Grid transparency and grid hole pattern control for ion beam uniformity
View Patent ↗A design process for varying hole locations or sizes or both in an ion beam grid includes identifying a control grid to be modified; obtaining a change factor for the grid pattern; and using the change factor to generate a new grid pattern. The change factor is one or both of a hole location change factor or a hole diameter change factor. Also included is an ion beam grid having the characteristic of hole locations or sizes or both defined by a change factor modification of control grid hole locations or sizes or both.
1. A design process for creating a modified pattern of holes for a beam grid comprising:
identifying an initial pattern of holes for the beam grid to be modified;
obtaining a change factor for the initial pattern of holes for the beam grid;
using the change factor to generate the modified pattern of holes for the beam grid based on the initial pattern of holes.
2. A design process according to claim 1 wherein the change factor is one or both of a hole location change factor or a hole diameter change factor.
3. A design process according to claim 1 wherein the obtaining operation includes solving a differential equation.
4. A design process according to claim 1 wherein the obtaining operation includes solving one or both of the following differential equations:
ⅆ
R
ⅆ
r
=
r
×
f
(
r
)
R
×
F
(
R
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
f(r) represents grid transparency of the initial pattern hole locations,
F(R) represents grid transparency of the modified pattern hole locations, and
R represents the change factor for generating the modified pattern of holes
ⅆ
X
ⅆ
x
=
h
(
x
)
H
(
X
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations,
h(x) represents grid transparency of the initial pattern hole locations,
H(X) represents grid transparency of the modified pattern hole locations, and
X represents the change factor for generating the modified pattern of holes.
5. A design process according to claim 4 wherein the obtaining operation includes providing one or more of
f(r) and F(R), and using the one or both differential equations to obtain R, which is used to radially re-locate hole locations of the initial pattern of holes to obtain the modified pattern of holes; and
h(x) and H(X), and using the one or more differential equations to obtain X, which is used to linearly re-locate hole locations of the initial pattern of holes to obtain the modified pattern of holes.
6. A design process according to claim 4 wherein one or both of the differential equations are solved using a forward-marching numerical technique.
7. A design process according to claim 1 wherein the obtaining operation includes solving one or more of the following differential equations using a 4th order Runge-Kutta method:
ⅆ
R
ⅆ
r
=
r
×
f
(
r
)
R
×
F
(
R
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
f(r) represents grid transparency of the initial pattern hole locations,
F(R) represents grid transparency of the modified pattern hole locations, and
R represents the change factor for generating the modified pattern of holes;
or,
ⅆ
X
ⅆ
x
=
h
(
x
)
H
(
X
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations,
h(x) represents grid transparency of the initial pattern hole locations,
H(X) represents grid transparency of the modified pattern hole locations, and
X represents the change factor for generating the modified pattern of holes;
or,
ⅆ
r
'
ⅆ
r
=
r
r
'
×
g
(
r
)
,
wherein
g(r) represents a desired ratio of grid transparency in a radial system, and
r′ represents an approximation of the change factor for generating the modified pattern of holes;
or
ⅆ
x
'
ⅆ
x
=
1
i
(
x
)
,
wherein
i(x) represents a desired ratio of grid transparency in a Cartesian system, and
x′ represents an approximation of the change factor for generating the modified pattern of holes.
8. A design process according to claim 1 wherein the obtaining a operation includes solving one or both of the following differential equations:
ⅆ
r
'
ⅆ
r
=
r
r
'
×
g
(
r
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
g(r) represents a desired ratio of grid transparency in a radial system, and
r′ represents an approximation of the change factor for generating the modified pattern of holes;
or
ⅆ
x
'
ⅆ
x
=
1
i
(
x
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations,
i(x) represents a desired ratio of grid transparency in a Cartesian system, and
x′ represents an approximation of the change factor for generating the modified pattern of holes.
9. A design process according to claim 8 wherein the obtaining operation includes providing one or more of
g(r) and using the one or both differential equations to obtain r′, which is used to radially re-locate hole locations of the initial pattern of holes to obtain the modified pattern of holes; and
i(x) and using the one or both differential equations to obtain x′, which is used to linearly re-locate hole locations of the initial pattern of holes to obtain the modified pattern of holes.
10. A design process according to claim 8 wherein one or both of the differential equations are solved using a forward-marching numerical technique.
11. A design process according to claim 1 , wherein one or more of the identifying, obtaining, and using operations are iterated to generate the modified pattern of holes.
12. A design process according to claim 1 wherein the beam grid substantially continuously varies in transparency.
13. A beam grid generated by the design process of claim 1 .
14. A design process according to claim 1 wherein the change factor defines an array of individual hole locations in the modified pattern of holes relative to an array of individual hole locations in the initial pattern of holes.
15. The design process of claim 1 wherein the change factor is further used to vary hole locations in the beam grid to change transparency of the beam grid.
16. A beam grid having a modified pattern of holes designed by:
identifying an initial pattern of holes for the beam grid to be modified;
obtaining a change factor for the initial pattern of holes for the beam grid;
using the change factor to generate the modified pattern of holes for the beam grid based on the initial pattern of holes.
17. A beam grid according to claim 16 wherein the change factor is one or both of a hole location change factor or a hole diameter change factor.
18. A beam grid according to claim 16 wherein the change factor is obtained from the solution of a differential equation.
19. A beam grid according to claim 16 wherein the change factor is obtained from a solution of one or both of the following differential equations:
ⅆ
R
ⅆ
r
=
r
×
f
(
r
)
R
×
F
(
R
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
f(r) represents grid transparency of the initial pattern hole locations,
F(R) represents grid transparency of the modified pattern hole locations, and
R represents the change factor for generating the modified pattern of holes;
or,
ⅆ
X
ⅆ
x
=
h
(
x
)
H
(
X
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations,
h(x) represents grid transparency of the initial pattern hole locations,
H(X) represents grid transparency of the modified pattern hole locations, and
X represents the change factor for generating the modified pattern of holes.
20. A beam grid according to claim 19 wherein the one or both differential equations are provided with one or more of
f(r) and F(R), and using one or both differential equations to obtain R, which characterizes radial hole locations of the modified pattern of holes compared to the initial pattern of holes; and
h(x) and H(X), and using one or more differential equations to obtain X, which characterizes linear hole locations of the modified pattern of holes compared to the initial pattern of holes.
21. A beam grid according to claim 19 wherein one or both of the differential equations are solved using a forward-marching numerical technique.
22. A beam grid according to claim 16 wherein the change factor is obtained from a solution of one or more of the following differential equations using a 4th order Runge-Kutta method:
ⅆ
R
ⅆ
r
=
r
×
f
(
r
)
R
×
F
(
R
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
f(r) represents grid transparency of the initial pattern hole locations,
F(R) represents grid transparency of the modified pattern hole locations, and
R represents the change factor for generating the modified pattern of holes;
or,
ⅆ
X
ⅆ
x
=
h
(
x
)
H
(
X
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations,
h(x) represents grid transparency of the initial pattern hole locations,
H(X) represents grid transparency of the modified pattern hole locations, and
X represents the change factor for generating the modified pattern of holes;
or,
ⅆ
r
'
ⅆ
r
=
r
r
'
×
g
(
r
)
,
wherein
g(r) represents a desired ratio of grid transparency in a radial system
r′ represents an approximation of the change factor for generating the modified pattern of holes;
or
ⅆ
x
'
ⅆ
x
=
1
i
(
x
)
,
wherein
i(x) represents a desired ratio of grid transparency in a Cartesian system
x′ represents an approximation of the change factor for generating the modified pattern of holes.
23. A beam grid according to claim 16 wherein the change factor is obtained from the solution of one or both of the following differential equations:
ⅆ
r
'
ⅆ
r
=
r
r
'
×
g
(
r
)
,
wherein
r represents radial coordinates of the initial pattern hole locations,
g(r) represents a desired ratio of grid transparency in a radial system, and
r′ represents an approximation of the change factor for generating the modified pattern of holes; or
ⅆ
x
'
ⅆ
x
=
1
i
(
x
)
,
wherein
x represents Cartesian coordinates of the initial pattern hole locations and
i(x) represents a desired ratio of grid transparency in a Cartesian system, and
x′ represents an approximation of the change factor for generating the modified pattern of holes.
24. A beam grid according to claim 23 wherein the one or more differential equations are provided with one or more of
g(r) and using the one or both differential equations to obtain r′, which characterizes radial locations of the modified pattern of holes compared to the initial pattern of holes; and
i(x) and using the one or both differential equations to obtain x′, which characterizes linear locations of the modified pattern of holes compared to the initial pattern of holes.
25. A beam grid according to claim 23 wherein one or both of the differential equations are solved using a forward-marching numerical technique.
26. A beam grid according to claim 16 wherein the identifying, obtaining, and using operations are iterated to generate the modified pattern of holes.
27. A beam grid according to claim 16 wherein the modified pattern of holes varies from the initial pattern of holes by one or both of hole size and hole location.
28. A beam grid according to claim 16 that substantially continuously varies in transparency.
29. A beam grid according to claim 16 wherein the change factor defines an array of individual hole locations in the modified pattern of holes relative to an array of individual hole locations in the initial pattern of holes.
30. The beam grid of claim 16 wherein the change factor is further used to vary hole locations in the beam grid to change transparency of the beam grid.