Semiconductor Laser Induced Liquid Film Infiltration Etching Technique

A new method of laser assisted processing - semiconductor laser induced drop etching is proposed. Be different from other methods, the new method can remove the effect of crystal anisotropy effectively. More complicated figure could be made and the accuracy may be improved. Be compared with gas etching, the necessary processing condition may be obtained more easily, and the manipulation is easier. Be compared with dry ion etching, the semiconductor substrate isn't being damnified, the etching process may be controlled easily and the cost is lower. Be compared with ordinary laser assisted wet etching, the etched area can be controlled. So the laser assisted drop diffuse etching should have a wide potential application in micro-electronics, photoelectron, OEIC, and semiconductor processing technique could be supplemented by the method.The content of this dissertation is about laser assisted drop diffuse etching, and the primary result and innovation is followed:1) The process of drop diffuse has been observed, and the edge etching effect is analyzed.Affected by weight and strain of drop, in the surface of GaAs, the thickness is thin and the area is large. Because of the continuant diffusing process, the etched area diffuses continuously, but the edge of drop become thinner and the etching time become shorter, so the incompletive etching appears in the edge of drop. The phenomenon is described in the dissertation.2) Analysis of lateral etching characteristic and surface uniformity.The lateral etching effect and surface roughness have been analyzed. The landscape orientation etching is bad for making a hole, for restraining the effect, the roughness must be researched intensively. In the dissertation, GaAs is etched by multifarious etching solution, and after effect observing, the optimal solution fractional composition is presented. Using an infrared camera, the thermal image of etching drop in the GaAs has been obtained, and based on the corresponding TIP (thermal image processing), the roughness-variation rule of the GaAs surface was investigate.3) The fine hole has been done in the GaAs substrate using laser assisted drop diffuse etching.Think about the need of new science and technology and validating of laser assisted drop diffuse etching technics, a hole is made in the surface of GaAs with laser assisted drop diffuse etching. The reason of aberration is analyzed and means of amend is advanced.It's hard to make the hole because the light spot diffuses owing to radian of drop and the difference of reaction speed for crystal unisotropy. At first, considerable improvement of the etched figure had been demonstrated as a result of optimization of the thickness and area of drop. And then, it has been found that the quality of the etched hole may be influenced by the solution concentration. If the concentration of H₂O₂ is too high, the lateral etching will speed up and the hole contour will be distorted. If the concentration of H₂O₂ is too low, the reaction is very slow and no evident etching was observed. Based on the concentration optimization, high vertical to lateral ratio of etching speed has been obtained. Finally, the influence of the crystal unisotropy on the hole quality has been observed. The quality of the etched hole will be effected strongly by the reaction speed difference for different orientation , and eventually, elliptical hole, in stead of circular hole, will be shaped.. In this dissertation, unisotropic influence has been eliminated using laser chemistry liquid-phase two-step method, and high quality circular hole has been fabricated.The most important contributions are the elimination of anisotropic influence on the hole quality using "two-step" method, and the real-time observation of etched surface roughness with infrared thermal image and related analysis. As our knowledge, this is the first report about the innovation mentioned above.