Semiconductor Memory Oxide Conditioning Before Cleaning
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Solution Overview
Problem
In semiconductor memory manufacturing, existing processes lead to non-uniform oxide formation and damage during cleaning, due to natural oxidation and inefficient wet etching methods, resulting in performance issues and potential short circuits.
Innovation Solution
A method involving a thermal oxidation process using oxygen plasma followed by a cleaning process with controlled pressure and radio frequency power to generate uniform oxides, which are then removed to prevent further oxidation and ensure stable processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If natural oxidation is allowed to occur during waiting time, then oxides form on the semiconductor surface, but the oxide formation is non-uniform and causes performance issues
Solution Approach 1:
The patent applies parameter changes by controlling temperature, pressure, and gas composition during the thermal oxidation process. Specifically, it uses a temperature range of 60°C to 120°C, pressure of 900-1500 Torr, and specific gas flow rates (O2: 13000 sccm, N2H4: 130 sccm) to achieve uniform oxide formation, directly resolving the non-uniform oxide issue caused by natural oxidation.
Solution Approach 2:
The patent employs strong oxidants by using oxygen plasma and thermal oxidation with ozone (O3) instead of relying on slow natural oxidation. This accelerated oxidation process, conducted under controlled conditions with RF power of 3500-4400 W, produces uniform oxides efficiently while preventing the performance degradation associated with non-uniform natural oxidation.
2Ease of manufacture
If wet etching is used to remove oxides, then oxides can be cleaned from the surface, but the cleaning process damages the semiconductor material
Solution Approach 1:
The patent replaces the mechanical/chemical wet etching process with a controlled thermal oxidation and plasma cleaning approach. By using thermal oxidation to create uniform, compact oxides followed by controlled removal processes, it eliminates the damaging effects of wet etching while maintaining effective oxide removal capability.
Solution Approach 2:
The patent applies preliminary action by performing thermal oxidation to create a uniform, compact oxide layer before the cleaning step. This pre-formed uniform oxide layer can be removed cleanly without damaging the underlying semiconductor material, whereas attempting to remove non-uniform naturally-formed oxides causes damage.
3Productivity
If thermal oxidation process parameters are increased to improve process rate, then oxide formation speed increases, but the process may affect semiconductor performance
Solution Approach 1:
The patent optimizes parameter changes by identifying specific ranges that balance process rate and performance: temperature of 60°C to 120°C, pressure of 900-1500 Torr, RF power of 3500-4400 W, and specific gas flow rates. These parameters achieve high oxidation rates while maintaining semiconductor performance, resolving the contradiction between productivity and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach generates compact, uniform oxides that protect the semiconductor surface and allow for effective oxide removal without damaging the material, improving the uniformity and performance of semiconductor memory.
Implementation Method 1
The thermal oxidation process is performed by using oxygen plasma
Implementation Method 2
performing a thermal oxidation process on the portion to be processed
Implementation Method 3
a first radio frequency power range for generating the oxygen plasma is from 3500 W to 4400 W
Implementation Method 4
heating the portion to be processed, so that the temperature of the portion to be processed increases to a first temperature
Implementation Method 5
performing a cleaning process, the cleaning process being used to remove oxides from the surface of the portion to be processed
Data Source
AI summary
A method for manufacturing a semiconductor memory includes: providing a portion to be processed, and performing a preset process step on the portion to be processed at least after a minimum waiting time; before performing the preset process step, performing a thermal oxidation process on the portion to be processed; and before performing the preset process step, performing a cleaning process, the cleaning process being used to remove oxides from the surface of the portion to be processed, the oxides being wholly or partly generated by the thermal oxidation process.