Plasma Etching Silicon Wafers

university wafer substrates

Plasma Etching Silicon Wafers

A postdoctoral researcher requested a quote for the following:

I need 6" (150mm) Si wafers with a notch not a flat. these will be used as carrier wafers in an ICP plasma etching tool. normal large wafers have to much of a flat and are not covered completly by the internal clamping ring. please let me know if you have any.

Reference #279274 for specs and pricing.

We have a large selection of silicon wafers for plasma etching. Many of our clients prefer our low cost mechanical grade silicon wafers for plasma etching. An item popular with researchers is item #1196. These are 100mm mechanical grade wafers. These wafers are less than $10.00 each! On client uses these mech grade wafers for carving a simple pattern on the wafers by plasma etching.

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Single Crystal Quartz Wafers used for Plasma Etch

A nanotechnology researcher requested a quote for the following.

Can I get a bit of information on the grade and quality your quartz, specifically the 100mm 550um DSP?  Our application is using a plamsa etch system to etch channels in glass and quartz.

These are ST cut quartz. See below for more specs. The quality is excellent.

* Flatness
Bow: 20um
Warp: 30um
* Roughness
Ra: 6 angstroms (on the polished side)

Reference #879-1517 for specs and pricing.

Fused Silica for Plasma Etch

A PhD candidate requested a quote on fused silica substrates:

We only want one side to be used (we are not growing on this, just using it in our plasma etching experiments on Al2O3).  It would be best to have just one side polished so it is easier for him to keep track of which side he is using.

Reference #126647 for specs and pricing.

Substrates Used for Pulsed Plasma Etching

A scientist requested a quote for the following:

Are you able to deposit MgF2 on PMMA (Plastic “Plexiglass”) substrates? Small (about 1”x1” and 2”x3”) and flat. One side. If so, how much for an initial test on 10 pieces?

If we are sure about adhesion we'd like to order? Regarding the adhesion issue; what plasma prepreparation capability do you have? Are you able to do any kind of RF or pulsed plasma etching, or preferable E-beam etching of the substrate before deposition?

UniversityWafer, Inc. Quoted:

We can perform a sputter etch prior to loading the parts into our evaporation system.  This would add an extra charge to the lot charge.

Reference #169028  for specs and pricing.

Coated Silicon Wafers Used in Plasma Etching

A chemical engineer requested a quote for the following:

I am looking to source silicon wafers coated with a) silicon dioxide,
b) silicon nitride and c) polysilicon. The coatings should be about
100 nm. I would need 5 wafers for each coating.

I am mostly interested in plasma etching into the coatings. So lets say N doped, <10 Ohm/cm, <100> orientation. Can you do polysilicon?

Reference #188124 for specs and pricing.

Dummy Carrier Silicon Wafers for Plasma Etching

An engineering technician asked for the following quote:

Do you sell 4” dummy wafers with 2 micron or so of standard Oxide?

We go through dummy wafers, used as carrier wafers in our etchers. The research students put pieces of wafers, and small samples on the “carrier wafer” and the loader arm can transfer in and out of the machine for plasma etching.

The dummy wafers need to be flat, preferably only one flat at bottom, but small side flats are ok…..and we usually have a oxide coating on the wafer.

These don’t have to be high quality Oxide as they are just dummy carrier wafers.

If you have them how much would a cassette of 25 cost? And could you supply them on a regular basis?

Reference #215104 for specs and pricing.

How are Carrier Wafers are Used in Plasma Etching?

Carrier wafers play a crucial role in the plasma etching process, especially when dealing with thin or fragile substrates. Here's an overview of how they are used:

  1. Support for Thin Substrates: Thin substrates, such as those used in advanced semiconductor devices, can be difficult to handle and process due to their fragility. Carrier wafers provide a stable base to support these thin substrates during the etching process.

  2. Bonding to the Carrier Wafer: The thin substrate is temporarily bonded to the carrier wafer. This bonding can be achieved through various methods, such as thermal bonding, adhesive bonding, or electrostatic bonding, depending on the substrate material and the requirements of the etching process.

  3. Processing in the Plasma Etcher: Once bonded to the carrier wafer, the thin substrate can be processed in the plasma etcher as if it were a standard thickness wafer. This allows for uniform etching and handling without damaging the thin substrate.

  4. Removal After Etching: After the plasma etching process is completed, the thin substrate is carefully separated from the carrier wafer. This separation must be done gently to avoid damaging the etched substrate.

  5. Advantages: The use of carrier wafers enables the etching of very thin substrates that would otherwise be too fragile to handle. It ensures that these substrates can be processed with the same high precision and uniformity as thicker wafers.

  6. Reusability: Carrier wafers are often designed to be reusable, which is cost-effective and efficient for large-scale manufacturing processes.

In summary, carrier wafers are essential tools in the plasma etching process, allowing for the effective handling and processing of thin and fragile substrates, which are increasingly common in advanced semiconductor manufacturing.

Plasma Etching Silicon Wafers

Plasma etching, you know, it's like this cool method we use in making tiny electronic components - really big P (Inductively Coupled Plasma) etching tool. This visualization represents the complex nature of such semiconductor manufacturing equipmentdeal in the world of semiconductors. This process involves using plasma – a state of matter similar to gas but with some of its particles ionized (meaning it has free electrons and positively charged ions) – to remove material from a surface, typically a wafer in semiconductor manufacturing.

Here's how it works:

  1. Creation of Plasma: The etching process starts by introducing a gas mixture into a chamber containing the substrate (like a silicon wafer). The gas is then energized into a plasma state using an electric field. Typically, stuff like fluorocarbons, chlorocarbons and oxygen are the go-to gases for this process.

  2. Reaction with the Surface: The reactive particles in the plasma interact with the material on the surface of the substrate. These reactions can either be physical, where the particles physically knock off atoms from the surface, or chemical, where the particles react with the material on the surface to form a volatile byproduct.

  3. Selective Etching: By using masks or other forms of patterning, plasma etching can remove material selectively from specific areas of the substrate. This key step of selectively stripping away stuff is how we're able to create those super detailed, tiny patterns that are vital in the microelectronics game.

  4. Advantages: Plasma etching offers several advantages over other etching methods. With plasma etching, you get the superpower to accurately peel off material on a mind-blowing nanometer scale. Moreover, this process lets us carve out a variety of materials and intricate designs - a critical aspect for today's semiconductor tech.

  5. Small businesses and startups must strategically allocate their limited marketing budgets, opting for imaginative yet realistic plans over expensive splashy campaigns. Applications: Plasma etching has many industrial uses beyond semiconductors, like etching glass or prepping surfaces so materials stick better, as well as making tiny fluid-controlling devices.

To put it simply, plasma etching is like the superhero of modern manufacturing – it's all about molding materials with crazy precision, right down to the microscopic level.

What substrates are commonly used for plasma etching

Plasma etching, you know, it's a process that gets a lot of play in the world of semiconductors and related areas because they often need to work with various materials. The choice of substrate often depends on the intended application and the desired properties of the final product. Some of the most commonly used substrates include:

  • Silicon: Silicon is the most widely used substrate in semiconductor manufacturing due to its excellent electronic properties. So, what's silicon all about? Well, it's the superstar when we're talking crafting integrated circuits and loads of other microelectronic devices.

  • Silicon Dioxide (SiO2): Often used as an insulating layer in semiconductor devices, silicon dioxide can be precisely etched using plasma to create insulating channels and patterns.

  • Silicon Nitride (Si3N4): This substrate is valued for its mechanical hardness and chemical resistance. Often, when silicon wafers need etching, this stuff's a go-to because of its resistance and toughness.

  • Gallium Arsenide (GaAs): This compound semiconductor is used in high-speed and high-frequency electronic devices. To get those precise patterns on GaAs substrates, which are key in the creation of high-speed and high-frequency electronics, we're using a process called plasma etching.

  • Sapphire: Sapphire substrates are used in LED manufacturing. In the process of shaping and creating unique designs on sapphire wafers, we turn to plasma etching.

  • Silicon Carbide (SiC): Silicon carbide (SiC) plays a significant role in plasma etching, both as a substrate material and as an etching agent. Here's how SiC is utilized in plasma etching. Etching of SiC Substrates: Due to its robustness and chemical resistance, etching SiC requires specialized plasma etching processes. Gases such as SF₆, Cl₂, or BCl₃ are often used in the plasma to etch SiC effectively. The plasma generates reactive species that can react with the SiC surface, removing material and creating the desired patterns.
  • A Quantum computer researcher requested the following quote:

    I would probably need 2-4 wafers.  They will be used as carrier wafers in a plasma etching system so a range of specs will work.  They need to be somewhat conducting and reasonably flat.  It would be good if all the wafers meet the same spec.

    Reference #165260 for specs and pricing.

  • Glass and Quartz: These substrates are used in various applications, including microfluidic devices and certain types of sensors. Plasma etching enables accurate patterning and etching on these materials.

  • Metals: Various metals are used as substrates or layers in microelectronics. You can use plasma etching not just to give metal layers unique patterns, but also for a deep clean of their surfaces.

  • "Chatting about polymers and plastics, you know they're not just for water bottles - we use them in microelectromechanical systems (MEMS) and loads of other tech applications." Microelectromechanical systems (MEMS) and various other fields often use certain kinds of polymers and plastics. Plasma etching can be used to modify the surface properties or to etch these materials.

Each of these substrates reacts differently to plasma etching, requiring specific gas mixtures and etching conditions to achieve the desired results. Plasma etching's got this cool ability to adjust and cater to loads of different materials and applications, you know?

Plasma etching of various metals and dielectrics has long been used in semiconductor construction. Structuring silicon by means of plasma etching is one of the most widely used techniques in silicon-based components, especially when high dimensional accuracy and verticality are required. [Sources: 6, 7]

The etching process can be carried out with a variety of metals such as aluminium, copper and gold. SF-6 CF-4 is used for anisotropic etching of silicon and carbon tetrachloride (CCl 4) is etched in silicon and aluminum. [Sources: 0, 5, 11]

The CF-4 gas used as reaction gas serves to form a plasma in order to etch the oxide layer. The RF energy ionizes the gas and forms a caustic plasma that reacts with the wafer to form a volatile product that is pumped out. Potassium hydroxide (KOH) is also used for etching silicon, while hydrofluoric acid (HF) has been used for etching SiO 2. CF, C and F ions react chemically and the type of plasma is produced, whereby the above-mentioned plasma etching is performed. [Sources: 1, 3, 11]

In accordance with this invention, silicon dioxide was found to be favoured by adding a formaldehyde component to the BF-3 plasma. It was found that the etching rate of silicon dioxide can be increased, although the effect on silicon was not significant. [Sources: 13]

If you consider a high selectivity towards silicon as criteria for choosing the mask, silicon oxide can be considered the best mask for the process if you use it in recipe A for silicon etching. [Sources: 6]

The etching beam, like silicon, would bend in the plane of the wafer. The more silicon wafers are etched, the more difficult the shape of the etched portions will be. [Sources: 8, 12]

Plasma etching is the preferred choice because it offers the possibility to transfer the plane geometry from the vertical wall to the silicon substrate. It also has an etching rate equal to or higher than wet etching and there is no need to create a straight etching profile. [Sources: 6, 8, 9]

The etching rate is strongly influenced by the chemical reactivity of the plasma types produced, which varies depending on the different gases used to produce them. In a plasma etching process, the material removed from the substrate by physical or chemical means can be used as the basis for the transfer of the plane geometry from the vertical wall to the horizontal wall, regardless of the mechanism used. [Sources: 9, 10]

For example, the buffering of hydrofluoric acid (BHF) is often excused by etching silicon dioxide on silicon substrates. When BF-3 plasma gas is used at low frequencies of electrical excitation, it has been shown to be a good candidate for etching silicon oxide (SiO2) in silicon wafers. In line with this invention, we have discovered a new method to demonstrate the transfer of plane geometry from the vertical wall to the horizontal wall of a silicon substrate, and to provide a quick and cost-effective solution to this problem. Since many etching silicones do not react with Si o2, a layer of Si O2 and two layers of silicone can form an excellent etching stop. We used 35 kHz excitation for a period of 30 seconds with a frequency of 1,000 Hz and 2,500 Hz. [Sources: 0, 12, 13]

A critical component, best made of silicon, is the plasma containment ring, which helps keep plasma concentrated on the wafer. [Sources: 2]

In the case of acid etching, an electric power supply can be used to control chemical reactions to supply the hole in the silicon surface. In addition, heating the environment adjacent to the plasma etching system saves the need to encounter a deposition reactor on the wafer during the etching process. [Sources: 12, 13]

This effect allows for very high anisotropy, as shown in the illustration, and is also suitable for the development of high-quality silicon wafers with high thermal conductivity and high surface area. [Sources: 0, 7]

Standard processes include resistance processes to organic strips with oxygen oxide nitrogen oxide and silicon carbide, as well as etching processes with SF-6 chemistry. These processes are available in a wide range of materials such as silicon wafers, polymers, ceramics, plastics and other substrates, as well as in other materials. [Sources: 4]

Conventional semiconductor chip manufacturing technologies require plasma etching, in which a vacuum chamber is filled with an excited and grounded electrode with a plasma containing ions and reaction gases. Known methods for forming recesses or openings in silicon wafers and other materials such as ceramics and polymers are wet etching processes with reactive solutions such as potassium hydroxide and reactive ion etching processes using plasma - the ion reaction gas. [Sources: 8, 13]

In order to avoid etching the underlying silicon sublayer in which the oxide is first clarified, it is desirable to initiate a selective plasma process that does not seriously affect or reduce the etching rate of SiO 2 or significantly reduce the silicon rate. In addition, many other gases can be used for etched photoresist layers such as etched nitride layers or sf etches and for etching different materials. Accordingly, it would be desirable to have a plasma gas composition that can be generated by using low frequencies of electrical excitation. [Sources: 1, 13]