1. A method for fabricating a composite structure, comprising:
applying a bonding material to a first component;
converting the bonding material applied to the first component to an enhanced bonding layer by:
heating the bonding material to outgas volatile species from the bonding material, wherein the outgassed volatile species accumulate to at least 0.05% in mass of the bonding material; and
monitoring at least one of a ratio of the outgassed volatile species of different molecular weights and evaporating rates of the outgassed volatile species,
wherein the enhanced bonding layer has a molecular weight that is reduced by at least 35% from a molecular weight of the bonding material; and
contacting a second component and the enhanced bonding layer to join the first and second components, wherein contacting the second component and the enhanced bonding layer comprises pressing the first and second components against each other at a pressure between about 14 psi to about 200 psi.
2. The method of claim 1, wherein heating the bonding material comprises baking the bonding material and the first component at a baking temperature.
3. The method of claim 1, wherein the bonding material is an acrylic based or silicone based polymer bonding material.
4. The method of claim 3, wherein converting the bonding material further comprises reducing molecular weight and polymer chain length or cross linking.
5. The method of claim 2, wherein converting the bonding material comprises heating the bonding material and the first component in a vacuum environment.
6. The method of claim 5, wherein converting the bonding material further comprises determining an end point by monitoring the volatile species escaped from the bonding material.
7. The method of claim 2, wherein converting the bonding material further comprises heating the bonding material to a temperature higher than an intended operating temperature of the composite structure.
8. The method of claim 7, wherein heating the bonding material to a temperature higher than an intended operating temperature of the composite structure comprises heating the bonding material to a temperature between about 60\xb0 C. to about 260\xb0 C.
9. The method of claim 7, wherein heating the bonding material to a temperature higher than an intended operating temperature of the composite structure comprises heating the bonding material for about 1 hour to about 180 hours.
10. A method for forming a structure for a semiconductor processing chamber, comprising:
applying a bonding material to a first component of the structure;
converting the bonding material applied to the first component to an enhanced bonding layer by:
baking the bonding material and the first component while the bonding material is exposed, wherein the enhanced bonding layer has at least 0.05% less volatile material than the bonding material, and the enhanced bonding layer has a molecular weight that is reduced by at least 35% from a molecular weight of the bonding material; and
pressing a second component against the enhanced bonding layer to join the first and second components by applying a pressure between about 14 psi to about 200 psi.
11. The method of claim 10, wherein baking the bonding material is performed at a temperature between about 60\xb0 C. to about 260\xb0 C.
12. The method of claim 10, wherein the bonding material is an acrylic based or silicone based polymer bonding material.
13. The method of claim 12, wherein the enhanced bonding layer is different from the bonding material in molecular weight and polymer chain structure.
14. The method of claim 13, wherein the structure is an electrostatic chuck or a showerhead.
15. The method of claim 1, wherein converting the bonding material further comprises changing a heating temperature to adjust the ratio of outgassed species escaped from the bonding material.
16. The method of claim 15, further comprising increasing the heating temperature to increase an average molecular weight in the outgassed species.
17. The method of claim 15, further comprising reducing the heating temperature to reduce an average molecular weight in the outgassed species.
18. The method of claim 1, further comprising doping the bonding material with an oxide material at up to 50% in volume in the bonding material.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for determining the interstitial oxygen concentration of a sample made from p-type semiconductor material from the thermal donor concentration, comprising the following step:
subjecting the sample to thermal treatment for a specified time to form thermal donors;
bringing the sample to a temperature comprised between 4 K and 100 K and measuring the charge carrier concentration of the sample;
determining the thermal donor concentration of the sample from the charge carrier concentration and the temperature of the sample; and
determining the interstitial oxygen concentration from the thermal donor concentration and the specified time, as a function relating the thermal donor concentration, the interstitial oxygen concentration, and the specified time.
2. The method according to claim 1, comprising a plurality of measurements of the charge carrier concentration at different temperatures comprised between 4 K and 100 K, and wherein the thermal donor concentration is determined by correlation of the measurements with a relation describing the variation of the charge carrier concentration versus the temperature.
3. The method according to claim 2, wherein, the sample comprising dopant impurities of acceptor and donor type, the thermal donor concentration NTDD is determined by means of the following relation:
p
\u2061
(
T
)
=
–
1
2
\u2062
(
2
\xd7
N
TDD
+
N
D
+
N
V
4
\u2062
\u2147
–
E
A
kT
)
+
1
2
\u2062
(
2
\xd7
N
TDD
+
N
D
+
N
V
4
\u2062
\u2147
–
E
A
kT
)
2
+
(
N
A
–
2
\xd7
N
TDD
–
N
D
)
\xd7
N
V
\u2062
\u2147
–
E
A
kT
wherein p(T) is the variation of the charge carrier concentration versus the temperature, NA is the concentration of dopant impurities of acceptor type, ND is the concentration of dopant impurities of donor type, EA the energy level of the acceptor states, Nv the equivalent density of states in the valence band, k the Boltzmann’s constant and T the temperature.
4. The method according to claim 3, comprising, before the thermal treatment step, a step of determining the dopant impurity concentration from a resistivity measurement of the sample.
5. The method according to claim 1, wherein, the sample comprising dopant impurities of acceptor and donor type, the thermal donor concentration NTDD is determined by means of the following relation:
p
\u2061
(
T
)
=
–
1
2
\u2062
(
2
\xd7
N
TDD
+
N
D
+
N
V
4
\u2062
\u2147
–
E
A
kT
)
+
1
2
\u2062
(
2
\xd7
N
TDD
+
N
D
+
N
V
4
\u2062
\u2147
–
E
A
kT
)
2
+
(
N
A
–
2
\xd7
N
TDD
–
N
D
)
\xd7
N
V
\u2062
\u2147
–
E
A
kT
wherein p(T) is the variation of the charge carrier concentration versus the temperature, NA is the concentration of dopant impurities of acceptor type, ND is the concentration of dopant impurities of donor type, EA the energy level of the acceptor states, Nv the equivalent density of states in the valence band, k the Boltzmann’s constant and T the temperature.
6. The method according to claim 5, comprising, before the thermal treatment step, a step of determining the dopant impurity concentration from a resistivity measurement of the sample.
7. The method according to claim 1, initially comprising an annealing step at a temperature greater than or equal to 650\xb0 C.
8. The method according to claim 1, wherein the charge carrier concentration is measured by Hall effect.
9. The method according to claim 1, wherein the thermal treatment is performed at a temperature comprised between 200\xb0 C. and 500\xb0 C.
10. The method according to claim 9, wherein the temperature of the thermal treatment is comprised between 400\xb0 C. and 500\xb0 C.
11. The method according to claim 1, wherein the sample is brought to a temperature comprised between 4 K and 20 K to measure the charge carrier concentration.