Method for testing group III-nitride wafers and group III-nitride wafers with test data
AssigneeSixPoint Materials, Inc.
InventorsTadao Hashimoto, Masanori Ikari, Edward Letts
Life of this patent
Estimating the term…
Abstract
The present invention discloses a new testing method of group III-nitride wafers. By utilizing the ammonothermal method, GaN or other Group III-nitride wafers can be obtained by slicing the bulk GaN ingots. Since these wafers originate from the same ingot, these wafers have similar properties/qualities. Therefore, properties of wafers sliced from an ingot can be estimated from measurement data obtained from selected number of wafers sliced from the same ingot or an ingot before slicing. These estimated properties can be used for product certificate of untested wafers. This scheme can reduce a significant amount of time, labor and cost related to quality control.
Claims23
A certified Group III-nitride wafer comprising (i) a documentation of a value of a physical property in combination with (ii) a wafer from a first set of Group III-nitride substrates cut from an ingot formed using a seed material, wherein the value of the physical property is derived by a method comprising
- a) selecting substrates from the first set of substrates to form a second set of substrates, the second set of substrates being a subset of the first set and therefore being a selection of substrates from the first set of substrates that does not include all members from the first set of substrates, the second set of substrates having at least one substrate selected from the substrates cut from a portion of the ingot located on one side of a seed used to form the ingot, and the second set of substrates having at least one substrate selected from the substrates cut from a second portion of the ingot located on the other side of the seed,
- b) analyzing samples taken from the substrates of the second set to assess values of a first property of each of the substrates of the second set,
- c) determining a correlation for the values of the first property, said correlation being a function of distance of each of said substrates of the second set from the seed used to form the ingot, and either
- i) applying said correlation to substrates not in said second set of substrates to provide estimated values of said first property for said substrates;
- or
- ii) comparing said correlation against a value of said property for the seed material to assess whether said value of the property for the seed material can be used as an estimate of the property for wafers cut from the ingot, and providing said value of the property for the seed material as the value of the property for said wafers.
Dependencies are inferred from the claim text.