KR100463248B1 - Flexible electrode equipment for cochlear implant - Google Patents

Abstract

The present invention relates to a flexible electrode structure, the electrode structure comprises an electrode pattern formed with a lower insulating layer and an upper insulating layer on a substrate by a semiconductor manufacturing process; And an elastomer bonded to a lower portion of the substrate to support the electrode pattern, wherein the substrate is composed of a plurality of divided partition walls arranged side by side at a predetermined interval to make the electrode structure flexible. Since the electrode structure according to the present invention is excellent in flexibility and has a sufficient volume, it can be usefully used as an electrode for cochlear implants, and can be easily manufactured using a semiconductor process.

Description

Flexible electrode equipment for cochlear implant

The present invention relates to a flexible electrode structure, the electrode structure is formed with a lower insulating layer and an upper insulating layer on a substrate by a semiconductor manufacturing process; And an elastomer bonded to a lower portion of the substrate to support the electrode pattern, wherein the substrate is composed of a plurality of divided partition walls arranged side by side at a predetermined interval to make the electrode structure flexible. Since the electrode structure according to the present invention is excellent in flexibility and has a sufficient volume, it can be usefully used as an electrode for cochlear implants, and can be easily manufactured using a semiconductor manufacturing process.

A cochlear implant is a device that provides hearing by electrical stimulation of the auditory nerve to patients with highly sensorineural hearing loss or hearing impairment due to damage to the inner ear. The structure of the cochlear implant can be divided into the extracorporeal part and the internal part. The external part installed outside the body is composed of a microphone (transmitter), a sound processor (language synthesizer) and a transmitting antenna (transmitter), and the internal part implanted in the body is composed of a receiving / stimulating device (receiver) and an electrode.

Since the first single channel cochlear implant was first commercialized in 1972 and performed on hearing-impaired people, tens of thousands of hearing-impaired people have been transplanted to date. The main part of implantation of cochlear implant is to insert the electrode inside the cochlear implant into the cochlear implant and fix the body. Thus, the requirements for cochlear implant electrodes include sufficient volume for flexibility, in vivo safety, insertion and stable position retention. Currently, all cochlear implant systems use metal wire electrodes as cochlear implant electrodes, and cochlear implant electrodes using semiconductor microelectrodes are currently being researched and developed.

The metal wire electrode is an electrode in which a metal wire made of a Pt / Ir alloy is placed in a mold and molded by injecting a silicone elastomer. Since the metal wire electrode is flexible in itself and has a volume of about 1 mm in cross section diameter, all cochlear implant systems currently commercially use this metal wire electrode. However, when the metal wire is placed in the mold by hand, the work time is long and the defect rate is relatively high.

The semiconductor microelectrode is manufactured using a semiconductor process technology, and is made of silicon. Since silicon is flexible and easily bent when its thickness is thinner than 10 μm, this point is used to manufacture a semiconductor microelectrode made of a very thin silicon structure. The semiconductor process technology enables easy fabrication, high yield, and high accuracy of the electrode itself compared to the general metal wire electrode used in the conventional cochlear implant system. In addition, integrating active circuits into silicon, a substrate material, enables the fabrication of integrated devices with electrodes and systems. Element.

Kensall D. Wise, of the University of Michigan, USA, fabricated probe-type semiconductor microelectrodes for use in auditory prosthetic devices and applied them to laboratory animals to study the applicability of semiconductor electrodes. Tracy E. Bell, Kensall D. Wise, David J. Anderson, A flexible micromachined electrode array for a cochlear prosthesis, Sensors and Actuators A 66, pp. 63-69, 19981.

However, because the material called silicon is likely to be destroyed, although very thin and long silicon structures are flexible as described above, the possibility of destruction cannot be completely ruled out. In particular, since the semiconductor microelectrode has a very thin structure, there is a high possibility that it will be broken while catching it and inserting it into the cochlea. When the silicon structure is destroyed, not only there is a possibility of damage to tissues in vivo due to the fragments, but also the metal wiring on the silicon substrate is broken together, so that operation as an electrode cannot be expected.

In addition, apart from the flexibility issue, it is very difficult to insert silicon into the cochlea in the form of very thin and long structures of about 10 μm in thickness. Silicone is a hard material with a very high hardness. Therefore, there is a very high possibility of tissue damage when inserting a sharp structure of about 10 mu m in thickness and 2 to 2.5 cm in length into the cochlea. If the silicon is destroyed during insertion, it may also cause damage to biological tissue by the silicon fragments.

In addition, since the semiconductor microelectrode does not have sufficient volume, there is a possibility that its position is changed after insertion. A cochlear tube is an empty, end-closed tube with about 2.5 laps of wound, and the diameter of the cross section of the space in which the electrode is placed is about 2 mm or more. The closer the cochlear electrode is to the cochlear wall, the greater the stimulation effect. However, as described above, it is difficult for the electrode having a thickness of 10 μm, which is difficult to be inserted, to stably adhere to the inner wall of the space having a diameter of 2 mm. When the position of the cochlear implant electrode is changed, the threshold level or the like is changed, thereby lowering the stable operation of the prosthetic device. Thus, sufficient volume is recognized as one of the important requirements for cochlear implant electrodes.

Accordingly, the present inventors have conducted intensive research to manufacture electrodes having flexibility, in vivo safety, and sufficient volume while being manufactured using semiconductor process technology. As a result, not only the electrode structure according to the present invention can be easily manufactured by semiconductor processing technology, but also has flexibility, it is easy to insert into the cochlear implant, is safe in vivo, and has a sufficient volume so that the position in the cochlear implant can be improved. It was confirmed that the stability and completed the present invention.

Accordingly, it is an object of the present invention to provide an electrode structure which is flexible and has a sufficient volume.

1 is a cross-sectional view of an electrode structure according to the present invention,

2 is an overall outline of the cochlear implant prosthetic electrode structure according to the present invention,

3A to 3L are cross-sectional views illustrating a method of manufacturing an electrode structure according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: substrate

21: sacrificial layer for etching stop

22: sacrificial layer for the mask

30: insulating layer (upper insulating layer or lower insulating layer)

31: upper insulating layer

32: lower insulating layer

40: electrode pattern

41: bonding pad

50: bonding reinforcement layer

51: mask layer for etching the upper insulating layer

60: elastomer

70 mask layer for substrate etching

The present invention relates to a flexible electrode structure.

The electrode structure according to the present invention

An electrode pattern formed together with a lower insulating layer and an upper insulating layer on a substrate by a semiconductor manufacturing process; And

Elastomer bonded to the lower substrate to support the electrode pattern

It includes, the substrate is an electrode structure characterized in that it is made of a plurality of partition partitions arranged side by side at a predetermined interval is flexible.

In the present invention, a polyimide or a liquid crystal polymer film may be used as the insulating material used as the upper insulating layer or the lower insulating layer. In particular, since polyimide is a tough, flexible, transparent, biocompatible material and has the advantage of being capable of semiconductor processing, polyimide is preferably used. The polyimide may be laminated by hardening by heating through an oven or a hot plate after spin coating. Polyimide has the disadvantage that it is not firmly bonded to the elastomer, but in the present invention, the elastomer is bonded to the substrate, so it is not a problem in the present invention.

In the present invention, any substrate can be used as long as a hard material capable of forming a partition. For example, silicon, quartz, or Pyrex glass, which is glass having heat resistance and durability, may be used. Can be used, preferably silicone is used.

When silicon is used as the substrate, there is an advantage that an active circuit can be integrated on the substrate. That is, by integrating a desired active circuit in advance in the coupling pad 1 or the partition which is to be connected to the outside of the substrate, an electrode in which the system is integrated can be manufactured. In this case, if the electrode manufacturing process described later is performed at a low temperature, no problem occurs in the operation of the active circuit.

Gold, platinum, titanium nitride (TiN) and the like may be used as the electrode material in the present invention.

Since the electrode structure according to the present invention consists of a plurality of divided partition walls arranged side by side at a predetermined interval, the entire structure can be flexed flexibly.

The electrode structure according to the present invention can be easily manufactured by semiconductor processing technology. Specifically, the electrode structure according to the present invention

(a) forming a lower insulating layer, a metal electrode pattern, and an upper insulating layer on a substrate according to a semiconductor manufacturing process;

(b) forming a partition partition by selectively patterning and etching a rear surface of the substrate; And

(c) injecting the elastomer into the elastomer through molding on the back side of the substrate;

It can be prepared to include.

In the manufacturing method, step (a) is specifically

Depositing a sacrificial layer on both sides of the substrate;

Stacking a substrate etching mask layer on a sacrificial layer on a back side of the substrate;

Stacking a lower insulating layer on the sacrificial layer on the front surface of the substrate;

Stacking a metal material on the lower insulating layer, and then selectively patterning the electrode material to form an electrode pattern;

Stacking an upper insulating layer on a front surface of the substrate including the electrode pattern;

Stacking an upper insulating layer etching mask layer on the upper insulating layer;

After patterning the mask layer for etching the upper insulating layer, etching the upper insulating layer to open the electrode pattern;

Etching the sacrificial layer on the upper insulating layer, the lower insulating layer and the front surface of the substrate in the form of an electrode structure; And

Removing the upper insulating layer etching mask layer

It includes.

In addition, step (b) is specifically

Selectively patterning a sacrificial layer and a substrate etching mask layer on a rear surface of the substrate to form a mask;

Forming a partition partition by etching the back side of the substrate using the formed mask; And

Removing the sacrificial layer on the back surface of the substrate and the mask layer for etching the substrate, and etching the sacrificial layer on the front surface of the substrate to coincide with the division partition wall.

It includes.

In the present invention, the manufacturing process is the same even when manufacturing an electrode structure in which an active circuit is integrated on a silicon substrate. However, at the start of the process, a silicon substrate with integrated active circuits can be used.

As the sacrificial layer laminated on both surfaces of the substrate during the manufacturing process of the present invention, a silicon oxide film or a silicon nitride film may be used. Preferably, a silicon nitride film is used. The sacrificial layer laminated on the front surface of the substrate is an etch stop sacrificial layer for preventing the lower insulator from being etched when the substrate is etched during the process, and the sacrificial layer laminated on the back side of the substrate includes a substrate etching mask layer which is subsequently stacked; Together it is used as a mask for substrate etching. As the mask layer for etching the substrate, a silicon oxide film is preferably used.

Meanwhile, after the etching process of the substrate, a sacrificial layer for etching stop may remain on the substrate. Thus, the electrode structure according to the present invention may further include the sacrificial layer for etch stop on the substrate.

In addition, when the metal material is laminated in the above process, an adhesion enhancement layer is laminated before and after the metal material is laminated so that the upper insulating layer or the lower insulating layer and the metal material (electrode material) are strongly attached to each other. Ti may be preferably used as the adhesion reinforcing layer. Meanwhile, even after the upper insulating layer is etched to open the electrode pattern of the metal material, the adhesion reinforcing layer between the metal material and the lower insulating layer remains. Therefore, the electrode structure according to the present invention may further include the adhesion enhancement layer on the substrate.

Hereinafter, an electrode structure and a method of manufacturing the same according to the present invention will be described with reference to the drawings.

As can be seen in Figure 1, the electrode structure according to the present invention is a substrate 10, an etch stop sacrificial layer 21 on the substrate, the lower insulating layer 32 on the etch stop sacrificial layer, on the lower insulating layer And an upper insulating layer 31 for insulating the electrode pattern 40 formed between the electrode pattern 40 and the electrode pattern. Here, the substrate is composed of a plurality of divided partitions arranged side by side at a predetermined interval. An elastomer is bonded to the lower portion of the substrate.

2 is an overall outline of the cochlear implant prosthetic electrode structure according to the present invention. Here, the electrode site where the electrode pattern 40 is exposed is inserted into a cochlear cochlea to stimulate auditory cells.

1 and 2, the metal electrode on the side of the metal electrode that is not inserted into the cochlear is a bonding pad 41 connected to the outside.

3A to 3L are cross-sectional views illustrating a method of manufacturing an electrode structure according to the present invention.

According to the semiconductor manufacturing process, forming the lower insulating layer, the metal electrode pattern and the upper insulating layer on the substrate is as follows.

First, as shown in FIG. 3A, the silicon nitride film is deposited on the silicon substrate 10 by chemical vapor deposition (CVD) using LPCVD equipment, and the sacrificial layer 21 and the mask for the etch stop are deposited. The sacrificial layer 22 is formed. In the case of using LPCVD, deposition is simultaneously performed on both sides of the substrate. The sacrificial layer (nitride film) 21 on the front side of the substrate is an etch stop layer for stopping the etching of the silicon substrate, the mask sacrificial layer (nitride film) 22 on the back side is a substrate etching mask layer to be deposited later, For example, it is used as a mask for etching silicon along with a silicon oxide film.

Thereafter, as shown in FIG. 3B, a silicon oxide film is deposited to a thickness of about 2 μm using the mask layer 70 for etching the substrate on the back side of the substrate by PECVD. The silicon oxide film is used as a mask for etching a silicon substrate.

3C, the lower insulating layer 32 is formed by spin coating polyimide on the etch stop sacrificial layer 21 deposited on the front surface of the substrate. The lower insulating layer 32 has a thickness of about 10 μm.

Thereafter, as shown in FIG. 3D, Ti (200 μs) / Au (3000 μs) / Ti (500 μs) are deposited on the lower insulating layer 32 by the vapor deposition method in order from the bottom. Here, Ti is an adhesion layer 50 for enhancing adhesion between the polyimide insulating layer 30 and the electrode material gold (Au).

Thereafter, as illustrated in FIG. 3E, the electrode pattern 40 is formed by patterning by a lift-off method.

Thereafter, as shown in FIG. 3F, polyimide to be used as the upper insulating layer 31 is deposited by about 6 μm by a spin coating method, and then Ti is used as the upper insulating layer etching mask layer 51. do. The upper insulating layer 31 serves to insulate between the electrode patterns 40 and insulate between the electrode patterns 40 and the biological material.

Thereafter, as shown in FIG. 3G, the deposited Ti layer (the upper insulating layer etching mask layer) 51 is patterned, and then the electrode (Reactive Ion Etching) dry etching method is performed using a dry etching method. The upper insulating layer (polyimide) 31 is etched to expose the portion 40 to be bonded to the bonding pad 41.

Thereafter, as shown in FIG. 3H, after the Ti mask layer 51 is additionally patterned to form an electrode structure as a whole, an etch stop sacrifice of the upper insulating layer 31, the lower insulating layer 32, and the front surface of the substrate is performed. The layer 21 is etched.

3I, the lower insulating layer 32, the metal electrode pattern 40, and the upper insulating layer 31 are formed on the substrate by removing the Ti mask layer 51.

Selectively patterning and etching the back surface of the substrate to form a partitioned partition wall as follows.

As shown in FIG. 3J, a mask for etching a silicon substrate by etching the substrate etching mask layer (silicon oxide film) 70 and the mask sacrificial layer (nitride film) 22 on the back side of the substrate by RIE dry etching. To form.

Thereafter, as shown in FIG. 3K, the division barrier rib is formed by dry etching to expose the etch stop sacrificial layer 21 on the front surface of the substrate using an ICP deep silicon etching process.

Thereafter, as shown in FIG. 3L, the silicon oxide layer 70 used as the mask and the nitride layer 22 on the back side of the substrate are removed, and at the same time, the etch stop sacrificial layer 21 on the front side of the substrate also includes the divided partition wall. Etch to match.

Subsequently, an electrode structure (FIG. 1) according to the present invention is manufactured by injecting the elastomer 60 into the back side of the substrate 10 through molding.

As described above, the electrode structure according to the present invention is flexible because the substrate portion is composed of a plurality of divided partitions arranged side by side at a predetermined interval.

In addition, the partition partition wall serves as a medium for enhancing adhesion between the lower insulating layer, for example, polyimide and the elastomer. First, the lower insulating layer and the substrate are very strongly adhered to each other, and since the substrate is divided into partition walls, the surface area is increased, thereby enabling structurally rigid bonding. In view of the adhesion effect in this physical aspect, it can be seen that in the electrode structure according to the present invention, in addition to silicon, a hard material such as quartz or pyrex glass can be used as the above-mentioned substrate. On the other hand, when using a silicone resin (silicone) as the elastomer, and a semiconductor substrate such as silicon (silicon) as the substrate may be more strongly bonded due to the chemical bonding between the Si atoms.

In addition, since a soft material such as elastomer or polyimide surrounds the substrate, the tissue is less damaged when inserted into the cochlea and has a sufficient volume, so that the position within the cochlea is stable after insertion. In addition, the substrate is less likely to be destroyed, and there is no fear that the fragments will be exposed out of the electrode structure even if the substrate is destroyed. In addition, since the metal electrode exists between the upper insulating layer and the lower insulating layer, there is no fear that the metal electrode is broken even if the substrate is destroyed.

In addition, the electrode structure according to the present invention can be easily manufactured because it uses a semiconductor process technology, can reduce the error between products, it is possible to increase the yield.

As described above, since the electrode structure according to the present invention has excellent flexibility and has a sufficient volume, it can be usefully used as an electrode for cochlear implants, and can be easily manufactured using a semiconductor manufacturing process. In the case of using a silicon substrate, circuit integration in the substrate is possible.

Claims (5)

An electrode for a cochlear prosthetic device inserted within a cochlear implant to electrically stimulate the cochlear nerve to provide hearing. Board; A lower insulating layer stacked on the substrate; An upper insulating layer stacked on the lower insulating layer; A metal electrode pattern formed between the lower insulating layer and the upper insulating layer by a semiconductor manufacturing process; And An elastomer attached to a lower portion of the substrate to support the metal electrode pattern; The substrate is flexible because it consists of a plurality of divided partitions arranged side by side at a predetermined interval, One side of the metal electrode pattern is in contact with the cochlear nerve, the other side is composed of a coupling pad for receiving an external electrical signal, characterized in that to electrically stimulate the cochlear nerve by an external electrical signal received through the coupling pad. Electrode for cochlear implant prosthetics. The electrode of claim 1, wherein the upper insulating layer and the lower insulating layer are made of polyimide or a liquid crystal polymer film. The electrode of claim 1, wherein the substrate is made of silicon, quartz, or pyrex glass. 4. The electrode for cochlear prosthetic device according to claim 3, wherein the substrate is silicon, and an active circuit is integrated on the silicon substrate. delete