The changes in the carrying amount of goodwill for the year ended September 30, 2021 are as follows (in thousands):


	Semiconductor		Material and Substrate		Net Goodwill
Goodwill	$	5,905	$	728	$	6,633
Accumulated impairment losses		—		—		—
Balance at September 30, 2020		5,905		728		6,633
Goodwill acquired during 2021		—		4,535		4,535
Impairment of goodwill		—		—		—
Balance at September 30, 2021	$	5,905	$	5,263	$	11,168
Goodwill	$	5,905	$	5,263	$	11,168
Accumulated impairment losses		—		—		—
Balance at September 30, 2021	$	5,905	$	5,263	$	11,168

On March 3, 2021, we acquired Intersurface Dynamics, which has been integrated into our Material and Substrate segment. Under the purchase method of accounting, the purchase price for the acquisition was allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values. The excess purchase price over fair value of net assets acquired of approximately $4.5 million was recorded as goodwill in the Material and Substrate segment. The primary driver for this acquisition was to bolster our offerings in the substrate consumables space and incorporate wafer processing coolants and chemicals to our existing consumable and machine product lines.

During 2021, we periodically assessed whether any indicators of impairment existed which would require us to perform an interim impairment review. As of each interim period end during fiscal 2021, we concluded that a triggering event had not occurred that would more likely than not reduce the fair value of our reporting units below their carrying values. We performed our annual test of goodwill for impairment during the fourth quarter of 2021. The results of the goodwill impairment test indicated that the fair values of our Semiconductor and Material and Substrate reporting units were in excess of the carrying values, and, thus, we did not require an impairment charge. While the quantitative analysis indicated no impairment of Semiconductor and Material and Substrate segment goodwill existed as of September 30, 2021, if the future performance of these reporting units fall short of our expectations or if there are significant changes in operations due to changes in market conditions, we could be required to recognize material impairment charges in future periods.