Semiconductor Pillar Contact Hole Depth Control
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Solution Overview
Problem
Current semiconductor devices with pillar-shaped structures face challenges in forming contact holes of varying depths, leading to increased manufacturing steps, decreased circuit integration, and difficulties in etching control, particularly when forming contact holes adjacent to silicon pillars in solid-state imaging devices and surrounding gate transistors.
Innovation Solution
A method involving the simultaneous formation of pillar-shaped semiconductors of equal height, doping of impurity regions, and the use of conductor layers to connect these semiconductors, allowing for the formation of contact holes of uniform depth and reducing the complexity of wiring connections, thereby enhancing circuit integration and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contact holes of varying depths are formed adjacent to silicon pillars, then connections to different regions can be established, but the number of manufacturing steps increases and etching control becomes difficult
Solution Approach 1:
The contact hole formation process is segmented into multiple stages: first forming shallow contact holes through the insulating layer to reach the semiconductor surface, then selectively deepening specific contact holes through the semiconductor pillar to reach lower regions. This segmentation allows different contact depths to be achieved through separate, controlled etching steps rather than attempting to form all contact holes in a single complex step.
Solution Approach 2:
The method performs preliminary etching to form contact holes through the insulating layer before performing selective deepening into the semiconductor. By establishing the basic contact hole structure first, the subsequent selective deepening becomes a simpler, more controllable process that only needs to modify specific holes rather than forming all holes from scratch with varying depths.
2Adaptability or versatility
If contact holes of varying depths are formed, then connections to different regions can be established, but the number of manufacturing steps increases
Solution Approach 1:
The method merges the formation of contact holes through the insulating layer with the selective deepening into the semiconductor by using the same etching process chemistry and equipment. The process combines a first etching step that creates holes through the insulator and a second step that selectively deepens specific holes, allowing both functions to be performed in a unified process flow rather than requiring entirely separate manufacturing sequences.
Solution Approach 2:
The etching process applies local quality control by using selective masking and etch stop layers to ensure that only specific contact holes are deepened into the semiconductor pillar while others remain at the insulator-semiconductor interface. This local differentiation allows the process to achieve varying depths in different locations without requiring completely separate etching operations for each contact hole.
3Adaptability or versatility
If etching is performed to form contact holes of varying depths, then connections to different regions can be established, but etching control becomes difficult
Solution Approach 1:
The semiconductor pillar surface acts as an intermediary etch stop layer between the insulating layer and the deeper semiconductor regions. The etching process uses this intermediate surface to naturally terminate the first etching step, providing a precise depth control point. Subsequent selective deepening then uses another etch stop (such as a different material layer or geometric feature) to control the final depth, creating a staged precision control system rather than relying on a single difficult-to-control etching step.
Solution Approach 2:
The method replaces mechanical depth control (physical measurement and adjustment of etching parameters) with chemical selectivity (using different etch rates for different materials). By selecting etching chemistries that react at different rates with the insulating layer, semiconductor pillar, and underlying structures, the process achieves precise depth control through material properties rather than mechanical parameter adjustment, significantly improving etching control precision.
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 simplifies the manufacturing process, reduces the number of steps required, and improves the integration and performance of semiconductor devices by enabling easier formation of contact holes and connections, leading to higher integration density and faster operation.
Implementation Method 1
doping, with a donor or acceptor impurity, at least one of a bottom region of the first pillar-shaped semiconductor and a region that contacts the bottom region at a lower position to form a semiconductor layer
Data Source
AI summary
A method for producing a semiconductor device includes the steps of forming first and second pillar-shaped semiconductors on a substrate at the same time so as to have the same height; forming a first semiconductor layer by doping a bottom region of the first pillar-shaped semiconductor with a donor or acceptor impurity to connect the first semiconductor layer to the second pillar-shaped semiconductor; forming a circuit element including an upper semiconductor region formed by doping an upper region of the first pillar-shaped semiconductor with a donor or acceptor impurity; forming a first conductor layer in the second pillar-shaped semiconductor; forming first and second contact holes that are respectively connected to the first and second pillar-shaped semiconductors; and forming a wiring metal layer that is connected to the upper semiconductor region and the first conductor layer through the first and second contact holes, respectively.