DD285436A5

DD285436A5 - METHOD AND DEVICE FOR LATERAL AND VERTICAL LAYER THICKNESS CONTROL

Info

Publication number: DD285436A5
Application number: DD33005989A
Authority: DD
Inventors: Dietmar Krueger; Rainer Kurps; Georg Riepel
Original assignee: Veb Halbleiterwerk Kombinat Mikroelektronik,Dd
Priority date: 1989-06-28
Filing date: 1989-06-28
Publication date: 1990-12-12

Abstract

Verfahren und Vorrichtung zur lateralen und vertikalen Schichtdickenkontrolle fuer die Fertigungskontrolle von Halbleiterbauelementen, insbesondere auf Siliziumbasis, die ganzflaechig oder lateral selektiv p-n- und/oder l-h-UEbergaenge aufweisen. Aufgabe ist die Bestimmung lateraler und vertikaler Abstaende im Bereich von einigen 10 nm bis zu einigen 10 mm mit einem maximalen relativen Fehler * Die erfindungsgemaesze Loesung besteht in der selektiven anodischen Oxidation mit Brauchwasser als Elektrolyt, wobei p-n-UEbergaenge in Fluszrichtung, n-p-UEbergaenge in Sperrichtung betrieben den Volumengleichgewichtswert der jeweiligen UEbergaenge abbilden. Der nach Oxidabloesung, insbesondere nach mehrfacher anodischer Oxidation in steigender Qualitaet mikroskopisch oder profilometrisch auswertbare topografische Kontrast ist eine weitere Auswertbasis.{Schichtdickenkontrolle, vertikal, lateral; Halbleiterbauelemente; anodische Oxidation; selektiv}Method and apparatus for lateral and vertical layer thickness control for the production control of semiconductor devices, in particular silicon-based, which have ganzflaechig or laterally selective p-n and / or l-h-UEbergaenge. The task is the determination of lateral and vertical distances in the range of a few 10 nm to a few 10 mm with a maximum relative error * The inventive solution consists in the selective anodic oxidation with hot water as the electrolyte, wherein pn-UEbergaenge in the flow direction, np-UEbergaenge in Operated reverse lock represent the volume balance value of the respective UEbergaenge. The topographical contrast that can be evaluated microscopically or profilometrically after oxidative dissolution, in particular after multiple anodic oxidation in increasing quality, is another evaluation basis. {Layer thickness control, vertical, lateral; Semiconductor devices; anodic oxidation; selectively}

Description

fehlerbehaftete Schrägschliffe werden durch eine wiederholte Folge selektiv Oxidation-Oxidablösung gebessert, wobei gleichzeitig ein optisch und/oder profilometrisch mit steigender Behandlungsfolge immer besser auswertbares Oberflächenrelief entsteht. Es wurde festgestellt, daß p-n-Übergänge in Flußrichtung, n-p-Übergänge in Sperrichtung gepolt, innerhalb eines experimentell zu prüfenden Zeilspannungsintervalls die reale Lage des betreffenden Überganges, d. h. den Volumengleichgewichtswert, widerspiegeln, während bei umgekehrter Polung der durch Oberflächenladung verfälschte Meßwert bestimmbar ist. Gleiches gilt für die, aus den selektiven Oxidationsprozessen folgenden, nach Oxidablösung sichtbaren bzw. profilometrisch erfaßbaren topografischen Effekte, die die Bestimmung der Lage von Übergängen z.B. mittels Winkel-Längen-Meßmethodik gestatten.Erroneous oblique cuts are improved by a repeated sequence of selective oxidation-oxide dissolution, wherein at the same time an optically and / or profilometrically formed with increasing treatment successes better evaluable surface relief. It has been found that p-n transitions in the flux direction, n-p transitions in the reverse direction poled, within an experimentally tested Zeilspannungsintervalls the real position of the transition in question, d. H. reflect the volume equilibrium value, while in reverse polarity the measured value corrupted by surface charge can be determined. The same applies to the topographical effects that can be detected after oxide removal or that can be detected profilometrically from the selective oxidation processes and that are used to determine the position of transitions, e.g. allow by means of angle-length measuring method.

Der Oberflächenschutz der Proben kann entweder durch prozeßtypisch vorhandene Dotantengläser oder auch durch bei T < 600⁰C abscheidbare Isolatorschichten realisiert werden. Die Metallisierungsstruktur wirkt sich nicht störend auf die Erreichbarkeit der dargelegten Ergebnisse aus.The surface protection of the samples can be realized either by process typical existing Dotantengläser or by T <600 ⁰ C depositable insulator layers. The metallization structure does not interfere with the accessibility of the results presented.

embodiment The invention will be explained below with reference to the embodiments.

1. Eine mit Phosphorsilikatglas passivierte, ganzflächig mittels Phosphor diffundierte schräggeschliffene Probe mit den Abmessungen 20mm χ 5mm und der Dicke von etwa 400pm wird, von der diffundierten Seite her ohmisch kontaktiert, anodisch mit U^, = 80V 4 Minuten in einer elektrolytischen Anordnung mit Brauchwasser als Elektrolyt belastet. Optimale Ergebnisse der selektiven Oxidation werden bei minimalem Abstand Katode-Anode erreicht. Die Beleuchtungsstärke beträgt 5CX)Ix. Katode und Siliziumprobenkontakt sind aus Platin gefertigt. Die Stromstärke, die zu Belastungsbeginn 4OmA betrug, ist nach 4 min stetig auf 8 mA gefallen. Der Übergang zum p-Substrat ist mikroskopisch durch Farbkontrast, nach Ablösen der Phosphorglas- und anodischen Oxidschicht mittels Flußsäure durch Topografiekontrast auswertbar.1. Passivated with Phosphorsilikatglasierte, all over phosphorus diffused oblique ground sample with the dimensions of 20mm χ 5mm and the thickness of about 400pm, ohmisch contacted from the diffused side, anodic with U ^, = 80V 4 minutes in an electrolytic arrangement with hot water loaded as electrolyte. Optimal results of selective oxidation are achieved with minimum cathode anode spacing. Illuminance is 5CX) Ix. Cathode and silicon sample contact are made of platinum. The current, which was 4OmA at the beginning of the load, dropped steadily to 8 mA after 4 min. The transition to the p substrate is microscopically evaluated by color contrast, after detachment of the phosphorus glass and anodic oxide layer using hydrofluoric acid by topography contrast.

2. Eine schräggeschliffene Siliziumprobe, die n-p-n/n+-Transistorstrukturen enthält, wird der gemäß Beispiel 1 formulierten Belastung unterzogen. Infolge Fehlerhaftigkeit der Schliffpräparation ist es notwendig, die Folge anodische Oxidation/ Oxidablösung viermal zu wiederholen. Im Ergebnis sind im anodischen Qxidbild, bedingt durch die lokal selektive Oxidationsrate, der Emitter-Basis-, der Basis-Kollektor-Übergang einschließlich des vorhandenen Emitter-Dips und der n/n⁺-Übergang einschließlich der Ausdiffusionszone aus dem n⁺-Substrat sichtbar.2. An obliquely ground silicon sample containing npn / n + transistor structures is subjected to the stress formulated in Example 1. Due to the defectiveness of the grinding preparation, it is necessary to repeat the sequence of anodic oxidation / oxide detachment four times. As a result, in the anodic oxide image, due to the locally selective oxidation rate, the emitter-base, base-collector junction including the existing emitter dips, and the n / n ⁺ junction including the outdiffusion zone are visible from the n ⁺ substrate ,

Die durch die genannte Präparationsfolge anodische Oxidation/Oxidablösung entwickelbaren und stufenweise verbesserungsfähigen topografischen Effekte weisen die bereits im selektiven Oxidbild genannten Details aus, die wahlweise meßmikroskopisch oder profilometrisch auswertbar sind.The topographical effects which can be developed by means of the aforementioned preparation sequence anodic oxidation / oxide detachment and which can be gradually improved have the details already mentioned in the selective oxide image, which can be evaluated either by measurement microscopy or profilometrically.

3. Eine schräggeschliffene, ganzflächig einer Bor-Diffusion unterzogene Siliziumprobe vom η-Typ wird anodisch in einer aus Platin-Katode und Brauchwasser bestehenden elektrolytischen Anordnung belastet, wobei der ohmsche Probenkontakt mittels Platin auf der bordiffundierten Seite nach partieller Ablösung des Borsilikatglases, unter Umständen mit Hilfe von Reibelot realisiert ist.3. An obliquely ground, a boron-diffused silicon sample of the η-type is anodically loaded in an existing platinum cathode and service water electrolytic arrangement, the ohmic sample contact by means of platinum on the bordiffundierten side after partial detachment of borosilicate glass, possibly with Help from Reibelot is realized.

Claims

1. A method for the lateral and vertical layer thickness control of pn or np transitions and / or dopant outdiffusion regions and / or Iow-high zone sequences, possibly grain dined with intrinsic regions, for the exclusion and identification of falsifying surface effects, in particular in obliquely ground Si samples by selective anodic oxidation, wherein the sample surface is fully or laterally selectively protected by anodic oxidation resistant layers, characterized in that the beveled silicon samples are ohmically contacted by platinum contact and anodic, to exclude the surface corrupted readings at pn transitions with applied flux voltage of 25 V to 400 V, with np-transitions with applied blocking voltage of 25 V to 400 V, and to indicate the surface-falsified measured values, the selective anodic oxidation on reversal of the load in the flow or blocking direction, simultaneously g is the action of polychromatic light 30sec to 20min with illuminances between 30Ix and 600Ix in the temperature interval 0 ^c CT80 ^o C, then the resulting by the excessive selective oxidation rate after oxide dissolution topography contrast is evaluated by light microscopy or profilome'crisch.

2. The method according to claim 1, characterized in that the electrical load and the illumination pulse-shaped in the frequency range of 3Hz to 15Hz.

3. Apparatus for lateral and vertical layer thickness control by means of anodic oxidation, characterized in that as the electrolyte of service water, as the cathode platinum and the anode is arranged by means of platinum ohmically contacted Si sample.

Field of application of the invention

The invention relates to a method and a device for controlling the vertical and / or lateral extent of zones in semiconductor components and / or control disks based on silicon, the n-p or p-n junctions and / or low-high zone sequence. U. combined with intrinsic areas, contained individually or in combination.

Characteris ' Jk of the known state of the art

Dia known, essentially oblique-grounding routine methods are described in a paper by S.M. Hu in J. Appl. Phys. 53 (3) March 1982 pp. 1499-1510 subjected to a fundamental criticism. The essential statement is that the electronic effectiveness of the sample preparation, in particular of the oblique cut, strongly depends on the position of the ζ. β. detect by means of staining or propagation resistance technique transitions, so that significantly deviating from the volume value, surface-distorted measured values are determined. This thus physically conditioned contradiction can not be solved, as formulated in WP 226693, by polarity of the electrolytically to be decorated transitions in the forward direction.

Object of the invention

The goal is the development of a routinely feasible with little effort methodology for determining the lateral and / or vertical position of pn, np and Iow-high zone sequences, which may contain intrinsic areas to ensure the controllability of production by the obtained measurement results ,

Explanation of the essence of the invention

The object of the invention is to ensure maximum errors <± 2.5% for lateral and vertical dimensions of a few 10 nm to about 20 μm zone sequences of the type mentioned with exclusion or identification of adulterant surface charge effects, and the transitions with a reproducibility error 1%, preferably 0.1% to measure. At the same time, the width of the z. B. identify by thermal stress of Iow-high transitions forming transition zones. According to the invention, the object is achieved as follows.

Slant-ground silicon samples containing the aforementioned zone sequences individually or in combination are ohmically contacted by means of platinum pressure contacts and connected anodically in an electrolytic arrangement consisting of platinum cathode and process water as the electrolyte. During a time of 30 scc to 20 min, the action of polychromatic light with an illuminance of 300Ix to 600Ix in the temperature range of 0 ⁰ C <T <80 ⁰ C at a cell voltage of 25V <U <400V, preferably in the range 25 <U <100V oxidized selectively laterally and vertically. The pulsating electrical and light-optical load in a frequency range of 3Hz <f <15Hz is in most cases, especially with larger sample geometry, of distribution. By means of profilometer it was found that the oxidation rate has a maximum directly at the pn junction. After oxide dissolution appears in its places according to a pit-like depression. Reale