CN117367914A - Test method for analyzing integrated circuit sample quality - Google Patents
Test method for analyzing integrated circuit sample quality Download PDFInfo
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- CN117367914A CN117367914A CN202311419424.7A CN202311419424A CN117367914A CN 117367914 A CN117367914 A CN 117367914A CN 202311419424 A CN202311419424 A CN 202311419424A CN 117367914 A CN117367914 A CN 117367914A
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- 238000010998 test method Methods 0.000 title claims abstract description 19
- 229910000765 intermetallic Inorganic materials 0.000 claims abstract description 83
- 229910000679 solder Inorganic materials 0.000 claims abstract description 80
- 238000010521 absorption reaction Methods 0.000 claims abstract description 44
- 238000010438 heat treatment Methods 0.000 claims abstract description 41
- 239000000126 substance Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 22
- 238000004140 cleaning Methods 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 22
- 150000001875 compounds Chemical class 0.000 claims description 16
- 238000000465 moulding Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000004506 ultrasonic cleaning Methods 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 238000005530 etching Methods 0.000 claims description 3
- 239000005022 packaging material Substances 0.000 claims description 3
- 235000001892 vitamin D2 Nutrition 0.000 claims 1
- 230000006378 damage Effects 0.000 abstract description 5
- 238000005516 engineering process Methods 0.000 abstract description 2
- 239000007788 liquid Substances 0.000 description 18
- 230000032683 aging Effects 0.000 description 8
- 230000032798 delamination Effects 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000003814 drug Substances 0.000 description 4
- 238000005476 soldering Methods 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 102100040381 Dol-P-Glc:Glc(2)Man(9)GlcNAc(2)-PP-Dol alpha-1,2-glucosyltransferase Human genes 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 101000890957 Homo sapiens Dol-P-Glc:Glc(2)Man(9)GlcNAc(2)-PP-Dol alpha-1,2-glucosyltransferase Proteins 0.000 description 1
- 101100072644 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) INO2 gene Proteins 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical group [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
- G01N17/006—Investigating resistance of materials to the weather, to corrosion, or to light of metals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0234—Metals, e.g. steel
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- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
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- Environmental Sciences (AREA)
- Acoustics & Sound (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Abstract
The present application relates to the field of integrated circuit technology, and in particular, to a test method for analyzing the quality of an integrated circuit sample. According to the method, after the integrated circuit sample to be analyzed is subjected to moisture absorption treatment, heating treatment is performed until the solder balls and the pad areas of the chip areas in the moisture absorption sample are peeled off, so that a test sample is obtained. After the initial sample is obtained by uncapping the test sample, the initial sample is subjected to cleaning treatment to obtain the target sample, and the intermetallic compound region of the target sample is analyzed. The application uses the mechanical external force to replace the chemical to enable the solder ball to be separated from the pad area, so that the damage to the intermetallic compound area after the chemical is used for corroding the solder ball is avoided, and the accuracy of analyzing the quality of the integrated circuit product is improved.
Description
Technical Field
The present application relates to the field of integrated circuit technology, and in particular, to a test method for analyzing the quality of an integrated circuit sample.
Background
During the bonding process of the integrated circuit, the bonding quality of the chip bonding pad area is determined by the area, thickness and distribution of intermetallic compounds (Intermetallic Compound, IMC) formed between the solder balls and the aluminum layer of the bonding pad area. The IMC layer directly determines the ball thrust and wire bond tension indicators in the ball quality inspection, and ultimately determines the integrated circuit product quality and service life. When the integrated circuit package is completed, the client side can conduct an electrified aging test, and the product quality and the service life of the integrated circuit are judged according to the aging test time. And when the aging test time is lower than the requirement of a client, judging that the product quality of the tested integrated circuit does not reach the standard.
For products which do not reach the standard in the charged aging test, the IMC layer of the integrated circuit needs to be analyzed, the existing test method mainly utilizes chemical liquid to remove the solder balls on the bonding pad area, and then the area, thickness and distribution condition of the IMC layer in the bonding pad area are observed, and finally whether the aging test is related to the IMC is judged. In the prior art, solder balls are etched by chemical solutions to clean the solder balls from the pad areas. However, the chemical liquid is used for corroding the solder balls, the chemical liquid is prepared in advance, the time, the proportion and the time for preparing the chemical liquid are not easy to control, the test time and the process are not easy to control, and the chemical liquid is easy to damage the IMC structure below the solder balls when corroding the solder balls, so that the accuracy of the subsequent IMC analysis results is influenced, and the accuracy of the quality of the integrated circuit products is influenced.
Disclosure of Invention
In view of the above, the present application provides a test method for analyzing the quality of an integrated circuit sample, which solves the technical problem of accuracy in analyzing the quality of an integrated circuit product by using a chemical liquid to corrode a solder ball in the prior art.
The present application provides a test method for analyzing the quality of an integrated circuit sample, the method comprising:
carrying out moisture absorption treatment on an integrated circuit sample to be analyzed to obtain a moisture absorption sample;
heating the moisture absorption sample until the solder balls and the bonding pad areas of the chip areas in the moisture absorption sample are stripped to obtain a test sample;
performing uncapping treatment on the test sample to obtain an initial sample;
cleaning the initial sample to obtain a target sample, wherein the solder balls in the target sample are separated from the pad area;
analyzing the mass of the integrated circuit sample based on the intermetallic region of the target sample.
In an alternative embodiment, the moisture absorption treatment is performed in a autoclave test chamber at 121 ℃/100% RH/2 atm/96H.
In an alternative embodiment, the heating the moisture-absorbing sample until the solder balls of the chip area and the pad area in the moisture-absorbing sample are peeled off, and obtaining the test sample includes:
heating the moisture absorption sample for a preset number of times in a preset heating environment to obtain a heated sample;
performing layered scanning on the heated sample;
and when layering does not occur in the chip area in the heating sample, performing heating treatment on the heating sample in the preset heating environment until layering occurs in the chip area in the heating sample, and determining that the solder balls in the chip area are peeled off from the bonding pad area to obtain the test sample.
In an alternative embodiment, the preset heating environment is 260 ℃ to 300 ℃.
In an alternative embodiment, the performing the uncapping process on the test sample to obtain the initial sample includes:
and corroding the surface plastic packaging material of the test sample to expose the chip area and the solder balls, so as to obtain the initial sample.
In an alternative embodiment, the etching the surface molding compound of the test sample comprises:
corroding the surface plastic package material of the test sample by using laser equipment until the surface plastic package material exposes out of the wire, and corroding the surface plastic package material exposed out of the wire by using chemicals; or (b)
And corroding the surface plastic package material of the test sample by using chemicals.
In an alternative embodiment, the performing a cleaning process on the initial sample to obtain a target sample includes:
performing ultrasonic cleaning treatment on the initial sample to enable the solder balls to be separated from the pad area;
and for the part of the solder ball which is not separated from the pad area, the solder ball is pulled away from the pad area by a hook needle, and the initial sample after the solder ball is separated from the pad area is determined as the target sample.
In an alternative embodiment, the subjecting the initial sample to the ultrasonic cleaning process includes:
and carrying out ultrasonic cleaning treatment on the initial sample by using ultrasonic equipment and deionized water.
In an alternative embodiment, the analyzing the mass of the integrated circuit sample based on the intermetallic region of the target sample comprises:
calculating an intermetallic area of the intermetallic region;
calculating the ratio of the intermetallic compound area to the area of the intermetallic compound area;
comparing the duty cycle with a preset duty cycle threshold;
when the duty ratio is larger than the preset duty ratio threshold, acquiring an intermetallic compound shape corresponding to the intermetallic compound area;
comparing the intermetallic compound shape with a preset intermetallic compound shape;
and when the intermetallic compound shape is determined to be in accordance with the preset intermetallic compound shape, obtaining a test result of qualified integrated circuit sample quality.
In an alternative embodiment, the method further comprises:
and when the duty ratio is smaller than the preset duty ratio threshold, obtaining a test result of unqualified integrated circuit sample quality.
In summary, according to the test method for analyzing the quality of the integrated circuit sample provided by the application, the integrated circuit sample to be analyzed is subjected to the moisture absorption treatment and then is subjected to the heating treatment until the solder balls and the pad areas of the chip areas in the moisture absorption sample are peeled off, so that the test sample is obtained. After the initial sample is obtained by uncapping the test sample, the initial sample is subjected to cleaning treatment to obtain the target sample, and the intermetallic compound region of the target sample is analyzed. The application uses the mechanical external force to replace the chemical to enable the solder ball to be separated from the pad area, so that the damage to the intermetallic compound area after the chemical is used for corroding the solder ball is avoided, and the accuracy of analyzing the quality of the integrated circuit product is improved.
Drawings
FIG. 1 is a flow chart of a prior art test method for analyzing the quality of an integrated circuit sample;
FIG. 2 is a flow chart illustrating a test method for analyzing integrated circuit sample quality according to an embodiment of the present application;
FIG. 3 is a schematic diagram of solder balls and pads;
FIG. 4 is a schematic diagram of a chip area hierarchy shown in an embodiment of the present application;
FIG. 5 is a schematic illustration of a test sample of exposed wire with surface molding compound shown in an embodiment of the present application;
FIG. 6 is a schematic diagram of an uncapped chip and solder ball area as shown in an embodiment of the present application;
fig. 7 is a schematic diagram of a solder ball break-away pad area as shown in an embodiment of the present application.
Detailed Description
The terminology used in the following embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification of this application, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates to the contrary. It should also be understood that the term "and/or" as used in this application is intended to encompass any or all possible combinations of one or more of the listed items.
The terms "first," "second," and the like, are used below for descriptive purposes only and are not to be construed as implying or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature, and in the description of embodiments of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
Referring to fig. 1, a flow chart of a prior art test method for analyzing the quality of an integrated circuit sample is shown, the test method for analyzing the quality of an integrated circuit sample comprising the following steps.
S11, uncovering the sample.
And (3) carrying out uncapping treatment on the test sample which does not reach the standard in the charged aging test by using chemicals, namely corroding the surface plastic package material of the test sample by using the chemicals until the chip area and the solder balls are exposed.
In some embodiments, after uncapping the test sample, the uncapped test sample may be placed in an oven for baking. For example, for a copper wire bonded test specimen, it is necessary to place the test specimen in an oven at 175 ℃ for a baking time of 3 hours, wherein 3 hours does not include the time taken for the lifting process of the oven. After baking the test specimen for 3 hours, the test specimen was taken out of the oven with a heat-resistant glove and cooled.
S12, removing the solder balls by using chemical liquid medicine.
A chemical for removing the solder balls is pre-configured. For example, for a test sample of copper wire bonding, nitric acid at a concentration of 65% to 68% may be used to remove solder balls; for a gold wire bonded test sample, a potassium hydroxide solution can be prepared according to a weight ratio of 1 to 50, and the solder balls are removed by using the potassium hydroxide solution; for the test sample to which the alloy wire is bonded, fuming nitric acid of 98% concentration may be used, and fuming nitric acid may be used to remove the solder balls.
Because the chemical liquid needs to be pre-configured, the configuration time and the configuration proportion are not easy to control, and then the chemical liquid is used for corroding the solder balls, so that intermetallic compounds below the solder balls are easy to destroy.
S13, ultrasonic cleaning.
The test sample after the solder balls are removed is cleaned by ultrasonic equipment and deionized, and residual chemical liquid and attached impurities are removed.
S14, intermetallic compound measurement and inspection.
The test sample pad area was analyzed for regions of residual intermetallic compounds.
In the prior art, the solder balls bonded on the pad areas are etched by using the pre-configured chemical, so that the intermetallic compound areas below the solder balls are exposed, and the intermetallic compound areas are conveniently analyzed by using a microscope. However, the chemical liquid needs to be configured in advance, so that the test time is uncertain, the amount of the chemical liquid needed to be used in the test process is unknown, the test process is not easy to control, and the chemical liquid is easy to damage the intermetallic compound structure, so that the result of the subsequent analysis of the intermetallic compound area is influenced, and the accuracy of the quality analysis of the integrated circuit product is influenced.
Referring to fig. 2, a flowchart of a test method for analyzing the quality of an integrated circuit sample is shown in an embodiment of the present application, and the test method for analyzing the quality of an integrated circuit sample includes the following steps.
S21, carrying out moisture absorption treatment on the integrated circuit sample to be analyzed to obtain a moisture absorption sample.
When the charged aging test does not reach the standard, the test sample which does not reach the standard, namely the integrated circuit sample to be analyzed, needs to be subjected to intermetallic compound area analysis to judge whether the charged aging test is related to intermetallic compounds.
In some alternative embodiments, the integrated circuit sample to be analyzed may be placed in a autoclave test chamber (Pressure Cooker Test, PCT) and subjected to a moisture absorption treatment under conditions of a temperature of 121 c, a relative humidity of 100% rh, a pressure of 2atm, and a treatment time of 96 hours, and the integrated circuit sample after the moisture absorption treatment is referred to as a moisture absorption sample. Under the condition of high temperature, high pressure and high relative humidity of the PCT high-pressure stewing test box, the moisture absorption speed of the integrated circuit sample can be increased, the moisture absorption proportion of the integrated circuit sample can be increased, the moisture absorption time of the integrated circuit sample can be shortened, and the moisture absorption proportion of the integrated circuit sample can reach 100%.
In some embodiments, the integrated circuit sample to be analyzed may also be placed in air for a moisture absorption process, but typically the integrated circuit sample will require 7 days or more of air before moisture absorption can begin. In other embodiments, the integrated circuit sample to be analyzed may also be placed in a conventional constant temperature and humidity chamber, for example, a chamber having a temperature of 60 ℃ and a relative humidity of 60% rh, for moisture absorption. In this case, the integrated circuit sample needs to be placed in a constant temperature and humidity cabinet at 60 ℃ and 60% rh for 40 hours or even longer before moisture absorption begins. Aiming at the moisture absorption treatment carried out in the air or a constant temperature and humidity box, the problems of long moisture absorption time and low moisture absorption proportion caused by slow moisture absorption speed exist.
When the integrated circuit sample to be analyzed is subjected to the moisture absorption treatment for 96 hours according to 121 ℃/100% RH/2atm using a PCT autoclave test chamber, the moisture absorption rate can be increased and the moisture absorption ratio can be increased.
S22, heating the moisture absorption sample until the solder balls and the bonding pad areas of the chip areas in the moisture absorption sample are peeled off, so as to obtain a test sample.
After the moisture-absorbing sample is obtained, the moisture-absorbing sample needs to be subjected to heat treatment, so that the solder balls in the chip area and the bonding pad area in the moisture-absorbing sample are peeled off.
In an alternative embodiment, the heating the moisture-absorbing sample until the solder balls of the chip area and the pad area in the moisture-absorbing sample are peeled off, and obtaining the test sample includes:
heating the moisture absorption sample for a preset number of times in a preset heating environment to obtain a heated sample;
performing layered scanning on the heated sample;
and when the chip area in the heating sample does not have layering, performing heating treatment on the heating sample in the preset heating environment until the chip area in the heating sample has layering, determining that the solder balls in the chip area are peeled off from the pad area, and obtaining the test sample. Referring to fig. 3, the solder balls are shown above the pads, and if a gap exists between the solder balls and the pads, this indicates that the solder balls in the chip area are stripped from the pad area.
The preset heating environment may be a preset heating environment of 260 ℃ to 300 ℃, and the temperature may be at any one temperature node within a range of 260 ℃ to 300 ℃, for example, 280 ℃, 290 ℃. In some embodiments, the heating environment in the reflow soldering apparatus may be set to any one of the temperature nodes in the range of 260 ℃ to 300 ℃ in advance, and the moisture-absorbing sample may be placed in the reflow soldering apparatus for heat treatment. For example, the temperature of the reflow apparatus may be set to 260 ℃, and the moisture-absorbing sample may be placed in the reflow apparatus at 260 ℃ for 3 times of heat treatment, to obtain a heated sample.
In general, since the plastic package material of the integrated circuit main body is a macromolecular structure, after the integrated circuit sample to be analyzed is subjected to moisture absorption treatment, external water molecules enter the integrated circuit through gaps between macromolecules or the combination part of pins and the plastic package body, and are gathered among all material interfaces of the integrated circuit. When water molecules at each material interface are subjected to heat treatment through reflow soldering equipment, internal water vapor expansion is caused by high temperature to cause delamination of the internal material interface, and the mechanical stress generated by delamination can cause stripping of solder balls and bonding pad areas of a chip area in a moisture absorption sample. However, due to the difference in moisture absorption conditions, preset heating environments, the difference in structure or materials existing in the integrated circuit sample itself, or in some severe or severe conditions, there may be cases where the solder balls in the chip area are not peeled off from the pad area after the moisture absorption treatment and the heating treatment.
After the moisture-absorbing sample is heated by the reflow soldering device to obtain a heated sample, in order to ensure that the solder balls and the bonding pad areas in the chip area in the heated sample are peeled off, the heated moisture-absorbing sample, namely the heated sample, needs to be scanned. In some embodiments, the heated sample may be scanned using an ultrasound scanning device. Because the chip and the surface plastic package material are pulled out after the moisture absorption treatment and the heating treatment, when the chip and the surface plastic package material are separated, a large amount of air exists between the chip and the surface plastic package material. When the ultrasonic scanning equipment is used for scanning the heated sample, according to the principle of ultrasonic waves, the separation between the chip and the surface plastic package material is different from the reflection waveform generated by the fact that the separation between the chip and the surface plastic package material does not occur. When the chip and the surface plastic packaging material are separated, the generated reflection waveform is upward, which indicates that layering occurs in the chip area in the heated sample, namely, the solder balls in the chip area and the pad area are peeled off. When the chip and the surface plastic package material are not separated, the generated reflection waveform is downward, so that the chip area in the heated sample is not layered, namely the solder balls in the chip area are not peeled off from the pad area.
In some embodiments, in order to more intuitively determine whether the chip area is layered during scanning by the ultrasonic scanning device, the direction of the reflected waveform may be filled in a one-to-one correspondence with the preset color. For example, the heated sample may be automatically color filled, e.g., red, when the reflected waveform is up; the heated sample may be automatically color filled, for example white, when the reflected waveform is down. After the heated sample is filled with the color, the color displayed by the heated sample can be visually seen through a display device in communication connection with the ultrasonic scanning device, and whether layering occurs in the chip area is judged according to the displayed color. When the chip area is layered, the heated sample can be seen to be red, and the solder balls in the chip area are determined to be peeled off from the pad area, so that a test sample is obtained. When delamination did not occur in the chip area, the heated sample was seen to appear white, confirming that the solder balls in the chip area did not peel off from the pad area. Referring to FIG. 4, DIE1 is shown in red, indicating delamination of the chip area; DIE2 is shown in white, indicating that no delamination of the chip area has occurred.
When the heated sample is scanned by the ultrasonic scanning device, if it is determined that delamination occurs in the chip region in the heated sample, step S23 is performed; if it is determined that no delamination has occurred in the chip region in the heated sample, step S22 is performed.
S23, carrying out uncapping treatment on the test sample to obtain an initial sample.
In order to prevent the chip of the integrated circuit from being affected and damaged by the external environment, epoxy thermosetting resins are often used as surface molding compounds to encapsulate the chip, metal leads, and inner legs of the lead frame, which are easily damaged. When the intermetallic compound in the internal chip area needs to be analyzed, the test sample after layering in the chip area needs to be subjected to uncovering treatment, namely the surface plastic package material of the test sample is removed.
In an alternative embodiment, the surface molding compound of the test sample may be etched to expose the chip area and the solder balls, resulting in the initial sample.
In one embodiment, the surface molding compound may be etched using a laser apparatus (e.g., a laser etcher) first, when the surface molding compound is etched to expose the wire, as shown in fig. 5. The remaining surface molding compound is then etched with chemicals that decompose the surface molding compound, rendering the surface molding compound brittle and eventually dissolved. Once the surface molding compound is removed, the chip area inside and the solder balls on the surface of the chip area are exposed, and the test sample after the surface molding compound is removed is determined as an initial sample, as shown in fig. 6. If only the laser device is used to etch the surface molding compound of the test sample to expose the chip area and the solder balls, the laser device may affect the chip area, resulting in destruction of the intermetallic compound.
In some embodiments, chemicals may also be used throughout the etching of the surface molding compound of the test sample until the chip area and solder balls are exposed. However, the chemical agent needs to be prepared in advance, and the corrosion rate of the chemical agent is much higher than that of the laser device.
And S24, cleaning the initial sample to obtain a target sample, wherein the solder balls in the target sample are separated from the pad area.
Because the surface molding compound is corroded by using the laser equipment and the chemicals, residues of the surface molding compound and residual liquid of the chemicals remain in the chip area. Second, although the solder balls have been peeled off from the chip area, the solder balls remain attached to the surface of the chip area, and the initial sample needs to be cleaned.
In an alternative embodiment, the performing a cleaning process on the initial sample to obtain a target sample includes:
performing ultrasonic cleaning treatment on the initial sample to enable the solder balls to be separated from the pad area;
and for the part of the solder ball which is not separated from the pad area, the solder ball is pulled away from the pad area by a hook needle, and the initial sample after the solder ball is separated from the pad area is determined as the target sample.
In some embodiments, the initial sample may be placed in a cleaning vessel of an ultrasonic device, wherein the cleaning vessel contains deionized water. When the ultrasonic equipment is started, the ultrasonic equipment generates ultrasonic waves, the ultrasonic waves can form small bubbles in deionized water, then the small bubbles collapse rapidly to generate micro shock waves, and residues, chemical residual liquid and solder balls of the surface plastic package materials which are adhered to the chip area of the initial sample can be decomposed and removed. When the ultrasonic device cleaning is completed, the initial sample is taken out of the cleaning vessel and rinsed with pure water to remove any remaining deionized water.
Typically, the solder balls will disengage from the land areas after the initial sample is cleaned using ultrasonic equipment and deionized water. However, if the situation that the solder balls are not separated from the pad area is found in the initial sample, the solder balls which are not separated from the pad area can be lifted off the pad area by using the hook needle until the solder balls are completely separated from the pad area, and the initial sample after the solder balls are completely separated from the pad area is determined as the target sample, as shown in fig. 7.
S25, analyzing the quality of the integrated circuit sample according to the intermetallic compound region of the target sample.
When the solder balls are completely separated from the pad area, the intermetallic compound area is exposed, and the intermetallic compound area is further analyzed.
In an alternative embodiment, the analyzing the mass of the integrated circuit sample based on the intermetallic region of the target sample comprises:
calculating an intermetallic area of the intermetallic region;
calculating the ratio of the intermetallic compound area to the area of the intermetallic compound area;
comparing the duty cycle with a preset duty cycle threshold;
when the duty ratio is larger than the preset duty ratio threshold, acquiring an intermetallic compound shape corresponding to the intermetallic compound area;
comparing the intermetallic compound shape with a preset intermetallic compound shape;
and when the intermetallic compound shape is determined to be not in accordance with the preset intermetallic compound shape, obtaining a test result that the intermetallic compound region is qualified.
In some embodiments, the intermetallic region may be analyzed using image analysis software and a measurement microscope communicatively coupled to an electronic device in which the image analysis software is installed. The image analysis software can perform color filling according to non-intermetallic compounds in the intermetallic compound regions, namely, the regions which are not subjected to color filling in the intermetallic compound regions are intermetallic compounds, so that the intermetallic compound area can be calculated and the ratio of the intermetallic compound area to the intermetallic compound area in the intermetallic compound regions, namely, the ratio of the intermetallic compound area to the intermetallic compound area in the intermetallic compound regions can be calculated and obtained.
In some embodiments, a duty ratio threshold may be preset, the calculated duty ratio of the intermetallic compound area to the intermetallic compound area is compared with a preset duty ratio threshold, and when the duty ratio is smaller than the preset duty ratio threshold, a test result that the intermetallic compound area is unqualified is obtained. And when the duty ratio is larger than a preset duty ratio threshold value, acquiring the intermetallic compound shape, comparing the intermetallic compound shape with the preset intermetallic compound shape, and when the intermetallic compound shape is determined to be in accordance with the preset intermetallic compound shape, obtaining a test result that the integrated circuit sample is unqualified. And when the intermetallic compound shape is determined to be not in accordance with the preset intermetallic compound shape, obtaining a test result that the integrated circuit sample is qualified.
Illustratively, the predetermined intermetallic compound shape is cat-eye-like assuming that the predetermined duty cycle threshold is set to 80%. Assuming that the intermetallic compound area is 73, the intermetallic compound area is 100, and the calculated ratio of the intermetallic compound area to the intermetallic compound area is 73%, a test result is obtained in which the integrated circuit sample is unacceptable. Assuming that the intermetallic compound area is 93, the intermetallic compound area is 100, the calculated ratio of the intermetallic compound area to the intermetallic compound area is 93%, the obtained intermetallic compound is cat-eye-like in shape, and the test result that the integrated circuit sample is unqualified is obtained. And assuming that the intermetallic compound area is 93, the intermetallic compound area is 100, the calculated ratio of the intermetallic compound area to the intermetallic compound area is 93%, the obtained intermetallic compound is spherical in shape, and the test result that the integrated circuit sample is qualified is obtained.
It should be noted that the above duty ratio threshold is merely illustrative, and in practical application, the setting of the duty ratio threshold is adjusted according to the actual requirement.
Compared with the prior art, the test sample after the cover is corroded by using the chemical liquid medicine, the solder ball and the bonding pad area are separated by replacing the chemical liquid medicine by the mechanical external force, the influence of the chemical liquid medicine on corrosion of intermetallic compounds below the solder ball is reduced, and the accuracy of the subsequent analysis of the quality of the integrated circuit product according to the intermetallic compounds is improved.
The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes in structure, shape and principle of this application should be covered in the protection scope of this application.
Claims (10)
1. A test method for analyzing the quality of an integrated circuit sample, the method comprising:
carrying out moisture absorption treatment on an integrated circuit sample to be analyzed to obtain a moisture absorption sample;
heating the moisture absorption sample until the solder balls and the bonding pad areas of the chip areas in the moisture absorption sample are stripped to obtain a test sample;
performing uncapping treatment on the test sample to obtain an initial sample;
cleaning the initial sample to obtain a target sample, wherein the solder balls in the target sample are separated from the pad area;
analyzing the mass of the integrated circuit sample based on the intermetallic region of the target sample.
2. The test method for analyzing the quality of an integrated circuit sample according to claim 1, wherein the moisture absorption treatment is performed in a high pressure retort test box under conditions of 121 ℃/100% rh/2 atm/96H.
3. The method of claim 2, wherein the heating the moisture-absorbing sample until the solder balls and the land areas of the chip area in the moisture-absorbing sample are peeled off, the obtaining the test sample comprises:
heating the moisture absorption sample for a preset number of times in a preset heating environment to obtain a heated sample;
performing layered scanning on the heated sample;
and when layering does not occur in the chip area in the heating sample, performing heating treatment on the heating sample in the preset heating environment until layering occurs in the chip area in the heating sample, and determining that the solder balls in the chip area are peeled off from the bonding pad area to obtain the test sample.
4. A test method for analyzing the quality of an integrated circuit sample according to claim 3, wherein the predetermined heating environment is 260 ℃ to 300 ℃.
5. A test method for analyzing the quality of an integrated circuit sample according to claim 3, wherein said subjecting said test sample to a decap process comprises:
and corroding the surface plastic packaging material of the test sample to expose the chip area and the solder balls, so as to obtain the initial sample.
6. The method of claim 5, wherein etching the surface molding compound of the test sample comprises:
corroding the surface plastic package material of the test sample by using laser equipment until the surface plastic package material exposes out of the wire, and corroding the surface plastic package material exposed out of the wire by using chemicals; or (b)
And corroding the surface plastic package material of the test sample by using chemicals.
7. The method of claim 5, wherein the performing a cleaning process on the initial sample to obtain a target sample comprises:
performing ultrasonic cleaning treatment on the initial sample to enable the solder balls to be separated from the pad area;
and for the part of the solder ball which is not separated from the pad area, the solder ball is pulled away from the pad area by a hook needle, and the initial sample after the solder ball is separated from the pad area is determined as the target sample.
8. The method for analyzing the quality of an integrated circuit sample according to claim 7, wherein said subjecting said initial sample to an ultrasonic cleaning process comprises:
and carrying out ultrasonic cleaning treatment on the initial sample by using ultrasonic equipment and deionized water.
9. The method of claim 7, wherein analyzing the mass of the integrated circuit sample based on the intermetallic region of the target sample comprises:
calculating an intermetallic area of the intermetallic region;
calculating the ratio of the intermetallic compound area to the area of the intermetallic compound area;
comparing the duty cycle with a preset duty cycle threshold;
when the duty ratio is larger than the preset duty ratio threshold, acquiring an intermetallic compound shape corresponding to the intermetallic compound area;
comparing the intermetallic compound shape with a preset intermetallic compound shape;
and when the intermetallic compound shape is determined to be in accordance with the preset intermetallic compound shape, obtaining a test result of qualified integrated circuit sample quality.
10. The test method for analyzing integrated circuit sample quality of claim 9, further comprising:
and when the duty ratio is smaller than the preset duty ratio threshold, obtaining a test result of unqualified integrated circuit sample quality.
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