High density wafer production method

Details High density wafer production method High density wafer production method

2002-02-04

2004-02-17

Powell, William A. (Department: 1765)

Semiconductor device manufacturing: process

Chemical etching

Liquid phase etching

C216S027000, C216S056000, C216S100000, C438S751000, C438S754000, C438S756000, C438S757000

Reexamination Certificate

active

06693045

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a wafer production method used in an etching process of a substrate, and more particularly, to a high density wafer production method for controlling a thickness of the wafer.
2. Description of the Prior Art
Silicon substrates are presently widely used in integrated circuits, optical electronics, microelectronics and microelectromechanical systems (MEMS). However, silicon substrates have shortcomings in many applications. For example, silicon substrates are crystal materials with crystal directions. Anisotropic etching processes are performed on silicon substrates by using a potassium hydroxide (KOH) solution. The etching speed of silicon in the direction <100> and <110> is far faster than that in the direction of <111 > for forming an inclined plan with 54.74°, creating a large waste of space. The waste of space becomes more serious with an increasing thickness of the silicon substrate.
Please refer to FIGS.
1
through
FIG. 3
, which are diagrams of print head structures of the prior art.
FIG. 1
is disclosed in U.S. Pat. No. 6,019,907 “Forming refill for monolithic inkjet printhead”. As shown in
FIG. 1
, the prior art inkjet printhead is formed on a silicon substrate
10
comprising two slots
11
,
12
for passing ink, two nozzle chambers
14
,
15
located on the surface of slots
11
,
12
for jetting the ink, and two resistors
16
,
17
. The resistor
16
is located between the nozzle chamber
14
and the slot
11
, and the resistor
17
is located between the nozzle chamber
15
and the slot
12
for heating the ink. The slots
11
,
12
form a refilling chamber
13
for decreasing the turbulent effect.
FIG. 2
is disclosed in U.S. Pat. No. 5,658,471 “Fabrication of thermal ink-jet feed slots in a silicon substrate.” As shown in
FIG. 2
, the prior art inkjet printhead is formed on a silicon substrate
20
comprising slot
21
formed in the center of the substrate
20
for passing the ink, a dielectric layer
22
formed on the surface of the substrate
20
, and two heaters
23
,
24
formed on the surface of the dielectric layer
22
for heating the ink. The dielectric layer
22
isolates the substrate
22
from the heaters
23
,
24
. The structures shown in FIG.
1
and
FIG. 2
are different, but they are manufactured by similar processes, and both waste space.
Please refer to
FIG. 3
, which shows a prior art inkjet printhead formed on a silicon substrate. As shown in
FIG. 3
, a standard cleaning process is performed on a silicon substrate with a width W
1
and a thickness T
1
. A passivation layer
31
and a patterned passivation layer
32
P are formed on a top surface and a bottom surface of a silicon substrate
30
for forming the surface patterns of slots
33
,
34
. A distance between the slot
33
and the slot
34
is L
1
and a distance between slots
33
,
34
and the wafer edge is L
0
. An etching process is performed on the silicon substrate by using potassium hydroxide (KOH) solution to form the structure of the slots
33
,
34
, as shown in FIG.
3
. The passivation layers
31
,
32
P are composed of silicon oxide or silicon nitride.
The process of
FIG. 3
applied in FIG.
1
and
FIG. 2
for producing the inkjet printhead forms an inclined plane at 54.74°, creating a large waste of space. Additionally, the substrate needs sufficient space in L
0
and L
1
(as shown in
FIG. 3
) to glue an ink box (not shown). An inclined plane formed at 54.74°, and the space required for gluing the box lead to the creation of a large waste of space.
SUMMARY OF INVENTION
It is therefore a primary objective of the present invention to provide a method of high density wafer production that saves space.
Briefly, the claimed invention provides an etching method for high density wafer production used when etching a substrate for controlling a thickness of the wafer. The etching method forms a first patterned passivation layer and a second passivation layer on a top surface and a bottom surface, followed by performing a first etching process for simultaneously etching the substrate and the first passivation layer. After the first passivation layer is removed, a second etching process is performed to etch the substrate to a designated depth that is used to control the thickness of the wafer after the second etching process.
It is an advantage of the present invention that the etching method controls the thickness of the wafer and the size of slots for inkjet printhead and MicroElectroMechanical Systems applications.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.


REFERENCES:
patent: 4372803 (1983-02-01), Gigante
patent: 4957592 (1990-09-01), O'Neill
patent: 5316618 (1994-05-01), van Lintel
patent: 5994160 (1999-11-01), Niedermann et al.
patent: 6137511 (2000-10-01), Furuhata et al.
patent: 57095633 (1982-06-01), None

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