Optical bench on substrate

#The present disclosure relates generally to an integrated circuit.

#A multi-chip module package (MCM) integrates chips with different functions and made of different processes. Some MCMs utilize substrate materials based on ceramic or organic polymers, which, in certain configurations, may have insufficient coefficient of thermal expansion (CTE) matching to semiconductor chips and/or heat dissipation property. This causes potential reliability issues for III-V semiconductor material based optoelectronic chips and/or high power amplifiers.

#Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

#FIG. 1 is a schematic diagram of an optical bench on substrate according to some embodiments;

#FIGS. 2A-2E are schematic diagrams of various steps of fabrication process of the optical bench on substrate in FIG. 1 according to some embodiments; and

#The making and using of various embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use, and do not limit the scope of the disclosure.

#In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a feature on, connected to, and/or coupled to another feature in the present disclosure that follows may include embodiments in which the features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the features, such that the features may not be in direct contact. In addition, spatially relative terms, for example, “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top,” “bottom,” etc. as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) are used for ease of the present disclosure of one features relationship to another feature. The spatially relative terms are intended to cover different orientations of the device including the features.

#FIG. 1 is a schematic diagram of an optical bench 100 on substrate according to some embodiments. The optical bench 100 includes a laser diode land a photo diode 2 mounted on a substrate 3. The laser diode 1 and the photo diode 2 comprise III-V semiconductor materials and operate on electromagnetic wavelengths in the range of 450 nm-1700 nm in some embodiments. The substrate 3 can comprise any suitable material, such as silicon. An etching hard mask 4 comprises SiN or SiO2 and can achieve at least 30 □m etch depth in some embodiments. The etching hard mask layer 4 over the area for a trench 21 and/or an optical waveguide 19 is removed. In some examples, the etching hard mask layer 4 comprises SiN of at least 30 nm in thickness. In further examples, the etching hard mask layer 4 comprises SiO2 of at least 100 nm in thickness. A reflector layer 5 comprises at least one of Cu, Al, Ag, or Au, multi-layered dielectrics, or any other suitable material having a reflective property at desired electromagnetic wavelengths. In some embodiments, the reflector layer 5 has at least 90% reflectivity at selected wavelengths.