Monolithic 3D Integration With Photosensor and CMOS Circuits Using Ion-Cut Layer Transfer

A thin Si layer transfer process for monolithic 3D (M3D) integration is proposed using hydrogen ion (H+) implantation. The upper Si layer was transferred to CMOS circuits fabricated on the lower substrate by H+ implantation, oxide-to-oxide bonding, and a cleavage process at low temperature (< 500 degrees C). The M3D system comprising the photosensor connected to the CMOS device was demonstrated, where the thickness and roughness of the transferred Si layer were determined by H+ implantation and subsequent processes. The hetero-junctional photosensor was fabricated on the transferred Si layer, which generated the photocurrent (I-ph) by light exposure. The photosensor and ring oscillator circuits of the vertical structure implemented by the M3D process generated the I-ph according to the light exposure intensity and showed different frequency behaviors accordingly. Compared with the continuous device scaling approach, M3D may be an alternative scheme for low-power, high-performance, and multi-functional devices.

Automated summary

A thin Si layer transfer process for monolithic 3D (M3D) integration using H+ implantation is proposed, and the photosensor and ring oscillator circuits of the M3D system are demonstrated. Compared with the continuous device scaling approach, M3D may be an alternative scheme for low-power, high-performance, and multi-functional devices.