Method for recording identification information on semiconductor chip, and imaging device
On a wafer coated with photosensitizing agent, plural shots of exposure are applied through a mask including a plurality of reticles each of which has a circuit pattern and a top surface identification information, while the mask and the wafer are relatively moved. Then the wafer is developed and etched to form convex or concave reticle numbers (top surface identification information) on a metal layer which is the uppermost part or a part close to the uppermost part of the wafer. The reticle numbers enables to distinguish each of reticles on the mask. Next, an under surface identification information is recorded on an under surface of the wafer by laser marking or another method. The under surface identification information enables to distinguish each of the shots of exposure.
1 . A method for recording identification information on semiconductor chips comprising:
a patterning process for making plural shots of exposure on a top surface of a wafer coated with photosensitizing agent, through a mask including a plurality of reticles each of which has a circuit pattern and a top surface identification information, and then developing said wafer to form said circuit patterns and said top surface identification information on a metal layer which is the uppermost part or a part close to the uppermost part of said wafer, said top surface identification information enabling to distinguish said semiconductor chips from each other on the basis of said reticles;
a marking process for recording an under surface identification information on an under surface of said wafer, said under surface identification information enabling to distinguish said semiconductor chips from each other on the basis of said shots; and
a dicing process for cutting said wafer into plural pieces of said semiconductor chips.
2 . A method for recording identification information on semiconductor chips claimed in claim 1 , wherein said under surface identification information is at least one of a product model number, a lot number, a wafer number and a shot position on said wafer.
3 . A method for recording identification information on semiconductor chips claimed in claim 1 , wherein each of said top surface identification information and said under surface identification information is letters, numerals, symbols or combinations of them.
4 . A method for recording identification information on semiconductor chips claimed in, claim 1 , wherein said under surface identification information is plural barcodes arranged along different directions.
5 . A method for recording identification information on semiconductor chips claimed in claim 1 , wherein said under surface identification information is recorded by a laser marking method.
6 . A method for recording identification information on semiconductor chips claimed in claim 1 , wherein said under surface identification information is recorded by an ink-jet method in which ink dots are ejected.
7 . A method for recording identification information on semiconductor chips claimed in claim 6 , wherein said ink has heat-resistance and water-resistance
8 . A method for recording identification information on semiconductor chips claimed in claim 1 , wherein said semiconductor chips are image sensor chips.
9 . A method for recording identification information on semiconductor chips claimed in claim 8 , wherein said image sensor chips are CCD type image sensor chips.
10 . A method for recording identification information on semiconductor chips claimed in claim 8 , wherein said image sensor chips are CMOS type image sensor chips.
11 . An imaging device comprising:
an image sensor chip having a top surface provided with a light receiving section and an under surface on which identification information is recorded;
a package body having a chip chamber on a top surface thereof, said chip chamber containing said image sensor chip;
an opening penetrating through between an under surface of said package body and a bottom surface of said chip chamber, said identification information being visible through said opening; and
a transparent cover for sealing said chip chamber.
12 . An imaging device claimed in claim 11 , wherein said opening is sealed with a transparent sealing plate.
13 . An imaging device claimed in claim 11 , wherein said opening is sealed by transparent UV curing resin which is poured into said opening and then fixed by UV radiation.
14 . An imaging device comprising:
an image sensor chip having a top surface provided with a light receiving section and an under surface on which identification information is recorded; and
a package containing said image sensor chip, and being formed of a transparent material, said identification information being visible through said material.
15 . An imaging device claimed in claim 14 , wherein said package comprising:
a package body having a chip chamber on a top surface thereof, said chip chamber containing said image sensor chip; and
a transparent cover for sealing said chip chamber.