阅读说明：本技术 用于涂布机的分配喷嘴 (Dispensing nozzle for coating machine ) 是由 梅吉亚斯·卡德 于 2019-06-21 设计创作，主要内容包括：本发明涉及一种用于将涂层涂敷到基底上的分配喷嘴(1),具有：阀座(16)；阀元件(14),所述阀元件适于在关闭位置与打开位置之间移位,在所述关闭位置,所述阀元件与所述阀座(16)相互作用以关闭所述分配喷嘴(1)的涂层材料入口(2)与涂层材料出口(3)之间的连接,在所述打开位置,所述连接被打开；并且进一步具有收回元件(24),所述收回元件适于在前部位置与后部位置之间移位,所述收回元件(24)与所述分配喷嘴(1)的在所述阀元件(16)的下游的分配通道(18)流体连通。(The invention relates to a dispensing nozzle (1) for applying a coating to a substrate, comprising: a valve seat (16); a valve element (14) adapted to be displaced between a closed position, in which it interacts with the valve seat (16) to close a connection between a coating material inlet (2) and a coating material outlet (3) of the dispensing nozzle (1), and an open position, in which the connection is opened; and further having a retraction element (24) adapted to be displaced between a forward position and a rearward position, the retraction element (24) being in fluid communication with the dispensing passage (18) of the dispensing nozzle (1) downstream of the valve element (16).)

1. A dispensing nozzle (1) for applying a coating to a substrate, having: a valve seat (16); a valve element (14) adapted to be displaced between a closed position, in which it interacts with the valve seat (16) to close a connection between a coating material inlet (2) and a coating material outlet (3) of the dispensing nozzle (1), and an open position, in which the connection is opened; and further having a retracting element (24) adapted to be displaced between a forward position and a rearward position, the retracting element (24) being in fluid communication with a dispensing channel (18) of the dispensing nozzle (1) downstream of the valve element (14), wherein the retracting element (24) is a membrane exposed on one side to the dispensing channel (18).

2. Dispensing nozzle (1) according to claim 1, wherein the retraction element (24) is arranged transversely to the dispensing channel (18), in particular in a nozzle body (10) of the dispensing nozzle (1).

3. Dispensing nozzle (1) according to claim 1, wherein the retraction element (24) is arranged in the valve element (14) and is in fluid connection with the dispensing channel (18).

4. Dispensing nozzle (1) according to claim 1, wherein the valve element (14) is a sleeve, the diaphragm (24) being clamped to the valve element (14).

5. Dispensing nozzle (1) according to claim 1, wherein a sealing element (34) is provided which seals between the valve element (14) and the nozzle body (10) of the dispensing nozzle (1).

6. Dispensing nozzle (1) according to claim 5 in combination with claim 4, wherein the sealing element (34) is screwed into the valve element (14) and clamps the membrane (24) therein.

7. Dispensing nozzle (1) according to claim 1, wherein the retraction element is a piston which is exposed on one side to the dispensing channel (18).

8. Dispensing nozzle (1) according to claim 1, wherein a retraction control chamber (62) is provided, operatively connected to the retraction element (24).

9. Dispensing nozzle (1) according to claim 8, wherein a retraction control piston (64) is provided, which is exposed to the pressure in the retraction control chamber (62).

10. Dispensing nozzle (1) according to claim 9, wherein an adjustable retraction abutment (72) is provided for adjusting the maximum stroke of the retraction control piston (64).

11. Dispensing nozzle (1) according to claim 9 in combination with claim 6, wherein the sealing element (34) is guided on the retraction control piston (64).

12. Dispensing nozzle (1) according to claim 11, wherein the retraction control piston (64) is screwed on a protrusion (30) of the diaphragm (24).

13. Dispensing nozzle (1) according to claim 1, wherein a dispensing control chamber (52) is provided, operatively connected to the valve element (14).

14. Dispensing nozzle (1) according to claim 13, wherein an adjustable dispensing abutment (58) is provided for adjusting the maximum stroke of the valve element (14).

Technical Field

The present invention relates to a dispensing nozzle for applying a coating to a substrate, in particular a wafer.

Background

For the production of semiconductor chips and MEMS, it is known to apply a coating to a substrate (wafer), which is treated or facilitates the treatment of the substrate. It is important to apply the desired amount of coating to the surface of the wafer accurately since tolerances will result in a coating thickness that is higher or lower than it should be. Furthermore, after the process of applying the coating to the substrate is terminated, the droplets of the coating material are prevented from separating from the dispensing nozzle. Such droplets will cause a significant disturbance of the surface of the coating as flat as possible.

There have been various attempts to prevent droplets of coating material from separating from the dispensing nozzle after application of the coating has terminated. One widely used method is to use a vacuum line connected to the dispensing nozzle so that after the process of applying the coating material is stopped, a volume of coating material can be "sucked back" into the dispensing nozzle. This can lead to the formation of a so-called meniscus (meniscus) at the outlet of the dispensing nozzle, thereby preventing droplets from forming there and becoming detached from the dispensing nozzle.

A problem with this solution is that it prevents accurate metering of the amount of coating material supplied to the substrate, since it is not properly controlled how much coating material is "sucked back" into the dispensing nozzle at the end of the previous coating step, making it difficult to accurately meter the coating material applied in the subsequent coating step.

Disclosure of Invention

The aim of the invention is to increase the accuracy with which coating material can be metered through a dispensing nozzle, while at the same time reliably preventing droplets of coating material from unintentionally separating from the dispensing nozzle after the dispensing step has ended.

To this end, the invention provides a dispensing nozzle for applying a coating to a substrate, having: a valve seat; a valve element adapted to be displaced between a closed position, in which it interacts with the valve seat to close a connection between a coating material inlet and a coating material outlet of the dispensing nozzle, and an open position, in which the connection is opened; and further having a retracting element adapted to be displaced between a forward position and a rearward position, the retracting element being in fluid communication with the dispensing passage of the dispensing nozzle downstream of the valve element, wherein the retracting element is a diaphragm exposed on one side to the dispensing passage.

The invention is based on the basic idea of using a retracting element which mechanically "sucks" back a quantity of dispensed material downstream of the valve seat. Since the same amount of coating material can be "added" to the subsequent dispensing step precisely by moving the retraction element to the forward position, the retraction element allows very precise control of the amount of coating material that is sucked back into the dispensing nozzle at the end of one dispensing step, thereby facilitating correct metering of the coating material in the subsequent coating step. An additional advantage is that the suck-back is achieved close to the front end of the dispensing nozzle. This avoids the problems associated with prior methods in which suck-back is effected from a remote location, which is problematic in terms of accuracy and also leads to problems in that the material tends to outgas. Since the diaphragm is used as the retracting element, the dispensing channel side of the valve element can be very easily sealed from the "back side" of the valve element.

In one embodiment, the retraction element is arranged transversely to the dispensing channel, in particular in the nozzle body of the dispensing nozzle. This position of the retraction element results in a simple design.

In an alternative embodiment, the retraction element is arranged in the valve element and is in fluid connection with the dispensing channel. This design allows the formation of dispensing nozzles having very small dimensions, so that two or more dispensing nozzles can be arranged very close to each other on the application device.

By forming the valve element in the form of a sleeve, the diaphragm being clamped to the valve element, a very compact design can be achieved.

In order to prevent the coating material from contaminating the regions of the dispensing nozzle that should not be subjected to the coating material, a sealing element is provided that seals between the valve element and the nozzle body of the dispensing nozzle.

In order to reliably connect the diaphragm to the valve element without requiring a large space, the sealing element may be screwed into the valve element in order to clamp the diaphragm therein.

In an alternative embodiment, the retraction element is a piston which is exposed on one side to the dispensing passage. Since the piston is rigid, the amount of coating material sucked back into the dispensing nozzle can be controlled very precisely.

Preferably, a retraction control chamber is provided, operatively connected to the retraction element. The retraction control chamber allows for a very easy displacement of the retraction element between the forward and rearward positions by applying different levels of pressure to the sides of the control element exposed to the pressure in the retraction control chamber. As an example, applying a first (positive) pressure to the retraction control chamber may cause the retraction element to be in a forward position, while changing to a second (negative or lower) pressure may cause the retraction element to be displaced into a rearward position such that a defined volume of coating material is drawn back into the dispensing nozzle. The vacuum line and associated control elements and control logic of existing dispensing valves may continue to be used to control the operation of the retraction element or dispensing valve according to the present invention.

According to one embodiment, a retraction control piston is provided which is exposed to the pressure in the retraction control chamber. The retraction control piston is an intermediate element between the retraction element and, for example, the vacuum line and ensures that the retraction element is accurately controlled, especially in the case where the retraction element is a diaphragm or membrane. The retraction control piston may be mechanically connected to the retraction element.

Preferably, an adjustable retraction interface is provided for adjusting the maximum stroke of the retraction control piston. Retracting the docking member allows the amount of coating material that is drawn back into the dispensing nozzle to be adjusted according to the specific characteristics of the different coating materials so that the "correct" amount of coating material is drawn back at the end of the dispensing step independent of the specific coating material being processed.

The retraction interface may be a screw or contain threads and may be adjusted manually or remotely by using a stepper motor.

According to a preferred embodiment of the invention, a dispensing control chamber is provided which is operatively connected to the valve element. In a manner similar to controlling the movement of the retracting element, the dispensing control chamber is used to control the position and displacement of the valve element. This can be achieved by: the pressure level in the dispensing control chamber is varied such that when the force acting on the valve element towards the valve seat is higher than the force biasing the valve element away from the valve seat, the valve element is pressed against the valve seat and vice versa.

Preferably, the sealing element is guided on the retraction control piston such that a radial guiding function is provided for the valve element.

Preferably, the retraction control piston is screwed onto the protrusion of the diaphragm, which results in a compact and reliable connection.

Also for the valve element, the adjustable distribution docking piece may be arranged for adjusting the maximum stroke of the valve element. This allows the use of very basic control for the pressure level in the dispensing control chamber, since the pressure level therein is not necessary for controlling the position of the valve element in the open position. Instead, the pressure used is sufficient to displace the valve element between a fixed closed position (defined by the valve seat) and a fixed (but still adjustable) open position defined by the dispensing abutment.

The dispensing abutment may be in the form of a screw or use a threaded connection which converts rotation into translation so that the opening stroke of the valve element can be adapted to the specific properties of the different coating materials.

A drive mechanism, such as a stepper motor with gears, may be provided for adjusting the dispensing interface in an automatic manner based on the control signal.

Drawings

The present invention will now be described with reference to the accompanying drawings. In the drawings, there is shown in the drawings,

figure 1 shows a schematic cross-section of a dispensing nozzle,

figure 2 shows a cross-section of the core element of the dispensing nozzle of figure 1,

figure 3 shows in cross-section a valve element for use in a dispensing nozzle,

figure 4 shows the valve element of figure 3 in a perspective view,

figure 5 shows in cross-section a diaphragm for use in a dispensing nozzle,

figure 6 shows the membrane of figure 5 in a perspective view,

figure 7 shows in cross-section a sealing element for use in a dispensing nozzle,

figure 8 shows in cross-section an adjustable retraction interface for use in a dispensing nozzle,

figure 9 shows the adjustable retraction interface of figure 8 in perspective view,

figure 10 shows on an enlarged scale a portion of the dispensing nozzle in a state in which the coating material is being dispensed,

figure 11 shows the dispensing nozzle of figure 10 in a state where dispensing has been switched off,

fig. 12 shows the dispensing nozzle of fig. 10 in a state where some of the coating material has been sucked back.

Detailed Description

A dispensing nozzle 1 for applying a coating material on a substrate will now be described with reference to figures 1 to 9. The dispensing nozzle 1 is particularly suitable for machines used to produce semiconductor chips and MEMS.

The dispensing nozzle 1 has a nozzle body 10 provided with a coating material inlet 2 and a coating material outlet 3. The coating material inlet 2 is connected to a supply of coating material via a pipe or other suitable means. The coating material outlet 3 may be in the form of a nozzle or other configuration suitable for applying a particular coating material to a substrate.

Inside the nozzle body 10, a chamber 12 is arranged between the coating material inlet 2 and the coating material outlet 3. A valve element 14 is arranged in the chamber 12 and can cooperate with an annular valve seat 16 which is formed so as to circumscribe a dispensing passage 18 serving as the coating material outlet 3.

The side of the valve seat 16 or the direction toward the valve seat 16 will be referred to hereinafter as the "front", while the opposite side or direction will be referred to as the "rear".

The valve element 14 is displaceable between a closed position and an open position. In the closed position, the valve element 14 contacts the valve seat 16 with its front annular end. When the valve element 14 is sealed with respect to the nozzle body 10 (to be described in detail below), the connection between the coating material inlet 2 and the coating material outlet 3 of the dispensing nozzle 1 is closed at this position of the valve element 14. In the open position, the valve element 14 is spaced apart (in a controllable manner) from the valve seat 16, so that the flow connection between the coating material inlet 2 and the coating material outlet 3 is open. The amount of coating material dispensed by the dispensing nozzle 1 through the dispensing passage 18 then depends on the pressure at which the coating material is supplied, the viscosity of the coating material, and the stroke of the valve element 14 by which it is lifted from the valve seat 16.

The valve element 14 is a hollow sleeve (see especially fig. 3 and 4) having a tapered and rounded forward end face 20 adapted to contact the valve seat 16.

Inside it, the valve element 14 has an abutment 22 for a diaphragm 24 (see in particular fig. 5 and 6), which is arranged in a front portion of the valve element 14. At the rear of the abutment 22 (when viewed from the end face 20), the valve element 14 has an internal thread 26.

The diaphragm 24 has a disk-shaped front diaphragm 28 and a cylindrical protrusion 30 connected to the center of the diaphragm 28. A thread 32 is formed on the outer surface of the protrusion 30.

The separator 24 is formed of Polytetrafluoroethylene (PTFE) or perfluoroalkoxy resin (PFA). However, other materials may be used.

Here, the membrane 28 and the protrusion 30 are formed as one piece. However, it is also possible to form the protrusion 30 as a separate piece and then connect it to the membrane 28.

The diaphragm 24 is mounted inside the valve element 14 by clamping the outer periphery of the diaphragm 28 against an abutment 22 formed in the sleeve-like valve element 14. For this purpose, a sealing element 34 is used (see fig. 7).

The sealing element 34 is a hollow, generally sleeve-like body having a guide sleeve 36 at its front end and a sealing bellows 38 at its rear end.

The guide sleeve 36 has an inwardly tapered end face 40 which forms a support surface for the diaphragm 28 of the diaphragm 24. An external thread 37 is formed on the outer surface thereof.

At its rear end, the guide sleeve 36 has a control projection 42, which is provided with an external thread 44.

Here, the guide sleeve 36 and the control projection 42 form a continuous cylindrical guide surface 46.

The sealing bellows 38 is provided with an annular connection stiffener 48 which is used to clamp it to the nozzle body 10.

The sealing element 34 may be formed of the same material as the diaphragm 24, in particular PTFE. However, other materials may be used.

The outer periphery of the diaphragm 28 is clamped against the abutment 22 by screwing a guide sleeve 36 with its threads 37 into the threads 26 of the valve element 14. The projection 30 projects into the interior space of the valve element 14.

The annular connection reinforcement 48 of the sealing bellows 38 is clamped in a tight manner (in a light manner) between the two parts of the nozzle body 10, thereby sealing the chamber 12, so that the valve element 14 is arranged in the chamber 12 "between the coating material inlet 2 and the valve seat 16". A diaphragm 24 seals between the interior of the valve element 14 and the chamber 12.

The displacement of the valve element 14 is controlled by a dispensing control piston 50 which is disposed in a dispensing control chamber 52 formed in the nozzle body 10.

The dispensing control piston 50 has a connection protrusion 51 having an internal thread at its front end, which is screwed to the external thread 44 formed on the control protrusion 42 of the sealing element 34. Thus, any axial displacement of the dispensing control piston 50 is transmitted to the valve element 14 via the sealing element 34. The dispensing control piston 50 provides a guiding action for the valve element 14 when it is guided in the nozzle body 10.

The displacement of the dispensing control piston 50 within the dispensing control chamber 52 may be controlled by varying the pressure within the chamber 52. For this purpose, a pressure connection 54 is provided (see fig. 1). A spring 56 is arranged in the distribution control chamber 52 on the opposite side of the distribution control piston 50 to the side on which the pressure connection 54 is arranged.

In order to control the maximum displacement of the dispensing control piston 50 from the valve seat 16 in the direction of lifting the valve element 14 (rear direction), an adjustable dispensing abutment 58 is provided. The dispensing abutment 58 is formed by a screw extending into the dispensing control chamber 52. The maximum stroke of the dispense control piston 50 can be adjusted by screwing the dispense interface 58 more or less into the dispense control chamber 52.

As can be seen in fig. 2, the dispensing abutment 58 may be formed hollow so as to interact with a protrusion formed on the dispensing control piston 50 for performing a guiding function.

In a known manner, a seal 60 may be used to seal the piston 50 against the dispensing control chamber 52 and the nozzle body 10.

The dispensing control piston 50 is formed to be hollow such that a retraction control chamber 62 is formed therein. In the retraction control chamber 62, a retraction control piston 64 is arranged. It is provided with a protrusion 66 having a cavity with internal threads 68 at its front end. The threads 68 are threaded onto the threads 32 of the diaphragm 24.

By retracting the control piston 62, the diaphragm 28 of the diaphragm 24 may be displaced between the forward and rearward positions. Since the membrane 28 serves as one of the boundaries of the defined volume of the dispensing passage 18 when the valve element 14 is in the closed position, retracting the membrane 28 results in an increase of the volume of the dispensing passage 18, whereby a small volume of coating material is retracted into the dispensing passage 18 when the membrane 28 is retracted. The diaphragm 24 is referred to as a retraction element due to the retraction action exerted by the diaphragm 28 of the diaphragm 24 on the coating material.

The displacement of the retraction control piston 64 within the retraction control chamber 62 is controlled by varying the pressure in the retraction control chamber 62. For this purpose, a pressure connection 69 is provided (see fig. 1 and 2). A spring 70 is arranged in the retraction control chamber 62 on the opposite side of the retraction control piston 64 to the side on which the pressure connection 69 is arranged.

The pressure connection 69 can be formed in a retraction abutment 72, which is embodied here as a hollow adjusting screw, which engages by means of an external thread 74 into an internal thread 76 formed in the rear part of the dispensing control piston 50. Thus, when the valve element 14 is displaced, the retraction abutment 72 moves with the dispensing control piston 50.

The retraction control piston 64 may be displaced rearwardly (away from the valve seat 16) until it abuts the retraction abutment 72. The corresponding stroke may be adjusted by screwing the retraction abutment 72 more or less into the rear portion of the dispensing control piston 50.

To dispense the coating material, the valve element 14 is brought into the open state by increasing the pressure in the dispensing control chamber 52 to such an extent that the force of the spring 56 is overcome and the dispensing control piston 50 is moved in the rearward direction. Thus, the dispensing control piston 50 lifts the valve element 14 from the valve seat 16 via the sealing element 34. In this state shown in fig. 10, the coating material supplied via the coating material inlet 2 flows through the chamber 12 and exits through the distribution channel 18.

When the coating material is dispensed, the diaphragm 24 is in a forward position. This is accomplished by appropriately controlling the pressure in the retraction control chamber 62.

When the flow of coating material is to be stopped, the pressure in the dispensing control chamber 52 is reduced, so that the dispensing control piston 50 is moved in a forward direction by the action of the spring 56 and possibly by the pressure level applied to the dispensing control chamber 52 until the valve element 14 abuts at the valve seat 16. Then, the flow of the coating material is stopped. This state is shown in fig. 11.

To prevent coating material from dripping from the front end of the dispensing nozzle 1, a small amount of coating material is sucked back into the dispensing channel 18. This is accomplished by moving the retraction member 24 from the forward position to the rearward position shown in fig. 12. When the valve element 14 contacts the valve seat 16, the displacement of the retracting element 24 (more specifically, the displacement of the diaphragm 28) only acts on coating material located "downstream" of the valve seat 16. Thus, the volume sucked back into the front end of the valve element 14 may result in a small meniscus being formed at the outer end of the dispensing channel 18 and no coating material may drip from the dispensing nozzle 1 onto the substrate to be coated.