Conventional carbon dioxide sensors pose significant drawbacks such as large size and high power consumption. In recent years, with the development of semiconductor technology and materials, microelectromechanical systems (MEMS) technology has gradually become the focus of sensor research. In this study, a microelectromechanical system with an infrared light source chip structure for carbon dioxide sensors was designed and investigated. Silicon (Si) was used as the substrate, silicon dioxide (SiO2)–silicon nitride (Si3N4)–silicon dioxide (SiO2) was used as the support layer of the infrared light source, platinum (Pt), which has good ductility, was used as the heating resistor for the radiation area, and aluminum (Al) was used as the electrode. The support layer of the light source adopted a four-axis large rounded corner suspension structure, which significantly reduced the thermal conduction of heat from the radiation area to the substrate and provided better stability. Through finite element simulation analysis, the light source was characterized by low power consumption and a solid structure.