# US 9,039,907 B2 · Methods for improving integrated photonic device uniformity

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- Number: US 9,039,907 B2
- Document ID: US9039907B2
- Status: Granted
- Kind: B2
- Application number: 13/552,506
- Filed: 2012-07-18
- Published: 2013-01-24
- Granted: 2015-05-26
- Earliest claimed: 2011-07-20
- Assignees: Imec; Universiteit Gent
- Applicants: Philippe Absil; Shankar Kumar Selvaraja
- Inventors: Philippe Absil; Shankar Kumar Selvaraja
- Web page: https://patentgrep.com/patent/US9039907B2

## CPC

- G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- H10P 74/23: {characterised by multiple measurements, corrections, marking or sorting processes}
- G01B 2210/56: Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

A method is described for improving the uniformity over a predetermined substrate area of a spectral response of photonic devices fabricated in a thin device layer. The method includes (i) establishing an initial device layer thickness map for the predetermined area, (ii) establishing a linewidth map for the predetermined area, and (iii) establishing an etch depth map for the predetermined area. The method further includes, based on the initial device layer thickness map, the linewidth map and the etch depth map, calculating an optimal device layer thickness map and a corresponding thickness correction map for the predetermined substrate area taking into account photonic device design data. Still further, the method includes performing a location specific corrective etch process in accordance with the thickness correction map.

## Claims

### Claim 1

A method for improving the uniformity over a predetermined substrate area of a spectral response of photonic devices fabricated in a device layer of a Silicon-On-Insulator substrate, wherein the device layer of the Silicon-On-Insulator substrate is a silicon device layer on a silicon dioxide layer, the method comprising:
before fabrication of the photonic device structures in the device layer of the Silicon-On-Insulator substrate,
(i.) establishing an initial device layer thickness map for the predetermined area;
(ii) establishing an anticipated linewidth map for the predetermined area, wherein establishing the anticipated linewidth map comprises establishing, based at least on previously-collected process control data from optical lithography and from dry etching, an anticipated linewidth as a function of spatial wafer coordinates in the predetermined area;
(iii) establishing an anticipated etch depth map for the predetermined area, wherein establishing the anticipated etch depth map comprises establishing, based at least on previously-collected process control data from optical lithography and from dry etching, an anticipated etch depth as a function of spatial wafer coordinates in the predetermined area;
(iv) based at least on the initial device layer thickness map, the anticipated linewidth map and the anticipated etch depth map, calculating (i) an optimal device layer thickness map for matching a predetermined spectral response of a photonic device and (ii) a corresponding thickness correction map for the predetermined substrate area taking into account photonic device design data; and
(v) performing a location specific corrective etch process in accordance with the thickness correction map.

### Claim 2 (depends on 1)

The method of claim 1, wherein establishing the initial device layer thickness map comprises measuring the initial thickness of the device layer over the predetermined substrate area as a function of x and y, where x and y are spatial wafer coordinates.

### Claim 3 (depends on 2)

The method of claim 2, wherein measuring the initial thickness of the device layer comprises measuring by spectroscopic ellipsometry.

### Claim 4 (depends on 2)

The method of claim 2, wherein measuring the initial thickness of the device layer is performed with an accuracy better than 1 nanometer (nm).

### Claim 5 (depends on 1)

The method of claim 1, wherein calculating the optimal device layer thickness map comprises calculating, as a function of spatial wafer coordinates, an optimal device layer thickness needed for matching the predetermined spectral response of the photonic device.

### Claim 6 (depends on 1)

The method of claim 1, wherein determining the thickness correction map comprises calculating a difference between the optimal device layer thickness and the initial device layer thickness as a function of spatial wafer coordinates, wherein the difference corresponds to the thickness correction to be performed by the location specific corrective etch process.

### Claim 7 (depends on 1)

The method of claim 1, wherein the location specific corrective etch process is a Gas Cluster Ion Beam process.

### Claim 8 (depends on 1)

The method of claim 1, further comprising performing a second location specific corrective etch process after fabrication of the photonic device structures in the device layer of the Silicon-On-Insulator substrate.