Continuous Crystalline Semiconductor Structures via Epitaxy and Planarization
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Solution Overview
Problem
Conventional vapor phase epitaxy methods for forming crystalline materials at low temperatures result in the formation of amorphous regions, which negatively affect the electrical performance of semiconductor devices and are limited in thickness, making it difficult to achieve desired crystalline structures without damaging thermally sensitive components.
Innovation Solution
A method involving successive vapor phase epitaxy and chemical mechanical planarization (CMP) processes to form and remove amorphous portions, allowing for the achievement of crystalline materials with desired thicknesses greater than 500 Å, maintaining a low thermal budget and ensuring a continuous crystalline structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If vapor phase epitaxy is conducted at low temperature to avoid damaging thermally sensitive components, then the thermal budget is reduced and thermally sensitive components are protected, but amorphous regions are formed which negatively affect electrical performance
Solution Approach 1:
The deposition process is divided into multiple sequential stages: initial low-temperature deposition to form a nucleation layer, followed by higher temperature deposition to form crystalline material, and repeated cycles of deposition and annealing. This segmentation allows each stage to optimize for its specific purpose, avoiding the formation of amorphous regions while protecting thermally sensitive components.
Solution Approach 2:
A crystalline seed layer or template is formed on the substrate before the main deposition process. This preliminary crystalline structure provides a template that guides the growth of subsequent material layers, ensuring they grow in a crystalline manner rather than forming amorphous regions, even at lower temperatures.
2Temperature
If vapor phase epitaxy is conducted at low temperature, then thermally sensitive components are protected, but the crystalline material thickness is limited to about 500 Å
Solution Approach 1:
The deposition process uses periodic cycles of low-temperature deposition followed by annealing treatments. Each cycle deposits a thin layer and then anneals it to convert amorphous material to crystalline, allowing the process to be repeated to build up thickness beyond what a single low-temperature deposition could achieve.
Solution Approach 2:
The deposition temperature and annealing temperature parameters are dynamically adjusted during the process. Temperature profiles are optimized for each deposition cycle, with gradual increases to enable thicker crystalline layer formation while still protecting thermally sensitive components through controlled thermal exposure.
3Length of moving object
If vapor phase epitaxy is conducted at higher temperature to achieve thicker crystalline material, then crystalline material thickness increases, but thermally sensitive components are damaged
Solution Approach 1:
The total thickness requirement is divided into multiple thin layers deposited in sequential cycles. Each layer is deposited at a temperature that avoids damaging sensitive components, followed by annealing to ensure crystallinity. This segmentation of the deposition process allows accumulation of significant total thickness without exposing components to damaging high temperatures.
Solution Approach 2:
The process maintains continuous progress toward the thickness goal through repeated deposition-annealing cycles. Rather than requiring a single high-temperature step, the useful action of building crystalline material continues accumulatively through multiple controlled low-temperature cycles, each contributing to the final thickness while protecting sensitive components.
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 enables the fabrication of semiconductor structures with improved electrical properties and increased thickness of crystalline material, reducing leakage and enhancing performance, while avoiding damage to thermally sensitive components.
Implementation Method 1
Vapor phase epitaxy (VPE) has been used to form the crystalline materials on a substrate at a temperature of greater than or equal to about 600° C.
Implementation Method 2
A method involving successive vapor phase epitaxy and chemical mechanical planarization (CMP) processes to form and remove amorphous portions
Data Source
AI summary
A method of forming a semiconductor structure includes forming a first material over a base material by vapor phase epitaxy. The first material has a crystalline portion and an amorphous portion. The amorphous portion of the first material is removed by abrasive planarization. At least a second material is formed by vapor phase epitaxy over the crystalline portion of first material. The second material has a crystalline portion and an amorphous portion. The amorphous portion of the second material is removed by abrasive planarization. A semiconductor structure formed by such a method includes the substrate, the first material, the second material, and optionally, an oxide material between the first material and the second material. The substrate, the first material, and the second material define a continuous crystalline structure. Semiconductor structures, memory devices, and systems are also disclosed.