Patent Application
20220403953
The present invention relates to a gas inlet valve for admitting a process gas into a vacuum process chamber.
Such vacuum process chambers are used for Integrated Circuit (IC), semiconductor, flat panel or substrate manufacturing, wherein the vacuum chambers are flooded with a process gas at least for part of the process steps after evacuation. The production must take place in a protected atmosphere and, if possible, without the presence of contaminating particles. The evacuation is carried out with a vacuum valve, which connects the vacuum process chamber to a vacuum pump and differs in its design and technical requirements from a gas inlet valve.
Furthermore, such vacuum chambers have at least one or two vacuum chamber openings through which the elements to be processed can be guided into and/or out of the vacuum chamber. For example, in a manufacturing plant for semiconductor wafers or liquid crystal substrates, the highly sensitive semiconductor or liquid crystal elements pass sequentially through several vacuum process chambers, in which the elements are processed by means of one processing device each.
The element can, for example, be placed by means of a robot on extended support pins of a lifting system and by lowering the support pins it can be placed on a carrier, e.g. a potential plate (chuck). The robot arm, which typically carries the element, is then moved out of the chamber. The pins can be lowered after the element has been deposited and are then separated from the element, i.e. there is no contact between the pins and the element. After removing the robot arm and closing the chamber, the chamber is usually evacuated and then filled with a process gas, whereupon the processing of the element can start.
Gas inlet valves are especially designed for defined control or regulation of the gas flow and are located, for example, within a pipe system between a vacuum process chamber (or a transfer chamber) and a gas source, the atmosphere or another vacuum process chamber. The opening cross section of such gas inlet valves is usually smaller than that of a vacuum valve.
Since gas inlet valves, depending on the field of application, are used not only to fully open and close an opening, but also to control or regulate a flow rate by continuously adjusting the opening cross-section between an open position and a gas-tight closed position, they are also called regulating valves.
When admitting the process gas into the chamber, low fluidic effects within the chamber as well as fast and precisely controllable filling are of great importance.
Therefore, it is an object of the invention to provide an improved gas inlet valve for a vacuum process chamber. In particular, the gas inlet valve according to the invention enables a faster and more precisely controllable flooding of an evacuated vacuum process chamber with a process gas.
The present invention relates to a gas inlet valve for the controlled inlet of a process gas into a vacuum process chamber, wherein the gas inlet valve comprises: a gas flow unit with a gas inlet, a gas outlet and an inner volume which has free access to the gas inlet and the gas outlet, wherein the gas flow unit has a sealing surface in the inner volume, an adjusting device with an adjusting unit, wherein the adjusting unit projects into the inner volume and is adjustably mounted outside the gas flow unit in the adjusting device, wherein the adjusting unit has a plate which is arranged inside the inner volume, wherein the plate can be brought into a closed position by means of the adjusting device, in which the plate rests on the sealing surface and thus prevents a gas flow, and wherein the plate can be brought by means of the adjusting device into an open position in which the plate is spaced from the sealing surface and thus allows a gas flow, a first flexible sealing element attached to the gas flow unit and to the adjusting unit and seals the adjusting unit against the inner volume, and a position determination unit arranged on or in the adjusting unit and is adapted to determine a position of a part of the displacement unit having a fixed local relation to the plate.
In one embodiment, the gas inlet valve may include a second flexible sealing element, wherein the first and second flexible sealing elements embody two flexible sealing elements attached to the gas flow unit and the adjusting unit, respectively, thereby sealing the inner volume.
Thus, the present invention also relates to a gas inlet valve for controlled inlet of a process gas into a vacuum process chamber, wherein the gas inlet valve comprises: a gas flow unit with a gas inlet, a gas outlet and an inner volume having free access to the gas inlet and the gas outlet, wherein the gas flow unit has a sealing surface in the inner volume, an adjusting device with an adjusting unit, wherein the adjusting unit projects into the inner volume and is adjustably mounted outside the gas flow unit in the adjusting device, wherein the adjusting unit has a plate arranged inside the inner volume, wherein the plate is movable into a closed position by means of the adjusting device, in which the plate rests on the sealing surface and thus prevents a gas flow, and wherein the plate can be brought by means of the adjusting device into an open position in which the plate is spaced from the sealing surface and thus allows a gas flow, two flexible sealing elements attached to the gas passage unit and to the adjusting unit, respectively, and sealing the inner volume therewith, and a position determination unit arranged on or in the adjusting unit and adapted to determine a position of a part of the adjusting unit having a fixed local relation to the plate.
According to one embodiment, the first and/or second flexible sealing element may be attached to the plate and the gas flow unit.
One of the sealing elements or both sealing elements are designed in one embodiment as a membrane, in particular as a metal membrane. In particular, at least one of the sealing elements as well as the side of the plate opposite the respective sealing element have a similarly large, in particular exactly the same pressure application surface, whereby at least essentially a pressure force cancellation is achieved, which makes a movement of the plate independent of the prevailing pressure. This allows the valve to be adjusted more quickly.
In the closed position, the plate is pressed against the sealing surface in particular by a pretension, wherein the pretension emanates at least partially from at least one of the sealing elements and/or at least partially from a pretensioning device arranged outside the inner volume. In particular, therefore, at least one of the sealing elements has a spring hardness and can counteract the force of the prevailing pressure by means of a pretension. If the pretension is at least partially emanating from the pretensioning device, the pretensioning device is enclosed by the adjusting device. In addition, the above-mentioned application surfaces and/or the spring stiffness(es) of the spring element(s) can be adapted to each other in such a way that a pretension bias is created, which has a beneficial effect on the reaction time of the valve (e.g. if only opening or only closing must be able to take place quickly).
The plate and/or the sealing surface may have a sealing ring which is compressed in the closed position. Compression is due to the pretension and ensures that the gas inlet is separated gas-tight from the gas outlet.
The two sealing elements can be pretensioned against each other, so that if the adjusting unit is adjusted, no or only a comparatively low resistance force is generated by the sealing elements.
The sealing surface, the plate and the sealing elements have in particular a circular cross-section, wherein the inner volume is cylindrical at least in sections, and wherein the sealing surface is formed by a shoulder in the inner volume.
The cylindrical shape of the inner volume is formed in particular by the gas flow unit as a jacket surface and the sealing elements as base surfaces, wherein the gas inlet and gas outlet gain free access to the inner volume via the jacket surface. This means that gas inlet and gas outlet each pierce the outer surface.
The adjusting device can be operated electrically or pneumatically.
In particular, the plate divides the inner volume in the closed position into a first and a second partial inner volume, wherein the gas inlet has free access to the first partial volume and the gas outlet has free access to the second partial volume.
The gas outlet has especially free access to a vacuum process chamber and the gas inlet has especially free access to a gas source.
Further advantages of the present invention are evident from the detailed description and drawings.
The adjusting device 3 comprises an adjusting unit 31 and a plate 32, wherein the adjusting unit 31 projects into the inner volume 23 and is adjustably mounted outside the gas flow unit 2 in the adjusting device 3, wherein the plate is arranged inside the inner volume 23 and is movable by means of the adjusting device 3 into a closed position in which the plate 32 rests on the sealing surface 24 and thus prevents a gas flow. By means of the adjusting device 3, the plate can furthermore be brought into an open position in which the plate 32 is spaced from the sealing surface 24 and thus allows gas to flow.
The gas inlet valve 1 also has two flexible sealing elements 41 and 42, which are designed as membranes in the example shown. The sealing elements are each attached to the gas flow unit 2 and to the adjusting unit 31, thus sealing the inner volume 23.
A position determination unit 5 is located at the adjusting device 3 and is set up to determine a position of the upper end of the adjusting unit 31. In the example shown, the adjusting unit 31 has several elements that are fixedly connected to each other so that the location of the measurement (upper end of the adjusting unit 31) has a fixed local relation to the plate. Thus, the position of the plate can be determined at any time and without interruption. In other words, the plate 32 is fixedly connected to the adjusting unit 31, whereby the determination of a position of the adjusting unit 31 simultaneously corresponds to a position determination for the plate 32. By determining a plate position, in particular continuously or continuously, an active control (and/or regulation) of the valve and thus of the gas flow can be carried out. Advantageously, the downstream (after the gas outlet) determination of an actual gas flow (as controlled variable) depending on a current valve control can be omitted.
Connections 81 and 82 are provided in each case for gas inlet 21 and gas outlet 22. The line to the gas source and the line to the vacuum process chamber can be connected via these connections.
The sealing ring can be embedded in the plate 32 (as shown here) or (in other embodiments) in the sealing surface 24.
In addition, the sealing elements 41 and 42 can be braced against each other so that no force that is applied to the adjusting unit 31 is produced. However, this minimizes any force acting against the adjustment direction during the process of spacing the plate 32 from the sealing surface 24, i.e. when the valve is opened. This is due to the fact that one of the sealing elements approaches its initial position when the valve is opened, and the other one continues to (still) tension through the adjustment path. This reduction on the one hand and increase on the other ideally cancel each other out, but at least minimize the resulting resistance during adjustment. Consequently, (essentially) only the pretension caused by the pretensioning device (springs 91 and 92) has to be overcome when the valve is opened or closed. In particular, the sealing elements are metal membranes.
The seats of the flexible sealing elements 41 and 42 on the adjusting unit 31 can also be carried out by way of clamping, as shown in
Shown are inner volume 23, plate 32, sealing surface 24, shaft 311, sleeve 313, sealing elements 41 and 42, sealing ring 33 each with circular cross-section. In particular, the inner volume 23 is shown as a hollow cylinder. This is not necessarily the case as these components can also be elliptical, rectangular or manufactured in any profile. The sealing surface 24 is also shown here as a shoulder in the first partial volume 231, which has free access to the gas inlet 21, wherein this results in a smaller cross-section in the first partial volume. In other embodiments, the shoulder of the sealing surface 24 goes back again to the average which is also shown in the second partial volume 232, which has free access to gas outlet 22. The jacket surfaces can also have a different shape and do not have to be oriented to a hollow cylinder.
The first partial volume 231 is formed in a ring between the jacket surface of the inner volume 23 and a jacket surface of the upper axial part of the plate 32, and is limited in the axial direction by the sealing element 41 and the front plate surface. The second partial volume 232 is formed annularly between the jacket surface of the inner volume 23 and a jacket surface of the lower axial part of the plate 32, and is limited in the axial direction by the sealing element 42 and the rear plate surface.
The control unit 7 is especially designed to adjust the plate 32 in a defined way. The closed position (plate 32 is pressed against sealing surface 24) can be achieved either purely passively, i.e. by means of a possible pretension (pretensioning device and/or sealing elements), or by a corresponding active adjustment of the adjusting device 3, controlled by the control unit 7. An open position of the plate 32 means that the plate 32 is lifted from the sealing surface 24. The extent to which the plate 32 is lifted can be defined in this case by the adjusting device 3, which is correspondingly controlled by the control unit 7. In addition to defined target values (closed position, open position by a certain distance), the control unit 7 can also be set up to travel defined traverse paths of the plate 32. This means that in order to achieve a leisurely opening process that avoids turbulence, the plate 32 could be lifted from the sealing surface 24 at a very low starting speed and then, after a certain distance, achieve a faster lift-off speed. In other embodiments, the valve can be opened in a defined “pulsed” manner so that the process gas can be fed into the process chamber in chunks.
For the control of the adjusting unit 31 by the control unit 7, in particular the position determination unit 5 is continuously read out and used as feedback.
With such specific controls, it is also always taken into account that a relatively high pressure prevails at the gas inlet 21 of the gas flow unit 2 (due to the connected gas line or gas cylinder) and that a pressure of between 0 bar and the overpressure of the gas source can prevail at the gas outlet 22.
An advantage of the gas inlet valve according to the invention is that a gas supply can basically accumulate in the first partial volume, to which the gas inlet 21 has free access. When the gas inlet valve 1 is opened, this gas supply can be passed on to the second partial volume 232 in a fluidically favorable and abrupt manner. Measured against these fluidic advantages, the gas inlet valve according to the invention also has a very small size.
A further advantage lies in the flexible sealing elements, which are shown here as membrane 41 and 42. The pressure changes that occur when opening and closing the gas inlet valve 1 can be damped by these sealing elements, which increases the durability of the entire system.
Due to the fixed and in particular rigid connection of the plate 132 with the rod 131, the position of the plate 132 can be determined directly by means of the position determination unit 105, which can determine a linear position of the rod 131 (as part of the adjusting unit). The position determination unit 105 thus enables a determination of whether the valve is closed or open, as well as a determination of how large a possible distance between the sealing surface 124 and the valve plate 132 or sealing element 133 is, i.e. how large an existing opening cross-section is and thus how large a possible volume flow through the valve 100 currently is.
The membrane 141, which is designed as a flexible sealing element, provides a flexible seal of the inner volume with respect to the adjusting unit 103. For this purpose, the membrane 141 is connected on the one hand to the gas flow unit 102 and on the other hand to the adjusting unit, in this case to the plate 132 or to the rod 131.
The figures always show a plate 32 or 132, which has an upper and lower axial part (hollow shaft sections). In other embodiments, the plate 32 or 132 can be only a disc, wherein the upper and lower parts of the plate 32 or 132 can be replaced by simple hollow shafts, which are sealed axially to the disc. Furthermore, the figures always show a plate 32 or 132 which is opened in the direction of gas flow, i.e. which is adjusted from top to bottom according to the figures. In other exemplary embodiments, however, the components involved can also be designed and arranged in such a way that the plate is pressed onto the sealing surface from above for the closed position, and is moved upwards for an open position.
Although the invention has been explained on the basis of its preferred embodiment(s), many other changes and variations can be made without going beyond the scope of the present invention. Therefore, it is provided that the enclosed claims cover changes and variations which are contained in the actual scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 008 017.3 | Nov 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/082566 | 11/18/2020 | WO |
