Probe integrated with organic light source and manufacturing method thereof

Disclosed are a probe integrated with an organic light source and a manufacturing method thereof. An organic light source integration method includes forming a first thin film encapsulation layer on a probe shank, depositing a first electrode in a first region on the first thin film encapsulation layer, depositing an insulating layer in a second region on the first thin film encapsulation layer, depositing a light emitting layer on the first electrode and the insulating layer, depositing a second electrode on the light emitting layer, and forming a second thin film encapsulation layer on the second electrode.

The following application is incorporated herein, in its entirety, for all purposes: Korean Patent Application No. 10-2019-0115599, filed on Sep. 19, 2019, in the Korean Intellectual Property Office.

INTRODUCTION

A probe may be connected to a sensor using a needle-shaped tool made of metal as a kind of electrode to measure the temperature of a material, vibration, electrical changes during a chemical change, and the like. An optogenetic probe may measure electrical changes occurring at neurons, at the same time stimulating neurons expressing photoproteins with light by integrating a light source and a neural signal measuring electrode into the probe.

An existing optogenetic probe induces a laser beam to the end of a brain insertion part of the optogenetic probe by integrating a micro-light-emitting diode (pLED) within the device, or using a waveguide, thereby irradiating light onto tissues. However, the heat generated locally in the LED may incidentally activate and damage neurons. The waveguide also has a great light loss and thus, has low power efficiency.

An organic light-emitting diode (OLED) is a thin film LED made of a film of an organic compound, where a light-emitting layer emits light through electron-hole recombination.

SUMMARY

An aspect of the present disclosure provides a method of integrating an organic light source on a probe and a method of finely patterning a thin film encapsulation layer to protect an organic light source.

According to an aspect of the present disclosure, there is provided a method of integrating an organic light source, the method including forming a first thin film encapsulation layer on a probe shank, depositing a first electrode in a first region on the first thin film encapsulation layer, depositing an insulating layer in a second region on the first thin film encapsulation layer, depositing a light emitting layer on the first electrode and the insulating layer, depositing a second electrode on the light emitting layer, and forming a second thin film encapsulation layer on the second electrode.

The light emitting layer may include an organic light emitting material.

The depositing of the first electrode may include forming a fine pattern on the first thin film encapsulation layer using a photoresist, depositing a metal layer on the fine pattern, and forming the first electrode in the first region by performing lift-off on the metal layer.

The forming of the fine pattern may include patterning a region using the photoresist, except for a region for the first electrode and a region in which the first electrode is to be coupled to a power supply.

The depositing of the insulating layer may include depositing the insulating layer only in the second region so that only a region for the first electrode is opened on the first thin film encapsulation layer.

The depositing of the light emitting layer may include depositing the light emitting layer in high vacuum using a thermal evaporator.

The depositing of the light emitting layer may include depositing the light emitting layer only on the first electrode without covering a contact line of the second electrode.

The forming of the first thin film encapsulation layer may include patterning a photoresist in a region on a wafer except for the probe shank to form the first thin film encapsulation layer on the probe shank, coating the entire surface of the wafer with a thin film encapsulation layer, and forming the first thin film encapsulation layer by performing lift-off on the thin film encapsulation layer.

The forming of the second thin film encapsulation layer may include patterning a photoresist in a region on a wafer except for the probe shank to form the second thin film encapsulation layer on the second electrode, coating the entire surface of the wafer with a thin film encapsulation layer, and forming the second thin film encapsulation layer by performing lift-off on the thin film encapsulation layer.

The coating of the entire surface of the wafer with the thin film encapsulation layer may include coating the entire surface of the wafer with the thin film encapsulation layer through atomic layer deposition (ALD) and spin coating.

The method may further include depositing a sacrificial layer on a wafer, and manufacturing the probe shank on the sacrificial layer.

The probe shank may include a signaling electrode.

According to another aspect, there is provided a probe integrated with an organic light source, the probe including a probe shank, a first thin film encapsulation layer formed on the probe shank, a first electrode deposited in a first region on the first thin film encapsulation layer, an insulating layer deposited in a second region on the first thin film encapsulation layer, a light emitting layer deposited on the first electrode and the insulating layer, a second electrode deposited on the light emitting layer, and a second thin film encapsulation layer formed on the second electrode.

The light emitting layer may include an organic light emitting material.

The probe shank may include a signaling electrode.

The second region may include all regions except for the first region on the first thin film encapsulation layer.

The light emitting layer may be deposited only on the first electrode without covering a contact line of the second electrode.

DETAILED DESCRIPTION

Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. However, various alterations and modifications may be made to the example embodiments. Here, the example embodiments are not construed as limited to the disclosure. The example embodiments should be understood to include all changes, equivalents, and replacements within the idea and the technical scope of the disclosure.

When describing the example embodiments with reference to the accompanying drawings, like reference numerals refer to like constituent elements and a repeated description related thereto will be omitted. In the description of example embodiments, detailed description of well-known related structures or functions will be omitted when it is deemed that such description will cause ambiguous interpretation of the present disclosure.

FIG.1illustrates a process of an organic light source integration method according to an example embodiment.

An organic light source may be integrated on a probe200. For example, the organic light source may be finely patterned and integrated on a flexible probe200including a signaling electrode.

A thin film encapsulation layer may be formed to protect the probe200from an external environment. For example, the thin film encapsulation layer may be formed on the bottom and/or on the top of the organic light source integrated in the probe200to protect the organic light source from the external environment.

If an organic light source is manufactured using only a shadow mask, delicate patterning may not be performed at pattern edges due to the characteristics of shadow mask process, such that the brightness and/or color of the light source may be nonuniform. In addition, since the shadow mask needs to be changed in situ in a high-vacuum chamber, misalignment may occur at this time. If the length resolution of the pattern is reduced to a few micrometers (μm) through shadow mask process, the accuracy of the pattern may decrease.

Further, since there exists a space between a substrate and a mask due to the thickness of the shadow mask during deposition using the shadow mask, the size of the manufactured organic light source may be larger than 900 μm2. That is, if an organic light source is manufactured with a multilayer structure of a metal electrode layer, an organic light source layer, and the like, it may be difficult to accurately adjust the organic light source to a desired size.

The light source integrated into the probe200may be manufactured in a smaller size than the conventional light source, and a thin film encapsulation layer is formed to protect the light source from the external environment when inserted into the body. Thus, the probe200may stably and selectively stimulate neurons in a local site, thereby enabling accurate brain research.

By fine patterning instead of the process method using a shadow mask, the organic light source may be manufactured in a size sufficient to stimulate neurons, for example, in a size of 10 μm×10 μm, and may further be manufactured with a length of at least several μm. In addition, since a 4-inch wafer process is possible, a large area process may be performed.

For example, an organic light source of a size of tens to hundreds of μm2may be integrated in the probe200, and a thin film encapsulation layer of the organic light source may be finely patterned to protect the organic light source from the outside.

A micro-organic light-emitting diode (OLED) and a signaling electrode may be integrated into an optogenetic brain probe200. For example, on the flexible and transparent brain probe200, an organic light source (for example, an OLED) with a small local heat production may be manufactured and integrated in a micro size, and a thin film encapsulation layer capable of protecting the integrated micro OLED may be finely patterned, such that the light source may be protected.

A micro-OLED is a light source that has not been used in the conventional implantable photic stimulation brain probes. The brain probe200integrated with the micro OLED and the signaling electrode for measuring signals of neurons together may enable stable and local photic stimulation and measurement of neuron signals at the same time.

Hereinafter, a process of an organic light source integration method10will be described.

In operation S101, the organic light source integration method10may dispose a probe shank310on a wafer100. For example, the probe shank310may be disposed on the wafer100to integrate an organic light source on the probe shank310.

In operation S102, the organic light source integration method10may form a bottom thin film encapsulation layer on the probe shank310. For example, the organic light source integration method10may form the bottom thin film encapsulation layer by patterning a thin film encapsulation layer on the probe shank310through thin film encapsulation.

In operation S103, the organic light source integration method10may pattern an anode on the bottom thin film encapsulation layer. For example, the anode may be an OLED anode.

In operation S104, the organic light source integration method10may pattern an insulator on the bottom thin film encapsulation layer. For example, the organic light source integration method10may deposit an insulating layer by patterning the insulator in a region where the anode is not formed on the bottom thin film encapsulation layer.

In operation S105, the organic light source integration method10may deposit a light emitting layer and a cathode on the anode and the insulating layer. For example, the organic light source integration method10may deposit the light emitting layer on the anode and the insulating layer, and deposit the cathode on the light emitting layer. The light emitting layer may include an organic light emitting material.

After the cathode is deposited, the organic light source integration method10may form a top thin film encapsulation layer, in operation S106. For example, the organic light source integration method10may pattern a thin film encapsulation layer through thin film encapsulation to protect the organic light emitting layer. That is, the top thin film encapsulation layer may be formed to enclose the anode, the insulating layer, the light emitting layer, and the cathode deposited on the bottom thin film encapsulation layer.

FIG.2illustrates a detailed process of the organic light source integration method shown inFIG.1.

The organic light source integration method10may deposit, on the probe shank310of the brain probe200, thin film encapsulation layers400-1and400-2, a first OLED metal300, a second OLED metal700, a light emitting layer600, and an insulating layer800.

In this case, the first OLED metal300may include an anode300-1and contact line300-2, and the second OLED metal700may be a cathode layer, and a first probe material210may be used for the insulating layer800. In addition, the light emitting layer600may be an organic layer.

A process of manufacturing a probe may include operations S201to S203which will be described in detail below with reference toFIG.7.

In operation S204, the bottom thin film encapsulation layer400-1may be formed on the probe shank310. The bottom thin film encapsulation layer400-1may be formed on the entire upper surface of the probe shank310. For example, the upper surface of the probe shank310may be coated with the bottom thin film encapsulation layer400-1to protect the organic light source.

Fine patterning for the first OLED metal300may be performed on the bottom thin film encapsulation layer400-1. A photoresist (not shown) may be formed on the bottom thin film encapsulation layer400-1, and a fine pattern for the first OLED metal300may be formed on the bottom thin film encapsulation layer400-1through the photoresist (not shown). In this case, the photoresist (not shown) may be formed in a region except for a region (for example, a first region) on the bottom thin film encapsulation layer400-1in which the first OLED metal300is to be disposed. For example, the first region may include a region for the anode300-1and the contact line300-2for connection between the anode300-1and a power supply (not shown) for light emission of the light source.

In operation S205, the first OLED metal300may be deposited along the fine pattern formed on the bottom thin film encapsulation layer400-1. For example, the anode300-1and the contact line300-2may be deposited on the fine pattern formed on the bottom thin film encapsulation layer400-1using a thermal evaporator. That is, the first OLED metal300may be deposited on the first region on the bottom thin film encapsulation layer400-1in which the anode300-1and the contact line300-2are to be formed and the entire region coated with a photoresist500.

The anode300-1and contact line300-2may be formed in the first region on the bottom thin film encapsulation layer400-1by performing lift-off on the first OLED metal300. For example, the patterned photoresist (not shown) may be lifted off using an acetone solution. If the photoresist (not shown) is lifted off, the anode300-1and the contact line300-2may be formed only in the first region on the bottom thin film encapsulation layer400-1. Through this, the anode300-1and the contact line300-2may be deposited in a region that may effectively contribute to the light emitting area.

The anode300-1and the contact line300-2can each be deposited through separate lift-off processes. For example, contact line300-2may be deposited first and anode300-1may be deposited later.

The light emitting area of the micro-sized OLED may be determined according to the size and shape of the anode300-1that is finely patterned (or formed by fine patterning).

A shadow mask may be used to deposit a metal layer only in the region for connection between the anode300-1and the power supply for light emission of the light source, on the probe shank310. However, in this case, the size of the manufactured light source may be 900 μm2or more. Thus, it may be difficult to locally stimulate neurons.

In operation S206, the insulating layer800may be finely patterned on the bottom thin film encapsulation layer400-1. The insulating layer800may be deposited in a region on the bottom thin film encapsulation layer400-1except for the region in which only anode300-1is deposited. For example, the insulating layer800may be deposited in a region where contact line300-2is deposited under the anode300-1.

The insulating layer800may be finely patterned using a shadow mask and/or a photoresist (not shown). Further, the insulating layer800may be finely patterned and deposited by various methods such as using a thermal evaporator depending on the type of insulator that is used.

By depositing the insulating layer800on a region in which the anode300-1is not deposited on the bottom thin film encapsulation layer400-1, misalignment between the anode300-1and the light emitting layer600may be prevented, and light may be emitted from a desired region of the light source.

That is, even when a multilayer structure is formed through fine patterning of the insulating layer800, a micro-sized OLED may be formed on the probe shank310without inter-layer misalignment.

In operation S207, the light emitting layer600may be deposited on the anode300-1and the insulating layer800. For example, the light emitting layer600may be deposited in high vacuum using a thermal evaporator. In this case, the light emitting layer600may include an organic material (for example, an organic light emitting material).

When the light emitting layer600is deposited using a shadow mask, the light emitting layer600may be deposited only on the anode300-1without covering a contact line300-2.

In operation S207, the cathode layer700may be deposited on the light emitting layer600. For example, the cathode layer700may be deposited to cover both the light emitting layer600and the contact line for cathode, thereby enabling passivation of the light emitting layer600and contact of the cathode electrode at the same time. The cathode layer700may be a metal layer.

In operation S207, the top thin film encapsulation layer400-2may be formed on the very top of the deposited organic light source. For example, top thin film encapsulation layer400-2may protect the organic light source by coated on the very top of the deposited organic light source.

FIG.3illustrates a probe shank manufactured by the organic light source integration method shown inFIG.1.

The brain probe200may include the probe shank310, a neural signaling line contact pad (not shown; hereinafter, referred to as the “neural contact pad”), and an OLED cathode and anode contact line contact pad (not shown; hereinafter, referred to as the “OLED contact pad”).

The first OLED metal300, the organic material600, and the cathode700may be deposited on the probe shank310.

Power may be supplied to the anode300-1from the OLED contact pad (not shown) through a metal contact line300-2, and as the power is supplied, the organic material600in contact with the region in which the anode300-1is deposited may emit light. The organic material600may also emit light on a metal contact line.

The probe shank310may include a signaling electrode. Signals of neurons may be detected through the signaling electrode, and the detected signals may be transmitted to the neural contact pad (not shown).

The surface of the probe shank310except for the anode300-1may be coated (or patterned) with an insulator, such that the anode300-1may stably contact the organic material600, and the organic material600may emit light only at a desired site.

FIGS.4A to4Cillustrate a first OLED metal and insulator finely patterned in a brain probe integrated with an organic light source.

FIG.4Ashows an example in which the contact line300-2is finely patterned in a desired region on the probe shank310.

FIG.4Bshows an example in which the anode300-1is finely patterned in a desired region on the probe shank310.

FIG.4Cshows an example in which the insulator800is finely patterned in a desired region on the probe shank310. The insulator800may be deposited except for a region where anode300-1is patterned. That is, insulator800may cover the contact line300-2.

FIG.5illustrates a detailed process of thin film encapsulation layer formation in the organic light source integration method shown inFIG.1.

The thin film encapsulation layers400-1and400-2may be formed to enclose the light emitting layer600, for example, a micro-OLED. The thin film encapsulation layers400-1and400-2may protect the micro-OLED from the external environment.

The thin film encapsulation layers400-1and400-2may be formed on the entire surface of the wafer by atomic layer deposition (ALD) and spin coating. Spin coating is a physical method of uniformly coating the entire surface with a solution, and thus it is difficult to pattern the thin film encapsulation layers400-1and400-2in a micro size. In addition, the thin film encapsulation layers400-1and400-2include organic and inorganic materials. Thus, when the thin film encapsulation layers400-1and400-2are immersed in a metal etchant such as an acid or alkaline etchant, the encapsulation layers may be damaged by the etchant and thus, hardly maintain their original functions.

The entire surface of the wafer may be coated with the thin film encapsulation layers400-1and400-2, and then the thin film encapsulation layers400-1and400-2may be finely patterned using lift-off.

That is, the thin film encapsulation layers400-1and400-2that cannot be finely patterned may be finely patterned, by adjusting the hard bake time of the photoresist500to form the fine pattern of the thin film encapsulation layers400-1and400-2.

The organic and inorganic layers formed on the entire surface of the wafer100may be finely patterned through spin coating and ALD by controlling the hard bake time. Thus, the micro-sized organic light source600having stable performance may be integrated into the micro-brain probe200.

In operation S501, the probe shank310may be disposed on a sacrificial layer150.

In operation S502, the photoresist500may be patterned to enclose the perimeter of the probe shank310. The entire surface of the wafer, except for the region in which the probe shank310is disposed, may be coated with the photoresist500. Accordingly, if the photoresist500is lifted off, the bottom thin film encapsulation layer400-1may be formed only on the probe shank310.

In operation S503, the thin film encapsulation layer400-1may be formed on the entire surface of the wafer by ALD and spin coating.

The bottom thin film encapsulation layer400-1may be formed on the probe shank310by lifting off the photoresist500. If the photoresist500is lifted off, the thin film encapsulation layer400-1on the region coated with the photoresist500may be removed, and only the thin film encapsulation layer400-1on the probe shank310not coated with the photoresist500may be retained, whereby the bottom thin film encapsulation layer400-1may be formed on the probe shank310.

A micro-OLED may be manufactured on the bottom thin film encapsulation layer400-1. For example, the micro-OLED may be manufactured by depositing the anode300, the insulating layer800, the light emitting layer600, and the cathode700on the bottom thin film encapsulation layer400-1.

The thin film encapsulation layer400-2may be formed on the top to enclose the micro-OLED disposed on the probe shank310. As in the process of forming the bottom thin film encapsulation layer400-1, the photoresist500may be patterned in the perimeter of the probe shank310, and the entire surface of the wafer may be coated with the thin film encapsulation layer400-2, in operation S506.

The top thin film encapsulation layer400-2enclosing the micro-OLED may be formed by lifting off the photoresist500.

The bottom thin film encapsulation layer400-1and the top thin film encapsulation layer400-2may completely enclose the micro-OLED disposed on the probe shank310, thereby protecting the micro-OLED from the external environment.

FIGS.6A to6Cillustrate a thin film encapsulation layer of a probe manufactured through the thin film encapsulation layer formation shown inFIG.5.

The thin film encapsulation layers400-1and400-2formed on the surface of the probe200are shown. The thin film encapsulation layers400-1and400-2may efficiently protect the OLED integrated into the probe shank310from the external environment.

FIG.7illustrates an example of a process of manufacturing a probe.

The probe200may be manufactured on the wafer100. For example, the probe200may be manufactured by depositing the first probe material210, the second probe material230, and a signaling electrode900on the wafer100.

In operation S601, the sacrificial layer130may be deposited on the wafer100, and the first probe material210may be patterned on the sacrificial layer130. By depositing the sacrificial layer130on the wafer100, the probe200that is manufactured may be separated from the wafer. An insulator may be used as the first probe material210to form the structure of the probe200.

In operation S602, the signaling electrode900and/or the metal contact line may be patterned. For example, the signaling electrode900and/or the metal contact line may be patterned by depositing a metal layer on a fine pattern of the photoresist500and then lifting off the photoresist500.

In operation S603, the second probe material230may be patterned on the top and the outside of the first probe material210, the signaling electrode900, and/or the metal contact line. The second probe material230may improve adhesion by using a material different from the first probe material210. Since the second probe material230is deposited on the entire surface of the wafer, the photoresist500and a metal mask may be used to form the second probe material230at the bottom to enclose a region in which the first probe material230, the signaling electrode900, and the metal contact line are deposited.

In operation S604, the first probe material210may be patterned on the second probe material230. For example, the first probe material210may be patterned using the photoresist500and the metal mask.

For example, the photoresist500may be patterned on the second probe material230, and a metal layer may be deposited on the photoresist500. In order to etch the second probe material230deposited on an unnecessary region, the metal mask may be patterned to fit a required region. The photoresist500may be patterned only in a region for etching the second probe material230and may be lifted off together with the metal layer. In this case, the metal mask may be Al.

The second probe material230may be etched except for the region blocked by the metal mask. For example, the second probe shank material230in an unnecessary region may be etched through O2plasma etching.

The metal mask deposited to etch the second probe material230may be removed. After that, the first probe material210may be patterned on the very top. For example, the first probe material210may be formed thickly on the underlying layers.

FIGS.8A and8Billustrate light emission of a probe manufactured by the organic light source integration method shown inFIG.1, andFIGS.8C to8Eare graphs showing the performance of a probe manufactured by the organic light source integration method shown inFIG.1.

Referring toFIGS.8A to8B, it may be learned that an organic light source is successfully integrated into the probe shank310and emits light.

FIG.8Cshows I-V data of the organic light source. Each of theFIGS.8D and8Eshows wavelength spectrum data and optical power density data of the organic light source. The wavelength should be between 450 nm and 470 nm and the optical power density should be at least 1 mW/mm2, which shows that both are satisfied.

By manufacturing the organic light source in micro size through fine patterning of the anode300-1, and by integrating the micro-sized organic light source that may stably operate from the external environment through fine patterning of the thin film encapsulation layers400-1and400-2into the brain probe200, local photic stimulation on neurons and neural signal measurement therethrough may be enabled.

In addition, since the light emitting layer of the micro-OLED is manufactured by thermal evaporation using a shadow mask, OLED pixels deposited on the brain probe200may be manufactured in various colors through shadow mask patterning. In other words, even a single brain probe200may irradiate light of various wavelengths and thereby stimulate various photoproteins, and thus more types of neurons may be activated at a time.

The patterning process of the thin film encapsulation layers may independently protect each OLED pixel in a device such as an OLED microarray in the future.