JPH0779099B2 - Pattern formation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a pattern of a high-quality, high-precision superconducting element or the like.

(Problems to be Solved by Prior Art and Invention) FIG. 4 shows a conventional pattern forming method. In FIG. 4 (a), niobium (Nb) 5, aluminum (Al) or aluminum oxide is formed on a substrate 14. Layers are formed in the order of (Al ₂ O ₃ ) 4 and niobium 3, and a patterned resist 15 is further formed on niobium 3 (the layer composed of 3, 4, 5, 15 is referred to as a first layer). ). Next, dry etching is performed using the resist as a mask. However, the condition of reactive ion etching (RIE) by the CF ₄ gas that is usually used (several hundred W, several Pa)
However, since the etching rates of niobium (Nb) and aluminum (Al) are significantly different (Nb / Al >> 1), the etching of the Al film used for the tunnel layer is processed in a region where the gas effect is large and the sputtering effect is large.

In etching Nb and the like, stainless steel or the like is generally used for the substrate holder 12, but when etching the Al film 4, the stainless steel or the like in the holder is also etched.
At the same time, a part of the particles adheres to the resist stencil 15 used as a mask and the side wall of the upper Nb film 3 as 8 (see FIG. (B)). Then, as shown in FIG. 6C, SiO9 is deposited as an insulating layer (referred to as a second layer) on the substrate holder 14 having this joint, and then the resist 15 is removed as shown in FIG. A burr 8 is formed between the joints 3, 4, and the insulating layer 9. When the burr 8 is melted and removed, a void 10 is formed between the joint and the insulating layer as shown in FIG. Will be generated. Therefore, the pattern quality is significantly deteriorated when flattened. These cause a disconnection or a short circuit in the superconducting circuit, which affects the device characteristics and reduces the reliability of the device.

When stainless steel is used for the holder part, foreign matter is often mixed with stainless steel to form a residue, which makes it difficult to dissolve in acid. Also, when quartz or alumina is used for the holder part, the main component of the residue is quartz or alumina, so it is difficult to dissolve in acid.

(Means for Solving the Problems) The present invention has been proposed to remedy the above-mentioned drawbacks, and an object of the present invention is to eliminate the non-removable debris generated when manufacturing by the prior art. By improving the structure of the substrate holder and the like, forming a removable side wall adhesion layer in advance, and forming a removable side wall adhesion layer at the same time by vapor deposition or the like at the time of etching. ,
It is to provide a highly accurate pattern by chemically removing the generated residue.

To achieve the above object, the present invention provides a first step of forming a resist stencil having a desired pattern on a first layer formed on a substrate, and the first step using the resist stencil as a mask. Second dry etching layer
And a third step of depositing a second layer on the first layer on which the resist stencil is placed and in the region where the first layer has been removed, and a step of depositing a second layer on the resist stencil. In a pattern forming method comprising a fourth step of removing the second layer by lift-off, the second step is interrupted in the middle of the second step, and an acid-soluble P that does not damage the resist stencil is used.
b, Bi, In vapor deposition step, after the step is completed, the second step is performed again, and after the second step is completed, the Pb, Bi, In is removed. The gist is a characteristic pattern forming method.

Further, the present invention provides a first method for forming a resist stencil having a desired pattern on a first layer formed on a substrate.
And the second step of dry-etching the first layer using the resist stencil as a mask, and on the first layer on which the resist stencil is placed and in the region where the first layer is removed. A pattern forming method comprising: a third step of depositing a second layer; and a fourth step of removing the second layer deposited on the resist stencil by lift-off, in parallel with the second step. The step of performing Pb, Bi, In soluble in an acid that does not damage the resist stencil, and removing the Pb, Bi, In after the completion of the second step. The gist of the invention is a pattern forming method characterized by having steps.

Further, the present invention provides a first method for forming a resist stencil having a desired pattern on a first layer formed on a substrate.
And the second step of dry-etching the first layer using the resist stencil as a mask, and on the first layer on which the resist stencil is placed and in the region where the first layer is removed. In a pattern forming method comprising a third step of depositing a second layer and a fourth step of removing the second layer deposited on the resist stencil by lift-off, in the second step, As a substrate holder for holding the substrate and mounting the substrate in a dry etching apparatus, a substrate holder having Pb, Bi, In on the surface, which is soluble in an acid that does not impair the resist stencil, is used. The gist of the invention of a pattern forming method is characterized by having a step of removing the Pb, Bi and In after the second step.

The most important feature of the present invention is to introduce a layer removable between the sidewall adhesion layer and the resist stencil by an acid (for example, hydrofluoric acid, sulfuric acid, hydrochloric acid) which does not damage the resist, or the sidewall. The above-mentioned substance soluble in acid is positively mixed into the adhesion layer to make the side wall adhesion layer itself soluble in acid, thereby completely removing the side wall adhesion layer.

Next, examples of the present invention will be described.

Needless to say, the embodiment is merely an example, and various modifications and improvements can be made without departing from the spirit of the present invention.

FIG. 1 shows a first embodiment of the pattern forming method of the present invention.

FIG. 6A shows a layout of the sputter device. In the figure, 12 is a substrate holder, and a chip 11 placed on this substrate holder 12 shows the resists 1, 2 and Nb 3, 5 and the aluminum tunnel layer 4 and the substrate 14 in FIG. Is. Reference numerals 13a and 13b denote an upper electrode and a lower electrode, respectively.

(B) is Nb / Al (Al ₂ O ₃ ) / Nb after etching the tunnel layer 4 in the sputtering etching device shown in (a).
It is a junction. Here, by using a material (Pb, Cu, In, Al, etc.) that can be etched with a weakly acidic solvent for the 12 substrate holders, adhesion to the sidewalls of the resist stencils 1 and 2 generated when the tunnel layer 4 is etched. The layer (sidewall adhesion layer) 7 to be removed can be easily removed with a weakly acidic solvent. Conventionally, it is impossible to remove the "burrs" caused by the side wall adhesion layer formed by the spatter particles such as stainless steel used for the substrate holder, and these are one of the causes of disconnection or short circuit. On the other hand, this embodiment has a great improvement effect.

Using the conventional method and the method of the present invention, 100 Nb / Al (Al ₂ O ₃ ) / Nb junctions were manufactured, respectively, and their IV characteristics were examined. As a result, the conventional method leaked to 75 out of 100 junctions. While an increase in current was observed, according to the method of the present invention, the number of junctions with increased leakage current was only 10.

FIG. 2 is a diagram for explaining the second embodiment of the present invention.
The manufacturing process is shown from (a) to (f).
(A) The figure shows Nb / Al (Al of the bonding layer formed on the substrate 14
After applying a two-layer resist consisting of polymethylmethacrylate (PMMA) 2 and AZ resist 1 on the ₂ O ₃ ) / Nb film (3/4/5) (this is called the first layer), AZ resist 1 is applied. After patterning, PMMA ₂ is dry-developed in an O ₂ gas atmosphere. Further, O ₂ plasma treatment is applied to form a resist overhang structure, and then CF ₄ gas is used to subject the upper Nb film 3 to reactive ion etching (RIE) (b).
Figure). Subsequently, a film 6 (Pb or In vapor deposition film) capable of being etched with a weak acid solvent such as Pb or In is vapor-deposited under a condition that a lot of wraparound is performed so that the surface is well covered, and the figure (c) is obtained. Then, the tunnel layer (Al, Al ₂ O ₃ ) 4 is removed by sputter etching with Ar having a low gas pressure (Fig. D), (d).
In the figure, reference numeral 7 is an adhesion film formed by sputtering, and etching is performed on the lower Nb film 5 under the etching conditions for the upper Nb film 3 (e
(Fig.) Sidewall adhesion layer 6,7 if etching is performed with a weakly acidic solvent.
Are removed.

Here, if the resist is dissolved in a solvent such as acetone or MIBK, the junction (f) can be obtained. Before melting the resist, join (upper Nb3 + Al, Al ₂ O ₃ tunnel layer 4 + lower Nb5)
Insulator 9 such as SiO2 of the thickness of the part (this is called the second layer)
Is deposited and the lift-off process is performed, the flattening of the joint portion can be obtained (FIG. 7G).

Similar to the previous method, this method produces 100 Nb / Al, Al ₂ O ₃ / Nb joints.
As a result of individually manufacturing and examining the increase in leak current,
The increase in the leak current was only observed in 6 out of 6 pieces.

FIG. 3 is a diagram for explaining the third embodiment of the present invention.
The feature is that the tunnel layer 4 is processed while performing vapor deposition simultaneously with etching. That is, up to the processing of the upper Nb film (a → b) is the same as that of the second embodiment of FIG. 2, but when the next tunnel layer 4 is processed, it is removed at the same time with a weak acidic solvent such as Pb, In. The side wall adhesion layers 6 and 7 formed on the side walls of the upper Nb film 3 and the resist stencils 1 and 2 can be easily removed by depositing a material that can be deposited.

After forming the structure of FIG. 3B, the tunnel layer 4 is processed under the condition of etching amount> vapor deposition amount (FIG. 3C). At this time,
The gas pressure is several Pa to several nPa, and the gas is Ar. Then, the lower Nb film 5 is etched (d) in the same manner as in the second embodiment of FIG.
Figure), after cleaning with a weakly acidic solvent, remove resist films 1 and 2 (e
(Figure), vapor deposition of SiO9, and lift-off processing, and planarization can be achieved (Figure f).

As a result of producing 100 Nb / Al, Al ₂ O ₃ / Nb junctions by this method and examining the increase in leak current, an increase in leak current was observed in 3 of the 75 in the conventional method.

As is clear from these results, the present invention reduces leakage current due to residue removal, short circuit, and
Since the number of wire breaks was reduced, the accuracy and yield were greatly improved.

(Effects of the Invention) As described above, by using the manufacturing method of the present invention for a superconducting element having an Nb / Al (Al ₂ O ₃ ) / Nb junction, etc. Since burrs that occur in the parts can be completely removed, the pattern can be made highly accurate and high quality, and the yield can be improved.

Although the case where the present invention is applied to the method for manufacturing a superconducting element has been described above, the same problems and effects as above also occur in the pattern forming method for performing etching and lift-off using a resist stencil. It is obvious that the present invention can be applied.

[Brief description of drawings]

FIG. 1 shows a first embodiment of a pattern forming method of the present invention, FIG. 2 shows a second embodiment, FIG. 3 shows a third embodiment, and FIG. 4 shows a conventional pattern forming method. . 1 …… AZ resist 2 …… PMMA resist 3 …… Upper Nb film 4 …… Al, Al ₂ O ₃ tunnel layer 5 …… Lower Nb film 6 …… Evaporation film of Pb, In, etc. 7 …… Adhesive film by spatter 8: “Burning” caused by the side wall adhesion layer 9: Insulation film such as SiO 10: Voids during flattening 11: Wafer during spattering 12: Substrate holder during spattering 13: During sputtering Counter electrode 14 ... Substrate

Claims (3)

[Claims] 1. A first step of forming a resist stencil having a desired pattern on a first layer formed on a substrate, and the first step using the resist stencil as a mask.
A second step of dry-etching the first layer, and a third step of depositing a second layer on the first layer on which the resist stencil is placed and in a region where the first layer is removed. In a pattern forming method comprising a fourth step of removing the second layer deposited on the resist stencil by lift-off, the second step is interrupted in the middle of the second step, and the resist stencil is removed. Soluble acid-soluble P
b, Bi, In vapor deposition step, after the step is completed, the second step is performed again, and after the second step is completed, the Pb, Bi, In is removed. Characteristic pattern formation method. 2. A first step of forming a resist stencil having a desired pattern on a first layer formed on a substrate, and the first step using the resist stencil as a mask.
A second step of dry-etching the first layer, and a third step of depositing a second layer on the first layer on which the resist stencil is placed and in a region where the first layer is removed. A pattern forming method comprising a fourth step of removing the second layer deposited on the resist stencil by lift-off, the step being performed in parallel with the second step, which does not damage the resist stencil. A method of forming a pattern, comprising a step of vapor-depositing Pb, Bi, In soluble in an acid, and a step of removing the Pb, Bi, In after the completion of the second step. 3. A first step of forming a resist stencil having a desired pattern on a first layer formed on a substrate, and the first step using the resist stencil as a mask.
A second step of dry-etching the first layer, and a third step of depositing a second layer on the first layer on which the resist stencil is placed and in a region where the first layer is removed. In a pattern forming method comprising a fourth step of removing the second layer deposited on a resist stencil by lift-off, in the second step, the substrate is held and the substrate is placed in a dry etching apparatus. As a substrate holder for mounting, a substrate holder having Pb, Bi, In soluble in an acid that does not impair the resist stencil on the surface is used, and after the second step, the Pb, Bi, In A pattern forming method, which comprises a step of removing