Confirm the control method for the lifting parameters of the wafer lifting device
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- ARDENTEC CORP
- Filing Date
- 2025-01-15
- Publication Date
- 2026-08-01
AI Technical Summary
Conventional control methods for setting the rise parameter of a wafer lifting device are inefficient, requiring numerous small movements and failing to improve efficiency effectively due to the use of a minimum movement parameter that limits the movement range.
A control method that utilizes step movement parameters greater than the minimum movement parameter, involving steps to detect contact signals from both the longest and shortest probes, allowing for larger increments in wafer lifting, thereby reducing the overall number of operations required to set the optimized rise parameter.
Significantly reduces the number of operations needed to confirm the optimized rise parameter, enhancing efficiency and ensuring probes and wafers are within safe stress and pressure limits, preventing damage.
Smart Images
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Abstract
Description
[Technical Field]
[0001] This invention relates to a control method, and in particular to a control method for confirming the rising parameters of a wafer lifting device. [Previous Technology]
[0002] A computer in a wafer testing device has a preset rise parameter, which is a movement distance value and its unit can be micrometers (μm). The following first briefly describes how the wafer testing device uses this rise parameter, and then explains the conventional control method for obtaining this rise parameter.
[0003] In actual wafer testing production, the wafer testing equipment places a wafer to be tested on a wafer chuck, wherein the wafer chuck is mounted on a lifting device, and the computer can control the lifting device to operate and record position information. In the initial state, the wafer to be tested and the wafer chuck are located in a starting position, which is located below a probe card. At this time, the wafer to be tested has not yet contacted the probes of the probe card. The probes of the probe card are not completely of equal length, with a longest probe and a shortest probe, and the length difference between the longest probe and the shortest probe can be tens of micrometers (μm) or greater.
[0004] The computer controls the lifting device to raise the wafer under test from the starting position until the computer detects the contact signal between the longest probe and the wafer under test, thus obtaining a reference height position information. Then, the computer controls the lifting device according to the rising parameters to raise the wafer under test directly from the reference height by the corresponding distance and position it, so that all probes of the probe card (including the shortest probe) can contact the wafer under test. The computer can then transmit test signals and receive measurement signals to the wafer under test through the probe card. After completing the test of the wafer under test, the computer can control the lifting device to lower the wafer under test back to the starting position, preparing for the test of the next wafer under test.
[0005] If the moving distance value of the rise parameter is set appropriately, after the computer rises the wafer under test according to the rise parameter, all probes of the probe card (including the shortest probe) can effectively contact the wafer under test. At this time, the stress and pressure borne by the probes and the wafer under test are still within the tolerance range, and will not damage the probes and the wafer under test. Conversely, if the moving distance value of the rise parameter is set too short, after the computer rises the wafer under test according to the rise parameter, the shorter probes (including the shortest probe) may not contact the wafer under test, and the wafer test cannot be performed correctly; or if the moving distance value of the rise parameter is set too long, after the computer rises the wafer under test according to the rise parameter, although the probes and the wafer under test will be in contact, they will be subjected to excessive stress and pressure, which may lead to damage to the probes and the wafer under test.
[0006] It is evident that the setting of this rise parameter is crucial for wafer testing. For the conventional control method of obtaining this rise parameter, please refer to Figure 6, which is explained below.
[0007] Step S11: A test wafer is placed on the wafer chuck. The computer controls the lifting device to move up the test wafer from the starting position until the computer detects the contact signal between the longest probe and the test wafer and defines the current position information as a reference height.
[0008] Step S12: The computer determines whether the contact signal between the shortest probe and the test wafer has been detected.
[0009] Step S13: If the computer does not detect the contact signal of the shortest probe, the computer controls the lifting device to operate according to a minimum movement parameter to raise the test wafer by a distance and return to step S12. The minimum movement parameter is a movement distance value and its unit can be micrometer (μm). The minimum movement parameter is a preset value and is used to limit the lower limit of the movement distance of the test wafer. The minimum movement parameter depends on the specifications of the wafer testing equipment.
[0010] It is understood that as the aforementioned steps S12 and S13 are repeatedly executed, the position of the test wafer continues to rise step by step with the magnitude of the minimum movement parameter until the computer detects the contact signal of the shortest probe (i.e. the judgment result of step S12 is "yes"), and enters step S14: the computer defines the position information corresponding to the judgment of step S12 as "yes" as a final height, and the computer calculates a height difference between the final height and the reference height, and stores the value of the height difference as the rise parameter.
[0011] An example is given below. The minimum movement parameter is 1. After the conventional control method brings the position of the test wafer to the reference height through step S11, the position of the test wafer rises in increments of 1 (μm) during the repeated execution of steps S12 and S13. Assuming that steps S12 and S13 are repeated 42 times, the computer detects the contact signal of the shortest probe and defines the current position information as the final height. That is, after the 42nd rise, the height difference between the position (final height) of the test wafer and the reference height is 42 (μm). Therefore, the computer stores the aforementioned 42 (μm) as the rise parameter.
[0012] However, due to the limited movement range of the minimum movement parameter, the conventional control method only raises the test wafer by a distance according to the minimum movement parameter in step S13. The movement range is too short each time, resulting in a large number of overall movements and difficulty in effectively improving efficiency. [Summary of the Invention]
[0013] In view of this, the main objective of the present invention is to provide a control method for confirming the rising parameters of a wafer lifting device, in order to overcome the problem that the efficiency of conventional control methods is difficult to improve effectively.
[0014] This invention confirms a method for controlling the rising parameters of a wafer lifting device, executed by a computer electrically connected to a controller of the lifting device and a probe card. A test wafer is mounted on the lifting device, and the probe card is located above the test wafer and has a longest probe and a shortest probe. The control method includes: Step S01: Controlling the lifting device to rise the test wafer from a starting position until a contact signal of the longest probe is detected, and defining the current position information as a reference height; Step S02: Determining whether a contact signal of the shortest probe is detected; Step S03: If no contact signal of the shortest probe is detected, controlling the lifting device to rise the test wafer a distance according to a step movement parameter, and returning to step S02; Step S04: If a contact signal of the shortest probe is detected, controlling the lifting device to descend the test wafer a distance according to the step movement parameter; Step S05: Determining whether a contact signal of the shortest probe is detected. Step S06: When no contact signal of the shortest probe is detected, the lifting device is controlled to move according to a minimum movement parameter to raise the test wafer by a distance and return to step S05, wherein the step movement parameter is greater than the minimum movement parameter; Step S07: When the contact signal of the shortest probe is detected, a final height is defined according to the current position information, and an optimized rising parameter is defined and stored according to the height difference between the final height and the reference height.
[0015] According to the control method for confirming the rising parameters of the wafer lifting device of the present invention, after the position of the test wafer reaches the reference height, the control method of the present invention mainly controls the rising of the test wafer according to the step movement parameter, and the step movement parameter is greater than the minimum movement parameter. The present invention only operates a small part (step S06) of the minimum movement parameter or does not need to use the minimum movement parameter. Compared with the prior art, the conventional control method operates entirely according to the minimum movement parameter, resulting in the test wafer rising only slightly with the minimum movement parameter each time. The present invention mainly uses the step movement parameter to raise the position of the test wafer by a larger margin. Therefore, the control method of the present invention can significantly reduce the overall number of rising operations and significantly improve efficiency.
Implementation Method
[0016] Please refer to Figures 1 and 2. The present invention confirms that the control method of the rise parameter of the wafer riser can be applied to a wafer prober 10. The present invention is used to confirm an optimal rise parameter that is applicable before actual wafer testing production.
[0017] The wafer testing equipment 10 includes a wafer chuck 11, a lifting device 12, a probe card 13, and a computer 14. The computer 14 can connect to a workstation computer 15 for information transmission. The connection between the computer 14 and the workstation computer 15 can be wired (e.g., via a network cable or transmission line) or wireless (e.g., via Wi-Fi or Bluetooth). In one embodiment, the workstation computer 15 and the computer 14 of the wafer testing equipment 10 can work together and exchange data. The computer 14 can provide feedback on relevant information to the workstation computer 15, and the workstation computer 15 can execute an automatic control program to transmit relevant instructions to the computer 14 to execute the control method of the present invention.
[0018] The wafer chuck 11 is mounted on the lifting device 12. The top side of the wafer chuck 11 is used to carry a test wafer 20, wherein the test wafer 20 may be an engineering wafer or a wafer to be tested for future wafer testing and production. The probe card 13 is mounted above the wafer chuck 11 and the test wafer 20. The bottom side of the probe card 13 has a plurality of probes 130, the tips of which face the test wafer 20. The lifting device 12 is controlled by the computer 14 to move or position the wafer chuck 11, thereby moving the test wafer 20 toward the probe card 13, away from the probe card 13, or keeping it in a certain position. The computer 14 can be the built-in computer of the wafer testing equipment 10. The computer 14 is electrically connected to the controller of the lifting device 12 and the probe card 13. Therefore, the computer 14 can transmit signals to the test wafer 20 through the probe card 13, and the computer 14 can generate control commands to control the lifting device 12 to perform lifting actions and record position information.
[0019] Generally speaking, the specifications of the probe card 13 correspond to the specifications of the test wafer 20. The lengths of the plurality of probes 130 are not completely equal and are not flat. Therefore, as shown in Figure 2, there is a longest probe 131 and a shortest probe 132 among the plurality of probes 130. The length difference between the longest probe 131 and the shortest probe 132 can be tens of micrometers (μm) or more. The relative distance between the tip of the longest probe 131 and the test wafer 20 is smaller than the relative distance between the tip of the shortest probe 132 and the test wafer 20. Figure 2 is only a schematic diagram, and its size ratio is for reference only. The computer 14 can define and identify the longest probe 131 and the shortest probe 132 through probe coordinates or numbers.
[0020] Please refer to Figures 1 to 3. The control method for the rising parameters of the wafer lifting device of the present invention is executed on the computer 14. The control method of the present invention includes the following steps:
[0021] Step S01: The computer 14 controls the lifting device 12 to operate and raise the test wafer 20 from a starting position P0 below the probe card 13. Please refer to Figure 4. The computer 14 continues until it detects a contact signal between the longest probe 131 and the test wafer 20. This is the first contact between the longest probe 131 and the test wafer 20. The computer 14 defines and stores the position information corresponding to the first contact as a reference height OD1. As shown in Figure 2, when the test wafer 20 is at the starting position P0, the test wafer 20 is still a distance away from the probe card 13 and has not contacted any of the probes 130 of the probe card 13. At this time, the computer 14 does not detect a contact signal from the probe card 13. As the test wafer 20 continues to rise from the starting position P0, as shown in Figure 4, the test wafer 20 will first contact the longest probe 131. At this time, the test wafer 20 is located at the first contact position, so that the computer 14 detects the contact signal of the longest probe 131. The computer 14 can define and store the position information corresponding to the first contact as the reference height OD1. The reference height OD1 can refer to the height value relative to the starting position P0.
[0022] Step S02: The computer 14 determines whether a contact signal between the shortest probe 132 and the test wafer 20 is detected, that is, whether the shortest probe 132 is in contact with the test wafer 20. As mentioned above and in Figure 4, since the longest probe 131 has just contacted the test wafer 20, and the shortest probe 132 has not yet contacted the test wafer 20, the determination result of step S02 is "no" and proceeds to step S03, as explained below.
[0023] Step S03: The computer 14 controls the lifting device 12 to operate according to the step movement parameters to raise the test wafer 20 by a distance, and then returns to step S02. The computer 14 has preset step movement parameters, which are movement distance values along the Z-axis and whose units can be micrometers (μm). That is, the step movement parameters correspond to the movement distance of the test wafer 20. An embodiment of the step movement parameters can be represented as follows:
[0024]
[0025] In the above formula, d is the step movement parameter (unit: μm); OD* is a preset value of an upper limit of the rise parameter specification; X is a preset value greater than 1 and less than the upper limit of the rise parameter specification OD*. In one embodiment, X can be 10. The computer 14 has a preset upper limit of the rise parameter specification, which is a movement distance value along the Z-axis determined according to the specifications of the test wafer 20 and the probe card 13, and its unit can be micrometers (μm). The upper limit of the rise parameter specification is used to limit the maximum range by which the test wafer 20 can be raised after the initial contact position. X is also a value determined according to the specifications of the test wafer 20 and the probe card 13, used to determine the movement distance range of d. X and d are negatively correlated. When X is larger, d is smaller.
[0026] Generally, the probes 130 of the probe card 13 have not yet shown significant wear. When the test wafer 20 is raised to the upper limit of the rise parameter specification after the initial contact position, it can ensure that all probes 130 of the probe card 13 (including the longest probe 131 and the shortest probe 132) fully contact the test wafer 20. At this time, the probes 130 and the test wafer 20 bear a certain stress and pressure. However, since the probes 130 basically have extensibility and elasticity, the probes 130 and the test wafer 20 will not be damaged. Therefore, the upper limit of the rise parameter specification can be regarded as a safety threshold. On the other hand, even if the test wafer 20 is raised slightly less than the upper limit of the rise parameter specification after the initial contact position, all probes 130 of the probe card 13 can still fully contact the test wafer 20. At this time, the stress and pressure borne by the probes 130 and the test wafer 20 are relatively small.
[0027] It is understandable that as steps S02 and S03 are repeatedly executed, the position of the test wafer 20 continues to rise in a stepwise manner along the Z-axis at the aforementioned magnitude d. The test wafer 20 will successively come into contact with more and more probes 130. Since the probes 130 are basically elastic and flexible, they will not break or damage the test wafer 20 when they come into contact with the test wafer 20. Correspondingly, the number of contact signals detected by the computer 14 from the probe card 13 also increases until the test wafer 20 comes into contact with the shortest probe 132. At this time, the computer 14 detects the contact signal of the shortest probe 132, that is, the judgment result of step S02 is "yes" and proceeds to step S04. It should also be noted that the value of X should not be too small to avoid d being too large, which would cause the probe 130 to be damaged due to excessive stress and pressure when it comes into contact with the test wafer 20 during the last increase in magnitude d.
[0028] Step S04: The computer 14 controls the lifting device 12 to operate according to the step movement parameters to lower the test wafer 20 by a distance. That is, the position of the test wafer 20 is lowered along the Z-axis by the aforementioned magnitude d, and then proceeds to step S05, as explained below.
[0029] Step S05: The computer 14 determines whether it has detected a contact signal between the shortest probe 132 and the test wafer 20, that is, whether the shortest probe 132 has contacted the test wafer 20 again. When the position of the test wafer 20 drops by the aforementioned magnitude d, the shortest probe 132 may separate from the test wafer 20 and not make contact. For the computer 14, this means it has lost the contact signal of the shortest probe 132. Therefore, the result of step S05 is "no" and the process proceeds to step S06, as explained below.
[0030] Step S06: The computer 14 controls the lifting device 12 to operate according to a minimum movement parameter to raise the test wafer 20 by a distance, and returns to step S05. The minimum movement parameter is a movement distance value along the Z-axis and its unit can be micrometers (μm). The minimum movement parameter is a preset value and is used to limit the lower limit of the movement distance of the test wafer 20. The step movement parameter is greater than the minimum movement parameter. The minimum movement parameter depends on the specifications of the wafer testing equipment 10. It is understood that as the aforementioned steps S05 and S06 are repeatedly executed, the test wafer 20 can be gradually raised along the Z-axis in small increments according to the minimum movement parameter until the computer 14 determines that the shortest probe 132 contacts the test wafer 20 again. That is, the computer 14 detects the contact signal of the shortest probe 132 again. That is, the judgment result of step S05 is "yes" and proceeds to step S07.
[0031] On the other hand, after the position of the test wafer 20 decreases by the aforementioned d in step S04, the shortest probe 132 may still remain in contact with the test wafer 20. Therefore, the judgment result of step S05 is also "yes" and proceeds to step S07, as explained below.
[0032] Step S07: Referring to Figure 5, the computer 14, based on the determination of "yes" in step S05, defines the current position information (i.e., the position of the last contact) as a final height OD2. The final height OD2 can refer to the height value relative to the starting position P0. The computer 14 calculates a height difference ODF between the final height OD2 and the reference height OD1, and defines and stores the optimized ascent parameter based on the height difference ODF. In one embodiment, the computer 14 can directly define and store the height difference ODF as the optimized ascent parameter. Generally, the value of the optimized ascent parameter is less than or equal to the upper limit value of the ascent parameter specification.
[0033] Since the optimized rise parameters are confirmed in step S07, the computer 14 controls the lifting device 12 to lower the test wafer 20 back to the starting position P0 so that the test wafer 20 can be taken out and ready for actual wafer testing and production.
[0034] The following is an example. The minimum movement parameter is 1, the upper limit of the rise parameter specification is 45, and X is 10. Then the step movement parameter d is 4 (d=45 / 10=4.5, but this example only takes the single digit 4 and does not count the decimal). When the control method of the present invention brings the position of the test wafer 20 to the initial contact position in step S01, the computer 14 can obtain the position information of the reference height OD1. Then, during the repeated execution of steps S02 and S03, the position of the test wafer 20 rises in increments of 4 (μm) from the initial contact position. Assuming that steps S02 and S03 are repeated 11 times, that is, after the 11th rise of the test wafer 20, the computer 14 can detect the contact signal of the shortest probe 132. At this time, the position of the test wafer 20 relative to the reference height OD1 is 44 (μm). The computer 14 then executes step S04 to lower the position of the test wafer 20 by 4 (μm). The amplitude (12th operation) is then increased. At this point, the position of the test wafer 20 relative to the reference height OD1 is reduced to 40 (μm). At this time, the shortest probe 132 has not separated from the test wafer 20 and has not made contact. Then, steps S05 and S06 are repeated twice (13th and 14th operations), causing the position of the test wafer 20 to rise twice in increments of 1 (μm). After this, the computer 14 detects the contact signal of the shortest probe 132 again. The computer 14 can obtain the position information of the final height OD2. At this time, the position of the test wafer 20 relative to the reference height OD1 is increased to 42 (μm). That is to say, the height difference ODF between the final height OD2 and the reference height OD1 is 42 (μm). Therefore, the computer 14 stores the aforementioned height difference ODF of 42 (μm) as the optimized rise parameter.
[0035] Compared with the prior art, after the position of the test wafer 20 reaches the position of the first contact, the control method of the present invention only needs 14 operations to complete the confirmation of the optimal rise parameter. However, the control method of the prior art only rises slightly with the minimum movement parameter, which means that the prior art needs 42 operations to complete the confirmation of the rise parameter. Therefore, the control method of the present invention can greatly reduce the overall number of operations and greatly improve efficiency.
[0036] In actual wafer testing production, the wafer testing equipment 10 can directly utilize the optimized rise parameters for formal testing production operation. This mainly involves placing a wafer under test on the wafer chuck 11. The computer 14 controls the lifting device 12 to operate, raising the wafer under test from the starting position P0 until the computer 14 detects the contact signal between the longest probe 131 and the test wafer 20, thus obtaining the position information of the reference height OD1. Next, the computer 14 controls the lifting device 12 to operate, raising the wafer under test directly from the reference height OD1 along the Z-axis by the optimized rise parameter distance and positioning it. At this point, the wafer under test can effectively contact all probes 130 (including the shortest probe 132) of the probe card 13, and the stress and pressure borne by the probes 130 and the wafer under test are within the tolerance range, preventing damage to the probes 130 and the wafer under test. The computer 14 can then transmit test signals and receive measurement signals to the wafer under test through the probe card 13. After the measurement of the wafer to be tested is completed, the computer 14 can control the lifting device 12 to operate to lower the wafer to be tested back to the starting position P0, in preparation for testing the next wafer to be tested.
[0037] It is understood that the probe length of the probe card 13 will wear down with the increase of the number of uses, resulting in a shorter probe length and a relatively longer relative distance between the starting position P0 and the probe tip of the probe card 13. Therefore, in another embodiment of the control method step S07 of the present invention, the computer 14 can calculate the product of the height difference ODF and a preset value N, and define and store the product as the optimized rise parameter, where N is greater than 1, N can be, for example, 1.1, and the upper limit of N depends on the specifications of the probe card 13 and the test wafer 20 and the test frequency. Therefore, the value of the optimized rise parameter may also be greater than the upper limit of the rise parameter specification, so as to ensure that the probe 130 of the probe card 13 can still effectively contact all the probes 130 of the probe card 13 after the wafer under test rises from the reference height OD1 by the distance of the optimized rise parameter under a certain degree of wear. [Simplified Explanation of the Diagram]
[0038] Figure 1: Block diagram of the control system for implementing the control method for confirming the rise parameters of the wafer lifting device according to the present invention. Figure 2: Schematic diagram of the test wafer at the starting position in the present invention. Figure 3: Flowchart of an embodiment of the control method for confirming the rise parameters of the wafer lifting device according to the present invention. Figure 4: Schematic diagram of the test wafer at the reference height in the present invention. Figure 5: Schematic diagram of the test wafer at the final height in the present invention. Figure 6: Flowchart of a conventional control method.
Claims
1. A control method for confirming the rising parameters of a wafer lifting device, executed on a computer electrically connected to a controller of the lifting device and a probe card, wherein a test wafer is mounted on the lifting device, and the probe card is located above the test wafer and has a longest probe and a shortest probe, the control method comprising: Step S01: controlling the lifting device to actuate and raise the test wafer from a starting position until a contact signal of the longest probe is detected, and defining the current position information as a reference height; Step S02: determining whether a contact signal of the shortest probe is detected; Step S03: if no contact signal of the shortest probe is detected, controlling the lifting device to actuate and raise the test wafer a distance according to a step movement parameter, and returning to step S02; Step S04: if a contact signal of the shortest probe is detected, controlling the lifting device to actuate and lower the test wafer a distance according to the step movement parameter; Step S05: determining whether a contact signal of the shortest probe is detected. Step S06: When no contact signal of the shortest probe is detected, the lifting device is controlled to move according to a minimum movement parameter to raise the test wafer by a distance and return to step S05, wherein the step movement parameter is greater than the minimum movement parameter; Step S07: When the contact signal of the shortest probe is detected, a final height is defined according to the current position information, and an optimized rising parameter is defined and stored according to the height difference between the final height and the reference height.
2. The control method for confirming the rising parameters of the wafer lifting device as described in claim 1, wherein, The computer directly defines and stores the height difference as the optimized ascent parameter.
3. The control method for confirming the rising parameters of the wafer lifting device as described in claim 1, wherein, The computer defines and stores the product of the height difference and a preset value N as the optimized ascent parameter, where N is greater than 1.
4. A method for controlling the rise parameters of a wafer hoisting device as described in any one of claims 1 to 3, wherein, The step movement parameter is expressed as follows: In the above formula, d is the step movement parameter; OD* is an upper limit of an ascent parameter specification; X is greater than 1 and less than the ascent parameter specification.