Apparatus and method for inspecting substantially transparent electronic devices
An apparatus and a method for inspecting a substantially transparent semiconductor device are provided, where the method comprises the steps of holding the substantially transparent semiconductor device with a semiconductor device holder, and illuminating a surface of the semiconductor device held by the semiconductor device holder from multiple directions with an enveloping light source. Thereafter, capturing a first image of the semiconductor device with an imaging module from the light projected from the enveloping light source, the first image revealing a direction of grinding marks on the said surface of the transparent semiconductor device. Then, relatively aligning the semiconductor device and an adjustable light source based on the direction of the grinding marks, and projecting light from the adjustable light source onto the surface of the semiconductor device at an oblique angle relative to the surface of the semiconductor device in a projection direction, such projection direction being substantially perpendicular to the direction of the grinding marks.
1. A method for inspecting a substantially transparent semiconductor device, the method comprising the steps of:
holding the substantially transparent semiconductor device with a semiconductor device holder;
illuminating a surface of the semiconductor device held by the semiconductor device holder from multiple directions with an enveloping light source;
capturing a first image of the semiconductor device with an imaging module from the light projected from the enveloping light source, the first image revealing a direction of grinding marks on the said surface of the transparent semiconductor device;
relatively aligning the semiconductor device and an adjustable light source based on the direction of the grinding marks; and
projecting light from the adjustable light source onto the surface of the semiconductor device at an oblique angle relative to the surface of the semiconductor device in a projection direction from at least one side of the semiconductor device, such projection direction being substantially perpendicular to the direction of the grinding marks.
2. The method of claim 1 , wherein the enveloping light source is positioned to encircle a perimeter of the semiconductor device.
3. The method of claim 1 , wherein the adjustable light source is positioned outside a perimeter of the semiconductor device.
4. The method of claim 1 , wherein the step of projecting light from the adjustable light source comprises the step of projecting light from opposite sides of the semiconductor device in opposing projection directions, the opposing projection directions both being substantially perpendicular to the direction of the grinding marks.
5. The method of claim 1 , wherein the step of projecting light from the adjustable light source comprises the step of projecting light along planar directions which are substantially perpendicular to the direction of the grinding marks.
6. The method of claim 1 , wherein after the step of capturing the first image, moving the semiconductor device from a location of the enveloping light source to a location of the adjustable light source for capturing a second image.
7. The method of claim 1 , wherein the enveloping light source comprises a ring light source.
8. The method of claim 1 , wherein the adjustable light source comprises at least one LED.
9. The method of claim 1 , wherein the step of relatively aligning the semiconductor device and the adjustable light source based on the direction of the grinding marks comprises the step of moving a movable cover with at least one opening until the at least one opening is aligned with the projection direction, and light is projected from the adjustable light source through the at least one opening onto the semiconductor device in the projection direction which is substantially perpendicular to the direction of the grinding marks.
10. The method of claim 1 , wherein the step of relatively aligning the semiconductor device and the adjustable light source further comprises the step of rotating a ring structure on which a fixed light source is mounted for positioning the fixed light source relative to the semiconductor device.
11. The method of claim 10 , wherein the step of rotating the ring structure comprises the step of rotating the ring structure about an axis perpendicular to the said surface of the semiconductor device.
12. An apparatus for inspecting a substantially transparent semiconductor device, the apparatus comprising:
a semiconductor device holder for holding the substantially transparent semiconductor device;
an enveloping light source sized and configured to project light from multiple directions onto a surface of the semiconductor device;
an imaging module positioned to receive the light projected from the enveloping light source to capture an image revealing a direction of grinding marks on the said surface of the semiconductor device;
an adjustable light source positionable to project light onto the said surface of the semiconductor device at an oblique angle relative to the surface of the semiconductor device in a projection direction from at least one side of the semiconductor device, such projection direction being substantially perpendicular to the direction of the grinding marks; and
an alignment mechanism operative to align the adjustable light source relative to the semiconductor device based on the direction of the grinding marks.
13. The apparatus of claim 12 , wherein the enveloping light source is positioned to encircle a perimeter of the semiconductor device.
14. The apparatus of claim 12 , wherein the adjustable light source is positioned outside a perimeter of the semiconductor device.
15. The apparatus of claim 12 , wherein the adjustable light source is operative to project light from opposite sides of the semiconductor device in opposing projection directions, the opposing projection directions both being substantially perpendicular to the direction of the grinding marks.