JPH0129055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to patterning using a lift-off method.

Lift-off technology is one of the important techniques used for patterning thin films. This is a technique that realizes a desired pattern of the deposited layer by forming a cutting die using, for example, photoresist, depositing a deposited layer through the opening, and removing unnecessary deposits together with the cutting die.

In the conventional lift-off technique, in order to separate the deposited layer on the cutting die 2 from the deposited layer on the main surface without the cutting die, as shown in FIG. A so-called eave structure was necessary. Alternatively, as shown in FIG. 2a, in the case where the deposited layer is thin enough to cause a break at the pattern edge of the cutting die, a cutting die 2 without an eaves structure may be considered. However, regardless of whether the structure of the cutting die is an eave structure or not, deposits adhere to the sides of the cutting die in both cases, as shown in Figures 1a and 2a, respectively, and as a result, the Figure 1b, Figure 2b
As shown in FIG. 1, in both cases, after the cutting die is removed and patterning is completed, unnecessary deposits 4 remain and so-called burrs are formed on the pattern edges. In order to reduce the occurrence of burrs, as shown in Figure 3a, after depositing the deposited layer, a coating layer is provided, and the unnecessary deposits are sandwiched between the cutting die and the deposited layer, and then the cutting die and the coating layer are dissolved in the solution. One possible method is to apply mechanical vibration to the cutting die and the coating layer while removing them and to remove unnecessary deposited layers. When the cutting die melted, a portion 4 of unnecessary deposits remained as shown in FIG. 3b, and so-called burrs were sometimes left on the pattern edges.

An object of the present invention is to provide a pattern forming method using a lift-off method that can reduce the occurrence of burrs.

According to the present invention, in a pattern forming step by a lift-off method, a step of providing a cutting die, a step of providing a deposited layer to be patterned by the cutting die, and a coating layer covering the deposited layer are provided. and the cutting die to sandwich the unnecessary deposited layer, and applying mechanical vibration to the cutting die, the unnecessary deposited layer, and the coating layer in an insoluble solution or a difficult solution for the coating layer. A pattern forming method using a lift-off method is obtained, which is characterized in that it includes a step of removing the cutting die and the coating layer.

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

The principle of the present invention will be explained using FIGS. 4a to 4d. A cutting die 2 is formed on the main surface of the base layer 1 in a part where the deposited layer is not required (FIG. 4a), and then a deposited layer 3 is formed (FIG. 4b), and then the deposited layer 3 is A coating layer 5 is formed to cover the cutting die 2 and the coating layer 5 (FIG. 4c), and then mechanical vibration is applied to the cutting die 2 and the coating layer 5 in a solution in which the coating layer is insoluble or hardly soluble. By removing the covering layer 5, a pattern of the deposited layer is formed (FIG. 4).

As a result of the above, a pattern of the deposited layer having edges with less occurrence of burrs can be obtained. That is, when mechanical vibration is applied to the cutting die 2 and the coating layer 4, the vibration is applied in a solution where the coating layer is insoluble or hardly soluble, so the time period for applying the vibration can be relatively freely selected within a wide range. This makes it possible to apply sufficient mechanical vibration to the unnecessary deposited layer adhering to the side surface of the cutting die and sandwiched between the cutting die 2 and the coating layer 4.

After that, when the cutting die 2 and the coating layer 4 are removed, the unnecessary deposits are also removed at the same time. Therefore, by using this method, a deposited layer pattern having edges with few burrs can be realized.

Next, in order to better understand the present invention, examples will be given and explained. A method for manufacturing a Josephson device will be described as a preferred embodiment of the present invention using FIGS. 5a to 5g.

As shown in FIG. 5a, for example, Au
-For example, a base electrode 7 with a thickness of 200 nm is formed using a superconducting material such as a lead alloy such as Pb-In. Next, as shown in FIG. 5B, a punching die is formed using a positive tape type photoresist on the portion of the base electrode 7 other than where the insulating layer is to be provided. The structure of the cutting die may be, for example, one with a so-called eave structure in which the upper layer protrudes from the lower layer obtained by immersing it in chlorobenzene for about 10 minutes after exposure and development, or one without an eave structure. . (Figure 5b
shows the case of a cutting die with an eave structure. ) Thereafter, as shown in FIG. 5c, an SiO layer 9 is deposited as an insulating film to a thickness of, for example, 300 nm. The cutting die 8 needs to have a sufficient thickness for the thickness of the SiO layer, which in this case is 1.5 μm. The SiO layer 9 is deposited on a portion of the top and side surfaces of the cutting die 8 and on surfaces other than the cutting die. Next, as shown in FIG. 5d, a coating layer 10 of a positive type photoresist is formed to a thickness of, for example, 2 μm. As a result, unnecessary SiO on the top and side surfaces of the cutting die
The layer is sandwiched on both sides with photoresist.

Thereafter, the sample is immersed in, for example, pure water, and ultrasonic vibrations are applied. Thereafter, when the photoresist cutting die 8 and the coating layer 10 are removed in acetone while applying ultrasonic vibration, the SiO layer sandwiched between them is also removed at the same time, and there is no burr as shown in Fig. 5e.
A SiO layer 9 is obtained. Thereafter, as shown in FIG. 5f, a junction barrier layer 11 serving as a tunnel barrier is formed at the junction to a thickness on the order of several tens of angstroms by, for example, RF plasma oxidation, and then, as shown in FIG. For example, the counter electrode 12 is made of a superconducting material such as a lead-based alloy such as Pb-Au.
Form to a thickness of 400 nm. By the above method, a Josephson device including a joint portion having pattern edges without burrs is completed.

Although the embodiments have been described above, the main part of the present invention is to provide a coating layer that sandwiches unnecessary deposited layers with a cutting die in order to make it possible to realize a deposit pattern with edges without burrs. The purpose of this method is to remove the cutting die, the coating layer, and unnecessary deposits after applying mechanical vibration to them in an insoluble or poorly soluble solution.

[Brief explanation of drawings]

FIGS. 1a to 1b are structural cross-sectional views for explaining the principle of one of the conventional techniques for forming a pattern using a lift-off method. FIGS. 2a to 2b are structural cross-sectional views for explaining the principle of one possible technique of pattern formation using the lift-off method. FIGS. 3a to 3b are structural cross-sectional views for explaining the principle of another possible technique for forming a pattern using the lift-off method.
4A to 4D are structural cross-sectional views in the main manufacturing steps for explaining the principle of the pattern forming method by the lift-off method of the present invention. FIGS. 5a to 5g are cross-sectional views of a Josephson device at each step of manufacturing the device according to an embodiment of the present invention. In the figure, 1 is a base layer, 2 is a cutting die, 3 is a deposited layer, 4 is an unnecessary deposited layer (so-called burr) at the pattern edge, 5 is a covering layer, 6 is an insulating substrate, 4
is a base electrode, 8 is a photoresist cutting die, 9 is a
10 is a photoresist coating layer, 11 is a junction barrier layer, and 12 is a counter electrode.

Claims (1)

[Claims] 1. In a patterning process using a lift-off method, a step of providing a cutting die, a step of providing a deposited layer to be patterned by the cutting die, and a coating layer covering the deposited layer are provided, and the coating layer and the cutting die are provided. a step of sandwiching an unnecessary deposited layer; a step of applying mechanical vibration to the cutting die, the unnecessary deposited layer and the coating layer in an insoluble or difficult-to-solution solution to the coating layer; A pattern forming method using a lift-off method, comprising a step of removing the covering layer.