# US 7,608,549 B2 · Method of forming non-conformal layers

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- Number: US 7,608,549 B2
- Document ID: US7608549B2
- Status: Granted
- Kind: B2
- Application number: 11/375,588
- Filed: 2006-03-13
- Published: 2007-02-01
- Granted: 2009-10-27
- Earliest claimed: 2005-03-15
- Assignees: ASM America, Inc.
- Inventors: Sebastian E. Van Nooten; Jan Willem Maes; Steven Marcus; Glen Wilk; Petri Räisänen; Kai-Erik Elers
- Web page: https://patentgrep.com/patent/US7608549B2

## CPC

- H01J 37/32082: {Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence)}
- C23C 16/045: {Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates}
- C23C 16/403: {of aluminium, magnesium or beryllium}
- C23C 16/448: characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials
- C23C 16/45519: {Inert gas curtains}
- C23C 16/45525: {Atomic layer deposition [ALD]}
- C23C 16/45542: {Plasma being used non-continuously during the ALD reactions}
- C23C 16/45565: {Shower nozzles}
- C23C 16/50: using electric discharges {(generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34)}
- C23C 16/5096: {Flat-bed apparatus}
- C23C 16/52: Controlling or regulating the coating process {(C23C16/45557, C23C16/279 take precedence)}
- H01J 37/3244: {Gas supply means}
- H01J 37/32935: {Monitoring and controlling tubes by information coming from the object and/or discharge}
- H10D 1/047: {of conductor-insulator-semiconductor capacitors, e.g. trench capacitors}
- H10P 14/69391: {the material containing aluminium, e.g. Al2O3}
- H10P 14/6336: {in the presence of a plasma [PECVD]}
- H10P 14/6339: {deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD}
- H10P 14/69215: {the material being a silicon oxide, e.g. SiO2}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

In one aspect, non-conformal layers are formed by variations of plasma enhanced atomic layer deposition, where one or more of pulse duration, separation, RF power on-time, reactant concentration, pressure and electrode spacing are varied from true self-saturating reactions to operate in a depletion-effect mode. Deposition thus takes place close to the substrate surface but is controlled to terminate after reaching a specified distance into openings (e.g., deep DRAM trenches, pores, etc.). Reactor configurations that are suited to such modulation include showerhead, in situ plasma reactors, particularly with adjustable electrode spacing. In another aspect, alternately and sequentially contacting a substrate, the substrate including openings, with at least two different reactants, wherein an under-saturated dose of at least one of the reactants has been predetermined and the under-saturated dose is provided uniformly across the substrate surface, deposits a film that less than fully covers surfaces of the openings, leading to depletion effects in less accessible regions on the substrate surface.

## Claims

### Claim 1

A method for depositing a film on a semiconductor substrate, the method comprising:
providing a substrate with a surface comprising regions with different levels of accessibility;
providing a sequence of at least two different reactants in temporally separated and alternating reactant pulses, wherein at least one of the at least two different reactants is provided through a showerhead or otherwise provided in that it impinges vertically on the substrate;
selecting plasma-enhanced atomic layer deposition (PEALD) conditions to achieve self-satuaration and self-limiting atomic layer deposition (ALD) mode deposition on the most accessible regions on the substrate surface and depletion effects in less accessible regions on the substrate surface; and
exposing the semiconductor substrate to the sequence of the reactant pulses with the selected temporal separations and durations to deposit the film.

### Claim 2 (depends on 1)

The method of claim 1, wherein the regions comprise top surface regions.

### Claim 3 (depends on 2)

The method of claim 2, wherein the regions further comprise trench regions that are less accessible than the top surface regions.

### Claim 4 (depends on 2)

The method of claim 2, wherein the regions comprise pore regions that are less accessible than the top surface regions.

### Claim 5 (depends on 1)

The method of claim 1, wherein the substrate comprises a DRAM trench and the film comprises a collar extending only partially from a top surface of the substrate into the trench.

### Claim 6 (depends on 1)

The method of claim 1, wherein selecting PEALD conditions comprises tuning at least one parameter selected from the group consisting of RF power on-time, RF power amplitude, frequency, reactant concentration, chamber pressure, total gas flow, reactant pulse durations and separations, and RF electrode spacing.

### Claim 7 (depends on 1)

The method of claim 1, wherein providing a sequence of at least two different reactants in temporally separated and alternating reactant pulses comprises providing one reactant continuously and intermittently pulsing plasma power.

### Claim 8

A method of controlling conformality of a deposited film on a semiconductor substrate, the method comprising:
providing a substrate with a plurality of openings at a surface thereof
alternately and sequentially supplying pulses of at least two different reactants to the substrate; and
selectively activating at least one of the two different reactants in pulses, wherein selectively activating is controlled to have a depletion effect within the openings to less than fully cover surfaces of the openings.

### Claim 9 (depends on 8)

The method of claim 8, wherein conformality of a deposited film is reduced in a controlled manner.

### Claim 10 (depends on 8)

The method of claim 8, wherein selectively activating comprises activating a plasma within a deposition chamber directly over the surface.

### Claim 11 (depends on 10)

The method of claim 10, wherein selectively activating comprises supplying the at least one of the reactants through a showerhead having openings extending across the substrate in face-to-face relation with the substrate.

### Claim 12 (depends on 11)

The method of claim 11, wherein selectively activating comprises applying a first polarity to the showerhead and a second polarity to the substrate.

### Claim 13 (depends on 12)

The method of claim 12, wherein the second polarity is ground.

### Claim 14 (depends on 8)

The method of claim 8, wherein alternately and sequentially supplying pulses comprises supplying pulses of a first reactant, supplying a continuous feed of a second reactant, and selectively activating comprises pulsing plasma power to the second reactant between pulses of the first reactant.

### Claim 15 (depends on 8)

The method of claim 8, wherein alternately and sequentially supplying pulses comprises alternating pulses of a first reactant with pulses of a second reactant, and selectively activating comprises pulsing plasma power during only portion of each pulse of the second reactant.

### Claim 16 (depends on 8)

The method of claim 8, wherein the at least one of the two different reactants comprises a species non-reactive with the other of the two different reactants under deposition conditions in the absence of the selective activation.

### Claim 17 (depends on 16)

The method of claim 16, wherein the at least one of the two different reactants comprises O2.

### Claim 18 (depends on 16)

The method of claim 16, wherein the at least one of the two different reactants comprises N2.

### Claim 19 (depends on 8)

The method of claim 8, wherein selectively activating comprises tuning at least one parameter selected from the group consisting of RF power on-time, RF power amplitude, frequency, reactant concentration, chamber pressure, total gas flow and RF electrode spacing.

### Claim 20 (depends on 8)

The method of claim 8, wherein the openings comprise DRAM trenches and the deposited film comprises an insulating collar extending from the surface of the substrate into the trenches.

### Claim 21 (depends on 8)

The method of claim 8, wherein the deposited film comprises a section having an end proximal to the substrate surface having a thickness greater than 90% of a thickness of the deposited layer at the substrate surface, the section having an end distal from the substrate surface having a thickness less than 10% of a thickness of the deposited layer at the substrate surface, the section having a length between the ends of less than about 1.0 μm.

### Claim 22 (depends on 21)

The method of claim 21, wherein the section has a length between the ends of less than about 0.5 μm.

### Claim 23 (depends on 8)

The method of claim 8, wherein the openings comprise trenches and pores in an insulating layer.

### Claim 24 (depends on 23)

The method of claim 23, wherein the deposited film extends no more than about 3 pore depths into the insulating layer.

### Claim 25 (depends on 8)

The method of claim 8, wherein the deposited film is an insulator.

### Claim 26 (depends on 8)

The method of claim 8, wherein the deposited film is a conductor.