Device and method for detecting orderliness of wafer pair by wafer bonding machine

Abstract

The invention discloses a device and a method for detecting irregularity of wafer pairs on a wafer bonder, the bonder is provided with a workbench used for bearing the wafer pairs, an ejector pin assembly used for lifting the wafer pairs is arranged in the workbench, at least two ejector pins in the ejector pin assembly are provided with weighing elements, and the weighing elements are arranged on the ejector pins. Measuring the gravity center and the weight of the wafer pair through the weighing element; each weighing element generates a corresponding unit weight numerical value G1, G2..., and the center-of-gravity position O and the total weight G of the wafer pair are determined through the position of the ejector pin provided with the weighing element and the corresponding unit weight numerical value; and when the deviation between any numerical value of the gravity center position O or the total weight G of the wafer pair and a preset numerical value is greater than a set range, the wafer bonding machine stops running. According to the method, whether the wafer pairs are stacked orderly or not is detected through the center-of-gravity deviation of the wafer pairs, the method is simple and clear, whether the wafer pairs are irregular or not can be accurately detected, and wafer scrapping is avoided.

Description

Technical Field

[0001] The present invention relates to the field of wafer processing technology, and in particular to a device and method for a wafer bonding machine to detect whether a wafer pair is aligned, so as to avoid wafer scrapping due to wafer bonding failure and reduce losses. Background Art

[0002] Direct wafer bonding technology is the most popular bonding method in recent years. It is also the most difficult bonding method with the highest requirements on silicon wafer surface morphology and surface treatment process. Therefore, bonding failures often occur.

[0003] Direct wafer bonding generally refers to the process of bonding two wafers together. When a bond failure occurs, both wafers are typically scrapped, resulting in significant cost losses. Failures can be caused by issues with the bonding machine or poor silicon wafer surface topography. However, if the bonding machine can detect bond failures and shut down immediately, further losses can be avoided.

[0004] There are two situations in which bonding fails: 1. See Figure 1 As shown, at this time, the upper wafer 01 and the lower wafer 02 are misaligned, resulting in the wafer pair not being stacked neatly; 2. See Figure 2 As shown, at this time, the upper wafer 01 and the lower wafer 02 are peeled off, that is, the two wafers are seriously offset, resulting in the upper wafer 10 being separated from the lower wafer 02.

[0005] Both of the above situations will cause the bonding of the wafer pair to fail and result in the wafer being scrapped. In addition, an analysis of the time and location of wafer pair bonding failure shows that the current wafer pair bonding failure mainly occurs at the following two time points: 1. During the wafer bonding process, wafer dislocation and peeling may occur due to machine or wafer abnormalities; 2. During the wafer pair transfer process, the robot may misalign or peel the wafers due to vibration or inertia; Through research on bonding failures, the inventors believe that these two situations have a common phenomenon: relative to the neat wafer pair, the center of gravity of the wafer pair that has been misaligned or peeled has shifted. Therefore, as long as it can be detected that the center of gravity offset of the wafer pair exceeds a certain set value, it can be determined that there is a problem with the wafer pair, and the wafer bonding machine will stop working immediately to avoid losses.

[0006] See patent document no. CN117612958 A Chinese invention patent application, which discloses "a wafer defect detection method and equipment", which adopts the technical scheme is: including: obtaining the weight data, thickness data and detection image of the wafer to be detected;Obtain the weight parameter and thickness parameter of the standard wafer;Obtain the defect image of each defect wafer with brightness information, and establish a defect database according to the defect image of the defect wafer with brightness information;The third detection data with brightness value information is input into the defect database, and the similar image is obtained by traversing the defect database;Read the defect information parameters carried by the similar image, and obtain the specific defect type of the wafer to be detected. The patent document uses the detection image, weight and thickness data of the wafer to be detected, the weight and thickness parameters of the standard wafer and the defect image of the defect wafer to screen out wafers with different defect types. However, it can be seen that the technical scheme only measures the weight of the wafer, detects whether a single wafer has defects, and cannot detect whether the wafer is stacked in place.

[0007] See patent documents CN104900552A and CN117870832A, which propose to weigh the wafer to detect whether the wafer has defects. These technical schemes do not propose a technical scheme to detect whether the wafer is stacked in place.

[0008] In view of the above, the present inventors have proposed the following technical solutions in view of the deficiencies in the prior art. SUMMARY

[0009] The technical problem to be solved by the present application is to overcome the deficiencies of the prior art and provide a device and method for detecting whether the wafer pair is in place in a wafer bonding machine, so as to avoid the scrapping of wafer pieces and reduce losses.

[0010] In order to solve the above technical problems, the device for detecting whether the wafer pair is in place in the wafer bonding machine adopts the following technical scheme: the wafer pair is two stacked wafer pieces processed by the bonding machine, the bonding machine has a worktable for carrying the wafer pair, a needle assembly for lifting the wafer pair is arranged in the worktable, at least two needles in the needle assembly are provided with a weighing element, and the center of gravity and weight of the wafer pair are measured by the weighing element.

[0011] Further, in the technical scheme of the above device, the bonding machine further comprises a mechanical hand for transferring the wafer pair, the mechanical hand has a supporting plate for carrying the wafer pair, and a weighing element is arranged on the supporting plate.

[0012] Further, in the technical scheme of the above device, the bonding machine further comprises a mechanical hand for transferring the wafer pair, the mechanical hand has a supporting plate for carrying the wafer pair, and a weighing element is arranged on the supporting plate.

[0013] Further, in the technical scheme of the above device, the line connecting the two top pins provided with the load-bearing elements corresponds to the diameter position of the wafer pair.

[0014] The method for detecting whether the wafer pair is in order in the wafer bonding machine in the present application adopts the technical scheme that: the wafer pair is two stacked wafer pieces processed by the bonding machine, the bonding machine has a worktable for carrying the wafer pair, a top pin assembly for lifting the wafer pair is arranged in the worktable, at least two top pins in the top pin assembly are provided with load cells; the method for detecting whether the wafer pair is in order is that: when the wafer pair is placed on the top pin assembly of the worktable, each load cell will generate a corresponding unit weight value: G1, G2, …; the center of gravity position O and the total weight G of the wafer pair are determined through the position of the top pin provided with the load cell and the corresponding unit weight value; when any one of the center of gravity position O or the total weight G of the wafer pair deviates from the preset value by more than a set range, the wafer bonding machine stops running.

[0015] Further, in the technical scheme of the above detection method, the distance between the top pins provided with the load cells in the top pin assembly does not exceed the diameter of a single wafer piece.

[0016] Further, in the technical scheme of the above detection method, the number of top pins provided with the load cells in the top pin assembly is three, and the three top pins provided with the load cells are not located on the same straight line, i.e., the top pins provided with the load cells determine a plane.

[0017] Further, in the technical scheme of the above detection method, the bonding machine further includes a robot for transferring the wafer pair, the robot has a supporting plate for carrying the wafer pair, and a load cell is arranged on the supporting plate; when the wafer pair is placed on the supporting plate and enters the bonding machine or is taken out of the bonding machine, the total weight G of the wafer pair is obtained through the load cell arranged on the supporting plate; when any one of the total weight G of the wafer pair deviates from the preset value by more than a set range, the wafer bonding machine stops running.

[0018] Further, in the technical scheme of the above detection method, at least two load cells are arranged on the supporting plate; when the wafer pair is placed on the supporting plate, each load cell on the supporting plate will generate a corresponding unit weight value: g1, g2, …; the center of gravity position and the total weight of the wafer pair are determined through the position of the top pin provided with the load cell and the corresponding unit weight value; when any one of the center of gravity position or the total weight of the wafer pair deviates from the preset value by more than a set range, the wafer bonding machine stops running.

[0019] After adopting the above technical scheme, the present application has the following beneficial effects compared with the prior art: Firstly, the present application sets a weighing element on at least two thimbles in the thimble assembly aiming at the main position of wafer pair bonding failure, so as to determine the center of gravity position O and total weight G of the current wafer pair; when any one of the center of gravity position O or the total weight G of the wafer pair deviates from the preset value by more than the set range, the wafer bonder stops running. The wafer pair center of gravity deviation is used to detect whether the wafer pair is stacked neatly, which is simple and clear, and can accurately detect whether the wafer pair is not neat, so as to immediately stop the wafer bonder, avoiding wafer scrap.

[0020] Secondly, the present application detects the center of gravity and simultaneously detects the weight of the wafer pair by the weighing element, when any wafer in the wafer pair has a defect, causing the weight to deviate, which will also trigger the wafer bonder to stop.

[0021] Finally, aiming at the main position of wafer pair bonding failure, the present application sets a weighing element on the pallet of the mechanical hand used for transferring the wafer pair, realizing omnidirectional detection. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the wafer pair in the first case of existing bonding failure; Figure 2 is a schematic diagram of the wafer pair in the second case of existing bonding failure; Figure 3 is a structural schematic diagram of the workbench in the wafer bonder in the embodiment one of the present application; Figure 4 is a structural schematic diagram of the wafer bonder and the mechanical hand in the embodiment two of the present application. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with specific embodiments and drawings.

[0024] The present application relates to a device and method for detecting wafer pair misalignment on a wafer bonder.

[0025] See Figure 3 The wafer pair 1 in the present application is two stacked wafer pieces 11, 12. The two wafer pieces are the same in size and size specification, and are bonded by a wafer bonder. During bonding, the two stacked wafer pieces 11, 12 need to be stacked neatly.

[0026] The bonding machine has a workbench 2 for carrying a wafer pair, and a pin assembly 3 for lifting the wafer pair is provided on the workbench 2. The pin assembly 3 has a plurality of pins 30 distributed along the surface of the workbench 2. All the pins 30 are raised or lowered by a piston or a mechanical mechanism (such as a cam mechanism). When the wafer pair 1 is sent in or removed, the pin assembly 3 is used to lift or place the wafer pair 1 on the surface of the workbench 2.

[0027] In the first embodiment of the present invention, weighing elements 4 are installed on at least two ejector pins 30. Determining an object's center of gravity typically requires at least two weighing elements. By using two weighing elements 4, the weight distribution of the object in different directions can be measured, thereby calculating the center of gravity. Specifically, weighing elements are installed at different locations on the object, the values ​​of each weighing element are recorded, and the center of gravity position is calculated based on these readings.

[0028] The following describes the method for detecting whether wafer pairs are aligned in the first embodiment by taking the case where two ejector pins 30 in the ejector pin assembly 3 are provided with weighing elements 4 as an example.

[0029] First, the standard center of gravity position Op and the standard total weight Gp of the wafer pair 1 in the stacked and aligned state are determined as reference standards, and the corresponding error range is set.

[0030] Then, when the wafer pair 1 is placed on the ejector pin assembly 3 of the workbench 2, each weighing element 4 in the ejector pin 30 with a weighing element 4 will generate a corresponding unit weight value: G1, G2. By setting the position of the ejector pin with a weighing element and the corresponding unit weight value, the center of gravity position O and the total weight G of the wafer pair 1 are determined.

[0031] Next, perform a numerical comparison. Compare the center of gravity position O and total weight G of the current wafer pair 1 with the standard center of gravity position Op and standard total weight Gp. The following results will be obtained: 1. If the deviations between the center of gravity position O and the total weight G of the current wafer pair 1 and the standard center of gravity position Op and the standard total weight Gp are within the set error range, it means that the current wafer pair is stacked neatly and there is no abnormality, and the wafer bonder does not stop working; 2. If the deviation between the center of gravity position O of the current wafer pair 1 and the standard center of gravity position Op is within the set error range, but the deviation between the total weight G and the standard total weight Gp is ​​greater than the set error range, it means that the current wafer pair is stacked neatly, but at least one wafer itself has a defect. At this time, the wafer bonder stops working; 3. The center of gravity of the current wafer pair O deviates from the standard center of gravity Op by more than a set error range, but the value of the total weight G deviates from the standard total weight Gp by within a set error range, indicating that the current wafer pair is not stacked neatly, and the wafer bonder stops working; 4. The center of gravity O and the value of the total weight G of the current wafer pair deviate from the standard center of gravity Op and the standard total weight Gp by more than a set error range, indicating that the current wafer pair is not stacked neatly, or even the wafer itself has defects, and the wafer bonder stops working.

[0032] Finally, according to the above situation, the wafer bonder makes a corresponding response.

[0033] In combination Figure 3 As shown in the figure, when setting the position of the needle 30 with the weighing element 4, the preferred solution is to place the two needles 30 with the weighing element 4 as close to the edge of the wafer pair 1 as possible. For example, the line connecting the two needles 30 with the weighing element 4 is approximately located at the diameter position of the wafer pair 1, and the distance between the two needles 30 with the weighing element 4 does not exceed the diameter of a single wafer. Since the position of the wafer pair 1 is relatively fixed when it is moved by the robot to the position above the workbench 2, if the wafer pair 1 deviates in position, it will cause a needle 30 with a weighing element 4 to fail to detect the value, at which point it is determined to be abnormal, and the wafer bonder stops working. In addition, placing the needle 30 with the weighing element 4 as close to the edge of the wafer pair 1 as possible can also more accurately determine the deviation of the center of gravity.

[0034] In the present application, the needle 30 needs to lift the wafer pair, and at least three needles 30 are usually provided in the needle assembly 3. In order to facilitate design, a weighing element 4 can be provided on each of the three needles 30. Except for the different center of gravity calculation algorithms, the detection methods of the two are exactly the same, which will not be described here.

[0035] See Figure 4 As shown in the figure, this is the second embodiment of the present application. According to the background art, abnormalities can also occur during the movement of the wafer pair by the robot. Therefore, based on the first embodiment, the weighing element 4 is also provided on the robot 5 used by the bonder to move the wafer pair 1. The robot 5 has a supporting plate 50 for carrying the wafer pair 1, and the weighing element 4 is provided on the supporting plate 50.

[0036] Similar to the setting method of the top pin assembly 3 in the first embodiment, the supporting plate 50 is provided with at least two weighing elements 4. When the wafer pair is placed on the supporting plate, each weighing element on the supporting plate will generate a corresponding unit weight value: g1, g2. By setting the position of the weighing element and the corresponding unit weight value, the center of gravity position O1 of the wafer pair 1 on the supporting plate 5 and the total weight G1 are determined. When any one of the center of gravity position O1 or the total weight G1 of the wafer pair deviates from the preset value beyond the set range, the wafer bonding machine stops running. The specific judgment method is the same as that described in the first embodiment, which will not be described here.

[0037] Of course, the above only describes specific embodiments of the present application, and is not intended to limit the scope of the present application. Any equivalent changes or modifications made to the structure, features and principles described in the patent application scope of the present application shall be included in the patent application scope of the present application.

Claims

1. A wafer bonder is a device that detects the alignment of wafer pairs. The wafer pair is two stacked wafers that are bonded together by the bonder. The bonder has a worktable for supporting the wafer pair, and a pin assembly is provided on the worktable for lifting the wafer pair. The device is characterized by: In the ejector pin assembly, at least two ejector pins are provided with weighing elements, and the center of gravity and weight of the wafer pair are measured by the weighing elements.

2. The device for detecting whether wafer pairs are aligned in a wafer bonding machine according to claim 1, characterized in that: The bonding machine further comprises a robot for transferring the wafer pair, the robot having a support plate for carrying the wafer pair, and a weighing element is arranged on the support plate.

3. The device for detecting whether wafer pairs are aligned in a wafer bonding machine according to claim 1 or 2, characterized in that: The line connecting the two ejector pins of the load-bearing element corresponds to the diameter position of the wafer pair.

4. The device for detecting whether wafer pairs are aligned in a wafer bonding machine according to claim 1 or 2, characterized in that: The two top pins of the load-bearing element correspond to the edge position areas of the wafer.

5. A method for detecting whether a wafer pair is aligned on a wafer bonder, wherein the wafer pair is two stacked wafers bonded by a bonding machine, the bonding machine having a worktable for supporting the wafer pair, and a pin assembly for lifting the wafer pair disposed on the worktable, wherein: In the ejector pin assembly, at least two ejector pins are provided with weighing elements; The method for detecting whether a wafer pair is aligned is as follows: after the wafer pair is placed on the ejector pin assembly of the workbench, each weighing element will generate a corresponding unit weight value: G1, G2, ..., and the center of gravity position O and the total weight G of the wafer pair are determined by the position of the ejector pins provided with the weighing elements and the corresponding unit weight values; When the deviation between the center of gravity position O of the wafer pair or the total weight G and the preset value exceeds the set range, the wafer bonding machine stops running.

6. The method for detecting whether wafer pairs are aligned by a wafer bonding machine according to claim 5, characterized in that: In the ejector pin assembly, the distance between the ejector pins provided with weighing elements does not exceed the diameter of a single wafer.

7. The method for detecting whether wafer pairs are aligned by a wafer bonding machine according to claim 5, characterized in that: In the ejector pin assembly, there are three ejector pins provided with weighing elements, and the three ejector pins provided with weighing elements are not located on the same straight line, that is, the ejector pins provided with weighing elements define a plane.

8. The method for detecting whether wafer pairs are aligned by a wafer bonding machine according to any one of claims 5 to 7, characterized in that: The bonding machine further comprises a manipulator for transferring the wafer pair, the manipulator having a support plate for carrying the wafer pair, and a weighing element being arranged on the support plate; When the wafer pair is placed on the pallet and enters the bonding machine or is taken out of the bonding machine, the total weight G of the wafer pair is obtained by the weighing element set on the pallet; when the deviation between the total weight G of the wafer pair and the preset value is greater than the set range, the wafer bonding machine stops running.

9. The method for detecting whether wafer pairs are aligned by a wafer bonding machine according to claim 8, wherein: At least two weighing elements are provided on the support plate; When the wafer pair is placed on the pallet, each weighing element on the pallet will generate a corresponding unit weight value: g1, g2... The center of gravity position and total weight of the wafer pair are determined by the position of the weighing element and the corresponding unit weight value; when the deviation between the center of gravity position or the total weight of the wafer pair and the preset value exceeds the set range, the wafer bonding machine stops running.

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