CO2-laser produced micro-bumps on glass substrates are not only of int
erest in tribological applications, e.g. zone texturing of substrates
as discussed in this paper, but for other applications such as micro-o
ptics fabrication. These bumps are positive protruding domes with net
volume gain. Mass conservation implies a local density decrease inside
the bump. We have studied this density variation using nanoindentatio
n to probe local hardness. Our findings indicate a clear and significa
nt decrease in bump hardness (up to 30%) relative to the background gl
ass - consistent with this local change in density. SIMS and electron
microprobe analysis indicate no chemical changes between the bump surf
ace and backrground regions. Regardless, the glass texture zone displa
ys excellent bump durability and contact start/stop performance. Addit
ionally, the role played by the chemical surface strengthening and its
effect on bump height has been investigated. For chemically engineere
d surface stresses ranging from 100 to 500 MPa, the bump height increa
ses with increasing surface stress at a rate of 0.064 nm/MPa Extrapola
tion of the plot to zero stress confirms a non-zero thermal expansion
contribution to the bump height - consistent with our theory for bump;
generation. Reflectivity measurements have shown that the optical cons
tants vary little with changing surface stress, implying that the lase
r coupling to the surface is essentially unaltered.