EP3378093A1

EP3378093A1 - Wafer boat and plasma treatment device for wafers

Info

Publication number: EP3378093A1
Application number: EP16797907.9A
Authority: EP
Inventors: Peter VÖLK; Uli Walk; Wolfgang Jooss
Original assignee: Centrotherm International AG
Current assignee: Centrotherm International AG
Priority date: 2015-11-18
Filing date: 2016-11-17
Publication date: 2018-09-26
Also published as: KR20180084926A; TW201724326A; DE102015014903A1; CN108475653A; WO2017085178A1; US20180337079A1; TWI716491B

Abstract

The invention relates to a plate element for a wafer boat for the plasma treatment of disk-shaped wafers, in particular semiconductor wafers for semiconductor or photovoltaic applications. The plate element is electrically conductive and has at least one holding unit on each side, for holding a wafer in a wafer holding region. The plate element has at least one recess in at least one side of the plate element and/or at least one opening in the plate element, wherein the at least one recess and/or the at least one opening in the plate element lies at least partially radially outside of the wafer holding region and directly adjacent thereto. The invention further relates to a wafer boat that has a plurality of plate elements of the above type arranged parallel to each other, wherein plate elements arranged adjacent are electrically insulated from each other. The invention further relates to a wafer boat in combination with a plasma treatment device, which has a process chamber for accommodating the wafer boat, means for controlling a process gas atmosphere in the process chamber in an open-loop or closed-loop manner, and at least one voltage source, which can be connected to the electrically conductive plate elements of the wafer boat in a suitable manner in order to apply a voltage between directly adjacent wafers held in the wafer boat.

Description

Wafer boat and plasma treatment device for wafers

The present invention relates to a wafer boat and a wafer processing apparatus suitable for generating a plasma between wafers housed therein.

In semiconductor and solar cell technology, it is known to suspend disk-shaped substrates made of different materials, which are referred to below independently of their geometric shape and their material as wafers, different processes.

In doing so, 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 the wafers are used in so-called boats, which have recordings for a variety of wafers. In the boats, the wafers are usually arranged parallel to each other. Such boats can be designed differently and often they only provide for receiving the lower edges of the respective wafers so that the wafers are upstanding. 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 used, for example, for plasma processing of wafers in semiconductor or solar cell technology, 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 are deposited on each of these sides. can be taken. As receiving elements, pins are usually provided on each side of the plate facing another plate, which holders 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 an AC voltage is usually applied in the kHz range or else in the MHz range during the process. In this way, 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. For the arrangement of the plates to each other spacer elements are used, each having a predetermined length for setting predetermined distances between the plates. An example of such a wafer boat, which is constructed from plates and spacers, is described in DE 10 201 1 109 444 A1.

As mentioned, a plasma is created not only between adjacent wafers but also between adjacent plates. Due to a usually higher conductivity of the plates compared to the wafers, the

Plasma between the plates will therefore be denser than between the wafers, which may be detrimental to the process and homogeneity of the wafer treatment. In particular, a greater effect can occur in the edge region of the wafer than in other regions of the wafer. Furthermore, this results.

Problem that there is a backside treatment, especially one

Reverse coating of the wafer may occur, which is also referred to as encasing the coating and is caused by the plasma directly adjacent to the wafer edge. To remedy this problem, the plates have in the past been pre-coated with an insulating layer, for example SiN, over the

To attenuate plasma formation between the plates. However, such a pre-assignment can in turn lead to other problems and beyond regularly in particular after a wet cleaning of the plates in one

Etching, to be renewed, which is associated with additional costs.

It is therefore an object of the present invention to provide a wafer boat and a plasma processing apparatus for wafers which overcomes or alleviates the above-mentioned problems of wrap-around.

According to the invention, this object is achieved by a plate element

Claim 1, a wafer boat according to claim 6, and a plasma treatment apparatus according to claim 8 solved. Other embodiments of the invention will become apparent, inter alia, from the respective subclaims.

In particular, a plate element is provided for a wafer boat for the plasma treatment of disk-shaped wafers, wherein the plate element is electrically conductive and has on each side at least one receiving unit for receiving a wafer in a wafer receiving region. According to the invention, the plate element has at least one recess in at least one side of the plate elements and / or at least one opening in the plate element, wherein the at least one recess and / or the at least one opening in the plate element at least partially radially outside of the wafer receiving region and directly adjacent thereto , As the wafer receiving area, the area that is usually covered by the wafer is considered here. A small overlap of recess / opening and wafer in the recording state is possible, but not necessarily wanted. Such a plate element has the advantage that it generates an attenuated plasma in use in the range of a recorded wafer, and thus can prevent or at least reduce edge effects and in particular encase of the plasma. The plate element preferably has a corresponding depression on both sides. In one embodiment, the plate member has at least one

Well, which surrounds the wafer receiving area substantially completely. In this context, the term I should essentially comprise at least 80, preferably more than 90% or 95%. This is to ensure that the effect of an attenuated plasma is given substantially in full. )

In an alternative embodiment, the plate member has a plurality of apertures each lying at least partially radially outside the wafer receiving region and adjacent thereto. With a large number of openings, it is possible with sufficient stability to surround a large peripheral area of the wafer receiving area. Preferably, the openings in the plate element should radially surround at least 50%, preferably at least 80%, of the wafer receiving area.

The wafer boat for the plasma treatment of disk-shaped wafers has a plurality of parallel plate elements of the above type, with adjacent plate elements being electrically insulated from each other. Such a wafer boat, in turn, makes it possible to produce a weakened plasma when used in the edge areas of recorded wafers and thus to prevent or at least reduce edge effects and, in particular, encasing the plasma.

In panel members with openings, the openings in adjacent Plattenelem ^'ducks be arranged offset to each other to provide the Abschwäch- ungseffekt in edge regions of the wafer receiving portion is substantially full.

The plasma treatmen averaging device for disc-shaped wafer has a ^'process chamber for receiving a wafer boat of the above type, means for controlling or regulating a process gas atmosphere in the process chamber, and at least one voltage source, which can be connected to the electrically conductive receiving elements of the wafer boat in a suitable way is over apply an electrical voltage between directly adjacent wafers housed in the wafer boat.

The wafer plasma processing apparatus has a process space for housing a wafer boat of the type described above. Further, means for controlling a process gas atmosphere are in the

Process space and at least one voltage source, which is suitably connectable to the electrically conductive plate elements of the wafer boat, provided to directly adjacent, in the wafer boat

Wafer to create an electrical voltage recorded.

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

Fig. 1 is a schematic side view of a plate member for 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. 4a and 4b are enlarged perspective views of portions of

Plate elements of the wafer boat according to Fig. 1;

Fig. 5 is a schematic view of a plasma processing apparatus having wafer boat thereof shown in Fig. 1;

Fig. 6 is a schematic side view of an alternative plate member; Fig. 7 is a schematic side view of another alternative one

Plate member;

8 is an enlarged perspective partial sectional view of a portion of the plate member of FIG. 6.

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 °, otherwise it should comprise substantially at least 80%, preferably at least 90% or 95% of the indicated value. Hereinafter, the term wafer is used for disk-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 4, FIG. 1 showing a schematic side view of a plate element wafer boat 1, FIGS. 2 and 3 showing a top view and a front view and FIG Figures 4a and 4b show enlarged perspective views of portions of two adjacent plate elements of the wafer boat. 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, which are held together by contacting and clamping units and each suitable for receiving a plurality of wafers 7. The illustrated wafer boat 1 is specifically for a layer deposition of a plasma, for example of Si ₃ N ₄ , SiN _xl a-Si, Al 2 O 3, AIO _x , doped and undoped poly silicon or amorphous silicon, etc., and in particular a plasma

Nitriding of wafers suitable. 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 8, 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, or may be completely dispensed with the recesses. The plates 6 each have parallel upper and Lower edges, (wherein in the upper edge, for example, a variety 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 according to Figure 2, 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 to form receiving slots 1 1 therebetween. Twenty-three plates 6 thus twenty-two of the receiving slots 1 1 are formed. However, in practice, 25, 19 or 21 plates are often used, and the invention is not limited to a certain number of plates 6. An even number of disks may also be used (e.g., 20, 22, 24, 26, ...).

The plates 6 each have at least on their side facing an adjacent plate 6 groups of three receiving elements 9, which are arranged so that they can receive a wafer 7 therebetween. In this case, two wafers 7 are shown in the representation according to FIG. 1, as they are accommodated in the two left-lying groups of receiving elements 9. In the other groups, no wafers are included. The groups of the receiving elements 9 are each one at a time

Recesses 8 arranged around, as indicated schematically in Fig. 1. The groups of the receiving elements 9 each define a wafer receiving area, the term wafer receiving area denoting the area of the plate (including the notches 8) which is usually covered by a wafer 7 received in a respective group of receiving elements. The wafers 7 can be accommodated in such a way that the receiving elements 9 each contact different side edges of the wafer 7. In this case, in the longitudinal direction of the plate elements (corresponding to the recesses 8) a total of six groups of receiving elements 9 are provided for each receiving a wafer. In each side of the plate elements 6, a plurality of recesses 10 are provided, each radially surrounding a respective wafer receiving region. The recesses 10 may wafer receiving areas in each case completely surrounded, ^'as shown, but it is also possible that the recesses 10, the wafer receiving areas only partly surround.

In particular, in the area of the receiving elements 9 could from

Stability reasons are waived on the recess 0. Preferably, the recesses 10 should, however, substantially completely surround the wafer receiving regions, wherein substantially at least 90% should preferably encompass more than 95% radial surrounding, in which case optionally a plurality of depressions 10 per wafer receiving region may be provided. Preferably, the recesses 10 adjoin radially outwardly directly to the respective wafer receiving region, but it can in the context of

Töleranzabweichungen in use also come to a small distance between the wafer receiving area and recess 10, or to a small overlap of wafer receiving area and recess 10.

As can be seen in particular in the view according to FIGS. 4a and 4b, adjacent plates 6 in the wafer boat 1 have a distance a between them, which is increased in the region of the depressions 10 to a greater distance b. In this case, the recesses 10 of adjacent plates 6 are such that they are exactly aligned with each other. As a result, the distance b is twice the depth of the recesses 10 greater than the distance a.

Although recesses 10 are formed in both sides of the plates in the above description, it would also be conceivable to provide a respective recess 10 in only one side, with each wafer side then having one plate side with recess 10 facing an adjacent plate side without recess. This would result in a local increase in the distance to the simple depth of the recess.

At their ends, the plates 6 each have a protruding contact lug 3, which serves for electrical contacting of the plates 6, as follows will be explained in more detail. 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 directly adjacent to the lower edge, while in the other embodiment they are spaced from the lower edge, the distance to the lower edge being 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 best seen in the view of FIG. 2, thus the contact lugs 13 are directly adjacent 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 or titanium, and arranged at 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 having a shaft portion (not visible) and a head portion, such as a screw. By acting on the free end of the shaft part counter element, such as a nut 17 ^' the plates 6 can then be 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 J which 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

Further, further through holes are provided in the plates adjacent to the upper edge and the lower edge, each allowing the passage of a clamping member 9 having a shank portion (not visible) and a head portion, such as a screw of the clamping unit. These in turn can interact with corresponding counter-elements 20, such as nuts. In the illustrated embodiment, seven through holes are provided adjacent to the top edge and seven through holes are adjacent to the bottom edge. In each case, four passage openings are arranged around each recess 8, namely approximately symmetrically thereto. As a further part of the clamping unit a plurality of spacer elements 22 is provided, for example, as

Spacer sleeves are formed 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 the plates 6 can then be fixed substantially 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 are preferably made of an electrically insulating material, in particular an oxide ceramic, which also applies to the spacer elements 22. FIGS. 6 to 8 show alternative embodiments of plates 6 which can be used to form a wafer block 1. 6 shows a schematic side view and FIG. 8 shows an enlarged perspective partial sectional view of an alternative plate, and FIG. 7 shows a schematic side view of a further alternative of a plate. As in the first embodiment, in the side views according to FIGS. 6 and 7, two wafers 7 received on the plates 6 are indicated. In the view according to FIG. 8, wafers 7 likewise received on the plate 6 are also visible

indicated, with wafers 7 are accommodated on both sides of the plate 6.

The plates 6 are similar to the previously described plates 6 (according to FIGS. 1 to 4) with respect to the material and the basic structure with recesses 8, receiving elements 9 and lugs 13. The plates 6, however, differ in that they have no recesses 10. Rather, in the alternative embodiments of the plate 6 each have a plurality of openings 25 instead of a recess 10 is provided. In each case, a plurality of openings 25 surrounds a respective wafer receiving area of the plates 6. Preferably, the openings 25 adjoin the respective wafer receiving area radially outwards, but within a tolerance deviation in use it can also lead to a small distance between wafer receiving area and openings 25 , or come to a small overlap of wafer receiving area and openings 25.

Each plate 6 has a plurality of apertures 25 each radially surrounding a respective wafer receiving area. The apertures 25 can not completely surround the wafer receiving areas, as in the cavities 10, otherwise the wafers could not contact the plates 25, the wafer receiving areas preferably at least 90% surrounded in the radial direction. The effect of the openings 25 is that there is substantially no plate material (preferably less than 10% of the circumference of the wafer receiving area) in adjacent plates 6 within a wafer boat in an area directly adjacent to the wafer receiving area. Specifically, in the embodiment according to FIGS. 6 and 8, four identically sized openings 25 are provided along a respective side edge of a wafer receiving area. These are equally spaced, so that there are webs between them. In this embodiment, webs also form adjacent to the edge regions of the wafer receiving regions. The webs are aligned with the attachment points of the receiving elements 9, which may also be attached to the plates radially outside the area enclosed by the openings 25. Of course, the number of respective openings 25 may vary and, in particular

A single opening may also be provided adjacent the upper edge of the wafer receiving area.

In the embodiment according to FIG. 7, another configuration of openings 25 is shown. In particular, adjacent the top edge of the wafer receiving area, there is provided a single elongated opening 25 which extends substantially the entire length of the top edge. Adjacent to the other side edges of the wafer receiving area, two elongated openings 25 each having different lengths are provided. The web formed between the openings 25 is aligned with the attachment points of the receiving elements 9. Adjacent to the corners of the wafer receiving area, further triangular openings 25 are provided.

As one skilled in the art will appreciate, the arrangement and number of apertures may be varied and it is also possible to combine the different types of apertures and to provide the different aperture types on different panels 6 (which are then immediately adjacent to each other in the wafer boat); Preferably, however, the openings 25 should surround the wafer receiving area at least 90% in the radial direction.

In a particular embodiment, not shown, it is possible that the openings 25 surround the wafer receiving areas less even then a radial surrounding of at least 50%, in particular of 80% should be provided. In this particular embodiment, the different plates 6 of a wafer boat 1 (with bottom / top contact tabs 13) located directly adjacent to each other in the wafer boat 1 are formed so that apertures 25 of one plate 6 are offset from apertures 25 of the other plate. In this way, even with a smaller percentage of the radial surrounding of the openings 25 with respect to the wafer receiving areas, it can be achieved that there is substantially no plate material (preferably less than 0% of the circumference) in adjacent plates 6 within a wafer boat in an area directly adjacent to the wafer receiving area of the wafer receiving area).

In the following, the basic structure of a plasma treatment device 30, in which a wafer boat 1 of the above type can be used, will now be explained in more detail with reference to FIG. 5, which shows a schematic side view of the treatment device 30.

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. 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 tube member 36 receiving elements not shown in detail are provided, which form a receiving plane for receiving a wafer boat 1 (which is only partially shown in Fig. 5), 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 By appropriate receiving elements and or a direct placement on the tubular element is thus defined in combination with the dimensions of the wafer boat, a receiving space in which a properly inserted wafer boat is. The wafer boat can be traded as a whole in the loaded state into and out of the process chamber 38 via a suitable handling mechanism, not shown. In this case, upon loading of the wafer boat, an electrical contact is made automatically with in each case at least one contact block 15 of each of the groups of plates 6, as is known.

To the interior of the tube member 36, a lower gas guide 44 and an upper gas guide 46 are further provided, each allowing the introduction and / or suction of gas. The gas guides 44, 46 are provided at diametrically opposite ends of the pipe member around a To allow flow through the receiving slots of a recorded wafer boat with gas

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, although of course any other number may be provided. For example, the gas sources may be 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 entrances of the Provide gas control unit 60. The gas control unit 60 has two outputs, wherein one of the outputs is connected to the lower gas guide 44 and the other with a pump 70 of the vacuum control unit 62. The

Gas control unit 60 can suitably connect the gas sources 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 44 introduce different gases into the process chamber.

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 46 and can hereby the

Pump process chamber to a predetermined pressure. The connection from the gas control unit 60 to the pump serves to dilute from the process chamber pumped process gas optionally with N ₂ .

The electrical control unit 64 has at least one voltage source suitable for applying at least one high-frequency voltage to an output thereof. 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 over a corresponding one

Vacuum and temperature suitable implementation through the casing 40 and introduced into the tube member 36.

The operation of the plasma treatment device 30 will now be explained in more detail with reference to the drawings, by way of example a plasma-assisted silicon nitride or aluminum oxide deposition in a plasma stimulated by 40 kHz being described 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 range from 20 kHz to 450 kHz or even higher.

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 twelve wafers, in the present example in particular Si wafers are added, in each case six on each of the plates 6. The wafers are recorded so 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.

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

Process chamber via the vacuum control unit 62 are pumped to a predetermined negative pressure. Upon reaching the predetermined negative pressure, 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 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.

Via the electrical control unit 64, an RF voltage having a frequency of 40 kHz 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 Siliziumnitridabscheidung on the wafers. In the region of the depressions 10 in the plate elements 6, the attenuation of the distance between the plates locally causes a weakening of the distance between the plates. Thus, the plasma is attenuated directly adjacent to the edge region of the wafer (radially outside the wafer), ie, it is locally less dense than in other areas between the plates 6. As a result, edge effects and in particular a backside separation (wrapper) can be prevented or at least reduced. A corresponding effect of attenuation of the plasma also results in the plates 6 with openings 25, since in the region of the openings 25 between the plates results in a greatly attenuated plasma. The effect may be stronger than in the wells.

The gas flow is maintained during the deposition process to minimize local depletion of the process gas relative to the active gas

Components to avoid. 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 are then brought back to ambient pressure. As can be seen from the above description, the wafer boat 1 of the above type offers the advantage that an attenuated plasma is generated in the edge region (radially outside) of the wafer.

The plates 6, the treatment device 30 and the wafer boat 1 were explained in more detail with reference to certain embodiments of the invention with reference to the drawing, without being specifically shown

Embodiments to be limited. In particular, the plates 6 of the wafer boat 1 could have other dimensions and be sized to accommodate a different number of wafers.

Claims

claims

Plate element for a wafer boat for the plasma deposition of disc-shaped wafers, in particular semiconductor wafers for semiconductor or photovoltaic applications, wherein the plate element is electrically conductive and on each side at least one receiving unit for receiving a wafer in a wafer receiving region, characterized by at least one recess in at least one side of the plate member and / or at least one opening in the

Plate element, wherein the at least one recess and / or the at least one opening in the plate member is at least partially radially outside of the wafer receiving region and directly adjacent thereto.

A panel member according to claim 1, wherein the panel member has a corresponding recess on both sides.

A plate member according to any one of the preceding claims, wherein the recess substantially completely surrounds the wafer receiving region.

A panel member according to any one of the preceding claims, wherein the panel member has a plurality of apertures each lying at least partially radially outside the wafer receiving area and adjacent thereto.

A plate element according to any one of the preceding claims, wherein the apertures in the plate element radially surround at least 50%, preferably at least 80% of the wafer receiving area.

Wafer boat for the plasma treatment of wafer-shaped wafers, in particular semiconductor wafers for semiconductor or photovoltaic applications, comprising a plurality of plate elements arranged parallel to each other according to one of the preceding claims, wherein adjacently arranged plate elements are electrically insulated from each other.

A wafer boat according to claim 6, wherein openings in adjacent ones

Plate elements are arranged offset from one another.

Plasma wafer-shaped wafer processing apparatus, in particular semiconductor wafers, comprising

a process space for receiving a wafer boat according to any one of the preceding claims;

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

at least one voltage source which is suitably connectable to the electrically conductive receiving elements of the wafer boat in order to apply an electrical voltage between directly adjacent wafers housed in the wafer boat.