ETCHING APPARATUS FOR SEMICONDUCTOR FABRICATION
An apparatus (and method for operating the same) which allows etching different substrate etch areas of a substrate having different pattern densities at essentially the same etch rate. The apparatus includes (a) a chamber; (b) an anode and a cathode in the chamber; and (c) a bias power system coupled to the cathode, wherein the cathode includes multiple cathode segments. The operation method includes the steps of: (i) placing a substrate to be etched between the anode and cathode, wherein the substrate includes N substrate etch areas, and the N substrate etch areas are directly above the N cathode segments; (ii) determining N bias powers which, when being applied to the N cathode segments during an etching of the substrate, will result in essentially a same etch rate for the N substrate etch areas; and (iii) using the bias power system to apply the N bias powers the N cathode segments.
1 . An apparatus, comprising:
(a) a chamber;
(b) an anode and a cathode positioned in the chamber; and
(c) a bias power system coupled to the cathode,
wherein the cathode comprises N cathode segments electrically insulated from each other, N being an integer greater than 1, and
wherein the bias power system is configured to apply N bias powers one-to-one to the N cathode segments.
2 . The apparatus of claim 1 , wherein the anode is coupled to a plasma generation power system configured to apply sufficient power to the anode to generate a plasma in the chamber.
3 . The apparatus of claim 2 , wherein the plasma generation power system comprises:
a radio frequency plasma generation power source; and
a matching network coupled to the radio frequency plasma generation power source and to the anode.
4 . The apparatus of claim 1 ,
wherein the bias power system comprises N bias power subsystems being coupled one-to-one to the N cathode segments, and
wherein the N bias power subsystems are configured to apply the N bias powers one-to-one to the N cathode segments.
5 . The apparatus of claim 4 , wherein for i=1, 2, . . . , N, an i th bias power subsystem of the N bias power subsystems comprises:
an i th radio frequency bias source; and
an i th matching network coupled to the i th radio frequency bias source and to the i th cathode segment.
6 . The apparatus of claim 4 , wherein each bias power subsystem of the N bias power subsystems is capable of adjusting the bias power subsystem's generated bias power.
7 . The apparatus of claim 1 ,
wherein the bias power system comprises (i) an impedance dividing circuit coupled to the N cathode segments, and (ii) a bias power subsystem coupled to the impedance dividing circuit, and
wherein in response to receiving a total bias power from the bias power subsystem, the impedance dividing circuit is configured to generate the N bias powers one-to-one to the N cathode segments.
8 . The apparatus of claim 7 , wherein the bias power subsystem comprises:
a radio frequency bias power source; and
a matching network coupled to the radio frequency bias power source and to the impedance dividing circuit.
9 . The apparatus of claim 7 , wherein the bias power subsystem is capable of adjusting the bias power subsystem's generated bias power.
10 . The apparatus of claim 1 , wherein the chamber comprises:
a gas inlet configured to receive first gas species into the chamber; and
a gas outlet configured to exhaust second gas species out of the chamber.
11 . An apparatus operating method, comprising the steps of:
(a) providing (i) a chamber, (ii) an anode and a cathode positioned in the chamber, and (iii) a bias power system coupled to the cathode, wherein the cathode comprises N cathode segments electrically insulated from each other, N being an integer greater than 1;
(b) placing a substrate to be etched between the anode and the cathode, wherein the structure comprises N substrate etch areas facing the anode, and wherein the N substrate etch areas are directly above the N cathode segments in a reference direction and match in size and shape with the N cathode segments, wherein the reference direction is essentially perpendicular to a surface of the anode facing the cathode;
(c) determining N bias powers which, when being applied one-to-one to the N cathode segments during an etching of the substrate, will result in essentially a same etch rate for the N substrate etch areas; and
(d) using the bias power system to apply the N bias powers one-to-one to the N cathode segments during the etching of the substrate.
12 . The method of claim 11 , wherein step (c) is performed using the following steps:
(i) etching a first test substrate using the steps (b) and (d), wherein the N bias powers are predetermined;
(ii) examining the first test substrate after step (i) is performed;
(iii) adjusting the N bias powers based on a result of step (ii); and
(iv) repeating steps (i), (ii) and (iii) for at least one additional test substrate until step (ii) results in essentially the same etch rate for the N substrate etch areas.
13 . The method of claim 11 , wherein step (c) is performed using the following steps:
determining N pattern densities for the N substrate etch areas; and
using a database to determine the N bias powers based on the N pattern densities,
wherein the database contains correlations between bias powers, pattern densities, and etch rates.
14 . The method of claim 13 , wherein the correlations between bias powers, pattern densities, and etch rates are determined from empirical data.
15 . The method of claim 11 , wherein step (d) comprises the step of using N bias power subsystems of the bias power system to apply the N bias powers one-to-one to the N cathode segments, wherein the N bias power subsystems are coupled one-to-one to the N cathode segments.
16 . The method of claim 11 , wherein step (d) comprises the steps of:
using a bias power subsystem of the bias power system to generate a total bias power to an impedance dividing circuit of the bias power system; and
in response to the impedance dividing circuit receiving the total bias power, using the impedance dividing circuit to generate the N bias powers one-to-one to the N cathode segments.
17 . An apparatus operating method, comprising the steps of:
(a) providing (i) a chamber, (ii) an anode and a cathode positioned in the chamber, and (iii) a bias power system coupled to the cathode, wherein the cathode comprises N cathode segments electrically insulated from each other, N being an integer greater than 1;
(b) placing a substrate to be etched between the anode and the cathode, wherein the substrate comprises N substrate etch areas facing the anode, and wherein the N substrate etch areas are directly above the N cathode segments in a reference direction and match in size and shape with the N cathode segments, wherein the reference direction is essentially perpendicular to a surface of the anode facing the cathode;
(c) applying a plasma generation power to the anode sufficiently to generate a plasma in the chamber; and
(d) applying N bias powers one-to-one to the N cathode segments.
18 . The method of claim 17 ,
wherein in step (d), the N bias powers chosen such that N substrate etch areas of the substrate experience essentially a same etch rate.
19 . The method of claim 17 , wherein step (d) comprises the step of using N bias power subsystems of the bias power system to apply the N bias powers one-to-one to the N cathode segments, wherein the N bias power subsystems are coupled one-to-one to the N cathode segments.
20 . The method of claim 17 , wherein step (d) comprises the steps of:
using a bias power subsystem of the bias power system to generate a total bias power to an impedance dividing circuit of the bias power system; and
in response to the impedance dividing circuit receiving the total bias power, using the impedance dividing circuit to generate the N bias powers one-to-one to the N cathode segments.