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MARKING SYSTEM FOR WAFER LOCATION IDENTIFICATION IN A THERMAL INK JET PRINTHEAD

IP.com Disclosure Number: IPCOM000027503D
Original Publication Date: 1997-Jun-30
Included in the Prior Art Database: 2004-Apr-08
Document File: 4 page(s) / 181K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is a method of coding thermal ink jet die for identification. The method uses etched features visible from the edge of a bonded and diced silicon printhead structure. Orientation Dependent Etch (ODE) channels form binary-coded information that appear as small triangles at the edge of the die. The coding allows for nondestructive identification of the die configuration or wafer location. Such identification simplifies the assembly of developmental devices and provides access to additional information for process control.

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XEROX DISCLOSURE JOURNAL

MARKING SYSTEM FOR WAFER LOCATION IDENTIFICATION IN A THERMAL INK JET PRINTHEAD Eduardo M. Freire
Virgil J. Hull

Proposed Classification
U. S. C1.347/020 Int. C1. B41j 02/015

c;

2= 2l 2O

10 12 14

f 20 2l 22 23 I 24 1 25

72

2

...... k72 6

FIG. 2

FIG. 3

A

............ .......... ........

721

".... ....... 72n

A

................. .~.:.:.:.~..
...........
..:.:.:.:

.,.,

..:.:"..

.:.y..:.:.:.: :::::. ::.:.:.:.:.:.:.:.

...........

FIG. 4

XEROX DISCLOSURE JOURNAL - Vol. 22, No. 3 May/June 1997 127

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MARKING SYSTEM FOR WAFER LOCATION IDENTIFICATION IN A THERMAL INK JET PRINTHEAD (CONT'D)

Proposed is a method of coding thermal ink jet die for identification. The method uses etched features visible from the edge of a bonded and diced silicon printhead structure. Orientation Dependent Etch (ODE) channels form binary-coded information that appear as small triangles at the edge of the die. The coding allows for nondestructive identification of the die configuration or wafer location. Such identification simplifies the assembly of developmental devices and provides access to additional information for process control.

Thermal ink jet printheads are fabricated using orientation-dependent etching of the channels. This creates triangular cross channels whose width is controlled by the etch mask and whose profile is determined by the { 11 1 } planes of the silicon substrate. When the die is diced and packaged, only the triangular shape of the channels is visible from outside the printhead.

For a 300 spot per inch head, the channels are typically 50 to 70 pm wide on 83.5 pm centers. Much smaller channels can be viewed microscopically and are currently used as markers for the front channel length. The proposed marking system encodes configuration or die location information in a binary form by placing small dummy channels (5 to 5 pm wide) in the vicinity of at least one end of an array of nozzles. Figures 1 and 2 illustrate an example where wafer column and row number are encoded for Column 5, Row 19. Figures 1 and 2 represent the same dummy channels. Figure 1 is a top view and Figure 2 is a front face view. Referring to Figure 1, there is shown a plurality of etched channels 12 and non-etched channels 14 on both sides of a reference channel 10. The channels 10, 12, and 14 are approximately 40 pm in length, as indicated by dimension B, and spaced at 15 pm intervals shown by dimension A. The etched channels 12 and non-etched channels 14 to the left of reference channel 10 encode the channel bits. A respective binary weight
(i.e., 2', 2l, and 2') is shown above each channel 12 and 14 for illustrative purposes. One skilled in the art will appreciate that non-etched channels 14 represent absences of etched channels 12. Thus, in Figure 2, the weights of the column bits to the left of reference channel 10 are:

Column bits = (1 x 2') + (1 x 2') = 4 + 1 = 5

In a simila...