Apparatus and method for investigating semiconductors wafer
AssigneeMetryx Limited
InventorRobert John Wilby
Life of this patent
Estimating the term…
Abstract
In order to determine the dielectric constant of a layer deposited on a semiconducotr wafer (2), the density of the layer is obtained. To obtain that density, the wafer (2) without the layer is weighed in a weighing chamber (4) in which a weighing pan (7) supports the wafer on a weighing balance. The weight of the wafer is determined taking into account the buoyancy exerted by the air on the wafer (2). Then the layer is deposited on the wafer (2) and the weighing operation repeated. Alternatively a reference wafer may be used. If the material of the layer is known, the weight of the layer can be used to derive its density using a thickness measurement. Alternatively, if the density is known, the thickness can be obtained.
Claims26
A method for determining a dielectric constant of a layer deposited on a semiconductor wafer, the method comprising the steps of determining the density of the layer and deriving the dielectric constant of the layer from the density of the layer using a predefined relationship between the density and the dielectric constant of the layer.
A method according to any preceding claim wherein the dielectric constant of the material is determined from the density thereof using the following formula:
- 9 ϵ = 2 · α · ρ - ϵ 0 α · ρ - ϵ 0
- where ε is the dielectric constant, ε0 is the permittivity of free space, ρ is the density of the layer and ∝ is a constant for the layer.
An apparatus for determining the dielectric constant of a layer deposited on the surface of a semi-conductor wafer, the apparatus comprising:
- a weighing chamber containing a weighing instrument to weigh a semiconductor wafer, the weighing instrument having means to receive a wafer;
- a temperature sensor, a pressure sensor and a humidity sensor, for monitoring conditions in the weighing chamber;
- and
- a processor to receive measurements from the temperature, pressure and humidity sensors, the processor being arranged to calculate the air-density within the chamber from these measurements, to calculate the buoyancy exerted on the wafer from the calculated air density, to determine the means of the layer, to determine therefrom the density of the layer, and to determine the dielectric constant of the layer from the density of the layer using a predefined relationship between the density and the dielectric constant of the layer.
A method of Statistical Process Control for monitoring the statistical variation in properties of layers deposited on a semiconductor wafer according to one or more manufacturing processes, and for providing a statistical analysis of the accuracy of the processes being carried out, wherein measurement of the mass of said deposited layers is used to provide said statistical analysis.
Dependencies are inferred from the claim text.