Abstract: A solid-state imaging device into which is integrated an optical low pass filter serving as the transparent window thereof, this integrated structure simplifying the configuration of the imaging system, reducing its size and manufacturing cost. The optical low pass filter is configured of an optical phase grating low pass filter to obtain satisfactory frequency characteristics. The optical low pass filter is constructed in such a manner that a grating with a predetermined thickness, generating the phase shift of &phgr;, a grating whose thickness is twice the &phgr;-phase shift grating, generating the phase shift of 2&phgr;, and a grating portion generating the phase shift of 0 form a basic pattern, the basic pattern being periodically arranged.

Abstract: There is provided an optical low pass filter passing only a lower spatial frequency using a phase grating and the structure of the grating. The optical low pass filter utilizes the two-dimensionally arranged phase grating for the purpose of removing an image with a higher spatial frequency in an imaging system employing a semiconductor solid-state imaging device such as CCD image sensor or CMOS image sensor, The optical low pass filter which suppresses a spatial frequency component higher than a specific frequency and passes a component lower than the specific frequency in an imaging system sensing input images includes a grating generating the phase shift of 0, a grating generating the phase shift of &phgr;, arranged at the right and bottom of the 0-phase shift grating, and a grating generating the phase shift of 2&phgr;, arranged at the diagonal side of the 0-phase shift grating.

Abstract: There is a provided a method for fabricating a grating pattern, including the steps of: coating an SOG solution on a glass substrate by spin coating method; heat-treating the SOG thin film coated on the glass substrate, to form a silicon oxide layer; coating a photoresist on the silicon oxide layer and exposing the photoresist layer by masking process; developing the exposed photoresist layer and wet-etching the silicon oxide layer; and developing the photoresist layer used as a mask. According to the present invention, the grating pattern can be fabricated without etching the glass substrate, and high-quality products at a low cost is accomplished since the present invention does not require the expensive sputtering apparatus. Furthermore, the step-shape oxide layer pattern can be obtained through one-time wet etching since the multilevel oxide layer is easily formed.