We investigated the optimal surface structure of an n-type Si substrate for Si-Al bonding (which prevents high-energy barrier formation) using simulation by the phase field method. The surface structure of the substrate contained a groove to suppress regrowth layer formation at the bottom of the groove. We determined the appropriate width and depth of the groove to effectively suppress the regrowth layer. The features of the regrowth layer suppression mechanism were clarified as the following: narrowing the groove caused the Al concentration to increase inside the groove and, in turn, decreased the degree of supercooling of the Si-Al liquid. However, when the groove was too narrow, the radius of curvature at the bottom of the groove decreased, and the equilibrium melting point of the Si-Al liquid rose due to the Gibbs–Thomson effect. On the other hand, the narrow groove increased the Al concentration, leading to decrease of the equilibrium melting point of the Si-Al liquid. This implies that there is always an optimum value for the width and the depth of the groove by which the regrowth layer is effectively suppressed through forming the groove in the Si surface for the Si-Al bonding process. Any groove morphology with the growth ratio (the ratio of the regrowth layer at the bottom to that at the top of the groove) less than 0.3 is appropriate to achieve good ohmic contact; however, it is considered that the groove with periodic length of 9.4 μm and aspect ratio around 0.2 is the best because of the ease of manufacturing.

我们研究了n的最佳表面结构使用相场法模拟的用于 Si-Al 键合（防止高能垒形成）的 型 Si 衬底。基板的表面结构包含凹槽以抑制凹槽底部的再生长层形成。我们确定了适当的凹槽宽度和深度，以有效抑制再生层。再生长层抑制机制的特征阐明如下：槽变窄导致槽内Al浓度增加，进而降低Si-Al液体的过冷度。然而，当凹槽过窄时，凹槽底部的曲率半径减小，由于 Gibbs-Thomson 效应，Si-Al 液体的平衡熔点升高。另一方面，窄槽增加了Al浓度，导致Si-Al液体的平衡熔点降低。这意味着槽的宽度和深度总是存在最佳值，通过在Si-Al键合工艺中在Si表面中形成槽可以有效地抑制再生长层。任何生长比（凹槽底部再生长层与顶部再生长层的比例）小于0.3的凹槽形态都适合实现良好的欧姆接触；然而，由于易于制造，认为周期长度为9.4μm且纵横比为0.2左右的凹槽是最好的。这意味着槽的宽度和深度总是存在最佳值，通过在Si-Al键合工艺中在Si表面中形成槽可以有效地抑制再生长层。任何生长比（凹槽底部再生长层与顶部再生长层的比例）小于0.3的凹槽形态都适合实现良好的欧姆接触；然而，由于易于制造，认为周期长度为9.4μm且纵横比为0.2左右的凹槽是最好的。这意味着槽的宽度和深度总是存在最佳值，通过在Si-Al键合工艺中在Si表面中形成槽可以有效地抑制再生长层。任何生长比（凹槽底部再生长层与顶部再生长层之比）小于0.3的凹槽形态都适合实现良好的欧姆接触；然而，由于易于制造，认为周期长度为9.4μm且纵横比为0.2左右的凹槽是最好的。3 以达到良好的欧姆接触为宜；然而，由于易于制造，认为周期长度为9.4μm且纵横比为0.2左右的凹槽是最好的。3 以达到良好的欧姆接触为宜；然而，由于易于制造，认为周期长度为9.4μm且纵横比为0.2左右的凹槽是最好的。