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Preparation method of lead bonding interface transmission electron microscope sample and method for observing evolution process of intermetallic compound

An electron microscope and wire bonding technology, which is applied in the preparation, sampling, and measuring devices of test samples, can solve problems such as increased research errors, poor repeatability of experimental conclusions, and deviations

Pending Publication Date: 2022-02-18
EAST CHINA NORMAL UNIVERSITY
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  • Description
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  • Application Information

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Problems solved by technology

However, the above research methods all use ex-situ research, that is, a batch of samples are treated with different annealing temperatures and annealing times, and then the annealing reaction is completed before sample preparation and microscopic characterization
This ex-situ research method, which separates the reaction process from the observation, will inevitably result in the loss and deviation of some data on the structural evolution during the annealing process.
At the same time, since the samples observed in the later stage are only samples of the same batch rather than the same sample, the error of the research will be further increased due to process deviation, pollution and the non-uniform growth of intermetallic compounds at the bonding interface, and the experimental conclusions can be repeated. poor sex
[0004] "In-situ Experimental Study on the Growth Process of Intermetallic Compounds at Cu / Al Wire Bonding Interface" (Yang Qingling, Chen Yiyi, etc., Acta Physica Sinica, 2015, 216804-1~216804-6) discloses the use of high-resolution transmission electron microscopy in situ Observing the growth process of intermetallic compounds at the Cu / Al wire bonding interface, after using pure Cu wires to ultrasonically bond to Al metal discs, using traditional grinding, polishing and thinning, to obtain samples before annealing, the accuracy of the observation results is poor

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  • Preparation method of lead bonding interface transmission electron microscope sample and method for observing evolution process of intermetallic compound
  • Preparation method of lead bonding interface transmission electron microscope sample and method for observing evolution process of intermetallic compound
  • Preparation method of lead bonding interface transmission electron microscope sample and method for observing evolution process of intermetallic compound

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preparation example Construction

[0028] The invention provides a method for preparing a wire bonding interface transmission electron microscope sample, comprising the following steps:

[0029] (1) Select a bonding wire from the chip wiring structure contained in the chip package, and deposit a metal protective layer on the surface of the bonding ball at one end of the bonding wire and the surface of the pad in contact with the bonding ball to obtain protected bonding balls and pads, the chip package containing a wire bonding structure;

[0030] (2) cutting the protected bonding ball and pad by ion beam to obtain bonding ball-pad sample;

[0031] (3) Cutting the bonding ball-pad sample longitudinally with an ion beam to obtain a bonding ball-pad sample with an exposed wire bonding interface;

[0032] (4) Depositing a metal protective layer on the wire bonding interface region of the bonding ball-pad sample of the exposed wire bonding interface to obtain a protected wire bonding interface;

[0033] (5) Cuttin...

Embodiment 1

[0074] (1) Select a chip package including a copper-aluminum wire bonding structure, unpack the chip, and remove the package shell.

[0075] (2) Put the chip obtained in step (1) without the package shell into the instrument of the double-beam focused ion beam-scanning electron microscope, observe the internal wiring structure of the chip from the window of the scanning electron microscope, and select a copper bond arbitrarily fit line.

[0076] (3) In step (2), select the bonding ball structure at one end of the copper bonding wire and deposit a layer of Pt protection on the surface of the surrounding pads, with a thickness of 1 μm, and use focused ion beams to dig trenches on both sides of the Pt protection layer Obtain a rough cut bond ball-pad sample from one end of the selected bond wire.

[0077] (4) The bonding ball-pad sample prepared in step (3) was longitudinally sliced ​​to the center position, and the bonding ball sample was divided into two to obtain a bonding ba...

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Abstract

The invention relates to the technical field of lead bonding interface intermetallic compounds, and in particular relates to a preparation method of a lead bonding interface transmission electron microscope sample and a method for observing the evolution process of an intermetallic compound. The preparation method provided by the invention comprises the following steps: firstly, depositing a metal protection layer on the surface of a bonding ball and the surface of a bonding pad in contact with the bonding ball to prevent damage to the bonding ball and the bonding pad during ion beam cutting, and after a bonding ball-bonding pad sample is obtained, carrying out longitudinal ion beam cutting on the bonding ball-bonding pad sample to obtain an exposed lead bonding interface; and carrying out ion beam cutting on the metal protection layer deposited in the lead bonding interface area of the bonding ball-bonding pad sample with the exposed lead bonding interface, thereby effectively preventing damage to the lead bonding interface during ion beam cutting. According to the preparation method provided by the invention, the lead bonding interface in the chip packaging body is selected for sample preparation, and the prepared lead bonding interface transmission electron microscope sample is higher in precision.

Description

technical field [0001] The invention relates to the technical field of wire bonding interface intermetallic compounds, in particular to a method for preparing a wire bonding interface transmission electron microscope sample and a method for observing the evolution process of intermetallic compounds. Background technique [0002] Wire bonding originated in the early 1960s and is widely used in the electrical interconnection between chips and substrates and the information interaction between chips. Epoxy resin molding is required after wire bonding. This post-molding package usually requires annealing at a higher temperature. During the bonding and annealing process of the wire bonding interface, intermetallic compounds will be formed due to the diffusion of metal atoms. The excessive growth of intermetallic compounds at the wire bonding interface and the formation of voids will increase the contact resistance and reduce the bonding strength, thereby affecting the performance...

Claims

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Application Information

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IPC IPC(8): G01N1/28G01N23/20058
CPCG01N1/28G01N1/2806G01N1/286G01N23/20058G01N2001/2873G01N2223/418G01N2223/611
Inventor 吴幸王亚男张子健叶长青骆晨王超伦
Owner EAST CHINA NORMAL UNIVERSITY
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