Variety of specialized capabilities enabling the production of high precision custom products.
Currently, our in-house crystal growth is done using the Czochralski method. We start with ultra-high purity source materials which are mixed and melted in a controlled atmosphere. Low dislocation density material is core drilled to provide high quality seed material. Through years of development, our growth department is able to provide material that is highly uniform and nearly defect free allowing Hoffman Materials to offer some of the highest performing materials in the world. Our research and development team is constantly working on the next generation materials which will supersede the current material properties/capabilities commercially available today.
Contrary to an amorphous material, a single crystal material exhibits unique properties relative to the inherent crystallographic planes. Therefore, it is critical that the desired orientation of the crystal is identified before processing the material. Through the use of double diffraction X-ray analysis of the crystalline material, we are able to provide parts cut to within 15 arc seconds of accuracy.
Due to the hardness and brittleness of many single crystal materials, special techniques must be used to cut them. Depending on the application and material, we use diamond and slurry wire saws, along with a variety of dicing saws, to cut and slice ceramics and single crystalline materials. Currently, we can process material up to 150 mm in diameter.
Our precision grinding machines are used to shape crystalline materials into various geometries, with unique features, shapes and sizes. To reduce the thickness of a crystal, we use double-sided lapping machines which are capable of producing very thin pieces while maintaining flat and parallel surfaces. These machines can accommodate material up to 200 mm in diameter.
Hoffman Materials uses commercially available and specialized chemical etchants for the elimination of chips, sub-surface damage, and to relieve residual stress in the materials.
Annealing of crystalline or amorphous materials has been used for decades to treat and condition the materials. Depending on the atmosphere and temperature, heating of the material can cause internal bulk diffusion, surface diffusion or even thin film growth at the surface. Our furnaces are able to heat up to 1200°C with a range of controlled atmospheres and pressures. We have high precision gas flow controls integrated into our annealing systems for maintaining partial pressures of various gases.
Custom shapes and geometries are processed with high accuracy from raw crystal boules or wafers through the use of CNC milling and dicing machines. These machines use diamond tooling and have integrated precision measurement capabilities making it possible to repeatably and accurately cut straight edges, holes, bevels, notches, and chamfers. Currently, we have the capability of holding dimensional tolerances to within ±25 µm.
A materials’ hardness and surface chemical reactivity play a key role in how it will polish. Our proprietary polishing techniques exceed industry standards and provide flat and smooth finished surfaces. We entered the crystal polishing market by first developing processes for crystalline quartz and have since established techniques for many piezoelectric, pyroelectric, and optical crystals and ceramics. Through the use of mechanical and chemical-mechanical polishing (CMP), we have the ability to provide polished surfaces with average roughness below 0.5 nm.
Hoffman Materials has over 30 years of experience depositing high quality metallic films onto crystalline surfaces. These films often times act as electrical contacts for sensor elements which are packaged or integrated into systems which rely on a stable and durable interface to the crystal. Our plating is done through physical vapor deposition via resistive thermal evaporation or electron beam evaporation. All evaporation is done under ultra-high vacuum conditions which promotes a high bonding strength and purity of the metal layers. We pride ourselves in having the ability to maintain tight tolerances for the sheet resistance of our plated layers.
Unique part identification can be achieved by creating a mark on each piece of product. We use laser scribing, edge notching and corner chamfering as means of marking product. Each of our marking techniques are developed to prevent any changes in the material properties of the part. In particular, careful studies are done when laser scribing is used to minimize subsurface damage.
Having the appropriate metrology tools is a necessity for maintaining quality crystal synthesis and precision machining of raw materials. We are constantly upgrading our inspection equipment to provide the most accurate and reliable measurements possible for the surface finish, flatness, dimensions, sheet resistance, and bulk resistivity of our products.