Back-Side Depopulated GAA Transistors for Drive Current Variation

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Solution Overview

Problem

Existing integrated circuit (IC) technologies face challenges in achieving varying drive currents for different applications within a single IC, particularly in gate-all-around (GAA) transistor structures, where efficiently depopulating channel regions to adjust drive currents is complex and invasive.

Innovation Solution

The solution involves fabricating double-sided integrated circuit transistor structures with depopulated bottom channel regions using a back-side channel depopulation method, which allows for the removal or deactivation of channel regions nearest to the back-side metallization level, thereby varying the number of active channel regions in GAA transistor structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If channel regions are depopulated from the front side of GAA transistor structures, then different drive currents can be achieved, but the processing becomes complex and invasive, reducing IC die yield

Engineering Contradiction:

Improvedrive current variationVSAvoidprocessing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional approach by performing channel depopulation from the back side of the substrate rather than the front side. This allows selective removal of channel regions through the substrate thickness to achieve different drive currents while avoiding complex front-side processing modifications, thereby maintaining higher IC die yield

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the number of channel regions is varied in GAA transistor structures, then different drive currents are achieved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvedrive current adjustmentVSAvoidmanufacturing simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent segments the channel regions into groups that can be selectively depopulated from the back side. By dividing the channel stack into accessible segments through substrate thinning and selective etching, different drive currents are achieved through simple back-side processing rather than complex front-side manufacturing modifications

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If front-side processing is complicated to depopulate channel regions, then IC die yield decreases, but drive current variation is still needed

Engineering Contradiction:

Improvedrive current controlVSAvoidIC die yield

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent transitions the depopulation process from the two-dimensional front-side plane to the third dimension by accessing channel regions through the substrate thickness. This vertical access approach allows selective channel removal without complicating front-side processing, thereby maintaining high IC die yield while achieving drive current variation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3926668B1Double-sided integrated circuit transistor structures with depopulated bottom channel regions

Publication Date: 2025.03.05 INTEL CORP

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Figure 3A~3B

AI summary

Integrated circuitry comprising interconnect metallization on both front and back sides of a gate-all-around (GAA) transistor structure lacking at least one active bottom channel region. Bottom channel regions may be depopulated from a GAA transistor structure following removal of a back side substrate that exposes an inactive portion of a semiconductor fin. During back-side processing, one or more bottom channel region may be removed or rendered inactive through dopant implantation. Back-side processing may then proceed with the interconnection of one or more terminal of the GAA transistor structures through one or more levels of back-side interconnect metallization.