JP2705295B2 - Method of forming fine pattern by etching - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to semiconductor-related components, particularly lead frames and TAs.
The present invention relates to a method for forming a fine pattern on a B tape by etching.

<Conventional technology> Conventionally, in the etching process of TAB tape, for example,
As shown in the drawing, when, for example, Cu is bonded as a metal layer 2 to be etched on a supporting base material 1, when an etching solution (for example, an FeCl ₃ solution) is sprayed on, it is covered with a photoresist mask 3. The exposed portion of the metal layer 2 which does not melt is dissolved, and a groove-shaped etching portion 4 (etching groove) is formed.

However, the formation state of the groove-shaped concave portion is such that a groove is quickly formed in the depth direction of the metal layer 2 at the beginning of etching, and when the groove becomes deeper, the etching solution stays in the groove and the inflow and outflow of the solution become insufficient. The rate of progress of the corrosion in the depth direction gradually decreases, and the corrosion dissolution mainly proceeds in the lateral direction, that is, along the lower portion of the photoresist mask 3 (side etching).

As a result, if the etching factor is reduced and the thickness of the metal layer 2 to be etched is kept constant, it becomes difficult to perform fine and deep etching.

Here, conventionally, as a method of increasing the etching factor, for the purpose of always replacing the corrosion-deteriorated etching solution stagnated in the groove with a fresh etching solution,
A high-pressure droplet is sprayed onto the metal layer 2 to be etched at a high spray pressure. A high-pressure gas is repeatedly sprayed on the metal layer 2 repeatedly for a short time during the spray etching. The processed surface of the metal layer 2 to be etched is brushed. Etching while rubbing has been proposed, and some effects have been confirmed.

<Problem to be Solved by the Invention> However, what is always a problem in the above is the occurrence of the chipped portion 5 of the mask, and the dissolving portion 6 is generated below the portion,
It becomes difficult to obtain a normal pattern (see FIG. 4).

The above conventional methods (1) to (4) cannot always be effective methods, and their solutions have been straddled.

An object of the present invention is to provide a method for forming a fine pattern by etching having a high etching factor, in which a photoresist mask is prevented from being chipped even by an external force applied to an etching solution to promote flow.

<Means for Solving the Problems> The inventors of the present invention prevent mask freezing damage by suppressing excessive free vibration of a photoresist mask caused by ultrasonic vibration given as an external force, and promote flow of an etchant. Can be measured, which has led to the present invention.

The effect of ultrasonic vibration was confirmed as an acceleration of the sand erosion velocity, which is one of the physicochemical dissolution phenomena of metals, as seen in the reference [Masamura Matsumura et al .: Corrosion Protection Technology, 29, 13 (1980)]. Therefore, it is expected that it can be used for the etching phenomenon.

That is, according to the present invention, in order to achieve the above object, a member to be etched is covered with a photoresist mask, a part to be removed is exposed, and an etching solution is supplied to dissolve and remove to form a pattern. In the method, a perforated material and / or a shield is provided on a surface of the member to be etched having the photoresist mask, and ultrasonic vibration is applied from above or below the member to be etched via an etching solution. A method for forming a fine pattern by a characteristic etching is provided.

 Hereinafter, the present invention will be described in more detail.

FIG. 1 is a cross-sectional view for explaining an etching process showing one embodiment of the present invention. Here, a case of a TAB tape is shown as an example of the member to be etched.
A metal layer to be etched 2 is laminated on a support substrate 1, and a photoresist mask 3 is further laminated thereon. In the present invention, a perforated substance 8 is provided on the surface of the member to be etched 7 in close contact with the upper surface of the photoresist mask 3.

Examples of the porous material 8 include a porous material such as a commercially available sponge, and a soft material having an opening according to a masking shape.

The layer thickness of the porous material 8 is not limited, but in the case of the sponge, for example, a material having a thickness of 15 mm may be compressed to 3 mm and used in close contact.

By bringing the perforated substance 8 into close contact with the surface of the member 7 to be etched, and attaching an appropriate holder 9 to the outside thereof,
The photoresist mask 3 is pressed strongly against the metal layer 2 to be etched to prevent free vibration and deformation due to external force of the photoresist mask 3.

The workpiece 7 to be etched having the perforated substance 8 attached thereto is processed with the etching solution 10
Into the container 11 with the ultrasonic generator 12
And ultrasonic vibration 13 is given. As a result, when the processing side is thrown upward, the ultrasonic vibration 13 moves through the hole of the perforated material 8 and reaches the deep part of the etching groove 4, and vigorously agitates the etching solution in the groove, and mainly Corrosion and dissolution of the metal layer in the deep part of the groove is assisted, and the dissolution shape is such that the opening is narrow and the etched portion 4 of the fine pattern that has advanced in the depth direction.
Can be obtained. At this time, since the photoresist mask 3 is strongly pressed by the perforated substance 8, it hardly vibrates freely, does not easily peel off due to fatigue destruction, and obtains a desired etching pattern.

Instead of the perforated substance 8, a shield 14 having an opening corresponding to the masking shape (having a planar shape processed substantially in the same manner as the mask) 14 may be provided on the photoresist mask 3. Alternatively, the shielding body 14 may be placed over the photoresist mask 3 in the porous material 8 as shown in FIG. This is expected to have an effect of preventing the photoresist mask 3 from peeling below the shield 14 and an effect of promoting attenuation of ultrasonic vibration in the depth direction.
Here, examples of the material of the shield 14 include a noble metal that is not easily eroded by an etchant, for example, a Ti-2Pd alloy, ceramics, and rubber. In addition,
If the ultrasonic generator 12 is placed in close contact with the perforated substance 8 and the etching liquid 10 is sprinkled from above, the etching liquid is held in the perforated substance 8 and below it,
Without using the container 11, the ultrasonic vibration 13 is transmitted downward, and the same purpose can be achieved.

FIG. 2 shows an example in which the transmission path of the ultrasonic vibration 13 is a liquid flow, and a handy type etching machine is used. That is, the etching solution 10 is filled from the etching solution introduction pipe 16 into the vertical tube 15 in which the etching solution flows, and the ultrasonic generator 12 is mounted on the upper portion of the vertical tube 15.

The etching liquid 10 and the ultrasonic vibration 13 can be applied to a predetermined portion by placing the cylindrical tip 15a (which may be flexible) downward above the porous material 8 of the member 7 to be etched.

By using this machine in combination with the conventional spray type etching machine (generally used to uniformly process the entire surface of a workpiece), a specific part (fine part) of the etching pattern can be effectively used. It is also possible to process it. Further, the apparatus can be strongly adhered to the perforated material 8 and a high etching factor can be obtained by spraying the etching solution 10 at a high pressure.

Next, a case where the workpiece 7 to be etched is put into the container 10 with the processing side facing downward will be described with reference to FIG.

In this method, the ultrasonic vibration 13 is applied from the back surface of the workpiece 7.

That is, in a configuration in which the ultrasonic vibration 13 is applied from above to the supporting base material 1 and the metal layer 2 to be etched located below the base material 1, the ultrasonic vibration 13 is apt to be attenuated in the depth direction, and the lower the vibration energy, Decrease.

As a result, the dissolution of the metal layer 2 to be etched is remarkably large in the upper part and small in the photoresist mask 3 side.
In addition, since the peeling of the photoresist mask 3 is less likely to occur as compared with the method of FIG. 1, the attachment of the peeling preventing member of the photoresist mask 3 such as a porous material becomes small, or as shown in FIG. There is also an effect that it can be omitted.

The etching solution 10 shown in FIG. 3 is not limited to the case where the etching solution is filled in the container 11, and spraying from below the workpiece 7 by spraying does not cause any problem in etching. If the state of stagnation in the groove 4 is adjusted, a higher etching factor may be obtained. Also, the workpiece 7 and the ultrasonic generator
12 and spray nozzle arrangement
The spray method can be used upside down.

<Example> Hereinafter, the present invention will be specifically described based on examples.

(Example 1) A PMER (manufactured by Tokyo Ohka Co., Ltd.) type photoresist mask (thickness: 5 μm), a pure copper metal layer to be etched (thickness:
35μm), adhesive (25μm thickness), polyimide mounting substrate (75μm thickness), semiconductor mounting structure parts, TA
Using a B tape (appearance size: 35 mm width × 135 μm thickness × 100 m length), etching was performed in a 42 ° Baume FeCl ₃ solution at 40 ° C.

As a perforated substance mounted on the photoresist mask, a commercially available sponge having a thickness of 15 mm was pressed from the outside to a thickness of 3 mm with a wire mesh holder, and was brought into close contact with the photoresist mask.

Next, the ultrasonic generator horn (20 kHz, amplitude 24 μm, horn size: 16 mm) almost adhered to the outer surface of the sponge
Φ × 15mm height), and let the etching solution flow down from the outside with a hose so that the entire surface to be processed is immersed.
Etched for 120 seconds.

As a result, the photoresist mask was not peeled off at all, and etching was preferentially performed below the mask mark, and the etching factor was 2.5 at a portion where the stripe mask width was 50 μm.

On the other hand, when I went without attaching the above sponge,
Part of the mask was peeled off, and the desired pattern was not etched.

In the conventional spray-type etching method, the etching factor of the above portion was 2.0 at the maximum.

In addition, after etching by a conventional spray method 1/2 to 2/3 hours before the predetermined time, when the method of the present invention was applied, the etching factor was improved to 3.0, and the method according to the present invention was more effective at the deep part of the etching groove. It was confirmed to work effectively.

In addition, a flow path cylinder (inner diameter: 20 mmΦ) of an etching solution according to the shape shown in FIG. 2 was prepared, pressed strongly against a member to be etched, and the etching solution was flowed at 1.8 kg / cm ^2. Improved to 3.4.

In place of the sponge-like substance, the sponge-like substance is also used when a thin plate made of Ti-2Pd (2 mmt in thickness) machined according to a masking shape is provided by pressing the surface of the member to be etched through a thin rubber plate. Almost the same tendency as in the case of providing was obtained.

Next, using the above-described materials and equipment, etching was performed by the method shown in FIG. Also in this case, the improvement of the etching factor was surely observed by applying the ultrasonic wave.

In particular, in the same manner as described above, the etching factor of the present invention was performed on the sample after the grooves were formed by the conventional spray method in advance, and the etching factor was observed to be about 3.2 at the maximum.

In this case, the ultrasonic frequency is 100 kHz rather than 20 kHz.
Since z is superior, it is clear that the specifications can be selected according to the shape of the member to be etched and the state of ultrasonic transmission.

Next, by using the method of the present invention, the semiconductor-related parts can be finely etched, and the size of the prototype is 65% of the conventional product, and the size of the electronic machine using the semiconductor structure is the conventional product. 85% of the total, and has a significant significance as an electronic machine.

<Effects of the Invention> Since the present invention is configured as described above,
By using the present invention, it is possible to obtain a semiconductor-related component that has not been conventionally obtained and that has been subjected to fine etching processing, so that a semiconductor structure and a product using the same can be reduced in size and weight. As a result, it is possible to strongly contribute to cost reduction from materials to products, increase in functions, and increase in commercial value.

In addition, it is possible to use a material that has been difficult to use conventionally or to use a combination thereof.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining an etching process showing one embodiment of the present invention. FIG. 2 is a perspective view of a handy type etching machine for carrying out the present invention. FIG. 3 is a cross-sectional view for explaining etching showing another embodiment of the present invention. FIG. 4 is a cross-sectional view of a conventional etched part. DESCRIPTION OF SYMBOLS 1 ... support base material 2 ... metal layer to be etched 3 ... photoresist mask 4 ... etched part (etching groove) 5 ... mask chipped part 6 ... dissolved part 7 …… Etched workpiece, 8… Porous material, 9… Holder, 10… Etching liquid, 11… Vessel, 12… Ultrasonic generator, 13… Ultrasonic vibration, 14… Shield Body, 15… Vertical tube, 15a… Tube end, 16 …… Introduction tube

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Makoto Goto 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Metals, Ltd. Metal Research Laboratory (56) References JP-A-58-133379 (JP, A)

Claims (1)

(57) [Claims] 1. A method for forming a pattern by covering a member to be etched with a photoresist mask, exposing a portion to be removed to be removed, supplying an etchant, and dissolving and removing the pattern. A fine pattern is formed by etching characterized by providing a perforated substance and / or a shield on the surface of an etching member and applying ultrasonic vibration from above or below the member to be etched via an etching solution. Method.