JP2541391Y2 - Semiconductor device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device provided with electrodes suitable for connecting copper-based lead wires.

[0002]

2. Description of the Related Art The conventional semiconductor device shown in FIG. 2 has an insulating film 2 made of a silicon oxide film or the like on the surface of a semiconductor substrate 1. An electrode 4 made of Al (aluminum) is in contact with the semiconductor substrate 1 through the opening 3 of the insulating film 2.

In recent years, practical use of lead wires made of Cu (copper) has been advanced. Cu lead wire is Au
(Gold) Ball bonding (nail head bonding) can be performed without being restricted by the directionality of wire bonding as in the case of fine lead wires, and there is an advantage that it is less expensive than Au. However, as is well known, the ball portion of the Cu lead thin wire is formed to be harder than the Au lead thin wire, so that when this is ball-bonded to the Al electrode 4, the Al electrode 4 is easily crushed and thinned. FIG. 2 shows a state in which the Al electrode 4 at the position indicated by the dotted line is thinned to the position indicated by the solid line by bonding the Cu lead fine wire 5. Therefore, the semiconductor region 1 is connected via the Al electrode 4 in which the Cu component of the Cu lead thin wire 5 is thinned.
And the ohmic contact (low-resistance contact) of the Al electrode 4 to the semiconductor region 1 becomes worse. As a means for solving this problem, it is conceivable to form the Al electrode 4 to have a large thickness. However, if the Al electrode 4 is made thicker, the accuracy of etching is reduced. Therefore, the Al electrode 4 is so thick that diffusion of Cu can be prevented. It is difficult to do.

Accordingly, an object of the present invention is to provide a semiconductor device having an electrode structure capable of preventing diffusion of Cu or the like.

[0005]

In order to achieve the above object, the present invention provides a semiconductor substrate and a semiconductor substrate formed on the semiconductor substrate.
An insulating film having an opening and an opening in front of the semiconductor substrate .
Formed on the surface exposed by the opening and
A first metal layer made of a material mainly composed of aluminum is formed so as not to extend (Al) or aluminum (Al) is formed on the Enmaku, and formed on said first metal layer The opening so that a gap is formed between the opening and the opening.
Titanium, which is smaller than (Ti) or titanium (T
a second metal layer made materials or molybdenum (Mo) or molybdenum (Mo) of a material whose main component is the i) as a main component, is formed to cover the surface and a side surface of the second metal layer And formed so as to extend on the insulating film.
A third metal layer made of aluminum (Al) or a material containing aluminum (Al) as a main component ;
A ball bonding part, and the ball bonding part
The present invention relates to a semiconductor device including a lead wire connected to a stacked region of the first, second, and third metal layers so as not to extend over the film . In addition, as shown in claim 2,
As described above, aluminum (Al) or a metal layer containing aluminum (Al) as a main component can be further provided between the second metal layer and the third metal layer in the first aspect . Claims 1 and 2
The correspondence between the device and the embodiment is as follows. Claim 1
The first, second and third metal layers correspond to the first, second and third metal layers of FIG.
3. The metal layers 14a, 14b, 14c,
The first, second, third and fourth metal layers correspond to the first, second,
Third and fourth metal layers 6a, 6b, 6c, 6d.

[0006]

[Operation and effect of the invention] The invention of claim 1 of the present application is as follows.
Use and effect. (B) Second metal layer made of titanium or molybdenum
Means that the constituent materials of the lead wire are the first metal layer and the semiconductor substrate
Function as a diffusion blocking layer to prevent diffusion into
I do. Therefore, the first metal layer of the constituent material of the lead wire and
Deterioration of ohmic contact due to diffusion into semiconductor substrate
Can be prevented. (B) The first and second metal layers are arranged in the opening of the insulating film.
And a third metal layer is formed to extend over the insulating film.
And a second metal layer of titanium or molybdenum
Not only the top surface but also the side surfaces are covered with the third metal layer
You. Therefore, the oxidation of the second metal layer or the etching solution
Erosion can be satisfactorily prevented. (C) disposing the first and second metal layers in the opening of the insulating film;
The third metal at the edge of the opening of the insulating film.
The step of the metal layer becomes small, and the step of the third metal layer occurs.
Difficult to do. (D) The ball bonding part of the lead wire is on the insulating film
The first and second metal layers are laminated so as not to extend
On the lead wire
The breakdown of the insulating film due to the bug does not occur. Further, according to claim 2
The plan has the same functions and effects as those of claim 1, and
It has an effect. (E) The third metal layer according to claim 2 is a second metal layer.
The layers are formed by continuous evaporation and
It can be obtained by ching. Follow
And immediately oxidizes the second metal layer which is easily oxidized by the third metal layer.
By covering, the oxidation of the second metal layer can be prevented well.
it can. (F) The first, second and third parts are below the ball bonding part.
And a fourth metal layer stacking region, and the thickness of this region is
Thicker than the corresponding region of the invention of claim 1
The first and the second by ball bonding
More reliable destruction or deterioration of metal layer 2 and semiconductor substrate
Can be prevented.

[0007]

First Embodiment Next, a semiconductor device according to a first embodiment of the present invention will be described with reference to FIG. The semiconductor device of this embodiment includes a silicon semiconductor substrate 1, an insulating film 2 formed on the upper surface thereof, and a multi-layered electrode 6 that contacts the semiconductor substrate 1 through an opening 3 of the insulating film 2. The electrodes 6 are made of Al (aluminum) in order from the semiconductor substrate 1 side.
A first metal layer 6a of about 1.0 μm
A second metal layer 6b of about 5000 angstroms of (titanium), a third metal layer 6c of about 1.0 μm of Al, and a fourth metal layer of about 3.0 μm of Al It has a metal layer 6d. A method in which the first metal layer 6a, the second metal layer 6b, and the third metal layer 6c are sequentially switched to Al, Ti, and Al while maintaining a low-pressure atmosphere;
After being formed on the entire upper surface of the semiconductor substrate 1 by a so-called continuous vapor deposition method, the outer peripheral side thereof is removed by etching.
First metal layer 6a, second metal layer 6b, and third metal layer 6
c is formed inside the opening 3 when viewed in plan. The fourth metal layer 6d is formed on the upper surface of the third metal layer 6c, the first, second and third metal layers.
An Al film is formed by vacuum deposition so as to cover the side surfaces of the metal layers 6a, 6b, and 6c, the surface of the semiconductor substrate 1 exposed from the opening 3, and the upper surface of the insulating film 2, and the outer peripheral side is etched. Remove and get. The fourth metal layer 6 d extends to the upper surface of the insulating layer 2 outside the opening 3.

The fine lead wire 5 made of Cu is a bonding pad portion, that is, a portion where the first metal layer 6a, the second metal layer 6b, and the third metal layer 6c are formed inside the opening 3 in plan view. Is ball-bonded to the fourth metal layer 6d so as to be located above. The lead wire 5 is heated at its tip to form a sphere, which is crushed and connected to the electrode 6, so that the connection of the lead wire 5 allows the first, third, and fourth metals made of Al in the electrode 6 to be connected. Layers 6a, 6c,
6d is crushed and thinned. However, the second metal layer 6b made of Ti, which is harder than Al, has the first, third, and fourth metal layers.
Hardly crushed as compared with the metal layers 6a, 6c and 6d.

This embodiment has the following effects. (1) Since the second metal layer 6b made of Ti is interposed in the bonding pad portion and functions as a barrier for suppressing the diffusion of the Cu component of the fine lead wire 5, the ohmic contact between the electrode 6 and the semiconductor substrate 1 is good. Can be taken.
In particular, when used in a high-temperature environment, the ohmic property has conventionally tended to decrease, but in the present embodiment, this is improved. (2) Although the second metal layer 6b made of Ti is easily oxidized, the first, second and third metal layers 6a and 6
This problem is solved because b and 6c are continuously vacuum-deposited. (3) First, second and third metal layers 6a, 6b, 6c
Is formed inside the opening 3, so that the step of the second metal layer 6b made of Ti having poor step coverage does not occur. That is, the first, second, and third metal layers 6a, 6b, 6
Although the effect (1) described above can be obtained even if c is extended to the upper surface of the insulating film 3 outside the opening 3, the second metal layer 6b is formed on the opening 3 side of the insulating film 2 when formed in this manner. Step breakage is likely to occur in the ascending part. When the second metal layer 6b is disconnected, a space is easily formed between the first metal layer 6a and the third metal layer 6c at this portion. When the etchant enters this space, the first, second and third metal layers 6a, 6b,
6c may be etched in an undesired state.
In the present embodiment, such a situation can be prevented. (4) Second metal layer 6b having Cu diffusion blocking function
Is covered with a third metal layer 6c, and the side surface is made of a fourth metal layer.
Since the second metal layer 6b is covered with the metal layer 6d,
Protect not only the surface but also the side surface from oxidation or etchant etc.
Can be (5) The fourth metal layer 6d is formed by the third metal layer 6c.
The reinforcing effect can be obtained and the ball bond of the lead wire 5 can be obtained.
The first and second metal layers 6a, 6b and half
Stress on the conductor base 1 can be reduced. (6) The ball bonding portion of the lead wire 5 is the insulating film 2
Does not extend over the insulating film 2, so that the insulating film 2 is not broken.

[0010]

Second Embodiment Next, a semiconductor device according to a second embodiment will be described with reference to FIG. The semiconductor device shown in FIG. 3 includes a silicon semiconductor substrate 11, an insulating film 12 formed on an upper surface thereof, and an opening 13 in the insulating film 12.
And a thin lead wire 15 connected to the electrode 14. The electrode 14 is the semiconductor substrate 1
A first metal layer 14a made of Al and having a thickness of about 1.0 μm, a second metal layer 14b made of Mo (molybdenum) having a thickness of about 0.3 μm, and a thickness of Al The third metal layer 14c has a thickness of 3 μm. The first metal layer 14a and the second metal layer 14b are formed on the entire upper surface of the semiconductor substrate 11 by a method of sequentially switching the evaporation material to Al and Mo while maintaining a low-pressure atmosphere, that is, a continuous evaporation method.
After the layers are formed in layers, the outer peripheral side of the metal layer is removed by etching. The first metal layer 14a and the second metal layer 14b are provided inside the opening 13 in plan view. The third metal layer 14c includes the first and second metal layers 14c.
a, 14b, after forming the upper surface of the second metal layer 14a,
Side surfaces of first and second metal layers 14a and 14b, opening 13
An Al layer is vacuum-deposited so as to cover the surface of the semiconductor substrate 11 and the upper surface of the insulating film 12, which are exposed to the outside, and then the outer peripheral side of the Al layer is removed by etching. Third metal layer 14c
Extends to the outside of the opening 13 in plan view, and covers the first and second metal layers 14a and 14b.

The lead wire 15 is made of Cu, and the electrode 14
Bonding pad region, that is, the first metal layer 14a
And a second metal layer 14b and a third metal layer 14c are ball-bonded to a region where the metal layers are vertically stacked. this
When performing ball bonding, the distal end portion of the fine lead wire 15 is heated to form a spherical portion (ball) , which is pressed against the electrode 14 in the vertical direction to be connected. Therefore, the ball bonding portion 15a of the fine lead 15 is formed.
Then, the electrode 14 is crushed and thinned as in the conventional example.

This embodiment has the following effects. (1) M is provided below the bonding pad region of the electrode 14.
The second metal layer 14b made of o intervenes, and this suppresses the Cu component of the fine lead wire 15 from diffusing downward. Therefore, an ohmic contact between the electrode 14 and the semiconductor region 11 can be made well. In particular, when used in a high-temperature environment, in the conventional example, the reduction in ohmic properties due to the Cu diffusion was apt to occur, but this embodiment solves this problem. (2) Since the first and second metal layers 14a and 14b are covered with the third metal layer 14c, a highly reliable electrode structure is provided. That is, even if the electrode is formed by continuously depositing the first, second and third metal layers 14a, 14b and 14c and etching away the outer peripheral side of these metal layers at once, the above (1) The effect is obtained. However, since Mo has a higher etch rate with respect to a phosphoric acid-based etchant than Al, a step occurs in an etched cross section. Since it is difficult to cover the step portion with a protective resin or the like, harmful substances such as moisture easily enter and cause deterioration of characteristics. In the present embodiment, the second metal layer 14b
Is covered with the third metal layer 14c, and no step is formed on the side surface of the electrode 14, so that this problem is solved. (3) Since the second metal layer 14b made of Mo is covered not only with the top surface but also with the side surface with the third metal layer 14c, not only the top surface but also the side surface of the second metal layer 14b is oxidized or etched. Etc. can be protected. (4) Since the first and second metal layers 14a and 14b are arranged in the opening 13 of the insulating film 12, the insulating film 12
The step of the third metal layer 14c at the edge of the opening 13 becomes small, and this step is hardly generated. (5) Since the ball bonding portion 15a of the lead wire 15 does not extend over the insulating film 12, the insulating film 12 is not damaged.

[0013]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The thickness of the second metal layers 6b and 14b can be changed. However, the second metal layer 6b in the case of Ti is C
In order to effectively prevent the u component from penetrating downward, 3000
Should be set to angstrom or higher. In the case of Mo, it should be set to 0.1 μm or more.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of a semiconductor device according to a first embodiment.

FIG. 2 is a cross-sectional view showing a part of a conventional semiconductor device.

FIG. 3 is a sectional view showing a part of the semiconductor device according to a second embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor base 2 Insulating film 3 Opening 6 Electrode 6a 1st metal layer 6b 2nd metal layer 6c 3rd metal layer 6d 4th metal layer

Claims (2)

(57) [Scope of request for utility model registration] A semiconductor substrate and an insulation formed on the semiconductor substrate and having an opening.
A film, formed on the surface of the semiconductor substrate exposed by the opening, and formed so as not to extend on the insulating film.
Aluminum (Al) or aluminum (Al)
A first metal layer made of a material having, as a main component, a first metal layer formed on the first metal layer and between the first metal layer and the opening;
From titanium (Ti) or a material containing titanium (Ti) as a main component or molybdenum (Mo) or a material containing molybdenum (Mo) as a main component, formed smaller than the opening so as to form a gap. a second metal layer made, are formed so as to cover the upper and side surfaces of the second metal layer
And a third metal layer formed of aluminum (Al) or a material containing aluminum (Al) as a main component formed so as to extend on the insulating film, and a ball bonding portion. This ball bonding
The first so as not to extend to the upper parts is the insulating film, a semiconductor device that includes a Li <br/> lead wires connected to the deposition area of the second and third metal layers. 2. A semiconductor substrate and an insulation formed on the semiconductor substrate and having an opening.
A film and a surface exposed by the opening of the semiconductor substrate.
So that a gap is formed between the opening and the opening.
Formed smaller than the opening and extending over the insulating film
A first metal layer made of aluminum (Al) or a material containing aluminum (Al) as a main component formed so as not to be formed; and a first metal layer formed on the first metal layer and viewed in plan.
Titanium (Ti) or a material containing titanium (Ti) as a main component or molybdenum (Mo) or a material containing molybdenum (Mo) as a main component formed so as to have substantially the same area as the first metal layer. A second metal layer made of a material; and a second metal layer formed on the second metal layer and viewed in plan.
Formed to have approximately the same area as the second metal layer
From aluminum or substances containing aluminum as the main component
The third metal layer, said third upper surface and the first metal layer, the second, third gold comprising
And formed on the insulating film so as to cover the side surfaces of the metal layer.
A fourth metal layer formed of aluminum (Al) or a material containing aluminum (Al) as a main component formed so as to extend, and a ball bonding portion;
The first so as not to extend to the upper parts is the insulating film, the second, is connected to the deposition area of the third and fourth metal layers Tei
Semiconductor device having a lead wire that.