Through-wafer holes

The substrate is 425 tm thick (see Note 5). The cantilevers were fabricated in separate cavities with a pitch of 250 tm between them. The cavities are the through-wafer holes drilled using a deep reactive ion etching (DRIE) technique. Each cantilever was 40 pm wide and 200 pm long, the thickness of each cantilever was 334nm (which was fixed by the thickness of the structural layer) (see Note 6). 

Figure 1.13 Patterned SOIMUMPS wafer. Through-wafer etches are performed from the front side of the wafer 10 or 25 pm deep to form device layer holes, and from the back side 400 pm deep to form through-wafer holes.

The concentrations of tracers in solutions were determined periodically. The polyethylene containers were constructed in such a way that, when inverted, 50 ml of solution passed from the wafer compartment into a second compartment. The second compartment of the container was inserted through a hole in a lead shield which housed a... 

Plasma Etching, Fig. 6 Cross-sectional SEM micrographs of (a) high aspect ratio microstructure of holes with the same nominal diameter of 1.5 pm and nearly the same etching depth of 69.5 pm, (b) through-wafer etching... 

Figure 17.4 Process flow used to fabricate the prototype ultrasonic transducers (a) a silicon (Si) wafer is micromachined to create an array of holes with diameters between 0.75 and 2.00 mm, after which the wafer is then thermally oxidized to grow a 1.5 pm thick S1O2 layer (b) the wafer is then diced into 1 cm wide square die (c) the die is laid flat onto a piece of free-standing F DF film in a jig (the die is now viewed in cross-section through the hole) (d) the die and PVDF film are clamped into the jig against an O-ring forming an air-tight seal, and air pressure is applied to the face of the PVDF film to deflect it into the desired spherical shape (e) finally, conductive epoxy is injected into the hole and a 30 gage wire is potted into the epoxy the air pressure is maintained until the epoxy cures, then the transducer chip is removed from the jig.

Figure 8.10 Through-wafer etch holes to enable back-side release. The backside etch holes eliminate the need for etch holes in the Poly2 mirror membrane. (Reprinted with permission from IEEE Journal of Selected Topics in Quantum Electronics, Microelectromechanical deformable mirrors, 1967 IEEE.)...

Fig. 3, Illustration of a contaminated insert due to the slurry dry-out through the wafer notch hole when not cleaned properly after polishing. Each mark was formed after each wafer was polished. These marks can accumulate to cause polish nonuniformity.

Microfabrication is effected by etching a wafer from both sides which contains through-holes for the fluid connectors [42], Two transparent cover plates close the open structures and also have through-holes. A glass capillary was attached to the three-plate chip. The holes in the cover plate were made by sandblasting. 

Microstructuring was effected by dry reactive ion etching (DRIE) [109,132]. Two microstructured wafers were sandwiched between two powder-blasted wafers with through-holes and feed-rings. 

The combustor was composed of three fusion-bonded silicon wafers. Hydrogen was added to the air flow by 76 injector holes of 30 pm diameter. The mixture then entered the annular-shaped combustion chamber through 24 combustor inlet ports of340 pm diameter and left the device through a circular exhaust. The dimensions of the combustion chamber were 5 and 10 mm diameter at a height of 1 mm, which corresponds to a volume of 66 mm3. The fabrication of the device was performed by dry isotropic and anisotropic etching (Figure 2.42). 

After etching, access holes can be created on the Si substrate by wet etch-through [1,89,90,281,306] or by drilling [442,495]. A two-mask process was also used to create channel access holes on the Si wafers [90],... 

In a second embodiment, a masking layer having windows 46 is formed on a thinned wafer of p-type HgCdTe. Holes 48 are etched through the wafer in the regions inside the windows by ion etching. N-type zones 49 are developed under the windows and along the walls of the... 

A (100) silicon wafer 10 is anisotropically etched to form hollows 11 having sloped sides 15. A plurality of via holes are etched or laser drilled through the floor 17 of each hollow. Next, the wafer is oxidized to coat its surfaces with a first insulator of SiC>2. A refractory conductor is deposited within the vias to form conductive conduits. A perspective view of a single hollow is shown below. 

To produce through-holes and cavities in a wafer, special forms of lithography are employed. If it is assumed that a roughly constant amount of material requires to be removed from all over the wafer, the creation in one and the same process of both cavities and holes is not feasible. The only chance of achieving this is to perform masking and lithography from both sides and then etch both sides simultaneously. 

The captive bubble method was applied to quantify the wettability of the resist in contact with water, with surfactant solutions of different concentration and with water after contact with the surfactant solution. The wafer piece is mounted with the photoresist layer down in a cuvette filled with the solution of interest. Through a small hole in the wafer an air bubble is placed under the photoresist surface. The shape of the drop is analyzed while its volume is slowly increased and decreased and the contact angle of the bubble is computed. It has to be converted into the water contact angle by subtracting its value from 180°. 

Backside pressure Fluid pressure will be loaded on the wafer from the back side of the wafer through holes that were set on the back side of the carrier. The pressure on the wafer will be changed by selecting holes. In this way, the center portion of pressure (rate) will be controlled. 

In most ECMP applications a perforated polishing pad with holes through it is used. Thus, electrical contact between the Cu surface that is contacted to the anode and the cathode located under the polishing pad is achieved via the electrolyte [29]. In the applied materials ECMP reflexion platform, the wafer is contacted to the anode located at the center of the pad as shown in Fig. 11.14. 

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