CN102651304A

CN102651304A - Method for improving wet-method metal-etching process

Info

Publication number: CN102651304A
Application number: CN2011100433112A
Authority: CN
Inventors: 周颖; 丛茂杰
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2011-02-23
Filing date: 2011-02-23
Publication date: 2012-08-29

Abstract

The invention discloses a method for improving a wet-method metal-etching process. The method is realized by adding a photoetching dry-method etching step before a metal wet-method etching step and after a photoetching step on the basis of the current wet-method metal-etching process flow. The surface shape and the hydrophobicity of a photoresist can be effectively improved by the method, the surface tension of a liquid wet-method etching chemical for etching metal is reduced, sides and corners of the photoresist are round, the stripping of a product generated during etching is facilitated, the liquid wet-method etching chemical is more fully contacted with the etched metal, and the aims of uniform etching and reduction of metal residue are fulfilled.

Description

Be used to improve the method for wet etching smithcraft

Technical field

The present invention relates to the method for the wet etching smithcraft in a kind of semiconductor fabrication process, particularly relate to a kind of method that is used to improve the wet etching smithcraft.

Background technology

The wet etching smithcraft is compared with dry etching, has advantages such as cost is low, flux big, no electric charge accumulation, no physics damage, therefore, and extensive use in semiconductor technology.But existing wet etching smithcraft is not done special processing to the pattern of photoresist, after photoetching, directly carries out wet etching, thereby metal residual is arranged in this technology easily, and its reason is specific as follows:

(1) the photoresist sidewall is more straight, stops that easily product comes off, and product is deposited in the metal surface, stops etching;

(2) photoresist is hydrophobicity, and the etching soup is very big in the surface tension that is coated with film, causes soup to be difficult to fully and metal layer contacting, causes etching inhomogeneous, produces residual.

Wherein, in the existing wet etching smithcraft, the sketch map behind the typical metal lithographic is as shown in Figure 1, and the sketch map behind the typical wet etching metal is as shown in Figure 2.

Therefore; Owing to receive photoresist surface topography and hydrophobicity influence in the existing wet etching smithcraft; The etching soup is difficult to soak into fully the metal that is etched, and the product of etching also is deposited on the metal surface easily and stops etching, and this has all caused the generation of metal residual.Especially in the power device manufacturing process, more than 3 μ m, existing metal wet etching more is easy to generate metal residual to metal layer thickness usually.

Summary of the invention

The technical problem that the present invention will solve provides a kind of method that is used to improve the wet etching smithcraft, with effective reduction metal residual.

For solving the problems of the technologies described above, the method that is used to improve the wet etching smithcraft of the present invention is on existing wet etching smithcraft process base, realizes through increasing the photoresist dry etch step before the metal wet etching after photoetching.

Said photoresist dry etching is the method that adopts dry ashing (ASH), with the photoresist partial etching.Wherein, this partial etching can the photoresist etching that 2 μ m are thick be thinned to 1 μ m.

In addition, in this photoresist dry etch step, make the photoresist edge become circle or ellipse.

The method that is used to improve the wet etching smithcraft of the present invention, concrete steps comprise:

(1) resist coating in the metal surface;

(2) exposure, development;

(3) utilize dry etching that photoresist is carried out partial etching;

(4) wet etching metal.

The present invention is through on existing wet etching smithcraft process base; Before wet etching earlier with ASH with the photoresist partial etching; Can effectively improve the surface configuration and the hydrophobic proterties of photoresist, thereby reduce the surface tension of the used wet etching soup of etching metal; And make the photoresist corner become mellow and full, help the etching product and break away from, thus make the wet etching soup more fully with the Metal Contact that is etched, reach even etching, reduce the purpose of metal residual.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed explanation:

Fig. 1 is the sketch map behind the metal lithographic in the typical wet etching smithcraft;

Fig. 2 is the sketch map behind the etching metal in the typical wet etching smithcraft;

Fig. 3 is that metal surface of the present invention has been coated with the sketch map behind the photoresist;

Fig. 4 is the sketch map after resist exposure of the present invention, the development;

Fig. 5 is that the dry etching that utilizes of the present invention carries out the sketch map behind the partial etching to photoresist;

Fig. 6 is the sketch map behind the wet etching metal of the present invention.

Embodiment

Present embodiment is an example with the metal etch of silicon chip, and the method that is used to improve the wet etching smithcraft of the present invention is described.Wherein, this silicon chip is to be made up of metal level (like this metal level can be aluminium/copper, aluminium/silicon/copper material) and dielectric layer (like boron-phosphorosilicate glass BPSG/ non-impurity-doped silex glass USG).

The method that is used to improve the wet etching smithcraft of present embodiment, its concrete steps are following:

(1) the positive glue of resist coating in the metal surface of silicon chip, the result is as shown in Figure 3;

(2) through photo-etching machine exposal, develop then, the result is as shown in Figure 4;

(3) utilize dry ashing (ASH) etching that photoresist is carried out partial etching, make the thick photoresist etching of 2 μ m be thinned to 1 μ m, and make the photoresist edge become circle or ellipse, the result is as shown in Figure 5;

Behind the wet etching metal of (4) employing routine, the result is as shown in Figure 6.

Operate according to above-mentioned steps, can make the wet etching soup more fully with Metal Contact, reach even etching, reduce the effect of metal residual.

Claims

1. method that is used to improve the wet etching smithcraft, it is characterized in that: said method is on wet etching smithcraft process base, realizes through increasing the photoresist dry etch step before the metal wet etching after photoetching.

2. the method that is used to improve the wet etching smithcraft as claimed in claim 1 is characterized in that: said photoresist dry etching is the method that adopts dry ashing, with the photoresist partial etching.

3. the method that is used to improve the wet etching smithcraft as claimed in claim 2 is characterized in that: said partial etching is that the photoresist etching that 2 μ m are thick is thinned to 1 μ m.

4. the method that is used to improve the wet etching smithcraft as claimed in claim 1 is characterized in that: in the said photoresist dry etch step, make the photoresist edge become circle or ellipse.

5. the method that is used to improve the wet etching smithcraft as claimed in claim 1 is characterized in that: the concrete steps of said method comprise:

(1) resist coating in the metal surface;

(2) exposure, development;

(3) utilize dry etching that photoresist is carried out partial etching;

(4) wet etching metal.