JPH0669033B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to patterning of an aluminum electrode, and particularly to a semiconductor device which does not roughen an oxide film when patterning an aluminum electrode formed on an oxide film by dry etching. The present invention relates to a manufacturing method of.

(2) Background of the Invention In manufacturing a semiconductor device such as a planar transistor, etching is repeatedly performed for processing an aluminum electrode and removing a photoresist. Usually, this etching includes wet etching in which unnecessary aluminum or photoresist is dissolved using a liquid, and dry etching in which unnecessary aluminum or photoresist is removed using plasma in a gas such as fluorocarbon.

Dry etching is currently used especially because it does not require manual control of chemical purity and can easily replace the work process with mechanical work.

(3) Prior Art and Problems FIG. 1A to FIG. 1C show a manufacturing process for processing an aluminum electrode by dry etching in a semiconductor device.

First, as shown in FIG. 1A, aluminum (Al) 3 is deposited on an oxide film 2 of silicon oxide (SiO ₂ ) formed on a silicon (Si) substrate 1 and an opening 2a of the oxide film 2, An alumina layer 4 is formed on the aluminum 3 by natural oxidation or anodic oxidation, and a resist 5 is applied only to a portion of the alumina layer 4 necessary as an electrode to pattern the aluminum electrode. Next, as shown in FIG.
The portion of the alumina layer 4 not coated with is removed by dry etching. Further, in the process shown in FIG. 3C, the aluminum 3 in the portion not coated with the resist is removed by dry etching, and finally the resist 5 is removed.

The electrode patterning of the aluminum 3 is performed on the oxide film 2 and the opening of the oxide film 2 by the above process.

However, at this time, since reactive ion etching (RIE) in which alumina is hard to be removed is used as the dry etching, the alumina layer 4 formed on the surface of the aluminum 3 has unevenness as shown in FIG. Etching is performed.

Furthermore, this step is formed when etching aluminum 3.
The oxide film 2, which is an insulating layer, is also affected, so that the surface of the oxide film 2 becomes uneven as shown in FIG. That is, the oxide film 2 before dry etching has a thickness of about 4000Å, but after dry etching, the convex portion has a thickness of about 3000Å and the concave portion has a thickness of about 1000Å. This oxide film 2 is an insulating layer of a semiconductor device,
When the oxide film 2 has irregularities, insulation defects occur in the recesses, which also causes a short circuit.

Further, in order to reduce the number of recesses formed in the oxide film 2 reaching the silicon substrate 1, the dry etching time of the aluminum 3 must be finely controlled.

(4) Object of the invention In view of the above-mentioned conventional drawbacks, the present invention provides a step of removing the alumina layer by wet etching, and subsequently, using the pattern film as a mask, an etchant for removing aluminum, 10
A semiconductor device including: a step of wet-etching a surface layer having a thickness of ⅕; and a step of removing the aluminum layer by dry etching using the pattern film as a mask and transferring the pattern of the pattern film to the aluminum layer. It aims at providing the manufacturing method of.

(5) Essential Points of the Invention According to the present invention, the above object is to form an insulating film on the surface of a semiconductor substrate and to form an aluminum layer on the insulating film, and to form a predetermined pattern film on the aluminum layer. A step of forming and removing the alumina layer on the surface of the aluminum layer by wet etching using the pattern film as a mask;
Subsequently, using the pattern film as a mask, a step of wet-etching the surface layer of the aluminum layer with an etchant for removing aluminum, and the aluminum layer is removed by dry etching using the pattern film as a mask, and the pattern of the pattern film is aluminum. And a method of manufacturing a semiconductor device including the step of transferring to a layer.

(6) Embodiments of the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, the oxide film 7 formed on the silicon substrate 6
Aluminum 9 is vapor-deposited in the opening 8 of the oxide film 7 by the process shown in FIG. 3A to a thickness of 1 μm, for example, and an alumina layer 10 is formed on the aluminum 9 by natural oxidation or anodic oxidation. Further, a resist 11 is applied on the alumina layer 10 only in a portion required as an electrode of a semiconductor device.
Next, in the process shown in FIG. 2B, the resist 11 is formed by wet etching using an etchant for removing alumina (for example, a mixed solution of acetic acid and ammonium fluoride).
The part of the alumina layer 10 not coated with is removed. At this time, in order to completely remove the alumina layer 10, wet etching using an etchant for removing aluminum (for example, an organic alkaline solution or a solution of phosphoric acid or the like) is performed, so that the surface of the aluminum 9 also has a thickness of 1 / m of the total thickness of 1 μm.
A thickness of 1000Å to 2000Å corresponding to 10 to 1/5 is removed. At this time, since only a slight surface layer of the aluminum 9 is wet-etched, there is almost no influence of the side etching on the aluminum 9 under the resist 11 to be wiring. Further, in the process shown in FIG. 3C, the aluminum 9 in the portion where the resist 11 is not applied is removed by dry etching using reactive ion etching, and finally the resist 11 is removed.

An electrode of aluminum 9 can be provided on the silicon substrate 6 by the above process.

Thus, if the alumina layer 10 on the surface of the aluminum 9 is removed by first performing wet etching, the unevenness generated when the conventional alumina layer 10 is removed by dry etching is unlikely to occur. Moreover, even after a part of the alumina layer 10 remains on the aluminum 9 after this wet etching, the surface layer of the aluminum 9 is subsequently wet-etched by an etchant that removes aluminum, so that the remaining alumina layer Can be completely removed by a lift-off process-like effect (that is, even if the upper layer remains, the upper layer can also be removed by etching the lower layer). As a result, the surface of the aluminum 9 does not have unevenness as in the conventional case, and sufficient flatness can be obtained.

As described above, since the surface of the aluminum 9 is not uneven, the surface of the oxide film 7 is not uneven even if the aluminum 9 is completely removed by dry etching thereafter. Therefore, the surface of the oxide film 7 is flat, the thickness of the oxide film 7 is about 3000 Å, and the thickness of each part of the oxide film 7 is constant. Therefore, the electrodes of aluminum 9 and silicon 6 are reliably insulated from the external conductive material.

(7) Effects of the Invention As described in detail above, according to the present invention, since the oxide film which is the insulating film of the semiconductor does not have unevenness, the semiconductor device can be reliably insulated.

Further, since the oxide film 7 does not have unevenness, aluminum 9
It becomes easy to control the etching time of the dry etching.

[Brief description of drawings]

1 (a) to 1 (c) are manufacturing process diagrams of a conventional semiconductor device, and FIG.
(A)-(c) is a manufacturing process drawing of the semiconductor device of the present invention. 6 ... Silicon, 7 ... Oxide film, 9 ... Aluminum,
10 ... Alumina layer, 11 ... Resist

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-180149 (JP, A) JP-A-59-23876 (JP, A) JP-A-55-30826 (JP, A) JP-B-49- 40844 (JP, B2)

Claims (1)

[Claims] 1. A step of forming an insulating film on a surface of a semiconductor substrate, forming an aluminum layer on the insulating film, and forming a predetermined pattern film on the aluminum layer and using the pattern film as a mask to form the aluminum layer. A step of removing the alumina layer on the surface by wet etching, and subsequently, using the pattern film as a mask, an etchant for removing aluminum is used to make 1/10 to 1/1 of the entire aluminum layer.
Wet-etching the surface layer having a thickness of / 5,
A step of removing the aluminum layer by dry etching using the pattern film as a mask, and transferring the pattern of the pattern film to the aluminum layer.