CN100392821C - Method for removing polymer of etching residue - Google Patents

Abstract

A method for removing etching residue polymers comprises first providing a substrate with etching residue polymers, then treating the substrate with hydrogen plasma, and then removing the polymers on the substrate by wet cleaning. The hydrogen plasma treatment step can change the chemical properties of the polymers, making them easier to be removed in the subsequent wet cleaning step.

Description

Method for removing etched residual polymer

technical field

The present invention relates to semiconductor processing, and more particularly to a method for removing etch residue polymer from a substrate.

Background technique

In the semiconductor process, the patterning process of a material layer generally includes a lithography step to form a patterned photoresist, and an etching step using the patterned photoresist as a mask thereafter. Since the photoresist is organic, after the etching step, there are usually some etching residues composed of polymers left on the substrate, which will cause many problems. For example, in the process of damascene opening, there is usually etching residue polymer formed on the sidewall of the opening. If the polymer is not properly removed, it will affect the subsequent metal filling process and thus reduce the quality of the metal interconnection.

In order to solve the problem of polymer residue, in the prior art, after the etching step, the residual polymer on the substrate is removed by a wet clean method, which uses a solution containing a surfactant to clean the substrate. However, for the damascene opening process using a metal hard mask layer, the polymer on the sidewall of the damascene opening in the central part of the substrate (wafer) is often not cleaned completely, causing the quality of the metal interconnection to be greatly affected. impact, and the yield rate of the product is greatly reduced.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to provide a method for removing etching residual polymer, which can remove the polymer on the substrate more thoroughly than the existing method.

Another technical problem to be solved by the present invention is to provide a method for more thoroughly removing the etching residual polymer in the damascene opening after the etching step of the damascene opening is completed.

The steps of the method for removing etching residue polymer in the present invention are as follows. First, a substrate is provided on which a polymer is formed, and the polymer is an etch residue. The substrate is then treated with a hydrogen-containing plasma, and the polymer on the substrate is removed with a wet clean.

In the above method, the hydrogen-containing plasma treatment step can be performed in the same etching chamber where the dry etching step is performed after the dry etching step that produces the etching residue (ie, in-situ mode), to save time and reduce the risk of substrate damage due to handling. In addition, the generation gas of the hydrogen-containing plasma may also include nitrogen to facilitate the dispersion of the polymer into the solution during subsequent wet cleaning.

The hydrogen plasma treatment step of the present invention changes the chemical properties of the polymer remaining in the etch, making it easier to remove in a subsequent wet cleaning step. Therefore, if the method of the present invention is used after the etching process of the damascene opening, the etching residual polymer in the damascene opening can be removed more completely, so that the quality of the subsequently formed metal interconnection can be maintained.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are described below in detail with accompanying drawings.

Description of drawings

Figure 1 shows an example of a common dual damascene opening process;

2 to 3 are continuation of FIG. 1 , which are flow sectional views of a method for removing etching residue polymer according to a preferred embodiment of the present invention.

Explanation of reference signs

100: Substrate

110: dielectric layer

120: hard mask layer

122, 124: middle layer

130: Patterned photoresist layer

140: Anisotropic etching

150: via

150a: via pre-opening

160: Ditch

170: Double inlay opening

180: polymer

190: Hydrogen-containing plasma

197: Wet cleaning treatment

Detailed ways

The preferred embodiment takes the polymer removal step after the etching step of the dual damascene opening as an example, which is not intended to limit the scope of the present invention.

Please refer to FIG. 1 , which shows an example of a common dual damascene opening process. In this process, a dielectric layer 110 is firstly formed on the substrate 100, and its material is, for example, silicon oxide or a silicon-based low dielectric constant material, such as HSQ, MSQ and the like. Next, a hard mask layer 120 is formed on the dielectric layer 110, and its material is, for example, silicon nitride or metal. When the material of the hard mask layer 120 is metal such as titanium nitride (TiN), intermediate layers 122 and 124 are usually formed on the upper and lower sides, such as inorganic dielectric layers, which have the functions of blocking and increasing adhesion. .

Then, a hard mask layer 120 (not shown) is defined and the exposed dielectric layer 110 is etched to form via pre-openings 150 a in the dielectric layer 110 at positions where vias are expected to be formed. Next, a patterned photoresist layer 130 for defining trenches is formed on the hard mask layer 120, and then the photoresist layer 130 is used as a mask to define the hard mask again by dry anisotropic etching. mold layer 120, and etch the exposed dielectric layer 110 to deepen the via hole pre-opening 150a into the via hole 150, and at the same time form the trench 160, while the photoresist layer 130 and the upper intermediate layer 124 are etched go. The via 150 and the trench 160 are combined into a dual damascene opening 170 , the sidewall of which is formed with an etching residue polymer 180 . In the above process, if the material of the dielectric layer 110 is a silicon-based dielectric material such as silicon oxide, the etching gas is generally a fluorine-containing gas, such as CHF ₃ , CF _{4 ,} etc., and the polymer 180 contains fluorine.

Please refer to FIG. 2 , which illustrates the hydrogen-containing plasma treatment step in the method for removing etching residue polymer according to a preferred embodiment of the present invention. As shown in Figure 2, then use hydrogen-containing plasma 190 to process the substrate 100 through the above process, the plasma generation gas used is, for example, a mixed gas of hydrogen and nitrogen, or hydrogen and an inert gas (such as argon) as a carrier gas , helium, etc.) mixed gas.

When the plasma gas is hydrogen and nitrogen, the flow rate of hydrogen gas is preferably 50-800 sccm, the flow rate of nitrogen gas is preferably 10-500 sccm, the power used is preferably 50-2000 W, and the pressure is preferably 30 mTorr-1 Torr. When the plasma gas is hydrogen and inert gas as carrier gas, the flow rate of hydrogen gas is also preferably 50-800 sccm, and the preferred ranges of power and pressure used are the same as those mentioned above, and the flow rate of carrier gas can be adjusted according to actual needs.

Referring to FIG. 3 , a wet cleaning step 197 is then performed to wash away the polymer 180 , for example, using an aqueous solution containing a surfactant. The surfactant added in this solution is, for example, quaternary ammonium salt.

In this embodiment, if the etching gas used in the etching step of the dual damascene opening 170 contains fluorine, then the polymer 180 contains fluorine. Therefore, during the treatment with hydrogen-containing plasma 190, the hydrogen implanted in the polymer 180 will form hydrogen fluoride (HF) with fluorine, which will become hydrofluoric acid during the subsequent wet cleaning process 197, which can accelerate the polymer 180. disintegration. In addition, if the plasma generation gas used includes hydrogen and nitrogen, the nitrogen-hydrogen plasma treatment forms amine groups (-NH ₂ ) on the polymer chain, making the polymer easier to disperse during subsequent wet cleaning into the solution.

example

In order to prove the effectiveness of the present invention, several examples of the above-mentioned dual damascene opening process are given below, among which there are 4 examples of the present invention that use nitrogen/hydrogen plasma to process wafers, and 4 existing examples that do not process wafers with hydrogen-containing plasma. comparative example. The processing conditions for these examples and the number of polymer defects measured after wet cleaning are listed in Table 1 below, where t in parentheses indicates the top high frequency radio frequency (HF-RF) source used to generate the plasma , and b represents the bottom (bottom) low frequency radio frequency source (LF-RF) used to generate wafer bias. In addition, the flow units of N ₂ and H ₂ are sccm.

Table 1

It can be seen from the above table 1 that the method of treating the substrate with hydrogen-containing plasma before the wet cleaning step of the present invention can indeed greatly reduce the number of polymer defects on the substrate, that is, the etching residual polymer in the mosaic opening can be more completely removed , so that the quality of the subsequently formed metal interconnection can be maintained, and the yield rate of the product can be effectively improved.

In addition, although the above-mentioned preferred embodiment takes the process of dual damascene openings as an example for illustration, the scope of the present invention is not limited thereto, and can be applied to the process of single damascene openings (vias or wiring trenches), or other effective Patterning process for etch residual polymer problem.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention is defined by the appended claims.

Claims (18)

1. method of removing the polymer of etching residue comprises:

One substrate is provided, a dielectric layer is arranged on this substrate, an opening is arranged in this dielectric layer, the metal hard mask layer in order to a patterning that defines this opening is arranged on this dielectric layer, and be formed with a polymer on the sidewall of this opening as etch residue;

Use this substrate of a hydrogen-plasma treatment; And

Use wet-cleaning method is removed this polymer on this substrate,

Wherein, aforementioned hydrogeneous plasma can change the chemical property of aforementioned polymer, makes it be removed by aforementioned wet-cleaning method.

2. the method for the polymer of removal etching residue as claimed in claim 1, wherein this hydrogen-plasma treatment step is carried out in the employed same etching chamber of a dry etching steps that produces this etch residue in the mode of original position.

3. the method for the polymer of removal etching residue as claimed in claim 1, wherein this hydrogeneous isoionic generation gas comprises hydrogen and nitrogen.

4. the method for the polymer of removal etching residue as claimed in claim 1, wherein this hydrogeneous isoionic generation gas comprise hydrogen with as the indifferent gas of carrier gas.

5. the method for the polymer of removal etching residue as claimed in claim 4, wherein this indifferent gas is argon gas or helium.

6. the method for the polymer of removal etching residue as claimed in claim 1, wherein this opening comprises a dual damascene opening.

7. the method for the polymer of removal etching residue as claimed in claim 1, wherein this polymer is fluorine-containing.

8. the method for the polymer of removal etching residue as claimed in claim 1, wherein this wet-cleaning step use one aqueous solution that contains quarternary ammonium salt is removed this polymer on this substrate.

9. method of removing the polymer of etching residue comprises:

Provide and be formed with the substrate that a pattern metal hard mask layer and is inlayed opening, wherein this is inlayed on the sidewall of opening and is formed with a polymer, this polymer is inlayed the etch residue of a dry etching steps of opening for forming this, and this dry etching steps is used fluorine-containing etching gas;

Use this substrate of a hydrogen-plasma treatment; And

Use wet-cleaning method is removed this polymer on this substrate,

Wherein, aforementioned hydrogeneous plasma can change the chemical property of aforementioned polymer, makes it be removed by aforementioned wet-cleaning method.

10. the method for the polymer of removal etching residue as claimed in claim 9, wherein this hydrogen-plasma treatment step is carried out in the employed same etching chamber of this dry etching steps in the mode of original position.

11. the method for the polymer of removal etching residue as claimed in claim 9, wherein this hydrogeneous isoionic generation gas comprises hydrogen and nitrogen.

12. the method for the polymer of removal etching residue as claimed in claim 11, wherein in the hydrogen-plasma treatment step, the flow of hydrogen is 50～800sccm, and the flow of nitrogen is 10-500sccm, used power is 50～2000W, and pressure is 30mTorr～1Torr.

13. the method for the polymer of removal etching residue as claimed in claim 9, wherein this hydrogeneous isoionic generation gas comprise hydrogen with as the indifferent gas of carrier gas.

14. the method for the polymer of removal etching residue as claimed in claim 13, wherein this indifferent gas is argon gas or helium.

15. the method for the polymer of removal etching residue as claimed in claim 13, wherein in this hydrogen-plasma treatment step, the flow of hydrogen is 50～800sccm, and used power is 50～2000W, and pressure is 30mTorr～1Torr.

16. the method for the polymer of removal etching residue as claimed in claim 9, wherein this to inlay opening be a dual damascene opening.

17. the method for the polymer of removal etching residue as claimed in claim 9, wherein this is inlayed opening and is formed in an one silica layer or the silica-based low dielectric constant material layer.

18. the method for the polymer of removal etching residue as claimed in claim 9, wherein this wet-cleaning step use one aqueous solution that contains quarternary ammonium salt is removed this polymer on this substrate.

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