Device and method for handling substrates by means of a self-leveling vacuum system in epitaxial induction

• US 6,648,974 B1
• Filed: 08/07/2001
• Issued: 11/18/2003
• Est. Priority Date: 02/12/1999
• Status: Expired due to Fees

• Current Assignee: LPE S.p.A. (ASM International NV)
• Original Assignee: LPE S.p.A. (ASM International NV)
• Inventors: Pozzetti, Vittorio, Preti, Franco, Ogliari, Vincenzo
• Primary Examiner(s): Hassanzadeh, Parviz
• Assistant Examiner(s): MOORE, KARLA A
• Application Number:
  US09/913,096
• Time in Patent Office: 833 Days
• Field of Search: 118/719, 414/751.1, 414/751.2, 414/941, 156/345.31, 156/345.32
• US Class Current: 118/719
• CPC Class Codes: H01L 21/67748 horizontal transfer of a single workpiece
• CPC Class Codes: H01L 21/6838 with gripping and holding devices using a vacuum; Bernoulli devices
• CPC Class Codes: Y10S 414/141 includes means for gripping wafer
• CPC Class Codes: Y10S 438/907 Continuous processing

Abstract

A device for handling substrates, used in an epitaxial apparatus or reactor (20) for chemical vapour deposition (CVD) onto the said substrates, comprises an internal robot (30) provided with means (60) for gripping and transporting substrates, which are in the form of semiconductor slices (24), in order to transfer them from cassettes (38, 40) containing the semiconductor slices (24) to be processed, the gripping and transportation means (60) having precisely the task of transporting the slices (24), which are present in a purging chamber (34) and supplied from a cassette (38) for storage of the said slices (24), from the purging chamber (34) into a reaction chamber (22) of the epitaxial reactor (20) and, more particularly, into seats (28_a-e) formed on a flat disk-shaped susceptor (26) which is present in the reaction chamber (22) of the epitaxial reactor (20) and vice versa, from the reaction chamber (22) again passing through the purging chamber (34), to the cassettes (38, 40).

Claims

1. Device for handling substrates of materials produced in epitaxial apparatuses or reactors such as slices of semiconductor materials, comprising:

a reaction chamber (22),

an internal robot (30) for handling the substrates or slices (24) of semiconductor materials,

a purging chamber (34) for passing the slices (24) through a cleaning atmosphere,

a storage zone (36) containing cassettes (38, 40) which house, in a stacked arrangement, the slices (24) of semiconductor materials,

an external robot (32) for transferring the slices (24) from the storage zone (36) to the purging chamber (34),

the internal robot (30) comprising a sealed chamber (56) which houses an articulated arm (58) having a gripping means (60) at its external end,

characterized in that the gripping means (60) of the internal robot (30) comprises at least one arm (64) which can be inserted into the reaction chamber (22) and terminating in a gripping tool or hand (70) for removing a slice (24) of semiconductor material from the purging chamber (34) and transporting it, after passing through the sealed chamber (56), so as to be deposited in a recessed seat (28) of a disk-shaped susceptor (26) of the reaction chamber (22), and vice versa, from the recessed seat (28) to the purging chamber (34), where the hand (70) is designed to contact the slice (24) on its uppermost surface along a peripheral zone or chamfered edge (25) and the hand is adapted to grip the slice (24) by means of a vacuum effect, and where the gripping means (60) includes means for attaching it pivotally to the articulated arm (58) in such a manner that when depositing the substrate in the recessed seat (28) the substrate is held inclined to the plane of the recessed seat (28) so as to touch the recessed seat (28) initially only with the slice edge located furthest from the arm (64) of the gripping means (60) before then pivoting about said edge touching the seat to become fully in contact therewith, and vice versa, when transporting a slice (24) from the reaction chamber (22) to the purging chamber (34), the slice gripped by the hand'"'"'s vacuum effect is detached from the recessed seat (28) by first lifting the side of the slice nearest the arm (64) of the gripping means (60) and then detaching the substrate completely, and raising the substrate further whilst being held inclined to the plane of the recessed seat.

2. Device for handling substrates according to claim 1, characterized in that the arm (64) is tubular and hollow, being connected, on one side, by means of a flexible pipe (68) to a vacuum source and, on the other side, to a circular seat (84) formed inside the hand (70) so as to apply a vacuum between a bottom side of the said band (70) and a slice (24) present underneath the hand (70).

3. Device for handling substrates according to claim 2, characterized in that articulation means (62) are arranged between the hollow tubular arm (64) and the articulated arm (58) of the internal robot (30), said means allowing the hollow tubular arm (64) to be raised and lowered so as to bring the hand (70) above and below a plane defined by the articulated arm (58).

4. Device for handling substrates according to claim 3, characterized in that articulation means (62) are arranged between the hollow tubular arm (64) and the articulated arm (58) of the internal robot (30), said means also allowing a rotation of the hollow tubular arm (64) about its longitudinal axis.

5. Device for handling substrates according to claim 4, characterized in that the articulation means (62) comprise a support bearing (96) which is fixed to the articulated arm (58) and carries a rotating pin (98) about which the articulation means (62) rotate, and an adjusting screw (100) for fixing the permitted heights for raising and lowering of the hand (70) with respect to the plane of the articulated arm (58), so that the hand can rest in the radial direction on the disk-shaped susceptor (26) only with the front part, only with the rear part or perfectly level with the said susceptor (26).

6. Device for handling substrates according to claim 5, characterized in that the articulation means (62) also comprise, around the hollow tubular arm (64), anti-fiction bushes (63, 65) for allowing alignment of the said hand (70), in a direction perpendicular to the radius of the disk-shaped susceptor (26).

7. Device for handling substrates according to claim 6, characterized in that the hand (70) is in the form of a disk with a diameter greater than the diameter of the slice (24) to be handled and has a bottom part (74), facing the slice (24), provided with a recessed seat which engages only with an external peripheral rim (25) of the said slice (24).

8. Device for handling substrates according to claim 7, characterized in that the seat is present on a bottom part (74) of the hand (70) and is provided with a plurality of peripheral holes (86) connected to a chamber (84) inside the said hand (70) which, in turn, is connected to the hollow tubular arm (64) so as to apply a vacuum between the slice (24) and the hand (70).

9. Device for handling substrates according to claim 8, characterized in that the peripheral holes (86) are concentrated mainly where the greatest losses in vacuum are envisaged.

10. Device for handling substrates as recited in any one of claims 1-9, characterized in that a laser telemeter is used to measure a distance between a laser emitter and the disk-shaped susceptor (26) of the reaction chamber (22), in question, producing an analogue signal proportional to the said distance, where said telemeter detects defects in the level arrangement of the susceptor (26) as well as defects in the parallel positioning of the susceptor (26) with respect to the reaction chamber (22).

11. Device for handling substrates according to claim 10, characterized in that a notch formed in the external rim of the susceptor (26) is used as an angular reference point which can be detected by the laser telemeter and the recessed seats (28) for the slices (24) are counted starting from this notch.

12. Method for placing a slice (24) in a recessed seat (28) of a disk-shaped susceptor (26), present in a reaction chamber (22), by means of a hand (70) of a device according to any one of claims 1-9, characterized in that a slice (24), which is made to adhere to the hand (70) by means of a vacuum, enters into the reaction chamber (22) in the raised position, is transported to above one of the recessed seats (28) of the disk-shaped susceptor (26), is lowered so as to be placed onto the said seat (28), remaining inclined forwards so as to touch the recessed seat (28) initially only with the slice edge located farthest from the arm (64) of the gripping means (60), and then, after removal of the vacuum which keeps the slice (24) attached to the hand (70), is further lowered, detaching the hand (70) from the slice (24), and then the hand (70) is raised again, being detached entirely from the slice (24), and finally is retracted, leaving the reaction chamber (22).

13. Method for removing a slice (24) from a recessed seat (28) of a disk-shaped susceptor (26), present in a reaction chamber (22), by means of a hand (70) of a device according to any one of claims 1-9, characterized in that the hand (70) enters into the reaction chamber (22) in the raised position, is transported to above a slice (24) housed in one of the recessed seats (28) of the disk-shaped susceptor (26), is lowered until it touches the slice (24), first at the edge located farthest from the arm (64) of the gripping means (60) and then over the entire circumference of the slice (24) and then, after touching the slice over the entire circumference, applies a vacuum so as to cause the slice (24) to adhere with its edge (25) onto the hand (70) and then starts to move up again;

detaching the slice (24) from the recessed seat (28), first at the edge located nearest the arm (64) of the gripping means (60) and then over the entire surface of the slice (24), and finally, after the slice (24) has been raised completely from the recessed seat (28) of the susceptor (26), transports it outside the reaction chamber (22).

14. Method according to claim 13, characterized in that, in order to avoid excessive deformations of the slices (24) due to warping, a vacuum is applied to the hand (70), said vacuum being at a maximum at the start of engagement of the slices (24) by the said hand (70), when the slices (24) are not fully in contact with the hand (70), but subsequently means for adjusting the vacuum reduce the said vacuum to a minimum value sufficient to maintain adhesion between slices (24) and hand (70) without causing substantial deformation of the slices (24).

15. The method according to claim 12, characterized in that, in order to avoid excessive deformations of the slices (24) due to warping, a vacuum is applied to the hand (70), said vacuum being at a maximum at the start of engagement of the slices (24) by the said band (70), when the slices (24) are not fully in contact with the band (70), but subsequently means for adjusting the vacuum reduce the said vacuum to a minimum value sufficient to maintain adhesion between slices (24) and hand (70) without causing substantial deformation of the slices (24).