Methods, apparatus and media for determining a shape of an irradiance pulse to which a workpiece is to be exposed

Patent metadata

Field	Value
Publication number	US-9279727-B2
Application number	US-201113824269-A
Country	US
Kind code	B2
Filing date	Oct 14, 2011
Priority date	Oct 15, 2010
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A method and system for determining a shape of an irradiance pulse to which a semiconductor wafer is to be exposed during a thermal cycle are disclosed. The method includes receiving, with a processor circuit, thermal cycle parameters specifying requirements of the thermal cycle, and determining, with the processor circuit, a shape of a heating portion of the irradiance pulse. Determining includes optimizing at least one parameter of a flux profile model of the heating portion of the irradiance pulse to satisfy the requirements while minimizing frequency-domain energy spectral densities of the flux profile model at resonant frequencies of the wafer, to minimize vibration of the wafer at the resonant frequencies when the wafer is exposed to the irradiance pulse.

First claim

What is claimed is:

1. A method of determining a shape of an irradiance pulse to which a workpiece is to be exposed during a thermal cycle, the method comprising:
a) receiving, with a processor circuit, thermal cycle parameters specifying requirements of the thermal cycle;
b) determining, with the processor circuit, a shape of a heating portion of the irradiance pulse, wherein determining comprises optimizing at least one parameter of a flux profile model of the heating portion of the irradiance pulse to satisfy the requirements while minimizing frequency-domain energy spectral densities of the flux profile model at resonant frequencies of the workpiece, to minimize vibration of the workpiece at the resonant frequencies when the workpiece is exposed to the irradiance pulse; and
c) generating the irradiance pulse, incident on the workpiece.

2. The method of claim 1 wherein: the workpiece comprises a semiconductor wafer having a device side which is to be exposed to the irradiance pulse during the thermal cycle; wherein determining the shape of the heating portion of the irradiance pulse comprises optimizing the at least one parameter of the flux profile model of the heating portion of the irradiance pulse to satisfy the requirements while minimizing frequency-domain energy spectral densities of the flux profile model at resonant frequencies of the semiconductor wafer, to minimize vibration of the wafer at the resonant frequencies when the device side is exposed to the irradiance pulse; and wherein generating the irradiance pulse incident on the workpiece comprises generating the irradiance pulse incident on the wafer.

3. The method of claim 2 wherein optimizing causes the heating portion to have a duration between about one-eighth and about one-half of a period of a fundamental vibrational mode of the wafer.

4. The method of claim 3 wherein optimizing causes the heating portion to have a duration between about 1.2 and about 4.2 ms.

5. The method of claim 2 wherein optimizing causes the heating portion to have a duration between about one-tenth and about four times a thermal time constant of the wafer.

6. The method of claim 5 wherein optimizing causes the heating portion to have a duration between about 1.5 and about 60 ms.

7. The method of claim 2 wherein optimizing comprises optimizing a bandwidth parameter of the flux profile model associated with a rise rate of the heating portion of the irradiance pulse.

8. The method of claim 7 wherein the flux profile model comprises a non-linear function.

9. The method of claim 8 wherein the flux profile model comprises a function from the class of exponential functions.

10. The method of claim 8 wherein the flux profile model comprises a function from the class of sigmoidal functions.

11. The method of claim 7 wherein the flux profile model comprises a function whose rate of change in the time domain increases monotonically from commencement until at least a time at which a value of the function reaches 25% of its peak value.

12. The method of claim 7 wherein the flux profile model comprises a function whose rate of change in the time domain increases monotonically from commencement until at least a time at which a value of the function reaches 95% of its peak value.

13. The method of claim 7 wherein the flux profile model comprises a function of the form:

Q
h

⁡

(

t
;
c

,
a

)

=

c
⁢

⁢

f
⁡

(

t
,
a

)

=

c
⁢

e

a
⁢

⁢
t

-
1

k

wherein:
Q(t;c,a) is irradiance flux as a function of time t and parameters a and c;
a is the bandwidth parameter;
c is a scaling parameter associated with a peak magnitude of the heating portion;
e is the Euler number; and
k is defined as k=e at 1 −1, where t 1 is a rise time of the heating portion from commencement to peak magnitude.

14. The method of claim 7 wherein the flux profile model comprises a function of the form:

Q
h

⁡

(

t
;
c

,
a

)

=

c
⁢

⁢

f
⁡

(

t
,
a

)

=

c
⁡

(

1
-

e

-

(

t
-
k

)

⁢
a

1
+

e

-

(

t

Assignees

• Cibere Joseph
• Camm David Malcolm
• Mattson Tech Inc

Inventors

• Cibere Joseph
• Camm David Malcolm

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H10P72/0602

  Temperature monitoring · CPC title

• H10P72/0436 Primary

  mainly by radiation · CPC title

• H10P95/90 Primary

  Thermal treatments, e.g. annealing or sintering · CPC title