JPH029449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a manufacturing method for forming a silicon oxide (hereinafter abbreviated as SiO ₂ ) film by a sputtering method.

<Prior art> As the density of integrated circuits increases, patterns become finer and multi-layer wiring and laminated structures are used, making the structure of semiconductor circuit elements extremely complex, and the use of SiO ₂ as an insulating film. Strict properties are now being required for nitride films and nitride films. Recently, SiO ₂ used in such high-density integrated circuit elements is often produced by a sputtering method. However, SiO ₂ films created by the conventional sputtering method may have a significant change in the internal stress of the film due to heat treatment after creation, or the SiO ₂
This often causes the substrate on which the film is deposited to warp, and some films peel off from the substrate, making it impossible to achieve the intended purpose.

As long as the SiO ₂ film is used simply as a protective film covering the surface of a semiconductor substrate or as an interlayer insulating film for multilayer interconnection consisting of a relatively small stacked structure of one or two layers, the above-mentioned conventional Membranes prepared by this method can also be used. However, the insulating film inserted between the devices of laminated high-density integrated circuit elements, which are being developed due to the dramatic increase in the degree of integration, cannot be fabricated using the conventional method described above.
There are problems with SiO ₂ films.

That is, FIG. 1 is a cross-sectional view of a laminated high-density integrated circuit device that has been proposed in the past.In reality, it is laminated in many more layers, but in order to avoid complicating the diagram, the integrated circuit devices 10 and 20 are separated by two. An example of stacked layers is shown. Impurity diffusion region 12 in silicon substrate 11,
12, etc., and the second
Although the devices 20 are stacked, both devices 10 and 2
An insulating film 30 is inserted between 0 and 0 in order to electrically insulate the devices. After depositing the insulating film 30 on the first layer device 10 on which the circuit has been created, a polysilicon film 21 for the second layer device 20 is formed, and some areas within the polysilicon film 21 are The polysilicon is made into a single crystal by irradiation with laser light and laser annealing. A P or N type impurity is introduced into the single crystallized region to create a circuit element, and a second layer device 20 is created. Similarly, integrated circuit devices are sequentially stacked on the second layer device 20 via an insulating film, and the devices are stacked in at least five layers to form a three-dimensional circuit element with a very high degree of integration.

In the above-described laminated high-density integrated circuit element, a thermal process or heat treatment is often required in the process of creating devices in each layer. However, the insulating film interposed between the devices must not be deformed or peeled off from the device surface even when exposed to the above-mentioned heat treatment or other working environments. To this end, it is desirable that the internal stress of the insulating film formed on the device surface does not change due to thermal processes or heat treatments after the film is formed. However, in SiO ₂ films created by conventional sputtering methods, the internal stress in the thin film changes during heat treatment, resulting in cracks in the film itself or deformation of the silicon substrate on which the SiO ₂ film is deposited. There was an inconvenience.

<Object of the Invention> The present invention is directed to the manufacturing method produced by the above-mentioned conventional manufacturing method.
This was done in view of the problems with SiO ₂ films, and by providing a manufacturing method that can obtain a thermally stable SiO ₂ film whose internal stress hardly changes during sputtering regardless of the heat process or heat treatment. be.

<Example> One of the opposing electrodes provided in the reaction tank of a magnetron sputtering device contains SiO ₂ ,
A material to be sputtered such as a SiO ₂ substrate is set, and an integrated circuit device substrate on which a SiO ₂ film is to be deposited is set on the other electrode. The electrode side on which the integrated circuit device substrate is set is equipped with a heating means to heat and maintain the substrate at a predetermined temperature during sputtering. After setting the materials on each electrode, a predetermined inert gas is introduced into the reaction tank, and power is supplied between the electrodes. When the sputtering equipment operates, a high frequency voltage is applied between the electrodes and the voltage is ejected from the sputtering material.
Molecules or atoms for creating a SiO ₂ film are deposited on the substrate surface, creating a SiO ₂ thin film on the substrate surface.

FIG. 2 illustrates the relationship between the internal stress of a SiO ₂ film produced by magnetron sputtering and the substrate temperature during sputtering, using the post-sputtering heat treatment conditions as parameters. However, the high-frequency power density during sputtering was set at 5.5 W/cm ² to create the SiO ₂ film. In the figure, curve A is for a SiO ₂ film that has been deposited on a substrate by sputtering and has not been subjected to any particular heat treatment, and curve B is for a SiO ₂ film that has been heat treated at 600°C for 1 hour after sputtering.
Curve C is a measurement of how the internal stress of the SiO ₂ film that was heat-treated at 800° C. for 1 hour after sputtering changes depending on the substrate holding temperature during sputtering. As is clear from the figure, curves A, B, and C are at approximately the substrate temperature.
The internal stress of the film was approximately the same at around 200℃, which indicates that the internal stress of the film does not change regardless of the heat treatment after sputtering, depending on the substrate temperature _. Show what you got. The substrate temperature for creating a thermally stable SiO ₂ film with internal stress is not limited to the above-mentioned approximately 200°C, but varies depending on the RF power density during sputtering. The substrate temperature that should be selected changes depending on the RF power density, but by selecting the substrate temperature according to the electrical conditions during sputtering, there is almost no change in the internal stress of the film due to heat treatment, and a stable SiO ₂ film can be obtained. Become.

Based on the above results, the RF power density was 5.5W/cm ² by magnetron sputtering method,
When a SiO ₂ film formed at a substrate temperature of 200°C was heat-treated for 1 hour at different temperatures, the internal stress of the film did not change and remained at a nearly constant value, regardless of the heat treatment temperature, as shown in Figure 3. . The SiO ₂ film, whose internal stress does not change due to heat, is very suitable as an inter-device insulating film for high-density integrated circuit elements.

In the above example, the SiO ₂ film was created using the magnetron sputtering method, but DC
The present invention can be similarly applied to the sputtering method, the RF sputtering method, or the reactive sputtering method.

<Effects> As described above, by setting the RF power density in the sputtering reaction tank and the temperature of the substrate for sputtering film formation as in the present invention, SiO ₂ deposited on the substrate can be reduced.
The film becomes a stable film whose internal stress does not change due to heat treatment or heat treatment after sputtering, so no excessive force is applied to the substrate on which it is deposited, and no cracks occur in the film itself. This eliminates the occurrence of this phenomenon, making it possible to provide an extremely excellent film as an inter-device insulating film for high-density integrated circuit devices, thereby making it possible to manufacture highly reliable devices.

Therefore, it is possible to provide a film that is not adversely affected by post-process heating as an interlayer insulating film between devices of stacked integrated circuit elements, providing a highly reliable stacked high-density integrated circuit element. It becomes possible to do so.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a laminated high-density integrated device, Fig. 2 is a diagram of the relationship between substrate temperature and internal stress measured using heat treatment conditions as parameters to explain the present invention, and Fig. 3 is a diagram showing the relationship between substrate temperature and internal stress measured using heat treatment conditions as parameters to explain the present invention. FIG. 2 is a diagram showing the relationship between internal stress of a film and heat treatment temperature for explanation.

Claims (1)

[Claims] 1. When forming a silicon oxide film as an interlayer insulating film between devices of integrated circuit elements stacked on a substrate in multiple layers, under a set RF power density and various substrate temperatures. , depositing a silicon oxide film on the substrate,
This silicon oxide film is further subjected to heat treatment at various temperatures, and a deposition temperature at which the internal stress of the silicon oxide film is almost the same at any of the heat treatment temperatures is determined in advance, and the deposition temperature is set
A method for producing a silicon oxide film, comprising forming a silicon oxide film on a desired substrate under RF power density.