Abstract
During the wire electrical discharge machining (WEDM) process, a large number of discharge pits and a recast layer are easily generated on the workpiece surface, resulting in high surface roughness. A discharge forming cutting-electrochemical machining method for fabricating single-crystal silicon is proposed in this study to solve this problem. On the same processing equipment, single-crystal silicon is first cut using the discharge forming cutting method. Second, electrochemical anodic reaction technology is used to dissolve the discharge pits and recast layer on the single-crystal silicon surface. The machining mechanism of this process, the surface elements of the processed single-crystal silicon and a comparison of the kerf width are analyzed through experiments. On this basis, the influence of the movement speed of the copper foil electrode during electrochemical anodic dissolution on the final surface roughness is qualitatively analyzed. The experimental results show that discharge forming cutting-electrochemical machining can effectively eliminate the electrical discharge pits and recast layer, which are caused by electric discharge cutting, on the surface of single-crystal silicon, thereby reducing the surface roughness of the workpiece.
Highlights
Silicon is widely used in integrated circuits (ICs) and ultralarge-scale integrated circuits (ULSIs) due to its special physical, chemical, and electrical properties [1]. e current manufacturing process of a single-crystalline silicon chip mainly includes cutting, grinding, and grinding
The copper foil electrode is again fed along the cutting route at a certain speed v. e discharge pits and recast layer left after the first stage are removed with electrochemical anodic dissolution, thereby reducing the surface waviness of the single-crystal silicon and improving its surface quality
When the second feeding speed of the copper foil electrode is reduced to 120 μm/s, the copper foil electrode has sufficient time to dissolve the discharge pits and recast layer. e discharge pits and recast layer on the surface of the single-crystal silicon are fully dissolved, and a small amount of the surface substrate of the single-crystal silicon is
Summary
Silicon is widely used in integrated circuits (ICs) and ultralarge-scale integrated circuits (ULSIs) due to its special physical, chemical, and electrical properties [1]. e current manufacturing process of a single-crystalline silicon chip mainly includes cutting (rough), grinding (fine), and grinding (polishing). E surface of the silicon wafer, which is a high-quality substrate for the chip, should have extremely high flatness and low surface roughness, and there should be no deterioration layer or lattice structure defects on the surface. The primary machining method for silicon chip cutting is wire saw cutting [2,3,4], which is based on indentation fracture theory for brittle materials [5]. Severe vibration affects the surface quality of the workpiece, causing surface defects and shedding of abrasive particles and affects the life of the wire saw. E lateral vibration of the wire saw is the main factor affecting the cutting and wafer surface quality [7]. The vibration may cause the chip to collapse or break
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