WO1999012190A2

WO1999012190A2 - Sealed capsule opening and unloading system

Info

Publication number: WO1999012190A2
Application number: PCT/US1998/018394
Authority: WO
Inventors: George E. Niemirowski; John M. Harrell; P. V. Pateh
Original assignee: Novus Corporation
Priority date: 1997-09-03
Filing date: 1998-09-03
Publication date: 1999-03-11
Also published as: WO1999012190A3

Abstract

A system is provided for transferring a semiconductor wafer (111) supported in a sealed capsule (106) from a first stored position to a second working position using an opening mechanism having a load door (114). The capsule (106) is positioned adjacent the load door (114) to form a sealed environment between the capsule (106) and the opening mechanism. The load door (114) is then locked to the capsule door (126). Next, the load door (114) and the capsule door (126) are moved a predetermined distance while retaining the sealed environment between the opening mechanism and the capsule (106). Thereafter, the capsule (106) is purged with a gas. The load door (114) and the capsule door (126) are then moved a further distance to open the capsule (106), allowing the semiconductor wafer (111) to be retrieved.

Description

SEALED CAPSULE OPENING AND UNLOADING SYSTEM

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates generally to semiconductor wafer

fabrication and, more particularly, to methods and apparatus for

transferring wafers between various processing locations during

fabrication. Even more specifically, the invention relates to an opening

and unloading system for sealed capsules or cassettes containing wafers.

Description of the Related Art

Semiconductor wafer production typically involves the handling of

cassettes or capsules containing batches of semiconductor wafers.

These capsules are usually standardized devices used in the

semiconductor manufacturing industry for holding and moving

semiconductor wafers among different machining processes or locations.

Wafer fabrication requires extremely clean working environments

because contamination ordinarily results in costly production loss.

A problem associated with prior art sealed capsule handling

systems is that wafer contamination has been known to occur when

sealed capsules containing wafers are opened by the capsule handling

equipment to allow the wafers to be unloaded for some processing.

During the capsule opening process, the wafers are exposed to the

handling equipment, which ordinarily includes lubricated mechanical

elements. As a result, the wafers are subject to potential particulate and

gaseous contamination. To address this problem, it is known in the prior art to purge

contaminants in a semiconductor capsule prior to transfer of the capsule

and the wafers from one part of the wafer processing facility to another

(e.g., from an opening/unloading station in one area of the facility to a

robot assembly within a Class I clean room area) . Such capsules

typically include a complex arrangements of vents and associated valves.

Contaminants are purged from the capsule by selectively opening the

valves to introduce nitrogen in one vent and to remove it by applying

suction at the second vent. Different capsule manufacturers have

different venting arrangements. This approach requires specialized and

costly capsule construction, and it has not provided acceptable results.

Thus, a need exists for a sealed capsule opening and unloading

system that effectively purges the capsule of contaminants and that

reduces exposure of the wafers to contamination from the capsule

handling system.

BRIEF SUMMARY OF THE INVENTION

A primary object of the invention is to provide a sealed capsule

opening and unloading system that effectively purges the interior of the

capsule of contaminants prior to wafer removal from the capsule.

Another object of the invention is to provide a system for purging

the interior of a capsule that does not require specialized capsule

construction. A further object of the invention is to provide a sealed capsule

opening and unloading system that greatly reduces potential

contamination of wafers removed from the capsule.

These and other objects are accomplished by an inventive system

for transferring semiconductor wafers supported in a sealed capsule from

a first stored position to a second working position using an opening

mechanism having a load door. The capsule is positioned adjacent the

load door and a sealed environment is formed between the capsule and

the opening mechanism. The load door is then locked to the capsule

door. Next, the load door and the capsule door are moved a

predetermined distance to an intermediate position while retaining the

sealed environment between the opening mechanism and the capsule.

Thereafter, the capsule is purged with a gas. The load door and the

capsule door are then moved a further distance to open the capsule,

allowing the semiconductor wafers to be retrieved.

The foregoing has outlined some of the more pertinent objects and

features of the present invention. These objects should be construed to

be merely illustrative of some of the more prominent features and

applications of the invention. Many other beneficial results can be

attained by applying the disclosed invention in a different manner or

modifying the invention as will be described. Accordingly, other objects

and a fuller understanding of the invention may be had by referring to the

following Detailed Description of the Preferred Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and

the advantages thereof, reference should be made to the following

Detailed Description taken in connection with the accompanying

drawings, in which:

FIGURE 1 is a front perspective view of a sealed capsule opening

and unloading apparatus in accordance with the prior art;

FIGURE 2 is a rear perspective view of the FIGURE 1 apparatus;

FIGURE 3 is a front perspective view of a sealed capsule opening

and unloading apparatus in accordance with the present invention;

FIGURE 4 is a rear perspective view of the inventive apparatus;

FIGURE 5 is a top view of the inventive apparatus illustrating

purging of the capsule;

FIGURE 6 is front view of the capsule door opening mechanism in

the inventive apparatus; and

FIGURE 7 is a top view of the door opening mechanism .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A sealed capsule opening apparatus 1 0 in accordance with the

prior art is shown in FIGURES 1 and 2. The apparatus 10 is typically

located between different areas of a wafer processing facility, e.g.,

between a tool side Class 1 clean room and another processing area or

room such as a less stringent clean room. In FIGURE 1 , the less

stringent clean room is located behind the apparatus 1 0 and the Class 1

clean room into which the wafers are to be unloaded for further processing (e.g., by a robot apparatus) is in front of the apparatus 1 0.

(FIGURE 2 shows the reverse or capsule side of the apparatus 1 0.) The

goal of the apparatus 1 0 is to transfer wafers between rooms (or areas)

and limit contamination in the process.

In use, a sealed capsule 1 2 containing a plurality of wafers 14 is

placed on a movable carriage 1 6 on the apparatus 1 0. Pins 1 8 help

properly locate the capsule 1 2 on the carriage 1 6. A locking lug 20 on

the carriage 1 8 rotates to engage a slot on the bottom of the capsule 1 2,

locking it in position on the carriage 1 6. The movable carriage 1 6 is then

moved in the direction indicated by arrow 22 to a location just below a

load door 24 in the apparatus 1 0 such that the capsule door 26 contacts

the apparatus load door 24 with pads 28 on the capsule door 26 aligned

with vacuum ports 30 on the load door 24. The capsule door 26 is then

unlatched from the capsule 1 2 by lugs 32 on the load door 24 acting on

corresponding locks 34 on the capsule door 26.

As shown in FIGURE 1 , the apparatus 1 0 includes a hinged

assembly 36 pivotally mounted on a port frame 40. The hinged assembly

36 is hinged about a pivot pin 38. The load door 24 is mounted at the

upper portion 42 of the assembly 36. The capsule door 26, which is

held by vacuum to the load door 24, is pulled away from the rest of the

capsule 1 2 as the hinged assembly 36 is swung about the pin 38 away

from the port frame 40 to a retracted position indicated in phantom by

36a. Thereafter, the upper portion 42a of the hinged assembly 36,

which includes the load door 24 having the capsule door 26 attached thereto, is lowered by means of telescoping members 46 into a position

indicated by 42b. The capsule 1 2 is now open and the wafers 1 4 therein

are accessible from the interior side of the port frame 40. Thereafter,

robotic loading arms (not shown) can be used to remove the wafers 14

from the open capsule 1 2.

These steps are reversed to reload the wafers 1 4 into the capsule

1 2 to reseal the capsule 1 2 for removal from the apparatus 1 0.

As discussed, it is known in the prior art to purge contaminants in

the capsule 1 2 prior to transfer of wafers 1 4 to the tool side of the

fabrication facility. Such capsules typically include a complex

arrangement of vents and associated valves (not shown) . Contaminants

are purged from the capsule 1 2 by selectively opening the valves and

introducing nitrogen in one vent and removing it by applying suction at

the second vent. Different capsule manufacturers have different venting

arrangements. This approach requires specialized and costly capsule

construction and has not been found to provide suitable results. In

particular, when the capsule 1 2 is opened, the wafers 1 4 are exposed to

potential contamination from the lubricated mechanical elements of the

apparatus (e.g., the telescoping members 46) .

FIGURES 3-6 illustrate an inventive apparatus 1 00 for opening and

unloading sealed wafer capsules. FIGURES 3 and 4 illustrate front and

rear sides of the apparatus, respectively. As with the prior art apparatus

1 0, the apparatus 1 00 will ordinarily be located between different areas

or rooms of a wafer fabrication facility. For example, the apparatus 1 00 may be located to transfer wafers from a clean room processing area to a

Class 1 clean room having a nitrogen environment and suitable tools

(e.g., a robot apparatus for removing the wafers from the capsule for

subsequent processing).

The apparatus 100 includes a frame 102 containing a conventional

purging system described in detail below with respect to FIGURE 5 . A

platform 104 for supporting the capsule 106 extends outwardly from the

frame 102 on the rear or capsule side of the apparatus 100. The

platform 104 includes a movable carriage 108 therein.

The front side of the apparatus 100 shown in FIGURE 3 includes a

transfer chamber member 110 and a mechanism 112 to lower the

transfer chamber 110 as will be described in detail below. The movable

parts of the mechanism 112 are sealed as shown in the drawing to

ensure against contamination. A load door 114 (shown in FIGURE 5) is

located adjacent to the transfer chamber member 110.

In use, a sealed capsule or cassette 106 containing wafers 111 is

placed on the platform 104. Pins 116 on the platform 104 are preferably

used to help properly locate the capsule 106 on the movable carriage

108. The capsule 106 is preferably locked to the carriage 108 by means

of a locking lug 120. The capsule 106 is moved by the carriage 108

toward the load door 114, and a seal 122 is provided between the outer

flange 124 of the capsule 106 and the frame 102. The seal 122 extends

around the periphery of the capsule door 126. Next, the interior of the capsule 1 06 is purged, preferably with

nitrogen gas. The present invention accomplishes purging with greater

efficiently and without requiring that the capsule 1 06 have special purge

vents. Briefly, the load door 1 1 4 of the apparatus 1 00 is locked against

the capsule door 1 26 such that these doors may move together. Then,

the capsule door 1 26 is partially opened to allow the interior of the

capsule 1 06 to be purged, e.g., with a nitrogen gas. The particular gas

used to purge the capsule (and the transfer mechanism) is not an aspect

of the present invention and any suitable gas can be used for this

purpose. Nitrogen is preferred, however, given the nitrogen environment

of the tool side clean room area. After purging occurs, the load door

(together with the attached capsule door) is fully retracted into the

chamber 1 28 of the transfer chamber member 1 1 0. The transfer

chamber member 1 1 0 is then lowered out of the way, thereby exposing

the interior of the capsule and allowing the wafers in the capsule 1 06 to

be accessed (e.g., using a robot arm assembly situated on the tool side) .

Figure 5 shows the capsule door 1 26 is its partially-opened state,

i.e., in an intermediate position. When in this position, the inlet and

outlet ports 1 30, 1 32 of the purging system are open to the interior of

the capsule 1 06 to allow purging. Note that the seal 1 22 between the

capsule 1 06 and the frame 1 02 prevents leakage of the purging gas.

FIGURES 5-7 show how the capsule door 1 26 is locked, partially

opened (in the intermediate position), and then fully retracted. Element

1 34 of the load door 1 14 (shown in FIGURE 6) mates with a corresponding slot in the capsule door 1 26. Then, a linkage 1 36 in the

load door 1 1 4 is activated (moved left to right in FIGURE 6) to lock the

capsule door 1 26 to the load door 1 1 4. Cam 1 38 in the load door 1 1 4

rotates 90 degrees, causing cam follower 140 to move linearly by a

predetermined distance. This causes the load door 1 1 4 (with the capsule

door 1 26 locked thereto) to move into the intermediate position shown in

FIGURE 5. Such movement occurs via guide rails 140. Then the purging

takes place as shown in FIGURE 5 with the nitrogen introduced through

the inlet port 1 30 and removed under suction through the outlet port

1 32. Thereafter, the cam 1 38 is rotated another 90 degrees, causing the

load door 1 1 4 (with the capsule door 1 26 locked thereto) to continue

moving back into the chamber 1 28 of the transfer chamber member 1 1 0.

Thereafter, the mechanism 1 1 2 is used to move the transfer chamber

member 1 1 0, opening seal 1 44 (shown in FIGURE 5) which exists

between the frame 1 02 and the transfer chamber member 1 1 0. The

transfer chamber member 1 1 0 is then lowered out of the way so a robot

arm (not shown) can remove the wafers 1 1 1 in the capsule 1 06.

One of ordinary skill will appreciate that the frame 1 02 is smaller

than the corresponding frame in known prior art systems because of the

more compact mechanism 1 1 2.

Having thus described our invention, what we claim as new and

desire to secure by Letters Patent is set forth in the following claims.

Claims

1 . A method of transferring a semiconductor wafer supported in a

sealed capsule from a first stored position to a second working position

using an opening mechanism having a load door, the capsule having a

capsule door, comprising the steps of:

(a) positioning the capsule adjacent the load door to form a sealed

environment between the capsule and the opening mechanism;

(b) locking the load door to the capsule door;

(c) moving the load door and the capsule door a predetermined

distance while retaining a sealed environment between the opening

mechanism and the capsule;

(d) purging the capsule with a gas;

(e) moving the load door and the capsule door a further distance to

expose the wafer; and

(f) retrieving the semiconductor wafer.

2. The method of Claim 1 further including the step of lowering

the load door and the capsule door away from the capsule after step (e) .

3. An apparatus for opening a sealed capsule containing wafers,

the capsule having a capsule door, comprising:

means for providing a seal between the capsule and the apparatus

around the capsule door; means for moving the capsule door to an intermediate position while

maintaining a sealed environment between the capsule and the apparatus;

means for purging the capsule while the capsule door is in said

intermediate position; and

means for then moving the capsule door to an opened position to

enable access to the wafers in the capsule.