JPS61137327A - Etching of interlayer insulation film - Google Patents

Abstract

PURPOSE:To provide a through hole of desired shape to the interlayer insulation film by freely changing the shape of heat wire or ion beam in the reactive gas ambience for the operation. CONSTITUTION:The shape of heat wire and ion beam shows the Gaussian distribution. In the case of converged type ion beam, the diameter is about 0.1mum and the shape can be reproduced with high accuracy. The shape of beam become trapezoidal due to the lateral scanning and when the intensity is changed during the scanning, the desired shape can be obtained. When etching is carried out by irradiating the insulation film 2 in the reactive gas ambience, the shape of etching surface can be resembled to the shape of irradiation beam 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of etching an interlayer insulating film, particularly to a method of etching an interlayer insulating film of a semiconductor integrated circuit device.

[Conventional technology]

Conventionally, when etching an interlayer insulating film to form a through hole, after photoresist treatment, wet etching using liquid chemicals, plasma etching, a certain Vh expanded ion etching method, or the above-mentioned three methods are used. Etching has been carried out through a combination of laws.

However, among these etching methods, the ion etching method can perform etching with high dimensional accuracy.

Because it is anisotropic etching, as shown in FIG.
On the other hand, the wet etching method and the plasma etching method have the disadvantage of causing a break called step break at the shoulder 50 portion of the through hole portion 4 when forming the etching. Because of the etching, the shape of the through-hole portion 4 of the insulating film 2 has a slope, and even if the wiring 3 is formed in the next step, the above-mentioned break will not necessarily widen.

Since the through-hole portion 4 expands laterally, it is not suitable for miniaturization, and the slope makes it difficult to obtain an arbitrary shape, making it difficult to obtain a desired through-hole. [Problems] An object of the present invention is to provide a method of etching an interlayer insulating film in which the above-mentioned dots are eliminated and fine through holes are obtained with high accuracy.

[Means for solving problems]

The structure of the present invention is a method for etching an interlayer insulating film by irradiating a hot ray or an ion beam in a reactive gas atmosphere. It is characterized by obtaining a through hole having the shape of.

〔Example〕

The present invention will be described in detail with reference to the drawings.

FIG. 7 is a characteristic diagram showing the relationship between beam intensity and spread used in the embodiment of the present invention. The same figure (note that the beam shape of a heat ray beam, ion beam, etc. has a Gaussian distribution, and the beam diameter is, for example, a focused ion beam used in recent years as a method of maskless etching). For beams, the shape can be reproduced with high accuracy regardless of the diameter between 0.1 and α2μm (°84 Applied Physics Society Proceedings 29p-W-5).Moreover, the beam shape can be made into any shape. For example, if a trapezoidal beam is scanned in the lateral direction of the beam shown in FIG. 7, the shape shown in FIG. m1 can be obtained.

In this case, the sides of the beam have a Gaussian distribution, but °
By gradually increasing the beam strength rtt while scanning, scanning at a constant strength, and then decreasing it sequentially, an arbitrary profile as shown in Fig. 2 can be drawn. If the beam shown in FIG. 2 is scanned not only in the horizontal direction but also in the vertical direction, a sliver-shaped beam having an arbitrary inclination can be obtained.

When the beam formed in this way is irradiated onto the insulating film,
The thick part of the beam *i irradiates the insulating film with a lot of energy and is highly reactive, so the etching speed is high and it can be etched quickly. On the other hand, in areas where the beam intensity is weak, the etching rate is low.

Therefore, when the insulating film is irradiated with a beam having the beam shape shown in FIG. 2, the insulating film 2 begins to be etched in a cross-sectional shape as shown in FIG.
As shown in the figure, when the insulating film 2 is irradiated until it is completely etched away, the shape of the etched surface can be made similar to the shape of the irradiation beam 6. Here, the reactive gas etches the insulating film 2t, but a gas that does not etch the insulating film 2t may be selected for the arrangement tll, and even if some overetching occurs, the width will only expand slightly and the slope will remain the same.

Next, by sequentially repeating the above-described through-irradiation at through-hole positions in other parts, through-holes can be formed at necessary locations. At this time, if the shape of the beam is kept constant, the same through-hole can be formed, but since the shape of the beam can be changed arbitrarily, it is difficult to make each through-hole the desired shape. It's easy.

〔Effect of the invention〕

As explained above, according to the present invention, since the ion beam O shape can be formed arbitrarily, through holes, which could only be formed reliably until now, can be easily formed into the required shape. The effect is that it can be created at any position with high precision.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the beam shape when the beam used in the etching method according to the embodiment of the present invention is scanned in the horizontal direction, and FIG. 2 is a characteristic diagram showing the beam shape used in the etching method according to the embodiment of the present invention. Figure 3 is a cross-sectional view of the irradiated area when the insulating film is irradiated with the beam having the shape shown in Figure 5 and etching is started. , Fig. 4 is a cross-sectional view of the irradiated area when etching has progressed from the state shown in Fig. 3 to the lower wiring material, Fig. 5' is a cross-sectional view of nine through-holes created by the conventional ion etching method, and Fig. Figure 6 is a cross-sectional view of a through hole created by conventional wet or plasma etching methods, and Figure 7 is a characteristic diagram showing the shape of the ion beam intensity distribution. Lower layer wiring, 2...
...Interlayer insulating film, 3... Upper layer wiring, 4...
...Through hole part, 5...-Through hole shoulder part, 6...Beam.

Claims (1)

[Claims] In a method of etching an interlayer insulating film by irradiating a hot ray or ion beam in a reactive gas atmosphere, a through hole having a desired shape is formed by arbitrarily changing the shape of the beam and manipulating the beam. 1. A method of etching an interlayer insulating film, characterized by: