JPH0284727A - Thin film formation - Google Patents

Abstract

PURPOSE:To realize a thin film forming method wherein leak current between wirings can be reduced, stress generating between the wirings and a thin film can be decreased, and the generation of cracks and the disconnection of wirings can be prevented, by sputtering a specified target, and forming, on a substrate, an inorganic thin film whose stress is smaller than or equal to a specified value. CONSTITUTION:A target 14 is used, whose bond gap Eg is 3.5eV<=Eg<=10.0eV and whose resistivity rho is 1 1X10<13>OMEGAcm<=rho<=10<16>OMEGAcm. Material of the target 14 is spread on a substrate 13 by sputtering method, and an inorganic thin film, whose stress is smaller than or equal to 1500kg/cm<2>, is formed. For example, an Al wiring layer 22 is formed on an Si substrate 21; the sample substrate is mounted on an electrode 11 of a sputtering equipment as shown by figure; thereby depositing an insulating layer 23. Concerning to the target 14, material composed of 0.5SiO2-0.1ZrO2-0.4B2O3 is used, whose Eg is 7.4eV and whose rhois 1X10<15>OMEGAcm. After that, an Al wiring layer 24 is again formed on the insulating film 23, and, in this case, the stress in the insulating film 23 becomes 820kg/cm<2>.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for forming thin films used as interlayer insulating films, protective films, etc. of semiconductor devices, and in particular, relates to a method for forming thin films used as interlayer insulating films, protective films, etc. The present invention relates to a method for forming a thin film.

(Prior Art) Conventionally, insulating films of phosphoric acid silica glass, silicon oxide, silicon nitride, etc. have been used as interlayer insulating films of various semiconductor devices. These insulating films are in contact with the wiring, and the coefficient of thermal expansion of the insulating film and the wiring is generally about 20 times greater. For this reason, a large stress is applied between the interlayer insulating film and the wiring due to temperature change, resulting in a disadvantage that the wiring may be cut. Furthermore, conventional interlayer insulating films are not sufficient in suppressing leakage current between wirings, and also have the problem of cracking.

It should be noted that the above problem becomes more noticeable as the miniaturization of LSI progresses and the wiring width becomes 1 μm or less. Further, similar problems exist not only in interlayer insulating films but also in protective films of semiconductor devices.

(Problems to be Solved by the Invention) As described above, insulating films conventionally used as interlayer insulating films or protective films are subject to large stress due to the difference in coefficient of thermal expansion with wiring materials, which can lead to cracks and disconnection of wiring. There was a problem. Furthermore, this type of insulating film is not fully satisfactory in terms of leakage current between wirings.

The present invention has been made in consideration of the above circumstances, and its purpose is to be able to reduce leakage current between wirings, reduce stress generated between wirings, etc. It is an object of the present invention to provide a thin film forming method that can prevent the occurrence of cracks and disconnection of wiring.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the present invention, a thin film is formed in the following manner.

That is, in the present invention, the band gap Eg is 3.5eV≦Eg
≦lO, OcV, specific resistance ρ is 1×1013ΩC≦ρ≦1
Using a target of ×1016 Ωcm, the target was sputtered, and the material ejected by this sputtering was spread on a substrate, and the stress was 1500 kg/a.
This method is designed to form an inorganic thin film of II2 or less.

Further, the present invention uses a plurality of targets and has a plurality of thin films deposited on a substrate by sputtering, and at least one
This is a method in which one layer is amorphous and at least one other layer is crystalline, and the thin film deposited on the substrate by sputtering is further annealed or jittered.

Here, the reason for the above limitation is that if the band gap Eg is less than 3.5 cV, the insulation between wirings will be poor and the leakage current will increase, and if Eg is more than lOcV, a glass or inorganic film may be formed. This is because it becomes difficult. This is because if the internal stress exceeds 1,500 kg/c+a2, the occurrence of wiring breaks and glass cracks will increase significantly. Furthermore, if the specific resistance ρ is less than I×10 13 Ωcm, not only will the protective film fail to function, but it will also increase leakage current and adversely affect the electrical characteristics of the device. Furthermore, if ρ is 1×10 16 Ωcl1 or more, it is not only impossible to form an inorganic film, but also because the coefficient of thermal expansion of the insulating material becomes significantly smaller than that of the wiring material, causing cracks in the insulating film.

Also, the insulating film has two or more layers, one of which is amorphous.

The reason why the other material is crystalline is that it not only increases the band gap but also enhances the functions of the insulating film, such as impurity blocking effect and passivation. Furthermore, annealing and jitter are performed because they are effective in removing defects, reducing stress at interfaces, and the like.

(Function) According to the present invention, when applied to the formation of an interlayer insulating film of multilayer wiring or a protective film of an element, a highly reliable insulating film with low leakage current and stress can be formed. For example, when forming an interlayer insulating film for multilayer wiring, for an applied voltage of 50V,
The leakage current between the wiring becomes extremely small at about 1X10-''A, and furthermore, it is possible to reliably eliminate disconnection of the wiring and cracks in the insulating film.Also, the insulating film is made of two layers, one of which is amorphous and the other of which is crystalline. It has been found that by improving the quality, very good results can be obtained in blocking impurities, passivation, etc.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a sputtering apparatus used in a method according to an embodiment of the present invention. 10 in the figure is a vacuum container,
Inside this container 10, electrodes 11 and 12 are arranged facing each other. The lower electrode 11 is grounded, and a sample substrate 13 is placed on this electrode 11. High frequency power is applied to the upper electrode 12 from a high frequency power source 16 via a matching circuit 15, and a target 14 is applied to the upper electrode 12.
is fixed. In addition, a gas inlet 1 is provided in the container 10.
An inert gas such as A is supplied from 7 to 7, and the gas in the container 10 is exhausted from a gas exhaust port 18.

Next, an example in which an interlayer insulating film of a multilayer interconnection is manufactured using this apparatus will be described. First, as shown in FIG. 2(a), an Al wiring layer 22 was formed on an St substrate 21. This sample substrate is placed on the electrode 11 of the apparatus shown in FIG.
An insulating film 23 was deposited as shown in FIG. 2(b). At this time, a material described later was used as the target 14. Thereafter, the /i wiring layer 24 was formed again on the insulating film 23.

Further, as a modification of FIG. 2(b), as shown in FIG. 2(e), the insulating film 23 was formed into two layers using a 2B target. At this time, one insulating film 23+ was made amorphous, and the other insulating film llI23□ was made crystalline.

FIG. 3 is a diagram showing the band gap of an insulator, and it is desirable that Eg be as large as possible compared to a semiconductor. If Eg cannot be increased with a single layer, multiple layers may be used to increase Eg. Furthermore, in order to reduce the stress within the wiring and the insulating film as much as possible, it is necessary to reduce the difference in coefficient of thermal expansion between the two materials. The target materials used in this example and the insulating film to be formed are as follows.
The table also shows the characteristics of each material. The materials for each example are 0.82 n 0.4S i 02 for Example 1 and 0.5S f O2o, tz r O20,4t for Example 2.
hOi, in Example 3, the first layer is 0.9S i 02 0. lA S 20s
+2nd layer is SiN+bias sputtered SiO□, and in Example 4, 1st layer is ARN.

The second layer is 0.8S t 02 0.1B2030.1P
205, in Example 5, the first layer is Si and N4, the second layer is 0.9B 203 0.1B a O and 350
In Example 6, the first layer was quartz glass by bias sputtering.

The second layer is cristobalite crystal, Example 7 is The first layer is bias sputtered 5in2 glass.

The second layer is plasma SiO crystal.

By forming a thin film as shown in the table by sputtering using such a target, it is possible to form an interlayer insulating film having a sufficiently large band gap and resistivity and a sufficiently small mis-stress. Therefore, it is possible to realize a semiconductor device with less leakage current between wirings and with good block resistance and passivation.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without departing from the gist thereof. For example, the sputtering apparatus is not limited to the same as shown in FIG. 1, and can be modified as appropriate according to specifications. Specifically, the sputtering method is not limited to high-frequency sputtering, and direct current sputtering, bias sputtering, magnetron sputtering, or the like may be used.

[Effects of the Invention] As detailed above, according to the present invention, by selecting the material when depositing a thin film by sputtering, leakage current between wirings is small, stress in the wirings and insulating film is small, and Moreover, a highly reliable insulating film without cracks or disconnections can be formed.

Therefore, it can be applied to the manufacture of various semiconductor devices with great effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a sputtering apparatus used in a method according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the process of forming an interlayer insulating film according to the same embodiment, and FIG. 3 is a diagram showing a good insulating film. FIG. 3 is a characteristic diagram showing the bandgap of 10... Vacuum container, 11.12... Electrode, 13...
- Sample, 14... Target, 15... Matching circuit, 16... High frequency power supply, 17... Gas inlet,
18... Gas exhaust port, 21... Si substrate, 22.2
4...AN wiring layer, 23.23+, 232... interlayer insulating film. Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) Band gap Eg is 3.5eV≦Eg≦10.
0eV, specific resistance ρ is 1×10^1^3Ωcm≦ρ≦1×
Using a target of 10^1^6 Ωcm, the target material was deposited on the substrate by sputtering, and the stress was 150Ω.
A thin film forming method characterized by forming an inorganic thin film of 0 kg/cm^2 or less. (2) A plurality of the targets are used, and a plurality of thin films are deposited on the substrate by the sputtering method, and at least one
2. The thin film forming method according to claim 1, wherein the layer is amorphous and at least one other layer is crystalline. (3) Claim 1 characterized in that the thin film deposited on the substrate by the sputtering method is annealed or jittered.
Or the thin film forming method described in 2.