A Novel Etch Mask Process for the Etching of (011) Oriented Facet V‐Grooves in InP (100) Wafers

Huo, Da; Wynn, J. D.; Napholtz, S. G.; Lenzo, F. R.; Wilt, D. P.

doi:10.1149/1.2100300

Cited by 7 publications

(18 citation statements)

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“…The first two factors were studied in great detail in our previous papers (1,2). The mechanism of the third factor has not been clarified yet, but penetration of small ions like the fluoride anion in the etching solution could be a triggering reaction.…”

Section: Resultsmentioning

confidence: 99%

“…The principal requirements of photoresist masks in channelled substrate v-groove etching are: good pattern transfer, good etch resistance, and good control of photoresi~t undercutting. The first two factors were studied in great detail in our previous papers (1,2). The mechanism of the third factor has not been clarified yet, but penetration of small ions like the fluoride anion in the etching solution could be a triggering reaction.…”

Section: Resultsmentioning

confidence: 99%

“…A photoresist etch mask process has been developed for the etching of v-grooves in InP (001) for channelled substrate laser growth (1). The success of this technique depends largely on how to control the photoresist undercutting.…”

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confidence: 99%

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Preferential Etching of InP Through Photoresist Masks

Huo

Wynn

Napholtz

et al. 1988

J. Electrochem. Soc.

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Photoresist etch mask undercutting problems have been studied for the etching of v-grooves in InP (100) substrates for channelled substrate laser growth. The relationship between the photoresist mask undercutting and the impurity contents (HF, HBr, and H202) in the etchant were studied. The fluoride anion in the etchant causes the separation of the photoresist from the oxidized InP surface and results in excessive undercutting.A photoresist etch mask process has been developed for the etching of v-grooves in InP (001) for channelled substrate laser growth (1). The success of this technique depends largely on how to control the photoresist undercutting. The amount of photoresist undercutting caused by varying the dehydration bake temperature, the postbake temperature, and the photoresist film thickness has been studied (2). The undercutting phenomena is generally attributed to gradual lifting of a coated photoresist, thereby exposing a fresh area of the InP surface to the etchants. The separation of the photoresist from the InP substrate is due to the reaction between the surface native oxide on InP substrate and the etchant (2). To our knowledge there are no reported papers about the effect of the InP surface native oxide etching by different anions in the HCl:H3PO4 etchant. The purpose of this paper is to clarify that penetration of small ions like the fluoride anion in the etchants is a triggering reaction of the separation of the photoresist coating from the oxidized InP surface. ExperimentalAs received InP (001) oriented CSBH base structures grown by MOCVD are cleaned by conventional chloroform-acetone-methanol (CAM) solvents, rinsed in distilled water, blown dry with high purity nitrogen, etched in HF to remove native oxide, and blown dry with high purity nitrogen. In order to study InP (001) substrates with and without an intentionally grown native oxide, wafers were cleaved in half, and one-half of the wafers were heattreated at 200~ in air for 25 rain prior to the photoresist being applied. A positive photoresist (Microposit 1400-23) (3) is then spun onto the sample at 6 K rpm and softbaked at 90~ in air for 25 rain. The PR etch mask is direct contact patterned with a Karl Sfiess aligner and 1.0 ~m mask opening to open up 1.0-1.7 ~m wide windows, aligned parallel to the <011> crystal directions. The exposed wafer is developed, then etched in 5:l:n (n = 0.1 and 1); HCl:H3PO4:M (M = HF, HBr, and H202) mixed solutions at room temperature. After etching, the sample is cleaved along the {110} planes, i.e., perpendicular to the etched channel directions. Etching profiles are examined by using an Amray scanning electron microscope (SEM) with a sputtered Au coating on the photoresist. Results and DiscussionThe principal requirements of photoresist masks in channelled substrate v-groove etching are: good pattern transfer, good etch resistance, and good control of photoresi~t undercutting. The first two factors were studied in great detail in our previous papers (1, 2). The mechanism of the third factor ha...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Preferential Etching of InP Through Photoresist Masks

Huo

Wynn

Napholtz

et al. 1988

J. Electrochem. Soc.

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“…The mask designers need to know how the etching proceeds as the function of specific mask topology and its geometrical aspects. In this respect, the etching behaviour has mostly been documented for [011]-and [0 11]-oriented linear patterns on (100) wafers [18][19][20][21][22][23]. A few articles have dealt with differently oriented patterns or wafers [17,[24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Wet-etch bulk micromachining of (100) InP substrates

Eliáš

Kostič

Šoltýs

et al. 2004

J. Micromech. Microeng.

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The study focused on object formation in (100) InP by etching in 3HCl:1H3PO4 through convex and concave square mask patterns of varied orientation and size. Their upper right-hand-side corners were aligned to , and to 15°, 30° and 45° off to . Some -oriented convex squares had - and -oriented corners compensated with rectangular extensions. The concave patterns led to objects with ordinary slow-etching or etch-stop facets along sides in line within and with ordinary and re-entrant facets along sides in line within . The convex patterns (, 15° and 30°) led to objects initially confined by fast-etching facets at corners and slow-etching or etch-stop facets at sides (ordinary between and , and re-entrant between and ). The side facets were eliminated by the progress of the corner ones. They (-oriented patterns) proceeded at rates almost independent of size before the eradication of the side facets, after which they proceeded faster. The -oriented convex patterns led to objects confined only by fast-etching facets. The objects developed at rates that considerably depended on pattern size and etching time. Objects under small patterns developed faster compared to those under large ones. The -oriented corner-compensated patterns led to pyramidal objects confined by facets related to (110), , (101) and .

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“…Optical and scanning electron microscopes are usually used to inspect the etched profiles (7,8). Occasionally, defective profiles, such as vertical sidewalls and extraundercutting, were observed.…”

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Effects of Mask Imperfections on InP Etching Profiles

Huo¹,

Yan²,

Wynn³

et al. 1990

J. Electrochem. Soc.

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We have demonstrated that the quality of etch masks has a significant effect on the InP etching profiles. In particular, we have shown that mask imperfections can cause defective etching profiles, such as vertical sidewalls and extra mask undercutting in InP. We also discovered that the geometry of these defective profiles is determined by the orientation of the substrate relative to the direction of the mask imperfections. Along a < 110> line mask defect, the downward etching_process changes the < 110> v-grooves to vertical sidewalls without extra undercutting. For v-grooves aligned along the < 110> direction, defects on the mask give a significant extra undercutting without changing the etching profile.

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A Novel Etch Mask Process for the Etching of (011) Oriented Facet V‐Grooves in InP (100) Wafers

Cited by 7 publications

References 1 publication

Preferential Etching of InP Through Photoresist Masks

Preferential Etching of InP Through Photoresist Masks

Wet-etch bulk micromachining of (100) InP substrates

Effects of Mask Imperfections on InP Etching Profiles

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