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Solid-state hot-compression low-temperature bonding method using nickel micro needle cones

A low-temperature bonding and thermal compression technology, used in semiconductor/solid-state device manufacturing, electrical components, circuits, etc., can solve the problem of difficult removal of flux residues, improve interconnect density, simplify process flow, and improve product reliability. Effect

Inactive Publication Date: 2012-07-04
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The application of flux and the removal of residues take a certain amount of production time, and the smaller the gap between the chip and the chip, or between the chip and the substrate, the more difficult it is to completely remove the flux residue

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Under-bump metallurgy (UBM), copper pillar bumps, nickel barrier, and bump surfaces formed on bare die with I / O pads by standard photolithographic patterning, sputter deposition, and electrochemical deposition A typical copper pillar bump size is 60 μm in diameter and 40 μm in height. A typical nickel barrier layer thickness is about 1 μm. A typical tin layer thickness is 5 μm with a height difference of less than 0.5 μm. The nickel microneedle cone layer and the surface anti-oxidation gold layer were prepared by chemical deposition or electrochemical deposition on the pad area of ​​the flip-chip substrate. The overall thickness was about 5 μm, the surface needle cone height was about 1 μm, and the gold thickness was about 10 nm. This thickness of gold plating does not affect the needle cone topography. Fix the chip, which has been washed with acid to remove the oxide layer on the surface of the bump, and the substrate face-to-face and fix it on the flip-chip bon...

Embodiment 2

[0038] The front I / O pads of the bare chip with I / O pads on the front side and through-silicon vias (TSVs) to the device side on the back form the under-bump metal layer (UBM) and tin layer, typically tin The layer thickness is 2 - 5 μm, and the height difference is less than 0.5 μm. The chip is usually thinned to less than 100 μm, and the nickel microneedle cone layer and the surface anti-oxidation gold layer are prepared on the surface of the ground and exposed TSV filling metal. The overall thickness is about 5 μm, and the height of the surface needle cone is about 1 μm. The thickness is about 10 nm. After using plasma to remove the surface oxide layer and contamination particles, two or more silicon wafers with this structure are stacked and fixed in the bonding machine, and the temperature is raised to a bonding temperature of 180 ° C. At the same time, the bonding machine applies 7.5 The equivalent static pressure of MPa is maintained for 5 minutes to complete the in...

Embodiment 3

[0040] The nickel microneedle cone layer and the surface anti-oxidation gold layer are prepared on the metal block of the pad area of ​​the printed circuit board (PCB) for ball grid array (BGA) surface mounting, the overall thickness is about 5-10 μm, and the surface needle The cone height is about 1-2 μm, and the gold thickness is about 10 nm. The BGA package planted with tin alloy solder balls with a size of 300 - 800 μm is pickled to remove the oxide layer on the surface of the solder balls, and fixed and aligned with the PCB in the bonding machine, and the temperature is raised to a bonding temperature of 180°C , and at the same time, the equivalent static pressure of 10 MPa is applied by the bonding machine, and it is kept for 5 minutes to complete the preliminary stacking bonding. After the preliminary bonding is completed, the chip is placed in a 140°C protective atmosphere for heat treatment for 6h.

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PUM

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Abstract

The invention provides a solid-state hot-compression low-temperature bonding method using nickel micro needle cones. A layer of metallic nickel featured by being bestrewed with needle cones is manufactured on one side of a to-be-bonded welding spot, and welding flux is used on the other side of the to-be-bonded welding spot. A colligator is used for being aligned with the electrically interconnected welding spot, the welding spot is heated to a certain temperature not higher than the solder cap melting point, and a bonding pressing force is exerted and maintained for some time so that inlay bonding of needle cones and welding flux at the position of the interconnection point is achieved. A thin layer of precious metal is electroplated on the layer of nickel micro needle cones to prevent the surface from being oxidized prior to bonding. After bonding is finished, the welding spot is placed at a certain temperature for heat treatment for some time to achieve diffusion reaction and remove holes. The solid-state hot-compression low-temperature bonding method using nickel micro needle cones is capable of overcoming some defects in the prior art in novel encapsulation technology application, avoids thermal damage caused to components by reflow soldering process temperature, and resolves the problems of welding flux spreading in molten welding and solid-liquid phase fast reaction.

Description

technical field [0001] The invention relates to the field of semiconductor chip packaging, in particular to a method for realizing solid-state interconnection and bonding between components through the use of a metal layer with a special needle cone shape on the surface. [0002] Background technique [0003] The micro-interconnection technology of semiconductor chip packaging is constantly innovating. Now the interconnection technologies in chip manufacturing mainly include: lead frame type; wire bonding; ball array; QFN; chip flip chip; bump bonding; load; 3D Packaging and other technologies. The innovation of electrical interconnection technology is the key to the development of microelectronics technology. The traditional fusion bonding technology is to control the temperature to make the metal at the bonding point melt and wet the two sides of the bonding point. After cooling, the bonding point solidifies, so as to obtain good welding. , such as reflow soldering. [...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L21/60
Inventor 李明胡安民陈卓
Owner SHANGHAI JIAO TONG UNIV
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