JPH04199628A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the title semiconductor device having wirings in high reliability to be manufactured by a method wherein the whole surface of a tungsten layer on an interlayer insulating film is etched back to be left in thickness of about 500Angstrom so that an Al alloy and the layer insulating film may not be brought into direct contact with each other so as to avoid the growth of nodules in the Al alloy. CONSTITUTION:A layer insulating film to be a silicon oxide film 102 is formed on the surface of a silicon substrate 101 and then contact holes 103 are made in the film 102. Next, a titanium layer 104 and a titanium nitride layer 105 to be directly connected to a prospective contact region 101a and to lower the contact resistance are successively deposited on the inner surface of the contact holes 103 and on the surface of the silicon oxide film 102. Next, a tungsten layer 106 is formed extending over the whole wafer surface on the surface of a titanium nitride layer 105 and the whole surface of the tungsten layer 106 is etched back to reduce the film thickness to about 500Angstrom on the silicon oxide film 102. Through these procedures, the tungsten layer 106 used as a barrier metal to avoid the growth of modules thereby enabling the wirings in high reliability to be made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming wiring in a semiconductor device.

[Prior Art] In a conventional semiconductor manufacturing method, as shown in FIG. 2, after an interlayer insulating film 202 is deposited on a semiconductor substrate 201, a contact hole 203 is opened and a titanium layer serving as a base metal layer is deposited. 204 (100 people) and titanium nitride layer 205 (5
00 people) are deposited consecutively. Then, a tungsten layer 206 is deposited inside the contact hole 203 and on the interlayer insulation M2O2 by chemical vapor deposition. After that, the entire surface of the tungsten layer 206 is etched back, and the tungsten layer 206 is etched only inside the contact hole 203.
After that, an aluminum alloy 207 layer was deposited and patterned into a desired pattern by photolithography and etching.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technique, the tungsten layer 206 on the glabella insulating film 202 is removed by etching back the entire surface, so the interlayer insulating film 202 and the aluminum alloy 207
A region is formed where the silicon atoms are in direct contact with each other, and silicon atoms diffuse into the aluminum alloy 207 to form a nodule, which may cause the wiring layer 207 made of the aluminum alloy to be disconnected.

Therefore, the present invention is intended to solve such problems, and its purpose is to remove 50% of tungsten on the glabella insulating film.
A method for manufacturing semiconductor devices with highly reliable wiring is achieved by etching back the entire surface to avoid direct contact between the aluminum alloy and the interlayer insulating film, thereby suppressing the generation of nodules in the aluminum alloy. It's there to provide.

[Means for Solving the Problems] The present invention provides a step of forming an interlayer insulating film above a semiconductor substrate, a step of forming a contact hole by opening a window in the interlayer insulating film, and an inner surface of the contact hole and the interlayer. on the insulating film,
Depositing a tungsten layer with a thickness larger than the radius of the contact hole by chemical vapor deposition, etching back the entire surface of the tungsten layer to a thickness of 50 mm.
a step of depositing an aluminum alloy layer on the tungsten layer; a step of depositing an aluminum alloy layer on the tungsten layer using a photoresist as a mask, which is formed above the aluminum alloy layer in a region previously designed to become a wiring; and a step of etching the tungsten layer to form wiring.

[Example] Next, a method for manufacturing a semiconductor device according to an example of the present invention,
This will be explained with reference to FIGS. 1(a) to 1(f), which are cross-sectional views of the process.

First, as shown in FIG. 1, semiconductor regions (not shown) such as diffusion layers are formed on the surface of the silicon substrate 101, and these semiconductor regions and electrode wiring formed on the surface side of the silicon substrate 101 are formed on the surface of the silicon substrate 101. In order to insulate and separate the layers, a glabella insulating film including a silicon oxide film 10 with a thickness of about 5000 is formed on the surface of the silicon substrate 101 by chemical vapor deposition. A contact hole 103 is formed by etching in a portion of the silicon oxide film 102 corresponding to the contact area 101a, and the contact area 101a of the silicon substrate 101 is opened at the bottom thereof.

Next, as shown in FIG. 1(b), the contact hole 10
3 and on the surface of the silicon oxide film 102, there is a titanium layer 104 with a thickness of 150 mm, which is directly connected to the contact area 101a of the silicon substrate 101 and serves as a contact metal layer for reducing the contact resistance. In order to improve the adhesion between the layer 104 and the contact buried layer 106 to be described later, a titanium nitride layer with a thickness of 500 μm and 1°5 as an adhesion metal layer interposed between these two layers is sequentially deposited by sputtering. . Here, titanium layer 10
4 is the contact area m at the bottom of the contact hole 103
It is in contact with 101a. On the other hand, the titanium nitride layer 105
A tungsten layer 106 is formed over the entire surface of the wafer, as shown in FIG. 1(C). The thickness of the tungsten layer 106 is more than half the diameter of the contact hole 103. For example, the diameter of the contact hole 103 is 0. If the thickness is 5 μm, the thickness of the tungsten layer 108 will be at least 250 OA. If this thickness is deposited, the inside of the contact hole 103 will be filled with the tungsten layer 106. Further, since the TiN layer 105 mentioned above is located under the tungsten layer 106, sufficient adhesion is ensured.

Next, as shown in FIG. 1(d), a tungsten layer 10
6 is etched back on the entire surface, and the thickness of the tungsten layer 106 on the silicon oxide film 102 is reduced to about 50.0 mm. This makes it possible to reduce the thickness of the wiring layer consisting of the titanium layer 104, the TiN layer 105, the tungsten layer 106, and the aluminum alloy layer 107, which will be described later, and to improve the coverage of the film deposited above this wiring layer. It will be good. Conversely, by leaving about 500% of the tungsten layer 106 on the silicon oxide film 102 without completely removing it, the tungsten layer 106 can be used as a barrier metal. The generation of nodules due to the diffusion of silicon atoms can be suppressed.

Next, as shown in FIG. 1(e), aluminum alloy 107 was
Deposited by 00OA sputtering method. The lower layer of the aluminum alloy layer 107 is a tungsten layer 1 which becomes a barrier metal.
06, silicon substrate 101 and silicon 102
Interdiffusion between the aluminum alloy layer 107 and the aluminum alloy layer 107 is prevented. or,
The final thickness of the wiring layer is approximately 6000 mm, and the coverage of the film deposited over the wiring is tungsten II! 10
This is greatly improved compared to the case where 6 is not etched back at all.

Next, as shown in FIG. 1(f), the titanium layer 105 and the TiN layer 105 are etched using photolithography and etching techniques.
, the tungsten layer 106 and the aluminum alloy layer 107 are patterned into a desired pattern. The wiring is now complete.

[Effects of the Invention] In the wiring formed according to the present invention described above, the inside of the contact hole is filled with the tungsten layer and has sufficient step coverage. Furthermore, by leaving the tungsten layer on the interlayer insulating film, the reaction between the aluminum alloy and the interlayer insulating film is suppressed, resulting in high reliability. Furthermore, by depositing a tungsten layer and then etching back the entire surface, the thickness of the wiring layer is suppressed, which also has the effect of improving the covering properties of the film above the wiring layer, such as passivation.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(f) are process cross-sectional views showing the method for manufacturing a semiconductor device of the present invention. FIGS. 2(a) to 2(d) are process cross-sectional views showing a conventional method for manufacturing a semiconductor device. 101.201 Semiconductor substrate 101a Contact area 102.202 Silicon oxide film 103.203 Contact hole 104.204 Titanium layer 105.205 Titanium nitride layer 106.206 Tungsten layer 107.207 Aluminum alloy layer and above Applicant Seiko Epson Corporation Agent Person Patent attorney Kizobe Suzuki (1 person)

Claims (1)

[Scope of Claims] A step of forming an interlayer insulating film above a semiconductor substrate, a step of forming a contact hole by opening the interlayer insulating film, and forming the contact hole on the inner surface of the contact hole and on the interlayer insulating film. a step of depositing a tungsten layer with a thickness larger than the radius of
a step of depositing an aluminum alloy layer on the tungsten layer; a step of depositing an aluminum alloy layer on the tungsten layer using a photoresist as a mask, which is formed above the aluminum alloy layer in a region previously designed to become a wiring; and etching the tungsten layer to form wiring.