Phase Change Memory Data Retention via Non-Volatile Storage
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Solution Overview
Problem
Phase change memory in semiconductor devices is prone to data loss due to low thermal retention resistance, which affects the yield and performance of semiconductor devices during packaging, as the information stored in phase change memory is lost when the chip is heated during assembly.
Innovation Solution
A semiconductor device is designed with both phase change memory and non-phase change memory types on the same substrate, where the non-phase change memory, such as an EPROM or EEPROM, is used for storing information before packaging, and the phase change memory is used after packaging to prevent data loss during thermal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If phase change memory is used for data storage, then small-size and large-capacity memory can be implemented, but thermal retention resistance is low causing data loss during packaging
Solution Approach 1:
The memory system is segmented into two distinct types: phase change memory for high-capacity storage and non-phase change memory (fuse/antifuse) for reliable data retention during thermal processes. Each type performs its specialized function without interfering with the other's weaknesses.
Solution Approach 2:
Non-phase change memory acts as an intermediary to store critical inspection data before packaging, protecting this information from thermal damage. The phase change memory then provides the high-capacity storage needed, while the intermediary ensures data integrity survives the packaging process.
2Productivity
If wafer inspection results are stored in phase change memory, then inspection efficiency is improved, but data is lost during semiconductor package assembly heating
Solution Approach 1:
Wafer inspection results are stored in non-phase change memory before the packaging process begins. This preliminary storage action ensures that critical inspection data is preserved in a thermally stable medium before any heating occurs during assembly.
Solution Approach 2:
The patent uses disposable fuse/antifuse elements that are programmed with inspection data before packaging. These elements serve their purpose of data storage during the critical pre-packaging phase and are replaced or rendered obsolete after packaging, where permanent thermal damage resistance is no longer needed.
3Adaptability or versatility
If phase change memory is used as fuse element, then fuse functionality is achieved, but information is lost due to low thermal retention during packaging
Solution Approach 1:
Different regions of the semiconductor device use different memory types with locally optimized properties: fuse/antifuse elements provide thermal stability for critical data, while phase change memory provides high capacity for bulk storage. Each location uses the memory type best suited for its specific function.
Solution Approach 2:
The semiconductor device incorporates multiple memory types that can serve different functions: non-phase change memory serves as a thermal-resistant fuse element for critical data, while phase change memory provides high-capacity storage. This multi-functionality allows the system to leverage the strengths of each memory type.
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 improves the manufacturing yield and performance of semiconductor devices by maintaining stored data through the packaging process, as the non-phase change memory retains information during high-temperature thermal processes, while allowing the phase change memory to be used post-packaging without data loss.
Implementation Method 1
the non-phase change memory retains information during high-temperature thermal processes
Implementation Method 2
a phase change memory which is constructed to cause a phase change between an amorphous state and a crystalline state in the phase change film (chalcogenide layer) of each memory cell and thereby change the resistivity of the phase change film
Data Source
AI summary
A semiconductor device having improved performance and improvement manufacturing yield is provided. After a semiconductor integrated circuit including a phase change memory and a nonvolatile memory other than a phase change memory is formed in a semiconductor substrate, an inspection step such as a probe inspection is performed. In accordance with the result of the inspection, data is stored in the nonvolatile memory other than a phase change memory. At this stage, the data is not stored in the phase change memory. Then, the semiconductor substrate is cut by dicing or the like into separate pieces corresponding to individual semiconductor chips. Each of the separate pieces of semiconductor chips is packaged.