JPH11305454A - Removing method of residual substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent production of sulfur residue on a wafer and to easily remove a photoresist residue by cleaning a wafer with deposition of a residual matter on its surface metal layer by using a developer. SOLUTION: After a photoresist layer on a wafer with deposition of the photoresist on its metal layer is removed (31), the wafer is cleaned with a deionized water (32). The wafer is rotated at a high spinning rate to form a deionized water film on the wafer (33). By decreasing the spinning rate, the deionized water film is uniformly distributed on the wafer due to the surface tension of the water. Then a developer is introduced into the deionized water film, and the concn. of the developer is decreased by the deionized water film (34). Thereby the alkalinity of the developer is decreased, which suppresses possibility to form a recess on the wafer surface. The spinning rate is increased to uniformly mix the developer and the deionized water film, and then spinning speed is decreased to remove the residual matter on the metal layer (35). Then the soln. on the wafer is cleaned with water (36).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a residue, and more particularly to a method for removing a photoresist residue remaining on a metal layer after performing an etching process of the metal layer.

[0002]

2. Description of the Related Art In a conventional method of forming a metal layer,
The photoresist layer is formed and patterned by photolithography and etching. Photoresist residues form on exposed metal layers during the etching process. This residue is a type of polymer and affects the conductivity of the metal layer and wire bonding. Therefore, such residues must be removed.

FIG. 1 shows a conventional method for removing a photoresist residue after etching a pad layer, for example, an aluminum layer. As mentioned earlier, the pad layer is formed by photolithography and etching using a photoresist layer. Thereafter, a cleaning process is performed to remove photoresist polymer residues.

FIG. 1 shows a conventional cleaning process of a residue using a solvent tank immersion method. Reference numbers represent each step of the process. In step 10, a wafer is provided. In step 11, the photoresist layer is removed. In step 12, the organic solvent on the surface of the wafer is washed away. In step 13, a large amount of deionized water is used for quick down cleaning (Quic
k-down Rinsing).
In step 14, further cleaning is performed, and in step 15, water is vaporized from the wafer.

In step 11, the wafer is placed in a polymer removal tank to remove the photoresist. In step 12, the organic solvent is washed away. The polymer removal tank contains an organic solvent. Since the organic solvent cannot be washed away with water, the wafer is taken out of the polymer removal tank. The removed wafer is used for interruption (P
SR) placed in the tank. The solvent in the suspending tank can wash away the organic solvent on the surface of the wafer. This step makes the subsequent water cleaning effective.

In step 13, a quick down cleaning using a large amount of deionized water is performed by placing the wafer in a quick down cleaning machine (QDR). Whether the wafer has been completely cleaned can be determined by measuring the resistance after the cleaning. Water is vaporized by introducing isopropanol.

[0007]

The throughput is low because many steps are required to clean the wafer. The time consumed in each lot is as long as about 50 minutes. further,
The solutions in the polymer removal tank, the PSR tank and the GDR tank are susceptible to deterioration and must be replaced frequently. These result in increased manufacturing costs. After completing the cleaning process, an Auger spectroscopy (AES) test is performed on the wafer. Fig. 2 shows an example of the analysis result.
Shown in In the figure, the peak indicated by reference numeral 20 indicates that sulfur (S) remains on the wafer.
Sulfur residues affect the subsequent wire bonding process.

[0008]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a method for removing photoresist residues that can prevent the formation of sulfur residues on a wafer and easily remove the photoresist residues. . The method for removing the residue of the present invention for achieving these objects and effects includes the following steps. That is, a wafer having a metal layer on the surface and having a residue attached to the metal layer is supplied. A coating of water is formed on the wafer. The residue on the metal layer is removed by introducing the developer into the water film and mixing it uniformly.

The above general description and the following detailed description are both to be understood as specific descriptions of the present invention, and do not limit the present invention.

[0010]

DETAILED DESCRIPTION OF THE INVENTION It is known that after exposure, the photoresist layer is removed by development. In the present invention, after removing the metal layer by etching, the photoresist residue on the metal layer is removed by a developer. The metal layer is easily eroded by the alkali material. The use of 2.38% (v / v) alkaline tetramethylammonium hydroxide (TMAH) as a developer causes depressions on the surface of the metal layer. In a preferred method, the concentration of the developer is controlled and the photoresist residue removal time is appropriately selected. At this time, the photoresist residue is effectively removed without forming a depression on the surface of the metal layer.

FIG. 3 illustrates a method for diluting TMAH to remove photoresist residues on a metal layer. In the figure, each step of the cleaning process is indicated by a reference number. In step 30, a wafer is provided. In step 31, the photoresist layer on the wafer is removed. In step 32, the wafer is cleaned with deionized water. In step 33, a deionized water film is formed on the surface of the wafer. In step 34, a developer is introduced. In step 35, the residue on the metal layer is removed. In step 36,
The following cleaning process is performed.

[0012] Now, after removing the photoresist layer on the wafer in step 31, a deionized water cleaning process is performed in step 32. The wafer is spun at a high spin rate. At a high spin rate, a deionized water film is formed on the wafer (step 33). The thickness of the deionized water film affects the concentration of the developer introduced in the next step. By reducing the spin rate, the deionized water coating has a uniform distribution on the wafer due to the surface tension of the water.

In step 34, a developer is introduced into the deionized water coating. Deionized water coatings are used to dilute the developer and reduce the concentration of the developer. Thereby, the alkalinity is weakened and the possibility of forming a depression on the surface of the wafer is suppressed.

The spin speed is increased to uniformly mix the developer and the deionized water film. In step 35, the spin speed is reduced again to remove any residue on the metal layer. In step 36, the solution on the wafer is washed away with a water wash. When cleaning a wafer by the above method, the time required for each lot is only 30 minutes, and the throughput of the process is improved. on the other hand,
It is also useful to extend the life of the developer, thereby saving the cost of cleaning.

The results of using the above method to remove photoresist residue on the pad and performing atomic emission spectroscopy on the resulting pad are shown in FIG. In the figure, reference numeral 40 indicates the position of the sulfur peak. It can be seen that traces of sulfur in the profile as seen in conventional cleaning methods are not seen when the method of the present invention is employed. Consequently, subsequent wire bonding is not affected by sulfur residues.

[0016]

The features of the present invention can be summarized as follows: (1) It is possible to remove a photoresist residue by using a developing solution, and it is easy to store the developing solution. Costs can be reduced. (2) The concentration of the diluted developer can be controlled by the thickness of the deionized water film and the amount of the developer. (3) The thickness of the deionized water film can be controlled by the spin speed of the wafer. (4) Since the generation of the sulfur residue on the metal layer can be prevented, there is no influence of the sulfur residue on the subsequent wire bonding step.

Further embodiments and modifications of the present invention are:
It will be apparent to those skilled in the art from the contents disclosed in the specification. The description in the specification, especially the examples introduced herein, should be construed as illustrative of the present invention, and the scope of the present invention should be construed according to the claims.

[Brief description of the drawings]

FIG. 1 is a flow chart of a conventional method for removing photoresist residues using a solvent tank immersion method.

FIG. 2 is a profile of Auger spectroscopic analysis of a wafer surface measured after performing the conventional cleaning method shown in FIG.

FIG. 3 is a flow chart of a method of removing photoresist residues by introducing a developer according to an embodiment of the present invention.

4 is an Auger spectroscopic profile of the wafer surface measured after performing the cleaning method of the present invention shown in FIG. 3.

[Explanation of symbols]

 10 Step 10 11 Step 11 12 Step 12 13 Step 13 14 Step 14 15 Step 15 20 Peak indicating sulfur remaining on the wafer 30 Step 30 31 Step 31 32 Step 32 33 Step 33 34 Step 34 35 Step 35 36 Step 36 40 Sulfur peak location

Claims (10)

[Claims] An object of the present invention is to supply a wafer having a metal layer on a surface and having a residue adhered on the metal layer, and removing the residue by cleaning the wafer using a developing solution. Characteristic residue removal method. 2. The method of claim 1, wherein said residue is a photoresist residue. 3. The method according to claim 1, wherein said developer contains tetramethylammonium hydroxide. 4. The method according to claim 1, wherein said developer is diluted before use. 5. The method according to claim 1, wherein after removing the residue by using the developing solution, the wafer is washed with water.
Removal method. 6. A wafer having a metal layer on its surface and having a residue attached to the metal layer is supplied, a water film is formed on the wafer, and a developer is introduced into the water film. A method for removing a residue, wherein the residue is removed by uniformly mixing. 7. The method of claim 6, wherein the residue is a photoresist residue. 8. The method according to claim 6, wherein the developer contains tetramethylammonium hydroxide. 9. The concentration of the developer is about 2.38%.
7. The method according to claim 6, wherein (v / v). 10. The method according to claim 6, wherein said water film is a film of deionized water.