NCR-2041 · Post-grind wafer thickness

CASE PREPARED · AWAITING YOUR REVIEW

Lot

C-4471 · 25-wafer cassette

Process step

Backside grind

Characteristic

Post-grind thickness, subgroup mean (n=5)

Specification

Target 75 µm · LSL 72 · USL 78

Current lot mean

71.6 µm · OUT OF SPEC

Feeds

Stacking / bonding (thickness-sensitive)

Prepared case · trend

Lot mean, last six lots

Current lot below LSL

Current lot subgroup (n=5) 71.4 · 71.8 · 71.5 · 71.7 · 71.6 µm → mean 71.6 µm

REQUIREMENTS-ONLY RESULT

Current lot mean is below the 72 µm LSL. The lot is nonconforming and must remain on hold pending disposition.

MAPPED ENGINEERING JUDGMENT ADDS

The six-lot one-way drift, the current out-of-spec mean, and the thickness-sensitive downstream step point to a developing systematic condition — not an isolated unit. Contain the current lot, evaluate affected scope, confirm metrology, and inspect wheel wear and dressing history.

Prepared case · evidence

Current lot readings attached to the case
Five wafers × nine sites recorded
Current lot mean 71.6 µm, below the 72 µm LSL out of spec
TTV per wafer within the fictional 1.5 µm cap
Gauge calibration current, last verified 2026-06-14
Six-lot trend attached to the case
Material revision unchanged across the six lots
Wheel dressing log for the current run missing · requested

The missing dressing log does not block immediate containment. It blocks cause confirmation and any release or use-as-is path.

Prepared case · hard gates checked first

Nonconformance

Current lot mean is below LSL. Hold remains in effect until an authorized disposition is signed.

Customer contract

Use-as-is below the contractual lower limit requires written customer concession.

Downstream criticality

The lot feeds stacking and bonding, where minimum-thickness margin affects warpage and handling risk.

Authority

An authorized disposition role signs. MRB review is required when customer concession, broader affected scope, or unresolved risk enters.

Prepared case · similar prior calls

NCR-18932026-04-16 HELD · PROCESS ACTION REQUIRED

Same characteristic and the same sustained downward trend across consecutive lots. Wheel replacement stopped the drift.

Contributes: supports the wheel-wear mechanism as the leading candidate and supports containment ahead of cause confirmation.

NCR-17102026-02-09 REMEASURED · ORIGINAL SIGNAL INVALIDATED

A single low result without a sustained trend. Metrology confirmation found a measurement issue, and the original signal did not survive.

Contributes: the reason metrology confirmation stays in the recommended actions even when the trend looks convincing.

Three matching occurrences on this characteristic in the fictional record. The recurrence pattern warrants corrective-action review beyond the current lot.

NCR-1893 · 2026-04-16 | NCR-2007 · 2026-06-02 | NCR-2041 · 2026-06-20 (current)

PREPARED RECOMMENDATION · NOT A DECISION

HOLD contain · confirm · investigate

QUARANTINE CURRENT LOT
CONFIRM METROLOGY
REVIEW AFFECTED SCOPE
CHECK WHEEL WEAR AND DRESSING HISTORY
NOTIFY PROCESS ENGINEERING

Engineering basis

The current lot is below LSL after a sustained six-lot downward trend. The pattern is consistent with a developing systematic condition on a subtractive process. Immediate containment is supported. Final cause and affected scope remain subject to the missing dressing record and process review.

Boundary of this reasoning

This mapped pattern applies only when current metrology is valid and the downward trend is sustained. Reopen the reasoning if calibration fails, a wheel change occurred before the current lot, the material revision changed, or the process history contradicts the assumed mechanism.

Traces to: SPC trend rule + downstream failure mode GRIND-DISP-DRIFT-002 · v2.0 Mapped 2026-06-12 · re-verify on wheel change

The same mapped cases can also support development of less-experienced staff. See the transfer-mode demonstration.

Human review

The decision is yours.

Signatory of record in this illustration: J. Alvarez · Disposition Authority (fictional person, illustrative signature block only). This demonstration does not provide electronic-signature capability.

A review outcome has been recorded for this illustration, so the decision controls are locked. Use RESET DEMO below to return to the incoming flag and try another branch.

Revise the recommendation

Your rationale (required)

Revised action (optional)

A logged revision does not sign a disposition. In this illustration it is captured as a candidate change to the mapped pattern and would be reviewed with the pattern owner before any change to approved guidance.

Signed · hold approved

Hold recorded under the illustrative signatory J. Alvarez, Disposition Authority, at 2026-06-20 14:32. Lot C-4471 stays quarantined. Metrology confirmation, affected-scope review, wheel wear and dressing history check, and process engineering notification are recorded as required actions. The dressing log remains outstanding, so no release or use-as-is path is open.

Revision logged · case open

Your rationale is attached to NCR-2041 at 2026-06-20 14:38 and the case remains open under your authority. The prepared recommendation is marked as revised by the reviewer. No final disposition has been signed.

Routed to MRB

The prepared case has been routed to Material Review Board as a packet at 2026-06-20 14:41: trend, evidence, missing dressing log, gates, prior calls, mapped pattern, and open questions. MRB starts from the assembled case. No final disposition has been signed. Routing is not a disposition.

The record

The record below is generated from the current review state. Nothing is presented as signed until an authorized reviewer records a decision in this illustration.