Introduction to the Use of Statistical Process Control in Lithography
Notice bibliographique
Résumé
Statistical methods need to be part of every lithographer's toolbox, because lithographic processes contain intrinsic levels of variation. This variation is a consequence of the nature of the world. For example, petroleum is typically the starting material from which photoresists are synthesized, and the composition of crude oil varies from well to well. Lithographic processes and tools are affected by environmental parameters such as barometric pressure and relative humidity, and these factors vary with the weather. Lithography is a manufacturing science implemented and ultimately exercised by human beings, each of whom is a unique individual, different from all others. When people are involved, there is a special element of variation interjected into the process. The analytical methods used by lithography engineers and managers must be capable of dealing with variation in equipment, materials, and people. The objective of any process control methodology is the reduction of variation, in order to maintain conformance to standards or to meet a higher standard. Variations in gate lengths can lead to degraded yield or slower parts, which usually sell for a lower price than faster devices. Higher manufacturing costs result from variation, in the form of scrap, reduced yield, rework, and low equipment utilization. Often there are costs associated with attempts to reduce variation. Since the objective of process control is to maximize profitability, the most effective methods are those which accomplish control in the most cost-effective manner. Indeed, Dr. Walter Shewhart, the inventor of statistical process control, titled his book, Economic Control of Quality of Manufactured Product, with the first word of the title identifying the monetary considerations motivating his methods. Generally, the most economical approaches require that particular levels of variation be tolerated, and the purpose of statistical process control is the identification of variation in excess of the norms of a controlled process. Statistics is the mathematical science for making inferences about quantities which are probabilistic (in contrast to deterministic) in nature. Many statistical methods are therefore applicable only to situations that are random, in which events are independent of each other. A large fraction of the first three chapters of this Tutorial Text will involve the examination of commonly occurring situations in microlithography in which measurements are not independent. The discussion will lead to methods for applying statistical control techniques correctly in such situations.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,004 | 0,011 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,002 | 0,004 |
| Études des sciences et des technologies | 0,001 | 0,006 |
| Communication savante | 0,003 | 0,003 |
| Science ouverte | 0,002 | 0,002 |
| Intégrité de la recherche | 0,003 | 0,006 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,009 | 0,004 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».