KR19990006092A - Method for forming charge storage electrode of semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a charge storage electrode of a semiconductor device, wherein the surface area of a charge storage electrode is increased by a process of depositing a conductor and an insulator and forming an entire surface during the formation of the charge storage electrode, thereby increasing capacitance of the capacitor and simplifying the process. By reducing the production cost, thereby improving the productivity of the semiconductor device and thereby high integration of the semiconductor device.

Description

Method for forming charge storage electrode of semiconductor device

The present invention relates to a method of forming a charge storage electrode of a semiconductor device, and more particularly to a technique for increasing the capacitance of a capacitor by forming a cylindrical charge storage electrode having a plurality of spacers.

Recently, due to the trend toward higher integration of semiconductor devices, it is difficult to form capacitors with sufficient capacitance due to a decrease in cell size. In particular, a DRAM device including one MOS transistor and a capacitor has a word in a vertical and horizontal direction on a semiconductor substrate. Lines and bit lines are orthogonally arranged, a capacitor is formed over two gates, and a contact hole is formed in the center of the capacitor.

In this case, the capacitor mainly uses an oxide film, a nitride film, or an O.O. (oxide-nitride-oxide) film as a dielectric, using polycrystalline silicon as a conductor, and a capacitance of a capacitor that occupies a large area in a chip. While reducing the area, reducing the area becomes an important factor in the high integration of the DRAM device.

Therefore, C = (ε ₀ × ε _r × A) / T (where ε ₀ is the vacuum permittivity of vaccum, ε _r is the dielectric constant of the dielectric film, A is the surface area of the capacitor, and T is the dielectric film In order to increase the capacitance C of the capacitor, a material having a high dielectric constant is used as the dielectric, a thin dielectric film is formed, or the surface area of the capacitor is increased.

However, these methods all have their problems.

That is, dielectric materials having high dielectric constants, such as Ta ₂ O ₅ , TiO _2, or SrTiO ₃ , have been studied. Difficult to apply to the device, and reducing the thickness of the dielectric film seriously affects the reliability of the capacitor by breaking the dielectric film during device operation.

Further, in order to increase the surface area of the charge storage electrode of the capacitor, a polysilicon layer is formed in multiple layers and then formed into a pin structure through which they are connected to each other, or a cylindrical charge storage electrode is formed on the contact. It may be used a method such as forming.

However, the method of manufacturing a charge storage electrode of a semiconductor device according to the prior art as described above has a problem in that the area of the device is reduced due to the high integration of the DRAM, and thus it is still unable to measure sufficient capacitance.

In order to solve the above-mentioned problems of the related art, a multi-cylindrical charge storage electrode is formed by a deposition process and an entire surface etching process of conductors and insulators, thereby increasing the capacitance of the capacitor to enable high integration of semiconductor devices. It is an object of the present invention to provide a method for forming a charge storage electrode of a semiconductor device.

1A to 1I are cross-sectional views illustrating a method of forming a charge storage electrode of a semiconductor device according to a first embodiment of the present invention.

2A to 2H are cross-sectional views illustrating a method of forming a charge storage electrode of a semiconductor device according to a second embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

11, 12: semiconductor substrate, 13, 14: lower insulating film, 15, 16: first polycrystalline silicon, 17, 18: first insulating film, 19, 20: photosensitive film pattern, 21, 22: second polycrystalline silicon, 23 ,: Second insulating film, 25: third polycrystalline silicon

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

Forming a lower insulating film having a charge storage electrode contact hole on the semiconductor substrate;

Forming a first conductive film on the lower insulating film;

Forming a first insulating film on the first conductive film;

Etching the entire surface of the first insulating layer using a charge storage electrode mask;

Partially etching the first conductive film in a predetermined thickness;

Forming second conductive spacers on both side walls of the first insulating film;

Removing the first insulating film;

Forming a second insulating film spacer on both side walls of the second conductive spacer;

Forming a third conductive spacer on both side walls of the second insulating film spacer;

It is a 1st characteristic that the process includes removing the said 2nd insulating film.

In addition, the method for forming a charge storage electrode of a semiconductor device for achieving the above object,

Forming a lower pickling film including a large storage hole with a charge storage electrode on the semiconductor substrate;

Forming a cylindrical charge storage electrode by forming a first conductive film on the lower insulating film;

Forming a first insulating layer on the cylindrical charge storage electrode;

Forming a load light film pattern having a width of the cylindrical charge storage electrode on the first insulating film;

Removing the first insulating layer using the photoresist pattern as an etching mask;

Removing the photoresist pattern;

Etching the entire first insulating film;

Forming a second conductor on top of the entire surface of the structure;

Etching the entire surface of the second conductor,

A second feature is to include a step of forming the second conductive spacer by removing the first insulating film.

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

1A to 1I are cross-sectional views illustrating a method of forming a storage electrode of a semiconductor device according to a first embodiment of the present invention, and a method of forming a triple cylinder type charge storage electrode.

First, a lower insulating film 13 is formed on the semiconductor substrate 11 on which a MOS field effect transistor (not shown) is formed.

Next, the lower insulating layer 13 on the upper portion of the semiconductor substrate 11, which is supposed to be the charge storage electrode contact, is removed to form a charge storage electrode contact hole (not shown).

Then, the first polycrystalline silicon 15 is deposited on the entire surface of the structure.

A first insulating layer 17 is formed on the first polysilicon 15. In this case, the first insulating layer 17 may be formed of P. S. G. (hereinafter referred to as PSG) or nitride.

Subsequently, a photosensitive film pattern l9 is formed on the first insulating layer 17 to form a charge storage electrode. (FIG. 1A)

Next, the first insulating layer 17 is etched using the photoresist pattern 19 as an etching mask.

At this time, the etching process is carried out using an etching gas of C _x F _y type, using a gas of C _X F _Y type containing CHFx to reduce the interaction between silicon and F _X , and increases the etching selectivity .

The etch selectivity is controlled by the C _x F _Y thickness that appears on the silicon surface after steady state.

Then, the first polycrystalline silicon 15 is partially etched using the photoresist pattern 19 as a mask, and then removed while leaving enough in the subsequent process.

In this case, the etching process is performed using an etching gas composed of Cl ₂ / HBr to increase the etching selectivity with respect to the first insulating layer 17.

Here, the first polysilicon 15, which is thin on the lower insulating layer 13, is connected to conductors that are subsequently deposited to form a charge storage electrode. (FIG. 1B)

Next, the photoresist layer pattern 19 is removed, and the second polysilicon 21 is deposited on the entire surface of the structure. (FIG. 1C)

Next, the second polycrystalline silicon 21 isotropically etched to form a second polycrystalline silicon 21 spacer connected to the first polycrystalline silicon 15.

Thereafter, the first insulating layer 17 is removed. (FIG. 1D)

Subsequently, a second insulating film 23 is formed on the entire surface of the structure.

Here, the second insulating layer 23 is formed of PSG or nitride layer (Si ₃ N ₄ ). (FIG. 1E)

The second insulating layer 23 is isotropically etched until the first polysilicon 15 is exposed to form second insulating layer 23 spacers on both sidewalls of the second polysilicon 21 spacer.

In this case, the etching process is to etch the second insulating layer 23 by using an etching selectivity difference with a C _x F _y type etching material including CHF _x .

In addition, when the second insulating layer 23 is deposited as a nitride layer, the nitride layer having a higher Si / N ratio is etched faster in the mixed gas of CF _X / He, and the etching selectivity is improved when N ₂ is added instead of He. .

At this time, the addition of the N ₂ gas reduces the radicals forming the polymer and increases the dissociation / ionization process in the CHF _x gas, thereby increasing the etching selectivity. (FIG. 1F)

Next, a third polysilicon 25 is formed on the entire surface of the structure. (Fig. 1g)

Next, the third polysilicon 25 is isotropically etched until the first polycrystalline silicon 15 is exposed to form a third polysilicon 25 spacer on both sidewalls of the spacer of the second insulating layer 23.

In this case, the isotropic etching process removes the first polycrystalline silicon 15 remaining in the portion where the charge storage electrode is not formed due to the transient etching.

Here, the etching process is performed using HBr / Cl ₂ as an etching source. (FIG. 1H)

Subsequently, the second insulating layer 23 is removed to form a third polysilicon 21 spacer and a third polysilicon 25 spacer connected to the first polysilicon 15 to form a tri-cylindrical charge storage electrode. Form. (FIG. 1i)

2A to 2H are cross-sectional views illustrating a method of forming a storage electrode of a semiconductor device according to a second embodiment of the present invention, and a method of forming a double cylinder type charge storage electrode.

First, a lower insulating film 14 is formed on the semiconductor substrate 12 on which a MOS field effect transistor (not shown) is formed.

Next, the lower insulating film 14 on the upper portion of the semiconductor substrate 12, which is supposed to be the charge storage electrode contact, is removed to form a charge storage preform contact hole (not shown).

Next, a cylindrical first polycrystalline silicon 16 is formed on the entire surface of the structure. (FIG. 2A)

A first insulating film 18 is formed over the entire surface of the structure.

In this case, the first insulating layer 18 may be formed of P. S. paper (hereinafter referred to as PSG) or nitride film. (FIG. 2B)

Subsequently, a photosensitive film pattern 20 for forming a charge storage electrode is formed on the first insulating layer 18.

In this case, the photoresist pattern 20 is formed by the size of the cylindrical charge storage electrode formed of the first polycrystalline silicon 16. (FIG. 2C)

Next, the first insulating layer 18 is etched using the photoresist pattern 20 as an etching mask.

In this case, the etching surface formed after the etching process is formed of the first polysilicon 16, the first insulating layer 18, and the photoresist pattern 20. (FIG. 2D)

Next, the photoresist layer pattern 20 is removed, and the first insulating layer 18 is etched or isotropically etched to remove the spacers of the first insulating layer 18 to expose the first polysilicon 16. . (FIG. 2E)

Thereafter, a second polycrystalline silicon 22 is formed on the entire surface of the structure. (FIG. 2F)

Subsequently, the second polysilicon 22 is completely etched to form second polycrystalline silicon 22 spacers on both sidewalls of the first polycrystalline silicon 16 and the first insulating layer 18. (Fig. 2g)

The first insulating layer 18 is removed to form a double cylinder type charge storage electrode formed of two pairs of spacers. (FIG. 2H)

The width of the cylindrical charge storage electrode as described above can be adjusted by adjusting the thickness of the polysilicon.

As described above, in the method of forming a charge storage electrode of a semiconductor device according to the present invention, the capacitance of the capacitor is increased by increasing the surface area of the charge storage electrode through the deposition and front side etching process of the conductor and the insulator during the formation of the charge storage electrode. In addition, there is an advantage of reducing the production cost by simplifying the process, thereby improving the productivity of the semiconductor device.

Claims (11)

Forming a lower insulating film having a charge storage electrode contact hole on the semiconductor substrate; Forming a first conductive film on the lower insulating film; Forming a first insulating film on the first conductive film; After etching the first insulating layer using a charge storage electrode mask, Partially etching the first conductive film in a predetermined thickness; Forming second conductive spacers on both side walls of the first insulating film; Removing the first insulating film; Forming a second insulating film spacer on both side walls of the second conductive spacer; Forming a third conductive spacer on both sidewalls of the second insulating film spacer and overetching the entire substrate to remove the first and third conductive films other than the charge storage electrode region; A method of forming a charge storage electrode of a semiconductor device comprising the step of removing the second insulating film. The method according to claim 1, And the first insulating film and the second insulating film are PSG. The method according to claim 1, The first insulating film and the second insulating film is a nitride film forming method, characterized in that the nitride film. The method according to claim 1, And removing the first insulating film and the second insulating film by an etching process using a C _x Fr gas including CHF _X. The method according to any one of claims 1 to 3, The first and second insulating film etching process is performed by the etching process using a CFx / He mixed gas, the method of forming a charge storage electrode of a semiconductor device. The method according to any one of claims 1 to 3, And etching the first and second insulating layers by an etching process using CHF _X / N ₂ gas. The method according to claim 1, Wherein the etching process of the third conductor is performed by an etching process using HBr / Cl ₂ gas as an etching source. The method according to claim 7, And etching the third conductor is a transient etching process. Forming a lower insulating film having a charge storage electrode contact hole on the semiconductor substrate; Forming a cylindrical charge storage electrode by forming a first conductive film on the lower insulating film; Forming a first insulating layer on the cylindrical charge storage electrode; Forming a photoresist pattern having a width of the cylindrical charge storage electrode on the first insulating layer; Etching the first insulating layer using the photoresist pattern as an etching mask; Removing the photoresist pattern; Etching the entire surface of the first insulating layer; Forming a second conductor on top of the entire surface of the structure; Etching the entire surface of the second conductor, Forming a second conductive spacer by removing the first insulating layer; The method according to claim 9, And the first insulating layer is formed of PSG. The method according to claim 9, The first insulating layer is formed of a nitride film, the charge storage electrode forming method of a semiconductor device.