Method of manufacturing a semiconductor device
Provided is a method of manufacturing a semiconductor device with which a trench shape having vertical, flat, and smooth side wall surfaces can be formed even at room temperature. A semiconductor substrate is placed on a sample stage which is kept at room temperature in a reaction container. A trench is formed in the semiconductor substrate by plasma etching that uses etching gas including oxygen and sulfur hexafluoride, while controlling the gas ratio of oxygen to sulfur hexafluoride so that the gas ratio is from 70% to 100%.
1. A method of manufacturing a semiconductor device in which a trench is formed on a semiconductor substrate, comprising:
forming a mask of an inorganic substance on a front surface of a semiconductor substrate so that the mask has an opening in a portion in which a trench is formed;
controlling a temperature of a sample stage in a reaction container of an etching machine so as to keep the sample stage at constant predetermined temperature of 5° C. to 30° C.;
putting the semiconductor substrate on the sample stage;
introducing an etching gas including oxygen and sulfur hexafluoride to an interior of the reaction container while maintaining a flow rate ratio of oxygen to sulfur hexafluoride between 70% and 100%; and
performing plasma etching of the semiconductor substrate with the etching gas to form the trench, while maintaining the constant predetermined temperature.
2. A method of manufacturing a semiconductor device in which a trench is formed in a semiconductor substrate, comprising:
forming a mask from an inorganic substance on a front surface of a semiconductor substrate so that the mask has an opening in a portion in which the trench is formed;
controlling a temperature of a sample stage in a reaction container of an etching machine so as to keep the sample stage at a constant predetermined temperature of 5° C. to 30° C.;
putting the semiconductor substrate on the sample stage;
introducing an etching gas including oxygen and sulfur hexafluoride to an interior of the reaction container while setting a flow rate ratio of oxygen to sulfur hexafluoride to a first ratio;
a first etching step of performing plasma etching on the semiconductor substrate with the etching gas at the first ratio, while maintaining the constant predetermined temperature;
after the first etching step, introducing the etching gas including oxygen and sulfur hexafluoride into the interior of the reaction container while setting the flow rate ratio of oxygen to sulfur hexafluoride to a second ratio that is lower than the first ratio,
wherein the first ratio and the second ratio have an oxygen to sulfur hexafluoride ratio between 70% and 100%; and
a second etching step of performing plasma etching on the semiconductor substrate with the etching gas at the second ratio, while maintaining the constant predetermined temperature.
3. A method of manufacturing a semiconductor device in which a trench is formed in a semiconductor substrate, comprising:
forming a mask from an inorganic substance on a front surface of a semiconductor substrate so that the mask has an opening in a portion in which the trench is formed;
controlling a temperature of a sample stage in a reaction container of an etching machine so as to keep the sample stage at a constant predetermined temperature of 5° C. to 30° C.;
putting the semiconductor substrate on the sample stage;
performing plasma etching by introducing an etching gas including oxygen and sulfur hexafluoride into an interior of the reaction container while setting a flow rate ratio of oxygen to sulfur hexafluoride to a first ratio; and
continuing the plasma etching by introducing the etching gas to the interior of the reaction container while changing the flow rate ratio of oxygen to sulfur hexafluoride to a second ratio that is lower than the first ratio in a single step instead of in stages, while maintaining the constant predetermined temperature
wherein the first ratio and the second ratio have an oxygen to sulfur hexafluoride ratio between 70% and 100%.
4. A method of manufacturing a semiconductor device according to claim 1 , wherein a sum of flow rates of the etching gas is constant.
5. A method of manufacturing a semiconductor device according to claim 1 , wherein the etching gas including oxygen and sulfur hexafluoride comprises only oxygen and sulfur hexafluoride.
6. A method of manufacturing a semiconductor device according to claim 2 , wherein the etching gas including oxygen and sulfur hexafluoride comprises only oxygen and sulfur hexafluoride.
7. A method of manufacturing a semiconductor device according to claim 3 , wherein the etching gas including oxygen and sulfur hexafluoride comprises only oxygen and sulfur hexafluoride.
8. A method of manufacturing a semiconductor device according to claim 4 , wherein the etching gas including oxygen and sulfur hexafluoride comprises only oxygen and sulfur hexafluoride.
9. A method of manufacturing a semiconductor device according to claim 2 , wherein a sum of flow rates of the etching gas at the first ratio and a sum of flow rates of the etching gas at the second ratio are the same.
10. A method of manufacturing a semiconductor device according to claim 3 , wherein a sum of flow rates of the etching gas at the first ratio and a sum of flow rates of the etching gas at the second ratio are the same.