CN114130709B - LED crystal grain appearance detection method - Google Patents
LED crystal grain appearance detection method Download PDFInfo
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- CN114130709B CN114130709B CN202111198694.0A CN202111198694A CN114130709B CN 114130709 B CN114130709 B CN 114130709B CN 202111198694 A CN202111198694 A CN 202111198694A CN 114130709 B CN114130709 B CN 114130709B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
- B07C5/3422—Sorting according to other particular properties according to optical properties, e.g. colour using video scanning devices, e.g. TV-cameras
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/02—Measures preceding sorting, e.g. arranging articles in a stream orientating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
- B07C5/3425—Sorting according to other particular properties according to optical properties, e.g. colour of granular material, e.g. ore particles, grain
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/36—Sorting apparatus characterised by the means used for distribution
- B07C5/361—Processing or control devices therefor, e.g. escort memory
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/36—Sorting apparatus characterised by the means used for distribution
- B07C5/361—Processing or control devices therefor, e.g. escort memory
- B07C5/362—Separating or distributor mechanisms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses an LED crystal grain appearance detection method, which comprises the steps of carrying out optical detection on an LED crystal grain to obtain an appearance parameter document; dividing the LED crystal grains into first qualified crystal grains, first unqualified crystal grains and suspicious crystal grains according to the appearance parameter document; acquiring pictures of suspicious crystal grains, and judging appearance defect types of the suspicious crystal grains according to the pictures of the suspicious crystal grains; and dividing the suspicious crystal grains into second qualified crystal grains and second unqualified crystal grains according to the appearance defect types. The detection method carries out the re-judgment at the wafer stage, can timely select the unqualified grains, and avoids the unqualified grains from being sorted and arranged on the finished square sheet, thereby omitting the step of manual visual inspection and further saving a great deal of manpower and microscope cost.
Description
Technical Field
The invention relates to the technical field of light-emitting diodes, in particular to an LED crystal grain appearance detection method.
Background
After the electrical parameter test, the appearance automatic optical inspection (Automated Optical Inspection, AOI) and the wafer good product sorting are finished on the LED wafer, the crystal grains with the same grade on the LED wafer are selected to the square sheet, and finally, the appearance of the crystal grains of the finished square sheet is required to be manually inspected again, and the abnormal crystal grains missed in the AOI inspection are picked out, so that the appearance of each crystal grain is ensured to meet the quality requirement of shipment.
Because AOI detection capability can not achieve 100%, a small part of abnormal grains can be selected on a square sheet, manual recheck is needed through a microscope, and a large amount of manpower and microscope equipment are consumed in the mode, namely, in order to pick up 1% of unqualified grains, 100% of finished grains are needed to be checked, and the inspection is equivalent to 99% of time to be idle, so that efficiency and labor cost are greatly affected.
In addition, in the manual microscope picking mode, due to limited microscope visual field, the abnormal crystal grains are easy to miss and miss, and abnormal quality is formed.
Disclosure of Invention
The invention aims to solve the technical problems of providing the LED crystal grain appearance detection method which is high in efficiency, low in cost and high in detection rate of unqualified crystal grains.
In order to solve the technical problems, the invention provides an LED crystal grain appearance detection method, which comprises the following steps:
optically detecting the LED crystal grains to obtain an appearance parameter document, wherein the appearance parameter document comprises the crystal grain defect area proportion;
dividing the LED crystal grain into a first qualified crystal grain, a first unqualified crystal grain and a suspicious crystal grain according to the appearance parameter document, wherein the crystal grain defect area ratio of the suspicious crystal grain is in a preset range, the crystal grain defect area ratio of the first qualified crystal grain is smaller than the preset range, and the crystal grain defect area ratio of the first unqualified crystal grain is larger than the preset range;
obtaining pictures of suspicious crystal grains, and judging appearance defect types of the suspicious crystal grains according to the pictures of the suspicious crystal grains, wherein the appearance defect types comprise epitaxial appearance defects and polluted appearance defects;
dividing the suspicious crystal grains into second qualified crystal grains and second unqualified crystal grains according to the appearance defect types, wherein if the appearance defect types of the suspicious crystal grains are epitaxial appearance defects, the suspicious crystal grains are second unqualified crystal grains, if the appearance defect types of the suspicious crystal grains are pollution appearance defects, the suspicious crystal grains are second qualified crystal grains, the first qualified crystal grains and the second qualified crystal grains form qualified crystal grains, and the first unqualified crystal grains and the second unqualified crystal grains form unqualified crystal grains.
As an improvement of the above solution, the appearance parameter document further includes a grain defect area, where a grain defect area ratio=a grain defect area/a grain light emitting area, the grain light emitting area is an area of orthographic projection of the LED grain on the light emitting surface of the optical detection device, and the grain defect area is a total area of orthographic projection of the LED grain on the defect of the optical detection device.
As an improvement of the above scheme, the epitaxial appearance defect refers to an appearance defect caused by an epitaxial defect of the LED die, and the polluted appearance defect refers to an appearance defect caused by external pollution of the LED die in the preparation process.
As an improvement of the above-mentioned scheme, the appearance defect includes one or more of dropping electrode, dropping luminescent layer, scratch, adhering pollutant, dent, crack.
As an improvement of the above-mentioned scheme, the method for dividing the LED die into a first qualified die, a first disqualified die and a suspicious die includes:
setting a first judgment standard, wherein if the area ratio of the crystal grain defects of the LED crystal grains is smaller than or equal to the first judgment standard, the LED crystal grains are primary selected crystal grains, and if the area ratio of the crystal grain defects of the LED crystal grains is larger than the first judgment standard, the LED crystal grains are first unqualified crystal grains;
setting a second judgment standard, wherein if the grain defect area ratio of the primary selected grain is smaller than the second judgment standard, the primary selected grain is a first qualified grain, and if the grain defect area ratio of the primary selected grain is larger than or equal to the second judgment standard, the primary selected grain is a suspicious grain;
the area ratio of the crystal grain defect in the second judgment standard is smaller than that in the first judgment standard.
As an improvement of the scheme, the area ratio of the crystal grain defects in the first judging standard is 30% -60%, and the area ratio of the crystal grain defects in the second judging standard is 10% -40%.
As an improvement of the above scheme, scanning the suspicious crystal grains to generate a picture of the suspicious crystal grains;
and transmitting the picture of the suspicious crystal grain to display equipment, judging the appearance defect type of the suspicious crystal grain according to the picture of the suspicious crystal grain, and dividing the suspicious crystal grain into a second qualified crystal grain and a second unqualified crystal grain.
As an improvement of the above solution, the LED die appearance detection method further includes:
acquiring the position information of the LED crystal grains, wherein the position information of the LED crystal grains comprises the position information of qualified crystal grains and the position information of unqualified crystal grains;
according to the position information and the appearance parameter document of the LED crystal grains, appearance information of qualified crystal grains and appearance information of unqualified crystal grains are obtained;
and classifying the qualified crystal grains into good grades according to the appearance information of the qualified crystal grains and the appearance information of the unqualified crystal grains, and classifying the unqualified crystal grains into defective grades.
As an improvement of the above solution, the method for obtaining the positional information of the LED die includes:
the method comprises the steps of carrying out optical detection on an LED crystal grain, acquiring position information of the LED crystal grain while acquiring an appearance parameter document, wherein the position information of the LED crystal grain comprises position information of a first qualified crystal grain, position information of a first unqualified crystal grain and position information of a suspicious crystal grain;
scanning the suspicious crystal grains to acquire pictures of the suspicious crystal grains, and acquiring position information of the suspicious crystal grains, wherein the position information of the suspicious crystal grains comprises position information of second qualified crystal grains and position information of second unqualified crystal grains;
the position information of the first qualified crystal grain and the position information of the second qualified crystal grain form the position information of the qualified crystal grain, and the position information of the first unqualified crystal grain and the position information of the second unqualified crystal grain form the position information of the unqualified crystal grain.
As an improvement of the scheme, the sorting equipment arranges the qualified crystal grains on a finished square sheet according to the appearance information of the qualified crystal grains, and the appearance qualification rate of the LED crystal grains on the finished square sheet is 100%.
The implementation of the invention has the following beneficial effects:
the detection method is a brand new LED crystal grain appearance detection method, and the detection method is re-judged in the wafer stage, so that unqualified crystal grains can be timely selected, and the unqualified crystal grains are prevented from being sorted and arranged on a finished square sheet, so that the step of manual visual inspection is omitted, and a large amount of manpower and microscope cost are further saved.
The detection method of the application generates pictures for re-judging suspicious crystal grains, and the observation field of view and definition of the pictures are better than those of a microscope, so that the detection rate of unqualified crystal grains is high, and the accuracy is also high.
According to the detection method, the pictures of the suspicious crystal grains can be displayed on the display device at the same time, so that the pictures of the suspicious crystal grains can be compared and judged, an operator can also improve the accuracy of the repeated judgment.
The detection method collects the position information and the appearance information of the suspicious crystal grains, so that the fine statistics of the unqualified crystal grains can be realized, the improvement of the prior process and the quality improvement are facilitated, and the repeated rechecking of the unqualified crystal grains and the precise tracing of the wafer can be realized.
Drawings
FIG. 1 is a photograph of 2 suspected grains in an embodiment of the present application;
fig. 2 is a picture of 12 suspected grains in an embodiment of the present application.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
The LED crystal grain appearance detection method provided by the application comprises the following steps:
s1, carrying out optical detection on LED crystal grains to obtain an appearance parameter document, wherein the appearance parameter document comprises the area proportion of crystal grain defects;
the optical inspection is an appearance inspection method of the LED die to determine whether the appearance of the LED die meets the requirements, and specifically, the inspection standard is set according to the application field of the LED die and the requirements of the customer.
Preferably, the present application places the LED die in an appearance automatic optical inspection device for optical inspection.
The appearance parameter document further comprises a crystal grain defect area, wherein the crystal grain defect area ratio = crystal grain defect area/crystal grain light-emitting area, the crystal grain light-emitting area refers to the orthographic projection area of the LED crystal grain on the optical detection equipment, and the crystal grain defect area refers to the total orthographic projection area of the defect of the LED crystal grain on the optical detection equipment.
S2, dividing the LED crystal grains into first qualified crystal grains, first unqualified crystal grains and suspicious crystal grains according to the appearance parameter document;
specifically, the method for dividing the LED crystal grain into a first qualified crystal grain, a first disqualified crystal grain and a suspicious crystal grain comprises the following steps:
s21, setting a first judgment standard, wherein if the area ratio of the crystal grain defects of the LED crystal grains is smaller than or equal to the first judgment standard, the LED crystal grains are primary selected crystal grains, and if the area ratio of the crystal grain defects of the LED crystal grains is larger than the first judgment standard, the LED crystal grains are first unqualified crystal grains;
s22, setting a second judgment standard, wherein if the area ratio of the crystal grain defects of the primary selected crystal grains is smaller than the second judgment standard, the primary selected crystal grains are first qualified crystal grains, and if the area ratio of the crystal grain defects of the primary selected crystal grains is larger than or equal to the second judgment standard, the primary selected crystal grains are suspicious crystal grains;
the area ratio of the crystal grain defect in the second judgment standard is smaller than that in the first judgment standard.
In the existing method for detecting the appearance of the LED die, after the LED die is optically detected in step S1, the LED die is separated into a pass die and a fail die by the first judgment criterion only, but in the pass die, there is a small portion of abnormal die (fail die). If the first judgment standard is improved, the area proportion of the crystal grain defect is set to be small, the number of unqualified crystal grains is increased, and some LED crystal grains meeting the requirements are divided into unqualified crystal grains, so that waste is caused, and the cost is increased.
In order to select out the small part of abnormal grains, the qualification rate of the finished grains on the square sheet reaches 100%, and meanwhile, the cost can be reduced.
The second judging standard is more strict than the first judging standard, wherein the area ratio of the crystal grain defects in the second judging standard is smaller than that of the crystal grains in the first judging standard, so that unqualified crystal grains with large area ratio of the crystal grain defects are removed through the first judging standard, qualified crystal grains with small area ratio of the crystal grain defects are removed through the second judging standard, suspicious crystal grains with small area ratio of the crystal grain defects in a preset range are finally selected for repeated judgment, abnormal crystal grains can be prevented from being misjudged as qualified crystal grains, qualified crystal grains can be prevented from being misjudged as unqualified crystal grains, the qualification rate of finished crystal grains on a square sheet is improved, and meanwhile cost is reduced.
Taking 100 LED crystal grains as an example, setting the flaw area ratio of the LED crystal grains in the first judging standard as 40%, setting the flaw area ratio of the crystal grains in the second judging standard as 20%, wherein the flaw area ratio of 90 LED crystal grains is less than or equal to 40%, the flaw area ratio of 10 LED crystal grains is more than 40%, the flaw area ratio of 80 LED crystal grains in the 90 LED crystal grains is less than 20%, and the flaw area ratio of 10 LED crystal grains is more than or equal to 20% and less than or equal to 40%.
Because the flaw area proportion of the LED crystal grains in the first judging standard is 40%,10 first unqualified crystal grains and 90 first selected crystal grains exist in the 100 LED crystal grains;
since the defective area ratio of the grains in the second judgment standard is 20%, 80 first qualified grains and 10 suspicious grains are included in the 90 first selected grains.
After this step, 10 first failed grains and 80 first qualified grains are finished, and appearance detection is finished, the LED grains can be sorted and arranged on a square sheet, and the defect area ratio of the first failed grains and the first failed grains is strict, so that the detection accuracy of the existing AOI equipment on the grains is 100%.
In the method for detecting the appearance of an LED die, in addition to the classification of a pass die and a fail die by the defective area ratio of the die, it is necessary to classify the pass die and the fail die by the appearance defect type of the die. The appearance defect types include epitaxial appearance defects and contaminating appearance defects. It is difficult for existing AOI devices to distinguish whether the type of apparent defect of a die is a contaminating apparent defect or an epitaxial apparent defect.
In addition, since the defect area ratio of the LED die which is an epitaxial appearance defect is small, the LED die can be judged as a qualified die, but the defect area ratio of the LED die which is a polluted appearance defect is not so strict, if the qualified die and the unqualified die are divided only by the defect area ratio, misjudgment is easy to occur.
If the defect area ratio of the 10 suspicious grains is more than or equal to 20% and less than or equal to 40%, the 10 suspicious grains can be divided into qualified grains if the qualified grains and the unqualified grains are divided by the defect area ratio, but among the 10 suspicious grains, the appearance defect type of part of the grains is an epitaxial appearance defect, the appearance defect type is a grain with an epitaxial appearance defect, the qualified grains can be divided if the defect area ratio is less than 20%, and the unqualified grains can be divided if the defect area ratio is more than or equal to 20%; the appearance defect type of the other part of the crystal grains is pollution appearance defect, and the defect area ratio can be divided into qualified crystal grains as long as the defect area ratio is less than or equal to 40%.
Because the existing AOI equipment is difficult to distinguish whether the appearance defect type of the crystal grain is a polluted appearance defect or an epitaxial appearance defect, the LED crystal grain is divided into a first qualified crystal grain, a first unqualified crystal grain and a suspicious crystal grain by the first judging standard and the second judging standard, and then the suspicious crystal grain is subjected to re-judging so as to divide the suspicious crystal grain into a second qualified crystal grain and a second unqualified crystal grain.
Preferably, the area ratio of the crystal grain defect in the first judging standard is 30% -60%, and the area ratio of the crystal grain defect in the second judging standard is 10% -40%. By setting the area proportion of the crystal grain defects in the first judgment standard and the second judgment standard, the detection efficiency can be effectively improved.
S3, obtaining pictures of suspicious crystal grains, and judging appearance defect types of the suspicious crystal grains according to the pictures of the suspicious crystal grains, wherein the appearance defect types comprise epitaxial appearance defects and polluted appearance defects;
specifically, scanning the suspicious crystal grains to generate pictures of the suspicious crystal grains, and judging appearance defect types of the suspicious crystal grains according to the pictures of the suspicious crystal grains, wherein the appearance defect types comprise epitaxial appearance defects and polluted appearance defects.
The method and the device can scan the suspicious crystal grains through the camera of the AOI device or an external camera so as to obtain pictures of the suspicious crystal grains, and then the pictures of the suspicious crystal grains can be transmitted to the display device.
S4, dividing the suspicious crystal grains into second qualified crystal grains and second unqualified crystal grains according to the appearance defect types;
and if the appearance defect type of the suspicious crystal grain is a defect of an outward appearance, the suspicious crystal grain is a second unqualified crystal grain, and if the appearance defect type of the suspicious crystal grain is a defect of a polluted appearance, the suspicious crystal grain is a second qualified crystal grain, the first qualified crystal grain and the second qualified crystal grain form qualified crystal grains, and the first unqualified crystal grain and the second unqualified crystal grain form unqualified crystal grains.
The appearance defect types of the suspicious crystal grains are classified into a polluted appearance defect and an epitaxial appearance defect, wherein the LED crystal grains belonging to the polluted appearance defect are judged to be second qualified crystal grains as long as the flaw area is less than or equal to 40%; if the appearance defect of the suspected grain is an epitaxial appearance defect and the defect area ratio is less than 20%, the suspected grain is judged to be a second unqualified grain.
Referring to fig. 1, the ratio of the defect area of two suspicious grains in the graph is less than or equal to 40%, so that the conventional AOI method cannot find out the suspicious grains in the first judgment standard, and therefore, abnormal LED grains missed in AOI detection are required to be selected from a finished square sheet in a subsequent step by a manual visual inspection method so as to ensure that the appearance of each LED grain meets the quality requirement of shipment.
If the ratio of the flaw area in the first judgment standard is reduced, the qualified crystal grains are easily misjudged as unqualified crystal grains, so that waste is caused, and the yield is reduced. Therefore, the LED die is detected only by the first judgment criterion, and 100% of defective die detection rate cannot be achieved.
In order to solve the problems, the method and the device select suspicious grains from the normal grains by setting a second judgment standard, and then re-judge the suspicious grains so as to improve the unqualified grain detection rate of the AOI.
Firstly, sorting LED crystal grains according to the appearance defect types of the LED crystal grains, and classifying the appearance defect types of suspicious crystal grains into polluted appearance defects and epitaxial appearance defects; the suspicious grains are selected by the second judging standard because the requirements of the unqualified grains on the flaw area of the LED grains which are the pollution appearance defects and the flaw area proportion of the LED grains which are the epitaxy appearance defects are different.
Secondly, as shown in two suspicious grains in fig. 1, the appearance defect type of the suspicious grains on the left is a polluted appearance defect, the appearance defect of the suspicious grains on the right is an epitaxial appearance defect, the existing AOI is difficult to distinguish whether the defects of the suspicious grains are polluted appearance defects or epitaxial appearance defects, and the qualified grains can be judged as the qualified grains only if the defect area proportion of the LED grains which are epitaxial appearance defects is very small, but the defect area proportion requirement of the LED grains which are polluted appearance defects is not very strict, so that the application judges whether the appearance defects of the suspicious grains are polluted appearance defects or epitaxial appearance defects by generating pictures. Although the accuracy of judging the polluted appearance defect and the epitaxial appearance defect by the AOI is very low, after the picture is generated, the appearance defect of the LED crystal grain is easily judged to be the polluted appearance defect or the epitaxial appearance defect by manpower.
The appearance defect includes one or more of electrode dropping, light emitting layer falling, scratch, adhering pollutant, dent and crack, but is not limited thereto.
Specifically, the suspicious crystal grains can be scanned by a camera of the AOI equipment or an external camera so as to obtain pictures of the suspicious crystal grains, then the pictures of the suspicious crystal grains can be transmitted to display equipment, and unqualified crystal grains are selected from the suspicious crystal grains according to the pictures of the suspicious crystal grains.
In the existing manual visual inspection method, the LED crystal grains on the finished square sheet are required to be inspected through a microscope, the inspection area is limited, a large number of microscope equipment and visual inspection personnel are required, the cost is high, and the efficiency is low.
After the suspicious crystal grains generate the pictures, the pictures of the suspicious crystal grains can be transmitted to the display equipment for judgment, as shown in fig. 2, so that the visual field can be enlarged, the definition of the pictures can be improved, in addition, the pictures can be displayed and judged at the same time, and the accuracy of the re-judgment can be improved as well as the operator.
Referring to fig. 2, 12 LED dies in fig. 2 are suspicious dies, wherein the appearance defects of suspicious dies of numbers 1, 2, 3, 5, 7, 12 are general polluted appearance defects, and the defect area ratio of 20% to 40% is within the qualified range, so the suspicious dies of numbers 1, 2, 3, 5, 7, 12 are judged as qualified dies; although the suspicious grains of the numbers 4, 6, 8, 9, 10 and 11 have a defect area ratio of 20% to 40%, the appearance defect is an outward appearance defect, and therefore the suspicious grains of the numbers 4, 6, 8, 9, 10 and 11 are judged as unqualified grains.
Specifically, the present application may determine the suspicious grain in fig. 2 as a failed grain by clicking on it; or click on the corresponding location of the suspicious grain in fig. 2 (e.g., the box below the suspicious grain, the box above the suspicious grain, the box to the left of the suspicious grain, etc.).
Since the LED die detected on the AOI device is also on the wafer, after AOI detection, the LED die determined to be a qualified die needs to be subsequently arranged on a finished square sheet through a sorting device to become a finished product.
In order to avoid that the sorting equipment arranges unqualified grains on the finished square sheet so as to ensure that the LED grains on the finished square sheet are 100% of qualified grains, the position information of the suspicious grains is acquired while the picture of the suspicious grains is acquired.
Specifically, the suspicious crystal grains can be scanned through the camera of the AOI equipment or an external camera, and the position information of the suspicious crystal grains can be obtained by constructing an XY axis system.
After the unqualified grains are selected from the suspicious grains, the appearance information of the unqualified grains can be recorded through the position information of the unqualified grains. As shown in fig. 2, after the suspicious die No. 4 is determined as a failed die, the present application records the appearance information (such as the defect area ratio, the defect type, etc.) of the die according to the position information (such as coordinates) of the die on the LED wafer, and finally classifies the die as a bad grade according to the appearance information of the die.
Since the suspicious grains are classified as normal grains after passing the first judgment standard, the suspicious grains are all sorted on the finished square sheet in the information transmitted to the sorting equipment by the AOI equipment.
According to the method, the position information of the suspicious crystal grains is obtained while the pictures of the suspicious crystal grains are obtained, the appearance information of the qualified crystal grains and the appearance information of the unqualified crystal grains are obtained according to the position information and the appearance parameter document of the LED crystal grains, the qualified crystal grains are classified as good product grades according to the appearance information of the qualified crystal grains and the appearance information of the unqualified crystal grains, and the unqualified crystal grains are classified as bad product grades, so that the qualified crystal grains of which the LED crystal grains on a finished product square sheet are 100% are improved.
The above disclosure is only a preferred embodiment of the present invention, and it is needless to say that the scope of the invention is not limited thereto, and therefore, the equivalent changes according to the claims of the present invention still fall within the scope of the present invention.
Claims (8)
1. An LED die appearance detection method, comprising:
optically detecting the LED crystal grains to obtain an appearance parameter document, wherein the appearance parameter document comprises the area proportion of crystal grain defects;
dividing the LED crystal grain into a first qualified crystal grain, a first unqualified crystal grain and a suspicious crystal grain according to the appearance parameter document, wherein the crystal grain defect area ratio of the suspicious crystal grain is in a preset range, the crystal grain defect area ratio of the first qualified crystal grain is smaller than the preset range, and the crystal grain defect area ratio of the first unqualified crystal grain is larger than the preset range;
acquiring pictures of suspicious crystal grains, and judging appearance defect types of the suspicious crystal grains according to the pictures of the suspicious crystal grains, wherein the appearance defect types comprise epitaxial appearance defects and polluted appearance defects;
dividing the suspicious crystal grains into second qualified crystal grains and second unqualified crystal grains according to the appearance defect types, wherein if the appearance defect types of the suspicious crystal grains are epitaxial appearance defects, the suspicious crystal grains are second unqualified crystal grains, if the appearance defect types of the suspicious crystal grains are pollution appearance defects, the suspicious crystal grains are second qualified crystal grains, the first qualified crystal grains and the second qualified crystal grains form qualified crystal grains, and the first unqualified crystal grains and the second unqualified crystal grains form unqualified crystal grains;
the epitaxial appearance defects refer to appearance defects caused by epitaxial defects of the LED crystal grains, and the polluted appearance defects refer to appearance defects caused by external pollution of the LED crystal grains in the preparation process;
the method for dividing the LED crystal grain into a first qualified crystal grain, a first disqualified crystal grain and a suspicious crystal grain comprises the following steps:
setting a first judgment standard, wherein if the area ratio of the crystal grain defects of the LED crystal grains is smaller than or equal to the first judgment standard, the LED crystal grains are primary selected crystal grains, and if the area ratio of the crystal grain defects of the LED crystal grains is larger than the first judgment standard, the LED crystal grains are first unqualified crystal grains;
setting a second judgment standard, wherein if the grain defect area ratio of the primary selected grain is smaller than the second judgment standard, the primary selected grain is a first qualified grain, and if the grain defect area ratio of the primary selected grain is larger than or equal to the second judgment standard, the primary selected grain is a suspicious grain;
the area ratio of the crystal grain defects in the second judgment standard is smaller than that in the first judgment standard.
2. The LED die appearance inspection method of claim 1, wherein the appearance parameter document further comprises a die defect area, wherein the die defect area ratio = die defect area/die light exit area, the die light exit area being an area of an LED die projected forward onto a light exit surface of the optical inspection apparatus, the die defect area being a total area of the LED die projected forward onto the optical inspection apparatus.
3. The LED die appearance inspection method of claim 1, wherein the appearance defect type comprises one or more of dropped electrodes, dropped luminescent layers, scratches, adhering contaminants, dents, cracks.
4. The LED die appearance inspection method of claim 1, wherein the ratio of die defect areas in the first criterion is 30% -60% and the ratio of die defect areas in the second criterion is 10% -40%.
5. The LED die appearance inspection method of claim 1, wherein the suspected die is scanned to generate a picture of the suspected die;
and transmitting the picture of the suspicious crystal grain to display equipment, judging the appearance defect type of the suspicious crystal grain according to the picture of the suspicious crystal grain, and dividing the suspicious crystal grain into a second qualified crystal grain and a second unqualified crystal grain.
6. The LED die appearance detection method of claim 1, further comprising:
acquiring the position information of the LED crystal grains, wherein the position information of the LED crystal grains comprises the position information of qualified crystal grains and the position information of unqualified crystal grains;
according to the position information and the appearance parameter document of the LED crystal grains, appearance information of qualified crystal grains and appearance information of unqualified crystal grains are obtained;
and classifying the qualified crystal grains into good grades according to the appearance information of the qualified crystal grains and the appearance information of the unqualified crystal grains, and classifying the unqualified crystal grains into defective grades.
7. The LED die appearance inspection method of claim 6, wherein the method of obtaining positional information of the LED die comprises:
the method comprises the steps of carrying out optical detection on an LED crystal grain, acquiring position information of the LED crystal grain while acquiring an appearance parameter document, wherein the position information of the LED crystal grain comprises position information of a first qualified crystal grain, position information of a first unqualified crystal grain and position information of a suspicious crystal grain;
scanning the suspicious crystal grains to acquire pictures of the suspicious crystal grains, and acquiring position information of the suspicious crystal grains, wherein the position information of the suspicious crystal grains comprises position information of second qualified crystal grains and position information of second unqualified crystal grains;
the position information of the first qualified crystal grain and the position information of the second qualified crystal grain form the position information of the qualified crystal grain, and the position information of the first unqualified crystal grain and the position information of the second unqualified crystal grain form the position information of the unqualified crystal grain.
8. The LED die appearance inspection method of claim 6 or 7, wherein the sorting apparatus arranges the qualified dies on a finished square according to the appearance information of the qualified dies, and the appearance yield of the LED dies on the finished square is 100%.
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