Design, microfabrication and characterization of planarized multilayer atom chips with enhanced heat dissipation

Abstract

This paper describes the design and fabrication of planarized multilayer atom chips for an ultrahigh-vacuum system in atomic physics experiments. A fabrication process is developed to define micrometer-scale wire patterns on a silicon substrate and wires are plated by copper electroplating. SU-8 is chosen as the isolation layer between the upper and bottom wires, and its thickness, surface flatness and surface roughness (Ra = 5 nm) are controlled by the chemical–mechanical planarization process. A reflectivity of nearly 90% is measured on the chip surface; thus, the former method of attaching a silver mirror is unnecessary (Du et al 2004 Phys. Rev. A 70 053606). A heat dissipation copper block is incorporated in our chip design to increase the sustainable current densities of upper wires of more than 3.8 × 105 A cm−2. Results show the improvement of 55.74%, compared with the nonheat dissipation design (2.44 × 105 A cm−2), and thus meeting the requirements for chip-based atom trapping experiments.

Fifteen years of cold matter on the atom chip: promise, realizations, and prospects

“…superconductors) and be strong enough for use as a facet of the vacuum chamber, in which case through-wafer etchings (vias) should also be vacuum compatible [ 195 ]. Substrates should also be able to easily accommodate multi-layer chip designs [ 171 , 196 , 197 ].…”

Atom-Chip Fountain Gravimeter

“…Atom chips with the required optical surfaces of interferometric qualities were reported in Refs. [62][63][64]. The proximity of atoms close to the chip also leads to a phase shift and hence a measurement bias due to its gravity [60].…”

The Design, Fabrication and Characterization of a Transparent Atom Chip

“…Some atom chips are designed to reflect laser beams on the chip surface. Chuang et al [15] reported a multilayer atom chip which is fabricated on a silicon substrate with electroplated copper wires on the top surface and a copper thin film is evaporated on the outside area of the electroplated copper wires to reflect the laser beams. In addition, a silver mirror is attached on the chip surface for the purpose of reflecting laser light [16] in order to achieve the laser cooling process.…”

“…In addition, a silver mirror is attached on the chip surface for the purpose of reflecting laser light [16] in order to achieve the laser cooling process. The disadvantages of this method are: (1) the incident angle of the laser light is short of one degree of freedom, (2) the glue used to attach the silver mirror is easily degraded after a period of time, and (3) the deposited copper thin film causes varying reflectivity on different areas of the atom chip due to the different height of the wire patterns [15]. An alternative way is to deposit a gold thin film directly on the chip surface for reflecting the laser beams.…”

“…The magnetic field types and gradients generated by applying current through the wires are different according to various wire shapes. The wire shapes used in this study are those referred to by Chuang et al [15], namely double layer atom chips, except for two laser light transmitting regions with a diameter of 3 mm that are inserted in-between the wire patterns as shown in Figure 1. The wire shapes on atom chips are mainly combinations of U and H-wire trap patterns.…”