JP3149858B2 - Local pad of semiconductor memory device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local pad of a semiconductor memory device and a method of manufacturing the same, and more particularly, to a semiconductor device in which a local pad for contact connection of a DRAM can be formed without damaging an element region. The present invention relates to a local pad of a storage device and a method of manufacturing the local pad.

[0002]

2. Description of the Related Art Along with miniaturization of a pattern, an element region caused by misalignment has become a serious problem. However, a method of increasing the reticle mask pattern and increasing the eye misalignment margin is impossible in mask fabrication. Therefore, at present, the amount of misalignment with the element region is reduced as much as possible to prevent the element region from being damaged, but this is approaching its limit. The conventional example is shown below.

FIG. 4 is a plan view in which a local pad 321 for a capacity contact and a local pad 322 for a bit line contact provided between the word lines 103 and 103 are formed. FIG. FIG. 6 is a sectional view taken along the line AA ′ showing the manufacturing process of the local pad. First, as shown in FIG. 6A, a trench isolation 302 is formed on a semiconductor substrate 301, and then, as shown in FIG. 4, after forming a word line 303, a polysilicon layer 304 is deposited at 8000.degree.
Then, as shown in FIG. 6B, an oxide film hard mask 310 is formed on the polysilicon layer 304 at 2000 to 4000 °, and then oxidized using the resist pattern 305 as a mask as shown in FIGS. 6B and 6C. The film hard mask 310 is etched. Thereafter, as shown in FIG. 6D, a second oxide film is formed on the entire surface of the oxide
Then, the second oxide film is etched back, and an oxide film sidewall 306 a is formed on the sidewall of the oxide film hard mask 310. Then, FIG.
As shown in (e), the polysilicon layer 304 is formed using the oxide film hard mask 310 and the oxide film sidewalls 306a as masks.
Is etched to form a local pad 300. In this way, the local pad 300 is
The thickness can be increased by the thickness of 6a.

[0004] However, oxide film hard mask 310 remains on local pad 300 at 2000 to 4000 °. Therefore, an interlayer insulating film 323 to be formed thereafter is formed.
Must be formed thick. However, when the thickness of the interlayer insulating film 323 is large, (1) when CMP is used in the planarization of the interlayer insulating film, the polishing time becomes long, and the thickness variation in the wafer surface increases. In addition, if the interlayer thickness is adjusted in the oxide film hard mask portion, the depth of the contact in the peripheral portion becomes deep, making the contact formation difficult. (2) When the local pads are high, voids are generated between the local pads when the interlayer insulating film is formed. (3) The use of the reflow-based planarization method has a drawback that a step is generated in the cell and in the peripheral circuit portion, and a problem such as disconnection or short-circuit of the wiring occurs in the step portion at the time of wiring patterning in a later step.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and in particular to eliminate damage to the element region due to misalignment when forming local pads.
By reducing the thickness of the interlayer insulating film, the occurrence of voids in the interlayer insulating film is reduced, and the opening of the contact is further facilitated.
Accordingly, it is an object of the present invention to provide a novel local pad of a semiconductor memory device having improved performance and a method of manufacturing the same.

Another object of the present invention is to provide a local pad of a semiconductor memory device in which the resistance of the local pad is reduced, and a method of manufacturing the local pad.

[0007]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object. That is, the first aspect of the local pad of the semiconductor memory device according to the present invention is the local pad of the semiconductor memory device which is provided between the word lines and connects the bit line contact or the capacitor contact to the element region. The local pad includes a polysilicon film formed so as to cover the element region, a WSi film formed on the polysilicon film, and a sidewall of an oxide film formed on a side wall of the WSi film. In a second aspect, the polysilicon film is larger than the element region.

Further, a first aspect of the method of manufacturing a local pad of a semiconductor memory device according to the present invention is a semiconductor provided between word lines and connecting a bit line contact or a capacitance contact to an element region. In a method of manufacturing a local pad of a storage device, an element isolation region is formed on a semiconductor substrate, a word line is formed, a polysilicon film is formed on the entire surface, and the polysilicon film is etched into a predetermined shape. Forming a local pad portion, forming a sidewall on a side wall of the local pad portion, and using the sidewall as a mask, further etching the remaining polysilicon film; and A second aspect is a local mode of a semiconductor memory device provided between a word line and a word line and connecting a bit line contact or a capacitance contact to an element region. In the method for manufacturing a semiconductor device, a first step of forming a word line after forming an element isolation region on a semiconductor substrate, and a second step of forming a polysilicon film on the entire surface to have a predetermined thickness A third step of applying a photoresist film on the polysilicon film and patterning the photoresist film; and forming a local pad portion by etching the polysilicon film using the photoresist film as a mask. A fourth step of leaving the film thickness of a portion not covered with the mask to a predetermined film thickness and performing etching so that the film thickness of the remaining portion is smaller than the etched film thickness; A fifth step of forming an oxide film on the entire surface, etching back the oxide film to form an oxide film sidewall on the side wall of the local pad portion, and using the sidewall as a mask And a sixth step of etching the remaining portion of the polysilicon film. The third aspect is provided between a word line and a word line contact. Alternatively, in a method of manufacturing a local pad of a semiconductor memory device for connecting a capacitor contact and an element region, an element isolation region is formed on a semiconductor substrate, a word line is formed, and a polysilicon film is formed on the entire surface. A film is formed, the WSi film is etched into a predetermined shape to form a local pad portion, a sidewall is formed on a side wall of the local pad portion, and the polysilicon film is formed using the sidewall as a mask. The fourth aspect is characterized in that etching is performed between the word line and the word line, the bit line contact or the capacitor contact and the element region are provided. In the method for manufacturing a local pad of a semiconductor memory device, a first step of forming a word line after forming an element isolation region on a semiconductor substrate, and forming a polysilicon film on the entire surface, A second step of forming a WSi film thicker than the thickness of the polysilicon film, a third step of applying a photoresist film on the WSi film and patterning the photoresist film, A fourth step of etching only the WSi film to form a local pad portion as a mask, forming an oxide film on the entire surface, etching back the oxide film, and forming an oxide film on the side wall of the local pad portion. A fifth step of forming a side wall; and a sixth step of etching the polysilicon film using the side wall as a mask.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a local pad of a semiconductor memory device according to the present invention is provided between a word line and a word line, and connects a bit line contact or a capacitance contact to an element region. Forming a device isolation region on a semiconductor substrate,
After forming the word line, a polysilicon film is formed on the entire surface, the polysilicon film is etched into a predetermined shape to form a local pad portion, and a sidewall is formed on a side wall of the local pad portion. Using the sidewall as a mask, the remaining polysilicon film is further etched, so that damage to the element region due to misalignment at the time of local pad formation is eliminated, and
By reducing the thickness of the interlayer insulating film, the occurrence of voids in the interlayer insulating film is reduced, and the opening of the contact is facilitated.

An element isolation region is formed on a semiconductor substrate, a word line is formed, a polysilicon film is formed on the entire surface, a WSi film is formed, and the WSi film is etched into a predetermined shape. After forming a local pad portion by forming a side wall on the side wall of the local pad portion, the polysilicon film is etched using the side wall as a mask. Can be made smaller than the above method.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of local pads of a semiconductor memory device according to the present invention and a method of manufacturing the same will be described in detail with reference to the drawings. FIG. 1 is a view showing a specific example of a method of manufacturing a local pad of a semiconductor memory device according to the present invention, and FIG. 2 is a sectional view in a direction orthogonal to FIG. In
In the method for manufacturing a local pad of a semiconductor memory device provided between a word line and a word line and connecting a bit line contact or a capacitance contact to an element region, after forming an element isolation region 102 on a semiconductor substrate 101, A first step of forming a word line 103, a second step of forming a polysilicon film 104 over the entire surface to a predetermined thickness, and applying a photoresist film 105 on the polysilicon film 104; A third step of patterning the photoresist film 105; etching the polysilicon film 104 with the photoresist film 105 as a mask to form a local pad 107; The film thickness is left at a predetermined film thickness, and the film thickness 104a of the remaining portion is made smaller than the etched film thickness. A fourth step of etching, and film an oxide film on the entire surface, the oxide film is etched back, the sidewall of the oxide film on the sidewall of the local pad portion 107 1
A fifth step of forming the sidewall 10;
6 as a mask, the remaining portion of the polysilicon film 1
A method for manufacturing a local pad of a semiconductor memory device, which includes a sixth step of etching the substrate 04a.

Hereinafter, this specific example will be described in more detail. FIG. 1 shows a process of forming a local pad between word lines after forming a word line on a semiconductor substrate on which elements are formed. First, a trench isolation 102 is formed on a semiconductor substrate 101 shown in FIG. 1A, and then, as shown in FIG. 4, after forming a word line 103, a polysilicon film 104 is deposited, for example, at 8000.degree. Thereafter, the film thickness of the polysilicon film 104 is etched back, and the film thickness of the polysilicon film 104 is adjusted on the word line 103 so as to be 2000 ° or less as shown in FIG. After that, as shown in FIG.
Is applied and patterning is performed. Next, as shown in FIG. 1C, the polysilicon film 104 is etched using the photoresist film 105 as a mask to form a local pad portion 107 having a shape left 500 to 1000 degrees from the base. Then, FIG.
As shown in (d), an oxide film is deposited on the entire surface to cover the local pad portion 107 at a temperature of 1000 to 4000 °, and the oxide film is etched back to form the local pad portion 1.
The oxide film side wall 106 is formed on the side wall 07. Finally, as shown in FIG. 1E, the remaining polysilicon film 104a is etched using the oxide film sidewall 106 as a mask to form a convex local pad 100.

As described above, the etching of the polysilicon film 104 is stopped halfway while leaving 500 to 1000 ° from the base, an oxide film sidewall 106 is formed on the side wall, and the polysilicon film 104 is masked using the oxide film sidewall 106 as a mask.
By etching 4a, the size of the local pad can be made larger than the local pad pattern formed of the photoresist. Therefore, even if the photoresist on the local pad is misaligned, the size of the local pad is larger than the photoresist pattern, so that damage to the element region 108 due to etching can be avoided.

(Second Specific Example) Next, a second specific example of the present invention will be described with reference to FIG. First, as shown in FIG. 3A, a trench isolation 202 is formed on a semiconductor substrate 201, and then a word line 203 is formed, and then a polysilicon film 204 is deposited, for example, at 800.degree. After that, a WSi (tungsten silicide) film 209 is deposited on the polysilicon film 204 at 5000 °. Then, FIG.
A photoresist film 205 is applied as shown in FIG.
The photoresist film 205 is patterned. Thereafter, as shown in FIG. 3C, the WSi film 209 is etched using the photoresist film 205 as a mask, the etching is stopped on the polysilicon film 204, and the local WSi pad 20 is removed.
7 is formed. Then, as shown in FIG. 3D, an oxide film is formed on the entire surface so as to cover the local WSi pad 207.
An oxide film sidewall 206a is formed on the side wall of the local WSi pad 207 by depositing the film between 00 and 4000 ° and etching back this oxide film. Then, FIG.
As shown in (e), the polysilicon film 204 is etched using the oxide film sidewall 206a as a mask to form a convex local WSi pad 200.

As described above, according to the manufacturing method of the second embodiment, the local pad of the semiconductor memory device is provided between the word lines and connects the bit line contact or the capacitance contact to the element region. In the method, after a device isolation region is formed on a semiconductor substrate, a first step of forming a word line, a polysilicon film 204 is formed over the entire surface, and a WSi film having a thickness greater than the thickness of the polysilicon film 204 is formed.
A second step of forming a film 209, and the WSi film 209;
A third step of applying a photoresist film 205 thereon and patterning the photoresist film 205; and using the photoresist film 205 as a mask to form the WSi film 2
09 to form a local pad portion 207, and an oxide film is formed on the entire surface, and this oxide film is etched back to form an oxide film sidewall 206a on the side wall of the local pad portion 207. A fifth step of forming
A sixth step of etching the polysilicon film 204 using the sidewalls 206a as a mask.

In each of the specific examples, the end of the polysilicon film is connected to the element isolation region 102 surrounding the element region 208,
202 overlaps the end.

[0017]

The local pad of the semiconductor memory device and the method of manufacturing the same according to the present invention have the following effects because they are configured as described above. (1) The element region is not damaged due to misregistration at the time of local pad formation, and the device characteristics are improved.

(2) Since it is not necessary to leave a hard mask of an oxide film on the local pad, it is not necessary to increase the thickness of the interlayer insulating film, and the uniformity within the wafer surface during CMP is improved. (3) Generation of voids in the interlayer insulating film between local pads can be reduced. (4) Since the thickness of the interlayer insulating film is small, opening of the contact is facilitated.

(5) The resistance of the local pad can be reduced by using the second specific example.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing step of a local pad of a semiconductor memory device according to the present invention.

FIG. 2 is a sectional view in a direction orthogonal to FIG.

FIG. 3 is a cross-sectional view showing another manufacturing step of the local pad of the semiconductor memory device according to the present invention.

FIG. 4 is a plan view showing an arrangement state of local pads of the semiconductor memory device.

FIG. 5 is a sectional view taken along line B-B 'of FIG.

FIG. 6 is a cross-sectional view showing a conventional manufacturing step taken along the line AA ′ of FIG. 4;

[Explanation of symbols]

 100, 200 Convex type local pad 101, 201 Semiconductor substrate 102, 202 Trench isolation 103, 203 Word line 104, 204 Polysilicon film 104a Remaining polysilicon film 105, 205 Photoresist 106, 206a Oxide film sidewall 107, 207 Local Pad section 108, 208 Element area 209 WSi film

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/108 H01L 21/8242

Claims (6)

(57) [Claims] 1. A semiconductor device, comprising: a word line;
In a local pad of a semiconductor memory device for connecting a bit line contact or a capacitance contact to an element region, a polysilicon film formed so that the local pad covers the element region, and a WS formed on the polysilicon film
A local pad of a semiconductor memory device comprising an i film and an oxide film sidewall formed on a side wall of the WSi film. 2. The local pad according to claim 1, wherein said polysilicon film is larger than said element region. 3. It is provided between a word line and a word line,
In a method for manufacturing a local pad of a semiconductor memory device for connecting a bit line contact or a capacitance contact to an element region, an element isolation region is formed on a semiconductor substrate, a word line is formed, and then a polysilicon film is formed on the entire surface. Then, the polysilicon film is etched into a predetermined shape to form a local pad portion, a sidewall is formed on a side wall of the local pad portion, and the remaining polysilicon film is further formed by using the sidewall as a mask. A method of manufacturing a local pad of a semiconductor memory device, characterized by etching a semiconductor device. 4. It is provided between a word line and a word line,
In a method of manufacturing a local pad of a semiconductor memory device for connecting a bit line contact or a capacitor contact to an element region, a first step of forming a word line after forming an element isolation region on a semiconductor substrate; A second silicon film is formed to a predetermined thickness.
A third step of applying a photoresist film on the polysilicon film and patterning the photoresist film; and etching the polysilicon film using the photoresist film as a mask to form a local pad portion. While forming
A fourth step of leaving a film thickness of a portion not covered with the mask to a predetermined film thickness and performing etching so that the film thickness of the remaining portion becomes smaller than the etched film thickness; Film an oxide film, etch back this oxide film,
A fifth step of forming a sidewall of an oxide film on a side wall of the local pad portion; and a sixth step of etching the remaining portion of the polysilicon film using the sidewall as a mask. Manufacturing method of a local pad of a semiconductor memory device. 5. A semiconductor device provided between a word line and a word line,
In a method for manufacturing a local pad of a semiconductor memory device for connecting a bit line contact or a capacitance contact to an element region, an element isolation region is formed on a semiconductor substrate, a word line is formed, and then a polysilicon film is formed on the entire surface. After that, a WSi film is formed, the WSi film is etched into a predetermined shape to form a local pad portion, a sidewall is formed on a side wall of the local pad portion, and the polysilicon is formed using the sidewall as a mask. A method of manufacturing a local pad of a semiconductor memory device, characterized by etching a silicon film. 6. A semiconductor device provided between a word line and a word line,
In a method of manufacturing a local pad of a semiconductor memory device for connecting a bit line contact or a capacitor contact to an element region, a first step of forming a word line after forming an element isolation region on a semiconductor substrate; A second step of forming a WSi film thicker than the polysilicon film after forming the silicon film; and a third step of applying a photoresist film on the WSi film and patterning the photoresist film. And a fourth step of etching only the WSi film using the photoresist film as a mask to form a local pad portion. An oxide film is formed on the entire surface, and the oxide film is etched back.
A fifth step of forming a sidewall of an oxide film on a side wall of the local pad portion; and a sixth step of etching the polysilicon film using the sidewall as a mask. A method for manufacturing a local pad of a device.