CN101493578B - Period-adjustable micro-mechanical grating and making technique thereof - Google Patents

Abstract

The invention discloses a micro-mechanical grating with tunable period and a preparation process thereof, belonging to the field of MOEMS devices. The grating is characterized in that a substrate is made of insulated transparent material such as glass, sapphire and the like. The preparation process comprises the steps as follows: a layer of metal film is deposited on the surface of the substrate; one side of the structural material is etched as an anchor point with a certain height; the substrate and the structural material are bonded to each other by the anchor point; furthermore, the structural material is thinned to the required thickness; and the structural material is etched and the formed structural layer part is released, thus forming the grating. As the substrate of the grating is completely transparent, when the incident light radiates on the grating, part of the incident light is reflected to generate a reflection-typed diffraction spectrum and the other part thereof reaches the front surface of the substrate through the clearance between the grating bars so as to generate projection, therefore, the grating can work in the reflection type and the transmission type simultaneously.

Description

A micro-mechanical grating with adjustable period and its manufacturing process

Field:

The invention belongs to the field of micro-opto-electro-mechanical (MOEMS) devices, and mainly relates to micro-electro-mechanical systems (MEMS) technology, grating technology, micro-processing technology and the like.

current technology:

Period-tunable micromachined grating is a kind of grating under the new concept, which is based on micro-electromechanical system (MEMS) and manufactured by micro-processing technology. Through the programming control of the grating driving circuit, the adjustment of the grating period is realized, so that the diffraction spectrum is shifted. Compared with traditional gratings, period-tunable micromechanical gratings have the characteristics of programmable control of diffracted light intensity, fast response, and mass production.

In recent years, with the continuous deepening of research on micro-mechanical grating technology, there have been many reports on the research of period-tunable micro-mechanical gratings. In 2001, Taiwan's Ching-liang Dai et al. used CMOS technology to produce a reflective period-tunable micromechanical grating (Sensor.Actuat.A, 2001, 95:69). The grating structure uses three layers of metal and two layers of silicon oxide materials Composite deposition is a structural layer, using silicon as a substrate, and the substrate silicon is opaque, so this grating can only work in reflection mode. In 2005, researchers at the University of Michigan used nanoimprint technology to process PDMS materials and fabricated a transmission-type period-tunable micromechanical grating (Appl. Phys. Lett., 2005, 86: 161113-1). The grid structure of the grating is obtained by directly scribing on the PDMS material. Since PDMS is a transparent polymer material, after the incident light is diffracted by the grating bars, the diffracted light is directly transmitted out. Due to the small stiffness of the PDMS material, when a tensile or compressive force is applied to the PDMS in the direction perpendicular to the grid bars, the PDMS will produce stretching deformation, which will drive the grid bars to move, thereby realizing the adjustment of the grating period. In 2007, based on the SOI process, the University of Tokyo developed a reflective period-tunable micromechanical grating (MEMS'2007, Jan.21-25, 2007, pp.147-150). It obtains a movable grating structure by etching the SOI silicon wafer structure layer and selectively removing the silicon dioxide layer. The substrate is also silicon material, so it can only work in the reflection mode. When a voltage is applied to every two adjacent grid bars of the grating, an electrostatic force will be generated between the grid bars to cause the grid bars to move and change the grating period.

However, the existing period-tunable micromechanical gratings can only work in reflection or transmission mode due to the constraints of technology and materials, which limits the application of gratings to a certain extent.

Invention content:

Purpose of the invention:

In order to overcome the shortcomings of the existing period-tunable micro-mechanical gratings that can only work in one of the reflection or transmission modes, and the application of the grating is limited, the present invention proposes a new type of period-tunable micro-mechanical grating and its manufacturing method. The period-tunable micromachined grating can work in reflection and transmission modes simultaneously.

Technical solutions:

Referring to Fig. 1, the period-tunable micromechanical grating proposed by the present invention is composed of a substrate and a structural layer, and the structural layer is suspended on the substrate through anchor points 3; the structural layer is made of silicon, gallium arsenide, etc. The conductive material combined, the structural layer includes a number of equidistant parallel grating bars 8, elastic support beams 9 and connecting beams 10, and every two adjacent grating bars 8 are connected by folding U-shaped connecting beams 10 on both sides, The two grating bars 8 at both ends are connected to the anchor point 3 through the elastic support beam 9, and the driver 7 is connected to the grating bar 8 at one end, driving the grating bar 8 to reciprocate along the direction perpendicular to the bar; The base is insulating transparent material, such as glass, sapphire, etc.; there are metal films on the base as electrodes and leads, so that the driver 7 is connected to the outside through the metal film, so as to supply power to the driver 7. The metal film is made of gold, aluminum and other materials.

Referring to Fig. 2, the method for fabricating a period-tunable micromechanical grating proposed by the present invention includes the following process steps:

Step 1: Deposit a layer of metal film 2 on the surface of substrate 1;

Step 2: Etching an anchor point 3 of a certain height on one side of the structural material;

Step 3: bonding the structures obtained in steps 1 and 2 together through anchor points 3, and thinning the structural material to the desired thickness;

Step 4: Etching the structural material and releasing the part forming the structural layer to form a micromechanical grating with an adjustable period.

Referring to FIG. 3 , during operation, the incident light 4 is incident on the micromechanical grating, a part of which is reflected by the grating bars 8 to generate a reflective diffraction spectrum 5; the other part of the incident light reaches the front of the substrate 1 through the gaps between the grating bars 8 Since the substrate 1 is completely transparent, a transmission diffraction spectrum 6 is formed on the rear surface of the substrate 1 . Under the smaller grating period, the reflective diffraction spectrum 5 and the transmission diffraction spectrum 6 of the incident light 4 shifted greatly by the period-tunable micromechanical grating; driven by the driver 7, the elastic support beam 9 and the connecting beam 10 are deformed , the grating bar 8 moves, the grating period becomes larger, and the period-adjustable micromechanical grating produces a small shift in the reflective diffraction spectrum 5 and the transmission diffraction spectrum 6 of the incident light 4 .

Beneficial effect:

The beneficial effects of the present invention are: the period-adjustable micromechanical grating can work in both reflection and transmission modes at the same time, and the change of the period of the grating can change the diffraction angle of the diffraction spectrum, so that the reflective diffracted light and the transmissive diffracted light can be redistributed in the surrounding space , thereby changing the light intensity distribution.

Description of drawings:

Figure 1. Schematic diagram of the period-tunable micromechanical grating proposed by the present invention

Figure 2. The process flow chart of the period-tunable micromachined grating production process proposed by the present invention

Figure 3. Schematic diagram of the working principle of the period-tunable micromachined grating proposed by the present invention

Figure 4. Schematic diagram of the period-tunable micromachined grating structure in Example 1

Among them: 1. Substrate; 2. Metal film; 3. Anchor point; 4. Incident light; 5. Reflective diffracted light output; 6. Transmissive diffracted light output; 7. Driver; 8. Grating bars; 9. Elasticity Supporting beam; 10. Connecting beam

Detailed ways:

Example 1:

Referring to FIG. 4 , the period-tunable micromechanical grating in this embodiment is composed of a substrate and a structural layer, and the structural layer is suspended on the substrate through anchor points 3 . The material of the structural layer is silicon, including 7 equidistant and parallel grating bars 8, 4 elastic support beams 9, and 12 connecting beams 10, and every two adjacent grating bars 8 are connected by folding U-shape on both sides The beams 10 are connected, and the two grating bars 8 at both ends are connected to the anchor point 3 through the elastic support beam 9. The driver 7 is driven by an electrostatic comb, connected with one end of the grating bar 8, and drives the grating bar 8 along the The grid bars reciprocate in the vertical direction. The base material is glass, on which a metal film made of gold is used as electrodes and leads, so that the driver 7 is connected to the outside through the metal film, so as to supply power to the driver 7 .

The manufacturing method of the period-tunable micromechanical grating in this embodiment, the process steps are as follows:

Step 1: Deposit a layer of gold on the surface of the substrate 1 as the metal film 2;

Step 2: etching an anchor point 3 with a height of 50 μm on one side of the silicon wafer;

Step 3: bonding the structures obtained in steps 1 and 2 together through anchor points 3, and thinning the silicon wafer to 20 μm;

Step 4: Etching the silicon wafer, releasing the part forming the structural layer, and forming a micromechanical grating with an adjustable period.

Example 2:

Referring to FIG. 4 , the period-tunable micromechanical grating in this embodiment is composed of a substrate and a structural layer, and the structural layer is suspended on the substrate through anchor points 3 . The material of the structural layer is gallium arsenide, including 7 equidistant and parallel grating bars 8, 4 elastic support beams 9, and 12 connecting beams 10, and every two adjacent grating bars 8 pass through the folding U on both sides. The two grating bars 8 at both ends are connected to the anchor point 3 through the elastic support beam 9. The driver 7 is driven by an electrostatic comb and connected to one end of the grating bar 8, driving the grating bar 8 along the It reciprocates in the direction perpendicular to the grid bar. The base material is sapphire, on which there is a metal film made of aluminum as electrodes and leads, so that the driver 7 is connected to the outside through the metal film, so as to supply power to the driver 7 .

The manufacturing method of the period-tunable micromechanical grating in this embodiment, the process steps are as follows:

Step 1: Deposit a layer of aluminum on the surface of the substrate 1 as the metal film 2;

Step 2: Etch an anchor point 3 with a height of 50 μm on one side of the gallium arsenide wafer;

Step 3: bonding the structures obtained in steps 1 and 2 together through anchor points 3, and thinning the silicon wafer to 30 μm;

Step 4: Etching the gallium arsenide wafer, releasing the part forming the structural layer, and forming a micromechanical grating with adjustable period.

Claims (6)

1. A period-tunable micromechanical grating, consisting of a substrate and a structural layer, the structural layer is suspended on the substrate through anchor points (3); the structural layer is a conductive material that can be etched and bonded, and the structural layer includes several etc. From the parallel grating bars (8), elastic support beams (9) and connecting beams (10), every two adjacent grating bars (8) are connected by folding U-shaped connecting beams (10) on both sides, The two grating bars (8) at both ends are connected to the anchor point (3) through elastic support beams (9), and the driver (7) is connected to the grating bar (8) at one end, driving the grating bar (8) along the Reciprocate in the direction perpendicular to the grid bars; there are metal films on the base as electrodes and leads, so that the driver (7) is connected to the outside through the metal film, so as to supply power to the driver (7). It is characterized in that: the base is insulating and transparent Material. 2. A period-tunable micromechanical grating as claimed in claim 1, characterized in that: said driver (7) is an electrostatic comb driver. 3. A period-tunable micromechanical grating as claimed in claim 1, characterized in that: said base material is glass or sapphire. 4. A period-tunable micromechanical grating as claimed in claim 1, characterized in that: said structural layer material is silicon or gallium arsenide. 5. A period-tunable micromechanical grating as claimed in claim 1, characterized in that: said metal thin film material is gold or aluminum. 6. A method for fabricating a period-tunable micromechanical grating as claimed in claim 1, comprising the following process steps: Step 1: Deposit a layer of metal film (2) on the surface of the insulating transparent material substrate (1); Step 2: Etching an anchor point (3) of a certain height on one side of the structural material; Step 3: bonding the structures obtained in steps 1 and 2 together through anchor points (3), and thinning the structural material to the desired thickness; Step 4: Etching and releasing the structural material to form the structural layer part to form a micro-mechanical grating with an adjustable period. The micro-mechanical grating with an adjustable period is composed of a substrate and a structural layer, and the structural layer is suspended by the anchor point (3). Placed on the substrate; the structural layer is a conductive material that can be etched and bonded, and the structural layer includes a number of equidistant parallel grating bars (8), elastic support beams (9) and connecting beams (10), each adjacent The two grating bars (8) are connected through the folded U-shaped connecting beams (10) on both sides, and the two grating bars (8) at both ends are connected to the anchor points (3) through elastic support beams (9). (7) Connect with the grating bar (8) at one end, and drive the grating bar (8) to reciprocate along the direction perpendicular to the bar; there is a metal film on the substrate as an electrode and a lead, so that the driver (7) passes through the metal film Connect with the outside world, thereby supplying power to the driver (7).

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