Fluid Vapor Mixing and Delivery System

Abstract

In one aspect, the present invention provides a method and apparatus for supplying IPA vapor to a substrate processing chamber, the method comprising: a controller; a liquid mass flow controller (LMFC) associated with a vaporizer for converting a first fluid into a vapor; a mass flow controller (MFC) associated with a carrier gas; a mixing unit for mixing the vapor with the carrier gas to create a predetermined mixture; and a drain circuit including a first flow path having a first valve between the mixing unit and a drain, and a second flow path having a second valve between the mixing unit and the processing chamber, whereby the first flow path can be opened until the predetermined mixture is reached, after which the second flow path can be opened to allow the predetermined mixture to be supplied to the chamber.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The embodiments described herein relate generally to equipment used in the manufacture of electronic devices, and more particularly to substrate processing systems that may be used to clean the surface of a substrate. [Background technology]

[0002] One of the most important tasks in the semiconductor industry is cleaning and preparing silicon surfaces for further processing. Its primary objectives are to remove contaminants, such as particles, from the wafer surface and to control chemically grown oxides on the wafer surface. Modern integrated electronics would not be possible without the development of cleaning and contamination control technologies, and further reduction in silicon wafer contamination levels is essential for further reductions in IC feature dimensions. Wafer cleaning is the most frequently repeated operation in IC manufacturing and one of the most important segments of the semiconductor equipment business, and it appears as though wafer cleaning will remain that way for some time. Every time device feature sizes shrink or new tools and materials are introduced into the manufacturing process, the task of cleaning becomes more complex.

[0003] Most cleaning methods can be roughly divided into two major groups: wet and dry. Liquid chemical cleaning processes are commonly referred to as wet cleaning. Liquid chemical cleaning processes rely on a combination of solvents, acids, and water to spray, scrub, etch, and dissolve contaminants from the wafer surface. Dry cleaning processes use gas-phase chemistry and rely on the chemical reactions required for wafer cleaning as well as other techniques such as laser, aerosol, and ozonated chemistry.

[0004] Among wet chemical cleaning methods, the RCA clean, developed in 1965, still forms the basis for most front-end wet cleaning. A typical RCA-type cleaning sequence begins with the use of a H2SO4 / H2O2 solution, followed by a dip in dilute HF (hydrofluoric acid). A standard clean 1 operation (SC1) may use a NH4OH / H2O2 / H2O solution to remove particles, while a standard clean 2 operation (SC2) may use a HCl / H2O2 / H2O solution to remove metals. Despite increasingly stringent process demands and orders of magnitude improvements in analytical techniques, chemical cleanliness, and DI water, the basic cleaning strategy has remained unchanged since the initial introduction of this cleaning technology. Thirty years ago, environmental concerns and cost-effectiveness were not significant issues, so RCA cleaning procedures are far from optimal in these respects.

[0005] Marangoni drying is a commonly used method for drying wafers after processing on a wet bench. This method uses the difference in surface tension gradient between IPA and DI water to help remove water from the wafer's surface. This surface tension phenomenon is known as the Marangoni effect. The Marangoni effect is characterized by a thin liquid film and foam, whereby stretching the interface reduces the surface excess surfactant concentration and therefore increases the surface tension; the resulting surface tension gradient causes the liquid to flow toward the stretched area, thus providing both a "healing" force and a resistance to further thinning.

[0006] In the Marangoni drying operation described above, IPA vapor is combined with a carrier gas, such as N2, and then delivered to the surface of the substrate through a nozzle. In most conventional designs, the IPA vapor is generated in a refillable container and stored in a box within the processing system. As the demand for substrate drying increases, multiple fluid boxes, each with its own container, are required to accommodate multiple chambers adapted to perform the Marangoni drying process. Due to their size, having a separate container for each box is an inefficient use of space and also requires additional time as each container needs to be periodically filled and refilled.

[0007] Another challenge with surface drying using the above-described methods relates to the ability of the IPA mixture distribution component to deliver a consistent concentration of IPA vapor in the carrier gas to the substrate surface during the beginning, middle, and end of the Marangoni drying process. In one example, due to unsteady flow experienced in the IPA mixture distribution component during the initial stages of the Marangoni drying process, it can take several seconds before the desired concentration is reached at the beginning of the drying process. This can result in drying-related defects or contamination of the substrate surface caused by incorrect flow rates and mixtures of IPA vapor and carrier gas delivered to the substrate surface. Furthermore, in Marangoni-type dryers, a constant throughput of substrates through the process chamber is desired, and delaying the Marangoni process to allow the IPA mixture to stabilize can result in substrate throughput issues.

[0008] Therefore, there is a need for a more efficient fluid delivery system that requires a smaller footprint while serving several chambers.

[0009] There is a further need for a drying apparatus that allows for a constant throughput of substrates while ensuring proper fluid concentration throughout the drying cycle. Summary of the Invention

[0010] The present disclosure generally describes an apparatus and method for supplying IPA vapor to a substrate processing chamber. In one aspect, the present invention includes a controller, a liquid mass flow controller (LMFC) associated with a vaporizer for converting fluid IPA into IPA vapor, a mass flow controller (MFC) associated with a carrier gas, a mixing unit for mixing the IPA vapor with the carrier gas to create a predetermined mixture, and a drain circuit including a first flow path having a first valve between the mixing unit and a drain, and a second flow path having a second valve between the mixing unit and a processing chamber, whereby the first flow path can be opened until the predetermined mixture is reached, after which the second flow path can be opened to allow the predetermined mixture to be supplied to the chamber.

[0011] In another embodiment, a fluid box assembly includes a controller; a first box having an IPA container for storing liquid IPA, the liquid IPA being pressurized for delivery via a first fluid path to a first liquid mass flow controller (LMFC) associated with a first vaporizer for converting the fluid IPA into IPA vapor, a first mass flow controller (MFC) associated with a carrier gas, and a first mixing unit for mixing the IPA gas with the carrier gas to create a predetermined mixture for delivery to a first processing chamber; a second box having a second LMFC associated with a second vaporizer for converting the fluid IPA into IPA vapor, a second MFC controller associated with the carrier gas, and a second mixing unit for mixing the IPA vapor with the carrier gas to create a predetermined mixture for delivery to a second processing chamber; and a second fluid path between the IPA container and the second box.

[0012] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that since the present disclosure may admit of other equally effective embodiments, the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered limiting of its scope. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates a cross-sectional view of a cleaning chamber in a CMP processing system according to one or more embodiments. [Figure 2] 1 is a simplified diagram illustrating a gas supply system according to one aspect of the present invention. [Figure 3] FIG. 2 is a schematic diagram of the components of a main fluid box, according to one aspect of the present invention. [Figure 4] FIG. 1 is a schematic diagram of one aspect of the present invention showing a main fluid box and a remote fluid box. DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 1 is a cross-sectional view of a cleaning chamber in a chemical mechanical polishing (CMP) processing system, according to one or more embodiments. Generally, an ICD chamber 110 may be utilized to remove contamination from a substrate 200 that, if not removed, could result in the corresponding substrate 200 not meeting cleanliness requirements for subsequent processing steps and being discarded. In one example, the ICD chamber 110 is configured to perform a cleaning and drying process that prevents the formation of water droplet tracks on the surface of the substrate 200. In the illustrated embodiment, a substrate is introduced into the chamber 110 through an entrance door 610 on one side of the chamber, and after cleaning, the substrate exits through an exit door 615 on the opposite side. Generally, the process performed in each ICD chamber 110 is the final cleaning process performed in a cleaning sequence performed on a substrate in the CMP system 100. The process performed in each ICD chamber 110 may include one or more cleaning steps in which a cleaning or rinsing fluid (e.g., DI water) is applied to the top and / or bottom sides of the substrate, and then a drying process is performed on the substrate.

[0015] The ICD chamber 110 includes a substrate gripping device 603, a sweep arm 630, a first nozzle mechanism 640, a second nozzle mechanism 641, a plenum 680, a drain / exhaust 660, and a gas source 670. The ICD chamber 110 may further include a sensing device 694, such as a camera for detecting the status of the cleaning process or a retro-reflective position sensing device for sensing the position of the substrate within the internal volume 695.

[0016] One or more fluids may be applied to the processing side of the substrate 200 by a first nozzle mechanism 640 and a second nozzle mechanism 641. For example, a first fluid supply source 643 may provide deionized water, an inert gas, and / or IPA vapor to the second nozzle mechanism 641, which is positioned to supply fluids to the surface of the substrate 200, and the first nozzle mechanism 640 may apply deionized (DI) water to the processing side of the substrate 200. As further disclosed herein, the IPA vapor is provided from an IPA vapor supply assembly that may include an IPA vapor source 644 and a carrier gas source 645. The IPA vapor source 644 may include an IPA liquid vaporizer (not shown) configured to receive liquid IPA and convert the liquid IPA into a vapor, which is then mixed with a carrier gas (e.g., N) provided from the carrier gas source 645 and then provided to the surface of the substrate during the Marangoni drying process.

[0017] During processing, once the substrate 200 is placed on the bracket of the substrate gripping device 603, the bracket may be lowered to a process position as shown in FIG. 1. In one embodiment, as shown in FIG. 1, the first nozzle mechanism 640 and the second nozzle mechanism 641 may each be positioned to direct a flow of gas, vapor, or liquid onto the top surface of the substrate 200. The second nozzle mechanism 641 may flow one or more cleaning solutions, such as those used in an RCA cleaning process, to contact the substrate 200 at a first location on the surface of the substrate (e.g., the center of the substrate) during processing. The second nozzle mechanism 641 may also be used in a rinse cycle to flow an IPA mixture, or some other surface tension-reducing chemical, onto the top surface of the substrate at a second location. The distance between the first nozzle mechanism 640 and the second nozzle mechanism 641, i.e., edge-to-edge, may be positioned such that the streams from the first nozzle mechanism 640 and the second nozzle mechanism 641 can be separated by a desired distance. The IPA mixture may be generated prior to entering the process chamber 100, as described further below. The first nozzle mechanism 640 and the second nozzle mechanism 641 may be movable, for example, by pivoting or by linear translation across the surface of the substrate. During the drying process, while the first nozzle mechanism 640 and the second nozzle mechanism 641 are translated, the first nozzle mechanism 640 may dispense a first fluid (e.g., DI water) and the second nozzle mechanism 641 may provide the IPA mixture, thus performing the Marangoni drying process. Moving the first nozzle mechanism 640 and the second nozzle mechanism 641 may move the contact point for the fluids (the first location and the second location, respectively) from the substrate center toward the substrate edge. The first nozzle mechanism 640 and the second nozzle mechanism 641 may be attached to each other to move in unison, or the first nozzle mechanism 640 and the second nozzle mechanism 641 may move independently.

[0018] The airflow provided to the ICD chamber 110 may be provided at a desired pressure and flow rate to ensure removal of vapors (e.g., IPA vapor) and / or airborne particles that form within the processing region of the ICD chamber 110 during processing. In some embodiments where nitrogen gas is supplied to the ICD chamber 110, it may be desirable to eliminate the use of HEPA filters from the system to reduce system and maintenance costs and system complexity. In some embodiments, the gas source 670 is configured to provide filtered air or other gas such that a desired pressure (e.g., greater than atmospheric pressure) is maintained in the processing region of the ICD chamber.

[0019] FIG. 2 is a simplified diagram illustrating a fluid delivery system according to one embodiment of the present invention. The system includes an enclosure 400 that houses a main fluid box 500 and two remote fluid boxes 505, 510, with a fluid path 515 passing between them. As described in more detail herein, the fluid path 515 serves to transfer liquid IPA from an IPA container (not shown) in the main fluid box to the remote fluid boxes. The fluid boxes 500, 505, 510 serve to mix fluids, in this case IPA vapor and N2 gas, prior to delivery of the desired mixture to a processing chamber 110, such as that shown and described with respect to FIG. 1. FIG. 2 facilitates understanding of the arrangement of the fluid boxes 500, 505, 510 within the enclosure 400 and the movement of liquid IPA, and does not include the portions of the apparatus that actually mix and deliver gases to the chamber.

[0020] 3 is a schematic diagram of components of a main fluid box 500 according to one embodiment of the present invention. These components include a container 520 containing liquid IPA, which is typically pressurized with an inert gas such as N2 to move the liquid from the container along a flow line 521 toward a liquid mass flow controller (LMFC) 525. The LMFC 525 is used to automatically control the flow rate of the liquid according to set flow rate commands sent as electrical signals from a system controller 530, regardless of the pressure conditions of the liquid. The system controller 530 includes a programmable central processing unit (CPU) and is in communication with several components of the fluid box 500, including the LMFC 525, a mass flow controller (MFC) 526, and a vaporizer unit 527 for converting the IPA fluid into IPA vapor. Dotted lines 528 between the controller and other components indicate communication paths and relationships between those components.

[0021] From LMFC 525, liquid IPA is pushed at a predetermined flow rate of the liquid IPA through flow line 521 to vaporizer unit 527, which acts to vaporize the liquid IPA and supply the vaporized IPA to mixer 535. Separately, a source of N gas 540 controlled by gas valve 545 (e.g., a pressure regulator) enters its own MFC 526, which automatically controls the flow rate of N gas according to predetermined settings through the use of system controller 530. Predetermined flow rates of IPA vapor and N gas then enter gas / vapor mixer 535. Once the IPA vapor is mixed with the nitrogen gas in the mixer, the predetermined mixture proceeds along flow line 521 toward chamber 110.

[0022] Also shown in FIG. 3 is a drain circuit 700 including a “T” junction 705, with a first flow path 710 leading to the chamber 110 and a separate flow path 715 leading to a drain 720 (also visible in FIG. 1 ). In each case, there are automatically controlled valves 730, 740 operable by the controller 530 to open and close the flow paths 715, 710 to the drain 720 and the chamber 110, respectively. The drain circuit 700 is constructed and configured to ensure that the flow rates and concentrations of the process gases (IPA vapor and N gas) in the mixture are at or near a desired rate and / or predetermined mixture when introduced into the chamber for delivery onto the surface of the substrate 200 via the nozzle 640. In one embodiment of the invention, the chamber valve 740 is initially closed and the drain valve 730 is opened, allowing the predetermined mixture of IPA vapor and N gas to flow through the flow path 715 to the drain 720. Once the flow “ramps up” or reaches its desired flow rate, or steady state, the drain valve 730 is closed and the chamber valve 740 is opened, thereby avoiding exposing the nozzle 640, and with it the substrate 200, to an incorrect flow rate or mixture that can cause drying-related defects or contamination on the substrate as it is being processed. In some cases, an incorrect flow rate or mixture can include an initial burst of IPA vapor and N gas mixture onto the surface of the substrate 200, which has been found to cause particles and other related defects on the surface of the substrate. In one embodiment, once the desired flow rate is established, the drain valve 720 is closed and the chamber valve 740 is simultaneously opened. In another embodiment, there is a delay between closing the drain valve 720 and opening the chamber valve 740. In yet another embodiment, the drain valve 720 is closed at a predetermined rate, or closed to a certain point, and the chamber valve 740 is opened in an opposite manner at the same rate.In another embodiment, drain valve 730 is opened when a substrate is introduced into chamber 110 through entrance door 610 (FIG. 1) to have the mixture in the correct flow when the substrate reaches its processing position, and after the substrate reaches its processing position, the drain valve is closed and chamber valve 740 is opened to provide the mixture with the desired flow / mixture characteristics to nozzle 640. Once the substrate is processed and moved toward exit door 615, chamber valve 740 is closed and drain valve 720 is reopened. It will be appreciated that any number of timing configurations for the open / close positions of valves 720, 740 are possible depending on aspects of the particular process, including the throughput requirements of substrates through the chamber.

[0023] FIG. 4 is a schematic diagram of one embodiment of the present invention showing a main fluid box 500 and a remote fluid box 510. FIG. 4 illustrates the use of multiple fluid boxes, all relying on a single liquid IPA container 520 to reduce the footprint of an enclosure with any number of fluid boxes, each providing a predetermined fluid mixture to an assigned chamber 110, 110a. While FIG. 4 includes only one remote box 510, it will be understood that any number of remote fluid boxes can operate according to embodiments of the present invention, limited only by the number of associated chambers in the manufacturing facility and the capacity of the single IPA container 520 in the main fluid box 500. In one embodiment, the IPA container 520 is provided with a fluid level sensor (not shown) to automatically maintain the liquid IPA in its container at a predetermined level sufficient to provide liquid to all of the IPA mixing components in the fluid box. As shown in FIG. 2, the remote fluid box is physically smaller than the main fluid box due to the absence of an IPA container, thereby saving valuable space and reducing the footprint of the enclosure 400. As shown, the remote box 510 contains all of the components of the main fluid box except for the liquid IPA container. The remote fluid box components include a source 540a of N2 carrier gas, an MFC 526a for N2 gas, an LMFC 525a for liquid IPA, an IPA vaporizer 527a, and a mixing unit 535a. A drain circuit 700a, such as the drain circuit 700 described with respect to FIG. 3, is also included. A second fluid flow path 521a is provided from the IPA container 520 in the main fluid box 500 to the LMFC 525a in the remote fluid box 510. In the illustrated embodiment, both boxes 500, 510 rely on a single controller 530.

[0024] The drain circuit 700, 700a shown and described herein is particularly advantageous in processes requiring a nearly constant throughput of substrates. In one example, substrates are delivered to a chamber for processing and then immediately moved to a drying chamber. Any delay while the predetermined gas / vapor mixture ramps up could result in substrate defects. Once the predetermined mixture of vapor and carrier gas is achieved in the drain circuit, this can be maintained by keeping the vent valve open whenever the chamber valve is closed when a completed substrate is robotically removed from the chamber and the next substrate is placed in the chamber.

[0025] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. 1. An apparatus for delivering a predetermined mixture of fluids to a substrate in a processing chamber, comprising: A controller; a liquid mass flow controller (LMFC) associated with a vaporizer configured to convert the first liquid into a vapor; a mass flow controller (MFC) associated with the carrier gas; a mixing unit for mixing the vapor with the carrier gas to create the predetermined mixture; A drain circuit, a first flow path having a first valve between the mixing unit and a drain; a second flow path having a second valve between the mixing unit and the processing chamber; Including, a drain circuit whereby the predetermined mixture is provided through the first flow path for at least a first period of time before the second valve in the second flow path is opened to allow the predetermined mixture to be delivered to the surface of the substrate in the processing chamber; and An apparatus comprising:

2. The apparatus of claim 1 , wherein the first liquid comprises isopropyl alcohol (IPA).

3. 3. The apparatus of claim 2, wherein at the end of the first time period, the first valve in the first flow path is closed while the second valve in the second flow path is opened.

4. 3. The apparatus of claim 2, wherein at the end of the first time period, the first valve in the first flow path is closed after the second valve in the second flow path is opened.

5. 3. The apparatus of claim 2, wherein at the end of the first time period, the first valve in the first flow path remains open after the second valve in the second flow path is opened.

6. 3. The apparatus of claim 2, wherein at the end of the first time period, the first valve in the first flow path is closed at a predetermined rate and the second valve in the second flow path is opened at a substantially corresponding rate.

7. The apparatus of claim 1 , wherein the first flow path is configured to open at a predetermined time relative to a first position of the substrate within the processing chamber.

8. The apparatus of claim 7 , whereby the second flow path is configured to be open at a predetermined time relative to a second position of the substrate within the processing chamber.

9. The apparatus of claim 8 , whereby, at the first position, the substrate is introduced into the chamber.

10. The apparatus of claim 8 whereby the second position is a processing position.

11. 1. A fluid box assembly comprising: A controller; A first box, the first box comprising: an IPA container for storing liquid IPA, the liquid IPA being pressurized for delivery via a first fluid path to a first liquid mass flow controller (LMFC) associated with a first vaporizer for converting the fluid IPA into IPA vapor; a first mass flow controller (MFC) associated with the carrier gas; a first mixing unit for mixing IPA gas with the carrier gas to create a predetermined mixture for delivery to a first processing chamber; a first box having a second box, the second box comprising: a second LMFC associated with a second vaporizer for converting the fluid IPA into IPA vapor; a second MFC controller associated with the carrier gas; a second mixing unit for mixing the IPA vapor with the carrier gas to create the predetermined mixture for delivery to a second processing chamber; a second box having a second fluid path between the IPA container and the second box; A fluid box assembly comprising:

12. 12. The fluid box assembly of claim 11, wherein the controller controls the first and second LMFCs, the first and second MFCs, and the first and second vaporizers.

13. The fluid box assembly of claim 11 , wherein the first box and the second box are housed in an enclosure.

14. a third box, the third box comprising: a third LMFC associated with a third vaporizer for converting the fluid IPA into IPA vapor; a third MFC associated with the carrier gas; and a third mixing unit for mixing the IPA vapor with the carrier gas to create the predetermined mixture for delivery to a third processing chamber; a third box having a third fluid path between the IPA container and the second box; The fluid box assembly of claim 11 further comprising:

15. The fluid box assembly of claim 14 , wherein the second fluid path terminates at the second LMFC and the third fluid path terminates at the third LMFC.

16. 1. A fluid box assembly comprising: A controller; A first box, the first box comprising: an IPA container for storing liquid IPA, the liquid IPA being pressurized for delivery via a first fluid path to a first liquid mass flow controller (LMFC) associated with a first vaporizer for converting the fluid IPA into IPA vapor; a first mass flow controller (MFC) associated with the carrier gas; a first mixing unit for mixing IPA gas with the carrier gas to create a predetermined mixture for delivery to a first processing chamber; a first box having a second box, the second box comprising: a second LMFC associated with a second vaporizer for converting the fluid IPA into IPA vapor; a second MFC controller associated with the carrier gas; a second mixing unit for mixing IPA vapor with the carrier gas to create the predetermined mixture for delivery to a second processing chamber; a second box having a second fluid path between the IPA container and the second LMFC in the second box, wherein liquid IPA is pressurized for delivery from the IPA container to the second LMFC; a first drain circuit associated with the first processing chamber, a first flow path having a first valve between the first mixing unit and a drain; a second flow path having a second valve between the first mixing unit and the first processing chamber, whereby the first flow path can be opened until the predetermined mixture is reached, and then the second flow path can be opened to allow the predetermined mixture to be delivered to the first chamber; a first drain circuit including: a second drain circuit associated with the second processing chamber, a first flow path having a first valve between the second mixing unit and a drain; a second flow path having a second valve between the second mixing unit and the second processing chamber, whereby the first flow path can be opened until the predetermined mixture is reached, and then the second flow path can be opened to allow the predetermined mixture to be delivered to the second chamber; a second drain circuit including: A fluid box assembly comprising:

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