JPH01230254A - Flattening method - Google Patents

Abstract

PURPOSE:To suppress the yield of coarse parts on the surface due to damage of resist and to flatten an insulating film, by projecting ion beams on the surface of the resist at a specified angle, and performing etching. CONSTITUTION:A wiring 1a that is a protruding part is formed on a substrate 1 on which a semiconductor element is formed. An SiO2 film 2 as an interlayer insulating film is deposited on a substrate 1. Resist 3 is applied on the film 2 and baked. At this time, the surface of the resist 3 is flattened. Ion beams are projected on the surface of the resist 3 at an angle of 15-50 deg.C, and the resist 3 and the film 2 are etched. In this way, the interlayer insulating film can be flattened without the yield of coarse parts on the resist. When the ion beams are projected on the side surface of the protruding part of the insulating film at 15-90 deg.C without using the resist and on the upper surface of the insulating film at an angle less than 10 deg., the protruding part is selectively etched, and the insulating film can be flattened.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Field of Industrial Application The present invention is a method for manufacturing a semiconductor device, and relates to a planarization method for flattening the surface of a film such as an interlayer insulating film.

2. Description of the Related Art Multilayer wiring technology is an indispensable technology for reducing the area occupied by wiring in semiconductor integrated circuit devices. In multilayer wiring, it is important to planarize the interlayer insulating film in order to avoid disconnections and short circuits in the wiring.

Methods for flattening interlayer insulating films include, for example, a glass coating method (spin-on glass method) in which a liquid containing an organic silicon compound is spin-coated and then heat-treated to make it vitrified to flatten its surface, and a method for forming grooves between wirings is used. After depositing an insulating film to completely fill the area and flattening the surface by spin-coating a planarization sacrificial film such as photoresist on top of it, the planarization sacrificial film and the insulating film have approximately the same etching rate. There is an etch-back method in which the entire surface is etched and flattened under certain conditions. However, Japanese Patent Laid-Open No. 61-285737 proposes a flattening method that combines these two methods.

C) Problems to be Solved by the Invention Flatness in Etch-back Method An ion beam etching method is an etching method in which the sacrificial film and the insulating film are etched at approximately the same etching speed. In order to increase the etching rate in ion beam etching, it is sufficient to increase the ion acceleration energy and current density.However, if the acceleration energy and current density are increased, the resist used as the planarity sacrificial film has poor heat resistance, so damage may occur. If the acceleration energy and current density are reduced in order to minimize the damage, the etching rate decreases and etching back takes time, resulting in poor efficiency.

The present invention has been made with these points in mind, and is intended to flatten an interlayer dielectric film using an ion beam without causing resist roughening or without using a resist.

2) Means for Solving the Problems The present invention is a planarization method for planarizing the surface of an insulating film formed on a substrate having a convex portion, in which a resist is placed on the insulating film so that the surface becomes flat. The resist and the insulating film are etched by irradiating the surface of the resist with an ion beam at an angle of 15° to 50°, or the side surface of the convex part of the insulating film is etched with an ion beam of 15” to 50°. 90#
Further, the insulating film is etched by irradiating the ion beam at an angle of 10° or less with respect to the upper surface of the insulating film.

e) Effect Damage to the beam irradiated object (resist or insulating film) and etching rate vary depending on the incident angle of the ion beam. Therefore, 151
By irradiating the ion beam at an angle of 50° to 50°, the insulating film can be planarized without lowering the etching rate, while suppressing damage to the bottom. In addition, without using a resist, it is possible to apply a coating film of 15 to 90' to the side surface of the convex part of the insulating film and 15 to 90' to the top surface of the insulating film.
The insulating film can be flattened by irradiating the ion beam at an angle of 0'' or less and setting the etching rate for the convex portions higher than for other portions.

Example 1 FIG. 1 is a process explanatory diagram showing an example of the method of the present invention. (1) is a substrate on which a semiconductor element is formed, and on the substrate (1), a convex wiring (la) is formed (Fig. 1A), and this wiring (ig) is For example, the width is 53
1111. The height is 0.64m1.

On this substrate (1), a 5iOz film (2
) by CVD method (usually IECVD, plasma CVD, etc.)
．． This 5i02 film (Fig. 1B) is deposited in two layers (Fig. 1B).
2) Regis above) (3) (For example, Tokyo Ohkabu 'OMR'
> is spin-coated for 30 seconds at 5HOr, p, m, and then baked at 140°C for 30 minutes (Fig. 1C). At this time, regardless of the unevenness of the 5iOz film (2) due to the arrangement: The resist (3) surface becomes flat.

The resist (3) and the 5i02 film (2) are irradiated with an ion beam in a direction at an angle of 0 to the resist (3) surface.
(Fig. 1D).

The first image shows the surface state of the resist (3) after etching at the incident angle θ of the ion beam using Ar gas.

(Hereinafter, blank spaces) Table 1 Here, the accelerating voltage and ion current density of ion beams A, B, and C are 500 V -0.7 mA/am2.5
00V-1.4mA/cm2.100OV ・1.4m
Indicates the case of A/cyn', O indicates good surface condition,
△ indicates that the surface condition is somewhat poor, and × indicates that the surface condition is poor. 1. Poor surface condition means that the surface is scorched and roughened (uneven) due to damage from the ion beam.

As shown in Table 1, when 0 is 50@ or less, the damage to the resist (3) is small and ion beam etching can be performed without roughening the surface.

However, if the angle .theta. is too small, the etching rate becomes extremely small. FIG. 3 shows the correlation between the incident angle .theta. of the ion beam and the etching rate. In this figure, the etching rate is normalized. The etching rate gradually increases as the angle decreases from the perpendicular direction (90") to the substrate (resist) surface, but after peaking around 35 degrees, the etching rate begins to decrease, and after 15 degrees, it suddenly decreases. Etching rate drops, last (09)
will no longer be etched.

That is, if the incident angle θ is 15° or more, etching can be performed without reducing the etching rate.

Therefore, the ion beam is irradiated onto the substrate (resist) with an incident angle set between 15' and 50°. Then,
Resist (3) and SiO2 film (2) are removed by ion beam.
) is etched at the same etching rate, and the SiO2 film (2) with a flattened surface is completely exposed (1st!l:
IE).

Next, a planarization method that does not use a resist and does not require consideration of damage to the resist caused by an ion beam will be described. As shown in Figure 3, the etching rate is
If it is 5" or more, it will be equivalent to or more than 90". However, below 15°, the etching rate becomes extremely small. Therefore, ion beam etching is performed by setting the angle so that a high etching rate is applied to the convex portions and a low etching rate is applied to other parts.

FIG. 2 shows a process explanatory diagram of one embodiment, FIG. 1A,
Similarly to B, first, a 5iOz film (2>) is deposited on the substrate (1) on which the wiring (1a) is formed as a convex portion (FIG. 2A) (2130 B).

Convex portions (2a) due to wiring (1a) of this SiO2 film (2)
) is 2, and the surface parallel to the board surface! , the side surface of the convex portion is marked as ■. Then, the incident angle θ with respect to the substrate surface ■ is 10"
The ion beam is irradiated at the angle below and at an angle where the incident angle G is 15° to 90° with respect to the side surface
) 0 for example θ-5. If a-50°, the etching rate of the side surface (■) is about 12 times that of the substrate surface (■), and the thickness of the 5iOz film (2〉) on the substrate surface I is ff.
When i/12 etching is performed, a flat Si02g (2>) with the protrusion (2a> removed) is obtained (Fig. 2D). In order to reduce the film thickness, for example, in the above case, if the film is t!-m5, an extra amount may be deposited in advance using a hot acid solution of about 4,200 degrees Celsius.

Therefore, there is no need to consider resist damage.
The O2 film can be flattened, and since no resist is used, the number of steps and cost can be reduced.

In addition, if the ion beam is irradiated evenly from both sides of the convex part,
Even better planarization can be achieved, and the reduction in film thickness can be reduced to 50%.

In addition, when the wiring pattern (40) is two orthogonal wiring lines as shown in Fig. 4, if α-45° is set, a relatively high equivalent etching rate can be obtained for any wiring line. A 5iOz film can be flattened well.

G) Effects of the Invention As is clear from the above description, the present invention can eliminate surface roughness due to resist damage without lowering the etching rate by irradiating the resist with an ion beam at an angle of 15° to 50°. Suppress the occurrence of RMK
can be flattened well or without using resist.
By irradiating the side surface of the convex part of the insulating film with an ion beam at an angle of 15" to 90° and at an angle of 10° or less to the top surface of the insulating film, the convex part is selectively etched, and the insulating film is etched. can be flattened.

[Brief explanation of the drawing]

Fig. 1 is a process explanatory diagram of one embodiment of the present invention, Fig. 2 is a process explanatory diagram of another embodiment, Fig. 3 is a correlation diagram of the ion beam incident angle and etching rate, and Fig. 4 is a diagram of the relationship between the ion beam incident angle and the etching rate. It is an explanatory view of another example.

Claims (2)

[Claims] (1) An insulating film is formed on a substrate having a convex portion, a resist is formed on the insulating film so that the surface is flat, and an ion beam is irradiated at an angle of 15° to 50° with respect to the surface of the resist. etching the resist and insulating film by irradiating;
A planarization method comprising planarizing the surface of the insulating film. (2) In a planarization method for flattening the surface of an insulating film formed on a substrate having a convex portion, the angle is 15° to 90° with respect to the side surface of the convex portion of the insulating film and with respect to the top surface of the insulating film. te1
A planarization method characterized by etching an insulating film by irradiating an ion beam at an angle of 0° or less to planarize the insulating film.