Apparatus and method for wafer cleaning

• US 6,648,979 B2
• Filed: 01/24/2001
• Issued: 11/18/2003
• Est. Priority Date: 01/24/2001
• Status: Expired due to Term

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Lofaro, Michael F., Stevens, Leonard C. Jr., Mattaroccia, Marc
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): Winter, Gentle E
• Application Number:
  US09/768,833
• Publication Number:
  US 20020096191A1
• Time in Patent Office: 1,028 Days
• Field of Search: 134/2, 134/6, 134/21, 134/32, 134/44, 134/84, 134/104.2, 134/137, 134/140, 451/10, 451/111, 451/286, 451/288, 451/287, 451/394, 451/331
• US Class Current: 134/6
• CPC Class Codes: B08B 1/32 using rotary cleaning members
• CPC Class Codes: H01L 21/67046 using mainly scrubbing means, e.g. brushes

Abstract

A semiconductor wafer is cleaned while a sponge or brush is pressed against the wafer with a constant forced applied utilizing a bias in a constant force pencil. The wafer is cleaned in the state wherein a collapsing portion of the constant force pencil with respect to the cleaning sponge cloth is set in such a way that the cleaning pressure, which is applied from the cleaning sponge to the wafer, can be constant and is adjustable. A method for cleaning wafers using a constant force pencil is also described.

Claims

1. A wafer cleaning apparatus comprising:

a carrier sustaining a wafer against a cleaning agent, said wafer intermediate said carrier and said cleaning agent;

a liquid supply furnishing cleaning liquid to a surface of said wafer for cleaning;

an end effector having a first end and a second end,

wherein said end effector includes a cleaning head comprising;

a holder depending from a shaft, said holder having a plurality of holes;

a plurality of studs having heads disposed on a first side of said holder, said plurality of studs slidably extending through said plurality of holes and extending on a second side of said holder;

a base portion having one end coupled to said holder with said plurality of studs, wherein said base portion is biased towards said wafer and allowed to vertically translate to and from said holder, limited by a length of said plurality of studs intermediate of said base portion and said second side of said holder; and

a cleaning agent extending from an other end of said base portion, said cleaning agent correspondingly allowed to vertically translate with said base portion relative to a support surface sustaining the wafer against said cleaning agent;

said end effector holding said cleaning agent at said first end, said second end having a fixed distance to a surface of said carrier sustaining said wafer, said cleaning agent having a floating movement relative to said surface of said carrier and floating movement perpendicular to said surfaces of said wafer and said carrier, said cleaning agent having a bias towards said wafer that provides a constant force against said wafer independent of the topography of said surface of said wafer, said cleaning agent operably cleans said surface of said wafer in surface contact with said cleaning agent by slidable contact therebetween; and

an arm assembly and a shaft capable of supporting said end effector at said second end.

2. The wafer cleaning apparatus in claim 1, wherein said end effector comprises:

a holder depending from said shaft, said holder having a plurality of holes;

a plurality of studs having heads disposed on a first side of said holder, said plurality of studs slidably extending through said plurality of hales and extending on a second side of said holder;

a base portion having one end coupled to said holder with said plurality a studs, wherein said base portion biased towards said wafer and allowed to vertically translate to and from said holder, limited by a length of said plurality of scuds intermediate of said base portion and said second side of said holder; and

said cleaning agent extending from an other end of said base portion, said cleaning agent correspondingly allowed to vertically translate with said base portion relative to a support surface sustaining the wafer against said cleaning agent.

3. The wafer cleaning apparatus in claim 2, wherein said base portion comprises:

a housing having an edge attachable to said plurality of studs; and

a cleaning agent holder depending to said housing and having a cleaning agent at one end, and at the other end, having a ledge with a plurality of holes aligned with said plurality of holes in said holder, said ledge depending to said edge of said housing.

4. The wafer cleaning apparatus in claim 3, wherein said plurality of studs have a shoulder opposite said head;

said shoulder having a diameter larger than a diameter of said plurality of holes on said ledge.

5. The wafer cleaning apparatus in claim 4, wherein said plurality of studs further includes a threaded end opposite said head for attaching to said housing and wherein said shoulder biases said ledge towards said housing.

6. The water cleaning apparatus in claim 1, wherein said cleaning agent is one of a sponge and a brush operably cleaning said wafer.

7. The wafer cleaning apparatus in claim 2, wherein said bias towards said wafer includes a weight of said base portion.

8. The wafer cleaning apparatus in claim 2, wherein said bias towards said wafer includes weight added to said base portion.

9. The wafer cleaning apparatus in claim 2, wherein said bias towards said wafer includes a bias intermediate said holder and said base portion.

10. The wafer cleaning apparatus in claim 2, wherein said bias towards said wafer includes a spring disposed around each said plurality of studs.

11. The wafer cleaning apparatus in claim 3, wherein said housing further includes at least one orifice for receiving one of at least one weight for biasing said cleaning agent towards said wafer.

12. A cleaning head for use in cleaning a semiconductor wafer, the cleaning head comprising:

a holder depending from a shaft, said holder having a plurality of holes;

a plurality of studs having heads disposed on a first side of said holder, said plurality of studs slidably extending through said plurality of holes and extending on a second side of said holder;

a base portion having one end coupled to said bolder wit said plurality of studs, wherein said base portion is biased towards said wafer aid allowed to vertically translate to and from said holder, limited by a length of said plurality of studs intermediate of said base portion and said second side of said holder; and

a cleaning agent extending from an other end of said base portion, said clawing agent correspondingly allowed to vertically translate with said base portion relative to a support surface sustaining the wafer against said cleaning agent.

13. The cleaning head in claim 12, wherein said base portion comprises:

a housing having an edge attachable to said plurality of studs; and

a cleaning agent holder depending to said housing and having a cleaning agent at one end, and at the other end, having a ledge with a plurality of holes aligned with said plurality of holes in said holder, said ledge depending to said edge of said housing.

14. The cleaning head in claim 13, wherein said plurality of studs have a shoulder opposite said head;

said shoulder having a diameter larger than a diameter of said plurality of holes on said ledge.

15. The cleaning head in claim 14, wherein said plurality of studs further includes a threaded end opposite said head for attaching to said housing and wherein said shoulder biases said ledge towards said housing.

16. The cleaning head claim 12, wherein said cleaning agent is one of a sponge and a brush for cleaning said wafer.

17. The cleaning head in claim 12, wherein said bias towards said wafer includes weight added to said base portion.

18. The cleaning head in claim 12, wherein said bias towards said wafer includes at least one weight added to said base portion.

19. The cleaning head in claim 12, wherein said bias towards said wafer includes a bias intermediate said holder and said base portion.

20. The cleaning head in claim 12, wherein said bias towards said wafer includes a spring disposed around each said plurality of studs.

21. The cleaning head in claim 13, wherein said housing further includes at least one orifice for receiving one of at least one weight for biasing said cleaning agent towards said wafer.

22. A method for cleaning a semiconductor wafer comprising:

providing a wafer cleaning assembly for cleaning a surface of a semiconductor wafer;

using a constant applied force for cleaning uniformity, the wafer cleaning assembly including a carrier rotatable about a first axis and holding said wafer, a cleaning head with a cleaning agent having a bias that applies a constant force to said wafer surface and rotating about a second axis;

wherein the cleaning head comprises;

a holder depending from a shaft, said holder having a plurality of holes;

a plurality of studs having heads disposed on a first side of said holder, said plurality of studs slidably extending through said plurality of holes and extending on a second side of said holder;

a base portion having one end coupled to said holder with said plurality of studs, wherein said base portion is biased towards said wafer and allowed to vertically translate to and from said holder, limited by a length of said plurality of studs intermediate of said base portion and said second side of said holder; and

a cleaning agent extending from an other end of said base portion, said cleaning agent correspondingly allowed to vertically translate with said base portion relative to a support surface sustaining the wafer against said cleaning agent;

and a cleaning head displacement arm assembly which moves the cleaning head across said carrier and wafer and has a vertical adjustment to set height of cleaning head above wafer;

using a liquid supply for furnishing liquid to said surface of said wafer for cleaning;

using said wafer cleaning assembly to clean said surface of a semiconductor wafer at a cleaning uniformity according to a set of controllable operational parameters that upon variation change cleaning rate and cleaning uniformity;

using said vertical adjustment to set height of cleaning head above wafer such that cleaning agent contacts wafer under the bias within a midrange of a full allowable range;

monitoring in situ at least one of said operational parameters of said wafer cleaning assembly; and

adjusting in situ at least one of the operational parameters in response to the control information to effectuate a new cleaning rate and a new cleaning uniformity and then continuing cleaning of said semiconductor wafer surface according to said new cleaning rate and new cleaning uniformity.

23. A method according to claim 22 further comprising varying the bias of said cleaning head by one of adding weight and eliminating weight from said cleaning head.

24. A method according to claim 22 further comprising varying the bias of said cleaning head by using springs to bias cleaning agent towards wafer.