KR100696774B1 - A method for forming a capacitor of a semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a capacitor of a semiconductor device, wherein a conductive layer for polysilicon and a lower electrode used as a contact plug to form a concave type capacitor capable of sufficiently securing the capacitance of a highly integrated device. In order to improve the electrical resistance characteristics of the metal layer used as a barrier and to form a barrier metal layer to prevent the diffusion of impurities in the metal layer, bit lines and storage electrode contact plugs are formed on the semiconductor substrate and the insulating film is flattened over the entire surface. Next, the storage layer may be formed by etching the insulating layer to expose the storage electrode contact plug, and the insulating layer may be divided into a first etching process of vertically etching the insulating layer and a second etching process of obliquely etching. The barrier metal layer only on the exposed storage electrode contact plug surface. After the formation, forming a conductive layer for the storage electrode on the entire surface and forming a storage electrode isolated in each storage electrode region by using a front etching process to shorten the manufacturing process of the semiconductor device and to prevent deterioration of characteristics As a result, the productivity of the semiconductor device is improved and the characteristics and reliability of the semiconductor device are improved.

Description

A method for forming a capacitor of a semiconductor device

1A to 1C are cross-sectional views illustrating a method of forming a capacitor of a semiconductor device in accordance with an embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

11: bit line 13: storage electrode contact plug

15 nitride film 17 oxide film for storage electrode

21: photosensitive film pattern 23: titanium silicide layer

25 conductive layer for storage electrode 27 dielectric film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a capacitor of a semiconductor device, and in particular, to conducting a conductive plug for a polysilicon and a lower electrode used as a contact plug to form a concave type capacitor capable of sufficiently securing the capacitance of a highly integrated device. The present invention relates to a technique for forming a barrier metal layer to improve the electrical resistance characteristics of the metal layer used as the layer and to prevent the diffusion of impurities in the metal layer.

As semiconductor devices are highly integrated and cell size is reduced, it is difficult to secure a capacitance that is proportional to the surface area of the storage electrode.

In particular, in a DRAM device having a unit cell composed of one MOS transistor and a capacitor, it is important to reduce the area while increasing the capacitance of a capacitor, which occupies a large area on a chip, which is an important factor for high integration of the DRAM device.

Thus, the capacitance C of the capacitor represented by (εo × εr × A) / T (where, εo is the dielectric constant of the dielectric, εr is the dielectric constant of the dielectric film, A is the area of the storage electrode and T is the thickness of the dielectric film). In order to increase the dielectric constant, a material having a high dielectric constant was used as the dielectric film, a thin dielectric film was formed, or the surface area of the storage electrode was increased.

In the conventional concave-type capacitor forming process, a CMP process for forming storage electrodes and separating them is performed.

However, the CMP process is expensive and difficult to secure process uniformity.

In other words, in the CMP process for separating the entire die of the wafer, oxide loss for the storage electrode in a specific region is increased, resulting in a decrease in the height of the storage electrode.

Although not shown, it is a cross-sectional view showing a capacitor forming method of a semiconductor device according to the prior art.

First, an isolation layer, an impurity junction region, a word line, a bit line, and a storage electrode contact plug are formed on a semiconductor substrate, and an interlayer insulating layer is formed to planarize an upper portion thereof.

In this case, the contact plug for the storage electrode is formed of polysilicon.

Then, a titanium film is deposited on the entire surface and heat treated to react with the contact plug to form a titanium silicide layer and remove the remaining titanium film.

Then, a barrier metal layer is formed by forming a titanium nitride film on the entire surface.

Then, a nitride film and an oxide film for a storage electrode are sequentially formed on the entire surface.

The nitride electrode and the oxide layer for the storage electrode are patterned by a photolithography process using a storage electrode mask to expose the storage electrode contact plug (not shown) to define a storage electrode region.

Next, a conductive layer for a storage electrode is formed on a surface of the storage electrode region, and is formed to be connected to the contact plug through a barrier metal layer provided on the storage electrode contact plug.

In addition, the photoresist layer filling the storage electrode region is coated and the photoresist layer is etched by a subsequent planarization process, and the storage electrode conductive layer on the oxide layer for the storage electrode is etched to etch the storage electrode conductive layer in each storage electrode region. To isolate.

Then, the photoresist film remaining in the storage electrode region is removed, and a dielectric film and a plate electrode are formed on the entire surface to form a capacitor.

As described above, the method of forming a capacitor of a semiconductor device according to the related art includes a process of forming a contact plug in which a crack is caused in the titanium nitride film or a contact hole for a storage electrode is filled during the deposition process of a titanium nitride film used as a barrier metal layer. There is a problem that can cause sea voids. In addition, when excessively performing the planarization etching process to solve the above problem, there is a problem that the bit line may be damaged.

In order to solve the problems of the prior art as described above, a capacitor of a semiconductor device capable of preventing the deterioration of device characteristics by forming a barrier metal layer without performing a planar etching process after a contact etching process and a titanium nitride film deposition process. The purpose is to provide a formation method.

Capacitor forming method of a semiconductor device according to the present invention for achieving the above object,
Forming an interlayer insulating film having bit lines and storage electrode contact plugs formed on the semiconductor substrate;
Forming a planarized insulating film over the entire surface;
Defining a storage electrode region to expose the storage electrode contact plug by etching the insulating layer, wherein the insulating layer is divided into a first etching process of vertically etching the insulating layer and a second etching process of etching obliquely;
Forming a barrier metal layer only on the exposed storage electrode contact plug surface;
Forming a storage electrode conductive layer on the entire surface and forming a storage electrode isolated in each storage electrode region by using a front etching process;
Forming a dielectric film and a plate electrode over the entire surface thereof;
The storage electrode contact plug is formed of polysilicon,
The insulating film is provided with a stacked structure of a nitride film and an oxide film for a storage electrode,
The first etching process is performed using a high density plasma of 10 ¹¹ ~ 10 ¹³ / cm 3 using CO, Ar, C ₄ F ₈ , O ₂ gas as the source gas, the first etching process is 30 ~ Performing at a condition having a pressure of 70 mTorr, a power of 1300 to 1900 watts, and an electrode temperature of 30 to 80 캜;
The second etching process is performed by inclining the insulating film using a high density plasma of 10 ¹¹ to 10 ¹³ / cm 3 using Ar, C ₄ F ₈ , O ₂ gas as the source gas, but the second etching is performed. The step is carried out under conditions having a pressure of 30 to 70 mTorr, a power of 1300 to 1900 watts, and an electrode temperature of 30 to 80 ° C,
The barrier metal layer is formed by depositing a titanium film on the entire surface including the exposed contact plug and performing a heat treatment process to form a titanium silicide layer on the contact plug surface and to remove the remaining titanium film on the other part, wherein the titanium film is removed. Is characterized in that it is carried out using a solution such that the ratio of HF: (NH ₃ F + H ₂ O) is about 1: 250 to 350 in a spin etcher having a spin rotational speed of 3000 to 6000 RPM. .
Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

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1A to 1C are cross-sectional views illustrating a method of forming a capacitor of a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 1A, a planarized interlayer insulating film (not shown) including an isolation layer, an impurity junction region, a word line, a bit line 11, and a storage electrode contact plug 13 is formed on the semiconductor substrate (not shown). Form.

In this case, the contact plug 13 is formed of polysilicon.

Then, a nitride film 15 and an oxide film 17 for a storage electrode are formed over the entire surface.

The photoresist pattern 21 is formed on the storage electrode oxide layer 17.

In this case, the photoresist pattern 21 is formed by an exposure and development process using a storage electrode mask to define a storage electrode region.

Referring to FIG. 1B, the storage electrode oxide layer 17 and the nitride layer 15 are etched using the photoresist pattern 21 as a mask to form a storage electrode region exposing the contact plug 13. In this case, the etching process may partially etch the surface of the contact plug 13 in accordance with the transient etching process. Then, the etching selectivity difference between the contact plug 13 and the storage electrode oxide film 17 is about 20 to 1.

The etching process of the oxide layer 17 and the nitride layer 15 for the storage electrode is as follows.                     

First, the first etching process is performed vertically on the oxide layer 17 of the storage electrode using a high density plasma of 10 ¹¹ to 10 ¹³ / cm 3 using CO, Ar, C ₄ F ₈ and O ₂ gas as the source gas. Conduct. In this case, the first etching process is carried out under the conditions having a pressure of 30 to 70 mTorr, power of 1300 to 1900 watts, electrode temperature of 30 to 80 ℃.

Then, the secondary etching process is performed to incline the oxide film 17 for the storage electrode using a high density plasma of 10 ¹¹ to 10 ¹³ / cm 3 using Ar, C ₄ F ₈ , O ₂ gas as the source gas. In this case, the second etching process is carried out under the conditions having a pressure of 30 to 70 mTorr, a power of 1300 to 1900 watts, and an electrode temperature of 30 to 80 ℃.

Then, a titanium film is deposited on the entire surface including the exposed contact plug 13 and a heat treatment is performed to form a titanium silicide layer 23 on the surface of the contact plug 13 and to remove the remaining titanium film on the other portion. do.

In this case, the titanium film removal process uses a solution having a ratio of HF: (NH ₃ F + H ₂ O) of about 1: 250 to 350 in a spin etcher having a spin rotational speed of 3000 to 6000 RPM. This is done by minimizing damage to the oxide film 17 for the storage electrode.

Referring to FIG. 1C, a conductive layer 25 for a storage electrode, which is a lower electrode, is formed on an entire surface including the titanium silicide layer 23. In this case, the storage electrode conductive layer 25 is formed of a metal such as iridium, ruthenium, platinum, or the like.                     

Then, a photoresist (not shown) is applied on the entire surface, and the conductive layer 25 for the storage electrode on the storage electrode oxide layer 17 is etched by the entire surface etching process, so that only the storage electrode conductive layer is formed in each storage electrode region. (25) is patterned to form a storage electrode.

Next, a capacitor is formed by forming a dielectric film 27 and a plate electrode (not shown) which is an upper electrode on the entire surface.

As described above, the method for forming a capacitor of a semiconductor device according to the present invention can eliminate a planar etching process, that is, a CMP process, which is unnecessary in the process of forming a contact plug for a storage electrode, thereby shortening the process and preventing deterioration of characteristics. It provides an effect that can improve the characteristics of the semiconductor device and improve the productivity.

Claims (9)

Forming an interlayer insulating film having bit lines and storage electrode contact plugs formed on the semiconductor substrate; Forming a planarized insulating film over the entire surface; Defining a storage electrode region to expose the storage electrode contact plug by etching the insulating layer, wherein the insulating layer is divided into a first etching process of vertically etching the insulating layer and a second etching process of etching obliquely; Forming a barrier metal layer only on the exposed storage electrode contact plug surface; Forming a storage electrode conductive layer on the entire surface and forming a storage electrode isolated in each storage electrode region by using a front etching process; A method of forming a capacitor of a semiconductor device comprising the step of forming a dielectric film and a plate electrode on the entire surface. The method of claim 1, And the storage electrode contact plug is formed of polysilicon. The method of claim 1, And the insulating film has a laminated structure of a nitride film and an oxide film for a storage electrode. The method of claim 1, The first etching process is a capacitor forming method of a semiconductor device, characterized in that using a high density plasma of 10 ¹¹ ~ 10 ¹³ / cm 3 using CO, Ar, C ₄ F ₈ and O ₂ gas as the source gas . The method of claim 4, wherein Wherein the first etching process is performed under conditions having a pressure of 30 to 70 mTorr, a power of 1300 to 1900 watts, and an electrode temperature of 30 to 80 ° C. The method of claim 1, The second etching process is a semiconductor device characterized in that the inclined etching of the insulating film using a high density plasma of 10 ¹¹ ~ 10 ¹³ / cm 3 using Ar, C ₄ F ₈ and O ₂ gas as the source gas Capacitor formation method. The method of claim 6, Wherein the second etching process is performed under conditions having a pressure of 30 to 70 mTorr, a power of 1300 to 1900 watts, and an electrode temperature of 30 to 80 ° C. The method of claim 1, The barrier metal layer is formed by depositing a titanium film on the entire surface including an exposed contact plug and performing a heat treatment process to form a titanium silicide layer on the contact plug surface and to remove the remaining titanium film on other portions. Capacitor formation method. The method of claim 8, The removal process of the titanium film is carried out using a solution having a ratio of HF: (NH ₃ F + H ₂ O) of 1: 250 to 350 in a spin etcher having a spin rotational speed of 3000 to 6000 RPM. A method of forming a capacitor of a semiconductor device, characterized in that.

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