JPS6250461A - Method for depositing thin film by sputtering - Google Patents

Abstract

PURPOSE:To deposit a thin film on the surface of a substrate so that the small recesses in the substrate are filled by carrying out bias sputtering in an atmosphere contg. a gaseous compound of the nongaseous constituent element of the thin film to be deposited. CONSTITUTION:A tungsten plate or the like is used as a target 10 and high frequency power is supplied to the target 10 from a high frequency power source 11. High frequency power is supplied to a substrate holder 12 from other high frequency power source 13 to apply negative self-DC bias voltage to a substrate 14. Gaseous Ar mixed with about 50% gaseous tungsten hexafluoride or the like is used as a sputtering gas. By this sputtering method, a film 16 is deposited on the substrate 14 so that the micropores 15 in the substrate 14 are filled. The deposited film contains no void and the micropores are perfectly filled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of depositing thin films using sputtering.

[Conventional technology]

It is known that by using bias sputtering, which performs sputtering while applying a bias voltage to the substrate or substrate holder, it is possible to improve the film coverage at the stepped portions of the substrate surface and to prevent the occurrence of microcracks. . Furthermore, the present inventor has discovered that by using bias sputtering, it is possible to fill and deposit wiring metal into, for example, minute contact holes and through holes in the wiring of integrated circuit devices, and to significantly reduce (flatten) the level difference on the surface of this deposited film. I discovered that. Such characteristics are extremely important in multilayering the wiring of integrated circuits.

[Problem that the invention seeks to solve]

However, a more detailed study revealed that the filling of such fine holes (or grooves, generally recesses) is difficult because the aspect ratio (ratio of depth to diameter or planar dimension) of the fine hole is 0. It has become clear that when the diameter is about .8 or higher, the micropores are not completely filled and cavities remain inside the pores. This is due to the following reasons. In other words, in conventional bias sputtering, deposition of atoms and molecules sputtered from the target and sputter etching, which occurs when sputter gas ions are accelerated by the substrate bias and incident on the substrate surface, occur simultaneously on the substrate surface. . Sputtering gas ions are accelerated by a bias electric field that is generated almost perpendicular to the substrate surface, so they are generally incident perpendicularly to the substrate surface, but there are various factors that affect the incidence of atoms and molecules sputtered from the target onto the substrate surface. There is a directional component, and for example, a component incident from an angle is also large. Therefore, when a film is deposited in a micropore with a high aspect ratio using the conventional bias sputtering method, as the film deposition progresses, as shown in FIG. 2(a),
An "overhang" 4 grows in the deposited film 3 due to the obliquely incident component at the entrance of the fine hole 2 of the substrate 1, and the proportion of deposited atoms that enter the fine hole being captured by this "overhang" 4 increases. The rate of incidence inward decreases. As a result, the "overhang" grows more and more, and the incidence of deposited atoms into the micropores becomes more and more reduced, resulting in a vicious cycle that eventually closes the micropore entrances, leaving a cavity 5 inside as shown in Figure 2(b). it is conceivable that.

If such cavities remain, impurities and chemicals may enter the cavities during the manufacturing process when applied to the wiring of integrated circuit devices, causing manufacturing problems, deterioration of reliability, and increased wiring resistance. This is not desirable as it may cause

An object of the present invention is to provide a novel thin film deposition method that greatly improves the drawbacks of the conventional thin film deposition method using bias sputtering.

[Means for solving problems]

The method of depositing a thin film by sputtering of the present invention is characterized in that bias sputtering, in which sputtering is performed while applying a bias voltage to a substrate or a substrate holder, is performed in an atmosphere containing a compound gas of a non-gas composition element of the thin film to be deposited. It is said that

[Effect]

In the method according to the present invention, since the sputtering gas contains a non-gaseous elemental compound gas having a film composition, the ions that are attracted by the bias voltage and are almost perpendicularly incident on the substrate also contain non-gaseous elemental compound ions having a film composition. include. Non-gas elemental compound ions in this film composition contribute to film deposition when incident on the substrate surface, i.e. equivalent to an effective increase in the normal incidence component of sputtered atoms or molecules from the target onto the substrate surface. bring about an effect. Therefore, the film deposition rate within the micropores increases, and “
It is thought that because the micropores can be filled before the overhang ''' blocks the population, it is possible to fill and deposit holes with a higher aspect ratio than in the conventional method.

〔Example〕

The sputtering apparatus used in the examples of the present invention is a standard parallel plate two-electrode high frequency sputtering apparatus. A schematic diagram of a part of the Perjar is shown in Figure 3.

A tungsten plate is used as the target 10, and high frequency power is supplied from a high frequency power source 11. By supplying high frequency power from another high frequency power source 13 to the substrate holder 12 placed facing the target, the substrate 1
4 to induce a negative self-direct current bias voltage. Argon and tungsten hexafluoride (WFe) are used as sputtering gas.
) gas was added by approximately 50%. As the substrate 14, a silicon wafer was used in which a silicon oxide film with a thickness of 1.2 μm was grown on the surface and a contact hole with a diameter of 1.5 μm was formed in this oxide film.

Target power approximately 1kW, substrate self-bias voltage approximately -6
By bias sputtering tungsten at 00V, it was possible to fill with a tungsten film a fine contact hole with a high aspect ratio, which could not be filled with the conventional method. FIG. 1 is a schematic cross-sectional view of a structure in which the fine holes 15 on the surface of the substrate 14 are filled and a film 16 is deposited by the method described above. No cavities were formed in the deposited film with micropores, and the micropores were completely buried.

In the above examples, a combination of a tungsten target and an atmosphere containing tungsten hexafluoride was used, but a combination of a molybdenum target and an atmosphere containing molybdenum fluoride, a combination of a silicon target and an atmosphere containing silane, or a combination of a quartz target and an atmosphere containing silane was used. It is clear that the combination of targets and silane or silane and oxygen containing atmospheres can be widely used for the deposition of metal, semiconductor, and insulator thin films of any material.

Furthermore, it is clear that the sputtering method can be applied not only to high frequency sputtering but also to various sputtering methods such as DC sputtering and DC bias application.

〔Effect of the invention〕

By using the method according to the invention, it is possible to deposit thin films filling small recesses on the surface of a substrate.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of a structure in which a film is deposited by filling micropores on the substrate surface by the method according to the present invention. Figure 2 is a schematic cross-sectional diagram of a structure in which a film is deposited by a conventional method. Figure 3 is a schematic cross-sectional diagram of a structure in which a film is deposited by a conventional method. It is a partial schematic diagram of the Pelger of the high frequency spacing apparatus used in the example of a method. 1.14 ...... Board 2.15 ・
・・・・・・・・・ Micropore 3.16 ・・・・・・・・・
... Deposited film 4 ...... Overhang 5 ...... Cavity 10 ...... Target 11,
13... High frequency power supply 12...
Kawa, Kawa, Substrate Holter 13...... Kawa Substrate Agent Patent Attorney Yoshiyuki Iwasa Figure 1 (a) (b) Figure 2 High Frequency Power Supply Figure 3

Claims (1)

[Claims] (1) A method for depositing a thin film by sputtering, characterized in that bias sputtering, in which sputtering is performed while applying a bias voltage to a substrate or a substrate holder, is performed in an atmosphere containing a compound gas of a non-gas composition element of the thin film to be deposited. .