TWM573893U - Cleaning apparatus - Google Patents

Abstract

The present disclosure provides a cleaning apparatus for removing residues from a wafer stack structure. The cleaning apparatus includes: a carrier for placing the wafer stack structure, and a two-fluid nozzle movable relative to the carrier to an interval alignment with two adjacent wafers, wherein the two-fluid nozzle is for applying a chemical liquid and The gas-liquid mixed gas of the gas is applied to the wafer stack structure. The chemical liquid in the gap is separated from the surface to which it adheres via the chemical liquid of the gas-liquid mixed fluid, and the residual force is carried out from the gap by the impact force applied by the gas of the gas-liquid mixed fluid.

Description

Cleaning device

The present disclosure relates to a cleaning apparatus, and more particularly to a cleaning apparatus for removing residues on a wafer stack structure.

The general three-dimensional integrated circuit packaging process includes four steps of making a Via Formation, a Via Filling, a Wafer Thinning, and a Wafer Bonding, and each A wafer cleaning step must be performed before and after a step to avoid contamination of the wafer during processing. Furthermore, the steps of wafer bonding can be roughly divided into three types: chip to wafer (C2W), chip to chip (C2C), wafer to wafer (Wafer to Wafer, W2W). Type. However, whether the gap formed by wafer-to-wafer or wafer-to-wafer bonding is usually 20 to 50 μm, how to remove the residue in such a small gap is a technical bottleneck that is urgently needed to overcome the challenge.

The Taiwan Patent Publication No. TW I539515 discloses a cleaning method and a cleaning apparatus for a wafer stack structure which can clean flux or other impurities in a minute gap between a wafer and a wafer. However, in the patent, it is to adopt a roller type or a brush type sliding structure at the bottom end of the liquid suction device, so that the liquid suction device slides on the substrate by the sliding structure to move to a to be cleaned. position. That is to say, the liquid suction device exerts a downward pressure on the wafer stack structure, which easily causes damage or breakage of the wafer.

In view of the above, it is necessary to propose a cleaning device to solve the problems in the prior art.

In order to solve the above problems of the prior art, it is an object of the present disclosure to provide a cleaning apparatus for cleaning a wafer stack structure in a non-contact manner, thereby avoiding the problem of damage to the wafer caused by applying a downward pressure to the wafer stack structure.

In order to achieve the above object, the present disclosure provides a cleaning apparatus for removing a residue on a wafer stack structure, the wafer stack structure including a substrate and a plurality of wafers, the wafer is separated from the substrate by a gap, and the residue level In the gap between the wafer and the substrate, wherein the cleaning device comprises: a carrier for placing the wafer stack structure; a liquid supply device for providing a chemical liquid; and a gas supply device for Providing a gas; and a two-fluid nozzle movable relative to the carrier to an interval alignment with two adjacent wafers, wherein the two-fluid nozzle is coupled to the liquid supply device and the gas supply device for Applying a gas-liquid mixed fluid comprising the chemical liquid and the gas to the substrate of the wafer stack structure such that the gas-liquid mixed fluid flows into the gap along a first side of the gap, wherein the gas-liquid mixed fluid is passed through the gas-liquid mixed fluid The chemical liquid separates the residue in the gap from the surface to which it adheres, and the impact force applied by the gas of the gas-liquid mixed fluid passes the residue through the residue The second side of the band gap out.

In a preferred embodiment of the present disclosure, the cleaning apparatus further includes: a precision driving device for controlling the movement of the two fluid nozzles in a vertical direction relative to the loading platform and in a horizontal direction.

In a preferred embodiment of the present disclosure, the precision driving device includes a vertical lifting mechanism for controlling the movement of the two fluid nozzles relative to the loading table in the vertical direction. The vertical lifting mechanism includes a stepping motor.

In a preferred embodiment of the present disclosure, the precision driving device includes a horizontal moving mechanism for controlling movement of the two-fluid nozzle relative to the loading table in the horizontal direction, the horizontal moving mechanism including an XY-axis coordinate working table ( XY Table).

In a preferred embodiment of the present disclosure, the cleaning device further includes a cavity, wherein the carrier and the two-fluid nozzle are disposed in the cavity, and a suction port is disposed at a bottom of the cavity.

In a preferred embodiment of the present disclosure, the cleaning device further includes a gas-liquid separation device, wherein the gas-liquid separation device is coupled to the suction port of the cavity for extracting the gas and liquid through the suction port. The mixed fluid is subjected to gas-liquid separation.

In a preferred embodiment of the present disclosure, the gas supply device includes a heater for heating the gas in the gas supply device to a temperature close to the chemical liquid.

In a preferred embodiment of the present disclosure, the gas supply device includes a humidifier for increasing the humidity of the gas in the gas supply device.

In one preferred embodiment of the present disclosure, the carrier includes another heater for heating the wafer stack on the stage to maintain a process temperature.

In a preferred embodiment of the present disclosure, the cleaning device includes a plurality of two-fluid nozzles aligned in a row and juxtaposed, and the plurality of two-fluid nozzles are movable relative to the carrier to two rows The spacing between adjacent wafers is aligned.

In a preferred embodiment of the present disclosure, the front end of the two-fluid nozzle of the cleaning device is disposed at an angle to the surface of the cleaning wafer stack.

In a preferred embodiment of the present disclosure, the two-fluid nozzle comprises a high pressure Clean the nozzle.

In contrast to the prior art, the present disclosure applies a gas-liquid mixed fluid to a wafer stack structure using a two-fluid nozzle in a cleaning device, and cleans the residue in the gap of the wafer stack structure by a gas-liquid mixed fluid. During cleaning, the chemical liquid of the gas-liquid mixed fluid separates the residue in the gap from the surface to which it adheres, and the impact force exerted by the gas of the gas-liquid mixed fluid carries the residue out through the second side of the gap. By this design, the present disclosure can achieve a non-contact cleaning of the wafer stack structure, thereby avoiding the problem of applying a downforce to the wafer stack structure resulting in wafer damage.

1‧‧‧cleaning device

100‧‧‧ cavity

101‧‧‧Exhaust port

110‧‧‧Loading station

111‧‧‧heater

120‧‧‧Liquid supply device

121‧‧‧Supply

122‧‧‧pipe

123‧‧‧Chemical liquid

130‧‧‧ gas supply unit

131‧‧‧ gas supply

132‧‧‧ pipeline

133‧‧‧ gas

134‧‧‧heater

135‧‧‧ humidifier

140‧‧‧Two fluid nozzle

150‧‧‧ gas-liquid mixed fluid

160‧‧‧ gas-liquid separation device

161‧‧‧Liquid recovery tank

170‧‧‧Precision drive

2‧‧‧ wafer stack structure

S‧‧‧Substrate

C‧‧‧ wafer

B‧‧‧Connecting parts

G‧‧‧ gap

D‧‧‧ interval

R‧‧‧residue

P1‧‧‧ first side

P2‧‧‧ second side

3‧‧‧Drying device

310‧‧‧Rotary clamping table

320‧‧‧first nozzle

330‧‧‧Two fluid nozzle

440, 540‧‧‧ two fluid nozzle

Θ‧‧‧ angle

1 is a schematic view showing a cleaning apparatus of a first preferred embodiment of the present disclosure; FIG. 2 is a partial structural view showing the cleaning apparatus of FIG. 1; FIG. 3 is a schematic view showing a moving mechanism of the cleaning apparatus; A schematic view of a drying device corresponding to the cleaning method of the present disclosure; FIG. 5 is a partial schematic view showing the cleaning device of the second preferred embodiment of the present disclosure; and FIG. 6 is a view showing the cleaning of the third preferred embodiment of the present disclosure. A partial schematic of the device.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

The microprocessor chip includes a logic unit and a plurality of cache memories. If both the logic unit and the cache memory are configured in a two-dimensional (2-D) pattern, the physical size of the wafer will limit the cache memory. The number of bodies (due to poor processing of large-area wafers) limits the performance of the microprocessor. In order to solve the problem of 2-D resources on the wafer, a Three-Dimensional (3-D) integrated circuit is being actively developed. In general, a typical 3D-IC process includes four steps: making a Via Formation, filling a Via Filling, Wafer Thinning, and Wafer Bonding. And the wafer cleaning step must be performed before and after each step to avoid contamination of the wafer during processing. Furthermore, the steps of wafer bonding can be roughly divided into three types: chip to wafer (C2W), chip to chip (C2C), wafer to wafer (Wafer to Wafer, W2W). Type. However, the gap between wafer and wafer or wafer and wafer bonding is typically 20 to 50 μm . The cleaning apparatus and cleaning method of the present disclosure can achieve the removal of residues in such minute gaps.

Referring to Figure 1, there is shown a schematic view of a cleaning apparatus 1 of a first preferred embodiment of the present disclosure. The cleaning device 1 is for removing the residue R on the wafer stack structure 2, wherein the residue R may be a substance remaining in a previous process, such as flux, resin, adhesive, particles, organic matter, inorganic matter, and the like. The wafer stack structure 2 is a three-dimensional integrated circuit board including a substrate S and a plurality of wafers C arranged in an array. A plurality of connecting members B are disposed between the wafer C and the substrate S. Connector B can be a solder ball or any suitable component that solders substrate S to wafer C. The connector B is used to connect the substrate S and the wafer C and to separate the substrate S from the wafer C by a gap G, wherein the substance to be removed by the cleaning device 1 is the residue R located in the gap G between the substrate S and the wafer C.

As shown in FIG. 1 , the cleaning device 1 mainly includes a cavity 100 , a loading platform 110 , a liquid supply device 120 , a gas supply device 130 , a two-fluid nozzle 140 , and a gas-liquid separation device 160 , wherein the loading platform 110 and the two-fluid nozzle 140 It is disposed in the cavity 100. A suction port 101 is provided at the bottom of the cavity 100, and the gas-liquid separation device 160 is connected to the suction port 101 of the cavity 100. The carrier 110 is used to place the wafer stack structure 2. The carrier 110 includes a heater 111 for heating the wafer stack structure 2 on the carrier 110 to maintain the proper process temperature.

Please refer to FIG. 1 and FIG. 2, wherein FIG. 2 is a partial schematic view showing the cleaning device 1 of FIG. The liquid supply device 120 includes a liquid supply end 121 and a line 122, wherein the liquid supply end 121 contains a chemical liquid 123 therein. The gas supply device 130 includes a gas supply end 131 and a line 132, wherein the gas supply end 131 contains a gas 133 therein. Alternatively, the gas 133 may be nitrogen, Clean Dry Air (CDA), or the like. The two-fluid nozzle 140 is connected to the liquid supply device 120 and the gas supply device 130 for mixing the chemical liquid 123 provided by the liquid supply device 120 and the gas 133 provided by the gas supply device 130 to form a gas-liquid mixed fluid 150, and the gas The liquid mixed fluid 150 is ejected onto the substrate S of the wafer stack structure 2.

As shown in FIG. 2, the air supply device 130 further includes a heater 134 and a humidifier 135. In order to remove the residue R on the wafer stack 2, the use of a chemical liquid 123 with a certain temperature accelerates the reaction between the chemical liquid 123 and the residue R, so that the residue R is separated from the surface to which it adheres. However, when the gas 133 is mixed with the chemical liquid 123, the gas 133 causes the temperature of the chemical liquid 123 to drop. Therefore, the present disclosure provides the heater 134 so that the gas 133 in the gas supply device 130 can be heated to be close to the temperature of the chemical liquid 123, thereby preventing the chemical liquid 123 from being lowered due to the influence of the low temperature gas 133. Further, the present disclosure increases the humidity of the gas 133 in the air supply device 130 by providing the humidifier 135 to prevent the temperature of the chemical liquid 123 from being affected by the humidity of the gas 133.

Please refer to FIG. 3, which shows a schematic diagram of the moving mechanism of the cleaning device 1. The moving mechanism of the cleaning device 1 can be implemented by the precision driving device 170. The precision driving device 170 has a vertical lifting mechanism and a horizontal moving mechanism. The vertical lifting mechanism and the horizontal moving mechanism of the precision driving device 170 are electrically connected to the main control device (for example, a computer), and the operation of the moving mechanism of the cleaning device 1 can be set by a control program in the main control device.

As shown in FIG. 3, the precision drive unit 170 is coupled to the two-fluid nozzle 140. The vertical lifting mechanism has a connector connected to the two-fluid nozzle 140 and a precision driving element (for example, a stepping motor) for controlling the movement of the two-fluid nozzle 140 in the vertical direction relative to the carrier 110 (ie, away from or near the stage 110). ). By setting the precision driving element, the position of the two-fluid nozzle 140 to move up and down can be precisely controlled. Preferably, the precision driving device 170 can be combined with a coordinate measuring mechanism to record the moving position and speed of the two-fluid nozzle 140 in the vertical direction. In addition, the horizontal movement mechanism is for controlling the horizontal movement of the two-fluid nozzle 140. For example, the horizontal moving mechanism can employ an X-Y axis table (X-Y Table) to precisely control the horizontal movement of the two-fluid nozzle 140 to accurately align to the cleaning position. Moreover, the X-Y axis coordinate working table can be used with a point recording device for recording the moving position of the two-fluid nozzle 140, so as to facilitate the rapid positioning of the positioning point of the two-fluid nozzle 140 required for the wafer stack structure 2 of the same pattern during mass production. It should be noted that in order to cooperate with the precise point setting described above, the carrier 110 preferably holds the wafer stack 2 thereon by vacuum adsorption, thus ensuring that the wafer stack 2 is not carried during the cleaning process. Stage 110 produces relative movement.

It is an object of the present disclosure to provide a cleaning apparatus and method in which the cleaning apparatus 1 cleans the wafer stack structure 2 in a non-contact manner, thereby avoiding the problem that the wafer C is damaged by applying a downward pressure to the wafer stack structure 2. Part of the steps of the cleaning method of the present disclosure is performed by the cleaning device 1, wherein the specific steps of the cleaning method are detailed later with the cleaning device 1.

The cleaning method of the present disclosure includes the following steps. First, referring to FIG. 1, the wafer stack structure 2 is placed on the stage 110. The heater 111 on the stage 110 is opened to heat the wafer stack 2 on the stage 110 to maintain the wafer stack 2 at a suitable process temperature. By maintaining the temperature, the subsequently applied chemical liquid 123 can be maintained at an appropriate process temperature without It will be cooled, thereby accelerating the reaction between the chemical liquid 123 and the residue R to separate the residue R from the surface to which it adheres.

As shown in FIGS. 1 and 3, after the wafer stack 2 is placed, the two-fluid nozzle 140 is controlled to move over the stage 110 by the precision driving device 170 to move the two-fluid nozzle 140 to be adjacent to the two. The spacing D between the wafers C is aligned and moved to align with the first side P1 of the gap G.

As shown in FIGS. 1 and 2, the humidity of the gas 133 in the air supply device 130 is increased by the humidifier 135, and the gas 133 in the air supply device 130 is heated to the chemical liquid 123 by the heater 134. The temperature is similar. Next, the gas supply device 130 and the liquid supply device 120 transfer the gas 133 and the chemical liquid 123 to the two-fluid nozzle 140, respectively. The gas 133 and the chemical liquid 123 are mixed inside the two-fluid nozzle 140 to form a gas-liquid mixed fluid 150.

Next, as shown in FIG. 1, the gas-liquid mixed fluid 150 is applied to the substrate S of the wafer stack structure 2 by the two-fluid nozzle 140, so that the gas-liquid mixed fluid 150 flows into the gap G along the first side P1 of the gap G. . The chemical liquid 123 passing through the gas-liquid mixed fluid 150 undergoes a chemical cleaning reaction with the residue R in the gap G, causing the residue R to be separated from the surface to which it adheres, and the impact force applied by the gas 133 of the gas-liquid mixed fluid 150. The residue R is taken out via the second side P2 of the gap G. It should be noted that while the two-fluid nozzle 140 is spraying the gas-liquid mixed fluid 150, the precision driving device 170 controls the two-fluid nozzle 140 to move in the horizontal direction. Preferably, the two-fluid nozzle 140 is moved in parallel along the interval D between two adjacent wafers C. However, in another embodiment, in order to simplify the control program, the precision driving device 170 can be set to only move the two-fluid nozzle 140 from the interval D between two adjacent wafers C when moving in the X direction. Moving to the interval D between the other two adjacent wafers C, when the two-fluid nozzle 140 sprays the full-face wafer stack junction along the X direction After the structure 2, the stage 110 is rotated by 90 degrees. When the precision driving device 170 sets the two-fluid nozzle 140 to move in the Y direction, the two-fluid nozzle 140 corresponds to the interval D between two adjacent wafers C, and moves in parallel along the direction in which the interval D extends. The spraying operation of the gas-liquid mixed fluid 150 is simultaneously performed, and the above-described full-spraying operation is performed again, so that the gap G of the wafer stack structure 2 is cleaned.

In the present disclosure, the liquid supply device 120 may provide a cleaning liquid such as pure water, deionized water or the like in addition to the chemical liquid 123. Also, after the residue R in the gap G is removed via the gas-liquid mixed fluid 150, the liquid supply device 120 can be switched to supply the cleaning liquid to the two-fluid nozzle 140, so that the two-fluid nozzle 140 sprays the cleaning liquid on the wafer stack structure 2. To remove the gas-liquid mixed fluid 150 on the wafer stack 2.

On the other hand, as shown in FIG. 1, when the two-fluid nozzle 140 sprays the gas-liquid mixed fluid 150 or the cleaning liquid on the wafer stack structure 2, the gas-liquid separation device 160 can take the outlet 101 through the cavity 100. The extracted liquid and gas are subjected to gas-liquid separation. Preferably, the gas-liquid separation device 160 is provided with a filter which filters the extracted solid residue R first, then separates the liquid from the gas, finally introduces the liquid into the liquid recovery tank 161, and discharges the gas. Therefore, the liquid recovered after the gas-liquid separation can be reused after being appropriately treated. Further, a flow meter may be added to the liquid recovery tank 161 for recording the pumping flow rate value.

After the residue R in the gap G of the wafer stack structure 2 is removed, the wafer stack structure 2 is moved into the drying device to perform a final cleaning and drying step on the wafer stack structure 2. Referring to Figure 4, there is shown a schematic diagram of the drying apparatus 3 used in the cleaning method of the present disclosure. The drying device 3 includes a rotating clamping table 310, a first nozzle 320, and a two-fluid nozzle 330. The first nozzle 320 is connected to the liquid supply end, and the two-fluid nozzle 330 and the volatile solvent The supply end is connected to the gas supply end. After the wafer stack structure 2 is moved into the drying device, the first nozzle 320 sprays the cleaning liquid on the back surface of the substrate S of the wafer stack structure 2 to remove the gas-liquid mixed fluid 150 remaining on the back surface of the substrate S, wherein the cleaning liquid may be Pure water, deionized water, etc.

Then, after the front and back sides of the wafer stack 2 are cleaned, the wafer stack 2 is simultaneously supplied with a volatile solvent and a drying gas through the two-fluid nozzle 330 to remove moisture on the surface of the wafer stack 2, wherein the volatile solvent It may be Isopropyl Alcohol (IPA), and the drying gas may be nitrogen. Alternatively, after the front and back sides of the wafer stack 2 are cleaned, the moisture of the surface of the wafer stack 2 may be removed by placing the wafer stack 2 in the oven, without being limited thereto.

Please refer to FIG. 5, which shows a partial schematic view of the cleaning device of the second preferred embodiment of the present disclosure. The cleaning device of the second preferred embodiment is substantially the same as the cleaning device 1 of the first preferred embodiment, except that the cleaning device of the second preferred embodiment is provided with a plurality of two-fluid nozzles 240, so that it can be disposable A plurality of gaps G between the wafer C and the substrate S of the wafer stack structure 2 are cleaned. Specifically, a plurality of two-fluid nozzles 440 are aligned in a row in a side-by-side arrangement, and a plurality of two-fluid nozzles 440 are movable to align with a plurality of gaps G between two adjacent rows of wafers C. By this design, the cleaning time of the wafer stack structure 2 can be effectively shortened to improve the cleaning performance.

Referring to Figure 6, there is shown a partial schematic view of a cleaning apparatus in accordance with a third preferred embodiment of the present disclosure. The cleaning apparatus of the third preferred embodiment is substantially the same as the cleaning apparatus 1 of the first preferred embodiment, except that the cleaning apparatus of the third preferred embodiment sets the front end of the two-fluid nozzle 540 to be stacked with respect to the cleaning wafer. The surface of the structure 2 is inclined by an angle θ. Preferably, the angle θ is 30 to 60 degrees. And with a precision drive to control the two-fluid nozzle to move in a single direction The spraying operation is performed so that the residue R can be moved in the same direction. For example, when the two-fluid nozzle 540 is inclined in the upper right direction toward the lower left direction, and the precision driving device controls the two-fluid nozzle to move from the right to the left direction and performs the spraying operation, the residue R is moved to the left direction. . With this design, the residue R can be prevented from being flushed back into the cleaned gap G.

In summary, the present disclosure applies a gas-liquid mixed fluid to the wafer stack structure by using a two-fluid nozzle in the cleaning device, and cleans the residue in the gap of the wafer stack structure by the gas-liquid mixed fluid. During cleaning, the chemical liquid of the gas-liquid mixed fluid separates the residue in the gap from the surface to which it adheres, and the impact force exerted by the gas of the gas-liquid mixed fluid carries the residue out through the second side of the gap. The present disclosure uses a two-fluid nozzle to apply a gas-liquid mixed fluid to the wafer stack structure. High pressure cleaner (HPC) nozzles can also be used to apply high pressure fluid to the wafer stack structure, and the wafer stack structure is cleaned by high pressure liquid. Residues in the gap. Upon cleaning, the high pressure liquid separates the residue within the gap from its attached surface, and the impact force exerted by the high pressure liquid carries the residue out through the second side of the gap. By this design, the present disclosure can achieve cleaning of the wafer stack structure in a non-contact manner, thereby avoiding the problem that the cleaning nozzle directly applies a downward pressure to the wafer stack structure, resulting in wafer damage.

The above is only a preferred embodiment of the present disclosure, and it should be noted that those skilled in the art can also make several improvements and refinements without departing from the principles of the present disclosure. These improvements and refinements should also be considered as protected range.

Claims (12)

A cleaning device for removing residues on a wafer stack structure, the wafer stack structure comprising a substrate and a plurality of wafers, the wafer being separated from the substrate by a gap, and the residue being located between the wafer and the substrate In the gap, wherein the cleaning device comprises: a loading platform for placing the wafer stack structure; a liquid supply device for providing a chemical liquid; a gas supply device for supplying a gas; and a two fluid a nozzle movable relative to the carrier to an interval between two adjacent wafers, wherein the two-fluid nozzle is coupled to the liquid supply device and the gas supply device for applying the chemical liquid and the gas a gas-liquid mixed fluid onto the substrate of the wafer stack structure such that the gas-liquid mixed fluid flows into the gap along a first side of the gap, wherein the chemical liquid passing through the gas-liquid mixed fluid is within the gap The residue is separated from the surface to which it is attached, and the residue is carried out via the second side of the gap by the impact force applied by the gas of the gas-liquid mixed fluid. The cleaning device of claim 1, wherein the cleaning device further comprises: a precision driving device for controlling the movement of the two-fluid nozzle relative to the loading table in a vertical direction and in a horizontal direction. The cleaning device of claim 2, wherein the precision driving device comprises a vertical lifting mechanism for controlling movement of the two fluid nozzles relative to the loading table in the vertical direction, the vertical lifting mechanism comprising a stepping motor. The cleaning device of claim 2, wherein the precision driving device comprises a horizontal moving mechanism for controlling movement of the two-fluid nozzle relative to the loading table in the horizontal direction, the horizontal shift The moving mechanism includes an X-Y axis work table (X-Y Table). The cleaning device of claim 1, further comprising a cavity, wherein the carrier and the two-fluid nozzle are disposed in the cavity, and a suction port is disposed at a bottom of the cavity. The cleaning device of claim 5, further comprising a gas-liquid separation device, wherein the gas-liquid separation device is connected to the suction port of the cavity for gasifying the gas-liquid mixed fluid pumped through the suction port Liquid separation. The cleaning device of claim 1, wherein the gas supply device comprises a heater for heating the gas in the gas supply device to be close to a temperature of the chemical liquid. The cleaning device of claim 1, wherein the gas supply device comprises a humidifier for increasing the humidity of the gas in the gas supply device. A cleaning apparatus according to claim 1, wherein the stage includes another heater for heating the wafer stack structure on the stage to maintain a process temperature. The cleaning device of claim 1, wherein the cleaning device comprises a plurality of two-fluid nozzles aligned in a row and juxtaposed, and the plurality of two-fluid nozzles are movable relative to the carrier to two rows The spacing between adjacent wafers is aligned. The cleaning device of claim 1, wherein the front end of the two-fluid nozzle of the cleaning device is disposed at an angle to the surface of the cleaning wafer stack. The cleaning device of claim 1, wherein the two-fluid nozzle comprises a high pressure cleaning nozzle.