Method for controlling electrochemical deposition to avoid defects in interconnect structures

Patent metadata

Field	Value
Publication number	US-11603602-B2
Application number	US-202117238080-A
Country	US
Kind code	B2
Filing date	Apr 22, 2021
Priority date	Nov 30, 2018
Publication date	Mar 14, 2023
Grant date	Mar 14, 2023

Abstract

A method for performing an electrochemical plating (ECP) process includes contacting a surface of a substrate with a plating solution comprising ions of a metal to be deposited, electroplating the metal on the surface of the substrate, in situ monitoring a plating current flowing through the plating solution between an anode and the substrate immersed in the plating solution as the ECP process continues, and adjusting a composition of the plating solution in response to the plating current being below a critical plating current such that voids formed in a subset of conductive lines having a highest line-end density among a plurality of conductive lines for a metallization layer over the substrate are prevented.

First claim

The invention claimed is:

1. A method for forming a semiconductor structure, comprising:
forming a plurality of contact openings in a dielectric layer over a substrate;
depositing a seed layer over surfaces of the plurality of contact openings and the dielectric layer;
introducing the substrate into an electrochemical plating (ECP) system comprising:
an ECP cell comprising a plating solution;
a monitoring device configured to in situ measure a plating current flowing through the plating solution between an anode and the substrate;
a plating solution supply system in fluid communication with the ECP cell and configured to supply the plating solution to the ECP cell; and
a control system operably coupled to the ECP cell, the monitoring device and the plating solution supply system; and configured to control the ECP cell, the monitoring device and the plating solution supply system;
electrodepositing a conductive layer over the seed layer, thereby forming a plurality of conductive lines in the plurality of contact openings, the plurality of conductive lines comprising a subset of conductive lines having a highest line-end density;
in situ monitoring the plating current during electrodepositing the conductive layer;
receiving a layout data of a metallization layer in an integrated circuit corresponding to the plurality of conductive lines;
calculating a line-end density of the plurality of conductive lines in each of a plurality of unit grids defined in the substrate based on the layout data;
identifying the subset of conductive lines having the highest line-end density in a unit grid of the plurality of unit grids;
determining a critical plating current below which voids are formed in the subset of conductive lines by using a linear model that correlates plating currents which result in defects with corresponding line-end densities;
comparing the plating current with the critical plating current; and
adding one or more organic additives to the plating solution in response to the plating current being below the critical plating current so as to increase the plating current until the plating current is greater than the critical plating current.

2. The method of claim 1 , wherein the monitoring device comprises a probe adapted to be partially immersed in the plating solution.

3. The method of claim 1 , wherein the plating solution comprises a metal salt and organic additives, wherein the control system is configured to adjust an amount of at least one of the organic additives in the plating solution.

4. The method of claim 1 , wherein the ECP system further comprises one or more spin rinse dry cells and one or more substrate bevel cleaning cells.

5. The method of claim 1 , wherein the ECP system further comprises a factory interface comprising a plurality of substrate loading stations.

6. The method of claim 1 , wherein each line-end density is calculated as a ratio of a surface area of the plurality of conductive lines in a corresponding unit grid and an area of the corresponding unit grid.

7. The method of claim 1 , wherein the ECP system further comprises an anneal chamber.

8. The method of claim 7 , wherein the anneal chamber comprises a cooling plate and a heating plate.

9. The method of claim 8 , wherein the ECP system further comprises a substrate transfer robot configured to move the substrate between the cooling plate and the heating plate.

10. A method for depositing a conductive layer on a plurality of substrates, comprising:
introducing the plurality of substrates into an electrochemical plating (ECP) system; comprising:
a plurality of ECP cells, each of the plurality of ECP cells comprising an anode, a substrate holder configured to hold a corresponding substrate of the plurality of substrates to be plated by an ECP process, and a plating bath containing a plating solution for the ECP process;
a plurality of monitoring devices, each of the plurality of monitoring devices being coupled to a corresponding ECP cell of the plurality of ECP cells and configured to in situ measure a plating current flowing through the plating solution between the anode and the corresponding substrate in the corresponding ECP cell;
a plating solution supply system in fluid communication with the plurality of ECP cells and configured to supply the plating solution to each of the plurality of ECP cells; and
a control system configured to control the plurality of ECP cells, the plurality of monitoring devices and the plating solution supply system, immersing each of the plurality of substrates in the plating solution of a corresponding ECP cell;
in situ measuring a plating current flowing through the plating solution between an anode and a corresponding substrate;
comparing the plating current with a critical plating current below which voids start to occur in conductive lines having a highest line-end density in a metallization layer formed over the substrate, wherein the critical plating current is determined by:
receiving a layout data of an integrated circuit to be manufactured on the substrate;
dividing an entire area of the substrate into a plurality of unit grids;
calculating a line-end density of conductive lines in each unit grid of the plurality of unit grids;
identifying a unit grid with the conductive lines having the highest line-end density among the plurality of unit grids; and
determining the critical plating current using a linear model that correlates plating currents which result in defects with corresponding line-end densities; and
adding one or more organic additives to the plating solution in response to the plating current being below the critical plating current so as to increase the plating current until the plating current is greater than the critical plating current.

11. The method of claim 10 , wherein each of the plurality of monitoring devices is a current meter.

12. The method of claim 11 , wherein each of the plurality of monitoring devices comprises a probe configured to be in contact with the plating solution during the ECP process to in situ measure the plating current, wherein the probe comprises a metal to be electrochemically plated on the plurality of substrates.

13. The method of claim 10 , wherein the plating solution comprises a metal salt and organic additives, wherein the control system is configured to adjust an amount of at least one of the organic additives in the plating solution.

14. The method of claim 13 , wherein a quantity of the one or more organic additives being added to the plating solution is controlled to maintain an atomic ratio of carbon and metal in the conductive lines greater than 1%.

15. A method for forming a semiconductor structure, comprising:
depositing a dielectric layer on a substrate;
forming a plurality of contact openings having different line-end densities in the dielectric layer;
depositing a barrier layer along sidewalls and bottoms of the plurality of contact openings and over the dielectric layer;
depositing a seed layer over the barrier layer;
contacting the seed layer with a plating solution comprising a salt of an electrically conductive metal and organic additives comprising a suppressor, an accelerator and a leveler, the plating solution is held in an electrochemical plating (ECP) cell,
applying a plating current to the substrate using a power supply to thereby deposit the electrically conductive metal on the seed layer;
in situ monitoring the plating current as the electrically conductive metal being deposited on the seed layer using a monitoring device;
receiving a layout data of a metallization layer to be manu

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Nian Jun-Nan
• Jangjian Shiu-Ko
• Peng Yu-Ren
• Liang Yao-Hsiang
• Wang Ting-Chun

Classifications

• H10W20/056

  by filling conductive material into holes, grooves or trenches · CPC title

• H10W20/043

  for electroplating · CPC title

• C25D17/001 Primary

  Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells · CPC title

• H10W20/057

  by selectively depositing, e.g. by using selective CVD or plating · CPC title

• C25D7/123 Primary

  Semiconductors first coated with a seed layer or a conductive layer · CPC title