CN118010460A - Sample preparation method for representing chip lead bonding micro-welding spot structure - Google Patents
Sample preparation method for representing chip lead bonding micro-welding spot structure Download PDFInfo
- Publication number
- CN118010460A CN118010460A CN202311821444.7A CN202311821444A CN118010460A CN 118010460 A CN118010460 A CN 118010460A CN 202311821444 A CN202311821444 A CN 202311821444A CN 118010460 A CN118010460 A CN 118010460A
- Authority
- CN
- China
- Prior art keywords
- sample
- chip
- micro
- grinding
- welding spot
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000003466 welding Methods 0.000 title claims abstract description 135
- 238000005464 sample preparation method Methods 0.000 title claims abstract description 17
- 238000000227 grinding Methods 0.000 claims abstract description 102
- 238000005498 polishing Methods 0.000 claims abstract description 63
- 244000137852 Petrea volubilis Species 0.000 claims abstract description 62
- 238000000034 method Methods 0.000 claims abstract description 59
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 41
- 230000003287 optical effect Effects 0.000 claims abstract description 22
- 239000000203 mixture Substances 0.000 claims abstract description 14
- 239000004593 Epoxy Substances 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 10
- 239000002390 adhesive tape Substances 0.000 claims abstract description 7
- 239000003822 epoxy resin Substances 0.000 claims description 34
- 229920000647 polyepoxide Polymers 0.000 claims description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 229920002120 photoresistant polymer Polymers 0.000 claims description 11
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 claims description 8
- PXKLMJQFEQBVLD-UHFFFAOYSA-N bisphenol F Chemical compound C1=CC(O)=CC=C1CC1=CC=C(O)C=C1 PXKLMJQFEQBVLD-UHFFFAOYSA-N 0.000 claims description 6
- -1 glycidyl ester Chemical class 0.000 claims description 6
- 238000007711 solidification Methods 0.000 claims description 6
- 230000008023 solidification Effects 0.000 claims description 6
- 125000001931 aliphatic group Chemical group 0.000 claims description 5
- 150000001412 amines Chemical group 0.000 claims description 5
- 150000008064 anhydrides Chemical class 0.000 claims description 5
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical compound C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 claims description 5
- AFEQENGXSMURHA-UHFFFAOYSA-N oxiran-2-ylmethanamine Chemical compound NCC1CO1 AFEQENGXSMURHA-UHFFFAOYSA-N 0.000 claims description 3
- 229910000679 solder Inorganic materials 0.000 claims description 2
- 238000000059 patterning Methods 0.000 claims 5
- 238000002360 preparation method Methods 0.000 abstract description 14
- 238000004458 analytical method Methods 0.000 abstract description 4
- 239000000463 material Substances 0.000 abstract description 3
- 239000000523 sample Substances 0.000 description 249
- 230000008569 process Effects 0.000 description 22
- 239000000110 cooling liquid Substances 0.000 description 13
- 238000005516 engineering process Methods 0.000 description 7
- 238000007517 polishing process Methods 0.000 description 6
- 238000012512 characterization method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000002932 luster Substances 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- VILCJCGEZXAXTO-UHFFFAOYSA-N 2,2,2-tetramine Chemical group NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 description 2
- 239000005062 Polybutadiene Substances 0.000 description 2
- 239000004841 bisphenol A epoxy resin Substances 0.000 description 2
- 239000004842 bisphenol F epoxy resin Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000004845 glycidylamine epoxy resin Substances 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 150000002978 peroxides Chemical class 0.000 description 2
- 229920002857 polybutadiene Polymers 0.000 description 2
- 229960001124 trientine Drugs 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 238000012536 packaging technology Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000007494 plate polishing Methods 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Landscapes
- Sampling And Sample Adjustment (AREA)
Abstract
The invention relates to a sample preparation method for representing a chip lead bonding micro-welding spot structure, and belongs to the technical field of material analysis and representation sample preparation. The method comprises the steps of horizontally fixing a chip sample in a mold in a clamping manner, adding an epoxy resin-curing agent mixture into the mold to submerge the chip sample and a clamp, standing and solidifying to obtain a cold mounting; under the observation of an optical microscope, adopting sand paper with different mesh numbers to grind the cold insert step by step: the cold-inlaid chip is firstly grinded to be 0.8-1.2 mm away from the end face of the chip sample negative electrode, the chip negative electrode end of the cold-inlaid chip is subjected to rough grinding, fine grinding and polishing to be the section position of the target micro welding spot, and a traceless adhesive tape is adopted to cover the chip negative electrode end of the cold-inlaid chip; coarsely grinding the positive end of the cold-inlaid chip until the metal end is exposed to obtain a chip bonding micro-welding spot tissue sample; and (5) observing and characterizing the chip bonding micro-welding spot tissue sample by adopting an electron microscope. The invention has lower sample preparation cost, simple sample preparation method and can obtain clear and complete bonding micro-welding spot tissue sample in a short time.
Description
Technical Field
The invention relates to a sample preparation method for representing a chip lead bonding micro-welding spot structure, and belongs to the technical field of material analysis and representation sample preparation.
Background
Semiconductors are currently in the post-molar age, packaging technology being a major aspect of electronics manufacturing. Advanced 5G communication technology and three-dimensional integrated circuits (3D-ICs) in the big data age have made microelectronic interconnection technology a critical challenge in developing finer pitch wire-bond interconnection technology for ever more dense I/O. Wire bonding plays a key role in achieving electrical connection of the semiconductor chip with the leads/pads. The largest gap between the current domestic lead bonding products and foreign products is concentrated on the service reliability after bonding. And the determining factor of the reliability is the property change process of the bonding micro-welding spot interface in the service process. Due to the special geometry of the micro welding spots and the complexity of application scenes, the inside of the welding spots has the changes of current density, temperature, stress, chemical concentration and the like in the service process. When the bonding micro-welding spot is in service, the bonding micro-welding spot is subjected to stress field coupling effects such as electricity, heat, force and the like, so that various failure modes exist in the micro-welding spot, such as: an interfacial intermetallic compound (IMC) layer is thickened, and a chip Under Bump Metallization (UBM) layer is depleted, a Kelvin hole is formed, and electromigration is performed. Based on the above, how to clearly explain and characterize the structural evolution between the micro-welding spots and the chip interconnection layers is important to the improvement of the reliability of the wire bonding product in China. However, since the bonding pads of the wire bond are all in a micro-scale structure, the conventional sample preparation method is difficult to obtain an observation section, so that development of a micro-pad sample preparation method suitable for representing the change process of the microstructure of the micro-pad of the wire bond of the chip is needed.
At present, a method of combining a polishing method with an X-ray three-dimensional microscope (X-ray) is generally adopted in the semiconductor industry to observe the positions of micro-welding spots to prepare a sample of a bonding micro-welding spot tissue characterization, but the equipment has higher cost and complex operation, and a conventional laboratory generally does not have the equipment. The disadvantage of the device is that the sample has a simple shape under the X-ray three-dimensional microscope, has no clear structural characteristics, and is unfavorable for observation and positioning during grinding and polishing. The method generally takes 1-2 weeks to complete single sample preparation, and has low success rate. In addition, advanced electron microscopy techniques have been increasingly applied in recent years to the characterization of micro-pads, and focused ion beam cutting (FIB) can be used to prepare wire-bond micro-pad cross-sections. However, FIB technology is extremely expensive to remove equipment, and requires a high level of skill in the art (at least five years or more of the skilled use of electron microscopes is required). After the cross section sample preparation is carried out by adopting FIB cutting, the sample and the sample table form an included angle of 54 degrees, and when the grain orientation analysis and the stress analysis are required to be carried out on the micro welding spots, the space state of the sample does not accord with the test condition of the EBSD, and the EBSD probe cannot correspond to the observation position of the cross section of the sample, so that the corresponding Electron Back Scattering Diffraction (EBSD) characterization cannot be completed. Because of the technical difficulty, the current FIB technology can only be used for preparing the common morphology observation section of the micro-welding spot, and the structural evolution of the micro-welding spot cannot be further explored. In addition, the FIB technology has higher requirements on the height and packaging of the chip, and the polymer plastic packaging material wrapped on the chip during the packaging of the chip volatilizes a large amount during the FIB processing to influence the shooting effect of the electron microscope.
Disclosure of Invention
Aiming at the problems of long time consumption, high cost, complex technical requirements and the like, the invention provides a sample preparation method for representing a chip wire bonding micro-welding spot structure, namely, a chip sample is subjected to cold mounting by adopting a mixture of epoxy resin (such as bisphenol A epoxy resin, bisphenol F epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin or glycidyl amine epoxy resin) and curing agent (such as amine curing agent, anhydride curing agent or latent curing agent), and the chip sample is kept horizontally placed in the cold mounting process, so that the general position of micro-welding spots in the cold mounting can be observed by naked eyes, and the position of the micro-welding spots can be clearly observed by using an optical microscope; the sample grinding process can be performed quickly until the sample is close to the position of the micro welding spot, then the time required for grinding the sample to the position of the micro welding spot can be estimated more accurately through observation of an optical microscope, the sample is accurately ground to the section position of the micro welding spot, the sample preparation time is shortened greatly, and the sample preparation success rate is improved. The method has the advantages of short time, simple equipment materials, easy operation and high sample preparation success rate, and can judge the position of the welding spot in grinding and polishing in time by naked eyes; the section obtained after sample preparation can simultaneously meet the requirements of tissue section observation and fine structure characterization of the EBSD of the conventional micro-welding spots.
A sample preparation method for representing a chip lead bonding micro-welding spot structure comprises the following specific steps:
(1) Fixing a chip sample in a die in a clamping and horizontal manner, wherein the chip sample is a photoresist-removed chip sample, and the exposed surfaces of micro welding spots of the chip sample are clamped and fixed downwards; the chip sample is a chip sample without photoresist removal, a marking surface of the chip sample is clamped and fixed downwards, and the marking surface is the back surface of the exposed surface of the micro welding spot; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Adopt different mesh numbers sand paper to grind the appearance step by step to cold mosaic: under the observation of an optical microscope, the cold-mounting is firstly grinded to be 0.8-1.2 mm away from the negative end face of the chip sample, the negative end of the chip of the cold-mounting is roughly grinded, finely grinded and polished to the section position of the target micro-welding point, and a traceless adhesive tape is used for covering the negative end of the chip of the cold-mounting;
(3) Coarsely grinding the positive end of the cold-inlaid chip until the metal end is exposed to obtain a chip bonding micro-welding spot tissue sample; the rough grinding can be carried out by adopting 240-mesh sand paper;
(4) And (5) observing and characterizing the chip bonding micro-welding spot tissue sample by adopting an electron microscope.
The epoxy resin in the step (1) is bisphenol A type epoxy resin, bisphenol F type epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin or glycidyl amine type epoxy resin, and the viscosity is 10-10000 mPa.s; the curing agent is an amine curing agent, an anhydride curing agent or a latent curing agent; the epoxy resin accounts for 65 to 98.5 percent of the epoxy resin-curing agent mixture, and the curing agent accounts for 1.5 to 35 percent of the epoxy resin-curing agent mixture.
And (3) when the chip sample in the step (1) is a chip sample without photoresist removal, marking the position of the micro welding spot of the estimated chip sample at a position 1.9-2.1 mm away from the positive end of the chip sample.
The chip sample is a photoresist-removed chip sample, and the specific method for grinding the chip sample step by step in the step (2) comprises the following steps of:
1) Preliminary grinding the sample by 240-mesh sand paper until the distance from the end face of the negative electrode of the chip sample is 0.8-1.2 mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample by using 1200-mesh sand paper until the lead position is observed on the negative end face of the chip sample;
4) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
5) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample;
6) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
The chip sample is a chip sample without photoresist removal, and the specific method for grinding the chip sample step by step in the step (2) comprises the following steps of:
1) Preliminary grinding the sample by 240-mesh sand paper until the distance from the end face of the negative electrode of the chip sample is 0.8-1.2 mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample to the end face of the negative electrode by using 1200-mesh sand paper, wherein the distance from the sample marking position of the chip is 0.8-1.2 mm;
4) Grinding the sample to the marked position of the negative end face of the chip sample by using 2000-mesh sand paper;
5) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
6) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample;
7) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
The polishing method in the step (2) comprises the following specific steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length is not more than 200 mu m;
2) Finely polishing the sample with polishing paste of 1.5 mu m for many times until the section of the micro welding spot of the sample has no scratches or the number of scratches is not more than 5, the depth of the scratches is not more than 2 mu m, and the length is not more than 50 mu m;
3) And (3) removing the polishing paste on the surface of the micro welding spot by adopting clean water micro polishing.
The beneficial effects of the invention are as follows:
(1) The invention adopts the mixture of epoxy resin (such as bisphenol A epoxy resin, bisphenol F epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin or glycidyl amine epoxy resin) and curing agent (such as amine curing agent, anhydride curing agent or latent curing agent) to carry out cold sample-in on the chip sample, and maintains the chip sample to be horizontally placed in the cold sample-in process, so that the general position of micro welding spots in the cold sample-in can be observed by naked eyes, and the position of the micro welding spots can be clearly observed by using an optical microscope; the sample can be rapidly ground to a position close to the micro-welding spot in the sample grinding process, and then the time required for grinding to the micro-welding spot position can be estimated more accurately by observing through an optical microscope, and the cross section position of the micro-welding spot can be accurately ground, so that the sample preparation success rate is improved;
(2) Unlike the traditional technology, which needs repeated grinding observation and changing of finer sand paper, the invention only needs grinding to the position near the micro welding point once and then grinding to the section position of the micro welding point slowly, the grinding steps are greatly reduced, and the sample preparation time can be greatly shortened;
(3) The method only needs to use a common optical microscope and a polishing machine, is simple to operate, does not need to use high-end microscopic instruments (such as an X-ray three-dimensional microscope (X-ray) and an ultrasonic scanning microscope), has less requirements on the instruments, and reduces the sample preparation cost.
Drawings
FIG. 1 is a sample diagram of a preparation process;
FIG. 2 is a diagram of a sample after primary grinding of cold plate inserts in examples 1 to 3;
FIG. 3 is a diagram showing the polishing process of the die-bonding micro-pad of examples 1 to 3 under an optical microscope;
FIG. 4 is a graph showing the positions of marks on a chip sample in example 3;
FIG. 5 is a diagram of a sample after complete grinding and polishing of a cold plate;
FIG. 6 is a morphology image in an electron microscope after bonding wire micro-welding spot cold-mounting polishing is completed in an embodiment;
FIG. 7 is an EBSD image of a bond wire micro solder joint after cold plate polishing is completed in an embodiment.
Detailed Description
The invention will be described in further detail with reference to specific embodiments, but the scope of the invention is not limited to the description.
Summary of the invention
A sample preparation method for representing a chip lead bonding micro-welding spot structure comprises the following specific steps:
(1) Fixing the chip sample in a mold in a clamping level, wherein the epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin or glycidyl amine type epoxy resin, and the viscosity is 10-10000 mPa.s; the curing agent is an amine curing agent, an anhydride curing agent or a latent curing agent; the epoxy resin accounts for 65 to 98.5 percent of the epoxy resin and the curing agent in the mixture, and the curing agent accounts for 1.5 to 35 percent; if the chip sample is the photoresist-removed chip sample, the micro-welding spots of the chip sample are clamped and fixed downwards in a bare surface; if the chip sample is a chip sample without photoresist removal, marking the position of a micro welding spot of the estimated chip sample at a position 1.9-2.1 mm away from the positive end of the chip sample, wherein the marking surface of the chip sample is downwards clamped and fixed, and the marking surface is the back surface of the exposed surface of the micro welding spot; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Adopt different mesh numbers sand paper to grind the appearance step by step to cold mosaic: under the observation of an optical microscope, the cold-mounting is firstly grinded to be 0.8-1.2 mm away from the negative end face of the chip sample, the negative end of the chip of the cold-mounting is roughly grinded, finely grinded and polished to the section position of the target micro-welding point, and a traceless adhesive tape is used for covering the negative end of the chip of the cold-mounting;
If the chip sample is a photoresist-removed chip sample, the specific method of step-by-step grinding of the cold-fitting (see fig. 1 (a)) is as follows:
1) Preliminary grinding the sample by using 240-mesh sand paper until the sample is 0.8-1.2 mm away from the negative end face of the chip sample (see fig. 1 (b));
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample by using 1200-mesh sand paper until the lead position is observed on the negative end face of the chip sample;
4) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
5) Fine grinding with 4000 mesh sand paper until the negative end surface of the chip sample has a complete target micro-welding spot section (see fig. 1 (c));
6) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
If the chip sample is a chip sample without photoresist removal, the specific method for grinding the chip sample step by step comprises the following steps:
1) Preliminary grinding the sample by 240-mesh sand paper until the distance from the end face of the negative electrode of the chip sample is 0.8-1.2 mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample to the end face of the negative electrode by using 1200-mesh sand paper, wherein the distance from the sample marking position of the chip is 0.8-1.2 mm;
4) Grinding the sample to the marked position of the negative end face of the chip sample by using 2000-mesh sand paper;
5) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
6) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample;
7) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
The polishing method comprises the following specific steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length is not more than 200 mu m;
2) Finely polishing the sample with polishing paste of 1.5 mu m for many times until the section of the micro welding spot of the sample has no scratches or the number of scratches is not more than 5, the depth of the scratches is not more than 2 mu m, and the length is not more than 50 mu m;
3) Removing polishing paste on the surface of the micro welding spots by adopting clean water micro polishing;
(3) Coarsely grinding the positive end of the cold-inlaid chip until the metal end is exposed to obtain a chip bonding micro-welding spot tissue sample (see fig. 1 (d)); the rough grinding can be carried out by adopting 240-mesh sand paper;
(4) And (5) observing and characterizing the chip bonding micro-welding spot tissue sample by adopting an electron microscope.
Example 1: the chip sample of the embodiment is a photoresist-removed chip sample, and a direct observation method is adopted;
A sample preparation method for representing a chip lead bonding micro-welding spot structure comprises the following specific steps:
(1) Clamping and horizontally fixing a chip sample in a die, wherein the chip sample is a photoresist-removed chip sample, and the exposed surface of a micro welding spot of the chip sample (the front surface of the chip sample) is clamped and fixed downwards; the epoxy resin is commercial low-viscosity epoxy resin and peroxide polybutadiene, the viscosity is 10-100 mPa.s, and the curing agent is triethylene tetramine; the low-viscosity resin accounts for 76.92 percent and the curing agent accounts for 23.08 percent in percentage by mass; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Step-by-step grinding of cold inserts (see fig. 2 (a)) was performed using different mesh sandpaper: under the observation of an optical microscope, the exposed surface of the micro-welding spot and the negative electrode end of the cold-inlaid chip sample are initially ground to be 1mm away from the end surface of the chip sample, so that a shape convenient for observation is obtained; taking water as cooling liquid, adopting sand paper with different mesh numbers to perform rough grinding, fine grinding and polishing on the negative end of the cold-inlaid chip to the section position of the target micro-welding spot, and adopting a traceless adhesive tape to cover the negative end of the cold-inlaid chip;
The chip sample is a photoresist-removed chip sample, and the specific method for gradually grinding the cold mounting sample comprises the following steps:
1) Taking water as cooling liquid, and adopting 240-mesh sand paper to perform preliminary sample grinding until the distance from the end face of the negative electrode of the chip sample is 1mm;
2) Taking water as cooling liquid, and grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Taking water as a cooling liquid, grinding the sample to a negative end surface of a chip sample by using 1200-mesh sand paper to observe the position of a lead, wherein the negative end surface of the chip sample is shown in fig. 3 (a), and the exposed surface of a micro welding spot (the front surface of the chip sample) is shown in fig. 3 (d);
4) Taking water as cooling liquid, grinding the sample to the negative end surface of the chip sample by using 2000-mesh sand paper, and observing the positions of the lead and the bonding pad; in the sample grinding process, the front side (the exposed surface of the micro welding spot) and the negative end of the sample are observed through an optical microscope, the position of the distance from the micro welding spot is determined, the sample is ground to the position near the target micro welding spot, namely, a bonding pad can be observed when the negative electrode of the sample is observed under a light microscope, and a point of lead wire is arranged above the bonding pad as shown in the figure 3 (b);
5) Taking water as cooling liquid, and adopting 4000-mesh sand paper to finely grind until a complete target micro-welding spot section appears on the end face of the negative electrode of the chip sample; in the sample grinding process, the other point above the negative electrode bonding pad of the sample can be observed through an optical microscope, and the areas of the two points are larger and larger until the two points are completely connected, as shown in fig. 3 (c), the front surface (the exposed surface of the micro-welding point) of the sample is shown in fig. 3 (e), and the complete negative electrode sample grinding process is completed;
the rotating speed of the sample grinding process is 200r/min, the sample grinding process is carried out while observing through an optical microscope, and the main observation surfaces are the front surface (the exposed surface of the micro welding spots) of the cold insert sample and the negative electrode end;
6) Polishing the cross section position of the target micro welding spot on the negative end face of the chip sample; the polishing method comprises the following specific steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length of the scratches is not more than 200 mu m so as to reduce the scratches on the chip and the micro welding spots;
2) In the same direction, polishing paste with the thickness of 1.5 mu m is adopted for multiple times until no scratches or no more than 5 scratches exist on the section of the micro welding spot of the sample, the depth of the scratches is no more than 2 mu m, and the length is no more than 50 mu m;
3) Removing polishing paste on the surface of the micro welding spots by adopting clean water micro polishing;
The rotating speed of the polishing process is 200r/min, and the single polishing time is not longer than 3min;
(3) Coarsely grinding the positive end of the cold-inlaid chip by using 240-mesh sand paper until the metal end is exposed (the positive end of the sample is exposed to metal luster) to obtain a chip bonding micro-welding spot tissue sample (see figure 5);
(4) Observing and characterizing a chip bonding micro-welding spot tissue sample by adopting an electron microscope;
The microstructure sample of the chip bonding micro-welding spot of the embodiment is observed and characterized by an electron microscope, and the clear cross-section morphology characteristics of the micro-welding spot can be obtained as shown in fig. 6 (a); then, carrying out local EBSD scanning on the section of the micro welding spot, and the result is shown in FIG. 7 (a); the method can analyze interface defects, grain orientations, grain boundary conditions, grain changes and the like, can be finally used for judging interface reaction mechanisms of bonding wires and analyzing interface conditions, and provides clear and complete micro-welding spot cold-inlaid samples and reliable sample preparation methods for failure researches of the bonding wires.
Example 2: the chip sample of the embodiment is a photoresist-removed chip sample, and a direct observation method is adopted;
A sample preparation method for representing a chip lead bonding micro-welding spot structure comprises the following specific steps:
(1) Clamping and horizontally fixing a chip sample in a mold, wherein the chip sample is a photoresist-removed chip sample, the exposed surface of a micro welding spot of the chip sample (the front surface of the chip sample) is clamped and fixed downwards, the epoxy resin is bisphenol A type epoxy resin, the viscosity is 1000-10000 mPa.s, and the curing agent is polyethylene polyamine; 94.74% of the low-viscosity resin and 5.26% of the curing agent in percentage by mass; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Step-by-step grinding of cold inserts (see fig. 2 (b)) was performed using different mesh sandpaper: under the observation of an optical microscope, the exposed surface of the micro-welding spot and the negative electrode end of the cold-inlaid chip sample are initially ground to be 1mm away from the end surface of the chip sample, so that a shape convenient for observation is obtained; taking water as cooling liquid, adopting sand paper with different mesh numbers to perform rough grinding, fine grinding and polishing on the negative end of the cold-inlaid chip to the section position of the target micro-welding spot, and adopting a traceless adhesive tape to cover the negative end of the cold-inlaid chip;
The chip sample is a photoresist-removed chip sample, and the specific method for gradually grinding the cold mounting sample comprises the following steps:
1) Taking water as cooling liquid, and adopting 240-mesh sand paper to perform preliminary sample grinding until the distance from the end face of the negative electrode of the chip sample is 1mm;
2) Taking water as cooling liquid, and grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Taking water as a cooling liquid, grinding the sample to a negative end surface of a chip sample by using 1200-mesh sand paper to observe the position of a lead, wherein the negative end surface of the chip sample is shown in fig. 3 (a), and the exposed surface of a micro welding spot (the front surface of the chip sample) is shown in fig. 3 (d);
4) Taking water as cooling liquid, grinding the sample to the negative end surface of the chip sample by using 2000-mesh sand paper, and observing the positions of the lead and the bonding pad; in the sample grinding process, the front side (the exposed surface of the micro welding spot) and the negative end of the sample are observed through an optical microscope, the position of the distance from the micro welding spot is determined, the sample is ground to the position near the target micro welding spot, namely, a bonding pad can be observed when the negative electrode of the sample is observed under a light microscope, and a point of lead wire is arranged above the bonding pad as shown in the figure 3 (b);
5) Taking water as cooling liquid, and adopting 4000-mesh sand paper to finely grind until a complete target micro-welding spot section appears on the end face of the negative electrode of the chip sample; in the sample grinding process, the other point above the negative electrode bonding pad of the sample can be observed through an optical microscope, and the areas of the two points are larger and larger until the two points are completely connected, as shown in fig. 3 (c), the front surface (the exposed surface of the micro-welding point) of the sample is shown in fig. 3 (e), and the complete negative electrode sample grinding process is completed;
the rotating speed of the sample grinding process is 200r/min, the sample grinding process is carried out while observing through an optical microscope, and the main observation surfaces are the front surface (the exposed surface of the micro welding spots) of the cold insert sample and the negative electrode end;
6) Polishing the cross section position of the target micro welding spot on the negative end face of the chip sample; the polishing method comprises the following specific steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length of the scratches is not more than 200 mu m so as to reduce the scratches on the chip and the micro welding spots;
2) In the same direction, polishing paste with the thickness of 1.5 mu m is adopted for multiple times until no scratches or no more than 5 scratches exist on the section of the micro welding spot of the sample, the depth of the scratches is no more than 2 mu m, and the length is no more than 50 mu m;
3) Removing polishing paste on the surface of the micro welding spots by adopting clean water micro polishing;
The rotating speed of the polishing process is 200r/min, and the single polishing time is not longer than 3min;
(3) Coarsely grinding the positive end of the cold-inlaid chip by using 240-mesh sand paper until the metal end is exposed (the positive end of the sample is exposed to metal luster), so as to obtain a chip bonding micro-welding spot tissue sample;
(4) Observing and characterizing a chip bonding micro-welding spot tissue sample by adopting an electron microscope;
The microstructure sample of the chip bonding micro-welding spot in the embodiment is observed and characterized by an electron microscope, and the clear cross-section morphology characteristic of the micro-welding spot can be obtained as shown in fig. 6 (b). Then, carrying out local EBSD scanning on the section of the micro welding spot, and the result is shown in fig. 7 (b); the method can analyze interface defects, grain orientations, grain boundary conditions, grain changes and the like, can be finally used for judging interface reaction mechanisms of bonding wires and analyzing interface conditions, and provides clear and complete micro-welding spot cold-inlaid samples and reliable sample preparation methods for failure researches of the bonding wires.
Example 3: the chip sample of the embodiment is a chip sample without photoresist removal, and a scale pre-estimation method is adopted;
A sample preparation method for representing a chip lead bonding micro-welding spot structure comprises the following specific steps:
(1) The chip sample is clamped and horizontally fixed in a die, the chip sample is a chip sample without photoresist removal, the micro-welding spot position of the chip sample is estimated by a scale method and marked (marked is positioned at a position, which is 2mm away from a positive electrode frame, of the chip sample, as shown in fig. 4), the marked surface of the chip sample is clamped and fixed downwards, the marked surface is the back surface of the exposed surface of the micro-welding spot, at the moment, the front surface (the micro-welding spot surface, but the micro-welding spot is covered by colloid and cannot be observed) of the chip sample is upwards, the epoxy resin is low-viscosity epoxy resin and peroxide polybutadiene, the viscosity is 10-100 mPa.s, and the curing agent is triethylene tetramine; the low-viscosity resin accounts for 76.92 percent and the curing agent accounts for 23.08 percent in percentage by mass; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Step-by-step grinding of cold inserts (see fig. 2 (c)) was performed using different mesh sandpaper: under the observation of an optical microscope, the marking surface and the negative electrode end of the cold-inlaid chip sample are initially ground to be 1mm away from the end surface of the chip sample, so that a shape convenient for observation is obtained; taking water as cooling liquid, adopting sand paper with different mesh numbers to perform rough grinding, fine grinding and polishing on the negative end of the cold-inlaid chip to the section position of the target micro-welding spot, and adopting a traceless adhesive tape to cover the negative end of the cold-inlaid chip;
the chip sample is a chip sample without photoresist removal, and the specific method for grinding the chip sample step by step comprises the following steps:
1) Preliminary grinding the sample by using 240-mesh sand paper until the distance from the sample negative end face of the chip is 1mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample by using 1200-mesh sand paper until the distance from the end face of the negative electrode to the marking position of the chip sample is 1mm;
4) Grinding the sample to the marked position of the negative end face of the chip sample by using 2000-mesh sand paper, observing the negative end of the sample under a light microscope to observe a lead, wherein the negative end face of the chip sample is shown as a figure 3 (a);
5) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad; viewing the sample negative under the mirror can observe the pad and a point above the pad and the unconnected leads as shown in fig. 3 (b);
6) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample; in the sample grinding process, the other point above the negative electrode bonding pad of the sample can be observed through an optical microscope, and the areas of the two points are larger and larger until the two points are completely connected, as shown in fig. 3 (c), so that the complete negative electrode sample grinding process is completed;
The rotating speed of the sample grinding process is 200r/min, the sample grinding process is carried out while the sample is observed through an optical microscope, and the main observation surface is the cold-inlaid negative end;
7) Polishing the cross section position of the target micro welding spot on the negative end face of the chip sample; the polishing method comprises the following specific steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length of the scratches is not more than 200 mu m so as to reduce the scratches on the chip and the micro welding spots;
2) In the same direction, polishing paste with the thickness of 1.5 mu m is adopted for multiple times until no scratches or no more than 5 scratches exist on the section of the micro welding spot of the sample, the depth of the scratches is no more than 2 mu m, and the length is no more than 50 mu m;
3) Removing polishing paste on the surface of the micro welding spots by adopting clean water micro polishing;
The rotating speed of the polishing process is 200r/min, and the single polishing time is not longer than 3min;
(3) Coarsely grinding the positive end of the cold-inlaid chip by using 240-mesh sand paper until the metal end is exposed (the positive end of the sample is exposed to metal luster) to obtain a chip bonding micro-welding spot tissue sample (see figure 5);
(4) Observing and characterizing a chip bonding micro-welding spot tissue sample by adopting an electron microscope;
the microstructure sample of the chip bonding micro-welding spot of the embodiment is observed and characterized by an electron microscope, and the clear cross-section morphology characteristics of the micro-welding spot can be obtained as shown in fig. 6 (c); then, carrying out local EBSD scanning on the section of the micro welding spot, and the result is shown in fig. 7 (c); the method can analyze interface defects, grain orientations, grain boundary conditions, grain changes and the like, can be finally used for judging interface reaction mechanisms of bonding wires and analyzing interface conditions, and provides clear and complete micro-welding spot cold-inlaid samples and reliable sample preparation methods for failure researches of the bonding wires.
The method can finish the whole polishing process by using an optical microscope in the sample polishing process, does not need to use a high-end microscopic instrument in the traditional sample polishing method, greatly reduces the sample preparation cost of the section of the bonding micro welding spot, has simple operation and shorter time, and solves the problems of the traditional technical method that the requirements of various instruments are met and the polishing time is longer.
While the specific embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes may be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
Claims (6)
1. A sample preparation method for representing a chip lead bonding micro-welding spot structure is characterized by comprising the following specific steps:
(1) Fixing a chip sample in a die in a clamping and horizontal manner, wherein the chip sample is a photoresist-removed chip sample, and the exposed surfaces of micro welding spots of the chip sample are clamped and fixed downwards; clamping and horizontally fixing a chip sample in a mold, wherein the chip sample is a chip sample without photoresist removal, a marking surface of the chip sample is downwards clamped and fixed, and the marking surface is the back surface of the exposed surface of the micro welding spot; adding the epoxy resin-curing agent mixture into a die to submerge a chip sample and a clamp, and standing for solidification to obtain a cold mounting;
(2) Adopt different mesh numbers sand paper to grind the appearance step by step to cold mosaic: under the observation of an optical microscope, the cold-mounting is firstly grinded to be 0.8-1.2 mm away from the negative end face of the chip sample, the negative end of the chip of the cold-mounting is roughly grinded, finely grinded and polished to the section position of the target micro-welding point, and a traceless adhesive tape is used for covering the negative end of the chip of the cold-mounting;
(3) Coarsely grinding the positive end of the cold-inlaid chip until the metal end is exposed to obtain a chip bonding micro-welding spot tissue sample;
(4) And (5) observing and characterizing the chip bonding micro-welding spot tissue sample by adopting an electron microscope.
2. The method of patterning a die wire bond micro pad structure of claim 1, wherein: the epoxy resin in the step (1) is bisphenol A type epoxy resin, bisphenol F type epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin or glycidyl amine type epoxy resin, and the viscosity is 10-10000 mPa.s; the curing agent is an amine curing agent, an anhydride curing agent or a latent curing agent; the epoxy resin accounts for 65 to 98.5 percent of the epoxy resin-curing agent mixture, and the curing agent accounts for 1.5 to 35 percent of the epoxy resin-curing agent mixture.
3. The method of patterning a die wire bond micro pad structure of claim 1, wherein: and (3) when the chip sample in the step (1) is a chip sample without photoresist removal, marking the position of the micro welding spot of the estimated chip sample at a position 1.9-2.1 mm away from the positive end of the chip sample.
4. The method of patterning a die wire bond micro pad structure of claim 1, wherein: the chip sample is a photoresist-removed chip sample, and the specific method for grinding the sample step by step in the step (2) comprises the following steps:
1) Preliminary grinding the sample by 240-mesh sand paper until the distance from the end face of the negative electrode of the chip sample is 0.8-1.2 mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample by using 1200-mesh sand paper until the lead position is observed on the negative end face of the chip sample;
4) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
5) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample;
6) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
5. A method of patterning a die wire bond micro solder joint structure according to claim 3, wherein: the chip sample is a chip sample without photoresist removal, and the specific method for grinding the sample step by step in the step (2) comprises the following steps:
1) Preliminary grinding the sample by 240-mesh sand paper until the distance from the end face of the negative electrode of the chip sample is 0.8-1.2 mm;
2) Grinding the sample to the negative end face of the chip sample by adopting 600-mesh sand paper;
3) Grinding the sample to the end face of the negative electrode by using 1200-mesh sand paper, wherein the distance from the sample marking position of the chip is 0.8-1.2 mm;
4) Grinding the sample to the marked position of the negative end face of the chip sample by using 2000-mesh sand paper;
5) Grinding the sample to the negative end face of the chip sample by using 2000-mesh sand paper to observe the positions of the lead and the bonding pad;
6) Finely grinding the chip sample by adopting 4000-mesh sand paper until a complete target micro-welding spot section appears on the negative end face of the chip sample;
7) And polishing the section position of the target micro-welding spot of the negative end face of the chip sample.
6. The method of patterning a die wire bond micro pad structure of claim 1, wherein: the polishing method in the step (2) comprises the following steps:
1) Performing primary polishing by using 2.5 mu m polishing paste until the number of scratches is not more than 30, the depth of the scratches is not more than 5 mu m, and the length is not more than 200 mu m;
2) Finely polishing the sample with polishing paste of 1.5 mu m for many times until the section of the micro welding spot of the sample has no scratches or the number of scratches is not more than 5, the depth of the scratches is not more than 2 mu m, and the length is not more than 50 mu m;
3) And (3) removing the polishing paste on the surface of the micro welding spot by adopting clean water micro polishing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311821444.7A CN118010460A (en) | 2023-12-27 | 2023-12-27 | Sample preparation method for representing chip lead bonding micro-welding spot structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311821444.7A CN118010460A (en) | 2023-12-27 | 2023-12-27 | Sample preparation method for representing chip lead bonding micro-welding spot structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118010460A true CN118010460A (en) | 2024-05-10 |
Family
ID=90955295
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311821444.7A Pending CN118010460A (en) | 2023-12-27 | 2023-12-27 | Sample preparation method for representing chip lead bonding micro-welding spot structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118010460A (en) |
-
2023
- 2023-12-27 CN CN202311821444.7A patent/CN118010460A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108318304B (en) | PCBA effective section preparation and damage detection method for aerospace | |
| JP2008529031A (en) | Sample preparation for microanalysis | |
| CN104465315B (en) | The chip separation method of 3D Stacked Die Packaging devices | |
| CN105699875B (en) | The detection method of multiple layer of copper interconnection wiring structure | |
| JP2001319994A (en) | Semiconductor package and its manufacturing method | |
| CN113182531A (en) | Composite defect for metal additive manufacturing nondestructive testing and preparation method thereof | |
| Inoue et al. | Protective layer for collective die to wafer hybrid bonding | |
| CN118010460A (en) | Sample preparation method for representing chip lead bonding micro-welding spot structure | |
| KR101161808B1 (en) | Method of Making Conductive Cold Mounting Specimen for SEM | |
| CN115808341B (en) | Grinding sample preparation method of semiconductor chip sample section | |
| CN114371184B (en) | Method for representing microstructure evolution of IGBT chip bonding region | |
| Kim et al. | Fluxless flip-chip solder joint fabrication using electroplated Sn-rich Sn-Au structures | |
| CN115683795A (en) | Preparation method of oriented silicon steel sample for EBSD detection | |
| CN114199917A (en) | Hot chamber radioactive sample inlaying method for improving conductivity and inlaying sample | |
| CN110455711B (en) | Polymer coating material interface bonding strength testing arrangement | |
| CN113447339A (en) | Preparation method of sample for analyzing copper crystal grains of PCB hole | |
| CN111393997B (en) | Intermetallic compound polishing solution and intermetallic compound contour line display method | |
| Arjmand et al. | Development of Cu-Cu joining technology by laser welding for terminal attach within power semiconductor package | |
| Panchenko et al. | Metallographic preparation of the SnAgCu solders for optical microscopy and EBSD investigations | |
| Wulff et al. | Measurement of gold ballbond intermetallic coverage | |
| WO2022083185A1 (en) | Die taking-out method | |
| CN116297586A (en) | EBSD sample of packaging substrate and preparation method thereof | |
| Budiana et al. | Study Of Decapsulation On IC With Temperature And Volume H2SO4 Variation | |
| CN113009185A (en) | Preparation method of micron-sized powder sample of transmission electron microscope | |
| Tobias | Joining methods in electronics packaging: Sintered silver and eutectic bonding |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |