DE202010015818U1 - Apparatus for treating a substrate by means of a plasma - Google Patents

Abstract

Apparatus for treating a substrate by means of a plasma, comprising
a plurality of adjacent plasma units for respectively generating a plasma in a plasma region of the plasma units, the plasma units being arranged so that the plasma region of at least a first plasma unit overlaps a radiation region of at least one adjacent second plasma unit;
a control arrangement which is suitable for controlling at least the first and second plasma units independently of one another.

Description

The present invention relates to an apparatus for treating a substrate by means of a plasma.

In various technical fields, it is known to treat substrates by means of a plasma. In particular, in semiconductor technology, it is known to etch a surface of a substrate by means of a plasma or in a layer structure by a z. As plasma assisted oxidation to grow a SiO _x N _y Fim or to support a deposition of the vapor phase by means of a plasma (PECVD = Plasma Enhanced Chemical Vapor Deposition).

The plasma units used for the treatment of substrates each have a significantly higher ignition performance than a power required to maintain a once ignited plasma. Thus, a corresponding plasma unit must be energized to initially fire a plasma at high power, which is then reduced to a level at which the plasma is fed to treat the substrate.

This results in the problem that can result in the ignition of the plasma, a plasma pressure wave with high energy. In addition, very high energies of the plasma particles are present immediately after ignition, which can lead to damage to the substrate surface to be treated. Moreover, in the case of an SiO _x N _y film growth or PECVD process, a very high growth rate initially sets in, which correlates with the high ignition power fed in. However, such a high growth rate leads to a non-optimal layer composition and a non-optimal layer structure, as it was already Eisele, A. Ludsteck, J. Schulze, Z. Nenyei at the 10th IEEE International Conference on Advanced Thermal Processing of Semiconductors-RTP2002, Vancouver, Canada, ISBN 0-7803-7465-7, (2002), pages 11-1 , has been described.

One way to minimize the effect of this effect on the substrate is a variation in the distance between the plasma unit and the substrate to be treated so that a plasma is first ignited at a large distance and then, after the plasma power has been set to a lower treatment level, reduces the distance will, as it is in the unpublished DE 2009060230.5 is described. For this purpose, however, a corresponding apparatus design is necessary to allow the distance adjustment.

Based on the above-mentioned prior art, the object of the present invention is to prevent, or at least reduce, negative influences which may arise when a plasma is ignited onto a substrate.

According to the invention this object is achieved by a device according to claim 1. Further embodiments of the invention will become apparent from the dependent claims.

In the apparatus for treating a substrate by means of a plasma, a plurality of adjacent plasma units are provided for respectively generating a plasma in a plasma region of the plasma units, wherein the plasma units are arranged such that the plasma region of at least a first plasma unit overlaps a radiation region of at least one second plasma unit. Furthermore, a control arrangement is provided, which is suitable for controlling at least the first and second plasma units independently of one another. However, the control unit can also control each individual plasma unit independently of the others in such a way that apart from a spatial delay there is also a time delay.

Preferably, the at least one first plasma unit has an ignition power which is substantially smaller than the ignition power of the at least one second plasma unit, whereby the generation of high-energy plasma components can be reduced upon ignition of a plasma in the region of the first plasma unit. Preferably, the one first plasma unit is arranged outside a projection region of the substrate to be treated. In addition or alternatively, however, it may also be further away from the treating surface of the substrate than the at least one second plasma unit.

Preferably, a plurality of second plasma units are provided, which are arranged adjacently such that a respective plasma region of a second plasma unit overlaps a radiation region of an adjacent second plasma unit. As a result, a sequential ignition of adjacent second plasma units is possible. In particular, the plasma regions of at least two adjacent plasma units overlap to produce a more uniform total plasma.

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

1 a schematic sectional view through a plasma treatment apparatus;

2 a schematic cross-sectional view of the plasma treatment apparatus according to 1 with a cutting plane rotated by 90 degrees;

3 a schematic view from below of an array of plasma units, which in the arrangement according to the 1 and 2 can be used;

4 a schematic view from below of an alternative arrangement of plasma units, which in the device according to the 1 and 2 could be used;

5 a schematic plan view of different arrangement examples for plasma units, which in the device according to the 1 and 2 could be used.

Location or directional information used in the following descriptions refers primarily to the illustration in the drawings and therefore should not be taken as limiting. You can also refer to a preferred final arrangement.

The 1 and 2 show each 90 degree rotated cross-sectional views through a plasma treatment apparatus 1 for the treatment of flat substrates 2 , The substrates 2 In this case, semiconductor substrates may be in particular whose surface is etched by means of a plasma or on the surface of which a layer growth is carried out. The plasma treatment device essentially consists of a housing 3 Inside, a process chamber 4 defined, a substrate receiving unit 7 , a heating arrangement 8th as well as a plasma arrangement 9 ,

The housing 3 may be of any suitable type including a process chamber 4 defined inside, can be set in the desired, not shown inlets and outlets predetermined process conditions with respect to a gas composition and gas pressures. in a side wall of the housing 3 is a loading-unloading opening 12 provided, which has a movable door element 13 can be closed and opened.

Furthermore, the housing has 3 in opposite side walls a plurality of through holes 14 for receiving quartz tubes 16 , which in turn serve to accommodate heating units or plasma units, as will be explained in more detail below. The holes 14 are each pairwise formed in opposite side walls such that a quartz tube 14 through the process chamber 4 can extend through, perpendicular to the holes 14 having side walls. In a lower area of the process chamber 14 are eight such pairs of holes 14 with the corresponding quartz tubes received therein 16 intended. In an upper area are a total of ten pairs of holes 14 in the opposite side walls of the housing 3 educated. In this case, nine of these pairs lie on one line, while another pair is for this purpose down, ie offset to the center of the process chamber out. Also in these holes are each quartz tubes 16 added.

On an upper wall of the housing 3 is on the inside, ie inside the process chamber 4 a cover element 18 provided to the housing inner wall opposite one through the plasma assembly 9 protect generated plasma.

In the bottom of the case 3 is a passage opening for a support shaft 20 the substrate holding arrangement 7 intended. The substrate holding assembly consists essentially of a vertically extending support shaft 20 , a horizontally extending support plate 21 as well as support elements 22 , The support shaft 20 extends through the bottom of the case 3 and can be outside the case 3 For example, be connected to a drive motor to rotate the support shaft about its longitudinal axis and / or to move in the vertical direction. To a gas-tight implementation of the support shaft 20 through the housing 3 to allow appropriate sealing mechanisms, such as a bellows mechanism may be provided in the region of the implementation. The support shaft 20 For example, from one for electromagnetic radiation of the heating arrangement 8th essentially transparent material, such as quartz. Alternatively, the support shaft could 20 but also have a highly reflective surface.

The support shaft 20 carries at its upper end the support plate 21 , which is height adjustable via the support shaft both in the vertical direction, as well as about a longitudinal axis of the support shaft 20 is rotatable. The support plate 21 is preferably one for the electromagnetic radiation of the heating arrangement 8th constructed essentially transparent material. On top of the support plate 21 is a variety of support elements 22 provided, in turn, from a preferably for the radiation of the heating arrangement 8th transparent material is constructed. The support elements 22 are shown as conical tapered cones, on top of which the substrate 2 rests. The support elements 22 hold the substrate 2 spaced apart a certain distance to the support plate 21 , Overall, the substrate-holding arrangement could also have a different structure. In particular, the support plate could be constructed as a so-called susceptor having a projection surface corresponding to the substrate 2 and the electromagnetic radiation of the heating arrangement 8th absorbed, to be heated up and above it the substrate 2 to heat.

The heating arrangement 8th consists essentially of eight heating lamps 24 that in the eight quartz tubes 16 in the lower part of the process chamber 4 are arranged. The heating lamps 24 are designed as flashlights, which are essentially completely through the process chamber 4 extend through. The heating lamps 24 may be of any type necessary for heating the substrate 2 is suitable by means of electromagnetic radiation, such as tungsten halogen lamps. Although this is not shown in detail, the quartz tubes can 16 with a cooling medium, such as air flowing through, around the quartz tubes 16 and the heating lamps 24 to cool during operation. Of course, another heating arrangement may be used, such as a resistance heating arrangement, for example integrated in the support plate.

However, it is an alternative construction of the heating arrangement 8th conceivable, in which, for example, an arrangement of heating lamps 24 via a quartz plate opposite a process space for the substrate 2 is separate, as is known in the art.

The plasma arrangement 9 consists essentially of a first rod-shaped plasma unit 27 , as well as a plurality of second rod-shaped plasma units 28 , The first and second plasma units 27 . 28 are each in corresponding quartz tubes 16 taken up in the upper part of the process chamber 4 extend through them. While the second plasma units 28 in the quartz tubes lying in a row 16 are included, is the plasma unit 27 in the slightly downwardly offset quartz tube 16 arranged (see right outer quartz tube 16 in 2 ).

The plasma units 27 and 28 can each have substantially the same basic structure as, for example, in the DE 10 2008 036 766 A1 is described. The plasma units each have a waveguide 30 as well as an inner conductor 31 , The waveguide 30 has, as in the view from below according to 3 to recognize a section in which he is the inner conductor 31 completely surrounds, and a subsequent slotted area in which the inner conductor is gradually exposed until a free end of the inner conductor is completely exposed. The plasma units 27 and 28 are each of the type from one side (right, see 1 ) is energized. At the free end of the inner conductor 31 the first plasma unit 27 is also a resonator 32 (please refer 3 ) to promote ignition of a plasma in the region of the first plasma unit.

For the exact structure of the plasma units is on the DE 10 2008 036 766 A1 in this respect, the object of the present invention is made in order to avoid repetition.

As in the illustration according to the 2 and 3 can be seen, is the first plasma unit 27 represented smaller than the second plasma units 28 , This is intended to indicate that the first plasma unit 27 a lower power, in particular a lower ignition performance may have, as the second plasma units 28 , Alternatively, it is also possible, the first plasma unit 27 in the same manner as the second plasma units 28 , A separate embodiment in the manner described above is advantageous when the first plasma unit 27 is used as a designated ignition unit, as will be explained in more detail below.

In the 1 and 2 is in each case a plasma region of the respective plasma units 27 and 28 in the form of a dashed line surrounding the respective plasma unit. This is intended to be a conventional expansion range of a plasma, which by a corresponding plasma unit 27 . 28 is generated, be indicated. An actual radiation range of the plasma units before ignition of a plasma may go further than the plasma region shown, as the person skilled in the art can see.

The plasma units 27 and 28 can be controlled individually and / or in groups. In particular, they can be controlled individually and / or in groups with regard to the power fed in and the time control. This applies in particular to the first plasma unit 27 , For this purpose, a control unit, not shown, which is connected in a corresponding manner with the plasma units is provided.

The 4 shows an alternative arrangement of the plasma units 27 and 28 , wherein the second plasma units 28 are arranged in the same way as in 3 is shown. However, the second plasma unit extends 27 below and across the first plasma units 28 , In this case, the first plasma unit is arranged so that a plasma generated by it in a radiation region of all second plasma units 28 when they are powered, lies. In this case, both embodiments according to the 3 and 4 same, that the first plasma unit 27 is outside a projection range of a substrate to be treated, by the dashed line in the 3 and 4 is indicated.

The 5 shows further arrangement examples of the first plasma unit 27 relative to second plasma units 28 , which in turn can be arranged as well as in the 3 and 4 is shown. The first plasma units 27 are to improve the appearance in 5 hatched shown. The dotted circle in 5 again represents a projection surface of a substrate to be treated.

at 27a an arrangement of the first plasma unit is shown, which is substantially the arrangement according to 3 corresponds, that is, the first plasma unit extends substantially parallel to the second plasma units 28 and is adjacent to an outer second plasma unit 28 ,

at 27b is the arrangement according to 4 illustrated in which the first plasma unit perpendicular to the second plasma units 28 extends and a plasma region of the first plasma unit covers the plasma region of all second plasma units.

at 27c the arrangement of a first plasma unit is shown, which in turn is substantially parallel to the second plasma units 28 extends, but is shorter and beyond between two adjacent plasma units 28 is arranged. The first plasma units may in particular also be arranged above the first plasma units, as long as their plasma region has a radiation region of the adjacent second plasma units 28 overlaps.

at 27d In turn, a first plasma unit is shown, which is perpendicular to the plane between two adjacent second plasma units 28 extends.

The first and second plasma units 27 . 28 may be of a different basic type and in particular they may have different ignition powers. In particular, the first plasma unit 27 have a significantly lower ignition performance than the ignition performance of the second plasma units 28 , A firing rate of not more than 70% of the ignition power of the second plasma units, preferably of not more than 50% of the ignition power of the second plasma units, is regarded as significantly smaller. The ignition power of the first plasma unit should be preferred 27 a maximum of 20% or even less than or equal to 10% of the ignition power of the second plasma units 28 exhibit.

In the different representations, the first plasma units are each shown as having a projection area of the substrate 2 do not overlap. Although this may be advantageous to minimize ignition effects on a substrate surface, it is also possible to allow such overlap. It may be advantageous to provide the first plasma unit further apart from the substrate than the second plasma units. Depending on the actual ignition performance of the first plasma unit 27 However, this is not absolutely necessary, especially when the ignition power of the first plasma unit is in a power range in which the second plasma units a plasma for a treatment of the substrate 2 produce.

In the embodiments described above, in each case a first plasma unit 27 described, which differs in terms of their arrangement, size and other of second plasma units. However, it is also possible to have such a separate first plasma unit 27 completely dispense, and only the arrangement of second plasma units 28 provided that they are individually and or in groups controllable.

The operation of the device will be described below 1 explained in more detail with reference to the figures.

First, a substrate to be treated is introduced into the process chamber 4 loaded and held in a position and, as in the 1 and 2 is shown. The process chamber 4 is over the door element 13 closed, and it becomes a desired gas atmosphere within the process chamber 4 set. About the heating arrangement 8th can the substrate 2 to a desired process temperature within the process chamber 4 to be heated. By preheating the substrate (~ 400 ° C) even the plasma ignition power can be reduced. Directly above the substrate, the gas is as hot as the substrate in a cold wall reactor, and thus a plasma would also be ignitable at a lower power for that reason. Preferably, the substrate may be preheated to a temperature in the range of 200 to 600 ° C, preferably to a temperature of 400 ° C ± 50 ° C.

When the plasma treatment is to begin, and a corresponding gas atmosphere in the process chamber 4 is present, first the first plasma unit 27 applied with a Zündleistung to a plasma in the plasma region of the first plasma unit 27 to ignite. If the plasma is ignited, or even before, at least the adjacent to the first plasma unit 27 lying plasma unit 28 applied with a power that is substantially lower than their ignition performance, but sufficient plasma within the plasma region of the second plasma unit 28 to maintain. In particular, the second plasma unit 28 be applied with a power to be applied to the plasma for an initial treatment. During the treatment of the substrate 2 the power can then be changed accordingly, but at the beginning the desired power can be set directly.

Due to the fact that the first plasma unit 27 has already ignited and the plasma region of the first plasma unit has a radiation area of the directly adjacent second plasma unit 28 overlaps, also arises adjacent to this second plasma unit 28 a corresponding plasma. This plasma can then be correspondingly over the entire second plasma units 28 spread out, for example, from right to left according to 2 , In this case, the second plasma units 28 each be subjected to a power that is much lower than their ignition performance. In particular, they can be directly applied with the power suitable for an initial substrate treatment. The application of an ignition power to the second plasma units 28 , which would initially produce very high energy plasma particles is not necessary at any time, since the respective plasmas in the range of the second plasma units 28 be ignited by adjacent plasma.

As a result, high-quality coatings can be generated from the outset using plasmas without damaging the substrate surface during the ignition process.

In particular, a progressive plasma surface can be generated, which can optionally contribute to a cleaning of the substrate surface.

In an arrangement of the plasma units according to 4 It would be possible after the ignition of the first plasma unit 27 all other plasma units to ignite substantially simultaneously, since in the transversely extending arrangement of the plasma unit 27 to the plasma units 28 , whose plasma region, the radiation of all second plasma units 28 would cover.

As one skilled in the art will recognize, the plasma treatment may be controlled from the beginning with a desired plasma power. After the gentle ignition, the plasma power can be increased or decreased (changed) with arbitrary mathematical functions.

Of course, the plasma units can also be arranged differently, and it is also possible to provide a distance adjustment between the plasma units and the substrate, as for example in the not previously published DE 10 2009 060 230 is shown.

By using a designated ignition antenna, such as the first plasma unit 27 For example, it is possible to generate significantly less high-energy plasma particles during the ignition process, since the designated ignition antenna can be provided with a lower ignition power than the main units, ie the second plasma units 28 , By means of a corresponding spatial arrangement outside a projection region of the substrate to be treated, the proportion of the still high-energy plasma particles which still strike the substrate can be substantially minimized. By appropriate activation of the second plasma units, the initial growth rate of a layer to be formed on the substrate can be greatly reduced, resulting in higher-quality layers with regard to the charge-to-break-down Q _bd or the interface state density D _it .

Alternatively to using a designated firing antenna, such as the first plasma unit 27 it is also possible to use only one or one of the second plasma units for ignition. This can be realized by implementing a single or group control of the second plasma units. For example, if in 2 the first plasma unit 27 would not be provided, for example, the two outer, outside the projection range of the substrate 2 lying second plasma units 28 At the beginning of the process, ignition power is applied to ignite a plasma in the region thereof. The remaining second plasma units could in turn then be subjected to a much lower power than the ignition power, in turn, to provide a progressive plasma surface. This would run in this example from the outside in. Of course, it would be equally possible, only one of the outer second plasma units 28 to apply ignition power, and then to reach a plasma face advancing from one side to the other. Of course, depending on the arrangement of the plasma electrodes and corresponding control, it is also possible to generate a plasma front from the center to the outside.

Preferably, however, the plasma electrode used for the initial ignition of a plasma should each be outside a projection range of the substrate to be treated. As described above, a plasma with small plasma powers can be ignited in the main field of the second plasma units. It is also a particularly rapid ignition of the respective plasma in the region of the second plasma units 28 possible because they are ignited quickly by an adjacent plasma. Therefore, the present structure is particularly suitable for the application of a pulsed plasma during the substrate treatment, which can significantly reduce the average power over other pulsed plasmas.

In addition, a faster pulse is possible, resulting in a faster refreshment of the reactive species. If possible, one, in particular the designated ignition antenna, ie the first plasma unit, should be used in the pulse process 27 , are essentially operated continuously. Alternatively, it is of course also possible one or more of the second plasma units 28 operate continuously while the other second plasma units 28 be pulsed. Of course, a mutual pulsing of the plasma units would also be possible, as long as there is still a plasma present, in order to achieve a renewed ignition of the plasma in each case with a power which is substantially lower than the ignition power of the corresponding plasma unit.

The invention has been explained in detail above with reference to preferred embodiments, without being limited to the specific embodiments shown.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2009060230 [0005]
• DE 102008036766 A1 [0027, 0028]
• DE 102009060230 [0049]

Cited non-patent literature

• Eisele, A. Ludsteck, J. Schulze, Z. Nenyei at the 10th IEEE International Conference on Advanced Thermal Processing of Semiconductors-RTP2002, Vancouver, Canada, ISBN 0-7803-7465-7, (2002), pp. 11-1 [0004 ]

Claims (7)

Apparatus for treating a substrate by means of a plasma, comprising a plurality of adjacent plasma units for respectively generating a plasma in a plasma region of the plasma units, the plasma units being arranged such that the plasma region of at least a first plasma unit overlaps a radiation region of at least one adjacent second plasma unit; a control arrangement which is suitable for controlling at least the first and second plasma units independently of one another. The apparatus of claim 1, wherein the at least one first plasma unit has an ignition performance that is substantially less than the ignition power of the at least one second plasma unit. Apparatus according to claim 1 or 2, wherein at least a first plasma unit is arranged outside a projection region of the substrate to be treated. Device according to one of claims 1 to 3, wherein the at least one first plasma unit is further away from the surface of the substrate to be treated than the at least one second plasma unit. An apparatus according to any one of claims 1 to 4, wherein a plurality of second plasma units are provided adjacently arranged such that a respective plasma region of a second plasma unit overlaps a radiation region of an adjacent second plasma unit. The device of any one of claims 1 to 5, wherein the plasma regions of at least two adjacent plasma units overlap. Device according to one of claims 1 to 6, wherein the second plasma units each have rod-shaped microwave antennas.

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