Cristobalitized Heat Treatment Jig for Semiconductor Substrates
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Solution Overview
Problem
Conventional heat treatment jigs for semiconductor silicon substrates fail to adequately prevent the generation of slips, which are crystal defects caused by thermal and own-weight stresses during high-temperature processing, leading to issues like increased leak current and substrate flatness degradation.
Innovation Solution
A heat treatment jig with a cristobalitized oxide film is used, where the oxide film is formed by introducing a cristobalitization promoting agent, such as alkali metal or alkali earth metal, to create cracks that allow stress release, and a shielding plate is employed to prevent particle adhesion, ensuring effective slip prevention and maintaining substrate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a disc-structured heat treatment jig is used to support the whole backside of the silicon substrate, then deflection displacement is decreased, but a local temperature difference is easily generated causing slip generation
Solution Approach 1:
The heat treatment jig is segmented into a ring structure with multiple support points instead of a continuous disc structure. The ring tray has an inner peripheral end face that contacts the substrate at distributed points rather than across the entire backside surface, reducing local temperature differences while maintaining structural support.
Solution Approach 2:
The ring structure concentrates support functionality at the inner peripheral end face rather than distributing it uniformly across the entire substrate backside. This localized support approach reduces the contact area, minimizing local temperature differences and thermal stress generation while still providing adequate mechanical support.
2Object-affected harmful factors
If a ring tray is used to receive the outer peripheral portion of the silicon substrate backside, then thermal stress is reduced, but the central portion of the substrate is bent by own-weight causing contact with the inner peripheral end face and slip generation
Solution Approach 1:
The ring tray structure is designed with specific geometric parameters where the ratio between outer diameter and inner diameter falls within 0.4 to 0.7, and the thickness is optimized to provide adequate support to the central substrate portion without causing excessive bending. This segmented support approach distributes the weight-bearing function across multiple points.
Solution Approach 2:
The dimensions of the ring tray are optimized with specific parameter ranges: the outer diameter to inner diameter ratio is controlled between 0.4 and 0.7, and the thickness is set between 0.5 to 2.0 mm. These parameter changes balance the support of the central substrate portion while preventing excessive bending and own-weight stress.
3Object-affected harmful factors
If high-accuracy machining is performed to achieve flatness of not more than 50 μm in the silicon substrate receiving surface, then slip generation is suppressed, but production cost is increased and realistic production conditions cannot be achieved
Solution Approach 1:
The ring structure concentrates the support function at the inner peripheral end face, which means that the critical flatness requirement applies only to this localized contact region rather than the entire receiving surface. This allows for relaxed machining tolerances in non-critical areas, reducing manufacturing cost while still preventing slip generation at the contact points.
Solution Approach 2:
By segmenting the support function to specific regions (the inner peripheral end face contact points), the patent reduces the total area requiring high-precision machining. This segmentation allows standard machining tolerances to be applied to most surfaces while maintaining adequate flatness only where substrate contact occurs, making production economically viable.
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
The cristobalitized oxide film effectively prevents slip generation by allowing stress release and the shielding plate suppresses particle adhesion, enhancing substrate quality and production yield.
Implementation Method 1
a cristobalitized oxide film is formed in a region of the heat treatment jig which functions to support the semiconductor substrate while contacting the same
Implementation Method 2
when an uneven temperature distribution is generated in a surface of the semiconductor silicon substrate, a resultant thermal stress is generated in the semiconductor silicon substrate
Data Source
AI summary
A heat treatment jig for semiconductor silicon substrates is configured such that a cristobalitized oxide film is formed in a region where the cristobalitized oxide film is in contact with a silicon substrate backside. When said heat treatment jig is used, generation of a slip can be prevented during heat treatment. In the case where the heat treatment jig is used in combination with a shielding plate, particles are further prevented from adhering to the silicon substrate surface to maintain quality characteristics of the semiconductor silicon substrate at a higher level, and device production yield can largely be improved. The heat treatment jig can easily be manufactured by introducing a cristobalitization promoting agent to a surface or in the vicinity of a surface of the heat treatment jig, performing the heat treatment at temperatures in the range of 1000 to 1380° C., and repeating the introduction of the cristobalitization promoting agent and the heat treatment.