JPH0582472A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the contact holes at high aspect ratio to be buried evenly by a method wherein a conductive film containing W is formed in the first contact hole and nearby part thereto and after depositing an insulating film, the W is buried in the second contact hole by selective CVD-tungsten process. CONSTITUTION:The first contact hole 6 is made in the NSix layer 2B of a gate electrode 2 on an N<+> Si layer 3 and a P<+> Si layer 4. Next, P point and BF2 irons are respectively implanted in the N<+> Si layer 3 and the P<+> Si layer 4 using photoresist as a mask. Next, WSi2 is etched on a leading-out electrode 9. Next, a deposited insulating film 10 is etched to lead out WSi2 to make the second contact hole in the leading-out electrode 9. Next, a selective CVD tungsten layer 12 is grown; a TiW 13 is sputtered; tungsten 14 is grown on the whole surface; and finally, the tungsten layer 12 and the TiW 13 on the interlayer insulating film 10 are removed. Through these procedures, a favorable buried shape and the contact characteristics can be dis-played.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More specifically, the present invention relates to a method of forming an electric conduction part.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor devices, the diameter of contact holes has become finer, and the depth-to-diameter ratio (aspect ratio) of the contact holes has become larger and larger. Then, it has become difficult to coat the wiring material even inside the contact hole.
As a solution to this problem, conventionally, there is a chemical vapor deposition method (hereinafter referred to as a CVD method) of a refractory metal such as tungsten. The CVD method includes a selective growth method and a blanket growth method.
In the selective growth CVD method, tungsten is grown in the contact hole by utilizing the property that it does not grow on the insulating film but grows only on Si, silicide or metal by appropriately selecting the conditions. The embedded aspect ratio is reduced. In the overall growth method, it is possible to cover the adhesion layer such as Ti, TiW, or WSix in advance by the sputtering method, and then grow tungsten over the entire surface to fill the contact hole.

[0003]

However, the contact layer is indispensable not only as a contact between tungsten and the insulating film but also as a barrier metal for suppressing the erosion of Si during the growth of tungsten. As the aspect ratio of the hole becomes higher, it becomes difficult to cover the bottom portion of the contact hole with a necessary amount of the adhesion layer by a conventional thin film forming method by sputtering. It is said that the limit of the aspect ratio of the contact to which the whole surface growth method can be applied is about 2.5. Next, also when the tungsten is buried in the contact by the selective growth method, the erosion of the underlying Si causes the junction leak. Also, the higher the aspect ratio of the contact,
That is, the thicker the insulating film, the greater the amount of Si overetch due to the variation in contact etching. This also causes a junction leak. In recent years, as the miniaturization of LSI has progressed and the aspect ratio of contact holes has become higher, the above problems cannot be ignored.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a semiconductor device in which a contact hole having a high aspect ratio can be uniformly filled.

[0005]

According to the present invention, a thin insulating layer is formed on a silicon substrate, the insulating layer is etched to open a first contact hole, and W is formed in the opening and its vicinity. After forming a conductive film to be contained and depositing an insulating film, a second contact hole is opened and selective CVD is performed in this opening.
There is provided a method for manufacturing a semiconductor device, which comprises burying W by a tungsten method or a full-face CVD-tungsten method to form wiring.

In the method of manufacturing a semiconductor device of the present invention,
As a semiconductor substrate for wiring, a predetermined element such as an element isolation region, a gate electrode having a laminated structure of a WSix layer and a poly-Si layer, an N ⁺ Si layer, and a P ⁺ S layer are prepared in advance.
What formed the element etc. which consist of i layer can be used. Next, when forming the wiring, a thin insulating layer is formed. As a forming method, it is usually formed by a CVD method and its layer thickness is 0.02 to 0.1 μm.

Further, the insulating layer is etched to form a first layer.
Forming contact holes. The etching method is etching using a photolithography method. If the layer thickness of the insulating layer is 0.02 to 0.03 μm, the contact hole may be opened by low-damage isotropic dry etching or wet etching. Therefore, a good contact can be formed.

A tungsten compound is sputtered on the silicon substrate to form a W-containing conductive film with a film thickness of 0.03 to 0.05 μm. WSi as the tungsten compound
_2, etc., but the material is not particularly limited as long as it is a material that can withstand the high temperature annealing at the time of forming the W-containing conductive film and forming the second insulating film. Next, by etching the W-containing conductive film,
The first contact hole and its vicinity are processed into a lead electrode shape so as not to be electrically connected to the electrode of the adjacent contact at this time.

On the other hand, if the selective CVD-tungsten method is used as the method of forming the W-containing conductive film, W can be grown only in the opened first contact hole.
There is an advantage that the number of sputtering and etching steps is reduced as compared with the method of forming a contained conductive film. Next, an insulating layer is formed by, for example, the CVD method. The film thickness at this time is 0.5 to
The thickness is 1.5 μm, and examples of the material for the insulating layer include SiO ₂ .

Further, the insulating layer is etched to form a second contact hole on the lead electrode of the W-containing conductive film. At this time, it is desirable that the second contact hole is smaller than the first contact hole. After this, the second contact hole is selectively CVD-tungsten method or whole surface CV.
Embedding with tungsten by the D-tungsten method.

The CVD-tungsten method may be carried out under the conditions known in the art. When the selective CVD-tungsten method is used, for example, a substrate placed in a CVD apparatus is heated to 250 ° C. to 350 ° C.
The flow rate ratio of F ₆ / SiH ₄ is 30/24 to 30/16, the pressure is 0.01 to 0.12 Torr, and tungsten is usually deposited in the contact hole to a thickness of 0.5 to 1.5 μm. It is possible.

When using the full-face CVD-tungsten method,
For example, the adhesion layer is 0.05 to 0.1 μm by the sputtering method.
Then, tungsten is deposited on the adhesion layer, and a substrate placed in a CVD apparatus is heated to 380 ° C. to 450 ° C.,
WF ₆ / H ₂ at a flow rate of 450/65 to 520/80 sccm and a pressure of 70 to 90 Torr is usually 0.4.
It is possible to deposit with a thickness of ˜0.7 μm to completely fill the contact holes.

The adhesion layer used in the above method is T
i, TiW and the like. Next, the tungsten on the insulating film can be etched to form a contact buried plug. A semiconductor device can be manufactured by forming a wiring after forming a tungsten plug.

[0014]

Since the conductive film containing W is formed in the first contact hole, it becomes a barrier metal when tungsten is grown by the selective CVD method or the full-scale CVD method in the subsequent step, and the erosion of the underlying Si is suppressed and the junction is formed. Suppress the generation of leak current. Since the WSi ₂ extraction electrode may be processed so as not to be electrically connected to the electrode of the adjacent contact, even if the alignment for forming the second contact hole is slightly misaligned, it is still on the WSi ₂ electrode, so that the photolithography alignment margin is large. Become. From this, a good buried shape and good contact characteristics can be obtained in a high contact hole.

When the conductive film containing W is formed by the selective CVD-tungsten method, it is not necessary to process the film after sputtering, and the photolithography and etching steps are reduced. Further, since the contact area between the conductive film and the Si substrate can be made large, the contact resistance can be reduced.

[0016]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

Example 1 A method of manufacturing a semiconductor device using the above-described method for embedding a contact in SRAM will be described.

As shown in FIG. 1A, a device isolation region 1, a WSix layer 2B and a poly-Si are formed on a silicon substrate 15.
Gate electrode 2 and N ⁺ Si layer 3 each having a layered structure of layer 2A
After forming the element composed of the P ⁺ Si layer 4 and
A μm interlayer insulating film (SiO ₂ ) 5 is deposited by the CVD method. This interlayer insulating film is etched by photolithography to form a first contact hole 6 on the N ⁺ Si layer 3 and the P ⁺ Si layer 4 and on the WSix layer 2B of the gate electrode 2. The diameter of each contact hole is 0.4 μm,
The depth on the N ⁺ , P ⁺ Si and the WSix layer is 0.1 μm. Next, the silicon substrate is immersed in 1% buffered hydrofluoric acid for 45 seconds to remove the native oxide film on the element, and then WSi
₂ 7 is deposited by 0.05μm sputtering method.

As shown in FIG. 3B, masking with a photoresist is performed, and P ions are 3 × 10 ¹⁵ ions on the N ⁺ Si layer 3.
/ Cm ² , with an accelerating voltage of 40 kev, P ⁺ Si layer 4
BF ₂ ions are implanted on the top at 5 × 10 ¹⁵ ions / cm ² and an acceleration voltage of 30 kev.

As shown in (c), WSi ₂ is etched on the extraction electrode 9. It may be processed so as not to be electrically connected to the adjacent contact electrode.

As shown in (d), the insulating film 1 having a thickness of 1.2 μm
0 is deposited, the insulating layer is etched, WSi ₂ is drawn out, and a second contact hole 11 having a diameter of 0.3 μm is opened on the electrode 9.

As shown in (e), the deposition temperature is 270 ° C., the pressure is 0.02 Torr, the flow rates of WF ₆ and SiH ₄ are 10 sccm and 8 sccm, respectively, and selective CVD tungsten for 400 seconds until the contact is filled with 1.2 μm. The layer 12 was grown.

As shown in (f), TiW 13 is added to 0.1 μm.
m sputter, substrate temperature 430 ° C., pressure 80 Tor
r, WF ₆ and H ₂ flow rates are 500 sccm and 75 sccm, respectively, and 0.4 μm thick tungsten 14 is grown over the entire surface in 60 seconds, followed by etching back to remove tungsten and TiW on the interlayer insulating film and contact The embedded plug is completed.

Example 2 As shown in FIG. 2A, after forming an element composed of an element isolation region 1, an N ⁺ Si layer 3 and a P ⁺ Si layer 4 on a silicon substrate, a 0.05 μm interlayer insulation film was formed. Membrane (SiO ₂ ) 5
Is deposited by the CVD method and wet-etched by the photolithography method to open the first contact hole 6. The contact hole diameter is 0.6 μm and the depth is 0.05 μm.

As shown in (b), Si having a film thickness of 0.05 μm and having W exposed by using the selective CVD-tungsten method.
Only grow on.

As shown in (c), a mask of a photoresist is used and P ions on the N ⁺ Si layer 3 are 3 × 10 ¹⁵ ions /
cm ^{2 at} an accelerating voltage of 40 kev, and BF ₂ ions are implanted on the P ⁺ Si layer 4 at 5 × 10 ¹⁵ ions / cm ^{2 at} an accelerating voltage of 30 kev.

As shown in (d), the insulating film 1 having a thickness of 1.2 μm
0 is deposited, the insulating layer is etched, and a second contact hole 11 having a diameter of 0.3 μm is formed on the W electrode 16.

As shown in (e), the deposition temperature is 270 ° C., the pressure is 0.02 Torr, the flow rates of WF ₆ and SiH ₄ are 10 sccm and 8 sccm, respectively, and selective CVD tungsten for 400 seconds until the contact is filled with 1.2 μm. The layer 12 was grown.

As shown in (f), TiW 13 is added to 0.1 μm.
m sputter, substrate temperature 430 ° C., pressure 80 Tor
r, WF ₆ and H ₂ flow rates are 500 sccm and 75 sccm, respectively, and 0.4 μm thick tungsten 14 is grown over the entire surface in 60 seconds, followed by etching back to remove tungsten and TiW on the interlayer insulating film and contact The embedded plug is completed.

[0030]

As described in detail above, according to the present invention, a good embedding shape and good contact characteristics can be obtained in a contact hole having a high aspect ratio.

[Brief description of drawings]

FIG. 1 is an explanatory view of a manufacturing process of a semiconductor device showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory view of the manufacturing process of the semiconductor device showing the configuration of the embodiment of the present invention.

[Explanation of symbols]

1 element isolation region 2 gate electrode 2A poly-Si layer 2B WSix layer 3 N ⁺ Si layer 4 P ⁺ Si layer 5 interlayer insulating film 6 first contact hole 7 sputtered WSi ₂ layer 8 photoresist 9 WSi ₂ extraction electrode 10 interlayer insulating Film 11 Second contact hole 12 Selective CVD-W 13 TiW 14 Full surface CVD-W 15 Silicon substrate 16 W electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiyo Nakamura 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture

Claims (3)

[Claims] 1. A thin insulating layer is formed on a silicon substrate,
This insulating layer is etched to open a first contact hole, a conductive film containing W is formed in the opening and the vicinity thereof, and after depositing an insulating film, a second contact hole is opened.
Selective CVD-tungsten method or blanket CVD is applied to this opening.
-A method for manufacturing a semiconductor device, which comprises burying W by a tungsten method to form wiring. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the formation of the conductive film containing W in the opening of the first contact hole and in the vicinity thereof is performed by etching after sputtering a tungsten compound. .. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the formation of the conductive film containing W in the opening of the first contact hole and in the vicinity thereof is performed by a selective CVD-tungsten method.