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Etch Difficulty Index; A Measure of Difficulty of Etching of a Surface Film in Presence of Complex Tall Structure Patterns Used in Advance CMOS Technologies

IP.com Disclosure Number: IPCOM000016553D
Original Publication Date: 2003-Jun-27
Included in the Prior Art Database: 2003-Jun-27
Document File: 1 page(s) / 75K

Publishing Venue

IBM

Abstract

A concept of Etch Difficulty Index (EDI) has been defined as a relative means of estimating the difficulty in wet etch process, based only on geometric design parameters of a given part number. Calculation of this index uses the design parameters like chip length, chip width, C4 pitch, actual number of C4's on the chip, and the width of widest kerf. EDI number, independent of wafer size, is calculated as a dimensionless index. This index provides a quick method of comparing a new product with the existing ones to the designer in estimating the level of etch challenge that a new product can present.

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  Etch Difficulty Index; A Measure of Difficulty of Etching of a Surface Film in Presence of Complex Tall Structure Patterns Used in Advance CMOS Technologies

  EDI, as given by eqn (1), is a measure of difficulty to expect in a wet etch process due to design parameters in removing TiW from the array and kerf areas, with respect to a wafer with fully 1populated C4's of 250 micron pitch and kerf width same as pitch. EDI's for some of the representative products of the current C4 plating process are ummarized in Table (1) .

    EDI = (250/P) (K/P) (A/((L/P)-2)*((W/P)-2)) ......................................(1)
where K is kerf width; P is pitch, L and W are length and width of chip respectively in units of micron. A is actual number of c4's per chip. Table (1) EDI for Some of the Current C4 Plating Products

Part Pitch Kerf Number of Number of Chip Length Chip Width Total # of C4's Ecth

Name Minimum Max Width Actual C4's Chips Difficulty

P K

L W Index

Blizzard

DD2

250 2139.55 170 180 13455.54 8499.96 30600

0.9

Noreaster

250 277.34 162 360 8499.6 7849.8 58320

0.2

Gobi

225 2474 482 599 6796.35 5086.35 288718

10.1

Reference: (1) "Etch Difficulty Index for Advance CMOS Device Designs", TR 03/22-4166, Jan. 2003

Disclosed by International Business Machines Corporation

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