KR100324812B1 - Method for fabricating semiconductor memory device - Google Patents

Abstract

PURPOSE: A method for fabricating a semiconductor memory device is provided to increase a surface area of a storage electrode and guarantee large capacitance by forming hemispherical grain(HSG) silicon on the storage electrode. CONSTITUTION: A lower insulation layer(2) having a contact hole is formed on a semiconductor substrate(1). A polycrystalline silicon layer for the storage electrode is formed on the resultant structure. A silicon-containing metal layer is formed on the polycrystalline silicon layer for the storage electrode wherein silicon is formed on an interface between the polycrystalline silicon layer for the storage electrode and the metal layer. The metal layer and the polycrystalline silicon layer are sequentially and selectively etched to form a metal layer pattern and a polycrystalline silicon layer pattern(14) for the storage electrode. The metal layer pattern is etched to make the HSG silicon left on the polycrystalline silicon layer pattern for the storage electrode so that the surface area of the storage electrode is expanded.

Description

Semiconductor Memory Manufacturing Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor memory device, and is a technique capable of improving the reliability of a device by forming a silicon mass on a storage electrode to form a high capacity semiconductor memory device.

An important factor related to the integration of DRAM, a general-purpose semiconductor memory device, is the reduction of the cell area and consequently the limitation of securing the charge storage capacity. However, in order to achieve high integration of semiconductor integrated circuits, the reduction of the unit area of chips and cells is inevitable. Therefore, with the development of advanced process technology, securing the reliability of the device and securing the charge storage capacity of the cell are urgent challenges. .

The prior art uses a semi-spherical grain (HSG: Hemisperical Grain, hereinafter referred to as HSG) silicon to form a semiconductor memory device.

However, the HSG silicon has a large leakage current in use, poor uniformity, and the HSG silicon can be formed only in a certain temperature range. In addition, the shape of the HSG silicon may be formed in a toy shape instead of a hemispherical shape, which may cause loss of a small impact.

Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor memory device capable of securing a large storage capacity by increasing the surface area of a storage electrode by forming a hemispherical silicon mass on the storage electrode formed in the prior art.

A feature of the present invention for achieving the above object is the step of forming a lower insulating layer on the semiconductor substrate and a contact hole on the lower insulating layer using a contact mask, and depositing a polysilicon film for the storage electrode Connecting the polysilicon film for the storage electrode to the semiconductor substrate through a contact hole; depositing a metal layer containing silicon on the polycrystalline silicon film for the storage electrode; and forming a storage electrode mask over the metal layer on the metal layer. And etching the metal layer and the polysilicon film for the storage electrode sequentially using the storage electrode mask to form a metal layer pattern and the polysilicon film pattern for the storage electrode, and removing the storage electrode mask. Removed by a wet method for the storage electrode during the metal layer deposition process It is to include a process for forming a storage electrode having an enlarged surface area remains a hemispherical silicon lump on top of the crystalline silicon film.

Another aspect of the present invention for achieving the above object is a step of forming a lower insulating layer on the upper surface of the semiconductor substrate and forming a contact mask on the lower insulating layer, and a contact for exposing the semiconductor substrate using the contact mask Forming a hole and filling the contact hole with a polysilicon film for a storage electrode to be connected to the semiconductor substrate through the contact hole, and then forming a storage electrode mask thereon; and using the storage electrode mask Etching the storage electrode polycrystalline silicon film to form a polysilicon film pattern for the storage electrode and removing the storage electrode mask; depositing a metal layer on the entire structure to a predetermined thickness; and depositing the polycrystalline silicon for the storage electrode when the metal layer is deposited. Leaving a silicon lump formed on the metal layer in contact with the sidewalls and top of the film pattern. It includes a step of removing the base metal layer by a wet method.

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

1A to 1E are sectional views showing the semiconductor memory device manufacturing process as the first embodiment of the present invention.

FIG. 1A is a cross-sectional view illustrating the formation of the contact mask 3 using the photoresist film after applying the lower insulating layer 2 on the semiconductor substrate 1. The device isolation layer is formed on the semiconductor substrate 1. Oxide films, bit lines, word lines, and the like are omitted for convenience.

FIG. 1B shows a contact hole 10 exposing the semiconductor substrate 1 by etching the lower insulating layer 2 using the contact mask 3, removing the contact mask 3, and then storing the contact hole 3. A cross-sectional view showing the filling of the contact hole 10 so as to be connected to the semiconductor substrate 1 through the contact hole 10 by depositing an electrode polycrystalline silicon film 4.

FIG. 1C is a cross-sectional view of depositing a metal layer 6 containing silicon on the polysilicon film 4 for the storage electrode and forming a storage electrode mask 7 using the photosensitive film thereon. When the metal layer 6 is deposited, when the metal layer 6 is deposited on the polysilicon film 4 for the storage electrode, the silicon component of the metal layer 6 diffuses and the hemispherical silicon agglomerate 5 is formed on the bottom surface of the metal layer 6. ) Is formed. Here, the silicon agglomerate 5 is formed when the deposition temperature is high when the metal layer 6 is deposited, the size of the silicon agglomerate 5 is increased and the number is formed less. When the deposition temperature is low, the silicon agglomerate 5 is formed. The surface area of the silicon agglomerate 5 formed by decreasing the size and increasing the number of is increased. The deposition temperature in the present invention corresponds to a case where the temperature is lower than 100 ° C-200 ° C or less.

1D is a mask process using the storage electrode mask 7 to sequentially etch the metal layer 6 and the polysilicon film 4 for the storage electrode to sequentially etch the metal layer pattern 16 and the polysilicon film pattern 14 for the storage electrode. ) Is a cross-sectional view showing that the storage electrode mask 7 is removed, and the silicon lump 5 remains on the bottom surface of the metal layer pattern 16.

FIG. 1E is a cross-sectional view of the metal layer pattern 16 leaving the silicon agglomerate 5 by a wet method. The silicon agglomerate 5 remains on the polysilicon film pattern 14 for the storage electrode. By being used as the storage electrode together with the polysilicon film pattern 14 for the storage electrode, the surface area of the storage electrode can be enlarged to form a semiconductor memory device having an increased charge storage capacity. Here, instead of the wet method, dry etching may be performed using a gas having a high selectivity with respect to polycrystalline silicon.

2A to 2D are sectional views showing the semiconductor memory device manufacturing process as the second embodiment of the present invention.

FIG. 2A is a cross-sectional view showing the formation of the storage electrode mask 7 using the photoresist film on the storage polycrystalline silicon film 4 after the process of FIG. 1B of the first embodiment.

2B is a cross-sectional view showing that the polysilicon film pattern 14 for the storage electrode is etched by using the storage electrode mask 7 to form the polysilicon film pattern 14 for the storage electrode, and then the storage electrode mask 7 is removed. to be.

FIG. 2C is a cross-sectional view showing a predetermined thickness of depositing a metal layer 6 containing silicon on the entire structure, wherein the metal layer 6 is in contact with the polysilicon film pattern 14 for storage electrodes and the metal layer 6. The silicon component of 6) diffused to form the silicon lump 5 is shown. Here, the metal layer 6 is formed of an alloy of aluminum and silicon.

FIG. 2D is a cross-sectional view illustrating the removal of the metal layer 6 while leaving the silicon lump 5 formed on the sidewalls and the upper portion of the polysilicon layer pattern 14 for the storage electrode, wherein the storage electrode having an enlarged surface area is formed. do.

According to the present invention, it is possible to solve the problem caused by using the HSG silicon in the prior art and to maximize the charge storage capacity by increasing the surface area of the storage electrode can improve the reliability of the semiconductor device.

1A to 1E are cross-sectional views showing a semiconductor memory device manufacturing process as the first embodiment of the present invention.

2A to 2D are cross-sectional views showing a semiconductor memory device manufacturing process as a second embodiment of the present invention.

◈ Explanation of symbols for the main parts of the drawings

1: semiconductor substrate 2: lower insulating layer

3: contact mask 4: polysilicon film for storage electrode

5: silicon lump 6: metal layer

7: storage electrode mask 10: contact hole

14 polysilicon film pattern for storage electrode

16: metal layer pattern

Claims (4)

In the semiconductor memory device manufacturing method, Forming a lower insulating layer having a contact hole on the semiconductor substrate; Forming a polysilicon film for a storage electrode on the structure; Forming a metal layer containing silicon on the polysilicon film for the storage electrode, wherein a silicon lump is formed at an interface between the polysilicon film for the storage electrode and the metal layer; Forming a metal layer pattern and a polysilicon layer pattern for a storage electrode by sequentially etching the metal layer and the polysilicon layer for a storage electrode; Forming a storage electrode having an enlarged surface area by etching the metal layer pattern to leave a hemispherical silicon mass on the polycrystalline silicon film pattern for the storage electrode. The method of claim 1, And the metal layer is wet etched or dry etched using a gas having a high selectivity to polycrystalline silicon. The method of claim 1, And depositing the metal layer at 100 ° C.-200 ° C. or less. In the semiconductor memory device manufacturing method, Forming a lower insulating layer having a storage electrode contact hole on the semiconductor substrate; Forming a polysilicon film for a storage electrode connected to the semiconductor substrate through the storage electrode contact hole on an entire surface thereof; Forming a storage electrode by patterning the polysilicon film for the storage electrode using a storage electrode mask; Depositing a metal layer containing silicon on the entire structure to a predetermined thickness, and forming a silicon mass at an interface between the storage electrode and the metal layer; Removing the metal layer by a wet method to obtain a storage electrode having silicon lumps formed on top and sidewalls.