JPH03262122A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reliability of wire bonding, and to make it possible to prevent the lowering of yield of production and reliability of LSI and the like by a method wherein a non-penetrated aperture is formed on an insulating film by etching, an argon sputtering treatment is conducted, and then an aperture is formed by penetrating the non-penetrated aperture. CONSTITUTION:When an insulating film 3 is etched by RIE treatment using a resist film 4 as a mask, the resist component dissolved by the RIE etching is adhered, as the deposited film 7 of polymer to the side wall of the section to be etched, namely, the aperture 5 for etching of the resist film 4 and the side wall of a non-penetrated bonding window 6a which is being formed. At that time, a wire-bonding window 6 is etched to the extent that the window 6 is brought into the state of non-penetrated window 6a having the depth just before penetration, and the etching operation is temporarily discontinued. Then, an argon sputtering treatment is conducted, a polymer deposited film 6 is sputtered by argon particles 8, and after the film 7 is removed by scattering, the coated insulating film 3 is etched again until a bonding pad 2 is exposed, and a wire bonding window 6 is completed.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the method of manufacturing semiconductor devices, especially the method of forming a wire bonding window in an insulating film in the manufacturing process of LSI, etc., the present invention involves depositing a deposited film such as a polymer on a bonding pad. The purpose of this invention is to provide a method for forming a wire bonding window that does not interfere with the wire bonding.
When forming an opening (6) exposing the surface of the conductive substrate (2) by reactive ion etching using a mask as a mask, a non-penetrating opening (6) is formed in the insulating film (3) by the reactive ion etching. 6a), and perform argon sputtering while leaving the resist (4) to remove the polymeric substance (7) adhering to the inner surface of the non-through hole (6a). A non-through hole (
6a) to form an opening (6).

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and particularly to an improvement in a method for forming a wire bonding window in an insulating film in the manufacturing process of an LSI or the like.

The reliability of wire bonding when incorporating chips such as LSI into a package depends on the cleanliness of the surface of the bonding pad made of a conductive substrate such as aluminum (AI!) exposed within the wire bonding window of the insulating film. Therefore, there is a need for a technique for forming wire bonding windows that does not allow foreign matter to adhere to the surface of the bonding pad.

[Conventional technology]

Generally, in the manufacturing process of LSI etc., active ion etching (RIB) is used to form wire bonding windows.
) process is widely used, and conventionally, when forming a wire bonding window 56 exposing the bonding pad in an insulating film that covers the bonding pad made of, for example, An, the process shown in FIG. 3(a) is used. As shown in FIG. 3, a resist film 54 is coated on the covering insulating film 53 that covers the interlayer insulating film 51 on which the bonding pad 52 is formed, and a shape corresponding to the wire bonding window is formed on this resist film 54 by a photo process. After forming the etching holes 55, as shown in FIG. 3(b), the resist film 54 is
A method has been used in which a RIE process is performed using the resist film 54 as a mask, and the covering insulating film 53 under the etching opening 55 of the resist film 54 is selectively etched at once until the bonding pad 52 is exposed.

[Problem to be solved by the invention]

However, according to the above-mentioned conventional method, when the film to be etched on the bonding pad, that is, the covering insulating film 53, becomes thick and the etching time becomes long, polymers ( As shown in FIG. 3(a), the polymeric substance 57 may re-deposit on the surface of the bonding pad 52 in the form of a film. Therefore, the above-mentioned pounding pad 5
When bonding, for example, a gold wire (not shown) onto the pad 2 by thermocompression bonding or the like, the polymer 57 is interposed between the bonding pad 52 and the gold wire (not shown) to ensure complete bonding. There is a problem in that the yield and reliability of LSI etc. are reduced due to interference and bonding peeling.

Therefore, the present invention improves the reliability of wire bonding and
An object of the present invention is to provide a method for forming a wire bonding window without depositing a deposited film of polymer or the like on a bonding pad, in order to prevent a decrease in manufacturing yield or reliability of LSI or the like.

[Means to solve the problem]

The above problem is solved by the insulating film (
3), when forming an opening (6) exposing the surface of the conductive substrate (2) by reactive ion etching using the resist (4) as a mask, the insulating film (3) is formed by the reactive ion etching. ) with an unpierced hole (6a
) and a first etching step to form the resist (4).
) is left intact to remove the polymeric substance (7) adhering to the surface of the resist and the inner surface of the non-penetrating hole (6a), and the resist (4) is masked. Solved by the method for manufacturing a semiconductor device according to the present invention, which includes a second etching step of penetrating the non-through hole (6a) of the insulating film (3) by reactive ion etching to form the hole (6). be done.

[For production]

FIGS. 1(a) to 1(C) are process sectional views for explaining the principle of the present invention.

In the figure, 1 is an interlayer insulating film, 2 is a bonding pad (conductive base), 3 is a covering insulating film (insulating film), 4 is a photoresist film (resist), and 5 is an etching hole in the resist film. , 6 is a through bonding window (opening), 6a
7 indicates a non-penetrating bonding window (a non-penetrating opening), 7 indicates a deposited film such as a polymer (polymerized substance), and 8 indicates an argon (Ar) particle. As shown in FIG. 1(a), the resist film 4
When etching is performed by RIE process using as a mask,
The components of the resist decomposed by the RIE etching form a deposited polymer film 7 on the sidewalls of the etched portion, that is, the etching openings 5 in the resist film 4 and the sidewalls of the non-penetrating bonding windows 6a that are being formed. . If etching is continued in this state, the area to be etched will be etched in a polymer-rich atmosphere.
A deposited polymer film is easily formed on the pad surface.

Therefore, in the method of the present invention, as shown in FIG. 1(a), the wire bonding window 6 is etched to the state of an unpenetrated window 6a having a depth immediately before being penetrated, the etching is temporarily stopped there, and then As shown in FIG. 1(1)), argon sputtering is performed, and the deposited polymer film 7 is struck with argon particles 8 to scatter and remove, and then as shown in FIG. 1(C), The covering insulating film 3 is etched again until the bonding pad 2 is exposed, and the through bonding window (wire bonding window) 6 is completed.

In this way, when the surface of the bonding pad 2 is exposed in the window 6 for wire bonding, the amount of polymer contained in the etching atmosphere on the part to be etched is significantly reduced, so that the window 6 for through bonding The exposed surface of the bonding band 2 becomes a clean surface free from deposits such as polymers.

Therefore, the bonding strength of the gold wire or the like bonded onto the bonding pad 2 by thermocompression bonding or the like is sufficiently ensured.

〔Example〕

Hereinafter, one embodiment of the present invention for forming a window for wire bonding will be specifically described with reference to process cross-sectional views shown in FIGS. 2(a) to 2(C).

Refer to FIG. 2(a) According to the method of the present invention, for example, a bonding pad 12 made of a first Al film is formed on the first interlayer insulating film 11, and A! Silicon oxide (CVDSiOz) film by vapor phase growth 1 with a thickness of about 2000 to suppress the protrusions of
3 is formed, a spin-on glass (SOG) layer 14 is applied to flatten the upper layer wiring formation surface, and a second interlayer insulating film 15 made of phosphosilicate glass (PSG) with a thickness of about 1 μm is applied thereon. is formed, and a second Aff is formed on top of it.
An upper layer wiring 16 made of an i film is formed, and a covering insulating film 17 made of a PSG film 17A with a thickness of about 0.7 μm and a silicon nitride (SiJn) film 17B with a thickness of about 0.3 μm is formed thereon. When forming a wire bonding window that exposes the bonding pad 12 on a semiconductor substrate to be processed, first, three
Forming a positive resist film 18 having a thickness of about μm,
An etching opening 19 having a shape corresponding to the shape of the wire bonding window is formed in this resist film 18 by a normal photo process.

As a first etching process, this resist film 18 is used as a mask, and a normal parallel plate type etching apparatus is used to perform etching using, for example, methane trifluoride (CI (F3)) as an etching gas of about 0.1 to 0.2 Torr. At a power density of about 0.2 to 0.3 W/cn+2 during depressurization,
The PSG film 17A in the lower layer part of the covering insulating film 17 is
Reactive ion etching (Il) until 0 people remain.
lE) Processed and unpierced wire bonding window 2
Form 0a. At this time, on the side wall surfaces of the etching openings 19 and the non-penetrating wire bonding windows 20a of the resist film 18, which are not subjected to strong etching, a polymer with a thickness of about 100 people is generated due to the decomposition and polymerization of the resist. It becomes a deposited film 21 and adheres.

Refer to FIG. 2(b). Next, the substrate to be processed was transferred into an ordinary barrel-type etching apparatus, and the etching process was carried out at a pressure Q of 5 Torr and a power of 300 W.
Argon (Ar) sputtering is performed for about 10 minutes. With this treatment, the polymer deposited film 21 is made of Ar particles 22.
It is struck and scattered.

At this time, the weight loss of the resist film 18 was about 1,000 people. Almost no problem.

Refer to FIG. 2(C) Next, the substrate to be processed after the sputtering process is returned to the parallel plate type etching apparatus, and is subjected to RIE processing under the same conditions as the first etching process, using the resist film 18 as a mask. A second etching process is performed to remove the PSG film 17^ exposed at the bottom of the non-penetrating wire bonding window 20a, the second interlayer insulating film 15 below it, and the CVD-3iO□ film 13 below it. is removed to complete a penetrating wire bonding window 20 that exposes the upper surface of the bonding pad I2.

It should be noted that on the surface of the bonding pad 12 exposed within the wire bonding window 20 formed in the above embodiment, almost no polymer adhesion that would interfere with wire bonding was detected by a commonly performed microscopic examination. .

Furthermore, it is desirable that the insulating film etched in the second etching process be as thin as possible in order to reduce the amount of polymer generated during the second etching and to avoid contamination on the bonding pad during the second etching. Therefore, if there is little variation in the etching gray 1- within the substrate and between substrates during etching, the second interlayer insulating film 15 can be
There is no problem even if the layers are removed by etching.

At this time, due to variations in etching rate, the first
It must be avoided that a partially penetrating wire bonding window is formed only by subsequent etching.

In the embodiments described above, the method of the present invention is used to form a wire bonding hole, but the method of the present invention can of course also be applied to the formation of a normal wiring contact window.

〔Effect of the invention〕

As described above, according to the present invention, the surface of the bonding pad exposed within the wire bonding window is a clean surface on which no deposited film of polymer or the like is formed. The bonding strength of the bonding wire made of gold or the like fixed to the substrate is sufficiently guaranteed and variations thereof are suppressed, thereby ensuring the reliability of the bonding. Therefore, the present invention is effective in improving the yield and reliability of LSIs and the like.

7 is a polymer deposited film (polymerized substance); 8 is argon (Ar) particle Not shown.

[Brief explanation of drawings]

Figures 1 (a) to (C) are process sectional views for explaining the principle of the present invention, Figures 2 (a) to (C) are process sectional views of an embodiment of the method of the present invention, and Figure 3 (a). ) to (t)) are process cross-sectional views of the conventional method. In the figure, 1 is an interlayer insulating film, 2 is a bonding pad (conductive base), 3 is a covering insulating film (insulating film), 4 is a photoresist film (resist), 5 is an etching hole, and 6 is a through bonding. 6a is an unpierced bonding window (unpierced hole), 3 4 25 −

Claims (1)

[Claims] A resist (4) is applied to the insulating film (3) on the conductive substrate (2).
) is used as a mask to form an opening (6) exposing the surface of the conductive substrate (2) by reactive ion etching. (6a) and the polymer substance (7) attached to the inner surface of the non-through hole (6a) is removed by performing argon sputtering while leaving the resist (4). a second etching step of penetrating the non-through holes (6a) of the insulating film (3) to form holes (6) by reactive ion etching using the resist (4) as a mask; A method for manufacturing a semiconductor device, comprising: