SK Hynix's union members have voted down a tentative wage deal to pay the bulk of special bonuses--designed to share surging profit--in shares rather than cash.

The deal reached last week at the South Korean memory-chip maker narrowly failed to win majority approval in a union vote that ended Tuesday, with 49.92% of voting members in favor, state news agency Yonhap said.

The voting outcome would bring both union and management representatives back to the negotiating table, according to Yonhap.

SK Hynix officials weren't immediately available for comment.

Under the preliminary agreement, 40% of workers' special bonuses would be paid in cash and 60% in shares, some of which would be subject to a lock-up period.

SK Hynix last year agreed to allocate 10% of its operating profit to special bonuses.

Both union and management negotiators also agreed to a 6.3% pay increase and improved welfare benefits for workers under the recent agreement.