Method for cleaning semiconductor wafers in a cleaning line - Patents.com

Abstract

1. A method for cleaning semiconductor wafers in a cleaning line comprising at least two cleaning modules, wherein vertically oriented semiconductor wafers are successively treated with liquids of respective cleaning steps during the cleaning steps, characterized in that at least one gripping system comprising two adjacent manipulators is moved over one of the cleaning modules, one manipulator being moved through a slot in a cover of the one cleaning module for loading or picking up the semiconductor wafer, and the other manipulator being positioned between the slot in the cover of the one cleaning module and the slot in the cover of the other cleaning module.

Description

[Technical field]

[0001] The present invention relates to a method for cleaning semiconductor wafers in a cleaning line comprising at least two cleaning modules, in which vertically oriented semiconductor wafers are successively treated with liquids of the respective cleaning steps during the cleaning steps, and in which at least one gripping system comprising two adjacent manipulators is moved over one of the cleaning modules, one manipulator being moved through a slot in a cover of that one cleaning module for loading or picking up a semiconductor wafer. [Background technology]

[0002] Conventional technology / challenges US Patent Publication No. 20030200988 describes a modular substrate cleaning system in which multiple semiconductor wafers can undergo individual wafer cleaning simultaneously in an indexed sequence in successive cleaning modules of a cleaning line.

[0003] The drawback of this is that it is less flexible. US Patent Application Publication No. 20060254715 describes a method in which semiconductor wafers are transferred between successively arranged cleaning modules of a cleaning line so that the semiconductor wafers undergo individual wafer cleaning in each of the cleaning modules, during which at least one of two manipulators is lowered into the cleaning module to load or pick up the semiconductor wafer. Summary of the Invention [Problem to be solved by the invention]

[0004] The drawback of this is that cross-contamination can occur, jeopardizing the success of the cleaning process.

[0005] It is an object of the present invention to increase the efficiency of cleaning of semiconductor wafers in a cleaning line and to avoid situations in which the semiconductor wafers become contaminated during handling during the cleaning process. [Means for solving the problem]

[0006] The object of the present invention is achieved by a method for cleaning semiconductor wafers in a cleaning line comprising at least two cleaning modules, characterized in that vertically oriented semiconductor wafers are successively treated with the liquids of the respective cleaning steps during the cleaning steps, and at least one gripping system comprising two adjacent manipulators is moved over one of the cleaning modules, one manipulator being moved through a slot in the cover of that one cleaning module for loading or picking up the semiconductor wafer, and the other manipulator being positioned between the slot in the cover of that one cleaning module and the slot in the cover of the other cleaning module.

[0007] The arrangement of the manipulators avoids a situation in which one manipulator is moved over the cleaning module and liquid drips from the other manipulator or from the semiconductor wafer held by the other manipulator while the other manipulator is being lowered into the cleaning module, which could cause cross-contamination.

[0008] The cleaning line comprises at least one gripping system to which two manipulators are fixed. The two manipulators are arranged at a certain distance from each other. Preferably, there is at least one further gripping system with one or two manipulators. Preferably, the further gripping system with manipulators is used to transport the semiconductor wafers to a dryer after the last cleaning step.

[0009] The method is preferably used to clean semiconductor wafers after polishing by CMP (chemical mechanical polishing). After CMP, the semiconductor wafer goes through a sequence of cleaning steps. During each cleaning step, the semiconductor wafer undergoes an individual wafer treatment with a liquid cleaning agent in a cleaning module. During this process, the semiconductor wafer is treated with the cleaning agent in a vertical position. If necessary, it stands on a roll and is rotated about its center. The order of the sequence may, but does not have to, correspond to the order of arrangement of the cleaning modules. Each cleaning module is designed to perform either a bath cleaning, a spray cleaning, a brush cleaning, or a combination of spray cleaning and brush cleaning. During bath cleaning, the semiconductor wafer is immersed in the cleaning agent, during spray cleaning, the cleaning agent is sprayed on the front and rear faces of the semiconductor wafer, and during brush cleaning, the cleaning agent is distributed on the front and rear faces of the semiconductor wafer by a rotating brush. The cleaning liquid can be supplied via a roll or a separate spray nozzle. Cleaning in the cleaning bath can be assisted by irradiation with megasonic waves.

[0010] Each cleaning module of the cleaning line is provided with a cover incorporating a slot. To load a semiconductor wafer into one of the cleaning modules or to remove a semiconductor wafer from one of the cleaning modules, one of the two manipulators of the gripping system is moved through the slot to this one cleaning module. To avoid cross-contamination by dripping liquid, the other manipulator of the gripping system remains during this process in a position that makes it impossible for liquid dripping from the other manipulator or the semiconductor wafer held by it to fall through the slot of the cover into this one cleaning module. This position is the placement of the second manipulator between the slot in the cover of this one cleaning module and the slot in the cover of the adjacent cleaning module. The other manipulator is preferably placed above the cover of this one cleaning module, but not above the slot of the cover of this one cleaning module. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view of a polishing station with an associated cleaning station suitable for carrying out the present method, the structure of which is based on the apparatus shown in US Patent Publication No. 20060254715. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS ACCORDING TO THE PRESENT PRESENT EMBODIMENT The following description will be made with reference to the drawings, in which the illustrations are limited to those features important to the understanding of the invention.

[0013] FIG. 1 shows diagrammatically the arrangement of a polishing station 1 and a cleaning station 2 with three cleaning modules 3a-3c. These cleaning modules and a dryer 4 are part of a cleaning line in which semiconductor wafers are cleaned and dried in the polishing station 1 after CMP has been completed. The polishing station comprises at least one polishing head, which presses the semiconductor wafer to be polished against a polishing cloth (not shown) during polishing. A robot, which transports the polished semiconductor wafer from the polishing station to the cleaning station, and a device for intermediate storage of the semiconductor wafer are also not shown.

[0014] The cleaning line comprises a guide 5 for a gripping system 6 to which two manipulators 7 and 8 are fixed. The semiconductor wafer to be cleaned is held by one of the two manipulators 7, 8 and is lowered from a position above one of the cleaning modules 3a-3c into the cleaning module and loaded into the cleaning module. The semiconductor wafer cleaned in one of the cleaning modules is picked up in the cleaning module by one of the two manipulators 7, 8 and lifted out of the cleaning module. There is preferably a further gripping system with manipulators, which transports the semiconductor wafer to a dryer 4 after the final cleaning step (not shown).

[0015] Each of the cleaning modules 3a-3c has a cover 9, each of which has a slot 10 allowing the manipulators 7 and 8 to access the respective cleaning module.

[0016] When one of the two manipulators 7, 8 loads a semiconductor wafer into or lifts it from a cleaning module, the other manipulator takes a position between the slot 10 in the cover of this cleaning module and the slot 10 in the cover of the adjacent cleaning module. In this situation, droplets, which may be from the other manipulator or the semiconductor wafer held by the other manipulator, cannot fall through the slot in the cover of the cleaning module where this one manipulator is active. [Explanation of symbols]

[0017] List of reference symbols used 1 Polishing Station 2 Washing Station 3a Cleaning module 3b Cleaning module 3c Cleaning module 4 Dryer 5 Guide 6. Grasping System 7 Manipulator 8 Manipulator 9 Cover 10 Slots

Claims

1. 1. A method for cleaning semiconductor wafers in a cleaning line comprising at least two cleaning modules, wherein vertically oriented semiconductor wafers are successively treated with liquids of respective cleaning steps during cleaning steps, and wherein at least one gripping system comprising two adjacent manipulators is moved over one of the cleaning modules, one manipulator being moved through a slot in a cover of the one cleaning module to load or pick up the semiconductor wafer, and the other manipulator being positioned between a slot in the cover of the one cleaning module and a slot in a cover of the other cleaning module.

2. The method of claim 1 characterized by three cleaning modules.

3. 3. The method according to claim 1 or 2, characterized in that the other manipulator is positioned above the cover of the one cleaning module but not above the slot of the cover of the one cleaning module.

Images