A method and apparatus for monitoring wafer yield

Abstract

The application provides a method and device for monitoring wafer yield, the method comprising continuously detecting different to-be-detected wafers to obtain detection results of the wafers, determining the yield of the latest n wafers based on the detection results, and prompting that the wafer yield is abnormal in a short period if the yield of the latest n wafers is lower than a preset first yield value. The method provided by the application effectively avoids that the unqualified chips in a part of the area are balanced by the overall yield, and the user can quickly receive the prompt when the chips are abnormal in a short period, so that the situation that the abnormal yield in a part of the area cannot be perceived or is perceived with a delay is prevented, and the time and efficiency of chip detection are guaranteed to a certain extent.

Description

Technical Field

[0001] This invention belongs to the field of chip testing technology, specifically relating to a method and apparatus for monitoring wafer yield. Background Technology

[0002] A wafer is a silicon wafer used to fabricate silicon semiconductor circuits; its raw material is silicon. High-purity polycrystalline silicon is dissolved, doped with silicon crystal seed crystals, and then slowly pulled out to form a cylindrical single-crystal silicon wafer. After grinding, polishing, and slicing, the silicon ingot is formed into a silicon wafer. Domestic wafer production lines mainly produce 8-inch and 12-inch wafers.

[0003] The main processing methods for wafers are wafer fabrication and batch processing, which means processing one or more wafers simultaneously. As semiconductor feature sizes become smaller and processing and measurement equipment becomes more advanced, new data characteristics have emerged in wafer fabrication.

[0004] During wafer inspection, staff monitor chip yield in real time using ATE (Automatic Test Equipment). Yield refers to the proportion of qualified chips out of all inspected chips. As the number of chips being inspected increases, higher defect rates in some areas of the wafer disk are balanced out by the overall yield. Staff only see the overall yield, so abnormal yields in some areas go unnoticed or are detected late, which affects inspection time and efficiency to some extent. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention proposes a method and apparatus for monitoring wafer yield, the method comprising:

[0006] Different wafers to be inspected are continuously inspected to obtain the inspection results for each wafer;

[0007] Based on the test results, determine the yield of the latest n wafers tested;

[0008] If the yield of the latest n wafers detected is lower than the preset first yield value, it indicates that the wafer yield is abnormal in the short term.

[0009] Furthermore, the method also includes:

[0010] If it is determined that the yield of the latest n wafers being inspected is not lower than the first yield value, monitor whether there are any new preset number of wafers to be inspected.

[0011] If a new preset number of wafers are detected to be inspected, repeat the step of "determining the yield of the latest n inspected wafers".

[0012] Specifically, the preset number is less than n.

[0013] Preferably, the method further includes:

[0014] Based on the test results, the yield of the total number of wafers tested is determined.

[0015] If the total yield of the wafers inspected is lower than the preset second yield value, an abnormal wafer yield is indicated.

[0016] Furthermore, the method also includes:

[0017] If the yield of the current total number of wafers inspected is not lower than the second yield value, determine whether the yield of the latest n wafers inspected is lower than the yield of the current total number of wafers inspected.

[0018] If the judgment result is yes, determine whether the yield of the latest n wafers being detected is lower than the yield of the total number of wafers being detected by the current number of wafers by a preset threshold.

[0019] If the judgment result is yes, it indicates that the wafer yield is abnormal in the short term.

[0020] The present invention also proposes an apparatus for monitoring wafer yield, used to implement the method for monitoring wafer yield as described above, the apparatus comprising:

[0021] The detection module is used to continuously detect different wafers to be inspected and obtain the detection results of each wafer;

[0022] The calculation module is used to determine the yield of the latest n wafers detected based on the detection results;

[0023] The first judgment module is used to determine whether the yield of the latest n wafers being inspected is lower than the preset first yield value;

[0024] The first prompting module is used to prompt that the wafer yield is abnormal in the short term when the first judgment module determines that the yield of the latest n wafers detected is lower than the first yield value.

[0025] Furthermore, the device also includes:

[0026] The monitoring module is used to monitor whether there are any new preset number of wafers to be inspected after the first judgment module determines that the yield of the latest n wafers being inspected is not lower than the first yield value.

[0027] The calculation module is also used to execute a preset function again when the monitoring module detects that a new wafer is being tested.

[0028] Specifically, the preset number set by the monitoring module is less than n.

[0029] Preferably, the calculation module is further configured to calculate the yield of the total number of wafers inspected based on the detection results, and the first judgment module is further configured to determine whether the yield of the total number of wafers inspected is lower than a preset second yield value. The device further includes:

[0030] The second prompt module is used to prompt an abnormal overall wafer yield when the second judgment module determines that the yield of the total number of wafers detected is lower than the second yield value.

[0031] Furthermore, the device also includes:

[0032] The second judgment module is used to determine whether the yield of the latest n wafers being inspected is lower than the yield of the total number of wafers being inspected.

[0033] The third judgment module is used to determine whether the difference between the yield of the latest n wafers being lower than the yield of the total number of wafers being detected exceeds a preset threshold after the second judgment module determines that the yield of the latest n wafers being lower than the yield of the total number of wafers being detected.

[0034] The first prompting module is also used to prompt that the wafer yield is abnormal in the short term when the third judgment module determines that the yield of the latest n wafers is lower than the yield of the total number of wafers detected by the current total number of wafers by the value exceeding the threshold.

[0035] The present invention has at least the following beneficial effects:

[0036] This invention provides a method and apparatus for monitoring wafer yield. The method proposed in this invention can detect whether the wafer yield is normal in a short period of time, avoiding the situation where the yield detected in the short period of time is covered by the overall yield, which would prevent the abnormality from being detected in time.

[0037] Furthermore, the method proposed in this invention can simultaneously consider the yield of the wafer throughout its entire lifecycle, and on this basis, can judge whether the yield of the wafer is abnormal in the short term, thus achieving the effect of dynamic monitoring.

[0038] Therefore, the present invention provides a method and apparatus for monitoring wafer yield. The method proposed in this invention effectively avoids the overall yield balancing caused by high defect rates in some areas. When abnormalities occur in chips in the short term, users can receive prompts quickly, preventing situations where abnormal yields in some areas cannot be detected or are detected with delays. This ensures a certain level of time and efficiency for chip detection. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the overall process of the method for monitoring wafer yield provided in Example 1;

[0041] Figure 2 A flowchart illustrating a method for simultaneously considering wafer yield throughout its entire lifecycle;

[0042] Figure 3 A flowchart illustrating a method for determining short-term yield based on the overall yield of a wafer.

[0043] Figure 4 A schematic diagram of the module structure of the device for monitoring wafer yield provided in Example 2;

[0044] Figure 5 A schematic diagram of the module structure of the device designed to simultaneously ensure the yield of wafers throughout their entire lifecycle;

[0045] Figure 6 A schematic diagram of the module structure of a device for determining short-term yield by measuring the yield of a wafer throughout its entire lifecycle.

[0046] Figure label:

[0047] 1-Detection module; 2-Calculation module; 3-First judgment module; 4-First prompt module; 5-Monitoring module; 6-Second prompt module; 7-Second judgment module; 8-Third judgment module. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Various embodiments of the invention will be described more fully below. The invention may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the invention to the specific embodiments disclosed herein, but rather the invention should be understood to cover all modifications, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of the invention.

[0050] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of the disclosed functions, operations, or elements, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or the possibility of adding one or more combinations of the foregoing.

[0051] In various embodiments of the invention, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0052] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

[0053] It should be noted that, in this invention, unless otherwise explicitly specified and defined, terms such as "installation," "connection," and "fixation" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] In this invention, those skilled in the art should understand that the terms indicating orientation or positional relationship in the text are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the purpose of facilitating the description of this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0055] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0056] Example 1

[0057] This embodiment provides a method for monitoring wafer yield, used to monitor wafer yield over a short period of time. Please refer to [link / reference needed]. Figure 1 The method includes:

[0058] S100: Continuously inspect different wafers to be inspected, obtain the inspection results of each wafer, and proceed to step S110.

[0059] S110: Based on the detection results, determine the yield of the latest n wafers detected, and proceed to step S120.

[0060] It should be noted that, assuming a total of m wafers are being inspected, n < m; yield = number of qualified wafers ÷ total number of inspected wafers × 100%.

[0061] S120: Determine whether the yield of the latest n wafers being inspected is lower than the preset first yield value.

[0062] If the yield of the latest n wafers is lower than the first yield value, it is determined that the chip yield is low in the short term, and the process proceeds to step S130; if the yield of the latest n wafers is not lower than the first yield value, it is determined that the chip yield is normal in the short term, and the process proceeds to step S140.

[0063] S130: Indicates an abnormality in wafer yield in the short term.

[0064] S140: Monitor whether a new preset number of wafers are being inspected.

[0065] If a new preset number of wafers are detected to be inspected, repeat step S110.

[0066] It should be noted that the preset number of wafers to be inspected, as mentioned in "monitoring whether a preset number of wafers are being inspected", should be less than n to prevent the occurrence of missed wafers.

[0067] Preferably, the method proposed in this embodiment can also take into account the overall yield of the wafer. For details, please refer to... Figure 2 The method includes:

[0068] S200: Continuously inspect different wafers to be inspected, obtain the inspection results of each wafer, and proceed to step S210.

[0069] S210: Based on the detection results, determine the yield of the latest n wafers detected and the yield of the total number of wafers detected, and proceed to step S220.

[0070] S220: Determine whether the yield of the latest n wafers being inspected is lower than the preset first yield value, and whether the yield of the total number of wafers being inspected is lower than the preset second yield value.

[0071] It should be noted that the first yield value and the second yield value can be preset to the same or different values ​​according to actual needs. In this embodiment, the first yield value and the second yield value are preset to the same value.

[0072] If the yield of the latest n wafers is lower than the first yield value, the chip yield is determined to be low in the short term, and the process proceeds to step S230; if the yield of the total number of wafers inspected is lower than the second yield value, the chip yield is determined to be low throughout the entire life cycle, and the process proceeds to step S240; if the yield of the latest n wafers inspected is not lower than the preset first yield value, and the yield of the total number of wafers inspected is not lower than the preset second yield value, the chip yield is determined to be normal in both the short term and throughout the entire life cycle, and the process proceeds to step S250.

[0073] S230: Indicates an abnormality in wafer yield in the short term.

[0074] S240: Indicates abnormal wafer yield throughout the entire process.

[0075] S250: Monitors whether a new preset number of wafers are being inspected.

[0076] If a new preset number of wafers are detected to be inspected, repeat step S210.

[0077] Furthermore, the method proposed in this embodiment can also determine whether the yield is abnormal in the short term by measuring the yield throughout the entire wafer lifecycle, achieving a dynamic monitoring effect. For details, please refer to... Figure 3 The method includes:

[0078] S300: Continuously inspect different wafers to be inspected, obtain the inspection results of each wafer, and proceed to step S310.

[0079] S310: Based on the detection results, determine the yield of the latest n wafers detected, and proceed to step S320.

[0080] S320: Determine whether the yield of the total number of wafers inspected is lower than the preset second yield value.

[0081] If the yield of the total number of wafers inspected is lower than the preset second yield value, the overall yield of the chip is determined to be low, and the process proceeds to step S350; if the yield of the total number of wafers inspected is not lower than the preset second yield value, the overall yield of the chip is determined to be normal, and the process proceeds to step S330.

[0082] S330: Determine whether the yield of the latest n wafers being inspected is lower than the yield of the total number of wafers being inspected.

[0083] If the yield of the latest n wafers is lower than the yield of the total number of wafers inspected, proceed to step S340; if the yield of the latest n wafers is not lower than the yield of the total number of wafers inspected, it is determined that the yield of the chip is normal in the short term, and proceed to step S370.

[0084] S340: Determine whether the yield of the latest n wafers being inspected is lower than the yield of the total number of wafers being inspected by a preset threshold.

[0085] If the yield of the latest n wafers is lower than the yield of the total number of wafers detected by the current process by a value exceeding a preset threshold, it is determined that the yield of the chip is low in the short term, and the process proceeds to step S360; if the yield of the latest n wafers is lower than the yield of the total number of wafers detected by the current process by a value not exceeding a preset threshold, it is determined that the yield of the chip is normal in the short term, and the process proceeds to step S370.

[0086] S350: Indicates abnormal wafer yield throughout the entire process.

[0087] S360: Indicates an abnormality in wafer yield in the short term.

[0088] S370: Monitors whether a new preset number of wafers are being inspected.

[0089] If a new preset number of wafers are detected to be inspected, repeat step S310.

[0090] Example 2

[0091] This embodiment proposes a device for monitoring wafer yield, used to implement the method for monitoring wafer yield proposed in Embodiment 1. Please refer to [link / reference needed]. Figure 4 The device includes:

[0092] The detection module 1 is used to continuously detect different wafers to be inspected and obtain the detection results of each wafer;

[0093] Calculation module 2 is used to determine the yield of the latest n wafers inspected based on the detection results;

[0094] The first judgment module 3 is used to determine whether the yield of the latest n wafers being inspected is lower than the preset first yield value;

[0095] The first prompt module 4 is used to prompt that the wafer yield is abnormal in the short term when the first judgment module 3 determines that the yield of the latest n wafers detected is lower than the first yield value.

[0096] Monitoring module 5 is used to monitor whether a new preset number of wafers are being inspected.

[0097] It should be noted that, assuming a total of m wafers are being inspected, n < m; yield = number of qualified wafers ÷ total number of inspected wafers × 100%.

[0098] Specifically, if the first judgment module 3 determines that the yield of the latest n wafers being inspected is lower than the first yield value, it determines that the chip yield is low in the short term, and the first prompt module 4 prompts the user that the wafer yield is abnormal in the short term; if the first judgment module 3 determines that the yield of the latest n wafers being inspected is not lower than the first yield value, it determines that the chip yield is normal in the short term, and then it switches to the monitoring module 5. When the monitoring module 5 detects that a new preset number of wafers to be inspected are being inspected, the calculation module 2 executes the preset function again.

[0099] It should be noted that in the step of "monitoring whether there are new preset number of wafers to be inspected" performed by the monitoring module 5, the preset number should be less than n to prevent the occurrence of missed wafers.

[0100] Preferably, the device proposed in this embodiment can also take into account the yield of the entire wafer lifecycle. Specifically, the calculation module 2 is further used to calculate the yield of the total number of wafers inspected so far based on the inspection results, and the first judgment module 3 is further used to determine whether the yield of the total number of wafers inspected so far is lower than a preset second yield value. Please refer to [reference needed]. Figure 5 The device further includes:

[0101] The second prompt module 6 is used to prompt an abnormal overall wafer yield when the first judgment module 3 determines that the yield of the total number of wafers detected is lower than the second yield value.

[0102] It should be noted that the first yield value and the second yield value can be preset to the same or different values ​​according to actual needs. In this embodiment, the first yield value and the second yield value are preset to the same value.

[0103] Specifically, if the first judgment module 3 determines that the yield of the total number of wafers currently being inspected is lower than the second yield value, it determines that the overall yield of the chip is low, and the second prompt module 6 prompts the user that the overall wafer yield is abnormal; if the first judgment module 3 determines that the yield of the total number of wafers currently being inspected is not lower than the second yield value, it determines that the overall yield of the chip is normal. When the first judgment module 3 simultaneously determines that the yield of the latest n wafers being inspected is not lower than the first yield value, that is, the chip yield is normal in the short term, it switches to the monitoring module 5. When the monitoring module 5 detects that a new preset number of wafers to be inspected are being inspected, the calculation module 2 executes the preset function again.

[0104] Furthermore, the device proposed in this embodiment can also determine whether the yield is abnormal in the short term by measuring the yield throughout the entire wafer lifecycle, achieving a dynamic monitoring effect. For details, please refer to... Figure 6 The device further includes:

[0105] The second judgment module 7 is used to determine whether the yield of the latest n wafers being inspected is lower than the yield of the total number of wafers being inspected.

[0106] The third judgment module 8 is used to determine whether the difference between the yield of the latest n wafers being detected and the yield of the total number of wafers being detected exceeds a preset threshold after the second judgment module 7 determines that the yield of the latest n wafers being detected is lower than the yield of the total number of wafers being detected.

[0107] Specifically, if the second judgment module 7 determines that the yield of the latest n wafers being inspected is lower than the yield of the total number of wafers being inspected, the fourth judgment module continues to execute the preset function; if the second judgment module 7 determines that the yield of the latest n wafers being inspected is not lower than the yield of the total number of wafers being inspected, it determines that the yield of the chip is normal in the short term, and transfers to the monitoring module 5. When the monitoring module 5 detects that a new preset number of wafers to be inspected are being inspected, the calculation module 2 executes the preset function again.

[0108] If the third judgment module 8 determines that the yield of the latest n wafers being tested is lower than the yield of the total number of wafers being tested by more than a threshold, it determines that the chip yield is low in the short term, and the first prompt module 4 prompts the user that the wafer yield is abnormal in the short term; if the third judgment module 8 determines that the yield of the latest n wafers being tested is lower than the yield of the total number of wafers being tested by more than a threshold, it determines that the chip yield is normal in the short term, and switches to the monitoring module 5. When the monitoring module 5 detects that a new wafer is being tested, the calculation module 2 executes the preset function again.

[0109] In summary, this invention provides a method and apparatus for monitoring wafer yield. The method proposed in this invention effectively avoids the overall yield balancing caused by high defect rates in some areas. When abnormalities occur in chips in the short term, users can receive prompts quickly, preventing situations where abnormal yields in some areas cannot be detected or are detected with delays. This ensures a certain level of time and efficiency for chip detection.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of monitoring wafer yield, the method comprising: The method comprises: ​ continuously detecting different to-be-detected wafers to obtain detection results of the wafers; based on the detection results, determining a yield of the latest n wafers detected currently, and determining a yield of all the wafers detected currently; if the yield of the latest n wafers detected currently is lower than a preset first yield value, prompting that the wafer yield in a short term is abnormal; if it is determined that the yield of the latest n wafers detected currently is not lower than the first yield value, monitoring whether new wafers of a preset number are detected; if it is monitored that new wafers of the preset number are detected, repeating the step of determining the yield of the latest n wafers detected currently; the preset number is less than n; if the yield of all the wafers detected currently is lower than a preset second yield value, prompting that the wafer yield in a whole term is abnormal; if it is monitored that new wafers of the preset number are detected, repeating the step of continuously detecting different to-be-detected wafers to obtain detection results of the wafers; The method further comprises: if the yield of all the wafers detected currently is not lower than the second yield value, determining whether the yield of the latest n wafers detected currently is lower than the yield of all the wafers detected currently; if the determination result is yes, determining whether the yield of the latest n wafers detected currently is lower than the yield of all the wafers detected currently by a preset threshold value; if the determination result is yes, prompting that the wafer yield in a short term is abnormal.

2. An apparatus for monitoring wafer yield, the apparatus comprising: The device for implementing the method for monitoring the wafer yield of claim 1 comprises: a detection module, configured to continuously detect different to-be-detected wafers to obtain detection results of the wafers, and further configured to, when it is monitored that new wafers of a preset number are detected, repeat the step of continuously detecting different to-be-detected wafers to obtain detection results of the wafers; a calculation module, configured to determine a yield of the latest n wafers detected currently based on the detection results; a first determination module, configured to determine whether the yield of the latest n wafers detected currently is lower than a preset first yield value; a first prompting module, configured to, when the first determination module determines that the yield of the latest n wafers detected currently is lower than the first yield value, prompt that the wafer yield in a short term is abnormal; a monitoring module, configured to, when the first determination module determines that the yield of the latest n wafers detected currently is not lower than the first yield value, monitor whether new wafers of a preset number are detected; the preset number set by the monitoring module is less than n; the calculation module is further configured to calculate a yield of all the wafers detected currently based on the detection results, and further configured to, when the monitoring module monitors that new wafers are detected, execute a preset function again; the first determination module is further configured to determine whether the yield of all the wafers detected currently is lower than a preset second yield value; a second prompting module, configured to, when the first determination module determines that the yield of all the wafers detected currently is lower than the second yield value, prompt that the wafer yield in a whole term is abnormal; The second judging module is configured to judge whether the yield of the latest n wafers detected is lower than the yield of the wafers detected in total; The third judging module is configured to judge whether the value of the yield of the latest n wafers detected being lower than the yield of the wafers detected in total exceeds a preset threshold when the second judging module judges that the yield of the latest n wafers detected is lower than the yield of the wafers detected in total; and the first prompting module is further configured to prompt that the yield of the wafers appears abnormal in a short period when the third judging module judges that the value of the yield of the latest n wafers detected being lower than the yield of the wafers detected in total exceeds the threshold.

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