U.S. patent application number 11/029481 was filed with the patent office on 2005-07-14 for etching apparatus.
Invention is credited to Fujisawa, Shinichi.
Application Number | 20050150860 11/029481 |
Document ID | / |
Family ID | 34737178 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050150860 |
Kind Code |
A1 |
Fujisawa, Shinichi |
July 14, 2005 |
Etching apparatus
Abstract
In order to prevent a workpiece from being damaged in etching
workpiece of various external diameters, a ceramic holding jig
corresponding to the external diameter of workpiece is mounted on a
chuck table in a chamber of an etching apparatus. The chuck table
is composed of a holding face for holding a workpiece and for
converting etching gas into plasma and insulating zones each having
an internal diameter smaller than the external diameter of the
workpiece and an external diameter larger than the external
diameter of the workpiece. In case a workpiece is to be held by
either a first ceramic holding jig or a second ceramic holding jig
on the chuck table, a jig identifying means installed to the
chamber identify in advance which ceramic holding jig is mounted on
the chuck table to match the holding jig and the workpiece each
other, thereby to prevent the workpiece from being damaged.
Inventors: |
Fujisawa, Shinichi; (Tokyo,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
34737178 |
Appl. No.: |
11/029481 |
Filed: |
January 6, 2005 |
Current U.S.
Class: |
216/2 |
Current CPC
Class: |
H01L 21/67069 20130101;
H01L 21/68785 20130101; H01J 37/32082 20130101 |
Class at
Publication: |
216/002 |
International
Class: |
C23F 001/00; B24B
001/00; B24B 007/19; B24B 007/30 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 9, 2004 |
JP |
2004-004044 |
Claims
1. An etching apparatus comprising: a chuck table for holding a
workpiece; etching gas supply means for supplying an etching gas to
the workpiece held by said chuck table; a chamber housing said
chuck table and said etching gas supply means and having an
opening, through which said workpiece is delivered in and out;
transfer means for delivering the workpiece into and out of said
chamber through said opening; and a shutter for bringing said
opening into an opened state or a closed state, wherein said chuck
table is configured to include a holding face for holding the
workpiece and for converting the etching gas into plasma, and
insulating zones each having an internal diameter smaller than the
external diameter of the workpiece and an external diameter larger
than the external diameter of the workpiece, said insulating zones
respectively match at least two types of workpiece with different
external diameters, including a first ring-shaped insulating zone
having an internal diameter smaller than the external diameter of a
first workpiece with the larger external diameter and an external
diameter larger than the external diameter of said first workpiece;
and a second ring-shaped insulating zone having an internal
diameter smaller than the external diameter of the second workpiece
with external diameter smaller than said first workpiece, and an
external diameter larger than the external diameter of said second
workpiece, and said chuck table can mount a first ceramic holding
jig for housing said first workpiece and for covering the portion
of said first insulating zone of said chuck table that does not
contact said first workpiece; and a second ceramic holding jig for
housing said second workpiece and for covering the portion of said
second insulating zone of said chuck table that does not contact
the second workpiece, and further comprising: a jig identifying
means for identifying said first ceramic holding jig and said
second ceramic holding jig.
2. An etching apparatus according to claim 1, wherein the external
diameter of said first ceramic holding jig and the external
diameter of said second ceramic holding jig are different, and said
jig identifying means is arranged on the outer side of the chamber
for measuring the external diameter of the first ceramic holding
jig and the external diameter of the second ceramic holding jig
when the opening is brought into the opened state.
3. An etching apparatus according to claim 2, wherein said jig
identifying means has a function to output a signal corresponding
to an identified result, and decision means for deciding, by
inputting the signal, whether or not the ceramic holding jig
mounted on the chuck table matches the workpiece to be delivered
into the chamber is connected with the jig identifying means, the
transfer means is informed of the result of the decision by the
decision means, and the transfer means controls the delivery of the
workpiece into the chamber on the basis of the result of the
decision.
4. An etching apparatus according to claim 1, wherein the workpiece
is a semiconductor wafer, whereby the face of the ground
semiconductor wafer is thereafter etched in the chamber.
5. An etching apparatus according to claim 2, wherein the workpiece
is a semiconductor wafer, whereby the face of the ground
semiconductor wafer is thereafter etched in the chamber.
6. An etching apparatus according to claim 3, wherein the workpiece
is a semiconductor wafer, whereby the face of the ground
semiconductor wafer is thereafter etched in the chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an etching apparatus for
etching a workpiece by plasma etching.
[0003] 2. Related Art
[0004] A plate-shaped workpiece is ground on its face to a desired
thickness by using a grindstone. For example, a semiconductor wafer
has a plurality of IC, LSI or the like formed on its surface side
and is formed to a desired thickness by grinding its back face.
[0005] However, fine cracks called the "microcracks" are generated
in the ground face. When a plate-shaped article is divided into
individual chips by a later cutting operation, there arises a
problem that the folding endurance of the individual chips
degrades. Therefore, the ground face is plasma-etched to remove the
microcracks (see JP-A-2001-257186, for example).
[0006] In the plasma etching apparatus, as disclosed in
JP-A-2001-257186, a lower electrode (a chuck table) holds by
suction the plate-shaped article to be etched. However, the
plate-shaped article may be one of various types with different
external diameters. In order that the chuck table may hold the
plate-shaped articles stably with sufficient suction force without
any leakage of air, therefore, troublesome works are required for
replacing the chuck table to match the external diameter of each
individual plate-shaped article.
[0007] As shown in FIG. 7, therefore, a chuck table 55 is formed
into a ring shape by providing its holding face with a plurality of
(e.g., two in the shown example) ring-shaped first and second
insulating zones 55d and 55e having different internal diameters
and external diameters. On the other hand, among the various kinds
of the plate-shaped articles, ceramic holding jigs 100 and 101
capable of covering those insulating zones and housing plate-shaped
articles are produced as many as the plate-shaped articles. These
plate-shaped articles are held not by interchanging the chuck
tables matching their external diameters but through ceramic
holding jigs capable of housing them individually.
[0008] In case the plate-shaped articles to be plasma-etched are
two kinds of semiconductor wafers having external diameters of 200
mm and 300 mm, for example, the first ring-shaped insulating zone
55d having an internal diameter of 295 mm and an external diameter
of 305 mm and the second ring-shaped insulating zone 55e having an
internal diameter of 195 mm and an external diameter of 205 mm are
formed in the chuck table 55 sized to hold a plate-shaped article
having an external diameter of 300 mm at the maximum. The
semiconductor wafers are housed in the housing portions of the
individual holding jigs, by preparing two kinds of holding jigs 100
and 101 having housing portions having external diameters for
covering the first insulating zone 55d and the second insulating
zone 55e and storage portions corresponding to the external
diameters of the semiconductor wafers of 200 mm and 300 mm (having
internal diameters slightly larger than the external diameters of
the semiconductor wafers), and by replacing the holding jig
according to the external diameter of the semiconductor wafer to be
etched. By thus holding the plate-shaped articles through the
holding jigs, the semiconductor wafer of different external
diameters can be stably held all over their faces and etched.
SUMMARY OF THE INVENTION
[0009] In case, however, the plate-shaped article to be held on the
chuck table and the ceramic holding jig mounted on the chuck table
do not match each other, for instance if a plate-shaped article
having a diameter of 150 mm or 300 mm is delivered onto the chuck
table although the ceramic holding jig for the semiconductor wafer
having an external diameter of 200 mm is mounted on the chuck
table, the plate-shaped article cannot be housed in the ceramic
holding jig or even if housed, a large clearance is formed with the
inner circumference of the ceramic holding jig. If the plasma
etching is performed in that state, there arises a problem that the
semiconductor wafer is etched and damaged at its faces other than
the back face.
[0010] Therefore, the problem to be solved by the invention is to
prevent a workpiece from being damaged, by causing the ceramic
holding jig to be mounted on a chuck table in a chamber of an
etching apparatus and the workpiece to be held on the chuck table
to match each other.
[0011] In order to solve the above-specified problem, according to
the invention, there is provided an etching apparatus comprising: a
chuck table for holding a workpiece; etching gas supply means for
supplying an etching gas to the workpiece held by said chuck table;
a chamber housing said chuck table and said etching gas supply
means and having an opening, through which said workpiece is
delivered in and out; transfer means for delivering the workpiece
into and out of said chamber through said opening; and a shutter
for bringing said opening into an opened state or a closed state,
wherein said chuck table is configured to include a holding face
for holding the workpiece and for converting the etching gas into
plasma, and insulating zones each having an internal diameter
smaller than the external diameter of the workpiece and an external
diameter larger than the external diameter of the workpiece, said
insulating zones respectively match at least two types of workpiece
with different external diameters, including a first ring-shaped
insulating zone having an internal diameter smaller than the
external diameter of a first workpiece with the larger external
diameter and an external diameter larger than the external diameter
of said first workpiece; and a second ring-shaped insulating zone
having an internal diameter smaller than the external diameter of
the second workpiece with external diameter smaller than said first
workpiece, and an external diameter larger than the external
diameter of said second workpiece, and said chuck table can mount a
first ceramic holding jig for housing said first workpiece and for
covering the portion of said first insulating zone of said chuck
table that does not contact said first workpiece; and a second
ceramic holding jig for housing said second workpiece and for
covering the portion of said second insulating zone of said chuck
table that does not contact the second workpiece, and further
comprising: jig identifying means for identifying said first
ceramic holding jig and said second ceramic holding jig.
[0012] In case the external diameter of the first ceramic holding
jig and the external diameter of the second ceramic holding jig are
different, and the jig identifying means is arranged on the outer
side of the chamber for measuring the external diameter of the
first ceramic holding jig and the external diameter of the second
ceramic holding jig when the opening is brought into the opened
state, the kind of the ceramic holding jig mounted on the chuck
table can be identified from outside the chamber. For example, an
optical sensor can be used for the holding discrimination of this
case. If the ceramic holding jig is formed to be identified by a
feature other than the external diameter, the etching apparatus may
be provided with corresponding means for the discrimination.
[0013] Moreover, the jig identifying means may have a function to
output a signal corresponding to an identified result, and decision
means for deciding, by inputting the signal, whether or not the
ceramic holding jig mounted on the chuck table matches the
workpiece to be delivered into the chamber is connected with the
jig identifying means. The transfer means is informed of the result
of the decision by the decision means, whereby the transfer means
controls the delivery of the workpiece into the chamber. Then, it
is possible to avoid the delivery of a workpiece failing to match
the ceramic holding jig mounted on the chuck table, into the
chamber.
[0014] In case the workpiece is a semiconductor wafer, the face of
the ground semiconductor wafer is etched in the chamber.
[0015] According to the invention, the jig identifying means can
determine, before the workpiece is etched, whether the holding
mounted in advance on the chuck table is the first ceramic holding
jig or the second ceramic holding jig, and the workpiece can be
treated according to the identified result.
[0016] In case the external diameter of the first ceramic holding
jig and the external diameter of the second ceramic holding jig are
different, and the jig identifying means is arranged outside the
chamber for measuring the external diameter of the first ceramic
holding jig and the external diameter of the second ceramic holding
jig when the opening is brought into the opened state, the kind of
the ceramic holding jig mounted on the chuck table can be
identified from outside the chamber. Therefore, the jig identifying
means can be kept away from the influences of the etching gas or
the plasma.
[0017] The jig identifying means has the function to output the
signal corresponding to the identified result, the decision means
is connected with the jig identifying means, and the transfer means
is informed of the result of the decision by the decision means.
The transfer means controls the delivery of the workpiece into the
chamber on the basis of the decision. Here, the decision means
decides for instance whether or not the ceramic holding jig mounted
on the chuck table and the workpiece to be inserted match each
other. In case the ceramic holding jig mounted on the chuck table
and the workpiece to be inserted fail to match each other, the
transfer means can stop the delivery of the workpiece into the
chamber. It is, therefore, possible to prevent the workpiece from
being damaged by the etching.
[0018] In case the workpiece is a semiconductor wafer, the
semiconductor wafer can be prevented from being damaged, and the
microcracks generated by the grinding operation can be etched off.
It is, therefore, possible to enhance the folding endurance of the
semiconductor chip after dicing.
BRIEF DESCRIPTION OF THE DRAWING
[0019] FIG. 1 is a perspective view showing a grinding apparatus
and an etching apparatus according to an embodiment of the present
invention;
[0020] FIG. 2 is a sectional view showing an example of
configuration of the etching apparatus;
[0021] FIG. 3 is a perspective view showing a chuck table, jig
identifying means and ceramic holding jigs in the etching
apparatus;
[0022] FIGS. 4A and 4B are sectional views showing configurations
of the ceramic holding jigs;
[0023] FIGS. 5A and 5B are sectional views showing the states, in
which the ceramic holding jigs are mounted on the chuck table;
[0024] FIG. 6 is a top plan view showing the chuck table and the
jig identifying means; and
[0025] FIG. 7 is a perspective view showing a chuck table and
ceramic holding jigs in the etching apparatus of the prior art.
DETAILED DESCRIPTION OF THE INVENTION
[0026] An etching apparatus 50, as shown in FIG. 1, is disposed in
the shown embodiment adjacent to a grinding apparatus 10. A
workpiece with one face ground by the grinding apparatus 10 is
transferred to the etching apparatus 50, in which the ground face
can be etched. Here will be described the case in which the back
face of a semiconductor wafer as one kind of workpiece is ground in
the grinding apparatus 10 and in which microcracks generated on the
ground back face of the semiconductor wafer are removed in the
etching apparatus 50.
[0027] This grinding apparatus 10 is provided with: a cassette 11
for housing a semiconductor wafer W with protective tape adhered to
its front surface; a cassette 12 for housing the semiconductor
wafer W with protective tape adhered to its front surface and its
back surface being ground; transfer means 13 for transferring the
semiconductor wafer W out of the cassette 11 or into the cassette
12; a positioning table 14 for positioning the semiconductor wafer
W; first and second delivery means 15 and 16 for delivering the
semiconductor wafer W; four holding tables 17, 18, 19 and 20 for
holding by suction the semiconductor wafer W; a turntable 21 for
supporting the holding tables 17, 18, 19 and 20 rotatably; first
and second grinding means 22 and 23 for grinding the semiconductor
wafer W; and rinsing means 24 for rinsing the semiconductor wafer W
ground.
[0028] Semiconductor wafers W not yet ground but with protective
tape adhered to its front surface are stacked in plural levels in
the cassette 11 and are picked up one by one by the transfer means
13 to be placed on the positioning table 14 with their back
surfaces directed upward.
[0029] After being positioned at a predetermined position in the
positioning table 14, moreover, the semiconductor wafer W is
attached by suction to the first delivery means 15 and is delivered
onto the holding table 17 by the turning motion of the first
delivery means 15 to be placed on the holding table 17. At this
time, the semiconductor wafer W takes the state in which its back
surface is exposed upward.
[0030] Next, the turntable 21 turns a predetermined angle (90
degrees in the shown example where there are four holding tables)
so that the semiconductor wafer W held on the holding table 17 is
positioned just below the first grinding means 22. In this action
as well, the holding table 18 is brought to the previous position
of holding table 17 before the turn of the turntable 21, the
semiconductor wafer to be ground next is delivered out of the
cassette 11, and placed on the positioning table. After
positioning, the next semiconductor wafer is delivered to the
holding table 18 by the first delivery means 15 and placed
thereon.
[0031] The first grinding means 22 is made vertically movable with
respect to an erected wall portion 25. On the inner face of the
wall portion 25, there are vertically arranged a pair of rail 26,
along which a support plate 28 is driven by a drive source 27 to
move vertically along the rails 26. Accordingly, the first grinding
means 99 fixed on the support plate 28 is vertically moved.
[0032] In the first grinding means 22, a grinding wheel 31 is
mounted via a mounter 30 to the leading end of a spindle 29a
rotatably supported. A grinding wheel 32 for a rough grinding
operation is fixed below the grinding wheel 31.
[0033] When the semiconductor wafer W is positioned just below the
first grinding means 22, it is turned by the turning motion of the
holding table 17, and the first grinding means 22 is moved downward
while the grinding wheel 32 is turned by the turning motion of the
spindle 29. The grinding wheel 32 comes into contact with the back
face of the semiconductor wafer W so that the back face of the
semiconductor wafer W is roughly ground. Here, cut grooves for
separating a plurality of circuits are formed in the front surface
of the semiconductor wafer W. In the case of so-called "first
dicing" in which the back face of the semiconductor wafer is ground
till the cut grooves are exposed on their back faces so that the
semiconductor wafer is divided into individual semiconductor chips
for individual circuits, the rough grinding is ended just before
the cut grooves are exposed to the back face.
[0034] The semiconductor wafer W thus roughly ground is positioned
just below the second grinding means 23 by turning the turntable 21
a specific angle.
[0035] The second grinding means 23 is made vertically movable with
respect to the erected wall portion 25. On the inner face of the
wall portion 25, there are vertically arranged a pair of rail 33,
along which a support plate 35 is driven by a drive source 34 to
move vertically along the rail 33. Accordingly, the second grinding
means 23 fixed on the support plate 35 is vertically moved.
[0036] In the second grinding means 23, a grinding wheel 38 is
mounted on a mounter 37 which in turn is mounted on the leading end
of a spindle 36, which is rotatably supported. A grinding wheel 39
for a finish grinding operation is fixed below the grinding wheel
38.
[0037] When the semiconductor wafer W with protective tape 1
adhered to its surface and which has been roughly ground is
positioned just below the second grinding means 23, it is turned by
the turning motion of the holding table 17, and at the same time
the second grinding means 23 is moved downward while the grinding
wheel 39 is turned by the turning motion of the spindle 36. The
grinding wheel 39 comes into contact with the back face of the
semiconductor wafer W so that the back face of the semiconductor
wafer W is given a grinding finish. Here in the case of so-called
"first dicing", the cut grooves are exposed to the outside so that
the semiconductor wafer W is divided into the individual
semiconductor chips.
[0038] The semiconductor wafer W given a grinding finish and held
on the holding table 17 is positioned near the second delivery
means 16 by the turn of the turntable 21. Then, the semiconductor
wafer W is delivered to the rinsing means 24 by the second delivery
means 16 to be rinsed and cleared of the grinding chips. After
this, the semiconductor wafer W is delivered out of the rinsing
means 24 by transfer means 40 incorporated in the etching apparatus
50.
[0039] The transfer means 40 arranged near the cassette 12 is
provided with: a suction unit 41 to suck the semiconductor wafer W;
an arm unit 42 for moving the suction unit 41 horizontally and
vertically; and a drive unit 43 for driving the arm unit 42. The
semiconductor wafer W rinsed is attached by suction to the suction
unit 41, and this suction unit 41 moves to deliver the
semiconductor wafer W to the etching apparatus 50.
[0040] As shown in FIG. 1, this etching apparatus 50 is configured
so that a gas supply unit 51 and a plasma treatment unit 52 are
connected to each other. The gas supply unit 51 is provided with a
tank for reserving an etching gas, a pump for feeding the etching
gas to the plasma treatment unit 52, and so on. The tank is stored
with a mixed gas whose main components include a fluorine gas such
as CF.sub.4 and oxygen.
[0041] As shown in FIG. 2, the plasma treatment unit 52 is provided
with a chamber 53 for plasma etching, and is configured to house
etching gas supply means 54 from the upper side of the chamber 53
and to house a chuck table 55 for holding the workpiece to be
etched, from the bottom of the chamber 53. The etching gas supply
means 54 introduces the gas supplied from the gas supply unit 51
into the chamber 53.
[0042] The etching gas supply means 54 is provided with a spindle
54a which is made vertically and rotatably movable, fitted in a
bearing 56 attached to the chamber 53, and an upper electrode 54b
extending from the lower end of the spindle 54a. A gas flow passage
57 communicating with the gas supply unit 51 is formed in the
etching gas supply means 54, and a plurality of gas injection ports
54c communicating with the gas flow passage 57 are formed in the
upper electrode 54b.
[0043] A lift unit 60 is connected to a side of the spindle 54a.
The lift unit 60 is screwed on a threaded rod 59, which is arranged
in the vertical direction. The threaded rod 59 is connected to a
motor 58. As the threaded rod 59 is turned by the motor 58, the
lift unit 60 moves up and down, and the etching gas supply means 54
accordingly moves up and down.
[0044] The chuck table 55 is provided with a spindle 55a, which is
made vertically and rotatably movable, fitted in a bearing 61
attached to the chamber 53, and a lower electrode 55b extending
from the upper end of the spindle 55a. The lower electrode 55b is
composed of a holding face 55c made of a metal such as aluminum
having a high electric conductivity for holding the workpiece and
for converting the etching gas into plasma, and first and second
ring-shaped insulating zones 55d and 55e. The holding face 55c is a
zone for holding the workpiece by an attractive force. The first
and second insulating zones 55d and 55e are zones in which the
force for holding the workpiece does not act and in which the
plasma is not generated by the discharge. In the shown embodiment,
the first insulating zone 55d is formed to protrude upward from the
upper face of the outer circumference side, and the first
insulating zone 55d, the second insulating zone 55e and the holding
face 55c are flush with one another. Alteratively, three or more
insulating zones may also be formed.
[0045] In the chuck table 55, there are formed a suction passage 63
communicating with a suction source 62, and a cooling passage 65
communicating with a cooling unit 64. The suction passage 63 is
branched in the lower electrode 55b into a plurality of suction
ports 63a and forms the holding face 55c on the surface of the
chuck table 55. The cooling passage 65 cools the held workpiece
with the cooling water circulating in the chuck table 55.
[0046] In one side of the chamber 53, there is formed an opening
66, through which the workpiece to be etched is delivered in and
out. On the outer side of the opening 66, there is arranged a
shutter 67 for opening or closing the opening 66 as it moves up and
down. This shutter 67 is brought upward and downward by a piston
69, which is driven to move up and down by a cylinder 68. In the
bottom of the chamber 53, moreover, there is formed a discharge
port 71, which communicates with a gas discharge unit 70 to
discharge the used gas from the discharge port 71 to the gas
discharge unit 70.
[0047] The etching gas supply means 54 and the chuck table 55 are
connected with a high-frequency power source 72. This
high-frequency power source 72 supplies the etching gas supply
means 54 and the chuck table 55 with high-frequency electric power
for converting the gas introduced into the chamber 53, into
plasma.
[0048] As shown in FIG. 3, the first insulating zone 55d and the
second insulating zone 55e are formed in the chuck table 55. In
order to hold two kinds of workpiece having different external
diameters, moreover, there are prepared a first ceramic holding jig
100 for the first workpiece having a larger external diameter, and
a second ceramic holding jig 101 for the second workpiece having a
smaller external diameter. Depending on which workpiece is to be
etched, one of the ceramic holding jigs is placed in advance on the
chuck table 55 so that the workpiece is held on the chuck table
through that ceramic holding jig.
[0049] As shown in FIG. 3, the first insulating zone 55d has
internal diameter D.sub.11, and an external diameter D.sub.12, and
the second insulating zone 55e has an internal diameter D.sub.21
and an external diameter D.sub.22. With these dimensions, the first
workpiece larger in external diameter has an external diameter
larger than D.sub.11 and smaller than D.sub.12, and the second
workpiece smaller in external diameter has an external diameter
larger than D.sub.21 and smaller than D.sub.22.
[0050] As shown in FIGS. 4A and 4B, the first ceramic holding jig
100 and the second ceramic holding jig 101 are formed to have steps
on the inner circumferences so that they have different internal
diameters on their front side and their back side. The internal
diameter D.sub.31a of the front side of the first ceramic holding
jig 00 is made slightly larger than the external diameter of the
first workpiece so that it can house the first workpiece. The
internal diameter D.sub.41a of the front side of the second ceramic
holding jig 101 is made slightly larger than the external diameter
of the second workpiece so that it can house the second workpiece.
On the other hand, the internal diameter D.sub.31b of the back side
of the first ceramic holding jig 100 and the internal diameter
D.sub.41b of the back side of the second ceramic holding jig 101
are made slightly larger than the external diameter D.sub.12 (as
referred to FIG. 3) of the first insulating zone 55d. Thus, the
inner circumference of the first ceramic holding jig 100 and the
second ceramic holding jig 101 which has the larger internal
diameter (on the back side) is fitted and fixed on the outer
periphery of the first insulating zone 55d.
[0051] In the shown embodiment, moreover, the external diameter
D.sub.32 of the first ceramic holding jig 100 and the external
diameter D.sub.42 of the second ceramic holding jig 101 are made
sufficiently different so that the first ceramic holding jig 100
and the second ceramic holding jig 101 can be dearly
distinguished.
[0052] FIG. 5A shows the case where the first ceramic holding jig
100 is mounted on the chuck table 55 and a first semiconductor
wafer W1 as the first workpiece is housed in the first ceramic
holding jig 100. FIG. 5B shows the case where the second ceramic
holding jig 101 is mounted on the chuck table 55 and a second
semiconductor wafer W2 is housed in the second ceramic holding jig
101. In either case, the back faces of the semiconductor wafer W1
or W2 and the ceramic holding jigs 100 or 101 make close contact
with the holding face 55c, thereby preventing air leakage, so that
the semiconductor wafer W1 or W2 housed is held by the suction
force acting on the holding face 55c.
[0053] On the outer side of the chamber 53, as shown in FIG. 3 and
FIG. 6, there is arranged a jig identifying means 80. This jig
identifying means 80 has a function to identify the kind of the
ceramic holding jig mounted on the chuck table 55, and is provided
with an optical sensor 81 in the shown embodiment. The ceramic
holding jig, which is mounted on the chuck table 55, has different
external diameters according to the external diameter of the
semiconductor wafer W housed, so that the optical sensor 81 can
identify the kind of the ceramic holding jig on the basis of the
distance from the ceramic holding jig.
[0054] Failure of the jig identfying means 80 can be prevented
through its installation outside the shutter 67 for opening or
dosing the opening 66 of the chamber 53. This is because the jig
identifying means 80 is thereby not affected by the plasma etching.
The holding jig is distinguished when the semiconductor wafer is
about to be passed through the shutter 67 in the open state.
Therefore, a semiconductor wafer which does not match the ceramic
holding jig mounted on the chuck table 55 is prevented from being
delivered into the chamber 53 and etched with the plasma.
[0055] The jig identifying means 80 has a function to output a
signal corresponding to the discrimination result. If a decision
means 82 is connected not only with the jig identifying means 80
but also with the transfer means 40, as shown in FIG. 6, the
decision means 82 can decide from the signal coming from the jig
identifying means 80 whether or not the ceramic holding jig mounted
on the chuck table 55 and the semiconductor wafer to be delivered
into the chamber 53 match each other. If storage means 83 stores
the external diameter of the semiconductor wafer inputted from an
operation panel 10a of the grinding apparatus 10, for example, the
decision means 82 is enabled to decide by reading out the value of
the external diameter from the storage means 83 whether or not the
ceramic holding jig and the semiconductor wafer match each other.
In case it is decided that the ceramic holding jig and the
semiconductor wafer do not match, moreover, the transfer means 40
is informed of the failure and can control the suction unit 41 and
the arm unit 42 so that the delivery of the semiconductor wafer
into the chamber 53 is stopped to prevent the semiconductor wafer
from being damaged by etching. Here, in case the storage means 83
does not store the external diameter of the semiconductor wafer,
the configuration may be so modified that the decision means 82 can
recognize the external diameter of the semiconductor wafer. With
reference to FIG. 2 and other diagrams, here will be described the
case in which the back face of the semiconductor wafer W is
plasma-etched after being ground. At first, the shutter 67 is moved
down to open the opening 66, and the semiconductor wafer W held by
the suction unit 41 (in FIG. 1) is advanced through the opening 66
into the chamber 53. At this time, the kind of the ceramic holding
jig mounted on the chuck table 55 in the chamber 53 is identified
by the jig identifying means 80 (as referred to FIGS. 3 and 6), and
it is decided by the decision means 82 whether or not the
semiconductor wafer is to be delivered in. Only when it is decided
by the decision means 82 that the semiconductor wafer W to be
delivered in matches the ceramic holding jig, the semiconductor
wafer W is advanced through the opening 66 into the chamber 53 and
put onto the chuck table 55 by suction through the ceramic holding
jig by placing the semiconductor wafer on the ceramic holding jig
with its back face facing upward and by causing the holding face
55c to apply suction force.
[0056] Next, the suction unit 41 is taken to the outside of the
chamber 53, and the shutter 67 is returned to its original position
to bring the opening into the closed state. Then, the back face of
the semiconductor wafer W is plasma-etched by evacuating the inside
of the chamber 53, introducing the gas into the chamber 53 from the
etching gas supply means 54, and feeding the high-frequency
electric power from the high-frequency power source 72 to the
etching gas supply means 54 and the chuck table 55 to convert the
introduced gas into plasma. The microcracks are removed by this
plasma etching, thereby enhancing the folding endurance of each
semiconductor chip.
[0057] The semiconductor wafer W plasma-etched its back face as
described hereinbefore is attached by suction to the suction unit
41 shown in FIG. 1 after moving down the shutter 67 shown in FIG. 1
and FIG. 2 to open the opening 66, and the suction unit 41 is moved
to deliver it out of the chamber 53. Then, the etched semiconductor
wafer W is transferred to the rinsing means 24 of the grinding
apparatus 10 shown in FIG. 1, in which the semiconductor wafer W is
rinsed. After this, the rinsed semiconductor wafer W is housed in
the cassette 12 by the transfer means 13. All the semiconductor
wafers housed in the cassette 11 are subjected to the grinding
operation and the plasma etching described above, and all the
semiconductor wafers are housed in the cassette 12.
[0058] In the embodiment, the kinds of ceramic holding jigs are
identified by the jig identifying means 80 on the basis of the
different external diameters of the ceramic holding jigs. However,
this discrimination can also be performed on the basis of
differences in the shapes, for example. Moreover, the jig
identfying means 80 is not be limited to those using the optical
sensor.
[0059] The invention can be employed in etching for various
workpiece having different external diameters.
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