CN106744659B - Research method based on laser controlling nanostructure silicon substrate surface form - Google Patents

Abstract

The invention discloses a research method for controlling the surface morphology of nanostructured silicon substrates based on laser: 1. Using materials with different thermal conductivity to contact the nanostructured silicon substrates respectively; 2. Laser irradiation on the surface of nanostructured silicon substrates; 3. Observing silicon The morphology of the substrate surface and the aspect ratio of the protrusions on the silicon substrate were measured. 4. Summarize the change law of the silicon-based surface morphology. The invention has the following characteristics: firstly, the nanostructure silicon base surface morphology is changed through the thermal conductivity of the contact material. Second, the nanostructured silicon substrate is irradiated with a laser, which is clean, environmentally friendly, and does not produce any pollution. Third, the time required to change the surface morphology of the nanostructured silicon base is short and the efficiency is high.

Description

Laser-Based Control of Surface Morphology of Nanostructured Silicon Substrates

technical field

The invention belongs to the technical field of nanostructure research, and in particular relates to a research method for controlling the surface morphology of nanostructured silicon substrates based on laser.

Background technique

Nanostructured silicon-based materials are new materials developed on the basis of silicon materials, and are playing an increasingly important role in the field of MEMS (micro-electromechanical systems). With the continuous development and improvement of MEMS (micro-electromechanical systems), the silicon-based surface morphology required on these micro-devices has become more and more complex and diverse.

At present, it has been possible to form silicon-based surface morphology on nanostructured silicon-based materials, but this technology is not yet mature, mainly in how to control the silicon-based surface morphology. For changing the silicon-based surface morphology on nanostructured silicon-based materials, the wet etching technology in the United States is currently more commonly used. The technology is to control the surface morphology of nanostructured silicon base through repeated wet etching. The defect of this technology is that the surface morphology of the silicon substrate etched for the first time will affect the surface morphology of the second etching, and the surface morphology of the silicon substrate etched for the second time will be distorted. Such a silicon substrate surface morphology is obviously not very good. ideal.

Contents of the invention

Based on the above-mentioned defects in the prior art, the present invention proposes a research method for controlling the surface morphology of nanostructured silicon based on laser.

The present invention takes following technical scheme:

The first technical solution:

The research method of controlling the surface morphology of nanostructured silicon base by laser can be carried out according to the following steps:

Step 1, using materials with different thermal conductivity to contact the nanostructured silicon substrate respectively;

Step 2, irradiating the surface of the nanostructured silicon substrate with laser light;

In step 3, the surface morphology of the silicon base can be observed under an AFM (atomic force microscope), and the aspect ratio of the corresponding protrusions on the silicon base surface can be measured.

Step 4, summarizing the change law of the surface morphology of the silicon substrate.

Preferably, materials with different thermal conductivity are selected: heat insulating material, same material, and heat conducting material.

Preferably, asbestos is selected as the heat insulating material, silicon is selected as the same material, and aluminum is selected as the heat conducting material.

The second technical scheme: a method for researching the surface morphology of nanostructured silicon substrates controlled by laser, which follows the steps below:

Step 1, using materials with different thermal conductivity to contact the surrounding area of the nanostructured silicon substrate;

Step 2, the laser irradiates the nanostructured silicon substrate;

Step 3, turn off the laser, and observe the silicon substrate irradiated by the laser; for example, put the silicon substrate irradiated by the laser under an AFM (atomic force microscope) for observation.

Step 4, measuring the surface morphology of the silicon substrate. For example, the modified silicon-based surface morphology is measured by AFM (atomic force microscopy).

Preferably, materials with different thermal conductivity are selected: heat insulating material, same material, and heat conducting material.

Preferably, the heat insulating material is asbestos, the same material is silicon, and the heat conducting material is aluminum.

Preferably, in step 1, contact the left and right sides of the silicon substrate with the heat insulating material, the heat conducting material and the heat insulating material, and use the heat insulating material, the same material, and the heat insulating material to contact the front and back of the silicon substrate.

Preferably, in step 2, the power of the laser is P=75mW, and the laser irradiation time is t=10s.

Preferably, in Step 3, the surface morphology of the silicon base presents a pyramid shape. For example, when observed under an AFM (atomic force microscope), the surface morphology of the silicon base presents a pyramid shape.

Preferably, in Step 4, the ratio of the largest diameter D to the shortest diameter W of the silicon-based surface is 0.74, and the maximum height H is 950 nm.

The present invention is based on the research method of laser controlling the surface morphology of nanostructured silicon base. Compared with the prior art, the present invention has the following characteristics:

One, the modification of nanostructured silicon-based surface morphology through the thermal conductivity of the contact material.

Second, the nanostructured silicon substrate is irradiated with a laser, which is clean, environmentally friendly, and does not produce any pollution.

Third, the time required to change the surface morphology of the nanostructured silicon base is short and the efficiency is high.

Description of drawings

1A-1C are simplified schematic diagrams of the surface morphology of silicon substrates in contact with materials with different thermal conductivity.

Fig. 2 is a schematic diagram of the relationship between the thermal conductivity of the contact material and the aspect ratio of the silicon-based surface morphology.

Fig. 3 is a schematic diagram showing the distribution of materials with different thermal conductivity around the silicon substrate.

Fig. 4 is a schematic diagram of the surface morphology of the pyramid-shaped silicon substrate after modification.

Detailed ways

In order to make the objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be noted that all the drawings are in a very simplified form and use inaccurate scales, and are only used for the purpose of conveniently and clearly illustrating the embodiments of the present invention. Preferred embodiment of the present invention is described in detail below:

At the beginning of the experiment, materials with different thermal conductivity were used to contact the right plane of the silicon substrate, and then the surface of the nanostructured silicon substrate was irradiated with laser light for 10 seconds. By comparing the contact materials with different thermal conductivity, the change law of the surface morphology of the silicon substrate was summarized. The specific experimental plans involved are as follows:

Example 1

Asbestos (thermal insulation material) is used to contact the right plane of the nanostructured silicon substrate, and the thermal conductivity of asbestos k ₁ =0 W/mK. Then adjust the power of the laser to P=75mW, and irradiate the surface of the silicon-based material for 10 seconds. After laser irradiation, the silicon substrate was placed under an optical magnifying instrument for observation. The result of observation is that there is a raised silicon-based surface morphology in the center of the silicon substrate, and the corresponding height H=900nm and maximum diameter D=5.15um are measured, and the corresponding aspect ratio is 0.175, as shown in Figure 1A.

Example 2

Silicon (same material) is used to contact the right plane of the nanostructured silicon substrate, and the thermal conductivity of silicon is k ₂ =150W/mK. Repeating the above operations, the corresponding height H=900nm and the largest diameter D=6.00um were measured, and the corresponding aspect ratio was 0.150, as shown in FIG. 1B .

Example 3

Aluminum (thermal conductive material) is used to contact the right plane of the nanostructured silicon substrate, and the thermal conductivity of aluminum is k ₃ =200W/mK. Repeat the above operations to measure the corresponding height H=900nm and maximum diameter D=6.85um, and the corresponding aspect ratio is 0.131, as shown in Figure 1C.

It can be seen from the above examples that when the thermal conductivity of the contact material gradually increases (the thermal conductivity of asbestos is the lowest, the thermal conductivity of silicon is medium, and the thermal conductivity of aluminum is the highest), the maximum height of the silicon-based surface morphology will not change. The maximum diameter D becomes larger and larger. According to the aspect ratio of maximum height H/maximum diameter D, it can be obtained that the aspect ratio of the silicon-based surface morphology is getting smaller and smaller.

The above is to study the aspect ratio of the surface morphology of the silicon substrate by contacting the silicon substrate with aluminum, silicon, and asbestos. Through the above experiments, it can be found that the greater the thermal conductivity of the contact material, the greater the maximum diameter D of the silicon-based surface morphology, and the smaller the corresponding aspect ratio.

The experiment can also use more materials with different thermal conductivity to study the aspect ratio of the silicon-based surface morphology, which will not be described in detail here. The relationship between the thermal conductivity of the contact material and the aspect ratio of the silicon-based surface morphology is finally drawn as shown in Figure 2 shown.

The surface morphology of the silicon substrate can be changed by using the above-mentioned experimental rules. The specific experimental operation is as follows:

In this experiment, three materials with different thermal conductivity, asbestos, silicon, and aluminum, were used to contact the surrounding silicon-based materials under laser irradiation. In order to facilitate the description of the experiment, it is first necessary to abstract the silicon-based material into a cuboid, and the six faces are respectively marked as front, back, left, right, top, and bottom. The contact method of the material is shown in Figure 3. The left and right surfaces are in contact with asbestos, aluminum, and asbestos at equal intervals, and the front and rear surfaces are in contact with asbestos, aluminum, and asbestos at equal intervals. The experimental operation steps are as follows:

Step 1: According to the contact method shown in Figure 3, materials with different thermal conductivity are used to contact the surroundings of the silicon substrate.

Step 2: adjust the power of the laser to P=75mW, and irradiate the silicon substrate with the laser for 10 seconds.

Step 3: Turn off the laser, and then observe the silicon-based material irradiated by the laser under an AFM (atomic force microscope), and obtain the silicon-based surface morphology as shown in FIG. 4 .

Step 4: Measure the surface morphology of the changed silicon substrate by AFM (atomic force microscope), the ratio of the largest diameter D to the shortest diameter W is 0.74, and the largest height H is 950nm.

The ratio of the largest diameter D to the shortest diameter W of 0.74 is roughly equal to the ratio of the thermal conductivity _k2 of silicon to the thermal conductivity _k3 of aluminum of 0.75, indicating that the thermal conductivity of the surrounding materials affects the silicon-based surface morphology on the surface of the silicon substrate.

This experiment has basically realized the change of the surface morphology of the silicon substrate, and the modified surface morphology of the silicon substrate is roughly close to a pyramid in size and shape. By matching materials with different thermal conductivity, the surface shape of the silicon base can be changed, not only can the surface shape of the silicon base show a pyramid shape, but other shapes are also possible, and the present invention will not elaborate here.

The above embodiments and the accompanying drawings are all simplified schematic diagrams for describing the present invention in detail. Those skilled in the art can make various formal modifications or changes to the above examples without departing from the essence of the present invention, and all fall within the protection scope of the present invention.

Claims (6)

1. based on the research method of laser controlling nanostructure silicon substrate surface form, it is characterized in that as follows：

One, the silicon substrate of the material nanostructure of different thermal conductivity is used respectively；The material selection of the different thermal conductivity is exhausted Hot material, same material, Heat Conduction Material；The heat-insulating material selects asbestos, same material to select silicon, Heat Conduction Material aluminium；

Two, the silicon substrate of laser irradiation of nano structure；

Three, silicon substrate surface form is observed, and measures the draw ratio of silicon substrate surface protrusion；

Four, the changing rule of silicon substrate surface form is summarized.

2. based on the research method of laser controlling nanostructure silicon substrate surface form, it is characterized in that as follows：

Step 1, with the silicon substrate surrounding of the material nanostructure of different thermal conductivity；The material of the different thermal conductivity selects With heat-insulating material, same material, Heat Conduction Material；The heat-insulating material selects asbestos, same material that silicon, Heat Conduction Material is selected to select Aluminium；

Step 2, laser are irradiated the silicon substrate of nanostructure；

Step 3 closes laser, observes the silicon substrate after laser irradiation；

Step 4 measures the configuration of surface of silicon substrate.

3. the research method as claimed in claim 2 based on laser controlling nanostructure silicon substrate surface form, it is characterized in that：Step One, the left and right face of silicon substrate is contacted with heat-insulating material, Heat Conduction Material and heat-insulating material, with heat-insulating material, same material, heat insulating material Material removes contact silicon substrate front-back.

4. the research method as claimed in claim 2 based on laser controlling nanostructure silicon substrate surface form, it is characterized in that：Step Two, power P=75mW of laser, laser irradiation time t=10s.

5. the research method as claimed in claim 2 based on laser controlling nanostructure silicon substrate surface form, it is characterized in that：Step Three, pyramid is presented in silicon substrate surface form.

6. the research method as claimed in claim 2 based on laser controlling nanostructure silicon substrate surface form, it is characterized in that：Step Four, silicon substrate surface maximum dimension D and the ratio of most short diameter W are 0.74, maximum height H=950nm.