阅读说明：本技术 一种Ni柱子辅助PMMA微透镜阵列及其制备方法 (Ni column-assisted PMMA (polymethyl methacrylate) microlens array and preparation method thereof ) 是由 梁小筱 伊福廷 刘静 王波 张天冲 颜铭铭 徐源泽 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种Ni柱子辅助PMMA微透镜阵列及其制备方法。本方法为：1)在镀铬金的硅片上电镀Ni柱子阵列；2)在电镀有Ni柱子阵列的所述硅片上旋涂一层液态PMMA后进行烘干处理；3)运用套刻技术,将X射线掩膜版与所述硅片上的Ni柱子对准,然后进行曝光、显影后得到具有PMMA柱子阵列的样品,其中所述PMMA柱子阵列中每一PMMA柱子内部包含一Ni柱子；4)将步骤3)所得样品放入烘箱中加热,使得所述PMMA柱子阵列中的各PMMA柱子热熔为微透镜,得到微透镜阵列。本发明通过在PMMA柱子中加入Ni柱子,达到的增加微透镜接触角的效果,进而能够制备接触角较大的微透镜阵列。(The invention discloses a Ni pillar-assisted PMMA (polymethyl methacrylate) micro-lens array and a preparation method thereof. The method comprises the following steps: 1) electroplating a Ni column array on a silicon wafer plated with chrome gold; 2) spin-coating a layer of liquid PMMA on the silicon wafer electroplated with the Ni column array, and then drying; 3) aligning an X-ray mask plate with the Ni columns on the silicon wafer by using an alignment technology, and then carrying out exposure and development to obtain a sample with a PMMA column array, wherein each PMMA column in the PMMA column array comprises a Ni column; 4) putting the sample obtained in the step 3) into an oven for heating, and carrying out hot melting on each PMMA column in the PMMA column array to obtain the microlens array. According to the invention, the Ni column is added into the PMMA column, so that the effect of increasing the contact angle of the micro lens is achieved, and the micro lens array with a larger contact angle can be prepared.)

1. A preparation method of a Ni pillar-assisted PMMA micro lens array comprises the following steps:

1) electroplating a Ni column array on a silicon wafer plated with chrome gold;

2) spin-coating a layer of liquid PMMA on the silicon wafer electroplated with the Ni column array, and then drying;

3) aligning an X-ray mask plate with the Ni columns on the silicon wafer by using an alignment technology, and then carrying out exposure and development to obtain a sample with a PMMA column array, wherein each PMMA column in the PMMA column array comprises a Ni column;

4) putting the sample obtained in the step 3) into an oven for heating, and carrying out hot melting on each PMMA column in the PMMA column array to obtain the microlens array.

2. The method of claim 1, wherein the Ni pillars have a diameter of 180 μm and a height of 7 to 10 μm.

3. The method of claim 2, wherein the PMMA columns have a diameter of 245 μm and a height of 104 μm.

4. A method as claimed in claim 1, 2 or 3, wherein in step 2), the sample spin-coated with a layer of liquid PMMA is placed on a hot plate at 95 ℃ and heated for 2 hours to dry the liquid PMMA.

5. The method of claim 1, 2 or 3, wherein in step 4), the sample is placed in an oven for heating, the hot-melt temperature is 240 ℃ and the hot-melt time is 30 minutes.

6. The Ni pillar-assisted PMMA microlens array is characterized by comprising a plurality of microlenses formed by hot melting PMMA pillars, wherein each microlens internally comprises a Ni pillar.

7. The Ni pillar-assisted PMMA microlens array of claim 6 wherein the Ni pillars have a diameter of 180 μm and a height of 7 to 10 μm.

Technical Field

The invention belongs to the technical field of micromachining, and relates to a Ni pillar-assisted PMMA (polymethyl methacrylate) microlens array and a preparation method thereof, which can be used for improving the contact angle of the microlens array.

Background

Microlens arrays are formed by arranging individual lenses in an array as micro-optical elements, and have a wide range of applications, such as optical communication, integrated imaging, fiber coupling, optical field display technology, and the like. The method for manufacturing the microlens array includes a photo-etching hot melting method, a hot press molding method, a micro-jet printing method, a femtosecond laser direct writing method and the like. The photoetching hot melting method is widely adopted because the process is relatively simple, the requirements on materials and equipment are not high, and the process parameters are stable and easy to control.

LIGA (LIGA is the acronym for lithography, electroforming and injection molding, which are three terms in lithograph, Galvanoformung and abormung, germany) technology is an MEMS processing technology based on X-ray lithography technology, mainly comprising three process steps of X-ray deep synchrotron radiation lithography, electroforming and injection molding replication. Because the X-ray has very high parallelism, extremely strong radiation intensity and continuous spectrum, the LIGA technology has advantages in manufacturing three-dimensional structures with large height-width ratio, smooth side walls and parallelism deviation in a submicron range. This is not possible with other micromachining techniques. And PMMA (organic glass) is a conventional photoresist for X-ray synchrotron radiation in the LIGA technology, and has the advantages of high transparency, low price, easy machining and the like.

The traditional method for manufacturing the micro-lens array is to manufacture the micro-lens array by a photoetching hot melt method and a LIGA technology, generally, a columnar micro-lens array is manufactured firstly and then is put into a constant temperature chamber for heating, when the heating temperature is higher than the vitrification temperature of PMMA, the PMMA column can gradually form a sphere under the action of surface tension, and after the constant temperature is kept for a period of time, a sample is naturally cooled and taken out, so that the micro-lens array can be obtained. The conventional method cannot further improve the lens contact angle.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a Ni pillar-assisted PMMA micro lens array and a preparation method thereof. The invention combines the LIGA technology with the photoresist hot melting method, and adds a Ni column into a PMMA micro column through the alignment technology, so that the contact angle of the obtained micro lens is larger than that of the micro lens without the Ni column. The addition of the Ni pillars plays a role in increasing the contact angle of the micro-lenses, so that a micro-lens array with a larger contact angle can be prepared.

According to the invention, the Ni column is added into the PMMA column, so that the effect of increasing the contact angle of the micro lens is achieved, and the micro lens array with a larger contact angle can be prepared.

The technical scheme adopted by the invention for solving the technical problems is as follows:

1. spin-coating a layer of AZ4620 photoresist, drying, and exposing and developing.

2. An array of Ni pillars, each having a diameter of 180 μm and a height of 7 to 10 μm, was electroplated on the gold-plated silicon wafer.

3. And spin-coating a layer of liquid PMMA on the Ni-electroplated column array sample and drying.

4. Aligning an X-ray mask plate with a Ni column of the sample by using an alignment technology, and performing deep synchrotron radiation photoetching and development to obtain the sample with the Ni column positioned in the middle of the PMMA column. The PMMA columns had a diameter of 245 μm and a height of 104 μm.

5. And putting the sample into an oven to be heated to obtain the micro lens array.

The invention has the following innovation points:

1. the use of Ni pillars can alter the topography of the lenses in the microlens array.

2. The Ni pillars cause the lens contact angle of the microlens array to increase.

The invention has the following advantages:

1. compared with a surface modification method for changing the size of the contact angle of the lens, the method is simple to operate and high in controllability.

2. The addition of the Ni column can prepare the photoresist column with a larger height-width ratio, and further exerts the advantages of the LIGA technology.

Drawings

FIG. 1 is a flow chart of the present invention.

FIG. 2 is a graph of experimental results;

(a) the PMMA column has a hot melting result diagram of the Ni column,

(b) thermal melting results of Ni-free columns in PMMA columns.

Detailed Description

The invention will be described in further detail with reference to the following drawings, which are given by way of example only for the purpose of illustrating the invention and are not intended to limit the scope of the invention.

The preparation method of the invention has the flow shown in figure 1, and comprises the following steps:

1. and spin-coating a layer of photoresist with the thickness of 10 mu m on a 2-inch chrome-plated gold silicon wafer. Obtaining a mould for electroplating the Ni column after the ultraviolet exposure and development are finished; and (3) putting the sample into a Ni electroplating pool for electroplating, setting the electroplating current to be 0.03A, using a photoresist removing solution to remove the AZ4620 photoresist after the electroplating time is 45 minutes, and cleaning and airing to obtain the sample with the Ni column array. Wherein the Ni column size is 7 to 10 μm and the diameter is 180 μm.

2. The electroplated sample is put into a degumming solution to remove the photoresist, and a Ni column (without large requirement, the interval can not cause adhesion phenomenon, and the quantity has no requirement) can be obtained, the height is 7-10 μm, and the diameter is 180 μm.

3. And spin-coating a layer of liquid PMMA on the sample electroplated with the Ni column, putting the sample on a hot plate at the temperature of 95 ℃, and heating for 2 hours to dry the liquid PMMA.

4. Aligning the Ni column with the pattern on the X-ray mask (the pattern on the mask is a template for obtaining the sample with the Ni column in the middle of the PMMA column, the pattern area of the X-ray mask, i.e. the circular array, is opaque, the PMMA is positive glue, and the opaque part is not shown by the developing solution) by the alignment technology of the sample, and then exposing by the X-ray.

5. And developing and airing the exposed sample to obtain a PMMA column array, wherein the height is 104 micrometers, the diameter is 240 micrometers, the PMMA column array is placed in an oven to be hot-melted into a micro lens, the hot melting temperature is 240 ℃, the hot melting time is 30 minutes, and the micro lens array with the micro lens contact angle increased through the Ni column can be obtained.

6. The comparative experiment sample, as shown in FIG. 2, wherein the sample preparation process without Ni column is similar to that with Ni column, the step of preparing Ni column is eliminated. The PMMA column without Ni column had a height of 109 μm and a diameter of 235 μm.

Although specific embodiments of the invention have been disclosed for purposes of illustration, and for purposes of aiding in the understanding of the contents of the invention and its implementation, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.