JPH0223030B2 - - 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> SiO ₂ is widely used as an interlayer insulating film for multilayer wiring in integrated circuit elements, a surface protective film, and the like. Recently, these SiO ₂ films have been increasingly produced by the sputtering method. However, SiO ₂ films created by applying the conventional sputtering method do not undergo thermal oxidation.
The film density was lower than that of SiO ₂ , and there were major problems with thermal stability, such as the internal stress of the film changing significantly during heat treatment after film formation.

As mentioned above, the SiO ₂ film can be used as a surface protective film or as a
As long as the film is used as an interlayer insulating film for multilayer wiring having a laminated structure with relatively few layers, a film produced by the conventional sputtering method as described above can also be used. However, in the case of stacked high-density integrated circuit elements, which are being developed with dramatic improvements in the degree of integration, there are problems with the SiO ₂ film produced by the above-mentioned conventional method.

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 film 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-mentioned laminated high-density integrated circuit elements, SiO ₂ film or silicon nitride film is used as the insulating film inserted between the devices, but it must ensure electrical insulation between the devices, and In the process of stacking layers, they are often exposed to thermal processes and heat treatments, and even when exposed to such working environments, they must not deform or peel off from the device surface. However, the SiO ₂ film produced by the conventional method described above has a low film density and therefore does not have sufficient electrical insulation, and the internal stress in the thin film changes during heat treatment, causing the silicon substrate to deteriorate. There were some inconveniences such as deformation. These inconveniences can be somewhat alleviated by performing heat treatment at a high temperature for a long time after film formation. However, depending on the integrated circuit element, it is often impossible to apply heat treatment at high temperature and for a long time, and there is a problem that the SiO ₂ film cannot be used as an insulating layer.

<Object of the Invention> The present invention is directed to the production of a product manufactured by the above conventional manufacturing method.
This was done in view of the problems with SiO ₂ film, and it is possible to create a thermally stable SiO ₂ film by sputtering, which maintains a high film density and whose internal stress hardly changes even after heat treatment. The object of the present invention is to provide a manufacturing method that can obtain the same.

<Example> A material to be sputtered is set on one of opposing electrodes provided in a reaction tank of a magnetron sputtering apparatus, and an integrated circuit device substrate to be coated with a SiO ₂ film is set on the other electrode. . The electrode side on which the integrated circuit device is set is equipped with heating means,
The substrate during sputtering is maintained at a predetermined temperature.
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 sputtering material is ejected from the sputtering material.
Molecules or atoms for creating a SiO ₂ film are deposited on the substrate surface to create a SiO ₂ thin film. The SiO ₂ film created by sputtering is heat treated to stabilize internal stress.

Figure 2 is a diagram showing the relationship between the film quality of the SiO ₂ film created by the above magnetron sputtering and the substrate holding temperature, where curve A is for the SiO ₂ film without heat treatment after sputtering, and curve B is for the SiO 2 film after sputtering. These are measurement results for a SiO ₂ film heat-treated at 800°C for 1 hour. Film quality was evaluated based on the etching rate (×10 ³ Å/min), and the etching solution was buffered hydrofluoric acid. As is clear from curves A and B in the same figure, the SiO ₂ film sputtered at room temperature without heating the substrate has a very high etching rate.
Even if heat treatment is performed at 800° C. for 1 hour to improve the film quality, the etching rate does not decrease to the level shown by the SiO ₂ film created by thermal oxidation (approximately 1000 Å/min).
However, the etching rate of the SiO ₂ film created by maintaining the substrate temperature at 350°C during sputtering was that of thermally oxidized SiO ₂ even without heat treatment after sputtering.
The etching rate is approximately the same as the film etching rate. This is SiO ₂ sputtered while the substrate is heated.
The film shows that the quality of the film is dense. In addition, the SiO ₂ film created by keeping the substrate temperature at 200°C is 800°C.
When heat treatment is performed for 1 hour, the etching rate becomes comparable to that of a thermally oxidized SiO ₂ film. That is, the SiO ₂ film produced by sputtering while the substrate is heated and held has a significantly denser film quality and higher electrical insulation.

The internal stress of the dense SiO ₂ film described above is stabilized by subsequent heat treatment.

FIG. 3 is a diagram showing the relationship between elapsed time and internal stress at each heat treatment temperature, where the heat treatment temperatures were selected to be 600°C for curve a, 800°C for curve b, and 900°C for curve c. At any treatment temperature, there is a large change in the initial 10 minutes of heat treatment, and then there is almost no change. In other words, the internal stress has been stabilized.

Based on the above results, a sputtered SiO ₂ film prepared at a substrate temperature of 250°C was heat treated at 800°C for 10 minutes, and the resulting SiO ₂ film had an etching rate of 1000 Å/min and an internal stress of 2.6× ¹⁰⁹ dyn/ ^cm2
It was hot. Even if this SiO ₂ film was further heat-treated at 800°C or again at a temperature below 800°C, no change in etching rate or internal stress was observed, and the film was dense and had stable internal stress. condition.

The above-mentioned film with stable internal stress is suitable as an inter-device insulating film for laminated high-density integrated circuit elements because it does not deform due to heat treatment during work or exerts excessive force on the substrate. .

Note that the sputtering is not limited to the magnetron sputtering method, but the present invention can also be applied to the RF sputtering method.

<Effects> As in the present invention, by applying a relatively short heat treatment to a sputtering film formed by heating the substrate to 200°C or higher, a thermally stable silicon oxide film can be created while maintaining a high film density. As a result, it is possible to form an interlayer insulating film in a laminated high-density integrated circuit element without adversely affecting the elements already formed in the lower layer.
As a result, it becomes possible to provide highly reliable laminated high-density integrated circuit elements.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a laminated high-density integrated device, and FIG. 2 is a diagram showing the relationship between etching rate and substrate temperature during sputtering to explain the present invention.
FIG. 3 is a diagram showing the relationship between internal stress of a film and heat treatment time for explaining the present invention.

Claims (1)

[Claims] 1. A method for manufacturing a silicon oxide film as an interlayer insulating film between devices of integrated circuit elements stacked on a substrate in multiple layers, the method comprising: setting the substrate holding temperature at 200°C or higher; , a step of depositing a silicon oxide film on a substrate by a sputtering method, and a step of heat-treating the silicon oxide film at a temperature of 600 to 900°C for within 20 minutes, to reduce internal stress for subsequent heat treatment. A method for producing a silicon oxide film, which is characterized by creating a stable thin film with little change in .