a different arrangement or different shapes of the openings for example, slots to provide. Via such gas guide tubes 44, 46, a good homogeneous gas distribution can be achieved within the process chamber, in particular in the receiving slots 1 1 of the wafer boat.
• the lower gas guide tube is acted upon with gas, while gas is drawn off via the upper gas guide tube 46 gas.
• the lower gas guide tube 44 ensures a good distribution of gas below the wafer boat, and the suction on the upper gas guide tube 46 ensures that the gas between the plates 6 of the wafer boat 1 is transported upwards.
• two optional, movable deflecting elements 50 are provided in the process space.
• the deflection elements 50 which are not shown in FIG. 4 for the sake of simplicity of illustration, have an elongated configuration.
• the deflecting elements 50 extend in the longitudinal direction of the process tube 36 and preferably have a length which corresponds at least to the length of the wafer boat.
• the deflecting elements 50 should preferably have a length which corresponds at least to the length of the region of the lower gas guiding tube 44 in which the openings 48 are formed.
• the deflection elements 50 are arranged below and in the transverse direction laterally to the wafer boat 1 in the process chamber 38.
• the deflecting elements 50 are each mounted rotatably and can by means of a Einstellmecha- mechanism, not shown between a first position, which is shown in Figures 5 and 7 to 9 in a solid line, and a second position, shown in the figures 5 and 7-9 is shown with a dashed line. In the first position, the baffles substantially prevent gas flow laterally around the wafer boat while allowing one in the second position.
• the adjustment mechanism may, for example, be adjusted to the pressure in the
• Process chamber 38 be responsive mechanism that brings the deflecting elements 50, for example, automatically at a certain negative pressure in the process chamber 38 in the first position. But there are also other adjustment mechanisms that are mechanically or electrically operated conceivable, for which then appropriate supply lines for the control must be provided.
• Figures 7 to 9 show schematic front views of alternative process chamber structures, which differ only in terms of the shape and / or number of gas guide tubes. In the embodiment according to FIG. 7, two lower and two upper gas supply pipes 44, 46 are provided in each case.
• the lower gas guide tubes 44, 44 lie in a horizontal plane below the wafer boat 1 and are arranged symmetrically with respect to a vertical center plane of the process chamber. With regard to the openings, they can be constructed and arranged equal to the gas guide tube described above.
• the upper gas guide tubes 46, 46 lie in one horizontal plane above the wafer boat 1 and they are also arranged symmetrically with respect to a vertical center plane of the process chamber. In particular, in this or a similar arrangement with several lower gas guide tubes for the gas supply via the different gas guide tubes different gases can be introduced into the process chamber 38, which thus mix only in the process chamber to avoid premature reaction within the gas supply.
• the gas guide tubes 44, 46 each have an elliptical cross-sectional shape, wherein the respective major axes are arranged horizontally.
• the gas guide tubes 44, 46 are in turn centrally below or above the wafer boat. 1 In other words, they are arranged symmetrically with respect to a vertical center plane of the process chamber. With regard to the openings, they can be constructed and arranged essentially the same as the gas guide tubes described above.
• the lower gas guide tubes 44 are below the wafer boat 1, wherein the two exits lie in a plane while the middle is slightly offset downwards. But it would also be another arrangement possible. With regard to the openings, they can be constructed and arranged equal to the gas guide tube described above.
• the upper gas guide tube 46 lies above the wafer boat 1 and has an elliptical cross-sectional shape, as in FIG. 8, and is arranged symmetrically with respect to a vertical center plane of the process chamber. Alternatively, several gas guide tubes or another form of the gas guide tube could also be provided here.
• the control part 34 of the treatment device 30 has a gas control unit 60, vacuum control unit 62, an electrical control unit 64 and a temperature control unit, not shown, which can all be controlled jointly via a higher-level control, such as a processor.
• the temperature control unit is in communication with the heater unit, not shown, to primarily control the temperature of the pipe member 36 and the process chamber 38, respectively.
• the gas control unit 60 communicates with a plurality of different gas sources 66, 67, 68, such as gas cylinders containing different gases.
• the gas sources may include di-chlorosilane, tri-chlorosilane, SiH 4 , phosphine, borane, di-borane, German (GeH 4), Ar, H 2 , TMA NH 3 , N 2, and various other gases at respective gas control unit inputs 60 deploy.
• the gas control unit 60 has two outputs, one of the outputs being connected to the lower gas guide tube 44 and the other to a pump 70 of the vacuum control unit 62.
• the gas control unit 60 may suitably connect the gas sources to the
• the vacuum control unit 62 consists essentially of the pump 70 and a pressure control valve 72.
• the pump 70 is connected via the pressure control valve 72 to the upper gas guide tube 46 and can thereby pump off the process chamber to a predetermined pressure.
• the connection from the gas control unit 60 to the pump serves to dilute process gas pumped from the process chamber, optionally with N 2 .
• the electric control unit 64 has at least one voltage source suitable for providing, at an output thereof, at least one of a DC voltage, a low frequency voltage, and a high frequency voltage.
• the output of the electrical control unit 64 is connected via a line to a contacting unit for the wafer boat in the
• the line is inserted through a corresponding vacuum and temperature suitable passage through the sheath 40 and into the tube member 36.
• the line is in particular constructed so that it is designed as a coaxial line 74 with an inner conductor and an outer conductor.
• the coaxial line 74 Over the length of the coaxial line 74, there is approximately field freedom on the outside, so that no parasitic plasmas arise even at high frequencies in the MHz range and transmission takes place as lossless as possible.
• Inside the coaxial line wave propagation takes place with the wavelength ⁇ .
• the wave propagation continues between plate pairs (planar waveguide), but at a different wavelength, which depends on the presence and type of the plasma.
• a suitable dielectric is provided which, when subjected to high-frequency voltage, the
• Propagation speed and the wavelength of the electromagnetic wave in the coaxial conductor relative to a corresponding propagation speed and wavelength of the electromagnetic wave in vacuum reduced.
• the reduction of the propagation velocity and the wavelength of the electromagnetic wave in the coaxial conductor relative to a corresponding propagation velocity and wavelength of the electromagnetic wave in vacuum is equivalent to increasing the effective electrical length of the coaxial conductor 74 relative to vacuum Wavelength.
• the geometric length of the coaxial conductor should be close to an odd multiple of ⁇ / 4 of the wavelength reduced by the dielectric, or in other words, the effective electrical length of the coaxial conductor close to an odd multiple of ⁇ / 4 be set to the wavelength of the applied frequency.
• Outer conductor of coaxial conductors usually have a round cross-section
• the term coaxial conductor is also to include inner and / or outer conductor with other cross-sections.
• the inner and / or outer conductors may have rectangular or oval cross-sections and extend along a common longitudinal axis.
• the local propagation speed of the high-frequency wave, and thus integrally the effective electrical length of the coaxial conductor 74 depends essentially on the dielectric between the inner and outer conductors. As the dielectric constant increases, the propagation velocity decreases with 1 / ( ⁇ ⁇ ) / 2 and accordingly the effective electrical length of the coaxial conductor 74 increases.
• a desired average dielectric constant can be set over the length by suitably arranging short insulator pieces of different dielectric constant over the length.
• the Jsolator may have a shape corresponding to the inner and outer conductors, such as a ring shape, which allows sliding on the inner conductor.
• the coaxial line 74 leads substantially to the contact areas of the wafer boat 1.
• the inner and outer conductors are connected in a suitable manner to the different groups of plates 6. The wave propagation between the plate pairs affects the properties of the plating plasma, for example in the homogeneity / uniformity over the wafer and the wafer boat.
• the contact lugs 13 of the wafer boat 1 should be reduced as far as possible in terms of mass and length for the coupling of high-frequency power in order to keep the local heat capacity and the supply inductance as low as possible.
• the lead inductance formed by the sum of the contact tabs 13 in combination with the contact elements 15 should be substantially smaller than the inductance of the sum of the plates 6.
• the impedance of the corresponding lead inductance at the operating frequency should be less than half and preferably less than 1/10 of the impedance of the plate stack of plates 6.
• Figures 10 to 12 show an alternative wafer boat 100 that in a
• Plasma treatment apparatus 30 of the above type but also in classical plasma treatment apparatus can be used.
• the wafer boat 100 is formed by an electrically conductive support unit 101 with a plurality of electrically conductive supports 102, 104, for example made of graphite or another good electrically conductive material, an insulated guide unit 106.
• the support unit 101 and the insulated guide unit 106 are connected via insulated connecting elements 108 and together form the wafer boat 100.
• the electrically conductive supports 102, 104 are best seen in the schematic side views of Figures 11 a to 1 1 c.
• 1 1 a shows a schematic side view of the support 102
• FIG. 1 b shows a schematic side view of the support 104
• FIG. 1 c shows a schematic side view of the supports 102, 104 in an end arrangement.
• the supports 102, 104 each have an elongated base body 1 10 having a substantially rectangular cross-sectional shape.
• the main body 1 10 each has a straight central part, in the top of a slot 1 12 for receiving wafers (W) is formed.
• the slot depth is chosen to be less than or equal to a customary edge exclusion during wafer production and is therefore approximately 1 to 5 mm.
• the width of the slot is in turn selected so that two wafers (W) to be processed can be received back-to-back therein, as indicated in the plan view according to FIG. 12.
• the slot 1 12 may be inclined transversely to the longitudinal direction by 1 ° to 2 °, so that a wafer pair received therein is slightly inclined in the slot 1 12.
• Pads 104 in a lower level, as shown in Fig. 1 1 c can be seen.
• the main bodies 1 10 each have a plurality of transverse bores 1 16 are provided, which serve for the implementation of clamping elements 1 18, and 120, respectively. These can be of the type described above with head and shaft part, which can interact with counter-elements. While the clamping elements 1 18 are used in the central region 1 1, the clamping elements 120 are used in the region of the end portions 1 14.
• a plurality of, for example, 22 of the pads 102, 04 are arranged transversely to their longitudinal extent parallel to one another, with the pads 102 and 104 alternating in the assembly.
• spacers (not shown) are provided between directly adjacent pads 102, 04, which are aligned with the transverse bores 16 1.
• These spacers are sleeve-shaped and are dimensioned so that they are in the assembled state of the Waferbootes 1 00 are placed on the shaft portion of the clamping element 1 1 8.
• the spacers may be electrically insulating or else electrically conductive, such as the spacer elements 22 of the wafer boat 1 described above, if they are to have a similar heating function.
• each electrically conductive sleeves 124 are provided, which are dimensioned so that they can be plugged onto the shaft portion of the clamping elements 120.
• the sleeves 124 each have a length equal to the length of two spacers plus the width of an overlay.
• they are capable of electrically connecting two pads 102, 102 or 104, 104 in the array respectively.
• the pads 102 form a first group of pads, each electrically connected, and the pads 104, a second group of pads, each electrically connected. This in turn allows the application of a voltage between the different groups, as well as the wafer boat. 1
• the guide unit 106 is formed by two elongate holding members 130 and seven guide rods 132 each made of a dielectric material.
• the holding elements 130 and the guide rods 132 may be made of ceramic or quartz, for example.
• the holding elements 130 each have an elongated configuration with a length substantially equal to the length of the pads 102, 104 and they extend substantially parallel to the pads 102, 104, wherein the retaining members 130 are arranged higher than the pads 102, 104.
• the guide rods 132 extend vertically between the holding elements 130, as can be seen in the plan view of FIG. 12 and are suitably connected to these.
• the guide rods 132 may have a circular cross-section, but other shapes are possible.
• the guide rods 132 each have a plurality of notches 134 which are dimensioned to receive and guide an edge region of wafer pairs W, W, in particular an edge scraping region thereof.
• the guide rods 132 are spaced so that they each have a pair of wafers W, W can take in between, as indicated in Fig. 12. It should be noted that the top view of FIG. 12 does not fully show the wafer boat 100 and the wafer boat is only partially loaded to simplify the illustration.
• the notches 1 34 are in the transverse direction of the
• Notches 134 correspondingly slightly offset from the slots 1 12, to allow a recording of the wafer pairs W, W in a slightly inclined position.
• the support unit 101 consisting of the associated supports 102, 1 04 and the insulated guide unit 1 06 consisting of the support members 1 30 and the guide rods 132 are connected in the end regions in each case via insulated connecting elements 108.
• the connecting elements 108 each have a plate shape and they cooperate with the clamping elements 118 and 120 and additional clamping elements for connection to the holding element 130 in order to fix the arrangement as a whole and thus to form the wafer boat 100.
• the wafer boat 100 can be used in the same way as a classic wafer boat, or also in the form described below, if the spacers are electrically conductive, such as the spacers 22 in the wafer boat 1.
• FIGS. 13 and 14 show a schematic side view of a single plate of the wafer boat.
• the wafer boat 200 is essentially formed by electrically conductive plates 202, 204, for example made of graphite or another good electrically conductive material, which are arranged alternately parallel to each other via spacers and clamping elements 206, not shown. This can be done in the manner described above, wherein the spacers may be made of a dielectric material or a high-resistance electrically conductive material, depending on whether they should have a Sakikifunktion or not, as explained below.
• the plates 202, 204 each have upwardly open recesses 208.
• a group of three receiving pins 210 are provided in the region of each recess, which provide a three-point system for wafers W to be accommodated.
• one of the receiving pins below the recess 208 and the other two receiving pins are located on opposite sides of the recess 208 and higher than the lower receiving pin 210.
• the vertical distance between the lower receiving pin 210 and the upper edge of the respective plates 202, 204 is smaller
• recorded wafers are thus not completely accommodated between two plates, but they project upwards clearly beyond the plates, as can be seen in FIG.
• the wafer boat 200 can thus have a significantly reduced thermal mass.
• the plates 202, 204 each have contact lugs 213 at their ends, wherein the contact lugs 213 of the two plates are in turn at different heights so as to be electrically conductive contact elements (not shown) in turn to enable a group-wise contacting of the plates.
• the contact lugs are preferably kept short and are rounded towards the outside, but may also have other shapes. «In addition, the distance in the height direction between the contact tabs is shortened, which is advantageous when applying an RF voltage, especially in the MHz range. In particular, if a coaxial feed line is provided, as in the plasma treatment device 30 described above.
• FIG. 15 is a schematic plan view of the wafer boat 300
• FIG. 16 is a schematic sectional view of a portion thereof
• FIGS. 17 (a) and (b) are schematic sectionsal views of a portion thereof.
• Wafer boat (and thus parallel to the longitudinal extent of the plasma treatment apparatus) are taken, the wafer boat of the type in which the wafers are taken transversely to the longitudinal extent of the wafer boat 300.
• the wafer boat 300 has a classic design, as used for example in thermal diffusion systems for semiconductor wafers.
• the wafer boat 300 has an elongated configuration, i. it has in longitudinal extension (left-right in Figure 15) has a much greater length than in the other dimensions.
• an end plate 303 is provided, which is preferably formed of quartz. But it can also be constructed of another suitable non-conductive material.
• the end plates 303 Between the end plates 303 extend in each case two transversely spaced receiving elements 305 and two spaced contact and guide elements 307, which are respectively secured to the end plates 303.
• the contact and guide elements 307 lie in the transverse direction between the receiving elements 305th
• the receiving elements 305 extend, as mentioned above, between the end plates 303 and are secured thereto, in particular by
• the receiving elements 305 may also consist of quartz and each have an elongated rod shape.
• the receiving elements 305 essentially have a rectangular cross-section, wherein "substantially” should also include in particular rectangles with rounded corners, but in principle it would also be possible for the receiving elements 305 to be round or have other shapes are mutually inclined and each have a plurality of receiving slots 313 in their upwardly directed narrow side, which extend transversely to the longitudinal extension of the receiving element 305, preferably substantially at a 90 ° angle to the longitudinal extension
• the receiving slots 313 are each equidistant
• each other has a predetermined (constant) depth for receiving a peripheral region of a respective wafer to be picked or a pair of wafers, which can be accommodated in the slot, for example in a back-to-back arrangement.
• the depth will be approximately equal to or less than an edge exclusion area of the wafers.
• the receiving slots may be inclined in the longitudinal direction by 1 ° to 2 °, so that a recorded therein wafer or a pair of wafers is arranged correspondingly inclined to the vertical.
• contact and guide elements 307 will now be described in more detail, of which two are shown in the plan view of FIG.
• the contact and guide elements 307 are each in
• rod-shaped element 320 of an electrically conductive material, such as graphite, whose ends are electrically contacted in a suitable, not shown manner.
• the rod-shaped elements 320 each have a substantially round cross-section, as best seen in the sectional view of FIG. 17.
• each rod-shaped element 320 is a plurality of
• Slits 322 (contact slot) and slots 323 (insulating slot) are provided, which alternate in the longitudinal direction, as best seen in Fig. 16.
• the slots 322 each have a first depth and a first width
• the slots 323 have a second depth and a second width, wherein the second depth is greater than the first and the second width is greater than the first, as explained in more detail below becomes.
• the slots 322, 323 have the same spacings as the slots 313 of the receiving elements 303, here in each case the distance from the slot center of a respective slot to the slot center of the next slot is meant.
• the slots 322, 323 in the spaced contact and guide elements 307 are offset from one another.
• the slots 313, 322, and 323 are aligned with each other such that a wafer (a pair of wafers) housed in the wafer boat respectively in two slots 313 (the spaced receiving members), a slot 322 (a contact and guide member 307) and a slot 323 (of the other contact and guide member 307) is received.
• the depth and width of the slot 322 is selected such that the wafer (the pair of wafers) securely contacts the contact and guide element 307.
• the depth and width of the slit 323, on the other hand, are chosen so that the wafer (the pair of wafers) does not contact the contact and guide element 307, as indicated in FIG. 16.
• FIGS. 17 (a) and (b) show, for example, cross-sectional views through adjacent slots in the wafer boat.
• the cut is such that it cuts a slot 322 in the left contact and guide member 307 and a slot 323 in the right contact and guide member 307.
• the adjacent slot view Fig. 17 (b)
• a slot 323 cut and in the right contact and guide member 307 a slot 322.
• the contact and guide elements 307 may be formed relatively thin. However, to provide sufficient stability over the entire length of the wafer boat, in the illustrated embodiment of the wafer boat 300, a second rod-shaped member 330 is provided vertically below the contact and guide members 307 and extends between the end plates 303.
• the element 330 is preferably formed of an electrically insulating material having sufficient stability that does not introduce impurities into the process and also has sufficient thermal stability, such as quartz or another suitable material.
• the contact and guide element 307 can, as shown, rest directly on the element 330, or a plurality of supports can be provided between the lower element 330 and the contact and guide element 307.
• FIG. 18 is a schematic plan view of the wafer boat 300
• FIG. 19 is a schematic sectional view of a portion thereof
• FIG. 20 (a) and (b) are schematic cross-sectional views of a plasma processing apparatus having such a wafer boat 300. Also in this wafer boat 300 The wafers are taken transversely to the longitudinal extent of the wafer boat 300.
• the wafer boat 300 again has an elongated configuration, wherein at the ends of the wafer boat 300 each have an end plate 303 is provided, which may be formed as described above. Extending between the end plates 303 are two transversely spaced first receiving members 305, two transversely spaced second receiving members 306, and two spaced contact and guide members 307 secured to the end plates 303, respectively. In the transverse direction, the contact and guide elements 307 between the second receiving elements 306 and the second receiving elements 306 are in each case between a first receiving element 305 and a contact and guide element 307.
• the contact and guide elements 307 have the same structure as described above, with upper and lower rod members 320, 330 and contact slots 222 and insulating slots 223, which are arranged offset in the respective contact and guide elements 307 to each other. As a result, every second wafer accommodated in the wafer boat is contacted by one of the contact and guide elements 307 while the other wafers are contacted by the other contact and guide element 307.
• the first and second receiving elements 305, 306 extend between the end plates 303 and are secured thereto as described above.
• the first and second receiving elements 305, 306 may again consist of quartz and each have an elongated rod shape, the first and second receiving elements 305, 306 each have a basic shape, as in the wafer boat 300 according to Figures 1 5 to 17. They also have a plurality of slots 330 corresponding to the
• the slots 330 have two slot types that differ in size and function.
• the first slot type serving as a receiving slot 332 has a first depth and a first width adapted to receive an edge portion of a respective wafer or wafer pair to be contacted, for example in a back-to-back arrangement, in the slot.
• the depth will be approximately equal to or less than an edge exclusion area of the wafers.
• the second slot type serving as the insulating slot 333 has a second depth and a second width, which are larger than the first depth and the first width, respectively.
• the insulating slots 333 are each suitably a peripheral portion of a respective wafer to be picked or a pair of wafers. without contacting it in the slot,
• the receiving slots 332 and the insulating slots 333 alternate in the longitudinal direction of the receiving elements 305, 306, as can be seen in the view in FIG. 19.
• the receiving slots 332 and the insulating slots 333 of the first receiving elements 305 are aligned with each other.
• the receiving slots 332 and the insulating slots 333 of the second receiving elements 306 are aligned with each other.
• the receiving slots 332 of the first receiving elements 305 are aligned with the insulating slots 333 of the second receiving elements 306 and the insulating slots 333 of the first receiving elements 305 with the receiving slots 332 of the second receiving elements 306, in other words, the receiving and insulating Slits 332, 333 of the first receiving elements 305 to the receiving and insulating slots 332, 333 of the second receiving elements 306 offset.
• every second wafer received in the wafer boat is picked up and carried by the first receiving elements 305 while the other wafers are picked up and carried by the second receiving elements 306.
• all wafers which are received and supported by the first receiving elements 305 contact the same contact and guide element 307, while the further wafers received and supported by the second receiving elements 306 contact the other contact and guide element 307.
• a corresponding mutual carrying and contacting is shown in FIGS. 20 (a) and (b) indicated.
• This configuration may in operation prevent a short circuit between adjacent wafers via the first and second receptacles 305, 306 in the event that during a plasma treatment (which, for example, is to deposit conductive layers on the wafers) conductive layers on the first and second receptacles Separate 305, 306.
• a plasma treatment which, for example, is to deposit conductive layers on the wafers
• Receiving elements 305, 306 form additional conductive to apply here also on a voltage between received in the wafer boat 300 wafers, for example, thus increasing the contact area to the wafers and the "surface for the introduction of electrical power.
• the plasma treatment device 30 will now be described in greater detail with reference to the drawings, by way of example a plasma-assisted silicon nitride or aluminum oxide deposition in a plasma excited by 1 3.56 MHz as a treatment.
• the treatment device 30 can also be used for other plasma-assisted deposition processes, the plasma also being excited by other frequencies, for example in the 40 kHz range can be.
• the coaxial line 74 is provided and optimized especially for frequencies in the MHz range.
• a loaded wafer boat 1 of the type described above (as shown in FIG. 1) is loaded into the process chamber 38 and is closed by the closing mechanism, not shown.
• the wafer boat 1 is loaded so that in each of the receiving slots 1 1 a total of 12 wafers, in the present example, in particular Si wafer, are added, namely six at each of the plates. 6
• the wafers are picked up so that they face each other in pairs, as known in the art.
• the interior is at ambient pressure and can be purged or flooded with N 2 , for example via the gas control unit 60 (in combination with the vacuum control unit 62).
• the tube member 36, and thus the process chamber 38, are heated by the heater, not shown, to heat the wafer boat 1 and the wafers received therein to a predetermined, process-beneficial process temperature.
• the deflecting elements are in the second position (shown in dashed lines in FIG. 5) in order not to impair heating via convection. In this case, however, a heating of the inner plates 6 of the wafer boat 1 and the wafer picked up therebetween via a heating of the tubular element 36 can be tedious.
• a DC or low frequency AC voltage may be applied to the wafer boat 1 to assist in heating via the electrical control unit 64.
• the voltage is sufficiently high so that current is conducted via the high-resistance spacer elements 22 and these act as resistance heating elements.
• heating power is specifically in the
• Receiving slots 1 1 introduced so that compared to a heating from the outside much faster the predetermined temperature can be achieved can.
• voltages in the range of at least 200 V to approximately 1 kV are considered to achieve sufficient current flow and heating of the spacers 22.
• the electrical control unit 64 can first be deactivated and the process chamber is pumped to a predetermined negative pressure via the vacuum control unit 62.
• the deflection elements 50 are automatically by the self-adjusting negative pressure or active in the first position
• a desired process gas such as SiH 4 / NH 3 for a silicon nitride deposition in a defined mixing ratio is initiated via the gas control unit 60 depending on the required layer properties, while the negative pressure control unit 62 further vacuum by sucking the introduced Process gas is maintained.
• the process gas extracted via the pump 70 may be diluted with 2 at this time, as known in the art.
• the gas control unit 60 and the corresponding line of the pump N 2 is supplied. Due to the special arrangement of the gas guides 44, 46 in combination with the deflecting elements 50 is within the
• Process chamber mainly generates a gas flow through the receiving slots 1 of the wafer boat 1. This can be formed homogeneously by the special arrangement of the gas ducts 44, 46 over the width and length of the wafer boat.
• an RF voltage with a frequency of 13.56 MHz is now applied to the wafer boat 1.
• This causes a plasma ignition of the process gas between the plates 6 and in particular between the wafers housed in the wafer boat 1 and there is a plasma-assisted silicon nitride deposition on the wafers.
• the gas flow is maintained during the deposition process to to avoid a local depletion of the process gas with respect to the active components.
• the electrical control unit 64 is in turn deactivated and the gas supply stopped or again switched to N 2 in order to flush the process chamber 38 and, if appropriate, simultaneously to vent it (equalization to the atmospheric pressure). Subsequently, the process chamber 38 can then be brought back to ambient pressure.
• the wafer boat 1 of the above type irrespective of other components of the treatment device, has the advantage that it allows heating directly in the region of the receiving slots 11 between the plates 6 of the wafer boat 1 during the heating phase , This is possible via the electrically conductive spacer elements 22.
• They are chosen especially high impedance, they do not affect the plasma formation when applying the RF voltage significantly.
• the special gas guide via the gas guides 44, 46 offers - again independently of other components of the treatment device, such as the special wafer boat 1 - the advantage of a homogeneous gas flow in the process chamber 38.
• the deflecting a targeted gas flow through the receiving slots can be achieved .
• a good gas exchange and a homogeneous gas distribution in the reaction space is ensured and, if appropriate, lower flow rates can be used for the process gases,
• the special coaxial line 74 - again independently of other components of the treatment device, such as the special wafer boat 1 with electrically conductive spacer elements 22 or the special gas guide - the advantage that efficiently stresses in the MHz range, in particular with 13.56 MHz to the Waferboot can be created. Electrical losses can be reduced.
• the wafer boats 1 00, 200 and 300 offer compared to the wafer boat 1 a significantly reduced thermal mass and the free-standing in large parts wafer can be better heat. In the area of the supports 102, 104 and the plates 202, 204 can again be used to electrically conductive spacers to provide here during the heating phase, a local additional heating. In particular, a compensation for the thermal mass of the pads or plates can be created, which is not present in the free area of the wafer.
• the wafer boat 300 allows a different alignment of the wafers, in particular at a constant
• Process chamber allows the inclusion of larger wafers.
• the treatment device 30 and the wafer boat 1 have been explained in more detail with reference to certain embodiments of the invention with reference to the drawing, without being limited to the specific embodiments shown.
• the gas guides 44, 46 could take different forms or be arranged differently, as already indicated by FIGS. 7 to 9.
• the plates 6 of the wafer boat 1 may have other dimensions and in particular be dimensioned for receiving a different number of wafers.
• the treatment apparatus is shown in a horizontal orientation, and this also represents a preferred orientation.
• most advantageous aspects of the present application also apply to a vertical chamber with a vertically arranged tubular element, wherein location details are to be reinterpreted as described above, below in lateral location , This applies in particular to the arrangement of

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• 2015
  • 2015-04-02 DE DE102015004430.3A patent/DE102015004430B4/de not_active Expired - Fee Related
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