Small form factor camera module with lens barrel and image sensor
A camera module includes an image sensor substrate including image sensor circuitry, and a lens barrel. A lid structure includes a transparent window and is disposed between, and attached to, the lens barrel and the image sensor substrate. The lid structure may be fabricated as part of a wafer-level process.
1 . An apparatus comprising a camera module including:
an image sensor substrate including image sensor circuitry;
a lens barrel;
a substantially planar lid structure disposed between, and attached to, the lens barrel and the image sensor substrate, wherein the lid structure includes a transparent window located over image sensor circuitry on the substrate.
2 . The apparatus of claim 1 wherein the lid structure includes cut-out regions along its outer periphery, and the lens barrel includes alignment features that project into the cut-out regions of the lid structure toward the image sensor substrate.
3 . The apparatus of claim 1 including pairs of alignment features on a surface of the lid structure that engage corresponding projections on a lens in the lens barrel.
4 . The apparatus of claim 3 wherein the lens has integral projections that extend along sides of the lid structure and contact an upper surface of the image sensor substrate.
5 . The apparatus of claim 1 wherein the transparent window is surrounded along its periphery by a semiconductor frame integral with the transparent window.
6 . The apparatus of claim 5 wherein the semiconductor material comprises silicon.
7 . The apparatus of claim 5 wherein the transparent window comprises glass.
8 . The apparatus of claim 5 wherein respective surfaces of the semiconductor frame and the transparent window that face the lens barrel are in substantially the same plane as one another, and wherein respective surfaces of the semiconductor frame and the transparent window that face the image sensor are in substantially the same plane as one another.
9 . The apparatus of claim 1 wherein the transparent window is surrounded along its periphery by a metal frame integral with the transparent window.
10 . The apparatus of claim 9 wherein the transparent window comprises glass.
11 . The apparatus of claim 9 wherein respective surfaces of the metal frame and the transparent window that face the lens barrel are in substantially the same plane as one another, and wherein respective surfaces of the metal frame and the transparent window that face the image sensor are in substantially the same plane as one another.
12 . The apparatus of claim 1 wherein the camera module includes feed-through metallization that extends through the lid structure from a first surface of the lid structure that faces the image sensor substrate to a second surface of the lid structure that faces the lens barrel.
13 . The apparatus of claim 1 wherein a thickness of the lid structure is on the order of several hundred microns.
14 . A method of fabricating a camera module, the method comprising:
providing a substantially planar lid structure including a transparent window;
attaching a first surface of the lid structure to an image sensor substrate such that the transparent window is positioned over image sensor circuitry on the substrate and attaching a second surface of the lid structure to a lens barrel, such that the lid structure is disposed between the lens barrel and the image sensor substrate.
15 . The method of claim 14 wherein at least the following are performed in a wafer-level process:
forming the substantially planar lid structure; and
attaching the first surface of the lid structure to an image sensor substrate.
16 . The method of claim 15 wherein forming the substantially planar structure includes:
attaching a handling wafer to a first wafer from which the lid structure is to be formed;
reducing the thickness of the first wafer while the handling wafer is attached; and
subsequently removing the handling wafer.
17 . The method of claim 16 wherein the first wafer is glass.
18 . The method of claim 16 wherein the first wafer comprises areas of glass each of which is surrounded along its respective periphery by a semiconductor material.
19 . The method of claim 16 wherein the first wafer comprises areas of glass each of which is surrounded along its respective periphery by metal.
20 . The method of claim 17 wherein attaching a handling wafer includes attaching the handling wafer to the first wafer using a soluble adhesive.
21 . The method of claim 20 wherein the handling wafer includes holes aligned above openings in the first wafer, wherein removing the handling wafer includes providing a liquid through the holes to dissolve the adhesive.
22 . The method of claim 15 including separating the image sensor substrate into individual image sensor assemblies.
23 . The method of claim 14 wherein the lid structure includes cut-out regions along its outer periphery and wherein the lens barrel includes corresponding alignment features, wherein the method includes:
aligning the alignment features with corresponding ones of the cut-out regions.
24 . The method of claim 14 wherein providing the lid structure includes:
forming a cavity in a first side of a semiconductor wafer;
filling the cavity with a transparent material that bonds to the semiconductor wafer; and
removing semiconductor material and transparent material from the first side and an opposite second side so that a substantially planar structure is formed in which the transparent material is exposed on both sides and wherein a periphery of the transparent material is surrounded by semiconductor material.
25 . The method of claim 14 wherein providing the lid structure includes:
etching a cavity in a first side of a semiconductor wafer;
filling the cavity with a transparent material;
removing semiconductor material from a second side of the semiconductor material to reveal the transparent material.
26 . The method of claim 25 including causing the transparent material in the cavity to bond to the semiconductor wafer.
27 . The method of claim 25 further including:
removing transparent material from above a surface of the semiconductor wafer in which the cavity is formed.
28 . The method of claim 27 including using a double-sided etch to simultaneously form the cavity in the first side and openings in the second side.
29 . The method of claim 14 further including forming the lens barrel with an integral lens through a precision molding process.