DISPENSING ARM HEAD HAVING POINT OF DISPENSE RECIRCULATION MODE

A dispense arm device for controllably discharging a fluid onto a substrate includes a dispense head coupled to and contained within an arm portion of the dispense arm device, wherein the dispense head having a valve assembly that is configured to operate in: (1) a recirculation mode in which a dispense outlet formed in the dispense head is closed off and a recirculation path is opened for allowing heated chemistry that is delivered to the dispense head to be delivered back from the dispense head to a remote location (e.g., a recycle tank); and (2) a dispense mode in which the dispense outlet is opened to allow heated chemistry to be discharged from the dispense head and the recirculation path is closed off.

TECHNICAL FIELD

The present invention relates to wafer processing equipment and more particularly, relates to a head for a dispensing arm that has both a point of dispense recirculation mode and a dispense mode and is constructed to minimize variation in the temperature of the chemistry deposited onto the wafer during processing.

BACKGROUND

In wafer processing equipment, tight process control is of paramount importance. Therefore, it is desirable to minimize variation in the temperature of chemistry deposited onto the wafer during processing.

SUMMARY

In accordance with one embodiment, the present invention provides a dispense arm for controllably discharging a fluid. The dispense arm includes a dispense head contained within an arm structure. The dispense head has a valve assembly that is configured to operate in: (1) a recirculation mode in which a dispense outlet is closed off and a recirculation path is opened for allowing heated chemistry that is delivered to the dispense head to be delivered back to a chemical supply location; and (2) a dispense mode in which the dispense outlet is opened to allow heated chemistry to be discharged from the dispense arm and the recirculation path is closed off.

The present invention minimizes variation in the temperature of chemistry deposited onto the wafer during processing by allowing for a continuous flow of chemistry through the dispense arm whether the arm is actively dispensing or not. Additionally, a thermocouple is built in near the point of dispense to allow accurate monitoring of the temperature of the chemistry. Advantages of this design include that there are no moving seals to wear or fail and all surfaces that touch chemistry can be made from chemically compatible fluoropolymers (e.g. Teflon).

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

FIG. 1illustrates a dispense arm100that is part of a wafer processing system. As will be understood by one of skill in the art, a wafer processing system includes equipment that is used to process the substrate to form a completed product, such as an integrated circuit wafer, which is typically in the form of flat round disks (although other shapes are possible) and often is made from silicon. A wafer processing system is thus configured to process the wafer using various chemicals. One process is the use of liquid chemical etchant to remove material from or on the substrate, this process is often referred to as wet etching. Commonly used methods include dispensing fluid on a wafer while spinning (referred to as “single wafer processing”). As wafer sizes increase and geometry sizes decrease, substantial benefits can be realized by employing single wafer processing inasmuch as the processing environment may be better controlled. The dispense arm100is thus the component that is configured to controllably dispense the fluid (chemistry (etchant)) onto the spinning wafer which is located below. The dispense arm100is operatively connected to an automated control system which is designed to controllably move the dispense arm100relative to the wafer's top surface so as to permit controlled dispensing of the chemical etchant at a desired location. Since the water is rotating, etchant that is dispensed at a single radial location results in a ring-shaped etch along the wafer's surface at the single radial location (i.e., at a given radius from the center).

As shown, the dispense arm100has a housing that can be constructed so as to include a base portion110and an arm portion120. The arm portion120extends radially outward from the base portion110and includes a distal portion122and a proximal portion124that is connected to the base portion110. In the illustrated embodiment, the arm portion120has a cylindrical shape; however, other shapes are equally possible. The arm portion120is also a hollow structure and is intended to receive a dispense head200that is illustrated in detail inFIGS. 2-5.

The dispense head200is configured to be received within the hollow interior of the dispense arm120. As shown inFIG. 1, the dispense head200extends distally beyond the distal portion122of the arm portion120. The finish/fit between the dispense head200and arm portion120is preferably clean and therefore, the dispense head200can have a cylindrical shape.

More particularly, the dispense head200includes a body210that has a first end212and an opposing second end214. The first end212of the body210defines the distal end of the dispense arm100. The body210has a first portion220that terminates in the first end212and a second portion230that is of reduced dimensions (e.g., diameter) relative to the first portion220. As illustrated, both the first portion220and the second portion230can have a cylindrical shape with an annular shaped shoulder being formed between the first portion220and the second portion230. As shown, adjacent the exposed free end of the second portion230, a ferrule240is provided. As understood, the ferrule240is a ring or cap. A clamp plate250is disposed adjacent the ferrule240and thus, the ferrule240serves to space the clamp plate250from the second portion230. The clamp plate250includes a number of holes formed therein as described below for allowing passage of other parts (e.g., conduits) and also to allow coupling of the clamp plate250to the second portion230as by a fastener260, such as a screw or bolt, etc.

As shown inFIGS. 2-5, a number of conduits (e.g., tubes) pass through the holes of the clamp plate250in a direction away from the second portion230. For example, a first conduit270, a second conduit280, a third conduit290, and a fourth conduit300are provided. The conduits can be in the form of tubes, etc. In the illustrated embodiment, the first conduit270comprises a fluid inlet conduit for delivering the chemistry (e.g., etchant) to the dispense head200and thus, the first conduit270can be thought of as being a chemical supply conduit. The second conduit280comprises a recirculation conduit that is intended to carry recirculated chemistry away from the dispense head200for recirculation thereof as described below. The third conduit290is a fluid inlet which can be in the form a compressed gas (air) conduit that is configured to deliver a fluid (e.g., compressed air) to the dispense head200. The fourth conduit300is another fluid conduit and can be in the form of a vacuum or suck back conduit for withdrawing fluid (chemistry) from the dispense head200. The first conduit270, second conduit280, third conduit290and fourth conduit300are circumferentially spaced apart from one another.

A thermocouple400is also provided and as described herein is used to monitor the temperature of the chemistry within the dispense head200. As is known, a thermocouple400is an electrical device consisting of two dissimilar electrical conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature. The thermocouple400is an elongated structure that has a first end402that is disposed internally within the dispense head200in contact with the flow of the chemistry as described below. An opposite second end404of the dispense head200is located outside of the dispense head200. Like the conduits270,280,290,300, the thermocouple400extends outwardly in a direction away from the second portion230. The length of the thermocouple400can be greater than the lengths of the conduits270,280,290,300.

The thermocouple400is also circumferentially spaced relative to the conduits. As shown, the conduits270,280,290,300and the thermocouple400are disposed about (radially from) a center of the second portion230and the clamp plate250. The conduits and the thermocouple can be spaced equidistant. The fastener260is centrally located within the second portion230and the clamp plate250. As shown inFIG. 6, the fastener260can serve to attach the second portion230to the first portion220in that the fastener260passes completely through the second portion230into the first portion220.

In accordance with the present invention, the dispense head200is constructed so that it can be operated in at least two operating modes, namely, a recirculation mode and a dispense mode. The dispense head200is constructed such that it allows for a continuous flow of chemistry through the dispensed arm100whether the dispense arm100is actively dispensing chemical or not. As describe below, the thermocouple400is built in near a point of dispense to allow accurate monitoring of the temperature of the chemistry (liquid). Advantages of this design include that there are no moving seals to wear or fail and all surfaces that touch chemistry can be made from chemically compatible fluoropolymers (e.g. Teflon) or other suitable materials.

In the recirculation mode of operation, heated chemistry enters the dispensing head200and is not dispensed through a dispensing outlet201but is recirculated back to the chemistry supply, thereby allowing it to be recycled. In the dispense mode of operation, the heated chemistry is routed to the dispensing outlet201.

As shown inFIGS. 6-10, the second portion230comprises a channeled body in that channels or passageways are formed to both receive ends of the conduits270,280,290,300and thermocouple400. Thus, for each of the conduits270,280,290,300and the thermocouple400, there is a corresponding channel or passageway formed in and through the second portion230. The channels are sized so that the ends of the conduits270,280,290,300and thermocouple400can be received and contained and held within the respective channels/passageways. This allows fluid to flow through the conduit and into or out of the respective channel formed in the second portion230.

In the illustrated embodiment, the second portion230thus includes a first passageway231that receives the first conduit270; a second passageway233that receives the second conduit280; a third passageway235that receives the third conduit290; and a fourth passageway237that receives the fourth conduit300. The fastener260passes through a center passageway. In one embodiment, each of the passageways231,233,235and237are linear in shape.

The first portion220is designed so as to be complementary to and be in fluid communication with the passageways231,233,235and237formed in the second portion230. Therefore, the first portion220comprises a channeled body and further includes a valve assembly500that is movably contained therein. As described herein, the valve assembly500can be thought of as being a three-way valve.

As shown, the valve assembly500can be centrally located within the first portion220and includes a valve cavity (space or inner compartment)502that is formed within the first portion220. The valve cavity502has a first end503and an opposing second end504. As shown, the dimensions of the valve cavity502can vary along its length and in particular, the first end503can have smaller dimensions than the second end504. A right-angle shoulder can be formed between two different defined sections of the valve cavity and in particular, the valve cavity502can include a first section505that terminates in the first end503and a second section507that terminates in the second end504.

The valve assembly500also includes a movable valve510that can be positioned in an extended position and a retracted position as described herein. The valve510comprises a plunger520that has a main body portion522and a forward flange portion524at one end thereof and a rear flange portion528at another end thereof. Between the forward flange portion524and the main body522is a shaft portion526that has dimensions smaller than the forward flange portion524and main body522. For example, a diameter of the forward flange portion524and a diameter of the main body522can be the same, while the shaft portion526has a smaller diameter. The rear flange portion528can have a diameter that is greater than the main body522. The rear flange portion528is sized only for reception and travel within the second section507. There is an annular space525formed about the shaft portion526due to the reduced diameter of the shaft portion526.

The valve assembly500further includes a bellows530that is disposed circumferentially about the main body portion522and a return spring540that is also disposed about the main body portion522(radially outward from the bellows530). The bellows530and return spring540are also sized only for reception and travel within the second section507. The bellows530and return spring540are disposed adjacent the rear flange portion528and thus act thereon when a return biasing force is generated as discussed below. As shown, at the forward end of the second section507is a stop509that limits the degree of travel of the bellows530and return spring540when the valve510moves in a forward direction. As described herein, when the valve510is moved forward, the bellows530and return spring540contact the stop509(which can be thought of as being a shoulder between the first section505and second section507) and become compressed, thereby storing energy. In this condition, the bellows530and return spring540are compressed between the stop509and the rear flange portion528. When the driving force is removed from the plunger520, the stored energy is released and the plunger520is driven rearward as described herein.

As mentioned herein, the first portion220of the dispense head200is channeled and in particular, there are channels/passageways that are in fluid communication with the channels/passageways formed in the second portion230and the valve cavity502. More specifically, the first portion220includes a first channel/passageway310that is in fluid communication with the first passageway231and the first conduit270and also is in fluid communication with the valve cavity502. The first portion220includes a second channel/passageway312that is in fluid communication with the second passageway233and the second conduit280and also is in selective fluid communication with the valve cavity502. The first portion220includes a third channel/passageway314that is in fluid communication with the third passageway235and the third conduit290and also is in fluid communication with the valve cavity502. The first portion220includes a fourth channel/passageway316that is in fluid communication with the fourth passageway237and the fourth conduit300and also is in fluid communication with the valve cavity502.

As shown inFIGS. 8 and 9, the first channel310can include an angled portion that leads to another portion that leads to the valve cavity502for carrying the heated chemistry to the valve cavity502. Along the angled portion, one end of the thermocouple400is exposed and is in contact with the heated chemistry for measuring the temperature of the heated chemistry as it flows toward the valve cavity502. As shown inFIG. 8, one end of the first channel310communicates with the forward end (first section505) of the valve cavity502.

The second channel312also communicates with the forward end (first section505) of the valve cavity502as shown inFIG. 7and as described below and will be appreciated in view ofFIGS. 8 and 9, the liquid chemistry that is delivered to the forward end of the valve cavity502(forward of the valve510) can flow into the second channel312and then into the second passageway233and ultimately the second conduit280which leads to the source of the chemistry, thereby allowing the reuse of the chemistry when the dispense head200is operating in recirculation mode.

As shown inFIG. 10, the third channel314communicates with a rear end (second section507) of the valve cavity502and more particularly, the third channel314opens into the valve cavity502to the rear of the rear flange portion528. As a result, when the fluid travels within the third channel314, the fluid directly contacts the rear flange portion528and causes movement of the valve510within the valve cavity502. The fluid (e.g., compressed air) within the third channel314is therefore the driving force for causing the plunger520to move from the retracted (at rest) position (FIGS. 6-10) to the extended position (FIGS. 11-15). The force of the fluid within the third channel314is greater than the biasing force of the return spring540and therefore, the force of the fluid is able to exert a sufficient force against the rear flange portion528to cause forward movement of the plunger520within the valve cavity502.

The fourth channel316communicates with the fourth conduit300with a forward end of the fourth channel316communicating with the valve cavity502as shown inFIG. 6. Unlike the first and second channels310,312that communicate with the forward end of the valve cavity502, the fourth channel316communicates with a dispensing portion of the valve cavity502. The dispensing portion includes dispensing outlet (dispense port)201which discharges the chemistry (heated liquid) from the valve cavity502. The dispensing outlet201is formed as a channel in the second portion230and extends radially outward from the valve cavity502and is open along the outer surface of the second portion230. As shown, the dispensing outlet201is spaced from the first end (forward end) of the valve cavity502. As described below in more detail, the fourth channel316is intended for selectively withdrawing any chemistry (liquid) that remains in the dispensing portion after dispensing action has been completed. The fourth conduit300is operatively connected to a suction source or similar equipment which can generate negative pressure within the fourth conduit300, the fourth channel/passageway316and the fourth passageway237.

As shown inFIG. 10, when the forward flange portion524is retracted, its degree of travel is limited by a wall229that can be considered to be a valve seat for the forward flange portion524, whereby the spaces515,525are sealed from one another.

As mentioned above, the dispense head200operates in a recirculating mode (FIGS. 6-10) and a dispense mode (FIGS. 11-15) each of which is discussed below.

Recirculation ModeFIGS. 6-10illustrate the recirculation mode. In the recirculation mode, the valve510is located in the fully retracted position in which the rear flange portion528is proximate to or in contact with rear wall of the rear end of the valve cavity502. When the valve510is in this position, the forward flange portion524is spaced from the first end503of the valve cavity502so as to define a forward space515that is located between the forward flange portion524and the first end of the valve cavity502. In the recirculation mode, the chemical supply path (defined by the first conduit270, the first channel/passageway310, and the first passageway231) delivers the chemistry (liquid) to the forward space515ahead of the forward flange portion524. Since the recirculation path (defined by the second conduit280, the second channel/passageway312, and the second passageway233) is also in fluid communication with the forward space515, the heated chemistry delivered to the forward space515is routed to the recirculation path resulting in the delivered heated chemistry being recirculated when the dispense head200is in the recirculation mode which is a mode in which the chemistry is not dispensed from the dispense arm100.

The dispense outlet201is thus closed in the recirculation mode. As shown inFIG. 6, the dispense outlet201communicates with the annular space525formed about the shaft portion526but does not communicate with the forward space515to which the heated chemistry is delivered and thus, the heated chemistry is not dispensed. Likewise, the suction pathway defined by the fourth conduit300, the fourth channel/passageway316and the fourth passageway237is closed off since it communicates with the dispensing portion of the valve cavity502which again is placed offline due to the location of the plunger520within the valve cavity502(in the retracted position).

As the chemistry flows through the chemical supply line, it contacts the thermocouple400which allows for accurate temperature control. Outside of the dispense arm100, the recirculation path flows into a receptacle, such as a tank, (chemical supply) that is, in turn, feed into the chemical supply line (conduit270), allowing the chemistry to be recycled.

Dispense Mode

In the dispense mode of operation, the chemistry (fluid) is discharged through the dispense outlet201while the recirculation path is closed off such that the heated chemistry is prevented from flowing within the recirculation path.

To switch the dispense head200from the recirculation mode to the dispense mode, fluid (e.g., compressed air or nitrogen) is blown in through the compressed air path resulting in the fluid contacting the rear flange portion528causing the plunger520to be driven forward. This driving action of the plunger520causes the compression of the bellows530and return spring540as the plunger520pushes forward. As the plunger520moves forward within the valve cavity502, it opens the dispense path and covers up the opening to the recirculation path. A comparison ofFIGS. 6-10(recirculation) withFIGS. 11-15(dispense) shows that in the dispense mode of operation, the chemical supply path is in fluid communication with the annular space525formed about the shaft portion526and the forward space515is eliminated. As shown inFIG. 11, in a dispensing mode, the dispense outlet201is in fluid communication with the annular space525and thus, when the heated chemistry flows into this annular space525from the chemical supply path, the heated chemistry flows into and through the discharge outlet (dispense point)201. As shown inFIG. 12, the recirculation path is closed off by the elimination of the forward space515by placement of the forward flange portion at the first (front) end of the valve cavity502(which is where the entrance to the recirculation path is located).

This valve arrangement allows the fluid to continue flowing through the chemical supply path at the same temperature and flow rate, without interruption, thus maintaining steady process conditions. The only difference in the dispense mode of operation is that the flow is now directed through the dispense outlet201and onto the surface of the wafer being processed.

When the process is completed, releasing the gas pressure that compressed the bellows530and return spring540allows the return spring540to push the plunger520back to its previous location, closing off the flow to the dispense outlet201and opening the recirculation path again.

Additionally with reference toFIG. 11, the inclusion of the suck back path allows the chemistry stranded in the dispense point (the annular space525and the dispense outlet201) to be sucked back through the dispense head200, thus preventing dripping after the dispense is shut off. For example, negative pressure (a vacuum) can be supplied to the suck back path causing any chemistry that may remain within the annular space525or even within the dispense outlet201) to be sucked through the suck back path (to a collection vessel). As mentioned, this prevents any chemistry from dripping.

It will be understood that the suck back path can be eliminated to allow a volume of fluid to be held in the valve cavity502.

FIGS. 16A and 16Billustrate an alternative arrangement between the valve seat and the plunger. In particular, inFIG. 16B, a flexure seat600is provided and represents a flexible flange that is created by forming an annular shaped recess602, thereby defining the flexure seat600about which the plunger520seats when in its retracted position. Unlike the surface to surface valve seat229ofFIG. 10, the flexure seat600has a degree of flexibility that provides a sealing arrangement between the plunger520and the valve seat (flange600).

The flange600can be formed of a suitable material that can flex, such as certain plastics, rubbers, etc.

FIGS. 17A and 17Billustrate an alternative arrangement between the valve seat and the plunger. In particular, inFIG. 17B, an O-ring610is provided and disposed about the plunger520with the shaft portion526of the plunger520passing therethrough. The O-ring610can be anchored into the body210of the dispense head200(e.g., by being provided on a ledge as shown) proximate the dispensing outlet201. The O-ring610thus provides a sealing arrangement between the plunger520since the plunger520seats against the O-ring610in its retracted position. UnlikeFIG. 10arrangement in which the plunger and valve seat sealing arrangement is a surface-to-surface arrangement, inFIG. 17B, the plunger520seats against the O-ring610to provide improved sealing (to prevent any leakage between spaces515,525).

FIGS. 18A and 18Billustrate an alternative arrangement between the valve seat and the plunger520. In particular, inFIG. 18B, a gasket620is provided and disposed about the plunger520with the shaft portion526of the plunger520passing therethrough. The gasket620thus provides a sealing arrangement between the plunger520since the plunger520seats against the gasket620in its retracted position. UnlikeFIG. 10arrangement in which the plunger and valve seat sealing arrangement is a surface-to-surface arrangement, inFIG. 18B, the plunger520seats against the gasket620to provide improved sealing (to prevent any leakage between spaces515,525) since the gasket620has different properties (e.g., elasticity) than a hard surface (FIG. 10).

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It would be apparent to one skilled in the relevant art(s) that various changes in form and detail could be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.