JPH0282623A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain a CCB structure of a BLM electrode having no peeling from a surface protective film by so selecting that the minus free energy of the material of a BLM electrode lowermost layer becomes larger than that of the material for forming the protective film, i.e., the material of the lowermost layer can reduce the material of the protective film. CONSTITUTION:A BLM electrode 8 is formed of four layers, which are sequentially from the bottom a titanium silicide (TiSi2) layer 9, a titanium nitride (TiN) layer 10, a Cu layer 11 and an Au layer 12. Since Ti in the layer 9 has larger minus reference generation free energy than that of an SiO2 for forming a surface protective film 6, the layer 9 reduces the SiO2. Constituent substances are diffused to each other in a boundary between the layer 9 and the film 6 by scientific reaction to rigidly bond the layer 9 to the film 6 through a reaction layer formed at this time. A solver ball 13 is formed on the layer 12 thereby to form a CCB structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit device, and particularly to a technique that is effective when applied to a semiconductor integrated circuit device having metal protruding electrodes.

[Prior art]

CC is one of the methods for mounting semiconductor pellets on a mounting board.
B (Control Co11apsed Bo
There is a W structure. In this method, a metal protrusion electrode such as a solder ball is formed on a base electrode layer formed on the pellet surface, and the pellet is electrically connected to a wiring board using the protrusion electrode. Below the base electrode layer C, simply BL
M (Ball L i m i t e d M e
(also referred to as an electrode) is formed on the surface insulating film of the pellet so as to be connected to the underlying wiring layer through a through hole formed in the surface insulating film of the pellet. Gold (A u) from the top, I!
It is composed of three layers: 4'(C, u) and chromium (Cr). The above Au layer works to prevent oxidation of the electrode surface, but the lead (Pb) contained in the solder that forms the solder ball is
b) is sucked in and diffused. The Cu layer forms an intermetallic compound with tin (Sn) contained in the solder, and acts to form a metallic bond. The Cr layer acts as an adhesion layer between the solder in the upper layer of the BLM electrode, the reaction prevention layer of the metal in the lower layer, and the underlying surface protective film.

Incidentally, an example of a document describing BI and M electrodes is described in Japanese Patent Laid-Open No. 61-1.66049.

[Problem to be solved by the invention]

The BT and Mffi electrodes are partially formed on the surface protective film of the semiconductor pellet, but conventionally, the material of the bottom layer of the BLM electrode that contacts the surface protective film, that is, Cr, and the surface protective film, silicon oxide (S), are formed. i O2) is not so strong, and the above Br=[! There was a problem in that the BLMfM and the electrode were likely to peel off from the surface protective film due to the thermal deformation force of the solder balls formed on the electrode. In addition, as the wiring layer becomes finer and the number of electrodes increases, the diameter of the through-holes formed in the protective film becomes finer, and the pitch between the electrodes also becomes smaller, making it necessary to process the CCB through-holes by a dry etching process. There is. Through-holes processed by a dry etching process have sidewalls that are almost perpendicular to the underlying wiring layer, so B.
The inventor of the present invention has discovered that there is a problem in that the BLMffi electrode peels off from the wiring layer due to defective step coverage when forming the LM electrode.

The object of the present invention is to provide BT, M without peeling from the surface protective film.
An object of the present invention is to provide a semiconductor integrated circuit device having a CCBI structure using electrodes.

Still another object is to provide a semiconductor integrated circuit device having an OCR structure using BLMffi electrodes that does not cause poor contact with lower wiring layers even through minute through holes.

The above and other objects and novel features of the present invention will become apparent from the description of this document xB and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, the combination of the material of the bottom layer of the BLM electrode that contacts the surface protective film and the surface protective film material (oxide) is determined by the standard free energy of formation/temperature diagram (Niringham diagram).
using the BT, so that the negative free energy of the material of the bottom layer of the BLM electrode is greater than the negative free energy of the material forming the surface protective film.
The material of the lowest layer of Mffi is selected so that it can reduce the surface protective film material.

Yet another method is to embed metal into the through holes formed in the surface protection film almost in the same space as the surface protection film, before forming the BLMffi electrode.

[For production]

According to the above means, the material forming the conductive layer in contact with the surface protective film among the BT and M electrode layers has a larger negative standard free energy of formation than the material forming the surface protective film, and Since the film can be reduced, diffusion occurs at the interface between the two and they work to bond with each other with strong adhesive force, achieving a CCB structure using the BLM electrode without peeling from the surface protective film.

According to yet another method, the metal that is almost completely embedded in the through holes formed in the surface protection film acts to electrically connect the BLM electrode and the lower wiring layer, and Even if the hole is processed by dry etching process, there is no contact failure with the lower wiring layer.
This achieves a CB structure.

[Example 1] Figure 1 shows an example of the present invention, in which a C with BI and M electrodes is used.
FIG. 3 is a longitudinal cross-sectional view of the CB structure.

In this figure, although not particularly limited, BLMffi pole 8
Two wiring layers are formed below.

An insulating film 2 is deposited on a semiconductor substrate 1 , a first wiring layer 3 is formed on top of the insulating film 2 , and a second wiring layer 5 is further formed on top of that through an interlayer insulating film 4 . It is formed. A surface protective film 6 as an insulating layer made of SiO2 is deposited on the second wiring layer 5, and through holes 7 are formed in required portions of the protective film 6 on the wiring layer 5. BL so as to connect to wiring M5 via through hole 7.
A Mffl pole 8 is formed. The RLM electrode 8 is 4
It consists of two layers, from the bottom: titanium silicide (Tisiz).
) layer 9. Titanium nitride (TiN) Wllo,
Cu layer 11. The Au layer 12 is formed. The above TiSi2
[9 is an example of a metal capable of reducing 5in2 forming the surface protection film 6. In this case, the possibility that certain metal compounds or metals reduce certain oxides is suggested, for example, by the Nillingham diagram. According to this.

TiSi, Ti in the layer 9 is S which forms the surface protective film 6
Since the negative standard free energy of formation is larger than that of i O, the T i S i7 layer 9 is S i O.

Due to this chemical reaction, the respective constituent substances diffuse into each other at the interface between the TiSi2 layer 9 and the surface protective film 6 made of 5in2, and the Ti5127M9 and the The surface protection film 6 is strongly bonded.

Solder balls 13 are formed on the A u FJ 1.2, thereby forming a CCB structure. In addition, the above A
Since the U layer 12 diffuses into the solder PB during the formation of the solder balls 13, it is represented by imaginary lines in this figure. Further, the TiN layer 10 is a barrier metal that prevents the solder balls 13 formed on the upper layer of the eight and M electrodes 8 and the aluminum forming the wiring layer formed on the lower layer from reacting with each other and causing diffusion. Work as.

Next, the manufacturing process of the CCB structure shown in FIG. 1 is shown in FIG. 3 (
The explanation will be based on a) to (e).

As shown in FIG. 3(a), an insulating film 2 made of Sin is formed on a semiconductor substrate 1 through a predetermined process, and a first aluminum wiring layer 3 is formed on top of the insulating film 2. .

On the wiring layer 3 is SiO, /SOG/S i
02(1) A second aluminum interconnection layer 5 is formed via a laminated interlayer insulating film 4, and on top of this a second aluminum interconnection layer 5 is formed.
, a surface protection film 6 is formed. A through hole 7 is formed in a predetermined position of the surface protective film 6 formed on the second layer aluminum wiring layer 5.
is drilled.

Next, as shown in FIG. 3(b), on the surface protection film 6,
The second layer aluminum 1 is inserted through the through hole 7.
A T i S i layer 9 is deposited so as to be connected to the first wiring layer 5 . Since the TiSi2 layer 9 has the function of reducing SiO2 forming the surface protection film 6, diffusion occurs at the interface between the two and they are bonded to each other with strong adhesive force. Next, on the TiSi2 layer 9, the solder ball 13 formed on the upper layer of the BT and M1 layer 8 acts as a barrier metal to prevent diffusion of the aluminum constituting the wiring layer formed below. Layer 10 is deposited. Further, a Cu layer 11 and an Au layer 12 are deposited on the TiN layer 10, and then etched to form a desired size and shape to form a BLM electrode.

Next, as shown in FIG. 3(c), the surface protective film 6 and B
For example, a photosensitive polyimide layer 15 is applied over the entire surface of the LM electrode 8, and after exposing only a predetermined position on the BLM electrode 8, development is performed to form an opening 16.

Furthermore, as shown in FIG. 3(d), the Sn layer 16 and the PbM
17 is deposited over the entire surface with a thickness ratio of, for example, 5:95, the photosensitive polyimide layer 15 serves as a mask and the solder ball material is deposited on the BLM electrode 8 exposed in the opening 16. The above S n Ml 6 and pb
Layer 17 is formed.

Next, by dissolving the photosensitive polyimide layer 15 with a chemical, unnecessary S on the photosensitive polyimide 15 is removed.
The n layer 16 and the pb layer 17 are removed, leaving only the SnM and pb layer, which will become the solder ball material on the BLM electrode 8. Finally, heat is applied to the S on the BLMffi pole 8.
The n layer 16 and the Pb layer 17 are melted to form solder balls 13.
form.

At this time, the Au layer 12 is absorbed by the PB contained in the solder and diffused.

According to the above embodiment, the following effects are obtained.

(1) Since Ti5iJ59, which exists in the bottom layer of the BLM electrode 8 and is in contact with the surface protective film 6, has a larger negative standard free energy of formation than the Sin forming the surface protective film 6, it reduces the above 5in2 and both Since diffusion occurs at the interface of the BLM electrodes 8 and they are bonded to each other with strong adhesive force, the Sin of the BLM electrode 8 concerned.

The occurrence of peeling from the surface protective film 6 can be suppressed.

[Embodiment 2] FIG. 2 shows a longitudinal cross-sectional view of a CCB structure with BLMffi poles showing another embodiment of the present invention. The difference is that a tungsten electrode 20 is embedded in the through hole 7.

The tungsten electrode 20 is formed by forming a through hole 7 in a required portion of the surface protective film 6, and then depositing it in the through hole so as to be substantially flush with the surface protective film 6 by selective CVD.

Note that the manufacturing process is the same as in the above embodiment except that the tungsten electrode 20 is added.

According to the above embodiment, the following effects are obtained.

(1) The tungsten electrode 2o is deposited in the through hole 7 almost flush with the surface protection film 6, and the second wiring layer and the Ti layer 9 are electrically connected by the tungsten electrode 20. It is possible to prevent poor contact between the second wiring layer and the TiSi layer 9 due to poor step coverage of the TiSi layer 9 formed on the upper layer of the surface protection film 6 into the through hole 7. .

Although the invention made by the present inventor has been specifically described above based on examples, it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from the gist thereof.

For example, in this example, the material of the surface protective film and the material of the bottom layer of the BLM electrode in contact with the surface protective film are SiO2 and TiS.
i2, but the combination is not necessarily limited to this, and the material of the lowermost electrode layer may be titanium, an alloy of titanium and tungsten, aluminum, or an insulating compound such as an oxide that forms the above-mentioned surface protective film. A material having a larger negative standard free energy of formation can be appropriately selected.

Further, in the above embodiment, a TiN layer was used as the barrier metal, but TiSi was used as the bottom layer of the BLM electrode.

When using the TiN layer, the TiN layer may be omitted, and in this case, TiSi2 functions as a barrier metal.

Moreover, although the material of the layer of the BLM electrode layer that is metallically bonded to the solder is Cu, it is not necessarily limited to this, and nickel or the like may also be used. Furthermore, in Example 2, the material of the electrode embedded in the through-hole portion was tungsten.

Any material that can be selectively deposited on metal or the like can be used as appropriate.

In the above explanation, the invention made by the present inventor was mainly applied to monolithic semiconductor integrated circuits, which is the background field of application, but the present invention is not limited to this, and It can be widely used in semiconductor integrated circuits, etc. The present invention can be applied to conditions having at least a CCB structure.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical ones are as follows.

In other words, the material of at least the part of the BLMffi electrode that contacts the surface protective film has a larger negative standard free energy of formation than the material forming the surface protective film, so it reduces the surface protective film and diffuses at the interface between the two. occurs and are bonded to each other with strong adhesive force, which has the effect of suppressing the occurrence of peeling of the B1 and M electrodes from the surface protective film.

Furthermore, an electrode is formed by depositing metal in the through hole provided in the surface protective film almost entirely with the protective film, and the lower wiring layer is electrically connected to the I' (LM group electrode) by the electrode. Therefore, it is possible to prevent contact failure between the lower wiring layer and the BLM electrode due to defective step coverage within the through hole.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a CCB structure as an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing a CCB structure as another embodiment of the present invention, and FIGS. 3(a) to (e) ) are vertical cross-sectional views sequentially showing an example of the manufacturing process of the above CCB structure. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Insulating film, 3... First wiring layer, 4... Interlayer insulating film, 5... Second wiring layer, 6... Si 02 surface protective film, 7... through hole, 8... BLM electrode, 9... TiSi 2 layer,
10...TiN layer, 11...Cu layer, 12...A
U layer, 13...Solder ball, 15...Photosensitive polyimide layer, 16...Sn layer, 17...PB layer, 20.
・Tungsten electrode. 2 = \-117-111'

Claims (1)

[Scope of Claims] 1. A base electrode layer for forming metal protruding electrodes connected to the wiring layer through through-holes formed in required portions of the surface protection film provided on the wiring layer is provided on the surface protection film. 1. A semiconductor integrated circuit device, wherein at least a portion of the base electrode layer that contacts the surface protection film is a conductive layer that can reduce the surface protection film. 2. The semiconductor according to claim 1, wherein the material forming the conductive layer in contact with the surface protective film has a larger negative standard free energy of formation than the oxide forming the surface protective film. Integrated circuit device. 3. Metal is selectively deposited in the through hole,
2. The semiconductor integrated circuit device according to claim 1, wherein the wiring layer and the base electrode layer are electrically connected by the deposited metal.