Plasma Etching Mask Layer Bowing Prevention
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Solution Overview
Problem
Current substrate processing methods for semiconductor devices face challenges in preventing bowing of hole cross-sections in amorphous carbon mask layers, leading to insufficient remaining layer quantity and incomplete etching of target oxide layers during the miniaturization of semiconductor devices.
Innovation Solution
A substrate processing method involving a plasma etching process with a pressure of 7 mTorr or less and a substrate temperature of 0°C or less, using a mixed gas of O2 and COS, and adjusting excitation powers and DC voltages to prevent bowing and ensure vertical hole shapes and sufficient mask layer retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high etching rate is achieved in ACL layer, then productivity is improved, but bowing occurs in hole cross-section causing manufacturing precision to deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing multiple etching conditions simultaneously: using a specific mixed gas composition (CF4, CHF3, and C4F8 in controlled ratios), maintaining pressure at 7 mTorr or less, controlling substrate temperature at 0°C or less, and applying specific excitation power ranges. These parameter adjustments work together to achieve high etching rates while preventing bowing in the hole cross-section, thus resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If minimum dimension of patterns in mask layer is reduced, then manufacturing precision is improved, but bowing occurs causing remaining mask layer quantity to become insufficient
Solution Approach 1:
The patent uses parameter changes to control the etching process such that even when minimum pattern dimensions are reduced for higher precision, the hole cross-section maintains a vertical shape without bowing. This is achieved through the specific gas mixture ratios, pressure control at 7 mTorr or less, and temperature control at 0°C or less, which together ensure sufficient remaining mask layer quantity while achieving the required pattern precision.
3Speed
If ACL layer is etched at conventional conditions, then etching speed is improved, but hole cross-section expands causing shape to deteriorate
Solution Approach 1:
The patent applies parameter changes by using a mixed gas of CF4, CHF3, and C4F8 in specific ratios, controlling pressure at 7 mTorr or less, and maintaining substrate temperature at 0°C or less. These parameter adjustments enable high etching speed while maintaining a vertical hole cross-section shape without expansion, thus resolving the contradiction between etching speed and shape quality.
4Manufacturing precision
If mask layer thickness is reduced for miniaturization, then manufacturing precision is improved, but mask layer becomes insufficient preventing complete etching of target layer
Solution Approach 1:
The patent uses parameter changes to optimize the etching process for thin mask layers. By controlling pressure at 7 mTorr or less, temperature at 0°C or less, and using specific gas mixture ratios, the process achieves high precision pattern transfer while ensuring complete etching of the target oxide layer through the reduced mask thickness, thus resolving the contradiction between manufacturing precision and etching completeness.
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 method effectively prevents bowing, maintains a sufficient mask layer quantity, and achieves excellent vertical working shapes in semiconductor devices by optimizing plasma etching conditions, including pressure, temperature, and gas composition.
Implementation Method 1
generating plasma of a processing gas in the processing space
Data Source
AI summary
Disclosed is a substrate processing method configured to prevent the occurrence of a bowing shape to form a hole of a vertical processing shape on a mask layer, and to secure a remaining layer quantity as the mask layer. The substrate processing method receives a wafer W in which a mask layer and an intermediate layer are stacked on a target layer to be processed in a chamber, generates plasma of processing gas in the chamber, performs an etching process on wafer W using the plasma, thereby forming a pattern shape on the target layer to be processed through the intermediate layer and the mask layer. The etching process etches the mask layer by applying excitation power of 500 W for generating plasma, maintaining processing pressure at 5 mTorr (9.31×10−1 Pa) or less, and maintain temperature of wafer W in the range of −10° C. to −20° C.