Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
2002-11-26
2004-07-27
Nghiem, Michael (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
Reexamination Certificate
active
06768964
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a prompt and accurate positioning method which can arbitrarily specify a forming position of dot marks for production management or various securities, which are made at a minute substantially planar portion existing on a peripheral surface of a semiconductor wafer and a positioning apparatus therefor. The forming position of dot marks according to the present invention means where dot marks must be formed and where dot marks are formed.
2. Prior Art
Conventionally, in the steps for manufacturing a semiconductor, for example, variable and strict manufacturing conditions must be set for the respective steps. In order to manage such manufacturing conditions, primary marks by numbers, characters or dots, or marks by a bar code or the like are indicated on a partial surface of a semiconductor wafer. However, the number of steps for manufacturing a semiconductor reaches several hundreds or more as high integration of a semiconductor proceeds. In addition, large numbers of element forming processes and planarizing processes are performed in the respective steps. As these processes, planarizing processes performed by, for example, resist coating, reduced projection of a pattern onto a resist, resist development, and various coating operations of insulating films, metal films and the like for filling gaps formed by copper lines are known.
Said dot marking is generally conducted irradiation of a continuous pulse laser beam on a partial surface of a semiconductor wafer through an optical system. In addition, marking is not performed only once, and minimum necessary historical data is often marked in the manufacturing steps to indicate the historical characteristics of the manufacturing steps. On a semiconductor wafer subjected to dot marking, information is generally read as a change in reflectance caused by irradiation of a laser beam of a He-Ne laser or a change in vibration of the heat wave of a conventional laser beam. Various manufacturing conditions in the subsequent manufacturing steps are set on the basis of the read information.
Processing histories in manufacturing steps of a wafer or a semiconductor or varying historical information such as historical characteristics of lots can be indicated by dot marks formed on a front surface of an orientation flat portion of a wafer, a rear surface of a wafer, or a wafer peripheral surface as disclosed in Japanese Patent Application Laid-Open No. 7-201688.
Moreover, in recent years, as Applicant suggests in Japanese Patent Application No. 11-333824 and Japanese Patent Application Laid-Open No. 2000-23382, the shape of a dot mark is reduced in size to vertical dimensions of 0.01 to 5 &mgr;m and a maximum width of 1 to 15 &mgr;m, and a dot shape which is good in visibility can be formed. Consequently, dot marking areas has greatly expanded. For example, marking can be conducted on such minute areas as a planar surface of a scribe line for cutting a semiconductor wafer to the dimensions of semiconductor chips, a planar surface of an upper and lower chamfering portions of a wafer rim, and, moreover, a planar surface of upper and lower chamfering portions of a V-notch serving as a reference mark for positioning formed on a wafer rim.
Meanwhile, various positioning apparatuses for setting wafers at predetermined positions have been proposed for exposure and transferring steps for a wafer in a conventional semiconductor-element-manufacturing device. For instance, Japanese Patent Application Laid-Open No. 4-212436 and Japanese Patent Application Laid-Open No. 6-45226 suggest devices to further increase positioning accuracy and speed.
In such conventional wafer positioning apparatus including the wafer positioning devices disclosed in these publications, the position of a reference mark such as an orientation flat or a V-notch formed on a wafer rim is detected, and positioning is conducted by moving the wafer to three axial directions of x, y and z to adjust the detected position to a predetermined position.
Since said orientation flat surface or said scribe line exists on a smooth surface side of a wafer, it is not technically difficult to orthogonalize an optical axis to the beam irradiation surface of the orientation flat surface or the scribe line in positioning of the marking by irradiation of a laser beam because the wafer surface is entirely smooth.
However, the chamfering portions of the wafer rim or the V-notch are extremely minute areas with width of about several hundred micrometers in the radial direction, and the tilt angles of these chamfering portions are not always constant. Therefore, when positioning is performed on such a minute area, a planar portion of a chamfering area must be precisely detected, and the irradiated optical axis of a laser marker must be orthogonalized accurately to the planar portion for following reasons:
(1) When an image-forming position of a processing system is considerably out of a wafer peripheral surface, the machining system becomes out of focus and high-quality processing cannot be performed. Even the marking itself sometimes becomes impossible.
(2) Influence on marks in the manufacturing steps depends on bevel surface positions of the wafer peripheral surface. An upper part of the mark may be erased with only its lower part remaining, or vice versa. In this case, the mark cannot be recognized in the subsequent steps, and management of wafers is disturbed.
(3) With respect to a reading device, if marking is not performed to a determined position, the mark may be out of a predetermined light-intensity range, or mark recognition may become difficult because the reading device is out of focus.
For these reasons, accuracy higher than that of conventional positioning is required in order to decide a forming position of fine dot marks formed on a minute area. Such accuracy is a severe requirement unnecessary for mere dot marking by punching on the front and rear surfaces of a semiconductor wafer. Not only the visibility but also the accuracy must be specially considered upon marking.
Therefore, Applicant proposed a processing apparatus which can efficiently read and write fine dot marks on such minute areas in Japanese Patent Application Laid-Open No. 2001-235309 (Device for Optically Detecting and Processing Surface to be Processed) and Japanese Patent Application No. 2000-284617 (Apparatus and Method for Optically Processing Planar Part of Notch-beveled Part of Semiconductor Wafer). A basic detection mechanism for a read/write position disclosed in these publications uses a change in light intensity at the planar portion of a chamfer of a V-notch on a minute area.
The device for optically detecting and processing surface to be processed according to said Japanese Patent Application Laid-Open No. 2001-235309 can optically detect the planar portion of the chamfer of a V-notch on a minute area and, at the same time, can automatically perform positioning of the processing apparatus.
More specifically, the optical axis of an image pickup unit arranged on a bisector of an angle between optical axes of a light-projection unit and a light-receiving unit is set to be orthogonalized to the planar portion of the chamfer of the V-notch on the minute area. Then, incident light scans along the planar portion of the chamfer, so that the change in light intensity on the planar portion of the chamfer is captured as a predetermined change in light intensity. The change in light intensity is detected through a photoelectric transfer element and, simultaneously, this light is used as illumination light of the image pickup unit. Image of the surface of the detected surface is picked and displayed on a monitor or the like. The image pickup unit is finely adjusted to be focused on the planar portion of the chamfer, and a desired optical process is performed thereto.
Meanwhile, in the apparatus and method for optically processing planar part of notch-beveled part of semiconductor wafer according to Japanese Patent Application No. 2000-2846
Bell Boyd & Lloyd LLC
Komatsu Limited
Nghiem Michael
LandOfFree
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