JPS61289635A - Surface flatterning - Google Patents

Abstract

PURPOSE:To flatten easily the thin film surface having a roughness in a fewer number of processes by a method wherein the surface is etched back by performing an ion beam milling from the oblique direction. CONSTITUTION:The dependency of the etching rate on the incident angle of the ion beam at the time of an ion beam milling is classified roughly into one reaching the maximum at a vertical incidence (theta=0) like an Au ion beam, for example, and one reaching the maximum at theta=40 deg.-60 deg. like an Si ion beam, for example. In whatever cases, when the ion incident angle theta is 60 or more, the etching rate decreases with an augmentation of the incident angle and dwindles into zero at an incident angle of 90 deg.. Accordingly, when the thin film surface having a step difference is etched backed at an ion incident angle theta, there exists an incident angle theta that an etching rate R (m) on the stepped inclined planes of the surface becomes larger compared to an etching rate R (theta) on the flat parts of the surface. By performing an etching back at this incident angle, the thin film on the protruded parts is selectively etched. By this way, an etching is selectively applied the protruded parts of the surface utilizing the dependency of the etching rate on the incident angle of the ion beam and the thin film surface can be flattened.

Description

[Detailed description of the invention] [Summary] Ion beam milling error due to d2? With your own pack,
In this method, the incident angle of the ion beam is set such that the etching rate in the direction parallel to the substrate at the stepped portion is larger than the etching rate in the depth direction l: at the flat portion. .

Thereby, planarization can be easily achieved with fewer steps.

[Industrial application field]

The present invention relates to an etch pack method using ion beam milling as a surface planarization technique in the manufacturing process of semiconductor devices.

[Conventional technology]

Currently, planarization of an interlayer insulating film or metal wiring is considered to be an essential technique in order to prevent disconnection at one step in multilayer wiring for increasing the density and speed of semiconductor devices. The etch e-pack method, which is conventionally used as a planarization method,
The sputter etch method will be explained.

1) Example 2 of planarization using etch-back method C; Fig. 4 (α)
If there is a step formed by the metal wiring batten 12 on the insulating layer 11, for example, it is absolutely necessary to deposit Si0.15 by sputter deposition or plasma CVD method, and then apply a resist etc. Then, the resist surface is flattened using the fluidity of the resist (Fig. 4(b)).
). Thereafter, etching is performed using, for example, CF/Ox plasma under conditions where the etching speed of the resist 14 and the SzO, 13 are equal (FIG. 4(O)). According to the above step I, the recessed region can be filled with an insulating film and 1.1dii can be planarized. However, with this method, when planarizing deep steps, there are severe limitations in that it is difficult to planarize the surface due to the resist, and that the etching speeds of the resist and the material to be planarized must be equal. Problems such as this arise.

2) Example of planarization by sputter etching 1: ζ as shown in FIG. 5 (α); ζ on the insulating film 21;
For example, if there is a step difference due to
It is deposited by 25K sputter deposition or plasma CVD method (FIG. 5(b)). After that, the surface is sputter etched using Ar plasma. Due to the angular dependence of sputtering efficiency, the corners of the stepped portion are selectively etched, resulting in a gradual step (FIG. 5(C)). This method only selectively etches the corners of the stepped portions, and sufficient planarization is not achieved.

[Problem that the invention seeks to solve]

As mentioned above, 1: With the conventional method, it is difficult to flatten deep steps, the etching conditions are strict, or only the corners of the step are selectively etched and sufficient planarization cannot be achieved. , it was still insufficient.

[Means for solving problems]

The present invention is a substrate! Forming a thin film with a thickness equal to or greater than that of the two-step difference between the first and second sections; In ion beam milling; It is characterized in that the incident angle of the beam is set to such an angle that the etching rate in the direction parallel to one plate in the stepped portion S is greater than the etching rate C in the depth direction of the flat portion.

[For production]

According to the above, by utilizing the dependence of the etching rate on the incident angle of the ion beam, it is possible to selectively etch the convex portions of the surface and flatten the surface.

The ion incidence angle is set to the substrate normal 1 as shown in Figure 5 (α);
When defined at an angle of 0 with respect to the general C; ion beam
The dependence of the etching speed in milling on the beam incidence angle is
For example, haze like Ah: Maximum at normal incidence (0■0) (Fig. 5 (j)-51) and 1 like Si:
Maximum at θ-40° to 60° (Fig. 5(b)-
32) and (:). In either case, when the ion incidence angle θ is 60° or more, the etching rate decreases as the incidence angle increases and becomes zero at 90°.

Therefore, when a surface with steps is etched and packed at an ion incidence angle θ as shown in FIG.
From the dependence of the beam incidence angle and the step shape C=, the etching speed R(θ) on the step slope is the same as the etching speed R(θ) on the flat part.
There is a θ that is larger than θ). The etch pack at this incident angle allows selective etching on the thin film on the convex portion (hereinafter referred to as oblique ion beam milling).

〔Example〕

As an example of the present invention, S with a width of 1 μm and a thickness of 0.5 μm is used.
FIG. 1 shows a case where only the concave region formed by the film bump is left with C:A cram, and the surface is flattened. Above S g Q
Au 52 is deposited on the entire surface of the uneven surface ζ consisting of the film pattern 51 by, for example, 0.4μ by sputter deposition method C (first
Figure (α)). Then, for example, ion beam milling (ion beam 55) with an ion incidence angle of about 70°
Perform sex back. At any given time, the etching speed of the stepped slope is about five times that of the flat part, and As&t/selective C: etching of the convex part can be performed (FIG. 1(b)). The above sex back fsi
By performing this process until the O1 film is exposed, the surface is flattened, leaving only the Sin and Am in the concave areas of the pattern (FIG. 1C).

〔Effect of the invention〕

As explained above, by etching back using oblique ion beam milling, planarization can be easily achieved with a small number of steps. This planarization etch-pack method includes the necessary planarization of the multilayer wiring 12 and self-aligned batten formation using a concave pattern.

It has the advantage of having a wide range of application fields0

[Brief explanation of the drawing]

The first factor -) to (ff) are cross-sectional views of the main steps of the embodiment of the present invention, and the second factor≠structure is a diagram for explaining the present invention in detail. Figures 3(a) and 1k) are diagrams for explaining the definition of the ion incidence angle and the relationship between the ion incidence angle and the etching rate, Figure 4+8) ~ (C) and Figure 5 (a) ~ <01 are process diagrams of the first conventional example and the second conventional example, respectively. DESCRIPTION OF SYMBOLS 11... Insulating film, 12... Metal wiring, 13... Interlayer insulating film, 21... Insulating film, 22... Metal wiring, 2
5... Interlayer insulation j[,51...Sin! (bang)
, 52... Aμ, 53... Ion beam patent applicant Nippon Telegraph and Telephone Corporation Agent Benten clerk Gobe Tamamushi (2 others) 1JJIT+ Process area of embodiments of the invention Figure 1 Details of the invention Fig. 5 shows the second conventional example.

Claims (1)

[Claims] A step of depositing a thin film on the surface of a substrate having a step on the surface, the thickness of which is comparable to or thicker than the step; surface flattening characterized by including the step of etching back the thin film by ion milling at an angle such that the etching rate in the direction parallel to the flat part is higher than the etching rate in the depth direction of the flat part. Method.