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| delayer:wet [2015/01/13 04:19] – mcmaster | delayer:wet [2023/07/28 06:47] (current) – mcmaster | ||
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| * Notes | * Notes | ||
| * Adding HCl may reduce insoluble oxide bi-products | * Adding HCl may reduce insoluble oxide bi-products | ||
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| + | ==== Pitting ==== | ||
| + | |||
| + | A common issue seems to be pitting if left in too long. As BOE itself can't etch silicon, it must be an additive. Some evidence suggests this is caused by not cleaning upper (ie metal) layers away. Possibly due to atmospheric oxygen. This also causes issues for staining and similar processes. | ||
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| + | Recommendation: | ||
| + | |||
| + | Below example is on Generalplus GPLB52A24A | ||
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| + | {{mcmaster: | ||
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| + | Above: left 40 min etch, right 40 hour etch 130F forced air w/ BOE | ||
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| + | {{mcmaster: | ||
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| + | Above: die at angle, left side lower than right. Right side shows deep pits in focus even though its higher than surface visible at left | ||
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| + | {{mcmaster: | ||
| + | {{mcmaster: | ||
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| + | Above: deep staining shows doping much higher than substate now as evidenced by significant focus difference | ||
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| * "Very uniform attack, also very gentle to oxides and silicon." | * "Very uniform attack, also very gentle to oxides and silicon." | ||
| * If you are having problems completely removing it there may be a metal barrier, see "Beck barrier Ti/TiN solution" | * If you are having problems completely removing it there may be a metal barrier, see "Beck barrier Ti/TiN solution" | ||
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| + | |||
| + | ==== HCl-H2O2 ==== | ||
| + | |||
| + | Very aggressive. | ||
| + | |||
| + | Ingredients: | ||
| + | * 4 mL HCl | ||
| + | * 1 mL 35 H2O2 | ||
| + | * 1 mL H2O | ||
| + | |||
| + | [[http:// | ||
| ==== Nitric ==== | ==== Nitric ==== | ||
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| * 1 mL 40% HF | * 1 mL 40% HF | ||
| * 20-25 @ room temp | * 20-25 @ room temp | ||
| + | |||
| + | Alternate: | ||
| + | * 1 mL Whink | ||
| + | * 10 mL 70% HNO3 | ||
| Notes: | Notes: | ||
| - | * I haven' | + | * 2023-07-23: did a good job near top metal when the other solution wasn' |
| ====== References ====== | ====== References ====== | ||
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| * Wikipedia: Buffered oxide etch: http:// | * Wikipedia: Buffered oxide etch: http:// | ||
| * "DSP-1 emulation": | * "DSP-1 emulation": | ||
| + | * https:// | ||