KR20000042479A - Method for fabricating capacitor of semiconductor device - Google Patents

Abstract

PURPOSE: A method for fabricating a capacitor of a semiconductor device is provided to improve property and reliability of the device by preventing damage of a lower electrode and removing polymer and etching remains without lifting of a storage electrode pattern. CONSTITUTION: A method for fabricating a capacitor of a semiconductor device comprises forming a capacitor with high dielectric material and etching a layer for a lower electrode, a diffusion barrier and an adhesive layer, wherein polymer and etching remains are cleaned out by using a deionized water and tetramethyl-ammonium hydroxide mixture.

Description

Capacitor Formation Method of Semiconductor Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a capacitor of a semiconductor device. In particular, the polymer and the etching residue generated during the etching process of a capacitor using a high dielectric material are deionized water and tetramethyl-ammonium hydroxide. By using a mixed solution of TMAH (hereinafter referred to as TMAH), the lower layer is prevented from being damaged, thereby eliminating the lifting phenomenon of the pattern, thereby improving the characteristics and reliability of the device and improving the yield.

In general, as the high integration of semiconductor devices increases, a fixed capacitance of a capacitor is required. To solve this problem, a method of using a material having a high dielectric constant of a capacitor, reducing the thickness of a dielectric film, or increasing the surface area of a charge storage electrode has emerged. In order to solve this problem, attempts have been made to apply a material having a high dielectric constant.

As the material having a high dielectric constant, a high dielectric material and a ferroelectric material are used. The ferroelectric material has a dielectric constant of several hundreds to thousands at room temperature and is thinned into a ferroelectric having two stable residual polarization states. It is applied to FeRAM device development which is a nonvolatile memory which stores data even in this off state.

Hereinafter, a method of forming a capacitor of a semiconductor device according to the prior art will be described with reference to the accompanying drawings.

FIG. 1 is a SEM photograph showing that a polymer remains after etching a lower electrode by a method of forming a capacitor of a semiconductor device according to the prior art, and FIG. 2 is an upper part etched by a method of forming a capacitor of a semiconductor device according to the prior art. SEM photo of the electrode.

First, an interlayer insulating film having a storage electrode contact plug is formed on a semiconductor substrate on which a predetermined lower structure is formed.

Next, a Ti film as an adhesive layer and a TiN film as a diffusion barrier layer are formed on the structure, and a thin film for lower electrodes is formed on the diffusion barrier layer. In this case, a Pt film, an Ir film, a Ru film, an IrO ₂ film, and a RuO ₂ film may be used as the lower electrode thin film.

Next, the lower electrode thin film, the diffusion barrier and the adhesive layer are etched using the storage electrode mask to form the lower electrode, the diffusion barrier pattern and the adhesive layer pattern.

Thereafter, a washing process for removing the polymer and residue (ⓐ) generated by the etching process is performed.

Next, a dielectric film and an upper electrode thin film are formed over the entire surface.

In this case, the dielectric layer may be formed of BST ((Ba _1-x Sr _x ) TiO ₃ ), PZT (Pb (ZrTi _1-x ) O ₃ ) or Y-1 (SrBi ₂ Ta ₂ O ₉ ), and the upper electrode The thin film is formed using the same material as the lower electrode thin film.

Next, the thin film and the dielectric film for the upper electrode are etched by an etching process using the upper electrode mask.

Thereafter, a washing process for removing the polymer and residue (ⓑ) generated by the etching process is performed.

As described above, in the method of forming a capacitor of a semiconductor device according to the related art, residues and polymers are generated after an etching process of a lower electrode, a high dielectric film, and an upper electrode formed of a high dielectric material, as shown in FIGS. 1 and 2. Since the etching residue and the polymer may be generated as particles in a subsequent process and cause contamination, a method of performing a washing process using a solvent having a hydroxylamine as a main component is used. Chemically penetrating the diffusion barrier and the adhesive layer, there is a problem that the storage electrode pattern is lifted when a long time treatment or ultrasonic or the like is used.

The present invention is to solve the problems of the prior art, by using a mixed solution of deionized water and TMAH in the polymer and the etching residue generated during the etching process of the lower electrode and the upper electrode in the capacitor manufacturing process using a high dielectric material It is an object of the present invention to provide a method for forming a capacitor of a semiconductor device which prevents damage to a lower layer by removing the polymer and etch residue without lifting a storage electrode pattern, thereby improving device characteristics and reliability.

1 is a SEM photograph showing that a polymer remains after etching a lower electrode by a method of forming a capacitor of a semiconductor device according to the prior art.

2 is a SEM photograph of an upper electrode etched by a method of forming a capacitor of a semiconductor device according to the prior art.

3 is a SEM photograph of a lower electrode etched by a method of forming a capacitor of a semiconductor device according to the present invention.

Figure 4 is a SEM photograph after cleaning the upper electrode etched by the method of forming a capacitor of the semiconductor device according to the present invention.

In order to achieve the above object, a method of forming a capacitor of a semiconductor device according to the present invention,

In the method of forming a capacitor of a semiconductor device using a high dielectric material,

And a step of washing the polymer and the etching residue generated after the etching process of the capacitor formed of the high dielectric material using a mixed solution of deionized water and TMAH.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is an SEM photograph of a lower electrode etched by the method of forming a capacitor of a semiconductor device according to the present invention, and FIG. 4 is an SEM photograph of the upper electrode etched by the method of forming a capacitor of a semiconductor device according to the present invention. .

First, a MOSFET isolation layer (not shown) and a gate insulating layer (not shown) are formed on a semiconductor substrate (not shown), and a MOS field effect transistor including a gate electrode (not shown) and a source / drain electrode (not shown) is provided. And an interlayer insulating film (not shown) having a storage electrode contact plug on the structure.

Next, an adhesive layer is formed on the structure with a Ti film and a diffusion barrier is formed on the TiN film so that the lower electrode thin film formed in a subsequent process is well adhered to the interlayer insulating film.

Next, a thin film for lower electrode is formed on the diffusion barrier layer, and is formed using a Pt film, an Ir film, a Ru film, an Iro ₂ film, or a RuO ₂ film.

Next, a photoresist pattern (not shown) is formed on the lower electrode thin film to protect a portion intended as the lower electrode, and the thin film for diffusion, the diffusion barrier and the adhesive layer are sequentially formed using the photoresist pattern as an etching mask. After etching, the photoresist pattern is removed. In this case, an etching residue and a polymer are formed by the etching process.

Next, a washing process is performed to remove the etch residue and the polymer.

The cleaning process is performed for 1 to 10 minutes using 10 to 70 ° C., preferably 60 ° C. deionized water and 1 to 99% and preferably 2.38% of TMAH mixed solution, in which etching to the lower adhesive layer and the diffusion barrier is difficult. Preferably it is carried out for 5 minutes. At this time, the process temperature of the cleaning process and the concentration of the mixed solution change the removal rate of the etching residue and the polymer, and the removal capacity does not change.

In order to perform the cleaning process more effectively, mechanical methods such as ultrasonic, megasonic, or stirling bars are used together.

As shown in FIG. 3, the etch residues and the polymers existing between the lower electrodes are completely removed, and the damage of the lower layer does not occur, so that the lifting of the lower electrode does not occur.

Next, a dielectric film and an upper electrode thin film are formed over the entire surface. In this case, the dielectric layer may be BST ((Ba _1-x Sr _x ) TiO ₃ ), which is a high dielectric material, or Y-1 (SrBi ₂ Ta ₂ O ₉ ), which is a ferroelectric material, or PZT (Pb (Zr _x Ti _1-x ) O. ₃ ) using. A thin film for the upper electrode is formed, but is formed using the same material as the lower electrode thin film.

Next, the thin film for the upper electrode is etched by an etching process using the upper electrode mask. Etch residues and polymers generated by the etching process are subjected to the same cleaning process as the cleaning process after the lower electrode forming process to completely remove the etching residues and polymers as shown in FIG. 4.

As described above, in the method of forming a capacitor of a semiconductor device according to the present invention, in the method of forming a capacitor using a high dielectric material, the polymer and the etching residue generated after the lower electrode or the upper electrode are etched with deionized water and TMAH solution. Therefore, the lower adhesive layer and the diffusion barrier are lost during the cleaning process, thereby preventing the lower electrode and the upper electrode from being lifted, thereby improving the characteristics and reliability of the device.

Claims (4)

In the method of forming a capacitor of a semiconductor device using a high dielectric material, And cleaning the polymer and the etching residue generated after the etching process of the capacitor formed of the high dielectric material using a mixed solution of deionized water and TMAH. The method of claim 1, The cleaning process is a capacitor forming method of a semiconductor device, characterized in that performed after etching the lower electrode and the upper electrode. The method of claim 1, The cleaning step is a semiconductor device characterized in that performed for 1 to 10 minutes, preferably 5 minutes using 10 to 70 ℃ preferably deionized water of 60 ℃ and 1 to 99%, preferably 2.38% TMAH mixed solution Capacitor formation method. The method of claim 1, The cleaning process is a capacitor forming method of a semiconductor device, characterized in that performed using a mechanical method such as ultrasonic or sterling.