JPH08213554A - Forming method of roughened polysilicon film - Google Patents

Abstract

PURPOSE: To provide a method of easily forming a roughened polysilicon film. CONSTITUTION: A positive resist film 16 of positive resist high in plasma resistance and low in heat resistance is formed on an opening and an interlayer insulating film 12. Then, the positive resist film 16 is subjected to a high-power RIE. In result, irregularities 18 are generated on the surface 16a of the positive resist film 16. Then, the positive resist film 16 provided with irregularities 18 and the interlayer insulating film 12 are etched. As a result, irregularities 20 are formed on the primary surface 12a of the interlayer insulating film 12. After the residual positive resist film 16 is removed, polysilicon is deposited on the primary surface 12a of the interlayer insulating film 12 through an LPCVD method, whereby a roughened polysilicon film is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of this application relates to a method for forming a rough-surface polysilicon film suitable for use as a storage electrode film in a semiconductor device.

[0002]

2. Description of the Related Art An example of a conventional method of forming a storage electrode film made of a rough-surfaced polysilicon film is disclosed in the document: Japanese Patent Application Laid-Open No. 4-752. According to the technique disclosed in this document, first, a polysilicon film having an island structure or a mesh structure is formed on the underlying film. Next, an amorphous polysilicon film is formed on this polysilicon film. Next, this polysilicon film is conductively polycrystallized to form a conductive polysilicon film having irregularities on the surface. Then, by patterning this conductive polysilicon film, a large surface area,
Therefore, the storage electrode film made of a rough-surfaced polysilicon film having a large capacitance is formed.

[0003]

However, according to the technique disclosed in the above-mentioned document, since the polysilicon film having the island structure or the network structure is formed, not only the process becomes complicated but also very strict. There is a problem that management of film forming conditions is required. Further, there is a problem that the reproducibility of the film quality of the formed rough surface polysilicon is low.

Therefore, it has been desired to realize an easy method for forming a rough-surfaced polysilicon film.

[0005]

According to the method of forming a rough-surfaced polysilicon film of the first invention of this application, a step of forming a positive resist film on an underlayer, and a step of forming the positive resist film Reactive ion etching (RIE)
To form irregularities on the surface of the positive resist film, and to form irregularities on the main surface of the underlying layer by etching the positive resist film and the underlying layer having the irregularities And a step of forming concavities and convexities on the main surface of the base, and then removing the remaining positive resist film, and using a low pressure CVD (LPCVD) method to form polysilicon on the main surface of the base with the concavities and convexities. And forming a rough surface polysilicon film by depositing.

Further, according to the method for forming a rough surface polysilicon film of the second invention of this application, a step of forming irregularities on the main surface of the base by performing sputter etching on the main surface. And a step of forming a rough surface polysilicon film by depositing polysilicon on the sputter-etched main surface by using a low pressure CVD (LPCVD) method.

[0007]

According to the method of forming the rough-surfaced polysilicon film of the first invention of this application, a positive resist film is formed on the underlayer and RIE is performed. When RIE is performed with high power on a positive resist having weak plasma resistance and heat resistance, the surface of the positive resist solidifies and shrinks. As a result, irregularities can be formed on the surface of the positive resist film.

The thickness of the concave portion of this positive resist film is smaller than that of the convex portion. Therefore, when the positive resist film having irregularities is etched, the base is exposed in the concave regions before the convex regions. Therefore, the underlying surface exposed in the region of the recess can be partially etched. As a result, irregularities can be formed on the main surface of the base.

By depositing polysilicon by LPCVD on the base having irregularities, it is possible to form a rough surface polysilicon film having irregularities corresponding to the irregularities of the foundation. As described above, according to the method of the present invention, the rough-surfaced polysilicon film can be easily formed.

Further, according to the method of forming the storage electrode film of the second invention of the present application, the main surface of the base film is subjected to sputter etching to directly form irregularities on the main surface. To do. Then, a polysilicon film can be easily formed by forming a polysilicon film on the base having the irregularities by the LPCVD method.

The rough surface polysilicon formed by the methods of the first and second inventions has not only unevenness on the upper surface but also unevenness along the underlying surface on the lower surface. as a result,
The surface area can be increased by the unevenness of the upper surface and the lower surface. Therefore, a storage electrode having a large electric capacity can be easily formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present application with reference to the drawings
And an example of a method of forming a rough-surfaced polysilicon film of the second invention will be described respectively. It should be noted that the drawings to be referred to, the size of each constituent component,
The shape and the positional relationship are only schematically shown.
Therefore, these inventions are not limited to the illustrated examples.

<First Embodiment> FIGS. 1A to 1C show
FIG. 6 is a sectional process diagram of the first half used for explaining a method of forming a rough-surfaced polysilicon film of the first example. In addition, FIGS. 2A and 2B are sectional process drawings of the latter half following FIG. 1C.

In this embodiment, a stack type capacitor storage electrode film is formed.

First, after forming an opening 14 to be a trench in the interlayer insulating film 12 of the base 12 provided on the substrate 10,
A positive resist film 16 is formed on the opening 14 and the interlayer insulating film 12. The material of the positive resist film 16 is
A positive resist with low plasma resistance and low heat resistance will do,
In particular, a positive resist that cures at a temperature of about 100 ° C. or lower is desirable. Here, FH6400 (trade name) manufactured by Fuji Hunt is used as a positive resist ((A) of FIG. 1).

Next, the positive resist film 16 is subjected to RIE with high power. When exposed to a high temperature by this RIE, the surface of the positive resist film 16 hardens and contracts. As a result, the unevenness 18 can be formed on the surface 16a of the positive resist film 16 ((B) of FIG. 1).

Next, the positive resist film 1 having the unevenness 18 is formed.
6 and the interlayer insulating film 12 are etched. During etching, the positive resist film 16 partially remains, and the interlayer insulating film 12 exposed between the remaining portions.
The etching is stopped when the main surface of is partially etched. As a result, the main surface 12a of the interlayer insulating film 12
The unevenness 20 can be formed on the surface (FIG. 1C).

Next, after the unevenness is formed on the main surface 12a of the interlayer insulating film 12, the remaining positive resist film 16 is removed ((A) of FIG. 2).

Then, polysilicon is deposited by a low pressure CVD (LPCVD) method on the main surface 12a of the inter-layer insulation film 12 on which the irregularities are formed to form a rough surface polysilicon film 22. Here, the rough surface polysilicon 22
In order to render the semiconductor conductive, an impurity is introduced and an annealing treatment is performed (FIG. 2B).

Next, the storage electrode film 24 is defined from the rough surface polysilicon film 22 by using a normal photolithography and etching technique ((C) of FIG. 2).

<Second Embodiment> (A) to (C) of FIG.
FIG. 8 is a sectional process diagram for explaining the rough-faced polysilicon film of the second example.

In this embodiment, a stack type capacitor storage electrode film is formed.

First, after forming an opening 14 to be a trench in the underlying interlayer insulating film 12 provided on the substrate 10, a positive resist 30 is embedded in the opening 14 by an etch back method. This is to protect the substrate 10 from damage in later steps ((A) of FIG. 3).

Next, the main surface 12a of the interlayer insulating film 12 is sputter-etched with Ar, so that the main surface 12a is roughened to form irregularities 32. The conditions for this sputter etching (for example, pressure,
By controlling the power and the gas flow rate), it is expected that the degree of unevenness can be controlled ((B) in FIG. 3).

Next, the positive resist 30 embedded in the opening 14 is removed ((C) in FIG. 3).

Then, low pressure CVD is performed on the sputter-etched main surface by the same process as in the first embodiment.
A rough surface polysilicon film is formed by depositing polysilicon using the (LPCVD) method. Then, by defining this, a storage electrode having a fin structure is formed (not shown).

In each of the embodiments described above, these inventions are
Although an example of using a specific material and forming under specific conditions has been described, these inventions can be subjected to many modifications and variations. For example, in the second embodiment described above, sputter etching using argon (Ar) was performed.
In the second invention, for example, sputter etching using krypton (Kr) or xenon (Xe) may be performed to form irregularities on the underlying surface.

[0028]

According to the method for forming a rough surface polysilicon film of the first invention of this application, a positive resist film is formed on the underlayer and RIE is performed. As a result, irregularities can be formed on the surface of the positive resist film.

When the positive resist film having irregularities is etched, the underlying surface exposed in the concave region can be partially etched. As a result, irregularities can be formed on the main surface of the base. By depositing polysilicon by LPCVD on the base having irregularities, it is possible to form a rough surface polysilicon film having irregularities corresponding to the irregularities of the foundation. As described above, according to the method of the present invention, the rough-surfaced polysilicon film can be easily formed.

Further, according to the method of forming the storage electrode film of the second invention of this application, the main surface of the base film is subjected to sputter etching to form irregularities directly on the main surface. To do. Then, a polysilicon film can be easily formed by forming a polysilicon film on the base having the irregularities by the LPCVD method.

The rough surface polysilicon formed by the methods of the first and second inventions has not only the unevenness on the upper surface but also the unevenness along the underlying surface on the lower surface. as a result,
The surface area can be increased by the unevenness of the upper surface and the lower surface. Therefore, a storage electrode having a large electric capacity can be easily formed.

[Brief description of drawings]

1A to 1C are sectional process diagrams of the first half used to describe a first embodiment.

2A to 2C are cross-sectional process diagrams of the latter half following FIG. 1C.

3A to 3C are cross-sectional process diagrams for explaining the second embodiment.

[Explanation of symbols]

 10: Substrate 12: Interlayer insulating film 12a: Main surface 14: Opening 16: Positive resist 16a: Surface 18: Unevenness 20: Unevenness 22: Rough surface polysilicon film 24: Storage electrode film 30: Positive resist 32: Unevenness

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/3065 21/32 H01L 21/32

Claims (2)

[Claims] 1. A step of forming a positive resist film on a lower surface, and a step of forming unevenness on the surface of the positive resist film by performing reactive ion etching (RIE) on the positive resist film. The step of forming irregularities on the main surface of the underlayer by etching the positive resist film and the underlayer having the irregularities, and the step of forming the irregularities on the main surface of the underlayer and then remaining the positive film The step of removing the resist film and the low pressure CVD (L
And a step of forming a rough surface polysilicon film by depositing polysilicon using a PCVD method. 2. A step of forming irregularities on the main surface by performing sputter etching on the main surface of the base, and low pressure CVD on the main surface sputter-etched.
A method of forming a rough surface polysilicon film, comprising the step of forming a rough surface polysilicon film by depositing polysilicon using the (LPCVD) method.