Wafer cleaning method and equipment

Abstract

The present invention relates to a method for processing a wafer surface with multiple liquids, comprising rotating the surface of the wafer and releasing different liquid streams from separate outlets onto the rotating surface in a sequence, wherein the release of adjacent liquid streams in the sequence overlaps during a transition phase, and wherein during the transition phase, the liquid streams merge after leaving the outlets to form a merged liquid stream before impacting the rotating surface. The present invention also provides a liquid distribution device incorporating a housing holding two or more liquid delivery tubes, wherein the outlets of the tubes are bent inwardly toward each other so that, in use, the liquid streams delivered from the outlets of the two or more liquid delivery tubes merge to form a merged liquid stream.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for cleaning wafers, particularly semiconductor wafers, for subsequent use in electronic devices. Background Art

[0002] The performance of semiconductor wafers is highly sensitive to contamination that occurs on the wafer surface, and therefore considerable effort is made to limit potential sources of contamination and remove contamination whenever it occurs. As part of this process, wafers are subjected to cleaning steps during and after the process to remove residual contamination.

[0003] One of the cleaning processes commonly encountered in wafer cleaning is the so-called "RCA cleaning," which is performed prior to the high-temperature processing steps of silicon wafers. This cleaning involves the following multi-step sequence:

[0004] (1) Removal of organic and particulate contaminants, typically using a mixture of deionized water, ammonia, and hydrogen peroxide;

[0005] (2) optional removal of the thin oxide layer produced by step (1), typically using hydrofluoric acid;

[0006] (3) Removal of ionic contaminants, typically using a mixture of deionized water, hydrochloric acid, and hydrogen peroxide; and

[0007] (4) Rinse and dry the wafer.

[0008] The simplest way to perform RCA cleaning, as well as other wafer cleaning methods, is to immerse the wafer in a cleaning tank containing a cleaning liquid and optionally mechanically clean the substrate with a brush after removal from the tank. However, this method is not ideal because contaminants that enter the cleaning tank or adhere to the brush can be redeposited on the wafer. Therefore, in order for the cleaning method to be practical, it is necessary to ensure that the cleaning tank itself does not contribute a significant level of contamination (for example, in the RCA cleaning method described above, it is impossible to use borosilicate glassware because impurities can leach out and cause contamination) and to use electronic-grade (or "CMOS"-grade) cleaning liquids.

[0009] To address the shortcomings of simple immersion of the substrate, it is known to subject the wafer to spin rinsing. In this technique, a cleaning liquid is sprayed onto the rotating wafer (which is held on a rotating block), causing the cleaning liquid to flow over the edge of the wafer due to centrifugal force before being dispersed from the sides. Advantageously, this flow of cleaning liquid helps minimize the redeposition of contaminants removed from the wafer surface, as well as the deposition of contaminants from the cleaning liquid itself, in situations where tank cleaning is not possible.

[0010] An example of a rotary cleaning apparatus suitable for delivering a sequence of fluids is discussed in US 6,383,311. In this system, the authors discuss a system having multiple dispensing arms linked to a suspension, wherein the arms can all rotate independently of one another about the same axis. In this manner, each arm can be rotated to an "active" position above a wafer to dispense a fluid, and then rotated away from the wafer to a "rest" position to prevent residual fluid from dripping onto the wafer. To dispense multiple fluids, the apparatus rotates a first dispensing arm above the wafer and delivers a fluid, rotates the first dispensing arm away from the wafer to a rest position, and then rotates a second dispensing arm above the wafer and delivers another fluid.

[0011] However, the present inventors have discovered that using spin cleaning equipment to perform multi-step cleaning processes such as RCA cleaning can be problematic. In particular, centrifugal forces can cause rapid drying of the wafers between process steps, which can lead to the deposition of contaminants from the various cleaning liquids. Furthermore, to perform a full RCA clean, several different hazardous chemicals must be used, complicating the design of equipment suitable for safely delivering all the different components.

[0012] Therefore, a need remains to develop improved methods and apparatus for safely and effectively cleaning wafers. Summary of the Invention

[0013] In light of the shortcomings of the prior art described above, the present inventors have discovered that contamination following multi-step cleaning processes can be minimized by implementing a spin cleaning process in which wafer drying between cleaning steps is limited or avoided. In light of this discovery, the present inventors first sought to develop equipment that allows for the direct delivery of a series of different cleaning liquids to the wafer surface, with the delivery of successive cleaning liquids in the sequence occurring simultaneously with short "switch" or "transition" periods to maintain continuous wafer wetting. However, it was discovered that when the different liquid streams are delivered simultaneously to the rotating surface, waves are generated between the different impact zones on the wafer, resulting in significant splashing. Such splashing is highly undesirable for several reasons. First, because it disrupts the flow of liquid across the entire wafer surface, it results in wasted cleaning liquid—a significant consideration when using expensive, high-purity ("CMOS"-grade) liquids. Second, splashing can lead to uneven treatment levels across the entire wafer surface. Third, splashing can pose safety concerns due to the corrosive nature of many chemicals typically encountered in cleaning processes. Fourth, cleaning liquid can become deposited on equipment (e.g., nozzles), leading to cross-contamination between steps and potentially necessitating intermittent cleaning of the nozzle equipment. In light of these issues, the inventors sought to develop a safer and more efficient continuous wet wafer cleaning method, leading to the present invention.

[0014] In particular, in a first aspect, the present invention provides a method for treating a wafer surface with multiple liquids, comprising: rotating the surface of the wafer; and releasing different liquid streams from separate outlets onto the rotating surface in a sequence, wherein the release of consecutive liquid streams in the sequence overlaps during a transition phase, and wherein during the transition phase, the liquid streams merge after leaving the outlets to form a merged liquid stream before impacting the rotating surface. By this method, the inventors of the present case have found that the wafer can be continuously maintained wet during the cleaning process while minimizing or eliminating undesirable splashing. In particular, allowing the liquid streams to merge into a single merged liquid stream before impacting the rotating surface means that the liquid systems are delivered to the same point on the wafer, thereby avoiding the formation of problematic waves that occur when liquid streams are delivered to different parts of the surface during the cleaning process. In this regard, a reader with ordinary skill will understand that the term "cleaning" as used in this specification is intended to be used to describe the cleaning process. Figure 1 Generally refers to the step of releasing liquid onto the surface of the wafer, without being limited to a specific purpose - for example, "cleaning" can be to clean the wafer to remove contaminants, or to perform some chemical modification of the wafer itself.

[0015] In the methods of the present invention, multi-step processes can be divided into a "processing" phase and an intervening "transition" phase, alternatively referred to as a processing period and a transition period. A "processing" phase corresponds to a period during which a particular processing step is performed. A "transition" phase corresponds to a transition period between adjacent processing steps in a processing sequence (i.e., between processing phases), during which the two processing steps are performed substantially simultaneously. For example, for a multi-step cleaning process comprising steps A and B, each delivering liquid X and liquid Y, the process has three phases: (i) a processing phase, in which only liquid X is delivered; (ii) a transition phase, in which the delivery of X and Y occurs simultaneously; and (iii) a processing phase, in which only liquid Y is delivered.

[0016] The duration of the transition phase will depend on the specific protocol to be implemented, but may be, for example, at least 0.1 seconds, at least 0.2 seconds, at least 0.3 seconds, at least 0.4 seconds, at least 0.5 seconds, at least 1 second, or at least 2 seconds. An upper limit for the duration of the transition phase may be, for example, 0.5 seconds, 1 second, 1.5 seconds, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 10 seconds, 20 seconds, or 30 seconds. In methods involving more than one transition period, the transition periods may have the same duration, or may have different durations.

[0017] The duration of the transition phase as a percentage of the preceding process phase may be, for example, at least 0.01%, at least 0.1%, at least 0.5%, at least 1%, at least 2%, or at least 5%. An upper limit for the duration of the transition phase as a percentage of the preceding process phase may be, for example, 40%, 30%, 20%, 10%, or 5%; for example, the percentage may be in the range of 0.01 to 40%, 0.1 to 30%, 0.5 to 20%, or 1 to 5%. In methods involving more than one transition period, the percentage durations of the transition phases (collectively or individually) may be relative to the above ranges.

[0018] Suitably, the outlets are curved toward each other to form the combined liquid stream. The angles of the outlets are such that the paths of the emitted streams intersect at a position "P" above the surface of the wafer. Advantageously, arranging the outlets to combine the liquid streams into a combined liquid stream above the wafer surface means that a single liquid "column" impinges on the wafer, thereby avoiding the formation of waves that would otherwise occur if the simultaneously delivered liquid streams did not combine or combined only at the wafer surface (i.e., at P≈0).

[0019] The appropriate angle will depend on the flow rate of the liquid and the height of the outlets above the wafer surface. The angle may also depend on the type of chemicals being delivered—for example, if chemicals from different adjacent steps react undesirably with each other, it may be advantageous to have position P close to the wafer surface to limit the time during which the reaction can occur.

[0020] This angle can be defined in two different ways: as a "pencil flow path intersection" angle, or as a "true flow path intersection" angle.

[0021] The "pencil path intersection" angle (θS) of two outlets is the angle defined by two straight lines drawn from the two outlets, assuming the trajectory of the liquid stream remains unchanged after ejection. Therefore, the pencil path angle is independent of the flow rate (which will be constant for a particular setup) and neglects the effects of gravity. The flow path is taken as the line corresponding to the center point of the pencil path.

[0022] The "true flow path intersection" angle (θT) of two outlets is the angle at which the flow paths of the liquid streams actually intersect in use. This flow path therefore takes into account the true trajectory of the streams, taking into account the effects of flow rate and gravity. The flow path angle between two liquid streams is determined by: (i) measuring the trajectory of the first liquid stream in the absence of the second liquid stream (i.e., with the second liquid stream stopped or diverted); (ii) measuring the trajectory of the second liquid stream in the absence of the first liquid stream; and (iii) determining the point where the trajectories intersect and measuring the maximum angle between these lines near that point. The flow paths are considered to be lines corresponding to the center point of the streams. If necessary, the trajectories can be modeled using quadratic equations to assist in the calculation of the intersection point.

[0023] The pendant flow path intersection angle and the true flow path intersection angle can be the same, especially in the case of low angles and high flow rates. However, in the case of higher angles and lower flow rates, differences will occur in the two measurements.

[0024] Typically, the intersecting angle of the pen paths is less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, or less than or equal to 25°. The intersecting angle of the pen paths may be at least 5°, at least 10°, at least 15°, or at least 20°. For example, the intersecting angle of the pen paths may be 10° to 40°, 15° to 35°, or 15° to 30°.

[0025] Generally, the true flow path angle between the combined liquid streams is less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, or less than or equal to 25°. The true flow path angle may be at least 5°, at least 10°, at least 15°, or at least 20°. For example, the true flow path angle between the combined liquid streams may be 10° to 40°, 15° to 35°, or 15° to 30°.

[0026] Preferably, the liquid stream is released downwardly onto the rotating wafer surface (ie, in the general direction of gravity).

[0027] Generally speaking, as determined according to the "pendulum flow path" or "true flow path" methods proposed above, the angle between a single flow path and the axis of rotation of the wafer is less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, or less than or equal to 25°, and is generally at least 5°, at least 10°, at least 15°, or at least 20° (for example, 10° to 40°, 15° to 35°, or 15° to 30°).

[0028] The height at which the liquid streams merge during the present method is not particularly limited. The term "height" is used to generally refer to the distance between the wafer and the point at which the liquid streams merge, without intending to limit the process to a particular orientation (vertical / horizontal). However, in general, the liquid streams are released downward onto a rotating surface, in which case "height" has its standard meaning—that is, the vertical distance between the intersection point of the liquid streams and the wafer (where the intersection point is above the wafer).

[0029] This height can be defined in two different ways as the "pendulum intersection height" (HS) or the "true flow intersection height" (HT). The calculation of these heights follows the same method outlined above for the pendulum intersection angle and the true flow intersection angle, except that instead of measuring the angle at the point where the tracks intersect, the distance is measured to the surface of the wafer. As mentioned above, the height at the point where the liquid streams merge is not particularly limited. This is in contrast to EP 0 618 611, in which the height is a critical parameter because it determines the heat of the cleaning mixture at the impact point. However, it is generally preferred that the intersection height is relatively small so that the impact area does not shift significantly when switching from the processing phase to the transition phase.

[0030] Generally, the pen-line diameters intersect at a height of at least 2 mm, at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, or at least 25 mm. The pen-line diameters intersect at a height of 100 mm or less, 90 mm or less, 80 mm or less, 70 mm or less, 60 mm or less, 50 mm or less, 40 mm or less, or 30 mm or less. For example, the pen-line diameters intersect at a height of 2 mm to 100 mm, 5 mm to 50 mm, or 10 mm to 40 mm.

[0031] Generally, the true intersection height of the combined liquid streams is at least 2 mm, at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, or at least 25 mm above the wafer surface. The true intersection height may be 100 mm or less, 90 mm or less, 80 mm or less, 70 mm or less, 60 mm or less, 50 mm or less, 40 mm or less, or 30 mm or less. For example, the true intersection height of the combined liquid streams may be between 2 mm and 100 mm, between 5 mm and 50 mm, or between 10 mm and 30 mm above the wafer surface.

[0032] The combined liquid streams impact the wafer and subsequently flow across the surface of the wafer due to the centrifugal force generated by the rotation of the wafer. The combined liquid streams can be caused to impact any point on the wafer. However, typically, the combined liquid streams are released to impact the rotational axis of the rotating wafer. Generally, this corresponds to the center of the wafer, about which the wafer rotates. In this way, the liquid can pass through the entire wafer and will be subjected to the maximum centrifugal force. As mentioned above, the method is generally implemented by releasing the liquid downward onto the wafer rotating about an axis aligned with the direction of gravity. In such an example, in order to achieve the delivery of the liquid to impact the rotational axis of the rotating wafer, the intersection point of the liquid streams is located at or close to the rotational axis of the wafer (generally above the center of the wafer).

[0033] The liquid in the method of the present invention is delivered to the wafer in the form of a stream / spray. In other words, the liquid flows in a specific direction as a "column" rather than being delivered in the form of a dispersed mist or spray that is then deposited on the wafer.

[0034] The flow rate of liquid onto the wafer will depend on the particular application, but may be, for example, at least 0.5 liters per minute, at least 1 liter per minute, at least 1.5 liters per minute, or at least 2 liters per minute.

[0035] The rotation speed of the wafer can be, for example, at least 60 rpm, at least 100 rpm, at least 200 rpm, or at least 300 rpm.

[0036] The method of the present invention is used to treat the surface of a wafer (alternatively referred to as a "substrate") and is particularly well-suited for the treatment of semiconductor wafers, where a complete and reliable cleaning solution is crucial. By "wafer" we mean a piece or block of (generally thin) material suitable for rotation at the high speeds necessary for effective spin cleaning. For example, the method can be applied to the treatment of silicon wafers.

[0037] Sequential delivery solution

[0038] The method of the present invention can be used to perform a large number of possible multi-step surface treatments.

[0039] Generally speaking, a multi-step surface treatment will involve an active step (in which one or more active chemicals are delivered to the wafer surface to react with the wafer and / or components on the wafer surface) and a rinse step (in which one or more chemicals are delivered to rinse the wafer surface without reacting significantly or at all with the wafer and / or components on the wafer surface). Generally speaking, the rinse step uses water, preferably purified water such as deionized water. In this way, the chance of interaction between chemicals associated with different active steps is reduced or eliminated.

[0040] In certain embodiments, the multi-step surface treatment corresponds to the implementation of RCA cleaning as described in detail in the previous technical section above, with optional rinse steps between each active step. For example, the method can involve treating the surface of a semiconductor wafer, wherein the sequence of steps involves a cycle of one or more of the following steps:

[0041] (A) optional rinsing step;

[0042] (B) steps for removing organic and / or particulate contaminants;

[0043] (C) an optional rinsing step;

[0044] (D) an optional step for removing the surface oxide layer;

[0045] (E) an optional rinsing step;

[0046] (F) a step for removing ionic contaminants; and

[0047] (G) an optional rinsing step;

[0048] Or, for example, the above steps may be rearranged in the following order: (A), (F), (G), (B), (C), (D), (E).

[0049] For example, the method may involve a cycle of one or more of the following steps:

[0050] (A) optionally, rinsing the surface with water;

[0051] (B) treating the surface with a mixture of ammonia and hydrogen peroxide;

[0052] (C) optionally, rinsing the surface with water;

[0053] (D) optionally, treating the surface with hydrofluoric acid;

[0054] (E) optionally, rinsing the surface with water;

[0055] (F) treating the surface with a mixture of an acid (such as sulfuric acid or hydrochloric acid) and hydrogen peroxide; and

[0056] (G) optionally, rinsing the surface with water;

[0057] Or, for example, the above steps may be rearranged in the following order: (A), (F), (G), (B), (C), (D), (E).

[0058] Preferably, the sequence includes at least one of the rinsing steps (C), (E), and (G), and most preferably all of the rinsing steps (C), (E), and (G). Inclusion of the rinsing steps helps to avoid reactions between the different reagents used in steps (B), (D), and (F).

[0059] To implement the above process, the different liquid components are delivered from separate outlets using the method according to the present invention. In the steps involving the use of a combination of different chemicals (i.e., steps (B) and (F)), the chemicals can be pre-mixed and delivered from the same outlet.

[0060] In one embodiment, the method involves a cycle of one or more of the following steps:

[0061] (A) optionally, rinsing the surface with water released from the first outlet;

[0062] (B) treating the surface with a solution released from the second outlet, the solution comprising a mixture of ammonia and hydrogen peroxide;

[0063] (C) optionally, rinsing the surface with water, preferably released from the first outlet;

[0064] (D) optionally, treating the surface with hydrofluoric acid;

[0065] (E) optionally, rinsing the surface with water, preferably released from the first outlet;

[0066] (F) treating the surface with a solution released from a third outlet, the solution comprising a mixture of an acid (e.g., sulfuric acid or hydrochloric acid) and hydrogen peroxide; and

[0067] (G) optionally, rinsing the surface with water, preferably released from the first outlet;

[0068] or a variation of the above steps in the order of (A), (F), (G), (B), (C), (D), (E);

[0069] Each cycle of the sequence includes at least one of the rinsing steps (A), (C), (E), and (G).

[0070] Preferably, the sequence is selected from one of the following:

[0071] (B), (C), (F);

[0072] (B), (C), (F), (G);

[0073] (B), (C), (D), (E), (F);

[0074] (B), (C), (D), (E), (F), (G).

[0075] Preferably, all rinse steps are performed using water released from the same outlet, as this limits the number of outlets required to carry out the method of the invention.

[0076] cleaning equipment

[0077] The present invention also provides a cleaning apparatus for performing the method of the present invention. More particularly, in a second aspect, the present invention provides a cleaning apparatus for treating a substrate with multiple liquids, comprising:

[0078] a clean chamber; a wafer support in the clean chamber;

[0079] means for rotating the wafer support; and

[0080] A liquid dispensing device comprises a housing holding two or more liquid delivery tubes, wherein the outlets of the tubes are bent inwardly toward each other so that in use the liquid flows delivered from the outlets of the two or more liquid delivery tubes merge to form a combined liquid flow.

[0081] In a third aspect, the present invention provides a liquid dispensing device suitable for use in the cleaning apparatus of the second aspect. In particular, this aspect provides a housing for holding two or more liquid delivery tubes, wherein the outlets of the tubes are bent inwardly toward each other so that, in use, the liquid flows delivered from the outlets of the two or more liquid delivery tubes merge to form a combined liquid flow.

[0082] Optional and preferred features of the liquid dispensing device will now be described.It will be understood that the options and preferences set out below apply equally in relation to the first aspect of the invention.

[0083] Suitably, the housing of the liquid dispensing device helps to hold and guide the liquid delivery tubes into their inwardly curved configuration. To this end, the housing may include channels to receive the liquid delivery tubes, wherein the channels bend the tubes into their inwardly curved configuration. For example, in a particularly advantageous configuration, the liquid dispensing device comprises:

[0084] a housing defining an opening of the interior chamber at the outlet port;

[0085] a spacer positioned within the interior chamber of the housing; and

[0086] Two or more liquid delivery pipes passing through the partition in the inner chamber of the housing and extending to the outlet port;

[0087] The two or more liquid-carrying tubes are bent around the spacer so that their outlets curve inwardly toward each other, so that, during use, the liquid flows from the outlets of the two or more liquid-carrying tubes merge to form a combined liquid flow. In this arrangement, the two or more liquid-carrying tubes can pass between the spacer and the wall of the inner chamber of the housing, along / around the spacer. In this way, for a given housing, the width of the spacer and its position relative to the housing's outlet port can be used to determine the angle of the outlets of the tubes.

[0088] From the above, it is clear that the "spacer" is a component that guides the tubes to be set at the desired angle. Preferably, the spacer is a separate component. Although the spacer is not indispensable in all embodiments, the spacer can be a separate component fixed to the housing by a suitable fixing method to limit or prevent relative movement of the housing and the spacer. For example, the spacer can be fixed to the housing by screws, pins, or plugs. In such an embodiment, the housing may have through holes that are aligned with corresponding holes in the spacer to receive the screws, pins, or plugs. Preferably, the spacer is a replaceable / removable spacer that can be replaced by other (optionally different) spacers. This is particularly advantageous in embodiments where the liquid dispensing device can be combined with different spacers, because different spacers can be used to achieve different settings using the same housing.

[0089] Generally speaking, the housing encloses the liquid conveying tubes and helps support the tubes. The housing can be a tubular housing, such as a cylindrical tubular housing (although other cross-sections are possible). In this way, the liquid conveying tubes can be inserted / passed through the tubular housing.

[0090] In one embodiment, the housing and the spacer hold the two or more liquid-carrying tubes in place, and the housing's internal chamber narrows at or toward the outlet port to bend the liquid-carrying tubes around the spacer and thereby orient the outlets of the tubes in the inwardly curved configuration. In this embodiment, the housing's internal chamber may taper inward to produce the narrowing at or toward the outlet port. In such a case, the spacer may be configured to complement the taper of the housing, extending within the tapered portion of the housing. This configuration provides a simple and effective method for providing the device with the tubes formed in the desired configuration.

[0091] To aid in positioning the liquid delivery tubes, the spacer preferably has one or more channels / recesses adapted to accommodate the liquid delivery tubes. Optionally, the housing has one or more channels for accommodating the liquid delivery tubes. Where both the spacer and the housing include such channels, the channels can be complementary, forming a closed conduit that completely surrounds the tubes when the housing and spacer are assembled in the liquid dispensing device (e.g., by providing a half-pipe recess in the housing and a complementary half-pipe recess in the spacer for each liquid delivery tube). Optionally, channels can be provided in the spacer if the housing does not already have corresponding channels. This latter embodiment is particularly advantageous when the spacer is interchangeable within the housing, as it allows switching between different spacers having different numbers and / or arrangements of channels to implement different solutions without interference from the channels in the housing (which might otherwise interfere with proper placement when switching between different spacers). Preferably, the channels in the spacer are open channels (ie, they do not completely surround the fluid delivery tubes) to facilitate insertion and removal of the fluid delivery tubes.

[0092] In one embodiment, the liquid dispensing device has two liquid delivery tubes, which are located in two (preferably open) channels provided in / on the partition. These channels can pass through along opposite sides of the partition to appropriately separate / isolate the tubes.

[0093] In another embodiment, the liquid dispensing device has three liquid delivery tubes, which are located in three (preferably open) channels provided in / on the spacer.

[0094] In a particularly advantageous embodiment, the housing comprises a main body and a removable cap, wherein the removable cap comprises the outlet port. In this manner, the removable cap can be removed to allow adjustment of the spacer and the liquid delivery tube. In such an embodiment, the spacer is preferably removable when the removable cap is removed. In this way, the spacer can be directly replaced for maintenance reasons or to replace it with a different spacer suitable for a different solution. The removable cap can be connected via any suitable connection method, such as a screw fit (threaded connection), a friction fit (push fit), or a snap fit. The removable cap can be attached to the main body of the housing and / or the spacer through the connection. Suitably, the spacer is a separate component that holds / clamps the spacer in place when the removable cap is attached to the liquid dispensing device, but is freely removable when the removable cap is removed.

[0095] In a preferred arrangement, the liquid dispensing device comprises:

[0096] a housing defining an interior chamber opening at the outlet port, the housing having a body and a removable cap connected by a friction fit or screw fit engagement, wherein the removable cap contains the outlet port;

[0097] a spacer positioned within the interior chamber of the housing; and

[0098] Two or more liquid delivery pipes passing between the partition and the wall of the inner chamber of the housing, around the partition, and extending to the outlet port;

[0099] The spacer has channels in its outer surface that accommodate the two or more liquid-carrying tubes, and the inner surface of the removable cap does not include channels for accommodating the liquid-carrying tubes. Advantageously, in this embodiment, the removable cap is held in place by a secure screw fit or friction connection, but the lack of tube support channels in the cap means that the cap can be rotated to allow removal without significantly rotating the spacer and liquid-carrying tubes. This means that even without a fixed mounting of the spacer / tubes relative to the main body of the housing, twisting of the tubes during cap removal can be minimized or eliminated. This directly avoids deformation or tangling of the tubes, which could damage the liquid-carrying tubes and also force the spacer upward into the housing, making removal more difficult. Such an embodiment also allows for simple replacement of the liquid-carrying tubes. In particular, removal of the removable cap offsets the clamping force on the liquid-carrying tubes, allowing the liquid-carrying tubes to be pulled (upward or downward) out of the housing.

[0100] In the above particularly preferred arrangement, the main body can be a tubular housing (that is, a hollow tube). In this way, the liquid delivery tubes can be easily pushed / inserted into the hollow tube and fixed in place by the detachable cap.

[0101] In a particularly preferred arrangement, the spacer includes a stop surface that abuts a corresponding stop surface of the housing (e.g., within the housing). The complementary stop surface can be used to assist in positioning the spacer within the housing and prevent the spacer from being pushed too far into the housing. In one embodiment, the stop surface of the spacer is provided as a collar portion.

[0102] In a particularly preferred embodiment, the liquid dispensing device comprises:

[0103] a housing defining an inner chamber opening at the outlet port, the housing having a body and a removable cap, wherein the removable cap includes the outlet port;

[0104] a spacer positioned within the interior chamber of the housing, the spacer having a collar portion and an inwardly tapered portion; and

[0105] Two or more liquid delivery pipes passing between the partition and the wall of the inner chamber of the housing, around the partition, and extending to the outlet port;

[0106] The spacer has a channel in its outer surface that accommodates the two or more liquid-carrying tubes, and the liquid-carrying tubes are bent into their curved configuration at their lower, inwardly tapered portions, and the collar portion of the spacer abuts the lower portion of the body (the "outlet" portion of the body), and the removable cap is held in place on the collar of the spacer (e.g., by a friction fit with the collar). The spacer is optionally secured to the housing by a suitable securing means. Advantageously, this arrangement provides a particularly simple and reliable assembly device. In particular, the device can be assembled by inserting the liquid-carrying tubes through the body of the housing, placing the tubes into the channels provided in the spacer, pushing the spacer into position in the body of the housing until the collar portion of the spacer contacts the outlet of the body of the housing, and finally pushing / locking the removable cap into position on the collar of the spacer, so that the tubes adopt the desired inwardly curved configuration.

[0107] Preferably, the liquid delivery tubes are separate parts held within the housing (as opposed to being integral parts of the housing). The tubes may be plastic tubes, for example fluorine-based tubes, such as perfluoroalkoxy tubes.

[0108] The outlet through which the liquid is delivered may be of any suitable form for delivering a stream / spray of liquid at a suitable flow rate. The outlet may alternatively be referred to as a "nozzle." The outlet may simply be the open end of a tube that delivers the liquid. Alternatively, the outlet may be a separate nozzle that directs the flow of the liquid. The outlet may have the same internal diameter as the conduit through which the liquid is delivered, or may have a somewhat different shape—for example, with a smaller cross-section to increase the flow rate. The internal diameter of the outlet will depend on the specific flow characteristics desired for a particular application, but may be, for example, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, or at least 10 mm.

[0109] Preferably, the outlets of two or more liquid delivery tubes fall within the range given above for the “direction intersection angle”, such as between 10° and 40°, between 15° and 35°, or between 20° and 30°.

[0110] In the cleaning apparatus of the present invention, the openings are preferably located at a height above the wafer according to the range given above for the "direction intersection height." For example, the direction intersection height may be between 2 mm and 100 mm, between 5 mm and 50 mm, or between 10 mm and 40 mm.

[0111] The wafer support may be a rotatable platform with a suitable wafer gripping device. The wafer may be held by a rotatable platform, such as a vacuum chuck (or clamp), an edge gripping chuck, or a Bernoulli chuck (or clamp). The cleaning chamber of the cleaning apparatus of the present invention may include an annular liquid collector surrounding the rotating platform and wafer to collect liquid flowing from the wafer surface.

[0112] spacers

[0113] In a further aspect, the present invention provides a spacer for use in the above-mentioned apparatus and liquid dispensing device. In a particularly preferred embodiment, the spacer comprises:

[0114] an upper portion having fixing means for fixing the spacer to the frame;

[0115] a lower portion having an inwardly tapered shape (e.g., a frustoconical portion);

[0116] a collar portion, between the upper and lower portions, having a width greater than the upper and lower portions to assist in positioning the spacer within the housing;

[0117] The outer surface of the spacer includes two or more channels for receiving liquid delivery tubes, and the lower portion helps to bend the liquid delivery tubes into a desired configuration.

[0118] Parts Set

[0119] In a further aspect, the present invention provides a kit of parts for assembling a liquid dispensing device according to the present invention. The kit comprises the housing, one or more spacers for placement within the housing body, and optionally two or more liquid delivery tubes (although the latter can be supplied separately). Preferably, the kit comprises at least two spacers having different numbers of channels for accommodating the liquid delivery tubes. For example, the kit may comprise a first spacer having two channels and a second spacer having three channels. The components of the kit may have any of the preferred and optional features briefly described above. In particular, the housing may be a multi-part construction comprising a main body and a removable cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0120] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0121] Figure 1 A perspective view showing a liquid dispensing device according to the present invention;

[0122] Figure 2A and 2B for Figure 1sectional views of a liquid dispensing device, wherein the two figures show views orthogonal to each other;

[0123] Figure 3A 、 3B 3C is a schematic diagram showing a liquid delivery sequence according to the method of the present invention;

[0124] Figure 4 is a schematic diagram of delivery from a liquid dispensing device according to the present invention, illustrating the deviation between the pendant flow path intersection angle and the actual flow path intersection angle;

[0125] Figure 5 A flow chart showing an embodiment of RCA cleaning according to the method of the present invention;

[0126] Figure 6A and 6B is a perspective view of the top and bottom of a three-tube spacer;

[0127] Figure 7 is a schematic diagram of the bottom of a double-tube spacer;

[0128] Figure 8A 、 8B 8C show the detachable cap of the liquid dispensing device of the present invention, and are respectively a top perspective view, a bottom perspective view, and a cross-sectional view. DETAILED DESCRIPTION

[0129] Figure 1 A liquid dispensing device 1 according to the present invention is shown. The device incorporates a tubular housing 2 having a main portion 3 and a removable cap 4. The housing comprises spacers 5 (shown in subsequent figures) fixed in place by screws 6, and three PFA tubes 7 (shown in subsequent figures) connected to a liquid reservoir (not shown).

[0130] Figure 2A and 2B The inner edge of the shell 2 Figure 1 The housing encloses the spacer 5 and the tube 7, the latter protruding at an angle through the open end of the removable cap 4 due to the inward taper provided on the inner surface of the removable cap 4 and the corresponding tapered outer surface of the spacer 5.

[0131] Figures 3A-3C Shown in Figure 1-2B The operation of the device. Figure 3A In the first rinsing step, a flow of liquid 10 is delivered from a first pipe 11 onto a rotating wafer 12. Figure 3BIn the transition period, the device enters a transition period, in which a stream of liquid 10' is delivered from the second tube 11' while the delivery of the first liquid 10 from the first tube 11 is maintained. The liquids 10 and 10' form a single stream that impacts the rotating wafer at the center point of the rotating wafer. Finally, in Figure 3C In this embodiment, the flow of liquid 10' is continued while the flow of liquid 10 is stopped, to achieve a second cleaning step.

[0132] Figure 3B Dashed lines are shown indicating the theoretical flow paths of liquids 10 and 10' assuming the liquids are ejected from tubes 11 and 11' along straight paths. The point "P" where the flow paths intersect corresponds to the height at which the linear paths intersect, in this example 10 mm above the surface of the rotating wafer 12. The linear path intersection angle, denoted as θS, is 26°. In this example, since the liquid flow rate and the proximity to the surface of the rotating wafer 12 mean that there is no significant deviation from straight flow, the actual flow path intersection angle θT is approximately the same as that calculated based on straight flow. This is consistent with the Figure 4 This contrasts with the situation shown in , where the combination of lower flow rate and steeper nozzle angle means that the vertical flow path angle θS is greater than the true flow path angle θT, and similarly, the true intersection height is lower than that predicted based on the vertical flow path height.

[0133] Figure 5 shows the use of the Figure 1-4 An embodiment of RCA cleaning using a three-tube liquid dispensing apparatus, wherein deionized water is dispensed from a first tube, an aqueous mixture of ammonia and hydrogen peroxide in deionized water is dispensed from a second tube, and an aqueous mixture of sulfuric acid and hydrogen peroxide in deionized water is dispensed from a third tube. The shaded area indicates the transition phase, during which liquids are delivered simultaneously from the associated tubes.

[0134] Figure 6A and 6B Show in more detail Figure 2A 、 Figure 2B The spacer assembly 20 includes three channels 21 for receiving liquid delivery tubes (not shown). The spacer includes a collar 22 having a diameter corresponding to the inner cavity of the housing to stably place the spacer horizontally in the housing. The collar is provided with threads (not shown) on its outer surface to match corresponding threads in the housing. The collar also has an upper connecting surface 23, which abuts the outlet area of ​​the tubular portion 3 of the housing in use (see Figure 2A 、 Figure 2B) to position the spacer vertically within the frame and prevent the spacer from being pushed too far into the frame; and a lower connecting surface that connects to a corresponding stop surface in the removable cap. Below the collar, there is a tapered portion 24 that fits within a corresponding inwardly tapered chamber of the frame, which bends the tube into place. Above the collar, a scalloped portion 25 (i.e., the "empty" area between the channels) helps minimize friction during insertion of the spacer into the frame and generally reduces the amount of material used to make the spacer. The spacer 20 also includes an anchor portion 26 having a screw hole 27 that can be used to secure the spacer to the frame using screws, such as Figure 2A As shown in . Figure 7 Instead of the spacer 30 , it has only two channels 31 for receiving liquid delivery tubes (not shown), the other features being the same as those shown for the spacer 20 .

[0135] Figures 8A-8C Features of the removable cap 40 are shown in greater detail. Figure 8A is a cross-sectional view of a cap 40. The cap includes an upper chamber 41 having a diameter corresponding to the collar 22 of the spacer 20. The surface of the upper chamber includes threads (not shown) that screw onto corresponding threads provided on the collar of the spacer to hold the cap in place. The cap also has a lower chamber 42 having a frustoconical shape terminating in an open outlet port 43. The lower chamber has a cone angle of approximately 22°, which guides the liquid delivery tubes into their inward bending position, where they engage the tapered portion of the spacer. Between the upper and lower chambers 41, 42 is an intermediate chamber 44 having a larger diameter to allow the plastic liquid delivery tubes to bulge outward when they are bent into position and to prevent friction of the tubes. Figure 8B and 8C A view of the cap looking into the upper chamber 41 and the lower chamber 42 is shown, respectively, depicting a narrower section at the outlet port 43 .

[0136] The features disclosed in the foregoing, in the following patent applications, or in the accompanying drawings, expressed in an appropriate manner, in their specific form, or in terms of means for performing the disclosed functions, or methods or procedures for obtaining the disclosed results, may be described individually or in any combination of these features to implement the invention in its various forms.

[0137] Although the present invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art upon receiving this disclosure. Therefore, the exemplary embodiments of the present invention described above are to be considered illustrative rather than restrictive. Various modifications may be made to the described embodiments without departing from the spirit and scope of the present invention.

[0138] To avoid any doubt, any theoretical explanations provided herein are provided for the purpose of enhancing the reader's understanding. The inventors of this case do not wish to be bound by any of these theoretical explanations.

[0139] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the scope of the application described.

[0140] Unless the context requires otherwise, throughout this specification, including the claims that follow, the words "comprises" and "comprising" and variations thereof will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0141] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation by using the preceding "about," it will be understood that the particular value forms another embodiment. The term "about" in relation to a value is optional and means, for example, + / - 10%.

Claims

1. A method for processing a wafer surface with multiple liquids, comprising: rotating the surface of the wafer; and releasing different liquid streams from separate outlets onto the rotating surface in a sequence, wherein the release of adjacent liquid streams in the sequence overlaps during a transition phase, and wherein during the transition phase, the liquid streams merge after leaving the outlets to form a merged liquid stream before impacting the rotating surface.

2. The method of claim 1, wherein the outlets are bent toward each other to form the combined liquid stream.

3. The method for processing a wafer surface with multiple liquids as claimed in claim 1 or 2, wherein the actual flow path intersection angle between the merged liquid flows is 10° to 40°.

4. The method for processing a wafer surface with multiple liquids as claimed in claim 1, wherein a true flow intersection height of the combined liquid streams is between 2 mm and 100 mm.

5. The method of claim 1, wherein the sequence comprises alternating active steps and rinse steps.

6. The method of claim 5 , wherein the method comprises processing a surface of a semiconductor wafer, wherein the sequence of steps comprises one or more cycles of the following sequence of steps: (A) optional rinsing step; (B) steps for removing organic and / or particulate contaminants; (C) an optional rinsing step; (D) an optional step for removing the surface oxide layer; (E) an optional rinsing step; (F) a step for removing ionic contaminants; and (G) Optional rinsing step.

7. The method of claim 5 , wherein the method comprises processing the surface of a semiconductor wafer, wherein the sequence of steps comprises one or more cycles of the following sequence: (A) optional rinsing step; (F) a step for removing ionic contaminants; (G) an optional rinsing step; (B) steps for removing organic and / or particulate contaminants; (C) an optional rinsing step; (D) an optional step for removing the surface oxide layer; and (E) Optional rinsing step.

8. The method of claim 6 or 7, wherein the method comprises one or more cycles of the following sequence of steps; the one or more cycles comprising steps (B), (F) and at least one of steps (A), (C), (D), (E), and (G): (A) rinsing the surface with water released from the first outlet; (B) treating the surface with a solution released from the second outlet, the solution comprising a mixture of ammonia and hydrogen peroxide; (C) rinsing the surface with water; (D) treating the surface with hydrofluoric acid; (E) rinsing the surface with water; (F) treating the surface with a solution released from a third outlet, the solution comprising a mixture of an acid and hydrogen peroxide; and (G) rinsing the surface with water; and Each cycle of the sequence includes at least one of the rinsing steps (A), (C), (E) and (G).

9. The method for treating a wafer surface with multiple liquids according to claim 8, wherein step (F) comprises treating the surface with a solution comprising a mixture of sulfuric acid or hydrochloric acid and hydrogen peroxide.

10. The method for processing a wafer surface with multiple liquids according to claim 6 or 7, wherein the method comprises one or more cycles of the following sequence of steps; the one or more cycles comprising steps (B), (F) and at least one of steps (A), (C), (D), (E) and (G): (A) rinsing the surface with water released from the first outlet; (F) treating the surface with a solution released from a third outlet, the solution comprising a mixture of an acid and hydrogen peroxide; (G) rinsing the surface with water; (B) treating the surface with a solution released from the second outlet, the solution comprising a mixture of ammonia and hydrogen peroxide; (C) rinsing the surface with water; (D) treating the surface with hydrofluoric acid; (E) rinsing the surface with water; and Each cycle of the sequence includes at least one of the rinsing steps (A), (C), (E) and (G).

11. The method for treating a wafer surface with multiple liquids according to claim 10, wherein step (F) comprises treating the surface with a solution comprising a mixture of sulfuric acid or hydrochloric acid and hydrogen peroxide.

12. A liquid dispensing apparatus for performing a method for treating a wafer surface with multiple liquids, the method comprising: rotating the surface of the wafer; and releasing different liquid streams from separate outlets onto the rotating surface in a sequence, wherein the release of adjacent liquid streams in the sequence overlaps during a transition phase, and wherein during the transition phase, the liquid streams merge after leaving the outlets to form a merged liquid stream before impacting the rotating surface, the liquid dispensing apparatus comprising: a housing holding two or more liquid delivery tubes, wherein the outlets of the liquid delivery tubes are bent inwardly toward each other so that, in use, the different liquid streams delivered from the outlets of the two or more liquid delivery tubes merge to form the merged liquid stream, The intersection angle (θ s ) is 10° to 35°.

13. The liquid dispensing device of claim 12, comprising: the housing, the housing defining an inner chamber opening at the outlet port; a spacer positioned within the interior chamber of the housing; as well as The two or more liquid delivery pipes pass through the partition in the inner chamber of the housing and extend to the outlet port; The two or more liquid delivery tubes are bent around the spacer so that the outlets of the tubes bend inwardly towards each other so that in use the liquid flows delivered from the outlets of the two or more liquid delivery tubes merge to form the merged liquid flow.

14. The liquid dispensing device of claim 13 , wherein the housing and the spacer hold the two or more liquid delivery tubes in position, and the inner chamber of the housing narrows at or toward the outlet port to bend the liquid delivery tubes around the spacer and thereby orient the outlets of the liquid delivery tubes in the inwardly curved configuration.

15. The liquid dispensing device of claim 13 or 14, wherein the spacer has one or more channels, the one or more channels accommodating the liquid delivery tube.

16. The liquid dispensing device of claim 13 or 14, wherein the housing comprises a main body and a removable cap, wherein the removable cap comprises the outlet port.

17. A kit of parts for assembling a liquid dispensing device according to any one of claims 13 to 16, the kit of parts comprising: the frame; and One or more of the spacers.

18. The kit of parts according to claim 17, for assembling a liquid dispensing device, the kit of parts comprising: At least two spacers having different numbers of channels for accommodating the liquid delivery tubes.

19. A cleaning apparatus for treating a wafer surface with multiple liquids, the cleaning apparatus comprising: Clean the chamber; a rotatable wafer support in the clean chamber; as well as A liquid distribution device for performing a method for treating a wafer surface with multiple liquids, the method comprising: rotating the surface of the wafer; and releasing different liquid streams from separate outlets onto the rotating surface in a sequence, wherein the release of adjacent liquid streams in the sequence overlaps during a transition phase, and wherein during the transition phase, the liquid streams merge after leaving the outlets to form a merged liquid stream before impacting the rotating surface, the liquid distribution device comprising: a housing holding two or more liquid delivery tubes, wherein the outlets of the liquid delivery tubes are bent inwardly toward each other so that the different liquid streams delivered from the outlets of the two or more liquid delivery tubes merge in use to form the merged liquid stream, The intersection angle (θ s ) is 10° to 35°.

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