JP2882065B2 - Method for manufacturing 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 method for manufacturing a semiconductor device, and more particularly, to a method for forming a passivation film on a surface of a semiconductor device.
The present invention relates to a method for forming an electrode pad exposed from the passivation film.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a semiconductor device having a passivation film and an electrode pad, for example, FIG.
As shown in FIG. 1, an aluminum film 2 is formed on a silicon substrate 1 by a sputtering method or the like, and a top pattern wiring 4 having a desired pattern shape and a mask pattern 3A of an electrode pad portion 5 serving as an input / output terminal are formed using a photoresist. . Then
As shown in FIG. 3B, the aluminum film 2 is etched by reactive ion etching or the like using the mask pattern 3A to form the uppermost layer wiring 4 and the electrode pad portion 5 at the same time, and then as a passivation film as shown in FIG. 3C. The silicon nitride film 6 is coated by a plasma CVD method or the like. next,
Mask pattern 3 made of photoresist as shown in FIG. 3D
B is formed, and the silicon nitride film 6 is etched using the B, and only the electrode pad portion 5 is opened. Further, FIG.
3F, a photoresist mask pattern 3C is formed as shown in FIG. 3F, and the polyimide film 7 is formed using tetramethylammonium hydroxide (TMAH) as shown in FIG. Is selectively etched to open only the electrode pad portion 5 so that the electrode pad portion 5 is exposed in the opening.

[0003]

In the above-described conventional method for manufacturing a semiconductor device, the formation of a mask pattern using a photoresist and the etching step using the same are each performed in three steps.
However, there is a problem that the number of manufacturing steps is large and complicated. For this reason, photosensitive polyimides have been developed in recent years so that they can be easily patterned, but they are inferior in terms of tightness and moisture resistance with respect to the resin for semiconductor device sealing. In addition, a silicon nitride film formed by a plasma CVD method, which has excellent moisture resistance as a passivation film, has a thickness of 1 to 5.
Since it has a compressive stress of 9 × 10 ⁹ dyn · cm ^-2 ,
When a hole is formed in a thin film state of the silicon nitride film 6 as shown in D, the stress balance is broken at this hole and the silicon nitride film 6
There is a problem that cracks 8 occur. Similarly, in the opening for the polyimide film 7, the polyimide film 7
There is a problem that cracks 8 are likely to be generated in the opening portions by selectively etching the. Furthermore, when non-photosensitive polyimide is used, a highly dangerous chemical solution such as hydrazine is required at the time of opening, and there is a problem that a device for safety must be provided. An object of the present invention is to provide a manufacturing method in which the number of manufacturing steps is reduced and cracks in a passivation film are prevented.

[0004]

According to the manufacturing method of the present invention, a metal film is formed on a semiconductor substrate on which an electronic circuit including a semiconductor element is formed, and a mask pattern of an electrode pad portion is formed on the metal film. And selectively etching and removing the upper layer portion of the metal film with the mask pattern,
Forming a mask pattern of wiring and electrode pad portions on the metal film, selectively removing the lower layer portion of the metal film with this mask pattern to form wiring and electrode pads, and forming a passivation film on the entire surface. The method includes a step of coating and a step of etching back the passivation film to expose only the electrode pad portion.

[0005]

Next, the present invention will be described with reference to the drawings. 1A to 1G are longitudinal sectional views showing a first embodiment of the present invention in the order of manufacturing steps. First, as shown in FIG. 1A, a surface of a silicon substrate 1 on which an electronic circuit including a semiconductor element is formed is coated with an aluminum film 2 to a thickness of 2 μm by a sputtering method or the like. Next, a mask pattern 3A is formed using a photoresist only for the electrode pad portion 5, which is an input / output terminal. Then, as shown in FIG. 1B, the aluminum film 2 is formed by reactive ion etching or the like using this mask pattern.
Is removed by etching for a thickness of 1 μm.

Next, after the mask pattern is incinerated and removed by oxygen plasma, a mask pattern 3B is formed on both the uppermost layer wiring 4 and the electrode pad portion 5 using a photoresist as shown in FIG. 1C. Then, as shown in FIG. 1D, the aluminum film 2 is formed by reactive ion etching or the like.
Are removed by etching to form the uppermost layer wiring 4 and the electrode pad portion 5. Next, after the mask pattern 3A is ashed and removed by oxygen plasma, as shown in FIG. 1E, a 1 μm silicon nitride film 6 is coated as a first passivation film by a plasma CVD method. Further, as shown in FIG. 1F, a non-photosensitive polyimide film 7 is applied as a second passivation film to a thickness of 2 μm and baked at 350 ° C.

[0007] Thereafter, the gas and the high-frequency power source such as oxygen and carbon tetrafluoride (CF ₄₎ by reactive ion etching or the like as shown in FIG. 1G, for example, by 13.56MH _Z low pressure (0.1 to 50
By simultaneously etching back the entire surface of the polyimide film 7 and the silicon nitride film 6 in the closed container of Pa), only the upper surface of the electrode pad portion 5 formed thicker than the uppermost wiring 4 is exposed.

[0008] By forming the electrode pad portion 5 in this manner, in the etching back step for exposing the upper surface, the silicon nitride film 6 alone is not etched alone, and the polyimide film 7 is formed on the entire surface. Since the film is sufficiently covered, the stress balance does not locally deteriorate and the silicon nitride film 6 does not crack. Further, since there is no need to form an opening in the polyimide film 7, no crack is generated in the polyimide film 7. Further, the formation of the mask pattern by the photoresist and the etching process using the same may be performed twice,
The number of manufacturing steps can be reduced. Further, even if a non-photosensitive polyimide is used, it is not necessary to use a highly dangerous chemical such as hydrazine, and a special device for safety is not required.

FIGS. 2A to 2G are cross-sectional views showing a second embodiment of the present invention in the order of manufacturing steps, and portions equivalent to those of the first embodiment are denoted by the same reference numerals. In this embodiment, FIG.
2B, as in the first embodiment, after selectively etching the upper layer of the aluminum film 2, a mask pattern 3B 'is formed to cover the upper surface of the uppermost layer wiring 4 and the electrode pad 5 and the periphery thereof. The point of formation is different from the first embodiment. Therefore, by etching the aluminum film 2 using the mask pattern 3B 'in this manner, the electrode pad portion 5 has a step 2a at the peripheral portion as shown in FIG. 2D.
Are formed in the cross-sectional shape. Thereafter, as shown in FIGS. 2E to 2G, the same process as in the first embodiment is performed to expose the upper surface of the electrode pad portion 5, and in the electrode pad portion 5, the inclination of the silicon nitride film 6 is reduced by the step 2a. The stress concentration of the silicon nitride film 6 in the electrode pad portion 5 can be suppressed, and cracks can be more effectively prevented.

[0010]

As described above, according to the present invention, a metal film is etched using a mask pattern to form an electrode pad portion with a thickness greater than that of a wiring, and a passivation film is formed thereon. Since the upper surface of the electrode pad portion is exposed by etching back later, a mask pattern forming process using a photoresist and an etching process using this mask pattern can be performed twice. The number of manufacturing steps can be reduced as compared with three times. Further, a step of selectively opening a silicon nitride film or a polyimide film as a passivation film is not required, and there is an effect that cracks generated in the passivation film in the opening step can be prevented. Further, there is an effect that a chemical solution such as hydrazine becomes unnecessary, and a device for safety measures can be made unnecessary.

[Brief description of the drawings]

FIG. 1A ~

FIG. 1G is a sectional view showing the first embodiment of the present invention in the order of manufacturing steps.

FIG. 2A ~

FIG. 2G is a sectional view showing the second embodiment of the present invention in the order of the manufacturing steps.

FIG. 3A ~

FIG. 3G is a cross-sectional view showing the conventional manufacturing method in the order of steps;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Aluminum film 3A, 3B, 3B 'Mask pattern 4 Top layer wiring 5 Electrode pad part 6 Silicon nitride film (passivation film) 7 Polyimide film (passivation film)

Claims (1)

(57) [Claims] 1. A step of forming a metal film on a semiconductor substrate on which an electronic circuit including a semiconductor element is formed, and a step of forming a mask pattern of an electrode pad portion as an input / output terminal of the electronic circuit on the metal film. And selectively etching away the upper layer of the metal film with the mask pattern;
Forming a mask pattern of an uppermost layer wiring of the electronic circuit and the electrode pad portion on the metal film; and selectively etching and removing a lower layer portion of the metal film by using the mask pattern. Forming a;
A method of manufacturing a semiconductor device, comprising: a step of covering a whole surface with a passivation film; and a step of etching back the passivation film to expose only the electrode pad portion.