Measuring device and method for measuring layer thicknesses and defects in a wafer stack

• US 10,008,424 B2
• Filed: 02/25/2016
• Issued: 06/26/2018
• Est. Priority Date: 11/12/2010
• Status: Active Grant

• Current Assignee: EV Group E Thallner GmbH (Thallner Privatstiftung)
• Original Assignee: EV Group E Thallner GmbH (Thallner Privatstiftung)
• Inventors: Wimplinger, Markus
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Sinha, Tarun
• Application Number:
  US15/053,237
• Publication Number:
  US 20160172254A1
• Time in Patent Office: 852 Days
• Field of Search: 73632
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection
• CPC Class Codes: G01B 11/2441 using interferometry
• CPC Class Codes: G01B 17/02 for measuring thickness
• CPC Class Codes: G01B 17/025 for measuring thickness of coating
• CPC Class Codes: G01B 7/06 for measuring thickness measuring during the manufacture of coatings C23C14/54
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/9505 Wafer internal defects, e.g. microcracks
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/2697 Wafer or (micro)electronic parts
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/265 by moving the sensor relative to a stationary material
• CPC Class Codes: G01N 29/27 by moving the material relative to a stationary sensor
• CPC Class Codes: G01N 29/275 by moving both the sensor and the material
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67288 Monitoring of warpage, curvature, damage, defects or the like
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps

Abstract

A method for measuring and/or acquiring layer thicknesses and voids of one or more layers of a temporary bonded wafer stack on a plurality of measuring points is provided. A sequence of the method includes an arrangement of a measurement means for measuring and/or acquiring the layer thicknesses and voids of the layers of the wafer stack at the measuring points relative to a flat side of the wafer stack. The sequence further includes an emission of signals in the form of electromagnetic waves by a transmitter of the measurement means, and a receiving the signals which have been reflected by the wafer stack by a receiver of the measurement means. The sequence also includes an evaluation of the signals which have been received by the receiver by an evaluation unit.

Claims

1. A method for processing a temporarily bonded wafer stack, said method comprising the following steps:

temporarily bonding one or more layers to form the temporarily bonded wafer stack, the layers comprising a structure wafer, a connecting layer of temporary adhesive, and a carrier wafer, the temporarily bonding step comprising a step of temporarily bonding the structure wafer to the carrier wafer via the temporary adhesive connecting layer,

accommodating and fixing the temporarily bonded wafer stack to move the temporarily bonded wafer stack parallel to a reference plane (R),

measuring respective thicknesses of the layers and/or detecting voids of the layers on a plurality of measuring points distributed on the temporarily bonded wafer stack, the measuring and/or detecting step comprising the steps of;

first moving a transmitter relative to the temporarily bonded wafer stack,

emitting signals in the form of electromagnetic waves or ultrasonic waves from the transmitter into the temporarily bonded wafer stack,

second moving a receiver relative to the temporarily bonded wafer stack, the receiver being moved with the transmitter,

receiving, with the receiver, signals that were emitted by the transmitter and reflected by the temporarily bonded wafer stack, and

evaluating the received signals, the step of evaluating comprising;

distinguishing a group of the received signals by at least two transitions between the layers of the temporarily bonded wafer stack,

determining a distance of each of the received signals to one another and/or a reference plane (R),

detecting a movement of the temporarily bonded wafer stack and/or the transmitter and receiver parallel to the reference plane (R), and

detecting a position of each of the measuring points along the reference plane (R),

grinding at least a portion of the temporarily bonded wafer stack after the step of evaluating the received signals, and

detaching the temporarily bonded structure wafer from the carrier wafer.

2. The method according to claim 1, wherein the grinding occurs spatially separate from the measuring, as far as no deviation of quality criteria is determined.

3. The method according to claim 1, wherein the wafer stack is reworked in case of deviations of quality criteria.

4. The method according to claim 1, wherein the portion of the temporarily bonded wafer stack is the structure wafer.

5. The method according to claim 1, wherein the detaching comprises dissolving an edge zone of the temporary adhesive connecting layer by applying chemicals to the edge zone.

6. The method according to claim 1, wherein the measuring and/or detecting comprises measuring the thickness of the temporary adhesive connecting layer and/or detecting the voids in the temporary adhesive connecting layer.

7. The method according to claim 6, wherein the measured thickness of the temporary adhesive connecting layer is in a range between 37 μ

m and 42 μ

m.

8. A method for processing a temporarily bonded wafer stack, said method comprising the following steps:

temporarily bonding one or more layers to form the temporarily bonded wafer stack, the layers comprising a structure wafer, a connecting layer of temporary adhesive, and a carrier wafer, the temporarily bonding step comprising the step of temporarily bonding the structure wafer to the carrier wafer via the temporary adhesive layer;

arranging a measurement means relative to a flat side of the temporarily bonded wafer stack, the measurement means being configured to measure layer thicknesses and/or detect voids of the layers of the wafer stack at a plurality of measuring points distributed on the temporarily bonded wafer stack;

emitting electromagnetic or ultrasonic wave signals into the temporarily bonded wafer stack with a transmitter of the measurement means;

receiving reflected electromagnetic or ultrasonic wave signals from the temporarily bonded wafer stack with a receiver of the measurement meant, the reflected electromagnetic or ultrasonic wave signals being generated by reflection of the injected electromagnetic or ultrasonic wave signals by the temporarily bonded wafer stack; and

evaluating the received reflected electromagnetic or ultrasonic wave signals received by the receiver by an evaluation unit, the evaluating comprising;

distinguishing a group of the received reflected electromagnetic or ultrasonic wave signals by at least two transitions between the layers of the temporarily bonded wafer stack;

determining a distance of each of the received reflected electromagnetic or ultrasonic wave signals to one another and/or a reference plane (R);

detecting a movement of the temporarily bonded wafer stack and/or the measurement means parallel to the reference plane (R), and

detecting a position of each of the measuring points along the reference plane (R); and

detaching the temporarily bonded structure wafer from the carrier wafer.

9. The method according to claim 8, further comprising:

grinding at least a portion of the temporarily bonded wafer stack after the step of evaluating received reflected electromagnetic or ultrasonic wave signals.