JPS6115140A - Formation of pattern - Google Patents

Abstract

PURPOSE:To widen the angle of an edge of an etched thin film with high reproducibility by exposing a photoresist through a mask pattern, shifting the pattern, exposing the resist again through the pattern so as to widen the angle of an edge of the patterned resist, and using the resist as a mask during the etching of a thin film. CONSTITUTION:An SiO2 layer 2 and a conductor pattern 3 are formed, resin 4 is applied, and a photoresist 5 for removing the parts of the SiO2 layer 2 and the resin layer 4 in an information accumulating region 6 by etching is applied. The photoresist 5 is patterned through a mask pattern, the pattern is shifted, and the resist 5 is patterned again through the pattern to obtain an inclined edge 7. The layers 2, 4 are then etched through the patterned photoresist 5 as a mask to obtain an edge 8 having an angle theta corresponding to the angle theta of the edge 7. The preferred angle theta of the dual spacer edge 8 is <=65 deg. from the viewpoint of characteristics, so the extent (d) of shift of the mask pattern is preferably regulated to >=1.0mum. Thus, the angle of an edge of a thin film pattern can be widened with high reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for forming patterns for magnetic bubble memory elements and the like.

TECHNICAL BACKGROUND The following describes an example of a magnetic bubble memory element. Recently, as the density of magnetic bubble memory elements has increased, the bubble transfer pattern in the information storage section has become smaller, and one cycle of a 4 megapixel chip has become about 4 .mu.m. On the other hand, in functional units such as swap gates, replicate gates, and generators, large patterns with a period of 16 μm, for example, are used in consideration of alignment accuracy with the conductor pattern. If transfer patterns of different sizes are used in one chip in this way, a problem arises in terms of characteristics because the pull driving force differs depending on the pattern size. To improve this, a dual spacer method has been developed in which a thick spacer is used for a large pattern portion and a thin spacer is used for a small pattern portion to adjust the difference in driving force.

Prior Art and Problems FIG. 6 is a diagram for explaining the conventional dual spacer system. This method uses bubble crystal 20K 5in.
A second layer 21 is formed by sputtering, an Au conductor pattern 22 for functional gate control is created thereon, and a POLS resin 23 is applied and thermally cured in order to flatten the steps of the conductor pattern. POLS resin in area a and sio.

to expose the surface of the bubble crystal 20,
Next, a sio layer 24 is formed on the entire surface, and a soft magnetic material such as permalloy is deposited thereon, and then a bubble transfer pattern 25° 26 is formed on the permalloy layer using photolithography and ion etching. be. However, in the above manufacturing process, sio, layer 21 and POLS
The angle θ of the stepped portion 27 where the resin layer 23 is etched is 9.
If it is steep near 00, the steepness remains in the subsequent sio layer 24 as well. Therefore, when etching the permalloy layer, etching residues are left at the stepped portions. In order to prevent this etching residue, conventionally, when exposing a resist using a projection exposure apparatus, a method has been used in which the distance between the wafer and the lens is defocused to dull the edges of the resist pattern. However, in this case, there was a problem with the reproducibility of sag. FIG. 7 shows the relationship between focus and pattern dimensions, and it can be seen that the pattern width varies greatly with respect to the focus value at points other than the best focus indicated by the arrow. This is the reason why it is important to obtain reproducibility.

OBJECTS OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a pattern forming method in which the angle of pattern edges is made gentle and the reproducibility thereof is good.

According to the present invention, the structure and object of the invention are as follows: (e) In a pattern creation method in which a mask pattern is transferred to a photosensitive material on a wafer (by IJ lithography method) and then etched to create a pattern, the relative relationship between the mask and the wafer is position a few μ
This is achieved by providing a pattern creation method whose characteristic is to transfer the mask pattern to a photosensitive material by exposing twice with a shift of m, and then to etch the thin film on the wafer using the photosensitive material as a mask.

Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram for explaining the principle of the pattern creation method according to the present invention, in which a shows the position in the resist and the exposure range when normal exposure is performed, and b shows the exposure according to the present invention. This figure shows the relationship between the position in the resist and the amount of exposure when the process is performed.

In figure a, the position O in the resist is a position corresponding to the edge of the mask pattern, and the exposure f;1 is 0.5 (5
0%). The exposure amount has a distribution within the resist depending on the performance of the lens. In the case of the present invention shown in figure b, A and B
Two exposures are made, with the exposure of each exposure being a conventional bar,
Furthermore, the mask pattern was shifted by 1 μm. In this case, an exposure distribution represented by A+B occurs in the resist, which causes sag in the resist pattern.

FIG. 2 is a diagram for explaining an embodiment of the pattern creation method according to the present invention, in which a case where the Vi mask pattern is shifted equally in the X and Y directions, and b where the Vi mask pattern is shifted only in the X direction.

In the figure, A shows the first exposure, and B shows the second exposure with the mask pattern shifted, and the hatched areas are the areas where sagging occurs. Therefore a
In the figure, there are two points, and in figure b, two straight lines have areas with little sagging.

FIG. 3 is a diagram showing an example in which the present invention is applied to a stepped portion of a dual spacer method of a magnetic bubble memory, in which a is after the photoresist pattern is created, and b is a 5in2. Each figure shows the state of the POLS layer after etching.

In the figure, 1 is a bubble crystal, 2 is a SiO2 layer, and 3 is a bubble crystal.
4 indicates a conductor pattern, 4 indicates a POLS resin layer, and 5 indicates a photoresist.

In this application example, as shown in Fig. 3a, after creating SiO layer 2, conductor pattern 3, and coating POLS resin 4, information storage area 6
A photoresist 5 is applied to remove the 5IO2 layer 2 and the POLS resin layer 4 (4 μm periodic pattern portion) by etching, and is patterned using the method of the present invention to obtain an inclined edge portion 7. Using this patterned photoresist 5 as a mask, Sio! By dry etching the layer 2 and the POLS resin layer 4, a stepped portion 8 of the layer 2 and the POLS resin layer 4 is obtained at an angle θ corresponding to the angle of the edge portion of the photoresist 5, as shown in FIG. In this case, photoresist 5
The relationship between the edge taper angle θ and the shift amount d of the double exposure mask pattern is K as shown in FIG. It has been found that the angle θ of the dual spacer type portion 8 is preferably 65° or less in terms of characteristics, and from this it is understood that d is preferably 1.0 μm or more.

The present invention is also applicable to the creation of conductor patterns.

That is, as shown in FIG. 5, it is also possible to reduce the level difference that occurs in the permalloy pattern 10 by sloping the edge of the conductor pattern 11 that the permalloy pattern 10 traverses (the hatched area).

Effects of the Invention As explained in detail above, the pattern forming method of the present invention exposes the photoresist twice with a mask pattern shifted, thereby changing the angle of the pattern edge portion of the resist to 1 with an acid comb and using the resist as a mask. This has a great effect in that when etching a thin film, the angle of the edge portion of the thin film pattern can be made gentler with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the principle of the pattern creation method according to the invention, FIG. 2 is a diagram for explaining an embodiment of the pattern creation method according to the invention, and FIG. 3 is a diagram for explaining the embodiment of the pattern creation method according to the invention. A diagram for explaining a dual spacer type magnetic bubble memory as an application example, Figure 4 is a diagram showing the relationship between the amount of mask pattern shift and the taper angle of the pattern edge of the photoresist, and Figure 5 is a diagram showing the pattern of the present invention. Figure 6 is a diagram to explain an example of applying the creation method to a conductor pattern, Figure 6 is a diagram to explain a conventional dual spacer type magnetic bubble memory, and Figure 7 is a diagram showing the relationship between focus and pattern dimensions. It is. In the drawing, 1 is a bubble crystal and 2 is a sio. 4 is a POLS resin layer, 5 is a photoresist, 6 is an information storage area, and 7 and 8 are edge portions.

Claims (1)

[Claims] 1. In a pattern creation method in which a mask pattern is transferred to a photosensitive material on a wafer by photolithography and then etched to create a pattern, the mask pattern is exposed twice by shifting the relative positions of the mask and the wafer. A pattern creation method comprising transferring a mask pattern to a photosensitive material and etching a thin film on a wafer using the photosensitive material as a mask. 2. The pattern forming method according to claim 1, wherein a projection type stepper method is used for exposing the mask pattern. 3. The amount of shift in relative position between the mask and wafer is X
2. The pattern creation method according to claim 1, wherein the pattern creation method is different in the direction and in the Y direction. 4. The pattern forming method according to claim 1, wherein the thin film is etched using a dry etching method such as ion etching or plasma etching.