In this lesson

You have loaded a lot and want to know what is wrong with it. tsmap has already looked, and this lesson shows you how to read what it found.

• Read What stands out, and show any row on the map
• Read the Findings list and the patterns behind it
• Use the Summary panel's tables and reports

Fields that move together

The lot's other fields are compared the same way. When two fields give the same groups, such as a tester and its probe card, tsmap names them together. It does not pick one for you; you choose which to follow.

Every row shows the affected dies

Click a row and the map shows which dies it is about. You can then see for yourself whether the problem sits at the edge, in one corner or all over the wafer. Click the row again to clear it.

Losses and signals

Each item is one of two kinds, and they call for different questions.

• A loss costs dies: a weak region, a low wafer, a failing test. Ask where the dies went.
• A signal moves values or compares groups, such as a split shift. A shift in a test will not show in yield, but it may still matter.

The dots and word beside an item are its impact: the share of the lot it affects. Read the impact first, to see how much an item matters.

Full report

Full report ▸ at the foot of the section opens the report, which begins with the same items. The Summary report button at the top of the panel opens the same report.

The sample lot mixes test programs, so its report has one section for each group. The first section holds only that group's wafers.

Bigger lots

Checks on test values, such as a region reading high, take longer, so they run on their own only for small loads. On a larger one the Findings list says so, and Analyse adds them for every wafer.

More in the user guide

Narrow the list

The Unusual and Notable buttons narrow the list. Click a finding to show it on the map.

What tsmap looks for

tsmap compares each part of the lot with the rest, and checks the failing dies for shapes it recognises.

• Regions: rings, quadrants, finer sectors, and test sites that yield or read differently
• Clusters of failing dies, and edge arcs at the rim
• Spatial patterns such as a donut, scratch or centre spot
• Reticle positions, once a reticle is set (lesson 11)

Show one at a time

Click a button to show only that test, bin or pattern on the map. It is the quickest way to see where one thing happens. This is Iddq, with the dies outside its limits marked ▽ and △.

A bin button

A bin's button shows only the dies in that bin. This is hard bin 3.

Wafer Yield rows

A badge on a row counts that wafer's findings. Click a row to open the wafer. A single wafer has no such list.

Which yield?

The panel's 66.2% mean per-wafer yield averages the 25 wafers' own yields, each wafer counting once. A pooled yield counts every die once, so big wafers weigh more. The label always says which. Check it before you compare the figure with one from somewhere else.

Hard Bin Breakdown

Hard Bin Breakdown shows where the lost dies went. Bars are a share of dies: pass bins first, then failing bins from the most dies to the fewest.

Soft bins

Soft switches the breakdown to soft bins, with their own colours. By default it follows the map's plot mode.

Ring Yield

Ring Yield shows yield by ring from the centre out, each row with its difference from the wafer's yield. Ring is the default because edge roll-off dominates real wafer maps.

Quadrant

Quadrant splits the wafer into NE, NW, SE and SW instead of rings.

Test Values

The Test Values table has one row per test: the mean, Ppk (lesson 06 explains it) and the share of dies within limits. Ppk uses the overall spread, wafer-to-wafer variation included.

Functional Tests

The Functional Tests table gives pass and fail counts and the pass rate for each functional test.

Summary report

Summary report 1 opens a printable report: the findings, bins, regions and the full per-test table. It is the report Full report ▸ opens. Save it as a PDF from the print dialog.

Data tables

Data tables 2 opens the same tables as the Data tab in Insights (lesson 06): statistics, every die, and one row per wafer, each with Copy and Export CSV. Insights does not need to be on.

Recap

• What stands out ranks losses and signals, largest first. Most rows show their affected dies on the map; an item about groups of wafers shows a chart instead.
• Findings lists what tsmap noticed by severity. Patterns carry the findings that support them.
• The tables, Summary report and Data tables carry the numbers behind all of it

When you open a new lot, read the headline and the top item first, click a row to see where it is, then use the Findings list for the rest.

More in the wafer map guide