BACKGROUND

Technical Field

The disclosure relates to optical elements, and more particularly, to optical sensors and methods for forming the same.

Description of the Related Art

Optical elements of an optical sensor can include a light collimator, a beam splitter, a focus lens, and a linear sensor. The function of the light collimator is to collimate light to reduce power loss caused by light divergence. For example, the light collimator may be applied to optical sensors to increase the efficiency of fingerprint recognition devices.

The light collimator includes transparent pillars and a light-shielding layer surrounding the transparent pillars to achieve the effect of collimating light. When the transparent pillars are required to have a high aspect ratio due to design demands, the process capability limitation may easily cause the deformation and collapse of the transparent pillars, thereby affecting the yield of the optical sensors.

Although existing optical sensors have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects. In particular, increasing the aspect ratio of the light collimator still needs further improvement.

SUMMARY

Some embodiments of the present disclosure provide an optical sensor. The optical sensor includes pixels disposed in a substrate and a light collimating layer disposed on the substrate. The light collimating layer includes a transparent layer blanketly disposed on the substrate, covering the pixels and a region between the pixels; a light-shielding layer disposed over the transparent layer; and transparent pillars through the light-shielding layer, correspondingly disposed on the pixels.

Some embodiments of the present disclosure provide a method for forming an optical sensor. The method includes forming pixels in a substrate and forming a light collimating layer on the substrate. Forming the light collimating layer includes blanketly forming a transparent layer on the substrate, covering the pixels and a region between the pixels; forming transparent pillars on the transparent layer, wherein the transparent pillars are correspondingly disposed on the pixels; and planarizing upper surfaces of the transparent pillars and the light-shielding layer.

In order to make the purposes, features and advantages of the present disclosure easy to understand, a detailed description is given in the following embodiments with reference to the accompanying drawings.

