STOCK BASED COMPENSATION - Stock-based compensation expense (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | |||
| Stock-based compensation expense | $ 2,888 | $ 2,890 | $ 3,208 |
| Cost of revenues | |||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | |||
| Stock-based compensation expense | 121 | 347 | 360 |
| Research and development | |||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | |||
| Stock-based compensation expense | 2,022 | 2,045 | 1,873 |
| Sales, general and administrative | |||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | |||
| Stock-based compensation expense | $ 745 | $ 498 | $ 975 |