JP2000031123A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the reaction product made of a polymer and to form superior polyimide film at the opening of a passivation film, comprising two layers of an SiO2 film and an SiN film. SOLUTION: A patterned photosensitive polyimide film 7 is set as the mask. CF4 gas is used, and under the conditions of RF power and pressure, which can cause a plasma, isotropic plasma etching is performed for an SiN film 4 at a flow rate of 100SCCM or higher. When an SiO2 film 3 is exposed, the etching conditions are changed, and the main etching gas is set as CF4. Anisotropic plasma etching is performed on the SiO2 film by the gas, wherein the gas of the anisotropic component is mixed with CHF3 or C2Cl2F4 and moreover Ar and O2 and so on are mixed at a constant rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to an opening in a passivation film.

[0002]

2. Description of the Related Art In general, a semiconductor device on a wafer is completed by forming various elements and then protecting an uppermost aluminum wiring layer with a passivation film. After that, the wafer is divided into chips for packaging and assembly is performed, but it is necessary to open a passivation film for packaging.

FIG. 3 is a process chart showing a conventional method for manufacturing a semiconductor device. In FIG. 3, 1 is a substrate and various elements formed on the substrate, 2 is an uppermost aluminum wiring layer, 3
Denotes a SiO ₂ film, 4 denotes a SiN film, and 6 denotes a resist pattern. The passivation film 5 is constituted by two layers of the SiO ₂ film 3 and the SiN film 4.

First, in FIG. 3A, anisotropic plasma etching is performed by using a resist gas 6 as a mask and using a mixed gas of CHF ₃ / CF ₄ / Ar / O _2.
Two layers of the iO ₂ film 3 and the SiN film 4 are etched. As a result, as shown in FIG. 3B, the passivation film 5 on the aluminum wiring layer 2 is opened.

Some semiconductor devices require further protection against moisture resistance, scratches, etc., in which a polyimide film is formed on the passivation film 5. In this case, using a patterned polyimide film as a mask instead of the resist pattern 6 in FIG.
Anisotropic plasma etching is performed using a mixed gas of HF ₃ / CF ₄ / Ar / O ₂ to open the passivation film 5.

[0006]

The conventional method of manufacturing a semiconductor device is as described above. As shown in FIG.
_{Since the} passivation film 5 composed of two layers of the _two films 3 and the SiN film 4 is opened by one etching, CHF ₃
Anisotropic etching must be performed for a long time using a mixed gas of / CF ₄ / Ar / O ₂ .

Therefore, a mixed gas of CHF ₃ / CF ₄ / Ar / O ₂ reacts with the passivation film 5 composed of two layers of the SiO ₂ film 3 and the SiN film 4, and the polymer mainly containing C and H reacts. A reaction product consisting of It is difficult to completely remove this polymer even in the step of removing the resist pattern 6 serving as a mask, and there is a problem that the polymer remains as a foreign substance and causes a reduction in yield.

Further, in the case of a semiconductor device having a polyimide film on the passivation film 5, a mask removing step is not required because the polyimide film is used as a mask. For this reason, there is a problem that the reaction product made of the polymer is more likely to remain than when the resist pattern 6 is used as a mask.

Further, O ₂ in the mixed gas of _{CHF 3 / CF 4 / Ar /} O 2 is a polyimide film is etched, there is a problem of reduced thickness of the polyimide film occurs. Further, since the anisotropic etching is performed for a long time, the polyimide film is exposed to the plasma or the high-temperature atmosphere for a long time, so that the polyimide film contracts and the polyimide film and the SiN film 4 are not exposed.
There is also a problem that the adhesion to the film is reduced and the polyimide film is peeled off.

The present invention has been made in order to solve the above problems, and provides a method of manufacturing a semiconductor device capable of reducing a reaction product composed of a polymer and forming a good polyimide film. It is intended to be.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising:
₂ film, a step of the upper layer is a passivation film composed of two layers of SiN film, an isotropic plasma etch in the SiN film using the resist pattern as a mask, the S
opening the passivation film by performing anisotropic plasma etching on the iO ₂ film.

In the method of manufacturing a semiconductor device according to a second aspect of the present invention, the mask used for opening the passivation film is a polyimide film.

According to a third aspect of the present invention, in a method of manufacturing a semiconductor device, isotropic plasma etching is mainly performed by using CF _4.
Gas is used, and anisotropic plasma etching is performed using CF.
_{The process} is mainly performed using _four gases, CHF ₃ or C ₂ Cl ₂ F ₄ as an anisotropic component gas, and a gas obtained by mixing Ar and O ₂ at a fixed ratio.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a process chart showing a method for manufacturing a semiconductor device according to the present invention. In FIG. 1, reference numeral 1 denotes a substrate and various elements formed on the substrate;
Is the uppermost aluminum wiring layer, 3 is a SiO ₂ film, 4 is SiN
Reference numeral 6 denotes a resist pattern, and the SiO ₂ film 3 and Si
The passivation film 5 is composed of two layers including the N film 4.

[0015] First, in FIG. 1 (a), the resist pattern 6 as a mask, the flow 100 using a CF ₄ gas
RF power and pressure capable of generating plasma at _SCCM or higher, for example, RF power 150 W, pressure 550 mmH
The isotropic plasma etching is performed on the SiN film 4 under the condition of g.

Next, as shown in FIG. 1B, when the etching of the SiN film 4 is completed and the SiO ₂ film 3 is exposed, the etching conditions are changed, the main etching gas is CF ₄ , and the anisotropic Component gas is CHF ₃ or C ₂ Cl ₂ F
₄ , a gas obtained by mixing Ar, O _{2, and the} like at a constant ratio, for example, having a gas flow ratio of CHF ₃ or C ₂ Cl ₂ F ₄ / C
Anisotropic plasma etching is performed on the SiO ₂ film 3 under the conditions of F ₄ / Ar / O ₂ = 55/65/800/8 and RF power and pressure capable of generating plasma, for example, RF power of 500 W and pressure of 500 mmHg. Apply.

As a result, the passivation film 5 is opened as shown in FIG. After that, as shown in FIG. 1D, the resist pattern 6 is removed.

As described above, the passivation film 5 is etched in two stages, ie, isotropic plasma etching and anisotropic plasma etching. Can be reduced.

Embodiment 2 Here, a case where a polyimide film is provided over a passivation film will be described. FIG. 2 is a process chart showing a method for manufacturing a semiconductor device according to the present invention. In FIG. 2, reference numeral 1 denotes a substrate and various elements formed on the substrate, 2 denotes an uppermost aluminum wiring layer, and 3 denotes SiO _2.
The film 4, 4 are SiN films, 6 is a resist pattern, 7 is a polyimide film, and the passivation film 5 is composed of two layers of the SiO ₂ film 3 and the SiN film 4.

First, as shown in FIG. 2A, a photosensitive polyimide film 7 is formed on the passivation film 5 and patterned. Next, in FIG. 2B, using the patterned photosensitive polyimide film 7 as a mask, C
The SiN film 4 is subjected to isotropic plasma etching under the conditions of RF power and pressure capable of generating plasma, for example, RF power of 150 W and pressure of 550 mmHg at a flow rate of 100 _SCCM or more using F ₄ gas.

Next, as shown in FIG. 2C, when the etching of the SiN film 4 is completed and the SiO ₂ film 3 is exposed, the etching conditions are changed, the main etching gas is CF ₄ and the anisotropic Component gas is CHF ₃ or C ₂ Cl ₂ F
₄ , a gas in which Ar, O _2, etc. are mixed at a constant ratio, for example, a gas flow ratio of CHF ₃ or C ₂ Cl ₂ F ₄ / CF
_{4 / Ar / O 2 = 55} /65 / at 800/8, RF power and pressure that can cause plasma, for example, RF power 500 W, SiO ₂ film 3 under a pressure of 500mmHg
Is subjected to anisotropic plasma etching. As a result, FIG.
As shown in (d), the passivation film 5 is opened.

As described above, since the passivation film 5 is etched in two stages of isotropic plasma etching and anisotropic plasma etching, the passivation film 5 is not exposed to the anisotropic plasma etching for a long time, and the reaction product of polymer Of the polyimide film 7 and a decrease in the film thickness of the polyimide film 7 due to O ₂ can be prevented, and a favorable polyimide film can be maintained.

[0023]

As described above, according to the present invention, a step of forming a passivation film having a lower layer of SiO ₂ film and an upper layer of SiN film on a substrate, and forming the passivation film on the SiN film using a resist pattern as a mask. A step of opening the passivation film by performing isotropic plasma etching on the SiO ₂ film and anisotropic plasma etching on the SiO ₂ film. In addition, a reaction product composed of a polymer can be reduced.

Further, since the mask used for opening the passivation film is a polyimide film, the polyimide film is not exposed to anisotropic plasma etching for a long time, and the adhesion is reduced due to shrinkage of the polyimide film. Also, a decrease in the thickness of the polyimide film due to O ₂ and O ₂ can be prevented, and a good polyimide film can be maintained.

The isotropic plasma etching is mainly performed by using CF ₄ gas, and the anisotropic plasma etching is mainly performed by using CF ₄ gas as the main component and using an anisotropic component gas of C ₄ gas.
Since the process is performed using HF ₃ or C ₂ Cl ₂ F ₄ and a gas in which Ar and O ₂ are mixed at a fixed ratio, the opening of the passivation film can be satisfactorily performed.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process chart showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a process chart showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 substrate, 3 SiO ₂ film, 4 SiN film, 5 passivation film, 6 resist pattern, 7 polyimide film.

Continued on front page F term (reference) 5F004 DA01 DA08 DA16 DA23 DA26 DA30 DB03 DB07 EA29 EB01 EB03 5F040 DA29 EH08 EJ08 EL01 EL02 EL06 FC21 FC23 5F058 AA02 AA08 AC02 AD10 AD11 AF04 AG04 AH03 BC02 BC08 BD01 BD04 BD10 BHJ B

Claims (3)

[Claims] A lower layer is a SiO ₂ film and an upper layer is a Si layer on a substrate.
Forming a two-layer passivation film of an N film, and performing isotropic plasma etching on the SiN film and anisotropic plasma etching on the SiO ₂ film using a resist pattern as a mask; Forming a semiconductor device. 2. The method according to claim 1, wherein the mask used for opening the passivation film is a polyimide film. 3. The method according to claim 1, wherein the isotropic plasma etching mainly comprises C
Performed using F ₄ gas, as a main anisotropic plasma etching of CF ₄ gas, the gas of the anisotropic component CHF <sub>3
3. The</sub> method for manufacturing a semiconductor device according to claim 1, wherein the method is performed by using C ₂ Cl ₂ F ₄ and a gas in which Ar and O ₂ are mixed at a fixed ratio.