Die-beam alignment for laser-assisted bonding
A method of making a semiconductor device involves the steps of disposing a first semiconductor die over a substrate and disposing a beam homogenizer over the first semiconductor die. A beam from the beam homogenizer impacts the first semiconductor die. The method further includes the steps of determining a positional offset of the beam relative to the first semiconductor die in a number of pixels, using a first calibration equation to convert the number of pixels into a distance in millimeters, and moving the beam homogenizer the distance in millimeters to align the beam and first semiconductor die.
1 . A method of making a semiconductor device, comprising:
disposing a first semiconductor die over a substrate;
disposing a beam homogenizer over the first semiconductor die in a first position, wherein a beam from the beam homogenizer impacts the first semiconductor die;
generating a first calibration equation by,
capturing a first image of the first semiconductor die and beam using a camera with the beam homogenizer in the first position over the first semiconductor die,
calculating a first positional offset of the beam relative to the first semiconductor die in a first number of pixels by using image processing on the first image,
moving the beam homogenizer a first known distance to a second position over the first semiconductor die,
capturing a second image of the first semiconductor die and beam using the camera with the beam homogenizer in the second position over the first semiconductor die,
calculating a second positional offset of the beam relative to the first semiconductor die in a second number of pixels by using image processing on the second image, and
performing a first linear regression with the first known distance, first number of pixels, and second number of pixels;
returning the beam homogenizer to the first position over the first semiconductor die after generating the first calibration equation;
generating a second calibration equation by,
capturing a third image of the first semiconductor die and beam using the camera with the beam homogenizer in the first position over the first semiconductor die,
calculating a first rotational offset of the beam relative to the first semiconductor die as a first angle value by using image processing on the third image,
rotating the beam homogenizer a second known distance to a third position over the first semiconductor die,
capturing a fourth image of the first semiconductor die and beam using the camera with the beam homogenizer in the third position over the first semiconductor die,
calculating a second rotational offset of the beam relative to the first semiconductor die as a second angle value by using image processing on the fourth image, and
performing a second linear regression with the second known distance, first angle value, and second angle value;
returning the beam homogenizer to the first position over the first semiconductor die after generating the second calibration equation;
calculating a third positional offset of the beam relative to the first semiconductor die in a first unit;
using the first calibration equation to convert the third positional offset into a first distance in a second unit;
moving the beam homogenizer the first distance to center the first semiconductor die fully within the beam;
calculating a third rotational offset of the beam relative to the first semiconductor die in a third unit;
using the second calibration equation to convert the third rotational offset into a second distance in a fourth unit;
rotating the beam homogenizer the second distance to rotationally align the beam to the first semiconductor die;
disposing the beam homogenizer over a second semiconductor die;
calculating a fourth positional offset of the beam relative to the second semiconductor die in the first unit;
using the first calibration equation to convert the fourth positional offset into a third distance in the second unit;
moving the beam homogenizer the third distance to center the second semiconductor die fully within the beam;
calculating a fourth rotational offset of the beam relative to the second semiconductor die in the third unit;
using the second calibration equation to convert the fourth rotational offset into a fourth distance in the fourth unit; and
rotating the beam homogenizer the fourth distance to rotationally align the beam to the second semiconductor die.
2 . The method of claim 1 , further including generating the first calibration equation by performing the first linear regression on a plurality of known positional offsets.
3 . The method of claim 1 , further including reflowing a plurality of bumps disposed between the semiconductor die and substrate using the beam.
4 . The method of claim 1 , further including disposing the beam homogenizer over the semiconductor die by:
locating a first corner of the semiconductor die;
locating a second corner of the semiconductor die opposite the first corner; and
moving the beam homogenizer to the average position between the first corner and second corner.
5 . The method of claim 1 , further including calculating the first positional offset by:
determining a first boundary of the semiconductor die;
determining a second boundary of the beam; and
comparing the first boundary and second boundary.
6 . The method of claim 1 , further including regenerating the first calibration equation and second calibration equation periodically using a third semiconductor die.
7 . A method of making a semiconductor device, comprising:
disposing a first semiconductor die over a substrate;
disposing a beam homogenizer over the first semiconductor die in a first position using a first camera, wherein a beam from the beam homogenizer impacts the first semiconductor die;
generating a second calibration equation by,
capturing a third image of the first semiconductor die and beam using a second camera with the beam homogenizer in the first position over the first semiconductor die, wherein the second camera is a different type of camera from the first camera,
calculating a first rotational offset of the beam relative to the first semiconductor die as a first angle value by using image processing on the third image,
rotating the beam homogenizer a second known distance to a third position over the first semiconductor die,
capturing a fourth image of the first semiconductor die and beam using the second camera with the beam homogenizer in the third position over the first semiconductor die,
calculating a second rotational offset of the beam relative to the first semiconductor die as a second angle value by using image processing on the fourth image, and
performing a second linear regression with the second known distance, first angle value, and second angle value;
returning the beam homogenizer to the first position over the first semiconductor die after generating the second calibration equation;
calculating a third rotational offset of the beam relative to the first semiconductor die in a third unit using image processing on an image from a second camera;
using the second calibration equation to convert the third rotational offset into a second distance in a fourth unit;
rotating the beam homogenizer the second distance to rotationally align the beam to the first semiconductor die;
disposing the beam homogenizer over a second semiconductor die;
calculating a fourth rotational offset of the beam relative to the second semiconductor die in the third unit;
using the second calibration equation to convert the fourth rotational offset into a fourth distance in the fourth unit; and
rotating the beam homogenizer the fourth distance to rotationally align the beam to the second semiconductor die.
8 . The method of claim 7 , further including generating the second calibration equation by performing the second linear regression on a plurality of known rotational offsets.
9 . The method of claim 7 , further including disposing the beam homogenizer over the semiconductor die by:
locating a first corner of the semiconductor die;
locating a second corner of the semiconductor die opposite the first corner; and
moving the beam homogenizer to the average position between the first corner and second corner.
10 . The method of claim 7 , further including reflowing a plurality of bumps disposed between the semiconductor die and substrate using the beam.
11 . The method of claim 7 , further including performing image processing on the third image to determine a first boundary of the semiconductor die and a second boundary of the beam.
12 . A method of making a semiconductor device, comprising:
disposing a beam homogenizer over a semiconductor die in a first position with a beam from the beam homogenizer disposed onto the semiconductor die and with an entire footprint of the semiconductor die within the beam of light;
generating a second calibration equation by,
capturing a third image of the first semiconductor die and beam using a camera with the beam homogenizer in the first position over the first semiconductor die,
calculating a first rotational offset of the beam relative to the first semiconductor die as a first angle value by using image processing on the third image,
rotating the beam homogenizer a second known distance to a third position over the first semiconductor die,
capturing a fourth image of the first semiconductor die and beam using the camera with the beam homogenizer in the third position over the first semiconductor die,
calculating a second rotational offset of the beam relative to the first semiconductor die as a second angle value by using image processing on the fourth image, and
performing a second linear regression with the second known distance, first angle value, and second angle value;
returning the beam homogenizer to the first position over the first semiconductor die after generating the second calibration equation;
calculating a third rotational offset of the beam homogenizer relative to the semiconductor die in a third unit while the beam homogenizer is disposed over the semiconductor die with the beam impacting the semiconductor die;
using the second calibration equation to convert the third rotational offset into a second distance in a fourth unit; and
rotating the beam homogenizer the second distance to rotationally align the beam to the semiconductor die.
13 . The method of claim 12 , further including generating the second calibration equation by performing the second linear regression on a plurality of known offsets.
14 . The method of claim 12 , further including reflowing a plurality of bumps disposed under the semiconductor die using the beam homogenizer.