CN210224055U

CN210224055U - Interface metal structure for flip chip

Info

Publication number: CN210224055U
Application number: CN201921372998.2U
Authority: CN
Inventors: Fan Zhang; 张帆; Yongsheng Wu; 吴永胜
Original assignee: Fujian Trillion Photoelectric Co Ltd
Current assignee: Fujian Trillion Photoelectric Co Ltd
Priority date: 2019-08-22
Filing date: 2019-08-22
Publication date: 2020-03-31
Anticipated expiration: 2029-08-22

Abstract

The utility model relates to an interface metal structure for a flip chip, which comprises a thin gold layer, a bonding force lifting layer, a metal buffer layer and a filling metal layer in sequence; the thickness of the thin gold layer is 1-5000

(ii) a The binding force promoting layer is a Ni layer with a thickness of 1-5000

For strengthening the bonding force with the solder paste. The utility model discloses can effectively improve the bonding force that chip and base plate pass through the tin cream.

Description

Interface metal structure for flip chip

Technical Field

The utility model relates to a chip design monitoring field, especially an interface metal structure for flip chip.

Background

Flip chips are a new chip type that is very popular in the LED industry at present, and have a very broad application prospect and a huge development space. The main difference of the flip chip compared with the conventional flip chip is that the flip chip is combined with the substrate by soldering and the circuit conduction is realized. The bonding method is to butt-bond the electrodes of the flip chip to the substrate of the substrate (solder paste is often used as the bonding agent for bonding).

At present, the electrode of the flip chip takes aluminum and gold as main materials, and the materials are easy to form brittle compounds between metals after being combined with solder paste and a substrate, and are easy to break, so that the bonding force between the electrode and the substrate is insufficient. When the bonding force between the chip electrode and the substrate is insufficient, the chip can fall off or the heat dissipation and the electric conduction are poor. When the chip is used for a flexible substrate, the chip has higher requirements on the bonding force between the chip and the substrate, and the current common chip electrode cannot meet the welding bonding force requirement of the flexible substrate.

Disclosure of Invention

In view of this, the present invention provides an interface metal structure for a flip chip, which can improve the bonding force between the chip and the substrate through solder paste.

The utility model discloses a following scheme realizes: an interface metal structure for a flip chip sequentially comprises a thin gold layer, a bonding force promoting layer, a metal buffer layer and a filling metal layer; the thickness of the thin gold layer is

The binding force promoting layer is a Ni layer with the thickness of

So as to enhance the bonding force with the solder paste.

Furthermore, the metal buffer layer is of one or more layers of structures, and a Ti layer, a Cr layer or a Ti layer and a Cr layer are adopted.

Furthermore, the filling metal layer adopts a double-layer Al metal structure and comprises two Al layers, and Ti or Cr metal is adopted as an adhesive between the two Al layers.

Furthermore, the filling metal layer adopts a three-layer Al metal structure, the three-layer Al metal structure comprises three Al layers, and Ti or Cr metal is adopted as an adhesive between every two Al layers.

Furthermore, each layer of the interface metal structure for the flip chip is grown in an electron beam evaporation or magnetron sputtering mode.

The utility model discloses reduce the thickness of interface metal level gold, reduce the formation of gold tin brittle compound, add the Ni metal and be used for combining with the tin cream and generate high cohesion alloy-layer, make the buffer layer metal of using earlier in the lower floor of Ni and use the Al metal again as filling realization electric conduction and heat conduction, use bilayer or three-layer Al metal structure to fill sufficient metal thickness, use Ti or Cr metal as the binder between multilayer Al metal. A buffer layer must be used between the Ni and Al metals. The growth of the metal interface layer is mainly carried out by using electron beam evaporation and magnetron sputtering.

Compared with the prior art, the utility model discloses following beneficial effect has: adopt the utility model discloses a structure, flip chip can promote 50% with the cohesion that the base plate passes through the tin cream and combines. The chip and the substrate combined by the method can keep a stable set under the action of external force, torsion, cold and hot stress and the like, and the chip and the substrate can meet the requirements of electric conduction, heat conduction, stability and the like.

Drawings

Fig. 1 is a schematic view of an interface metal structure 1 according to an embodiment of the present invention.

Fig. 2 is a schematic view 2 of an interface metal structure according to an embodiment of the present invention.

Fig. 3 is a schematic structural view illustrating the flip chip and the substrate according to an embodiment of the present invention.

Detailed Description

The present invention will be further explained with reference to the drawings and the embodiments.

As shown in FIG. 1, the present embodiment provides an interface for a flip chipThe metal structure sequentially comprises a thin gold layer, a bonding force improving layer, a metal buffer layer and a filling metal layer; the thickness of the thin gold layer is

The binding force promoting layer is a Ni layer with the thickness of

So as to enhance the bonding force with the solder paste.

In this embodiment, the metal buffer layer has one or more layers, and a Ti layer, a Cr layer, or a Ti layer and a Cr layer is used.

In this embodiment, the filling metal layer has a double-layer Al metal structure, which includes two Al layers, and Ti or Cr metal is used as a binder between the two Al layers.

In this embodiment, the metal filling layer may also be a three-layer Al metal structure including three Al layers, and Ti or Cr metal is used as a binder between each two Al layers.

In this embodiment, each layer of the interface metal structure for the flip chip is grown by electron beam evaporation or magnetron sputtering.

Step S1: growing on the surface of a P-type layer of the GaN-based LED chip by adopting electron beam evaporation equipment;

step S2: growing a filling metal layer;

step S3: growing a metal buffer layer;

step S4: use of

A bonding force promoting layer Ni layer is grown at the rate of (2);

step S5: use of

A thin gold layer is grown.

In this embodiment, the filling metal layer has a double-layer Al metal structure, which includes two Al layers, and Ti or Cr metal is used as a binder between the two Al layers. Or the filling metal layer adopts a three-layer Al metal structure and comprises three Al layers, and Ti or Cr metal is adopted as an adhesive between every two Al layers.

In this embodiment, when the metal buffer layer has a one-layer structure, the step S3 is specifically to use

A Ti layer or a Cr layer is grown. When the metal buffer layer has a multilayer structure, step S3 is to perform multilayer alternate growth by using a metal including Ti or Cr to form superlattice metal layers with different growth rates and different densities.

Specifically, the present embodiment gives two examples. In fig. 1, the metal buffer layer includes one layer, and the filling metal layer has a three-layer Al layer structure. The alloy comprises a Cr layer, an Al layer 1, a Ti layer 1, an Al layer 2, a Ti layer 2, an Al layer 3, a Ti layer 3, a Ni layer and an Au layer from bottom to top in sequence. In fig. 2, the metal buffer layer includes two layers, and the filling metal layer adopts a two-layer Al structure. The composite material sequentially comprises an Al layer 1, a Ti layer 1, an Al layer 2, a Ti layer 2, a Cr layer, a Ni layer and an Au layer from bottom to top.

For ease of understanding, the present embodiment provides a structure diagram of a flip chip and a substrate assembly, which is specifically shown in fig. 3.

In the embodiment, the thickness of gold in the interface metal layer is reduced, the generation of gold-tin brittle compounds is reduced, Ni metal is added for being combined with tin paste to generate a high-bonding-force alloy layer, buffer layer metal is firstly used and then Al metal is used as filling in the lower layer of Ni to realize electric conduction and heat conduction, a double-layer or multi-layer Al metal structure is used for filling enough metal thickness, and Ti or Cr metal is used as an adhesive among the multi-layer Al metal. A buffer layer is required to be used between Ni and Al metal, and the buffer layer is alternately grown by using multiple layers of Ti, Cr and other metals to form superlattice metal layers with different growth rates and different densities. The growth of the metal interface layer is mainly carried out by using electron beam evaporation and magnetron sputtering.

It is worth mentioning that the utility model protects a hardware structure, and does not require protection as to the preparation method. The above is only a preferred embodiment of the present invention. However, the present invention is not limited to the above embodiments, and any equivalent changes and modifications made according to the present invention do not exceed the scope of the present invention, and all belong to the protection scope of the present invention.

Claims

1. An interface metal structure for a flip chip is characterized by sequentially comprising a thin gold layer, a bonding force promoting layer, a metal buffer layer and a filling metal layer; the thickness of the thin gold layer is

The binding force promoting layer is a Ni layer with the thickness of

So as to enhance the bonding force with the solder paste.

2. The interfacial metal structure for flip-chip as claimed in claim 1, wherein said metal buffer layer is one or more layers of Ti, Cr or both Ti and Cr.

3. The interfacial metal structure for flip-chip as claimed in claim 1, wherein said filling metal layer is a dual Al metal structure comprising two Al layers with Ti or Cr metal as a binder.

4. The interfacial metal structure for flip-chip as claimed in claim 1, wherein said metal filling layer is a three-layer Al metal structure comprising three Al layers, each two of which uses Ti or Cr metal as a binder.

5. The interface metal structure of claim 1, wherein each layer of the interface metal structure for a flip chip is grown by electron beam evaporation or magnetron sputtering.