KR100960641B1 - Method for fabricating liquid lens using wafer level packaging - Google Patents

Abstract

The present invention relates to a liquid lens manufacturing method using wafer level packaging to improve the efficiency of the quality control and manufacturing process by performing a packaging process in a wafer level state where a plurality of liquid lenses are formed, the electrode pad on the lower glass wafer Forming a plurality of chamber regions on the silicon wafer to be used as the intermediate plate; forming an insulating film on the silicon wafer; bonding the lower glass wafer and the silicon wafer to each other, and the electrolyte solution and the insulating solution inside the plurality of chamber regions. Forming a plurality of liquid lenses by bonding the upper glass wafer to the silicon wafer; And individualizing a plurality of liquid lenses and opening the electrode pad.

Liquid Lens, Wafer Level Package, DFR, Insulation, Electrolyte, Chamber

Description

Method for fabricating liquid lens using wafer level packaging

The present invention relates to a liquid lens, and more particularly, to a liquid lens manufacturing method using wafer level packaging, in which a packaging process is performed at a wafer level in which a plurality of liquid lenses are formed, thereby improving efficiency of quality control and manufacturing processes. .

The liquid lens is an application of the human eye's lens to change the focus by changing its shape.The liquid lens has a simple structure and no mechanical driving part, so it is not only reliable, suitable for mass production, but also fast for reaction and very low power consumption. It can be downsized to several millimeters or less.

Liquid lenses can be used in various ways such as digital cameras, camera phones, endoscopes, security systems, optical recording devices, and the like.

The basic principle of the liquid lens is as follows.

When a conductive solution droplet such as water is placed on a substrate composed of an insulator and a metal plate and a voltage is applied between the metal plate and the conductive solution, as shown in FIG. 1A, the shape of the conductive solution drop on the insulator is changed from the dotted line A while increasing the hydrophilicity of the insulator. It changes to the form of the solid line B.

Such a phenomenon is called an electrowetting phenomenon.

Instead of the water defenses placed in the air as in FIG. 1A, electrowetting can be found even with water and oil having the same density and different refractive indices and not mixing with each other as shown in FIG.

In the situation in which the oil droplet, which is a non-conductive solution, is immersed in the water, which is a conductive solution, the hydrophilicity of the insulator increases according to the electrowetting phenomenon, and thus the shape of the water, which is the conductive solution, is changed from the dotted line A to the solid line B. Will change.

This electrowetting phenomenon refers to the contact angle between the conductive solution and the two solutions by controlling the surface tension of the conductive solution by applying a voltage to the electrode and the conductive solution from the outside when the conductive solution and the non-conductive solution contact the electrode coated with the insulator. It means to change the shape of the interface.

2 shows the structure by the individual liquid lens packaging process of the prior art.

A lower substrate 21 having an electrode 22 formed thereon, a chamber 25 bonded to the lower substrate 21 and filling a solution therein, an insulating film 24 formed on the surface of the chamber 25, and a few The film 23 includes an electrolyte solution 26 and an insulating solution 27 filled in the chamber 25, and the upper substrate 28 is bonded to the upper portion of the chamber 25.

Here, an oxide film (SiO ₂ ) is used for the insulating film 24, and parylene is used for the hydrophobic film 23.

Such a liquid lens packaging method of the prior art is a form in which the chamber in which the chamber is formed and the lower substrate in which the metal electrode is formed are bonded to each other and then cut and separated, injecting a solution into the separated individual elements, and packaging the upper substrate.

Therefore, the liquid lens packaging method of the prior art has the following problems.

That is, as each liquid lens is packaged one by one, it takes a long time and reduces productivity.

In addition, even when inspecting the packaged device efficiency is reduced, there is a difficulty in applying the aspect.

The present invention is to solve the problem of the conventional packaging method of the liquid lens, the wafer level to improve the efficiency of the quality control and manufacturing process by proceeding the packaging process in the state of the wafer level formed with a plurality of liquid lenses It is an object of the present invention to provide a liquid lens manufacturing method using packaging.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid lens manufacturing method using wafer level packaging, in which a packaging process is performed at a wafer level in which a plurality of liquid lenses are formed to increase productivity and increase efficiency in device inspection. .

According to an aspect of the present invention, there is provided a method of manufacturing a liquid lens using wafer level packaging, the method including: forming an electrode pad on a lower glass wafer; forming a plurality of chamber regions on a silicon wafer to be used as a middle plate; Forming an insulating film on a wafer; bonding the lower glass wafer and the silicon wafer, injecting an electrolyte solution and an insulating solution into the plurality of chamber regions, and bonding an upper glass wafer on the silicon wafer to form a plurality of liquids. Forming a lens; And individualizing the plurality of liquid lenses and opening the electrode pad.

The forming of an electrode pad on the lower glass wafer may include: depositing an electrode forming material layer on the lower glass wafer; selectively patterning the electrode forming material layer to form an electrode layer; And forming a bonding layer for wafer bonding on the lower glass wafer having the electrode layer formed thereon.

The forming of the bonding layer may include stacking a dry film resist (DFR) for bonding to the silicon wafer on the lower glass wafer on which the electrode layer is formed; and selectively patterning the DFR so that only the bonding region remains. To form a bonding layer on the lower glass wafer.

And forming a stop groove in the silicon wafer before the forming of the chamber region on the silicon wafer.

The forming of the stop groove on the silicon wafer may be performed in a circular shape around a region where the chamber is to be formed by using any one of a sand blasting process and a silicon deep etching process using an ICP. It is characterized by forming.

The forming of the chamber region may include removing the region in which the chamber is to be formed using any one of laser processing on the silicon wafer, Si deep etching using ICP, and a diamond drill. It is characterized by being formed.

The forming of the insulating film may include: forming a first insulating film on a surface of the silicon wafer; And forming a second insulating film on side surfaces of the plurality of chamber regions of the silicon wafer on which the insulating film is formed.

The forming of the first insulating layer may be performed by selectively stacking one of a thermal oxide film using a thermal oxidation process, a nitride film using a CVD (Chemical Vapor Deposition), and a paraline film.

The first insulating film has a laminated structure in which a thermal oxide film is grown to a thickness of 1,000 to 3,000 kPa using a thermal oxidation method, and a nitride film having a thickness of 0.3 to 1 μm is formed on the thermal oxide film by CVD. It is done.

The forming of the second insulating layer may include forming a protective film on the lower portion of the silicon wafer and forming a mask layer on the silicon wafer; a plurality of chambers of the silicon wafer on which the protective film and the mask layer are formed. Forming a hydrophobic insulating film on the side of the region; And removing the protective film and the mask layer formed on the silicon wafer.

The forming of the hydrophobic insulating layer may include forming a hydrophobic insulating layer by coating a Teflon layer on one side of the plurality of chamber regions by any one of dipping, spraying, or spin coating. .

The forming of the plurality of liquid lenses may include: bonding the lower glass wafer and the silicon wafer; injecting electrolyte into a plurality of chamber regions of the bonded silicon wafer, and having specific gravity without mixing with the electrolyte. Injecting the same insulating liquid to protrude above the upper surface of the silicon wafer; And bonding the silicon wafer and the upper glass wafer into which the electrolyte and the insulating liquid are injected.

The bonding of the silicon wafer and the upper glass wafer may include forming a bonding layer on the silicon wafer, and heat treating the formed bonding layer at a temperature of 150 to 190 ° C. to bond the silicon wafer and the upper glass wafer. Characterized in that.

The separating of the plurality of liquid lenses and exposing the electrode pads to the outside may include a process of dicing the plurality of liquid lenses in a half-cutting form in which a part of a silicon wafer remains for each liquid lens. Defining a pad open area; Dicing the plurality of liquid lenses, each having an electrode pad open region defined therein, in individual units; And removing the electrode pad open region to expose the electrode pad on the lower glass wafer.

The liquid lens manufacturing method using the wafer level packaging according to the present invention has the following effects.

First, the packaging process may be performed at a wafer level in which a plurality of liquid lenses are formed, thereby improving efficiency of quality control and manufacturing process.

Second, since the solution is injected and packaged at the wafer level, the separation process is performed when the packaging is completed, thereby reducing the occurrence of defects during the manufacturing process.

Third, since the silicon wafer is used as the body electrode of the liquid lens, it is possible to apply the general semiconductor process in the wafer state.

Fourth, the packaging process may be performed in a wafer level state in which a plurality of liquid lenses are formed, thereby reducing the manufacturing process progress time and increasing the possibility of mass production.

Hereinafter, a preferred embodiment of a liquid lens manufacturing method using wafer level packaging according to the present invention will be described in detail.

Features and advantages of the liquid lens manufacturing method using wafer level packaging according to the present invention will become apparent from the detailed description of each embodiment below.

3A and 3B are cross-sectional configuration diagrams of a liquid lens using wafer level packaging according to the present invention.

The present invention can increase the ease and efficiency of the process by performing a separate process of the injection and packaging process of the solution in the wafer level state to individually complete the packaging.

After the silicon structure in which the chamber is formed and the lower glass in which the metal electrode is formed are bonded together, the injection and packaging of the solution is completed at the wafer level without separate cutting, and then separated separately.

First, FIG. 3A is bonded to the lower glass wafer 31 and the lower glass wafer 31 on which the electrode pads 32 are formed corresponding to the respective liquid lens forming regions, and is formed on the silicon wafer 35 to be formed therein. And a chamber for filling the solution, an insulating film 34 formed on the surface of the chamber, a hydrophobic film 33, and an electrolyte solution 36 and an insulating solution 37 filled in the chamber. The upper glass wafer 38 is bonded.

As described above, the external exposed area 39 of the electrode pad is diced in the form of half cutting to expose the electrode pad to the outside in the state where the injection of the solution and the upper glass wafer 38 are bonded to each other. Each liquid lens is separated separately at the wafer level.

3B is a structure in which a jersey groove 52 is formed in a circle around the chamber region of the silicon wafer 51 and a UV epoxy layer 60 is formed outside the jersey groove 52. A lower glass wafer 41 having an electrode pad 42a corresponding to the formation region, a bonding layer 43a bonded to the lower glass wafer 41, a chamber for filling a solution therein, and a surface of the chamber And an insulating film 54, a hydrophobic film 57, an electrolyte 61 filled in the chamber, and an insulating liquid 62. The upper glass wafer 63 is bonded to the upper portion of the chamber. .

As described above, the external exposed region 64 of the electrode pad, which is diced in the form of half cutting, is defined to expose the electrode pad to the outside while the solution is injected and the upper glass wafer 63 is bonded, and the dicing isolation region 65 Each liquid lens is separated separately at the wafer level.

3A and 3B show a dicing process for injecting a solution into the chamber area, covering the top glass wafer for wafer level packaging, half cutting to expose the electrode pads to the outside, and individually separating the respective liquid lenses. The structural cross section of the state which progressed.

The liquid lens manufacturing method using wafer level packaging according to the present invention can be roughly divided into a lower substrate manufacturing process, a mid-sized silicon manufacturing process, and a wafer level packaging process.

The following description focuses on the structure of FIG. 3B which forms a stop groove to serve to prevent the injected solution from flowing out during bonding of the upper glass substrate and to prevent the epoxy from being pressed into the chamber.

In addition to the formation of the stop groove and the epoxy layer, the other processes proceed in the same manner as in the liquid lens of FIGS. 3A and 3B.

First, the lower substrate manufacturing process is as follows.

4A-4E are cross-sectional views of a process for manufacturing a bottom glass of a liquid lens using wafer level packaging according to the present invention.

First, as shown in FIGS. 4A and 4B, an electrode layer material 42 is deposited on the lower glass wafer 41.

The material layer 42 for forming an electrode uses Au.

Next, as shown in FIG. 4C, the electrode layer material 42 is selectively patterned by the photolithography process to form the electrode layer 42a deposited on the lower glass wafer 41.

As shown in FIG. 4D, a dry film resist (DFR) 43 for wafer bonding is stacked on the lower glass wafer 41 on which the electrode layer 42a is formed, and as shown in FIG. 4E, the stacked DFR 43 is stacked. Is selectively patterned by a photolithography process so that only the bonding region remains, thereby forming the bonding layer 43a.

And the middle silicon manufacturing process is as follows.

5A through 5G are cross-sectional views of a process for manufacturing a mid-sized silicon substrate of a liquid lens using wafer level packaging according to the present invention.

First, as shown in FIGS. 5A and 5B, any one of a sand blasting process or a silicon deep etching process using ICP is applied to a silicon wafer 51 used as a container (chamber) and a body electrode of a solution. A blocking groove 52 is formed in a circle around the chamber forming regions so as to correspond to the respective chamber forming regions.

The stop groove 52 formed corresponding to the respective chamber forming regions by the above process prevents the injected solution (oil) from flowing out during the upper glass bonding by the epoxy after solution injection and the epoxy from being pressed into the chamber. It plays a role.

As illustrated in FIG. 5C, the silicon wafer 51 having the blocking grooves 52 is selectively processed to remove only the chamber forming region, thereby forming a plurality of chambers 53 serving as solution injection regions.

Each chamber 53 is formed to be spaced apart at regular intervals in the inner center of the blocking groove 52, the process for forming the chamber 53 is laser processing, silicon deep etching (Si deep etching) using ICP, or Form using a diamond drill.

Subsequently, as illustrated in FIG. 5D, the first insulating film, that is, the insulating film 54 is formed on the silicon wall inside the chamber 53 to enable the electrowetting phenomenon.

The insulating film 54 may be a thermal oxide film using a thermal oxidation process, a nitride film using a CVD (Chemical Vapor Deposition), a paraline film, or the like, and may be used in combination.

Preferably, the thermal oxide film is first grown to a thickness of 1,000 to 3,000 kPa using the thermal oxidation method. This thermal oxide film has an effect of increasing the insulation strength.

A nitride film having a thickness of 0.3 to 1 μm is formed on the substrate by CVD to have a stacked structure of an oxide film and a nitride film.

Since the nitride film has a higher dielectric constant than the oxide film, the nitride film exhibits an electrowetting phenomenon at a low voltage.

5E, a UV film is attached to a lower surface of the silicon wafer 51 to be bonded to the lower glass to form a protective film 55, and an upper part of the mask layer 56 is formed by depositing and selectively patterning a DFR. To form.

Subsequently, as shown in FIG. 5F, a hydrophobic insulating film 57 is formed as a second insulating film in the plurality of chambers 53 formed in the silicon wafer 51.

The hydrophobic insulating film 57 is formed by coating a Teflon film on the wall surface of the chamber 53 by using a method such as dipping, spraying or spin coating.

In this case, the Teflon membrane uses a Teflon-AF solution produced by DuPont.

Here, in the process of forming the hydrophobic insulating film 57 with the second insulating film inside the chamber 53 of the silicon wafer 51, instead of the process of forming a mask layer 56 by depositing and selectively patterning a DFR on the top. It is also possible to form the hydrophobic insulating film 57 in a masked state using a shadow mask.

As shown in FIG. 5G, the protective film 55 and the mask layer 56 are removed to prepare a middle silicon layer.

As described above, when the lower substrate and the intermediate silicon are manufactured, the wafer level package process is performed as follows.

6A-6I are cross-sectional views of a wafer level packaging process of a liquid lens in accordance with the present invention.

In the wafer level packaging process of the liquid lens, as shown in FIG. 6A, the lower glass wafer 41 having the plurality of electrode layers 42a and the bonding layer 43a and the middle silicon layer, that is, the plurality of chambers 53 are formed. The wafer 51 is bonded using the bonding layer 43a at a temperature of 150 to 190 ° C.

As shown in FIG. 6B, the UV epoxy layer 60 is formed on the outer periphery of the blocking groove 52 of the upper portion of the silicon wafer 51 by screen printing or dispensing.

6C, the electrolyte 61 is injected into each chamber 53 formed in the silicon wafer 51.

6D, an insulating solution 62 having the same specific gravity is injected without mixing with the electrolyte 61.

Here, the insulating liquid 62 is injected to protrude above the upper surface of the silicon wafer 51.

Subsequently, as shown in FIG. 6E, the upper glass wafer 63 is covered on the silicon wafer 51 on which the UV epoxy layer 60 is formed to be cured by UV irradiation.

At this time, the insulating glass 62 is pushed out to cover the upper glass wafer 63 so that no bubbles are formed in the chamber 53.

Although not shown, a bonding layer formed by patterning a DFR is formed in the bonding region of the silicon wafer 51 to be bonded to the upper glass wafer 63, and the bonding of the silicon wafer 51 and the upper glass wafer 63 is performed. The step is performed by the step of heat-treating the bonding layer at a temperature of 150 to 190 ° C.

6F, the bonded structure of the lower glass wafer 41, the silicon wafer 51, and the upper glass wafer 63 is selectively etched, and subsequently, the electrodes 42a of the lower glass wafer 41 are subjected to a subsequent separation process. The dicing process is performed such that the silicon wafer 51 has a thickness of about 100 μm or less from the bottom surface so as to expose the pad, thereby defining the external exposed area 64 of the electrode pad.

6G and 6H, the upper glass wafer 63, the middle silicon wafer 51, and the lower glass wafer 41 are removed to define the dicing isolation region 65, and the respective liquid lens elements Dicing process is carried out so that can be separated.

6I, each separated liquid lens is removed with the half-cut separation silicon layer 66 so that the pad of electrode 42a on the lower glass wafer is exposed.

The liquid lens manufacturing method using the wafer level packaging according to the present invention improves productivity because the packaging is performed in a state where a plurality of liquid lenses are formed at the wafer level.

In addition, since the process is performed at the wafer level, quality control of the product is easy, which is advantageous in mass production.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1A and 1B are schematic diagrams for explaining the principle of a liquid lens.

2 is a structural cross-sectional view of an individual liquid lens packaging process of the prior art.

3A and 3B are cross-sectional configuration diagrams of a liquid lens using wafer level packaging according to the present invention.

4A-4E are cross-sectional views of a process for manufacturing a bottom glass of a liquid lens using wafer level packaging according to the present invention.

5A to 5G are cross-sectional views of a process for manufacturing a mid-sized silicon substrate of a liquid lens using wafer level packaging according to the present invention.

6A-6I are cross-sectional views of a wafer level packaging process for a liquid lens in accordance with the present invention.

Explanation of symbols for the main parts of the drawings

41. Lower glass wafer 42. Metal layer for electrode formation

43. DFR 51. Silicon Wafers

52. Jersey groove 53. Chamber

54. Insulation film 55. Protective film

56. Mask layer 57. Hydrophobic insulating film

60. UV Epoxy Layer 61. Electrolyte

62. Insulating solution 63. Upper glass wafer

64. Electrode pad open area 65. Dicing separation area

66. Separation Silicon Layer

Claims (14)

Forming an electrode pad on the lower glass wafer; Forming a plurality of chamber regions on a silicon wafer to be used as a heavy plate; Forming an insulating film on the silicon wafer; Bonding the lower glass wafer and the silicon wafer, injecting an electrolyte solution and an insulating solution into the plurality of chamber regions, and bonding the upper glass wafer on the silicon wafer to form a plurality of liquid lenses; And, Separating the plurality of liquid lenses individually and exposing the electrode pads to the outside; liquid lens manufacturing method using wafer level packaging, comprising: a. The method of claim 1, wherein forming an electrode pad on the lower glass wafer comprises: Depositing an electrode forming material layer on the lower glass wafer; Selectively patterning the electrode forming material layer to leave only an electrode region to form an electrode layer; And forming a bonding layer for wafer bonding on the lower glass wafer on which the electrode layer is formed. The method of claim 2, wherein the forming of the bonding layer, Stacking a dry film resist (DFR) for bonding to the silicon wafer on a lower glass wafer on which the electrode layer is formed; and Selectively patterning the DFR such that only a bonding region remains, thereby forming a bonding layer on the lower glass wafer. The method of claim 1, further comprising forming a stop groove in the silicon wafer before the forming of the chamber region on the silicon wafer. The method of claim 4, wherein forming a stop groove on the silicon wafer comprises: Manufacture of liquid lens using wafer level packaging, wherein the silicon wafer is formed around the region where the chamber is to be formed by using any one of a sand blasting process and a silicon deep etching process using ICP. Way. The method of claim 1, wherein the forming of the chamber region comprises: Wafer-level packaging, characterized in that the chamber region is formed by removing the region where the chamber is to be formed using any one of laser processing, Si deep etching using ICP, and diamond drill in the silicon wafer. Liquid lens manufacturing method using the. The method of claim 1, wherein the forming of the insulating layer comprises: Forming a first insulating film on a surface of the silicon wafer; And, Forming a second insulating film on side surfaces of the plurality of chamber regions of the silicon wafer on which the insulating film is formed; and manufacturing a liquid lens using wafer level packaging. The method of claim 7, wherein forming the first insulating film, Liquid using wafer level packaging, which is formed by stacking any one of a thermal oxide film using a thermal oxidation process and a nitride film and a paraline film using CVD (Chemical Vapor Deposition), or two or more of the thermal oxide film, a nitride film and a paraline film Lens manufacturing method. The method of claim 7, wherein the first insulating film, By using a thermal oxidation method, a thermal oxide film was grown to a thickness of 1,000 to 3,000Å, and a nitride layer having a thickness of 0.3 to 1 μm was formed on the thermal oxide film by CVD. Liquid lens manufacturing method. The method of claim 7, wherein forming the second insulating film, Forming a protective film on the bottom of the silicon wafer, and forming a mask layer on the silicon wafer; Forming a hydrophobic insulating film on side surfaces of the plurality of chamber regions of the silicon wafer on which a protective film and a mask layer are formed; And Removing the protective film and the mask layer formed on the silicon wafer; liquid lens manufacturing method using a wafer level packaging comprising a. The method of claim 10, wherein forming the hydrophobic insulating film, A method of manufacturing a liquid lens using wafer level packaging, wherein the Teflon film is coated on one side of the plurality of chamber regions by any one of dipping, spraying, or spin coating. The method of claim 1, wherein the forming of the plurality of liquid lenses comprises: Bonding the lower glass wafer and the silicon wafer; Injecting an electrolyte solution into a plurality of chamber regions of the bonded silicon wafer, and injecting an insulating solution having a specific gravity equal to the upper surface of the silicon wafer without mixing with the electrolyte solution; And, Bonding the silicon wafer and the upper glass wafer into which an electrolyte solution and an insulating solution are injected; and manufacturing a liquid lens using wafer level packaging. The method of claim 12, wherein the bonding of the silicon wafer and the upper glass wafer comprises: Forming a bonding layer on the silicon wafer, and heat-treating the formed bonding layer at a temperature of 150 ~ 190 ℃ to bond the silicon wafer and the upper glass wafer, the liquid lens manufacturing method using a wafer level packaging. The method of claim 1, wherein the separating of the plurality of liquid lenses separately and exposing the electrode pad to the outside, Dicing the plurality of liquid lenses in a half-cutting form in which a portion of a silicon wafer remains for each liquid lens to define an electrode pad open region; Dicing the plurality of liquid lenses, each having an electrode pad open region defined therein, in individual units; And, And removing the electrode pad open region to expose the electrode pad on the lower glass wafer.

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