EP3278351A1

EP3278351A1 - Plasma-treatment device for wafers

Info

Publication number: EP3278351A1
Application number: EP16717581.9A
Authority: EP
Inventors: Michael Klick; Ralf Rothe; Wilfried Lerch; Johannes REHLI
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-04-02
Filing date: 2016-04-01
Publication date: 2018-02-07
Also published as: DE102015004414A1; CN108140528A; US20180076070A1; TW201703109A; CN108140528B; WO2016156606A1

Abstract

The problem addressed by the inventions is that of providing an improved introduction of high-frequency waves into a wafer boat. This problem is solved in that a plasma-treatment device, in particular for semiconductor wafers for semiconductor or photovoltaic applications, is provided, comprising a processing chamber for receiving a wafer boat having a plurality of electrically conductive receiving elements for the wafers, means for controlling or regulating a process gas atmosphere in the processing chamber, and at least one voltage source, which can be connected to the wafer boat via a line guided into the processing chamber. The line is configured as a coaxial line having an inner conductor and an outer conductor, and between the inner conductor and the outer conductor, a dielectric is provided such that when impinged upon with high-frequency voltage, the propagation velocity and the wavelength of the electromagnetic wave in the coaxial conductor are reduced with respect to a corresponding propagation velocity and wavelength of the electromagnetic wave in vacuo.

Description

Plasma treatment apparatus for wafers

The present invention relates to a treatment device for wafers which is suitable for generating a plasma between wafers accommodated therein.

In the semiconductor and solar cell technology, it is ^"known to suspend disc-shaped substrates made of different materials, which are hereinafter referred to irrespective of its geometric shape and its material as wafers different processes.

The wafers are often both individual treatment processes as well as batch processes, ie. 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.

In one type of wafer boat, for example, used for plasma processing of wafers in semiconductor or solar cell technology, the wafer boat is formed by a plurality of electrically conductive plates, 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. Thus, in each receiving slot, at least two wafers can be completely sandwiched between the plates so as to face each other. Adjacent plates of the wafer boat are electrically isolated from each other, and between directly adjacent plates becomes a high frequency AC voltage during the process

usually applied in the kHz range or in the MHz range. As a result, a plasma is to be formed between the plates and in particular between the wafers held on the respective plates in order to obtain a

Provide plasma treatment such as plasma deposition or plasma nitriding of layers. It has been found that the initiation of a high frequency AC voltage, especially in the MHz range, is often associated with high losses, which in some cases can prevent the ignition of a plasma between wafers.

The present invention is therefore based on the object to provide a plasma treatment apparatus for wafers, which allows an improved introduction of the high-frequency AC voltage.

According to the invention, this object is achieved by a plasma treatment device according to claim 1. Other embodiments of the invention will become apparent, inter alia, from the respective subclaims.

In particular, the semiconductor wafer plasma processing apparatus is for semiconductor or photovoltaic applications, and includes a process space for housing a wafer boat having a plurality of electrically conductive wafers for the wafers, means for controlling a process gas atmosphere in the process space, and at least one power source can be connected to the wafer boat via a line guided into the process space. The line is as Coaxial line is formed with a I nnenleiter and an outer conductor and between the inner conductor and the outer conductor, a dielectric is provided such that when exposed to high-frequency voltage, the propagation velocity and the wavelength of the electromagnetic see wave in the coaxial with respect to a corresponding propagation speed and wavelength of the electromagnetic Wave is reduced in the vacuum. The above apparatus allows for improved introduction of high frequency waves into a wafer boat in a plasma processing apparatus.

Preferably, the geometric length of the coaxial conductor ^'is close to an odd multiple of λ / 4 of the wavelength reduced by the dielectric. In one embodiment, the dielectric is formed from a plurality of dielectric elements, resulting in a simple construction. Preferably, the dielectric is made of a plurality of dielectric, preferably stratified in the propagation direction

Elements with different dielectric constant formed, which allows the setting of a desired effective real dielectric constant of the dielectric.

Preferably, the at least one voltage source of the type which is suitable for generating a high-frequency AC voltage, in particular with a frequency in the MHz range and in particular in the range of 13.56 MHz.

The invention will be explained in more detail with reference to the drawing; in the drawings shows:

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.

FIG. 3 is a schematic front view of the wafer boat according to FIG. 1; FIG. 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.

Fig. 6 is a schematic plan view of a part of a gas supply of

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 of FIG. 4; 9 is a schematic front view of a further alternative

Process chamber of the plasma treatment apparatus of FIG. 4;

Fig. 10 is a schematic side view of an alternative wafer boat, for

Use in a plasma treatment device;

Fig. 1 1 a to c schematic side views of parts of the alternative

Wafer boat according to FIG. 9, individually and in its end configuration;

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; and

Fig. 14 is a schematic side view of a part of the alternative

Wafer boat according to Fig. 12;

Fig. 15 is a schematic plan view of another alternative wafer boat; 16 shows a schematic side view of a part of the wafer boat according to FIG

Fig. 15;

17 (a) and (b) are schematic cross-sectional views taken through a process chamber of a plasma processing apparatus of FIG. 4 with a wafer boat of FIG. 15 therein;

Fig. 18 is a schematic plan view of another wafer boat;

FIG. 9 shows a schematic side view of a part of the wafer boat according to FIG. 19; FIG. and

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

restrictive to see. But you can choose preferred designs

describe. The formulation essentially based on parallel, perpendicular or angle specifications should include deviations of ± 3 °, preferably ± 2 °. Hereinafter, the term 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.

In the following, the basic structure of a wafer boat 1 for use in a plasma treatment apparatus will be explained in more detail with reference to FIGS. 1 to 3, wherein FIG. 1 shows a schematic side view of a wafer boat 1 and 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 units by a ^"plurality of plates 6, contact-7 and clamping units 8 is formed. The wafer boat 1 shown is specifically etc for a film deposition from a plasma, for example, Si3N4, SiNx, a-Si, and more particularly to a plasma The plates 6 each consist of an electrically conductive material and are in particular formed as graphite plates, it being possible, depending on the process, to provide a coating or surface treatment of the plate base material The plates 6 each have six recesses 10 as will be described in more detail below, although six notches are provided per plate 6 in the illustrated embodiment, it should be understood that a greater or lesser number may be provided. and lower edges, wherein in the upper edge, for example, a plurality of Notches may be formed to allow a position detection of the plates, as described in DE 10 2010 025 483.

In the illustrated embodiment, a total of twenty-three plates 6 are provided, which are arranged on the corresponding contacting units 7 and clamping units 8 substantially parallel to each other

between receiving slots 1 1 to form. Twenty-three plates 6 thus twenty-two of the receiving slots 1 1 are formed. However, in practice, 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 accommodated in such a way that the receiving elements respectively contact different side edges of the wafer.

In this case, a total of six groups of receiving elements for respectively receiving a semiconductor wafer are provided in the longitudinal direction of the plate elements (corresponding to the recesses 10).

At their ends, 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. In this case, two embodiments of plates 6 are provided which differ with regard to the position of the contact lugs 13. In one embodiment, 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 13 of the plates of the other embodiment. The two embodiments of plates 6 are alternately arranged in the wafer boat 1. As can best be seen in the view according to FIG. 2, the contact tabs 1 3 are thus located directly adjacent to one another. barten plates 6 in the arrangement of the wafer boat 1 on different levels. For each second plate 6, however, the contact lugs 13 are in the same plane. As a result, 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 13 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. These allow in the aligned state to perform a tensioning element 16, which has a shaft portion (not visible) and a head portion, such as a screw, About acting on the free end of the shaft portion counter element, such as a nut 17, the plates 6 are then fixed to each other. Here, the plates are fixed in two different groups to each other and in such a way that the plates of the different groups are arranged alternately. In this case, 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 13 of the plates 6) corresponding to the width of two receiving slots 1 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. Preferably, even the combined thermal mass of the sum of the contact blocks and the sum contact noses 13 of the plates should be smaller than the thermal mass of the

Sum of the plates 6 less the thermal mass of the respective contact noses 13th Further, further passage openings are provided in the plates adjacent to the upper edge and the lower edge, each allowing the passage of a clamping element 19 having a shaft portion (not visible) and a Kppfteil, such as a screw of the clamping unit 8 allow. These in turn can interact with corresponding counter-elements 20, such as nuts. In the illustrated embodiment, each of seven through holes adjacent to the top edge and seven through holes adjacent to the bottom edge are provided. In this case, four through holes are arranged around each recess 10, and approximately symmetrical thereto. As a further part of the clamping unit, a plurality of spacer elements 22 is provided, which are formed, for example, as spacer sleeves with substantially the same length. The spacer elements 22 are each arranged in the region of the respective passage openings between directly adjacent plates 6.

The shank parts of the clamping element 19 are each dimensioned so that they can extend through corresponding openings of all plates 6 and respective spacer elements 22 located therebetween. By means of the at least one counter element 20, all plates 6 can then essentially be fixed parallel to one another. However, there are also other clamping units with spacer elements 22 conceivable here, which arrange the plates 6 with interposed spacer elements 22 substantially parallel and jammed. In the illustrated embodiment, at 22 receiving slots and a total of 14 spacing elements 22 per slot (seven adjacent to the top edge and seven adjacent to the bottom edge) 308 spacer elements are provided.

The clamping elements 19 are preferably made of an electrically insulating material, while the spacer elements 22 preferably consist of an electrically conductive material. In particular, the spacer elements 22 preferably consist of a high-resistance material, such that the spacer elements serve as a resistance element when a DC or low-frequency voltage of sufficient amplitude is applied, but in the case of Applying a high frequency voltage (to create a plasma between the plates) does not provide significant attenuation of the wave propagation. For the low-frequency voltage, in particular a frequency range of 50 Hz to 10 kHz is considered. For the

High frequency voltage is considered a range over 40 KHz, in particular over a MHz in particular in the range of 13.56 MHz considered, but also other frequency ranges would be possible. In the illustrated embodiment with the chosen distribution, for example, each should

Distance element have a resistance of greater than 3 kQ, in particular greater than 20 kQ or even greater than 40 k i. For example, the spacer elements can be made of doped silicon, polysilicon or another suitable material, which on the one hand is not impaired by the process and on the other hand does not affect the process, in particular does not introduce impurities into the process. While on the contact elements 1 5 d he plates 6 a group (overhead

Contact nose 1 3 / bottom lying contact lug 1 3) electrically connected and fixed to each other via the spacer elements 22 all plates are electrically connected and fixed to each other. The basic structure of a plasma treatment device 30, in which a wafer boat 1 of the above type (but also a conventional wafer boat) can be used, will now be explained in more detail below with reference to FIGS. 4 to 6, FIG. 4 being a schematic side view of the treatment device 30 FIG. 5 shows a schematic front view of a process chamber structure and FIG. 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 dent to loading 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 pipe element consists of a suitable Material that does not introduce impurities into the process, is electrically isolated 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. Between the sheath 40 and the tube member 36, a heating device, not shown, is provided, such as a resistance heater, which is suitable to heat the tube member 36. However, such 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. At present, however, an external heating device is preferred and in particular one which has different, individually controllable

Has heating circuits.

In the interior of the tubular element 36, receiving elements not shown in greater detail are provided, which form a receiving plane for receiving a wafer boat 1 (which is only partially shown in FIG. 4), which may be of the above type, for example. However, the wafer boat can also be inserted into the tubular element 36 so that it rests on the wall of the tubular element 36. In this case, 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. By appropriate receiving elements and or a direct placement on the tubular element, a receiving space is thus defined in combination with the dimensions of the wafer boat, in which a wafer boat is inserted properly. The wafer boat, as a whole in the loaded state, can be brought in via a suitable handling mechanism (not shown) the process chamber 38 are traded in and out of it. In this case, upon loading of the wafer boat, 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.

Inside the tube member 36, 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 tubular element 36 and 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 tube member 36 lying end with a gas supply unit or a Gasabführ- unit in combination, as will be explained in more detail below. The respective opposite end of the gas guide tubes 44, 46 is closed. However, in principle, a short gas guide is conceivable in which, for example, gas is introduced 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.

In particular, it is contemplated to provide a plurality of rows of apertures 48 extending transversely to the longitudinal extent of the gas guide tube 44, each row having, for example, five apertures 48. In the plan view of FIG. 6, a portion of a corresponding gas guide tube 44 is shown schematically. 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. Preferably, the region has a greater length than the wafer boat and is arranged so that the area goes beyond the ends of the wafer boat. Preferably, the sum of the area of the openings 48 is smaller than the cross-sectional area of the gas guide tube 44. Preferably, the ratio of the sum of the area of the openings 48 to the cross-sectional area of the

Gas guide tube 44 between 30 and 70% and in particular between 40 and 60%. Upon application of a gas, a constant pressure then arises in the gas feed pipe 44 and a uniform gas distribution over the apertured region can be achieved. In particular, a spacing of the rows of openings 48 of approximately 5 mm is considered with an opening diameter of approximately 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

Press the distance could be larger. Preferably, 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 structure with openings, in which case the openings are formed in the lower half. In essence, the gas guide tubes 44, 46 may be identical, but arranged in a respective different orientation, so that the openings point respectively to the wafer boat 1. Thus, both the openings in the lower gas guide tube 44 and the upper gas guide tube 46 to the receiving space, i. the area where a properly inserted wafer boat is placed. Instead of providing rows with five openings, it is also possible a different arrangement or different shapes of the openings, for example, slots to provide.

By means of such gas guide tubes 44, 46, a good homogeneous gas distribution within the process chamber can be achieved, in particular also in the receiving slots 11 of the wafer boat. For this purpose, for example, preferably 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 pipe 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.

To enhance this effect, i. to direct the gas flow in particular between the plates 6 of the wafer boat, two optional, movable deflecting elements 50 are provided in the process space. The deflection elements 50, which are not shown in FIG. 4 for ease of illustration, have an elongated configuration. The Umienkelemente 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. However, 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. At their upper end, the deflecting elements 50 are each rotatably mounted and can by means of an adjustment mechanism, not shown, between a first position, which is shown in Figures 5 and 7 to 9 with a solid line, and a second position shown in Figures 5 and 7 to 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, in each case two lower and two upper gas supply pipes 44, 46 _. intended. 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 a 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.

In the embodiment according to FIG. 8, again only one lower and one upper gas guide tube 44, 46 are provided. 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.

In the embodiment of FIG. 9, three lower gas supply pipes 44 and a single upper gas supply pipe 46 are provided. 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. Regarding 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. 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. In particular, in this arrangement, a first gas can be introduced via the outer gas guide tubes 44, while a second gas is introduced via the middle. The arrangement allows a good and homogeneous mixing and distribution of the gases.

The control part 34 of the treatment device 30 will now be explained in more detail. The control part 34 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. In the illustrated form three gas sources are shown, of course, any other number may be provided. For example, the gas sources di-chlorosilane, tri-chlorosilane, SiH ₄ , phosphine, borane, di-borane, German. (GeH4), Ar, H _2, N ₂ TMA NH _3l and various other gases at respective inputs of the gas control unit 60 bereitstellen.- The gas control unit 60 has two outputs, wherein one of the outputs is connected to the lower gas guide tube 44 and the other with a pump 70 of the vacuum control unit 62. The gas control unit 60, the gas sources in a suitable manner with the

Connect outputs and control the flow of gas, as is known in the art. Thus, the gas control unit 60, in particular via the lower gas guide tube 44 introduce different gases into the process chamber, as will be explained in more detail below.

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

Process chamber in connection.

The line is introduced through a corresponding vacuum and temperature suitable passage through the sheath 40 and into the tube member 36. The line is in particular designed so that they as

Coaxial line 74 is formed with an inner conductor and an outer conductor. Over the length of the coaxial line 74, there is approximately the outside

Field freedom, so even at high frequencies in the MHz range

(For example, at 13.56 MHz) no parasitic plasmas arise and as lossless transmission takes place. Inside the coaxial line wave propagation takes place with the wavelength λ. The

Wave propagation is between plate pairs (planar waveguide) but with a different wavelength, depending on the presence and type of plasma.

Between the conductors of the coaxial line 74, a suitable dielectric is provided which, when subjected to high-frequency voltage, ^reduces 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 a vacuum. 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 the vacuum wavelength. In particular, for impedance transformation due to the low impedance of wafer boat 1, the geometric length of the coaxial sander should be close to an odd multiple of λ / 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 λ / 4 be set to the wavelength of the applied frequency.

In one embodiment, adjustment of the wavelength or the electrical length of the coaxial conductor 74 via a plurality of insulators, which are insertable into the space between the inner and outer conductors and thus form the dielectric. Also on the geometry of inner and outer conductor can be made a certain setting. Although the inner and outer conductors of coaxial conductors usually have a round cross-section, the term coaxial conductor, as used in the present application, should also include inner and / or outer conductor with other cross-sections. For example, the inner and / or outer conductors may have rectangular or oval cross-sections and extend along a common longitudinal axis. The local propagation velocity of the high - frequency wave and thus integrally the effective electrical length of the Coaxial conductor 74, however, depends substantially on the dielectric between the inner and outer conductors. As the dielectric constant increases, the propagation velocity decreases with 1 / (ε _Γ ) ^{1 2} and, accordingly, the effective electrical length of the coaxial conductor 74 increases. In this case, a desired average dielectric constant can be set over the length by suitably arranging short insulator pieces of different dielectric constant over the length. In particular, it is contemplated to introduce a suitable selection into the space between inner and outer conductors from a set of two to four different different dielectric constant elements to set a desired effective dielectric constant for the dielectric. The insulator pieces 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 influences the properties of the depositing plasma, for example in the homogeneity / uniformity over the wafer and the wafer boat,

Here, the contact lugs 13 of the wafer boat 1 should be reduced for the coupling of high-frequency power as possible in mass and length to keep the local heat capacity and Zuleitungsinduktivität as low as possible, in particular by the sum of the contact lugs 1 3 in combination with the contact elements Preferably, the impedance of the corresponding supply inductance at the operating frequency should be less than half and preferably less than 1/10 of the impedance of the plate stack of the 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 classic Plasma treatment devices can be used. The wafer boat 100 is formed by electrically conductive support unit 1 01 with a plurality of electrically conductive pads 102, 104, for example made of graphite or another good electrically conductive material, an insulated guide unit 106. The support unit 01 and the insulated guide unit 106 are connected via insulated connecting elements 108 and thus jointly form the wafer boat 100.

The electrically conductive pads 102, 104 are best seen in the schematic side views of Figures 10a to 10c. 1 1 a shows a schematic side view of the support 102, FIG. 1 b shows a schematic side view of the support 104, and 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 10 with a substantially rectangular cross-sectional shape. The main body 1 10 has in each case a straight central part, in the upper side of a slot 12 for receiving wafers (W) is formed. In the longitudinal direction of the slot 1 2 is dimensioned so that it can accommodate six wafers (W) side by side with a predetermined distance, as can be seen in Fig. 10. The slot depth is chosen to be less than or equal to a conventional edge margin in wafer production and is thus about 1-5 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. At their longitudinal ends (adjacent to the slot 1 12 having central portion 1 1 1) have the respective base body 1 0 end portions 1 14, which are offset with respect to the central portion 1 1 1 in the plane up or down. The end portions 1 14 of the support 102 are offset upwards and the end portions 1 14 of the support 104 down, as shown in Figures 1 1 a and 11 b is clearly visible. When the pads 102, 1 04 are in their final configuration, the end pieces lie 1 14 of the pads 102 in an upper level and the end portions 1 14 of the

Pads 104 in a lower level, as shown in Fig. 1 1 c can be seen.

In the main bodies 1 10 each have a plurality of transverse bores 116 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 1, the clamping elements 120 are used in the region of the end parts 1 4.

In your final assembly, a plurality of, for example, 22 of the pads 102, 104 are arranged transversely to their longitudinal extent parallel to one another, with the pads 102 and 104 alternating in the assembly. in the

Middle region 1 1 1 of the pads 102, 104 spacers (not shown) are provided between directly adjacent pads 102, 104, which are aligned with the transverse bores 16 1. These spacers are sleeve-shaped and are dimensioned so that they are plugged in the assembled state of the wafer boat 100 on the shaft portion of the clamping element 1 18. 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.

In the region of the end portions 1 14 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 each have a length equal to the length of two spacers plus the width of a support. Thus, they are capable of electrically connecting two pads 102, 102 or 104, 104 in the array respectively. Thus, 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 supports 102, 104 and they extend substantially parallel to the supports 02, 104, wherein the holding elements 130 are arranged higher than the supports 102, 104. The guide rods 13 extend perpendicularly between the holding elements 130, as can be seen in the plan view according to FIG. 12, and are connected to them in a suitable manner. 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. In the longitudinal direction of the wafer boat 100, the guide rods 132 are spaced so that they can each receive a wafer pair W, W therebetween, as indicated in FIG. 12. It should be noted that the plan 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 134 are in the transverse direction of the

Waferbootes 00 with the slots 1 12 in the pads 102, 104

aligned. If the slots 1 2 have a tendency are the

Notches 134 correspondingly slightly offset from the slots 1 2, to allow a recording of the wafer pairs W, W in a slightly inclined position.

The support unit 101 consisting of the connected supports 102, 1 04 and the insulated guide unit 1 06 consisting of the holding elements n 130 and the guide rods 132 are connected in the end regions in each case via insulated connecting elements 108. In particular, the connecting elements 108 each have a plate shape and they work with the clamping elements 1 18 and 120 and additional clamping elements for the connection. Together with the holding member 130 together to fix the assembly as a whole, and thus to form the wafer boat 100.

The wafer boat 1 00 can be used in the same way as a classic wafer boat, or also in the form described below, when the spacers are electrically conductive, such as the spacers 22 in the wafer boat 1. An electrical contacting of the wafer pairs W, W, which are received on the supports 102, 104, takes place only in the area of the respective slots 12. The wafer boat 100 does not take the wafers between plates, but leaves them essentially free. As a result, heating of the wafers can be improved. This is further promoted by a reduced thermal mass of the wafer boat 100 compared to wafer boat 1. The back-to-back arrangement of the wafer pairs can contribute to improved slip freedom of processed wafers. Furthermore, this may optionally the transverse dimensions of the wafer boat at the same

Recording capacity can be reduced.

A further alternative embodiment of a wafer boat 200, which can be used in a plasma treatment device 30 of the above type but also in classical plasma treatment devices, will now be explained in more detail with reference to FIGS. 13 and 14. FIG. 13 shows a schematic side view of a loaded wafer boat and FIG. 14 shows a schematic side view of a single plate of the wafer boat. The wafer boat 200 is substantially electrically conductive by electrically conductive plates 202, 204, for example made of graphite or another. Material formed, 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 Zusatzheizfunktion or not, as explained below. The plates 202, 204 each have upwardly open recesses 208. On both sides of the plates 202, 204, 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. In each case, one of the receiving pins below the recess 8 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 21 0 and the upper edge of the respective plates 1 02, 204 is smaller than half the height of a wafer W to be recorded. Unlike the wafer boat 1, recorded wafers are thus not completely accommodated between two plates, but rather project upwardly beyond the plates, as can be seen in FIG. Compared to the wafer boat 1, 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, in order to enable group-wise contacting of the plates via electrically conductive contact elements (not shown). The contact tabs are preferably kept short and are rounded to the outside. 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. Especially if a coaxial

Supply line is provided, as in the plasma treatment apparatus 30 described above,

A further alternative embodiment of a wafer boat 300, which can be used in a plasma treatment device 30 of the above type but also in classical plasma treatment devices, is explained in more detail with reference to FIGS. 15 to 16. FIG. 15 is a schematic plan view of the wafer boat 300, FIG. 16 is a schematic sectional view of a portion thereof, and FIGS. 17 (a) and (b).

schematic cross-sectional views of a plasma treatment apparatus with Such a wafer boat 300. While the previous wafer boats were each of the type in which the wafers parallel to the longitudinal extent of

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. In particular, the wafer boat 300 has a classic design, as used for example in thermal diffusion systems for semiconductor wafers. As can be seen in the plan view of Figure 15, 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. At the ends of the wafer boat 300, an end plate 303 is provided, which is preferably formed of quartz. But it can also be constructed of another suitable non-conductive material.

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. In this case, 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

Welding or bonding. The receiving elements 305 may also consist of quartz and each have an elongated rod shape. In this case, 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 arranged mutually inclined and have in their upwardly facing narrow side in each case a plurality of receiving slots 313 which extend transversely to the longitudinal extent of the receiving element 305, and Although preferably substantially at a 90 ° angle to the longitudinal extent. The receiving slots 3.13 are each evenly spaced

provided with each other and they have 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. Preferably, the depth will be approximately equal to or less than one edge scraping 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.

Subsequently, the 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

Essentially formed by a 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. In 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, and 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 distances as the slots 31 3 of the receiving elements 303, in which case the distance from the Schlitzmiüe 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. In addition, the slots 313, 322 and 323 are aligned with each other such that a wafer (wafer wafer) received in the wafer boat pair) are each received 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). In this case, 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. This ensures that adjacent wafers (wafer pairs) which are received in the wafer boat in the longitudinally adjacent slots contact different contact and guide elements 307. This is indicated, for example, in Figures 17 (a) and (b), which show, for example, cross-sectional views through adjacent slots in the wafer boat. Here, in the view of FIG. 17 (A), 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. Accordingly, at the adjacent slot (view Fig. 17 (b)) in the left

Contact and guide member 307 a slot 323 cut and in the right contact and guide member 307 a slot 322, Thus, as the skilled person will recognize, between the wafers (wafer pairs) a

Voltage are applied when a voltage is applied between the contact and guide elements 307. Although not shown in Fig. 16, insulating inserts could be provided in the slots 323, each having respective receiving slots for the wafer (a pair of wafers), or the slots 323 could have an insulating coating. In particular, it is possible to first form the slots 323 in the contact and guide element 307, and in

Connection to apply an insulating coating, which is then destroyed locally in the subsequent formation of the slots 322. As a result, an electrical contacting of wafers only in the region of the slots 322 is possible. The contact and guide elements 307 may be formed relatively thin. However, to provide sufficient stability across 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 3. 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. Again, the lower member 330 may have a round shape, but has no slots, thereby providing greater stability over a comparable slotted member, and may therefore support the contact and guide member 307 over the length thereof.

Figures 18 to 20 show yet another alternative embodiment of a wafer boat 300. This wafer boat 300 is broadly similar to the wafer boat 300 previously described with reference to Figures 15 to 17, and therefore the same reference numerals are used for the same or equivalent elements. FIG. 18 shows a schematic plan view of the wafer boat 300, FIG. 19 shows a schematic sectional view of a partial region of the same, and FIGS. 20 (a) and (b) show schematic cross-sectional views of one

Plasma treatment apparatus with 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. As can be seen in the plan view of Figure 18, 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. Between the end plates 303 each extend two transversely spaced first receiving members 305, two transversely spaced second receiving members 306, and two spaced contact and guide elements 307, which are respectively secured to the end plates 303. In the transverse direction, the contact and guide elements 307 between the second receiving elements 306 and the second receiving elements 306 are each between a first receiving elements 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 bar members 320, 330 and contact slots 222 and insulating slots 223, which are offset from one another in the respective contact and guide elements 307. As a result, every second recorded in the wafer boat wafer by one of

Contact and guide elements 307 contacted while the other wafers are contacted by the other contact and guide member 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 be made of quartz and each have an elongated rod shape. In this case, the first and second receiving elements 305, 306 each have a basic shape, as in the wafer boat 300 according to Figures 15 to 17. They also each have a plurality of slots 330 corresponding to the

Variety of receiving slots 313 according to Figures 15 to 17. However, 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 suitable for receiving an edge portion of a respective wafer or wafer pair to be received, for example, in a back-to-back arrangement, contacting the slot the depth is about one edge scrap area of the wafers be corresponding or smaller. 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 slits 333 are each suitably free-standing, that is, without contact herewith in the slit, of an edge region of a respective wafer or pair of wafers to be picked up.

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 female screw ^'strand 332 and the isolation slots 333 of the first recording 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. Further, the receiving slots 332 of the first receiving members 305 are aligned with the insulating slots 333 of the second receiving members 306 and the insulating slots 333 of the first receiving members 305 with the receiving slots 332 of the second receiving members 306. In other words, the receiving and insulating slots 332, 333 of the first receiving elements 305 to the receiving and insulating slots 332, 333 of the second receiving elements 306 offset.

As a result, 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. As a result, it is further achieved that 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 indicated in Figs. 20 (a) and (b). This configuration may in operation prevent a short across the first and second receiving elements 305, 306 in the event that during a plasma treatment (e.g. conductive layers on the wafers) conductive layers on the first and second receiving elements 305, 306 deposit.

In this configuration, it would also be possible the first and second

In addition, receiving elements 305, 306 form a voltage in addition to this, to apply a voltage between wafers accommodated in the wafer boat 300 in order, for example, to increase the contact area with the wafers and thus the area for the introduction of electrical power. The operation of 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. However, the treatment device 30 can also be used for other plasma-assisted deposition processes, wherein the plasma can also be excited by other frequencies, for example in the 40 kHz range. However, the coaxial line 74 is provided and optimized especially for frequencies in the MHz range. First, it is assumed that 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. In this case, 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, in each case six on each of the plates 6. The wafers are so accommodated that they are pairwise opposite, as is known in the art.

In this state, 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. Therefore, if a wafer boat 1 of the type described above is provided, 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. In this case, the voltage is sufficiently high so that current is conducted via the high-resistance spacer elements 22 and they act as resistance heating elements. As a result, 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. Depending on the resistance of the spacers, 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.

When the predetermined temperature of the wafer boat 1 and thus the whole unit (wafer boat 1, wafer and tube element 36) is reached, 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 moved by the self-adjusting negative pressure or active in the first position (solid line in Fig. 5). When the predetermined negative pressure is reached, a desired process gas, such as, for example, S 1 H 4 / NH ₃ for silicon nitride deposition, is introduced via the gas control unit 60 in a defined mixing ratio as a function of the required layer properties, via the vacuum control unit 62 Furthermore, the negative pressure is maintained by sucking the introduced process gas. The process gas extracted via the pump 70 may be diluted with N ₂ at this time, as known in the art. For this purpose, via 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 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.

Via the electrical control unit 64, 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 avoid local depletion of the process gas with respect to the active components. After a sufficient deposition time for the desired layer thickness, the electrical control unit 64 is in turn deactivated and the gas supply is stopped, or switched back to N ₂ , in order to flush the process chamber 38 and if necessary to ventilate simultaneously (equalization to the atmospheric pressure). Subsequently, the process chamber 38 can then be brought back to ambient pressure.

As can be seen from the above description, 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. The fact that 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. In particular w combination with the deflecting a targeted gas flow through the receiving slots can be achieved become. As a result, a good gas exchange and a homogeneous gas distribution in the reaction chamber is guaranteed and it may possibly lower

Flow rates are 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 applied voltages in the MHz range, in particular at 13.56 MHz to the wafer boat can be. Electrical losses can be reduced. The special configuration of the contact areas of the wafer boat 1, such as the dimensions and shapes of the contact tabs, also contribute to this.

Wafer boats 100, 200 and 300 offer a significantly reduced thermal mass compared to wafer boat 1, and the largely free-standing wafers heat better. 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. In particular, for example, the gas guides 44, 46 assume different shapes or be arranged differently, as already indicated by FIGS. 7 to 9. Also, 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. However, 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

Gas guide tubes with respect to the wafer boat or a receiving space for this.

Claims

Claims. A plasma processing apparatus for wafers, in particular semiconductor wafers for semiconductor or photovoltaic applications, comprising: a process space for accommodating a wafer boat having a plurality of electrically conductive receptacles for the wafers;

Means for controlling or regulating a process gas atmosphere in the process space; and

at least one voltage source which can be connected to the wafer boat via a line guided into the process space, wherein the line is designed as a coaxial line with an inner conductor and an outer conductor, and wherein between the inner conductor and the outer conductor

Dielectric is provided such that when exposed to high-frequency voltage, the propagation velocity and the

Wavelength of the electromagnetic wave in the coaxial conductor is reduced relative to a corresponding propagation velocity and wavelength of the electromagnetic wave in vacuum.

2. A plasma treatment apparatus according to claim 1, wherein the

geometric length of the coaxial conductor is close to an odd multiple of λ / 4 of the wavelength reduced by the dielectric.

3, plasma treatment device according to one of the preceding

Claims, wherein the dielectric is formed from a plurality of dielectric elements.

4. Plasma treatment device according to one of the preceding

Claims, wherein the dielectric of a plurality of dielectric

Elements with different dielectric constant is formed.

5. Plasma treatment device according to one of the preceding

Claims, wherein the at least one voltage source of the type is it is suitable to generate a high-frequency AC voltage, in particular with a frequency in the MHz range and in particular in the range of 1 3.56 MHz.