Pretreatment method for photoresist wafer processing

• US 9,607,822 B2
• Filed: 09/13/2016
• Issued: 03/28/2017
• Est. Priority Date: 04/21/2014
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Buckalew, Bryan L., Rea, Mark L.
• Primary Examiner(s): Henry, Caleb
• Assistant Examiner(s): Belousov, Alexander
• Application Number:
  US15/264,262
• Publication Number:
  US 20170011906A1
• Time in Patent Office: 196 Days
• US Class Current: 1/1
• CPC Class Codes: C23C 18/1605 by masking
• CPC Class Codes: C23C 18/1803 of metallic material surfaces or of a non-specific material surfaces
• CPC Class Codes: C25D 5/022 using masking means
• CPC Class Codes: C25D 5/34 Pretreatment of metallic surfaces to be electroplated
• CPC Class Codes: C25D 5/48 After-treatment of electroplated surfaces
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: G03F 7/427 using plasma means only
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32889 Connection or combination with other apparatus
• CPC Class Codes: H01J 37/32899 Multiple chambers, e.g. cluster tools
• CPC Class Codes: H01L 21/0206 during, before or after processing of insulating layers
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/6723 comprising at least one plating chamber electroless plating apparatuses C23C, electroplating apparatuses C25D
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76885 By forming conductive members before deposition of protective insulating material, e.g. pillars, studs
• CPC Class Codes: H01L 2224/0361 Physical or chemical etching
• CPC Class Codes: H01L 2224/0381 Cleaning, e.g. oxide removal step, desmearing
• CPC Class Codes: H01L 2224/03912 the bump being used as a mask for patterning the bonding area
• CPC Class Codes: H01L 2224/0401 : Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05023 : the whole internal layer protruding from the surface
• CPC Class Codes: H01L 2224/05557 : comprising protrusions or indentations
• CPC Class Codes: H01L 2224/05568 : the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05647 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/11462 : Electroplating
• CPC Class Codes: H01L 2224/1147 : using a lift-off mask
• CPC Class Codes: H01L 2224/1161 : Physical or chemical etching
• CPC Class Codes: H01L 2224/1181 : Cleaning, e.g. oxide removal step, desmearing
• CPC Class Codes: H01L 2224/13018 : comprising protrusions or indentations
• CPC Class Codes: H01L 2224/1308 : being stacked
• CPC Class Codes: H01L 2224/13111 : Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/13147 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13155 : Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 24/03 : Manufacturing methods
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/11 : Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 : of an individual bump connector
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/014 : Solder alloys

Abstract

Certain embodiments herein relate to methods and apparatus for processing a partially fabricated semiconductor substrate in a remote plasma environment. The methods may be performed in the context of wafer level packaging (WLP) processes. The methods may include exposing the substrate to a reducing plasma to remove photoresist scum and/or oxidation from an underlying seed layer. In some cases, photoresist scum is removed through a series of plasma treatments involving exposure to an oxygen-containing plasma followed by exposure to a reducing plasma. In some embodiments, an oxygen-containing plasma is further used to strip photoresist from a substrate surface after electroplating. This plasma strip may be followed by a plasma treatment involving exposure to a reducing plasma. The plasma treatments herein may involve exposure to a remote plasma within a plasma treatment module of a multi-tool electroplating apparatus.

Claims

1. A method of removing photoresist scum and electroplating metal into photoresist features, the method comprising:

(a) receiving a substrate in a multi-tool electroplating apparatus, the multi-tool electroplating apparatus comprising;

(i) at least one plasma treatment module comprising a plasma treatment chamber and a plasma generation chamber connected to the plasma treatment chamber; and

(ii) at least one electroplating module comprising an electroplating chamber;

wherein the substrate comprises;

(i) a metal seed layer, and

(ii) a layer of photoresist over and directly in contact with the metal seed layer, wherein the layer of photoresist comprises photoresist features patterned therein, and wherein a bottom of the photoresist features comprise photoresist scum;

(b) generating a reducing plasma from a reducing plasma generation gas in the plasma generation chamber;

(c) flowing the reducing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the reducing plasma, react the photoresist scum with the reducing plasma, and remove at least a portion of the photoresist scum; and

(d) transferring the substrate to the electroplating module and electroplating metal on the metal seed layer in the photoresist features.

2. The method of claim 1, wherein the reducing plasma generation gas comprises one or more of hydrogen, ammonia, nitrogen, carbon monoxide, diborane, sulfite compounds, hydrocarbons, phosphites, and/or hydrazine.

3. The method of claim 1, wherein the reducing plasma generation gas comprises hydrogen.

4. The method of claim 1, further comprising:

(e) after electroplating in (d), transferring the substrate to the plasma treatment chamber, generating a stripping plasma in the plasma generation chamber from a stripping plasma generation gas, flowing the stripping plasma from the plasma generation chamber into the plasma treatment chamber, exposing the substrate to the stripping plasma, and thereby reacting the stripping plasma with the layer of photoresist to strip the layer of photoresist from the substrate.

5. The method of claim 4, wherein the stripping plasma generation gas comprises oxygen and/or CO₂.

6. The method of claim 4, wherein operation (e) forms oxidized portions of the metal seed layer, and further comprising:

(f) after stripping the layer of photoresist in (e), generating a second reducing plasma in the plasma generation chamber from a second reducing plasma generation gas, flowing the second reducing plasma from the plasma generation chamber into the plasma treatment chamber, exposing the substrate to the second reducing plasma, and thereby reacting the oxidized portions of the metal seed layer with the second reducing plasma to reduce the oxidized portions of the metal seed layer.

7. The method of claim 6, wherein the second reducing plasma generation gas comprises one or more of hydrogen, ammonia, nitrogen, carbon monoxide, diborane, sulfite compounds, hydrocarbons, phosphites, and/or hydrazine.

8. The method of claim 1, wherein the reducing plasma is substantially free of oxidizing species.

9. The method of claim 8, wherein the layer of photoresist is not exposed to an oxidizing plasma between the time it is developed and the time at which operations (b)-(c) occur.

10. A multi-tool electroplating apparatus for removing photoresist scum and electroplating metal in features on a semiconductor substrate having a metal seed layer under an exposed layer of patterned photoresist, comprising:

(i) a plasma treatment module comprising a plasma treatment chamber connected with a plasma generation chamber;

(ii) an electroplating module comprising an electroplating chamber;

(iii) a transfer mechanism for transferring the substrate between the plasma treatment module and the electroplating module; and

(iv) a controller having instructions to;

(a) transfer the substrate into the plasma treatment chamber of the plasma treatment module;

(b) generate a reducing plasma in the plasma generation chamber from a reducing plasma generation gas, and flow the reducing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the reducing plasma and react the photoresist scum with the reducing plasma to remove at least a portion of the photoresist scum;

(c) transfer the substrate from the plasma treatment chamber to the electroplating chamber via the transfer mechanism; and

(d) electroplate metal on the metal seed layer in the features in the patterned photoresist.

11. The apparatus of claim 10, the controller further having instructions to:

(e) after electroplating in (d), transfer the substrate from the electroplating chamber to the plasma treatment chamber via the transfer mechanism;

(f) generate a stripping plasma in the plasma generation chamber from a stripping plasma generation gas, and flow the stripping plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the stripping plasma and react the stripping plasma with the layer of patterned photoresist to strip the patterned photoresist from the substrate.

12. The apparatus of claim 11, the controller further having instructions to:

(g) after stripping photoresist in (f), generate a second reducing plasma in the plasma generation chamber from a second reducing plasma generation gas, and flow the second reducing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the second reducing plasma and react the second reducing plasma with oxidized portions of the metal seed layer to thereby reduce the oxidized portions of the metal seed layer.

13. A multi-tool electroplating apparatus for removing photoresist scum and electroplating metal in features on a semiconductor substrate having a metal seed layer under an exposed layer of patterned photoresist, comprising:

(i) a plasma treatment module comprising a plasma treatment chamber connected with a plasma generation chamber;

(ii) an electroplating module comprising an electroplating chamber;

(iii) a transfer mechanism for transferring the substrate between the plasma treatment module and the electroplating module; and

(iv) a controller having instructions to;

(a) transfer the substrate into the plasma treatment chamber of the plasma treatment module;

(b) generate a first oxidizing plasma in the plasma generation chamber from a first oxidizing plasma generation gas, and flow the first oxidizing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the first oxidizing plasma and react the first oxidizing plasma with the photoresist scum to remove at least a portion of the photoresist scum and form oxidized portions of the metal seed layer;

(c) generate a reducing plasma in the plasma generation chamber from a reducing plasma generation gas, and flow the reducing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the reducing plasma and react the oxidized portions of the metal seed layer with the reducing plasma to reduce the oxidized portions of the metal seed layer;

(d) transfer the substrate from the plasma treatment chamber to the electroplating chamber via the transfer mechanism; and

(e) electroplate metal on the metal seed layer in the features in the patterned photoresist.

14. The apparatus of claim 13, the controller further having instructions to:

(f) after electroplating in (e), transfer the substrate from the electroplating chamber to the plasma treatment chamber via the transfer mechanism;

(g) generate a stripping plasma in the plasma generation chamber from a stripping plasma generation gas, and flow the stripping plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the stripping plasma and react the stripping plasma with the layer of patterned photoresist to strip the patterned photoresist from the substrate.

15. The apparatus of claim 14, wherein operation (g) results in formation of oxidized portions of the metal seed layer, the controller further having instructions to:

(h) after stripping photoresist in (g), generate a second reducing plasma in the plasma generation chamber from a second reducing plasma generation gas, and flow the second reducing plasma from the plasma generation chamber into the plasma treatment chamber to thereby expose the substrate to the second reducing plasma and react the second reducing plasma with the oxidized portions of the metal seed layer to reduce the oxidized portions of the metal seed layer.