Cleaning method and cleaning apparatus for chip stack assembly

Abstract

The application provides a cleaning method and a cleaning device for a chip stack assembly, the chip stack assembly comprising a wafer and a plurality of chips on the wafer, the cleaning method comprising: keeping the chip stack assembly stationary, spraying cleaning liquid on the chip stack assembly for a certain time period using a nozzle, the nozzle being inclined relative to the chip stack assembly when spraying the cleaning liquid; rotating the chip stack assembly by a preset angle and then stopping the rotation, spraying cleaning liquid on the chip stack assembly for a certain time period using the nozzle until the chip stack assembly is rotated by 360 degrees. The cleaning method provided by the application can improve the cleaning effect of residues in the gap of the chip stack assembly.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment, and more specifically, to a cleaning method and cleaning apparatus for chip stacking components. Background Technology

[0002] Chip-on-Wafer (CoW) technology refers to stacking chips together and then packaging them onto a wafer to form a chip stack assembly. CoW technology can reduce chip size, as well as power consumption and cost. During the CoW packaging process, flux is typically used to assist in the connection between the chip and the wafer. However, flux can easily remain in the gaps between the wafer and the chip, posing a challenge for subsequent cleaning.

[0003] Commonly used cleaning devices employ nozzles that move in an arc-shaped trajectory across the wafer surface while the wafer is rotating at high speed to rinse it. However, this method limits the cleaning effectiveness for stacked chip assemblies, especially for removing contaminants from the gaps between the wafer and the chips. Summary of the Invention

[0004] In view of this, this application provides a cleaning method and cleaning apparatus for chip stacking components, which can improve the cleaning effect of residues in the gaps.

[0005] In a first aspect, this application provides a cleaning method for a chip stacking assembly, comprising: keeping the chip stacking assembly stationary, spraying cleaning fluid onto the chip stacking assembly for a certain duration using a nozzle, wherein the nozzle is tilted relative to the chip stacking assembly when spraying the cleaning fluid; rotating the chip stacking assembly by a preset angle and stopping the rotation, and spraying cleaning fluid onto the chip stacking assembly for a certain duration using a nozzle until the chip stacking assembly rotates one full revolution.

[0006] Optionally, the preset angle is less than 180°.

[0007] Optionally, the size of the preset angle is positively correlated with the number and density of the chips.

[0008] Optionally, the angle between the nozzle and the vertical direction is 40°-50°.

[0009] Optionally, the nozzle is a needle nozzle.

[0010] In one possible implementation, the distance L1 between the contact point of the cleaning fluid on the chip stack assembly and the orthogonal projection point of the nozzle on the plane where the wafer is located is greater than or equal to the distance L2 between the orthogonal projection point and the center of the wafer.

[0011] In one possible implementation, if the distance L′1 between the contact point of the cleaning fluid on the chip stack assembly and the orthogonal projection point of the nozzle on the wafer plane is less than the distance L′2 between the orthogonal projection point and the center of the wafer, then each time the chip stack assembly stops rotating, the nozzle is first moved a first distance d along the direction from the orthogonal projection point to the center of the wafer, and then the nozzle is used to spray cleaning fluid for a certain period of time until the chip stack assembly rotates one revolution. The first distance... N represents the number of times the chip stack assembly stops rotating.

[0012] In one possible implementation, after the chip stack assembly has rotated one revolution, the chip stack assembly is kept rotating, and a nozzle is used to spray cleaning fluid onto the chip stack assembly for a certain period of time.

[0013] Optionally, the chip stack assembly is kept rotating at a speed of 1000rpm-2000rpm.

[0014] Secondly, this application provides a cleaning apparatus for chip stacking components, comprising:

[0015] A wafer carrier for supporting the chip stack assembly;

[0016] The nozzle is located above the chip stack assembly;

[0017] A rotary drive mechanism is used to drive the wafer carrier to rotate;

[0018] A driving device for driving the nozzle to move;

[0019] The controller, coupled to the rotary drive mechanism and the drive device, is configured as follows:

[0020] Keeping the chip stack assembly stationary, the nozzle is used to spray cleaning fluid onto the chip stack assembly for a certain period of time. During the spraying of the cleaning fluid, the nozzle is tilted relative to the chip stack assembly.

[0021] After rotating the chip stack assembly by a preset angle, stop rotating and spray cleaning fluid onto the chip stack assembly for a certain period of time using the nozzle until the chip stack assembly rotates one full revolution.

[0022] The cleaning method and apparatus for the chip stacking assembly provided in this application can effectively guide the cleaning fluid into the gap between the chip and the wafer in the chip stacking assembly, improving the cleaning effect on residues in the gap. Specifically, it consists of two rounds of rinsing. In the first round, the chip stacking assembly is stationary and the nozzle is tilted, which facilitates the cleaning fluid flowing into the gap along one side, thus ensuring sufficient contact with the residues and causing them to detach from their attached surfaces. Then, the chip stacking assembly is rotated multiple times for repeated rinsing in different areas, ensuring that the gaps in each area of ​​the chip stacking assembly are rinsed. In the second round, the centrifugal force generated by the high-speed rotation effectively removes residues from the surface of the chip stacking assembly. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a chip stacking component cleaning device provided according to an embodiment of this application.

[0024] Figure 2A and Figure 2B This is a schematic diagram of the cleaning trajectory of the nozzle on the surface of the chip stacking assembly in a chip stacking assembly cleaning device according to an embodiment of this application.

[0025] Figure 3 This is a schematic flowchart of a chip stacking component cleaning method provided according to an embodiment of this application.

[0026] Figure 4 This is a schematic flowchart of another chip stacking component cleaning method provided according to an embodiment of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0029] In this application, the reference to "embodiment" means that a specific feature, component, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0030] Figure 1 A schematic diagram of a chip stacking assembly cleaning device provided in this application is shown. Figure 1 As shown, the cleaning device mainly includes a cavity 1, a wafer carrier 10, and a nozzle 30. The wafer carrier 10 and the nozzle 30 are disposed within the cavity 1. The wafer carrier 10 is used to support the chip stack assembly 20. The wafer carrier 10 is connected to a rotary drive mechanism (not shown) via a rotating shaft 11. The rotary drive mechanism can drive the wafer carrier 10 to rotate, thereby driving the chip stack assembly 20 to rotate. The nozzle 30 is located above the chip stack assembly 20 and is used to spray cleaning fluid 31 onto the chip stack assembly 20 for cleaning, ultimately forming an arc-shaped cleaning trajectory on the surface of the chip stack assembly 20. The cleaning fluid 31 may include deionized water, pure water, etc.

[0031] The chip stack assembly 20 is a three-dimensional integrated circuit board comprising a wafer w and a plurality of chips 22 arranged in an array. A plurality of connectors 21 are provided between the chips 22 and the wafer w, creating a gap between the wafer w and the chips 22. In one embodiment, the connectors 21 are metal balls used to solder the wafer w and the chips 22. During the process of connecting the wafer w and the chips 22 using flux, flux flows back into the gap between the chips 22 and the wafer w, leaving residue 23. The cleaning apparatus provided in this application is used to remove the residue 23 in the gap between the chips 22 and the wafer w.

[0032] It should be noted that the nozzle 30 moves in an arc-shaped trajectory above the chip stack assembly 20 via a swing arm (not shown). One end of the swing arm is connected to the nozzle 30, and the other end is a pivot point, which is a fixed point. The swing arm can rotate around the pivot point under the drive of a drive device (e.g., a motor, not shown), thereby moving the nozzle 30. In one embodiment, the length of the swing arm is not less than the radius of the wafer w to ensure that the cleaning fluid can cover the entire area of ​​the chip stack assembly 20 after the cleaning step. The drive device for the swing arm can be found in related technologies and will not be described in detail here.

[0033] Correspondingly, Figure 3 and Figure 4 Methods for cleaning chip stack assemblies using the cleaning apparatus described above are illustrated.

[0034] Figure 3 This is a schematic diagram of a chip stacking assembly cleaning method 10 provided in this application. As shown in the figure, the method 10 includes the following steps:

[0035] S11: Tilting and fixing the nozzle in the vertical direction.

[0036] See Figure 1 Because the nozzle 30 is tilted in the vertical direction, there is an angle between the nozzle 30 and the chip stack assembly 20 (i.e., an angle between the nozzle 30 and the gap). In other words, the orientation of the nozzle 30 and its position relative to the vertical direction allow the cleaning fluid 31 provided by the nozzle 30 to be sprayed into the gap during subsequent cleaning. This effectively guides the cleaning fluid 31 into the gap between the wafer w and the chip 22. The tilt angle of the nozzle 30 is related to the height of the gap between the wafer w and the chip 22 and the length of the spacing between adjacent chips 22. Preferably, the angle between the nozzle 30 and the vertical direction is 40° to 50°, for example, 40°, 42°, 45°, 46°, 48°, or 50°.

[0037] S12: Keep the chip stack assembly stationary, move the nozzle above the chip stack assembly to perform the first rinse on the chip stack assembly.

[0038] See Figure 1 and Figure 2A During the first rinse, nozzle 30 moves around the pivot point of the swing arm, spraying cleaning fluid 31 back and forth between point A on one side of wafer w and point B on the other side. The movement of nozzle 30 forms an arc-shaped trajectory on the surface of wafer w. Cleaning fluid 31 in an arc-shaped trajectory The contact point of the cleaning fluid 31 is C, and the orthogonal projection point of the rotation point on the plane where the wafer w is located is D. The distance between the contact point C and the orthogonal projection point D is L1. The distance L1 is greater than or equal to the distance L2 between the orthogonal projection point D and the center R of the wafer w. This allows the sprayed cleaning fluid 31 to flow through more gaps between wafer w and chip 22, ensuring that after repeated first rinsing by rotating the wafer w multiple times to divide the area, the multiple arc-shaped trajectories formed by the movement of the nozzle 30 can cover the entire surface of the wafer w. That is, the cleaning fluid 31 can clean the entire area of ​​the chip stack assembly 20. In addition, during rinsing, the chip stack assembly 20 remains stationary and the nozzle 30 is tilted relative to the gap between the wafer w and chip 22. This facilitates the cleaning fluid 31 to flow into the gap along one side of the gap and fully contact the residue 23 in the gap, causing the residue 23 to detach from its attached surface.

[0039] The duration of the first rinse is generally 60-500 seconds. For example, the duration can be 60 seconds, 100 seconds, 200 seconds, 300 seconds, 400 seconds, or 500 seconds.

[0040] After the first rinse is completed, the spraying from the nozzle is stopped. After spraying stops, the nozzle can return to its initial position, i.e., away from the chip stack assembly and not overlapping with the chip stack assembly in the vertical direction, or it can remain above the chip stack assembly; this application does not limit this.

[0041] In some embodiments, the nozzle 30 is a needle nozzle, which makes the ejected cleaning fluid 31 a high-pressure column. The high-pressure columnar fluid flow can concentrate pressure to peel the residue 23 off the chip stack assembly 20, thereby improving the cleaning effect of the residue 23 in the gap.

[0042] S13: Rotate the chip stack assembly to a preset angle and then stop rotating. Repeat step S12 until the chip stack assembly has rotated one full circle.

[0043] The preset angle is less than 180°. The size of the preset angle is positively correlated with the number and density of chips on the wafer. The more chips there are and the denser they are arranged, the smaller the preset angle will be. This allows the wafer to stop multiple times during one rotation to rinse the chips from different positions.

[0044] After completing step S13, the nozzle 30 can form multiple arc-shaped cleaning tracks that are centrally symmetrical about the center R on the surface of the chip stack assembly 20. Since the area of ​​the chip stack assembly 20 is cleaned each time and each arc-shaped track covers different radial areas including the center R, these arc-shaped tracks cooperate to fill the cleaning blind spots between each other, and finally ensure that the gaps in each area of ​​the chip stack assembly 20 are thoroughly rinsed.

[0045] It should be noted that the duration of each spray of cleaning fluid from nozzle 30 can be the same or different.

[0046] S14: While keeping the chip stack assembly rotating, move the nozzle above the chip stack assembly to perform a second rinse.

[0047] The second rinse targets any residues that may remain on the surface of the chip stack assembly after the first rinse. The duration of the second rinse is typically 300-500 seconds. For example, the duration can be 300s, 350s, 400s, 450s, or 500s. The duration of the first rinse can be the same as or different from the duration of the second rinse. In step S14, the rotation speed of the chip stack assembly is 1000rpm-2000rpm, for example, 1000rpm, 1200rpm, 1500rpm, 1600rpm, 1800rpm, or 2000rpm. Under the centrifugal force generated by the high-speed rotation, the cleaning fluid quickly flows through the chip stack assembly, rapidly cleaning the residues remaining on the surface of the chip stack assembly, effectively removing the residues after the first rinse, and further improving the cleaning effect.

[0048] Figure 4 This is a schematic diagram of another chip stacking component cleaning method 20 provided in this application. As shown in the figure, method 20 includes the following steps:

[0049] S21: Tilt and fix the nozzle in the vertical direction.

[0050] For details, please refer to the above description of step S11, which will not be repeated here.

[0051] S22: Keep the chip stack assembly stationary and move the nozzle above the chip stack assembly to perform a third rinse.

[0052] See Figure 1 and Figure 2B During the third rinse, nozzle 30 moves around the pivot point of the swing arm, spraying cleaning fluid 31 back and forth between point A′ on one side of wafer w and point B′ on the other side. The movement of nozzle 30 forms an arc-shaped trajectory on the surface of wafer w. Cleaning fluid 31 in an arc-shaped trajectory The liquid application point on is C', the orthographic projection point of the rotation point on the plane where the wafer w is located is D, the distance between the liquid application point C' and the orthographic projection point D is L'₁, and the distance L'₁ is smaller than L₂ which is the distance between the orthographic projection point D and the center R of the wafer w. When the distance L'₁ is smaller than the distance L₂, the area covered by a single rinsing may be relatively small. Even if subsequent multiple rotations are performed to repeat the third rinsing in divided areas, the finally formed multiple arc-shaped trajectories cannot cover the entire surface of the wafer w, for example, cannot cover the central area of the wafer w, thereby failing to ensure that all the chip stack assemblies 20 are cleaned. The subsequent steps of the present application can solve this problem, and for details, please refer to the following description.

[0053] The duration of the third rinsing is generally 60-500s. For example, the duration is 60s, 100s, 200s, 300s, 400s or 500s.

[0054] After the third rinsing is completed, the nozzle stops spraying. After stopping spraying, the nozzle can return to the initial position, that is, it is far away from the chip stack assembly and does not overlap with the chip stack assembly in the vertical direction, or it can stay above the chip stack assembly, which is not limited in the present application.

[0055] S23: rotating the chip stack assembly to a preset angle and then stopping the rotation, moving the nozzle by a first distance d along the direction from the orthographic projection point to the center of the wafer, repeating step S22 until the chip stack assembly rotates one full circle.

[0056] wherein, the first distance N is the number of times the chip stack assembly stops rotating.

[0057] optionally, the specific process of moving the nozzle by the first distance d along the direction from the orthographic projection point D to the wafer center R comprises: keeping the rotation point stationary, extending the nozzle by the first distance d along the direction from the orthographic projection point D to the wafer center R, or horizontally moving the rotation point by the first distance d along the direction from the orthographic projection point D to the wafer center R, so as to drive the nozzle to move by the first distance d, which is not limited in the present application.

[0058] for the setting of the preset angle, reference can be made to the description of step S13 in the foregoing, which will not be repeated here.

[0059] in step S23, with each stop of rotation of the chip stack assembly, the nozzle moves by the first distance d and then step S22 is performed. This not only gradually increases the distance between the liquid application point and the orthographic projection point, but also expands the coverage area of the cleaning fluid, so that the rinsing areas at different positions on the surface of the chip stack assembly can complement each other. In particular, the cleaning area is limited at the beginning due to L'₁ < L₂, and the arc-shaped trajectory While the central area of ​​the chip stack assembly wasn't covered, the subsequent arc-shaped trajectory formed through multiple rotations and nozzle movements after each rotation covered previously unwashed areas. Furthermore, the initial distance calculation considered the number of times the chip stack assembly stopped rotating, ensuring that the distance between the cleaning fluid contact point C′ and the projection point D was uniformly adjusted during each rinse. This not only ensured the uniformity of the cleaning fluid distribution but also guaranteed that the entire surface of the chip stack assembly was thoroughly and evenly cleaned after multiple rotations and nozzle movements.

[0060] It should be noted that the duration of each spray of cleaning fluid from nozzle 30 can be the same or different.

[0061] S24: While keeping the chip stack assembly rotating, move the nozzle above the chip stack assembly to perform a fourth rinse.

[0062] For details, please refer to the previous explanation of step S14, which will not be repeated here.

[0063] The cleaning device also includes a controller coupled to the rotary drive mechanism and the drive device, the controller being configured to: keep the chip stack assembly stationary, move the nozzle above the chip stack assembly to rinse the chip stack assembly, wherein the nozzle is tilted relative to the chip stack assembly during rinsing;

[0064] After rotating the chip stack assembly by a preset angle, stop rotating and move the nozzle to rinse the chip stack assembly again until the chip stack assembly has rotated one full revolution.

[0065] It should be noted that the various components mentioned above work together through electrical connections. For details, please refer to the prior art, which will not be repeated here.

[0066] The cleaning method and apparatus for the chip stacking assembly provided in this application can effectively guide the cleaning fluid into the gap between the chip and the wafer in the chip stacking assembly, improving the cleaning effect on residues in the gap. Specifically, it consists of two rounds of rinsing. In the first round, the chip stacking assembly is stationary and the nozzle is tilted, allowing the cleaning fluid to flow into the gap along one side, thus fully contacting the residues and causing them to detach from their attached surfaces. Then, the chip stacking assembly is rotated multiple times for repeated rinsing in different areas, ensuring that the gaps in each area of ​​the chip stacking assembly are cleaned. In the second round, the centrifugal force generated by the high-speed rotation effectively removes residues from the surface of the chip stacking assembly.

[0067] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cleaning method for a chip stacking assembly, the chip stacking assembly comprising a wafer and a plurality of chips located on the wafer, characterized in that, The cleaning method includes: Keep the chip stack assembly stationary, and spray cleaning fluid onto the chip stack assembly using a nozzle for a certain period of time. While spraying the cleaning fluid, the nozzle is tilted relative to the chip stack assembly. After rotating the chip stack assembly by a preset angle, stop rotating and spray cleaning fluid onto the chip stack assembly for a certain period of time using the nozzle until the chip stack assembly rotates one full revolution.

2. The cleaning method for chip stacking components according to claim 1, characterized in that, The distance L1 between the contact point of the cleaning fluid on the chip stack assembly and the orthogonal projection point of the nozzle on the plane of the wafer is greater than or equal to the distance L2 between the orthogonal projection point and the center of the wafer.

3. The cleaning method for chip stacking components according to claim 1, characterized in that, If the distance L′1 between the contact point of the cleaning fluid on the chip stack assembly and the orthogonal projection point of the nozzle on the plane where the wafer is located is less than the distance L2 between the orthogonal projection point and the center of the wafer, then each time the chip stack assembly stops rotating, the nozzle is first moved a first distance d along the direction from the orthogonal projection point to the center of the wafer, and then the cleaning fluid is sprayed with the nozzle for a certain period of time until the chip stack assembly rotates one revolution, wherein the first distance... N represents the number of times the chip stack assembly stops rotating.

4. The cleaning method for chip stacking components according to claim 1, characterized in that, The preset angle is less than 180°.

5. The cleaning method for chip stacking components according to claim 1, characterized in that, The size of the preset angle is positively correlated with the number and density of the chips.

6. The cleaning method for chip stacking components according to claim 1, characterized in that, It also includes maintaining the chip stack assembly in rotation after it has rotated one revolution, and spraying cleaning fluid onto the chip stack assembly for a certain period of time using the nozzle.

7. The cleaning method for chip stacking components according to claim 6, characterized in that, The rotation speed of the chip stack assembly is 1000rpm-2000rpm.

8. The cleaning method for chip stacking components according to claim 1, characterized in that, The angle between the nozzle and the vertical direction is 40°-50°.

9. The cleaning method for chip stacking components according to claim 1, characterized in that, The nozzle is a needle nozzle.

10. A cleaning apparatus for a chip stack assembly, comprising: A wafer carrier for supporting the chip stack assembly; The nozzle is located above the chip stack assembly; A rotary drive mechanism is used to drive the wafer carrier to rotate; A driving device for driving the nozzle to move; The controller, coupled to the rotary drive mechanism and the motor, is configured as follows: The wafer carrier is kept stationary, and the nozzle is controlled to spray cleaning fluid onto the chip stack assembly for a certain period of time. When spraying the cleaning fluid, the nozzle is tilted relative to the chip stack assembly. The wafer carrier drives the chip stack assembly to rotate at a preset angle and then stops rotating. The nozzle is then controlled to spray cleaning fluid onto the chip stack assembly for a certain period of time until the chip stack assembly rotates one revolution.

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