US-12624317-B2 - Method of reducing defects on polished wafers

Abstract

This disclosure relates to a method that includes applying a polishing composition to a surface of a substrate; bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate to create a polished substrate; treating the polished substrate with a rinse solvent; flowing a vapor over a meniscus formed at an interface between air and the rinse solvent on the polished substrate. The vapor includes a first component containing a water miscible organic solvent, a second component containing a cleaning agent, and a third component containing an inert gas.

Inventors

• Bin Hu
• Binh Duong
• Carl Ballesteros
• Yannan Liang
• Hyosang Lee

Assignees

• FUJIFILM ELECTRONIC MATERIALS U.S.A., INC.

Dates

Publication Date

20260512

Application Date

20221215

Claims (18)

1. 1 . A method, comprising: applying a polishing composition to a surface of a substrate; bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate to create a polished substrate; treating the polished substrate with a rinse solvent; mixing an inert gas with a concentrate to form a vapor, wherein the concentrate comprises a first component comprising a water miscible organic solvent and a second component comprising a cleaning agent; and flowing the vapor over a meniscus formed at an interface between air and the rinse solvent on the polished substrate.
2. 2 . The method of claim 1 , wherein the first component has a vapor pressure at 20° C. from about 1 kPa to about 250 kPa.
3. 3 . The method of claim 1 , wherein the first component is selected from the group consisting of ethanol, isopropyl alcohol, propylene glycol n-propyl ether, n-methylpyrrolidone, acetone, tetrahydrofuran, isopentyl acetate, and mixtures thereof.
4. 4 . The method of claim 1 , wherein the second component is from about 0.001 wt % to about 5 wt % of the concentrate.
5. 5 . The method of claim 1 , wherein the concentrate is from about 0.001 wt % to about 90 wt % of the vapor.
6. 6 . The method of claim 1 , wherein the inert gas is selected from the group consisting of nitrogen, helium, argon, and mixtures thereof.
7. 7 . The method of claim 1 , wherein the rinse solvent comprises water.
8. 8 . The method of claim 1 , wherein the vapor has a flow rate from about 0.01 to about 50 standard liter per minute.
9. 9 . The method of claim 1 , wherein flowing the vapor is performed by spraying the vapor over the meniscus.
10. 10 . The method of claim 1 , further comprising forming a semiconductor device from the substrate.
11. 11 . The method of claim 1 , wherein the second component is an organic base that includes nitrogen.
12. 12 . The method of claim 11 , wherein the organic base has a molecular weight at most about 150 g/mol.
13. 13 . The method of claim 11 , wherein the organic base has a boiling point of from about 30° C. to about 170° C. at a pressure of 1 atm.
14. 14 . The method of claim 1 , wherein the second component is selected from the group consisting of a tetraalkylammonium hydroxide, 1-methylpiperidine, 4-methylpiperidine, 1,1,3,3,-tetramethylguanidine, morpholine, piperidine, 3-methoxypropylamine, dipropylamine, isopropylamine, and mixtures thereof.
15. 15 . The method of claim 14 , wherein the tetraalkylammonium hydroxide is selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, ethyltrimethylammonium hydroxide, diethyldimethyl-ammonium hydroxide, and mixtures thereof.
16. 16 . The method of claim 1 , wherein treating the polished substrate with a rinse solvent comprises placing the polished substrate into a rinse bath comprising the rinse solvent.
17. 17 . The method of claim 16 , further comprising removing the polished substrate from the rinse bath while flowing the vapor.
18. 18 . The method of claim 17 , wherein the vapor is flowed over the meniscus formed at an interface between air and the rinse solvent while removing the polished substrate from the rinse bath, and the vapor is flowed in the direction that the rinse solvent is removed from the polished substrate.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority to U.S. Provisional Application Ser. No. 63/292,511, filed on Dec. 22, 2021, the contents of which are hereby incorporated by reference in their entirety. BACKGROUND As semiconductor device geometries continue to decrease, the importance of ultra clean processing increases as even small amounts of contaminants/residue can dramatically impact device performance. Compared with other processing steps, chemical mechanical polishing/planarization (CMP) is a highly contaminating process because the substrate is contacted with a polishing composition that includes abrasives (inorganic particles) and chemical components that act on the substrate surface, both of which can leave behind residue/contamination. Post-chemical mechanical polishing (pCMP) and/or aqueous cleaning within a tank of fluid (or a bath) followed by a rinsing bath (e.g., within a separate tank, or by replacing the cleaning tank fluid) may be employed to try to remove defects after a polishing step. After removal from the rinsing bath, absent use of a drying apparatus, bath fluid may evaporate from the substrate's surface and cause streaking, spotting and/or leave bath residue on the surface of the substrate. Such streaking, spotting and residue can cause subsequent device failure. Accordingly, much attention has been directed to improved methods for drying a substrate as it is removed from an aqueous bath. Moreover, the aqueous cleaning steps taken prior to the rinse bath (e.g., post-CMP cleaning and/or using an aqueous cleaning tank) may not adequately clean organic or inorganic residue left behind from the CMP processes performed on the wafer. A method known as Marangoni drying (also referred to as surface tension gradient drying or IPA vapor drying) creates a surface tension gradient to induce bath fluid to flow from the substrate in a manner that leaves the substrate virtually free of bath fluid, and thus may avoid streaking, spotting and residue marks. Achieving uniform Marangoni drying of a substrate can be difficult and in some cases particles from the bath fluid may re-attach to, and thus contaminate, the substrate in addition to any contamination that might remain after the post-polish cleaning steps. As such, methods for reducing defects during substrate rinsing and/or drying could be useful to the semiconductor industry. SUMMARY This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. In one aspect, this disclosure features a method that includes (1) applying a polishing composition to a surface of a substrate; (2) bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate to create a polished substrate; (3) treating the polished substrate with a rinse solvent; and (4) flowing a vapor over a meniscus formed at an interface between air and the rinse solvent on the polished substrate. The vapor can include a first component containing a water miscible organic solvent, a second component containing a cleaning agent, and a third component containing an inert gas. Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. DETAILED DESCRIPTION Embodiments disclosed herein relate generally to methods of polishing a substrate and drying said polished substrate (e.g., a polished semiconductor substrate). As mentioned above, with the continued miniaturization of feature size in advanced semiconductor components, the minimization of defects on semiconductor substrates during the multitude of production steps involved in their production has taken on heightened importance. This increased importance has promoted a flurry of activity in the post-CMP cleaning field, with new cleaner formulations developed for the brush box cleaning that commonly takes place after a polished substrate is removed from the polishing platen of a polishing machine and interest in methods of “buffing” polished substrates while they are still on the polishing platen with formulations that include substantially zero abrasives. However, even after all of the above steps have been performed, residues/contaminants (e.g., organic residue, pad residue, inorganic/abrasive residue) still commonly exist on the polished substrates. To reduce these persistent contaminants and thereby improve the device yield of polished substrates, the present inventors have developed a method that includes adding a cleaning agent to the volatile vapor that is used in the substrate drying step (e.g., a vapor drying step), which is typically the final step performed after a polished substrate has been processed via CMP and the various stages of pCMP