JPH11111720A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an electric resistance of wiring constituted in a groove uniform, by heating a semiconductor substrate in a high gradient magnetic field space where unnecessary gas such as steam or the like is shut in high vacuum, and by applying a magnetic force to metallic molecules to move them in the direction of the bottom of the groove when the semiconductor substrate is reflown. SOLUTION: A high vacuum is produced in a reaction chamber 5, and a current is supplied to a superconductive magnet 16 from a power source 25 to generate a high magnetic field in a space where a silicon substrate 1 is arranged and a high gradient magnetic field around a metal net 28, and then the silicon substrate 1 is heated to a temperature less than the melting point of a Cu film by a stage 6 and a heating plate 12. Since Cu molecules are diamagnetic, they receive a magnetic repulsive force in the direction of thickness of the silicon substrate 1, that is, in the direction of the bottom of a groove, from the high gradient magnetic field generated around the metal net 28, thereby flowing into the groove in a state where cavity is not produced to form the Cu film. The surface of the silicone substrate 1 is then cut away to form a Cu wiring having no cavity and uniform electric resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a metal film in a groove.

[0002]

2. Description of the Related Art In a semiconductor device for forming a metal film in a groove by reflowing a metal serving as a wiring in a narrow groove, the metal is sputtered on a grooved substrate, and then the substrate is simply heated to a temperature lower than a melting point. A method is mainly used in which a sputtered metal is made to flow using the diffusion action of the sputtered metal and is poured into a groove to form a metal film.

[0003]

In the above-described conventional method of forming a wiring, the flow force of the flow to the bottom of the groove is small and the metal on both sides of the groove edge is firstly connected in a blitch shape at the groove opening, and the groove is formed. A cavity remains inside. For this reason, the electric resistance value of the wiring formed in the groove becomes non-uniform, the electric resistance value becomes non-uniform, and the characteristics of the semiconductor device vary.

An object of the present invention is to provide a method of manufacturing a semiconductor device in which the electric resistance value of wiring formed in a groove is made uniform and uniform characteristics are obtained.

[0005]

According to the method of manufacturing a semiconductor device of the present invention, when reflowing a semiconductor substrate, the substrate is heated in a high magnetic gradient magnetic field space in a state where unnecessary gases such as water vapor are cut off in a high vacuum. Then, a magnetic force is applied to move the metal molecules toward the groove bottom. As a means for generating a high magnetic gradient magnetic field, a superconducting magnet or a magnetic metal net is used.

[0006]

Next, the present invention will be described with reference to the drawings. 1 and 2 are a sectional view of an apparatus for explaining the embodiment of FIG. 1 of the present invention and an enlarged view of a part of a substrate. In FIG. 2A, the silicon substrate 1 before the step of forming the in-groove metal wiring film of the semiconductor device has a metal film formed in the groove on the surface of the silicon substrate 1 in which the groove 2 has been processed, for example, a copper wiring in the groove. In forming the Cu film, a Cu film 3 is formed on the edge of the opening of the groove 2 and a Cu film 4 is formed on the bottom of the groove 2 by sputtering or the like in a previous step. The reflow process is performed from this state.

In FIG. 1, the silicon substrate 1 before the step of forming a metal wiring film in a groove of the semiconductor device is placed on a stage 6 having a built-in heating heater provided in a reaction vessel 5, and the inside of the reaction vessel 5 is Is evacuated to about 0.018 Pa by a vacuum pump 6, a valve 7, and a pipe 8. Next, an appropriate amount of an inert gas such as an argon gas is supplied through an inert gas supply cylinder 9, a valve 10, and a pipe 11. In the upper part of the silicon substrate 1,
A heating plate 12 having a built-in heating heater is provided, and the stage 6 and the heating plate 12 are connected to a heater heating amount control device 15 by lead wires 13 and 14.

A cylindrical superconducting magnet 16 made of, for example, an NbTi conductor as a magnetic field generating means is arranged outside the reaction vessel 5, and the heat shield plate 1 is arranged so as to surround the superconducting magnet 16.
7 are surrounded by a vacuum insulated container 18 around them. The superconducting magnet 16 and the heat shield plate 17 are thermally integrated with a second stage 20 having a cooling temperature of 4.2K and a first stage 21 having a cooling temperature of 80K, for example, at a predetermined temperature. Is cooled. The helium refrigerator 19 is connected by a helium gas compressor 22 for working fluid, a high-pressure pipe 23 and a low-pressure pipe 24. The superconducting magnet 16 is connected to a power supply 25 by lead wires 26 and 27, is supplied with a predetermined current, and generates a predetermined magnetic field.

A wire mesh 28 made of a magnetic material, for example, high nickel stainless steel, for generating a high gradient magnetic field is disposed on the upper portion of the silicon substrate 1. Here, the superconducting magnet 1
The substrate 6 is cut by the stage 6 and the heating plate 12 without generating a magnetic field in the space where the silicon substrate 1 is disposed without supplying electricity to the substrate 6.
When heated to about 450 ° C., which is lower than the melting point of the film 3,
As shown in FIG. 2B, the flow force of the flow to the groove 2 is small, and the Cu films 3 on both sides of the groove edge are joined in a blitch shape at the groove opening, and the cavity 29 is formed inside the groove. Remains. For this reason, the electric resistance value of the wiring formed in the groove 2 becomes non-uniform, the electric resistance value becomes non-uniform, and the characteristics of the semiconductor device vary.

Therefore, a current is supplied from the power supply 25 to the superconducting magnet 16 so that, for example, 5
A high magnetic field of T is generated to create a high gradient magnetic field around the wire mesh 28, and the silicon substrate 1 is moved to the stage 6 and the heating plate 12
When the substrate is heated to about 450 ° C., which is lower than the melting point of the Cu film 3, the Cu molecules are diamagnetic and receive a magnetic repulsive force from a high gradient magnetic field generated around the wire mesh 28, and the Cu molecules are When a force is pushed in the thickness direction of the upper surface of the groove 1, that is, in the direction of the bottom of the groove 2, the Cu film 30 flows into the groove 2 without forming a cavity as shown in FIG. After that, when the surface of the silicon substrate 1 is scraped off, the wiring becomes as shown in FIG. 2D, and a Cu wiring 31 having a uniform electric resistance without a cavity is formed to obtain uniform characteristics of the semiconductor device. Can be.

Here, when the magnetic susceptibility of the wiring material is negative, that is, the anti-magnetic susceptibility is large, the wire netting 28 is unnecessary, and the metal film is formed only by the magnetic gradient generated near the magnet opening generated by the superconducting magnet 16. A reaction force with respect to the direction of the magnetic field can be obtained for the metal molecules.

When the susceptibility of the wiring material is positive and the susceptibility is small, as shown in FIG. 3, the wire mesh 28 is located in the magnetic field space generated by the superconducting magnet 16 and between the silicon substrate 1 and the stage 6 or It is arranged on the back side of the stage 6, and generates a magnetic attraction force on the metal molecules of the wiring material so that the metal molecules can flow toward the bottom of the groove 2. When the magnetic susceptibility of the wiring material is positive and the magnetic susceptibility is large, the wire mesh 28 is unnecessary for the superconducting magnet 16, and the metal molecules of the metal film are formed only by the magnetic gradient generated near the magnet opening generated by the superconducting magnet 16. A magnetic attraction force acting in the direction of the magnetic field can be obtained.

In order to control the magnetic repulsive force or the magnetic attractive force during the reflow process, the value of the current supplied to the superconducting magnet is controlled, and the relative position between the magnet 16 and the silicon substrate 1 is controlled by moving means or the like. Can be.

In this embodiment, NbTi is used for the superconducting magnet.
Although a conductor magnet was used, Nb ₃ Sn conductor or Nb ₃ A
The same effect can be obtained by using a conductor, a high-temperature superconducting conductor, a room-temperature electromagnet, or a composite magnet made of these materials. The same effect can be obtained by using a normal-conducting magnet, a permanent magnet, or a permanent magnet and an iron yoke. If the direction of the magnetic attraction force is the same, a similar effect is produced.

Therefore, according to the present invention, since a magnetic force is generated to move the metal molecules for wiring in the direction of the bottom of the groove, it is possible to form a metal film flowing into the groove without forming a cavity in the groove. Therefore, a metal wiring having uniform electric resistance is formed, and uniform characteristics of the semiconductor device can be obtained.

In this embodiment, a helium refrigerator is used as the refrigerator 19, but other devices using nitrogen, air, hydrogen, chlorofluorocarbon-based gas or Peltier according to the required cooling temperature of the magnet. An electronic device using an element may be used. Gifford McMahon, Solvay, Stirling, Collins type expander type, expansion turbine type, expansion valve type, and equipment combining these are used as refrigerators using gas as the working fluid. Good.

FIGS. 4 and 5 show another embodiment according to the present invention. FIG. 4 differs from FIG. 3 in that a magnetic gradient generating means 32 having small permanent magnets is disposed in place of the wire mesh 28. As shown in FIG. 5, the magnetic gradient generating means 32 is a flat plate 33 made of a non-magnetic material such as FRP resin.
The small permanent magnets 34 may be arranged densely, and the magnetic pole directions of the small permanent magnets 34 may be unified or arranged alternately with the NS poles. According to the present embodiment, since the electromagnetic magnet is not used, there is an effect that the device can be made compact.

[0018]

According to the present invention, a magnetic force is generated to move the metal molecules for wiring toward the bottom of the groove, so that a metal film flowing into the groove without forming a cavity in the groove can be formed. Therefore, a metal wiring having uniform electric resistance is formed, and uniform characteristics of the semiconductor device can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the structure of a semiconductor manufacturing apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view illustrating a step of forming a film on a silicon substrate by the semiconductor manufacturing apparatus of FIG.

FIG. 3 is a diagram illustrating a semiconductor manufacturing apparatus according to another embodiment of the present invention.

FIG. 4 is an explanatory view of a semiconductor manufacturing apparatus according to another embodiment of the present invention.

FIG. 5 is an explanatory view of a magnetic gradient generating means used in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Groove, 3 ... Cu film, 5 ... Reaction vessel, 6 ... Stage, 16 ... Superconducting magnet, 28 ... Wire mesh.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Minoru Morita 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref.

Claims (1)

[Claims] In a method of manufacturing a semiconductor device, a wiring metal film at a groove edge is heated by a heating means in a groove on a surface of a semiconductor substrate and caused to flow into the groove, wherein the metal film flows into the groove. A method of manufacturing a semiconductor device, wherein a magnetic gradient is generated in a space including a surface of the semiconductor substrate by a magnetic field generating means directly or through a magnetic gradient generating means in a direction to be made.