KR20000050330A - Method for forming contact of semiconductor device - Google Patents

Abstract

PURPOSE: A contact forming method of a semiconductor device is to prevent a contact fail generated as a void is exposed to an upper surface of a substrate. CONSTITUTION: A first insulating film(110), a second insulating film(112), and a third insulating film(114) are deposited in this sequence on a semiconductor substrate(100) with a lower conductive region(105,108) formed thereon. A mask pattern is then formed on the third insulating film to form a contact hole. A first contact hole is then formed by etching the third insulating film and the second insulating film by using the mask pattern. The mask pattern is partially etched in its thickness. An expanded first contact hole(118a) is formed by etching the third insulating film by using the mask pattern. A second contact hole(120a,120b) are formed by etching the first insulating film by using the second insulating film as a mask to expose the lower conductive region. After removing the mask pattern, a first metal film is disposed on the entire surface of the substrate to fill the second contact holes and the expanded first contact hole. A contact plug(124a,124b) are then formed by partially removing the first metal film. A metal line(126) is formed to be electrically connected to the contact plugs by depositing and patterning a second metal film overall surface of the substrate.

Description

TECHNICAL FOR FORMING CONTACT OF SEMICONDUCTOR DEVICE

The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming a contact of a semiconductor device.

In forming a contact of a semiconductor device, in particular, in forming a contact of a DRAM device, a process of filling a contact hole with a metal film becomes difficult as the aspect ratio of the contact hole increases. As a result, the metal film filling the contact hole is replaced with a tungsten (W) film having better step coverage than the conventional aluminum (Al) film.

1A through 1E are flowcharts sequentially illustrating processes of a method for forming a contact of a conventional semiconductor device.

Referring to FIG. 1A, a method of forming a contact of a conventional semiconductor device is first formed as a device isolation to define an active region and an inactive region on a semiconductor substrate 2. A trench isolation 4 is formed.

A transistor 6 is formed on the active region. The transistor 6 includes a gate electrode 7, a gate mask 8, a gate spacer 9, and a source / drain region 10. It includes.

The insulating layer 12 is deposited on the entire surface of the semiconductor substrate 2 including the transistor 6.

In FIG. 1B, after the photoresist pattern 14 for forming a contact hole is formed on the insulating layer 12, the insulating layer 12 is etched using the photoresist pattern 14 as a mask. Contact holes 16a and 16b are formed.

The contact holes 16a and 16b include a contact hole 16a formed to expose the source / drain region 10 and a contact hole 16b formed to expose the gate electrode 8.

Referring to FIG. 1C, after the photoresist pattern 14 is removed, a barrier metal layer 18 is formed on the insulating layer 12 including the contact holes 16a and 16b, for example. , Ti / TiN film is deposited within a thickness range of 100 kPa to 900 kPa. Next, a tungsten film 20 is deposited on the barrier metal film 18 in a thickness range of 3000 kPa to 6000 kPa so that the contact holes 16a and 16b are completely filled.

However, even when the contact holes 16a and 16b are filled with a tungsten film having better step coverage than the aluminum film, as shown in FIG. 1C in the case of the contact holes 16a and 16b having a high aspect ratio, The voids 21 are generated in the contact holes 16a and 16b.

The tungsten film 20 is etched by an etchback process so that the barrier metal films 18 on both sides of the contact holes 16a and 16b are exposed. As shown in FIG. 1D, the contact plugs 20a and 20b are exposed. ) Is formed.

After the aluminum film is deposited on the barrier metal film 18 including the contact plugs 20a and 20b, as shown in FIG. 1E, the contact plugs are patterned together with the barrier metal film 18 to form the contact plug. An aluminum line 22 is formed which is electrically connected to the 20a and 20b.

However, during the etch back process for forming the contact plugs 20a and 20b, the voids 21 are exposed on the surface and are formed on the lower surfaces of the contact holes 16a and 16b as shown by reference numeral 24 of FIG. 2. The barrier metal layer 18 is etched to generate contact failures between the contact plugs 20a and 20b and the gate electrodes 7 to 20a and 20b and the source / drain regions 10.

In addition, after forming the contact plugs 20a and 20b, when patterning the aluminum line 22 to be formed, a misalign margin with the contact plugs 20a and 20b is insufficient, as shown by reference numeral 26 of FIG. 3. The contact failure of the contact plugs 20a and 20b and the aluminum line 22 occurs.

The present invention has been proposed to solve the above-mentioned problems, can suppress the generation of voids, prevent the exposure of the voids during the etching process for forming the contact plug, overlapping with the contact plug when forming the metal line It is an object of the present invention to provide a method for forming a contact of a semiconductor device capable of improving a margin margin.

1A to 1E are flowcharts sequentially showing processes of a method for forming a contact of a conventional semiconductor device;

2 and 3 are cross-sectional views illustrating problems caused when forming contacts in a conventional semiconductor device, respectively;

4A through 4G are flowcharts sequentially illustrating processes of a method for forming a contact of a semiconductor device according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

2, 100: semiconductor substrate 4, 102: trench isolation

6, 104 transistor 12: insulating film

14 and 116 photoresist patterns 16a and 16b contact holes

18, 122: barrier metal film 20, 124: tungsten film

21: void 20a, 20b, 124a, 124b: contact plug

22, 126: aluminum line 110: first insulating film

112: second insulating film 114: third insulating film

118: first contact hole 118a: expanded first contact hole

120a, 120b: second contact hole

(Configuration)

According to the present invention for achieving the above object, in the contact forming method of a semiconductor device, a first insulating film, a second insulating film, and a third insulating film is deposited on a semiconductor substrate having a lower conductive region, the second insulating film Depositing a material having an etch selectivity with respect to the first insulating film and the third insulating film; Forming a mask pattern for forming a contact hole on the third insulating layer; Forming a first contact hole by sequentially etching the third insulating film and the second insulating film using the mask pattern; Etching a part thickness of the mask pattern; The mask pattern is used again to etch a third insulating film on both sidewalls of the first contact hole to form an extended first contact hole, wherein the second insulating film is used as an etch stop layer, and at the same time, the lower conductive region. Forming a second contact hole by etching the first insulating layer under the first contact hole to expose the second contact hole, wherein the second insulating layer is used as a mask; Removing the mask pattern; Depositing a first metal film on an entire surface of the semiconductor substrate to fill the second contact hole and the extended first contact hole; Forming a contact plug by removing the first metal film in the remaining area such that the first metal film remains only in the second contact hole and the extended first contact hole; And depositing and patterning a second metal film on the entire surface of the semiconductor substrate to form a metal line electrically connected to the contact plug.

(Action)

Referring to FIG. 4G, the contact forming method of the novel semiconductor device according to the embodiment of the present invention selectively extends the opening of the contact hole by using a multilayer insulating film having an etch selectivity. As a result, the deposition process of the metal film in the contact hole can be facilitated, and the voids can be prevented from being exposed during the etch back process for forming the contact plug, thus preventing contact fail due to the void exposure. In addition, as the opening of the contact hole is expanded, an overlap margin of the contact plug and the metal line may be improved.

(Example)

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 4.

4A through 4G are flowcharts sequentially illustrating processes of a method for forming a contact of a semiconductor device according to an embodiment of the present invention.

Referring to FIG. 4A, a method for forming a contact in a semiconductor device according to an embodiment of the present invention may first include device isolation, for example, trench isolation 102, to define active and inactive regions on a semiconductor substrate 100. Is formed.

Transistor 104 is formed on the active region. The transistor 104 includes a gate electrode 105, a gate mask 106, a gate spacer 106, and a source / drain region 108.

The first insulating layer 110 is deposited on the entire surface of the semiconductor substrate 100 including the transistor 104. A second insulating layer 112 having an etch selectivity with the first insulating layer 110 is deposited on the first insulating layer 110. Subsequently, a third insulating layer 114 having an etch selectivity with the second insulating layer 112 is deposited on the second insulating layer 112.

For example, the first and third insulating layers 110 and 114 are formed of the same material.

Preferably, the first and third insulating films 110 and 114 are formed of an oxide film, for example, a PTEOS film or an O3-TEOS film, and are deposited within a thickness range of 1000 kPa to 7000 kPa. In addition, the second insulating film 112 is formed of a nitride film and is deposited within a thickness range of 1000 kPa to 5000 kPa.

In FIG. 4B, a photoresist pattern 116 for forming a contact hole is formed on the third insulating layer 114. Using the photoresist pattern 116 as a mask, the third insulating layer 114 and the second insulating layer 112 are sequentially etched by an anisotropic etching process to form a first contact hole 118 having a width of 'a'. do.

After the photoresist pattern 116 is etched by, for example, an isotropic etching process and expanded to have a width 'b', the third insulating layer 114 and the photoresist pattern 116 are used again as a mask. The first insulating layer 110 is etched by an anisotropic etching process. Then, as shown in FIG. 4C, the extended first contact hole 118a and the second contact holes 120a and 120b connected to the lower portion of the extended first contact hole 118a are formed.

The second contact holes 120a and 120b include a contact hole 120a formed to expose the source / drain region 108 and a contact hole 120b formed to expose the gate electrode 105.

In forming the extended first contact hole 118a and forming the second contact hole 120a and 120b, the second insulating layer 112 is used as an etch stop layer and an etch mask, respectively.

The extended first contact hole 118a formed as described above corresponds to an opening of the conventional contact hole, and the second contact holes 120a and 120b correspond to a lower portion of the conventional contact hole. In this case, the expanded first contact hole 118a is larger than the opening of the conventional contact hole by the expanded width, and the second contact holes 120a and 120b are equal to the width of the lower portion of the conventional contact hole.

As described above, since the opening of the contact hole is extended than before, the process of filling the contact hole with the metal film is facilitated, and the contact failure caused by the exposure of the void generated when forming the contact plug is prevented.

After the photoresist pattern 116 is removed (FIG. 4D), the barrier metal is formed on the third insulating layer 114 including the second contact holes 120a and 120b and the extended first contact hole 118a. The film 122 is deposited. The barrier metal film 122 is, for example, deposited as a Ti / TiN film within a thickness range of 100 kPa to 1000 kPa.

A first metal film 124, for example, a tungsten film 124, is formed on the barrier metal film 122 so that the second contact holes 120a and 120b and the extended first contact hole 118a are completely filled. Is deposited. The tungsten film 124 is deposited in a thickness range of 2000 kV to 6000 kV. In this case, voids may be generated in the second contact holes 120a and 120b, but the voids are formed at a depth that is not exposed during an etch back process for forming a subsequent contact plug.

In FIG. 4F, the tungsten film 124 is etched by an etch back process so that the barrier metal film 122 on the third insulating film 114 on both sides of the extended first contact hole 118a is exposed. , 124b).

After the aluminum film including the contact plugs 124a and 124b is deposited on the barrier metal film 122, which is a metal film having a lower resistance than the tungsten film, the aluminum film is patterned together with the barrier metal film 122. As shown in 4g, an aluminum line 126 is formed. The aluminum film is deposited in a thickness range of, for example, 2000 kPa to 6000 kPa.

At this time, as the opening of the contact hole is expanded, the overlap margin between the contact plugs 124a and 124b and the aluminum line 126 when the aluminum line 126 is formed is further improved than before, and the contact fail due to misalignment is a conventional problem. To contact failing as the void is exposed is prevented. In this case, the etching selectivity of the aluminum film and the tungsten film is maintained at 20: 1 or more.

The present invention extends the opening of the contact hole by using a multilayer insulating film having an etch selectivity, thereby preventing the voids from being exposed when forming the contact plug, thus preventing contact fail due to the void exposure.

In addition, as the opening of the contact hole is expanded, an overlap margin between the contact plug and the metal line may be improved.

Claims (3)

The first insulating layer 110, the second insulating layer 112, and the third insulating layer 114 are deposited on the semiconductor substrate 100 on which the lower conductive regions 105 and 108 are formed, and the second insulating layer 112 is deposited. Depositing a material having an etch selectivity with respect to the first insulating film 110 and the third insulating film 114; Forming a mask pattern 116 on the third insulating layer 114 to form contact holes; Forming a first contact hole (118) by sequentially etching the third insulating film (114) and the second insulating film (112) using the mask pattern (116); Etching a portion thickness of the mask pattern 116; The mask pattern 116 is used again to etch the third insulating layer 114 on both sides of the first contact hole 118 to form an extended first contact hole 118a, wherein the second insulating layer 112 is formed. Is formed using an etch stopping layer, At the same time, the first insulating layer 110 under the first contact hole 118 is etched to expose the lower conductive regions 105 and 108 to form second contact holes 120a and 120b. Forming using 112 as a mask; Removing the mask pattern 116; Depositing a first metal film (124) on the entire surface of the semiconductor substrate (100) to fill the second contact holes (120a, 120b) and the extended first contact holes (118a); The contact plug is removed by removing the first metal layer 124 in the remaining area so that the first metal layer 124 remains only in the second contact holes 120a and 120b and the extended first contact hole 118a. Forming 124a, 124b; And Depositing and patterning a second metal layer on the entire surface of the semiconductor substrate 100 to form metal lines 126 electrically connected to the contact plugs 124a and 124b. Contact formation method. The method of claim 1, Wherein the first and third insulating films (110, 114) are formed of an oxide film, and the second insulating film (112) is formed of a nitride film. The method of claim 1, The etching of the part thickness of the mask pattern 116 may be performed by an anisotropic etching process.