JPH06132246A - Contact hole buried structure and contact hole burying method - Google Patents

Abstract

PURPOSE:To materialize the formation of multilayer wiring, where the electric conductivity can be obtained easily and Al wiring is flattened, by buring fine contact holes different in depth flatly. CONSTITUTION:Contact holes 4, 1/2 or more in aspect ratio and the same in diameter, are formed by performing ordinary exposure, development, and etching processes after forming an insulating layer 3 to cover an Si device layer 1 or lower-layer wiring 2, and a core forming layer (Si film) 6 is formed for a substrate, where a resist film 5 remains left, by selective CVD process. Next, the resist film 5 is removed, and Al 7 is stacked on the side and the bottom of a contact hole 4 by selective CVD so as to bury the contact hole 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring of an integrated circuit, and more particularly to a contact hole burying structure having the same diameter and different depth, and a burying method thereof.

[0002]

2. Description of the Related Art In the case of an LSI in which a coating type insulating film is used for planarization, the thickness of the insulating film is different between the area where the lower layer wiring is dense and the area where it is not dense. There is a case where the depth of the contact hole for each contact hole is different for each contact hole.

In order to fill the contact holes having different depths, conventionally, a blanket CVD is used to form a film of polysilicon or W conformally. However, since the resistance is high, a film formed on the entire surface of the substrate. Need to be etched back to the upper surface of the contact hole, which is complicated and the number of steps must be increased.

As a selective growth method using chemical vapor deposition, fall 1986, Japan Society of Applied Physics, No. 30a-N-1
0 fills the contact hole with W,
Proceedings of 8th Conference on Solid State Materials, 755-75
Triisobutylaluminum ((i
-C ₄ H ₅₎ 3Al) selective growth method of Al was used as a raw material have been reported. According to these, if the parameters such as the flow rate of the raw material and the substrate temperature are appropriately selected, the metal can be deposited only on the silicon exposed surface due to the difference in chemical activity between the insulating film and the silicon exposed surface.

[0005]

However, since the selectively growing surface is exposed only at the bottom surface of the contact hole, when a contact hole having a different depth is to be filled, the shallower the contact hole, the faster the filling. Be done. Therefore, even if the shallow contact hole can be filled up to the upper surface, at the same time, the deep contact hole cannot be filled up, and if the deep contact hole is filled up to the upper surface, the shallow contact hole has a problem that the deposit rises. .

An object of the present invention is to provide a contact hole burying structure and a burying method for burying fine contact holes having different depths in planarization.

[0007]

In order to achieve the above object, a contact hole burying structure according to the present invention is a contact hole burying structure having a nucleation layer and a burying metal, and the nucleation layer comprises: The embedded metal provided on the bottom and side walls of the contact hole is Al embedded inside the contact hole.

The contact hole burying structure according to the present invention is a contact hole burying structure having a barrier metal or polysilicon layer, a nucleation layer and a burying metal, and the barrier metal or polysilicon layer is a contact hole. The nucleation layer is provided on the side wall of the contact hole, and the buried metal is Al buried inside the contact hole.

The contact hole filling method according to the present invention is a contact hole filling method including a contact hole forming step, a nucleation layer forming step, and an Al depositing step. After forming the insulating layer that covers the Si device layer or the lower wiring, the normal exposure, development and etching processes are performed to obtain an aspect ratio of 1
/ 2 or more contact holes having the same diameter are formed. In the nucleation layer forming step, the nucleation layer is formed on the bottom and side walls of the contact hole by selective CVD while leaving the resist film on the insulating layer. In the Al deposition step, after removing the resist film, Al is selectively deposited on the side surface and the bottom surface of the contact hole by the selective CVD process.

A contact hole filling method according to the present invention is a contact hole filling method including a contact hole forming step, a nucleation layer forming step, a nucleation layer removing step, and an Al depositing step. In the contact hole forming process, after forming an insulating layer and a resist film for covering the Si device layer or the lower layer wiring, a normal exposure / development /
Etching / resist stripping treatment is performed to expose the insulating film to form contact holes having the same diameter with an aspect ratio of 1/2 or more. The nucleation layer forming step includes the contact holes by selective CVD treatment. The nucleation layer is formed on the entire surface of the insulating film, and the nucleation layer removing step removes the nucleation layer on the insulating film surface and the bottom surface of the contact hole by anisotropic etching. By selective CVD processing, Al is selectively deposited on the side surface and the bottom surface of the contact hole.

[0011]

[Function] In order to uniformly fill a plurality of contact holes having different depths and the same diameter up to the upper surface of the contact hole, a thin nucleation layer for starting deposition is formed not only on the bottom surface of the contact hole but also on the side surface. Thus, the deposition starts from the bottom surface and the side surface of the contact hole. In CVD where the deposition rate has no anisotropy, it is considered that the difference in the film formation start time due to the difference in the surface material between the initial side wall and the bottom surface of the contact hole is small, and after Al as the embedded metal is deposited, It is considered that there is almost no difference between the deposition rate from the side wall of the contact hole and the deposition rate from the bottom surface of the Al surface.

As for the deposition from the side wall of the contact hole, the contact hole can be buried by depositing up to a film thickness of half the diameter of the contact hole. On the other hand, when depositing from the bottom of the contact hole, in order to fill the contact hole, it is necessary to deposit up to the film thickness corresponding to the depth. When the aspect ratio is 1/2, that is, the distance between the side wall of the contact hole and the center of the contact hole is equal to the distance between the bottom surface of the contact hole and the position directly above the contact hole, the contribution of growth from the side surface to the deposition is considered. It is considered that the contribution of growth from the bottom surface becomes equal.

However, when the aspect ratio is larger than 1/2, the contribution of the growth from the side surface of the contact hole to the deposition is larger than the contribution of the growth from the bottom surface of the contact hole. If the diameter is the same, it can be filled by depositing from the side wall of the contact hole, and contact holes having the same diameter with different depths can be filled at the same time.

[0014]

The present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing Embodiment 1 of the present invention in the order of steps. First, as shown in FIG. 1A, an insulating layer 3 covering the Si device layer 1 and the lower wiring 2 is formed.
After the formation, the normal exposure / development / etching steps are performed to form the contact holes 4 having the same diameter and an aspect ratio of ½ or more. In this case, there is a difference in the thickness of the insulating film 3 between the portion where the lower layer wiring 2 has a narrow gap and the portion where the gap is wide, so that the depth of the contact hole 4 formed is different.

Next, as shown in FIG. 1 (b), S that is a nucleation layer is added to the substrate on which the resist film 5 is still formed.
When the i thin film 6 is formed by CVD with good step coverage, the Si thin film 6 is formed on the inner surface of the contact hole 4 and the surface of the resist film 5.

Next, as shown in FIG. 1C, when the resist film 5 is removed by a usual resist ashing and organic stripping process, only the bottom surface and the side surface of the contact hole 4 are S.
The surface of the insulating film 3 other than the contact hole 4 is covered with the i thin film 6 and the Si thin film 6 is not present. Since the surface of the Si thin film 6 formed on the bottom surface and the side surface of the contact hole 4 is oxidized when exposed to the atmosphere, the natural oxide film is removed with dilute hydrofluoric acid before being introduced into the CVD apparatus.

Next, using a low pressure CVD apparatus, a total pressure of 2 To
When selective CVD is performed for 2 minutes under the setting conditions of rr, hydrogen carrier 60 sccm, and DMAH (dimethylaluminum hydride) 0.2 Torr, contact holes 4 having different depths are made of Al7 and are directly above the contact holes as shown in FIG. 1 (d). Embedded up to.

(Embodiment 2) FIG. 2 is a sectional view showing Embodiment 2 of the present invention in the order of steps. First, as shown in FIG. 2A, an insulating layer 23 covering the Si device layer 21 and the lower wiring 22 is formed, and then a normal exposure / development / etching process is performed to obtain the same diameter with an aspect ratio of ½ or more. Contact hole 24 is formed.

Next, as shown in FIG. 2B, after removing the resist film 25, the Si thin film 26 as a nucleation layer is removed by C
When the step coverage is formed by the VD method, the Si thin film 26 is formed on the surface of the contact hole 24 and the surface of the insulating layer 23.

Next, as shown in FIG. 2C, the Si thin film 26 other than the side wall of the contact hole 24 is dry-etched by magnetron RIE under a pressure of 10 ^-3 Torr using Cl ₂ as a reaction gas. Get rid of. In this case, the Si thin film 26 on the side wall of the contact hole 24 is less likely to be impacted by the ions because it is a pressure region where the dry etching promotion reaction by Ar ions proceeds, and anisotropic etching of Si proceeds in a direction perpendicular to the substrate. Therefore, as shown in FIG. 2C, only the side surface of the contact hole 24 is covered with the Si thin film 26.

Next, as shown in FIG. 2D, low pressure CVD
Total pressure 2 Torr, hydrogen carrier 60scc
m, DMAH (dimethyl aluminum hydride)
When selective CVD is performed for 2 minutes under the setting condition of 0.2 Torr, Al 27 is deposited and the contact hole 24 can be filled.

In the above embodiments, the Si thin film 6 was used as the nucleation layer, but it goes without saying that it can be conformally deposited with a metal such as Ti, TiN, Cu or Au.

As a raw material for selective deposition of Al, DM
Although AH was used, it goes without saying that the same result can be obtained by using organic aluminum such as tributylaluminum or trimethylamine alane.

[0025]

As described above, according to the present invention, by forming the AlCVD nucleation layer on the side wall of the contact hole, the contact holes having different diameters and having the same aspect ratio of 1/2 or more are uniformly formed. Can be embedded, A
It is possible to realize flattening of 1-system wiring and multilayer wiring.

[Brief description of drawings]

FIG. 1 is a main process diagram for explaining a first embodiment of the present invention.

FIG. 2 is a main process diagram for explaining a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Si device layer 2 Lower layer wiring 3 Insulating layer 4 Contact hole 5 Resist film 5 Si thin film 7 Al 21 Si device layer 22 Lower layer wiring 23 Insulating layer 24 Contact hole 25 Resist film 26 Si thin film 27 Al

Claims (4)

[Claims] 1. A contact hole burying structure having a nucleation layer and a burying metal, wherein the nucleation layer is provided on the bottom and side walls of the contact hole, and the burying metal is buried inside the contact hole. Al
The contact hole embedding structure is characterized in that 2. A contact hole filling structure having a barrier metal or polysilicon layer, a nucleation layer and a buried metal, wherein the barrier metal or polysilicon layer is provided at the bottom of the contact hole, and the nucleation layer is , Is provided on the side wall of the contact hole, and the embedded metal is Al embedded inside the contact hole.
The contact hole embedding structure is characterized in that 3. A contact hole embedding method including a contact hole forming step, a nucleation layer forming step, and an Al depositing step, wherein the contact hole forming step is an insulation for covering a Si device layer or a lower layer wiring. After forming the layer, normal exposure
By developing and etching, contact holes with the same diameter with an aspect ratio of ½ or more are formed. In the nucleation layer formation process, nuclei are formed by selective CVD processing while leaving the resist film on the insulating layer. A layer is formed on the bottom and side walls of the contact hole. In the Al deposition step, after removing the resist film, selective CVD is performed.
A method of embedding a contact hole, characterized in that Al is selectively deposited on a side surface and a bottom surface of the contact hole by a treatment. 4. A contact hole filling method comprising a contact hole forming step, a nucleation layer forming step, a nucleation layer removing step, and an Al depositing step, wherein the contact hole forming step comprises a Si device layer. Alternatively, after forming an insulating layer and a resist film for covering the lower layer wiring, ordinary exposure, development, etching, and resist stripping are performed to expose the insulating film to form a contact hole with an aspect ratio of ½ or more and the same diameter. The nucleation layer forming step is a step of forming a nucleation layer on the entire surface of the insulating film including the contact holes by the selective CVD process. The nucleation layer on the film surface and the bottom surface of the contact hole is removed. In the Al deposition step, the side surface of the contact hole and the side surface of the contact hole are selectively CVD processed. A contact hole embedding method which is characterized in that one which selectively depositing Al on the surface.