Silicon substrate processing process and cleaning equipment
- Purpose of cleaning
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Pre-process cleaning: The main purpose is to remove contaminants generated in the process.
Post-process cleaning: Particle removal and metal removal are the main purposes. A typical cleaning method is a cleaning method called RCA cleaning.
- Purpose of RCA cleaning
- The ultimate goal in semiconductor manufacturing is to increase the yield to 100%. Particles and metal contamination have a major impact on yield. Particles can cut wires and cause shorts. Metal is a big contributor to noise. These factors appear prominently in yield.
Batch-type fully automatic wafer cleaning machine General view
- What is RCA cleaning?
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APM (SC-1) wash: A cleaning method that aims to remove particles.
ＮＨ４ＯＨ＋Ｈ２Ｏ２＋ＤＩＷHPM (SC-2) wash: Cleaning method for metal removal.
ＨＣＬ＋Ｈ２Ｏ２＋ＤＩＷDHF wash: A cleaning technique aimed at removing particles/metals.
ＨＦ＋ＤＩＷSPM wash: A cleaning method aimed at removing organic matter.
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Silicon substrate manufacturing process (deficit*Product lineup)
| process | content |
|---|---|
| single crystal | CZ method, MCZ method, FZ method |
| Crystal peripheral grinding Orientation measurement |
Peripheral grinding Orientation flat or notch processing so that the crystal orientation can be seen |
| Slice | Diamond blade: small diameter wafer Waitersaw:φ8、φ１２ Free abrasive grains, oil-based abrasive grains, water-based abrasive grains Fixed abrasive grains: Abrasive grains are fixed to the wire (saw marks are likely to appear) |
| Wash after slicing | Abrasive removal. Cleaning mainly with alkaline + interface In the case of φ12, implemented by demounter: Wafer cleaning & peeling |
| Beveling | Processing and polishing of wafer edge face. |
| Wrap | Double-sided lapping machine: Flatten the wafer. |
| Washing machine after wrapping | Removal of lapping abrasive grains: Washing mainly with alkali + interface |
| Etching | Eliminates processing strain that occurs during lapping. Acid etching (diffusion control): HF, HNO3.CH3COOH mixed acid solution Alkali etch (rate-determining reaction): KOH or NaOH concentrated solution |
| Gliding | In the case of φ12 wafers, a method of increasing the flatness by grinding instead of lapping. There are double-sided grinding and single-sided grinding. |
| Alkaline etching | Elimination of machining distortion caused by gliding |
| Cleaning before heat treatment | RCA cleaning is the basic method, but it varies depending on the user's line configuration. |
| Heat treatment | Gettering BSD: A strained layer is formed on the backside of the wafer by processing and has a gettering effect. Heat treatment: A strained layer is formed inside the wafer by heat treatment. There are various methods. |
| Cleaning after heat treatment | RCA cleaning is the basic method, but it varies depending on the user's line configuration. |
| Polishing (Grinding) | Mirror polishing: Eliminates unevenness on the wafer surface to the utmost limit. Double-sided polishing: φ12 is double-sided polishing Single-sided polishing: Mainly single-sided polishing up to φ8 |
| Cleaning after polishing | Cleaning after polishing: RCA cleaning is basic DHF, SC-1, SC-2, O3 water |
| Particle inspection | ＫＬＡ（Ｔｅｎｃｏｒ） ＳＰ３ |
| Final wash | RCA cleaning is basic DHF, SC-1, SC-2. O3 water |
In the φ12-inch silicon processing process, transportation between processes is almost automated.
FOSB containers are used for inter-process transfer, and the transfer is carried out in a state isolated from the environment.
There are two types of transportation between processes: the OHT method, which transfers products in the ceiling space, and the AGV method, which transfers products on the floor. It is an absolutely necessary system for managing particles and metals.