Abrading – Machine – Rotary tool
Reexamination Certificate
2000-12-14
2002-08-20
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Rotary tool
C451S041000, C451S287000, C451S288000, C451S397000, C451S398000
Reexamination Certificate
active
06435955
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an abrasive machine, more precisely relates to an abrasive machine, which comprises a holding unit for holding a work piece, e.g., a semiconductor wafer, and an abrasive plate having an abrasive face, which abrades a surface of the work piece by relatively moving the abrasive plate with respect to the holding unit. For example, the abrasive face abrades a surface of a semiconductor wafer, in which semiconductor chips are formed, like a mirror face.
Recently, circuits in semiconductor devices are highly integrated, so flatness and surface conditions of silicon wafers, etc., which will be substrates of semiconductor devices, must be highly improved. Further, insulating layers and cables paterns, which are formed on the wafer so as to form the devices, are abraded with higher flatness. Therefore, the abrasive machine must abrade the surfaces of the wafers, like mirror faces, with higher accuracy.
In a conventional abrasive machine, a whole surface of a wafer is uniformly pressed onto an abrasive face of an abrasive plate by an airbag of a wafer holding unit.
The wafer holding unit of the conventional abrasive machine will be explained with reference to
FIGS. 9 and 10
.
In
FIG. 9
, an abrasive plate
50
is rotated about a vertical shaft. An abrasive cloth
51
is adhered on an upper face of the abrasive plate
50
so as to form an abrasive face
52
. The wafer holding unit
60
is provided above the abrasive plate
50
. The wafer holding unit
60
is rotated about a vertical shaft and moved in the vertical direction.
The wafer holding unit
60
includes: a head
62
having a concave section
62
a,
whose opening section is headed downward; a wafer holding plate
64
having a holding face, on which the wafer
12
is held; an elastic member
66
, whose outer edge
66
b
is fixed to an enclosing section
62
b
of the head
62
and whose inner edge
66
a
is fixed to an outer end section
64
a
of the wafer holding plate
64
, being formed like a plate and capable of allowing the wafer holding plate
64
to move within a very small range; and an air-tightly sealed chamber
65
being formed, in the head
62
, by the wafer holding plate
64
and the elastic member
66
.
A vacuum unit
67
for sucking and holding the wafer
12
is communicated to sucking holes
67
a,
which are opened in a bottom face of the wafer holding plate
64
, which acts as a wafer holding face, via an air tube
67
b.
By actuating the vacuum unit
67
, the wafer
12
can be sucked and held on the wafer holding face of the wafer holding plate
64
.
A pressurizing unit
68
supplies pressurized fluid to the chamber
65
so as to press the wafer
12
onto the abrasive face
52
of the abrasive plate
50
together with the wafer holding plate
64
.
A pressure reducing unit
69
reduces inner pressure of the chamber
65
.
A male tapered section
70
, whose outer diameter is gradually reduced downward, is downwardly projected from an inner ceiling face of the head
62
; a female tapered section
72
, whose inner diameter is gradually increased upward, is upwardly projected from an upper face of the wafer holding plate
64
. With this structure, the male tapered section
70
fits in the female tapered section
72
when the pressure reducing unit
69
reduces the inner pressure of the chamber
65
.
In the conventional abrasive machine, the surface
12
a
of the wafer
12
to be abraded is capable of quickly following inclination, etc. of the abrasive face
52
because of the airbag function of the elastic member
66
, e.g., a rubber plate, so that the whole surface
12
a
of the wafer
12
can be uniformly pressed onto the abrasive face
52
even if the abrasive face
52
is inclined. With this action, the whole surface
12
a
can be uniformly abraded or polished like a mirror face.
By fitting the male tapered section
70
in the female tapered section
72
, the wafer holding plate
64
can be precisely positioned, so that the wafer
12
can be positioned or adhered at a correct position. Therefore, abrading accuracy and abrading efficiency can be improved, and abrading steps can be executed automatically.
However, in the conventional abrasive machine, the surface
12
a
of the wafer
12
is pressed onto the abrasive face
52
of the abrasive cloth
51
, which is adhered on the abrasive plate
50
, while abrading or polishing the wafer
12
. A part of the abrasive cloth
51
, on which the wafer
12
is pressed, is slightly caved downward with respect to other parts, so that a concave portion
51
a
(see
FIG. 10
) is formed. And, a lower outer edge
12
b
of the wafer
12
contacts an inner face of the concave portion
51
a
and is abraded thereby.
If the lower outer edge
12
b
of the wafer
12
is abraded by the inner face of the concave portion
51
a
of the abrasive cloth
51
, the abrasive face
52
is waved and badly abraded, so that flatness of the abraded surface
12
a
of the wafer
12
is made lower.
The abrasive face
52
of the abrasive cloth
51
, which has been waved and badly abraded, can be recovered by recovering means. In the conventional abrasive machine, for example, the recovering means, e.g., a dummy wafer, a ceramic plate, is attached to the wafer holding plate
64
of the holding unit
60
, then the recovering means is pressed onto the abrasive face
52
so as to recover the damaged abrasive face
52
. In the case of a new abrasive cloth
51
, a surface condition of the new abrasive cloth
51
is uniformed by the recovering member.
The step of recovering the abrasive cloth
51
cannot be simultaneously executed with the abrasive step. If the recovering step is executed before or after the abrasive step, required time of the abrasive step and the recovering step must be longer and working efficiency cannot be improved.
Conditions, e.g., pressing force, rotational speed of the wafer holding plate
64
, in the abrasive step are different from those in the recovering step, but the wafer holding plate
64
is used in the both steps. Therefore, the rotational speed of the wafer holding plate
64
and the pressing force applied to the wafer holding plate
64
(the inner pressure of the chamber
65
) must be newly set when the abrasive step or the recovering step is executed. The change of the conditions is troublesome, so that working efficiency and manufacturing efficiency cannot be improved.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an abrasive machine, which is capable of preventing deformation and bad abrasion of the abrasive cloth, maintaining flatness of the abrasive face of the abrasive plate and improving abrading accuracy.
To achieve the object, the abrasive machine of the present invention comprises:
a holding unit for holding a work piece; and
an abrasive plate having an abrasive face, which abrades a surface of the work piece by relatively moving the abrasive plate with respect to the holding unit,
wherein the holding unit includes:
an inner head having a first concave section, whose opening section is headed toward the abrasive face of the abrasive plate;
an outer head having a second concave section, in which the inner head is provided and whose opening section is headed toward the abrasive face of the abrasive plate,
a holding plate being provided in the first concave section and having a holding face, on which the work piece is held;
an elastic holding member being fixed to the inner head and the holding plate, allowing the holding plate to move with respect to the inner head, and forming a first chamber for pressing the work piece in the first concave section with the holding plate;
an outer enclosing member being provided to the outer head and enclosing the inner head;
an inner enclosing member being provided between the outer enclosing member and the inner head and enclosing the inner head;
a pressing member for pressing the abrasive face of the abrasive plate, the pressing member being formed into a ring shape enclosing the holding plate;
an elastic ring member being fixed to the outer enc
Denda Yasuhide
Furukawa Masanori
Kuroiwa Hisato
Nakamura Yoshio
Fujikoshi Machinery Corp.
Hail III Joseph J.
Jordan and Hamburg LLP
McDonald Shantese
LandOfFree
Abrasive machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Abrasive machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Abrasive machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2938650