Moment cancelling pad raising mechanism in wafer positioning pedestal for semiconductor processing

Patent metadata

Field	Value
Publication number	US-9960068-B1
Application number	US-201615367903-A
Country	US
Kind code	B1
Filing date	Dec 2, 2016
Priority date	Dec 2, 2016
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

An assembly used in a process chamber for depositing a film on a wafer including a pedestal assembly having a pedestal movably mounted to a main frame. A lift pad rests upon the pedestal and moves with the pedestal. A raising mechanism separates the pad from the pedestal, and includes a hard stop fixed to the main frame, a roller attached to the pedestal assembly, a slide moveably attached to the pedestal assembly, a lift pad bracket interconnected to the slide and a pad shaft extending from the lift pad, a lever rotatably attached to lift pad bracket, a ferroseal assembly surrounding the pad shaft, and a yoke assembly offsetting a moment to the ferroseal assembly when the lever rotates. When the pedestal assembly moves upwards, the lever rotates when engaging with the upper hard stop and roller, and separates the pad from the pedestal by a process rotation displacement.

First claim

What is claimed is:

1. An assembly for use in a process chamber for depositing a film on a wafer, comprising:
a pedestal assembly including a pedestal movably mounted to a main frame;
a lift pad configured to rest upon a pedestal top surface of the pedestal and move with the pedestal assembly; and
a lift pad raising mechanism configured to separate the lift pad from the pedestal, the lift pad raising mechanism including:
a lever assembly configured to translate with respect the pedestal assembly when actuated;
a ferroseal assembly surrounding the pad shaft and configured to provide a vacuum seal about the pad shaft, the ferroseal assembly interconnected to the lever assembly; and
a yoke assembly interconnected to the lever assembly and is configured to apply equal forces to opposing sides of the ferroseal assembly to offset a moment that is applied to the ferroseal assembly when the lever assembly is actuated.

2. The assembly of claim 1 , wherein the lever assembly comprises:
an upper hard stop fixed in relation to the main frame;
a first roller attached to the pedestal assembly;
a slide moveably attached to the pedestal assembly;
a lift pad bracket interconnected to the slide and interconnected to a pad shaft, wherein the pad shaft extends from the lift pad along a central axis; and
a lever rotatably attached to the lift pad bracket through a pin, wherein the lever rests on the first roller in a neutral position when not engaged with the upper hard stop;
wherein when the pedestal assembly is moving upwards, the lever is configured to rotate about the pin when engaged with the upper hard stop and first roller, and separate the lift pad from the pedestal top surface by a process rotation displacement.

3. The assembly of claim 2 , further comprising:
wherein the ferroseal assembly is attached to the pad shaft at a first end of the ferroseal assembly, wherein the ferroseal assembly includes a first connector arm and a second connector arm located at a second end opposite the first end of the ferroseal assembly, the first connector arm and second connector arm located on opposing sides of the ferroseal assembly and equidistant from the pad shaft; and
wherein the yoke assembly contacts the ferroseal assembly at the first connector arm and the second connector arm, wherein the yoke assembly applies equal forces to the first connector arm and the second connector arm, wherein the first connector arm and the second connector arm are located 180 degrees apart about the central axis.

4. The assembly of claim 3 , wherein the yoke assembly includes:
a yoke base rotatably attached to the lift pad bracket through a second pin, wherein the yoke base is rotatable about a pin axis;
a yoke arm attached to the yoke base and extending from the yoke base in parallel to the pin axis, the yoke arm offset from the pin by a radial displacement, wherein the yoke arm is rotatable about the pin axis; and
a forked end to the yoke arm distal from the yoke base, the forked end including a first fork extension configured to come into contact the first connector arm, and a second fort extension configured to come into contact with the second connector arm.

5. The assembly of claim 2 , wherein the lift pad raising mechanism further includes:
a rotation motor attached to the pad shaft through a belt, both of which are configured to rotate the pad shaft about the central axis;
wherein the ferroseal assembly includes a belt driven disk attached to the belt and attached to the pad shaft.

6. The assembly of claim 2 , wherein the pedestal assembly further comprises:
a pedestal bracket attached to the pedestal and moveably attached to the main frame, wherein the pedestal bracket is configured to move the pedestal along the central axis in relation to the main frame; and
a central shaft extending from the pedestal along the central axis, the central shaft configured to move with the pedestal; and
wherein the pad shaft is configured to separate the lift pad from the pedestal, and is positioned within the central shaft.

7. The assembly of claim 2 , wherein when the lever is rotating about the pin, the lift pad bracket and slide together move upwards in relation to the pedestal assembly, such that the lift pad is configured to move up relative to the pedestal top surface along the central axis.

8. The assembly of claim 2 , wherein there is no relative movement between the lever and the pedestal assembly when the lever is in the neutral position and not engaging with the upper hard stop.

9. The assembly of claim 2 , wherein a diameter of a pad top surface is approximately sized to a wafer diameter.

10. The assembly of claim 2 , wherein a diameter of a pad top surface is smaller than a wafer diameter.

11. The assembly of claim 2 , wherein the lift pad is configured to rotate relative to the pedestal top surface when separated from the pedestal between at least a first angular orientation and a second angular orientation.

12. The assembly of claim 1 , wherein the lift pad sits within a recess of the pedestal top surface.

13. An assembly for use in a process chamber for depositing a film on a wafer, comprising:
a pedestal assembly including a pedestal movably mounted to a main frame;
a lift pad configured to rest upon a pedestal top surface of the pedestal and move with the pedestal assembly; and
a lift pad raising mechanism configured to separate the lift pad from the pedestal, the lift pad raising mechanism including:
an upper hard stop fixed in relation to the main frame;
a lower hard stop fixed in relation to the main frame, and located below the upper hard stop with reference to the main frame;
a first roller attached to the pedestal assembly;
a second roller attached to the pedestal assembly;
a slide moveably attached to the pedestal assembly;
a lift pad bracket interconnected to the slide and interconnected to a pad shaft, wherein the pad shaft extends from the lift pad along a central axis;
a lever rotatably attached to the lift pad bracket through a pin, wherein the lever rests on the first roller in a neutral position when not engaged with the upper hard stop;
a ferroseal assembly surrounding the pad shaft and configured to provide a vacuum tight seal about the pad shaft while the pad shaft is static and rotating; and
a yoke assembly interconnected to the lift pad bracket and is configured to apply equal forces to opposing sides of the ferroseal assembly to offset a moment applied to the ferroseal assembly when the lever rotates about the pin;
wherein when the pedestal assembly is moving upwards, the lever is configured to rotate about the pin when engaged with the upper hard stop and first roller, and separate the lift pad from the pedestal top surface by a process rotation displacement;
wherein when the pedestal assembly is moving downwards, the lever is configured to rotate about the pin when engaged with the lower hard stop and second roller and separate the lift pad from the pedestal by an end effector access displacement.

14. The assembly of claim 13 , further comprising:
wherein the ferroseal assembly is attached to the pad shaft at a first end of the ferroseal assembly, wherein the ferroseal assembly includes a first connector arm and a second connector arm located at a second end opposite the first end of the ferroseal assembly, the first connector arm and second connector arm located on opposing sides of the ferroseal assembly and equidistant from the pad shaft; and
wherein the yoke assembly contacts the ferroseal assembly at the first connector arm and the second connector arm, wherein the yoke assembly applies e

Assignees

• Lam Res Corp

Inventors

• Konkola Paul
• Leeser Karl F
• Srinivasan Easwar

Classifications

• H10P72/7626

  characterised by the construction of the shaft · CPC title

• H10P72/7624

  characterised by the mechanical construction of the susceptor, stage or support · CPC title

• H10P72/7612

  characterised by lifting arrangements, e.g. lift pins · CPC title

• H10P72/0434

  mainly by convection · CPC title

• H10P72/0432

  mainly by conduction · CPC title