KR20020002602A - Method for forming bitline in semiconductor device - Google Patents

Abstract

PURPOSE: A method for forming a bit line of a semiconductor device is provided to prevent a lifting of the bit line due to thermal budget caused by overetch of a word line insulating layer in a corner cell region during the formation of the bit line. CONSTITUTION: After the word line insulating layer(33) is formed on a semiconductor substrate(31), several layers(35-38) for the bit line are formed thereon. The layers(35-38) are then selectively etched in the corner cell region by using a wafer edge exposure mask, and further selectively etched in a main cell region to form the bit line by using a bit line mask. Next, the first bit line insulating layer(41) with good gap-fill property is formed to supplement a part(33a) of the word line insulating layer(33) overetched in the corner cell region, and then the second bit line insulating layer(42a) with good step coverage property is formed thereon. Thereafter, the second bit line insulating layer(42a) is polished while preventing the lifting of the bit line.

Description

Method for forming bit line of semiconductor device {METHOD FOR FORMING BITLINE IN SEMICONDUCTOR DEVICE}

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for forming a bit line using a dual damascene process.

In general, the bit line forming method is made of polysilicon, tungsten silicide, and capping material, according to a design rule of mask oxide or mask nitride. It is formed by depositing and patterning it, and the metal resistive film is introduced to solve the problem that the specific resistance of polysilicon and tungsten silicide does not meet the requirements of increased device integration.

1A to 1D are diagrams illustrating a bit line forming method according to the prior art.

First, a word line insulating layer 13 is deposited on a semiconductor substrate 11 on which a predetermined process such as a word line (not shown) and an impurity bonding layer 12 is completed, and then the word line insulating layer 13 is selectively patterned to form the word line insulating layer 13. A plug contact hole for exposing the impurity bonding layer 12 is formed, and a bit line plug 14 for filling the contact hole is formed.

Subsequently, Ti / TiN is deposited as a diffusion barrier metal layer 15 for suppressing the reaction of the WF _{6 with} the semiconductor substrate 11 during deposition of a tungsten layer, and a metal interconnection layer on the diffusion barrier metal layer 15 is formed. 16) deposit tungsten.

Subsequently, an undoped silicon glass (USG) film is deposited as the buffer layer 17 to reduce the stress of the metallization layer 16 and the subsequent mask nitride layer, and a plasma enhanced deposition method or a low pressure deposition method is performed on the buffer layer 17. The mask nitride film 18 is deposited using low pressure deposition.

As shown in FIG. 1B, the mask nitride layer 18, the buffer layer 17, the metallization layer 16, and the diffusion barrier metal layer 15 are etched using a bit line mask to form a bit line. In order to suppress the occurrence of defects due to the metal wiring film that may remain in the wafer edge region, first, the mask nitride layer 18 and the buffer layer 17 of the wafer edge region are used by using a wafer edge exposure (WEE) mask 19. The metal wiring film 15 and the diffusion barrier metal film 15 are removed. At this time, the WEE mask 19 selectively opens only the 5 mm region of the wafer edge. That is, it opens by 5mm for Edge Bead Lining (EBR).

As shown in FIG. 1C, after removing the bit line forming films of the wafer edge region, patterning the bit line 19 using a bit line mask, the bit line sidewall spacer 20 in contact with the sidewall of the bit line. ). Subsequently, when the low-temperature USG film is deposited on the entire surface of the structure using the bit line insulating film 21, the bit line insulating film 21 is thinly deposited in the region 22 that is overlapped and opened in the WEE mask and the bit line mask process. That is, when the high density plasma oxide film having excellent gapfill characteristics is deposited in the low temperature USG film with the bit line insulating film 21, the bit line edge portion adjacent to the wafer edge is deposited and etched. The deposition thickness of the film becomes thin.

As shown in FIG. 1D, when the bit line insulating layer 21 is chemically mechanically polished to a target for remaining 2000 μs on the bit line mask nitride layer 18, that is, the chemical mechanical polishing of the bit line insulating layer 21 is performed. In the mechanical polishing (CMP) process, if the thickness of the insulating film on the mask nitride film 18 in the main cell region is adjusted to 2000Å, the mask nitride film 18 in the corner region is lost (23). There is a problem in that tungsten, which is a bit line wiring metal film, is lifted due to thermal budget.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and is a bit suitable for preventing the lifting phenomenon of the bit line wiring due to the thermal coagulation of the subsequent capacitor by the excessive etching of the word line insulating film of the corner cell region when forming the bit line wiring Its purpose is to provide a method of forming lines.

1A to 1D illustrate a method of forming a bit line according to the prior art;

2A to 2C illustrate a method of forming a bit line according to an exemplary embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

31 semiconductor substrate 32 impurity bonding layer

33: word line insulating film 34: bit line contact plug

35 metal diffusion prevention film 36 bit line wiring film

37: buffer layer 38: mask nitride film

39: bit line wiring 40: nitride film spacer

41: first bit line insulating film 42: second bit line insulating film

A bit line forming method of the present invention for achieving the above object comprises a first step of forming a word line insulating film on the semiconductor substrate after a predetermined process, and then forming a multi-layer film for bit line wiring on the word line insulating film; A second step of selectively etching the multilayer film for bit line wiring in a region where a subsequent corner cell region is to be formed using a WEE mask; Using a bit line mask to selectively etch the multilayer film for bit line wiring in a region where a subsequent center cell region is formed to form bit line wiring; A fourth step of forming a first bit line insulating film having excellent gap fill characteristics on the bit line wiring to compensate for the transient etching thickness of the word line insulating film in the region where the corner cell region is over-etched after the third step; A fifth step of forming a second bit line insulating film having an excellent layer covering property on the first bit line insulating film; And a sixth step of chemically mechanically polishing the second bit line insulating layer as a target for preventing lifting of the bit line wiring.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

2A to 2C are diagrams illustrating a bit line forming method according to an exemplary embodiment of the present invention.

As shown in FIG. 2A, after the word line insulating film 33 is formed on the semiconductor substrate 31 on which the predetermined process including the word line (not shown) and the impurity bonding layer 32 is completed, the word line insulating film ( 33) is selectively etched to form a plug contact hole through which the impurity bonding layer 32 is exposed. Subsequently, a bit line contact plug 34 embedded in the contact hole is formed.

Subsequently, any one of Ti, TiN, TiSi, WN, TaN, TiSiN, or TiAlN metal layers is formed on the bit line contact plug 34 and the word line insulating layer 33 by chemical vapor deposition. Deposition (CVD) or sputtering (Sputtering) method to deposit a thickness of 100 ~ 1000Å at 300 ℃ to 600 ℃, or a combination of the conductive layers are deposited.

Subsequently, a metal of any one of tungsten (W) or copper (Cu) as a bit line wiring film 36 on the metal diffusion barrier 35 is formed at 300 ° C to 600 ° C by chemical vapor deposition (CVD) or sputtering. It is deposited at a thickness of 500 kV to 2000 kV.

Subsequently, USG films such as PE-TEOS and PE-SiH ₄ are deposited at 300 占 폚 to 1000 占 퐉 at 300 占 폚 to 800 占 폚 as a buffer layer 37 for suppressing stress generation between the bit line interconnection film 36 and the subsequent mask nitride film. .

Next, Si _x N _y (x: y = 1: 1 to 5: 1) SiON as the mask nitride film 38 for protecting the bit line wiring film and the anti reflective coating layer (not shown) on the buffer layer 37. The nitride film of any one of Si-rich nitride is deposited at a low pressure (PE) or plasma (PE) method at a temperature of 300 to 3000 Å at 400 to 800 占 폚.

Subsequently, an anti-reflection film for bit line wiring, a mask nitride film 38, a buffer layer 37, a bit line wiring film 36, and a diffusion barrier 36 are etched using a WEE mask (not shown). At this time, the anti-reflection film is completely removed, and the word line insulating film 33 in the corner cell region is excessively etched by a predetermined depth.

Subsequently, when the bit line wiring 39 of the center cell region is patterned using the bit line mask, the word line insulating layer 33 in the region adjacent to the bit line wiring of the wafer edge is further etched by a predetermined depth. That is, the word line insulating layer 33 is excessively etched 33a in the region where the WEE mask and the bit line mask overlap.

Subsequently, a nitride film using a low pressure deposition method is deposited on the bit line wiring 39 at a thickness of 200Å to 700 ℃ at 300 ° C. to 800 ° C., and then the nitride film is etched entirely to contact the sidewall of the bit line wiring 40. To form.

As shown in FIG. 2B, a high-density plasma oxide film 41 having excellent gap fill characteristics is formed on the entire surface including the nitride film spacer 40 and the bit line wiring 39 based on argon (Ar) or helium (He) gas. Vapor deposition is carried out at 1000 to 4000 mm thickness at a temperature of 600 to 600 ° C.

Subsequently, any one of PE-TEOS, PE-SiH ₄ , LP-TEOS, or APL oxide film is 300 ° C. to 600 ° C. as the USG film 42 having excellent step coverage characteristics on the high density plasma oxide film 41. At a thickness of 3000Å to 8000Å.

As described above, when the high density plasma oxide film 41 and the USG film 42 are sequentially stacked as the bit line insulating film, the deposition thickness of the bit line insulating film deposited on the corner portion of the bit line wiring adjacent to the corner cell region is increased. You can.

As shown in FIG. 2C, the USG film 42 is chemically mechanically polished using a slurry maintained at a pH of 8 to 11 to which an abrasive of any one of 50 nm to 300 nm silica, alumina, or ceria is added. At this time, since the high density plasma oxide layer 41 is deposited first to compensate for the loss of the overetched word line insulating layer, the loss of the mask nitride layer in the adjacent region of the wafer edge is prevented. The thickness can be ensured by the thickness of 1000 mm 3.

As described above, the high-density plasma oxide film 41 and the USG film 42 are used as the bit line insulating film, and when the chemical mechanical polishing of the bit line insulating film is performed, the bit line wiring is formed on the mask nitride film of the bit line wiring adjacent to the wafer edge. A bit line insulating film having a thickness that can prevent the lifting of the film remains.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the bit line forming method of the present invention uses a high-density plasma oxide film having excellent gap fill characteristics and a USG film having excellent layer covering characteristics as a bit line insulating layer, thereby remaining on the upper part of the bit line wiring in the edge cell region during subsequent chemical mechanical polishing. The thickness of the bit line insulating layer can be increased to prevent the lifting of the bit line wiring.

Claims (9)

In the manufacturing method of a semiconductor device, A first step of forming a word line insulating film on the semiconductor substrate on which the predetermined process is completed, and then forming a multilayer film for bit line wiring on the word line insulating film; A second step of selectively etching the multilayer film for bit line wiring in a region where a subsequent corner cell region is to be formed using a WEE mask; Using a bit line mask to selectively etch the multilayer film for bit line wiring in a region where a subsequent center cell region is formed to form bit line wiring; A fourth step of forming a first bit line insulating film having excellent gap fill characteristics on the bit line wirings to compensate for the excessive etching thickness of the word line insulating film of the region where the corner cell region is over-etched after the third step; A fifth step of forming a second bit line insulating film having an excellent layer covering property on the first bit line insulating film; And A sixth step of chemical mechanical polishing the second bit line insulating film to prevent lifting of the bit line wiring; Bit line forming method characterized in that it comprises a. The method of claim 1, In the fourth step, The first bit line insulating film is a high-density plasma oxide film, and a method of forming a bit line, characterized in that the deposition of 1000 to 4000 mm thick at 300 ℃ to 600 ℃ based on argon or helium gas. The method of claim 1, In the fifth step, The second bit line insulating film is a bit line using a USG film of any one of a PE-TEOS, PE-SiH ₄ , LP-TEOS, or APL oxide film, and is deposited at a thickness of 3000 Pa to 8000 Pa at 300 ° C to 600 ° C. Method of formation. The method of claim 1, In the sixth step, And a slurry maintained at a pH of 8 to 11 to which an abrasive of any one of 50 nm to 300 nm silica, alumina or ceria is added during chemical mechanical polishing of the second bit line insulating film. The method of claim 1, The first step is, Forming a contact hole by selectively etching the word line before forming the multilayer film for the bit line wiring, and then forming a bit line contact plug embedded in the contact hole; And Sequentially forming a diffusion barrier layer, a wiring metal layer, a buffer layer, a mask nitride layer, and an antireflection layer on the bit line contact plug. Bit line forming method characterized in that it comprises a. The method of claim 5, The diffusion barrier layer is any one of a metal layer of Ti, TiN, TiSi, WN, TaN, TiSiN or TiAlN, using a chemical vapor deposition method or sputtering method to deposit a thickness of 100 ~ 1000Å at 300 ℃ ~ 600 ℃, or And depositing the metal layers in combination. The method of claim 5, The wiring metal film may be formed of any one of tungsten or copper, and is deposited using a chemical vapor deposition method or sputtering at a thickness of 500 kPa to 2000 kPa at 300 占 폚 to 600 占 폚. The method of claim 5, Wherein the buffer layer using a USG film of any one of PE-TEOS or PE-SiH ₄ , the method of forming a bit line, characterized in that deposited at 300 ~ 1000Å thickness at 300 ℃ ~ 800 ℃. The method of claim 5, The mask nitride film may be formed of a nitride film of any one of Si _x N _y (x: y = 1: 1 to 5: 1), SiON, and silicon sub-nitride film. A method of forming a bit line, characterized in that the deposition to a thickness.