Polishing agent
View Patent ↗The invention relates to the use of gluconates in the production of semiconductor wafers, preferably in the polishing of the semiconductor wafers during the production process, and to a polishing agent based on an abrasive substance and/or colloid and a mixture of disuccinates or methylglycine diacetic acid (MGDA) and gluconates.
1. A polishing agent which comprises
a) water,
b) an abrasive substance and/or colloid,
c) methylglycine diacetic acid or a disuccinate of the formula
wherein
R denotes —(NH—CH 2 —CH 2 —) n NH—,
X denotes hydrogen and/or an alkali metal,
n is an integer from 0 to 2 and
d) an alkali salt or alkaline earth salt of gluconic acid.
2. The polishing agent according to claim 1 , wherein the component b) comprises silica in a proportion of 0.05 to 50 wt. %, calculated as Si0 2 .
3. The polishing agent according to claim 1 , wherein the pH value is from 8 to 13.
4. The polishing agent according to claim 1 , wherein the sodium or potassium salts are used as alkali salts of gluconic acid.
5. The polishing agent according to claim 1 , wherein component (c) comprises iminodisuccinic acid (n=0) and/or ethylenediamine disuccinic acid (n=1) and/or diethylenetriamine disuccinic acid and/or one or more salts of these compounds or methylglycine diacetic acid.
6. The polishing agent according to claim 1 , wherein contains component (c) in a proportion of 0.005 to 5 wt. %.
7. The polishing agent according to claim 1 , wherein one or more basic salts and/or hydroxides of alkali metal ions and/or ammonium ions are contained in a proportion of 0.01 to 10 wt. % as additional component (e).
8. The polishing agent according to claim 1 , wherein the agent has a pH value of 9 to 12, and comprises components
(a) water in a proportion of 84 to 99.8 wt. %,
(b) silica in a proportion of 0.1 to 10 wt. %, calculated as Si0 2 ,
(c) sodium or potassium salt of iminodisuccinic acid and/or of ethylenediamine disuccinic acid in a proportion of 0.01 to 1 wt. %,
(d) sodium and/or potassium carbonate in a proportion of 0.05 to 5 wt. %, and
(e) potassium or sodium gluconate in a proportion of 0.01-0.5 wt. %.
9. A process for the polishing of a semiconductor wafer which comprises polishing a wafer which has a front surface and a back surface and an edge, with the polishing agent according to claim 1 .
10. The process according to claim 9 , wherein the semiconductor wafer consists substantially of silicon.
11. The process according to claim 10 , wherein the front surface of the silicon wafer is uncovered or is covered with native oxide and is polished with the introduction of the polishing agent.
12. The process according to claim 9 , wherein at least part of the front surface of the semiconductor wafer is covered with artificially applied layers and/or structures.
13. The process according to claim 12 , wherein copper is contained as an electrical conductor in the layers and/or structures.
14. The process according to claim 9 , wherein the front surface and the back surface of the silicon wafer are uncovered or covered with native oxide and are polished with the introduction of the polishing agent.
15. The process according to claim 9 , wherein the edge of the silicon wafer is polished with the introduction of the polishing agent.
16. The process according to claim 9 , wherein at least part of the polishing agent used is recycled.