IBM, AMD Speed Chips by Straining Silicon Wafers  SAN FRANCISCO (Reuters) - Researchers at IBM &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=IBM.N qtype=sym infotype=info qcat=news"&gt;IBM.N&lt;/A&gt; and  Advanced Micro Devices Inc. &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=AMD.N qtype=sym infotype=info qcat=news"&gt;AMD.N&lt;/A&gt; have improved a chip-making  technology called strained silicon, boosting  semiconductor  performance at a time when such gains are increasingly hard to  come by, the companies said on Sunday.