JP2681466B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention mainly forms a metal thin film with a good step coverage in a groove of a fine width formed on the surface of a semiconductor substrate for VLSI. The present invention relates to a method of manufacturing a semiconductor device. (Prior Art) Conventionally, as a method of forming a metal thin film having good step coverage in a concave groove on the surface of a semiconductor substrate, for example, a first method is known.
Electrodes d and e connected to high frequency power supplies b and c are provided facing each other in a vacuum chamber a into which Ar gas is introduced as shown in the figure, and a target f such as Al is attached to the plate surface of one electrode d and a semiconductor is formed. There is known a bias sputtering apparatus in which a substrate g is attached to the plate surface of the other electrode e and power is applied to the target f and the substrate g. In this device, by applying a negative potential also to the substrate g side, Ar ⁺ in the plasma rushes vertically into the substrate g and adheres to the inner surface of the concave groove h on the surface of the substrate g as shown in FIG. The inclined portion j of the growing metal thin film i is Ar
It is sputtered by ^{+ and} can be attached to the bottom of the concave groove h. The width W of the groove h is 1 to 3 μm, and the depth D is
The thickness is 0.8 to 2 μm, and when the metal thin film i is formed thereon by the bias sputtering method, the entire inside of the concave groove h can be sufficiently covered as shown in FIG. 3, but the ordinary sputtering method in which power is not applied to the substrate g is used. At this time, as shown in FIG. 4, the metal thin film i having a sufficient thickness cannot be formed at the bottom of the groove h. In general, in an LSI, a metal thin film i having a poor step coverage in the concave groove h is apt to cause a failure due to disconnection of the thin film, so that the metal thin film is often formed by the bias sputtering method. (Problems to be Solved by the Invention) In the bias sputtering method, when the groove h has a relatively large aspect ratio, that is, a depth-width ratio of 1 or less, a metal thin film i is formed with a sufficient thickness at the bottom thereof. Yes, but recently
When the recessed groove h has an aspect ratio of 1 or more like LSI, good step coverage cannot be obtained even by the bias sputtering method. That is, when the width of the concave groove h is narrowed, as shown in FIG. 5, even if the slanted portion j of the metal thin film i is sputtered by Ar ⁺ , the sputtered particles are re-incident on the facing slanted portion and the entrance There is a drawback that the deposition progresses so as to close the portion and does not deposit on the bottom portion, and as shown in FIG. 6, a void k is generated inside and the disconnection is likely to occur. In this case, it was attempted to heat the substrate g and melt the metal thin film i on its surface by conduction heat, but the substrate g was damaged by the heat and the thermal efficiency was poor. It is an object of the present invention to propose a method of manufacturing a semiconductor device in which a metal thin film is formed in a fine groove of a VLSI, which makes it difficult to form a metal thin film even by the bias sputtering method. (Means for Solving the Problem) In the present invention, there is provided a method for manufacturing a semiconductor device by forming a metal thin film other than aluminum or an aluminum alloy in a groove having a fine width formed on the surface of a semiconductor substrate. To achieve the above object by heating to a temperature at which only a metal thin film other than aluminum or an aluminum alloy attached to the semiconductor substrate is fluidized by a metal thin film heating device installed behind the semiconductor substrate. I chose For the metal thin film heating device, it is preferable to use an infrared heater or an induction heating coil in which the amount of heat is concentrated on a metal thin film other than the aluminum or aluminum alloy rather than the semiconductor substrate. (Operation) In the manufacturing process of a semiconductor device, a semiconductor substrate having a groove having a fine width of 1 or more with an aspect ratio formed on the surface is provided in a vacuum chamber, and the groove is formed by sputtering, vacuum deposition, or the like. A metal thin film made of a metal other than Al or an Al alloy is formed. In this case, the metal thin film cannot be formed with a sufficient thickness at the bottom of the groove because the groove has a fine aspect ratio of 1 or more. However, the metal thin film heating device behind the substrate during the formation of the metal thin film. Is heated to fluidize only the metal thin film attached to the substrate, the metal thin film that tends to accumulate near the entrance of the groove flows to the bottom of the groove, and the metal thin film is sufficiently filled in the groove. It is possible to form a thick metal thin film. (Embodiment) An embodiment of the present invention will be described with reference to FIG. 7 in the drawing. In the figure, reference numeral (1) is a vacuum chamber having a vacuum exhaust port (2), and (3) is the vacuum chamber ( 1) a cathode provided facing the inside, (4) a metal target on the front surface of the cathode (3), and (5) a silicon facing the target (4) via an openable shutter (6). A semiconductor substrate made of a wafer is shown, and the semiconductor substrate (5) is placed at a position facing a target (4) and into the vacuum chamber (1).
The substrate (5) is rocked by a platen (8) which can be rocked at a position along a conveyor (7) for carrying in. A metal other than Al and Al alloy is used for the metal target (4). For example, high frequency power is applied to the cathode (3) from a power source (9), and when the substrate (5) faces the front surface of the target (4), the shutter (6) retreats, and the surface (5a) of the substrate (5). The metal substance from the target (4) is attached to the film by sputtering to form a metal thin film other than Al and Al alloy. When there are fine grooves or holes with an aspect ratio of 1 or more that form a VLSI pattern on the surface (5a) of the semiconductor substrate (5), as described above, the sputtering is sufficient for the grooves. Since it is difficult to form a metal thin film having a uniform thickness, a metal thin film heating device (10) for heating and fluidizing only the metal thin film being formed is provided behind the substrate (5) in the present invention. The metal thin film was made to flow into the bottom of the groove. In the metal thin film heating apparatus (10), a frame-shaped frame (11) to which an infrared heater (10a) is attached in the example shown in FIG. 7 is swung from a retracted position (not shown) to a rear side of a substrate (5) as shown. And the metal thin film formed on the surface (5a) was sequentially heated and fluidized. In the case of VLSI, the substrate (5) has a thin thickness of about 0.4 to 0.6 mm, so about 90% of the infrared rays of the infrared heater (10a) pass through the substrate (5) from behind, It is possible to reach the metal thin film which is being formed on the surface (5a) or has been formed and can be heated to a temperature at which it is fluidized efficiently,
At this time, the substrate (5) absorbs only about 10% of infrared rays, so that the substrate (5) is not damaged by heating. By controlling the electric power to the infrared heater (10a), the temperature of the substrate (5) is kept lower than the temperature of the metal thin film, and only the metal thin film is heated and fluidized. ), The metal thin film (12) having good step coverage can be formed by flowing the fine groove (14) having an aspect ratio of 1 or more formed in the surface (5a). The metal thin film heating device (10) may be composed of an induction heating coil (10b) as shown in FIG. 9, whereby the metal thin film being formed on or formed on the surface of the substrate (5). It is also possible to generate an induced current in the above and heat and fluidize only this to deposit in the groove. Further, as shown in the tenth figure, the metal thin film is formed on the surface of the semiconductor substrate (5) by the metal particles evaporated from the evaporation source (13), in which case the metal thin film is formed from behind the substrate (5). The heating device (10) may heat and fluidize only the metal thin film. (Effect of the Invention) As described above, according to the present invention, in the method for manufacturing a semiconductor device, in which a metal thin film other than aluminum or an aluminum alloy is formed in a groove of a fine width on the surface of a semiconductor substrate, Since the metal thin film heating device installed behind the semiconductor substrate was heated to a temperature at which only the metal thin film other than aluminum or aluminum alloy attached to the semiconductor substrate was fluidized, A metal thin film other than aluminum or an aluminum alloy can be formed so as to be embedded, and a VLSI with few failures such as disconnection can be manufactured, and the metal thin film is formed in the groove without damaging the semiconductor substrate with heat. Since it is possible, there is an effect that productivity is good.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a bias sputtering method, FIG. 2 is a sectional view of a metal thin film formed in a concave groove on a surface of a semiconductor substrate, and FIG. 3 is a concave groove formed by the bias sputtering method. 5 is a sectional view of a metal thin film formed in a groove having a fine width by a bias sputtering method, and FIG. 7 is a sectional side view of an embodiment of the present invention. , FIG. 8 is a sectional view of a metal thin film formed by the apparatus shown in FIG. 7, FIG. 9 and FIG.
The figure is a cutaway side view of another embodiment of the invention. (5) ... semiconductor substrate, (5a) ... surface, (10) ... metal thin film heating device, (12) ... metal thin film other than aluminum or aluminum alloy, (14) ... concave groove,

Claims (1)

(57) [Claims] A method of forming a metal thin film other than aluminum or an aluminum alloy in a groove of a fine width of a semiconductor device formed on the surface of a semiconductor substrate, wherein a metal thin film heating device installed behind the semiconductor substrate A method of manufacturing a semiconductor device, comprising a step of heating only a metal thin film other than aluminum or an aluminum alloy attached to a semiconductor substrate to a temperature at which it is fluidized. 2. The semiconductor device according to claim 1, wherein an infrared heater or an induction heating coil whose heat quantity is concentrated on a metal thin film other than aluminum or aluminum alloy than the semiconductor substrate is used as the metal thin film heating device. Production method.