JPS61245540A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a thick silica thin layer with less stepped portions but without internal crack by coating an Si substrate with silica thin film, baking it at 200-400 deg.C, repeating such process and then processing it at a higher temperature. CONSTITUTION:An Al wiring 3 is formed and a thin film NSG4 is also formed on an insulation film 2 on an Si substrate 1 on which an element function part is formed. Next, a silica thin film 5a including phosphorus P is applied by spinning and it is vitrificated for 30min at 200-400 deg.C. In the same way, a layer 5b is laminated to form a comparatively thick silica layer, and it is then processed for 20min at 450-500 deg.C under the N2 to form a dense layer 5. Sudden volume compression of silica thin film can be avoided, internal cracks are not generated and a thick silica layer can be formed. Moreover, stepped portions are reduced, wiring is not open at the stepped portions, drop of interlayer insulation strength can be prevented and yield of apparatus can also be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more specifically, a method for manufacturing a semiconductor device by forming a relatively thick silica film layer on one principal surface of a semiconductor substrate by forming a crack inside the silica film layer. Concerning how to form without.

[Summary of the invention]

The present invention provides a method for manufacturing a semiconductor device in which a relatively thick silica film layer is formed on one main surface of a semiconductor substrate, in which a first silica film layer is formed on the semiconductor substrate by a coating method, and After baking at a temperature, a second silica film layer is formed on the first silica film layer by a coating method, and after baking at a temperature of 200 to 400 ° C.,
By repeating these steps several times in sequence and then performing a heat treatment at a higher firing temperature, a relatively thick silica film layer can be formed by a coating method without degrading the interlayer insulation properties. However, this reduces the level difference, improves the reliability of the wiring formed on it, and prevents a drop in dielectric strength between the upper and lower layer wiring.
This improves the manufacturing yield of semiconductor devices.

[Conventional technology]

In semiconductor devices and integrated circuits, multi-III wiring has come to be used more and more as the degree of integration increases.
In the multilayer wiring, steep irregularities of the interlayer insulating film formed on the lower layer wiring cause insulation defects in the @ line of the upper layer wiring and between the upper and second lower layer wiring.

Therefore, in recent years, in order to eliminate the above-mentioned obstacles, silicate glass is grown by vapor phase growth on the semiconductor substrate 1 on which the first RFJA wiring 3 is formed through the insulating film 2, for example, as shown in FIG. After forming 1114 (hereinafter referred to as NSG), a solution of silicic acid 51 (OR) 4 or its low-molecular polymer is applied and heated to form a silica film IfII5 on the NEIG film 4, and a silica film L is formed on the steep surface of the semiconductor substrate. The uneven portions are smoothed, and a 21st layer is applied on the silica film layer 4.
A coating method is used to form wiring.

[Problems and Objectives to be Solved by the Invention] However, in order to reduce the level difference, it is necessary to form a considerably thick silica film layer 5 without generating cracks or the like. However, since the silica film layer 5 is dehydrated and shrinks due to heating after coating, there is a drawback that cracks 7 may occur if the film becomes slightly thicker. In particular, since the Ill thickness is large at the stepped portion, the probability of cracking occurring at this portion is high. If, for example, aluminum wiring is placed on a cracked silica film layer, the wire will break at the cracked portion.

Therefore, conventionally, sheets were formed by a coating method.

Although the thickness of the pus film layer is made thin, for example, 1000 s or less, to prevent the occurrence of cracks, such a thin pus layer has a problem in that the effect of eliminating the step difference is very small.

Therefore, the present invention aims to solve these problems.
The objective is to form a relatively thick silica film layer using a coating method without degrading the properties of the interlayer insulating film, thereby reducing steps and improving the reliability of the wiring formed on it. Another object of the present invention is to provide a method for manufacturing a semiconductor device that prevents a decrease in dielectric strength between upper and lower wiring layers and improves the manufacturing yield of the semiconductor device.

[Means for Solving the Problem] The method for manufacturing a semiconductor device of the present invention includes a method for forming a relatively thick silica film layer on one principal surface of a semiconductor substrate. Forming a film layer by a coating method, baking the first silica film layer, and forming a second silica film layer by a coating method on the thus treated first silica film layer, The method is characterized in that the second silica film layer is fired, this process is sequentially repeated a plurality of times, and then heat treatment is performed.

In this case, it is preferable that the firing is performed at a temperature of 200 to 400°C, and the heat treatment is performed at a higher temperature than the firing temperature.

〔Example〕

The present invention will be explained in detail with reference to the following figures.

Referring to FIG. 1, a first layer of aluminum (Aj) wiring Is5 is formed on a semiconductor substrate 1 on which a functional part of a semiconductor element is formed and covered with an insulator 11W2, and a Si
A NBG layer 4 having a thickness of 0.5 to 1.0 μm is formed by a vapor phase growth method using a heat treatment of 81 compounds such as n, etc. and oxygen O2. Furthermore, a silica film I*5 is placed on this NSG ring 4.
This silica film 1-5 is formed into multiple layers as shown in FIG. N 130 Ill
A seventeenth phosphorus-containing film layer 5 a having a thickness of about 500 to 1.000 λ is formed on the phosphorus film by a coating method.

For the formation, for example, a silicic acid solvent containing silicon Si(OR)4, a phosphorus compound, and ethanol as the main solvent is used to form the above N5GIIl.
40o on A with spinner.

After applying for 10 seconds at ~6000 rpm, 200 ~ 4°C
Vitrification is performed at a temperature of 50 minutes. Further, a 27th lica film layer 5'b having the same thickness as the 17th lica film layer 5a over the 17th licar film 1-5a is formed by the coating method described above, and it is coated in the same manner as described above. Heat treatment is performed at a temperature of 200 to 400°C. This process is subsequently repeated to obtain a relatively thick silica film layer. After that, in a nitrogen atmosphere, 450-5
By heat treatment at a temperature of 00° C. for 20 minutes, the silica film layer is densified to obtain a silica film layer 5. In addition, in the figure, 1. The silica film layer 5a is shown as a sandy surface after being heated at a temperature of 200 to 400 DEG C., and the second silica film layer 5b is shown as having been coated with a solvent but not subjected to the heat treatment. As described above, since the level difference caused by the first aluminum wiring 5 is smoothed, the 21st aluminum wiring 6 without any step breaks is realized.

In addition, in the above-mentioned embodiment, the case where the wiring of the first eyelet is made of aluminum is shown, but the wiring of the first layer is made of aluminum.
In the case of 1-Si-11-con, the final heat treatment is carried out in a nitrogen atmosphere at a temperature of 8□00 to 1000°C for 20 minutes.
Or 900~+050℃ with a halogen lamp, 5
It is preferable to carry out for ~10 seconds.

To check the presence or absence of cracks in the silica film layer 5 formed as described above, after the silica film I95 is formed, the window opening in the next step is performed, and after the second layer of aluminum wiring 6 is formed, observation L7'c is performed using a microscope. However, it was confirmed that no cracks were generated at all. Furthermore, when the performance of the device was measured after molding and after die attachment, no phenomenon that could be considered to be an adverse effect due to the occurrence of cracks was observed.

By the way, in the above-mentioned example, the silica film 1
- uses a phosphorus-added film, and it has been confirmed that by adding phosphorus to the silica film, the stress within the film is relaxed and the crack resistance is improved.

〔Effect of the invention〕

As described above, according to the manufacturing method of the present invention, the coating and baking of a silica film layer having a thickness that does not cause cracks is repeated multiple times, and then the density of the silica film j#I is densified. Therefore, rapid volumetric shrinkage of the silica film layer can be avoided, and a relatively thick silica film layer can be formed without causing internal cracks.

Therefore, according to the method of the present invention, a relatively thick silica film 1- can be formed by a coating method without deteriorating its properties as an interlayer insulation, thereby reducing the level difference and improving the reliability of the wiring formed thereon. This has the effect of improving the manufacturing yield of semiconductor devices by preventing a decrease in dielectric strength between upper and lower layer interconnects, and improving the manufacturing yield of semiconductor devices.

In the above embodiment, a case was shown in which an NBG film was used as an insulator, but phosphosilicate glass (PSG) was used as an insulator. ! li, boron phosphosilicate glass (BPSG) IN, plasma nitridation (P-8iN) I
There is no problem in using II or the like. In addition, the silica film layer is phosphorus-added 7Joll! Although the above case is illustrated, a solvent in which phosphorus and boron are heavily added is also effective.

In addition, in the upper wiring example, we have explained the case where the wiring layer is made of polysilicon and aluminum, or two layers of aluminum, but it is also possible to use polycide or high single point metal for at least 1 m of the wiring layer, or use aluminum or other The present invention is also effective for multilayer wiring in which five or more layers of metal are provided.

[Brief explanation of drawings]

1 and 5 are process sectional views of a semiconductor device showing an embodiment of the present invention, and FIG. 2 is a process sectional view of a semiconductor device illustrating a conventional example. 1... Semiconductor substrate 2.4... Insulating canopy 5.6... Metal wiring 5... Silica film layer 5a... 17th Lica film layer 5b... 27th Lica film layer 7...・Crack or higher

Claims (3)

[Claims] (1) In a method of forming a relatively thick silica film layer on one principal surface of a semiconductor substrate, a first
A silica film layer is formed by a coating method, the first silica film layer is fired, a second silica film layer is formed by a coating method on the thus treated first silica film layer, and the first silica film layer is formed by a coating method. 1. A method for manufacturing a semiconductor device, comprising the steps of firing the silica film layer of No. 2, sequentially repeating this step multiple times, and then heat-treating the silica film layer. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the firing is performed at a temperature of 200 to 400°C. (3) The method for manufacturing a semiconductor device according to claim 2, wherein the heat treatment is performed at a higher temperature than the firing temperature.