SK Hynix has reached a tentative wage agreement with its labor union to pay most of its workers' special bonuses with shares.

The South Korean memory-chip maker said Thursday it agreed with its labor union that 40% of workers' special bonuses will be paid in cash and 60% in shares. Both sides also agreed to a 6.3% pay increase and an improved welfare perks for workers.

SK Hynix had agreed to allocate 10% of its operating profit to special bonuses last year, and Thursday's announcement sets out how the bonuses will be paid.

There will be a lock-up period for some of the shares received by workers, with 40% of the total bonus sellable this year, 10% after one year and the remaining 10% after two years, according to the deal.

The preliminary agreement is subject to approval via a vote by union members.