Frank Quattrone, who earned $120 million in 2000 as Credit Suisse First Boston’s top technology banker, was sentenced to 18 months in prison and fined $90,000 for urging employees to destroy documents during a probe of CSFB.

Quattrone’s lawyers had asked U.S. District Judge Richard Owen to sentence the former investment banker to 10 months in prison, the minimum under federal guidelines, with five months of home detention. Quattrone was convicted of impeding investigations into how his bank allocated shares of initial public offerings during the technology boom of the late 1990s.

Under U.S. sentencing guidelines, Quattrone faced 10 to 16 months in prison. Prosecutors said the range should be increased by five months, and Quattrone should serve from 15 to 21 months, because he lied in his testimony at trial. Mr. Owen granted the government’s request for a stiffer sentence, saying it was “crystal clear” Quattrone had been “untruthful.”

Quattrone, 48, is the highest-ranking securities executive to face prison since junk-bond pioneer Michael Milken was sentenced to 10 years behind bars in 1990. He served two.

“I humbly ask that you show mercy and compassion for me and my family,” Quattrone said before being sentenced in Manhattan federal court.

Quattrone has said he’ll challenge Owen’s trial rulings on appeal. He claims the judge gave jurors misleading instructions about the government’s burden of proof and denied him a fair trial by excluding evidence the defense wanted to offer.

At CSFB, Quattrone oversaw a Palo Alto, Calif.-based technology group that generated up to 15% of the bank’s revenue during the Internet boom. He took dozens of companies public, including Amazon.comInc. in 1997.

Quattrone may request assignment to a prison in California as Milken did after he pleaded guilty to securities fraud.

Before his trial, Quattrone sought unsuccessfully to have the case transferred to his home state because his wife is ill.

Quattrone was convicted of two counts of obstruction of justice and one count of witness tampering. His first trial ended with a hung jury in October.

The case turned on a single, December 2000 e-mail written by a colleague who urged CSFB employees to “clean up” their files and discard documents. Quattrone forwarded the message after learning that a federal grand jury was investigating how CSFB doled out IPO shares.

Before passing on the e-mail, Quattrone amended it. He noted his previous experience as a witness in a securities lawsuit and said that led him to “strongly advise” CSFB employees to follow the bank’s document retention policy which called for routine purging of some records.