JPH039613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pattern having a minute gap, which can reliably form a minute gap in a thin film layer formed on a wafer.

Conventionally, as a method for manufacturing gaps as described above, it has been considered to obtain gaps by forming a resist pattern using photolithography, but in this case, it was difficult to obtain gaps with minute widths of several thousand angstroms. .

The present invention is intended to solve the above-mentioned problems,
It is an object of the present invention to provide a method for manufacturing a pattern having a minute gap, which can obtain a gap with a minute width.

Embodiments of the invention will now be described with reference to the drawings.

It is conventionally known that when a resist pattern is formed on a thin film layer provided on the surface of a substrate and ion etching is performed on the resist pattern, an object to be etched is sputtered on the side surface of the resist pattern.

Next, the in-beam etching technique will be explained. In most practical ion beam etching applications, appropriate masking techniques are required.
In this application, photoresist masking methods have been developed for two types of etching. This technology has already been published in the Journal of Vacuum
Science & Technology Vol.12, No.1, 1975
(January/February combined issue), so I will explain its outline. (a) High resolution, shallow depth etching (typical dimensions ~1μ).

(b) Low resolution, extremely deep etching (typical dimensions ~50μ). The various methods used are discussed, and the effects of redeposition of sputtered material with argon ions (Ar ⁺ ) and the photoresist profile of the final etched wall feature are considered.

Single crystal materials exhibit anisotropy in their ion etching rate, meaning that the ion etching rate is a function of the crystal orientation as well as the beam projection angle.

The main advantages of ion beam etching technology are:
It lends itself well to planar technology, large areas can be easily etched uniformly, and the equipment required is relatively simple. Ion beam etching rates for various materials used in ion beam etching are as follows.

Material Etching rate Å/min SiO ₂ crystal {001} 330 GaAs {100} 650 Si {100} 215 SiO ₂ (deposited film) 280 Since these etching methods are essentially non-selective, relief etching )
Great care must be taken when selecting mask materials for.

Ion beam etching rate is also shown as a function of power density at normal incidence. For deep pattern etching, Riston
Photoresist has been found to be useful. It was developed for chemical etching and plating of circuit boards and is well suited for the purpose due to its thickness (>37μ) and relatively slow ion beam corrosion rate. Samples that are heated during etching along with other photoresists are problematic; therefore, if the power density exceeds 0.5 W/cm ² , the heat must be removed between the sample and the water-cooled sample holder with a thin layer of gallium or vacuum grease. Contact needs to be improved.

An example of an etched structure is shown in FIG. After removing the photoresist, a thin wall of substrate material leaves an outline in the area where the photoresist was placed, since large amounts of material are continually redeposited from the sidewalls and etched again.

A model of the time course of the cross-sectional profile is shown in FIGS. 8a, b, c. Experiments with materials actually used have confirmed that walls are generated at the contours of surfaces masked by a photoresist in which the bulk material is etched for several hours at normal incidence. Figures 8a, b, and c show diagrams that model this.

The time course of the trenches masked by photoresist takes into account redeposition of material. In the figure, a shows a cross section of the photoresist before etching. As the etching progresses in FIGS. 8b and 8c, small areas are formed in the photoresist, sidewall coverage occurs, and the sidewall thickness becomes progressively thicker.

When the etching is complete and the remaining photoresist is removed, the sidewalls may tear off (see Figure 8b), depending on how thin and brittle the sidewalls are, or It will remain intact (see Figure 8c).

From this modeled drawing, Figure 8 a, b, and c,
It is understood that the sidewall thickness becomes progressively thicker as the ion beam etching progresses. this is,
This is due to redeposition of material as described above. This sputtered object to be etched becomes a film-like wall, and this wall can be made several thousand Å wide and several μm high by adjusting the thickness of the resist pattern, ion etching time, etc. It is possible.

The present invention aims to solve the above-mentioned problems by paying attention to this point, and specific embodiments thereof will be described below in order.

First, as shown in FIG. 1 and FIG. 2, which is a sectional view thereof, a resist pattern 3 is formed in a checkered pattern on the SiO ₂ thin film layer 2 on the surface of the wafer 1. As shown in FIG. Next, applying the ion beam technique described above, ion etching is performed from above in the direction of the arrow in FIG. Figure 3 shows the completed state of etching.
In this state, on the sides of the resist pattern 3,
A wall 4 is formed. This is thought to be due to the effects of etching and redeposition of the substrate material (which affects the formation of sidewalls), which are the characteristics of the ion beam etching described above.
A SiO ₂ wall 4 is formed. Next, when the resist pattern is removed using oxygen plasma or the like, the state shown in FIG. 4 is obtained. Next, as shown in FIG. 5, a permalloy thin film layer 5 is formed on this surface by vapor deposition or the like. Next, as shown in FIG. 6, the exposed portion of the wall 4 from the thin film layer 5 is removed by ultrasonic cleaning or the like, a resist pattern is formed on the entire surface (not shown), and then etched by known ion beam etching or the like. By removing unnecessary portions, a permalloy pattern 6 as shown in FIG. 7 can be obtained. In this case, since an insulating gap is formed by the wall 4 in the adjacent portion of each permalloy pattern, the mask used in forming the resist pattern may be a continuous mask with no gap.

By the way, in a bubble memory, by using bubbles with a minute diameter, the bit density increases, which is advantageous in terms of cost, etc. However, when minute bubbles are used, the minimum pattern width and gap become small, making it impossible to form a pattern using conventional photolithography. However, this problem is resolved by employing the process described above. That is, as mentioned above, the height of the wall 4 can be made several thousand angstroms by adjusting the resist pattern thickness, ion etching time, etc., which makes it possible to manufacture chips using microbubbles. It becomes possible.

As described above, according to the present invention, it is possible to form a gap of 1 μm or less.
It is possible to produce bubble chips of less than m.

[Brief explanation of the drawing]

The figures show an example of the manufacturing method of a pattern having a minute gap according to the present invention in the order of steps. 3 is a front view showing a state in which a wall is formed on the side surface of the resist by ion etching, FIG. 4 is a front view showing a state in which the resist has been removed, and FIG. 5 is a front view showing a state in which permalloy has been deposited. FIG. 6 is a front view showing a state in which the exposed portion of the permalloy of the wall has been removed, and FIG. 7 is a plan view showing the state in which the permalloy has been patterned. Figure 8 a, b, c
1 is an explanatory drawing of known ion beam etching. In the figure, 1 is a wafer, 2 and 5 are thin film layers, 3 is a resist pattern, 4 is a wall, and 6 is a permalloy pattern.

Claims (1)

[Claims] 1 Form a pattern on a first insulating thin film layer created on a wafer, ion-etch the surface to form a sputtered layer of the material of the first thin film layer on the side surface of the pattern, and then A method for manufacturing a pattern having a small gap, the method comprising: removing the pattern and forming a second thin film layer thereon.