# US 2019/0378689 A1 · Method and Apparatus for the Planarization of Surfaces

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- Number: US 2019/0378689 A1
- Document ID: US20190378689A1
- Status: Published application
- Kind: A1
- Application number: 16/004,939
- Filed: 2018-06-11
- Published: 2019-12-12
- Earliest claimed: 2018-06-11
- Assignees: FEI Company
- Applicants: FEI Company
- Inventors: Philip BRUNDAGE; Zachary KLASSEN; Chad RUE
- Web page: https://patentgrep.com/patent/US20190378689A1

## CPC

- G01N 1/286: {involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising (microtomes G01N1/06; pulverising in general B02C; mixing in general B01F)}
- H10P 50/242: {of Group IV materials}
- C23F 4/00: Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
- G01N 1/32: Polishing; Etching
- H01J 37/3056: {for microworking, e. g. etching of gratings or trimming of electrical components}
- H01J 37/20: Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
- H01J 2237/20228: Mechanical X-Y scanning
- H01J 2237/3174: Etching microareas
- H01J 2237/31745: for preparing specimen to be viewed in microscopes or analyzed in microanalysers
- H01J 2237/31749: Focused ion beam
- 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
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Techniques for planarizing surfaces are disclosed herein. One example includes orienting a surface of a sample to a charged particle beam axis, the sample including a first layer formed from first and second materials, the first material patterned into a plurality of parallel lines and disposed in the second material, where the surface is oriented to form a shallow angle with the charged particle beam axis and to arrange the plurality of parallel lines perpendicular to the charged particle beam axis, providing a charged particle beam toward the surface, providing a gas to the surface, and selectively etching, with ion induced chemical etching, the second material at least down to a top surface of the first material, the charged particle induced etching stimulated due to concurrent presence of the charged particle beam and the gas over the surface of the sample.

## Claims

### Claim 1

A method comprising;
orienting a surface of a sample to a charged particle beam axis, the sample including a first layer, the first layer formed from first and second materials, the first material different than the second material and patterned into a plurality of parallel lines that are disposed in the second material, wherein a top surface of the second material forms the surface, and wherein the surface is oriented to form a shallow angle with the charged particle beam axis and to arrange the plurality of parallel lines so that a long side of the plurality of parallel lines extends across the charged particle beam axis;
providing a charged particle beam along the charged particle beam axis toward the surface of the sample;
providing a gas to the surface of the sample; and
selectively etching, with ion induced chemical etching, the second material at least down to a top surface of the first material, the charged particle induced etching stimulated due to concurrent presence of the charged particle beam and the gas over the surface of the sample.

### Claim 2 (depends on 1)

The method of claim 1, wherein the plurality of parallel lines forms a shadow mask to the charged particle beam.

### Claim 3 (depends on 1)

The method of claim 1, wherein a distance between adjacent parallel lines of the plurality of parallel lines determines a degree of the shallow angle.

### Claim 4 (depends on 3)

The method of claim 3, wherein the degree ranges from 1 degree to 38 degrees, the shallow angle measured from the charged particle beam axis and the surface of the sample.

### Claim 5 (depends on 3)

The method of claim 3, wherein the degree of the shallow angle is inversely related to the distance between adjacent parallel lines of the plurality of parallel lines.

### Claim 6 (depends on 1)

The method of claim 1, wherein providing a charged particle beam includes providing the charged particle beam at a low energy and at a low pattern beam density.

### Claim 7 (depends on 6)

The method of claim 6, wherein the low energy includes providing the charged particle beam at a voltage in a range of 0.5 KeV to 30 Kev.

### Claim 8

(canceled)

### Claim 9 (depends on 6)

The method of claim 6, wherein the low pattern beam density is in a range of 0.1 pA/um2 to 1 pA/um2.

### Claim 10 (depends on 1)

The method of claim 1, wherein the gas is an etchant gas.

### Claim 11 (depends on 10)

The method of claim 10, wherein the etchant gas is selected from one of Xenon difluoride, chlorine, iodine, bromine, nitrous oxide, oxygen, water, fluorine, trifluoroacetate acid, trifluoroacetamide, methyl nitro acetate, and acetic anhydride, and combinations thereof.

### Claim 12 (depends on 10)

The method of claim 10, wherein the etchant gas preferentially etches the second material over the first material.

### Claim 13 (depends on 1)

The method of claim 1, wherein the second material is a dielectric.

### Claim 14 (depends on 13)

The method of claim 13, wherein the dielectric is one of silicon oxide, silicon dioxide, silicon nitride, silicon carbide, polyimide and combinations thereof.

### Claim 15 (depends on 1)

The method of claim 1, wherein the first material is metal.

### Claim 16 (depends on 1)

The method of claim 1, wherein the sample is a semiconductor chip.

### Claim 17 (depends on 1)

The method of claim 1, wherein the sample is a transmission electron microscope (TEM) lamella.

### Claim 18 (depends on 1)

The method of claim 1, wherein a dwell time of the charged particle beam at locations on the surface is short.

### Claim 19 (depends on 17)

The method of claim 17, wherein the dwell time is in a range of 25 to 300 nanoseconds.

### Claim 20 (depends on 1)

The method of claim 1, wherein the sample surface is planarized due to charged particle beam induced selective etching of the second material over the first material, and further based on the plurality of parallel lines providing a shadow mask to the ion beam.

### Claim 21 (depends on 1)

The method of claim 1, further comprising:
spin milling a remainder of the first layer and a portion of a second layer disposed under the first layer, the remainder of the first layer including the first and second materials; and
planarizing the second layer down to a top surface of metal lines of the second layer, the second layer including third and fourth materials, wherein planarizing the third surface comprises:
orienting an exposed surface of the sample to the ion beam axis to form the shallow angle with the ion beam axis and to arrange metal lines formed of the fourth material normal to the ion beam axis;
providing the gas to the exposed surface of the sample;
providing the ion beam to the exposed surface at a low energy and at a low pattern beam density; and
based on the presence of the gas and the ion beam, stimulating ion beam induced etching of the third material.