Method for preparing GaAs micro/nono optical element

[0035] Example 1

[0036] figure 1 A schematic diagram of the processing technology of Example 1 of the present invention is given.

[0037] figure 1 a is the hot embossing process, the polymer material is PMMA 2 (polymethyl methacrylate) and the quartz optical element master 1 is placed in the hot embossing device, the selected glass transition temperature (T g ) temperature is 100°C. PMMA 2 has a thickness of 1mm and an area of ​​2cm 2 ,use figure 2 The shown hot embossing device is heated up to the glass transition temperature (T g ) above (generally controlled at 135°C), and then apply a pressure of 4 to 10 MPa for replication.

[0038] figure 1 B is the demoulding and separation process after hot pressing replication. After the hot pressed PMMA sheet 2 is separated from the quartz optical element master plate 1, the PMMA sheet 2 also needs to be degreased. 3 PO 4 50g/L+Na 2 CO 3 25g/L+NaOH 20g/L for degreasing treatment, the deoiling temperature is 85°C, and the time is 2.5h.

[0039] figure 1 C is that the Ti layer and the Pt layer of 20nm can form Ti/Pt metal layer 3 by sputtering thickness successively on the PMMA sheet 4 after oil removal by magnetron sputtering coating technology, respectively, and the Pt layer of 20nm, makes its surface metallization, obtains PMMA/Ti/Pt machining tools. The sputtering conditions are as follows: sputtering Ti: argon flow rate 50, sputtering current 0.1A, power 35W, rotation speed 0.5rpm/s, time 6.5min; sputtering Pt: argon flow rate 64, sputtering current 0.1A, The power is 40W, the rotation speed is 0.5rpm/s, and the sputtering time is 3.5-4min.

[0040] figure 1 During the etching process shown in d, the driving device constantly adjusts the distance between the processing tool and the workpiece to be processed. Applying a certain potential on the PMMA/Ti/Pt processing tool can generate a thin layer of confined etchant layer 5, which is tightly wrapped on the surface of the template electrode. As the workpiece continues to approach the template electrode, the fine structure on the template electrode can be completely It is replicated on the surface of GaAs sheet 6 to be processed. During the etching process, as the workpiece is etched, the contact force value detected by the drive device between the workpiece and the tool will decrease. The detection of this force value can be detected through the drive device part of the patent 03101271.X. The workpiece is continuously fed through the driving device to ensure the pressure between the workpiece and the tool (6mN/mm 2 )constant. Quartz optical element master is an array composed of micro-optical elements on quartz, which is a quartz device with certain optical functions. In this patent, it specifically refers to the structure of an array of 8-phase microlenses, each microlens is composed of 7 steps and 8 concentric circles, and this structure can be used as a master for the thermal embossing step. PMMA is polymethyl methacrylate. Constrained etchant layer 5 means that the etchant produced on the electrode surface by the electrochemical reaction cannot diffuse to the depth of the solution under the action of the constraint agent in the solution, so that the thickness of the etchant layer generated on the electrode surface can be controlled at several tens of nanometers to several microns. The Ti/Pt metal layer is sputtered on the PMMA surface by magnetron sputtering, and n-GaAs is the processed workpiece.

[0041] figure 1 e corresponds to that after the etching process is completed, the template electrode leaves the workpiece GaAs sheet 6, and the GaAs surface obtains a pattern complementary to the microstructure on the template electrode.

[0042] figure 2 A schematic structural diagram of the thermal embossing device in Example 1 is given. The PMMA 2 is in close contact with the master plate 1 of the quartz optical element, and is between the smooth quartz plate 9 and the interlayer of the rubber layer 8 . The pressure control device 7 can control the pressure in the hot embossing process, generally controlled at 4-10 MPa. The temperature control device 10 can adjust its experimental temperature to be controlled at 135°C. The rubber layer 8 acts as a buffer to avoid damage to the master plate 1 of the quartz optical element during the thermal embossing process. The smooth quartz plate 9 is used to ensure the parallelism of the PMMA 2 and the quartz optical element master 1 during the duplication process.

[0043] image 3 It is a structural schematic diagram of the device for adjusting the parallelism between the processing tool and the n-GaAs slice of the processed workpiece according to Embodiment 1 of the present invention. First, the polished surface of the n-GaAs sheet 6 (area 4mm×4mm) to be processed is placed on the surface of the processing tool without pressure, and the two are kept in natural parallel contact. A small amount of uncured epoxy resin 13 is coated on the back of the n-GaAs sheet, and then the stainless steel cylinder 12 is gradually approached by the driving device 11 to the back of the n-GaAs sheet 6. When contact occurs, due to the effect of pressure, the PMMA/Ti/Pt The template electrode 14 is always in parallel contact with the n-GaAs sheet 6, and the n-GaAs sheet 6 is bonded to the top of the stainless steel column 12 after the epoxy resin is cured. At this time, the stainless steel column 12 is controlled by the driving device 11 (refer to patent CN03101271.X, consisting of two parts: macro motion and micro motion) to leave a certain distance (about 50-250 nm) from the surface of the processing tool, and the two have good parallelism. The stainless steel post 12 plays a fixed role. PMMA/Ti/Pt processing tool 14 is through figure 1 The steps a to c are prepared, and the n-GaAs sheet 6 is a processing workpiece. The role of the epoxy resin 13 is to adjust the parallelism during the curing process, and then play a role of fixing and supporting.

[0044] Figure 4 The microstructure on PMMA prepared by hot embossing technology for Example 1 of the present invention is complementary to the microstructure on the quartz optical element template.

[0045] Figure 5 Microphotographs of arrays of micro/nano optical elements fabricated on n-GaAs surface. The composition of etching solution used in processing is 9.96×10 -2 mol/L HBr+9.96×10 -2 mol/L L-cystine+0.5mol/L H 2 SO 4 , the etching potential is 1.0V vs SCE (saturated calomel electrode), the etching processing time is 60min, and the driving device in the processing process can keep the contact pressure between the tool and the workpiece at 6mN/mm2. In this process, HBr provides Br - , and can generate Br on the surface of the processing tool through electrochemical oxidation reaction 2 , the latter can etch n-GaAs, and L-cystine acts as a constraining agent, which can quickly interact with the generated Br 2 elemental reaction, significantly limiting the Br 2 Diffusion of the elemental substance into the bulk of the solution can thus greatly reduce the thickness of the etchant layer.

[0046] Example 2-6

[0047] The specific operation steps of Examples 2-6 are the same as those of Example 1, and the specific composition of the solution is shown in Table 1, wherein the etching effect "+" is good.

[0048] Table 1

[0049] Example