KR20020002568A - Methof for strip photoresist - Google Patents

Abstract

PURPOSE: A photoresist pattern formation method is provided to effectively remove polymers without using a wet etching by simultaneously using a strip processing and a dry cleaning. CONSTITUTION: A photoresist pattern is formed on a conductive layer. The conductive layer is then etched by using the photoresist pattern as a mask. Polymers generated in the etching process and the photoresist pattern are simultaneously removed by performing a strip processing and a dry cleaning by in-situ. At this time, the strip processing and the dry cleaning are simultaneously carried out by adding CF4 gases during the strip processing of the photoresist pattern.

Description

How to remove photoresist {METHOF FOR STRIP PHOTORESIST}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor memory device, and more particularly, to a strip and dry cleaning method of a photoresist.

In general, a photoresist is used as a mask layer for forming a circuit pattern and an ion implantation region in a semiconductor manufacturing process, and the photoresist is stripped after completion of ion implantation. By using the oxygen plasma proceeds to the method of oxidizing the photoresist.

In the photoresist strip process, the ion bombardment during the ion implantation releases water vapor, a solvent, and the like to form a polymer layer which is densely composed of carbon, and the polymer layer is easily oxidized during stripping by subsequent oxygen plasma. It does not, and also shields the release of moisture and solvent contained in the lower layer at a temperature of 100 ℃ or more, the swelling of the photoresist pattern occurs, thereby changing the components of the photoresist. The altered photoresist is reconstituted with the contents of the implanted ions and reacts or sticks with the material of the underlying layer to remain unstriped to form residues or to form defects that cause the underlying layer to pit, making subsequent processing difficult and reducing the yield of the device. It will play a deadly role.

Recently, a method for removing a polymer generated when stripping a photoresist pattern has been studied in various ways.

1 is a view illustrating a method of stripping a photoresist according to the prior art, and illustrating a method of removing a polymer generated when a capacitor electrode of a memory device is formed.

As shown in FIG. 1, a ferroelectric material such as Ta ₂ O ₅ 13 is a dielectric material formed on the lower electrode 12 on the front surface of the lower structure 11 including a transistor in a capacitor forming process of a conventional memory device. In this case, a top layer 14 of polysilicon / titanium nitride (Polysilicon / TiN; hereafter abbreviated as 'Poly / TiN') or a titanium nitride (hereinafter, 'TiN'), etc. Use

As such, when the poly / TiN and TiN are used as the upper electrode 14, the polymer 16 generated after the upper electrode patterning using the photoresist 15 is wetted. chemical) and difficult to remove (see FIGS. 2 and 3).

In order to remove the polymer as described above, in the prior art, after the photoresist strip process, the polymer was removed by using megasonic during the cleaning process using a wet etchant (see FIG. 4).

Here, the megasonic cleaning method is wet cleaning using chemicals.

However, the megasonic cleaning method amplifies the efficiency reduction caused by using an intermediate medium and fine damage on the wafer or the photoresist pattern caused by chemicals, and removes the polymer due to the difference in the appearance of the polymer depending on the reticle used. To reduce process efficiency. As such, if the polymer is not completely removed, it can be a particle source for all equipment during subsequent processing, and can have a fatal effect on the equipment, especially during the thermal process.

In addition, when a polymer is present in a region where the metal contact is connected in a subsequent metal contact forming process, a problem may occur in that the contact is not opened or the deterioration of the iso device characteristic such that the contact resistance increases.

On the other hand, even if the polymer is completely removed, there is a problem that the capacitor is lifting (Lift) or fall down because the megasonic must be used in the capacitor formation process.

The present invention has been made to solve the above problems of the prior art, dry cleaning is carried out by a photoresist strip process and in-situ using a single or mixed RF source or microwave source. It is an object of the present invention to provide a photoresist strip method suitable for removing a polymer while eliminating the wet cleaning process during the upper electrode etching and the photoresist strip during the capacitor process.

1 is a view showing a method of forming a photoresist pattern according to the prior art;

2 illustrates a photoresist pattern and a polymer formed according to the prior art;

3 is a view showing a polymer remaining after wet cleaning according to the prior art,

4 is a view illustrating a capacitor in which lifting occurs during megasonic wet cleaning according to the prior art;

5 is a view showing a method of forming a photoresist pattern according to an embodiment of the present invention;

Figure 6 is a view showing a state in which the polymer after the in-situ process of the photoresist strip and dry cleaning in accordance with an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

22: lower electrode 23: ferroelectric film

24 upper electrode 25 photoresist

The photoresist removing method of the present invention for achieving the above object comprises a first step of forming a photoresist pattern on the conductive layer is completed a predetermined process; Etching the conductive layer using the photoresist pattern as an etching mask; And a third step of simultaneously removing the polymer generated during the etching of the conductive layer and the photoresist pattern, wherein the third step strips the photoresist pattern and simultaneously performs dry cleaning to remove the polymer. Characterized in that.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

5A to 5B illustrate a photoresist strip method according to an embodiment of the present invention.

As shown in FIG. 5A, after depositing an interlayer insulating layer on a semiconductor substrate, the interlayer insulating layer is selectively etched to form a contact hole, and a contact or contact plug connected to the semiconductor substrate is formed through the contact hole. do. Subsequently, the lower electrode 22 is formed on the entire surface of the lower structure 21 including the contact or contact plug, and then a ferroelectric film 23 such as Ta ₂ O ₅ , TaON, and BST is deposited to have a thickness of 10 to 500 kV using a dielectric film. Then, Poly / TiN, TiN or W is deposited on the ferroelectric layer 23 as the upper electrode 24. The above process is a conventional capacitor forming process, and may be performed by various known techniques.

Subsequently, the photoresist 25 is coated on the upper electrode 24 and patterned by an exposure and development process, and then the upper electrode 24 and the ferroelectric layer 23 are formed using the patterned photoresist 25 as an etching mask. ) And the lower electrode 22 are etched, and overetch of 30% to 200% is performed in consideration of the thicknesses of the upper electrode 24 and the ferroelectric layer 23.

Observation with a scanning electron microscope after such a photoresist patterning, it can be seen that a large amount of polymer 26 is formed on the sidewalls of the photoresist 25, the upper electrode 24, the ferroelectric film 23 and the lower electrode 22. have.

As shown in FIG. 5B, dry cleaning is performed with the photoresist strip and in-situ. The dry cleaning may be performed before the photoresist strip, and conversely, the photoresist strip may be performed after the dry cleaning.

During the dry cleaning, one of the RF source and the microwave source is selected, or the RF source and the microwave source are mixed to form a CF ₄ / O ₂ / N ₂ plasma. Subsequently, the polymer 26 formed on sidewalls of the photoresist pattern 25, the upper electrode 24, the ferroelectric layer 23, and the lower electrode 22 is removed using the CF ₄ / O ₂ / N ₂ plasma. . Here, a small amount of the CF ₄ gas serves to remove the polymer 26, and may be NF ₃ .

When using the RF source, using 200W to 500W of RF power, the gas composition ratio of CF ₄ to 5% to 30% of the total gas, helium (He), or to dilute the CF ₄ gas Argon (Ar) gas is added. In addition, the process pressure is 200 mTorr-800 mTorr.

On the other hand, when using a microwave source, the power of 1200W to 2000W is used, the gas composition ratio of CF ₄ is adjusted to 1% to 10% of the total gas, and the pressure during the process is 700mTorr to 2000mTorr.

Then, dry cleaning may be performed without using any one of the O ₂ / N ₂ , and the strip and dry cleaning of the photoresist pattern may be performed in the same process by adding CF ₄ gas in the subsequent strip of the photoresist pattern. have.

As one embodiment of the present invention, RF / Microwave type Isotropic Etcher from Gasonics, a commercial device, is used.

First, when the strip of photoresist pattern proceeds to the previous process, the photoresist pattern strip is performed for 70 seconds with 1700W microwave power and 2800 O ₂ / 125N ₂ plasma at a pressure of 950mTorr and a temperature of 270 ° C. Dry cleaning is performed for 20 seconds with a microwave power of 1700 W and a 2000 O ₂ / 50CF ₄ plasma at a pressure of 950 mTorr and a temperature of 250 ° C. to remove polymer 26.

Then, dry cleaning is carried out for 30 seconds with 420W RF power and 400O ₂ / 50CF ₄ plasma at a pressure of 300mTorr and a temperature of 70 ° C. And a microwave power of 1700 W and 280O ₂ / 125N ₂ plasma at a temperature of 270 ° C. for 70 seconds.

When the dry cleaning is performed simultaneously with the strip of the photoresist pattern with the above recipe, the polymer can be removed without the wet cleaning process.

6 is a view showing a state in which the polymer is removed according to an embodiment of the present invention, it can be seen that the polymer was removed without lifting or falling of the capacitor.

As described above, in the present invention, stability to subsequent thermal processes is secured, and the polymer in the region where the metal contact is connected can be removed to prevent the contact from being opened or to increase the contact resistance due to the polymer. .

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention can effectively remove the polymer by dry cleaning in situ and strip of the photoresist pattern without the usual wet cleaning, thereby improving the product yield by improving the characteristics of the device and securing process stability. It can be effective. In addition, since the wet cleaning is not performed, the amount of the wet etchant is reduced, thereby reducing the manufacturing cost.

Claims (16)

In the method of forming a photoresist pattern of a semiconductor device, A first step of forming a photoresist pattern on the conductive layer where the predetermined process is completed; Etching the conductive layer using the photoresist pattern as an etching mask; And A third step of simultaneously removing the polymer generated during the etching of the conductive layer and the photoresist pattern Photoresist removal method characterized in that it comprises a. The method of claim 1, The third step, And stripping the photoresist pattern and simultaneously performing dry cleaning. The method of claim 1, The third step, Stripping the photoresist pattern; And Dry cleaning to remove the polymer Photoresist removal method characterized in that it comprises a. The method of claim 1, The third step, Performing dry cleaning to remove the polymer; And Stripping the photoresist pattern Photoresist removal method characterized in that it comprises a. The method of claim 1, The third step, And stripping the photoresist pattern to dry cleaning in the same step as the strip of the photoresist pattern by adding CF ₄ gas. The method according to any one of claims 2 to 5, The dry cleaning is, And removing the polymer by using a CF ₄ / O ₂ / N ₂ plasma by an RF source. The method of claim 6, And the power of said RF source is 200500W. The method of claim 6, The CF ₄ gas has a composition ratio of 5% to 30% in the CF ₄ / O ₂ / N ₂ plasma. The method of claim 6, Dry cleaning using the RF source is a photoresist removing method characterized in that under a pressure of 200mTorr ~ 800mTorr. The method of claim 6, And any one of helium and argon is used to dilute the CF ₄ gas in the CF ₄ / O ₂ / N ₂ plasma. The method according to any one of claims 2 to 5, The dry cleaning is, And removing the polymer by using a CF ₄ / O ₂ / N ₂ plasma by a microwave source. The method of claim 11, And a power source of the microwave source is 1200 to 2000W. The method of claim 11, The CF ₄ / O ₂ / N ₂ plasma of the CF ₄ gas is how to remove the photoresist, it characterized in that it has a composition ratio of 1-10%. The method of claim 11, Dry cleaning using the microwave source is a photoresist removing method characterized in that under a pressure of 700mTorr ~ 2000mTorr. The method according to any one of claims 2 to 5, The dry cleaning is, And removing the polymer using a CF ₄ / O ₂ / N ₂ plasma mixed with an RF source and a microwave source. The method according to any one of claims 2 to 5, The dry cleaning method of removing the photoresist, characterized in that for removing the polymer using a CF ₄ / O ₂ or CF ₄ / N ₂ plasma.