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Title:
SOLUTION FOR REMOVAL OF POST DRY ETCHING RESIDUES
Document Type and Number:
WIPO Patent Application WO/2004/067692
Kind Code:
A1
Abstract:
A cleaning solution for removing post dry etching residues, the cleaning solution comprising sulfuric acid, hydrogen peroxide, a fluorine-containing compound and a surfactant. The percentage of sulfuric acid is from 1 wt% to 30wt%, the concentration of the fluorine-containing compound ranges from 1 ppm to 10000 ppm, the percentage of hydrogen peroxide is from 0.lwt% to 15wt%, and the concentration of the surfactant ranges from 1 ppm to 10000 ppm.

Inventors:
TU SHENG-HUNG (CN)
SHEEN WEN-SHOEI (CN)
SHEN KWO-HUNG (CN)
TING JACK (CN)
LI YING-HAO (CN)
LU CHIH-PENG (CN)
Application Number:
PCT/IB2003/001720
Publication Date:
August 12, 2004
Filing Date:
May 02, 2003
Export Citation:
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Assignee:
MERCK KANTO ADVANCED CHEMICAL (CN)
TU SHENG-HUNG (CN)
SHEEN WEN-SHOEI (CN)
SHEN KWO-HUNG (CN)
TING JACK (CN)
LI YING-HAO (CN)
LU CHIH-PENG (CN)
International Classes:
C11D3/02; C11D3/39; C11D11/00; (IPC1-7): C11D3/39; C09K13/08
Foreign References:
CN1227279A1999-09-01
CN1362467A2002-08-07
US5326490A1994-07-05
Attorney, Agent or Firm:
BEIJING ZHONGYUAN HUAHE INTELLECTUAL PROPERTY AGENT CO., LTD. (Huibin Building No.8 Beichendong Stree, Chaoyang District Beijing 1, CN)
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Claims:
WHAT IS CLAIMED IS:
1. A cleaning solution for removing post dry etching residues, comprising: sulfuric acid, hydrogen peroxide, a fluorinecontaining compound and a surfactant.
2. The cleaning solution of claim 1, wherein sulfuric acid has a percentage of lwt% to 30wt%.
3. The cleaning solution of claim 1, wherein the fluorinecontaining compound is selected from the following group consisting of hydrofluoric acid, ammonium fluoride, ammonium dihydrogen fluoride, hexafluorosilicate and fluoroboric acid (HBF4).
4. The cleaning solution of claim 1, wherein the fluorinecontaining compound has a concentration ranging from 1 ppm to 10000 ppm.
5. The cleaning solution of claim 1, wherein hydrogen peroxide has a percentage of O. lwt% to l5wt%..
6. The cleaning solution of claim 1, wherein the surfactant is a compound selected from the following group consisting of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates, acetates, and fluoride derivatives of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates and acetates.
7. The cleaning solution of claim 6, wherein the surfactant has a concentration ranging from 1 ppm to 10000 ppm.
8. A cleaning solution for removing post dry etching residues, comprising: sulfuric acid, hydrogen peroxide, hexafluorosilicate and a surfactant, wherein the surfactant is a compound selected from the following group consisting of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates, acetates and fluoride derivatives of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates and acetates.
9. The cleaning solution of claim 8, wherein sulfuric acid has a percentage of lwt% to 30wt%.
10. The cleaning solution of claim 8, wherein hexafluorosilicate has a concentration ranging from 1 ppm to 10000 ppm.
11. The cleaning solution of claim 8, wherein hydrogen peroxide has a percentage of 0. lwt% to 15wt%..
12. The cleaning solution of claim 8, wherein the surfactant has a concentration ranging from 1 ppm to 10000 ppm.
13. A cleaning solution for removing post dry etching residues, comprising: sulfuric acid, hydrogen peroxide, fluoroboric acid (HBF4) and a surfactant, wherein the surfactant is a compound selected from the following group consisting of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates, acetates and fluoride derivatives of aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates and acetates.
14. The cleaning solution of claim 13, wherein sulfuric acid has a percentage of lwt% to 30wt%.
15. The cleaning solution of claim 13, wherein fluoroboric acid (HBF4) has a concentration ranging from 1 ppm to 10000 ppm.
16. The cleaning solution of claim 13, wherein hydrogen peroxide has a percentage of O. lwt% to 15wt%..
17. The cleaning solution of claim 13, wherein the surfactant has a concentration ranging from 1 ppm to 10000 ppm.
18. A cleaning method for cleaning a wafer after dry etching, comprising: providing the wafer having a patterned conductive layer, wherein a polymer residue exists on a surface of the patterned conductive layer, since the pattern conductive layer is treated by ashing and dry etching; and cleaning the wafer to remove the polymer residue by using a cleaning solution comprising sulfuric acid, hydrogen peroxide, a fluorinecontaining compound and a surfactant, wherein a percentage of sulfuric acid is from lwt% to 30wt%, a concentration of the fluorinecontaining compound ranges from 1 ppm to 10000 ppm, a percentage of hydrogen peroxide is from 0. lwt% to 15wt%, and a concentration of the surfactant ranges from 1 ppm to 10000 ppm.
19. The cleaning method of claim 18, wherein the step of cleaning the wafer by using the cleaning solution includes performing a step selected from the following group consisting of a step of soaking the wafer into the cleaning solution, a step of spraying the cleaning solution onto the wafer and a step of spraying the cleaning solution onto the wafer and spinning the wafer (spin etching).
20. The cleaning method of claim 19, wherein a temperature of the step of cleaning the wafer by using the cleaning solution is between 0°C to 90°C.
21. The cleaning method of claim 19, wherein a spray pressure is 0. 52. 0 atm. for the step of spraying the cleaning solution onto the wafer or the step of spraying the cleaning solution onto the wafer and spinning the wafer (spin etching).
22. The cleaning method of claim 19, wherein a spin speed is 05000 rpm, for the step of spraying the cleaning solution onto the wafer and spinning the wafer (spin etching).
Description:
SOLUTION FOR REMOVAL OF POST DRY ETCHING RESIDUES

BACKGROUND OF THE INVENTION Field of Invention The present invention relates to a cleaning process for the semiconductor fabrication. More particularly, the present invention relates to a cleaning solution for removing the post dry etching residues.

Description of Related Art The etching process is regarded as one of the most important processes in the semiconductor fabrication, since the layout pattern of the mask is generally transferred to the underlying material layer through lithography and etching. The patterned material layer can be a layer of silicon dioxide, silicon nitride, polysilicon, aluminum alloy or phosphosilicate glass (PSG), if taking the CMOS fabrication process as an example. That is, almost all kinds of materials have to go through deposition, lithography and etching processes during the semiconductor fabrication processes.

The process for patterning the conductive layer is described as follows. After forming a silicon oxide layer and a conductive layer (such as, polysilicon or other metal materials, like aluminum), a patterned photoresist layer is formed on the conductive layer as an etching mask and dry etching is performed to etch the exposed conductive layer to form the conductive pattern. Afterwards, the photoresist layer is removed.

In the above process for patterning the conductive layer, the etching gases usually includes carbon, chlorine or oxygen, which may react with the photoresist layer or the conductive layer to form polymer residues on sidewalls of the photoresist layer or the conductive layer. The remained polymer residues not only interrupt the following

processes but also deteriorate the quality of the conductive layer. Therefore, after removing the photoresist layer by ashing, a cleaning process is usually applied to remove the polymer residues remained on the surface of the conductive layer after dry etching.

In the conventional cleaning process for removing the polymer residues, the wafer is soaked in the hot sulfuric acid solution. However, the polymer residues on the sidewalls can not be completely removed by treating with ozone ashing and hot sulfuric acid. The treated wafer is subsequently soaked in the diluted hydrofluoric acid solution for a short time. The soaking time has to be carefully controlled in order to prevent etching of the oxide layer on the wafer. Although it is possible that the polymer residues can be removed with specific cleaning solutions, the conventional cleaning process is complex and causes considerable inconvenience. Therefore, it is desirable that a suitable cleaning solution for removing residues after dry etching is developed.

SUMMARY OF THE INVENTION The present invention provides a cleaning solution for removing the post dry etching residues, which can effectively remove the polymer residues remained on sidewalls of the conductive pattern after dry etching.

As embodied and broadly described herein, the present invention provides a cleaning solution for removing post dry etching residues. The cleaning solution comprises at least sulfuric acid, hydrogen peroxide, a fluorine-containing compound and a surfactant. For the cleaning solution, the percentage of sulfuric acid is from lwt% to 30wt% and the percentage of hydrogen peroxide is from O. lwt% to 15wt%. The fluorine-containing compound can be hydrofluoric acid, ammonium fluoride,

ammonium dihydrogen fluoride, hexafluorosilicate or fluoroboric acid (HBF4), with a concentration ranging from 1 ppm to 10000 ppm. The surface surfactant can be a cation surfactant, an anion surfactant or a non-ion type surfactant, in a concentration ranging from 1 ppm to 10000 ppm.

The present invention further provides a cleaning method for cleaning the wafer after dry etching. A wafer having a patterned (etched) conductive layer is provided.

There are polymer residues remained on the surface of the patterned conductive layer. A cleaning solution comprising at least sulfuric acid, hydrogen peroxide, a fluorine- containing compound and a surfactant is used to clean the wafer, in order to remove the polymer residues.

By using the cleaning solution of the present invention, the polymer residues on the surface of the conductive pattern can be completely removed without damaging the conductive pattern, thus increasing the process window and the production yield, and enhancing the cleaning efficiency. Moreover, it decreases the consumption of solvents and reduces the cost.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,

Fig. 1 shows the scanning electron microscope image of the conductive pattern before treating with the cleaning solution; Fig. 2 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Example 1; Fig. 3 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Example 2; Fig. 4 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Example 3; Fig. 5 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Example 4; Fig. 6 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Example 5; and Fig. 7 shows the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of the Comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a cleaning solution for removing post dry etching residues. The cleaning solution comprises at least sulfuric acid, hydrogen peroxide, a fluorine-containing compound and a surfactant. For the cleaning solution, the percentage of sulfuric acid is from lwt% to 30wt% and the percentage of hydrogen peroxide is from O. lwt% to 15wt%. The fluorine-containing compound can be hydrofluoric acid, ammonium fluoride, ammonium dihydrogen fluoride, hexafluorosilicate or fluoroboric acid (HBF4), with a concentration ranging from 1 ppm

to 10000 ppm. The surface surfactant has a concentration ranging from 1 ppm to 10000 ppm.

The surfactant can be, for example, aliphatic (fatty) acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, succinates, fatty acid amides, phosphates, sulfates, sulfonates or acetates, or fluoride derivatives of the aforementioned compounds.

The cleaning solution of the present invention can effectively remove the polymer residues remained on sidewalls of the conductive pattern after dry etching, without increasing complexity of the fabrication process.

In order to illustrate the present invention in further details, a few samples of the cleaning solution of the present invention, comprising sulfuric acid, hydrogen peroxide, a fluorine-containing compound and a surfactant are produced, as examples for demonstrating the present invention.

Example 1: sample 1 includes 12wt% sulfuric acid, 2. 5wt% hydrogen peroxide, ammonium fluoride in a concentration of 50 ppm and surfactant A in a concentration of 50 ppm. Surfactant A is fluoro octyl ammonium sulfonate.

Example 2: sample 2 includes 7. 5wt% sulfuric acid, 2. 5wt% hydrogen peroxide, ammonium dihydrogn fluoride in a concentration of 50 ppm and surfactant B in a concentration of 300 ppm. Surfactant B is alkylnaphthalene sulfonic acid.

Example 3: sample 3 includes 7. 5wt% sulfuric acid, 2. 5wt% hydrogen peroxide and surfactant B in a concentration of 300 ppm. Surfactant B is alkylnaphthalene sulfonic acid.

Example 4: sample 4 includes 7. 5wt% sulfuric acid, 2. 5wt% hydrogen peroxide, hexafluorosilicate in a concentration of 250 ppm.

Example 5: sample 5 includes 7. 5wt% sulfuric acid, 2. 5wt% hydrogen peroxide, hexafluorosilicate in a concentration of 50 ppm and surfactant C in a concentration of 150 ppm. Surfactant C is nonyl phenol-6-polyoxyethylene ammonium sulfate.

Comparative: the comparative sample includes 7. 5wt% sulfuric acid, 2. 5wt% hydrogen peroxide and hydrofluoric acid in a concentration of 100 ppm.

Several wafers are provided for the test. After forming a silicon oxide layer and a conductive layer (such as, polysilicon or other metal materials, like aluminum), a patterned photoresist layer is formed on the conductive layer as an etching mask and dry etching is performed to etch the exposed conductive layer to form the conductive pattern. Afterwards, the photoresist layer is removed and the wafer (substrate) with the conductive pattern (by dry etching) is obtained.

The wafers are then respectively cleaned with the above six sample solutions, by soaking, spraying or spin etching, to remove the post dry etching residues remained on sidewalls of the conductive pattern. The temperature of the cleaning process is controlled between about 0°C to 90°C. For cleaning by spraying or spin etching, the spray pressure is 0. 5~2. 0 atm. and the spin speed is 0~5000 rpm.

The wafers (substrate) having the post dry etching conductive pattern are individually cleaned with the cleaning (sample) solutions of Example 1,2, 5 and Comparative by soaking. Using the cleaning (sample) solutions of Example 2,3, the wafers (substrate) having the post dry etching conductive pattern are individually cleaned by spraying onto the surface of the substrate.

Differences between the cleaning effects for the cleaning solutions of Example 1-5 and Comparative are discussed as follows.

Fig. 1 shows the scanning electron microscope image of the conductive pattern before treating with the cleaning solution. As shown in Fig. 1, there are polymer residues remained on the surface of the conductive pattern.

Figs. 2-7 show the scanning electron microscope image of the conductive pattern after treating with the cleaning solution of Examples 1-5 and the Comparative example.

As shown in Fig. 2, the polymer residues on the top surface of the conductive pattern has been completely removed, while some polymer residues still remain on the side surfaces (sidewalls) of the conductive pattern. Referring to Fig. 3 (Example 2), the polymer residues on the whole surface of the conductive pattern has been completely removed, which indicates that the concentration of the surfactant has great influence on the removal of polymer residues on the side surfaces of the conductive pattern.

From Fig. 4 (Example 3), it shows that the removal of polymer residues on the side surfaces of the conductive pattern is not complete. Therefore, the fluorine- containing compound is required for removing polymer residues.

From Fig. 5 (Example 4), it shows that the majority of the polymer residues on the surface of the conductive pattern are removed.

From Fig. 6 (Example 5), it shows that the removal of polymer residues on the surface of the conductive pattern is complete.

In Fig. 7 (Comparative), it shows that the conductive pattern is damaged (corroded) by the cleaning solution, although the polymer residues on the surface of the conductive pattern is completely removed.

The present invention provides a cleaning solution for removing post dry etching residues. The cleaning solution comprises at least sulfuric acid, hydrogen peroxide, a fluorine-containing compound and a surfactant. For the cleaning solution, the

percentage of sulfuric acid is from lwt% to 30wt% and the percentage of hydrogen peroxide is from O. lwt% to 15wt%. The fluorine-containing compound can be hydrofluoric acid, ammonium fluoride, ammonium dihydrogen fluoride, hexafluorosilicate or fluoroboric acid (HBF4), with a concentration ranging from 1 ppm to 10000 ppm. The surfactant has a concentration ranging from 1 ppm to 10000 ppm.

Because the concentration of the fluorine-containing compound is low, the cleaning solution of the present invention can remove the polymer residues on the surface of the conductive pattern completely without damaging the conductive pattern. Therefore, using the cleaning solution of the present invention decreases the consumption of solvents and thus reduces the cost. Moreover, it enhances the cleaning efficiency and increases the process window and the production yield.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.