JPH04280457A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To micronize a semiconductor device by providing the first contact pad and the second contact pad, which connects this contact pad with the conductive film having a desired wiring pattern structurally and electrically. CONSTITUTION:This includes a semiconductor substrate S or a semiconductor substrate B, which includes an insulating film I provided thereon, and semiconductor elements, and a conductive film C, which has desired wiring patterns. And the semiconductor substrate B and the conductive film C are connected with each other by the first contact pad P1 and the second contact pad P2, which is connected structurally and electrically with this contact pad P1. What is more, the second contact pad P2 has a sectional area larger than that of the first contact pad P1. Hereby, the aspect ratio of the contact hole of the contact pad can be suppressed to be small, so the micronization of the semiconductor device can be accelerated while sharply suppressing the contact inferiority.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device,
In particular, the present invention relates to a structure for making a conductive connection with a semiconductor element and a method of manufacturing a semiconductor device including this structure.

0002

2. Description of the Related Art FIG. 3(a) shows a cross section of a conventional semiconductor device, and an example of its manufacturing method is as follows.
An insulating film 1 is formed on a silicon substrate 11 on which a semiconductor element is formed.
After forming 2, a resist film is deposited on this insulating film by a photolithography process, a contact hole 13 is formed by etching using this resist film as a mask, and then the resist film is removed.

[0003] In the specification of this application, the term "semiconductor substrate" or "silicon substrate" refers to a state in which a semiconductor element is formed on a semiconductor substrate such as a silicon substrate, or a state in which an insulating film or the like is formed on a semiconductor substrate on which a semiconductor element is formed. Refers to a semiconductor device that is in the manufacturing process state, such as the state in which it has been deposited.

Next, an aluminum-silicon alloy film containing, for example, 1% silicon is deposited as the conductive film 14 by sputtering. The conductive film 14 and the semiconductor element on the silicon substrate 11 are electrically connected through this aluminum-silicon alloy film by heat treatment.

[0005] After that, a resist film is applied on the conductive film 14 by a photolithography process, and the conductive film 14 is etched using the resist film as a mask to remove unnecessary portions, and then the resist film is removed. By removing it, a conductive film having a desired wiring pattern is formed.

[0006]

[Problems to be Solved by the Invention] However, with the miniaturization of semiconductor devices, the level difference (aspect ratio) of wiring has increased significantly, and the amount of aluminum-silicon alloy film deposited in the contact hole 13 is not sufficient. For Figure 2(a)
As shown at 15 in Figure 2(b), a thin part may occur and the resistance may increase, and if this is significant, the aluminum-silicon alloy film may break as shown at 16 in Figure 2(b), causing damage to the semiconductor element. Electrical connections were sometimes not made.

Conventional methods to solve this problem include round etching in which the upper part of the contact hole is removed by isotropic etching when forming the contact hole, and measures such as forming a metal sidewall in the contact hole. However, in either method, the conductive material in the contact hole is formed simultaneously with the deposition of the conductive film on the top of the insulating layer, so step coverage (embedding) of the conductive material such as aluminum silicon alloy is required. Since the limit of miniaturization is influenced by the limit of , it is insufficient to consider the increase in aspect ratio due to future miniaturization.

[0008]Also, a method of selectively depositing a metal such as tungsten in the contact hole is being considered, but it is difficult to control the selective deposition reaction of the metal, so it is difficult to use selective metal film formation technology. need to be developed.

The present invention can also be applied to increasing the aspect ratio of contact holes in semiconductor devices, which are expected to become even smaller in the future. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can obtain a conductive connection between a semiconductor element and a wiring layer without causing an increase in contact resistance due to disconnection or thinning of the alloy film.

0010

Means for Solving the Problems In a semiconductor device, a structure is provided between a first contact pad in contact with a semiconductor substrate and a conductive film having a larger cross-sectional area than the contact pad and having a desired wiring pattern. a second
A contact pad is provided.

[0011] Also, one method of manufacturing the above-mentioned semiconductor device includes a step of providing a first contact pad on a semiconductor substrate on which a semiconductor element is formed, and a step of providing a first contact pad so that a part of the first contact pad is exposed. a step of providing a first interlayer film on the exposed first contact pad; and a step of providing a second contact pad having a larger cross-sectional area than the first contact pad and electrically connected to the first contact pad on the exposed first contact pad. a step of providing a second interlayer film so that a part of the second contact pad is exposed; and a step of providing a conductive film having a desired wiring pattern on the upper surface of the second contact pad and the second interlayer film. can be included.

0012

[Operation] FIG. 1 is a diagram conceptually showing a cross section of a semiconductor device according to the present invention, in which a semiconductor substrate B includes a semiconductor element on a semiconductor substrate S or an insulating film I provided on the upper surface thereof.
and the conductive film C having the desired wiring pattern.
and a second contact pad P1 which has a larger cross-sectional area than this contact pad P1 and is structurally and electrically connected to this contact pad P1.
It was made to connect with contact pad P2 of . Note that the left side of FIG. 1 shows cases in which direct electrical connections are made to semiconductor elements provided on semiconductor substrate B, and the right side shows cases in which semiconductor devices are connected via an insulating film I, such as MOS gate electrodes. Each state is shown when coupled with an element.

[0013] As a result, the first contact pad P1 in the first interlayer film M1 in contact with the semiconductor substrate B
Since the diameter of the opening w1 is smaller than the opening w2 of the second interlayer film M2 provided above, the composite aspect ratio of these contact pads P1 and P2 is w2.
/h, which can be smaller than the aspect ratio w2 /h when the second contact pad P2 is not provided, and furthermore, this combined aspect ratio can be arbitrarily selected.

Further, according to the method of manufacturing a semiconductor device according to the present invention, the first contact pad P1 and the second contact pad P1
Since the contact pads P2 are formed independently before forming the interlayer films M1 and M2, the aspect ratio of the conductive contact hole can be adjusted as the size of the conductive contact hole increases due to miniaturization by using conventional alloy deposition techniques such as those for aluminum-silicon alloys. Even if the ratio increases, conductive connections within the conductive contact holes can be achieved without disconnection or increased resistance due to thinning of the film. Since the surface of a semiconductor element having a large step difference can be flattened, the yield of semiconductor devices can be increased.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 schematically shows the manufacturing steps of a semiconductor device according to an embodiment of the semiconductor device manufacturing method of the present invention using cross-sectional views.

After selectively forming an insulating film 2 on a silicon substrate 1 on which a semiconductor element is formed, an aluminum-silicon alloy film is deposited as a first conductive film by sputtering.
By forming a resist film 4 on this first conductive film by a photolithography process and performing anisotropic etching, as shown in FIG.
As shown in (a), a first contact pad 3 is formed, and then the resist film 4 is removed.

Next, the insulating film 2 and the first conductive film 3 are formed.
A SiO2 film 51 with a thickness of 2,000 μm is deposited on top by P-CVD
0 Å deposited, and further SOG (spi
After depositing a film 52 with a thickness of 5,000 Å, heat treatment is performed at 420° C. in a nitrogen atmosphere.
After that, the surface is planarized by etching back by anisotropic etching, and then the SiO2 film 5 is etched back by P-CVD method.
Figure 2(b) was obtained by depositing 2,000 Å of
), a first interlayer film 5 is formed.

Next, a resist film is formed on the first interlayer film 5 by a photolithography process, and then anisotropic etching is performed to form a part of the first contact pad 3, as shown in FIG. 2(c). A contact hole 6 with an exposed portion is formed.

Next, an aluminum-silicon alloy film is deposited by sputtering on the first interlayer film 5 having the contact hole 6 and the exposed first contact pad 3, and heat-treated to establish electrical connection with the first contact pad 3. After establishing electrical conductivity, a resist film is formed by a photolithography process and then anisotropically etched to form a second contact pad 7 over the contact hole 5, as shown in FIG. 2(d).

Next, after removing the resist film, a 2,000 ml SiO2 film 81 is deposited on the first interlayer film 3 with a portion of the contact pad 6 exposed by the P-CVD method.
Then, a SOG film 82 of 5,000 Å was sequentially deposited, heat treated at 420° C. in a nitrogen atmosphere, and then flattened by anisotropic etching until a part of the contact pad 6 was exposed. ,after that,
A SiO2 film 83 with a thickness of 2,000 Å was formed using the P-CVD method.
This is deposited to form a second interlayer film 8, as shown in FIG. 2(e).

After that, an aluminum-silicon alloy film is deposited on the second interlayer film 8 where a part of the second contact pad 7 is exposed and heat-treated to ensure conduction with the second contact pad 7. A resist film is formed on this aluminum-silicon alloy film by a photolithography process to function as a mask for defining the wiring pattern, and after anisotropic etching is performed using this mask, this resist film is removed, as shown in FIG. In addition, a second wire having the required wiring pattern
A conductive film C is formed.

[0022]

[Effects of the Invention] As explained above, according to the present invention,
Since the aspect ratio of the contact hole of the contact pad can be arbitrarily suppressed, contact defects can be greatly suppressed while using existing conductive film and insulating film formation technology, and the contact element can be made small (when the semiconductor device is completed). Since it is possible to form contacts (with a large contact aspect ratio), it is possible to not only promote miniaturization of semiconductor devices but also improve yields, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a side cross-sectional view sequentially showing the manufacturing method of the embodiment of the present invention.

FIG. 3 is a side sectional view showing a conventional semiconductor device. S Semiconductor substrate B,1 on which a semiconductor element is formed Semiconductor substrate I,2 Insulating film C Conductive film P1,3 having a required wiring pattern First contact pad M1,5
First interlayer film P2,7 Second contact pad M2,8
Second interlayer film 4 Resist 51, 81 SiO2 film 52, 82 SOG film 53, 83 SiO2 film

Claims (2)

[Claims] 1. A method for structurally and electrically connecting a first contact pad in contact with a semiconductor substrate and a conductive film having a larger cross-sectional area than the contact pad and having a desired wiring pattern. 1. A semiconductor device comprising: a second contact pad provided in the semiconductor device; 2. A step of providing a first contact pad on a semiconductor substrate on which a semiconductor element is formed, a step of providing a first interlayer film so that a part of the first contact pad is exposed, and a step of providing the first contact pad. a step of providing a second contact pad having a larger cross-sectional area than the pad and electrically connected to the first contact pad on the exposed first contact pad; and a step of exposing a part of the second contact pad. A method for manufacturing a semiconductor device, comprising the steps of: providing a second interlayer film on the second contact pad and the second interlayer film; and providing a conductive film having a desired wiring pattern on the upper surface of the second contact pad and the second interlayer film.