PHYSICAL VAPOR SEPARATION DEVICE WITH SHORT-CIRCUIT INTERRUPTION SYSTEM

Description

TECHNICAL FIELD

[0001] The invention relates to the field of physical vapor deposition, also called PVD deposition (from the English “Physical Vapor Deposition” ), and for example known from document US 2015 / 0371847 A1.

[0002] It concerns more particularly the treatment of a case of electrical short circuit between a target located in a deposition chamber, and the bottom of this deposition chamber, in the event of an accidental fall of a substrate.

[0003] The invention has numerous applications, for example in the field of manufacturing photovoltaic cells, or in any other sector of the microelectronics industry. STATE OF PRIOR ART

[0004] As is known, physical vapor deposition (PVD) is a process of covering a surface of a substrate with atoms or molecules of a material to be deposited, which adhere to the substrate to be covered by passing through a passive (vacuum or inert atmosphere) or active (plasma, reactive gas) medium.

[0005] Generally, a PVD deposition device comprises a deposition chamber in which one or more targets are electrically powered, while the wall delimiting the chamber is connected to ground. In the case where the deposition is intended to be carried out on a surface of the substrate facing downwards, i.e. facing the bottom of the chamber, the targets are generally arranged between the substrate and this same bottom of the chamber, close to the latter.

[0006] Due to this configuration of the elements inside the chamber, there is a risk that the substrate could accidentally fall from its support, and come into contact simultaneously with one of the targets and the bottom of the chamber. This results in a short circuit, which could damage the target in question.

[0007] When such an accidental event occurs, the only currently known solution to remedy it is to open the deposition chamber, then remove the fallen substrate, before cleaning the affected target. However, this principle requires the implementation of numerous time-consuming operations, including stopping the deposition process, stopping the turbo-molecular pumps and the chamber ventilation, opening the chamber to manually remove the fallen substrate, cleaning the target, closing the chamber again, re-vacuumizing and applying a leak test, requalifying the equipment, etc. In total, this principle requires an intervention time of at least 9 hours, or even more when the problem appears after a large deposition has already been carried out in the chamber.In this case, a change of the chamber protection sheets may be necessary, and it involves an additional intervention time of at least 24 hours, during which the PVD deposition device must remain stopped.

[0008] There is therefore a need to optimize the management of short-circuit cases in the chambers of PVD deposition devices. SUMMARY OF THE INVENTION

[0009] To meet this need, the invention relates to a physical vapor deposition device, comprising a deposition chamber partly delimited by a chamber bottom, the device further comprising, housed in the chamber: substrate support means; and at least one target arranged in a lower part of the chamber, between the substrate support means and the chamber bottom in relation to a direction of the height of the deposition device.

[0010] According to the invention, the deposition device further comprises a short-circuit breaking system capable of being caused by a substrate that has fallen and is in a short-circuit position in simultaneous contact with the target and the chamber bottom, the short-circuit breaking system comprising a support structure on the possible substrate(s) that have fallen into the short-circuit position, as well as means for setting the support structure in motion in a space located between the chamber bottom and the target.

[0011] Similarly, the invention also relates to a method for breaking a short circuit in such a deposition device, the method comprising moving the support structure in the space located between the chamber bottom and the target, so as to come into contact with the substrate in the short-circuit position and then to move / break it, so that it is no longer in simultaneous contact with the target and the chamber bottom.

[0012] The invention thus provides a simple, effective solution, requiring a particularly short intervention time to break a short circuit which may have occurred following the accidental fall of a substrate into the bottom of the chamber.

[0013] As an indication, stopping the deposition process, setting the support structure in motion to move / break the fallen substrate, and then restarting the process require a machine downtime of approximately 1 hour. This downtime is therefore significantly lower than that required with the known prior art solution, which generates an extremely significant productivity gain.

[0014] The invention preferably provides at least one of the following optional technical features, taken alone or in combination.

[0015] Preferably, said at least one target arranged in the lower part of the chamber corresponds to one or more rotating targets, preferably along one or more axes of rotation parallel to a main plane of the chamber bottom. However, the use of fixed targets remains conceivable within the framework of the present invention.

[0016] Preferably, in the height direction, the spacing between said at least one target arranged in the lower part of the chamber, and the bottom of the chamber, is less than 20 mm.

[0017] Preferably, the support structure of the short-circuit breaking system comprises a support bar parallel to a main chamber bottom plane. Any other form of support structure may nevertheless be envisaged, without departing from the scope of the invention.

[0018] Preferably, the chamber bottom is equipped with at least one gas injection ramp in the deposition chamber, and the support structure of the short-circuit breaking system comprises, associated with each gas injection ramp, a support portion intended to be moved above the injection ramp. This makes it possible to eliminate any short circuit likely to occur between a target, and a gas injection ramp also connected to ground while being in contact with the chamber bottom.

[0019] Preferably, the movement means are designed to move the support structure of the short-circuit breaking system in translation. However, any other movement may be envisaged, such as a circular movement, or even a more complex movement, but which preferably makes it possible to maintain the support structure in a plane parallel to the main plane of the chamber bottom.

[0020] Preferably, the movement means comprise a pneumatic cylinder, preferably telescopic. Other movement means may be envisaged, such as other types of cylinders, or even a worm screw, a linear motor with a protective cover, etc.

[0021] Preferably, the short-circuit breaking system comprises a device for controlling the movement means, the control device being operable by an operator. These means therefore allow the operator to manually operate the control device, for example via a simple on / off button on the control device.

[0022] Alternatively or simultaneously, the deposition device comprises a short-circuit detection system between said at least one target arranged in the lower part of the chamber, and the chamber bottom, and this detection system is connected to the short-circuit breaking system so as to automatically actuate the device for controlling the movement means, in the event of short-circuit detection.

[0023] Preferably, the substrate support means are means for moving substrates within the deposition chamber. Alternatively, the support means could be designed to hold the substrates in a fixed position in the deposition chamber, without departing from the scope of the invention.

[0024] Preferably, the deposition chamber comprises a first compartment in which said at least one target is located, arranged in the lower part of the chamber, as well as a second compartment communicating with the first and housing at least one target arranged in an upper part of the chamber, the substrate support means being arranged under said at least one target arranged in the upper part of the chamber.

[0025] Preferably, said at least one target arranged in the lower part of the chamber is an integral part of a removable target block comprising an upper cover for closing the deposition chamber.

[0026] Preferably, the target block comprises target supports arranged between the upper closing cover and the target(s) arranged in the lower part of the chamber.

[0027] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] This description will be made with regard to the attached drawings, among which; [ Fig 1 ] is a schematic cross-sectional view of a PVD deposition device, according to a preferred embodiment of the invention; [ Fig 2 ] is a sectional view taken along line II-II of the figure 1 ; [ Fig 3 ] is an enlarged view of a part of the view of the preceding figure, showing a pneumatic cylinder for translating a support structure of a short-circuit breaking system; [ Fig 4 ] represents a more detailed perspective view of the jack shown in the previous figure; [ Fig 5 ] represents a perspective view, even more detailed, of a part of the jack shown in the previous figure; [ Fig 6 ] represents a perspective view of a target block comprising targets intended to be located in the lower part of the deposition chamber of the PVD deposition device shown in the Figures 1 and 2; [ Fig 7 ] represents a front view of the target block shown in the previous figure; [ Fig 8 ] represents a perspective view of a portion of a substrate holding tray; and [ Fig 9 ] represents a schematic side view illustrating a short-circuit breaking step between the chamber bottom and one of the targets, following the accidental fall of a substrate. DETAILED STATEMENT OF PREFERRED EMBODIMENTS

[0029] In reference to the figures 1 to 3 , a PVD deposition device is shown according to a preferred embodiment of the invention. This deposition device is suitable for numerous applications, in particular that of the manufacture of photovoltaic cells. However, other applications are possible, in particular in the field of the microelectronics industry.

[0030] The PVD deposition device, bearing the reference numeral 1 in the figures, mainly comprises a deposition chamber 2 delimited by a wall 4. Due to the substantially parallelepipedal shape of the chamber 2, the wall 4 comprises a chamber bottom 6, side walls 8, as well as an upper wall 10. The chamber bottom 6 is inscribed in a main chamber bottom plane 12, oriented horizontally or substantially horizontally. The side walls 8 are orthogonal or substantially orthogonal to this plane 12, while the upper wall 10 is parallel or substantially parallel to this same main chamber bottom plane 12.

[0031] In this preferred embodiment, the chamber 2 defines a first compartment 2a, in which there are targets 14a arranged in the lower part of the chamber, in relation to a direction of the height 16 of the device 1. The chamber also defines a second compartment 2b, in which there are targets 14b arranged in the upper part of the chamber. The first and second compartments are adjacent in a transverse direction 18 of the device 1, and separated from each other by one or more intermediate partitions 20, of openwork design. As a result, the two compartments 2a, 2b communicate with each other in the transverse direction 18 of the deposition device, and the depression applied within the chamber 2 thus remains the same within each of these two compartments 2a, 2b.

[0032] Equipment 22 of the device 1 is arranged under the bottom of the chamber 2, and shown only schematically on the figure 1. Furthermore, in a conventional manner known to those skilled in the art, the targets 14a, 14b are supplied with direct current, while the wall 4 of the chamber 2 is connected to ground.

[0033] The device 1 also comprises support means 24 for the substrates 26 on which the deposition is to be carried out. These support means 24 are carried internally by the side walls 8 of the chamber, and they have a known design which will not be further described here. It is simply indicated that these support means 24 are designed to allow the movement of the substrates 26 inside the chamber 2, along a movement path which is preferably rectilinear and parallel or substantially parallel to the transverse direction 18 of the device. On the figure 1, the path of movement of the substrates 26 has been represented schematically by the dotted line 28, which therefore extends through the first and second compartments 2a, 2b, passing through the openwork parts of the intermediate partitions 20. In this regard, it is indicated that the two side walls 8 located at the opposite ends of the chamber, in the transverse direction 18, are equipped with sealed openings 30 for respectively the introduction and extraction of the substrates 26 into and out of the chamber 2. In this way, the substrates 26 can for example successively enter several chambers of several distinct PVD deposition devices, arranged in series.

[0034] In the first compartment 2a, in the direction of the height 16, the targets 14a are arranged between the support means 24 and the chamber bottom 6 near which these targets 14a are located. Moreover, it is provided that the vertical spacing “E” between the targets 14a and the chamber bottom 6 is less than 20 mm, this spacing E having been referenced on the figure 1 .

[0035] The number of targets 14a is two here, but it could differ, without departing from the scope of the invention. These targets 14a are integrated into a first removable target block 32a, also shown in the figures 6 And 7 .

[0036] The first removable target block 32a comprises an upper cover 36a for closing the first compartment 2a, this cover thus forming an integral part of the upper wall 10 delimiting the deposition chamber 2. Vertical target supports 34a are arranged between the upper closing cover 36a and the targets 14a, being arranged at the ends of the block 32a in a direction 38 of the depth of the device 1, along which the targets 14a extend. In this way, there is no mechanical interference between the vertical supports 34a and the substrates 26 moving in the center of the chamber 2, along the movement path 28.

[0037] Here, the targets 14a each adopt a general shape of a cylinder of circular section, and they are rotatable along axes 40a parallel to each other, and parallel or substantially parallel to the direction 38 and to the main chamber bottom plane 12. Each of the two targets 14a thus extends over substantially the entire depth of the first compartment 2a, along the direction 38.

[0038] Similarly, the targets 14b are integrated into a second removable target block 32b, comprising an upper cover 36b for closing the second compartment 2b, this cover therefore also forming an integral part of the upper wall 10 delimiting the deposition chamber 2. Vertical target supports 34b, shorter than the supports 34a, are arranged between the upper closing cover 36b and the targets 14b, also being arranged at the ends of the block 32b in the direction 38.

[0039] With the design adopted, the targets 14a located in the lower part of the chamber 2, under the substrate support means 24, allow the deposition of material on the lower surface of the substrates 26 moving in the first compartment 2a, along the path 28. This inner surface of the substrates, oriented towards the bottom of the chamber 6, is also called the rear surface or face of the substrate. Conversely, the targets 14b located in the upper part of the chamber 2, above the substrate support means 24, allow the deposition of material on the upper opposite surface of the substrates 26 moving in the second compartment 2b, still along the movement path 28. The upper surface of the substrates, oriented towards the upper wall 10 delimiting the chamber 2, is also called the front surface or face of the substrate.

[0040] The PVD deposition device 1 is also equipped with several gas injection ramps 47a, 47b. Indeed, in the first compartment 2a, the chamber bottom 6 supports two inert gas injection ramps 47a, located respectively at the two opposite ends of this compartment 2a, in the transverse direction 18. In the same way, in the second compartment 2b, the upper cover 36b supports two inert gas injection ramps 47b, located respectively at the two opposite ends of this compartment 2b, in the transverse direction 18.

[0041] One of the particularities of the invention lies here in the implementation of a short-circuit breaking system capable of being caused by a fallen substrate 26, and being in a short-circuit position in simultaneous contact with one of the two targets 14a, and the chamber bottom 6. Such a short-circuit position is shown schematically on the figure 9In this position, a short circuit is likely to occur, corresponding to an electric field between the chamber bottom 6 connected to ground and the target 14a supplied with direct current, these two elements 14a, 6 then being electrically connected by the dropped substrate 26.

[0042] The short-circuit breaking system 50 firstly comprises a structure 52 for supporting the possible substrate(s) 26 which have fallen into the short-circuit position.

[0043] The support structure 52 may comprise a support bar 54 parallel to the main plane of the chamber bottom 12, and parallel or substantially parallel to the transverse direction 18. This support bar 54 preferably extends over approximately the entire transverse length separating the two gas injection ramps 47a, being housed between them, in a space 56 situated vertically between the chamber bottom 6 and the two targets 14a. The support bar 54 is here straight or substantially straight, but it could be replaced by any other shape, for example a V shape with the tip of the V facing forward in the direction of movement of this support structure 52.

[0044] The support structure 52 may be completed, at each of the two opposite ends of the support bar 54, with a support portion 58 intended to be moved above its associated injection ramp 47a. Each support portion 58 preferably takes the form of an upward step at the end of the bar. It thus makes it possible to deal with possible cases of short-circuit created by a substrate accidentally dropped and immobilized between one of the two targets 14a, and one of the two gas injection ramps 47a also connected to ground, via the chamber bottom 6.

[0045] In order for the support structure 52 to sweep the entire space 56, or a large part of the latter, the short-circuit breaking system 50 is completed by means 60 for setting the support structure 52 in motion in this space 56. The setting means 60 here correspond to means making it possible to move the support bar 54 in translation in the direction 38, therefore orthogonally to the proper axis of the bar 54, as has been shown diagrammatically by the support structure 52 in dotted lines on the figure 2 . To do this, the movement means preferably comprise a pneumatic cylinder 60, of telescopic design to limit the space requirement outside the chamber 2. This pneumatic cylinder 60, visible on the figures 2 to 5, is carried by one of the side walls 8, and it has a fixed body arranged externally to the chamber 2 on this side wall 8. This is crossed in a sealed manner by the different sections of the telescopic piston rod, these sections being referenced 62 on the figures 3 to 5 , and represented only schematically in dotted lines on the figure 2 , in the deployed position. Between the rod sections 62, reinforced sealing means are provided to prevent possible leaks of the control air from the cylinder, towards the interior of the chamber 2 under depression. These sealing means comprise, for example, between any two rod sections 62 and directly consecutive, the axial succession of a flat seal 64, a ferromagnetic liquid 66, another flat seal 64, and finally a scraper seal 68 which is located at the end of each rod section 62.

[0046] Associated with this pneumatic cylinder 60, the short-circuit breaking system 50 further comprises a control device 70 shown diagrammatically on the figure 2 This control device 70 of the jack 60 can be operated manually by an operator wishing to eliminate an accidental short circuit within the deposition chamber 2, for example via a simple on / off button integrated into this control device 70.

[0047] Additionally, or in an alternative embodiment, the actuation of the control device 70 can be carried out automatically, after detection of an accidental and potentially damaging short circuit for the targets 14a.

[0048] To do this, the device 1 may comprise a system 72 for detecting a short circuit between one of the two targets 14a and the chamber bottom 6, this system being able to adopt any design deemed appropriate. The detection may also be carried out directly or indirectly. For example, the detection system 72 shown diagrammatically in the figure 2can be based on the control and monitoring of the power required from the direct current generator which supplies the targets 14a. Indeed, it is possible to monitor the power delivered by this generator, as well as the lost power or leaks. Generally this lost power is of the order of 4 to 5 W in normal use, but during a short circuit caused by a substrate accidentally falling into the bottom of the chamber, this power can reach 800 to 1000 W. Thus, the jack 60 can be actuated automatically according to the signal supplied by the detection system 72 to the control device 70. In other words, the proposed solution allows the automatic actuation of the jack 60, as soon as the lost power value exceeds a threshold which is predetermined so as to avoid damage to the targets 14a.

[0049] Whatever the nature of the actuation produced, manual or automatic, the control device 70 causes the telescopic rod of the jack 60 to extend. This causes the support structure 52 to move in translation so as to sweep the entire space 56 under the targets 54a, in order to break / move the substrate(s) accidentally dropped into a short-circuit position between one of the targets 14a and the chamber bottom 6. Indeed, during such a movement of the support structure 52 shown diagrammatically on the figure 9 , the entry into contact of this structure 52 with the fallen substrate 26 causes the latter to break, or to destabilize until it falls flat on the bottom of the chamber 6. In both cases, the breaking / removal of the short circuit is obtained in a simple and satisfactory manner, since the substrate 26 is no longer in simultaneous contact with the target 14a and the bottom of the chamber 6.

[0050] In this regard, it is noted that the substrates 26 treated inside the deposition chamber 2 can be placed directly on the support means 24 which have been described previously. But more usually and preferably, these substrates 26 are arranged within holding trays (from the English "trays" ), which are themselves supported by the support means 24. These plates 74, one of which is partially shown on the figure 8 , therefore serve as an intermediate support between the substrates 26 and the support means 24 fixed to the side walls of the chamber 2. Still in a known manner, each plate 74 comprises a frame 76 delimiting through orifices 78, in which the substrates 26 are held.

[0051] Finally, it is specified that the support bar 54 can be in contact with the interior surface of the chamber bottom 6, so as to perform a scraper function during its movement in the lower space 56 of the chamber 2. Alternatively, a vertical clearance can be provided between the chamber bottom 6 and this support bar 54.

[0052] Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples, and the scope of which is defined by the appended claims.

Claims

1. A physical vapour deposition device (1), comprising a deposition chamber (2) partly delimited by a chamber bottom (6), the device further comprising, housed in the chamber: - substrate support means (24); and - at least one target (14a) arranged in a lower part of the chamber (2), between the substrate support means (24) and the chamber bottom (6) in relation to a direction of the height (16) of the deposition device, characterised in that it further includes a short-circuit breaking system (50) capable of being caused by a substrate (26) which has fallen and is in a short-circuit position in simultaneous contact with the target (14a) and the chamber bottom (6), the short-circuit breaking system (50) comprising a structure (52) for supporting the possible substrate(s) (26) which has fallen into the short-circuit position, as well as means (60) for moving the support structure (52) in a space (56) located between the chamber bottom (6) and the target (14a).

2. The deposition device according to claim 1, characterised in that said at least one target (14a) arranged in the lower part of the chamber corresponds to one or more rotating targets, preferably along one or more axes of rotation (40a) parallel to a main plane of the chamber bottom (12).

3. The deposition device according to claim 1 or 2, characterised in that in the height direction (16), the spacing (E) between said at least one target (14a) arranged in the lower part of the chamber, and the chamber bottom (6), is less than 20 mm.

4. The deposition device according to any one of the preceding claims, characterised in that the support structure (52) of the short-circuit breaking system (50) comprises a support bar (54) parallel to a main chamber bottom plane (12).

5. The deposition device according to any one of the preceding claims, characterised in that the chamber bottom (6) is equipped with at least one ramp (47a) for injecting gas in the deposition chamber (2), and in that the support structure (52) of the short-circuit breaking system (50) comprises, associated with each gas injection ramp (47a), a support portion (58) intended to be moved above the injection ramp (47a).

6. The deposition device according to any one of the preceding claims, characterised in that the movement means (60) are designed to move the support structure (52) of the short-circuit breaking system (50) in translation.

7. The deposition device according to any one of the preceding claims, characterised in that the movement means (60) comprise a pneumatic cylinder, which is preferably telescopic.

8. The deposition device according to any one of the preceding claims, characterised in that the short-circuit breaking system (50) comprises a device (70) for controlling the movement means (60), the control device (70) being operable by an operator.

9. The deposition device according to any one of the preceding claims, characterised in that it comprises a system (72) for detecting a short circuit between said at least one target (14a) arranged in the lower part of the chamber, and the chamber bottom (6), and in that the detection system (72) is connected to the short-circuit breaking system (50) so as to automatically actuate the device (70) for controlling the movement means (60), in the event of detection of a short circuit.

10. The deposition device according to any one of the preceding claims, characterised in that the substrate support means (24) are means for moving substrates (26) inside the deposition chamber (2).

11. The deposition device according to any one of the preceding claims, characterised in that the deposition chamber (2) includes a first compartment (2a) wherein said at least one target (14a) is located, arranged in the lower part of the chamber, as well as a second compartment (2b) communicating with the first and housing at least one target (14b) arranged in an upper part of the chamber, the substrate support means (24) being arranged under said at least one target (14b) arranged in the upper part of the chamber.

12. The deposition device according to any one of the preceding claims, characterised in that said at least one target (14a) arranged in the lower part of the chamber forms an integral part of a removable target block (32a) comprising an upper cover (36a) for closing the deposition chamber (2).

13. The deposition device according to the preceding claim, characterised in that the target block (32a) comprises target supports (34a) arranged between the upper closing cover (36a) and the target(s) (14a) arranged in the lower part of the chamber.

14. A method for breaking a short circuit in a physical vapour deposition device (1) according to any one of the preceding claims, characterised in that it comprises moving the support structure (52) in the space (56) located between the chamber bottom (6) and the target (14a), so as to contact the substrate (26) in the short-circuit position and to move / break it, so that it is no longer in simultaneous contact with the target (14a) and the chamber bottom (6).