DOPANT MARKER FOR PRECISE RECESS CONTROL
Recess markers are implanted in a material during deposition and used during etching of the material for in-situ removal rate and removal homogeneity-over-radius definitions. An embodiment includes depositing a material on a substrate, implanting two dopants at two predetermined times, respectively, during deposition of the material, etching the material, detecting depths of the two dopants during etching, calculating the removal rate of the material in situ from the depths of the two dopants, and determining from the removal rate an etching stop position. Embodiments further include laterally implanting two dopants in a material at a predetermined depth during deposition, etching the material, detecting the positions and intensities of the two dopants during etching, and calculating lateral homogeneity of the material in situ from intensities of the dopants. Embodiments further include in situ corrective action for the removal process based on the determined removal rate and lateral homogeneity.
1 . A method comprising:
depositing a layer of material on a substrate;
implanting at least two dopants at different depths in the material during deposition;
removing the material;
during material removal, detecting the dopants;
calculating the removal rate of the material in situ from the depths of the dopants; and
correcting the removal process to improve the removal rate of the material in situ.
2 . The method according to claim 1 , comprising calculating the removal rate by calculating the time between detection of consecutive dopants.
3 . The method according to claim 1 , comprising calculating the removal rate by calculating pressure between detection of consecutive dopants.
4 . The method according to claim 1 , further comprising calculating a stop point for material removal based on detection of the dopants and the calculated removal rate.
5 . The method according to claim 4 , comprising correcting the removal process based on the calculated removal rate and calculated stop point.
6 . The method according to claim 1 , comprising removing the material by etching.
7 . The method according to claim 1 , comprising removing the material by polishing.
8 . The method according to claim 1 , comprising implanting three dopants in the material during deposition.
9 . The method according to claim 1 , wherein the material comprises an interlayer dielectric (ILD), and the dopants comprise boron (B), nitrogen (N), and/or phosphorus (P).
10 . The method according to claim 9 , wherein the ILD comprises tetraethyl orthosilicate (TEOS).
11 . A method comprising:
depositing a layer of material on a substrate;
implanting at least two dopants at a predetermined depth, laterally separated, in the material during deposition;
removing the material;
during material removal, detecting the dopants;
calculating the lateral homogeneity of the material in situ from the appearance of the dopants; and
correcting the removal process to improve the lateral homogeneity of the material in situ.
12 . The method according to claim 11 , comprising calculating lateral homogeneity by recording intensity versus relative positions of the dopants and calculating lag time of detection of successive dopants.
13 . The method according to claim 12 , comprising correcting the removal process by controlling a relative intensity.
14 . The method according to claim 12 , comprising correcting the removal process by controlling a relative timing.
15 . The method according to claim 11 , wherein removing comprises chemical mechanical polishing (CMP), and correcting the removal process comprises changing pressure settings for the CMP.
16 . The method according to claim 11 , wherein removing comprises plasma etching, and correcting the removal process comprises biasing edges of the layer.
17 . The method according to claim 11 , comprising implanting three dopants in the material during deposition.
18 . The method according to claim 17 , wherein the material comprises an interlayer dielectric (ILD), and the dopants comprise boron (B), nitrogen (N), and/or phosphorus (P).
19 . The method according to claim 18 , wherein the ILD comprises tetraethyl orthosilicate (TEOS).
20 . A method comprising:
depositing an interlayer dielectric (ILD) on a substrate;
implanting at least three dopants comprising boron (B), nitrogen (N), and/or phosphorus (P) at different depths and/or at different lateral positions in the ILD during deposition;
removing the ILD by etching or polishing;
during ILD removal, detecting the dopants;
calculating the removal rate and/or lateral homogeneity of the ILD in situ from the appearance of the dopants; and
correcting the removal process to improve the removal rate and/or lateral homogeneity of the ILD in situ by controlling a relative intensity or a relative timing, by biasing edges of the layer, and/or by changing pressure settings.