Method for automatically identifying semiconductor wafers
First Claim
1. A method for automatically identifying a semiconductor wafer comprising the steps of:
- providing coded indicia including bars and spaces of a selected length in a predetermined portion of a surface of a semiconductor wafer;
imparting a relative rotational motion between the semiconductor wafer and a radiant energy sensing means through at least a predetermined arc about an axis perpendicular to the surface of the wafer while imparting a relative linear motion therebetween in a radial direction along the surface of the wafer;
directing a beam of radiant energy at said predetermined portion of the surface of the wafer along a first predetermined angular direction relative thereto so that the beam of radiant energy is reflected from the space portions of the coded indicia into the radiant energy sensing means along a second angular direction relative to the surface of the wafer;
sensing, at the radiant energy sensing means, the radiant energy reflected by the space portions of the coded indicia at successively different positions along the length thereof as the relative linear motion is imparted between the wafer and the radiant energy sensing means while the relative rotational motion is imparted therebetween, to generate signals identifying the wafer.
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Accused Products
Abstract
A technique for automatically identifying a semiconductor wafer (30) having bar code identification indicia (32) on the front surface (31) thereof. Reading of the code is achieved by rotating the wafer about an axis (34) perpendicular to its front surface (31); directing a beam of radiant energy (37) at the code (32) along a predetermined direction relative to the front surface (31); and sensing, while rotating the wafer, the reflected radiant energy (39) within a second predetermined angular direction relative to the front surface. The bar code used herein is preferably a modified or "stretched" bar code 39 formed on the front surface of the wafer, and having an aspect ratio (i.e., dimension of a space/dimension of a bar) ranging from 1 to 4 (FIG. 2).
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Citations
19 Claims
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1. A method for automatically identifying a semiconductor wafer comprising the steps of:
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providing coded indicia including bars and spaces of a selected length in a predetermined portion of a surface of a semiconductor wafer; imparting a relative rotational motion between the semiconductor wafer and a radiant energy sensing means through at least a predetermined arc about an axis perpendicular to the surface of the wafer while imparting a relative linear motion therebetween in a radial direction along the surface of the wafer; directing a beam of radiant energy at said predetermined portion of the surface of the wafer along a first predetermined angular direction relative thereto so that the beam of radiant energy is reflected from the space portions of the coded indicia into the radiant energy sensing means along a second angular direction relative to the surface of the wafer; sensing, at the radiant energy sensing means, the radiant energy reflected by the space portions of the coded indicia at successively different positions along the length thereof as the relative linear motion is imparted between the wafer and the radiant energy sensing means while the relative rotational motion is imparted therebetween, to generate signals identifying the wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for automatically identifying a semiconductor wafer having coded indicia on a surface thereof, the method comprising the steps of:
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laser marking bar code indicia in a predetermined portion of the front surface of the wafer, said bar code including wide spaces and wide bars and narrow spaces and narrow bars of a predetermined length and width with the ratio of the width of the narrow spaces to the narrow bars ranging from 2.0 to 4.0 and the ratio of the width of the wide spaces to the wide bars ranging from 1.5 to 4.0; continuously rotating the semiconductor wafer about an axis perpendicular to its front surface; moving an optical means in a radial direction along the front surface of the wafer; directing an optical beam, along a first predetermined angular direction relative to the rotating front surface of the wafer toward the bar code indicia thereon; and sensing, at the optical means during the movement thereof in a radial direction along the front surface of the wafer as it rotates, the optical energy reflected by the spaces of the bar code indicia at successively different positions along the length thereof, within a second predetermined angular direction, thereby generating signals identifying the wafer. - View Dependent Claims (11)
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- 12. A bar code identification for semiconductor wafers comprising a plurality of wide bars, wide spaces, narrow bars and narrow spaces wherein the ratio of the width of the narrow spaces to the narrow bars ranges from 2.0 to 4.0 and wherein the ratio of the width of the wide spaces to the wide bars ranges from 1.5 to 4.0 .
Specification