GB2505647A

GB2505647A - A vacuum processing apparatus which neutralises plasma in a gas flow path

Info

Publication number: GB2505647A
Application number: GB201215806A
Authority: GB
Inventors: Jeff Hill; Michael Dachwald; Arne Hofmann
Original assignee: PVA TePla AG
Current assignee: PVA TePla AG
Priority date: 2012-09-05
Filing date: 2012-09-05
Publication date: 2014-03-12
Also published as: GB201215806D0

Abstract

The application provides a vacuum processing apparatus 10. The vacuum processing apparatus 10 includes comprising a first vacuum processing chamber 14, a second vacuum processing chamber 13, and a seal valve 100. In practice, the seal valve 100 provides a very small gas flow path 115 between the first vacuum processing chamber 14 and the second processing chamber 13 because of mechanical tolerances. The gas flow path 115 acts to neutralise plasma contained in the gas flow path 115. The gas flow path 115 preferably changes direction to increase its length and increase the opportunity for the plasma to recombine and become neutralised without causing damage within the second vacuum chamber 13. Also disclosed is a magnetic manipulator for adjusting the position of a substance in a vacuum processing chamber having a magnetic drive, a sealing device for a load lock door in a vacuum processing apparatus, and magnetic door position lock for a load lock door in a vacuum processing apparatus.

Description

A VACUUM PROCESSING APPARATUS

The application relates to a vacuum processing apparatus. In particular, it relates to an improved substrate magnetic ma-nipulator, to an improved load lock door, and to an improved seal for the vacuum processing apparatus.

US 5,514,925 discloses a magnetic feed-through manipulator adapted to seal a chamber. The manipulator has a shaft, a non- magnetic tubular housing, a ferromagnetic armature, and alter-nately polarized magners. The shaft is used for inserting in the chamber and is capable of rotational and longitudinal movement. The ferromagnetic armature has an even number of longitudinal surface splines freely movable within the nonmag-netio tubular housing, wherein the shaft is axially coupled to the ferromagnetic armarure. The alternately polarized magnets slide and rotate on the outer surface of the housing for con-trolling the ferromagnetic armature. Two or more armatures in the same housing may control a like number of manipulator shafts independently.

US 6,471,459 P2 discloses a magnetic drive system for moving a substrate transfer shurtle along a linear path between cham-bers in a semiconductor fabrication apparatus. The magnetic drive aystem includea at leaat one magnetic rack and pinion device. The rack and pinion device includes a rack with rack magnets, and a rotatable pinion with pinion magnets. The rack is attached tc the track magnets and it is secured with the shuttle. The pinion is attached to the pinion magnets and it is positioned adjacent to the rack so that the pinion magnets magnetically engage wirh the reck magnets. A rotation of the pinion would cause the shuttle to move along a linear path. A set of lower guide rollers supports the shuttle, and a set of upper guide rollers prevents the shuttle from lifting off the lower guide rollers.

The magnets may be oriented with a helix angle between their primary axis and the axis of rotation of the pinion. One mag-netic rack and pinion device can be located on each side off the shuttle.

It is an object of this application to provide an improved vacuum processing apparatus.

The applicaticn provides a vacuum processing apparatus. The processing apparatus treats a substrate, such as a lead frame or a semiconductor wafer, in a vacuum. The vacuum refers to a low-pressure environment, which can allow plasma to reach and to treat the substrate.

The processing apparatus includes a first vacuum processing chamber, a second vacuum processing chamber, and a seal valve.

Because of mechanical colerances, the seal valve provides a very small gas flow path that extends between the first vacuum processing chamber and the second processing chamber. The gas flow path allows a small amount of plasma to flow between the first vacuum processing chamber and the second processing chamber, wherein the gas flow path acts to neutralise essen-tially the plasma contained in the gas flow path. In practice, a very small gap often defines or forms the gas flow path.

Plasma may be released in the first vacuum processing chamber to clean a substrate, such as a lead frame, which is placed in the processing chamber. The vacuum in the said processing chamber allows the plasma to reach the substrate. The plasma acts to remove a thin layer of external surface of the sub-strate. The removing of the thin layer serves to clean the substrate. Inside walls of this processing chamber are often selected such that the released plasma would essentially not damage the processing charter by removing a thin layer of the inside surfaces of the walls.

A small amount of the plasma may travel via the gas flow path from the first vacuum processing chamber to the second vacuum processing chamber. The seal valve neutralises the plasma such that plasma reaching the second vacuum processing chamber would not damage essenrially the second vacuum processing chamber. The neutralising is achieved by allowing free elec-trons of plasma in the gas flow path to bind or recombine with atoms. This binding talces occurs as the plasma travels through the gas flow path. In effect, the plasma is converted essen-tially to a non-ionized gas or gases. In other words, a very small amount of free electrons of plasma may reach the second vacuum processing chamber in which these free electrons does not produce visible or detectable damage in the second vacuum processing chamber.

In particular, plasma comprises positive and negative parti-cles, wherein the overall charge of the plasma is about zero.

Although these particles are unbound, when these charges move they generate electrical currents with magnetic fields. The negative particles refer to free electrons, wherein the free electrons are not bound to an atom. The positive particles re- fer to molecules or atoms. In general, the plasma shows dif-ferent features.

The plasma exhibits plasma approximation, wherein charged par-ticles of the plasma are close enough together such that each particle influences many nearby charged particles, rather than just interacting with The closest particle. These collective effects are a distinguishing feature of the plasma. The plasma approximation is valid when the number of charge carriers within the sphere of influence (cailed the Debye sphere whose radius is the Debye screening length) of a particular particle is higher than unity to provide coilective behaviour cf the charged particles. The average number of particles in the Dc-bye sphere is given by the piasrna parameter, "A'T (the Greek letter Lambda) The plasma also shows bulk interactions in which Debye screen- ing iength is short compared to the physical size of the plas-ma. This means that inceractions in the bulk of the plasma are more important than those at its edges, where boundary effects may take place. When this criterion is satisfied, the plasma is quasi-neutral.

The plasma also has plasma frequency, wherein the eiectrcn plasma frequency, which measures plasma oscillations of the electrons, is large compared to the electron-neutrai collision frequency that measures frequency of collisions between dcc-trons and neutral particles. Vhen this condition is valid, electrostatic interactions dominate over the processes of or-dinary gas kinetics.

For the plasma to exisc, ionization is necessary. The term "plasma density" by usually refers to "electron density", which refers to the number of free electrons per unit volume.

The degree of ionization of plasma relates to proportion of atoms that have lost or gained electrons, which is controlled mostly by the temperature. Even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma In terms of response to mag-netic fields and high electrical conductivity. The degree of ionization, a is defined as a = ni/(ni -I-na), wherein ni is the number density of ions and na is the number density of neutral atoms. The eleotron density is related to this by the average charge state <Z> of the ions through ne = <Z> ni where ne is the number density of electrons.

The gas flow path may comprise a lencrth of at least about 30 millimetres. The gas flow path may also comprise a height of between about 0.1 millimetres and about 1.0 millimetre.

In one implementation, no effects of plasma can be observed in the transfer chamber 13 when the lenoth of the gas flow path is about 30 millimetres and the height of the gas flow path is about 1.0 millimetre.

In a further embodiment, the gas flow path can provide one more than one change of direction. This allows plasma within the gas flow path to travel over a longer distance for provid-ing greater combination of free electrons with atoms.

In aspect of the invention, the first vacuum processing oham- ber includes a plasma source while the second vacuum pro-cessing chamber includes a transfer chamber. The transfer chamber holds substrate for moving to the first vacuum pro-cessing chamber.

A transport means, such as a magnetic manipulator, can be prc- vided between the first vacuum processing chamber and the se-cond processing chamber to move substrates between the first vacuum processing chamber and the second processing chamber.

The vacuum processing apparatus often includes a load lock chamber, which allows transfers of substrate into the vacuum processing apparatus. The load look chamber also provides a vacuum essentially inside the load lock chamber for allowing transfer of the substrate in the load lock chamber to a trans-fer chamber or to a processing chamber. The transfer chamber and the processing chamber also have a vacuum.

The appiicaticn also provides a magnetic feed-thrcugh manipu- lator for adjusting a position of a substance in a vacuum pro-cessing chamber.

The magnetic feed-through manipulator includes a movable shaft, a shaft magnet, and a magnetic drive device. The movable shaft and the shaft magnet are provided in the chamber while the magnetic drive device is provided outside the chamber.

The movable shaft adjusts the position of the substance by pushing or pulling the substance.

The shaft magnet is connected to the movable shaft.

The magnetic drive device includes a movable drive magnet, a movable magnetic flux return element, and an adjustment device.

The magnetic flux return element is also called a magnetic flux return ycke or bar.

In particular, the drive magnet is magnetically coupled to the shaft magnet. The movable drive magnet is separated from the movable magnetic flux return element by a pre-determined dis- tance. The adjustment device is provided for altering the dis- tance between the movable drive magnet and the movable magnet-ic flux return element.

The altering cf the distance between the movable drive magnet and the movable magnetic flux return bar acts to change the strength of the magnetic coupling between the shaft magnet and the drive magnet. A magnetic field of the shaft magnet inter- acts with a magnetic field of the drive magnet to form a mag- netic coupling. In comparison, the magnetic flux return ele- ment attracts nearby magnetic flux to pass through the magnet-ic flux return bar. The altering of the distance would alter the magnetic flux attracted by the flux return element, which in turn alters the strength of the magnetic coupling between the shaft magnet and the drive magnet.

This adjustment of the magnetic coupling is especially im-portant to avoid an overly strong macnetic coupling, which can generate jerky movemenos of the movable shaft.

In a general sense, the magnet can comprise a permanent magnet or an electro-magnet. The permanent magnet generates a magnet- ic field with an external energy source while the electro-magnet generates a magnetic field when it is energised by an electrical energy source.

The adjustment device can comprise an adjustment screw for moving or altering the position of the movable magnetic flux return bar with respecu to the movable drive magnet. The screw provides a simple means of altering the distance between the movable magnetic flux return bar and the movable drive magnet.

The magnetic flux return bar often includes an adjustment per-manent magnet.

In a general sense, the magnetic coupling between the shaft magnet and the drive magnet can magnetically push or move the shaft magnet towards the movable drive magnet. This moving al-so moves the shaft such that one-end of the shaft contacts a substrate and moves the substrate to a desired position.

The said magnetic coupling can also magnetically repel the shaft magnet away from the movable drive magnet. This repel!-ling also causes shaft to move. One end of the shaft contacts a substrate and moves The substrate to *a desired position.

The magnetic feed-through manipulator often includes a non-magnetic tubular housing, wherein the movable shaft and the shaft magnet are provided in the housing while the magnetic drive device is provided outside the housing. The non-magnetic tubular housing allows the shaft to move linearly while also allowing the magnetic field of the shaft magnet to interact

with the magnetic field of the drive device.

The application provides a vacuum processing apparatus.

The processing apparatus includes a vacuum processing chamber with a substrate transfer opening, a load look door, a sealing device, and one or more magnetic drive devices. The sealing device is provided between the load lock door and the vacuum processing chamber with the substrate transfer opening.

Referring to the magneric drive device, it includes at least one door magnet and a drive mechanism with at least one mova-ble drive magnet. The drive magnet is attached to the drive mechanism while the door magnet is attached to the load lock door.

In use, the drive mechanism positions the door magnet while a magnetic field of the door magnet interacts with a magnetic

field of the drive magnet.

The substrate transfer opening provides a passageway for mov-ing substrates into the vacuum processing apparatus and also moving the substrates out of the vacuum processing apparatus.

The load look door covers the substrate transfer opening of the vacuum prccessing chamber when the load lock door is in its closed position and the sealing device act to seal a gap between the substrate oransfer cpening and the load lock dcor against air outside the vacuum processing chamber.

The vacuum prccessing apparatus provides a sealing state in which the drive mechanism positions the door magnet, wherein the movable drive magnet magnetically repels and pushes the door magnet together with the load lock door towards the vacu-um processing chamber. In particular, the magnetic field of the door magnet repels or pushes away the magnetic field of the drive magnet. The sealing device then covers and seals the gap between the substrate transfer opening and the load lock door.

This magnetic pushing advantageously reduces the gap between the load lock chamber and the vacuum processing chamber. This reduced gap allows the sealing device to seal easily the re-duced gap against air outside the vacuum processing chamber.

The vacuum processing chamber may include a plasma source for generating plasma to treat a substrate placed in the vacuum processing chamber.

The direction of the pushing of the door magnet by the drive magnet is arranged essentially lateral to the direction of movement of the load lock door. This arrangement often produc-es the most effective sealing of the vacuum processing chamber.

The vacuum processing apparatus can provide an operating state in which the movable drive magnet is magnetically attracting the door magnet. The magnetic attracting allows the drive mag-net to move the load lock door to its closed position to its opened position. The drive meohanism positions the drive mag-net, which in turn positions the door magnet together with the load lock door by the said attracting.

In general, the vacuum processing apparatus can also provide an operating state in which the movable drive magnet is mag-netioally repelling the door magnet. The magnetic repelling allows the drive magner to move the load lock door to its closed position to its opened position. The drive mechanism positions the drive magnet, which in turn positions the door magnet together with the load lock door by the said repelling.

The vacuum processing apparatus can also include a load lock chamber for treating substrates.

The application provides a further vacuum processing apparatus.

The vacuum processing apparatus includes a load look chamber, a vaouum processing chamber, a load look door, and a magnetic door position lock.

The load lock door seals the processing chamfer from air and its pressure that is outside the vacuum processing chamber.

The magnetic door posirion lock includes a door lock magnet and a chamber lock magnet. The door lock magnet is attached to the load lock door while ths chamber lock magnet is attached to a fixed part of the vacuum processing apparatus.

In use, the door lock magnet and the chamber lock magnet are arranged such that the door lock magnet exerts a magnetic force that pushes away the chamber lock magnet to prevent opening of the load lock door when the load lock door is in a closed position. The arrangement also prevents closing of the load lock door when the load lock door is in an open position.

This arrangement advannageously provides a simple means to keep the load lock door magnetically in its closed position cr its open position.

The vacuum processing chamber may include a plasma source for treating substrates.

Fig. 1 Illustrates a top view of a plasma lead frame clean-ing apparatus, Fig. 2 illustrates a side view of the lead frame cleaning apparatus of Fig. 1, Fig. 3 illustrates a side view of a magnetic device for controlling a shaft of a magnetic feed-through ma-nipulator of the lead frame cleaning apparatus of Fig. 1, Fig. 4 illustrates a front view of a load lock door of the lead frame cleaning apparatus of Fig. 1, Fig. 5 illustrates a side view of the load lock door of Fig. Fig. 6 Illustrates a front sectional view of the load lock door of Fig. 5, Fig. 7 illustrates another front sectional view of the load lock door of Fig. 5, Fig. 8 Illustrates a side view of a labyrinth seal valve for the lead frame cleaning apparatus of Fig. 1, Fig. 9 illustrates a front sectional view of the labyrinth seal valve of Fig. 8, Fig. 10 illustrates a schematic view of the load lock door of Fig. 4, wherein the load lock door is in an oper-ating position, and Fig. 11 illustrates a schematic view of the load lock door of Fig. 4, wherein the load lock door is in a seal-ing position, Fig. 12 illustrates a side view of the load lock door of Fig. 4 for showing repelling of the load lock door for sealing, Fig. 13 Illustrates a side view of a gap seal valve for the lead frame cleaning apparatus of Fig. 1, and Fig. 14 Illustrates a front sectional view of the gap seal valve of Fig. 13.

In the following description, details are provided to de-scribe embodiments of The application. It shall be apparent to one skilled in the art, however, that the embodiments may be practiced without such details.

Scme parts of the embodiments, which are shown in the Figs. have similar parts. The similar parts have same names or simi-lar part numbers with a prime symbol or with an alphabetic symbol. The description of such similar parts also applies by referenoe to other similar parts, where appropriate, thereby reducing repetition of text without limiting the disclosure.

Fig. 1 shows a plasma lead frame cleaning apparatus 10. The cleaning apparatus 10 has a load lock chamber 12, a transfer chamber 13, and a processing chamber 14. One side of the transfer chamber 13 is positioned next to the load lock cham- bar 12 while another side of the transfer chamber 13 is posi-tioned next to the processing chamber 14.

The load lock chamber 12 includes a lead frame carrier opening 16 with a swing door 17, wherein the swing door 17 is attached to an external surface of the lead frame carrier opening 16 by hinges 19. The load lock chamber 12 is also connected to a vaouum pressure pump 21.

A lead frame carrier drive mechanism 24 extends from the in-side of the load lock chamber 12 to the inside of the transfer chamber 13. The carrier drive mechanism 24 includes a pair of rails 25 and a carrier platform 26 that is supported by the rails 25. The rails 25 extend from the inside of the load lock chamber 12 to the inside cf the transfer chamber 13.

A sliding load lock door 28 with a door enclosure 29 is placed between the transfer chamber 13 and the load lock chamber 12.

The transfer chamber 13 has a lead frame carrier transfer opening 31, which is placed next to the sliding load lock docr 28. A doorstop 30 is also provided along a sliding path of the load lock door 28.

As seen in Fig. 4, the load lock door 28 has a magnetic roller mechanism 32 and a magnetic position lock 33.

The magnetic roller mechanism 32 includes a plurality of mag-netic door bars 35 and a plurality cf magnetic roller bars 36.

Each of the magnetic door bars 35 and the magnetic roller bars 36 comprises a permanent magnet. The permanent magnet has north magnetic pole and a south magnetic pole, which generate a magnetic field. The permanent magnet generates the magnetic field without use of an electrical energy source. The north magnetic pole would point to the geographical North pole when the permanent magnet is supported on a pivot such that the permanent magnet is free to move in the horizontal plane.

Likewise, the south magnetic pole would point to the geograph-ical South pole when the permanent magnet is supported on the pivot.

The magnetic door bars 35 are placed above the magnetic roller bars 36 and the magnetic door bars 35 are separated from the magnetic roller bars 36 by a height h. The magnetic door bars are attached to a bottom part of the load lock door 28. The magnetic roller bars 36 are attached to a horizontal floor that is positioned below bottom part of the load look door 28.

The horizontal floor is positioned outside the load lock cham-ber 12 and the transfer chamber 13 and also below the load lock chamber 12 and the transfer chamber 13.

The magnetic door bars 35 are essentially oriented vertically, wherein the magnetic north poles of the magnetic door bars 35 are placed in bottom parts of the magnetic door bars 35. Simi-larly, the magnetic roller bars 36 are essentially oriented vertically, wherein the magnetic south poles of the magnetic roller bars 36 are placed in top parts of the magnetic roller bars 36.

Referring to the magnetic door position lock 33, it includes door position magnet 38 and a ohamber magnet 39. The door po-sition magnet 38 is attached to an upper part of the load lock door 28 while the chamber magnet 39 is attached to a fixed in-ner part of the transfer chamber 13 or to a fixed inner part of the load lock chamber 12, which is near to the door posit ion magnet 38.

As seen in Figs. 5, 6, and 7, the load look door 28 also in- cludes a magnetic drive mechanism 41, a slide 42, and a her-metio seal 44.

The load look door 28 includes a first major surface 47 and a second major surface 48, which is facing the first major sur-face 47.

The first major surface 47 is adjacent to the transfer chamber 13. The first major surface 47 is abuts the hermetic seal 44 and covers the lead frame carrier transfer opening 31 when the load lock door 28 is in a closed position. The second major surface 48 is adjacent to the load lock chamber 12 and is at-tached to the slide 42, which is also attached to an inner surface of slide door enclosure 29.

In one implementation, the hermetic seal 44 includes a fluid magnetic seal.

The door driving mechanism 41 includes a plurality of door magnets 50 and a driving device 51 with a plurality of drive magnets 52. The drive magnets 52 are attached to the driving device 51. The door magnets 50 are shown in Fig. 6 while the driving device 51 and the drive magnets 52 are shown in Fig. 6.

The door magnets 50 are attached to an upper part of the slid-ing load lock door 28 and they are arranged in a horizontal row with opposing poles of the door magnets 50 facing each other, as seen in Fig. 7. The driving device 51 and the drive magnets 52 are located outside the door enclosure 29, as seen in Fig. 5. The drive magnets 52 are also arranged in a hori-zontal row with opposing poles of the door magnets facing each other, as seen in Fig. 6.

As seen in Fig. 2, the transfer chamber 13 includes a lead frame carrier elevator 55 and a plurality of first magnetic feed-through manipulator 56. The lead frame carrier elevator 55 includes a horizontal platform 58 and a vertical extendable shaft 60. A top end of the extendable shaft 60 is attached to the platform 58 while a bottom end of the extendable shaft 60 is connected to a floor 62 of the transfer chamber 13. The first magnetic feed-through manipulators 56 are placed at one side of the transfer chamber 13. The transfer chamber 13 is also connected to a second vacuum pressure pump 64, as seen in Figs. 1 and 2.

As better seen in Fig. 2, a separatirg wall 66 with a lead frame opening 68 is placed between the transfer chamber 13 and the processing chamber 14. The separating wall 66 has an upper portion 70 and a lower portion 71. A bottom surface of the up- per portion 71 and a top surface of the lower portion 71 de-fine the lead frame opening 68.

Similarly, the processing chamber 14 includes a plasma source 73, a lead frame elevacor 75, and a plurality of second mag-netic feed-through manipulator 77. The lead frame elevator 75 has a horizontal platform 79 and a vertical extendable shaft 80. A top end of the extendable shaft 80 is attaohed to the platform 79 while a boctom end of the extendable shaft 80 is connected to a floor 82 of the processing chamber 14. The se-cond magnetic feed-through manipulators 77 are placed at one side of the processing chamber 14. The said side of the pro-cessing chamber 14 is opposite to the said side of the load lock chamber 13. The plasma source 73 is attached to a top part of the processing chamber 14.

The first and the second magnetic feed-through manipulators 56 and 77 have similar constructions. As shown in Figs. 2 and 3, each of the first and rhe second magnetic feed-through manipu- lators 56 and 77 has a nonmagnetic tubular housing 85, a lon-gitudinally movable push shaft 87 with a shaft magnet 88, and a linear drive mechanism 90 with a set of manipulator control magnets 92.

One end of the tubular housing 85 is enclosed or sealed while an opposite end of the tubular housing 85 is attached to a wall of the transfer chamber 13 or to a wall the processing chamber 14.

One end of the shaft 87 is inserted in the tubular housing 85 and is attached to the shaft magnet 88 while another end part of the shaft 87 can be placed inside the transfer chamber 13 or inside in the processing chamber 14. The shaft magnet 88 comprises a magnetic north pole and a magnetic south pole, wherein the magnetic north pcle is placed in a tcp part of the shaft magnet 88 and the magnetic scuth pole that is placed in a bottom part of the shaft magnet 88.

As better seen in Fig. 3, the manipulator control magnets 92 comprise a main control magnet 94 and an adjustment magnet 95 with adjustment screws 96, wherein the main control magnet 94 and the adjustment magnet 95 are placed next to each other.

The ad-ustment magnet 95 is connected to the adjustment screws 96. The main control magnet 94 and the adjustment magnet 95 are also separated by a distance d, which can be adjusted or changed. The main control magnet 94 comprises a magnetic north pcle that is placed in a top part of the main control magnet 94 and a magnetic south pole that is placed in a bottom part of the main ccntrol magnet 94. Likewise, the adjustment magnet also comprises a magnetic north pole that is placed in a bottom part of the adjustment magnet 95 and a magnetic south pole that is placed in a top part of the adjustment magnet 95.

Referring to Fig. 2, the processing chamber 14 also includes a labyrinth seal valve 100. As seen in Fig. 9, the seal valve 100 includes a saw tooch protrusion 102 and a corresponding saw tooth groove 104. The saw tooth protrusion 102 is part of an outer part of the platform 70 of the lead frame elevator 75 while the saw tooth groove 104 is part of a bottom surface of the upper portion 70 of the separating wall 66.

The seal valve 100 is labyrinthine in the sense that the seal valve 100 has a small gas path that has one or more turns.

In a general sense, the magnetic door bars 35 and the magnetic roller bars 36 can also include electromagnets with north mag-netic poles and south magnetic poles, instead of the permanent magnet. The horizontal floor oan also be located inside the load lock chamber 12 or inside the transfer chamber 13.

In a general sense, the second vacuum pressure pump 64 can al-so be connected to the processing chamber 14, instead of being connected to the transfer chamber 13.

A flux return yoke or bar can also replace the adjustment mag-net 95. The flux return yoke attracts a nearby magnetic field to pass through the flux return yoke.

The slide 42 can be replaced by a set of rollers.

In use, the plasma lead frame cleaning apparatus 10 provides cleaning of semiconducoor lead frames 105, as illustrated in Figs. 1 and 2. The lead frames 105 provide mechanical support for semiconductor chips or dies. The lead frames 105 include die oaddles and lead fingers. The die paddles are intended for attaching to semiconductor chips while the lead fingers serve as pads for attachment of electrical wires from the pads to external terminals.

The lead frame carrier opening 16 allows a use: to load lead frame carriers 110 inside the load lock chamber 12, shown in Fig. 2. The loading refers to placing the lead frame carriers inside the load lock chamber 12. In particular, the user plac-es the lead frame carrier onto the carrier platform 26 of the carrier drive mechanism 24. The lead frame carrier opening 16 also allows unloading of the lead frame carriers 110 from the load lock chamber 12. The unloading refars to removing the lead frame carriers from the load lock chamber 12.

In a general sense, the lead frame 105 can be replaced by a substrate, which can include a semiconductor wafer.

The swing door 17 essentially seals the load lock chamber 12 to prevent external air pressure from entering into the load lock chamber 12.

When activated, the vacuum pressure pump 21 removes air from the load lock chamber 12 to generate essentially a vacuum or a very low pressure inside the load lock chamber 12.

In practise, the vacuum has a pressure reading. Tn one imple-mentation, the vacuum has a pressure reading of 1/1000 bar. In a general sense, the vacuum can refer to a medium vacuum with a pressure reading of between about 3 kPa (kilo-Pascal) to about 100 rnPa and to a high vacuum with a pressure reading of between about 100 mPa and 100 nPa.

The load lock door 28 has an open position, a closed position, and a sealing position. Tn the open position, the load lock door 28 does not cover the lead frame carrier transfer opening.

In the closed position, the load lock door 28 covers the lead frame carrier transfer opening 31. In the sealing position, the load lock door 28 covers the lead frame carrier transfer opening 31 and seals the gap between the lead frame carrier transfer opening 31 and the load lock door 28.

To place the load look door 28 in the door open position, the load lock door 28 slides in a horizontal open direction 0 into the door enclosure 29 no unblock the lead frame carrier trans-fer opening 31. The door open direction 0, which is shown in Fig. 1, is in the longitudinal direction of the door enclosure 29.

In an operating state, the activated drive device 51 can move the drive magnets 52 together with the load lock door 28, in the door open direction C to its open position. The drive raacj-nets 52 magnetically engage with or magnetically attract the door magnets 50. As shown in Fig. 10, the magnetic south poles of the drive magnet 52 are placed near to the magnetic north poles of the door magnets 50 to pull or to attract the door magnets 50 to the drive magnets 52. The magnetic north poles of the drive magnet 52 also placed near to the magnetic south poles of the door magnets 50 to pull or to attract the door magnets 50 to the drive magnets 52. The drive device 51 then moves the drive magnets 52 in the open direotion 0, which in turn magnetically pull the door magnets 50 together with the sliding load lock door 28 in the same open direction 0. The drive device 51 later places the door 28 in its open position.

This attracting of the drive magnets 52 to the door magnets 50 also pulls the load lock door 28 against the slide 42 in the lateral direction of load lock door 28, wherein the slide 42 supports the load lock door 28. This pulling allows the slid-ing load lock door 28 no move easily via the slide 42 in the door open direction 0 no its open position.

In short, the drive magnets 52 can magnetically pull the load look door 28 both in the longitudinal direction and in the lateral direction of the load lock door 28.

The magnetic roller mechanism 32 allows easy movement of the load lock door 28 in the door open direction 0. The magnetic door bars 35 and the magnetic roller bars 36 generate magnetic fields, which repel each other such that the load, lock door 28 is lifted and is supported by these magnetic fields. This al- lows the load lock door 28 to be moved easily in the open di-rection 0.

When the load look door 28 is in its open position, the mag-netio door position look 33 aots to keep the load look door 28 in its open position. The door position magnet 38 magnetioally repels or pushes against the chamber magnet 39 via the inter-action of their magnetic fields. The magnetic south pole of the door position magnet 38 is placed near to the magnetio south pole of the chamber magnet 39. The magnetic field of the door position magnet 38 interacts with the magnetic field of the chamber magnet 39 no cause the door position magnet 38 and the chamber magnet 39 no repel each other. This repelling, in effect, then exerts a magnetic force onto the load look door 28 to keep the load lock door 28 in its open position.

The carrier platform 26 of the lead frame carrier drive mecha-nism 24 transports the lead frame carrier 110 from the load lock chamber 12 to the transfer chamber 13 via the rails 25.

To place the load lock door 28 in the door closed position, the load lock door slides out of the door enclosure 29 in a horizontal closed direction 0 to cover the lead frame carrier transfer opening 31. The door closed direction C is in the longitudinal direction of the load lock door 28. The door closed direction C is shown in Fig. 1.

In the operating state, the activated drive device 51 can also move the drive magnets 52, together with the load lock door 28, in the horizontal closed direction C to the closed position of the load lock door 28.

The drive magnets 52 magnetically attract the door magnets 50.

The manner in which the drive magnets 52 and the door magnets attract each other is similar to the manner in which the attraction that is described above for moving the load lock door 28 to its open position.

The drive device 51 afterward moves the drive magnets 52 in the closed direction C. This moving, in turn, magnetically pulls the door magnets 50, together with the sliding load look door 28, in the door closed direction C to place the load lock door 28 in its closed position.

The doorstop 30 prevenos tha load lock door 28 from moving be-yond a pre-determined location in the door closed direction C. This attracting of the drive magnets 52 to the door magnets 50 also pulls the load lock door 28 in the lateral direction of the load lock door 28 against the slide 42, wherein the slide 42 enables easy moving of the sliding load lock door 28 in the door closed direction C to its closed position.

The magnetic roller mechanism 32 also enables the load lock door 28 to slide easily to its closed position.

hen the load lock door 28 is in the closed position, the docr position magnet 38 also repels the chamber magnet 39 to exert a magnetic force onto rhe load lock door 28 to keep the load lock door 28 in the closed position. The magnetic north pole of the door position magnet 38 is placed near to the magnetic north pole of the chamber magnet 39 while the magnetic field of the door position magnet 38 interacts with the magnetic field of the chamber magnet 39. This interaction causes the door position magnet 38 and the chamber magnet 39 to repel each other to keep the load lock door 28 in the closed posi-tion.

In the door sealing position, the hermetical seal 44 covers cr seals the gap between che load look door 28 covers and seals the lead frame carrier transfer opening 31. In other words, the load lock door 28 covers and seals the lead frame carrier transfer opening 31 via the hermetical seal 44 such that air in the load lock chamber 12 Is prevented essentially from en-taring the transfer chamber 13.

To place the load lock door 28 in the sealing position, the load lock door 28 is initially placed in its closed position, where the load lock door 28 Is blocked by the doorstop 30. The activated drive device 51 then moves the drive magnets 52 fur-ther in the dcor closed direction C to the sealing position, wherein the drive magnets 52 repels the door position magnets 38, as illustrated in Fig. 11.

The magnetic north poles of the drive magnet 52 is placed near to the magnetic north poles of the door magnets 50 to repel magnetically the door magnets 50 from the drive magnets 52.

The repelling also pushes the load lock door 28 essentially in the lateral direction cowards the lead frame carrier transfer opening 31. This pushing reduces the gap between the load lock door 28 and the lead frame carrier transfer opening 31. The reduced gap enables the hermetic seal 44 to cover this gap easily, as shcwn in Fig. 12. In one implementation, the direc-tion of the repelling has an angle of about between 85 degrees and 95 degrees to the longitudinal direction of the load lock 28.

The pushing is especially important when the said gap is large such that the seal 44 may not fully cover the gap and thus al-low air in the load lock chamber 12 to enter the transfer chamber 13 The second vacuum pressure pump 64 serves to generate essen-tially a vacuum cr low pressure in the transfer chamber 13 as well as the prccessing chamber 14. The vacuum pressure pump 64 has a fine control, which allows the vacuum pressure pump 64 to achieve a vacuum wiTh greater accuracy than the vacuum pressure pump 21.

The low pressure in the processing chamber 14 allows free movement of plasma in che processing chamber 14 to reach and to treat the lead frames 105 placed in the processing chamber 14. In the other words, the absence of atoms or reduced number of atoms in the air allows plasma to reach and to treat the lead frames 105.

The lead frame carrier elevator 55 acts to lift or lower the platform 58 with its transferred lead frame carrier to a height that enables transfer of the lead frames 105 between the transfer chamber 13 and the processing chamber 14 via the lead frame opening 68.

The first magnetic feed-through manipulator 56 serves to push the lead frame 105 from the transfer chamber 13 tc the pro-cessing chamber 14 via the lead frame opening 68.

The labyrinth seal valve 100 has an open state, wherein the saw tooth protrusion 102 is separated from the corresponding saw tooth groove 104 by a distance that allows the lead frame to pass through the seal valve 1CC.

The labyrinth seal valve 100 also has a closed state, wherein the saw tooth protrusion 102 is placed essentially next to the corresponding saw tooth groove 104. The saw tooth protrusion 102 engages with the tooth groove 104. Due production toler-ances, the closed seal valve 100 often provides a gas path 115, which is placed between the saw tooth protrusion 102 and the oorrespondlng saw tooth groove 104. The gas path 115 is illus-trated in Figs. 3 and 9. Because of the saw tooth profile of the protrusion 102 and the groove 104, the gas path 115 has many changes cf direction or turns, which serve to lengthen the gas path 115.

The plasma source 73 generates plasma using radio waves for cleaning the lead frame 105. The plasma comprises ionized par-tioles and free electrons, wherein the free eleotrons are not bound to an atom. The particles refer to molecules or atoms.

The plasma oan interaco with the exposed surface of the lead frame 105 to remove a chin layer of the exposed surface for cleaning the lead frame 105.

In one implementation, the plasma source 73 includes a high frequency ultra-violet (UV) lamp that ionizes a low-density gas. In another implementation, the plasmas source 73 includes a device for producing a strong electric field to electrically breakdown a gas.

The exposed inside surface of the processing chamber 14 are selected such that the plasma would essentially not erode or damage its surface.

The generated plasma may seep through the gas path 115 towards the transfer chamber 13. The length of the gas path 115 allows the plasma contained in the gas path 115 to convert substan-tlaily to a non-ionized gas or gases. In this manner, the seeped plasma is deactivated or is neutralized.

In one implementation, when the iength of the gas path 115 is about 20 millimetres, effects of the plasma in the transfer chamber 13 are visible or detectable. When the length of the gas path 115 is about 30 millimetres, the plasma essentially does not affect the transfer chamber 13.

The gas path 115 of the seal valve 1CC prcvides a simple way of preventing the plasma from entering the transfer chamber 13, where the plasma can convert or erode the inner surface of the transfer chamber 13.

The lead frame elevator 75 serves to lift or lower the plat-fcrm 79 to a height that enables transfer of the lead frames between the transfer chamber 13 and the processing chamber 14 via the lead frame opening 68.

The second magnetic feed-through manipulator 77 acts to push the lead frame 105 from the processing chamber 14 to the transfer chamber 13 via the lead frame opening 68.

With reference to the magnetic feed-through manipulators 56 and 77, the linear drive mechanism 90 serves to move the main control magnet 94 togerher with the adjustment magnet 95 in the horizontal direction.

The main control magner 94 serves to attract the shaft magnet 88. The movement of the main control magnet 94 also causes the main control magnet 94 to pull magnetically the shaft magnet 88 together with the push shaft 87.

In particular, the main control magnet 94 generates a control magnetic field with inceract with a shaft magnetic field of the shaft magnet 88. This interactinc pulls the shaft magnet 88 towards the main control magnet 94.

The adjustment screws 96 act to change or move the position of the adjustment magnet 95. Turning of the adjustment screws 96 would move the adjustment magnet 95 with respect to the main control magnet 94.

The adjustment magnet 95 also generates an adjustment magnetic field, which also interacts with the control magnetic field of the main control magner 94. Changing the distance between the adjustment magnet 95 and the main oontrol magnet 94 would change the said interaction between the adjustment magnetic field and the control magnetic field, which in turn also change the interaction between the control magnetic field and the shaft magnetic field. When the distance between the ad-justment magnet 95 and the main control magnet 94 is reduced, the interaction between the adjustment magnetic field and the control magnetic field would be more intense, which in turn causes the interaction between the control magnetic field and

the shaft magnetic field to be less intense.

In this manner, changes the distance between the adjustment magnet 95 and the main control magnet 94 would changes the magnetic attraction berween control magnet 94 and the shaft magnet 88.

The adjustment magnet 95 is especially important since too strong attraction between the control magnet 94 and the shaft magnet 88 might cause The movement of the pushed lead frame to be jerky and unstable.

In a further embodimenu of the lead frame cleaning apparatus 10, the processing chamber 14 includes a gap seal valve 120, which replaces the above labyrinth seal valve 100. The gap seal valve 120 is shown in FIgs. 13 and 14.

Upper surfaces 122 of The platform 70 and bottom surfaces 124 of the upper portion 70 of the separating wall 66 forms the gap seal value 120. The upper surfaces 122 of the platform 70 have several flat portions while the bottom surfaces 124 ot the upper portion 70 have corresponding flat portions. As seen in Fig. 13, when viewed a direction fl of movement of the lead frames 105 between the transfer chamber 13 and the processing chamber 14, the profile of the upper surfaces 122 of the plat-form 70 has steps 128 chat corresponds to steps 126 of the profile of the bottom surfaces 124 of the upper portion 70.

In use, the gap seal valve 120 has an open state and a closed state.

In the open state, the upper surfaces 122 of the platform 70 is separated from the bottom surfaces 124 of the upper portion by a distance that allows the lead frame 105 to pass through the seal valve 120.

In the closed state, the upper surfaces 122 of the platform 7Q are placed next to the bottom surfaces 124 of the upper por- tion 70. Because of mechanical tolerances, a small gap is pro-vided between the upper surfaces 122 and the bottom surfaces 124. The gap provides a gas flow path 115 between the transfer chamber 13 and the processing chamber 14.

In one implementation, the gap has a height hi of between about 0.1 mm (millimetre) and about 1.0 mm and a length dl of at least about 30 mm. In a preferred embodiment, the gap has a height hi of between about 0.2 mm and about 0.5 mm. With these dimensions, no effects of plasma can be observed in the trans-fer chamber 13.

In general, when the height hi of the gap is larger, the length dl of the gap should be longer for plasma contained in the gas flow path 115 no be neutralised.

Although the above description contains much specificity, this should not be construed as limiting the scope of the embodi- ments but merely providing illustration of the foreseeable em-bodiments. The above snated advantages of the embodiments should not be construed especially as limiting the scope of the embodiments but merely to explain possible achievements if the described embodiments are put into practice. Thus, the scope of the embodimenns should be determined by the claims and their equivalents, rather than by the examples given.

Reference numbers plasma lead frame cleaning apparatus 12 load lock chamber 13 transfer chamber 14 processing chamber 16 lead frame carrier opening 17 swing door 19 hinge 21 vacuum pressure pump 24 lead frame carrier drive mechanism rail 26 carrier platform 28 sliding load lock door 29 door enclosure 30 doorstop 31 lead frame carrier transfer opening 32 magnetic roller mechanism 33 magnetic position lock magnetic door bar 36 magnetic roller bar 38 door position magnet 39 chamber magnet 41 magnetic drive mechanism 42 slide 44 hermetic seal 47 majcr surface 48 major surface door magnet 51 driving device 52 drive magnet lead frame carrier elevator 56 magnetic feed-through manipulator 58 platform shaft 62 floor 64 vacuum pressure pump 66 separating wall 68 lead frame opening 70 upper portion 71 lower portion 73 plasma source lead frame elevator 77 magnetic feed-through manipulator 79 platform shaft 82 floor tubular housing 87 shaft 88 shaft magnet linear drive mechanism 92 manipulator control magnet 94 main control magnet adjustment magnet 96 adjustment screw labyrinth seal valve 102 protrusion 104 groove lead frame 110 lead frame carrier gas path gap sea: valve 122 upper surface 124 bottom surface 128 step 126 step d distance d h height C closed direcrion 0 open direction ii direction hi height di length

Claims

Claims 1. A vacuum processing apparatus comprising a first vacuum processing chamber, a second vacuum processing chamber, and a seal valve providing a gas flow path between the first vacuum processing chamber and the second processing chamber, such thau the gas flow path essentially neutralises plasma con-tamed in the gas flow path.
2. The vacuum processing apparatus according to claim 1, wherein the gas flow path comprises a length of at least about 30 millimetres.
3. The vacuum processing apparatus according to claim I or 2, wherein the gas flow path comprises a height of between about 0.1 millimetre and about 1.0 millimetre.
4. The vacuum processing apparatus according to one of the above-mentioned claims, wherein the gas flow path provides at least one change of direc-tion.
5. The vacuum processing apparatus according to one of the above-mentioned claims, wherein the first vacuum processing chamber comprises a plasma source.
6. The vacuum processing apparatus according to one of the above-mentioned claims, wherein the second vacuum processing chamber comprises a transfer chamber.
7. The vacuum processing apparatus according to one of the above-mentioned claims further comprising a transport means between the first vacuum processing chamber and the second processing chamber.
8. The vacuum processing apparatus according to one of the above-mentioned claims further comprising a load lcck chamber,
9. A magnetic manipulator for adjusting a position of a sub-stance in a chamber, the magnetic manipulator comprising a mcvable shaft provided in the chamber for adjust-ing the position of the substance, a shaft magnet provided in the chamber, the shaft magnet being connected to the movable shaft, a magnetic drive device provided outside the chamber, the magnetic drive device comprising -a novable drive magnet, the drive magnet is magnetically coupled to the shaft magnet, -a movable magnetic flux return element, the movable drive magnet being separated from the movable magnetic flux return element by a pre-determined distance, and -an adjustment device for altering the distance between the movable drive magnet and the movable magnetic flux return element.
10. The magnetic manipulator according to claim 9, wherein the adjustment device comprises a screw for moving the position of the movable magnetic flux return bar.
11. The magnetic manipulator according to claim 9 or 10, wherein the magnetic flux return bar comprises an adjustment rnag-net.
12. The magnetic manipulator according to one of claims 9 to ii, wherein the magnetic coupling between the shaft magnet and the drive magnet magnetically pushes the shaft magnet towards the movable drive magnet.
13. The magnetic manipulator according to one of claims 9 tc 11, wherein the magnetic coupling between the shaft magnet and the drive magnet magnetically repels the shaft magnet away from the movable drive magnet.
14. The magnetic manipulator according to one of claims 9 to 13 further comprising a non-magnetic housing, wherein the movable shaft and the shaft magnet are provided in the housing, the magnetic drive device is provided out-side the housing.
15. A vacuum processing apparatus comprising a vacuum processing chamber, a icad lock door, a sealing device, the sealing device being provided between the load lock door and the vacuum processing chamber, at least one magnetic drive device, the magnetic drive device comprising -at least one door magnet being attached to the load lock door, and -a drive mechanism with at least cne movable drive magnet, the at least one drive magnet being attached to the drive mechanism, the vacuum processing apparatus provides a sealing state in which the movable drive magnet pushes the door magnet together with the load lcc:K door towards the vacuum processing chamber.
16. The vacuum processing apparatus according to claim 15, wherein the direction of nbc pushing of the door magnet is ar-ranged essentially lateral to the direction of movement of the load look door.
17. The vacuum processing apparatus according to claim 15 or 16, wherein the vacuum processing apparatus provides an operating state in which the movable drive magnet is magnetically attracting the door magnet.
18. The vacuum processing apparatus according to claim 15 or 16, wherein the vacuum processing apparatus provides an operating state in which the movable drive m.agnet is magnetically repelling the door magnet.
19. The vacuum processing apparatus according to one of claims 15 to 18 further comprising a load lock chamber.
20. A vacuum processing apparatus comprising a load look chamber, a vaouun processing chamber, a load look door, the load look door sealing the processing chamfer, a magnetic door position lock, the magnetic door po-sition look comprising a door look magnet and a chamber look magnet, the door look magnet being attaohed to the load look door, the ohamber look magnet being attached to the vaouum processing apparatus, wherein the door look magnet and the ohamber look magnet are ar-ranged suoh that The door look magnet exerts a magnetio foroe that pushes away the charter look magnet -to prevent opening of the load look door when the load lock door is in a closed position, and -to prevent olosing of the load lock door when the load lock door is in an open position.