PHOTOMASK POD, PHOTOMASK TRANSPORT POD AND SUPPORTER THEREOF
A photomask pod and a photomask transport pod are provided for preventing particles in the environment from defiling a photomask as well as charge accumulation on the photomask from causing ESD damage. The photomask pod comprises two covers and the supporters or retainers on at least one of the two covers are made of a static dissipative material, which facilitates reducing charge accumulation and protecting the photomask from ESD damage.
1. Field of the Invention
The present invention relates to photomask pods and photomask transport pods and, more particularly, to a photomask pod and a photomask transport pod which can prevent damage caused by ESD.
2. Description of the Related Art
In the rapidly developing semiconductor technology, optical lithography plays an important role and wherever pattern definition is conducted, optical lithography is requisite. As to the application of optical lithography relating to semiconductors, a designed circuit pattern is used to produce a light-transparent photomask. Based on the principle of exposure, after a light passes through the photomask to be projected on a silicon wafer, the circuit pattern formed on the photomask can be exposed onto the silicon wafer. Since any dust (such as particles, powders or an organic material) can adversely affect the quality of such projected pattern, the photomask used to produce the pattern on the silicon wafers is required with absolute cleanness. Thus, clean rooms are typically employed in general wafer processes for preventing particles in the air from defiling photomasks and wafers. However, absolute dustless environment is inaccessible even in known clean rooms. Hence, reticle pods that facilitate preventing defilement are implemented in current semiconductor processes for the purpose of storage and transportation of photomasks so as to ensure cleanness of the photomasks.
Conventional photomask pods are generally made of macromolecular materials, which possess the advantages of easy forming, inexpensiveness and the ability to form transparency. Such macromolecular materials, which are insulating and have high surface resistivity, are liable to induce static due to friction and separation. Especially, in the low-moisture environment of a clean room, photomask pods made of such macromolecular materials are apt to produce and accumulate charges thereon. Additionally, when a photomask is placed in or taken out from a photomask pod, static may easily occur on the surface of the photomask owing to friction. Static on the photomask is attractive to particles in the air and may, even worse, cause electrostatic discharge (ESD) on metal wires of the photomask. Transient currents induced by ESD can bring sparks or arcs that come along with powerful currents and high heat. As such powerful currents and high heat oxidize and melt the metal wires of the photomask, the pattern on the photomask is consequently deformed.
Many solutions have been introduced to eliminate ESD. The primary solution is to manage the operational environment with proper atmospheric moisture. Clothes having grounding effects for staff and ion fans may be also helpful to eliminate environmental static. However, there are countless factors in the operational environment, and it is actually impossible to completely protect photomasks from being damaged by static.
An alternative solution is to change the material of the components composing a photomask pod, as disclosed in U.S. Pat. No. 6,513,654, wherein a supporter having a grounding effect is provided so that when the photomask pod contacts a corresponding station, the supporter helps to conduct out charges on the photomask. Furthermore, another solution, provided by U.S. Pat. No. 6,247,599, involves equipping a metal layer on a bottom plate, a cover, or a handle of the photomask pod so as to reduce charge accumulation. While all the aforementioned solutions are dependent on grounded electrically conductive components to release charges, it is to be noted that when static is released by such electrically conductive components, currents are unavoidably generated and discharge can still occur to damage the photomask.
Therefore, the present invention provides novel supporters or retainers to remedy the above defects of the prior arts.
SUMMARY OF THE INVENTIONTo overcome the aforementioned defects of the prior arts, the present invention provides a photomask pod which has supporters or retainers made of a particular material. In the present invention, the supporters or retainers are made of a static dissipative material so that even when charges are generated on the static dissipative material because of friction, an adjacent metal material can instantly conduct out the charges so as to eliminate charge accumulation and ESD.
It is one objective of the present invention to provide a supporter of a mask, which is made of a static dissipative material to reduce charge accumulation and to protect a photomask from being damaged by static.
It is another objective of the present invention to provide a supporter of a photomask, which is made of a static dissipative material to continuously conduct out charges so as to protect a photomask from being damaged by high heat resulted from transient discharge.
It is another objective of the present invention to provide a retainer of photomask, which is made of a static dissipative material to reduce charge accumulation and to protect a photomask from being damaged by static.
It is another objective of the present invention to provide a retainer of a photomask, which is made of a static dissipative material to continuously conduct out charges so as to protect a photomask from being damaged by high heat resulted from transient discharge.
The present invention discloses a photomask pod and a photomask transport pod with supporters and retainers which directly contact a photomask and are made of a static dissipative material so as to provide a way for dissipating static. The static dissipative material has a property between conductive and non-conductive. Since the static dissipative material features a slow conductive velocity, discharge is not liable to happen between the supporters or the retainers and the photomask or the photomask pod. Consequently, the photomask can be free from the influence of heat generated by discharge so that the present invention provides superior protection to the photomask while shielding is also presented. As a result, the photomask is protected from the risk of being damaged.
The invention as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein
It is to be stated at first that essential components and combining means among the components of the disclosed supporters and retainers made of a static dissipative material in the present invention are well known in the art and need not be discussed at length herein. Meanwhile, the basic structure of photomasks pod and the principle where photomask pods are based on are also well known by those skilled in the art and need not be disclosed in the present invention. Beside, the accompanying drawings are provided for illustration and are not and need not to be drawn in scale.
In addition,
One additional embodiment of the present invention is herein provided for illustrating the plural retainers or supporters settled in the photomask transport pod 100. Therein, a photomask transport pod 100 comprises a top cover 102 and a bottom plate 104, which can be assembled to enclose an inner space to accommodate a photomask 114. The photomask transport pod 100 may be made of metal. Alternatively, a metal liner may be settled in the photomask transport pod 100 to provide the shielding effect so as to insulate an extrinsic interference. A plurality of supporters 112 in the photomask pod 100 may be provided in the forms of the first supporter 112, the second supporter 200 and the third supporter 300. The first supporters 112 are arranged on the bottom plate 104 and the second supporters 200 as well as the third supporters 300 are deposited on the top cover 102. At four corners of the top cover 102, the plural second supporters 200 or the third supporters 300 are provided and are detachably fastened to the corners of the top cover 102 by the connecting components 218 or the one or plural supporting points 304 of the base 302 thereof. The supporters 300 may be further equipped with a plurality of pressing surfaces 308 and propping surfaces 310 to fix and support the photomask 114. When placed in the bottom plate 104 of the photomask transport pod 100, the photomask 114 is supported by the plural retainers 110 as well as the first supporters 112 and is retained on the bottom plate 104 by the retainers 110. When the top cover 102 is assembled to the bottom plate 104, since the second supporters 200 are provided at the opening of a reversed-U shaped structure of the top cover 102 facing the bottom plate 104, the second inclined surfaces 206 of the second supporters 200 helps the photomask 114 to be smoothly guided into the position of the reversed-U shaped structure. Meanwhile, because the third supporter 300 are provided at the corners of the top cover 102, after being guided by the second inclined surfaces 206 of the second supporters 200 to the proper position, the photomask 114 is further jointly supported and fixed by the upper and lower fastening pieces 210 and 212 of the second supporters 200 and the pressing and propping surfaces 308 and 310 on the flexible bent component 306 of the plural third supporters 300. Besides, since the photomask 114 directly contact with the first, the second and the third supporters 112, 200 and 300, the static dissipative material of these supporters with the surface resistivity ranging from about 104 to about 1011Ω helps to continuously conduct out charges so as to protect the photomask from being damaged by high heat resulted from transient discharge. Since charge accumulation is reduced, the photomask is protected from being damaged by static.
All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.
From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the scope of the following claims.
Claims
1. A photomask pod comprising:
- a first cover, and
- a second cover, which is assembled to the first cover so as to enclose an inner space for accommodating at lease one photomask;
- wherein at least one of the first and second covers has a body with a plurality of supporters or retainers at a surface facing the inner space, in which the supporters or retainers are made of a static dissipative material.
2. The photomask pod of claim 1 wherein the static dissipative material has a surface resistivity ranging from about 104 to about 1011Ω.
3. The photomask pod of claim 1 wherein the supporters and retainers are made of different materials.
4. The photomask pod of claim 1 wherein the supporters and retainers are made of an identical material.
5. The photomask pod of claim 1 wherein a conductive panel is provided at the surface of the body facing the inner space, and the supporters are deposited on the conductive panel and electrically connect with the conductive panel.
6. The photomask pod of claim 1 wherein the first cover or the second cover is made of metal.
7. The photomask pod of claim 1 wherein each of the supporters comprises:
- a planar base connecting with a first inclined surface that further connects with a second inclined surface so that the planar base, the first inclined surface and the second inclined surface form as the supporter integrally, and two first openings are provided near both lateral sides of the supporter wherein each of the first openings is equipped with an upper fastening piece and a lower fastening piece.
8. The photomask pod of claim 1 wherein each of the supporters comprises:
- a base, which affixes to each corners of the upper cover of the photomask pod via a plurality of supporting points, and
- a flexible bent component, having one end which connects to the base and has an opposing end flexibly suspending between the plurality of supporting points, which further comprises a propping surface and a pressing surface;
- wherein when the photomask pod encloses a photomask, the propping surface and the pressing surface of the flexible bent component contact the photomask so as to fix it.
9. The photomask pod of claim 1 wherein the photomask pod can also be a photomask transport pod.
10. A photomask pod comprising:
- a first cover,
- a second cover, which is assembled to the first cover so as to enclose an inner space for accommodating at least one photomask and at least one of the first and second covers has a body,
- a plurality of retainers, which is provided at a surface of the body facing the inner space, and
- a plurality of supporters, which is provided at the surface of the body facing the inner space and made of a static dissipative material;
- wherein the plurality of retainers and the plurality of supporters are formed by multi-component injection molding method and then combined mutually.
11. The photomask pod of claim 10 wherein the static dissipative material has a surface resistivity ranging from about 104 to about 1011Ω.
12. The photomask pod of claim 10 wherein the photomask pod can also be a photomask transport pod.
13. A supporter comprising:
- a planar base connecting with a first inclined surface that further connects with a second inclined surface so that the planar base, the first inclined surface, and second inclined surface form as the supporter integrally, and two first openings are provided near both lateral sides of the supporter and each of the first openings is equipped with an upper fastening piece and a lower fastening piece wherein the supporter is partially or entirely made of a static dissipative material.
14. The supporter of claim 13 wherein the static dissipative material has a surface resistivity ranging from about 104 to about 1011Ω.
15. The supporter of claim 14 wherein the static dissipative material is polyetheretherketone.
16. A supporter comprising:
- a base, which affixes to each corner of an upper cover of a photomask pod via a plurality of supporting points, and
- a flexible bent component, which has one end connecting to the base and an opposing end flexibly suspending upon the plurality of supporting points, which further comprises a propping surface and a pressing surface;
- wherein when the photomask transport pod encloses a photomask, the propping surface and the pressing surface of the flexible bent component contact the photomask so as to fix it, in which the supporter is partially or entirely made of a static dissipative material.
17. The supporter of claim 16 wherein the static dissipative material has a surface resistivity ranging from about 104 to about 1011Ω.
18. The supporter of claim 17 wherein the static dissipative material is polyetheretherketone.
Type: Application
Filed: Apr 25, 2008
Publication Date: Feb 12, 2009
Inventor: Chien-Feng WANG (Shulin City)
Application Number: 12/110,276
International Classification: B65D 85/00 (20060101);