CN111312631A - Wafer cleaning device - Google Patents

Abstract

The present application discloses a wafer cleaning device, the wafer cleaning device includes: a cleaning chamber for accommodating an ultrasonic transmission medium; an ultrasonic generator for providing ultrasonic waves so that the ultrasonic transmission medium vibrates under the action of the ultrasonic waves; A circular placement mechanism, located in the cleaning chamber, is used for positioning the wafer in the ultrasonic transmission medium. The wafer cleaning device positions the wafer in the ultrasonic transmission medium, so that the surface of the wafer can be completely contacted with the ultrasonic transmission medium, and vibrates the ultrasonic transmission medium through ultrasonic waves, thereby achieving the effect of cleaning the surface of the wafer, and It will not damage the surface of the wafer while improving the cleaning efficiency and cleaning strength.

Description

Wafer cleaning device

technical field

The present invention relates to the technical field of semiconductor manufacturing, and more particularly, to a wafer cleaning device.

Background technique

The improvement of the storage density of memory devices is closely related to the advancement of the semiconductor manufacturing process. As the feature sizes of semiconductor manufacturing processes are getting smaller and smaller, the storage density of memory devices is getting higher and higher. In order to further increase the storage density, three-dimensionally structured storage devices (ie, 3D storage devices) have been developed. 3D memory devices include multiple memory cells stacked in a vertical direction, which can exponentially increase the integration level on a wafer per unit area, and can reduce costs.

Direct Wafer Bonding is a technique for tightly bonding two polished wafers together without the use of adhesives. This technology is widely used in emerging fields such as multi-functional chip integration, microelectronics manufacturing and MEMS packaging. Especially in recent years, the application in the manufacturing process of 3D memory chips has greatly promoted the rapid development of 3D memory device technology.

The wafer bonding technology has extremely high requirements on the cleanliness and flatness of the wafer surface. Therefore, if the particles cannot be removed when cleaning the wafer surface or the wafer surface is damaged during the cleaning process, it will affect the wafer surface. bonding effect.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an improved wafer cleaning device, which not only enhances the cleaning effect of the wafer, but also avoids damage to the wafer.

An embodiment of the present invention provides a wafer cleaning device, including: a cleaning chamber for accommodating an ultrasonic transmission medium; an ultrasonic generator for providing ultrasonic waves, so that the ultrasonic transmission medium vibrates under the action of the ultrasonic waves; and a wafer A placing mechanism, located in the cleaning chamber, is used for positioning the wafer in the ultrasonic transmission medium.

Preferably, the wafer placement mechanism is configured to support at least the edge of one wafer.

Preferably, the wafer placement mechanism includes at least one support portion, the at least one support portion is fixed and connected in sequence in the direction of gravity, and each support portion is used to support the edge of a corresponding one of the wafers.

Preferably, each of the supporting parts includes at least two supporting members, the supporting surface of each supporting member is used to support the edge of the corresponding wafer, and the supporting surface of each supporting member is generally along the The direction of gravity extends at an acute angle.

Preferably, the supporting surface is an arc surface, a plane surface, a stepped surface, a wavy surface, a zigzag surface or an irregular concave-convex surface.

Preferably, an adjustment mechanism is also included, which is connected with the wafer placement mechanism and is used for the circumferential radius enclosed by the support portion.

Preferably, each of the supporting parts includes an arc-shaped supporting member, the supporting surface of the arc-shaped supporting member is used to support the edge of the corresponding wafer, and the supporting surface of each arc-shaped supporting member is generally along the direction of gravity. Extends at an acute angle.

Preferably, the support surface of the arc-shaped support member is an arc surface, a plane surface, a stepped surface, a wavy surface, a zigzag surface or an irregular concave-convex surface.

Preferably, the ultrasonic transmission medium includes deionized water or an organic solvent.

Preferably, it further includes: a drying chamber for containing inert gas; and a wafer carrying mechanism located in the drying chamber.

Preferably, the wafer carrier mechanism includes a rotatable member for contacting the wafer, the axis of rotation of the rotatable member being perpendicular to the surface of the wafer and passing through the center/center of gravity of the wafer.

According to the wafer cleaning apparatus of the embodiment of the present invention, the wafer is positioned in the ultrasonic transmission medium by the wafer placement mechanism located in the cleaning chamber, so that the surface of the wafer can be completely contacted with the ultrasonic transmission medium, and the ultrasonic transmission medium is caused by ultrasonic waves. Vibration, so as to achieve the effect of cleaning the surface of the wafer. Compared with the prior art, the wafer cleaning device of the present application can make the wafer surface fully and uniformly contact the ultrasonic transmission medium, improve the cleaning efficiency of the wafer surface and enhance the decontamination ability of the wafer surface. , and will not damage the surface of the wafer.

At the same time, since the wafer placement structure locates the wafer in the ultrasonic transmission medium, the wafer is prevented from being exposed to the air and the oxidation of the metal structure on the surface of the wafer is prevented.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 a and FIG. 1 b respectively show a schematic structural diagram of a conventional wafer cleaning apparatus.

FIG. 2 shows a schematic structural diagram of a wafer cleaning apparatus according to an embodiment of the present invention.

FIG. 3a shows a schematic structural diagram of the wafer placement mechanism according to the first embodiment of the present invention.

Figure 3b shows a cross-sectional view along line AA in Figure 3a.

FIG. 4 shows a schematic structural diagram of a wafer placement mechanism according to a second embodiment of the present invention.

Detailed ways

The present invention will be described in more detail below with reference to the accompanying drawings. In the various figures, like elements are designated by like reference numerals. For the sake of clarity, various parts in the figures have not been drawn to scale. Additionally, some well-known parts may not be shown. For the sake of simplicity, the semiconductor structure obtained after several steps can be depicted in one figure.

It will be understood that, in describing the structure of a device, when a layer or region is referred to as being "on" or "over" another layer or region, it can be directly on the other layer or region, or Other layers or regions are also included between it and another layer, another region. And, if the device is turned over, the layer, one region, will be "under" or "under" another layer, another region.

In order to describe the situation directly above another layer, another area, the expression "directly on" or "on and adjacent to" will be used herein.

In this application, the term "semiconductor structure" refers collectively to the entire semiconductor structure formed during the various steps of fabricating a memory device, including all layers or regions that have already been formed. Numerous specific details of the present invention are described below, such as device structures, materials, dimensions, processing techniques and techniques, in order to provide a clearer understanding of the present invention. However, as can be understood by one skilled in the art, the present invention may be practiced without these specific details.

The invention may be embodied in various forms, some examples of which will be described below.

FIG. 1 a and FIG. 1 b respectively show a schematic structural diagram of a conventional wafer cleaning apparatus.

As shown in FIG. 1 a , the support table 110 attracts the backside of the wafer 10 to fix the wafer 10 . Deionized water (DIW) is delivered to the front side of wafer 10 through conduit 120 . The ultrasonic wave generator 130 is used to emit ultrasonic waves, and the ultrasonic waves act on the front surface of the wafer 10 through deionized water to remove particles attached to the front surface of the wafer 10 . Finally, the wafer 10 is driven to rotate at a high speed by the high-speed rotating stage 110 , thereby drying the wafer 10 and completing the final cleaning step.

During this process, since the deionized water is transported to the front side of the wafer 10 through the pipeline 120 , the distribution of the deionized water on the front side of the wafer 10 is uneven, so that the ultrasonic waves act on the front side of the wafer 10 through the deionized water. The effect is different, and the particles on the front side of the wafer 10 cannot be completely removed. At the same time, since the deionized water is only delivered to the front side of the wafer 10, and the back side of the wafer 10 is not in contact with the deionized water, the ultrasonic wave cannot act on the back side of the wafer 10, so the back side of the wafer 10 cannot be cleaned, which may cause The bonding of the wafer 10 is affected. For example, in the process of moving the wafers 10, the wafers 10 often need to be transported into a front opening unified pod (FOUP) for unified transport. In the wafer box, the particles on the backside of the wafer 10 may fall to the front side of the wafer below, or the front side of the wafer 10 may be re-contaminated by the particles above, thereby affecting the bonding effect between wafers . In addition, in the process of cleaning the wafer 10, the wafer 10 is exposed to the air for a long time, which accelerates the oxidation process of the metal structure on the wafer 10, resulting in a decrease in the yield of the device. Furthermore, since the wafer 10 is dried by high-speed rotation, there is a risk of slippage.

As shown in FIG. 1 b , the support table 210 attracts the backside of the wafer 10 to fix the wafer 10 . The deionized water is delivered to the junction part 240 through the pipeline 220 , and then the high-pressure gas pipeline 230 is used to deliver gas to the junction part 240 to be ejected to the front surface of the wafer 10 at a high speed. Thereby, the effect of removing the particles on the front surface of the wafer 10 is achieved. Finally, the wafer 10 is driven to rotate at a high speed by the high-speed rotating stage 210 , so as to dry the wafer 10 and complete the final cleaning step.

During this process, the front surface of the wafer 10 will be severely damaged due to the impact of the high-pressure water flow, thereby affecting the bonding effect. In addition, in the solution described in FIG. 1b, there are also problems that the backside of the wafer 10 cannot be cleaned, that the wafer 10 is exposed to the air for a long time to accelerate the oxidation of the metal structure on the wafer 10, and the problems of sliding sheets.

FIG. 2 shows a schematic structural diagram of a wafer cleaning apparatus according to an embodiment of the present invention.

As shown in FIG. 2 , the wafer cleaning apparatus according to the embodiment of the present invention includes a cleaning chamber 310 , an ultrasonic generator 320 , a wafer placement mechanism 330 , a drying chamber 340 , a wafer carrier mechanism 350 and an adjustment mechanism (not shown).

The cleaning chamber 310 is used to accommodate the ultrasonic transmission medium. Wherein, the ultrasonic transmission medium includes one or a combination of deionized water and an organic solvent. In some preferred embodiments, the ultrasonic transmission medium includes a volatile organic solvent, such as ethanol, isopropanol, and the like.

In the embodiment of the present invention, the cleaning chamber 310 has a box door. When the box door is opened, the wafers 10 can be put into or taken out of the cleaning room 310 from the outside, or the wafer placement mechanism 330 can be put into or taken out of the cleaning room 310 . When the cleaning chamber 310 cleans the wafers 10, the box door is closed, so that the cleaning chamber 310 is a closed space.

The ultrasonic generator 320 is used to provide ultrasonic waves. In this embodiment, the ultrasonic generator 320 is located on one side of the cleaning chamber 310 . In some other embodiments, the sonotrode is located at the bottom of the cleaning chamber 310 . However, the embodiment of the present invention is not limited thereto, and those skilled in the art can set other positions of the ultrasonic generator 320 as required, so that the ultrasonic transmission medium in the cleaning chamber 310 can vibrate.

The wafer placement mechanism 330 is located in the cleaning chamber 310 for positioning the wafer 10 in the ultrasonic transmission medium. The wafer placement mechanism 330 is configured to support at least the edge of one wafer. In the state where the cleaning chamber 310 cleans the wafers 10, at least a part of the wafer placement mechanism 330 is immersed in the ultrasonic transmission medium, wherein the part of the wafer placement mechanism 330 immersed in the ultrasonic transmission medium is used to support at least one wafer 10's edge. For example, the front side of the wafer 10 is sent to the wafer placement mechanism 330 with the front side facing the direction of gravity. The wafer placement mechanism 330 supports the edge of the wafer 10. If the ultrasonic transmission medium passes through the wafer placement mechanism 330, the wafer placement mechanism 330 is used to support the wafer. The edge portion can ensure that the front surface of the wafer 10 is fully in contact with the ultrasonic transmission medium. Further, the liquid level height of the ultrasonic transmission medium is increased, so that the backside of the wafer 10 is fully contacted with the ultrasonic transmission medium. Alternatively, regardless of the orientation of the wafers 10 , the front and back surfaces of the wafers 10 can be sufficiently cleaned by immersing the wafers 10 in the ultrasonic transmission medium at intervals. Since the ultrasonic transmission medium in the embodiment of the present invention is accommodated in the cleaning chamber, and the wafer placement structure can position the wafer in the ultrasonic transmission medium, the application of the ultrasonic transmission medium on the surface of the wafer in the prior art can be omitted. A step of. The specific structure of the wafer placement mechanism 330 will be described in detail later.

The drying chamber 340 is used to contain the inert gas. In the embodiment of the present invention, the drying chamber 340 has a box door. When the box door is opened, the wafers 10 can be put into or taken out of the drying chamber 340 from the outside. In the state where the drying chamber 340 is drying the wafer 10, the box door is closed, so that the drying chamber 340 is a closed space.

The wafer carrier mechanism 350 is located in the drying chamber 340 , and the wafer carrier mechanism 350 is used for adsorbing the backside of the wafer 10 to fix the wafer 10 . The wafer carrier mechanism 350 includes a rotatable member for contacting the wafer 10 , and the rotation axis of the rotatable member is perpendicular to the surface of the wafer 10 and passes through the center/center of gravity of the wafer 10 .

In the environment of inert gas, the wafer carrier mechanism 350 drives the wafer 10 to rotate, so as to achieve the purpose of drying the wafer 10 . Compared with the prior art, since the drying chamber 340 of the embodiment of the present invention is a closed space, and the drying chamber 340 is filled with inert gas, the wafer 10 is not in contact with the air during the drying process, which prevents the surface of the wafer 10 from being damaged. The metal structure is oxidized. Further, since there is no need to worry about the problem of oxidation of the metal structure, the rotational speed of the rotatable components can be relatively reduced to prevent the wafer 10 from having a problem of slippage.

FIG. 3a shows a schematic structural diagram of the wafer placement mechanism according to the first embodiment of the present invention. Figure 3b shows a cross-sectional view along line AA in Figure 3a.

As shown in FIGS. 3 a to 3 b , the wafer placement mechanism according to the first embodiment of the present invention includes at least one supporting portion 331 , the at least one supporting portion 331 is fixed and connected in sequence in the direction of gravity, and each supporting portion 331 is used to support a corresponding The edge of a wafer 10 . Wherein, each support portion 331 includes at least two support members. Fig. 3a shows the case where each support part 331 includes three support members 331a, 331b, 331c. In some specific embodiments, the support portion 331 may be fixed on the bracket 332 along the direction of gravity. The number and shape of the brackets 332 can be set as required.

In this embodiment, the supporting surface 301 of each supporting member is used to support the edge of the corresponding wafer 10 , and the supporting surface 301 of each supporting member generally extends along a direction forming an acute angle with the direction of gravity. The support surface 301 of each support member shown in FIG. 3a is a plane, therefore, the wafer 10 and the support surface 301 are in a point contact state. To maintain the stable support of the wafer 10, the wafer 10 and the support surface 301 need to be in contact with each other. The contact points are at least 3, so 3 supports 331a, 331b, 331c are required. In this embodiment, since the wafer 10 is in point contact with the support surface 301, the surface of the wafer 10 can be completely exposed to the ultrasonic transmission medium except for the contact points, and the surface of the wafer 10 is in contact with the ultrasonic transmission medium. uniformity, thereby increasing the cleaning effect.

In some other embodiments, the supporting surface 301 may also include one or a combination of a plane, an arc, a stepped surface, a wavy surface, a zigzag surface, or an irregular concave-convex surface. Since the support surface 301 is no longer just a plane, the contact point between the support surface of one support member and the wafer can be greater than 1, which increases the stability of the supported wafer 10, so the number of support members can be reduced to two.

The adjusting mechanism of the present invention is connected with the wafer placing mechanism, and is used for adjusting the circle radius enclosed by the support portion. In a specific embodiment, the adjusting mechanism can change the radius of the circle enclosed by the support portion by extending the length of the support surface 301, adjusting the position of the bracket 332, adjusting the inclination angle α of the support surface 301, etc., as shown in FIG. 3b. For example, when the inclination angle α of the support surface 301 increases, the linear distance between the ends of the support members becomes smaller, so that a wafer with a smaller radius can be supported. Extending the length of the support surface 301 (the dotted line is the extension of the support piece) can also make the linear distance between the ends of the support piece smaller. Those skilled in the art can make other settings for the specific scheme of adjusting the circle radius enclosed by the support portion as required.

FIG. 4 shows a schematic structural diagram of a wafer placement mechanism according to a second embodiment of the present invention.

The wafer placement mechanism of the second embodiment of the present invention includes at least two support parts 331 , at least one support part 331 is fixed and connected in sequence in the direction of gravity, and each support part 331 is used to support the edge of a corresponding wafer 10 . Wherein, each support portion 331 includes an arc-shaped support member, and the support surface 301 of the arc-shaped support member is attached to the edge of the wafer 10 for supporting the corresponding edge of the wafer 10 . The support surface 301 of each arc-shaped support member generally extends along a direction that forms an acute angle with the direction of gravity.

The support surface 301 of each support member shown in FIG. 4 is a plane, therefore, the wafer 10 and the support surface 301 are in a dotted state, so the surface of the wafer 10 can be completely exposed to the ultrasonic transmission medium except for the contact line, The uniformity of the contact between the surface of the wafer 10 and the ultrasonic transmission medium increases the cleaning effect.

In some other embodiments, the supporting surface 301 may also include one or a combination of a flat surface, an arc surface, a stepped surface, a wavy surface, a serrated surface, or an irregular concave-convex surface, thereby increasing the support of the supported wafer 10 . stability.

In some other embodiments, the wafer placement mechanism 330 may further include a bracket with at least one groove, the convex portion below the groove (in the direction of gravity) is used as a supporting portion, and the surface of the groove in contact with the wafer is inclined support surface, as shown in Figure 2. In addition, the wafer can be fixed by clamping the edge of the wafer to expose the wafer surface to the ultrasonic transmission medium.

According to the wafer cleaning apparatus of the embodiment of the present invention, by immersing the edge portion of the wafer placement mechanism used to support the wafer in the ultrasonic transmission medium, the surface of the supported wafer can be completely contacted with the ultrasonic transmission medium, and The ultrasonic wave is used to make the ultrasonic transmission medium vibrate, so as to achieve the effect of cleaning the surface of the wafer. Compared with the prior art, the wafer cleaning device of the present application can make the surface of the wafer fully and uniformly contact the ultrasonic transmission medium, thereby improving the cleaning efficiency and cleaning strength, and at the same time, the surface of the wafer will not be damaged.

Further, by exposing the wafer to an environment of inert gas for spin drying, the spin speed can be reduced and the risk of slippage can be reduced.

Further, during the cleaning and drying process of the wafer, the wafer is always in a closed environment, thus reducing the risk of metal oxidation on the surface of the wafer.

In the above description, technical details such as patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not exactly the same as those described above. Additionally, although the various embodiments have been described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

Embodiments of the present invention have been described above. However, these examples are for illustrative purposes only, and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present invention.

Claims (11)

1. A wafer cleaning device, comprising: a cleaning chamber for containing the ultrasonic transmission medium; an ultrasonic generator for providing ultrasonic waves so that the ultrasonic transmission medium vibrates under the action of ultrasonic waves; and A wafer placement mechanism, located in the cleaning chamber, is used for positioning the wafer in the ultrasonic transmission medium. 2. The wafer cleaning apparatus of claim 1, wherein the wafer placement mechanism is configured to support at least an edge of one wafer. 3 . The wafer cleaning apparatus according to claim 2 , wherein the wafer placement mechanism comprises at least one supporting portion, the at least one supporting portion is fixedly connected in sequence in the direction of gravity, and each supporting portion is used for 3 . supporting a corresponding one of the edges of the wafer. 4. The wafer cleaning apparatus according to claim 3, wherein each of the supporting parts comprises at least 2 supporting members, and the supporting surface of each supporting member is used to support the edge of the corresponding wafer, and each supporting member comprises at least two supporting members. The supporting surfaces of each of the supporting pieces extend along a direction that forms an acute angle with the direction of gravity as a whole. 5 . The wafer cleaning apparatus according to claim 4 , wherein the supporting surface is an arc surface, a flat surface, a stepped surface, a wavy surface, a serrated surface or an irregular concave-convex surface. 6 . 6 . The wafer cleaning apparatus according to claim 4 , further comprising an adjustment mechanism connected to the wafer placement mechanism for a circumferential radius enclosed by the support portion. 7 . 7. The wafer cleaning apparatus of claim 3, wherein each of the support portions comprises an arcuate support member, The support surfaces of the arc-shaped support members are used to support the edge of the corresponding wafer, and the support surfaces of each of the arc-shaped support members generally extend along a direction that is at an acute angle with the direction of gravity. 8 . The wafer cleaning apparatus according to claim 7 , wherein the supporting surface of the arc-shaped support member is an arc surface, a flat surface, a stepped surface, a wavy surface, a serrated surface or an irregular concave-convex surface. 9 . 9. The wafer cleaning apparatus according to any one of claims 1-8, wherein the ultrasonic transmission medium comprises deionized water or an organic solvent. 10. The wafer cleaning device according to any one of claims 1-8, further comprising: a drying chamber to contain an inert gas; and The wafer carrying mechanism is located in the drying chamber. 11. The wafer cleaning apparatus of claim 10, wherein the wafer carrier mechanism includes a rotatable member for contacting the wafer, the axis of rotation of the rotatable member being in contact with the surface of the wafer Vertical and through the center/center of gravity of the wafer.

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