Patent Document

CROSS REFERENCE TO A RELATED PATENT APPLICATION 
     This patent application claims as priority of the filing date of Provisional Patent Application Ser. No. 60/142,731 filed on Jul. 8, 1999, and entitled “Apparatus and Method for Inserting a Wafer, Substrate or Other Articles into a Process Module”, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to an apparatus and method for inserting a wafer, substrate or other article into a process module, and specifically, to an apparatus and method for inserting a wafer into a process module that provides a telescoping loading arm having a relatively long extension while requiring a relatively small footprint. 
     BACKGROUND OF THE INVENTION 
     A semiconductor wafer electroplating apparatus typically performs a wafer plating process within an enclosed and self-contained environment. One reason for this is to prevent contaminants from entering a wafer electroplating apparatus and adversely affecting the plating process. Another reason is typically toxic/corrosive fluids and gasses are involved in the plating process and containing them within an enclosed and self-contained environment is an environmental and safety requirement. Yet another reason for an enclosed and self-contained environment is to achieve a better control of the quantity, pressure, volume and other parameters of the fluids and gasses involved in the plating process. 
     Because of the enclosed and self-contained environment of a wafer electroplating apparatus, a wafer needs to be inserted into the plating apparatus to set the wafer at the plating process staging area. In many cases, plating apparatuses or other process modules are relatively large in size because they have to house electronics, mechanical parts, tubing, internal chambers, sumps, and other components. Accordingly, often a wafer needs to travel a long distance from outside of the process module into the process staging area of the module. Because of the relatively light weight characteristic of wafer, the transporting of the wafer into and from a process module should be performed with substantial control to avoid dislocation of the wafer from its appropriate position. Thus, there is a need for a system and method of transporting a wafer, substrate, or other articles into and out of a process module with substantial control, even though the wafer may travel a relatively long distance. 
     Another problem with inserting a wafer, substrate or other article into a plating apparatus or other process module arises from the need or desire to reduce the size of these machines. Since clean room real estate is a valuable commodity, there is a need to make efficient use of space. Thus, the sizes of plating apparatuses and other process modules have been substantially reduced in recent years. Because these process modules often house a substantial amount of components, process modules are becoming more crowded internally with components. As a result, it is sometimes difficult to insert a wafer, substrate or other article into a process module because of a relatively small clearance requirement. Thus, there is a need for a system and method of transporting a wafer, substrate, or other article into and out of a process module that has a relatively low profile (thickness) to allow an article to be inserted within a relatively small clearance. 
     Yet another problem with inserting a wafer, substrate or other article into a plating apparatus or other process module arises from the relatively high precision requirement in placing a wafer into a process staging area. A process staging area for a wafer electroplating apparatus includes cathode contacts that electrically connect to the top surface of the wafer, typically at very precise locations. Often, wafer electroplating apparatus include alignment mechanism so that the wafer is precisely placed in the process staging area. However, typically the wafer has to be transported within an alignment zone for the alignment mechanism to work properly. This still may require a relatively high level of precision, especially given the long distance the wafer has to travel from outside to the inside of the process module. Thus, there is a need for a system and method of transporting a wafer, substrate, or other article into and out of a process module with substantial precision. 
     In summary, there is a need for a system and method of transporting a wafer, substrate, or other article into and out of a process module that (1) has substantial control in inserting an article into a process module even though the article has to travel a relatively long distance, that (2) has a relatively low profile (thickness) to allow an article to be inserted within a relatively small clearance, and that (3) has substantial precision in placing of the article. Such a system and method is provided herein in accordance with the invention. 
     SUMMARY OF THE INVENTION 
     An aspect of the invention includes an apparatus for inserting and removing a wafer into and from a plating apparatus, comprising an elongated primary arm including a wafer seat for supporting the wafer, an elongated secondary arm for supporting the primary arm, and a mounting surface for supporting the secondary arm. The apparatus further includes a drive band mechanically coupled to the primary arm for causing the movement thereof. The drive band includes a portion wound around a drum that is driven by a motor. The motor causes the drive band to move the primary arm along an axis between a retracted position wherein the primary arm, the secondary arm, and the mounting surface are in a stacked relationship, and an extended position wherein the secondary arm protrudes from the mounting surface along the axis, and the primary arm protrudes from the secondary arm along the axis. 
     The drive band is preferably made out of stainless steel and has a concaveshaped cross-section for providing improved strength and rigidity during the extensions of the primary and secondary arms. The motor, which is preferably a stepper motor, provides substantial control in extending and retracting the primary and secondary arms. The mounting surface includes horizontally-oriented opposing rollers for guiding the movement of the secondary arm along the axis, and the secondary arm likewise includes horizontally-oriented opposing rollers for guiding the movement of the primary arm arm along the axis. Both the primary and secondary arm are comprised of a relatively thin plate, and this feature in combination with the horizontally-oriented rollers, gives the apparatus a low-profile characteristic to allow the wafer to be inserted within a relatively small clearance. 
     Another aspect of the invention includes a method of inserting and removing an article into a process staging area of a process module using an apparatus that includes a primary arm having a seat supporting the article, a secondary arm that supports the primary arm, and a mounting surface that supports the secondary arm. The method comprises a first step of moving the primary arm along an axis from a retracted position to a first intermediate position. In the retracted position, the primary arm, the secondary arm, and the mounting surface are in a stacked relationship. Also in this position, the article seated on the primary arm remains outside of the process staging area. In the first intermediate position, the secondary arm and the mounting surface are in a stacked relationship and the primary arm protrudes from the secondary arm along the axis. 
     The second step is moving the primary and secondary arms together along the axis from the first intermediate position to an extended position. In the extended position, the secondary arm protrudes from the mounting surface along the axis and the primary arm protrudes from the secondary arm along the axis. Also in this position, the article is now proximate the process staging area. The third step is moving the primary arm along the axis from the extended position to a second intermediate position. In the second intermediate position, the primary arm and the secondary arm are in a stack relationship, but both protrude from the mouting surface along the axis. The final step is moving the primary and secondary arms together along the axis from the second intermediate position to the retracted position wherein the article is again outside of the process staging area. 
     In summary, the apparatus and method is characterized by having an extension arm that has a low profile (thickness), is light weight, and has strength and rigidity when it is extended to provide a controlled insertion of the article into the process module. Although the insertion of a wafer is used to illustrate the invention, it shall be understood that other articles, including substrates can also be inserted into a process module in accordance with the invention. 
     Other aspects, features, and techniques of the invention become apparent in view of the following detailed discussion of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B illustrate top and side views of a wafer inserting apparatus in accordance with the invention; 
     FIG. 2 illustrates a perspective view of the wafer inserting apparatus in accordance with the invention; 
     FIG. 3 illustrates a top view of the wafer inserting apparatus in its fully retracted position in accordance with the invention; 
     FIG. 4 illustrates a front view of a portion of the wafer inserting apparatus in accordance with the invention; and 
     FIG. 5 illustrates a rear view of a portion of the wafer inserting apparatus in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1-5, a wafer inserting apparatus  100  in accordance with the invention is shown. The wafer inserting apparatus  100  comprises a primary arm  102  for supporting a wafer to be inserted into a process module (not shown). The primary arm  102  is mechanically coupled to a secondary arm  104  for extending the primary arm  102 , and mechanically coupled to a drive band  106  for extending and retracting the primary and secondary arms  102  and  104 . The drive band  106  includes a portion that is coiled around a drum  108  that is rotatably driven by a stepper motor  110 . The stepper motor  110  is mounted to an L-shaped bracket  113  that is, in turn, mounted on a mounting plate  112 . 
     The wafer inserting apparatus  100  also comprises a pneumatic cylinder  114  for raising and lowering the primary arm  102 . The pneumatic cylinder  114  is mounted to the underside of the mounting plate  112  and to a fixed mounting base  116  which is, in turn, mounted to a second fixed horizontal mounting plate  118 . The wafer inserting apparatus  100  also includes a guide cylinder/shaft  120  for guiding the vertical movement and providing lateral restraint of the mounting plate  112  as it is vertically positioned by the pneumatic cylinder  114 . The horizontal mounting plate  118  is mechanically coupled to a fixed vertical plate  122  which is, in turn, coupled to an additional fixed vertical plate  124  used for securely mounting to the process module. The wafer inserting apparatus  100  further includes a cover  126  for enclosing the stepper motor  110 , the pneumatic cylinder  114  and the guide cylinder  120 . 
     In more detail, the primary arm  102  comprises a thin plate  130  preferably formed of stainless steel. A wafer seat  132  is mounted on the thin plate  130  by suitable attachment means, such as screws  133 . In the preferred embodiment, the wafer seat  132  is formed of polypropylene material or other suitable plastic material. The wafer seat  132  includes a pair of ledges  134  situated on opposing sides of the wafer seat  132  for wafer alignment purpose and to keep the wafer situated on the wafer seat  132  during movement of the primary arm  102 . 
     The primary arm  102  is connected to the drive band  106  by suitable attachment means, such as screw  136 . The primary arm  102  further includes a contact surface  138  that makes contact with a contact pin  154  mounted on the secondary arm  104  when the primary arm  102  is retracted. This action causes the secondary arm  104  to retract when the primary arm  102  is retracted, as will be explained in more detail later. The primary arm  102  also includes at least one contact extension  140  (preferably two) that makes contact with rollers  152  mounted on the secondary arm  104  when the primary arm  102  is extended. This action causes the secondary arm  104  to extend when the primary arm  102  is extended, as will be explained in more detail later. The thin plate  130  may include one or more holes  142  to reduce the weight thereof. The thin plate  130  also includes a track  144  throughout its opposing edges to serve as a track for guiding the movement of the primary arm  102 . In the preferred embodiment, the track  144  is configured into a v-groove. 
     The secondary arm also comprises a thin plate  150  preferably formed of stainless steel. The thin plate  150  includes a plurality of rollers  152 , preferably four, horizontally mounted thereon. The rollers  152  mates with the track  144  of the primary arm  102  for guiding the sliding movement thereof. The rear rollers  152  of the secondary arm  104  makes contact with the contact extension  140  when the primary arm  102  is fully extended, to cause the extension of the secondary arm  104 . The secondary arm  104  further includes a contact pin  154  to make contact with the contact surface  138  of the primary arm  102  when it is retracted, in order to retract the secondary arm  104 . The secondary arm  104  also includes a contact extension  155  to make contact with horizontally-mounted rollers  159  on the mounting plate  112  when it is extended, in order to stop the secondary arm  104  from further extending. Additionally, the secondary arm  104  includes a contact surface  157  which makes contact with a contact pin  161  on the mounting plate  112  when the secondary arm  104  is fully retracted. 
     The thin plate  150  of the secondary arm  104  may include one or more holes  156  to reduce the weight thereof. In addition, the thin plate  150  includes a track  158  throughout its opposing edges to serve as a track for guiding the movement of the secondary arm  104 . In the preferred embodiment, the track is configured into v-groove track which mates with the horizontally-mounted rollers  159  on the mounting plate  112 . 
     The drive band  106  is formed of a pliable material, preferably of stainless steel. The drive band  106  has a concave downward cross-section to improve the strength and rigidity of the band during its extension. An end of the drive band  106  is attached to the primary arm  102  by suitable attachment means, such as screw  136 . From that end, the drive band  106  extends rearward to a 90-degree guide  160  and then downward to the drum  108 , where it is coiled around and attached thereto. The 90-degree guide  160  is mounted on the top side of the mounting plate  112 . 
     Referring specifically to FIGS. 2-3, the wafer inserting apparatus  100  further includes a platform  170  on which the wafer is placed before it is inserted into the process module. The platform  170  includes a slot  172  extending from the front to the rear of the apparatus  100  for housing the base plate rollers  159 , secondary arm  104  including its rollers  152 , primary arm  102  including the wafer seat  132 , and the drive band  106 . The platform  170  also includes a pair of opposing grooves  174  for providing clearances to the underside of the wafer for a wafer holding device, such as a pair of tweezers or a wand with suction cups. An optical sensor  176  may be mounted on the platform  170  to sense the presence of a wafer and relay that information to a controller (not shown). The controller prevents the extension of the arms  102  and  104  when there is no wafer sensed by the optical sensor  176 . 
     The wafer inserting apparatus  100  further includes a top cover  180  mounted to the platform  170 . The top cover  180  is preferably configured into a rear section  180   a  and a front section  180   b.  The front and rear sections  180   a-b  of the top cover  180  includes opposing curved sides  182   a-b  which outlines a portion of the perimeter of a wafer when seated on the platform  170 , and is used to assist in properly positioning the wafer on the wafer seat  132 . The rear section  180   a  of the top cover  180  includes a rear slot  184   a  situated between the top cover  180  and the mounting plate  112  to provide spacing for the band drive  106  and the 90-degree guide  160 . The front section  180   b  of the top cover  180  also includes a much wider front slot  184   b  situated between the top cover  180  and the platform  170  to provide spacing for the band drive  106 , the wafer seat  132 , and the wafer. 
     In operation, prior to inserting the wafer into the process module, the wafer inserting apparatus  100  is configured in a manner that both the primary and secondary arms  102  and  104  are in their fully retracted positions. This position is shown in FIG.  3 . The wafer is then positioned within the wafer alignment curved sides  182   a-b  of the top cover and seated on the wafer seat  132 . The stepper motor  110  is then actuated to cause the drive band  106  to move in a forward direction, thereby extending the primary arm  102 . During the extension of the primary arm  102 , its contact extension  140  makes contact with the rear rollers  152  of the secondary arm  104  and forces the secondary arm  104  to extend with the primary arm  102 . The stepper motor  110  continues to be actuated until the secondary arm  104  is fully extended by having its contact extension  155  make contact with the rear rollers  159 . 
     During the retraction of the primary and secondary arms  102  and  104 , the stepper motor  110  is actuated to cause the drive band  106  to move in a rearward direction, thereby retracting the primary arm  102 . During the retraction of the primary arm  102 , its contact surface  138  makes contact with the contact pin  154  of the secondary arm  104 , and thereby causes the retraction of the secondary arm  104  along with the primary arm  102 . The stepper motor  110  continues to be actuated until the contact surface  157  of the secondary arm  104  makes contact with the contact pin  161  of the mounting plate  112 . 
     During the extension and retraction of the primary and secondary arms  102  and  104 , it may be necessary to vertically position the primary arm  102  properly within the process module. To do so, the pneumatic actuator  114  may be actuated to position the primary arm  102  to a desired vertical position. The shaft/cylinder  120  guides the vertical movement of the mounting plate  112  and laterally restraints it. 
     The wafer inserting apparatus  100  and corresponding methods achieves a relatively long extension with the use of the primary and secondary arms  102  and  104  as well as their drive band for causing their extensions. The wafer inserting apparatus  100  and corresponding methods also achieves a relatively small footprint to implement since the primary and secondary arms  102  and  104  overlie each other when they are fully retracted (See FIG.  3 ). Additionally, the wafer inserting apparatus  100  and corresponding methods provides extension arms  102  and  104  that have a low profile (thickness) due to the relatively flat configuration of the arms  102  and  104  and the drive band  106 , as well as the horizontally-mounted rollers  152  and  159 . In addition, the arms  102  and  104  are light weight due to the plurality of holes  142  and  158 . Furthermore, the arms  102  and  104  and the drive band  106  have strength and rigidity during its extension due to its stainless steel composition, as well as the concave downward cross-section of the drive band  106 . 
     Although a stepper motor  110  is used to drive the drive band  106 , it shall be understood that other types of motors can be used, including direct current (DC) motors, alternating current (AC) motors, synchronous motors, asynchronous motors, and so on. The particular type of motor used to drive the drive band  106  is not critical to the invention. Also, although the pneumatic cylinder  114  is used to position the primary arm  102  to a desired vertical position, it shall be understood that other devices, such as an electric motor can be used to cause the vertical movement of the primary arm  102 . Furthermore, the primary and secondary arms  102  and  104 , and the drive band  106  can be made out of other material other than stainless steel, as long as it provides strength and rigidity during their extension. 
     The foregoing description of the exemplary embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not with this detailed description.

Technology Category: 5