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Improved Etch Depth Uniformity by Compensating Ion Mill Etching

IP.com Disclosure Number: IPCOM000015695D
Original Publication Date: 2002-Jul-24
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Abstract

We are describing a two-step Ion Mill Process. This includes a Low Etch Rate process step, at prescribed etch angle and a High Etch Rate process step, which does the major etch. This will achieve a better uniformity for any Ion Mill process that demands a better etch depth uniformity profile than a normal, single etch step, process can deliver. The Ion Mill uniformity across the pallet (from the center to the outside pallet) usually has a high etch depth in the center and a low etch depth on the outside, such as the Control process in Figure (A), control (ctl- no ash) curve, whereas the two-step process, also depicted in Figure (A), shows improved etch depth profile. The one with longer compensation (ash 4min) gives better uniformity than the other (ash 2min). Figure (A) 12345678910 11 12 13 Position from the Center (cm)

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Improved Etch Depth Uniformity by Compensating Ion Mill Etching

We are describing a two-step Ion Mill Process. This includes a Low Etch Rate process step, at prescribed etch angle and a High Etch Rate process step, which does the major etch. This will achieve a better uniformity for any Ion Mill process that demands a better etch depth uniformity profile than a normal, single etch step, process can deliver. The Ion Mill uniformity across the pallet (from the center to the outside pallet) usually has a high etch depth in the center and a low etch depth on the outside, such as the Control process in Figure (A), control (ctl- no ash) curve, whereas the two-step process, also depicted in Figure (A), shows improved etch depth profile. The one with longer compensation (ash 4min) gives better uniformity than the other (ash 2min).

Figure (A)

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Position from the Center (cm)

Effect of Etch Compensation to the Uniformity

( ctl: por etch 240 secs, others: 200 secs por etch)

Figure (B)

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SiO2 Etch Depth (A) ctl-no ashash 2minash 4min

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Effect of Fixture Angle to the Etch Depth

( Etch compensation process: Oxygen Ash 1 min.)

The compensation etch step is the etch process that produces a higher etch depth on the outside than that on the inside by a controlled amount. The etch profiles on Figure (B) at etch angle range 30, 40, and 50 degrees, illustrate the condition whereas the outside portion of the pallet etch deeper by a certain amount than the inside portion. This amount can compensate the difference of the higher inside etch depth, of the high rate process, when combining the 1st compensation etch step and the 2...