DE102024001225A1 - GAS INLET VALVE WITH IMPROVED FLOW GEOMETRY - Google Patents

Abstract

The invention relates to a gas inlet valve (1) for the controlled inlet of a fluid into a vacuum process chamber, wherein the gas inlet valve (1) comprises: a gas application unit (2) with a gas inlet (21), a gas outlet (22) and an internal volume (23) connecting the gas inlet (21) and the gas outlet (22), wherein the gas application unit has a valve seat body (24) with a sealing surface (24a) in the internal volume (23); an adjusting unit (4) projecting into the inner volume (23) with a valve plate (45) which is arranged within the inner volume (23) and has a seal (46), wherein the adjusting unit (4) is mounted so as to be movable along an adjusting axis (V) in the closing direction (S) and in the opening direction (O), and the valve plate (45) and the valve seat body (24) are designed to correspond to one another in such a way that the seal (26) touches the sealing surface (24a) in a closed position; a drive unit (3) coupled to the adjustment unit (4) outside the gas application unit (2) and providing adjustment of the adjustment unit (4) along the adjustment axis (V), wherein the valve plate (45) can be brought into an open position in the opening direction (O) by means of the drive unit (3), in which open position the seal (46) is spaced from the sealing surface (24a) and a fluid passage is provided; and a flexible sealing element (25) designed as a membrane, which is connected to the gas application unit (2) and to the adjustment unit and atmospherically separates the drive unit (3) from the internal volume (23). The valve seat body (24) is formed in a ring shape around the adjustment axis (V) and has an annular end face (26) facing the valve plate (45). The annular end face (26) has an inner partial surface (27) and an outer partial surface (28), wherein a distance of the inner partial surface (27) from the adjustment axis (V) is smaller than a distance of the outer partial surface (28) from the adjustment axis (V). The outer partial surface (28) has the sealing surface (24a).

Description

FIELD OF THE INVENTION

The present invention relates to a gas inlet valve for inlet of a fluid into a vacuum process chamber with an improved flow geometry.

BACKGROUND OF THE INVENTION

Vacuum process chambers are used for integrated circuit (IC), semiconductor, flat panel, or substrate production. After evacuation, the vacuum chambers are flooded with a process gas for at least some of the process steps. Production must take place in a protected atmosphere and, if possible, without the presence of contaminating particles. Evacuation is achieved using a vacuum valve that connects the vacuum process chamber to a vacuum pump. This valve differs fundamentally from a gas inlet valve in terms of its design, technical requirements, and purpose. While a generic gas inlet valve is designed for the defined application of a fluid into the vacuum process chamber (upstream), classic vacuum valves are intended for regulating the pressure conditions in the chamber (downstream) or for loading and unloading the chamber. Opening cross-sections, closing and opening times, and sealing requirements differ accordingly.

Furthermore, 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 facility for semiconductor wafers or liquid crystal substrates, the highly sensitive semiconductor or liquid crystal elements sequentially pass through several vacuum processing chambers, in each of which the elements are processed using a separate processing device.

The element can, for example, be placed by a robot on extended support pins of a lifting system and lowered onto a carrier, e.g., a potential plate (chuck). The robot arm, which typically carries the element, is then extended out of the chamber. The pins can be lowered after the element has been placed and are then separated from it, meaning there is no contact between the pins and the element. After the robot arm is removed and the chamber is closed, the chamber is usually evacuated and then filled with a process gas, after which processing of the element can begin.

A gas inlet valve is provided for filling the process chamber with one or more specific process gases or precursors. This allows for various substrate processing steps, such as the targeted deposition of a material layer on a wafer or etching of the wafer surface. Specifically, a specific amount of process fluid is released into the process chamber, and a reaction between the process fluid and the wafer is initiated or accelerated, for example, using a plasma.

Gas inlet valves are specifically designed for the defined control or regulation of gas flow and are located, for example, within a piping 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 typically significantly smaller than that of a vacuum valve.

Depending on the application, gas inlet valves can be used not only to completely open and close an opening, but also to control or regulate a flow by continuously adjusting the opening cross-section between an open position and a gas-tight closed position.

When admitting the process gas into the vacuum chamber, minimal flow effects within the chamber and rapid and precise filling of the chamber are of utmost importance. For example, a defined amount or volume of a defined process gas should be admitted into the chamber with one opening cycle of the gas inlet valve. To achieve this, rapid actuation of the valve and precise adjustment of the resulting valve opening cross-section are desirable.

Furthermore, the flow characteristics through the gas inlet valve are of key importance. The flow through the valve should be as homogeneous as possible to minimize or eliminate turbulence or eddies in the process chamber. Turbulence and eddies in the chamber can stir up deposited particles and thus lead to contamination in the process.

Classic gas inlet valves according to the state of the art already provide sufficient flow consistency, but the corresponding requirements are constantly increasing. Today's flow consistency is typically still acceptable, but should continue to increase for further improved and reliable processes.

OBJECT OF THE INVENTION

Therefore, it is an object of the invention to provide an improved gas inlet valve for a vacuum process to avoid the above-mentioned disadvantages.

In particular, the object is to provide a gas inlet valve for a processing system, which can provide a fast and continuously constant flooding of a vacuum process chamber with a process gas.

SUMMARY OF THE INVENTION

The present invention relates to a gas inlet valve with a seal set back from a gas connection, in particular the gas inlet. The seal is arranged such that it is not located in a flow-restricting region of the connection, but rather is located a certain distance away from the flow-restricting region. This prevents a detrimental influence of the seal on flow restriction. The seal is typically made of an elastic material. This elasticity and flexibility of the seal can have a correspondingly negative effect on flow consistency. In particular, a change in the flow characteristics can be caused by thermal expansion or shrinkage of the seal.

Accordingly, a sealing line, i.e. a line along which the seal interacts with the valve seat or with a sealing surface provided by the valve seat or rests on the valve seat body when the valve is closed, can be provided away from the flow-relevant area.

As a result of this arrangement of the sealing line, improved flow or flow consistency is provided through the gas application unit.

The invention accordingly relates to a gas inlet valve for the controlled inlet of a fluid into a vacuum process chamber, wherein the gas inlet valve comprises a gas application unit with a gas inlet, a gas outlet, and an internal volume connecting the gas inlet and the gas outlet. The gas application unit comprises a valve seat body with a sealing surface in the internal volume.

In the context of the present invention, a fluid is understood to mean at least one gas, a gas mixture, or a precursor-containing gas. The fluid can, in particular, be a process or precursor gas.

In addition, an adjustment unit with a valve disk is provided that extends into the interior volume. The valve disk is arranged within the interior volume and has a seal, i.e., a sealing material designed to create a gas-tight seal. The adjustment unit is mounted so that it can move along an adjustment axis in the closing and opening directions. The valve disk and the valve seat body are configured to correspond to one another in such a way that the seal contacts the sealing surface in a closed position. This allows the fluid flow through the gas application unit to be interrupted.

The gas inlet valve further comprises a drive unit coupled to the adjustment unit outside the gas application unit and providing adjustment or movement of the adjustment unit along the adjustment axis. The valve disk can be moved in the opening direction by means of the drive unit into an open position, in which the seal is spaced from the sealing surface and a fluid flow is provided.

The drive unit can have an electric motor or a pneumatic system for adjusting the adjustment element.

Furthermore, a flexible sealing element designed as a membrane is arranged, which is connected to the gas application unit and to the adjustment unit and atmospherically separates the drive unit from the internal volume.

The valve seat body is formed in a ring around the adjustment axis and has an annular end face facing the valve plate. The annular end face has an inner partial surface and an outer partial surface, with the distance of the inner partial surface from the adjustment axis being smaller than the distance of the outer partial surface from the adjustment axis. The outer partial surface has the sealing surface.

In one embodiment, the inner partial surface can be larger than the outer partial surface. This results in a correspondingly large distance between the sealing surface interacting with the seal and the adjustment axis and thus from the gas inlet. This can provide further improved flow consistency.

According to one embodiment, the inner partial surface and the outer partial surface can be formed in a ring shape, in particular around the adjustment axis.

In one embodiment, the valve seat body may have or surround a cylindrical recess forming the gas inlet or the gas outlet, wherein the recess has a cross-sectional area directed orthogonally to the adjustment axis.

In particular, a radius of the cross-sectional area can include a corner radius, wherein the corner radius is defined by a curved course of the surface between a lateral surface of the recess and the end face.

In particular, the end face can lie in a valve seat plane and a projection of the cross-sectional area onto the valve seat plane can define an inner boundary of the end face and a projection of the course of the seal onto the valve seat plane, in particular a projection of a sealing line, can define an outer boundary of the end face.

The front surface is particularly aligned orthogonally to the adjustment axis.

In one embodiment, an inner circumferential surface can be defined by the circumference of the inner boundary of the end face and the distance between the end face and a valve plate surface of the valve plate.

The seal runs particularly around the valve plate surface.

An outer surface can be defined accordingly by the circumference of the outer boundary of the end face and the distance between the end face and the seal, in particular the distance between the end face and the underside of the seal.

In one embodiment, the valve seat body and the valve disk can be shaped such that the outer surface is larger than the inner surface. In particular, the outer surface can be larger than the inner surface in the open position of the valve, i.e., when there is no contact between the sealing surface and the seal.

In the open position, there is a gap between the end face and the seal. This gap can be greater than 0.05 mm and less than 1.0 mm, and in particular less than 0.75 mm or 0.55 mm.

In one embodiment, the valve seat body and the valve disk can be shaped such that an area ratio of the outer surface to the inner surface is greater than 1:1 and less than 5:1.

In one embodiment, the seal can be connected to the valve plate and protrude from the valve plate with a sealing height h, in particular in the closing direction.

For the sealing height h the following applies in particular: 0.1 mm < h < 0.5 mm.

According to one embodiment, the distance d between the valve plate, in particular the valve plate surface, and the sealing surface of the valve seat body in the open position can be 0.2 mm < d < 1.2 mm. In particular, the distance d can be greater than 0.25 mm and less than 1.0 mm.

In particular, the valve disk divides the internal volume in the closed position into a first and a second partial internal volume, with the gas inlet having free access to the first partial volume and the gas outlet having free access to the second partial volume. In this arrangement, the gas outlet can be connected to a vacuum chamber, in particular having free access to the vacuum process chamber, and the gas inlet can, in particular, have free access to a process gas source.

The gas inlet valve according to the invention is described in more detail below using exemplary embodiments schematically illustrated in the drawings. Identical elements are identified by identical reference numerals in the figures. The described embodiments are generally not drawn to scale and are not to be understood as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 zeigt eine Ausführungsform eines erfindungsgemässen Gaseinlassventils in einer Schnittansicht; und
• 2 zeigt eine Darstellung des Ventilsitzkörpers des Gaseinlassventils gemäss 1.

Further advantages of the present invention will become apparent from the detailed description and the drawings.

• 1 shows an embodiment of a gas inlet valve according to the invention in a sectional view; and
• 2 shows a representation of the valve seat body of the gas inlet valve according to 1 .

DETAILED DESCRIPTION OF THE DRAWINGS

The 1 shows an embodiment of a gas inlet valve 1 according to the invention in a sectional view.

The gas inlet valve 1 has a gas application unit 2, which in turn has a gas inlet 21, two gas outlets 22 and an internal volume 23 wherein the inner volume 23 has free access to the gas inlet 21 and the gas outlets 22 or connects them. The gas application unit 2 has a sealing surface 24a in the inner volume 23. The sealing surface 24a here forms in particular the valve seat of the gas inlet valve 1 and is part of the valve seat body 24.

In an alternative embodiment not shown, the gas inlet valve 1 may have a single or a plurality of gas outlets.

The gas inlet valve 1 also has a drive unit 3. In the embodiment shown, the drive unit 3 is designed as a pneumatic drive. However, it is understood that in an alternative embodiment according to the invention, an electromechanical drive unit with an electric motor can be provided.

The gas inlet valve 1 is shown in an open position, i.e., a fluid flow through the internal volume 23, in particular from the gas inlet 21 to the gas outlets 22, is possible. The pneumatic drive unit 3 has a first reciprocating piston 31 and a second reciprocating piston 32, which can be moved in the opening direction O by means of a pressurization in a respective lifting cylinder and can thus move the valve 1 into the open position. The pressurization can be provided by means of respective compressed air channels or compressed air inlets 31a and 32a, here by means of a hollow screw with outlet bores.

Furthermore, a return element 33, e.g., a spring, is arranged such that the return element 33 causes a return force in the closing direction S. The return force is exerted directly on the first piston 31 and, upon contact between the two pistons, thus also acts on the second piston 32.

Due to the arrangement of the return element 33, the valve 1 is held in the closed position or moved into this position without active pressure being applied to the lifting cylinders.

The gas inlet valve 1 also has an adjustment unit 4. The adjustment unit 4 is designed such that it can be coupled to the drive unit 3 and is coupled, as shown.

For this purpose, the adjustment unit 4 is formed with a coupling section 41. This section 42 corresponds to a corresponding counterpart of the drive unit 3. For example, the second reciprocating piston 32 also has a coupling section at its lower end. The drive-side coupling section can, for example, have an external thread, and the coupling section 41 of the adjustment unit 4 can have an internal thread. By interacting, in particular screwing, the threads, a robust and precise coupling of the adjustment unit 4 to the drive 3 can be achieved. Alternatively, the coupling can also be achieved by means of a screw 42, as shown here, wherein a screw head interacts with the first reciprocating piston 31 and a screw thread interacts with the coupling section 41.

According to alternative embodiments, the coupling can be provided, for example, by a clamping or snap-on mechanism. The invention also extends to other connection variants known to those skilled in the art, such as a magnetic connection between the two components.

The drive unit 3 is thus coupled to the adjustment unit 4 outside the gas application unit 2 and is capable of providing adjustment of the adjustment unit 4 along the adjustment axis V. The adjustment unit 4 has a valve plate 45 at an opposite end. The valve plate 45 can thus be brought into an open position in the opening direction O by means of the drive unit 3, in which the valve plate 45 is spaced from the sealing surface 24a and thus a gas flow between the gas inlet 21 and the gas outlet 22 is provided through the internal volume 23.

The valve plate 45 has a seal 46 that contacts the valve seat body 24 when the valve 1 closes, thus ensuring a sealing interaction between the seal 46 and the sealing surface 24a, i.e., a closed valve state. Fluid flow through the gas application unit is then interrupted.

The adjustment unit 4 extends into the inner volume 23 and is adjustably mounted outside the gas application unit 2. The valve plate 45 is arranged within the inner volume 23 and is movable along an adjustment axis V in the closing direction S and in the opening direction O.

In the closed position, the valve plate 45 is pressed against the sealing surface 24a. The plate-side seal 46, e.g., a sealing ring, serves to ensure a gas-tight seal. The seal 46 can be arranged (as shown here) on the plate 45 or (in other embodiments) on the sealing surface 24a. This seal 46 consists in particular of an elastomer, thermoplastic, metal, etc., and can have a shape adapted to the shape of the plate 45 (e.g., an O-ring) or can be vulcanized to the plate 45.

The gas inlet valve 1 also has a flexible sealing element 25. This flexible sealing element 25 is designed as a membrane, in particular as a metal membrane.

The sealing element 25 is connected, on the one hand, to the gas application unit 2 and, on the other hand, to the adjustment unit 4, thus sealing the internal volume 23 from the drive unit 3. The flexible membrane 25 thus provides a flexible seal for the internal volume 23, in particular with respect to a drive unit 3, i.e., the seal remains tight even when the adjustment element 4 moves. The sealing element 25 can be connected, for example, to the gas application unit 2 by means of clamps and/or to the drive unit 3 by means of clamps.

The valve seat body 24 is formed annularly around the adjustment axis V and has an annular end face 26 facing the valve plate 45. The end face 26 extends, in particular, orthogonally to the adjustment axis V.

The end face 26, in turn, has an inner partial surface and an outer partial surface, wherein the distance of the inner partial surface from the adjustment axis V is smaller than the distance of the outer partial surface from the adjustment axis V, and wherein the outer partial surface has the sealing surface 24a. In other words, the seal 46 interacts with the outer partial surface when the valve is closed. The sealing line defined by this interaction is thus offset rearward from the direct flow area of the gas inlet 21.

2 shows a plan view of a valve seat body 24 of the gas inlet valve according to 1 The valve seat body 24 here surrounds a central recess forming the gas inlet 21. The recess has a cross-sectional area 21a oriented orthogonally to the adjustment axis V. Furthermore, the inner partial surface 27 and the outer partial surface 28 are shown.

The recess thereby defines the inner boundary of the end face 26. In other words, a projection of the cross-sectional area 21a onto the end face 26 defines an inner boundary of the end face 26. Furthermore, a projection of the profile of the seal onto the end face 26, in particular the projection of a sealing line, can define an outer boundary of the end face 26.

In the embodiment shown, an inner circumferential surface is defined by the circumference of the inner boundary of the end face 26 and the distance between the end face 26 and the valve plate surface 45a of the valve plate 45.

An outer surface is defined by the circumference of the outer boundary of the end face 26 and the distance between the end face 26 and the seal. This applies in particular in any open position, i.e., when the valve is not closed.

In the embodiment shown, the valve seat body 24 and the valve plate 45 are shaped such that the outer surface is larger than the inner surface, in particular in the open position.

The open position is defined in particular by a distance d between the valve plate 45, in particular the valve plate surface 45a, and the sealing surface 24a of the valve seat body 24. The following applies in particular to this distance: 0.2 mm < d < 1.0 mm.

In particular, the valve seat body 24 and the valve disk are shaped such that an area ratio of the outer surface to the inner surface is in a range between 1:1 and 5:1.

In particular, the seal 46 has a sealing height h of more than 0.1 mm and less than 1.0 mm from the valve plate. The seal thus protrudes from the valve plate 45 according to its height.

Such an advantageous design of the gas inlet valve 1 makes it possible to provide a precise and robust flow rate constancy, i.e. a constant flow rate through the gas application unit 2.

For gas inlet valves, it is typically critical that the flow through the valve be as uniform as possible. The requirements for flow consistency are in the range of < 1%. In state-of-the-art gas inlet valves, the flow-restricting part is usually located between the seal (typically made of PFA, PA, FFKM, or FKM) and the sealing surface. Since the seal material is usually made of an elastic material with significant thermal expansion behavior, this can result in uncontrolled flow influences, particularly due to changes in the thermal environment, opening/closing cycles with elastic and plastic compression, or other influences.

In order to counteract this disadvantage, the present invention is based on the idea of shifting the flow-throttling part of the valve away from the seal.

By setting back the sealing line as described, the flow-limiting area is created between the lower, flat metal surface (valve plate surface 45a) of the valve plate 45 and the inner connection, here the gas inlet 21. Thus, the flow-limiting area is no longer located between the seal and the sealing surface.

The ratio of inner shell surface to outer shell surface described above allows for further improved flow consistency to be provided in a robust and consistent manner.

The requirements for gas inlet valves are increasingly moving toward consistent and constant flow rates, which are required for various applications (e.g., ALD, CVD, etching). Current state-of-the-art diaphragm and other types of gas inlet valves can, at best, provide a flow rate consistency of +/-2%.

The proposed design of the gas inlet valve 1 can thus significantly improve the constancy of the C _v value, since deformation behavior (e.g. expansion) of the sealing material as well as the elastic and plastic behavior are removed from the flow-restricting region.

The invention will be explained with reference to exemplary embodiment(s), but numerous other changes and variations may be made without departing from the scope of the present invention. Therefore, it is intended that the appended claims cover such changes and variations as fall within the true scope of the invention.

Claims (12)

Gas inlet valve (1) for the controlled inlet of a fluid into a vacuum process chamber, wherein the gas inlet valve (1) comprises: - a gas application unit (2) with a gas inlet (21), a gas outlet (22) and an inner volume (23) connecting the gas inlet (21) and the gas outlet (22), wherein the gas application unit has a valve seat body (24) with a sealing surface (24a) in the inner volume (23), - an adjusting unit (4) projecting into the inner volume (23) with a valve plate (45) which is arranged within the inner volume (23) and has a seal (46), wherein - the adjusting unit (4) is movably mounted along an adjusting axis (V) in the closing direction (S) and in the opening direction (O), and - the valve plate (45) and the valve seat body (24) are designed to correspond to one another in such a way that the seal (26) in a Closed position, the sealing surface (24a) touches, - a drive unit (3) which is coupled to the adjustment unit (4) outside the gas application unit (2) and provides an adjustment of the adjustment unit (4) along the adjustment axis (V), wherein the valve plate (45) can be brought into an open position by means of the drive unit (3) in the opening direction (O), in which open position the seal (46) is spaced from the sealing surface (24a) and a fluid passage is provided, - a flexible sealing element (25) designed as a membrane, which is connected to the gas application unit (2) and to the adjustment unit and atmospherically separates the drive unit (3) from the inner volume (23), characterized in that - the valve seat body (24) is formed annularly around the adjustment axis (V) and has an annular end face (26) facing the valve plate (45), - the annular end face (26) has an inner Partial surface (27) and an outer partial surface (28), wherein a distance of the inner partial surface (27) to the adjustment axis (V) is smaller than a distance of the outer partial surface (28) to the adjustment axis (V), and - the outer partial surface (28) has the sealing surface (24a). Gas inlet valve (1) according to Claim 1 , wherein the inner partial area (27) is larger than the outer partial area (28). Gas inlet valve (1) according to Claim 1 or 2 , wherein the inner partial surface (27) and the outer partial surface (28) are annular. Gas inlet valve (1) according to one of the preceding claims, wherein the valve seat body (24) surrounds a cylindrical recess forming the gas inlet (21) or the gas outlet (22) and the recess has a cross-sectional area (21a) directed orthogonally to the adjustment axis (V), in particular wherein a radius of the cross-sectional area (21a) includes a corner radius, wherein the corner radius is defined by a curved course of the surface between a lateral surface of the recess and the end face (26). Gas inlet valve (1) according to Claim 4 , wherein the end face (26) lies in a valve seat plane and a projection of the cross-sectional area (21a) onto the valve seat plane defines an inner boundary of the end face and a projection of the course of the seal (46) onto the valve seat plane, in particular a sealing line, defines an outer boundary of the end face (26). Gas inlet valve (1) according to Claim 5 , where - an inner surface is defined by the Circumference of the inner boundary of the end face (26) and the distance between the end face (26) and a valve plate surface (45a) of the valve plate (45), in particular wherein the seal (46) runs around the valve plate surface (45a), and - an outer surface is defined by the circumference of the outer boundary of the end face (26) and the distance between the end face (26) and the seal (46). Gas inlet valve (1) according to Claim 6 , wherein the valve seat body (24) and the valve plate (45) are shaped such that the outer surface is larger than the inner surface, in particular in the open position. Gas inlet valve (1) according to Claim 6 or 7 , wherein the valve seat body (24) and the valve plate (45) are shaped such that an area ratio of the outer circumferential surface to the inner circumferential surface is in a range between 1:1 and 5:1. Gas inlet valve (1) according to one of the preceding claims, wherein the seal (46) is connected to the valve plate (45) and protrudes from the valve plate (45) with a sealing height h. Gas inlet valve (1) according to Claim 9 , where the sealing height h is: 0.1 mm < h < 0.5mm. Gas inlet valve (1) according to one of the preceding claims, wherein the following applies to a distance d between the valve plate (45), in particular the valve plate surface (45a), and the sealing surface (24a) of the valve seat body (24) in the open position: 0.2 mm < d < 1.2 mm. Gas inlet valve (1) according to one of the preceding claims, wherein the gas inlet valve has a restoring element (33), in particular a spring, wherein the restoring element (33) is arranged such that a restoring force is exerted on the adjusting unit (4) in the closing direction (S).